DEIERMI}IAÏI$¡ OF GOtÐ TOSSES M Tffi

FTRE ASSÁY ¡ÍETITCD

Sfegfrfed Gerhard Walt

- A thesis subnitËed fn conformfcy wlth the requfrenenËs for the degree of Doctor of phllo:sopby at

the Unl,versfÈy of ManLÈoba

August 1972 TABTÆ ÛF CO¡{TMqTS

Page

ABSI3ACT o oø ø o o @o @ o e øøø øø @ ø ø ø e 6 ø ø ô o ô ø o @ o o ø o € o o os o o o o o@ f

An Orfgl.ns @f, the Flre Assay .oeooøø.êøooøøø@@øoeø@øG n

B" Tbg Ffrg Assay Mgthod øøo6øoøo6@oeøooooooo øooo.ø@@ 5

T. Fusf.on 6øøêøeêøøëcoeeoaê@ooøøøø6øøcoøoooooooo 5

TI" Cupel,lati,on @øøo.øô@êoo'Þoô.soc. ¡o'ee o@èøøøøø I

lII" ParËl'ng .ooooc .øo.6.cooø oøøøøøaêêøøøøøoøøøøø 3.0

Lz IV" Analysfs " øoø@øoôoeo øøoê6oøøøøøøøaøs.øoo øcøoø

Cr GoX.d tossêS ooøøoøe@oøo@øo@øø6ê6oëøêøoøø6eoøøøêø@" 14

Ð, ExperlurenËalu ResuXts and DLseuesåon "oooêooo øøøøø 2L I" EqulpmenË and Reagents .,aøøèøøøøøøøø@eaøøøøø ZL

Ir ApparaÈug ø ø ø ø @ @ ø ô ø @ @ ø ø @ e e @ ø ø ø ø ø @ ø ø @ê ø ê ø. 2L

2t Reagent,s oooóeo@ooo @'êøøao@oo øø6êø@a@@ø@ø 2L

3' SÈandard Solutfons @øø@@oe@øo oooø@@@øø@eø 2t

IT" Genera& ConsådgraËions ooøøo øøøoøøøøø@aøøøø. 22

Lo ReJeetlon of dlscordant resules ,øooooooâ 22

2. lÍelghing proegdure aoø6ooøe ,@oo,oo'ooøoôo 23

IIT. Cu¡lel,lation and Pantfng losses øøøøaøøøêø@ø 23

lntrodugËlon . èaøoøøøqocooooø êoøeooooô.oooo 23 X" Effeet of Lead Welght on Cupel.latf@n

Lossgs of goLd øøøøeooooøøooooêooeooo¿oo, 27

2. Effeer of SLlver t@ [email protected] RaÊLo on

Cupe1lacl@n L@sses of GoX,d øøøøøøêø@eøø@@ 37

3" Effeet of ParËlng Froeedutre @n GoX.d l"osses 38

t4" VolatfX{,zatLon o@océooosô øøøøøø@ø.øÒ@ø@@" 56

5" Effget of Cleaníng Eeads øoooeøøøøøøøøøø" 63 IV" Losses of GoLd Ln Ehe Cornpn"eee Fire Assay ' " 65 [, E€feet of Mlxlag Froeedure of Ore ar¡d FXux 65 2, Effeet of Fusfon Temperature on Gotd Lossea 67 3" Effeet of Lead BuËËon I'Ieight on Gold Losses 78

4" Effeet of Fuslon Tlme on GoX.d l"oss€s o u'o 83 5, Effeet of CupetX.atfon TemperaËure on Gotd

Lossgs oaøooooooo oøøøø ooootéorocoooo 92

98 6" Effggt of a Covgf 'noc.oo@ øaø@ooøoøøooêøø 7. Mfscel,X,aneous Consldgracíons "e" oêøøøøøoø 98 a) Effeet of TernperaÈure on PereenËage

Sllver ReËafned by Geld Beads 98

b) SurehaEge @@øooe ø ø ø ø @ @ ø 6 o øo o esa @ @ @ @ @ ø @ &01

V, Appl{eatføn and ENËensLon ef OpÊfmrm Assay

Procedures Ë@ Uierogram Sløed Sæples øøëøøø@ å03

104 1' SËandard Geld $æples " ø@@øøooooo oø@@oøøø

2o GoLd Orgs øooøcøøøøsêoooo eøøø@oo.eooo@oøø x.08 VI, Radloehemieal EvaluatÍon of Flre Assay For

Gold o o o' o ê ô o o o a ø. o oo oo o' o e o o o @ ø ø o øo o o ø o e o € o 1'1'L

I' Ggneral Proggdurg ø.øøøêôøooêê.øô6øø6eoaø 111

2' Countfng Froggdurg oøøêøoooooeooô6ðooeoo@ 11'3

a) Partgd bgads ø.øoooooocooooo øøeøøo@@eø 113

b) CrueLblgs'ooooo oøooøoøøø.oêø ø.øê@øøøê XX'3

g) Slag øøøøøoooooðeøoo øêoo@ooo@øoóooosøo &I'5

d) MetaX MoXd ' ø@ooe6@eooeeó€oooóoø e@øøo" 13.6

g) Pareing Solutiorì.s,, ø@øoøøoaos eøøø@øøø 1L6

f) Washing Solutlollg,, øaøø@ooøøoecocooo@ LL7

g) Cupetrs êceøo oooaoo oøooooooo @øøøø ooto€" 1L7

3" Srxnrnary of Traegr SËudy 6øoóoøøeøoê@øêeøø L17

E. Strlltrary a øøø øo ø ø oo e øo a ø 6 þ øa ø ê ø ø & ø ø ô e ø6 øøøq@á o o ø @ ôo 119 trsT 0F' TA,BrÆs

TABTÆ N0. Fage b[o,

ï,, Ef,fect of Lead Welght on Cupellatfon Losses of Gol.d , ", 29 ïI" Surrnary of Effect of Lead !üef.ghr on Cupel.LaËf.on Losses

of Gol,d ooooooo,o. 36

ÏTT. Effeet of Sitver to GoXd Ratl@ on Cupellatfon tosses of

GoXd .oô[email protected] aeoøø oøaøo oeooooooe 39

TV, Sumrary of Effeet Sllver t@ G@[d Ratfo on Cupei.l.âtf@n

Lossgs of Gold oooo.ooooc øø.ooeøoèooooøoooøco @êêooøeø6e ¿+3

v Ef,feec of, ParÈíng Proeedure on GoLd lpssês ,oooøøo @øêøø 45 vl,. Srimnary of Effeet of ParÈ{ng Proeedure @r} Gold tosses " 5[ vÏl, Effeet of Heating Gol.du Sftrver, and Gold-Sl.Lver Beads " 57 VIII. Effegt of Egating GoLd Bgads o@o@s@@ê@døoo@øøøøøøø@øø@. 59

lx." Effect of lteatång Sll,ver Bgads ôø@oø ø@ø@6o@o66oooooôeôø 60

x" Effeet of Heatfng Gold and Sllver l{ires 6@@oo øoøoøoeoøo 62

NT. Ef,fect of Cleanlng Unparted Beads on Gold tosses êo@oo " 64 XTT" Effeet of PolyeËhy!,ene Bags on Gol.d tosses For Conptete

Flre Assay oôooo øuøøøøøøøøø'ôoooo@oo eøoøøê@øoø@oøooeooa 66

XIÏÏ. Effeet o€ Fusion Tem¡lerature on Gold Lossês oøøø6,000o0 69

xïv, Stmary ef Effeet of Fusfon Tøuglerature on GoLd Losses 76

)(vo Effect of tead BuËt@n lrÍefght on Gol.d tosses êôooeooøoo 79

NVT" Sr.¡n¡nrary of Effeet tead Button Ï,Ielght on Gold L@sses o. 82

xvll. Effget of Fusfon Tfing on GoLd Lossês ,"ooooo øøøøøøøo@ø 8{+

XVIT.T. Strmnary of Effeet of Fusfon Tfme en Gol.d Losgês ,uu,", 90 XÐ(. Eff,eec of CupellaËlon Temperature @n Gold tossês ",,.. 93 lt1t Srrmary of Effeet of 6upelXaLl.@n Tæ¡leratufê oo ø@ø@ø@@ 97

w? l\.ô¿ ø Effeet of a 25 g, Cover on GoÂd tosseg ø@øøøøøe@ooøø.ø 99

þlll, Effeet of Temperacurc on Fereentage Sflver Re€aíned by

Gold BgadS o r @o e @ a o e øp e @ ø øo e. oa a ø oo @ ø o ø øse@ o o o s o " L02 trTll" Applåeatløn of Optlmr:m Proeedures È@ Håer@gram Slaed

Saa:rples @ø ø ø ø ø a ø ø oa oa øê ø ê @ o ø ô @ ø @ 6 ø ø @ ø @ ø øø @ ê @ ê ø @ @ o ê o ø q o o 106

XXï.V, ÀpplieaELon of OpËlnum Proeedures co Gold Ores , øeøøeøø XlCI

)O(V, Tracer SÊudy of, Gold Losses fn the Cornpl.eee Flre

Assay ë ø o s ø 6 Ò ø ø ê þ o ø øê ø ø øøe @ ø ø øê ð ø o o o o@eø e ø øo oo ø øø ø ø øøo ø &1/+ tisË of Symbols

Pb Wefght : lleight lead foll used for eupellatlon,

Au Added : I'IeíghÊ gold used for anal.ysf.s.

Ag Added = ÌJelght sitrver powder added Ë@ the gotd, Sr¡m : Tileíght of gold-sltrver bead obtafned after eupe3.Latlon

Sureharge : Welght parted bead tress wefght added gold

Ag Retaf.ned = I,Ieíght sfl.ver found ln tbe parËed bead Au Found = I,Ie*ght goLd found ln the parËed bead

Au Loss : T'felght gold added X"ess wel.ghË gold f,ound

s : SEandard devfaËion

Ag;Au : RaElo of sl[ver added to gold added e/S0see, = Counts per 50"0 second eountlng inËeffiral. ¡r : l{uraber @f trlåXs ABSTRACT

Gold Losses {n the various stages of the fl.re assay method were lnvestlgated as a funcËion of erperfnenÈal eondltlons and pmcedures, Ipsses were deterained fndfrectly, bT dete¡mfnlng the extent of reeovery of gold added Èo standard samples, and dl.rectly, by a radfocheoicaL procedure, Procedures and condlËlons found to be optlnt¡!û for nllligran sam¡rles, were applied to several microgram slzed sanpl.es as well as oreso Determination of GoLd Loss In The Fire Assay Method A. Orlgins of the Fire Assay

The earllesÈ known analyËicat procedure which is stil1 in use

Èoday, is knor¡n as Èhe fire assay(l). According Èo the same source, the development of fire assaying arose as a result of the need for controlling the purity of sllver and gold, and prevenÈfng counterfeiting

of these precious metals. Fire assaying 1s a meÈhod of quantitat.ive determination ln which a metal or metals are separated from impurlties

by fuslon processes" It is parÈicularly well suited for deÈermlnatíon of the noble meÈals, which are readlly reduced to the elemenÈal state

on heating, rn a reducing atmosphere it. can also be used for deÈer- mfnatlon of some of the base metals.

one of the earliesE references to the fire assay was found in

the Tel al Amarna rabl.ers dared around t3g0 8.c., in which rhe

BabylonÍan king complained chat a bar ef rrgsldrr recelved from a

merchant v¡hen tested by fire, proved to be largely dro"r(2). A

cupellaÈfon proces.s for gold is mentloned by siculus as being ln use

in Èhe second cenÈury B.C. Several references to fire assaying can be

found in both old and New TesÈamenÈ. one such reference fs the sËaEemenÈ ttson of the prophet Ezekiel, of man, the house of rsrael fs to me become dross; Èhey are even the dross.of silver, .oo, As they gather sitver and brass, and iron, and tin, into the midst of the furnace,

to blow the fire upon ft, to melt ft .. o As silver fs rnelted in the midst of the furnace, so shaLl you be melted in the rnidst ¡¡"r"o¡.,r(3) Pl'1ny, Èhe Roman historian, records the use of lead for the purification of gold and silver by Roman metallr¡agisa"(t), Geber, the great Arabfan alchemist, also describes the decermfnaÈion of these meÈals bv cupel lat lon, .\

. Ïn EngÏ.and the assay o€ eoinage utin"izing eupel"LaLien was Ëi-rs{: reeosded in the tirne of Êlenry IT (I15¿+-f.1S9 A.D.)o whiÍ.e rhe f,i.rsr extant official" recond of i-ts use in Franee" dates ro l3n4 A,D.(2), îlparting The assay?î i¡r r+hÍch gotd is seperar,ed from sir.ver by Ehe

aetion of nitric acid, vcas tr

rn this conneetion Ít is inÈeresti-ng to noÈe Èhat the originax. name

for nitríe aeid was Itseparating rc¡aterlr(1), Albertus Magnus ( il"ES-LZg0 A"D.) gíves aR accrunr of the preparation of nitrlc aeid and íts abiÏ-ity to separate siLver fro* gotrd(l).

The first expLieiË reeords of assaying were pubtr íshed anom3rmously 'by ()\ a German earl.y ín Ehe sixLeenth eenLury A,D,'*'" In L666 pepys

gave an accÕunL of the parÈing prôcess which he observed ín the Eng].ish

mint ar¿d whieh aeeording cô R@se bears a strong resembtanee to methads of the presenr aan(2),

I'iith such an ancient hístôry one might ç¡e].r. ask on whaÈ. basis currenÈ interesÈ ín the fíre assay as an analytieaL method ís justífíed. I'IiËh Ehe advenË of sensítir¡e ínsÈrumental. teehniques,exuberant, claims

are of,ten made thaÈ Ehe nev¡ methods make Ë,he old obsoLeLe" Thus one source sE.ates that atomie absorpËion speetnophotomeEry is rapídLy

repl"acíng fire assay *uthods(4), Thi.s view is not sr-rpporred by many

expenieneed assayers ef go!-d, In a genera!. dÍsar¡ssíon of the prob}ems

assoeiated wíth Ëhe various stages of the fíre assay H, Brit.ten makes

the fotrlor"eing eom.ment¡ î?rn crrûnön r+ith gold assayíng eLsev¡here t.he

c3.assíe aL methods of f ire assay have conËínt¡ed t.o v¡iËhstand atr I

competltion from Èhe ne"r¡ rnethods of chemicaL analysls Lrhieh have been adopted as standard pnactise ín orher g1u1¿rrr(5), Tn a reeent .autheríLative Lreatíse the statement is made thaL, Î?Fíre assayíng is è 4lE

.Èi:e best method for deLerminaticln of go3.d in most material.s{6}tt, î}ie -

Latter stacemenË l.eans perhaps too far Ëo Lhe oËher extreme and defi¡"r:t teÏ.y requíres qualÍfíeaEion, There is no doubt, for instanceu that net¡tron aeLívatíon analysis of very poor gol,d-bearing geoLogíeaÌ. rnateríaX.s is the preferred method of anal.ysÍs,

TnspíÈe of írs antíquity the interest inu a¡rd ín s6me eases preference for, the fíre assay method is based on so!.íd reasons" Fore- mosL amongst Èhem ís the question af anaT,ysis Ëi.me, A eomplete fíre assay ean be aceompLished ç¡iLhin three hours after reeeiving the sample" Tn cont,rast r,¡et meÈhods requí"rlng complet.e dissotrution of an ore typÍeali.y require from e\nvo to three days" I'fuLËipn"e analyses are neadiny eondueËed by carnying through a dozen os more sampnes simul.Ëan- eousLy" Another probi-em whiehu íf noÊ rvercrrûeu is at åeast mínírnízed by the fire assay method, is the probLem of obtaíning a represenËaLive sam¡rI.e" În hightr"y sensitive methq¡ds sueh as neuLrûn ae Livatio¡r maximun sample sizes are l"fmiLed tÕ approxinate3"y 0,5 grams" Since gold ores are invariabny hetenogeneous the smatl- síze of sample increases the probabi}ity of, sampl.íng ernors. This ís rhen refLeeted in poor (24) precisíon For the fire assay, sampLes sizes from tr 5 to 60 grams are readitry handï.ed and yleLd a higher degree of apparent hcmogeneity,

FínatrI-y the fire assay ean be used for sampLes contaíníng from L"0 mieregram to 1.0 gnam of gold" At Lhe upper levels and whe¡l dealing ro¡igþ relatível-y pure gotr-d (eg, goX"d butrLi.on) the fíre assay method ís tlndoubtedi.y more acc,urate and preeise th¿an any insErumentaX. teehnique,

ïn a paper presented at a symposium on the anaX.ysís of high puricy gold-the e3.aim, r.¡as made that ltno methods of any kínd are availabi"e for determíning the crncenËrati.on of the rnajor etrement vrith anyËhíng remote.!"y approachf.ng Ëhe preeísíon cbtainabX.e for the anal"ysis of go1d _f¿_

l?\ by the fire assay techniqüê,11\r;"

Tn *¡iettv of the foregoing anC inspile of the rejeetion of the flre la\ assay by anal.ytl-cai- researchers reported ín a reeent boolc'"'one e'annôt hetrp but agree ?rith the vier,r expressed t-here thaÈ rrby ícs rejeetion

Ëhe researeher has el.iminated from his experience one of the most ferelte and usefutr" areas of ínvesÈigaLíon . ", " and Ëhat the fire assay r,¡í11 retain lts usefuÏ.ness to those who have mastered its simp!"e

tt( B ) ÈeehnLeþ¡rrÀ ¿qi -rracsv l]" The Fire Assay ïlethsd

The fire assay meth*d or p-rrcess can be dívided convenienËI"y and natural"l-y i.nto four stages. These ane: fusion, cupeÏ-lation, partíng,

and anaÏ"ysis, The probi-ent of sampLing ores, while very imperËant, ís

a prtblem nÕT: unique to Lhe fire assay and musL be taeed regardLess of

the nethod of assay chosen" Suffiee iÊ to say, that Lhe method of

sampling musË be reporred along r,rith Lhe results obtaíned" ï" Fusion The object of this phase of the fine assay is to erncentrate

the precious metals of an ore in a leacl buLton or Bhase ç¿hich forms

as a resutrr of ínteractions betv¡een f,tr-ux components, Under prtper conditions for the fusíon the renaining fLux materiaLs form a fusíbne

si-ag, The moLLenn two phase? lrass is poured into a meiaf. mold rorhere ít

is alT.orsed to csoL. AfLer cooling, the lead button can be separaËed

irom the s1.ag by genttr"e tapping r,¡iLh a hanmer,

CornmonÏ.y used flux materials inelude f.íeharge (p¡O), sitr ica (SiO2), soda (Na2CO3), borax g[ass (na2n4O7), and fi.our, the proportions of each varyingrdepending Õn the compositíon of the ore Eo be aira!.ysed and the preferenee of the assayer, Regardíng an optimum sLag composition lo\ Beanish"' scates, ttV.Ihether or not there Ls an optimum strag composition îoy eaeh ore ís not knoçrnîr, In any ease t?, ", no two assayers working on ihe saÍne ore vriL1. agree exactT.y on the fTux proport.ions to usee so

i'c ís safe Lo say Ehat, for any given ore, Ehere is a ccmparati.¡/ely r,eide range'.*iLhín v.'hich t.he four conrnon fLux eonstituents may be varíed and stiLl, ín the hands of an abl-e assayeru yiei"d praetic,ali"¡r ¿¿strtica3. y'?n\t'" resutr ts .11 ' " P.egardíng universal fLuxing mixtures Smíth(2) scaces Lhat ?tn,.n ff-uxing materiaLs suítabtr"e fo:: fluxíng a3"1" eLasses of ore are frequently -6- re&rmmended, but al.thøugh these rnixÌ:ures may be suitabS-e in many cases for certain ctr-asses of, ûreu they soone-r or T.aLer tr"ead ts tail"ute if used for al"l. ores"fl

The ehe¡nisLry of fr.¡sion prûcesses is nor,¿here near being established

1,IhíLe reasonabtre guesses ean be made concerning some of Ëhe reactions, a eompLeLe exp!"anation fo¡: even a singtre ore arvaíts a mtre extensir're sËudy oi these muì"ticomponent systens" The commonly hei"d view woulC be someç¡haL as fol.l-ot¡s (2,10,1L,L8,27). The fínely divided one and fl"ux materials after intirnate mixi.ng are heated" In the absenee of a pLentiiu1- supply of air the redueing agent (flous) eauses redueLíon of some of the tr-iiharge thröughour Lhe mixture,

2PbO + C - 2Pb + C02 The accumul"af:ion of 1-ead results ín the foernation of f,ine dropletsrr.¡hich in cLose eontact r.¡iLh the ÕreeextracË the goLd from ít- for-ning a ¡,:otr.d-l"ead ai-loy" As the temperature in the pôt or a,nucíbLe f-ncreases the i,ead dropLets setcle to Lhe boLLom carrying che goX-du and other precíous metals with thern, IL is generaLl"r' believed to be imporLant ihat the Êernperature must not be too high during, the initiaL sLages ¡¡f fusion f,or then the tr-ead fa!.ls too quíckly r+íthout- having futr-ly exËracted the goLd" For this reason the fusíon is often begun at a Lor¡er Èemperature and then graduaLLy ínereased tovrards the end, At the higher Lemperature the very dense gold which has not been exEracted raay sim.pLy settl-e out and coli.eet at the bottom r+ith the Lead. In aï.L

I"íkel.ihood Lhe overalL process ís a cornbínation of the tçøo"

Some assayers prefer cr rnal.-e use of a cover. This is a layer of some rûarerial, noL conLaining the ore, spread over t.he top of che eharge, T'he intent of the cover ís l-o prevent f"oss of ore by dusLi-ng frn\ or ebul3-ition'"-/, The cer'er materiaX- event.uaLl"y enLers the slag af.Eey -7-

the fusion is v¡eLL undervra-r" In addilion tÕ the reaetion absve, eleraenE.an lead. may be formed as Ëhe litharge reacts t:¡ítTr other eomponenis of, the ore, Tht¡s r,¡ith síLicace orese ín ç:hich gold is ofEen found, l-ítharge may reacL tû

form a l-ead si.X.icate of i.or¡ meLting point. s¡hieh ean further reaet wiLh oLher base meta-Ls presenL?say as sulfides,

eg. 2PbO + Si.OZ : PbZSiOe

PbzSiO4*2FeO*C : FerSiOO +COZ + 2Pb

A basic f,l-ux such as soda, ín addition ËÕ controlling the degree of aeidíty of the slag, aids in the process of desulfurízatíon at an ore high in sulfur" This is desÍrabI"e sínce sul"fur from base rneLal"s has an extremeLy hig.h reducíng por+es and resuLts ín excessiveLy Ï-arge

lead buctons"

êBn 2 FeS2 + 15 PbO : FerO, + 4 S03 + 15 Pb

lIagCO, + SOg : Na2S04 + COe

In those ores rahere Ëhe sulfur cônËent is objeetíonably high

íL ís sometimes necessary to add an oxidizing agent such as K03. Thfs method ís the charaeteristic feature of the nitre assay. 2FeS2*6KNO3: Fa2AU + ?KZSO' + SO3 +3N2

4FeS2+1-0KNO* : 4FeO + 5KZSO^ + 3S0Z+ 5NZ

The evol-ution of gases (C0, and Nr) helps tÐ stir the f'osion míxture

and enhances the extractíon proeess on r.rhich the method depends, Too vi.oLent an evolutíon of these flases can Lead tô lnechanieal Losses of

pree metal" íous " Regarding the opLimurn tread but.ton sir,e 1t"* nó rJata has been 8-

lr t I recordedtr\!r/' It is tradiclonal to produce Lead butÈons between 25 and 35 grams" The size of Lead button should bear some relation to Ëhe amount of charge(11)"

Trlhile texLbooks of fire assaying outline methods of calculaÈing flux compositionra good deal of empiricism prevails. In the main thís is due to the complex nature of ores whose composition is dt best only partially known" the failure of oxidlzing and reducíng agents co achieve their theoretical oxidizing and reducing power, and our ov¡n meagreunderstandlng of the baslc chernical reacÈions involved. II, Cupellation

The objectlve of cupellation is to separaËe the lead from the gold and silver whfch were combined in the lead phase formed during fuslon, Sllver is ofÈen presenr in gold ores and if lacking, ís al.ways added as iL exerts a procective effect on gold losses, Cupellation consisÈs of an oxidizing fusion in a porous vesseL called a cupel " Wtren the lead-precious meral alloy fs heated in rhe presence of air Èo a temperature sLlghtly above the melting point of the a11oy the lead is selectively oxidized Èo Pbo, The greater porrlon

(98.5%) of the licharge is absorbed by the cupel whlle the remainder is lost es vapor (tO¡. Conmon cupel maÈerials lnclude bone-ash, cemenË, and magnesia. Bone-ash cupels absorb an equal weight of litharge. Magnesia cupels absorb abouE 3/4 their weight of litharge, this factor deÈe¡mines the maxfmt¡m button size which can be handled by a given size of cupel. ThirËy and forty gram cupels are conunona In the cupellation process, which is conducted fn a ¡nuffle furnace aÈ Èenperatures of 17000n or higher, che lead alLoy melrs, lniÈial.ty fornrlng a dark scurn over Èhe surface. If the cupels are pre-heated for aÈ least 10 minutes Ëhls scum disappears and the molLen -q-

buttcn becoroes bright, This is referred to as llopeni-ngîÎ o and nel:rna.i-ly

talce.s Less than 5 rninutes ".,yith the draf: cl.osed" The drafc is chen opened aird the Lead begíns Lo oxídize rapid!-y thereby raising the

temperature øf. the moi.ten bucton so that i'c gtror+s" The surface Lhen

becomes sl-ighËT.12 eonvex and the moLten f.itharge passes dor"m over the surfaee and ís absorbed by the eupe!-" The butÊon is then sai.d to dríve,

To'"¡ards the end of the cupell"ation the propørti.Õn of sii.ver and gotrd increases requf::íng a higher ten:iperature to maintai.n the Liquid state and drive off the l-ast of ihe Lead, To aehieve Ëhis the draft ís

c1osed and the eupeLLation lïfiníshedl? f,or a coneÌ.udíng five rnÍnutes"

The basis of the separation of the Lead from the precí.ous metaÏ.s

is the faeL thai the PbO r¡ets the euBetr r¡hine rhe síl-ver and goLd do noT:" Thus Lhe sí3.ves and gol-d renaín as a smaLl bead or priI.T. ún the

surfaee of the cupen- r¡hitr-e rhe Lead o:

In a pro!¡er3"¡r eondueted eupe].LaÈion the molien síLver-gold bead

must be renoved, sLorvLy from rhe furnaee since síLver rich a3.i.oys have

Èhe eapaeiËy Ëo absorb large euaniities of oxygen whieh ís reX.eased explosir,'eLy on eooLing quicktry" Sueh beads are said to Itsprout.ll or

Î?spi,'rf and eannot be rel.ied upon Ëo gíve aeeuraie resutts, On eooling

a bead, from r¿llich aX.1. but a Lrae e of n ead has been removedo a

characËerístic bright ff.ash or îlbLiclcrr is observed, as Êhe Latent heaE of fusion ís released, FaiLure is exhibít Lhe Itbliqtr<'îî ls one índícation

that Ëhe eupel}ation has been arrested too sorn" In some cases crystals oi Ï-itharge f,onn on the edge of rhe eupeÏ. and grow in Lowards t?re eenËre

covering Èhe lldrivíngle bear3, such sampl"es are deseribed as îÎfrÕzenl? and musL be rejeeted, The eause of freezing is the faÍnure to maíntain temperature" Sinee inereasj.ng che tenÌperature of eupelX,ation ís eÊrürronly said to inerease gold 1osses, the recorn-mended Ëemperature of *10-

eupeLLatiÕn is öne jus: hi¡;h eaough i* prevent f.reez'tng. In any rase

l¿rsses Curing eupel-latiÕn are t¡ridety held to L.e the main seurqs ra{: on'}d l-osses in the conp}ete fiye assay(Lz)" ïII" Partiag Parting involves the seperaiion of the si}ver from the sitr"ver-gold

priT.L obeained from cupetX-ation" Any base meLaLs v¡hich may have been

carrÍed aLong to chis point are aLso Leached out of ¡he bead by an

acid treaiment. \,ihile sulfuric aeid is someiimes used the eommon acid

ís nitric. The exaci: procedure used probabLy varies môre from one

laborar.ory Lo anothero than for any óther phase of the total prÕeess,

Variations in procedure depend Õn T:he kind of príll received (sil-ver to gol.d ratio) and the pref,erenee of the assayer,

Earl,v asse]¡ers hend che vier.y ihal e'ompLeie remova1 of sil.ver r¡as impossibLe unLess che ínitíal- síLver Èo goLd ratio Ì¡as at Least 3:l-" In pri.Lls containing !-dore [han one-quarier gold, silver rras added unti].

lhe required ratio rvas attained" The prceess ??'as referred Lo as

íncuartation," P.ose(13) t thaE ti-re mininun raiío should increase "L¿ øith dec,reasing amounLs of goLd beSinníng \'riih 2,5:l-"0 f.ar ZAt mg" of

gold and inereasing to X.0:1 for 0"2 mg" of gold" i¡IhiLe a high sílver

to goLd ratio íncreases the rate at r+híah síLver ís dissol-ved it a1so

i:ends tt cause the bead io t¡rea!: up and make handÏ.ing more díffieul'("14)

Beads concaining I-ess than a 2;1 sil-ver to 3o1d raËio r;ould noL part adequateLy even :l-n sirong acicl" Decreasíng the sitver to goLd ratiô"

al"so íncreases'che dígestion time reqrrired to attaín a certaín degree

of siLver renovatr, Regardin3 acid s-c¡:engi:hudifferences cf opinion prevaiL here too,

Accordíng ,,o n,rglr*u(l-0) the recuired acid sLrenglh depeads on the si-Lver

Ëo gond rar:ío" TIne hi¡her i:his raiio ihe rveaicec il":e acicl e*neentration -11 *

.sheuï.d i:e in orCer to nainiai-n a c*he::ent beaqi, lle found that Ì.;7

nii-ri-e (acid:waier) is safe fo:r beads containing fror".r 3:1- to 1CI00:1"

silver to ge1â ratios, The slronger the aeíd the nore rapír3 anC

conplete ihe parting process is, 0n the other hand Smith(2) or:*,,n" T"K. Rose as i:oainiaÍning Lhat 4:3 nitric (acid:v¡aier) is suí.tabLe for al"l sil-ver tû tûLd ratios and.'chat no parr:icuLar ad'¡antage obcaíns fnore use of more dilute acids" KeLler(2) is reporied as recrminending

L :9 nitric ( acid:r¡ater) for aL-l" racios and ihat aLl- buttoir.s rer,iain coherent up Lo a siLver to gotd raiio of 50û:1"

Tí¡-rre of conLaei bei:rr;ssn acíd ancå l¡ucton is anoiher variab3.e on r.¡hieh ãgreement is Laci:ín6" Aeeorcling ;:o Shepherd and lietrich(14)

rlpartín¡; ís practica1,i-y eomplete r,¡hen evolution of gas ceases for

sanples contaínins up Ëo 2û n5" gol"d and rahen high silver io goX"d ::aÈios are mainiainecl ,r, By concras: Bu¡bee(10) ru*o*rnends one parting r,¡íilr l. z7 n|tric acid untí1" actíon ceases and a secnnd fo:: 1"0 rninutes wíth tr:L niiric, Snith(2) .,*i.rr.ins a singl"e L0 rnínute boiling ís

enouSh for 1-0 ng, goLd beadsrrehiLe for lange beads a second parting in ?:l- nitTie f*r 5-10 ninutes is requireC,

\Iith regard to iemperature of tl'¡e acíC aLl- sources consuLted

seera'to agree thai tresl. resuLis are obtained as tr speedo compÌ.eteness of nartíng, and coherence of goLd if the parting acid is heated before use and lcept jusI betoi+ boiLíng fo:: parting. Aelual boiLing ís nor generaLLy reconmended in order tÕ prevent mechanícal Losses of go3.d and reduce stress ôn rhe beads l'íany assa,vers alsc fLaËten che bead prior to partr-nE Lo a thiekness of 0"CL inch io aicl inóre c,sînplete removaL of sí3""¡er" In faei a

ù¿¿:,r!rÀ!bdr¿L ¡:eu¡ioftion of siLver atr+ays::esisËs dissolu¡itn\tol" The arrÌounl relaiaed depends on the sil"ver 1-o gold ralíou che thiei;ness tr -i 2-

+¡híah ir. has been ro3-Ledn the sLrength and nuraber of aeid treatmenË.s"

Ti is aLso eX.aimed Lhat anneaLing of the fLaiiened prílÏ- ís víLan íf

the eoncenÍ:ration of síl"ve:: reiaíned ls io be Xoç¡ ancl reproducible\r)1,

Af ter decantinp; rhe parÈing aeid, che gol-d residue ís r.¡ashed severaL tínes ryith hót water ic i:et rid of any siÏ.ver niËrate rr¡hiel: undoubredly renaíns ín Lhe pores of the gold, At Lhis point the bead is sofi and spongy and is easily broken if not handned r*íth reasonabl.e

c'are" I'Iith incoherent beads í:hís neeiuíreiaeni: is íncreased" The bead

is then SenLi-y dríed and anneaLed" The unanneaX.ed bead is black- ín col-or, The anneaLed bead attains the usuaL gold eolor associat.ed t"¡ith the metai- and ís ready for the finaL step of the pnocess, fV" Analysis

Tn the eLassica1- fíre assay Èhe analysis step invoLves the

ï¡eighing of the annealed bead on a micnobalance" It is assumed in the elassicat process that the final- bead ís pure goLd or that the error due to ineomplef:e parLíng is of, no eônsequence, Tn fact there

are eompensaLing eËrors ln the process v¡híeh Õntr-y ¡¿1'str"y can be expeeted

to offsei each other" In no::e aceurale r,¡ork thís probLem is overcome by assa¡'ing standard sampl.es aLong rçich the unknor+ns and apptrying an appro¡:ria-te eorreetion" The difference betr,"'een che r*eighe of parted bead and golC added- to the sr:andard sampLe is referred to as the surcharge" Tn more recent Limes a rnodiiíed or semí-cl.assícatr variety of fire

assay has evol-veC. Tn Èhese che fusion and eupe}tr ation phases of Ëhe classieal" proeess are usecå with nrodifieations introdueed at the -partíng

and analysís stage, Tn so¡re e'ases parting is el"iminated entirelyrwith

the gellC cÕnËent of che pri1.X- beíng deterrníned in the presenee of tire

sitr"ver by such r¡a-ried Ëechniques as a'romie absonpai*rr(28)" speer:rogr ^phy{29) , l-J-

{26) fco) neuLron ae tivaiion ", and x-ra.v fl"uorescencet*-'" Sueìr a synthesis uËiåizing the advanlages of the eLder eLassical. teehnÍgues and these sf the ner¡er niethods seer¡ls io be exemplary of the r?ferliLe and useful areas of investigationll referred I'o abæve" -L[+-

C " Gol"d Losses The l"osses of gold during iire assafing can conceívably, arise

ín a variety rf r,rays incl-udín3 the fol}-ovrín9"" i- " Fusion Losses due ts: a^ dusLing and/or spaËuering, b" ad - and/or absorption of goLd on ihe crucíbl"eo r, solubi1ity of goLd ín the slag,

d, vol.atít ization of gotr d"

2" CupelLatíon losses due Lo:

a" absorprion of goLd by uhe eupeL, i:. volacitr ízatíon of gctd"

3" Pariing tr"osses due Lô:

a" solr"rbil"ii5' of gold ín 'che parÍ:í-ng aeicln b. decanting, of sna-'l-l parLicLes af goLd r1åith the pârËíng acíd,

Tn point of fact no{: aLL the conceivable sources of loss have been demonstraï:ed Lr Þg sígnif icant" Accord-ing co Det*ey(16) tt.,,it is comnon to bi.ame irregular âssa,v resuLLs upon vol-at.ilizaiion (of goLd) but Lhai there ís no real evidenee for a Loss suffieient to appreciab!.y afíecr Lhe resuLt in a properLy eondue tectr âssayl?" Tn a more recent source(12) the Loss of gold by volatil.ization is considered possíbl-e though Ëhe Lacl.: of direet eviclence ís eonEeded,

A, simitr ar sit-uation arises r"rith respeei tÕ solubil" ity losses of 117\ golC in ihe partin¡ acid. Agaí-n De'.,reyt*" points oul that if ihere is an], sLatemení- that is f i::nLy estabi.íshed in r:he general cherníeal l-itera.ture ii is" that g*ld i.s nol solubLe in any siirgle acid" In the f-ilesaí:ure of assayinS, hûç.zever, ntaybe found various stalemenls to Lhe ef.f-ee': ihat, i:r partinß:o1d from si1.r,'er ín assayiirg, ¡otrd nay ¡:o íilto . -15- golution ín the nitric acid used, To resoLve the dlscrepancy Der,rey

proceeds to denonstrate that in boillng concenErared acid (l20oC) as nuch as 0.6 grams of gold wlLl dissolve per liter" Horvever, and rhís ls the key polnt, the parting of gold from silver never occurs under such drastic conCítfons as !üere here used Lo demonstrate the solubiltty of gold" Thus lË Ís possible to demonsLrate a poLentíal source,of

gold loss by ernploylng conditions whlch no assayer would in fact employ. In the particuLar case cfted Dewey goes on Eo agree wiÈh the practical conclusion of a previous n..,"ËhaÈ "audy(l7) the solubiliry of gold in the partíng acid i.n ordinary ore assaying is negligible,,,rr, rn spiÈe of thls it ls not uncoñmon to find references which give solubiltcy of gold in Èhe parting acid as a possible source of gold loss. In a recenÈ 0962) critical revier,r of r¡ethods for che analysis of high purfry gold bul.lion Finkelsreir,(12) tt"rs a variety of srudies relating to gold losses .in the assay process. Accord,ing Ëo these "ä,rrc.", losses increase wiËh the tenperature of eupellation(18), with Èhe quantlty of lead adde d(2) , and wirh rhe concenrralion of base (r\ metals added'-'. silver is cired as havíng a protecLive effecc on gold losses, while varying the nature of the cupel also affects the extenË lro\ of losst"'. All of these earlíer studíes are deficient, however, fn

ÈhaË Ëhey omft essentíal detalls and in Èhat in no invesEigation have all the signfficanr variables been controlled(2). ïn cupellaÈion temPeraEure sEudies for example, invariably the ternperêÈure reporËed ís Ëhat of the muffle air, rshile rhe signÍficanË paramerer is the temPeraËure of the bead lEself . Irrhile noL readily obtainable, especially before the advent of the opEical pyrometer, bead Èemperatures can vary conslderably from Èhe muffle air Èemperature slnce Èhe oxidatÍon pf lead occurs exot,hernally. Thus ihe bead temperaÈure depends on_ Ë"6 *

.Lire suppl"y oí 6xygen as røel"L as geireraÏ. aír tenperaiure" Ir is cot-tironLi' hel"d';ha-t the increase in go3.d losses rn eupel,LaEion depends on Ì.or,¡ering the viscosity of the g*ld, Tf sori:his variabLe shouLd depend en bead,uand noL air ;:ernperaiure"

I'ihil"e nuch cf the earl-ier ¡,¡crlc is suspeet for the reasons given above*severa-'l- ialeresi:ing stu<Ìíes of goÍ-d Losses have been atËenpted sinee then, Tn particular, a systenatic study of gol-d losses r,yas undesËak-en to deterrûine ttthe magaitude of, sysÏ:eroatic enrors in the standard iire assay for gold, under conditions prevailing in representative assay i.aboratcries on the l.IítiraLersrandll(ZO¡" They report 'r:haL under ôp'Èinum eonditions róutine mine assays give va!"tres absui ?JL Ls,,:¡ due io c,5iá gold Loss ro erucibLes, slagsrand butron dressing, A,7% gaLd loss Lo the cupen rand Ì. ,?,% di_tr:' r:i_on l¡T r"_ron durin¡; pr-ri.veriøing. Tn thís siu.dy radioactLve goi.d rpas useci Lo delerrníne ihese Losses, Bead "xeíghus ranged from 0*5 to B i-ng" unfortunacety, ihe exfent of goLd reeôvery in ihe fusion scudies average€tr øtr'Ly 96"69% for 73 d,eiesrninaiions" On [he basís of a sÈatísrical. study of iheír resutr i-s!'Èhe auiirors feLi: eoropeLl-ed ¿o eonelude Lhai the radioacËive ¿oLd did nol behave as Lhe earrier goLd fron Lhe ore" trThe real losses to str ags and erucibLes must therefore l¡e considered. to be ¡/o^\ 1? \ /'u 11nf i1g¡",* . '/

I"Tith regard to eupeLLation Losses in the sa¡ire sLudy a díff,erent probl-ern aríses" \.,IhíLe rhe Ëotal reeovery of ::adi':aeÈlve gotd avera¡;ed 99"77"/" for 90 eleterrrinai:ions one cann#i hetrp but îfieÕnder ru¡hy lhe aetive goi-d shouS.c nov¡ begin ro behave Líke earríer gold if ii did noË do so in ihe fusioir siudy" In both cases radioaetive goLd r'¡as a geÏ.ati.n stabi.Lízed eoÌ.Loidal- goLd suspensíon, Even if the radícr

'and carríer gcn-d behaved sir.r-i3-a::lyean even mære dåff iauLt problem remaíns, aa

Tn atlenptirrg io deteri'aíne cupel"f.atíæn S.osses ii Ís custtmary tû accurateLy r*xeigh oui u:cr;ions Õf high pu::ity g+lci ûn a l.eaC foiå of approxinaiely 25 g" To this is added sufficieni síX"ver Lo m-alie parling

feasil¡Le, T'he I-eacl. foii is rhen f,oLclecl eareful"i-v io encase the sil"ver

and gerLdu and cupelLed as the nomrai. Lead buLion ene vvcutr"d have obtained froia a fus'íon prÐe'ess, In Lhis wal' one hopes to ei.ininate losses frorn

the firs: s'':age of che ove::aLl fire assa)'and rhereby obiaín a r.n"easure of :he cupell-aiion and ¡:arí:ing tr-osses" TAe cuêstitn noi'¡ a-rises whecher goI-d lesses:l-n such a sinuX"aieci cupetlatíoll are ihe sa¡re as for the

cupellaiíot of a l.ead bur:ion in i,yhat::rust be cLose Lo a homogeneous lead button" In an arre!'l1pr. ir overcome this probl.ern coxon *- ux-(20)

p::epared an a1-L*y bu'cËon of :he l.ead and gol-d, The meth*d of preparaëfon

ì{as nÕi deseríbed. I'lost stud,i-es have not been eoneerned Lo even rnahe

thís distínction anci ha"¡e assuneC that eupellaiíon losses "lenerally measured frorn unai.Loyed butcons are vaLid estirnaÌ,es of ihe eupeltr-ation nosses in rhe overaLl- fire assay prrÈess,

A second study of ínierest ryas unde::Lai

the 1"?f/" puLverizing error coul-d ire el:Lminaied" tosses to sLags o lrased on L32 residue fusions wete 2"2)"L" Losses tÐ cupel"s deËeriained

iro¡r 44 resid,ue fusíons r..¡ere C "5?:/," The sílver reiained by the parted bead q*as found to be 1"93.%"

Since a sensi:íví:y of 5,0 X 10*tZ ,, has been repc)r:Èed using a

ì"ì.euiron actirratiçn rne:hs

rhe fire assay prseess" Sensitir"it)' nolr.¡j-thstandingul¡.in ec aL\¿'12) usin¡ a neutron ae 'Livat:ion rne'¿irod e:raärined fiu;r constítuents, str-ags u nnr r.r¡11c Iarr? þçiißns*and **r"- arrd, found goi.d !"- ' 9*"* *upels losses for fhe fíre -t8-

assa]' :o be ne3l"igible, I,ihi3.e sone ¡;ôi-d was eleteeted on the cupel amsunts x,xeïe repilrted as ne¡l ígibLe, As Bea¡rish and i/an Loon(B) point

oui ín iheir recenL bock, these resuLi:s are diifíeuLt r:o expTai.n, The

Þ-::obtr-errr ís sonewhat heíghtened sine,e the neutrrn aetívaLicn of rhe Lead

bu'¿tons produced by ihe fi::e assay"aad ihe ore itselfuindícaces a ¡o3"d cû:lien: of 0 "89 onlCon and A,9A oz/ton respeeË,iveL1'. The singl,e

vaLue of Û.8[+ azlton Êrorn a c*rr¡rLeie fire assay procedure indicaËes an

appreciable erro-r either in the fire assay or i.n Èhe ac,livaticn resutr-ts"

Loss of goLd. ín'che iire assay v¡as aLso srudied by shine(23), The

:aajor l-oss af ¡:oi.d was reported. as cccuring dtr::ing cupe'!Latíon, Fr*in autoradíographs i-c vvas shor'm that ihe 'cui"h of ¡he cuÞel l-oss v¡as al

the poíni: oi contaer- be'rr,reen the pr:'.tri. ani eupe1." This was aLso found 11ç) by Coxon eL a'!-'*-'u Ttre Lçsses tö the pot ?-saLL were found to be eûnceni:ratecl in ;:he area ?linuaedíai:ely above tTre fused I-ead-sLa¡ inter- iace (ie" near the botton of :he ÞoL) and. extended over those regions t'¡eLted lr.v lhe charge" t¡To detaii.s lr"ere given regardin¡¡ sampn"ing, neÈh*d of r-líxing 'iracer and sampi-e. Ðr even ternperaiures of fusion and eupelLaiíoa. ¡¡ain ¡oLd recovery l{as not quantiLative and nay índicate inade.suate techirique as sug3este,'i by Beanish and v.rl Loon(B), At ihe rr,icrograrn level very tr-íttle has lreen done to esiab}ísh { fha aq+an i aF anl .f *^^^""^*,- I - -- ¿,..rld recoveri- and^--1 goÍ.d^^t -l trøsses" Chor,¡tn*,^,.- "f'\ îepôx¿eå 97'L Tee{}ver)7 of geLd îar mLerogran: size sarnples, Losses were nol e::pL:Lcí';1y si:u.-iied ín tiris case, A specirophoiemeiríc rnettrod tr¡âs usêd for t-he rleterrainai:ien of ¡¡oLd conieni in the sÍLve:r bead" j-ir¡ii:ed A ,t.,dy(26) ir,.rol-vin¡; [r-tr aad 0,5 ng. Euanii'cies oí go}ci shoulC be mentioned, A prel_imirrary fueion of the flux naí:eriaLs senoved any goid and sÍLver :-nto a Lead burton l,¡hich "r¡as discarded, =1,?-

The s3.a¡ r'vas retrtund, raixed with suFfícient reduce-c and :he gof.d and

assayed to produce a earefuÏ"L-v ::eguÌ-aied síae cf Lead butcon" Tiris

bution r,¡as then íEradiated before i:he addition oí síl-ver-to reduce l-10.\3. background clue t" ;\f ier i::racXia,:ion the siLver was add,ed. in

the iorn of l-ead wi.re contaíning 2.L% siT"ver and eirpen.!.ed to¿;eiher r,rith the Lead buiron" Goi.d recoveries ranged from 97"C r-ø 99"û%,

Cupei. Losses ranged fron: T..5% co O"STz.rand s!.ag trosses fron tr,5 to A"3%"

Fusion tenperature l,eas.rirainiained ai 900 - lOOOGC for L hour inlervaLs"

Cupeli-aiíon teleperâiures were nrt repeirted" The tot-al recover:¡; 6g

3oL'd r.tas exac'cLy 10C,C?å in each of the seven samples exani,ned" Penha¡rs

as a resutr trcr',:ci.itLes were noi even counl-ed"

Äl :he aanog;rarl level a very e:itensíve si:udy of a variety s¡g nobLe netals ha-s l¡een re'ãvorËeel by Beye-r:nu,-r.(25), L¡hix.e the bux.k of '¡he s,udy deaLi l¡ich Lhe. other nobLe netaLsesûne i-nieresri.ng resuLis

1,¡ere reÞrrted for gold as weLl, Par';ing lr¡sses of 0" 4% and C,B% ç¡ere reported usíng 5A% v/v sulfuríe acíd on gotd-si}ver beads eontaíning l.a% anå.0"005% gotrd. Recoveries of, golcl from feldspar, gatrena and roasted ose ?;e're 1.0û%, 92"/"u an& D4% res¡leetívely, ALso of ínterest is the reported coprecipitation of LA% anð, T/" of the gold in a solution coniaining 2 rnicrograns and 2 ng" of golc respeetf\¡el,y, frsm whleh 5 mg, sfl"ver nas preeiplËated, Tn view of fhe contrad,ici:or1z sLaiemen:s forrnd Ín the i.íterature, it l¡as eons:Ldered desírabLe to atier¡tp ¡ ro shed sorne light o:r tha maLeer ìry siu-dyíng gold Losses under a r¡ariety eii conditíons usíng sj¡n:heiic ¡o!-cl ores, rn the proc,ess it r+as hoped that {:he oplírnurn- concl:L[ions and p:rocedures cou].d be dete::oined as l'¡el I as obiai.nin¡; a clireci neasure of fhe goi.d i.osses i-i: the varirsus sfiages of the eomp!.ete *.At ) - fi::e assay prt*ess. Tn such a nanner a colïpari-stn Õf Lhe }*sses deier¡¡ined CireciLl'" eouLd be nade tt ihe tosses detemlned by differenee frorir tTre e:{'rent of ::eeovery" The neihods de'¡el"oped røere then Lo be i:esied oi1 an aciuaL tre or ores" øLL'.t{

Du Experimental, ResuLÈs and Discussion

Io Equipment and ReagenÈs

1" AJcJt_ara_tqg

Lindberg Hevl-Duty 20 KhI electric furnace.

Perkin Elmer 306 Atomic Absorption Spectrophotometer

Unicam SP 90 Atomic Absorption SpectroPhoÈometer

Unicam SP 500 Ultra-Vlolet-Visfble Spectrophotorneter

Baird Àtomlc Sodium Iodide SclnÈillation CounEer

Eplc Inc. Optix Universal Optical Pyromet,er

Sartorlus Type 1802 Microbatance

Ohaus Harvard Ëríp balance

Magnesla Cupelsproduced by Leonard Ltght Industries (Benoni.¡ SouÈh Africa)

Crucfbles produced by A.P" Green Refractorfes (Western Ontarlo o Canada)

2" 4gaEen_ts_ Gold, unftuxed powder (Johnson Matthey & Mallory) S1lver, prec.ipitated powder (Johnson Matthey & Mallory) Lead, 0"004n foil (Matheson Coleman & Bell)

Sllica, about 240 mesh floated powder (ptsher)

Calcium oxider. Baker analyzed reagenË (Canlab)

Sodiu¡n carbonate, Baker analyzed reagent, (Canlab) L1Êharge, Baker Analyzed reagent (Canlab) Lltharge, Anachemia reagent grade (nobson)

ALt acids used were Baker analyeed reagent except hydrobromlc

acid which was the colorless fracÈion obÈained by distillatlon of Ëhe reagent grade acid" 3. Standard Solutions

Gold: Approxlmately 2 grarrs of the meÈal çrere dissol.ved in aqua -22-

'yÊg:t-ã.' NiËr*us æxides were remaved by regreated evaporatj.ons with hydroahlorie in the pnesence of some sodium chLoride, The soLution

røas dil"uf:ed to I" L" by additíon of 0"LN HcT. and sËar.¡,dardized using the

hydroqui.none method aceonding Ër Beamish" seath and Russerr(3i), DiLure

gold soluti.ons v¡ere obtaíned by diLut¡-on r.ríth 0"lN Hcl, For at*míe

absorption standards the matríx was matched v¡iËh the sampl.e,

siï"ver: A stock soLutíon contaíning tr000 p"p"n" of siLver r^ras

prepared by aecurateLy weíghing our 1"0 gnam of che silver powder,

di-ssol,víng in suffíeient HNo, to malce a x. l" volume apÐroximatel.y 0"x"N

in HN03' DíLute síLver sol-utí.ons vrere obtained by dj-Lurion wi"Ëh 0,LN

HN03" For atomic absorption standands the matríx was matehed wíth ttre

sampLe, Lead; A stoek sotutí-on eontaining 1.00 " 3 p,p,m" of, lead vras prepared by accuraËex-y r--vsi*hing 100"3 mg" of Lead f*íl" The nead v¿as

díssætr-vecÏ in 2û må, 5t'l lïNo3 by hearíng on a sËeanr bath for several, hours" Dilutirn tû l- 1", i"ras raade usíng O"LM IINC= vietrding a strek sol-ution 0"2I'I in t{Irl0= and r.0û,3 p"p,m" 3.eacl. Dítute T.ead soi_uËions r'¡ere made from t,he sLoek" For atomic absorpËíon sÈandards Che matrix v¡as rnatehed r,Ïíth the sampLe,

ï1" GeneraX" Consideratíons f Rg jeeålon- oå_{i*s_e.o-rjiqllr_ . -ne_qu_i_rs-

Diseordanf: nesutr"cs r"rere rejee ted for a variety of neasons, trIhen* ever an experimental" souree of error r,aas notie,ed sampLes were rejeeËed, Frszen sr sprÕured beads are examptr"es, Tn addårion earej.*ss pcuring of che fused eha"rge somef-imes resuLred in some of Èhe Lead phase beíng physieal"try Èrapped in the sl.ag" i,Ihenever beads of lead phase arere observed in Èl-re si-aguthe sampl.es veere rejeeted" I'fore rarel.y the eupei.1ed moi.ten beads r*å3.ed nff rhe aupeL ån che proeess *f handling *2,3 *

Tr¿Eh Èhe rupei trngs, sue'h beads vrere símpÏ"y 3_ost- Finaålyoin Êhose eases v'¡here no expsrirnenLal- reasûrr for rejeeLíon of a díseo¡:danl resuj.t ãïas kn$'vrnra statísticaL basis for rejee tion '*'as app!-ied, Tn aj"L such e,âses rejectìon was atr"ways made aË Êhe 957. conf ide¡rce level"

2, l"Igighlng prl¡-e,e_dr¡{e-

ïn order eo derermine the weíght of rhe inítíaT" gof.d taken for

anaLysis and Ëhe finaL rreighL oË parËed beacSoweíghings ç¡ere made on a

miersbaLanee tt the nearest microgran" To obLaín reprod,uaibl.e resuT.Ès

a standard proeedure for making r.reighings had cs be adopted, To

iÏ.lustratereonsíder Ëhe r"reighing of a Èypieatr- parÈed bead, To begin a series of weighångs Ëhe door r"¡as opened and the pan eleaned ç¡ith

a eameï 8s haÍr brush, The door -o¡as then elosed3 25 seconcls *ere

eounted off,; the pans v¡ere rel-easeeS,rand the aero adjusted aÈ rhe end oÍ a seeond 25 seeonci inÊervaL, The glans rr,;ere then arresced; the doon opened; the bead pLaeed on t.he pan and the sarïïe proeedure repeaÈed as for zeroing exeept that at the end of the secend eounting intervan the weight rvas read off. Ts eheck rhe proeedure a 6c mg" go1cl bead was rveighed ten times in suceession, The average weight r.yas 60,3n3 rng, r+iËh an average devÍ.ation of 1"4 mierogram and a range of, 6 micnograms, l"Ihif.e the balanee l"rad been caLíbrated and eorrections raere ax.ways app!'íed, the i'reight of gon-d taken was e*ntroi.Led so thar Èhe same *reíghts eoutrd be used, for the i.níËiaL and finan vreighíngs of tl"¡e golcl. In this t^ra,v it vras hoped io reduee variations i.n the goLcl loss due È@ eatíbraLion drift from day to day,

C-qpel"J ïïI " a tjoJl en4 P-aq eíJUl J,qsJse$_ InE$oduc-Eåon-

Tn an aÈËerapt to eLímínaLe. gold losses norrnally incurred Ín Ëhe fusi'on sEage *f the f,ire assay a series of experiment,s ro,ere eonducted ',2 * ¿i. _

'utiLizing an abbrevíated fí"re assay r+hi.eh has been deseni.bed above as ssimul.ated a eupel 1-aciont " Thai j-s, Eûxd and sixven por.rder røere

aeeurateï-y r-reighed Õut onto a l-ead foiT, ea:refuÏ,Ly foS"ded ËÕ enease

che tr,vo in Lhe Leaclu and rhen cupef.x-ed" lhe fol.ded Èead formed a cube

of ap¡2roxÍrnatety 3/4Tt dåmensions f,on 25 g, Lead" on3.y as a rrnsequenc.e

of subsequent studíes was t.he vatr-Í-dicy of this proeedure eattrecå ínËo

questiÕn" Ïn any case? the resul-ts indieate hor¡¡ that eoneLusíon r,¡as reaehed.. Furthermore, in gond buLx.ion anaLysís the fusion sËep is in faet by-passed sü that cupelX-atíon iosses of'r.¡hat is here referred to

as a simul.ated eupen"lation 'øouÌ.d be eomparabl-e co oupe3. lat.ion I.*sses ln butr"I-ion anaÏ"ysís,

Al"i- aupe!"I.aËions t+ere eonducËed in the sanre marìnÊr, The raagnesía aupe-Ls uzere preheated in the f,urnaee at ihe tårnperatuse used for eupeÌ"1aËiæn" un1ess noËed o{:hem¡ise the temperature ef eupetr }-aËion

'+¡as n-800oF (98?Õt)" The lead buttons pnepared as indi.eaÈed abe¡ve were added to the eupel.s as quickny as ËlossibLe te¡ prevent. an exeessÍve temperacure drop" After an ínitial" heating íntervaL of five rninutes r'riÊh the draft and door el.osed the tr"ead r"pas mol.ten and both dtraft and doo:: were opened. Ttie door oBening Þ¡as contro!"tr-ed by p}aeing a L/htl sËeel. pi.ate under the door. The draft vias a3.r,rays opened Èo E.he sarne e)rËenE by pu3.f.ing a Leven ËoaeonstanE marken. The resu3.ting flow of air eaused the muf,ff.e aÍr teaperacure ro drop approxímateLy 30-50ßF,

Under these conciítíond the tirÍ.ving oi che n-ead ocaurred. at a raËe of approxímatei.y I gram per minute. Thus a 2c gram but{:on r,J*ul"d ne

into the furnaee nean Lhe eupel. at "uvhieh the opcieal" pyreimet.er had been foeused" r+hiXe the coLd end Þras irrirnersed, in an iee baÈh, Ternperature readings by the Lr,¡o methods diífereci by Less than l.Oof, After the riniving stage v:as eomp1eced" the doon (ain suppty) was ci-osed ancl the eupetrlacion finished by heating for a fínal 5 mínutes" Ci.osíng T:he

door caused the muffLe air LernperaLure Eo inerease and ensured essentíaL3"y eor.iplete removatr of rhe Í.ead from Ehe sii.ver-gol-C beads"

A eSeterminatíon of the l"ead eontent of a series of suc,h beads indí¡:ated

an average tread residue of L,4 roierogram.s, Sinee the majoríLy of l:eads "¡?eighed were of the elreler øf. 2C mg" this enror Þras talcen Èo be mf nc ÕtnseqLrenee and ç;.iâs flGt correeteei íor,

AfÈer the cupeÏ.Lati*n I'tas com¡rÌ-ete, the docr T¿ras opened anci ¡he eupel,s t'¡ithCrarrv"n sLeir.ztry in tr.¡o stages st as eo prevent sprouting,

After an ínitial cooLing period of aborrt L mínutêr the eupetr-s l.rere noved to the furnace clsor'+¡here the buttons -*¡ere al lor.¡ed E.o solidifv"

1n Lhe vast majerily e1í beads observed the characteriscíe 1!b1íekil of

a Lead free bead Ìlvas seen, T-Ìre beads r.?ere then al. lor.¡ed to cool for one hour, removed From the cupel"s and "".veighed" Tn the earlíer expeninents, the beads %rere cl-eaned of cupeL rnatenial" by serapieg vrith a ptratinurn spatu!"a ¡:rion to t¡eighing" A l¡Lank determination for goLd eonÈeni of the sitver ponder and

25 gxar:-s of Lead foíl índicaËed no deLeetabne goLd in 4 repÏ-ícaf-e sanpÏ.es" The nodif ied 'orsmaurate spec trophotometrie method of Chor+ and 1"{r\ Beair.isht"^t \qas r¡sed" Tn vier+ of the EorrdiËions used this meant an upper l.ínic of L0 ririerograrns of geLd couLd be set, Iír vier,¡ of a simil.ar

TiLank 'Jeievr4inati*n(2¿+) ü ilizing 1onger e'eLLs ancå reporÈed tr be Lmlerograiae *zo -

;he bLanil again was igt-iøred fcri:he mei::e than 2C r:rg" sanpl-es cf go!d"

îrrors thus iirr:sodueed "¿rilul.d be ai rnûst Û,05i/" and ¡rrobabÍ.y rne re tr ike

"005%, Sinee detc¡:ninaLion of the gcld loss invotved Íneasurernent of the silver eûnËent at the L-?,fL aeeuraay Ï.eveI" thís procedure r,¡ound appear to be justified" '27 -

1, Effect of Lead I,IeighE on cupeLlarion Losses of Gold In order to study the effect of i.ead lreíght on the cupellaLion

loss twelve pieces of Lead foil (.0041r) were cuÈ for each wefght to be

considered. The first series of lead burtons of 6, L2, LB and 24 grarìs was cupelled on 30 gran magnesla cupels, The second series of

24, 32 and 40 grams was cupelled on 40 gram cupels. . rn each case

approximatel.y 20-30 ¡ugs. of gold was taken '+rith about three Èo four times as ¡ruch silver" I^Iith such a silver to gold raÈio a one hour parting treaËnent aË sË,eam bath temperatures ÌriËh 10 mL. of 1:2 nitric acid (acid:waËer) r¡as required Èo obtaÍn an adequaËe removal of silver.

The Parced bead was rrashed three times r,riEh hot water, annealed over a bunsen burneroand treighed, In almost all cases the parÈed bead welghed more than the gold added in the first pLace, In addftlonrthis differencen or surcharge, varied consfderably from sample to sample. rn view of the foregoíng and the claim reporÈed by coxsn(20) that signiflcanr amounis of sí1ver are retained by Ehe parted beads it, r¡as deemed necessary to analyse each parted bead for sitver content.

To do thlsrthe parted bead +ras dissolved in 3 nl" aqua regia wiÈh genÈle heaËing. The beads reacted lsr¡Tediately and dissolved cornpletely within the one hour digesElon period nonaally a1lowed, sufflcient concentrated hydrochloric acid was added to cornpletely complex all of Èhe s1lver, follosred by dilution Èo an appropriate volume so that the silver concentration would be between 2-10 p.p.n. rn this reglon the atomlc absorption callbraLion curve r,¡as linear. Standards were made up wlch the sÈock silver solutlon (above)1 and Èhe maLrix $ras maÈched wlth the sarnples" the weight of sflver found ç¡as Èhen deducted frorn the weight of rhe parred bead ro yield Èhe welght of gold found or recovered, T'he difference between gold added and found, represenÈed -2&*

tha gol"d loss" The resul-Ès of bo'¿h series *f experímerrts (30 and 4C g., er-rpe?.s) are f,ound ín Table I, ilrorn them it eai: "oe seen that the sold

r€overy çarj-ec f::*r:r 99 "37^99"39% î.ax 3c gran eupel"s (f årsr four pages of, the tabLe) ard varied from. 99,37-99"¿vt+,"/" nør 4û grarn cupex.s (lasr three pases oi the tabLe)" Thís represents a range ,:f abor:t 7 parts

in 10,CjA t.or all rriatr s"

To í:est røheiher there ?rere any sígnifíeant differences berr"¡een

i:he trial"s a test of significanee r¡ras appl_í.ed" A eomparison of the

resuLts for 3C g, cugreX.s indíeated no signíficani: difference at the 99% eonfÍdence leve}", síz¡i1arLy for the experíments using 40 s" cupels no sígnlfl-eant differenee rvas observed" A grou¡2íng oE a3.1- experimen'cs using 30 g" eupels led to an average vai_ue l,¿hieh sras c,rinpared to a grouping of, the resutLs r.¡ith 4Û g" cupens" Agaín at ihe 99% conficienee

Level there r",.?âS Do sí3nificant differenee" As a resuLt al"l" vaLues of

Ëhe goLd loss couLd ì:e groupeCr together g:i.rring an overalJ. average goT-C

-l-oss of a"6L% r,¡ith a standard devíation aî- a.aB%. nxpressed as a gcld reeover)¡r,this rçouLd be a 99"39% goLd recc,very.

Frorn the foregoíng it v¡ouLd appeat: that S"osses of gold in the sinuX.ated er-rpeLLation do nst vary signifieancLy as a function of Learl tveighi used or¡er tb.e range *t 6-4a grans. aL the confid.enee trevel indicaÈed,

rt shouLcl be pointecl out thac for one triaL, using tr2 grar:rs of l-ead, the Læss of goLd ?.:as found r¿¡ be anornolousLy high at L"3.8% çyirh a corresFr:ndir-lgny higir siand.ard der¡iation af. Ð"65%. Ne experí-menLal- reason r'¡as iino',,yn" Thís i:rian" varí-ed signif,ic.ant}l' f::orä atr1 the qlthe::

Ëríal"s ac the 99% cønî.idenee l-evelu and therefore tøas rejected and repear:eel" T'l'Le repeat is rëF8rrec? in Tabne r, ;\ su-rr-mary of al"l- fihe resuLts fs¡: tiris siudy is found ín Tabl"e IT" TABÏ,8 T

Effeet of Lead WetghÈ On Cupetr laLion

Losses of GoLd Pb lüeight Au Added Ag Added Sum Parted Bead Sureharge Ag ReËalned Au Found Au Loss Au Loss 7" (e" ) (*e" ) (te" ) (ms) (ote" ) (mg' ) (te. ) (me, ) (rg. )

6 L9 401 83"9 1 0 0.B0 "02 " 65,0 9,430 "a29 0"185 L9"24s c"156

6 L9.770 59 78.7 L9, BB4 0,1n4 0"218 L9 0 T"04 0.53 "02 "2 "666 "

6.02 25 550 7r 96 25.702 0.L52 0 25.t+Lz 0, 0"61" " ,3 "4 "290 r.38

6"03 22"6L0 63 "9 85"8 22.74s 0.t35 0. 268 22"477 0"133 0"59

6.02 20 64.6 84. B 20 868 0 20 o "76s " 0,t03 "23L "638 "L27 0"6L

6,01 2t+"333 75"3 99.2 2¿È"483 0"tr50 0.264 24"2L9 0" x.14 0 0 "47 Êg \o 6 L 8, 051 57 74"7 0,043 0,1"55 "02 "t+ 18.094 1"7.939 0.1t2 0 "62

6"03 L9 57 76.L L9 0"094 0"205 19,159 0 r.11 0, 58 "270 "4 "364 "

6 "02 23 "429 60.4 83"s 23.486 0"057 0,n93 23 "293 0"L36 0,59

6,01 2¿+"296 76 "L 99 "4 24"255 -0,041 0"L61 24.O9t+ 0 "202 0,93

6 2L.6BL 65 85,6 2L CI tr"30 2L,5¿+B 0, 133 0"6L "03 "2 "678 -0 "003 "

6 ,03 2s "629 83"L LO7 "6 25.682 0.053 0, 1B5 25 "497 0"t32 o "52 Average GoLd Reeovery 99"39% Average % Loss 0"6L"/.

s : 0"X0 Pb lttefghr Au Added Ag Added Sum Parted Bead Sureharge Ag Retained Au Found Au Loss Au toss (e" ) (*e" ) (*s. ) (*e" ) (*e" ) (*e" ) (*e" ) (*g" ) (mg" )

tr 1" 97 2A "062 s9"5 78.5 2\"293 0"23X. 0" 351_ 20 .942 *-0,860

1L"99 25 t+46 82"9 106 25 n 100 0 " "7 "6¿+5 ^392 25.253 0,L93 u" /o

11"97 2L "74s 65 "4 85"B 2L "9s3 0.208 0"341 2L "6L2 0. r.33 0.61

I 2,00 30,247 t06"i" 134" 5 30 a 0"450 "474 "227 30 "024 o "223 \) " l(t.

1-L.99 30 8r.0 86 f.i.5.2 3L,223 0 4r.3 0"543 3C,680 0, 0 " "2 " x30 "42

r.1" 9B 27 8L5 96 L22"4 27 0"047 0 32r. " "3 "962 " 27.64L 0"174 0.63

r.1 , 99 23 90, s LL?.4 2t+ 0,1"09 0,276 23.8L7 0 1.67 0"70 "984 "093 " g (¡,o 11"98 26.L99 72,5 YI.L 26 0 0"540 26.036 0 1"63 a 0 "s76 "377 " "62 11 00 Ï.9. 7n.8 )o" / 7s"L L9 "8L7 0"099 0,23¿+ I 9. sB3 0. L35 0"68

1T ,99 L9 s4"2 72,6 1 9, s01 0"089 0 25X. L9 o "4L2 " "250 "L62 0"84

11.98 22.0t+O 7 9¿+"9 4.4 22.Lâs 0"n05 0 "204 2L "94L 0"099 0"45

L1,9B L8 52"s 70"4 1"9" 110 0 L88 0.278 x.B"B32 0 "922 " .090 0"48

Average Gotd Reeovery : 99,37% Average % Loss : 0,63

s: 0"1.3 ,AO Pb T,Ieight Au Àdded Ag Addecf Sum Parted Bead Sureharge '^b Retained Au Found Au Loss Au Loss % (e' ) (*e" ) (*e, ) (me" ) (*e" ) ('c" ) (mg, ) (me" ) (*8" )

1B 0L 25 97 26 0 0" " "966 "3 L?L.9 "o78 ,LLz 0,252 25.827 0,139 54

r_8"00 29 "Br7 82"3 111,0 30"012 c . 1.9s 0 ,385 29 "627 0"L90 0.64

t 8"02 x.9 05L 70 89 L9 0"086 o,242 t"B nÁ1 " "9 "2 "L37 " 93s 0.1L6

1B,00 23 67 90"0 23 0"t7n 23 "6A7 "L "778 0.305 "t$73 0, 1.34 0"57

t B,0r. 1.8. BBB 59 "2 77 "5 1B"909 0,021 0. x_55 18, 754 0"134 0"71

r.8 00 23,L66 87 23 0"081 (r, " o)") "5 "2t+7 4.224 23.027 0, tr_39 0.60 0 ln nt fì noo 23,44s 78 "2 100"8 23. s44 0,248 23 "296 0,149 ^At

L8"Otr 24"LO6 66"0 90"0 24"287 0"181 0 31.0 23 0"136 0. " "970 s6

LE"02 LB 063 54,5 72"3 l_B 042 -0 021 0, x.18 L7,924 0. 139 4,77 " " "

n_8.0L 2A 6x. ,6 BN.. B 20 0.01_7 0 1"47 20 0"130 "772 "789 " "642 0,6s

18"00 3L"644 92.3 3L 755 0"11_r. o t+7 7 rì qî L22.s " "278 31" , 0, r.67

3" 7, 98 24,785 67 ,7 92.0 24,864 0 "a79 0,25L 24"6L3 o "L72 0.69

Average Gold Recovêry = 99 "37% Average % Loss : 0,63 0"07 Pb f,Ieight Added Sum Au Ag Added Parted Bead Surcharge Ag ReÊaÍned Au Found Au Loss Au Loss % (g. (rne" ) (*e' ) ) (*e, ) (*e" ) (*e" ) (*s, ) (*e" ) (*e. )

23.99 3s r.37,0 35 0, "773 112"8 " 960 tr"87 0,389 3s,571 0,202 0"56

24,02 20.572 67 86, 9 .L 20.647 0,07s 0" 219 20 "428 0,144 0.70 24"02 20,804 76 96,6 "B 20"875 0"071" 0"202 20 "673 0,13r. 0"63 23 25,I+35 77 LOZ"I_ "86 "6 25.55L 0.116 0 "276 25 "275 0, 160 0,63 2¿+"02 24.705 74.0 97 ,9 24.8L0 0"10s 0,2&7 24"s63 0.142 0"58

24"02 25,302 59, Br+"2 B 2s"&a9 0.LCI7 0"284 25 0,177 0 70 0 "L25 " u, N) 24.02 2s "L42 7L "4 95 "7 25"243 0"X.01 0,244 24.999 0"n 43 t"s7 B

21- 460 2t+"OZ " 67.5 88"3 2L.562 0"102 0"222 2L"340 0"L20 0,56

23"97 20,906 57 78,0 0, "6 20.929 0,023 r.s3 20 "776 0,130 a "62

23"99 20"768 64" 5 84,4 20 0"007 0"i.37 20 638 "775 " 0,130 a"62

24,01 1.B,360 59,1 77 18"363 0.003 0.131 L9 0 "5 "232 " 128 0,66 2[+,03 2X.,334 62"5 93"3 2I"376 0,042 0"L62 2L"2L4 0"1.20 0,56 Average Gol"d : Reeovery 99 "38% Average%Loss : 0,62 s : 0"05 Pb l^Ieíght Au Added Ag Addeci Sum Parted Bead Surcharge Ag RetaÍned Au Found Au Loss Au Loss % (e") (me.) (*e") (me.) (mg') (rng") (*s') (*g") (*s")

2¿+"00 27.602 83"2 LI0"7 27 "748 0"T.46 0"437 27 "3LL 0,291 I .05

0 0,1tr 6 0"52 24"03 22,283 6L.7 84,2 22,579 " 29s 0,4L2 22.L67

o 0 26 0, l-56 u"fv 23 "99 26 "647 76 "6 LA2"7 26 "9L2 "265 " 42X" ,t+gL

24" 03 21 044 73.3 93 2L 0, tr 08 0 241 20 9Ltr 0.133 0"63 " "6 "L52 " " 23"98 22,54t+ 70"L 92"4 22"698 0 "L5¿+ O "278 22,¿v20 A "L24 0, 55

0 24,00 22"9A9 6L,L 83"6 23"260 0"3s1- 0"448 22"8L2 0"097 0,42 (¡¡ q¡,

0 t+"2 0 0 2L 0 138 n r.o 23"99 22,06L 7 95"2 22,L85 .L24 .262 "923 "

0 0 0, n 28 o 23,99 22" 384 BO"B 102" 5 22,543 " 1L9 "2t4.7 22"256 "57 24,00 2s r.01,4 Lzs 25 0 01+B 0, 205 24.947 0, L57 0.63 "LOh "4 "Ls? "

â3,99 22"036 82" 6 tr 05" 3 22.090 0,06/+ 0"185 2L"905 0.13L 0"s5

0" 0 0.7L 23 "98 L9.9t+5 s9.7 79 ,2 20,0X.3 0 "068 21CI 19,803 "L42 0,161 23"98 2¿+,851 69 "t+ 1.03, ? ?,s.008 0,157 0"318 24"690 0'il- Average GoLd Recovêry = 99"4L% Average % Loss 0,59

q 0 ,08 Pb Weight Au *\dded Ag Added Sum Parted Bead Sureharge Ag Re tained Au Found Au Loss Au Loss (me. (e" ) (me" ) (*e' ) (*e, ) (ms" ) (*s' ) (tg' ) (me" ) )

1"t+L.2 169 29 .4L6 0.090 a,26L 29 a .L7L 0, 58 32.A9 29 "326 " 1. "Lss

0 1_97 1 9 ,928 0,1_1L 0"55 32"05 20.039 6L"T 8L,2 20,L25 0.086 "

31"96 22"s63 72"O 94.5 22"656 0"093 o "224 22.t+32 0"131 0" sB

0,1.15 O 25,91"8 0"1s9 0.6n 32,03 26 "077 7L "2 96.9 26 "L92 "27t+

o 0"17X 20 0 0,69 3tr 20.826 69.6 9C"1 20,8s3 "427 "682 " 1"4¿Ë "98 0 (Á, 0"161 0,206 2L"674 0"045 0"21ìr &. 32"02 2n,7L9 7A "2 9L.6 21.880 0.346 32.720 0"s6 32"O2 32" 903 88" 0 120, s 33 "066 0,l-63 0,183 q1 L L7 0 ,040 0"16s 1-7 o.L25 0,72, 32"00 L7 "48¿+ 69.6 "52¿+ "359

a 0,tr36 2L 0.1"07 A 32,02 22.0A9 83"0 L04, B 22.038 "029 "902 "¿+9

0 ,090 L8 280 0,130 0,7n" 32"02 L 8,410 66 "4 Btu."7 18,374 -0 ,036 "

n"B 429 54, s 73.7 L8"424 -0 ,005 0.L32 L8"292 0,L37 0,74 3t " 99 " 0,065 0.2L2 0.1.47 31"88 2L"220 65 "9 87 "2 2r"285 2L.073 %32 Average Gold Reaovetry : 99"37% Average%Loss= 0"63 s = 0"08

rejected on sËatlstical grounds Pb Ï,Ietght Au Added Ag Added Srmr Parted Bead Surcharge Ag Retained Au Found Au Loss Au Loss (me" (a') (me" ) ('e' ) (*e" ) (me' ) (*s" ) (me" ) (*e. ) )

21" O .A94 o 2L 0 ,002 0,01rr 39 "97 2L.7L\ 69"8 9L.6 BOs "096 "709

0 0"168 1-9 0, 088 0 45 39 "99 L9 "437 58"B 7e"6 L9 ,5L7 "080 "3¿r9 " 0"65 39,98 29.870 L02" 0 13L,4 29 "983 0 "1g3 0,308 29 "675 0,L95

27 0"L03 0,239 27 0 135 0.49 40"0L 27 "300 96 "6 L23,6 "403 "L65 "

¿r0,0L 23.9L7 61" B B5,B 2¿+"LL6 0"L99 0"346 23.770 0"1.47 0"61

39 22"022 6B,9 91,L 22"L37 0,L15 0"248 21,889 0"L33 0"60 &, "96 UT 6 10 0q 0"tr68 O"2BB Zlç,Ct¡l+ 0"120 iJ,50 2t+"L6¿+ 69 "6 93,9 24"332

40 ,00 23,030 67 .0 90,4 23.L72 A ,L42 a,269 22"903 0.L27 0"55

0 t 0,59 39"95 2¿$.559 76 "6 101,1 24.6L2 "c53 "L99 24"4L3 0,1"46 "i.8.6L7 40.00 18, 73s 73. L 92"2 L8,728 -A,OA7 0,11.1 0,118 0"63

. 9L"4 0 0,228 24"923 0"L79 0"7L 39"98 25 "LÐ2 LL6.2 25"L5L "049

¿$0 27 0"157 0.362 27 0 10s a_"_3_8 "00 27 "66L 76 "2 103"7 "BLB "&56 "

Average Gol,ci Recovery : 99 -41+% Average%Loss :0"56 s:0"L0

rejected on statlsticaL grounds -36-

TABLE ÏI

Summary of Effect of Lead l.Ieight On

CupenT.ation Losses of Gol.d

lleighÈ Lead Au Loss % ò

6"0 grams u, o.!. 0"x"0

L2"0 0.63 0, r.3 30 g, eupel"s

1"8,0 0,63 0n7 Average Au Loss o,62

24"0 0 "62 0"05 Þ- 0 ,08 2t+"A 0"59 0"08 1 40 e, cupetr s 32,0 0"63 0,08 I Average Au Loss 0, s9 I 40"0 0, s6 0"1CI S: 0,09

OveralL Average Au Loss %: 0"6L s : 0"08 -37 -

Ef,feet o-f SiLr¡er ro GoÌ"d Rati* on Cupel]-aiion Losses of Goi.d

Tne +bjecÍ:il'e of chis sLudy l.¡as ¡ô see hotv ¿oLci losses wouLd vary dur:i.n3 eupenS-atien as a result of varyi-ng the siL'ver to gold raËio. Tn f:heo::;'ihis can be accon':Lisheei by inc::easín3 the amúunl of silver,

*r by deereasiirg che amÕunt of gotd or both" Tn praetise decreasing the anount of 3olci is Linited by r:he r,rei-ghinl errór '",rhereas increasing i:he amor¡nt of siLver is LimiÈed by the aapacity of the partíng acid to dåssolve it" Far convenåence the sCudy was begun r+ÍÈh a seri.es of

sarnptr.es eontaining abour 2Û mg, gold and Ëen tímes as rnueh sil"ven' A

second triaL eonLaíning about 5 mg. gerl-d and Cen Línres as mueh sil.ver

?fas cilrilpared to the fírst tû see tyheehe:: the quantiëy of golcl had any

significant effect, Tr"ro more triaÌ,s fol"lov¡ed ln røhich the siX-ver Í-o

goT.cl rai:í,o T"?âs increased tc¡ 20:tr,0 anci 30:1,'r'eeping rhe go3.d lveight

approxÍrnate1"y censtant aÈ 5 ng" To enhanee the tendency of the Fari:ed beads to rem.ain eÕherenE, thereby redueíng nteehanfea3" tosses, a rûôi:e

dil"ute parLing aeid çyas used, Tn al"l €ases 6 rnL" i.:6 nÍtríc (acÍd: water) r,¡as used çyi¡h a tr- hour dígestíon period of the beads aE steam bath temperaEures, The resídue r¡as washed three tímes r"vith hÕt r,¡atere

anneal.ed, and rveighed on the mierobalance" The sll.ver conEent of the

parted bead -sras detecnined in the si:andard vray ouËXined ín the previous

s tudy " Tn order Lo reduee the sil-ver retained, the beads oTrtained frorn

the eupeï.tration proeess "*yere fLattened mn a hydrauS.ie press prior to pareiftg, \+híLe a l"ater study índieated Lha-t this effecr 'is aehieved-

¿t sÕme extent, the effeeL of using a rntre díl"ute pariing aeid nore than offsets the effeer of a redueLion ia thiekness" Thus the si.l,ver seËained in this study alreraged o',46% as eônpared to an average of

,L"A?% i.n the previous study" A Later study shæwed thaË Ehe teråperature -38-

Õf, Che pa1¿trír,g aeíd had an impo::tant bearing tn tïiís faaÈer"

The detaíf.ed resutr ts of thj-s study are to be fouad in TabLe ÏII c+iEh a sumnasy in TabLe I\¡" A eor,r¡parisæn of the fírst tç¿s tníal-s ef eonstanÈ sílver to gotd rat,io (lO:t) and va::yíng goT.d vreight índieaies no signifíeanË difference due to goT-d wefghc ai the 99iå confidenee teveL" A compaÍisÐn of the remainíng Èhree Lria3"s at consÈant goLd îseighl (5 ng,) and varyíng silver to gol-d raLio indieates a rninimum

golcl !.oss for a maxj.mllrn siLver to gold raËio but no eonsisLent

pactern emerges r,yíf:h ns signíiicant c{ifierences aË the usuatr confídenee

l"eveL af. 99%" Thus iÈ seens safe to conel-ude thai there is no significant effeet on goLd l-osses during eupel"!.ation and parting as a result CIf varying ¡ïre síl.ver to gûX-d ratie¡ frsm LCI-30:1-'0' I,Ihii"e no experiments r,¡ere eontiucted aË siLver Lo goLd ratios

Less chan L0:L the overall average goLd tross of 0,6L% for thís eomptrete study ís ídentical v¡iih the goX-d l"osses for rhe previous study çshene

fhe siÌ.ver EÕ gûT-d raLio t*'as in the range of about.3"5:L"0" This inspÍ.te of a mueh stronger (1;2) parting aaid Ín Ëhe tratter case" Since sii.ver to goi.d saËios !-ov¡er Ëhan 2"5:1-"0 are rÌoc

seeonurended in the l"iEerature" Lhere seemed ne poínÈ i.n exEending Èhis

study beyoncl the above" The average goLd reeo\tery ranged from

1" per ¿housand. 99 "32-99 "43%, a díf f erence of onl-y ParÈ

3, Effeet of Parting Proeedure On GoLd- Losses

/+rr 61? In Lhis study ai.3. the sampi.es \,¡ere eupetried v¡íth x x '001+11

Lead fciL. Since tr"ead t,reíght hari been denonsËrated Èo have no effeet

Ðn góÌ"d tr-ossesu variaf-íons in Lead t,reight r,¡ere of no eonsequenee. Thus

the r,:eight ehosen 1,¡as an arbítrary choice somewhere r+íthln ihe range rABr,E TrT

Effect of Silven t0 Gold Ratio on CupelLaÈion

Losses of GoLd Ag:Au Au Added Ag Added Sum Parted Bead Surcharge Ag Retaíned Au Found Au Loss Au I-oss 7. (me, ) (*e' ) (rng" ) (*e" ) (*e" ) (mg, ) (*e" ) (*e" )

11"0:1"0 18"90n 207 ,B 223"2 L9.L67 0.266 0 ,355 ].8 , 81- 2 0,089 0"47 rì t xo 10.0 :1 ,0 2L "A6s 2L0.2 227,4 2L"299 0.23¿+ 0,373 20 "926 v d LJ / 0"66 o ?9 9,9 :1 ,0 20 "704 205"4 222"6 20 "996 0 "296 0.362 20 "634 0,066

1aL ¿ ÒVAV Árn L9 o 0.332 19"505 0 tr.5 u, X.0,0:1" "0 n96,B 2\Z"B "837 "zLV " )y

0 0,315 1B 820 0"013 0 T.0,1 ¡L ,0 LB"833 L90.2 205,8 r.9, L35 "302 " ,0 7r'

20 206 222"9 0 0 20,340 0"104 u")L 1-0"1:1"0 "444 "O 20,708 "279 ,368 l_0,I t,0 L9 x.96 5 2L2"6 L9.6L2 0,205 0,3x.B L9 0"1I"3 0"58 "407 " "294 (rá \Ð tr 0"0 t"0 L9.626 L 96,I 2L3,0 Ì.9"837 A "zLL 0"389 ï9.448 0,178 0"91 B

10"0 1"0 2L.34¿r 2L3,8 232,0 2L "s93 O "2t+9 0"366 2L.227 0, r.17 0"55 oo 1"0 20.3s6 200,5 2L8.4 20 "63L o "2v5 a "4L7 2t "2L4 0"142 o "70

oo 22"\05 2L7 236 22"4L2 0,307 0"449 2L 0"042 0 19*' t,0 "9 "7 "963 "

1.0.0 tr 95"0 2LL 19 618 o.233 o L9 O, OBB or.4Þ [.0 t9"3Bs "B " "32L "297 -

Average Au Loss % 0. 57

0, x6

rejected on statístican grounds Au Added Ag:Au Ag Added Sum Parted Bead Surehange Ag Retained Au Found Au Loss Au Loss 7. (me, (*e' ) ) (*e" ) (¡ng, ) (*e' ) (ms" ) (*g- ) ('e" ) co I 10,0 :1 ,0 5 ,22'1" 56.6 s.278 0"057 0"072 5,206 0"015 Q "29'!. 10,L:1,0 4"825 48.7 s3,0 4,953 0,028 0 ,057 4"796 0"029 0"60 n0,2:X-"0 4"820 49" o I s3.1 4.846 "026 0"059 4.787 0"033 0"68 qq q 3.0,0:L"0 5,587 60 s,618 0 031. 0,069 5 0 038. "¿+ " "s49 " 0"68 10,0:L 4"828 48.1 50,9 tï"8t+9 0,02r. 0,058 4"79L 0,037 0.77 I "0 &Õ û 10.0:1 5,710 tr7 n 6r."4 "0 5.7 47 0"037 0, c69 5 "678 0,032 0. s6 10,3:l-,0 5"184 fJ"I 57 .L 5,226 0.042 0,069 5 "L57 o "027 0,52 L0"L:1-"0 5.03X. s0,9 5s"1 5"066 0"035 0"065 5 ,00tr 0"03n a "62 9,9:1 "0 4,824 47 "8 5L.B 4"852 0,028 0"055 4.7 97 0,027 0.58 I0"?:1"0 4" 935 50. 2 s4.2 4"969 0,034 0.066 4" 903 0,032 0,65

5,5L7 55, s 10,0:L,0 60"1 s"563 0"046 o "a77 5.486 0"03r. 0.56

10,0:1,0 5"L25 5L"2 55"3 ), t_oo 0 04x. 0 .068 5 A 0, " ,098 "027 5-5- Average Au Loss %: 0,62 s : 0"07 rejected on sEat.isLical grounds Ag:Au Au Added Ag Added Sum Parted Bead Surcharge Ag Retained Au Found Au Loss Au Loss % (ms" ) (*e" ) ('ne" ) (mg, ) (*e' ) (me" ) (me" ) (*e" ) 20,0:1 "0 5,854 LL7 "7 T?L.5 5.886 0 "032 0,112 5,854 0 ,080 I ,37Jr 20"0:1- "0 4"825 96,2 oo¿ 4" B6t 0"036 0 ,071 4"790 0"035 0"73

9L 0 0 1-8"3:l-"0 4"987 "t+ 95"0 5.029 "0¿rz "07t+ 4"955 0"032 0,64

L04" 6 LO7 0 1., 20.0:1"0 5.243 "9 5,290 "047 0,087 5"203 0"040 " /0

20"0:L "0 5,147 103"1 106.4 s "L72 0 ,025 a "076 5.096 0,049 0"95 &0 g 20,1:L"0 4"91-8 oor 102" 6 t+"960 0"042 0.072 4, BB8 0,030 nÁf

Qn 1 L9"9;L,0 4"926 101"4 4,979 0"053 0"075 4"904 0 "422 0,45

4"875 97.4 L0Ì. 3 4.926 u"uf.[ 0 4,848 o 0, 55 20"0:1,0 " "o7B "427 20"0:1"0 5.1"39 LOz"L 10s" 6 5.188 0,049 0"085 s"L03 0,036 0"70

20,0 :1 4,9¿¡3 98,6 L42"2 ¿ oon a o ¿+ 0.030 0.6r ,0 "047 "077 "0.1L3

5"048 i"01 3 0"040 o 20"1:1",0 " 104,9 5,088 "077 5,011 0"037 0"73

4"850 96 tr00"4 4" 900 0 O. OBB 0 038 0_.-7-B X.9,9:1-,0 "7 .050 4,BLZ "

Average Au Loss % 0,68

c c"i.3

rejected 0n statístlcaL grounds Au Loss Au Loss 7" Àg:Au Au Added Ag Added Sum Parted Bead Surcharge Ag Retained Au Found (mg" (ns. (me" (mg, ) (me" ) (mg, ) (me, ) ('e' ) ) ) )

0 ,03L 0"057 4.938 0,026 0"53 30,2:1,0 t+,964 Lt+9 "9 1.52"L 4,995 Ã qoR 0 5"484 0,041 0"74 0 154" 1" 156, s 5"548 0,023 "06¿* 28,0 :L " aì n?? 5"0tr9 o 0"63 :1 0 5,051 1sJ. , B 154.1 5"073 0"054 "432 30,0 " 2a4"7 6.435 0"040 0,c77 6 ,358 0"037 0"58 32,5:1, "0 6"39s 202"2 R 0"032 0"055 0 0.46 &* 30,2:1,0 5"U)) L52,7 L54"9 5"087 ^10 "423 t\Ð 0 5. BB7 0"025 0"069 s.8LB 0"044 a "76 30"0:1,0 5.862 L76 "s ]r lV "O 30"0:L"0 ¿+,851 145"s Lt+7.8 4. BB2 0"020 0"054 4"828 0"023 0"¿*B 0,030 0"06n s 0 03i. 0, 59 30"1:L.0 5 "279 1s9 "0 L6L,6 5 "309 "248 "

1'l+7 0 0"058 4"798 0"035 0 30"0:1"0 4,833 L 45. X. .3 4" Bs6 ,023 "73 0,078 6 ,181 0,025 0"40 0 6.206 1" 86, 9 190"6 6 0"053 3C,0 ;1 " "259 6 0 0¿+3 0,63 244"3 208"0 6,857 0"041 0,084 "773 " 29 "9 zL "0 6,8L6

n '! 5 0 031. 0_"_59 90 Q.1 n J. JJU L59"3 Á1 5"360 0"030 0,061- "299 "

Average Au Loss % 0"s9

s 0"r"1 TABI,E TV

Sr:nrnary of $llver to Gold Ratåo Effeat

On CupetrlaËfon Losses ef Gold

Sureharge s Ag Retained Au Loss 7. Au Added Ag:Au s Thíckness s f ot \ ( ( me \lol t*-\¡rrò, /\ ínch ) (i,rch r. r,ir ) " ) ñ t¿ 0"57 ô rf^ ?0"t48 10,1"¡1"0 0,3 0,0347 L"3 0,256 0'036 tr"80 0"08 a nô7 ), TJ+ 10"tr:1"0 0"n 0,0230 3,5 0"036 0"0L0 L "27 "62 0 ar 1â &\ 0'008 L.s9 0"].4 0 ,68 &, 5,063 19"9:L,0 0,5 0"0290 1.3 0"043 0 0"59 ô 11 )")r(È 30,L:i-,0 f-,0 0,0274 0"4 0"031 0"0Í,0 L"X.6 0"05 *&t4- of l"ead weighr núrma3.]-y tal:.en fo:: cupeåLatí*n ( ¿, e, ?CI g' ) " The weíght of gald Èaken was apprtxinaLeX-,v 20-30 ng, and beL¡"¡een 6 and 7 tímes as mueh sitver, In Che first five g:roeeduresethe tíne of eonLaat bei:r,yeen the preheated aeid and the gol"d-sín-ver pritÌ- t'¡as 35 rûinutes' trn erder to deterrûi.ne rhe eifeet cf a seeond parting, Lrj-at VI involved a see<¡nC partí-ng u"¡ith a more cûÏìeenLrated ae id" An. earlíer attempt to reduce the sii.ver ctntenc'¿ilh a seeond pârríng had preved to be of no ef f,eeË, Tnis r,,ras in âgliee,nent wiÈh the f inding o¡ Chu*(24)' Ho*¡ever in both earlier trial-s fhe beaels had been anneatred prior L0 the seeond parLing. In procedure vI the beads \}ïere anneatr ed cnÏ"y after the based on second í)arÈi.ng Lreatmeût, The time of ctrígestiOn ühosenrr'ras the i:ime::ecuired fos action (er"c3-rrtion of nitrogen oxides) to cease ín fhe nost då1"ute aei.d, The i:íme oJ: ctnLae.t f,o:: proeedure VÏ t+as Y"'rere x.5 nínutes f.*r each strength of aaid. The pa::ting acids taïëfulïy

Ceeanted and Che 1¡eads t:¡ashed lhree Límes tt¡ith hot ïaaLer' Af Ler r*ashing th.e baads \.Iere careful-ly anneaLed over a bunsen flarne nrhil"e stiLL tn the 3c ml-" beal:ers used for parËíng" The beads T"ere ther¿ weíghed and anatyaeå' íor_ sitve:r etntenc as usual" The oLher variabte rqhich v¡as systematícal 11' varied l'7as the thiehness of the gtlld-sítr.ver bead, Beads r'¡ere either ntË fLattened

at atr"l- (Proeedures III and VT) e¡r fLattened io either 50 or 25

Chousand.th of an j-neh" For f,latteaing the beads îrrere plaeed in the bet'rreen'È\'fß hotr-e of a meial "r.¡asher of; the appropriat.e thickness, stainl"ess steel" pÏ'aLes cn a hlidsaul-ie press' The ee'se v¡ith r¡¡hích the cesinec thiekness aould be aehieved. depenced a great deal" en the Lotal"

siae aî bead" Table''"¡givesadeiaíIediabu].atíonofLlreresuS"tsandTab].e

l¡l is a suÍrlnary *f the sarïe. Fr*m tlreseu the fon"i.mr+íng ¿eneralirzaEi#ns TABLE V

Ef fec i of Parting Preeedr:re

Gond Losses Partíng Procedure Ï

Acid Strength: L:6 (conc. HNO3:HrO) FLattened Lo a Thiclcness of 0"0504 inehn s : 0'0009 ineh

Au Added Ag Ac3ded Sum Parted Bead Sureharge Ag Retained Au Found Au Loss Au Loss % (*e' ) (*g" ) (*4" ) (me' ) (*e" ) (me, ) (ms" ) (*s' )

23 0 491 0,71"5 23 4.224 0"96 " 285 1"52"5 L73.9 23.776 " "O6L

21 0 0"943 2A 4A 0 r-x.6 0. s6 ?.0 " 8s6 116, s 13s " 4 .683 "827 "7 "

?0"1s2 12n,5 L40"2 20,733 O,sBÏ. 0,704 2A "029 0"n23 0 ,6Ï"

0 0"9L4 040 23 0, x.26 0, s3 &* 23"850 i"33,5 !.55"7 2¿þ"76t+ L "724 tjl I 0"758 2L "702 0, n"r"7 0"s4

0 1-9, s2tr 0 r.23 0,63 L9.6t+4 116"9 l-35,0 2t.220 0"576 "699 "

20 A.LL? 0. s4 20,803 129,s 14S.I 2L,37L 0"568 0"680 "691" ?0"028 L26,3 14s,1 20" s63 C, s3s U, O)g L9,9A7 0, i.21 0.60

25"062 1s4"7 L78.3 25,6/+8 0"586 0 "766 2d+, BBz 0"nB0 ^79

0 81.0 0 , 14.5 0"67 2L.6sr+ 13L"9 152"3 22"31-9 0'665 " ?1,509

0 23 0"203 0,85 23.9L9 L75 "7 L97 .6 2t+.4L5 o "¿+96 "699 "7L6 'l-77 2 ñ)'ic 2¿þ.L22 ,t+ L99.6 24.3L9 A "L97rr 0"68s 23,63¿* 0,488

Average Au Loss % :;

:'; rejeeLed sinee the bead brolce on annealing wiÈh loss of Þ : 0,1.4

some eotd Parting Proceclure 11

Ae icl S trength : i. :6 ( conc. ÏINO, :H2O ) FlatËened to a Thickness of 0"0249 ínch s : 0.0006 inch

Au Added Ag Added Sum Parted Bead Surcharge Ag Retaíned Au Found Au Loss Au Loss % (*s" ) (*e. ) (*g" ) (*g' ) (rng, ) (*e" ) (me" ) (*e" )

L9.479 L32"7 149. I 20"090 0"611 0"71B L9 "372 0,107 0.55

0.949 2C,BC5 0 1"43 0"68 20" 948 L34"B 153 , ¿+ 2L "7 5t+ 0,806 " n Ác L9"t4'97 L23'L 14.0,6 20"350 0"853 0"990 L9 "37C 0.L27

X.9 , 75L 123 , ¿¡ L¿'"L ,2 20,3L5 0,564 0"685 19"630 0,121 0"6L Õ.F. 0 20 0"1L3 0"s6 2A ,27 5 1" 40,6 15B, 9 20 "7L6 c"441 0"554 "L62

n" 40 20 0,4¿+5 0"565 20,2L0 0, L20 0. 59 20 " 330 ,0 15B,3 "775

23 .011 1" 45, s L66"0 23.600 0"s89 0"705 22"89s 0,116 0"50 0"135 o.66 20,493 139"8 1" 57, B 20 "997 0.504 0,639 20,3sB

175"3 23,703 0"502 o "6L6 23,087 0.114 A.¿69

2A L 39 6 2L"039 0"411 0 5x.3 20.526 0"102 0.49 "62,8 " L5B.5 "

19 L24,2 L9"40¿+ 0"363 0"486 1"8,918 0"123 tJ ó 0) " 041" 141,B AQn Lt+¿+ , 643 0 ,353 v d T/ê 19 15n 0,n39 a:72 L9 "290 L26,B "L 19 ^ " Average Au Loss % = 0"60

S : 0"08 Parting Procedure TIl

Acíd Strength; L :is (eonc" tû{Or:IlrO)

Thicl.,nessi no t f LatËened

Au Added Ag Added Sum Parted Bead Surcharge Ag Retained Au Found ¿\u Loss Au Loss % (me, ) (ms, ) (me. ) ('s" ) (me, ) (me. ) (me. ) (me" )

A 0, s4 19,8s3 138,s 155" 5 Zo "Z07 0,3s4 "f+62 L9 "745 0.108

0"339 0 22"38L 0 7n 22.5Lt+ LtY6,6 L66 " 1 22"853 "t+72 0,1_60 "

21 L44" s 163 22,L97 0. 369 a 2L 0,108 a "B2B " B "477 "720 "49 0"366 0, s46 22.3L3 0"80 0 22,493 156 " 3 r.7s,5 22,859 0"180 ¿r

23 1" 50 5 17r" 23,74t 0,375 0 58X. 23 . L60 a"206 0,88 .366 " " 1 "

0 0,54 2L "t-Ltr 141,6 160,2 2L"486 ^372 u")ö|J 21 ,000 0,n14 2L "¿rL6 Lt+3 "7 162" 8 2L "757 c"34L 0,4s1 2L"306 0,L10 0"52

?0 139 3 2A 0,3tr 8 0,1+21" 20,35L 0,103 0" 50 " 45¿r " 1s7,3 "772

L23 4 L9"521. 0,244 0"378 19 143 0.134 A L9.277 " L40"8 " "70 23 "3t+2 L62"3 t B3"? 23,728 0.386 0"501 23"227 0"1Ls 0,49

B 0. 406 Q.525 2L"968 0.54 22"t'87 L¿+9. L69 " 6 22"1+93 0,119

2L L37 â2"100 0"346 0 t+62 21- 638 o 116 o_, s$ "75tç "B L57.4 " " " Àverage :\u Loss % = 0,60 s : 0"13 Parting Proeedure IV

Acid Strength: 1:4 (conc" HNo3;H20)

FLatÈened to a Thieltness of 0"0259 ínch" s : 0"0008 inch"

Au Added Ag Added Sum P rËed Bead Surcharge g Retained Au Found Au Loss Au Loss % (*s" ) (rng" ¡ (*s' ) (*e" ) (*s' ) (*g" ) (*g" ) (*e" )

22.L¿¡.0 L36.9 157,0 22"4L9 o "279 0"389 22.030 0,1L0 0"50

L 0"205 0,328 19"030 0"123 0,6¿+ 19 " t"s3 t1B,2 13s"3 9,358

0.250 0,369 20 061 0, x.1 9 nqo 20,180 LZtï"5 L43"3 20. 430 "

B cr,a *r Lt+7 4 20 31L n\t.k\/ 0 1"34* 2A s ù^ 20,062 129,l" " " " "L77 -0"1tr oo 0 ô 1.69,0 L91_.B 0,366 0 26 24ls .L 26,L?Z 26.s58 "L22;r "¿\36 -0 "

23 161"0 182, 9 23"822 A 0.448 23.37 4 c,101. 0"43 "t+75 "3¿+7

Cr 9qq 0,369 20 905 0"114 . rì c¿ ?r.,0i.9 L27.9 L47 "2 2L.279 " oo 7qq ako I J¿ 138.7 t60.2 23,068 0"313 0"41B 22.65A 0,105 0"46

23,û24 1"48"s L7A.L 23,3/+0 0 ,316 0"430 22"gLA 0,1L¿$ 0"50

23 0 0"418 0,108 0"48 22"709 L4L,7 L62"9 "0'i.9 " 3x.0 22"60L

?,5 "9L3 L6Z"O 186,0 26 "3L2 0.399 0.502 25.810 0,1"03 0, 1r0 r"9,75s L23 "6 L42"5 20 "A25 0 .270 0.362 L9 "663 O "092 or37 >t the Ag analysis for these beads ísunexpectedly 1-ow, perhaçrs Average Au Lc¡ss 7" : 0"50 a Ëemporary bLoekage of the asplrator of the atom:'.c absorp tion spec tropho cometer, s : 0"07

rejected since suspeet Äg analysís led to an íncrease in Au weíght" ,Partíng Proceclure V

;\cid SËrength: L:3 (csnc" HliO-: HoO) Jt+ Flattened te¡ a ttrictr,ness aî. "A271 inch" s : 0"00trf+ ineh"

Àu Added Itg Àdded Sum Parted Bead Sureharge Ag Retained Au Found Au Loss An Loss % (ta' ) (rag" ) (me, ) (mg, ) (*e" ) (me" ) (*s' ) (tng" ¡

27 L7L L97 ?7.8C5 0 0 l+68 27.337 A o "5AB "7 "5 "297 " "L7L "62

â5 8s7 L7 t+" 4 t.222 0,1+60 25 0,238 0.92 " 150.3 26,079 "6L9

2r.836 1"29 . t+ L50.tr 22.C)ZL 0.1B5 0,362 2L "659 o 0"8L "L77 c .g- \o 19"034 11-s"6 1-33.3 L9.L69 0"L35 0"¿*07 L8.762 o 1".43 "272 0 n f oâ 1.9 "6L2 L20 "7 1"38. 9 L9 "735 t'a !àJ 4.342 19"393 0"21"9 1"12

128.1" 148.0 2L 0"tr83 0"364 20 805 0. 18i. 0"86 ?0,986 "L69 "

2L "728 L44,3 L64"7 2L "92te 0,L96 0.430 2L "49t+ 0,23t+ 1 .08

a a 26.66A 173"3 L97,6 26 . BBB t "?_28 "39?- 26 "t+96 0.164 "62

ô Q/, 2\,877 L47 "6 L67.6 22,061 c"184 0.390 2L "67L 0,206

ô4 4ôô n ,1 -7 0 ¿¡85 C"268 ¿lJ " åJJ L44,6 1"66,3 23,550 " 23,065

r.9 863 L¿ÈÐ,7 LJv") 20 0 I-86 0,3/+0 L9 0 x.s4 a " "049 " "709 " "78 7c)0 tul¿ooc t J J 2/+, 0 21çB 0. ¿¡44 0"_86_ I 3 L¿+5.9 23 "O¿r7 " 22.6A3 0,1"96 Average Au Loss % : 0"93 s - 0,23 ParÈíng Proeedure VÏ

Aeid Srrength: L z4 (conc. HNO3:lt2o) for f irst treatrïlent L:1 (conc" HNO,:HrO) for second treatnent

Th{c,lcnessr not fLatt.ened

Au Added Ag Added Sumìr Parted Bead Surcharge AE Retalnecl Au Found Au Loss Au Loss % (mg" ) (ng" ¡ (ros" ) (*e" ) (*e" ) (n'tg. ) (*g. ) (*e" )

L9 tr 29 L9 0 04.5 a 19"s33 0"187 u"y) ,720 " 3 "765 " "232 0.207 0"99 20,8?0 1{¡8"/+ 20,852 0,032 0,239 20 " 6L3 0 (Jl O n B6"8 23"2'2L 0 0"250 2,2"97L 0.1.78 4.77 23,1¿¡9 "a72 0

L¿rs 2A 0 052 0.20¿+ 20,490 0,152 o 2O,6¿i2 "2 "69t", " "73

20 tr 4L. 20, 933 0,053 0"20c 2A 0.L47 0"70 " 880 7 "733

0 1"97 19"3s6 o 0"75 t 9"s03 L24"3 19.ss3 c,050 " "L47

0,218 2L.6L3 0.1 40 0,64 2L,753 139 "0 21 "831 c,073 2L,B6L c,a76 a.2L6 21 645 0"140 0 2t "785 L4L"7 " "6t+ 4'¡ anrì L /+B, 23 a,067 0" 2L4 hé ô¿vv 0 x.47 0"63 23 " 447 t ,5L4 "

0 199 18"647 0.L52 0. B1 T.8"799 116"2 L8"8¿16 0,047 "

t+ 0 c,199 LY"YI) 0.l-38 0"68 20,l"L3 l"3B, B 20 .L7 " c6n_

?3 740 0. n"46 23,886 158" B 23,984 0"098 0,2t+4 " 9"-9Å

Average Ar: Loss % :4"7ù"

: v"l"/- t" Lhís parameter lras not neasured due to an oversight-" TABTE VT

Summary of ParÈing Procedures

Þ Au Loss s Procedure Aci.d Strength Thicicness s Surcharge s Ag Retai.ned ( rnch) (me" ) (%)

a 0.l-33 3 ,47 nq? 0"6s 0,1_4 -ã-:o 0 0.0009 ,625 Ê ï "0504 UI ana 1.6 0,0006 0,537 0 1"60 J a tua 0"83 0.60 0.08 0 ïï 0 "0249 " 2t) 0"L6 0"60 0,13 TÏÏ 1¿.- .1, unfX.attened -- 0"3sx 0"041 0"07 0,50 0.07 ÏV l_:4 o "0259 0,0008 0 "297 0.056 L "82 0 [,81 0,tr 9 0"93 0,23 \¡ l-:3 o "0271- 0.00f.4 0, 200 "047 0"08 O"7t+ 0"12 VÏ tr,:4 & L:i. unfl-atÈened -- 0.06x" 0"018 tr "03 -52-

-sÊen Lr be indica-Ledg

a), deereasing the thickness eí the bead deereases the su::charge anci

Lhe neycentage of silver ::etained" (Cornpare Prseedure T vs TT and lII vs IV)

b)" increasing Lhe aeid strengLh decreases the surcharge and fhe nel:centage of siLver retained, (Cornpare Froeedures TI vs IV and IV vs V) e )" decreasing the ttriei

1 vs IT and III vs TV) d), íncreasing ac' id sLrength (to a ¡:*int) reduees goLd !.osses" (Cornpare Procedures TT vs IV ancl T vs TV) e), inereasing acid serengch deereases the devíation in the síLven ::etained, (Cor'rpare Proaedures 1 vs TI and III vs VI) i) " a second. parLing is elfeetíve in reducíng Lhe siLver retaínec3"

(Cor,rpare Procedures TT. '¿s VI)

The reasons for the firsL tr,'¿o eoncLusions seem strâíght forward"

Since acid attaek oceurs at Lhe surfaeerihe removal. of siLver is enhaneed r.¡hen the surÍaee area of the bead is íncreased. FLattenín;¡ the bead increases surfaee area" llne reduction in the sin-ver reÊai-ned by use of a sLronger acld b) fs probabl.y due to the constariÈ Lfme of digestf.on anci the fai}ure Lo reaeh eauitr ibniun- For a given Lengrh of Li.nìe the müre eúneentrated t:ouLd be more f.ihel"y to l-eaeh out a greater proporcíon of six"ver, The increase in precision of 'che pereentâge ef siLver reT:aíned by use of more eoneentrated aei.ds musÈ be due to a sinLlar ef,feet" (e) For a gí.ren T.ength cf time of digest,ionn the eqi¡ilibrium siate i.s none 1.i1'"eLy to be reaetred srir:h the strenger acid" Sinee bead'u¡eights differ, the 1a.r5en i:reads, cr:n.taining more sil.ver, q,¿í.1-l be nore effee tíveLy- -53-

'leached 1n Ëhe stronger acid" As a resuLË deviatíons in the percent sllver reÈained due to incomplete Leaching will occur more frequent!.y ln the dtlute acid.

The reason for the reduced gold losses due Ëo a decrease in

thickness of bead (c),,and íncrease of acid srrengrh (d)rts nor as (37) readlly apparent, A considerarion of rhe gold-silver phase di"qra* near the melting poínts of the Ewo metats indicates a sfmple diagram, wlth no eutecElcs or compounds. since the roelting poínt of gold is approxirnately 100oc higher than rhar of sllver, rhe first crysrals forming on solidifícation of rhe bead would be gold rich r,¡hil€ rhe converse vrould apply near Èhe end of solidification. As a resulc the exterior v¡ould be hlgh in silver, on pressing the bead to reduce bead rhlckness, conslderabl.e friclional forces rnust be overcome, thus momentarily generatíng heaE, As Èhe ter,rperaLure lncreases diffuslon of silver and gold t¡ould be encoura8ed, such a bead when ex¡rosed to acid creatment rvould have a more regular surface than a bead in which a sllver rich surf.ace prevailed. The more frregular the surface Lhe nore likely would be the loss of sma1l even fnvisible gold parcicles. Essentially all reported parÈing losses are of such a naÈure. r{hile the mechanism of diffusion puL for:ward here may sound far fetched a simll.ar theory has been advanced to.juscify rhe annealing of the gold- sllver beads príor ro parrin r(2O¡ . Ic r+rould appear thaÈ lncreasing the acid sËrength reduces gold losses onLy if Ehe acid is not too strong. I'Iith a siLver to gold raÈlo of abouÈ 6,5:1.0 that poinÈ was reached around 1:4 nitric (acid: r¡ater)' llhlle no reasons can be advanced for Èhe generalizatlon d) regarding acíd sÈrength, an appl.icaLion of the t tesÈ for significant

-differences indicaEes the cornparisons upon rvhich 1È is based, represenË, -54-

'sigurífieanc differeìlces at; ihe 99% c'ænLLde¡-ree Í"evetr.

The final concLusi-on that a doubl"e aeid pari:in3 f:reacment red.uces rhe s:Llver: cûnienl ís el-ea.rLy inriicated by the::educed surcharge and pereente3e siLver ::elainecÏ" fne fail"ure æf prerrious double digestions rnusi have been due tô a closing of the ¡2ores of ihe bead on anneatring anC thereby prevenLing the acid f::s¡r coning in coni.act v¡ith signifieanË anounts of sí!.ves" Thê increased gold loss ín thís e'ase seerns to índieate fao strûng an aeid foy the second par'cing"

An atLenpt \cas nade at this point to detennine sonre of the gold

X.osses di.rectl.y" Several"(4), partinl soluiions fr*n Proeedure V r¡ere cæLl-eeted co¡;elher r¿yilh Lhe wash ;*ater, The soLu:ion rsas taken to near C::-vaess, The residü€ r:yâs treated r+i:h 6 nit" aqua regíâ, '*'hich resulied in ïïre preeígLtati*n cf consìderabl"e siLr¡er (approxinacetr-y

6{iû mg;, }" In a?:iempr.íng to d:l-ssoLve thís, 78 ";:-L, of eonçentratecl h;*d::oehl-oríe acid ryas added r,.¡hieh ¡enerated 1.arge cruanT:íríes of nÍ-Lrogen c:;iries as the exe,ess ni.t:rate in sol-utioir inte'raeted" r¡síth the added acírj, This s"+l-uiion v¡as then tal;en tr near drlmess oncê again, and fínatr1-;,- irealed rríih 6 nL, aqua regia and 10 ¡r1" hycJroehloric aeíd,

The residae which remained r,ras fíLtered off . The fillraLe af ter dilutí-on to volume ín a 100 nl , vol-ur4etric t¿as examined by aLomíe absorplion f,or goLC eontent, No go3.d rsas found" Under the eonditions used the ninírnum ai.ïount detecr:abl"e r.¡ouI-d have been 12 iaierograrns, Tn viets of che abiS.ily of AgCL í:Õ co-precipíLa"te goLd referred to abôveo ihe negatíve test ftay þ¿1¡s been due tô Ehís efr'ect, ALf:ernativeÌ-yn j-t r:aay be ihai: the sensi:ivity *f ihe procedure ï?as iór LrÞ¡, T.f son i"osses it ihe Fa::iing acid and r¡ash sol,uLions r,¡oui"d be Less than 3 microg,rams pe:: sar:iple, In any case a radiocheinieal- proeedure r,ras pÏ"annecl, to exanine -55-

'this loss at a laËer poinE in the research, 1\ro atternpts \,rere nade to deter.mine the gotrd conEent of the

cupel rnateríal, In the fírst ÈesE the cupels from Procedure V were

drilled Èo a depth of 3/16rr using a 7/321t bir for sanples 1-6 and a

gl32tt bil for sanples B-Lz. Sanple 7 r.ras losr. Each sample was

treated with 6 m1, aqua regia and 10 n!." HCl" This rrearnenr bnoughr

all sarnples inËo soluiion on heating. The soLuÈíons were evaporated

to drlness and Lhen treaied wiih 3 ml. aqua regia and 5 nl, conc. hydrochloric acid. In this volume the samples faileC Èo dissolve.

The samples were diluted io 5C ml. in a volunretric flask and asplrated wfth Ëhe precipitate ai ehe bottor¿ of che flask. The samples rvere

indlvÍdual1y aspiraLed and gold conceni deEermined by aÈomic absorption, the average signal vras just barely detec¡able and indicaLed ehe presence of 5-6 micmgrans of gold" Agaln ihe presence of Èhe precipiiate rilay have had a sfgnifícanL effect on ihe result,

The second tesE for gold in the cupels was sonewhat, modÍfied.

Cupels 1-6 from Procedure IV trere drilled over Ëhe entire upper

surface in such a $ray Ëhal Ëhe total cupel r'raLerial Ëaken was about å thaÈ of the previous tesE. These scrapings or drillings dissolved cleanly in 6 ml. aqua regia and 1.0 rnl" HCl afber heauing for several hours, Each sanple was Èhen diluted to 50 ml" in a volrmretric flask and asplraled as the prevfous case. The average gold conÈent was 25 nierograms qriih a slandard deviation of 4 mlcrogrartso Since the coial gold Lost ln Lhis parÈicuLar trial. was of the order of LCO micrograms 9 conslderabl.e gold rernained to be accounÈed for, Further consÍderatlon of this matter t¡as postponed unill a more saÈlsfaciory assay could be made of Èhe cupel naÈerial. -s6-

4" VerLa¿i3.i.za.lisn

The oi:jee. of :his pcrtitir *f :he s':udy iras tÕ'åeterrrine t+yheiher

¿cl.d vol"atil"izes l:t a si:ni,ficaat extent ¡:nder cupeÌ-3-aiion c*ndiii*ns" I:r a p::ei.íi,r-rirazy exSlerineni, :he resul.ts of r.;hieh are reprrted in Table

1¡IT, {:r,¡elr¡e beads oi-c apprô}iima':eLy eçuaL síze (8C n5,)t+ere made up

by rreíghin¡. out four sainptres of pur gold. four of pure sitver and four

oi a L:3 r¿í:rture of gol-d aneS silver ::esglectivell'" These rr¡ere

encased in 51r :s 6rt x "004ti Lead foil and cupeLled in ihe usuatr rvay" Since the Lead foil r,¡as ltnorm to contain an average of *5S:4 rnicrograms

of sil^ver pe:: !ra.rl9che sígnificani ehanges *e,cur a-fter a cupell,ed

i:ead çtas obtaíned, Tn 25 ...." of tread foil- the sín"ver ernÈeni eoul,l arjel as nuc'h as L"5 ng" tû 'rhe bead t:eí¡ht provi,Sed no l.osses rceurred"

This eor:ld exptr.ain, ai l"east part:i.al"X"¡', r'rhy :he goi.ci beacì obiained

af;er cupel.i.atiôa l.ras on- the average tr "0 ng. heavier lhan ihe gotrd added,

On heai:ing rhe cupelled beads srr,le ini:eresting ehan¡¡es oc,crlrred"

Tne firsl heating intervaL r.ras for 3C ninutes and appno>

iiilre requíred for cupellaiion, The go1d beads systemaiicaX"Ly i¡rcreased in vreigir: by an averal;e oi 0"tr26 mg, s:0,021¡ rng, The siS"ver beads dec::eased in vreígh'r by an average of t,L6?r mg, s : û"080 m.g" r,¡hiLe the goLd-sii.ver (1:3) beads deereased ín ".¡eíõhi by 0.Ðt¡2 mE, s : 0,018 ng, À1-l- heaiings r,'re;:e made on t-he sa¡ne cupel. used for the cupel la'¿íon of a. pa::i:ícuLar bead" A seconcT hea';in; of 'cire sane bea,ås for a Ðne hour intervai. incii.eai:ed an ap6lrtlrínateLy grropor;íonal deerea-se i.n røeighË for ihe pure silve:: aad che ini:ced beads" The goi.d beads, trol,;e'rer, Þo?í 'be3an (C"ûtr"6 : Lo decrease slighi:ny irg" s û "Q\t+ r.-¿") ín ryeislii, In vi.el¡ of, the hi¡ir rei"ative unceriainty here a:rd:he iae'l thai o::e of llrese gel.d bea.Js ae[ual.].lr increaseeJ in treighi-n and ín vierrr of i:he faet TABLE VTÏ

Ef iee t sf lleacíng Go3"d, SiLver*and GoLd-Sil.ver

Beasls

VoLatitr íEy SËudy 1 ¿\rr ¡\clded Ag Added Sum l.,,relghc Afteir I,leight Af rer Ghange In Íüelght Afeer 't. i-sÈ ireatíng Zncl heating tr st heating 2nd heatin¡; (*g" ) ("ng" ) (mc" ) ('ng, ) (*g') (me.) (*s. )

Stl 7¿*0 8n *0,039 " 579 BX,607 81" ,7or +0.133

79,33L+ 80 , ¿¡1L 80 d$28 +0,093 +íl c)17 80,3L8 " "

80. 996 a9 n'[ 7 82"n"43 82" 3.39 +0, r"26 -0.004

B9 858 e!."833. e0".-eeå e0. +9-*31Å LrJ0 " el¿ -U "

Avera3e 83 696 83 822 83 806 -i-0. r" 26 " " " -r""

Þ 0,024 0.024 Ur{ 81"834 BX. 81".377 058 I 82"66a .776 -0 " -0,399

87 B7 833 B7 39¿+ , 1¿$1 ¿!39 89,098 "974 " " -0 -0 '

80.288 79 , t+L6 79.L77 1^ 7r1 239 *Ç -0 " " 4s6

9!"-¡!-t 79,_5.!¡L 72,339 /&_9ÉÅ_ -_0*_eÅL -0.J*-Bl-

Avei:age 82, n9t 82"A29 8n. s83 *0 446 "L62 -0 " 0.080 0"c37

2A 60,207 8A B0 698 B0 684 n6g *0 0r.4 "765 "766 " " -c " "

9 drl+5

21".768 60"7tr6 81 B1_ 94s Bt 85¿r Cr39 .984 " " -0 " -{l " |9n

oo o4x 62.7 t*3 BJ._?3å Bs*-S)-t, -o.J!-1 -9*-3!É'''

At'eraûe 8n 784 8L t"2 078 " "7 -0 " O"OIB 0,058 rejecterl sinee bead fonlecS. a rtotLec inter the cupeÏ" on ihís heating -58- iha'c one *f 'che nixed beads had io'ce'rejeeted fc:: an experinenlaL reasrn i:: r:¡as deeided io:ral.-e a nÚra :horough e"=

';ol-atiLiaaiisn r+æul.d be Less than t niCraS::an per beaetr' I:-r r:ire second, i:esi: oF r¡ol-atiLi-t:yg]i? sanp3.es of ¡old Ön1"y !¡sss r'¡ei8ht i:he p::eparee3 ancS eupeiLed in';he ns::r'.iaL "';a)'" /\¡;aii: the of

beads j-ncreased by appro;xínai:e]-i; 1-f' n:j, ftv.t healin3 period.s *f the

rurl3ell-ed "nearis fo11o".¡ed, Bo';h i:erield.s we::e of 3C rnínutes duratioir"

¿\fter the fr-::st sr-rch heatin¡ lire treíÛht aî ';-he gæi-d beads ine::eased heaiíng procir-rced b], ar-,. averase of C.L42 n-g^ s: f "f8s, The second a sI-i¡hr: dee-rease i-n +reí-ghc of c"ûLi- i-irg, on í:he avera::e" The resul-ts *f this experi;¡eni are rec*cded in Tabl"e VTII" These results are quite ín ageeeneiri i*i;h ihe l-inired -resuLí:s ojl the prevíous e)îperinient' si3'ver oirLy ï,n the lhi::d Ì:es¿ of, volati1ity L2 sarnpX'es of ":eie prepared and eupel"Lec in the norraa'! flanner" The, resuLts of one bead indicaced an ha¡ri:i.lrvÉ q;¿Jc) ne:¡íócl. of 3t ni:'IuÍ:es <.1ura:ion of a cupeLi'ed

âverage l-oss of veí-gh; mf Û^l-68 irg, í¡r i:his e:çerirnenl as etnpa::ed ;o i:o poin'c in t,L(t?" r:.¡, _iia ihe BreLirirÍ-üary siucy" The::e seercecl be no eo:r:inuí:-t¡ ihis study" Tne beaqÌs nf tire prelírniirar)¡ sllidy had lrehaveei

ína:,:ep::esen'.a'iirte ilen'ner âS !7ã.s eonfir:ned Ì:y the Lasi ir¡o studies"

Tire lcss in ",¡ei:iti oí :ile siLver Leaðs c:: cu¡reL1a';is::. is consis:enr- 'rlii:h TABLE VÏIT

Effect of Heating GoÌ-d Beacis

VolaË:Ll"ity Study 11 Au Aclded Ideight Beact Obtaii-red Ideighr Bead Af i:er Change ín lleíght Af ter tr"sL heating 2nd heatinp; Lst heatíng 2nd heating \1118, / (*s' ) (rng. ¡ (mg" ) (*s" ) (ng" ¡

?o 1l(}c +0,00n | / ðJ/J BA "329 80"523 80"524. +c.194

Bl- 82.956 82"969 +o +0"0L3 " 97s 82"929 "427 +0"L¿$5 +0,026 76 "97L 77 "809 77 "95¿+ 77,980

85 228 86,09? 86,1_72 86, n,59 1-0,080 -0 01"3 " "

c,1 e B1 V¿at¿tr¿ao 82.670 82"6L2 +0. T.5 7 c58 " 469 -0.

99 d$85 100.367 LÐ4.722 1"00,5ffi" +0,355 -0 . 2L 1,:b " 0 L¡l\o 70 r.ao 80 g0"Brr7 BÐ +0 n"66 0 " 701 "827 " -0,040 79,L28 80"tr76

a F/ a¡ì 7q? ¿5)" +0 086 -t-0,010 t-i¿1. Q)O 8s"667 /OJ "

86 ,7 ¿16 87 ,70L 87.806 B7.Bt3 +0, 105 J-0"007

7(l ¿ôn 7o ?o,¡, 7E"3r.s . 79.2,96 , ¿aJ/a +0,1"c4 -0,006

313 (r0 ¿¡52 rfì I 1O -o-,-ryg ,60 " " 90.406

R? 111 Rj 1It *0, T" /+2 Àvera¡e 8L " 99L -c.0r.T. 0"085

:'ç rej ec Eed on s tatis ticatr ¡nounds TABLE U

Effect of Heating SiLver Beads t/oI" a'ril i ty S f:udy III Àg Added Welght Bead Obrafned I'Ietght Bead After Change in Wetght After lst heating lst heating (*g. ) (*g" ) (*g' ) (*e' )

1 98 756* 19s.318 195"000 " -0 " 3lgvr 80,204 79.126 7g.gg5 -0.131

59.028 5B,497 58.279 -0 " 218 106.331 t04.672 104.580 -0 "092 J -t- 80.235* 79.09L1- 79.2251- : +0.ß4+

0 B0 074 79,077 78.983 _0.094 o\ " o 0 77.630 76.892 76.77L -0.LzL

77.046 76,392 76.3L7 _0. 0 75

B0 " 8L9 79.990 79.830 -0. 160

BL.2L2 80.450 B0 366 084 " -0 "

79 79 79 "922 "309 "004 -0 " 305 83.131 82,948 92.548 -0 " 400

Â,verage 80.539 79.735 79.567 -0. 168

reJected on statistfcal grounds

thls bead excluded due to much larger size _69"^ .

-j.a ) 'eîorts -ire L i te-::a;u::â(33 " Âl1o:rir:¡'; Íc-:- ihe sil-ver bLanii oi L ,35 ;rg. and :he ::eal- J-oss *Í. C.8t r:,g" the :o ¿aL siiver l.oss ejrtunts

:o ?.Ttn r¡,2, *x 2"78"L af. :he *ri¡ira.l I'rej,:i.r: o:i siLver"

In *ycie:: ir bei::eÍ r:nders'¿ancï the calse of rhe increase ån "rleí¡ir.t

'-ire- .+'!:l . u.- iif (J: Li^irLÍ¿vr¡ tlu-.-i':r. .ciii *,Ie-';e ti -L!v úr.', u ie¡i^vi: -Þ ^^-'^1¡¿: :çJ ^^ ^' r.¡ire Cu'- a:rd.

",,:ei3hed" ìiaeir sairçle r.vas placecS on a ciean unused. cupel and heateci rrnder ihe sar:le eondi:ioas as fo:: cupel-La:ion" The resutis are sui.:iraríaed

{.:¿ Table X along l¡iih a simiLar series :lor siLvel:rr?iïe' The ueigh: of

¡;o1d r.,eÍre befo::e and afÈe:: hea:ing rerlained consian: lrlí.Í:hin ihe e=''rÐerír¡.reni:al iveíghin¡ er::c::" The î'rei-h: of siLver "..lire rlecreased en the ar¡eraûe by 1"138 r,i;" 0n rhe basis oi chese resuLis :'-t r*cu-1-d allgleaî

ihal the userl euÐej-'has sone effecc oi-Ì i.:he goLd beads" One possíi:iLi";y i,¡ou1"d. i:e :he df-ífusion *f sone eleaerital" tread iraeL; í-n:o the gold bead, i;h:Lle Í:his ::eve::saX. r:f, 1-ead nover:e:rt seenecì hi¡hl1' ul,1-i1--e1 ï, a leaC

analys!5 erf 'che ¡;o1.3 beads r:?âs suggesËed,

Each bead, r,ras dissolve,l in 6 nl". aelua ::e3ía a.nå t0 nL, coirc,ântraled hyrjrochl"oric a:rd drLLuLed. to 100 nL, Lead slanda'rds \'¡e::e prepared t¡ith

a z¡ra-:ehed, na.irix. The avera8e Leed ctní:eni: t¡as 0"140 ng, s *- C"0/+8"

The ine::ease in r,veií-.li. of 3o1-ci beacis an fí::sl heatii:g averaged co 0"L4?

. t;ió ù -- - G'-ttJù

T.i: ttould ap¡pea:r iha;'che rlncrease ín weiâht r:n hea;i:rg a pure 3o3.d bead is d,ue;o ctriffusion of lead ii'o:rr ihe cu¡:eL. i:a.cir ínio ¡he bead.

Eveni:uetr !.y, a s:a¡e of er='-li-l-íb:ciura is a:í:ained a:rd :he ì¡ead be,ins io

Læse snal-l (0,ûl"i¡.) ancuais erf ics:'rei.¡,h: on sulrseeueni ïreai:inFs, A seareh. æf ihe L:l:eraii-l-,:e lnqlicaterS tha;: ihe j-ircrease rl-n tieÍ-ghl unCer

discussiozr here liacl been obser'¡ed ¡eforu(34). These auihors tef i ¡oLd beads ía Ì-he fr:raa.ee for- va;:i'í.n3 lsngr-þs c-i iine Lo see elhe;her gelLd T\tsLE X

Effecf: of Ì{eating GoLd and Síl"ver I'Iires

Volatilíty S'rudy TV -62-

ideíght Au I,*rire TaLren Iiei;ht After lleating Change in i'leighr Once Àfter Heating (*s" ) (*g" ) (*g" )

c-j -7f^.) +0 002 J t t , ví¿ J I . I v,! "

70"t.Lt 7A "LA7 -0,004

93 Lbtþg û04 93.4s3 " -0 "

Lt,¿r"269 L0¿þ,268 -c,001"

Lts.629 tr"0s.628 -0,001

93.377 93 "37 4 -!,_Q.aå

Àvera¡le 87 "¿,,31t 87.rú2 - "002

Iror' ç 4¿jÀÀi ch: L Â r- I'I i re- Tallen lTeight After P'eating Change ín \'treíght

ÂFtov llpqríncÀ¿vs¿ 0nce -¡¡¿ ' (rag" ) (û'e, ) (rag" )

82.372 82"3¿+L -0, c3E

'¡ lv ñcrJ . lLa nx L L08, 887 -0.LLt+

87,26A 87.tt+3 -t.2L7

oo aoÕ _u Lroo JlaoJ/ / 97""333 "

86 B6,386 " s47 -0"16i

11.) /)qÞ 3L2'39r) LLA64Jê -9 "L37_ oq ô1 I _0, Averaiie .¿ r , v L* 94,87¿, 3.38 _63-

î?ttt 1-*sses woulC inerease The:' four:cl that csnst-ant Ë'essÊs 'î'rere o'i;served dü,6o but e'uri*r:s1i* enou3h there seern'ed to be a sl"ighi: is i:enrÍene1: iú ínerease i-"ri lrei8hi:. To r¡vha-3 ihj-s aou.Ì-d be arlribtrLed

of ci no i eLea::",,(3ri). IÌ: is possi¡1-e ihat rhe írcsease ín ""reight 3on .beads is due tr anGlher unhnresrfl lrÊâsÛn and f:hal- i:ire f.ead" had siirply Lhai- case nal: bc:en re¡n*ved froil Lhe bea-d ín i:he fi::sl'ínslance" In and :he ;he cl"ose aÊseeÏl-ei1 t hei*r¡êen ihe vrei¡ih: inerease on heaLing nÕi r,,rej-ght oÍ lead reiaíned r'¡outrrl l¡e fo"r:u--í-tÔus' i.lhii'e th5-s nighL enough be Ciff:'-culi i:û prÕve, ¡:T1e natiel r;iâs not csnsidered ínporiani lvas teqnínated ai io l:he aj-är. of, this resea::ch airrl che:ret'*re lhis studl'

L Lhis po í:: " r:hai: Oa :he basis *f i:he r¡ol-ai:j-1",'r;y s ir:d:ies j-i see;:rrs safe io saY ;:he eondítj-Ór::s ;3*L.i ,!-osses 1¡ía voi-aii-tr-izai- j-et are :1o:: si3r-ri:ÎÍeaa'c under s :udied. 5" Efiec; of Cleai:-ia; Beads Up un:i,l- :his poin; in :lie t¡nr1t' the beads obtaíned :lron i:he cupeil-atioi"r process tTere cLea::,ed of ati cu?en riraterj'aL by scraping' Sincen hor'¡erre::? al-l sousees seemed cÐ aÛree ".,¡ii-h a i:l-ari.nulä sî:aiula. í:hai i:he la.::gesi: Loss of go1-d ín j:he cupella-tíon p-rocess occurred aT:

ihe poini: of eoniae t beir¡een bead. aneS cugrel it seened highly f it'ieX"y

thar thís eupeL r:ateríal adherinE',co :he bead t¡o'-rld be reLatíve1"y to trea'c six ri*h ip :ioi-d" Ii '.aas ,:herefcre consiCerabl-e ciesíra-b]'e sanpl-es il i:ire usual:nallner and Lear¡e síx sa.npLes untouched' f; ç"xas prer"iousl-y esiabS-ished iirat i:ire eupei- ¡"areriaå ::eadiLy diss*Lved in j-:4 3.5 n'ínuies i:h* r:arií-ng aei-.rls u5ed" (15 ¡:inutes ni':::ic fotrio'"íec by 1r! nitrie ) r-rn'Je:: ihe condiiíoas of partÍ"ir¡' TabLe 'tl is a sllrl¿rery

o f ihese ¿v¡o tr:l-aL s "

Ir*..:,r labJ-e líT it ís evlLdelri iha;: ;lle rstC loss is in*reased by TABLE XT

Effect of Cl.eanång ÏInparËed Beads

On Geld Losses TABTE XÏ

Effect of Cleaning, Unparted Beads on Gotr d Lssses

Au Added Ag Added Parted Bead Sureharge Ag Ret,alned Au Found Au Loss Au Loss % (mg, ) (^s, ) (*e, ) (*s" ) (*e, ) (me, ) (ms" ) (me. ) Scraped Beads L9 "720 g?,9"3 t9 "765 0 "045 0 "232 19, s33 0,187 0,95

20 X.48 4 20" 0 20 0"99 " 820 " 852 "032 0.239 "6L3 0"207 23 ,L49 L86 .8 23 .22L A "072 0 "250 22"97L 0"r.78 a.77

20 14.s 2 20 0 052 O 2A 0"tr52 0"73 "642 " .694 " "%Ot+ "490 20, BB0 L4]., 7 2A"933 0,053 0"204 20"733 0"tr47 0"70 g\0 8\ r.9 " s03 L24"3 t 9. 553 0.050 c"197 19,3s6 0"_ry[7- 0"7å

Average Au Loss 0"I70 mg, A.BZ %

Unscraped Beads õ 0,025 rng" 0 "LZ %

139"0 2L B3t 0.078 0 21 613 0"64 2L"753 " " zx.B " 0"r.40

2L "785 1"4ï."7 21 , 86r. 0,076 0"2n6 2L "645 0"n 40 0"64

23 1 23 0"067 0 21.4 23 0, 0,63 "447 48,0 "5L¿þ " ,300 L47

L8 "799 LL6 "2 18,846 0.047 0,n99 I 8.647 0"L52 O.BL

20, LX_3 138,8 20 "L74 0.06tr 0,1 99 19"97s 0, L38 0,68 23"886 158, B 23 "984 0 ,098 O "244 23 "7tq0 0-""¡-,46- 0,_61_

Average Au Loss - 0"!.44 mg" A"67 % I Beads were cLeaned by seraping s : 0,005 mg. O"O7 % with a spatutr a" -6s-

the 26 nlerograxns on the arrerage vrhen the bead Ís seraped, Thus praeËf.se of e1eanlng beads of cupe1. maËerial !üas sËe$lped fron Chfs pofnË on fn this research" IV, tosses of Gold ln Tte Cønptete Fire Assay n. Effeat of, MlNing Proeedure of Ore and Flux Slnee fairi,y Xarge eontaLnefs (crucib!.es) are requlred for the f¡'uN fusloa ¡rrocess sarnpnes !ûere prepared !n groups of sfxo IniËfa}ly harvard eoÍ4ronenEs srere fndlvfdual.Ly vrelghed out from a seooE, type trl¡r balanee Êo the nearese L/10 gr¿m' and Ëransferred dlreeËI'y Ëo a cetlophane sheeË, Ilere they Ìúere thorougLy mlxed by tumblf.ng baek and forth for approxinately 30 mÍnuËes" lbis proeedure was found Ëo DusË be ermbens@mee sXolt and Ëequlred Èhe çYearLng of a dusÈ mask" i.- from che flux eornponenËs ls {.nJurl@us t@ heaLch' In order to speed up thfs pË@eess and reduce Che heatth hazard the flux eorllponenËs súere ?lbaggiestl mlxed in xarge utfnlEy sfzed potryethyS,ene bags known as (produeed {n Canada by Co1gaËe Pal.motive)" In chese the fLux com¡onents eould be vigorously tr¡rnbtred and nl:

1\üo ex?eriments were perfo:med, Uhe results of whl'eh are recorded and 1n Tabx.e xlÏ. In the one Ëest rhe fl,ux eorryonents were welghed transferred dlreet!.y Eo the fusLon erueible. ftre aecuraLeX.y welghed the anounEs of goXd qfere added to a slight [æ Xlow I'n Èhe eenËre of gold fxux mixture and sufftelent slx.ver was added so ÈhaL the sl'tver t'o gotd raÈl@ v¡ou1d be betç¡een 6c1. and 7:tr, the fluxu sflver and were nfxed as thoroughXy as possible wiËh a spaËuÍ.a' l{o vLsfb[e amounËs o€ fluxu sllver or gold adhered t@ Èhe spaÈuLa" fre other slx samples, for the seeond ËesL, rdere preElared by known as a transferring Ëhe f,&u x materiaS.s from the bal'anee Ëo whaË ls r?sanfuíçh siøe bagglutr (polleËhytrene bag vreighlng approxfmaÈeI"y X'"0 TABLE XTT

Ef.Eect of Polyethyl"ene Bags Oæ GoT"d Losses

For CompX.eEe Fire Assay T, No baggiesX Au Added Ag Added Sum ParËed Bead Ag Retained Au Found Au Loss Au Loss IdelghÈ Lead BuÈton (*e" ) (*g' ) (me" ) (me" ) (tng. ) (me' ) (mg' ) (grams )

no /, 19"548 r.32"3 r.45,3 L9"376 0.116 L9.260 0"288 L,47 L / ê4 22"L27 i.41,9 158,0 2r."B9S 0,X.41 2L"7s7 0"370 L,6B tB"2 20"680 137"X L52.4 20"603 0"120 20"483 0,L97 0"9s 1"8,6

21"0n5 136,0 L52"3 20.s9s O"r29 2A"466 0.549 2"6L L9 "2 18"23X" L26"6 L40.2 18"082 0,T.1-3 L7 "969 0"262 1,44 LB"s 19"52n 122"3 L37,4 L9"456 0,L13 n"9"343 0,r.78 0"_9-L_ L9 gr "4 o\ I Average Au Loss % : L"51 TI" Baggies s:0"62 L5"367 102,4 1L3,7 X5,261 0"10n" 15"160 0,207 1".34 ?1 q

27,754 t76"Ott

2A L27 20" 20 0 0 BB 29 "94L .6 L4t-þ"2 889 0,13n .758 " f.83 " "9 2,6"s64 L46"3 L67,4 26"s82 0"258 26"324 0"24A 0,90 3L,2 23,X68 X./+7.1. 165"s 23.L52 0"157 22"995 0,r.73 0.75 3L.8

31"Bs9 zLL"6 23s.7 3t "66s 0"236 3L"429 0"430 1*__3J 31"3 tt losË due to craclcíng of pot ln furnace Average Au Loss %: L,04

1- baggíes R?ere approxírnaËely tr,O g" polyeLhylene bags s : 0.28 ^67 -

gran), The go}d and slLver, ln Ëhe sane pr@$'orËi6ns as beforee Eetre Ëransferred direetXy frou che batranee lnter this baggf.e' ffire baggåes were Ef.ed off, and thorough]"y and vlgoroupl.y mfxed for 5 mfnuËes each" The flux maÈerlals, goLd, si!.ver and baggle were Ëhen p1aeed Ln the eruefbXes for fusfon"

In thfs parËfeular eomparfsone Ehe assay samples were ¡rXaeed fnËo the fuz¡aee at an LnlËfal t@perature of 1950@F ærd heaeed as qufekl.y as posslble to 23.00oF. Ttre sanples $sere all.oç,¡ed to ræain ln

the ove*r f.or 24 hours, after whi.eh Ëhe eruelbnes were rem@ved from the funraee and thefr eontenÈs poured lntô a eonlcal {.ron nol.d" Af,ter

a @ne hour {'nÈerr¡at for eootlngu the s!'ag rras separaËed fEom ehe nead

huËÈ@n by gent1e raBpf.ng wfth a meÈa& bar'

The nead b¡¡tËo¡¡s *rere welghed to Ëhe nearesg 1/L0 grarn and

eupenled at !.800@F as usr¡aL" After eupel.LaË{.or¿ and eoollng the beads were wefghed on a mlln"lgran balanee and parted as {ndLeaeed Í.n

PEoeedure Vl,. The beads were no longer senaped t@ rem@1te eupel naterf,al" the beads were washed three Ëimes !üf.Ëh hot water, annealed

and wefghed aec¡¡ratel.y to obtaln the wefght of rhe pareed bead. The

sl$r¡er e@nËent was deÈe¿rfned as deserfbed for tt¡e eupeLl.aÈÍon st'udfes

and the gold reeovened ssas dedueed 'ln the usuaf, way' In the f{.rsc tesÈ?Ì{lth no baggfes?Lhe aveaage gol'd loss was

tr"51% s:0.62 whlle w{eh bagg*es for ml.xfngu che aveaage gold &oss was

3..04% s = 0.28. ffirus both go[d loss and devfatl,@ns f.n Èhe pr@eess are nedueed when bagg{es are used for måx{.ng, Tn subsequemt, e:rperlmenEs

thf.s praeËlse was adogrËed.

2, Effeec of Fr¡sfon TemperaEure @n Gol.d Losses The basle proeedure for preparaËlon of samp&es and Ëhei.r fus{.on

E{as the 6a!ne as deserfbed above, røleh the pel.yethy1erre bags ¡¡sed for *68-

mfufng, The eupe&LaÈlor¡ øf aXL che lead buÈÈ@ns @bealned çaas aehåeved at a ÈempesaÈure øf t800oF ag f.n che eupe&Lacton sËudies. fte panelng

of the gotd-sllver beads was so{Ëh trd@ 1.5 mfnuËe LaeaÊmenÈs sülth 10 m&, of [:4 and [:1 nltrfe (aef.dsrdater) respeeËlvef,y" The aefd was pre-

heaeed ln 35 nt, beakers @n a seeam baÈh" T'he beade s{ere then ¡øashed

three ti.mes wfth hot waÈere annealed and wef.ghed" Tbe sf!.r¡er e@nÈenË

of the panted beads çyas detemfned by Èhe usua[ meth@ds ouÈl.lned above" As {ndleated ln the lntrodueÈfon, assaJrers ofeen adopt the

Írraetl,se of usfng a 3.ow lnftfa!. temperature for the fuslon proeess and

then {.narease the temperature Ë@wards Èhe end, T\do ËrLal.s wlth

{nlÈlal ËemperaÈures of ¡.850@F and [950oF were eonp[eeed aË a ffnal

Êernperature of 2&00@F (flrsc page of Table XIII)" The flrst ÊrLa&,

wfth che tower lnåc*at temperature, resulËed ln a &o¡øer gotd &oss of

0.81.% s = 0,n0 as e@mpared eo O"9T/. s={,Zf for ehe other" The tråan aÈ the hfgher temperaËure ls aetua[fy a repeat of, a slml.[ar tri.al.

reporeed f.n Tab3.e XII Ln whla,h the gol.d Loss eras L"04% s = 0.28, Ttrus

the &o¡ser lnfÈ1a!. Ëernperature appears Èo enhanee gol,d reeovery and lmprove preelslon"

Sfnee the tnitf.a!, temperaÈure of the eharge ls al,ways Lower than the flna[ tempeaature fr¡ any ease, ft was ehought thaË perhaps thls

eharrge ln furnaee ÈemperaÈure durf.ng Èhe pr@eess was an unnecessary reffnenent, of the proeedune, ll{.eh thls ln mfnd a serles of trfal.s were made at w'hl.eh furnaqe setËlngs remafned eonsÈant afeer Ehe ånf.t{.a$

teraperat¡¡re bad been set, Thc rmai.nder of Tab&e XLll Lne[udes the

resu1te of these ånvestfgatfons" Tabte XIV ls a suffinaay ef ehe eonsÈaÍ¡Ë

temperature Ër*a3,s,

The n¡¡nben of reptfeate samp!,es varåed smewhaÈ thnoughout this TABT,E XTTT

Effect of Fusion TemperaËure

on GoLd Losses 1850-21.00L 23.597 L47.8 L66"6 23"5L6 0.140 23"376 A"22L 0.98 LI"4 LBs0-2100L 2L"844 L33,4 1"s0"8 2L"786 0"trL9 2L "667 0 .1"77 0,81 Ì.6"0 1-850-2tr00y 26"5f6 L78"7 199"3* 26"3v7 0,152 26 "225 0 "29L 1,1"0 \7,7

LB50-2i.00L 2&."¿*87 L60"3 179,3 24,440 0"L40 24,300 0,187 0 "76 L6 "2

LB50*2100 L 22.3L2 LZ¿,""5 L42"5 22"302 0 "15L 22 "LsL 0, 1 61 O .J2_ L6 "7 0 cI\ Average Au Loss % : O,Bt \0 B

Average Au Reeovery : 99 "L9% s : 0.!.0

L950-2n00[ 1-35"1 0,107 A t" n"9 19"674 1s0"8 L9"547 19"440 "n4 " L7 ,7

1"950-2100y 2L"23a 148"4 160"0:r 20"6L3 a.097 2A "5L7 0. 71.3 3,36 X-5" ¿+ x.950-2100 L 26,347 L81"8 202.9 26.267 0.L27 26 "1_4A O "207 0,79 À0") r.950-2100y 22"045 154,5 17L"3 21"936 0"1"17 2L.869 0,176 0,80 18,4

1950-2100L 25,t+75 L60"2 f"81,5 25"396 0"L46 25"2s0 0"225 0"BB Iö.O

1950-21001 16,X.30 10s"5 118"8 16"00B A"A72 rs.936 0"x.94 1,30_ TR ?

"/, : Average Au Loss A "97 Average Au Recovery : 99,03% s : 0,21"

L the tower tenperature índícates Èhe iníËial temperarure and tlie htgher Eernperature indieates the fínal temperature attained roithin an hÕur, r'ç these beads formed rooLl"ets on eupe!.Lation and were re'i eeted" TempeTaturê Au Added Ag Added Sum Parted Bead Ag Retained Au Found Au Loss Au Loss % l,Ieight ï,ead Button (or) (*g' ) (*e. ) (me. ) (ne" ) (*e" ) (*g" ) (*g" ) ( grams )

9ç Q01 1 900 4J ô / / e x.64" 2 1B4" 4 2s.9s8 O "2t+2 2s "7L6 o "276 1 ,06 1s. 1

1 900 25 "750 n.63.I L84.7 25 "77r a "2&2 2s "529 a "22L 0,86 i.6.6

900 30 n o 0"20n 7 I " 4s5 BB.9 2r.4.3 30 " s30 "276 30,254 0"66 16,

L 900 1"46 9 166 23 0.226 23 o 0"75 23.746 " " r. "79s "569 "L77 L6.8

r.900 27.s82 L76 "9 L99 "6 27 "6ss a,2BO 27 "275 0,307 n_"07 16"f,

1900 26,3Bs n67"L I"89"0 26"297 0"258 26 "A39 0,346 tr _3Å I,4. B

d Average Au Loss%: 0,95 O{ 0 Average Au Reeovery = 99.05% s : 0.24 '!?o 2000 1"9"658 o 14s"3 L9,6¿+7 0"X75 L9 "472 0.x86 0.9s L7.7

2000 ?0,334 135, 7 't\2 O"tr 76 20.1"61 0.85 ^ 20"337 0"1"73 r.6"9 2000 2?,895 tr45"4 L64" 0 22.962 0"216 22.746 0.149 0,65 L7 "2

2000 24" s5B L{+7 "B I0/"o 24"s8t A"263 24"3L8 0,240 0,98 tq"i.

2000 28 "97 4 t"B3, 5 208. 0 29 "265 O "t+75 28 "790 0.180 0.62 1"6,9

2000 25,601 1 74"3 1.9s B 2,s 0 .280 2s 402 o, O:Jg L6 " .682 " [99 "t,

Average Au Loss % : 0"8tr" Average Au Recovety :99"L9% s : 0,L5 Temperature Au Added Ag Added Sunr Parted Bead Ag Retaíned Au Found Au Loss Au Loss % I.leight Ï-ead ButÈon (oF ) (*e" ) (rng" ) (^e" ) (nte, ) (*e. ) (me" ) (*e" ) ( grams )

21"00 22 "295 L26,s n 44,B 22.355 0,200 22"L55 0,140 0"63 17 "7

21"00 Lg x.34, s r.50 7 L9 0.118 "43!+ " "4L2 L9"294 0"L40 0"72 19"0 2L00 L9 "L99 128"0 x"43"8 L9 "196 0. r"s7 19,039 0.r.60 0.83 L7.6

0 2r"00 22,70L 1/+B, 7 x.68 0 0"L16 \, " 22.720 22.604 0"097 0,43 L7 "6 B 2100 2L x.s6 3 0,1"37 "804 L37.9 " 21,8L4 2L"677 A"L27 0"58 18"4 2i.00 2t,088 14X,3 !.58. 5 2L,O9L O"L26 20"965 0"123 O"_sg L7 "6 Avenage Au Loss %: 0"63

Average Atr Reeovety : 99"37% s : 0.1"4 Temperature Au Added Ag Added Sum parted Bead Ag Retalned Au Found Au Loss Au Loss l,^Ielght Lead Button (oF) (*e. (me" (*e" (me. (*e" (mg" ) ) ) ) ) ) (mg. ) (grams ) 220A 32.244 L92"5 218.3 32"293 0.232 32"061 0,Ì.83 0"57 r6.B

2200 23 X.54" n 70 n 1?1 "763 9 "6r- n "hAL 23 "270 0"493 2,08* 18. 4

2240 n.398 138,8 L57 23"362 o "7 "L26 23 "236 o "L62 0 "69 L7,2

2ZAO 21 , n 1.49 6s " X. L65 "4 18,0

2200 25 163 L82.7 25 0"L31 "794 "0 "792 2s.66L 0"133 0 "s2 L7.2

2200 24"868 tr 48.8 L68.7 2s"762 0"143 24"6L9 0 0,99 "247 L7 "9 2200 20 L36 1s1,9 20.L96 0 ,098 20 098 "264 "7 " 0"166 0.82 L7 "7 {0 2200 33 356 21"¿ç,6 Zqj 0 &\Ð " .4 3i "332 " r.74 33,trs8 0.198 0, s9 17 .5 I

2200 21. 1s3 1"3s, 9 15n 5 21 086 0 .106 20,980 o " " " "L73 0 "82 L8.2 2240 28.74L L72,3 L94"2 28 "648 0"145 28, 503 0"238 0"83 18. I

2200 L9.552 120"0 135.4 19,5¿î0 0. 107 19"433 0 " 11"9 0,61 16"0

22AO 29,774 L93"2 2L6"9 29.7s4 0 29.607 o o "L47 "L67 -55- t 7.3

Average Au Loss % : 0"70

s : 0,L6 ;t rejeeÈed since bead forrned rooÈLets Temperature Au Added Ag Added Sum Parted Bead Ag Retaíned Au Found Au Loss Au Loss % l'/eighr tead BuËton Toor (me" \ r',, (*e" ) ) (*s. ) (rs, ) (rng" ) (*e, ) (*e' ) ( grams )

2300 23 149 ,8 x.65. B 23,387 o 23 Ì.55 o 0,95 "378 "232 " "223 16, B

0 2300 35,04L LgB 3s n96 "4 224"6 " 0,500 34"696 0,345 0.99 16 ,0 (¡, B 2300 26 L65 183,6 26 0"336 26 058 0"69 "238 "7 "394 " 0,180 Ls "2 2300 24..586 L57.6 L7 4"6 2¿r"7 4L a "3L2 24"¿4.29 0,157 O"6t+ 15"8 .)â^^ ,4. Jc, þJVW L73 "4 L94"s 28"462 0,392 28 ,0 70 0 "LBz 0.64 T7 ,n-

2300 25 "27C L4s "2 16s,0 25"390 0"306 25 ,084 0,186 }rJA L6.7

Average Au Loss 7" : 0.78 Average Au Recovety :99"22% s : 0,16 Temperature Au Addecl Ag Added Sum Parted Bead Ag Retalned Au Found Au Loss Au Loss % Weíght Lead Button (or') (ms, ) (me. ) (me. ) (*e. ) (mg" ) (me" ) (mg. ) (grams )

T-B LL7 2400 " 168 "2 LzB,2 18,L66 0"111 18"055 0,113 0"62 Ls"4 240A 20 "0s2 138"1 L4s"9 L9 "s92 0"114 L9"478 0"574 2"86* 15,9

LsO L63 22"272 0"L39 0 2400 22"29&, "2 " s 22"L33 0,161 "72 14" I

2400 27 "L56 L6s"7 LBz"L 27 "L65 0"186 26.979 0 "L77 0,65 13.9

23 L¿+4"7 x. s9 23 0"L47 2400 "376 " 5 "362 23.2Ls 0"161- 0"69 L5,7

2400 25,679 148" 2 L66"s 2s.7L6 0.20L 25.sls 0"164 0 "64 J-O"I \¡ 28 L75 L97 29 o Þ 2I+OO "99L "5 "2 "t+25 "672 28.753 0"238 0"8L 1B"X t

24AO 2L"036 133"9 L42"4 20 "286 0 .330 L9"956 1,080 5"14't 15. 4 2400 24"507 152.8 L70 "9 24"782 0"485 24"297 0"2X.0 0"86 x.6,3

24OA 25, f.8¿¡. t 5L . I L67 "O 25.34s o "572 24,773 0"411 I "63* L6 "2 2L 2!+00 "333 133,8 L49"4 2L"ssg a,470 2f."089 A"24!+ 1"14 i.o " /

34"&,V 2L3 238 A 2¿+00 4 ,3 " 3 34"969 "73t+ 34.23s 0"239 a"*61_ r.)"o

Average Au Loss % : 0,BB

s : o.Ì-9 rejeeted sinee visibX-e portions of the Lead button were dispersed through the slag, Temperature Au Added Ag Added Sum Parted Bead Ag ReÈalned Au Found Au Loss Au Loss 7" I^Ielght Lead Button (*s. (*e. (on) ) ) (*e" ) (^g. ) (*8. ) (rg. ) (mg. ) (granos )

0 2500 32.399 L79,7 l,rl 0 2500 23,954 153.4 1.65.4 23.722 0"¡.78 23.544 0.310 1"30

2500 22"465 139.6 150.0 22.470 0 .L92 22.278 0, 187 0.83 2500 23"L22 150.1

2500 24.432 164"1 180"9 24"429 0.L92 24.236 0.196 0.g0

2500 26.597 L77.7 199"5 26.660 0.2L4 26.446 0.151 0"57

Average Au Loss % : 0.88 Samples i & 4 at 2500 were lost due Èo seepage of the s = 0.31 charge through Èhe cruclble.

Charge úsed for temperature sÊudy:

15,0 g. StO2i 85.0 g. PbO; zL.L g' Narco3; 4.5 g' cao; 0,9 g. flour. 0.9 - r.z g) polyerhylene bag -76-

TABT,E XTT/

Sunnnary of Effect of Fusion TemperaLure on GoLd i,osses

Temperature Au Loss % Ag;Au Ueight Lead BuEton oF) ( (grams )

i.900 tt 9\ a"24 6 I"6"0

åh u 2A0A u"0L 0.n"5 6 Lv 6 r

zLAA 0.63 0,14 6 1B"0

22AO 0"70 0"L6 10 17"5

23C0 û, 78 0"tr6 6 r-6,3

2404 0,88 nlo o 16.0

2500 0"88 0"3¡. 4 L6,¿$ -77 -

scudlr' Ln general a repeat trla!, was perfomed whenever ehe number of

reJeeted samp&es was ¡tr@re than one or søhen ghe results were e@nÈragy

Èo eKpeetatÍons, For the ËrÍ.aÏ. at 2500@F thfs praeÊl.se was noe f,o[!.oçøed

slnee fË beeame evfdent that t&re proeess çeas vlsfb&y breakÍng down"

Ac ehfs hfgh tenperature ehe sXag aeÈua3.Xy pemeated rhrougtr t&re eruefbtre

wa1'[ wlth@ut any apBaaent breakage of the eruclbl.e ftse]f. l\vo sanp[es srere entfrely !.ost ln thfs røay, Thts temperature was tbus gaken to be above the praeÈleal r.rpper llnit for the pr@eesso rhe exeessfwely

hfgh devfatfon Ln thls trfal supporËs ËhÍs eoneX.uslon.

A eonslderaËd.@n of the reraalnfng resu3.ts crould seem t@ LndÍ.eate

Èhat the praeËlse of Lotverlng the lnftfal Ëemperature and then nafsfrag

fE towards the endrdoes not yletd the best results w{eh regarde Èo mlnf.maf, gond Losses, Whf&e the nt¡mber of tmperaÊure eonobfnaELons sc¡¡dled was !.fmlted Ëo Èwoo these are e@¡ßn@nny used Ë,mperatures €or gof,d assayång"

l{Í.ttr regards to the eonsÈanË Ëempeaature studnese an optnmufii

ÈemperaËure fs f.ndleaÈed at 2L00oF" At Èemperaeures above thLso gold

Losses lnerease Èo a maxlmum of 0,88% and aE ËemperaÈures Lo¡øer than thls gold !.osses fncrease Ëo a maximum of, 0,95%, Ttre reason for et¡e breakdorwr aË Èhe hlgher ÈemperaËures has atready been suggestedu but the expÍ.anatfon fon the lower EemperaEure resul.ts Ls noE as obvlous, No doubt as Èemperature deereases Èhe Lnareased vlseosfty of che f[t¡x eønponenÈs mllleates agalnst the seËÈI,fng of the goïd parÈleles wh{.ch have not been eolleeted by r\e Lead, perhaps a[se of slgn{.ffeanee, ås the faet that [900@F fs rhe on&y ÉemBerarure be!.on Ëhe metrfng p@fnr of go3'd (1945@F)" At thl.s Lorser cernperature the s{.gnff,Íeanr dee,rease ln pneefslon {s eonsf.stent wfth the vlew thaÈ f,r¡såons shoutd rx@È be eondueted benow 2000@F" -78-

whå&e app[{.eat{on of a statlsÈleaå test tndleacee a slgrnfff.eant

df.fferenee beÈween rhe 23.00@F rrfa[ and onxy @ne other (3"900@r), and

ÊhaË onl.y at Ëhe 95% eonfådenee !.evel,u a fa{.r[y eønsfstenË Ërend

Èowards a ¡ufnfmurn go&d toss at z[00@F does appear È@ be fndfeated, [dhether lnereased losses wlth fnereaslng ËsnperaËure ean be attrlbuted

to lnereased Losses to rhe por watx. as Ëhe gotd vlseosLËy deereasesu

or Ëo fnereased vo[aÈft {.ty of ehe gotd ean noL be dedueed from thf.s

researeh" The overall average gold loss was 0.76% s = 0u1g" re shoul,d al.so be noËed rhar rhe wel.ght of tead burton passes through a maxfmum aË Etre temperaÈure where go!,d !.osses are mfnlmfzed, T*rls woux,d suggesr rhar the effect of lead bur,ron welght mlghr exptafn the obsew'ed tnend"

3, Effeet of l"ead Button f,Iefghr sn Gol.d Losses

Tn thfs serfes of experlments the go3.d &osses weae determfned ln exaecly Èhe same fashi.on as f.n rhe tempeaaËure seudy Just dåseussed above" ffi¡e alm of these experfmenËs !üas to determlne the re1atåonshlp betgqeen gol.d losses and Èhe wefght of !.ead button formed"

ftre eharge used was, exeepË for che wel.ght of reduelng agenc, unchanged fron che temperaËure sEudy and ls gf.ven at the bottom of

Table XV. &fs Èabl,e ls a stmratlon of the resu¡.ts obtafned çalth

TabLe XVT befng an abbrevl.ated surrunary of the sæìeo

lfsfng no added reduei.ng agent, Èhe average welght of, !.ead butÈ@n ean be seen to be 7.3 grêrns s = 0"7" addltfon of vary{.ng am@uncs of redr.lefng agent (fåsur) {¡rereases the welghr o€ nead bueË@n buË Ln an lrregutrar way" The ffrst 0.5 gnansfl.our lnereases button raelght by about f+ grams r¿hfne Ëhe nexÈ 0"4 gnams fncreases buËË@n weÍ.ght by almos8 9 grans' The next Ësv@ add{.tlons of 0"5 grams f3.our ear¡ses the b¡¡ËÊon wef.ght to fnerease by about z grams, ffie re1atfvel.y sna3.l IABI,E XV

Effect of Lead Bucron I,¡eighr On GoLd

Losses ItTeight FLour Au Added Ag Added Surn Parted Bead Ag ReËaíned Au Found Atr Loss Au Loss % I^ieight Lead Button ( grams ) (*e" ) (mg" ) (nrg, ) (ure. ) (*e. ) (*e' ) (me, ) ( grams )

niX. 29 189" zLA,6 29.325 o 29 o "2BB 7 "25¿," "O7L "2L7 0, 74 8.I 1?O nlL HLOLA/t7 134" '7 l. s L48.7 2L.LO? 0"145 20 "95V 0,L72 0"82 I ø+

niX 25. 210 3"73 I91"2 2s 0 x.77 2s,037 0. 173 0 "9 "2L4 " "69 7.¿r nr-i. 26 184" 202.3 26,2L7 a.L79 "244 L 26 "A3B 0,206 o "79 7"7 niL 27 ¿È4¿ï , 183"0 202,5 27 "455 O. TBB 26 "867 0"577 2"LLtç 7,A nitr 22.448 14T."0 156,s 22.350 0,155 22"L9s a "2L7 0,_9_5-

0 Average Au Loss % 0"80 = \o 0 Average Gotr d Recovery : 99,2Q% s : 0"10 0"5 28. s5B L72"6 1 94, s 28 " 571" 0,239 28"332 0"226 o,79 x-1"0 0"5 36.503 2L8.7 246.s 36,sl9 0 "32s 36 "L94 0" 309 0"85 10. s

0,5 L7 ll8.s 131 17 , i.9B 0 L7 0,14s "227 "5 " 11_6 "082 0,84 1L,2

u") 22"LL8 L37 1s3 9 22.L76 0. o ,2 " 0.206 2L.970 L4B "67 LA "7 0,5 3C,837 210"4 233,9 30 " 844 0.27s 30" s69 0,268 0"87 1"0"9

ud.f 30,067 194"0 2r.8,9 30"Li.2 0,26X. 29 0 ztr 6 o 'tt ? "85L " "13._

Average Au Loss 7. = t"79 L1"t" Average Gold Reeo\¡etry : 99"2L% = 0,08 0"6 ìt rejeeted on sËaËisticaL grounds ï'Ietght FLour Au Added Ag Added Sum Parted Bead Ag Rer:ained Au Found Au Loss Au Loss \^Ieight Lead BpËron ( grams ) (*s" ) (*s" ) (*e" (*e" (*e, ) ) ) (*g, ) (*B' ) ( grarns ) nq 22"295 L26 "s X.4¿r,8 22,355 0"200 ZZ,\S5 0"tr 40 CI,63 17 7 ncì r.9 434 L3/l.,5 1.50 7 1"9 0" " " "t¡Y2 I"18 L9 "Zgq 0"1¿+0 A^72 19,0 nq XQ ÏOA n 28"0 x.43"8 r.9"r.96 0.1s7 1"9"039 0,160 0 '!-7 "83 "6 0"9 2.2,7AL L48.7 168.0 22.72c 0.116 22"6A4 0 0" "097 43 L7 "6 oq 2L 804 L37 n s6 3 21 0 2L " "9 " ,8X.4 " x.37 "677 0 "L27 0.58 x.8"4 0"9 2L.0BB 14n "3 r"s8"s 2L.09L 0"1.26 20"96s 0"L23 o,_sg 17.6

0 Average Au Loss%: 0,63 1B"0 co O å Average Gotrd : Recovery 99 "37% s: 0"14 0,6 22"4¿ï3 L{+7 "4 L66"s 22"480 0.231 22,2s8 0"185 0,83 2L"L L,5 2l+"65A L67,3 186"8 24"6s6 0.2s8 24"398 0.252 L "02 2L "2 1"5 ?,6.597 166"0 L8B"B 26"568 0,24/* Z6"iZ4 4,273 1 02 20 " "0 L"5 28,64L L77 "6 203"3 28"759 0"312 28"447 0,68 0"194 2L "6 19 L64 'j-¿þ9 " 133,6 ,3 Lg 0 178 L9 .042 0 "22a " "L22 0.6¿r l- 9.0 TE !,âJ 20.660 134,0 L5¿',"2 20"706 O,X.BO 20.326 0,tr34 0_6l ry"1 ,herage Au Loss % : 0,8tr 20.6 Average Goi.d Recovery : 99"L9% s : o'L8 1'0 i'Ieight FLour Au Added Ag Added Sum Parted Bead Ag Retained (gran.ts) (ms,) - Au Found Au Loss Au Loss % I,treÍght T"ead B¡:rron (ms") (ms") (*e,) (*a") (me,) (re") (grams )

2"0 2L.269 L47,0 T.64"8 2L.329 0,183 2L"L46 0.123 0"58 27,0

,n 22"2s6 148"6 .t oo, ) 22"282 0, X.g¿l 2.?,0BB 0"L68 0, 75 ,l\ q

2"4 20 X. "LL7 131., L46 "9 20 ,063 0. r.47 19,916 0, r.B1 0.90 28. t 9n 20 L30"2 1.46, ? 20 0.17s 2A,24A o "366 " 41s "L26 0"62 7"7 .2

?,0 28 tB9"s 2L2"3 28,01s 0,226 27.789 0 "0L7 "228 0,82 /_I "å

áê\J 20,839 tr 35.0 L52"5 20.849 0 tr"61. 20,688 0. tr"5]. 0 " "7_3 A-9- 0 :0"73 @ Average Au Loss % 0 27 "2

Average Gold Reeovery = 99.27% Þ '9, - ^ \J") 2"5 ')R L74"7 L93"7 28"22A 0"252, 27.938 0"341 '74 I "24"¡ 34" 3 ?q f or Á 27 L7O.B 27"03t+ 0"23C 26 B0¿$ 0 :f.,08 "098 " "294 32"L

26.9t 5 L70 r"93 2 26 O "3 " "962 "2t+5 26 "7L7 0, 198 0"74 34" 3 7,"5 2L "78A L43.2 16L,3 2L "81.2 A "Lg7 21"61s 0,1.6s 0,76 33"9 2"5 2t"',"367 L61,2 1B0"3 2t""422 C"196 2t+"226 0.tr41 0"58 33. 7 r)Ê 26 L67.7 i.B9 B G"22a "298 " 26"375 26 "L5s 0"L43 Average Au Loss % :0"74 Average Gold Reeovery:99.26% s :0.2tr 1n

nejeeted due co spitting of the cupell-ed bead

Cl'rarge used: fLour-varíed t 15"0 g" SLo2i 85"0 g, Pb06 ?L"L g" Na2CO3ç 4"5 g, CaO -82*

TABI,E Xl'T

Sunurary of Efiect of Lead Button Ideight on Gold

ï,o s ses l,ieighr FLour Au Loss s Äg:Au I,'ieight Lead BuËron ù ( ç"*"-" ) (%) ( grarns )

,.'tr -rl!! C. BO 0,L0 6"6:L"C 7,3 4"7

v.J n7q C"0B 6"îzL,t 11"L 0"6 nq 0"63 û,14 6.5:1.0 LB, c 0"6

r") 0"Bt 0 6.6:l " tg ,A 20 "6 1"0

,r\ 0, 73 A 6,6 :1" "LZ .0 27 "2 U"J

'.,," / 4 fi .2L 6 ,4¡L "0 33,9 t^ -83-

'Lnerease ln bue,ton we{.ght øE 2,6 grêrns on addj.tlon of 0,6 gnams fxoun grams Êo 0'9 may have been due Ê@ an experimenËa[ reason" T&¡e draf,Ê

of Ëhe furnaee was aeefdenta!.[y trefc open from the prevåous eupeLtaÈfon.

sfnce the doon of the fuznaee $pas not e:Ëaet¡.y alr-tfght, an f.nereased

flova of afr I'n the fu¡rr¡ae,e nlay have malntafu¡ed a Less effeeci.ve reduef.ng

atmos¡rhere" The larger standard devl.at{on {n the wefght of lead but,Ë@n

{n thfs experlmenÈe as wel.l as the flnat one of, tbe serle$e may

refleee {.nadequate nfxlng of rhe fl.ux componenÈso

A sÊatlstleaX ana!.ys{.s of ehe resuX.ts f.ndieated varlatl.or¡s fn gold &oss as a funetLon of Lead buÈton erclght ldere not sf.gnff,leant at

tbe 99% confldenee neve!.. Tn che deve3.opmenË of, an optl,mum proeedure

the telal' havfirg a nead butt@n wefght of &8 gra¡ns sqas chosen mere!.y

beeause the goLd Í,oss was a mrnfmr¡m for chi.s røelght of !,ead,

fre average gold 3,oss for thls study r*as thus f,ound to be o"l3% :0"[4" I sfnee nelther Lefinperature or wefghe of tead butËon !üere obseryed Èo have a slgntffeant effeet upon the gold Losses at the 99% esnfldenee level a statlstlea!. test of sfgnffleant dffferenees should eonfl.:m Èhl.s" The overall average gotd Loss of 0.76/" s:0"[g for the

temperature scudy when eompared Ëo Ëhe overatr l average 3.oss for the

study under eonslderatl.@n fndieated no slgnffieanË dl.fferenees beË!úeen

the two Èrla3's" T-&rf.s ¡vouI.d be the case even at the 95% eonfldence i.eve&, ¿+. Ef'f,ecc of Fusfon Tlme on Gotd tosses

The obJeeelve of thfs portlon of Ehe researeh ssas to deËermfne

the shortest Èfme requlred for the smaåLest gox.d &osses. Fr¡sf.on and

eupenlat{on tsnPeratures were 2!.00@F and 1800@F sespeeÊflve&y, for aå& ass&ys, Sarsples were prepared as previous!.y deserlbed wfeh a charge as lndlcaLed aE Ëhe

boetom of TabÍ'e xvÏlÏ" Tabte XVrl {.s a detal8,ed s'eeord of rtre Eeeu[es of ehe tlme sÈudy and Tabïe xvrrr fs a sursnary of the same"

sLnee assays qrere done ln grouBs of slN, and s$.nee some samp&es TABLE XVTI

Effect of Fusion Tir-ne on

Gol.d Losses Tlme Au Added Ag Added Surn Parte¿l Bead Ag Retained Au Found Au Loss Au Loss % I'Ieight Lead ButËon (hrs) (*s" ) (*s, ) (mg. ¡ (ne" ) (r:rs. ) (mg" ) (*g' ) ( grar'rs )

2L"965 1s9" 21 984 a 2r" 808 0,71 0,5 L40.7 s " "L76 " 0"157 18"0 n '7D 0. s L6 "92L l-l_L"6 L25"L L6 "928 o "L29 1.6 "799 a "L22 LO.l

17 Â c" s 26,69L tr"83"/+ 208.6 29 "7s3 0.236 29,sr7 a.L74 0, 59 L. 4V

1+ o 9n7 0, s 24. s13 L6/+" 2 1B5 " 24. ss3 2¿\"3&6 u"¿o/ 0,68 T7.B

1'7 â 0, s 22"6\s 1"s1"6 171"0 22"632 c, tr-86 22"4fþ6 0 "L69 o"75 L I aW @ 0, 5 2¿*.2L2 160"2 1.8û, 7 2&.226 Ð 24.}ttt 0,2L2 0 16, L .Ê. "226 "87 c 1Dâ ? 0, s 16. 2B1" tr_1"0. 7 L6,276 0,11t x6,16s 0. L16 0. 7tr 18"5

0, 5 22.98L 1-35.7 L54,7 22'3A6 0,163 22,Lf43 0,L44 u"o) L7 "5 0.5 22"287 L52"L 170"8 22.998 22"8{"r5 0"L36 nqo 11 'Ì

0 25,050 L63,9 185"L 25,A6L 0"162 2,4"899 0.151 0.60 18. 4 " 5 1 71 .) 1-Ì , 0"s 28"323 x.97, I 2B "242 0"206 2e.036 0.287 1" 01"

'âA 1 0,5 24,042 154" 3 L74,7 24.060 0, L90 23 "B7o a "172 %J3. Lv õ , Average Au Loss %: O.72 t\verage Gol.d Recovery :99,28% s : 0,12 Time Au Added Ag Added Sun Parted Bead Àg Retained Au Found Au Loss Au Loss % I'Ieigirt tead Button (rs" (rng" (hrs) ) ¡ (ts" ) (mg. ) (*s" ) (*g" ) ( grams ) 1n1 L"0 27,262 L 70,0 1_92"8 27 0.1,93 H,?7 êLv¿ 0"L59 .296 0,58 L6 "2 11 ìnf 1"0 2?""tv32 15X 2 L70,û 22"460 0,1s9 tukôJJL 0,131 0,58 " L6 "7

L,0 30.635 1.8s" 6 2LÐ 30 Cr 3A ¿ï62 0"L73 rì tr? "9 "674 "ZLz " 1"8"0

L,0 26,5¿+7 16s"2 L87.6 26"609 A"220 26,389 0,158 0.60 1.7"0

r. ,0 ?3,809 1-c$9, 9 L69 0 23 0, "9 23,830 "L70 "66A t/+9 0"63 L7 "6 æ 2L"576 2L C.1"60 (¡ L.û 144"B L62"6 "sB6 2L,426 0,1 50 0"69 1_7 "6 0 q/, 1 .0 x" 9. 735 t_ 28, 0 1.44. 5 0"08s L9 rì x-7 4 L9.7L4 "629 0,106 Ll./a

27,7L8 tr 80, 202"5 1"0 5 27,685 0"147 27 "538 0, x80 0"65 18. 1

1"C 25"242 tr 51r"L L75"I 25 "224 1B. 4

1 C ?"4.7L6 1"64"0 183,B 0.101 " 24"680 24"579 0 "L37 0,56 1B,3

I 29,354 2L4.4 29 32s "û 190,2 " 19"2

27,663 198"8 27 Ð 1,0 178"3 .628 "L62 27.{"+66 o "L97 orJÅ LB,4

,\verage Au Loss 7. : a'6L : i\verage Gold Recovery 99 "39% s : 0"06 Tirne Àu ;\dded Ag Added Sum ParËed Bead Ag Reraíned Au Found Au Loss Àu Loss % I{eight Lead Button (hrs) (*e,) (ng. ¡ (*s" ) (mg" ) (*e" ) (ns. ) (*e, ) ( grams )

1. 5 22"297 14s" 5 163" 0,082 O"LLz " s 22"267 22"18s 0,50 L7 "9

1 ,5 22,285 L52.4 L70,7 22"L98 0 19 Xr7 0"tr58 0 70l.' "07L " L7 .L

n n7ô r L,5 23,567 148, L67 "B 23.s?g ^ 23.t+37 0,n30 0, 55 10

27,534" 1A I 1""5 L68,9 L92"9 27 "¿r78 0 "097 27 "3BL 0,153 0,56

1.5 27 L64,5 LB7 27,209 a 2_7 c)" "242 "3 "L27 .Ð82 L60 0"59 L6 "7

2L"871 L30,3 ?"1. BB9 n 1?9 x..s 1/+9.3 2L.757 0,114 o "52 1"8" s 1"5 L9"t+57 L30.4 æ 6r 1 30,6c+tr" '¡ qc n 209,8 30 6s5 0"LBg 0 " 5 " 30 "t+67 0, 174 0.57 17"0

1,5 23"937 1"58"8 tr 78,8 23 0"134 23 803 0,134 "937 " 0.56 19.3

2t+"LL3 LsB,2 178, 1 24,LL6 0 L4¿¡ 1,5 " 23,{¡72 0,tr41 0,59 2L"2

1. s 25,634 160"0 1.8tr B 2s tl 107 25 " "686 "¿¡89 0"14s 0,57 tB,9

1r7 R 1.5 20"263 14s"B 2A "25A 0"12s ztJ.L25 o. r38 0_"1!. tnl

Average Ar.r toss % : 0"56

Average Gold Reeovery : 99"¿r¿f/. : 0.03 Time Au Added Ag Added Sun Parted Bead A,g Rer:ained Au Found Au Loss Au Loss % I,treight Lead Br.rî:ton (hrs) (ms" ) (*s, ) (*e" ) (rs, ) (*e, ) (rng, ) (me, ) ( grams )

3,0 2{+ "937 L54.2 L75,3 24"91"5 0,110 24"805 0"1"32 0.53 19"s

f qo ,, '4qq 0 \J õ LJfu 1Q n 2"0 22^¿þ47 146"8 lo).lc " 1"04 2?-,295 ^ u"oö B @ 17Q j { t-58 l" 25.6s4 a 25 0,149 0"58 19"0 0 " ^L27 "s27

LB6 26 0 26 0, L33 0"5L 2,0 26,24A L64,3 "2 "238 " x.31 "L07 18,0 t? n .?" 26 L7L 26 0. 26 0 0.67 j" I 0 "56!+ "3 193,5 "s29 L42 "387 "L77 "2

0 De 7(a 0 0 2,0 23,732 r60"s 180 " " 135 23,618 " 1.14 0.gB tr 8"3

Average Au Loss % : ll ax

Average Gold Reeovery : 99,¿r?:i" Þ : 0.08 Time Au Added Ag Added Sum Parted Bead Ag ReËaíned Au Found Au Loss Au Loss % Lte{ght LeacT Button (hrs) (*e, ) (*e" ) (*e" ) (ms" ) (mg" ¡ (rns. ) (ms, ) ( granrs )

2, L ¿å1 0 s 21,684 . 5 \60 "7 2L "63!+ .094 2L"540 0"L44. 0"66 18.1

23"200 Li+9 r.68. B 23 200 0 Í.61. 23 0.161 1\ ) 2"5 "O " " "439 0,69

2u5 23.25/¡ t"s6. 7 L76.2 23. 2sB 0, r.35 23 123 0 131, 0 'I 7 n " " "62

'7 2L,52t', 1-42"9 n 21. û"102 2"5 ^'r. " 486 21 ,38¿s 0,140 u. o) 18, X

2" 26 .836 176, 9 201. 9 26 0"t57 0 5 "837 26.680 " 1s6 U. Jö 18. 6

1 7') -7 ry-ì 2"5 2L.575 i.sI"s ztr. s33 0 x"06 eL91 õ -"Ì44 | 0, 0"69 10 1 " ^ t48 0 æ 2" s 22"295 L26 11+4, B 22"35s 0"200 0"L40 rl Áa 1't a æ "5 6

19"43¿¡ 1,31+" 5 lCn 7 L9 0"11B L9 0 4"5 "4L2 "?-9¿v " x.40 0,72 L9"0 y".!")/ 2.s n9.199 128"0 11+3 , B 1"9" 196 1_ 9.039 0, L60 0, 83 1-7 ,6

9q ,r1nn at ¿1 1¿ç8"7 1"68 " 0 22.724 0, xL6 22"6пþ 0 ,097 [/"0

'[ Cì 2l_ 804 â.' 1.56 3 2t,814 0. L37 2L a 2.5 " " "677 "L27 0.58 r-8.4

2"5 ?n""088 r,4x" 3 L58"5 2L o 2C o O_"jrg L7 " "agL "L26 "965 " x.23 "6 Average Au Loss % : 0"64

n 1rì Average GoLd Reeovery : 99 "36% - Tíme Au Àdded Ag Added Sun Parted Bead Ag Retained Au Found Au Loss Au Loss % hleíght Lead ßuELnn (hrs ) (*s. ) ('e' ) (^s" ) (ms" ) (ng" ) (*e" ) (*s" ) ( grams )

0 3,5 31"¿+80 189, 7 2L4,7 31. sls "2{.v9 3L"266 0"2L4 e).68 16"I

r.B"B29 1"L9 133 7 1 8, 858 0 tr"47 0,lt_B 0"63 r"6"3 3.5 "2 " " 18.7X.r.

3 20.866 20 55 0,I"58 A,269 ZB:k .!./"J " 5 r-37"3 1.sl"9 "7 20"597 t,

6r.3 1Q ? 3.5 1B"591 L22,3 L37.3 18 " 0.1"46 Ì"8"4'67 0"L24 o,67

tr-7 026 i"1_7"8 1.31"2 17"033 0"n"l7 L6 0, t.10 0. 65 16"1- 3,5 " "9L6

3, 22,131 1"¿s8"1. 22.L34 0 L9¿+ 2T 0, O. BB s 130,6 " "936 tr9s t)"o 0 @ \Þ 20,561 130, L45" 4 20 û"L37 2a A,269 l" 30"r L6 3"5 s "4¿rg "?.92 " "7 0

3 5 22.270 L57 22.255 0 1"62 22 0 . r_ 77 0 .79 14"0 " L40"3 "6 " "093

.- a 3,5 2L"56V 133.9 1sl .4 2\ "sgz 0"L59 2r "b,23 0. 144 u"o/ LJ"O

20"798 144. n62 20 0,1"54 0 3"5 5 "0 "792 20.638 " 160 4.77 17"8

26.7t+7 186 26 3"5 tr.63,7 " s "796 0.205 26.sgl 0"156 0,58 16"0

3,5 24,3t-vz 158,8 i"7B"s 24.392 0,20t" 2¿r.LgL 0. f"str 0_",6? T7 .2

Average Au Loss % : O.69

Average Gol.d Recovetry : 99 "3\"L : 0"09

* rejeeted oß statf.sÊleal gnounds -90-

TABTE XVTTT

Summary of Effecr of Fusion Time on Gold Losses

Time Au Loss n Ag:Au trtteight Lead Button (hrs ) ("1) ( grarns )

0 0 0.5 "72 .09 5 6"5:1"0 L7 "3

0"5 a"73" 0,tr5 5 6.42L "A L7 "7 L,0 0.6tr 0"05 6 6 "4tL.0 L7,2 1,0 0"62 0 ,08 + 6"4:1"0 18"3

1 q n q,/, {r \J ð J"t 0 .04 o"i:r"(l ^

tr r^ Lo,r u,)/ 0 .0n 6"4:1,CI ^

2,0 0"58 0,08 6 6"4:1.0 18. 6

'? 2,5 0.65 c"04 b 6"6;1"0 x'7L! a t

2,5 0"63 0.14 6 6,5:1"0 I8.0 0,70 3,5 0"10 5 6,3 :1 .0 L6 "9

a"69 0 3,s ,09 5 6 "4zL "A 1.5 "7

Charge used; 15.0 g, Si.CIZ; 85,0 g, PbO; ZL"L g" NarC0rl' r+.5 g" CaO

I "0 g" flour -91 - had ro be æeJeeted o¡r oeeaslon åÈ, was deelded that eaeh assay shouåd be repeaËed by a duptr,ieaËe trla3., T,n thfs vray some {dea eyould a$.so be obtalned of, the reproduefbfxÍuy of the eonp&ete fLre assay pr@eess" Ttre resuÅts found ån Table XVIII refleet thls eomparlson and s{fËh the exeeptÍon of the 2 hour trlal. srhleh nas n@t repeated che dlf,ference beæreen any Ëw repeaÈ trfaïs was never greater than 0"03%. Put ln anoËher way, the reproouefbfnlty of gold rec@very i.s of the orde¡r of

3 parts f.n 101000"

A conslderaEion of the resul.ts of TabÅe XVII fndteares a def,fnl.te

Èrend ln gold !.osses begfuurlng w{th a maximum gold Loss of 0" ve/" Eør a ä hour fi¡slon and !.osses of 0,6X.e 0,56e 0.58, 0.64 and 0,69% for å.00 !."5e 2.0, 2'5 and 3'5 hours respeetf.ve!.y. A staÈfstfeal, analys{s of, t&¡e resu&ts f.ndfeates ËhaÊ Èhe mlnfmr:m gol.d 3,oss røhi.eh oeeursed for a fuslon Slme of 1"5 hours ls signffleantly dlffe¡rent f,rom rhe 0,5 hour and 3"5 hour Ërfals at the 99% confldenee åcrret and a3.so dlff,ens from the 2"5 hour Èr{aX. at the 95% eonffdenee &eve&" I%e optfutt¡m Èfme of fusion vgoul,d therefore seem to lle Ln the range of 1.-2 hours wf.th Lltt1.e t@ ehose between those XfmlÈs,

It should of eourse be reoæbered thar rhe goLd of the sæpl.es under eonsåderatfon ls not eheoleal.ly bound, but mere!.y a mfxture, Tr¡ those eases where the ore lnvolves a ehml.eat eomblnatlon the best xength of tlne for the fusl.on E r@eess may df.ffer signlfreant[y. trn po{nt of faet most goïd ln naËure {.s Ln the elemental sÊaËe and eonelusåons reaehed here should be aBp[f.eable prov{.ded the ore ls ftnely dlvfded"

A eons{.deraËi.on of Tabl.e XVffI a3.so lndleates that the wefght of tread butÈon may vary by as mueh as n,5 g" under apparently fdentieax eondltíons wfthout any s$.gnlfleanË effeer @n the go3.d 3.oss. ffirls faer -92-

ls eons{.sËenË w{,th the eone1usi.on of che reåated study c,onsådered ab@ve" (trffeer of llelghc læad Button)

5, Effeet of CupeLlatl@n TemperaËure @n Gøtd tosses

Lt ¡sf1I. be reeal.1ed ehar elalns are €reqra@nË[y made rhar the

ternperaÊure of eupetlaÈfon fs one of, che rnost lmBorÈant varlab!,es

affeeting goLd loss" The eupeltatÍ.on Loss reported fn the l,fÈeraÊure

fs often based on gold nosses for a proeess whleh was ear!.fer trabe!.}ed

as a r8s{muf,aced eupel1aÈlon!8. The Xosses detea"må¡led trere fr¡volve the eupe3,3.atlon of a Lead button eonËalnfng rhe sf!,ver and gold ln whar must be e3.øse Ëo a h@mogeneous altoy of the meËal.s fnr¡olved, x3re behavfor¡r of gotrd ln sueh a buËton, may dfffer sfgn{f,leant!.y from che pure gol.d and sllver wrapped fn &ead fodn o€ the same welghÈ,

Tbe fuslon e@perature Bras ma{.ntafned eonsËanc aÈ 23.00@F vylt&r a eharge f.dent{.ea& t@ that used for rhe rfrû@ srudy (boccsm of Tabtr.e Xlruftr)" Samp1.e preparatlon Þ¡as fn rtre usua3, way, T&e eupe&natlon procedure lnvoLved an fnítlatr tfme of 5 níauces hcat{ng wfth rhe door and draft eLosedu a drLving fnter,\ra3" dependent on Ëhe slze of the n argest Lead button, and a 5 minuÈe ftnlshfng perf.od" Ttre parËrng proeedure fnvolved Èwo ac{d Èreatments ¡øf,Ëh 1.:4 a¡rd 1sl nftrfc (aefd: ssater) foltovred by three washlngs ÌyLth t¡@t &rater" lhe anneaS.ed bead vaas wefghed and then anal.yzed for sllver by aÈonle absorptfon as usuat.

lbe fndfvfdual, entnles from thlsseudy are reported ln Table XIX and sumnarfaed f.n Tabte )0(, For the foun Èønperatures str¡d{,ed the ma:{{,mum dÍfferenee becween repeat Ëråa[s oeeurred at the håghest

ËenperaËure of, 2000@F and eorresponded co 6 parts per &01000 w$.th the mfnlnum diff,erenee sf 3 parÈs ln 1.01000 oeeurrlng at Ëhe ÈT{o S.owest

ÈemperaËures of ¡,800@F a¡rd 1700@F" fre mfi¡åmt¡m go[d !.oss oeeurred aË

1800oF, the usuaf, Ëemperature of eupelxatlon used ehnoughoue Ëhfs TABTE Xg

Effect of CupelLaËíon TemperaËure

0n GoLd Losses TemperaËure Au Added As Added Surn Parted Bead Surcharse AE Retained Au Found Au Loss Au Loss % " (oF) (*g' -(*e" (*e" - ) ) ) (*g" ) (*e' )- (nre" ) (*e' ) (*e, )

2000 20 x"38" 6 153"4 20 802 0 0L3 0" 17L 20 "789 " " "63L 0.158 0.76 2000 i.9 001 L23 L9 /+6 " "7 138,2 "OL7 0,0L6 0, n 18.871 0"1,30 0"68

2000 20 131"2 1.46 L 20.298 *0,071 0"n 54 20 0 "369 " "L44 "22s 1",10 2000 25"428 x.71 I L90"s 25 âsL 0 0,204 25 0, " " "023 "247 [8r. 0, 7x

2000 23 x.63 3 180"0 23 0"2x.1 23 O r. 00 "928 " "902 -a"026 "69L "237 " 2000 24"363 L59,6 1"79 "2 24"323 -0"040 0"203 2r.ï"L20 0.243 1,!!- \oB Average Au Loss % : 0"BB CÂ, 0 s : 0"LB

2000 2L L36,L 1sl_ 9 2L "426 " "366 -0"060 0,1L4 2L,252 0,n-74 0"8tr 2000 2t+,836 L52"L L70,2 24"676 -0" L60 0.118 24,558 A"278 1"n2

2000 25.04.9 1 60.0 L77 24"998 0 "7 -0.05r" " 136 2t+.862 0"t87 0,78

2000 23 145"L L62"9 22"9s9 0"t03 0 r" "027 -0"068 22.856 " 71 0, 74

2000 2L L43 1s9"8 2L.232 0 1_03 2r 0" 0 "292 "4 -0,060 " "L29 ¡.63 ,77

2000 28 s5B 191 2L2"5 28"496 -0 0,133 28 0 0,"6s- " "3 "a62 "363 " 19s Average Au Loss %: 0"82 s : o"L6 oF, Average for both tríal s at 2000 AuLoss%:0"85 s:0,L6 n=L2 Ag:Au :6"5 s:0"2 n:\2

Lead tr'Ieight : tr5.0 grarns s : n "3 n : L2 TemperaËr:re Au Arlded Ag Added Sum Parted Bead Sureharge Ag ReËained Au Found Au Loss Au Loss % (or) (*s" (*s" (mg" ) ) ) (*e, ) (*e" ) ('g, ) (*s" ) (*s" )

I" 900 26,539 164"3 26"55¿+ 0 I-85"8 0,015 " 165 26"389 0" 150 0,59 900 t ?,7 "256 L72,4 193"0 27 "L76 -0"080 0"1-6s 27,OLL A"245 0.90

L 900 2t ,306 L37.9 2L,276 154"0 -0,030 0"132 2L"L44 0"162 a "76

1 900 25 168,s tr 88"3 25"266 -0 024 c 25 "290 " "L37 ,L29 0, 1.61 0"64

co 1900 22" 80s 1sl ,2 L69 ,7 22. BOs 0,000 0 C, tr V " 1"33 22,672 33 ^ ð JO

1.900 22, s38 141"5 1s9.3 22"s39 0 0 0 " 001 "L¿"7 22.392 ,146 U"OJ

0 Average Au Loss % : C, \Þ "69 #. 0 0"12

1900 26 "9L6 16s. s 1-85, 6 26 "926 0"0L0 0.171 26"755 0.16T. 0"60

tr 900 23,L62 1s2"8 23"L32 L69"4 -0"030 0"14s 22"987 0"1.75 0 "76 I 900 18"3s9 123.3 135"6 L8.349 0"0tr.û 0,x"02 LB^247 0"I"X.2 0"61

1 900 22"6tt7 L41" s L59 22.6sL 0 0, 1.3 0 "4 " 004 7 22,5L4 , I"33 0"59 1900 27,626 L70 "6 1-92,9 27 .620 -0,006 0, 183 27 .t+37 0, tr"89 0.68 I 900 25 "t+j-O L61"8 180"6 25.426 0 "016 0.L79 2s"247 0" 163 q.,i3 Average Au Loss % : 0,65

0,06

Average for boËh trials at 19000F Au loss %: 4"67 s : 0"10 n : 12 ;\grAu :6"4 s:0"2 n:L2 Leadlleíghc :L4,0grams s:0,8 n:LZ Temperature Au Aclded Ag Added Sum Parted Bead Surcharge Ag Retaíned Au Found Au Loss Au Loss (oF) (rne,) (*e") (ms") (re,) (*e,) ('s,) (*e,) (*s,) 1800 22"297 145,5 163"5 22"267 -0"030 0,082 22.L85 0.L12 0"50

1800 22,285 152" 0 L7A 22.L98 -0 ,087 0.07L 0"1s8 0 70:t "7 22"L27 "

I 800 23 148. 767 23. s09 058 a 0 "s67 Ì. "B -0 " .072 23.437 " 1"30 0"55

r.800 27,534 L92.9 27 ,t+78 -0 056 0"097 27 0"L53 u")o 168.9 " "38L

1.800 27.242 27 03L 0,1.60 I-64.s 187.3 "2A9 -0 " 4.L27 27,082 0" 59

1 800 2L,87L 130"3 L49"3 2L +0"0nB 4"L32 2L,757 0"1l_4 o-.-5-4 "889 0 \o (Jl Average Au Loss % CI,54 0

Þ 0"04

n B00 19"457 130" 4 Lost tost Los t los t Los t n osE tos l:

r.800 3û,641 0"0L4 0 t"BB 30 0,L7 4 185,0 ?09"8 30,6ss " "t+67 0, 57

x.800 23,937 158. B 178"8 23 "937 0"000 0,134 23"803 0,r.34 0, 56

1"800 2¿$,113 L58"2 t 78.1 24.LL6 0,003 0 "Lât+ 23 "972 0, n 41 CI, 59

25,634 160" 0 1"81" a a 25 1.45 tr? 1800 B e5,686 .052 .L97 " 489 0, ^

I"800 20,263 127"8 L4s,B 20 -0 0tr.3 0, tr 25 20 0 138 0r 58_ "zsa " "L25 "

Average ,4,u Loss % a,57

s- 0 ,01

Average for both triaLs 1B00oF Au Loss %: A,56 s : 0,03 n : 10 Ag:Au :6"3 s:0,2 r'l:L0

* rejected on statis icat grouncls Lead I'Ieight : 18,7 grams s : 1"4 tc) Temperature Au Added Ag Added Sum ParËed Beacl Surcharge Ag ReÈained Au Found Au Loss Au Loss % (oF) (*9" ) (*a, ) (*e, ) (*g" ) (ng" ) (*g, ) (mg" ) (*s, ) L700 26,802 161,8 185"3 26"815 0,013 0.X.7tr 26"6¿v4 0"158 0"59

t 700 2g 491 L97 223 28 0,L54 0" 73 " "3 "2 "537 0"046 28.283 0,208

1 700 0.L2¿r 21"19B L!+2,t+ 160"5 2L " lBL -0"017 21,057 0"L¿+1 0"67

1 700 LB" 806 L20,7 f¡ozen f.tazen frozen frozen frozen froaen frozen

l^ 700 26 .!.)o,o L82" 0 26 0"1 37 25 0 0,56 "L09 "LOL -0,CI08 "96t+ " tr"45 1 700 26 "LLs L62"7 f.tozen frozen frozen frozen frczen froaen fLojaeJt \0ù Average Au Loss % : 0,6dr er 0 s : 0"0-8

tr 7CI0 25"st1 L62.L 183"9 25 "485 -Ð "026 a "Lo7 25,378 0"r"33 0.52

I 700 23, L90 n.52, s L72"t 23 "LB7 -0.003 t "L42 23"045 0"1/*5 0"63

9rì 11 cl 170C T.61" ,3 L82,7 2s "246 0"427 0"1,63 25.083 0"1.36 0"54

1 7nn to ocn X"l¡0"3 158. 4 2C¡ 0"X.0/+ 0 "92t+ -0"026 20"820 0" n30 "62

f ô7 I 3.700 L(JI êL nlo t ZB 0 28,362 " 3fl9 -0, û53 ,L72 28.L37 0"225 û"79

l.700 22"686 tr1+L.7 L62"B 22"7A4 0 "c18 0" 14s 22"5se o "L27 0_,1_6_ Average Au Loss % : 0,61

s : 0,1.0 Average for both tríals at 1700oF Aul-oss%:A,62 s:0"09 n:L0 Ag:Au :6"t+ s:C"3 n:L0 Lead'Ì.deighÈ : L5"3 grams s : Û"9 n = l0 -97 -

TABI,E }ffi

Summary of Ðffect r:f CupeX.Lation Temperature

On Gol"d Losses

Tenpenature Au Loss % s rÌ Ag:Au Lead l.treight (0r) (g"ur"f

2000 0,86 0.16 t2 6,5 15"0

1900 0 0 6 "67 " 10 L2 "4 L4.0 i.800 0"s6 0.03 10 6,3 18,7

1700 0,62 0,a9 10 6"4 15,3 -98-

researeh, A eupeLtr atÍ.@n tenperaeuae ef X800@tr produees a go3.d loss whfeh f.s slgnlf{eanËXy d$.ff,erent f'rem al.L the othen tenperatures stud{.ed

aL t?re 95% eonfldenee 1eve3. and dlffens slgnf.€{.eantX.y fron ehe h{gher

ËemperaËures at the 99% eonfldenee 3.er¡e1,

TLre above resuS.ts verlf,y ln part the genera&luatåon thaË

lr¡ereaslng Ëernperacure @f eupeX,l.atlon fnereases goLd trosses" lt Ls ín eontradfetlon Èo Èhe generalføaÈlen that the best temperaÊure of eupetrlaËion ls che losrest Èmperacure whleh prevents freeuing of, the eupeXtrlng buËtons.

6" Effect of A Cover

ï,n order Ëo tese the effeet of a c@veretÌso trlatrsu eonsfst{.ng o€ a dozen samples eaeh, çdere rung one Ërlal w{.Ehrand other røLthouÈ a eox/etr, ffi¡e eover eonsfsËed of 25 grams of exeess eharge but noÈ salted wlth goLd and sih¡er" The resu1ts are sunmarfaed ln Tab1e XXT," Sfnee the :result,s for Ëhe eupel1ation study had not been ana!.yzeðu the tem¡reraËune of eupetLati@n was &700@F, Samrple preparaËlon and røaalnfng aspeeËs srere Ehe same as usuat u wlÈh the eharge Ëhe same a6 for the tirne study. The average gold Loss wlthout a e6veË was 0.6n" s = 0"09 vøhi3,e ¡øfËh a eover fE was O"6L% s = 0"08" ISre vlrtual eofneLdenae of these resul.Ës fndfcates that a eover ís noË rnorËh the exËra bother lnvol.ved.

7 " Mlsee3.laneous Conslderatlons I{hL&e not strfet3.y re!.ated to goLd &osses ln flre assay*ng a few polnts of lnterest È@ assayÍ.ng are $rûrËhy of rnentlos¡"

â." EffeeË of, TønperaËure on Per.centage Sllven Retai.ned by Gotr d Beads

Slnee alL parËlngs $rere perfo:med on ttrìe sane sËeam bath the asswnptl@n was made ËhaÈ Ehe ËemperaËure of, the partlng aeåd(s) was essenEåal.I.y eonsËanË @r at neasc dld not lnwo!.ve sågnf.f,l.eanË warf.ael@ns, TABLE XXT

Ef feet of 25,0 g" Cor¡er on Gotr"d Losses of

Compi.eÊe Fire Assay n0 cOver

Au Added Ag Added Sum Parted Bead Ag ReÈained Au Found (*e" Au Loss Au Loss % I,Jelght ) ('e" ) ('g" ) ('e" ) l-. \ tead Button '"'b " / {*e" ) (*e" ) ( grams ) 26 802 " r.61"8 18s"3 26 815 0 17r. " " 26.6¿',4 0"L58 0"59 Ï.4"8 28,491 L97 "3 223"2 28.s37 u"t)4 28.283 0.208 0"73 r.6. B 21"19e L42"4 160"s 2!. t"BL " 0"124 23. .057 0"141 t "67 xs"3 18.806 L20 "V 15, 9 26 "L09 1 s6.6 tr 82" 0 26 0,n37 "LOL 25,964. 0, 145 0"56 ns,6

26,1 0 15 L62 "7 \o L7 \o "3 û 25,5t.1 t-62.1. 183"9 25 485 " 0. r.07 25 0,133 o "378 "52 L6 "0 23"190 L52.s L72"L 23 "LB7 0 23 ,045 0 L45 "L42 " 0"63 13. 3 25 161 L82.7 "2L9 .3 25 "2t,6 0.163 2s.083 0"136 0.54 1¿r". 5 20,950 L¿¡0,3 158"4 2D o 1n¿ 20,820 "924 0"n30 0 "62 r.).4 28 187" 1 2L2"2 28.309 ,)a "362 0 avoLJ¡ r,l" o "1_72 ^225 0 "79 15. 5 22"686 1"41.7 L62"8 22,704 0.145 22 "559 o "L27 0_"å6 1s.6

Average Au Loss % :0"62 Average Colcl Reeoveny : 99 "i8% : 0.09 T-T 25 g, cÕver

Au Added A¡¿ parted Added' Sum Bead AÊ Retained Au Found r*te.ight Au Loss Au Loss % Lead Button (.e,) {*e") (re,) (*e.) "l^r.> (*e" {mg',\ ) (grams ) T9.4s2 I27,9 L44"6 19"390 0"137 L9.2s3 o lqq t 02*' " L7 "O 19.7s6 r"36,5 153_s 19"7BB 0"140 :t 9.648 0.x08 0, s5 T.8"6 24,t2L 1"50.4 x.72"0 24"lss 0"173 )2 Ae.' 0 " 138 0"58 n7"0 25"L55 153"4 L77"!"+ 25"193 O"1BB 25.005 '¡Q 0.150 0"60 */øJ I 2¿r"107 159.2 187"5 2¿+"072 0,140 2¿ç.932 0,x75 o "73 17. s 2L L¿+7 166,3 Ztr F "9a6 "a ,953 0 " X.64 2L 0 . 1.17 'to q "789 0"53 t-t.J O 0 23.077 r&8"2 168,0 23,113 0,183 22,930 4.T47 0.64 1'Ì¿t ôTL 19,838 130,1 L46,5 r.9,837 0,146 T9,69L 0,1 47 0"74, L/"J 20 135 4 x. s3 3 2A "699 " " "728 0 . tr_3e 20.589 0"1t0 0"53 !.9.0 23 " 164 n 50 8 L70 23 c ?? qoo " "2 .L78 .L7s 0"165 n?1 20.0 20 L27 "696 ,3 145"6 2A.7s3 0 169 2A " "584 A "LTz 0"54 18"0 22"262 144,6 164.0 22"2s7 0"L64 22. Í.33 0 "rze o_"åq. 1-8.2 Average Au Lc¡ss % : 0,6tr

Average Gol"d Recovetry : gg.3g% : 0,08 ::ejeeEed on staE{.sÈíeaL grounds -tr01-

As rnore and mor"e experlmenLs lsere penformed thÍs di.d n@Ë prove Ê.6 be

the ease" Eventuanly an abrupt ehange fn Ëhe pereentage sflver reËalned

by Lhe parÈed beads ssas traeed to a redueed sceam f1ov¡ raËe tbror.lgh the

steam baLh, 0n measurlng the Ëemperature for a serfes of parË,ångs, varíaÈions as narge as 25oC were obsenred over a perlod of Ëime, Tab[e XXïT represents a sef,eetlon of three partings chosen f,rom a larger

group, fre reason for the seX.eeÈfon of Ë,hese Èr{.aXs was a e@rmron sl!.v€ir

to go1d raÈf.6 of 6.6:X..0 approxfnaËe1y constant welgbe of gotdu and a eoflmon parËing ¡rrocedureo For the nnajorlLy of the ocher partlngs

Lhe Èemperature of the partíng ac,íd was not measured" Fronr Ëhe tab!.e lE ls evldent that the percentage sf}ver retaåned

lnereases ln a pronouneed mannetr as ternperaLure deereasedn ffirus aep@rÈs l¡r Ëhe 1iÈeraËure Ëhat a speef.ff.ed pereencêge of sln.ver ls ret,alned by Èhe goLd beads atre meanlngless ¡rfthout sËatfng the parÈfng proeedune and the temp_ergÊu-rjå of the partl.ng aeld" Unfortunatetry thls effeet

?tas ¡r@Ë reeognl.zed aL the tlme srhen the sËudy of partl.ng procedures was made, Ttre redueed steam fl,or¡ rate ¡Ehfeh eould be reeognlzed audibly, oceurred beeause of a sudden dr,op fn pressure in a eentran steam heat sysËern as ôutsf.de temperatures dropped and pXaeed a greater demand on the heacfng systen, Sfoce Èhe parËfng proeedure study was begun fn

July and fl.nf.shed ln Septemnber of Lhe same yea:r varf.atlons fn sËeam floÞt

ËaËe etere n@Ê [email protected] and te$peraËure varlaÈLons were probab&y of n@ greaE effeet" ln any ease Lhe slgntfieanc eone&usl.ons relaËe Ëo the go1.d S.osses çvhfeh were floË affeeted by these Ëerrperature varlaLfons, b, Sureharge

As fndf.eated earl.ler the sureharge ls Ëhe dlfferenee becvreen Lhe weight of the parËed bead a¡rd rhe vaefghr of go1d added or raken, TÈ ls eusÈemary, espeefa!,Ly ln the assayfng of hfgh purlry gold (gold TABLE X,ÏIT Effee,c of Temperature on FercenLage Siiver

RetaÍned by Golrl Beads *LA2-

Temperatune*c Ag ReÈai.negt'r Ag:Au Au Added &) (*s. )

94,a CI"43 6"5:r.,0 ZL"6B4

94.C t"7A 6,4:t,C Z3"ZAA gt+.A 0 " 5B 6 ,7 ¡L ,A Z3.Z5q

9¿,,"C 0"49 6,7:L,C ZL"SZ|4

94,A 0"59 6"6:tr,0 26"836

e4"0 6 p._*2 é:x "o ?L_A_z Average 0 "54 6 ,6 : I ,0 ZL "3h6 s 0"10 0,1

83"0 C.Bz 6,7;L"C ZO"7gg

83,û 0"77 6,5:1"0 19"001

83"Û t"76 6"å:1,û 20.369

B3'0 0"80 6.8:1"û e5"428

B3,C 0,88 6"8:1"0 ZA"1ZB B3,Lr _t}*-qå 6"5:1,û 4S-13_6å

Average C 8L 6 ZZ"3L3 " "6:L "A s 0"04 C,z

78,0 L"aZ 6,6:1.0 ZZ,q43

7B"t 1,04 6,8;1,0 2û".650

7Lt D"92 6.Z:'t.0 Z6"5gj

78. C t 6 ,0B ,2:L "C 2S "64L 78,0 0,93 7 .A zL "i) Lg ,L6t+

78.0 s : i, ,rg .6 " "! ?0_,6_60_ Average f"g8 6 "6zL"A 22"692 s o.0B t .3 e; Parting Procedure - Ttie bead "¿sas Ëreated r¡yiLh f.û nI" portions oi

L;4 and x":1 ÏIhr-O, for l-5 rninuLes in eaeh" Tire panring acid ï¡ras poured

off and the bead irashed three tímes r.¡ith 5 mI" porcíons of hoË waier, bulll.on) to decerrnlne the surcharge experfnental!.y for each aasay by s{'mulcaneously assayr.ng several. standard sanples wfËh cheek gold. Accordfng to the l'lterature Èbe røelght of parred bead fs usua.1ty greater Èhan Èhe rrelghr of gold Èaken, rafs fnplles rhar the gain in welghr due Èo lncompl.ete parrfng r27) fs greater rhan che gold lo"s""(20 " an examfnarlon of even a fee, resu!.ts (eg. Table I) lndtcaces thac thder the condftlons of parcfng used ln thls research the nagnitude of rhe surcharge varys by as much as 0.400 mg, wfthin a stngl.e parËfng, (second page of Tabl,e r) rf this parÈl.cular parrfng fs taken as an

exe'¡ple a random sel,ectlon of any ¡hree sanpl,es would yield ¿¡n average surcharge ranglng from 0.112 ng. to 0.296 mg" If the average welght

of gold taken Ls 24 mgs. then the t¡ro results one srould obtaln usfng

Èhe extrsne values of the surcharge lndlcated above, r¿outd vary by

about 0'8%' Thfs is a eonsiderabry larger dlfference than can be tolerated Ln vlec of the reproduclbfxfËy aÈrafnable Ln ffre assayfng, Hhfle partl'cu!.ar thls exaryl.e was chosen delfberarely because of ¿he large varlatlons, Lc does sbow up Ëhê lfnfÈarlons of sl.nply applyfng the surcbarge as a correcÈion factor to obtaln the gold content. IË ls trr¡e ËhaË a closer control of condf.tlons such as teoperaËure, thickness, weighc of gold, and sllver to gold ratio reduces varfatfons of che surcharge, fr also greatly increases the tl,me requfred for analysls' lbe decetmf'naÈlon of the sfl,ver conÈent by atoanlc absotpÈiou when set uP on a routlne basfs should tn facË reduce Ëbe tlne fnvolved. lbfs was the pracËfce throughout the presenÈ research,

V' Appt fcatton and ExËensfon of opttnnn Assay Frocedures to Èflcrogr¿un Sfzed Sæples

sfnee m¿u'y econmlc ores bave gold eontents 1n the range of a¡r -L0¿q'-

ounee or tress ef goåd per t@n of ore l€ was thought des{.rab&e t@ Lest the assayíng of sam¡rtres [n vuhleh the eøneenÊratf,en of gotd qyas less than I oz./ton of ore,

ïn assayf.ng, Èhe eoneept of the assay t@n has arLsen" For

eonvenienee an assay ton ls deflned as that welght whfeh e@ntafns Ëhe

same nt¡rnber of mi3.l.lgrams as there are Ë,r@y ounees fn the avolrdupofs

ton" $lnee there axe 290&66 troy @unees ln rhe avorrdupols Èon. an assay ton ls 29"L66 gra$s, &us the number of mfl.tlgrams of gold ln

an assay ton of ore ls aLso the nr¡nber of ounees of gol.d per t@n of of,@o rn this researeh the ore was sfmulaÊed by approxfmatexy å assay

ton of s{.liea" Many gol.d ores âre ln faeË sf.lieate @res, t, Standard Gold Sarnpl,es

&e preparatå@n of, che sæp3,es was a sllght modfffeaclon of rhar used for nltr.Lf.grar:n samplesu wlËh a df.fferenee f.n Ëhe proeedure of saltlng the eharge vafËh silver and goLd" lnstead of welghfng @uË Ehe, sfl.ver and gond, sËandard solutlons of gol.d and sfåver were pre¡rared.

Approprfate dilu¿ions of these so¡.utlons yielded worklng soluÈlons from s¡hich varyfng volt¡nes of gold were ¡rl¡reÈted inË@ a hol,Low Ln Ëhe prevfously mfxed fl.ux eonsËl.tuencs" In eaeb ease 2,0 må, of the tr000

G,'p'mó silver solution was a3,so added" frre sa3.red flux was pfaeed fn a oven aÈ 65oC and a3.Lov¡"ed to dry overnlght óE aË teasc one hor¡r for every ml.ll1ter of sol.utlon added, AfËer drying Ëhe mfxËr¡re $rae mfxed for 5 rnfnuËes fn the pol.yethy1ene bags.

The mf.Ned s4rnpges were then plaeed baek la Ëheir en¡elb&es and fused at 2n00@F and eupetled at [80ooF as usual" The bead @bËaåned frorn eupel,laÈlon was welghed and then artal.yzed dfæeetty for gol.d çafÈhouc parÈlng, usfng a proeedure simfåar Êo thaË of van Lrnrr(28), To eaeh bead was added 0"5 m!., of e@neentrated nftrfe aeid ln order -105-

to I'each @ut Ëhe sflver, fre beads were heaÈed ar fnÈer?als unËf[ a1l, aeËfon stopped and then treaLed wlth sufflcfenr eoneentrared hydrochlorfc acld to nake the final soluËfon 507, by voh¡me acfd" Agaln che solurion ¡vas heaEed co dfssolve al.l the gold, Fallure ro flrsr leaeh rhe sflver wlth n1Ërlc acfd resulÈs Ín the fornatfon of a sflver chl.orfde coatlng on the bead whlch hfaders dfssolurlon, AfËer cooling and brtnglhg

the solution to 'r¡olunre ln an appropriaËe voLr:metrlco the gold contenÈ was dete¡mlned by atomlc absozptlon spectrophocornetry uslng the perkin Elner 306 mdel.

T¡m blank dete¡mf.nations ¡vere made on the flux containfng Èhe

usual an¡ormÈ of sflver, rn one case the i.itbarge used was produced

by Ànacbemla and ln the oÈher by Baker, The correspondfng blanks were

0"98 mfcrogr¿us s : 0,37 and l XZ mlerogrãns s : 0,30" Eaeh b!.ank was

detennlned on 6 repl.fcate sampi.es. fre results of chese experrments are recorded in Table xxrrr, For sanpl,es sÍzes of,49or zLsr 98 and 24,5 mlcrogr¿uus the average gold

recoverleg Ìrere L01% s =0.7r 100% s - 0.6, 101% s = lns, 101% s: log

resPectfvely' lltthfn oçerimental error these results fndlcaÈe co,mplete

tecovery. Iosses of gold are apparently Less tha¡¡ can be obsenred by atomf,c absorption ¡rfth the nr:mber of sam¡lles eaefned. lhe results

reported hera conpare favourably wiÊh Èhose reporÈed by van Loorr(Z8), The LaËter studyrinvolvl.ng a more dtfffculÈ probleco, ln rhar che gotd was detemlned fn the presence of platinun and pal.ladlum reporÈed recoverf.es ranging Erom 9fl" to L057. dependlng on Èhe amount of other noble metals, Scale expansfon tecbnlçes srere _used ln those cases wtrere the absorbance was Less tban 0"2 a¡rd lncreased to Èhfs val.ue, In chfs way the absorbance readlng could be obÈafned to tbe nearest part Ín 200" ÏABI,E XXTTT

AppÍ.icaLion of Optímurn Assay Proeedures

ro Mí.eogram sized Sarnptr"es -106-

Au Added Ag Added Sum Au Found % Recovery ¡{-gram3 #i-graüs À-grans Ä-grans

490 2000 2s55 51lx' 104,3

490 2000 2501. 498 101,6

490 2000 2539 494 100"9

490 2000 2s4I 503 L02"7

490 2000 2525 49L L00"2

490 2000 2538 49L 100"2

490 2000 2559 493 100"6

490 2000 25L7 494 100. I

490 2000 2578 496 101"2

490 2000 2522 494 100.9

490 2000 2520 49L 100.2

490 2000 2539 494 1_oo_rg Average 490 2000 2536 494 101 s 2L 4 o.7

245 2000 23LO 2L6 88" 6*

245 2000 2295 249 101 "6 245 2000 2301 244 gg "6 245 2000 2302 246 100"4

245 2000 2287 246 100"4

245 2000 2296 246 100" 4

245 2000 2288 244 99 "6 245 2000 2277 244 99 "6 245 2000 23L3 244 99 "6 245 2000 2325 244 99 "6 245 2000 2303 246 1.00.4 245 2000 23L2- ry_ 1-00. t Average 245 2000 2307 245 100 s 2 2 0"6 * rejecÈed sfnce a parÈ1cle of gold had failed to dissolve -107-

Au Added Ag Added Sum Au Found % Recovery }\.grams ¡\-grans ffBrans H- grans 9B 2000 zLO5 97 "4 99.4 98 2000 2095 97 "4 99 "4 98 2000 zLL5 100"4 LO?.4

98 2000 zLL3 98.9 100"9

98 2000 2108 100.9 103,0

98 2000 2L33 qaq 101.9

98 2000 2t45 101"4 103"5

98 2000 2L27 98 "9 100.9 9B 2AO0 2L74 gg.g 101.8

98 2000 2099 97 "9 99.9 98 2000 2L27 96 "9 98,9 98 2000 2g8g 98._9_ 100 f_ Average 98 2000 2LL9 99"1 101 s 24 2 l. .5 24,5 2000 2037 24"4 sg "6 24"5 2000 2004 24"9 101 "6 24.s 2000 2051 24"9 101.6

24"5 2000 2048 25.L 102" 5

24.5 2000 2059 24.9 101"6

24"5 2000 2047 25.2 103.3

24"5 2000 2067 24"9 101 .6

24"5 2000 2088 24.L gg.4

24"5 2000 20L2 23 "7 96.7 24"5 2000 2325* 24.9 101"6

24"5 2000 2007 24"7 100"8

24"5 2000 2065 2þ.2 ee-.2 Average 24.5 2000 2044 24.7 101 s 27 0"5 1.8 * rejected on s tatis Èfcal grounds Charge used: 15"0 g. Sio2, g5,0 g. pb0, ZL.L Na2CO3 g. , 4.5 g. CaO, 1"0 e. flour, 1,0 g" polyethylene bag -108-

GoI'd standards were aspLrated afcer every other unknosm, Drl,ft was of

ao consequgnee over such short perlods, The aspirator used &ras a corrosl'on resfstant one sLnce dtfffcul.ries had been reported(36) fa

the aspfratfon of hydrochl.orfc acl.d solutfons of gold, They found thaË gol,d reductlon occurred ln a sËee!. aspfrator,

2, Gold Ores q

rn thls sEudy Fvro gold ores îrere chosen havlng a prevlousl.y

decermfned gold content(Z4) or less than an ormce per Éoûo The saqple

preParatlon !ùas exacÈly as outllned ln Ehe prevlous secÊfon wlth trrc nodfficatÍons, Since the ore conrained rhe gold the sanples were only

salted wlch sil,ver and no sflfca was Èaken for the ore bl,ank buc raËher 15 grams of the ore iËself ç¡as taken,

Slnee the preclslon and accuracy obtafned wLEh any method depends

on tbe sanpllng procedure the procedure used fn this research Ls ouÈ-

I'fned here. fne sannple receir¡ed consisted of a prevlously crushed and s ised ore. the encfre ore passed through 100 nesh screen and 90-L0f/.

passed througb 200 nesh screen for both saryles. Approxfinacely 1-2 pounds of the ore was placed on a large cel.lophane sheet and rolled or

tunbled by llfttng alternare coners of the sheet, lte ore had been prevlousLy lnverted and shaken for about 20 mlnuËes fn its contaf.ner, After a¡rproxfmately 30 mfnuÈes Èuurbl.lng the sæple sas spread out evenly

on the cellophane ar¡d marked off lnto Ln squares, Ibe saryle ¡ras then obtalned by Èaklng a surall porÈlon on a spatula, fron each of the sguaËeso The spaËula çras exËended down to the botcon each tf¡ne, Ite

eaople was wefgbed after eacb row of squares had been sarnpl.ed, In Ëh1s rvay varf.aÈlons were kept to a ml,nlmun,

after wetgbfng the samp!,e accurately fn a polyethyx.ene bag rhe

flux eonstf.tuenÈs were added fn Èhe usual way" rn each case z mL" o€ -1 09-

Êhe scandard slnver sonuËj.@n (2 ng" siåver) was addcd and the sampLes were drfed for aË leasË uçro hours" The ahunks whfeh Èended to deve!.oB weËe broken up and, Ëhe ore, ftuxu and added slL¡¡er svere ¡nlxed fos 5 mLnuÈes,

Fuslonu eupellatlon and anal.ysf.s of the sæpXes was Èhen achfeved as fn the other mlerogram sfzed sarnptes deserfbed above. Ttre resuXts of rhls srudy are found fn Table Ð(rv" Each assay of, sfx sanrples was repeated fn dupåieate {.n order to obtain seme ldea of the reprodueåbf1,fty of the method. the gold eonteoL of the Lry@ @res examlned rsas found to be 0.313 ou,/ton s = 0.034 for ore #305 and 0"470 øa"lton s:0.0tr2 f,or ore 1i294, The re3.atlve scandard devlatfon for the tçm ores sras

LA"g% and. 2.9% respeeÈlveI.y as eompared Eo 0,8L% for a eonparab!.e e@neentratlon of a standard go!.d sæap1e. From thís ft ls evfdent that: the preeision of Èhe rnethod fs a funetåon noË onl.y of the sanrp!.1ng meËhodubuc also the nature of Lhe ore, If th@ preelsíon were affeeted by the sanpl{.ag method only then ihe tvm ores should have approxfnaÈe&y equal rel.atlve standard devfatfons. Tn faeÈ they df.ffer by al.mosÈ 300%, Slnee the particular ore samptes used had been prevíously (2tþ) anal.yøed a corn¡larison of the resul.ts wlth those obtalned hereu was posslbtr,e" lhe prevíous study invol,ved a prl.or part$.ng of rhe slLr¡er from ehe gol.d, colleetion of the gol.d on a ftluer, a*r.lng rhe ff&cer paper, dl.ssolutfon of che resldue and determínatl.on of the go!"d eon¡enÈ by Ëhe bromaurate speeÊrophocornetrlc method referred to earLfer, By vírtue of che l.arger number of, rnanfpuåatl.ons alone, fnereased devLaËløns and X.osses srere t@ be expeeted" Ttre resuXts of dupXieaËe trlats eonsf.stlng of sfx sarnples each was for ore 1t2949 Trl.al /É1 0.440 az"ltøn s = 0,014t Trtal {Í2 0"¿#9 oz,ltøn s :0.02{+ wiËh a eo¡nbfned resule of 0"455 øa,ltøn s :0,026 and for Ore #305 XbLa& lÍL 0.290 øø./ron s :0"O29g TrLaL llT TABTE XXÏV

Appï. ieatioir *f Optimun Assay Proeedures

To Gold Ones -nx.t-

Ore designation i¡JU ) !129¿"

I{íne Buf f a1"c AmberL ite

Tri.aL T LLLdL L

GoÏ.d C¡¡neentration (oz" /ton) t "297 0 ;457

Ð "289 t.462

û "6221v 0"457 0"306 4.475

Q,376 4.474

L' ¿+öJ " Average 4,325 ."*

0.038 0,01r"

Triatr I1 Tria1" IT

r,1.2 Gold ConcenËratírn 0"285 ^!'o T, J {ø2" f tæn,\ n ?qq t+øg Ð '

0, 280 0 "463

C"282 o "464

0,35? o "467 0"323 a,498

Ar¡erage 0,30? a "472

a "029 0.013

Csmbined resuLt *

Average n ?1 ? o "470 0 ,034 Ð "0i2

ea i ae í-o ¡! ôn sLatísLiea3. grounds -n11-

0'259 @z,lte¡n s : 0,025 wlËh a eomblned resuLr øE 0.274 øa,ltøn s = 0,031"

I{hfle the aeLua1 gold e@nËenL of an ore ås unknowru che app1åeaËlon @f

the proeedures deveXoped ín Ët¡fs researeh se€rrrs to ha.cre lnereased the

goLd reeovery by 3"8/" anð L¿*.X/" for Ores lÉ294 and #405 respecÈÍvely" Ilhe preeislon of the ana&ysls of ore #305 fs essenËialLy the sæe for the t'cro proeedures ç¡hl.Le rhe preefsion f,or aæ tÍzgÇ fs fnereased consíderably as evf.deneed by a standard devfatfon a [itcle !.ess than one-hal.f ËhaË of the ear3.l.er study" As evfdeneed by a !.arger standard devfatfon, the anal.ysis of ore #305 was not very saÈf.sfaeto3Jr. !ü'hile

Ëhe reeovery Bras conslderably Íncreased, Ëhe seE araËfon of che !.ead bucton and tbe sLag was noÊ elean and rhf.q no doubr, eontrf.buted to

Ëhe increase fn devl.atfons, llhe dífferenee betnreen duplleate rrla!,s was found to be 6"5% vs 0,85'¿ (rhls srudy) for ore lþzg¿ø, and r2,0% vs

7,6% (ehfs study) fer Ore /É305.

rn sunrnary åt vrould seem safe to eonelude that Èhe method of anatysls developed for mferogram sfzed sanples has a satfsfaeË@ry applleaeion to the anaXysis of gol,d bearlng ores Ln the eoncent,aaèf@n range of, an ounge per Ëon and Less,

VT. RadtochernÍcal Eval.uatl.on of Ffre Assay for Gol.d Ln General Procedure

At thls polnt Lt sras decf.ded Ëhar an aËrenpr shsuld be made ro obtain a dlreet measure of the gold nosses vrlth rhe help of a radLoaeËlve traeeËo the Ëraeer used fn Ëhís sÈudy was gold-X95 whieh has a ha1f-tff'e of 180 days, T,t was prepared by bonbardmenr of Bxarånun forl f.øæ Z hours, by 25 fit"êovø ñtroÈons ln a eyen@Ëro¡tø Ihe aetlve gold was separaced by approprfate radfoehqafeaS. proeedures and nefe unused for mor-e Èhan a year,

At the ÈÍme of, use Ëhe total sarnpS.e had an aeËivfty of appnoxlmaËe1y -1L 2-

2 rnånLlon e@unts per 50 seeond e@unËfng lnËerrya1" The tøËa3. sampte was dfluted eo 50 nrl.u afld 3 m1., atr.fquees v¡ere Laken for eaeh samp1.e and eounted ån tesË tubes whleh flc exaeË1y lnto the well of ttre Balrd sodår¡ra fodlde selntfllatíon eeunter, Ttre baekground çaas detemrlned before and after eaeh serles of measurements over n5 eounting fntenraXs, lbe aeËfviËy of a!.1 sampX.es was determlned by eountlng for 5 counËfng lnËewals?averagfng, and eorrecting for backgroundo l\ro allquots of the stock soLutf@n lrere retal.ned throughout as ea1lbratfon standards, The preparatfon of the f,lux eonsËltuents and the earrler gol,d of abouË 20 rng" was the same as usuaÍ. AfÈer thørough rnlxlng the aecfve gol.d was added Èo a holl.ow fo¡med ln the ehange wlÈh a spaËu3.a.

Xhe s*pnes vsere all,owed eo dry ovenright ar: abouÈ sOoC" The test

Êubes 1n whleh the acËtÌre gold had been eounÈed wez-e eounted agaln and found to reLaín varylng and sfgnlfieanc amounÈs of aetf.vlty" ffire aetívícy added to 'che sampne çyas deËerorined by dffferenee,

After drylng che sarn¡rl.es, they were nixed ônce more for abouË

5 rninures and any ehunks whfch fonned were erushed. the sarnples ære pt.aeed ia theLr approprlate eruelbl,es, fused ac 2L00oF and poured inËo the iron mold as usual" After eoollng the slag and button rüere p3.aeed in a polyeÈhyX.ene bag and gentl,y tapped Ë@ se¡rarate Ëhe s1,ag and bucton dresstng frorn the lead buËton. The tread butËon !ûas sreighed and cupelled as usual at 1.800@F" The slags and assoclaËed button dresslng were trabelled and kept together for counËing, The cruelbles from Ëhe fuslon æse numbered and set asl.de for eer¡ntång also"

lfhen the cupelled beads had eooX.ed eaeh eupel, sras XabeLLed and set aslde for eountlng" The gol.d-silver beads were noË v*ef.ghed but v¿ere parËed dtreecLy vrlth a doubl,e aefd treaÈment as outl.lned ln Partång

Proeedure VT," T*re parËfng acíds çere seË asf.de for counÊång, The -113-

parËed beads were ehen srashed chree tlmes wlch hßË. r.aaËer and rhe washlngs were eol.teeted for eaeh sarnpne and seË asíde for eounÊfag,

The parted beads were Ëhen anneal.ed and then dfreettry ptaeed

1nË@ Ëhe orlglnal test tubes used for eountf.ng. ln the fnEerírn the

test cubes were cleaned wlth aqua regf.a and cheeked for aeËf.vlËy" No

aeLlvlËy was reÈained" The beads were then dissolved in 3 rnlø êeuâ regia Ín the usual way and set aslde for eounËlng,

2" CounËfng Proeedure and Resul.ts

The deeay of the act{.ve goLd røas all.owed for by measurlng the aeÈlvlÈy of the standards eaeh day and in the ease of, the dlsselved beadso funnedfaËely after Ëhelr ¡ûeasurementu The cotan aeËLniLy decreased by only t/o øver Ëhe t1rne used for Èhe eomp[ece sËudy, &x addLtíon to the deeay eorree,Ëåon the presenee of 20-30 mg, earrier go1d fn the sarnpS.es neeessítated a e@rreeËf@n for sel.f-absorpÈlon" Thfs an@unted c@ ab@uL 3% øt Ëhe total e@unt as detennined €rom duptr"icate evaX.uaLfons" a). Parted Beads

Af ter dissol.utlon as oucl.fned above the beads e@nÈaining more t-h,an 99% of the goLd were eounted ln Lhe same voX.u¡qe (3 nL,) as che sËândards and f'n the same conËafners" AfËer correetf.on for decay and sel.f-absorpË1on chese measursrents should represent the gold reeovered. the average gond aeeovery (tabtre ffiV) of 99"5% s:0"3% agrees very welL

ç¡lËh that obtaf,ned by dfreet wefghlng of the beads (see Table XIX X.80OoF)" b). Crueíbles

TnltÍa1Ly the eruelbles grere counted who3.e" ffire eruefble çras

ånr¡erted @ver the counti.ng vrelL and eormËed for 5 f.nterva&s of 100 seeonds eaeh" The baekground based @n Ëhe average of 1.5 eounÈlng

ínteñtals before*and 15 i.ntes'\raLs after the eruclbl.e eounËs was [010 ï¿\BLE Xl{V

T::ace:: StuC,v of GoLd l,osses i_n The

CompLete Fire z\ssay Au Added Activity Acttvfty ln Parted Bead Activity in Crucible AcÈiviÈy in Cupel % Actlvity Recovered (*g. ) (c/50 sec. ) (c/50 sec, ) (%) (c/50 sec, ) &) (c/50 sec, ) CL)

26"247 L37,694 L37,270 99.7 870 0.63 32 0 "023 100"3 20 137,418 98.9 "sCI 135,863 758 0"55 35 0.025 99 "4 3().029 136,733 137 ,989 100. 9vc 1060 0.77 41 0,030 101.7*

28,054 L37,494 L36,874 99.6 986 0.71 53 0,038 1.00.3

23 "744 L36,L57 L36,099 100,C L074 0,78 37 0.027 100. B 23"486 L37,326 L37,032 99. I 1054 0"76 52 0.038 100" 6 F0 L9,929 136,098 1 35,968 99.9 B5B 0.63 35 0 "026 100,6 & 0 23 "L76 L37 ,922 L37,OLz 99.3 990 0.7L 43 0.031 100"L

25,083 L36,937 136,600 99. B 972 0"71 38 0.028 100. 5 1¡ì gg 24"429 L34,552 133,977 "6 966 0.72 50 0.037 1 00.3

L36,767 99 L9.286 L35,704 .2 842 0,61 39 0,028 99 "9 23.404 L37,652 136,440 gJ"f. 11 96 0. 86- 33 oro?!_ 100"0

Average % = 99"5 Average % = 0,70 Average % : 0,030 ''., s: 0.3 s : 0"09 s : 0.005 0"4 * rejected on st,atlsËical grounds

Charge used: 15.0 g" St02r 85.0 g. Pbo, 2L.L g. NarCOrr 4,5 g. Cao, 1.0'g. flour, 1,0 g, poLyethyl.ene bag -1t 5- s : 18. Tn vlær of the Large siøe of the eruefbtes uhe ni.d of the eounter eould n@Ë be nowered and henee the hlgh baekground, Thc baek- ground was detemrfned wlth a previousl.y used erue{ble whieh l¡ad e@ntafned no active gold" Ttre average eounË for all che eruefbles used wíËh aeclve goi-d ranged from 987-L045, the overall average of all. tçrelve eruclbXes sras acËuaLly lower (1006)eEhan the average baekground"

In vf.ew of the faet thaE sorne of the errrelbles had an average e@unt hlgher than baekground, lt v¡as thought Ehat perhaps the effeet of geometry night be slgnffieanË. the part of the eruelb1e wh{.eh aeeordfng to [email protected] lras the nîosË l1kei.y to be aetÍ.ve(Æ) ort che most rsa@Le from the eountfng qret3., As a resutÈ one enleibl.e was p1aeed ín a pol.yethyt ene bag and broken by hlttf.ng wtth a hard obJec,t" Lt was possfbte t@ do ehls in sueh a vray ÊhaL no pieees erere

Xarger Ëhan wouLd fic under the Xov,*ened Xid of the e@unter" Eaeh pleee sras eounËed ef ther atone or togetherr ln Ëhe ease of the sma3.X.er pleees çrfth one other plece" Ttre flnes and very sma1L påeces were eounËed Èogether, In each eese the slde of Ëhe err¡eible wb{ch had been weË by the eharge Þras ptr aced faee down above Ëhe counting taell, Tïre result rùas surprf.sing, In each case Ehe total aetivity vaas significant and averaged 0,707" s: 0"09, of the oríginal bead aetá.vlËy, T.t fs recogníøed, of eourse, Ëhat these resul,Ës eannot be taken as exaetly quanëíËatfve sf.nee a g@6meËríe effeet appXÍes" Ttre face of the countfng weX.L on whíeh the eruafbtre pleees erere eountedo were severatr eentl¡neters from the botLonn of the røel1. ç¡here the standards çsere eounted" e). 5Lag

fre slag rqnained in one large pleee exee$rt f.ør a sma3,L quaneåty of, button dresslng, The whole slag pleees ?üerê e@unËed atrong wÍth Ëhe buËton dresslng" That parË of che sLag whfeh had been in eont,aet røåth -l-l.þ-

the !.ead buËtøn was EluË faee down @n Ëhe e@unEer eregl" Ttre baekgr@und detemlned be€ore and afÈer the slag e@unte sras @bÈagned stf.th a sfmllar pfeee of slag fretrs a prevl@us non-êeÈive Ërlale and a\teragedl2S per 50 seeond eountlng lntenra!., The range of aeËlvlty f,or Che snags from the rlaetlverl run was X09-n30 eounËs for the sane tlme, w{Ëh an average aeËívlty øf. t22 e@unËs" tllËhln exgrerlmenËaX, sensftfvf ty the aetlvf ty sf rhe stag was eonsfdered to be fnsígntfíeanË' An aetlvlty of 7 eounLs per 50 second eounËing lnÈeffi/¿[ would represent 0'01% of the toÊal count for Ctre average sampl.e" As ean be seen fron Table XXV the amount @f aeLivlty added was not exaeEl.y e@nstanË from sanp}e to sanrp}e" d)" &fetal Mold

The rno!.d into çrhíeh the fused samgrles Brere poured s*ere eheeked for aet,lvfty aïso" In order to obtain a background Che mond t*as p!.aeed over Ëhe eounti.ng we3.1. with che unused slde faclng down over the we1.L. Th{s was reÍteaËed Ehree Ël.nes wlth varying posftl.ons of the nol,d, The overal.X. average stas 552 counËs Ber 50 second fnten¡al. Xhe eounÈing aras repeaËed @ver the sane lnten¡a3. wfth three dl.fferent posf.Ëlons of the Itastivelr side face doçcn, The resul.t, rüas an average ceunL of 540 eounÊs" fre standard devfaÊf.on ln both cases was 30 eounts" ït, ¡aas eoncl.uded Èhat no sfgnlff.cant aetivl.Ëy qtas trose to the mol.d" The 3.fd of the e@unter was up throughouÊ. e)" Partíng SoluLlons The parËång solutions were eounËed fn test eubes plaaed dlreetny

ln Ëhe eountfng weX3., For the ffrst parting ael.d (1:4 ¡lltrle) ttre range of aetlvíty found corrected for baekground was 4-L0 eounËs wf.eh an overanl average of 7 eounts s = 2 per 50 seeond åntemral" }-or the average sample thfs represents a Loss of 0"0X% gold, ffire seeond parËång -117-

aeldee@unted ln ttae same way./gave an aveeage eôunt of onny 2 e@unËs per 50 second *nËegrula3," &ís represented a n,oss çrhleh eould be ågnored" f )" ldashfng Sol.uËfons

The eømbLned wash s@tutlons for eaeh sample weËe e@unted i.n 30 rnn' beakers pS,aced dlrectly @ver Ehe eountlng well, Agaån the actåvf'tye cclrrecÊed f,or backgroundrwas on Ëhe average onl"y I eounË' per 50 seeond fntezrtal" Losses tcl the çsash soluËiorn were eonsfdered neglf.glbl'e" g), Cupetr.s

The eupels srere eounted whole, Aeeord{ng Eo auËoradfographsn eupel absorptlon was nafntry a surfaee effeeË wlth Lhe maxímum penetratfon noË more than abouË ätt" The eupef,s were henee lnverÈed clver Ëhe ecruntíng weT"X. and ealunLed for 5 repLleate lntemrals of 50 seeonds, Tbe range of aetlrrfËy ln Ëhis perf.od eorreeted for baekground was 32-53 wlÈh an overa!.tr- average of 4X. ecrunËs s = 7' &f's represented a g@ld loss of onl.y 0,030% s = 0.005, 3" Surmrary of Traeer Seudy A eoosideraËfon of TabLe )p(Vu whf.ch Lneludes at]. Ëhe aetivíEy nreasutremenEs for those sourees conËribuÈfiag more than 0.01.% of the total aeLf.vLty, LndleaEes that the overanl average reecrvery of the aeEive gol.d lneludfng !.osses !üas 100,t/o S = 0n4u ln viesa of the dlfferlng eounring technl.ques thLs musL be eonsidered as belngeaË least parËlally")

forËufËous " The sfgnf.ffeant eone}usl@ns are ÈhaL the maJor souree of gold loss

ís undoubeedXy nclL L@ eupeX absorpCfon but due to eruef.bS.e nosses"

T.IhÍLe these conclusions Etere not enÈirely surprfslng chey cerraf'nLy

?rere contrat'y t@ ff.ndings based on qrhat has here been deserlbed as ItsÍmulaced eupell.aËf@nstr, It røoul.d appear that the eupeltr atf.on of gold

aad s{.!ver Bonrder eneased fn lead folL cannoÈ be eornËtared Êøl Che -[18- eupellâEforn orf the nead butÈon eusûomarf3.y obtalned ai ¡he end of a fuslon" Ihe approxfnaËely equalåty of the gold 1@sses t@ earueibl.es ln the eornp!.ete assay, and the goLd Losges Ë@ eupels for ehe abbrevlaËed proeess, r*ruu&d apElear to be fortulËous and misgeadlng'

Suspielons thaË Èhe above eonelusLons might be Erue, began E@ grow tahen gold losses for the eornplete assay were redueed to che polnt rçhere they were tess Èhan had been found for a segmenÊ of rhe overal.L : proeessø In E arËLeu1.ar conBare the average go1d loss of 0" 56% s 0'03 recorded for optlmum condftLons fn the eupellaEf@n Ësn¡ierature study ") (table XIX) to a loss oE 0.6L7" s = 0"08 Ëhe average go3.d l.oss f,or the ttsl¡rulared eupellatlonlr reeorded Ln Table T" This differenee rePresenÈs a sfgnifieanË dlffêrenee aE a eonfldenee level someç*¡here betsreen 95-gY/" and etoser to the XaLËer, tosses ro parËing aelds and wash sol"uËLon were negll.bfbl.e as expeetedu since the beads renalned nleel.y eoherent under the eondftions of partlng' IË {s to be expeeted thaE losses Èo sl.ag ån parÈleul'ar and cruefble wa1l to a lesser degree would varye both wlth varlaÈfons Ín flux nlxtures and henee ln the natr¡re of an ore' In Ëhe bullc of the work reporLed on l¡ere the fl.ux eomponents were knovnr alnost exâet¡.y

(ftnpurities exeepted) and henee che Xosses reporcted on herershould be vfewed as charaeterlsÈle of the aondftlons used and as ar¡ ideal s{.tuaLlon

r¡hfeb one wpuLd aspfre Èo in the more real eendlËions of assaylng ores" -1.T.9-

E, Swirmary

Ï,n a reeenL revlew of neutron aet¿vatlon and Èra6er methods for

the decemlnaËlon of rhe nobl.e meralsoBeænísh eË ag(35) point @uE Ëhe

naek of even e slngtre adequace study of gotd losses in rhe ffre assay meËhod, 8s,""desplÈe che comnereåa!. slgnifiean€eof che method and cbe t many deeades of íts appxfeati@n,r¡ They go on t@ say Ëhac a varíeÊy

øf phenomenâ, may be lnvotved and Ëhat conslderacf.on of many faeÈors wfl 3, be required, This scudy has been an aËgernpË t@ meet chfs need" On the basls of the resul,ts of Lhls sÈudy several general.fzatlons ç¡ould appear Ëo be in order, with regards Ëo the abbrevlated fj.re assaye (sin'ruLated eupell.aÈfon) variaËlons ln the wel,ght of 3.ead foí!., ln the silver to gold rarfo, and ln rhe sise of eupeL, dld noÈ produee slgnff,leant ehanges fn rhe gold less under Ëhe eondftl.ons sËudfes"

No evldenee Eüas f,ound for si.gnlffeanE Í.osses as a eesuLÈ @f votracl.llzaËlon, fre cX.eanfng of eupelled beads by rmovlng Lhe smal!. quanËfËy of adherfng cupe1 maËerlalo inereased goLd losses and ls to be dlseouraged, ffhile reduel.ng the thfekness of rhe gol.d-sinver beads prlor to parËing reduces gold Losses the tlme fnvolved is hardly lrorth rhe efforÈ.

I,nereaslng aeid sËrengÈh atso reduces gold Losses fn Ëhe parting Eroeess, provfded eoherent beads are obËafned. T3re eonelusLons regardfng rhe el,eanlng of cupel,l.ed beads and parting proeedures should be val,ld for beads obtained from ¡he eomplete ffre assay also, Both proeesses (abbrevlated and eornpneee) produce a gold-sf[ver bead f,ree of essenËlal.Ly all Lead,

For Ëhe eoup!,ete flre assay Ëhe welghu of Xead bueton bet¡oreen the n lrnf ts of 7-34 grams had no sf.gnifleanr effeer on gold losses" Exeess eharge used as a eovea was also of no effeeË, tbe use of pol.y- ethylene bags for ni:rlng of thc f,Luxu sf.lver and gox.dron Lhe ocher hand,, -L20- gÊeatLy eedueed gold Løsses" The length øf clne used før the fusåon proeess was imporËant, sãf.th lnereased losses lf efËber t@o EhorË or too long a fuslon Ëfme was used, ftre optimm túne for this phase of

Èhe proaess wa6 found to be Lå hours. Ft¡slon and eu¡reX.X.aÈf.on tenperacure both were sígnificanr varlables, ln Èenns of cheir ef,feet on gold Losses" For fusl.on, a maxl¡nr¡m ËãnperaLure of 2500oF was lndleated as the cruelbl.es beea¡ne Elorous Lo Ëhe sXags at Ëhfs teÍ¡peraÈure, A lower nlmlt of 20000¡' ls desínabI,e and an opÈímrm Ë@r¡lerature of

2100oF fs reeomrended Ëo minfmize gol.d l@sses, The effect of varyl.ng cupetLaÊlon tsnperaËure was not nearXy as pronouneed as expeeted from some stetsrients found ln Ëhe !.l.terature. Aceordfng Hillebrand and (34) Allen'i-' gold Losses due to ínereasfng Ëemperature from front to back of a gas f,lred furnaee ranged from 0,5% Ë@ d+,0% due È@ a EemperaÈure differenee of abouË 1.00oC. Tn thls sËudy nosses ranged from 0' 56% tø

0"86% f,or tenBeraÈures bemreen 1700-2000oF, The use of radloaetíve Lraeer perrnitted the determination of gold losses direetl,y ln the varLous sËages of assyfng, Losses of abouË 0.707" to ehe erueibte walI, 0,03% to the eupeX., and 0"0X% to the partLng acfds vrere Ëhe maJor losses. tosses Èo Lhe slagu the lron nold, and the stash sol,utlons were not deEeetable, An aÈomíe absorptlon - fire assay method applfed to sËandard mlerogram sfaed sampS.es shov¡ed thaÈ losses &rere snal.ler than experlmental error" T.ItÈh1n the preeisfon of tl¡e mechod reeovery was eomplete, The sarne mechod appnled t@ tvüo dåfferent ores lndåeated a sømetøhaÈ lmÍÞr@ved method of analysis over a prevlous efforË, ltre preeisÍon r¡aried srfth the nature of the ore and was dependent on the sarnp3,fng proeedure used" Prebably the most slgníffeant flndlng ln ttre Eourse of thl,s study was the eonelusfon ËhaÈ the maJor loss of, gol.d oeeuns durlng fusfon as -Li¿L- gol,d {s retafned by the errrclble $rall. Taken together w1Èh the rrery treø eupel losses ft wuld appear thaÈ Èhe cupell.atlon of a Lead buEton as @bËal.ned frm fuslon ls not a sotrparable process Èo che cupellacton of a nf,xÈure of go!.d and sllver powders encased ln X,ead fofl.,

$lhlle varÍaÈlons, ln at least some of the condltfons enrployedo resulted f.n slgnfffcant variaefons fn gold tosseso the ovorall lmpresslon obtalned was that the fLre assay for gold fs rer"rt"bTy ínsensf.tlve to cbanges fn the condltÍons of assaying, Furthe¡more ln tbose cases where gold losses dfd varT sl.gniftcantly reproducfble assaylng was possfble even at condfElons ocher Èhan those which mlnl¡nlzed Losges, Perhaps thl.s ls one of ehe reasons why Èhe flre assay for gold Ls considered Èo be, along wlch tbe gravfmetric chlorldeu one of the rnoot rellable analyclcal rnechods knowr¡. Er¡en Ëhough gpld losses of alrnost X% nay be Lnvolved the pracÈ1se of dete¡mining these f,osses from standard samples under- the same condltlons of a¡ralysis as the unknowns makes accurate work possfble" -L22-

Bi.blåography

¡üStoqy_ L, Szabadvaryu F,, of -Anqlv-Ef,ejrtr- C_hqf-stty Pergamøn Press Nær York, (1966)

2" SniËhu E,A.e .Ttrg Sæ4!¡LlJLg an{Assav- of-&e.3re_f:ü¡gs Eet-a-l-s-" Znd Ed" Gríffin and Co. LËd, Ipndon (L947)

3, Ezeklel 229 LB-22 Kfge J_aqes- Bl-blj¡

¿+, SLavl.n, lJ., Atgqie_4bSerpt-l.og5pge_t_qgpho-tjqeËqf, TnËerselence

Publlshers Nesr Yorku (1968)

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TSre auther r¡lshes t@ e:rpress hls slneere Ëhanks Eo Professor

,{" Chor,r for hts eaeouragernenÊ, patf.ent audlenee and helpfun advlee throughouc the e@urse of chfs reseaseh, the author Ls anso lndebted to a patfenË and eneouraglng wife and fælty,