Patented May 1, 1923. 1,45%,562 UNITED SATES P All.‘ bl if" til? .

ROBERT E. WILSON, LEON ‘JV. PARSONS, AND STANLEY 1E. OHXSHOLIYI, OF WASHINGTON, DISTRICT OF COLUMBIA.

PROCESS THE PRODUCTION OE‘ All‘HALLEAETELMLETAL PERTJIANGANATES.

N0 Drawing". Application ?led September 27, 1918. Serial No. 255,975. To (all to]: am it may concern. .' manganate by oxidation or acidification, Be it known that we, Romain‘ E. lllinsou, metatheses into pern'iangamite by LEON “7. Parsons, and STANLEY L. Unis treatment With calcium sulphate or milk at HoLM, citizens of the United States. and sta lime. . tioned at ViTashington, District of Columbia, O'li' these four possible methods, (1.) is not 60 in the o?icc of the Director the Chemical a possible large scale method. on account l/Varfare Service, Research Division, have in of its use ot silver; (2) and are elec vented a Process for the ll’roduction oif Al trolytic methods Without a. great deal out kali-Earth-l\letal Permanpjanates, of which promise, and are to be considered elsewhere; ll) the ‘following is a speci?cation. (ll) the principal subject of this applica G3 in The present invention relates to the pro tion. duction oi? alkah» earth metal permangam Three distinct methods for preparing: ba~ nates and especially the of rium (or strontium) manganate have been calcium and magnesium as these have beenv here investigated. The ?rst of? these meth found to be very ellicient oxidizing agents ods involves heating together perox 70 for certain purposes, more e?icient even. than ide, hydroxide, or a salt, such as the nitrate the permanganates of the allmliearth metals. or chlorate,‘ witl an oxide of , as This superiority is shown in the so-called . Considerable iWOl'l’I has “British soda lime granules.” been done upon fusions ot this type, and More specifically, the object of‘ the inven beautiful green products were obtained, but tion. is the development of a commercial the most tavorable results obtained gave process oiliproducing the alkali-earth metal products containing only FS—lO“-"o milling,“ permanganates, since so tar as We are aware. the rest oi’ the product consistinc,r of residual their manufacture in quantity has never M1102, Ball and the Ball/int), from the been attempted on a large scale or even on thermal decomposition of the mangranate. a small. scale, except in Germany, Where The thorough n'iiningr of such dry sinteringi's they have been produced by a. rather expen is retl'icr :litlicult, but quite necessary; indeed sive electrolytic process starting with potas even the ‘fusions should be stirred to give the sium (Kb/[1104), best results. 30 lWe have discovered that calcium or map; The second and more preferable of these 00 L1 nesium pern'ianganate cannot be prepared methods involves the reaction of‘ similar mimw directly by ordinary, methods but that indi tures in a- low melt-ins; fused medium. such as rect methods must be used. e. g... by ?rst ‘fused sodium hydroxide, or sodium nitrate forming a. manganate, oxidizing; this, and at temperatures Well below a red heat. The neutralizing the perinauganic acid so termed cooled fused mass is extracted with Water. With barium, calcium or magnesium hydrox the ?ltrate containing chiefly NaOll or ide. _ - NaNUS being; evaporated to dryness, and the Vile have investigated very thoroughly the fusion medium being; returned to the proc possible methods of makingv calcium per ess. The insoluble residue cou'.. s ot a 40 mangana-te and believe that only tour of basic barium manganiunanganate contaiuiiuy 9 5 them are at all workable. These are: 20-32% Bail’lnfh, together with excess i (1) Preparation of silver permansenate MnO.,. etc.‘ This represents a decided grain by crystallization from slowly cooled solu over the first, or dry ‘Fusions. tions of silver nitrate and potassium or so llloth o‘l? these methods7 however, in many dium permanganate. Calcium permanga ways appear less attractive than a. third nate is then forn'ied metatheticallyI by treat method, which consists in boiling _“green ment with . leachings” containing about 8% (2) Selective transference and oxidation 4 tint)‘ and ‘lb-420% NaO'H, With a sol electrolysis of sodium or potassium manga uble barium compound, such as the hydrox note or permanganate and milk of lime or a ide or chloride,?ltering oil and washing the Illij calcium. salt. I insoluble barium manganate precipitate and (3) Electrolysis of term manganese anode evaporating down the ?ltrate to return‘the into solution of a calcium salt. caustic to the process in the “green ash” ‘(4) Preparation of barium manganate by (manganate) fusion. Barium manganate fusion or wet‘methods, conversion to per— precipitates obtained on a small scale in In; 1,453,562

this wet way contained 70—75% Ba-MnO“ most practicable for technical use. Bro the remainder appearing to consist of ab mine is barred. because of its scarcity and sorbed alkali and alkaline salts and barium cost. The use of ozone is entirely too ex carbonate, unless the green liquor has been pensive. ,l?ven electrolytic oxidation meth previously boiled with milk of lime to re ods, relatively much more e?icient than the move the carbonate almost invariably pres ozonizing methods, involve much expensive ent. Even in this case the precipitate gen apparatus. erally contains some carbonate due to ab Chlorination is undoubtedly the best and sorption of atmospheric carbon dioxide dur most economical )rocess of converting ing manipulation of the alkaline barium BaMnO, into Ba(l\ln()4)2 for any purpose 75 mixtures. The use of the barium hydroxide where the large amount of chloride im would probably be preferable to that of a purities could be tolerated. The nitric acid salt such as the chloride as no impurities are process is undoubtedly the next best, and thus introduced into the caustic ?ltrate, to it appears from the data now available that 15 prevent its reuse in the‘ green' ash fusion. by careful removal of the nitrate formed The preliminary removal of carbonate with by crystallization, a product pure enough Ca(OH)2 is preferable to using Ba(OH)2 for certain more special uses may be made. for this purpose. , If still greater purity is required recourse Such mixtures during treatment, should must be had to the carbonation or sulpha not be allowed to evaporate‘ too far, as’ tion methods. Each has some advantages. oxygen is then evolved, with the formation but both have serious disadvantages for of a basic manganrm’anganate similar to practical commercial operation. ‘The ?nal the product mentioned above in connection choice between the two would probably de with the caustic fusions. Thus by evaporat pend on local plant conditions. The 25 ing to pasty-dryness, and thoroughly ex Ca(i\’lnO,,)2 is'made by either of two ways, 90 tracting with water, a dark blue green depending on the process used in oxidizing residue is obtained, in place of ‘the “smalt the BaMnOr If Ba (MnO,)2 is made, the blau’7 manganate, which contains only about calcium salt is made by metathesis with 40% Ba'MnO4. CaS(),, ?ltering off the B2180‘. Owing to To summarize, probably the best method the much greater stability of Ba(MnO,)., as of making BaMnO, is by a preliminary compared with Ca(l\ln(),,)2 all possible puri fusion of NaOH and MnOg, which is ?cation. ?ltration and concentration should bleached, filtered and treated first with be done before the ?nal conversion to Ca(OH)2 to precipitate CaCOm and then Ca(.\1tn(),)2 is made. with. Ba(OH)2 to precipitate BaMnOp \Vhen a solutionv or a suspension of a This gives a. very high purity B'aMnO4 with manganate is acidi?ed, manganic acid. be a minimum amount of BaO used. Consid ing very unstable, breaks down into the rela ering the great saving‘ in the later conver tively much more stable sion of this material to permanganate this and manganese dioxide. Pcrmanganic acid. 40 method is undoubtedly the cheapest. while relatively much more stable than lllii Barium manganate is an intermediate mauganic acid, is, however. quite unstable product in the manufacture of barium, cal‘— except at low concentrations and low tem ciun'i and magnesium permanganates. Ba peratures. Any plan of acid treatment in rium manganate, as prepared by either fu volved in permanganate manufacture must sion or precipitation methods may be con take into account this instability. The ac~ llo verted into barium permanganate either by tion of light is similar but much less ap direct oxidation, as by the use of chlorine preciable than that of heat. or ozone, or by the action of acids, the lib— The action of carbon dioxide, or of nitric erated manganic acid acting‘ as its own ox and sulphuric acid respectively, may be re 50 idizing agent, being itself partially reduced garded as that of typical acids as regards the to manganese dioxide in consequence. The reaction and the products obtained. (‘arbon calcium permanganate may be obtained by dioxide is of course a gas with very slight metathesis with the somewhat soluble cal in water, giving an acid solution cium sulphate, or’ by'n‘eutralizing the acid of exceedingly low hydrogen ion concentra solution‘ of permanganate with milk of tion. and in consequencedrives the reaction lime; . . ., to completion, mainly by removing’ insolu Of these" two, methods, direct oxidation, ble equilibrium products. on the one hand, and ‘indirect oxidation, by acids on“ the other harid,_the former appears 60 tov be at. first sightrpreferable, because of its directness and because none of the product This reaction is complete and irreversible isjused up in the process. Of the available on account of the insolubility of the products oxidizing agents to oxidize directly man‘ formed, but, asmightbe expected ‘from the ganate .to permanganate including chlorine, slight solubility of both of the reactingvsub bromine, and ozone, the first of‘these is the stances, carbon dioxide and barium mangan inseam 8 ate, the solubility of the latter being com ditional soluble product, this latter involving parable to that of barium sulphate the rate an impurity in the final product obtained. of reaction is practically negligible at ordi Upon the other hand the reaction proceeds nary temperatures and very slow even at the so rapidly in the cold that decomposition is boiling temperature. The great advantage reduced to a minimum. As with sulphuric of carbonation for converting barium man acid, however, at least some excess of nitric ganate lies in the very pure product‘ to be acid is required in order to work with the obtained by this method. ‘ requisite rapidity due in this case to the fact ‘By using sulphuric acid in place or carbon that the reaction products are not as insolu 10 dioxide a soluble reacting); substance is sub ble ti S before, and there is apparently a stituted. for a very slightly soluble one and measurable equilibrium set up before the re - thus the rate of reaction is greatly increased action is complete. at the corresponding temperatures. Two of the reaction products are as before insoluble. 3Ba.l\([1'1()4+6HNO3: The use of this acid however, produces such. Ql-ll‘s’ln(_i4~[—Mi1U2+3Ba(N03)2+2H2U. a high hydrogen ion concentration that it is The nitric acid has absolutely no direct ox no longer-‘possible to work above ordinary idizing action in this process, its action is or room temperatures on account of the spon solely that of an acid. taneous decomposition of permanganic acid. It barium hydroxide is used to neutralize 20 This decomposition is appreciable even. ‘at the permanganic acid and ‘any excess nitric _ ' low temperatures. acid, the resulting solution contain barium This reaction is apparently also retarded nitrate and permanganate. 13y evaporation by the insoluble product barium sulphate it is possible to concentrate the relatively which seems to have a mechanical retarding more stable barium. permanganate and sepa— effect upon the yet undissolved manganate, rate the less soluble ba rium nitrate. If cal~ 90 apparently by the formation oiI an insoluble cium hydroxide is used for this neutraliza coating ‘upon the particles. This increases tion and the clear ?ltrate concentrated by the amount of decon'iposition by increasing evaporation, the least soluble salt barium the length‘ of: treatment required for com nitrate ?rst tends to separate out, followed plete conversion and requires the use of ex by calcium nitrate until when concentrated cess H2804. to about a 20% Ca(li’ln0.,,)._, only about 5% In. the. CO2 process the reaction can be .la(NQ,)2 remains in solution and a much stopped when Ba(l\/In()4)2 is obtained ac smaller proportion of Ba(NO,,,)2. cording to the equation: ' As an example of our process the itol~ lowing experiment was carried out. 22 liters 100 oiE green liquor made by an ordinary antic-traits“.(and)annoy h'aOlP-L-hilnOr tusion containing oi’ Theoretically, it would appear that the same sodium manganate and 524L375 of caustic a1» result would follow by using H2804 accord lrali, part of which was in. the term of can ing to the equation bonate, was boiled for 5 hours with at kilo T105 grams of 90% hydrated lime to remove the carbonate. The sludge was removed by dc» QBaSU, i-si (M110 , ) ,rMHoZpii-Li i. cantation and ?ltration. and 12 liters of and actually this must be passed thru as an the ?ltrate containingr 3.41% of sodium mans intermediate stage? but in order to obtain. ganate. was boiled with 1 kilogram. of hy» 110 complete conversion oi3 the manganate enough drated barium hydroxide for one hour. The acid must be added to carry the reaction still solution gradually became purplish but the further to the ‘following stage green color of inanfranate still persisted and. successive treatments with two portions of 1100 grams each of barium hydroxide for 115 By adding Ca(OH)2 to this reaction mix one hour each followed. The solution was ture, calcium perm aupganate is obtained. This cooled and ?ltered. The dried precipitate is essentially the equivalent of adding): Cat“), was a purplish blue color and contained in the alternative method, except that the about 1 kilogram of 74% barium manganate. process is carried out in two stages, '1. e, ?rst Fifty grams of? the 74% barium manganate 120 the steps oi? precipitating the 1321804 by the was suspended in one haltz liter of water and H280, and then the neutralization of the was treated with four successive portions oi‘ HMnO,1 by means of Caitlin? it milk diluted nitric acid ('1 to 10) each portion of lime is employed for the neutralization. being slightly in excess oi’ that theoretically 60 the ‘resulting ?ltered solution or”: calcium required to produce complete conversion. permanganate is of course contaminated The reacting mass was kept cool at all times. with calcium sulphate. The ?nal residue was entirely converted In. the case of nitric acid there is again one without requiring the boiling with sodium soluble reacting substance. in this resembling carbonate which it was necessary to employ the action oi? sulphuric acid, but with an ad to complete the conversion when carbonic 41 1,453,562

or sulphuricacids‘ were used. The mass was manganatc by treatingr the solution with a ?ltcredzand washed, and the. ?ltrate neu' calcium compound. tralizcd. and concentrated to 20%- barium 7. In a‘process of making ixarmanganatcs. permanganate, . the crystals of. nitrate. being addingnitric acid to barium manganate and removed after. cooling. Calcium sulphate then forming calcium permanganate by was added-to precipitate barium sulphate. treating the solution with a- calcium com 50 The yield. ofv calciumtpermanganatei was pound. 91.8% otthetheoretic'al. The total time of S. In a process of making permanganates, treatment was four hours. adding nitric acid to barium manganate, 10 It is'to be undcrstoodthatby the term then forming calcium permanganate by “alkali earth. metal,77 ~~wev include calcium, treating the solution with a calcium com barium, strontium and n'iaggiesium. pound andmaintaining the solution cool at Having thus described ouriiwention and all times. illustrated its operation'fby a speci?c exam 9. In the process for the roduction of . ple, ‘we claim : permanganatesthe steps which consist in 1. In aprocess of makingzpermanganates, formingpermanganic acid and treating the adding. to. ‘barium mauganate a reagent. same with an a1kali¢earth metal compound which’ reacts therewith to produce perm an to produce an alkali-earth metal permangan ganate radical and treating the same with a ate. compoundot an alkali-earth metal and form 10. In the process for the production of ‘ ing the correspondingpermanganate. pcrmanganates the steps which consist in 65 2.. In a.v process of making permanganates, formingperman anic acid and-treating the addingto. an alkali-earth metal .manganate a same with an al ali-earth metal hydroxide. reagent. which . reacts . therewith to ‘ produce 11. In the process for the production of 25 permanganate radical and treating the same permanganates the‘steps which consist in with a compoundof- an alkali>earth metal. formingpermanganic acid and treating the 70 3. Inaiprocess of makingpermanganates, same with. calcium . hydroxide. adding'toan allaali-earthmetal manganate a 12. The process for the production of per reagent which. reacts therewith to produce manganates which consists in forming permanganate. radical and treating the same barium manganate. oxidizing part of the with acalcium compound. same to produce permanganate radical and 4. In a process ofmaking permanganates, treating, the same with a compound of an adding to an alkali-earth metaliinanganatea alkali-earth metal and forming the corre reagent which reacts therewith to produce sponding permanganate. permanganate radical and treating same 13. The process for the production of per‘ ' with . manganates which consists in forming an 80 5. -In a process of-making pcrmanganates, alkali-earth metal manganate, oxidizing”r part addingan oxidizing acidto an alkali-earth of the same to produce permanganate radical metal man'ganate and-then. treating the solu-. and heating the same with a compound of tioni with; a compound! of an alkali-earth an alkali-earth metal. metal. > -. ‘6. In a process, of.- making permanganates, ROBERT E. \VILSON'. adding. nitric acid to antalkalieearthvmetal LEON I". PARSONS. manganateand. then formingcalcium per~