The Effect of Lignosulfonates on the
Floatability of Molybdenite and Chalcopyrite
By
Anita Ansari
B. A. Sc., University of British Columbia, 2003
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF APPLIED SCIENCE
In
THE FACULTY OF GRADUATE STUDIES
(MINING ENGINEERING)
THE UNIVERSITY OF BRITISH COLUMBIA
April 2006
© Anita Ansari, 2006 Abstract
The applicability of six lignosulfonates as selective depressants in chalcopyrite- molybdenite separation was assessed by means of modified Hallimond tube flotation tests, supplemented by adsorption studies to determine the magnitude of lignosulfonate- mineral interactions. Flotation and adsorption tests were performed as a function of pH using different pH modifiers, i.e. lime, potassium hydroxide (KOH) and soda ash. Size exclusion chromatograms (SEC) were generated to determine which molecular weight fractions of the lignosulfonates were actually adsorbing onto the surfaces of the minerals.
The depression of chalcopyrite flotation by lignosulfonates was found to be related to the presence of physically adsorbed xanthate and the availability of metallic sites on the mineral surface. Once the physically adsorbed xanthate was removed from the surface, the depression of the mineral was possible only when lignosulfonates adsorbed onto the mineral. The adsorption process was enhanced by the presence of positively charged metallic sites on the mineral surface. The activating role of calcium ions introduced by lime for lignosulfonate adsorption was demonstrated.
The depression of molybdenite flotation was a function of pH. Good flotation of molybdenite was observed only under neutral / weakly acidic pH values, and the addition of all lignosulfonates resulted in the complete depression of molybdenite flotation. As in the case of chalcopyrite, pH adjustments using KOH and soda ash decreased the adsorption of lignosulfonates, which strongly suggests that the lignosulfonate adsorption process was controlled by electrostatic repulsion between the anionic polyelectrolytes and the negatively charged mineral surface. When lime was used as a pH modifier, the adsorption density dramatically increased due to the presence of calcium species in solution.
The SEC data indicated that higher molecular weight fractions of lignosulfonates preferentially interact with mineral surfaces.
Overall, the results suggest that it is possible to selectively float chalcopyrite from molybdenite by depressing molybdenite. This can be achieved over a wide pH range provided that a pH modifier other than lime is used for pH control. It is suggested that this process option be used in a cleaner flotation stage where pulp dilution and the use of flotation columns could greatly enhance the selectivity of the process.
ii Table of Contents
Abstract ii Table of Contents : iii List of Tables ; v List of Figures vi Acknowledgements xi Research Objectives xii 1.0 Introduction - 1 - 2.0 Literature Review ; - 2 - 2.1 Copper .' -2- 2.2 Molybdenum - 2 - 2.3 Chalcopyrite - molybdenite separation - 4 - 2.4 Xanfhates : - 6 - 2.5 Lignosulfonates - 9 - 2.6 Lignosulfonate uses - 10 - 3.0 Experimental Procedure - 16 - 3.1 Materials - 16 - 3.1.1 Equipment.. - 16 - 3.1.2 Minerals...... - 16- 3.1.3 Reagents - 18 - 3.2 Methods - 21 - 3.2.1 Hallimond Tube Flotation - 21 - 3.2.1.1 Chalcopyrite Flotation Tests - 21 - 3.2.1.2 Molybdenite Flotation Tests - 24 - 3.2.2 Adsorption Tests - 26 - 3.2.2.1 Calibration Curves and Adsorption Matrices - 26 - 3.2.2.2 Chalcopyrite Adsorption Tests - 30 - 3.2.2.3 Molybdenite Adsorption Tests - 32 - 3.2.3 Size Exclusion Chromatography tests - 33 - 3.2.3.1 HPLC Apparatus and Reagents - 34 - 3.2.3.2 HPLC Procedure - 34 - 4.0 Results and Discussion - 35 - 4.1 Flotation Tests.. - 35 - 4.1.1 Depression of Chalcopyrite - 35 - 4.1.2 Depression of Molybdenite ; - 38 - 4.2 Adsorption Tests - 44 - 4.2.1 Adsorption on Chalcopyrite - 44 - 4.2.2 Adsorption on Molybdenite - 50 - 4.3 Size Exclusion Chromatography - 55 - 4.3.1. Chalcopyrite Size Exclusion Chromatography Tests :.- 55 - 5.0 Conclusions and Recommendations : - 58 - 6.0 References - 62 - Appendix I: Size Distribution Data - 66 - Appendix II: Absorbance Scans and Calibration Curves - 67 - Appendix III: Size Exclusion Chromatography Plots , - 74 -
iii Appendix IV: Xanthate Concentrations from Chalcopyrite Adsorption Tests -114 Appendix V: Electro-acoustic Measurements on Chalcopyrite 117
iv List of Tables
Table 3-1: Summary of mineral purity -18 Table 3-2: Select properties of lignosulfonate reagents being investigated - 19 Table 3-3: Xanthate and lignosulfonate concentrations obtained for the model mixtures - 30 Table IV-1: Summary of xanthate and lignosulfonate concentrations in equilibrium with chalcopyrite - 114
v List of Figures
Figure 2-1: Contact angle diagram -4 Figure 3-1: Illustration of modified Hallimond tube flotation test -23 Figure 3-2: Absorbance spectra of potassium ethyl xanthate, at a concentration of 25 mg/L - 27 Figure 3-3: Absorbance spectra of lignosulfonate D-912, at a concentration of 50 mg/L - 28 Figure 4-1: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-619 - 35 Figure 4-2: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-648 - 35 Figure 4-3: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-659 - 36 Figure 4-4: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-748 - 36 Figure 4-5: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-750 , - 37 Figure 4-6: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-912 - 37 Figure 4-7: Flotation results of molybdenite in 0.001 M KNO3 - 39 Figure 4-8: Flotation results of molybdenite in 0.001 M KNO3, using the lignosulfonate D-619 - 40 Figure 4-9: Flotation results of molybdenite in 0.001 M KNO3, using the lignosulfonate D-648 - 40 Figure 4-10: Flotation results of molybdenite in 0.001 M KNO3, using the lignosulfonate D-701 -41 Figure 4-11: Flotation results of molybdenite in 0.001 M KNO3, using the lignosulfonate D-748 -41 Figure 4-12: Flotation results of molybdenite in 0.001 M KNO3, using the lignosulfonate D-750 -42 Figure 4-13: Flotation results of molybdenite in 0.001 M KNO3, using the lignosulfonate D-912 - 42 Figure 4-14: Dodecane and lignosulfonate flotation tests, carried out in 0.001 M KNO3 - 43 Figure 4-15: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-619 - 44 Figure 4-16: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-648 -45 Figure 4-17: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-701 -45 Figure 4-18: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-748 - 46 Figure 4-19: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-750 '. - 46
vi Figure 4-20: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-912 - 47 Figure 4-21: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-619 -50 Figure 4-22: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-648 - 50 Figure 4-23: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-701 -51 Figure 4-24: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-748 - 51 Figure 4-25: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-750 - 52 Figure 4-26: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-912 - 52 Figure 1-1: Size distribution for adsorption grade chalcopyrite - 66 Figure 1-2: Size distribution for adsorption grade molybdenite - 66 Figure II-1: Absorbance spectra of lignosulfonate D-619, at a concentration of 50 mg/L - 67 Figure II-2: Absorbance spectra of lignosulfonate D-648, at a concentration of 50 mg/L - 68 Figure II-3: Absorbance spectra of lignosulfonate D-701, at a concentration of 50 mg/L - 68 Figure II-4: Absorbance spectra of lignosulfonate D-748, at a concentration of 50 mg/L - 69 Figure II-5: Absorbance spectra of lignosulfonate D-750, at a concentration of 50 mg/L - 69 Figure II-6: Calibration curve for D-619 - 70 Figure II-7: Calibration curve for D-648 - 70 Figure II-8: Calibration curve for D-701 - 71 Figure II-9: Calibration curve for D-748 -71 Figure 11-10: Calibration curve for D-750 - 72 Figure 11-11: Calibration curve for D-912 - 72 Figure II-12: Calibration curves for potassium ethyl xanthate -73 Figure III-1: D-619 standard elution - 74 Figure III-2: D-619, after adsorption on chalcopyrite at a natural pH of 5.3 - 75 Figure III-3: D-619, after adsorption on chalcopyrite at pH 10.9 using CaO - 75 Figure III-4: D-619, after adsorption on chalcopyrite at pH 11.0 using KOH -76 Figure III-5: D-619 after adsorption on chalcopyrite, at pH 11.1 using soda ash - 76 Figure III-6: D-648 standard elution - 77 Figure III-7: D-648, after adsorption on chalcopyrite at a natural pH of 6.5 - 77 Figure III-8: D-648, after adsorption on chalcopyrite at pH 11.0 using CaO - 78 Figure IH-9: D-648 after adsorption on chalcopyrite at pH 11.0 using KOH -78 Figure 111-10: D-648, after adsorption on chalcopyrite at pH 11.1 using soda ash - 79 Figure III-11: D-701 standard elution - 79 Figure 111-12: D-701 after adsorption on chalcopyrite at a natural pH of 5.5 - 80 Figure III-13: D-701, after adsorption on chalcopyrite at pH 11.0 using CaO - 80
vii Figure III-14: D-701, after adsorption on chalcopyrite at pH 11.1 using KOH -81 Figure III-15: D-701, after adsorption on chalcopyrite at pH 11.1 using soda ash -81 Figure III-16: D-748 standard elution - 82 Figure 111-17: D-748, after adsorption on chalcopyrite at a natural pH of 5.1 - 82 Figure III-18: D-748, after adsorption on chalcopyrite at pH 11.1 using CaO - 83 Figure III-19: D-748, after adsorption on chalcopyrite at pH 11.1 using KOH - 83 Figure 111-20: D-748, after adsorption on chalcopyrite at pH 11.0 using soda ash -84
Figure 111-21: D-750 standard elution ; ..- 84 Figure 111-22: D-750 after adsorption on chalcopyrite at a natural pH of 5.2 - 85 Figure 111-23: D-750, after adsorption on chalcopyrite at pH 11.1 using CaO - 85 Figure III-24: D-750, after adsorption on chalcopyrite at pH 11.1 using KOH -86 Figure 111-25: D-748 after adsorption on chalcopyrite at pH 11.1 using soda ash - 86 Figure 111-26: D-912, standard elution - 87 Figure 111-27: D-912, after adsorption on chalcopyrite at a natural pH of 5.1 -87 Figure 111-28: D-912 after adsorption on chalcopyrite at pH 11.1 using CaO - 88 Figure 111-29: D-912 after adsorption on chalcopyrite at pH 11.1 using KOH - 88 Figure 111-30: D-912 after adsorption on chalcopyrite at pH 11.1 using soda ash - 89 Figure 111-31: D-619 after adsorption on molybdenite at a natural pH of 4.2 - 90 Figure 111-32: D-619 after adsorption on molybdenite at a natural pH of 4.4 - 90 Figure 111-33: D-619 after adsorption on molybdenite at a natural pH of 4.4 .- 91 Figure 111-34: D-619 after adsorption on molybdenite at a pH of 11.4 in the presence of lime -91 Figure IH-35: D-619 after adsorption on molybdenite at a pH of 11.3 in the presence of lime -92 Figure 111-36: D-619 after adsorption on molybdenite at a pH of 11.2 in the presence of lime -92 Figure 111-37: D-619 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH - 93 Figure 111-38: D-619 after adsorption on molybdenite at a pH of 11.4 in the presence of soda ash -93 Figure 111-39: D-648 after adsorption on molybdenite at a natural pH of 4.4 - 94 Figure 111-40: D-648 after adsorption on molybdenite at a natural pH of 4.4 -94 Figure 111-41: D-648 after adsorption on molybdenite at a natural pH of 4.5 -95 Figure 111-42: D-648 after adsorption on molybdenite at a pH of 11.3 in the presence of lime -95 Figure 111-43: D-648 after adsorption on molybdenite at a pH of 11.3 in the presence of lime -96 Figure 111-44: D-648 after adsorption on molybdenite at a pH of 11.2 in the presence of lime -96 Figure 111-45: D-648 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH - 97 Figure 111-46: D-648 after adsorption on molybdenite at a pH of 11.2 in the presence of soda ash - 97 Figure 111-47: D-701 after adsorption on molybdenite at a natural pH of 4.4 -98 Figure 111-48: D-701 after adsorption on molybdenite at a natural pH of 4.4 -98 Figure 111-49: D-701 after adsorption on molybdenite at a natural pH of 4.5 -99
viii Figure 111-50: D-701 after adsorption on molybdenite at a pH of 11.2 in the presence of lime - 99 Figure 111-51: D-701 after adsorption on molybdenite at a pH of 11.1 in the presence of lime ..- 100 Figure 111-52: D-701 after adsorption on molybdenite at a pH of 11.1 in the presence of lime -100 Figure 111-53: D-701 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH - 101 Figure 111-54: D-701 after adsorption on molybdenite at a pH of 11.2 in the presence of soda ash - 101 Figure HI-55: D-748 after adsorption on molybdenite at a natural pH of 4.3 - 102 Figure 111-56: D-748 after adsorption on molybdenite at a natural pH of 4.3 - 102 Figure 111-57: D-748 after adsorption on molybdenite at a natural pH of 4.3 - 103 Figure 111-58: D-748 after adsorption on molybdenite at a pH of 11.1 in the presence of lime - 103 Figure 111-59: D-748 after adsorption on molybdenite at a pH of 11.1 in the presence of lime - 104 Figure 111-60: D-748 after adsorption on molybdenite at a pH of 11.0 in the presence of lime -104 Figure 111-61: D-748 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH - 105 Figure 111-62: D-748 after adsorption on molybdenite at a pH of 11.3 in the presence of soda ash - 105 Figure 111-63: D-750 after adsorption on molybdenite at a natural pH of 4.3 - 106 Figure 111-64: D-750 after adsorption on molybdenite at a natural pH of 4.4 - 106 Figure 111-65: D-750 after adsorption on molybdenite at a natural pH of 4.6 - 107 Figure 111-66: D-750 after adsorption on molybdenite at a pH of 11.2 in the presence of lime - 107 Figure 111-67: D-750 after adsorption on molybdenite at a pH of 11.2 in the presence of lime - 108 Figure 111-68: D-750 after adsorption on molybdenite at a pH of 11.1 in the presence of lime :.... - 108 Figure 111-69: D-750 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH - 109 Figure 111-70: D-750 after adsorption on molybdenite at a pH of 11.2 in the presence of soda ash - 109 Figure 111-71: D-912 after adsorption on molybdenite at a natural pH of 4.4 - 110 Figure 111-72: D-912 after adsorption on molybdenite at a natural pH of 4.4 - 110 Figure 111-73: D-912 after adsorption on molybdenite at a natural pH of 4.5 - 111 Figure 111-74: D-912 after adsorption on molybdenite at a pH of 11.3 in the presence of lime -Ill Figure 111-75: D-912 after adsorption on molybdenite at a pH of 11.2 in the presence of lime -112 Figure IH-76: D-912 after adsorption on molybdenite at a pH of 11.1 in the presence of lime -112
ix Figure 111-77: D-912 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH - 113 Figure 111-78: D-912 after adsorption on molybdenite at a pH of 11.2in the presence of soda ash - 113 Figure V-l: Electroacoustic measurement of chalcopyrite, using KOH and CaO - 117
x Acknowledgements
I gratefully acknowledge the support of LignoTech USA, through a grant-in-aid of research. Special thanks are extended towards Dr. Jerry Gargulak for his valuable comments on the chemistry of lignosulfonates, as well his assistance in interpreting the SEC data. I sincerely appreciate Xiadong 'Mark' Ma's assistance and comments regarding sample preparation/characterization, BET testing, and particle size analyses. Thanks are also offered to Kuljit Basi for his help with electroacoustic testing. I am indebted to Sally Finora, for her kind words of encouragement and the inspiration she has provided over the course of this research. I thank my parents for their unwavering support and faith towards this academic endeavour. Many thanks go to my brother Sheraz for moral support as well as comic relief, as required. I am very lucky that my fiance Brennan Anstey has been so helpful and understanding over the course of this research; I owe him many meals and many critical discussions that kept me motivated. Finally, I would like to express my gratitude to Dr. Marek Pawlik, for his untiring enthusiasm, critical input, and guidance. This thesis would not have been possible without his help.
xi Research Objectives
1. To demonstrate the applicability of lignosulfonates for the selective separation of chalcopyrite from molybdenite by froth flotation.
2. To identify the physico-chemical conditions for the optimum selective separation. 3. To elucidate the mode of action of lignosulfonates in the adsorption process and subsequent depression of the minerals. 4. To propose potential processing options for the selective flotation process.
xii 1.0 Introduction
The selective separation of sulfide minerals by froth flotation frequently relies on the use of various chemical additives that affect the floatability of individual ore components. In certain cases, e.g. copper-molybdenum separation, the use of sodium hydro-sulfide (NaHS), Noke's reagent (thiophosphorus or fhioarsenic compounds), or even cyanides, is widely practised for the selective depression of chalcopyrite. Needless to say, there are environmental and safety needs to replace these highly toxic reagents with more environmentally friendly chemicals.
Although used in a number of mineral processing applications, lignosulfonates have never been tested as selective depressants in sulfide flotation. If effective, they would provide a cheap and safe alternative to the currently employed reagents.
Since there is very little fundamental information on the adsorption and flotation characteristics of lignosulfonates, the main goal of this thesis is to establish basic relationships between these interfacial phenomena. 2.0 Literature Review
2.1 Copper
The first metals found by Neolithic man were gold and copper (Aitchison, 1960;
Tylecote, 1976). Today, as the most frequently used heavy nonferrous metal, the practicality of pure copper is based upon its physical and chemical properties, especially electrical and thermal conductivity, ductility, workability and corrosion resistance
(Lossin, 2001). Common copper alloys, such as brass and bronze, are also of great practical importance in modern society (Lossin, 2001).
About 80% of primary copper production comes from low-grade or poor sulfide ores (Lossin, 2001), such as chalcopyrite (CuFeS2), chalcocite (CU2S), bournonite
(CuPbSbSa) and bornite (CusFeS^. Copper deposits consist mainly of chalcopyrite and pyrite (FeSi), with small amounts of molybdenite (M0S2) (Bassarear et al., 1985).
2.2 Molybdenum
Molybdenum is mainly used as an alloying element in cast iron, steel and super alloys; it is known to increase strength, toughness and corrosion resistance. It has many other uses, mostly high-temperature applications, as it has a higher failure tolerance and ductility as compared to ceramics, and is less expensive than tantalum and niobium, other high-melting metals (Sebenik et. al, 2000).
Molybdenum occurs in nature as the mineral molybdenite, M0S2. It was originally discovered in 1778, but remained merely a laboratory curiosity until World War I, when molybdenum additions to alloys produced steels with outstanding toughness and strength at high temperatures, used for tank armour and aircraft engines (Sebenik et al., 2000). Molybdenite possesses a layered microscopic structure. Each molybdenum atom is surrounded by six sulfur atoms, at the apices of a triangular prism (Chander and
Fuerstenau, 1972). These prisms share vertical edges, to form an S-Mo-S layer. The molybdenite crystal is built up by the repetition of complete layers above one another, in a hexagonal close packing configuration (Wyckoff, cited in Chander and Fuerstenau,
1972). The sulfur and molybdenum atoms within these layers are held together with strong covalent bonds. Conversely, the successive layers of sulfur atoms are held together by weak van der Waals bonds (Leja, 1982). These bonds form the basis of the surface properties of the mineral. The sheet edges, formed by the breaking of the covalent bonds between the sulfur and molybdenum atoms, are ionized and thus hydrophilic in nature.
The sulfur-sulfur bonds, being considerably weaker, provide excellent cleavage characteristics parallel to the sulfur sheets; the surfaces of the sheets are thus hydrophobic
(Leja, 1982). Molybdenite is the most important naturally hydrophobic sulfide mineral.
Chander and Fuerstenau (1972) determined that the relative flotation of molybdenite was at a maximum in the pH range of 5.5 to 6.5. Although generally considered a hydrophobic, easily floatable mineral, molybdenite can be depressed quite easily by high pH (Chander and Fuerstenau, 1972), by calcium ions (Chander and
Fuerstenau, 1972), by ferrous and ferric ions at higher pH values (Castro and Bobadilla,
1995), by shear degraded polyacrylamide at acidic pH (Castro and Laskowski, 2004) and by dextrin (Wie and Fuerstenau, 1974).
Direct oxidation studies of the mineral have also been carried out. Chander and
Fuerstenau (1972) roasted the mineral at high temperatures, and reported the average contact angle on cleaved faces directly after oxidation. Figure 2-1 below explains the concept of the contact angle, which is a measure of surface hydrophobicity/floatability.
Figure 2-1: Contact angle, represented by 0 above. It is the tangent of the air-liquid interface, and reflects the surface-wetting properties of the solid. When the contact angle = 0°, a condition of perfect hydrophilicity is achieved. When the contact angle = 180°, perfect hydrophobicity is apparent.
Chander and Fuerstenau (1972) found that contact angle of untreated molybdenite was 80° on the hydrophobic face. Roasting the molybdenite at 300°C for one hour gave an angle of 63°; a further treatment at 500°C for one hour gave an angle of 53°; a further exposure at 500°C for three hours gave an angle of 30°; and finally, oxidation at 550°C for one hour gave, an angle of 35°. These numbers show that only under quite severe oxidizing conditions, the decrease in the contact angle is large; this is attributed to the appearance of hydrophilic sites on the surface, probably due to the formation of oxides.
2.3 Chalcopyrite - molybdenite separation
Most copper ores are generally too dilute for directly smelting out the copper in a cost-efficient manner. The ore from the mine must therefore be concentrated by beneficiation prior to smelting or roasting.
Valuable minerals like chalcopyrite are typically intergrown with gangue. To liberate the individual mineral phases, the ore is initially crushed and milled into fine particles (<100 um) (Lossin, 2001). Gyratory and cone crushers start off this liberation, which is then followed by wet grinding in tumbling mills. Size classification is performed in cyclones after the grinding. In the next stage of beneficiation, valuable minerals and gangue are separated by the froth flotation of the ore pulp. This is done by exploiting the different surface properties of the valuable components and the gangue (Forssberg,
1985).
At first, the chalcopyrite particles are hydrophilic. Through the addition of collectors (organic reagents with sulfur-containing groups at the polar ends, such as xanthates), the chalcopyrite is rendered hydrophobic. This allows the chalcopyrite particles to attach themselves to air bubbles dispersed through the pulp. The particles rise with the bubbles to the surface of the pulp, where they are skimmed off as froth, forming the bulk concentrate. Hydrophilic gangue minerals remain in the pulp, and are rejected as tailings. Hydrophobic minerals, however, like molybdenite and talc, also float with the chalcopyrite, posing a separation problem for the bulk concentrate.
The bulk concentrate is further separated via selective depression of chalcopyrite.
This time, the hydrophobic molybdenite is collected as the frothy concentrate, whereas the chalcopyrite is captured in the tailings (Bassarear et al, 1984). In order to achieve this separation, however, some rather deleterious reagents must be employed in the flotation procedure. These include: i) Sodium hydrosulfide, sodium sulfide or ammonium sulfide, as chalcopyrite
and pyrite depressants. Nitrogen gas is typically used instead of air in the
plants using this approach, as it reduces the oxidation and consumption of
sodium hydrosulfide. In some cases, the final molybdenite concentrate may be
subjected to a cyanide or ferric chloride leach to remove residual copper (Day, 2002). For example, Highland Valley Copper mine in British Columbia uses
sodium hydrosulfide in combination with nitrogen. Sodium sulfide was
reported as the copper depressant in the plants in Amalyk (Uzbekstan), in
Armenia, Cyprus Pima Mining Company's open-pit copper mine in Arizona,
and in Balkhash (Kazakhstan) (Bassarear et al., 1985).
ii) Noke's reagents, i.e. thiophosphorus or thioarsenic compounds, used as
chalcopyrite depressants. The final cleaning stages usually require sodium
cyanide washes (Day, 2002, Bassarear et al., 1985).
iii) Sodium or potassium ferrocyanide, under more oxidizing conditions (i.e. in
the presence of hypochlorite or hydrogen peroxide), can also be used as
chalcopyrite depressants (Day, 2002). The Molybdenite Corporation of
Canada's plant in Quebec reportedly used sodium cyanide as well as sodium
sulfite to depress their copper and iron sulfides (Bassarear et al., 1985). Ferro•
cyanide depressants are known to have been used at the Esperenza Mine run
by Duval Corporation (Bassarear et al., 1984).
All these chemicals are relatively environmentally hazardous, and toxic in comparatively low doses. This thesis investigates replacing these depressants with non• toxic lignosulfonates, without compromising the selectivity of copper-molybdenite sulfide separation.
2.4 Xanthates
Xanthates are derivatives of carbonic acid (H2CO3), where two oxygen atoms have been replaced by sulfur atoms, and one hydrogen atom has been replaced by an alkyl radical. Thus, they are O-alkyl dithiocarbonates (Leja, 1982). Commercial xanthates are rarely more than 90% pure. Alkali xanthates of short hydrocarbon chains are readily soluble in water. For flotation purposes, the most important reactions in xanthates occur in solutions in the pH range 6 to 12. Leja (1982) stated that it had been conclusively demonstrated that some oxidation, from oxygen in air, or an oxidizing agent, is necessary before xanthates can function as collectors in sulfide systems. Whether it is the oxidation of xanthate ions to dixanfhogen (R-OCS2-
S2CO-R), via the reaction shown below as equation (1), or whether it is the oxidation of sulfides to provide hydrophobic metal xanthate by-products, has not been proven.
2ROCS2 <^>{ROCS2)2+2e'
(1) 2ROCS~ +Y202 +H20 <=> (ROCS2)2+20H-
If there are no reactive species, such as dixanthogen, to influence the reaction between the xanthate ion and water, the half-life of the xanthate solution is constant and at its highest between pH 6 to pH 11. Therefore, the least amount of xanthate degradation will occur if the solution is maintained at an alkaline pH (Leja, 1982). Thus, fresh xanthate was made every day in this investigation, with a small amount of KOH to ensure a stable alkaline solution.
Arbiter (1985) summarized that chalcopyrite floats exceptionally well with xanthate as a collector. At the appropriate xanthate concentrations, complete chalcopyrite flotation can be achieved over a wide pH range (reportedly 3 to 12).
Leja (1982) stated that five main surfactant species were present in a xanthate- sulfide flotation system, in an aerated alkaline pulp: the xanthate ion (ROCSS),
dixanthogen (ROCSS-SSCOR), monothiocarbonate (ROCOS), metal xanthate (MX2),
+ and occasionally, metal-xanthate complexes ( M(X) or M(X)a"); note that X denotes the alkyl xanthate group; R denotes the associated xanthate hydrocarbon chain; M donates a the sulfide metal in the system, in our case, copper.
According to Leja (1982), the metal xanthate and the metal complexes are introduced into the system by the oxidative products formed on the surface of the ore.
Appreciable oxidation of sulfide surfaces can occur when the ore is exposed to the atmosphere, during grinding or whilst aerating the feed for flotation. The oxidation products thus created dissolve, producing measurable concentrations of metallic ions in pulp. These ions then form soluble metal-xanthate ionic complexes, as well as insoluble metal xanthates. The surfaces of the solid phases, from which the metal ions were derived, are believed to adsorb xanthate species, and quite possibly act as nucleating sites for metal-xanthate precipitation. Taggart, cited by Leja (1982), hypothesized that flotation was due to this precipitation of insoluble heavy metal xanthates.
Pomianowski and Pawlikowska-Czubak's (1967) work on capacity-potential determination suggested that electrostatic (physical) adsorption of the xanthate ion took place first, without any charge transfer occurring (an indicator of chemical adsorption).
Then, at a higher charge potential, a single charge transfer reaction took place, signifying the chemisorption of the xanthate ion. This is followed by a second charge transfer later, interpreted to be the formation of adsorbed dixanthogen. Subsequent two-electron transfer steps occurred, probably due to the formation of a metal xanthate on the surface.
Leja (1982) summarized the work of several other authors and stated that the electrochemical evidence indicated that chemisorption of xanthate species alone cannot result in sulfide flotation. Either a metal xanthate, or dixanthogen - formed at the metal- liquid interface - has to coadsorb on the first layer of adsorbed species (i.e. a Cu-X layer) before flotation can be induced. Thus, the hydrophobic character of the adsorbed xanthate was furnished and controlled by its metal xanthate or dixanthogen, physically coadsorbed, not by the chemisorbed species alone. Furthermore, the nature of the adsorbate species is not restricted just to dixanthogen or to the xanthate ion alone, but either of these two species can and probably do act as adsorbates, depending on conditions and availability. Generally, no direct evidence has been presented clarifying
+ the adsorption characteristics of metal xanthate complexes, M(X) or M(X)a". Leja (1982) speculated that, these species, when available, are likely to participate in depositing xanthate on sulfides; the nature of this participation is unknown.
2.5 Lignosulfonates
Industrial lignins are the by-products of the pulp and paper industry. The principle commercially available lignins are lignosulfonate and kraft lignin (Lebo et. al., 2001).
Lignosulfonates are derived from the sulfite pulping of wood, where the lignin within the wood is made soluble via sulfonation, at the benzyl alcohol, benzyl aryl ether and benzyl alkyl ether linkages of the phenyl propane units (Schneider, 1975). Depending on the intricacies of the pulping process, lignosulfonates of various bases, such as calcium, sodium, magnesium and ammonium, can be manufactured. These initial lignosulfonates can be easily manipulated into constructing different polymers with diverse properties. Unmodified lignosulfonates by themselves are known to have complex chemical and physical properties. Their molecular weight distributions as well as physical structures vary greatly, and they can be dissolved in water in virtually all pH values, but are insoluble in most common organic solvents (Lebo et. al., 2001). Various methods are available for the isolation and purification of lignosulfonates from spent pulping liquors. An example is the Howard process, where calcium lignosulfonates are precipitated out in the presence of an excess of lime (CaO).
Recoveries of 90 - 95% are achievable through this process (Lebo et al., 2001). Other industrially applicable methods include ultrafiltration and ion-exclusion, where ion- exchange resins separate the lignin from the sugars (Schneider et al., 1975). Many laboratory scale methods are available for isolating lignosulfonates; these include dialysis, electrodialysis, ion exclusion, precipitation in alcohol and extraction with amines. Precipitation using long-chain substituted quaternary ammonium salts is also possible (Lebo et al. 2001).
Lignosulfonates are considered non-toxic. To illustrate this point, consider the lethal dose 50 (LD50). The LD50 is a statistically derived single dose of a chemical that can be expected to cause death in 50% of a given population of organisms under a defined set of experimental conditions. It is not a very quantitative or accurate method of classifying toxicity, but does allow gross comparisons. In most cases, the oral LD50 for lignosulfonates is greater than 5 g/kg of rat (Lebo et al., 2001). For comparison, the equivalent LD50 value of table salt, NaCl, is 3 g/kg, and the equivalent sodium cyanide
LD50 value is 6.4mg/kg.
2.6 Lignosulfonate uses
Worldwide, the single largest use of lignosulfonates is as a water reducer for concrete (Lebo et. al., 2001). Addition of 0.1 - 0.3% of lignosulfonates primarily enhances concrete strength, and additionally retards the setting of concrete, which is why an estimated 50% of lignosulfonates produced worldwide are used for concrete mixtures
- 10- (Gargulak et al., 1999; Nimz, 2003). The second most important lignosulfonate
application is as a binder for animal food pellets, where a maximum dosage of 4% is
allowed in finished pellets. There are many oil-related functions of lignosulfonates, where chrome and ferrochrome salts of lignosulfonates are used in oil well drilling muds
as mud thinners, clay conditioners, viscosity control agents, and fluid loss additives.
Borregaard Lignotech in Norway uses lignosulfonates to produce vanillin; producers in
North America have ceased production in the past twenty years due to lower vanillin production costs from petrochemical feeds (Goheen, 1971; Nimz, 2003).
Due to the diversity of the lignosulfonate chemical properties, the research done on possible mineral processing applications of these polymers is quite broad in nature.
The chronologically presented cases below demonstrate this diversity.
Mathieu and Bruce (1974) looked at using lignosulfonate salts to separate talc from molybdenite ores. They found that lignosulfonates depressed molybdenite and had no effect on talc flotation at normal concentrations, even when the talc content of the feed exceeded 1%. They also found that the floatability of molybdenite depressed by the lignosulfonate could be restored by adequate addition of kerosene. While concentration control was not critical and was practically independent of talc content, the method did not require a separate flotation for the pre-concentration of the talc.
Arsentiev and Leja (1977) tested lignosulfonates as potential clay flocculants in the flotation of KC1 from a potash ore containing 5% clay. Their particular lignosulfonate was perceived as a poor 'slime blinder', in that it did not successfully depress the deleterious clay without affecting the potash flotation. Specifically, they noted that while a substantial decrease in the clay "recovery" was observed, the addition of their lignosulfonate also resulted in a reduced KC1 recovery.
Pradip and Fuerstenau (1991) investigated the use of lignosulfonates in the separation of rare-earth oxides. Specifically, they carried out a detailed study, examining solution equilibrium, electro-kinetic measurements, adsorption tests, micro-flotation and batch flotation tests to delineate the surface interactions of various reagents in the separation of a typical bastnaesite type rare-earth ore. The focus of this study was the flotation of a complex ore containing bastnaesite, barite, calcite and other sparingly soluble sulfates and carbonates (Mountain Pass deposit, California). Using a multistage conditioning procedure involving soda ash, lignosulfonates and steam with a fatty acid collector, carbonates can completely be separated from the sulfates. A number of inorganic and organic depressants were investigated by the rare-earth plant whilst developing the multistage conditioning procedure, and ORZAN-G, an ammonium lignosulfonate, was found most efficient at depressing barite (Fuerstenau et al., 1980).
Further investigation of this system showed that although lignosulfonate adsorbed on all three minerals, its depressing action, on calcite was not deemed significant. This separation process used boiling temperatures during conditioning, which were believed to make the lignosulfonate more selective. However, the extensive study done by Pradip and
Fuerstenau (1991) showed that the high temperature did not make the lignosulfonate any more selective, rather, it affected the selective adsorption of the fatty acid collector.
Sadowski found a particular sodium lignosulfonate from Crown Zellerback
Chemicals to be a selective dispersing agent for barite suspension (Sadowski and Smith,
1989; Sadowski, 1992). He went on to study the surface-chemical aspects of the spherical
- 12- * agglomeration of salt-type minerals, to demonstrate the influence of pH and modifying reagents on the selectivity of this agglomeration (Sadowski, 1994). The experimental data showed that the selective spherical agglomeration of binary mineral suspensions (barium- carbonate) is possible when the lignosulfonate was used as a surface modifier. A beneficial selectivity could be attained, if the lignosulfonate was added prior to the surfactant. Sadowski speculated that the presence of the lignosulfonate probably reduced the surfactant salt adsorption to the surfaces of the carbonate mineral particles.
Singh (1998) investigated the separation of plastics from a mixture using appropriate wetting agents. Polyvinyl chloride (PVC) and polyoxymethylene (POM) plastic samples were obtained from local agents and crushed, such that 2 to 4mm size fractions were used for studies on selective flotation separation, while ground samples under 100-mesh were used for adsorption tests. A sodium lignosulfonate was then compared against sorbitan monolaurate, to depress the plastics which under normal circumstances are naturally floatable. The sodium lignosulfonate was found to be the better depressant for the PVC. The adsorption tests showed that the lignosulfonate adsorption density was a little higher than the sorbitan monolaurate adsorption density.
Lu and Sun (1999) looked at the role of lignosulfonates in the phosphorus recovery flotation process, where the fine dissemination of the intergrown minerals and high content of carbonates must be addressed. They reported that a specific depressor developed for gangue-mineral dolomite, a sodium lignosulfonate referred to as L399, had been used to replace sodium silicate as the gangue depressant in the Jinping phosphorus mine (China). The flotation performance of the plant significantly improved, due to the successful removal of more than 95% of the gangue minerals, including dolomite, calcite,
- 13 - and iron, aluminium and silicon minerals. Studies of the depression mechanism of L339 showed that the lignosulfonate interacts with fatty acids to form a complex, which promotes the collector adsorption on fluorapatite, thus enlarging the wettability difference between apatite and carbonate gangue minerals.
Kelebek et al. (2001) used adhesion tension diagrams to characterize wettabilities of molybdenite and talc samples in sodium lignosulfonates and methyl isobutyl carbinol
(MIBC) solutions. They found that the adsorption density of the sodium lignosulfonate at the molybdenite/liquid interface of molybdenite face was significantly larger than that of talc by a factor of 2.7. They attributed this difference as the main reason for observed selectivity in the wetting and flotation separation of talc from molybdenite.
Grigg and Bai (2004) carried out adsorption and desorption studies with a calcium lignosulfonate on Berea sandstone. The study was focused on surfactants used for mobility control and fluid diversions caused by foam in the surfactant-based enhanced oil recovery processes. Their study showed that the lignosulfonate adsorption density was influenced by lignosulfonate solution concentration, temperature, salinity and injection rate. They also found adsorption and desorption were not completely reversible in the time frame of their experiment.
Ceramic wet-forming techniques, such as slip-casting, pressure-casting and thixotropic-casting, generally require suspensions that contain moderate-to-high solids loadings, exhibit good stability and have a low apparent viscosity as well as approximately Newtonian rheological behaviour. Such suspensions can be made by colloidally dispersing the ceramic particles in a liquid medium via pH control, and by the use of organic dispersants. Wet-forming for piezoelectric ceramics, based on lead
- 14- zirconate, had not been viable commercially, in part because of the inherent difficulties in producing a stable suspension of lead zirconate titanate (PZT). Ratinac et al. (2004) investigated the adsorption of lignosulfonate onto a commercial modified PZT powder in aqueous suspension, and its effect on PZT zeta potential and rheology. They found that a stable suspension at a given pH occurred at lignosulfonate dosages corresponding to monolayer coverage of the PZT particles. They speculated that stabilization of the suspensions took place by means of an electrosteric mechanism, due to the expanded conformation of the molecules under high pH conditions. Such suspensions proved suitable for use in ceramic wet forming of electroceramic PZT components.
Lignosulfonates were tested as potential talc depressants by Ma and Pawlik
(2005). They were found to completely depress the flotation of talc at high pH values when lime was used for pH adjustments. Ma and Pawlik speculated the role of lime in the system was to provide calcium ions to specifically adsorb onto the talc surfaces, thereby
'activating' the surface for lignosulfonate adsorption. They also found the adsorption density of the talc decreased with an increasing degree of anionicity in the reagents, suggesting that electrostatic forces controlled the adsorption process on the mineral.
- 15- 3.0 Experimental Procedure
3.1 Materials
3.1.1 Equipment
A Cary 50 Scan UV-Visible-Spectrophotometer by Varian was used for all absorbance readings. The centrifuge employed in this study was a Sorvall Biofuge Primo.
For uniform conditioning prior to the flotation tests, an RZR 1 Caframo mixer was used at the lowest speed for the indicated amounts of time. For uniform conditioning in the adsorption tests, the Labline Instruments' Orbit Enviro Shaker was used, at a moderate setting for the indicated amounts of time. All measurements and dilutions were made on a mass basis using an Ohaus Explorer analytical balance.
3.1.2 Minerals
Chalcopyrite, reportedly from Durango, Mexico, was obtained through Ward's
Natural Science (Rochester, NY). The material arrived as large pieces (approx. 2 inches by 3 inches), was dry-crushed to below ^-3/4 in. (20 mm), and then dry-ground using a porcelain ball mill. Preliminary flotation tests gave a yield of only about 60% which indicated that the mineral was not of high purity. This was confirmed by a chemical assay which showed a chalcopyrite content of 70%. This grade was considered insufficient for a systematic study. The remaining chalcopyrite pieces were "hand-picked" after dry- crushing and any pieces containing visible mineral inclusions were rejected. This simple procedure increased the chalcopyrite grade to over 90%.
The finely ground minerals were dry-screened on 105- and 38-micron sieves, and two size fractions were extracted: -105+38 microns, and -38 microns (finer than 38 microns). The -105+38 micron size fraction was used for flotation studies while the -38 micron material was retained for further adsorption tests. Since sulfide minerals are quite
-16- reactive under normal conditions, all the size fractions were stored in a closed container in the refrigerator to prevent any chemical oxidation of the minerals.
Molybdenite (M0S2) was obtained from Ward's Natural Science (Rochester, NY) in two batches. Received as large pieces (approximately 2 inches by 3 inches), it was dry- crushed to below -3/4 in. (20 mm), and then dry-ground using a porcelain ball mill.
The sample pieces appeared to be of low purity, showing signs of advanced oxidation with fine green-blue precipitates present on each piece. To produce as clean a fine fraction suitable for flotation as possible, the ground mineral was placed in a Denver
2 L flotation cell and mixed thoroughly with about 2 L of distilled water. The mechanical attrition being applied to the mineral allowed the relatively soft, fine molybdenite grains to detach themselves from the quartz-like matrix. The slurry was allowed to settle in the cell and any fines left in suspension were decanted. The liberated molybdenite was then floated out without any reagents present in the pulp. After about 1 hr of such collector- less flotation, the tailings left in the cell showed no visible grains or veins of molybdenite. The concentrate slurry was then wet-screened to extract the -150+38 microns (finer than 150 microns but coarser than 38 microns) size fraction. This material was then used for Hallimond tube flotation tests, whereas the undersize was retained for adsorption studies. There was not enough undersize to carry out all the adsorption tests, so more molybdenite was obtained, and processed as described above. The old undersize, the new processed molybdenite and remaining flotation grade molybdenite were then combined to make the required amount of adsorption grade. The samples were dried under vacuum, placed in a polyethylene bag, and stored in a refrigerator to prevent oxidation.
- 17- The minerals were assayed for purity by International Plasma Labs, by means of a multi-acid digestion followed by an atomic adsorption assay. The chalcopyrite and molybdenite samples were assayed for elemental copper and elemental iron; the molybdenite samples were assayed for elemental molybdenum as well. These elemental contents were used to calculate mineral purity, as summarized in Table 3-1 below. The molybdenite sample was reported to contain trace amounts of elemental copper and elemental iron, 0.37% and 0.81%, respectively.
Table 3-1: Summary of mineral purity. Mineral Grade Chalcopyrite Molybdenite Purity (%) Purity (%) Adsorption (-38 micron) 99.55 65.40 Flotation (+38 -105 micron) 98.02 72.98
The particle size distributions of the adsorption grade chalcopyrite and molybdenite were obtained using the Malvern Mastersizer 2000; these distributions can be seen in Appendix I.
A Quantachrome Autosorb-IMP BET analyzer was used to determine the BET
(Brunauer Emmett Teller; Brunauer et al., 1938) specific surface area. The specific surface area was determined from nitrogen adsorption after outgassing at room temperature for 60 hours, followed by outgassing at 80°C for 2 hours, both under vacuum. The surface area for the chalcopyrite was 0.29 m2/g and 0.89 m2/g, for the flotation and adsorption grades, respectively. The surface area for the molybdenite was
2 2
0.63 m /g and 2.03 m /g, for the flotation and adsorption grades, respectively.
3.1.3 Reagents
Potassium nitrate (KNO3) from Fisher Scientific was used to maintain a constant ionic strength for the flotation tests. Thi- 18s -background electrolyte was made at a concentration of 0.001M, by dissolving 0.2022g in 2 L of distilled water in a 2000-mL volumetric flask. Since the nitrate ion caused interference in the UV absorbance readings, potassium chloride (KC1), also from Fisher Scientific, was used to maintain constant ionic strength in the adsorption tests. This background electrolyte was made at a concentration of 0.001M, by dissolving 0.1491g, in 2 L of distilled water in a clean volumetric flask.
Six different lignosulfonates were provided by Borregaard LignoTech for testing purposes: D619, D648, D659, D748, D750 and D912. Halfway through the investigation,
D659 was replaced by D701, upon the request of Borregaard LignoTech. The chemical properties of all these lignosulfonates are tabulated below. Note that the tree species is indicated using S to denote softwood, and H to denote hardwood.
Table 3-2: Select properties of lignosulfonate reagents being investigated.
Ca Na Total Sulfonate Carboxylic Molecular Tree [%] [%] Sulfur Sulfur [%] Groups [%] Weight Species [%] [kDa] D-619 0.0 9.0 7.0 6.0 3.2 25 S D-648 0.1 15.9 11.1 8.1 7.4 5 H D-659 0.0 9.0 4.9 4.2 5.2 30 S D-701 8.7 0.3 6.6 5.8 7.2 10 H D-748 0.0 7.0 6.5 6.2 3.1 45 S D-750 0.0 8.0 3.2 2.7 7.4 6 S D-912 8.0 0.1 6.5 5.0 7.2 5.5 H
For the flotation tests, 10 g/L lignosulfonate solutions were made, i.e. l.OOg of the lignosulfonate powder was weighed in a volumetric flask, and made up to the 100-mL mark using the background electrolyte. For the chalcopyrite adsorption tests, the lignosulfonate solutions were made at a concentration of 1 g/L, i.e. 0.05g of lignosulfonate powder was carefully weighed into a volumetric flask, and made up to the
- 19- 50-mL mark using the background electrolyte. For the molybdenite adsorption tests, the lignosulfonate solutions were made at a concentration of 0.5 g/L, i.e. 0.025g of lignosulfonate powder is weighed into a volumetric flask and made up to the 50-mL mark using the background electrolyte.
The potassium salt of ethyl xanthic acid (Acros Organics) was used as the chalcopyrite collector. For the chalcopyrite flotation tests, a 10 g/L stock solution was made, i.e. 0.5g was weighed on an analytical balance, into a volumetric flask. A chip of
KOH (-0.1 g) was added to ensure reagent stability at high pH, and then the background electrolyte, 0.001M KNO3, was used to make the solution up to 50 mL. For the chalcopyrite adsorption tests, a 1 g/L stock solution was made, i.e. 0.05g was weighed into a volumetric flask using an analytical balance. A chip of KOH was added and the solution was made up to the mark using background electrolyte (0.001 M KC1 in this case).
For adjusting pH, three reagents were used. Lime (CaO) from Fisher Scientific was made into a 6% solids-content suspension, by mixing 3g into 50 mL distilled water.
Potassium hydroxide (KOH) from Fisher Scientific (in pellet form) was made at a concentration of 0.5M KOH by dissolving 1.40g of KOH in 50 mL of the appropriate background electrolyte. Anhydrous soda ash (Na2C03) from Fisher Scientific was added in excess to make a saturated solution in the background electrolyte when needed.
Dodecane (C12H26 - Sigma Chemicals) was used as a collector in some molybdenite flotation tests. Acetone from Fisher Scientific was also used as a cleaning agent in the majority of molybdenite flotation tests, to remove any organic residue from the molybdenite particles.
-20- The frother used in all flotation tests was methyl isobutyl carbinol (MIBC,
Aerofroth 70, from Cytec Chemicals). It was made down to 1 g/L, by weighing 0.25g (+ a drop) into a clean 250-mL volumetric flask and making up to the mark with distilled water.
3.2 Methods
3.2.1 Hallimond Tube Flotation Flotation tests were carried out to determine the experimental conditions under which the lignosulfonates could successfully depress the minerals being studied.
3.2.1.1 Chalcopyrite Flotation Tests
Despite repeated screening, the chalcopyrite contained a significant quantity of very fine poorly floating particles which had to be removed prior to flotation. 3.400 grams of the -105+3 8-micron size fraction was weighed on an analytical balance and placed in a 400-mL beaker. The pre-weighed amount of each mineral was mixed with
300 mL of distilled water. The mixture was placed for exactly 1 minute in an ultrasonic bath. The beaker was then quickly removed from the bath and allowed to settle for 15 seconds. Fine fractions were then removed by decanting the suspension. This desliming procedure was repeated an additional two times, until no slimes were left in suspension with the last decanting step done with 0.001M KNO3, the background electrolyte. Since sulfide minerals generally have high densities, it is easy to pour off practically the entire amount of solution leaving only wet mineral particles on the bottom of the beaker.
The wet, deslimed chalcopyrite was then conditioned with 80 mL of a 0.001 M
KNO3 solution in a 150-mL glass beaker for about 2 minutes. The pH of the pulp was adjusted using a 6% (wt) saturated suspension of lime (CaO). Afterwards, 0.425 mL of
-21 - 10 g/L potassium ethyl xanthate solution was added and the pulp was conditioned for 5 minutes. After readjusting the pH, when necessary, an aliquot of 10 g/L lignosulfonate solution (in 0.001M potassium nitrate) was added to the mixture and the entire suspension was conditioned for a further 10 minutes. The order of reagent addition should be noted: the xanthate was added first, followed by lignosulfonate. A small aliquot
(1.7 mL) of a stock 1 g/L MIBC (flotation frother) solution was added to the beaker, to achieve a final frother concentration of 10 mg/L, and the suspension was conditioned another 1 minute. For every lignosulfonate sample a series of tests was also carried out at natural pH, ranging from 5.5 to 8.5, without any CaO additions.
After conditioning, the whole mixture was transferred to a modified Hallimond tube and the tube was filled up with 0.001M KNO3 solution (with a pre-adjusted pH value). The final xanthate (chalcopyrite collector) concentration was 25 mg/L in all the tests. This dosage was optimized in a series of preliminary tests. Above 25 mg/L of xanthate, there was no significant improvement in the flotation of the sulfides.
The pulp was mechanically mixed in the tube for about 20 seconds. The total volume of the pulp was 170 mL. After mixing, flotation commenced, as shown in Figure
3-1.
-22- Figure 3-1: Illustration of modified Hallimond tube flotation test. Air bubbles combine with hydrophobic mineral particles to form a froth, which spills over into the collection arm.
All the chalcopyrite tests were preformed using compressed air. The flotation time was 90 seconds to minimize the mechanical carry-over of poorly floating particles, while the air flow rate was carefully maintained at 20 mL/min. The frother concentration was kept constant at 10 mg/L. This small amount of MIBC enhanced the kinetics of mineral flotation while stabilizing the formation of smaller, more uniform-in-size gas bubbles.
A flotation concentrate from each test was collected into the side-arm of the tube, and vacuum-filtered on a Q2 (fine porosity) Fisher Scientific cellulose paper. The wet product was then dried in an oven at 110 °C, and weighed on an analytical balance to the nearest 0.1 mg taking a correction for the mass of a dry filter paper. Any material left in the tube after flotation was treated as tailings. This non-floating (depressed) fraction was also collected, dried and weighed to calculate the yield of each flotation test. Note that a
-23 - significant amount of each mineral was lost due to desliming, so it would not be very accurate to base the calculations on the original amount of each mineral (3.400 g). The desliming procedure proved to be very reproducible and a total of 2.5-2.7 g of mineral
(tails + concentrate) was consistently collected from each test.
Lignosulfonate concentrations varying from 25 to 200 mg/L were investigated, at a natural pH, as well as at pH 9 and pH 11, using lime. A "control" test for each type of lignosulfonate was also performed using potassium hydroxide (KOH) and soda ash
(Na2C03) for pH adjustment. The reference lignosulfonate concentration chosen for such a test depended on the relative depressing power of each lignosulfonate reagent. In addition, a limited number of tests were performed with lignosulfonates added before xanthate. These tests are referred to as "LS first" in the legend to each figure.
3.2.1.2 Molybdenite Flotation Tests
To remove any oxidation products present on the molybdenite particles, the sample was first treated with 0.1M KOH followed by a distilled water wash, followed by a 64 mL (equivalent to 50 g) acetone wash (to remove organics), followed by another distilled water wash and a final rinse using the background electrolyte. After each washing step, the particles were allowed to settle and the supernatant was siphoned off, in order to preserve the hydrophobic layer of particles floating on the water-air interface.
This treatment restored the natural floatability of the mineral to higher levels, but still under the levels described in literature.
For molybdenite, no additional desliming was necessary since the attrition, wet- screening, and washing steps produced a sufficiently classified product for flotation. The mineral particles were conditioned with 80 mL of a 0.001M KNO3 (potassium nitrate)
-24- solution in a 150-mL glass beaker for about 2 minutes. Potassium nitrate was used to provide constant ionic strength. The pH of the pulp was adjusted to a pH of 8 using a 6%
(by weight) saturated suspension of lime (CaO), potassium hydroxide (KOH), or soda ash
(Na2C03). Afterwards, an aliquot of 10 g/L lignosulfonate solution (in 0.001M potassium nitrate) was added and the pulp was conditioned for 10 minutes. A small aliquot (1.7 mL) of a stock 1 g/L MIBC (flotation frother) solution was added to the beaker, to achieve a final frother concentration of 10-mg/L (10 ppm), and the suspension was conditioned another 1 minute. No collector was used in these tests.
The flotation and concentrate collection procedures were the same as in the case of the flotation tests with chalcopyrite, however, the lignosulfonate concentration varied between 5 and 50 mg/L.
A few of the molybdenite tests were carried out with the use of dodecane, to investigate the effect of an oily collector on the floatability of molybdenite. The sample was washed in the usual manner. Then, 6 mL of a dodecane emulsion, made by emulsifying 0.03g dodecane in 100 mL of background electrolyte in a blender, was added, and the sample was conditioned for five minutes. The sample was then conditioned as described above, first with lignosulfonate, then with MIBC, and the flotation was performed as usual in the modified Hallimond tube.
In the tests where the addition of dodecane followed the addition of the lignosulfonate, the sample was washed in the usual manner. 6 mL of a dodecane emulsion, prepared as described above, was added to the sample after it was conditioned with the lignosulfonate; the sample was then conditioned for a minute using MIBC, and the flotation was performed as usual in the modified Hallimond tube.
-25 - 3.2.2 Adsorption Tests
Adsorption tests were carried out for both minerals to gain insight into the mechanism of mineral depression by lignosulfonate. The equilibrium concentrations of the lignosulfonate and xanthates were determined in these tests. An analytical procedure was developed to simultaneously measure the amounts of lignosulfonate and xanthate.
The method is based on the UV absorbance measurements.
3.2.2.1 Calibration Curves and Adsorption Matrices
The Beer's law is an approximate expression for the change in the intensity of a light beam passing through an absorbing medium. It is shown below, as Equation 2, where In represents the incident light intensity, I is the final light intensity, s is the molar absorption coefficient, c is the molar concentration of the absorbing substance, and 1 is the light path length, 1 cm in this case.
( i\ A= log -eel (2)
Since according to the Beer's law, the absorbance for a multi-component solution is an additive quantity, an absorbance-concentration matrix was put together, based on the calibration curves, to simultaneously calculate the amount of xanthate and the amount of lignosulfonate found in a given supernatant sample (after removing mineral particles by centrifuging).
To verify the absorbance characteristics of ethyl xanthate, a UV scan was carried out from 220 nm to 350nm, for a 25 mg/L xanthate solution. The concentration was made by diluting a 1 g/L bulk xanthate solution, made in distilled water with KOH to stabilize the pH at a mildly alkaline range. The pH of solution was varied using both KOH and
CaO, to investigate the impact of the pH modifiers on the absorbance spectra. The peaks
-26- were located at 302 nm and 226 nm, close to the literature values; as can be seen in
Figure 3-2. The absorbance peaks were fairly independent of the pH examined, and the modifier used to achieve a given pH value.
3 i i i i i i 1 Im I i i i i i i i i i 1 i i i i i i i i i I
200 240 280 320 360 Wavelength [nm]
Figure 3-2: Absorbance spectra of potassium ethyl xanthate, at a concentration of 25 mg/L.
For each lignosulfonate, scans in the wavelength range from 210 to 400 nm were carried out to determine the optimum wavelength for spectrophotometric measurements.
It was quickly established that the absorbance spectra of a 50 mg/L lignosulfonate solution varied significantly depending on the pH and the reagent used for the pH adjustments (KOH, or CaO). However, the absorbance spectra for each lignosulfonate exhibited a common intersection wavelength, where the absorbance was independent of the experimental conditions. Thus, instead of using several different calibration curves, a single calibration curve was prepared at the common wavelength for each reagent. The measuring wavelengths for the lignosulfonates were 229 nm for D748, 233 nm for D619
-27- and D912, 236 for D648 and D701, and 308nm for D750. This phenomenon is illustrated for D912 in Figure 3-4.
~i—i—i—i—i—i—r ~i—i—i—i—i—i—i—i—i—|—i—r 240 280 Wavelength [nm] Figure 3-3: Absorbance spectra of lignosulfonate D-912, at a concentration of 50 mg/L. The common intersection wavelength is read at 233 nm, whereas the lignosulfonate contribution to the xanthate absorbance is the average of the readings at 302 nm.
For the lignosulfonate D-912, the common intersection point can be seen to be
233 nm in Figure3-3. A calibration curve was thus constructed at this point, by varying the concentration of the lignosulfonate solution between 0 and 150 mg/L and plotting the absorbance thus obtained. These individual curves are provided in Appendix II.
Since the lignosulfonate absorbance recorded at 302 nm varied depending on the pH of the solutions as well as the reagent used to obtain this pH, the average absorbance
302 nm was recorded from the above spectrum. This was used to approximate the contribution of the lignosulfonate to the total absorbance reading at 302 nm, which in a mixture would originate from xanthate and lignosulfonate.
As mentioned before, an absorbance-concentration matrix was put together, based on the calibration curves, to simultaneously calculate the amount of xanthate, and the
-28- approximate amount of lignosulfonate found in a given supernatant sample. The two equations comprising this matrix, at wavelengths of 302 nm and 233 nm are respectively given below as Equations 3 and 4. The S in the equations represents the slopes obtained from the calibration curves, and the C represents the concentration in mg/L; subscripts of the slopes indicate the wavelength as well as the reagent: the X subscript indicates xanthate, and the LS subscript indicates the lignosulfonate.
S'302.X + ^iOl.LS^LS = ^302 @)
^233,X^X + ^233,LsC' LS = -^233 (^) .
Together, these equations form a set of equations which, when simultaneously solved, provide the concentrations of both the xanthate and lignosulfonate in equilibrium, shown as Equation 5.
C ' A J 302.X ^302,LS ~cx~ •^302 (5). A ^233, X ^233,LS _ c . LS _ .^233 _
The matrix, once filled with the appropriate slope variables, looks as shown below as Equation 6. The numbers in this example are for the D-912 reagent.
~ A "0.10498 0.005284" C x •^302 0.040716 0.02051 r A _ LS _ . 233 _
The lignosulfonate amount obtained by the above calculation is not completely accurate, since the absorbance-concentration relationship was averaged out between the different points posed by the many curves at 302nm, as indicated earlier. The error involved in this approximation is not large since the absorbance of D-912 at 302nm was low compared to the absorbance of the xanthate at the same wavelength.
-29- In order to verify that the concentrations of the xanthate and lignosulfonate can be calculated using the above procedure, a set of model mixtures were examined. Each model mixture was made by using 0.001M KC1 background solution to dilute down the bulk reagent solutions, on a mass basis.. Appropriate amounts of a 1.00 g/L xanthate solution and 1.00 g/L D-912 solutions were used, to give the final concentrations shown in Table 3-3. As can be seen, cumulative reagent concentration was 50 mg/L for each solution. The calculated xanthate and lignosulfonate concentrations, using the Equation 6, for the model mixtures, are also shown. The agreement between the actual concentration and the recalculated concentration for the xanthates is quite remarkable. The lignosulfonate concentrations are not as accurate but still provide the correct qualitative trend. The deviation is attributed to the error due to the approximation at 302 nm mentioned above.
Table 3-3: Xanthate and lignosulfonate concentrations obtained for the model mixtures. Note that the concentrations were calculated using measured absorbances and the matrix given by Equation 6.
Solution Actual Recalculated % Actual Recalculated % No. xanthate xanthate Error lignosulfonate lignosulfonate Error concentration concentration concentration concentration in mg/L in mg/L, in mg/L in mg/L, using using absorbance absorbance 1 1 0.9 10 49 42.9 12 2 2 1.9 5.0 48 42.5 11 3 5 4.7 6.0 45 43.0 4.4 4 10 9.6 4.0 40 36.0 10 5 15 14.7 2.0 35 31.5 10 6 20 19.6 2.0 30 27.1 9.7 7 25 24.2 3.2 25 23.9 4.4
3.2.2.2 Chalcopyrite Adsorption Tests Initially, different pH-specific background electrolytes were made by raising the pH of stock 0.001 M KC1 to the desired value using the appropriate reagent, i.e.
-30- approximately pH 8.5, pH 10 and pH 11.5 using all the different pH reagents, i.e. lime,
KOH and soda ash separately. All tests were then run in their respective electrolytes.
4.000g of -38 microns (finer than 38 microns) chalcopyrite was weighed into a clean 125-mL Nalgene bottle. 25 mL of the appropriate background electrolyte was added to the bottle, after which the sample was conditioned on a shaker table for 5 minutes. 2.5 mL of 1 g/L xanthate solution was then added to the bottle, after which 22.5 mL of the appropriate background electrolyte was once again added to the bottle. The sample was conditioned for another five minutes in the shaker table. For a 'blank' sample, 50 mL of background electrolyte was used to make up the sample volume to 100 mL. Otherwise, the desired lignosulfonate concentration is achieved by adding the appropriate amount of 1 g/L lignosulfonate stock solution, and topped off to 100 mL using the correct background electrolyte. The final xanthate concentration was kept constant at 25 mg/L.
The sample was then conditioned one final time, for a minimum of 10 minutes.
Preliminary testing showed the absorbance readings did not significantly change after 10 minutes of conditioning, indicating that the adsorption equilibrium was achieved rather quickly.
After conditioning, the sample was transferred to a 50-mL centrifuge tube, and centrifuged in the Biofuge Primo for 8 minutes, at 10,000 Gs. If the once-centrifuged sample looked turbid, the centrifugation was repeated one more time in a fresh tube.
The supernatant of the sample was then poured into a clean quartz UV 1-cm cell, and absorbance measurements were obtained at wavelengths of 229, 233, 236, 302 and
308nm. These readings were zeroed against air, and the absorbance of the appropriate
-31 - background solution was subtracted prior to calculating the concentrations of the xanthate and lignosulfonate using the absorbance readings. All calculated lignosulfonate concentrations were also corrected against the blank test readings.
The amount of lignosulfonate adsorbed was calculated from the formula given as
Equation 7 below.
A = — ^ (7)
4g x SBET Ch
A is the amount of lignosulfonate adsorbed in mg/m , Cu, is the initial
lignosulfonate concentration in mg/L, Ceq. is the equilibrium lignosulfonate concentration as measured in mg/L, and SBET.ch is the specific surface area for the adsorption grade chalcopyrite in m /g.
3.2.2.3 Molybdenite Adsorption Tests
The molybdenite adsorption tests were carried out slightly differently from the chalcopyrite tests. Once again, different pH-specific background electrolytes were made by raising the pH of stock 0.001 M KC1 to the desired value using the appropriate reagent. All tests were then run in their respective electrolytes.
There was not enough adsorption grade molybdenite available to carry out full scale adsorption tests on the mineral. Therefore, individual tests were 'downsized'.
1.500g -38 microns (finer than 38 microns) molybdenite was carefully weighed into a clean 125-mL Nalgene bottle. 25 mL of the appropriate background electrolyte was added to the bottle, after which the sample was conditioned in the shaker table for 5 minutes. For a 'blank' sample, 25 mL of background electrolyte was used to make up the sample volume to 50 mL. Otherwise, the desired lignosulfonate concentration was
-32- achieved by adding the appropriate amount of 0.5 g/L lignosulfonate stock solution, and topped off to 50 mL using the correct background electrolyte.
The sample was then conditioned one final time, for a minimum of 10 minutes.
The sample was then transferred to a falcon tube, and centrifuged in the Biofuge Primo for 8 minutes, at 10, 000 Gs. The supernatant of the sample was then poured into a clean
1-cm quartz UV cell, and absorbance measurements were obtained at wavelengths of
229, 233, 236, 302 and 308nm. These readings were zeroed against air, and the absorbance of the appropriate background solution was subtracted prior to calculating the concentrations of the xanthate and lignosulfonate using the absorbance readings. All calculated lignosulfonate concentrations were also corrected against the blank test readings.
The amount of lignosulfonate adsorbed, was calculated from the formula given as
Equation 8 below. A represents the amount of lignosulfonate adsorbed in mg/m2, Cin is the initial lignosulfonate concentration in mg/L, Cgq. is the equilibrium lignosulfonate concentration as measured in mg/L, and SRET.MO is the specific surface area for the adsorption grade molybdenite in m2/g.
(C,„ -C£a)x0.05L A = — ^- (8)
1.5gxSe£TAto
3.2.3 Size Exclusion Chromatography tests
Size exclusion chromatography tests were carried out on the supernatants obtained from adsorption tests, to determine which weight fractions of the lignosulfonates were adsorbing onto the mineral surface. The high performance liquid chromatography
(HPLC) testing was done off-site by Borregaard LignoTech, the company sponsoring this research. Their testing method is summarized in this section.
-33 - 3.2.3.1 HPLC Apparatus and Reagents The instrument used in these tests is the Dionex DX 500 HPLC system. Jordi
4 °
Glucose-DVB columns, with 10 A pore size and 500x10 mm dimensions were used; the guard column was specified as GPC-300 A 7jim, and a Dioniex AD20 UV detector was used.
Nanopure water, with a resistance of 18 megaohm-cm or greater was used in the preparation of standards and reagents. HPLC grade dimethyl sulfoxide (DMSO), reagent
grade Na2P04H»7H20, 50% sodium hydroxide (NaOH) and reagent grade dodecylsulfate were the reagents used for this testing.
3.2.3.2 HPLC Procedure
First, the eluent was prepared. This was done by weighing out 800.0 g of nanopure water in a 1.0 1 vacuum flask. 80.9g of DMSO and 10.72g of sodium phosphate
(Na2P04H»7H20) was charged into the flask. The solution was stirred thoroughly, and the pH was adjusted to 10.50 using the NaOH.
The exact parameters of the HPLC testing are described in detail by Fredheim et al. (2002, 2003). A Lotus 123 spreadsheet is used to calculate molecular weight from the data transformed from a Peaknet file to a Lotus readable file. The spreadsheet calculation is based upon different polystyrene sulfonate standards of varying molecular weights (35
000, 18 000, 8 000, 5 400, 1 800 and 251). The intercept of the linear calibration curve was adjusted to match two standardized lignosulfonate standards of molecular weights 34
000 and 8 300. The results of these tests for each supernatant are attached in Appendix
III.
-34- 4.0 Results and Discussion
4.1 Flotation Tests
4.1.1 Depression of Chalcopyrite As Figures 4-1 to 4-6 show, the best chalcopyrite depression is achieved in presence of lime, at high pH values. Note the abbreviation LS refers to lignosulfonate.
0 50 100 150 200 Lignosulfonate Concentration [mg/L]
Figure 4-1: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-619.
1 1 1 1 1 1 1 1 r 0 50 100 150 200 Lignosulfonate Concentration [mg/L]
Figure 4-2: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-648.
-35- I I I D-659 pH 7.0-7.6 (natural) D-659 pH 8.9-9.2 (CaO) 2 D-659 pH 10.8-11.1 (CaO) 13 D-659 pH 11 (KOH) D-659 pH 7.8 (LS first) O v
O E
oOH O o 13 U —I 1 1 ' 1 50 100 150 200 Lignosulfonate Concentration [mg/L]
Figure 4-3: Flotation results of chalcopyrite in 0.001 M KN03, using the lignosulfonate D-659.
2 13
• D-748 pH 6.9-7.3 (natural) o • I-H • D-748 pH 8.8-9.2 (CaO) o A D-748 pH 10.9-11.1 (CaO) E v D-748 pH 11 (KOH) o O D-748 pH 7.8 (LS first) cu o o si U "i 1 r 200 50 100 150 Lignosulfonate Concentration [mg/L]
Figure 4-4: Flotation results of chalcopyrite in 0.001 M KNO3, using the lignosulfonate D-748.
-36- 0 50 100 150 200 Lignosulfonate Concentration [mg/L]
Figure 4-5: Flotation results of chalcopyrite in 0.001 M KN03, using the lignosulfonate D-750.
• D-912 pH 6.8-8.5 (natural) £ • D-912 pH 9.0-9.4 (CaO) A D-912 pH 10.8-11.1 (CaO) *-4—» v D-912 pH 11 (KOH) -4—» o O D-912 pH 7.3 (LS first) E
' 1 1 50 100 150 200 Lignosulfonate Concentration [mg/L]
Figure 4-6: Flotation results of chalcopyrite in 0.001 M KN03, using the lignosulfonate D-912.
In the case of reagents D-619 and D-648, chalcopyrite depression is only achieved at a high pH obtained using high dosages of lime, but at a relatively low lignosulfonate dosage. Under all other test conditions, these two lignosulfonates do not depress the mineral.
-37- Reagent D-748 appears to be a better depressant. It produces depression at moderate as well as high pH values adjusted with lime. As the pH adjusted with lime increases, lower and lower dosages of the reagent are required for depression.
Reagents D-659 and D-750 result in chalcopyrite depression in the presence of lime, both at high and moderate pH values, using fairly low concentrations of the lignosulfonates (10-25 mg/L). These reagents are not very effective at natural pH values at a high pH adjusted with KOH.
In contrast, the D-912 measurably depresses chalcopyrite flotation under all test conditions, at a sufficiently high concentration. It is also clear that its action is enhanced in the presence of lime, similarly to the other reagents. This observation is interesting since this lignosulfonate was the only calcium salt tested on chalcopyrite. The other reagents were sodium salts.
The depression level achieved by KOH at high pH is never as good as the depression level achieved in the presence of lime at high pH. This shows that the depression is not due to pH changes, but rather, due to the presence of the Ca2+ cations in the pulp. Generally, at natural pH, the reverse addition of lignosulfonate (i.e. the addition of lignosulfonate prior to the addition of the collector), results in better depression than the addition of xanthate followed by lignosulfonate.
4.1.2 Depression of Molybdenite
The molybdenite flotation tests began with a preliminary investigation to determine the effect of pH on the natural floatability of molybdenite. Three different pH reagents were used, as shown below in Figure 4-7.
-38- u_1—1—i—1—i—1—i—1—i—•—i—1—i—1—r 5 6 7 8 9 10 11 12 pH
Figure 4-7: Flotation results of molybdenite in 0.001 M KN03. Various pH values were achieved
using lime (CaO), KOH, and soda ash (Na2C03), to determine the optimum pH for testing lignosulfonates.
The pH investigation yielded two important conclusions:
i) The highest pH for good flotation was 8; at higher values than 8, the pH itself
depressed the flotation of molybdenite.
ii) Lime depresses molybdenite much more so than the other pH reagents, which
is consistent with the postulate put forward by Chander and Fuerstenau
(1972). Soda ash (Na2C03) initially improves flotation, as the carbonates in
the soda ash probably bind any trace amounts of Ca2+ ion on the surface of
molybdenite. This assumption is reasonable, since the molybdenite used in
this investigation came from a carbonate-bearing rock. Eventually, the effect
of increasing the pH dominates and the floatability of molybdenite declines.
Based upon these factors, molybdenite flotation tests were carried out at a natural pH, and at pH 8 using different pH modifiers. The results of these tests are shown in
Figures 4-8 to 4-13. Note that the abscissa scale (lignosulfonate concentration) shows a
-39- maximum of 50 mg/L, and the ordinate scale (flotation yield) has a maximum of 60% recovery. Typically, two tests using KOH were performed, one with a high dosage of lignosulfonate, and the other, a baseline test with no lignosulfonate.
1 1 1—1—I—1—I 1 1 ' T 0 10 20 30 40 50 Lignosulfonate Concentration [mg/L]
Figure 4-8: Flotation results of molybdenite in 0.001 M KN03j using the lignosulfonate D-619.
Figure 4-9: Flotation results of molybdenite in 0.001 M KN03, using the lignosulfonate D-648.
-40- 0 10 20 30. 40 50 Lignosulfonate Concentration [mg/L]
Figure 4-10: Flotation results of molybdenite in 0.001 M KN03) using the lignosulfonate D-701.
60 ' 1 ' 1 ' 1 1—-L- r——i w • D-748 pH 5.0-5.5 (natural) 2 " A D-748 pH 7.6-8.1 (CaO) £ V D-748 pH 7.8-8.1 (KOH)
a 40- • D-748 pH 7.8-8.3 (Na2C03)
°H—1 1—'—i 1—i •—i—1—r 0 10 20 30 40 50 Lignosulfonate Concentration [mg/L]
Figure 4-11: Flotation results of molybdenite in 0.001 M KNO3, using the lignosulfonate D-748.
-41 - 60- _L _L _L
• D-750 pH 5.1-5.8 (natural) A D-750 pH 7.9-8.2 (CaO) v D-750 pH 7.7-7.9 (KOH) a 40-1 O D-750 pH 7.9-8.5 (Na2C03) o
1o
a3 20H •8
n 1 1 1 1 1 r 0 10 . 20 30 40 50 Lignosulfonate Concentration [mg/L]
Figure 4-12: Flotation results of molybdenite in 0.001 M KNO3, using the lignosulfonate D-750.
60- J. _L • D-912 pH 5.1-5.3 (natural) A D-912 pH 8.0-8.2 (CaO) 2 v D-912 pH 7.7-8.4 (KOH) O D-912 pH 7.9-8.3 (Na2C€>3) a 40 H in o
a3 20H X)
0 10 20 30 40 50 Lignosulfonate Concentration [mg/L]
Figure 4-13: Flotation results of molybdenite in 0.001 M KN03> using the lignosulfonate D-912.
As seen in the case of D-619 and D-648, the two poorest performing lignosulfonates for chalcopyrite, low concentrations of lignosulfonate are sufficient to depress molybdenite, regardless of the pH modifier used. The D-648 exhibits an initial increase in flotation in the presence of soda ash; this could be due to binding of any traces-
-42- of calcium on the molybdenite by carbonate ions. Eventually, at high enough concentrations of the lignosulfonate, depression is achieved.
The D-748 at high enough concentrations is able to sufficiently depress molybdenite. However, this lignosulfonate performs relatively poorly under a natural pH.
The D-701, the D-750 and the D-912 induce very strong depression of molybdenite at very low concentrations (5 - 10 mg/L) and under all conditions.
A series of additional flotation tests were carried out to show the effect of induced hydrophobicity of molybdenite on the depressing action of lignosulfonates. The tests were carried out in the presence of 10 mg/L dodecane, used as an oily collector in the form of an aqueous emulsion (see the experimental section for details on preparation).
The concentration of lignosulfonates in all the tests was 50 mg/L to ensure overdosing of the reagents. The results of these tests are shown in Figure 4-14.
2 13 e _o Conditioning • First lignosulfonate, then dodecane -*-» O A First dodecane, then lignosulfonate E — — Dodecane only No dodecane, no lignosulfonate T3
D-619 D-648 D-701 D-748 D-750 D-912 Lignosulfonate type
Figure 4-14: Dodecane and lignosulfonate flotation tests, carried out in 0.001 M KNO3. The lignosulfonates concentration was held constant at 50 mg/L. The dodecane emulsion used in these tests yielded a final concentration of 10 mg/L.
-43 - When oil is added to molybdenite, the floatability of the mineral reaches very high levels (dashed line). The addition of dodecane doubles the recovery of molybdenite, as shown by the dashed and solid lines in Figure 4-14. Furthermore, if dodecane is introduced ahead of the lignosulfonate, the depression of the mineral is quite poor.
Alternatively, if the mineral is conditioned with lignosulfonate first followed by dodecane, the depression is excellent.
4.2 Adsorption Tests
4.2.1 Adsorption on Chalcopyrite
Chalcopyrite adsorption tests were carried out at a 'natural' equilibrium pH, and at an equilibrium pH of 11 using lime, KOH and soda ash. The results of these tests are shown below as Figures 4-15 to 4-20. The scale on the lignosulfonate concentration axis was kept constant for all the adsorption data for consistency.
3 | - • I i I i I i L • D-619 pH 5.4-5.8 (natural) A D-619 pH 11.0-11.1 (GaO) • D-619 pH 11.2 (KOH) • D-619 pH 10.7 (Na2C03)
20 40 60 80 100 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-15: Adsorption results of chalcopyrite in 0.001 M KCI, using the lignosulfonate D-619.
-44- Figure 4-16: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-648.
T3 i 1 -P s
T3 0 2H • D-701 pH 5.2-5.4 (natural) < A D-701 pH 10.9-11.1 (CaO) a cu>, .o o • D-701 pH 11.1 (KOH) o • D-701 pH 10:9 (Na2C03) o H a u HJ O
T 20 40 60 80 100 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-17: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-701.
-45- T3 .—. in <; O bo 2H
• D-748 pH 5.0-5.2 (natural) S Oh A D-748 pH 10.9-11.1 (CaO) 2-1 o • D-748 pH 11.3 (KOH) 1 1 l H • D-748 pH 10.8 (Na2C03) a U .SP a
~"l ' 1 * 1 ' r~ 20 40 60 80 100 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-18: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-748
0 20 40 60 80 100 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-19: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-750.
-46- 3
• D-912 pH 5.4 (natural) A D-912 pH 10.8-10.9 (CaO) • D-912 pH 11.3 (KOH) • D-912 pH 10.8 (Na2C03)
0 0 20 40 60 80 100 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-20: Adsorption results of chalcopyrite in 0.001 M KC1, using the lignosulfonate D-912.
All the sorbates except D-748 did not reach adsorption saturation within the tested concentration range, as demonstrated by the continuously increasing adsorption densities.
It is interesting to note that generally, there is no significant difference between the adsorption density of lignosulfonates at natural pH and pH 11 after lime addition.
This observation was unexpected since the flotation data indicated that the presence of calcium at high pH facilitates chalcopyrite-lignosulfonate interactions, and results in the depression of the mineral. Therefore, to explain the flotation data, the concentration of the xanthate collector was measured simultaneously with the concentration of lignosulfonates in solution, as described in section 3.2.2.1. This data can be seen in
Appendix IV.
The results show that under natural pH conditions, no xanthate can be detected in solution with lignosulfonate. However, at high pH, regardless of the pH modifier used, the xanthate collector appears in solution in equilibrium with the mineral, suggesting that
-47- desorption of a portion of the xanthate takes place. This in turn means that under high pH, the physically/electrostatically adsorbed xanthate (see the literature review section for the modes of adsorption of xanthates, page 8) gets removed from the mineral surface, but the surface remains sufficiently hydrophobic for good flotation.
As the adsorption and flotation data show, "chalcopyrite depression can be achieved only when lignosulfonates adsorb at high pH adjusted with lime. Control of pH with soda ash and KOH does not result in chalcopyrite depression, which correlates very well with low adsorption of lignosulfonates under these conditions. Low adsorption density of lignosulfonates coupled with the presence of just the chemically adsorbed xanthate on the mineral surface is insufficient to depress the mineral.
Under natural pH, the good flotation of the mineral despite the simultaneous high adsorption density of lignosulfonates can be explained by the presence of the physically/ electrostatically adsorbed xanthate on the mineral surface. In this case, the effect of high lignosulfonate adsorption density is dominated by the hydrophobicity induced by the combination of physically adsorbed and chemically adsorbed xanthate on the mineral surface. These conclusions are in excellent agreement with Leja's postulates (1982) regarding the importance of physically adsorbed xanthates.
In summary, high pH conditions displace the physically adsorbed xanthate from the chalcopyrite surface, but the depression of the mineral is possible only when lignosulfonates adsorb on the chalcopyrite surface, which in turn only takes place in the presence of polyvalent ions, such as calcium (from lime).
It should be remembered that sulfide surfaces are highly reactive under normal conditions, and a variety of oxidation products can be found both on the surface and in
-48- solution. The same cationic metal species involved in the adsorption of anionic xanthate can also interact with anionic lignosulfonates. For example, cationic copper- and iron- hydroxy species could function as activating sites for lignosulfonate adsorption in essentially the same way as calcium-hydroxy species in the presence of lime, which would explain why the adsorption density of lignosulfonates is practically the same at natural pH and at pH 11 using lime. It should also be remembered that copper ions may form water-soluble anionic copper-hydroxy species at high pH, which should not function as 'activators' for the adsorption of anionic lignosulfonates. It is also plausible that all the activating cations in solution are precipitated by carbonate ions from soda ash.
The role of electrostatic forces should also be considered. Adjusting pH with soda ash and KOH renders the chalcopyrite surface negatively charged, and does not produce any activating sites/species for lignosulfonate adsorption. An electro-acoustic test of the surface charge of chalcopyrite shown in Appendix V confirms the above observations regarding the sign of the mineral surface charge in the presence of Ca2+ and K+/Na+ ions.
This surface charge reversal observed at high pH allows the anionic lignosulfonates to develop a greater affinity for the chalcopyrite surface. Interestingly, the chalcopyrite surface is positively charged in the natural pH range from 5 to 7.
Overall, the adsorption data show that strong electrostatic repulsion between the negatively charged chalcopyrite surface and anionic lignosulfonates prevents the poly- electrolytes from interacting with the mineral. This aspect will be discussed in greater detail after the molybdenite adsorption tests are presented.
-49- 4.2.2 Adsorption on Molybdenite
Molybdenite adsorption tests were carried out at a 'natural' equilibrium pH, and at an equilibrium pH of 11 using lime, KOH and soda ash. The results of these tests are shown below as Figures 4-21 to 4-26.
-a .—i S-l <£ J D-619 pH 4.2-4.4 (natural) O bfi CO D-619 pH 11.2-11.3 (CaO) < " 0.6- D-619 pH 11.3 (KOH) D-619 pH 11.2 (Na2C03) * s Sag 0.4-
CO O
.SP fl 02-
-i—1 1—1—1—1— 20 40 60 80 100 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-21: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-619.
_L _L • D-648 pH 4.3-4.5 (natural) A D-648 pH 11.2-11.3 (CaO) J f 0.8- • D-648 pH 11.3 (KOH) o ao • D-648 pHl 1.2 (Na2C03) CO £H -a C < ^ 0.6-
•58 °-2H
~~i 1 1 1 1 1 r*~ 20 40 60 80 100 120 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-22: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-648.
-50- J i I I I I • D-701 pH 4.2-4.5 (natural)
Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-23: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-701.
_L _L _L • D-748 pH 4.3 (natural) A D-748 pH 11.0-11.1 (CaO) i 1 0.8-^ • D-748 pH 11.3 (KOH) •s « o "5b • D-748 pH 11.3 (Na2C03) -aos e < " 0.6 •
"I 1 1 1 1 1 r 20 40 60 80 100 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-24: Adsorption results of molybdenite in 0.001 M KC1, using the lignosulfonate D-748.
-51 - • D-750 pH 4.3-4.6 (natural) A D-750 pH 11.0-11.1 (CaO) • D-750 pH 11.3 (KOH) • D-750 pH 11.2 (Na2C03)
"1 1 1 1 1 ' r 100 20 40 60 80 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-25: Adsorption results of molybdenite in 0.001 M KCI, using the lignosulfonate D-750.
_L • D-912 pH 4.3-4.5 (natural) A D-912 pH 11.1-11.3 (CaO) |^ 0.8- • D-912 pH 11.3 (KOH) o ~St> • D-912 pH 11.2 (Na2C03) -O « < " 0.6 •
3^ 0.4-
•SP O 0 2-
"1 1 1 1 1 1 r~ 20 40 60 80 100 Equilibrium Lignosulfonate Concentration [mg/L]
Figure 4-26: Adsorption results of molybdenite in 0.001 M KCI, using the lignosulfonate D-912.
It should be noted that the adsorption density achieved on the surface of molybdenite is not as high as the densities achieved on the surface of chalcopyrite.
However, all the individual lignosulfonates show the same adsorption pattern. The
-52- isotherm using lime is much steeper than the isotherm obtained under natural conditions.
D-750 has the steepest isotherm among the tested reagents at pH 11 using lime; D619, D-
748 and D-912 have quite similar isotherms, and the lowest adsorption at pH 11 with lime is exhibited by D-648. Generally, the adsorption isotherms indicate that all the lignosulfonates exhibit a strong affinity towards molybdenite at high pH using lime.
The adsorption data obtained in the presence of KOH and soda ash generally show a lower lignosulfonate adsorption as compared to the natural or pH 11 using lime.
The high lignosulfonate adsorption can again be attributed to the presence of calcium species at high pH and not just to pH alone, similarly to the results for chalcopyrite.
According to Chander and Fuerstenau, (1972), the presence of calcium in solution at high pH can reverse the surface charge on molybdenite from negative to positive. This effect is known to result from the specific adsorption of CaOH+ ions on the mineral surface and this type of charge reversal due to calcium adsorption has been reported for several other minerals (Fuerstenau and Palmer, 1976 Hanna and Somasundaran, 1976,
Healy and Moignard, 1976). The other pH modifiers (KOH and soda ash) render the mineral surface more negatively charged (Chander and Fuerstenau, 1972). These observations indicate that lignosulfonate adsorption on molybdenite is controlled by electrostatic interactions with the mineral surface, even though the mineral is known to be naturally hydrophobic. In addition, the presence of polyvalent cations in solution should partly neutralize the anionic groups on lignosulfonates, which would further reduce the electrostatic repulsion between the reagent and the surface, and thus lead to higher adsorption density.
-53- Although the exact structure of lignosulfonates has not been satisfactorily elucidated, it is known that the highly anionic character of the macromolecules originates from the presence of phenolic, carboxylic and sulfonic groups. Phenolic groups are only
weakly acidic with the corresponding pKa values (pH of 50% dissociation) ranging from
pH 9 to pH 10. Carboxylic groups are characterized by dissociation constants, Ka, in the
4 5 range 10" -10- , which gives pKa values of about 4-5. In contrast, sulfonic groups are strongly acidic, fully dissociated over the entire pH range (Morrison and Boyd, 1966). In other words, the overall degree of anionicity of lignosulfonates should change with pH.
The molecules are highly negatively charged at high pH, when all the acidic groups are fully ionized, and the net negative charge decreases as the pH becomes more and more acidic. At pH 4, only sulfonic groups remain completely dissociated. Carboxylic and phenolic groups are also known to strongly interact with polyvalent ions (e.g., Ca2+) frequently producing water insoluble complexes (Morrison and Boyd, 1966) which should also affect the acidity of the organic molecules. Such observations also indicate that the affinity of the organic polyelectrolytes towards metallic sites on mineral surfaces is very high.
Therefore, it is easy to imagine that at high pH, when the surface of a mineral is highly negatively charged and lignosulfonates are at the peak of their anionicity, electrostatic repulsion between the mineral and the anionic molecules will be the strongest, unless the surface contains metallic sites which would facilitate chemical adsorption of lignosulfonates. As the adsorption data show, this is the case when the pH is adjusted with lime (the presence of Ca) for both chalcopyrite and molybdenite, or when the chalcopyrite surface still contains oxidation products (metallic species) at neutral/low
-54- pH (see also Appendix 5). In addition, the strength of this repulsive interaction should diminish as the pH decreases, which should also enhance the adsorption of lignosulfonates.
Even though the adsorption of lignosulfonates on molybdenite is not very high at natural pH, they are still capable of rendering the mineral hydrophilic. As seen in Figure
4-14, the presence of lignosulfonates on the molybdenite surface prevents any attachment of hydrophobic oil droplets to the mineral surface. However, once the surface is rendered strongly hydrophobic by the addition of oil, lignosulfonates do not seem to interact with such surfaces so strongly. Based on Figure 4-14, it appears that the D-701 and D-912 reagents show the highest affinity towards hydrophobic surfaces.
Since hydrophobic interactions appear to be weak in the case of lignosulfonate- molybdenite systems, hydrogen bonding is the most likely adsorption mechanism on molybdenite at neutral and low pH values.
4.3 Size Exclusion Chromatography
4.3.1. Chalcopyrite Size Exclusion Chromatography Tests
Chromatography is a sorpitive separation process, where a mixture of solutes are introduced at the inlet of a column containing a stationary phase, and separated over the column length by the action of an elution solvent that is continuously fed to the column during the separation (Harrison et al., 2003). Size exclusion chromatography (SEC) separates solutes based on their size by passing them through a gel-based resin in a column. This polymer gel is inactive, so there is no binding between the solutes and the gel. Instead, molecules larger than the largest pores in the gel cannot enter the gel, and thus are eluted out first. Smaller molecules enter the gel to varying degrees, based upon their shape and size; they are thus retarded on their passage through the gel (Harrison et
-55- al., 2003). Generally, the high molecular weight fractions elute out first, gradually followed by lower and lower molecular weights.
The SEC plots, shown in Appendix III, give full molecular weight distribution as a function of time, and each molecular weight fraction can be identified from such plots by the presence or absence of a characteristic peak at a given elution time. Hence, by comparing the molecular weight distribution of a sample after adsorption with that of a standard, the molecular weight distribution of the adsorbed component can be deduced.
In the case of adsorption of chalcopyrite, all the results show similar trends. In all cases, the high molecular weight fraction preferentially adsorbs on the mineral.
Generally, the samples obtained under natural pH and pH 11 adjusted with lime show a narrow and low molecular weight fraction left in solution, indicating that the amount adsorbed was relatively high, and that the high molecular weight fraction preferentially adsorbed on the mineral. In contrast, samples obtained at high pH using KOH or soda ash show a much broader distribution, even with a high molecular weight fraction left in solution, suggesting that the adsorption of the reagents was low under those conditions.
These trends agree very well with the direct adsorption measurements.
It should be borne in mind that any quantitative comparison of the adsorption data with the SEC results is not entirely accurate, because different molecular fractions of lignosulfonates are known to have different UV-absorption coefficients. The calibration curves, shown in Appendix II, therefore reflect the average UV-absorption characteristics of the samples, and not those of the individual molecular weight fractions.
In the case of molybdenite, the same trends can be observed. Again, adsorption in the presence of lime is much higher than in the presence of soda ash and KOH. In the
-56- case of lime additions only the lowest molecular weight fractions remain in solution, while for KOH and soda ash, a much broader molecular weight distribution can be seen.
Comparing the area under the molecular weight peaks, it appears that the adsorption density is lowest in the presence of KOH and soda ash, and very high in the presence of lime.
-57- 5.0 Conclusions and Recommendations
The depression of chalcopyrite flotation by lignosulfonates requires the following conditions:
i) desorption of the physically adsorbed portion of the xanthate collector. This
can be achieved by raising the pH of the pulp using any pH modifier.
ii) simultaneous adsorption of lignosulfonates on the mineral surface. This can be
achieved by providing polyvalent cations in solution to 'activate' the mineral
surface for lignosulfonate adsorption.
From this point of view, calcium salts of lignosulfonates are better depressants than sodium salts. Based on all the results, the most powerful lignosulfonate depressant should be a calcium salt, characterized by high molecular weight and a low degree of anionicity. These three properties must be carefully balanced since 'very powerful' depressants are also the least selective.
The flotation results for molybdenite and chalcopyrite indicate that lignosulfonates can be used as selective depressants at neutral pH. Under these conditions, molybdenite will be depressed while the flotation of. chalcopyrite should not be affected. The use of lime as a pH modifier is not recommended because of the activating role of calcium for lignosulfonate adsorption. In the presence of Ca2+ introduced by lime, the selectivity of depression will drastically be reduced.
Although the exact adsorption mechanism of lignosulfonates on chalcopyrite and molybdenite cannot be identified at this point, the adsorption data show that the adsorption process at high pH is controlled by electrostatic forces. The adsorption data generally illustrates the significance of metallic sites on mineral surfaces in enhancing
-58- lignosulfonate adsorption. In the case of molybdenite, hydrogen bonding should also be considered with only a minor contribution, if any, from hydrophobic interactions.
Although this study is of fundamental nature, the results point towards the following processing option for the selective separation of molybdenite from chalcopyrite by froth flotation:
i) A rougher bulk flotation stage in which only xanthates are used as collectors
to float chalcopyrite. Because of the natural floatability of molybdenite it is
reasonable to assume that significant amounts of molybdenite will also report
to the bulk concentrate. This stage can be performed at a relatively high pH
(to ensure the depression of pyrite) provided that a pH modifier other than
lime, e.g. soda ash, is used for pH control.
ii) A cleaning stage with the use of lignosulfonates. In this case, the floatability
of the already hydrophobic chalcopyrite will not be reduced, while any
molybdenite present in the bulk concentrate (rougher concentrate) will now be
depressed by the addition of lignosulfonates. The proposed pH of this stage is
the natural system pH, i.e. the pH carried over from the rougher bulk flotation
stage.
iii) A scavenger flotation stage with the use of an oily collector. The tailings
from the bulk flotation stage (1) will contain some amount of molybdenite
which should be easily floated after the addition of an oil.
Depending on the performance of the scavenger and cleaner flotation stages, the cleaner tailings and scavenger concentrate can be combined into a molybdenite concentrate. Figure 5-1 schematically shows the proposed flowsheet.
-59- XANTHATES ONLY, OILY COLLECTOR, pH>9.5 (SODA ASH) pH>9.5 CRUSHING GRINDING 1 CLASSIFICATION ROUGHER SCAVENGER :ore) > FLOTATION FLOTATION
LIGNOSULFONATE \ Molybdenite CLEANER 'Molybdenite FLOTATION
Chalcopyrite Molybdenite Concentrate (?)
Figure 5-1: Proposed flowsheet outlining the selective separation of molybdenite from chalcopyrite by froth flotation whilst using lignosulfonates.
From the mass balance/flow point of view, the proposed strategy is in contrast to the usual method of treating complex ores in which one of the valuable components is present in a very small quantity compared to the major component. In the case of copper- molybdenum ores, the higher proportion of chalcopyrite compared to that of molybdenite, usually dictates the depression of chalcopyrite rather than molybdenite, as discussed in the literature review section. When a large amount of the major mineral
(chalcopyrite in this case) reports to the concentrate, it usually enhances the entrainment of the less dominant mineral (e.g., molybdenite) regardless of the natural or induced hydrophilicity of the latter. However, since it is proposed to use lignosulfonates in a cleaning stage, it should also be remembered that the amount of solids treated in cleaner
-60- flotation is only a fraction of the overall plant feed so pulp dilution, and perhaps the use of flotation columns, could minimize entrainment effects.
For future research, testing of real ores is strongly recommended. Although this thesis focuses on two sulfide minerals, the adsorption characteristics of lignosulfonates on various tailings minerals (quartz, clays, carbonates) should also be investigated.
Due to the complexity of lignosulfonate molecules, the different modes of lignosulfonate adsorption, i.e., chemisorption, electrostatic/physical adsorption, and hydrophobic . interactions should be more clearly delineated using model materials/minerals, e.g. oxides, solid alkanes.
-61 - 6.0 References
Aitchison, L. A History of Metals, Vol. 1 and 2, MacDonald & Evans Ltd., London (1960).
Arbiter, N. (ed.) "Flotation, Section 5" in Weiss, N.L. (ed.) SME Mineral Processing Handbook, Vol. 1, Society of Mining Engineers, New York (1985).
Arsentiev, V.A and Leja, J. Problems in potash flotation common to ores in Canada and the Soviet Union. CIM Bulletin 70(779): 154-158 (1977).
Bassarear, J.H., Pilz, C. and Vincent, J.D. (eds.) "Section 14B - Typical Large Sulfide Flotation Mills," in Weiss, N.L. (ed.) SME Mineral Processing Handbook, Vol 2. Society of Mining Engineers, New York (1985).
Brunauer, S., Emmett, P. H., and Teller, E. Adsorption of gases in multi- molecular layers. Journal of the American Chemistry Society, 60:309-319 (1938).
Castro, S. H., and Bobadilla, C. The depressant effect of some inorganic ions on the flotation of molybdenite, in, Laskowski, J. S. and Poling, G.W. (eds.), Processing of Hydrophobic Mineral and Fine Coal: Proceedings of the First UBC-McGill Bi-Annual International Symposium on Fundamentals of Mineral Processing, Vancouver, British Columbia - 34th Annual Conference of Metallurgists of CIM, pp 95-103 (1995).
Castro, S. H., and Laskowski, J. S. Molybdenite depression by shear degraded polyacrylamide solutions, in, Laskowski, J. S. (ed.), Particle Size Enlargement in Mineral Processing: Proceedings of the Fifth UBC-McGill Bi-Annual International Symposium r/i on Fundamentals of Mineral Processing, Hamilton, Ontario - 43 Annual Conference of Metallurgists of CIM, pp 169 - 178 (2004) Chander, S., and Fuerstenau, D. W. On the natural floatability of molybdenite, Transactions of the American Institute of Mining, Metallurgical and Petroleum Engineers Inc. American Institute of Mining, Metallurgical and Petroleum Engineers, New York, Vol. 252: 62-68 (1972)
Day, Arnold (ed.) Mining Chemicals Handbook, Cytec Industries Limited (2002).
Forssberg, K. S. E. (ed.): Flotation of Sulfide Minerals, Elsevier Science Publication, New York (1985).
Fredheim, G. E., Braaten, S. M. and Christensen, B. E. Comparison of molecular weight and molecular weight distributions of softwood and hardwood lignosulfonates. Journal of Wood Chemistry and Technology, Vol 23 (2): 197 - 215 (2003).
Fredheim, G. E., Braaten, S. M., and Christensen, B.E. Molecular weight determination of lignosulfonates by size-exclusion chromatography and multi-angle laser light scattering, Journal of Chromatography A, 942: 191-199 (2002)
-62- Fuerstenau, D.W., Pradip and Khan, L.A., Final Progress Report. Submitted to MolyCorp USA (1980).
Fuerstenau, M.C., and Palmer, B.R. "Chapter 7 - Anionic Flotation of Oxides and Silicates" in Fuerstenau, M. C. (ed.) Flotation, American Institute of Mining, Metallurgical and Petroleum Engineers, New York, Vol 1 (1976).
Gargulak, J. D. and Lebo, S.E. in: Glasser, W.G., Northey, R.A., and Schultz, T.P. (eds.): Lignin: Historical, Biological, and Materials Perspectives. ACS Symposium Series 742: 301 (1999).
Goheen, D.W. in: Sarkanen, K. V. and Ludwig, C. H. (eds.): Lignin, Occurrence, Formation, Structure, Wiley-Interscience, New York (1971).
Grigg, R. B. and Bai, B. Calcium lignosulfonate adsorption and desorption on Berea sandstone, Journal of Colloid and Interface Science 279: 36-45 (2004).
Harrison, R. G., Todd, P., Rudge, S. R. and Petrides, D. P., Bioseparations Science and Engineering, Oxford University Press, New York (2003).
Hanna, H. S. and Somasundaran, P., "Chapter 8: Flotation of Salt-type Minerals" in Fuerstenau, M. C. (ed.) Flotation, American Institute of Mining, Metallurgical and Petroleum Engineers, New York, Vol 1 (1976).
Healy, T. W. and Moignard, M. S., "Chapter 9: A Review of Electrokinetic Studies of Metal Sulphides" in Fuerstenau, M. C. (ed.) Flotation, American Institute of Mining, Metallurgical and Petroleum Engineers, New York, Vol 1 (1976).
Kelebek, S., Yoruk, S. and Smith, G.W. Wetting behaviour of molybdenite and talc in lignosulfonate/MIBC solutions and their separation by flotation, Separation Science and Technology, 36(2): 145-157 (2001).
Lebo Jr., S. E., Gargulak, J. D., and McNally, T.J. "Lignin," in Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley and Sons. Posted online Dec 20 (2001). http://www.rnm.interscience.wiley.com/kirk/articles/lignlin.a01/sect5-fs.html
Leja, J. Surface Chemistry of Froth Flotation, Plenum Press, New York (1982).
Lossin, A. "Copper," in Ullmann's Encyclopedia of Industrial Chemistry, Wiley- VCH Verlag GmbH & Company. Posted online January 15 (2001). http://www.mrw.interscience.wiley.com/ueic/articles/a07_471/sect5-fs.html
Lu, S., and Sun, K. Developments of phosphate flotation reagents in China, in: Zhang, P., Elshall, H., and Wiegel, R., (eds.), Beneficiation of Phosphates - Advances in Research and Practice. SME Inc., Littleton (1999).
Ma, X., and Pawlik, M., The effect of lignosulfonates on the floatability of talc, submitted for publication in International Journal of Mineral Processing (2005).
-63 - Mathieu, G.I. and Bruce, R.W. Getting the talc out of molybdenite ores, Canadian Mining Journal 95 (6): 75 (1974).
Morrison, R. T. and Boyd, R. N. Organic Chemistry - Second Edition, Allyn and Bacon Inc, Boston (1966).
Nimz, H. H. "Lignin," in Ullmann's Encyclopedia of Industrial Chemistry, Wiley- VCH Verlag GmbH & Company. Posted online July 31 (2003). http ://www. mrw. interscience. wiley. com/ueic/articles/a 15_305/sect3 -fs .html
Pomianowski, A., and Pawlikowska-Czubak, J. Electrical and surface characteristics of the mercury/solution/air system containing xanthates and dodecyltrimethylammonium bromide: Part I, Industrial Chemistry, 46 (8), 481-485 (1967).
Pradip and Fuerstenau, D.W. The role of inorganic and organic reagents in the flotation separation of rare-earth ores, International Journal of Mineral Processing, 32:1- 22 (1991).
Ratinac, K.R., Standard, O.C. and Bryant, P.J. Lignosulfonate adsorption on and stabilization of lead zirconate titanate in aqueous suspension, Journal of Colloid and Interface Science 273: 442-454 (2004).
Sadowski, Z. Minerals Engineering 5: 421-428 (1992).
Sadowski, Z. Selective spherical agglomeration of fine salt-type mineral particles in aqueous solution, Colloids and Surfaces A: Physicochemical and Engineering Aspects 96: 277-282 (1995).
Sadowski, Z., and Smith, R.W. The stability of semi soluble salt type mineral suspensions in oleate solutions. Journal of Dispersion Sciences and Technology, 10: 715- 738 (1989).
Schneider, H. G. and Mikule, J. Recovery of sugar from beet molasses by the P. and L. exclusion process. International Sugar Journal 11 (921): 259-264 (1975).
Sebenik, R. F., Burkin, A. R., Dorfler, R. R., Laferty, J. M., Leichtfried, G., Meyer-Grunow, H., Mitchell, P. C. H., Vukasovich, M. S., Church, D. A., Van Riper, G. G., Gilliland, J. C, Thielke, S. A. "Molybdenum and Molybdenum Compounds," in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag GmbH &' Company. Posted online June 15 (2000). http://www.mrw.interscience.wiley.com/ueic/articles/al6_655/sect7-fs.html
Singh, B.P. Wetting Mechanism in the Flotation Separation of Plastics, Filtration & Separation, 35: 525-527 (1998).
Tylecote, R.F. History of Metallurgy, The Institute of Metals, London (1976).
-64- Wie, J. M. and Fuerstenau, D. W. The effect of dextrin on surface properties and the flotation of molybdenite, International Journal of Mineral Processing, 1: 17-32 (1974).
Wyckoff, R.W.G. Crystal Structures, Interscience Publication, Supplement V, Vol 1.
-65- Appendix I: Size Distribution Data
The size distributions of both adsorption grade chalcopyrite and adsorption grade molybdenite are shown below as Figures 1-1 and 1-2, respectively.
0 I 1—l I I I I 11 i—i—i i i i i 11 1 1—i i i i i 11 1 1—r 0.1 1 10 100 Particle Size [fim] Figure 1-2: Size distribution for adsorption grade molybdenite.
-66- Appendix II: Absorbance Scans and Calibration Curves
The absorbance scans shown below as Figures II-1 to II-5 were carried out to determine the lignosulfonates' common intersection wavelength, where the absorbance was independent of the experimental conditions. The scans for potassium ethyl xanthate and D-912 were discussed previously, on pages 26 and 27, respectively.
3
D-619
to CJ G •e o. CO
pH~7.5 (natural)
I r I 200 280 320 400 Wavelength [nm]
Figure II-l: Absorbance spectra of lignosulfonate D-619, at a concentration of 50 mg/L. The common intersection wavelength is read at 233 nm, whereas the lignosulfonate contribution to the xanthate absorbance is the average of the readings at 302 nm.
-67- 200 240 280 320 360 400 440 Wavelength [nm] Figure II-2: Absorbance spectra of lignosulfonate D-648, at a concentration of 50 mg/L. The common intersection wavelength is read at 236 nm, whereas the lignosulfonate contribution to the xanthate absorbance is the average of the readings at 302 nm.
200 240 280 320 360 400 Wavelength [nm] Figure II-3: Absorbance spectra of lignosulfonate D-701, at a concentration of 50 mg/L. The common intersection wavelength is read at 236 nm, whereas the lignosulfonate contribution to the xanthate absorbance is the average of the readings at 302 nm.
-68- D-748
O a 5 2
pH i 7.5 "nm (natural) 302! nm 0 ~i 1 i ^ i • n~ 200 240 280 320 360 400 Wavelength [nm] Figure II-4: Absorbance spectra of lignosulfonate D-748, at a concentration of 50 mg/L. The common intersection wavelength is read at 229 nm, whereas the lignosulfonate contribution to the xanthate absorbance is the average of the readings at 302 nm. _L
D-750
a*
o pH~ 11.0 (CaO)
0 200 240 280 320 360 400 Wavelength [nm] Figure II-5: Absorbance spectra of lignosulfonate D-750, at a concentration of 50 mg/L. The common intersection wavelength is read at 308 nm, whereas the lignosulfonate contribution to the xanthate absorbance is the average of the readings at 302 nm.
-69- Figures II-6. to 11-13 show the calibration curves constructed at the common intersection wavelengths for the lignosulfonates, as well as the xanthate calibration curves (taken at several wavelengths). The slopes obtained from these curves were used to simultaneously determine the xanthate and lignosulfonate concentrations found in equilibrium with the mineral after the completion of a given absorption test, as described on pages 28 - 29.
0 50 100 Lignosulfonate Concentration [mg/L] Figure II-6: Calibration curve for D-619. The best fit line passing through the origin, as well as the associated R2 value is as shown. This curve was generated at a wavelength of 233 nm.
0 50 100 150 200 Lignosulfonate Concentration [mg/L] Figure II-7: Calibration curve for D-648. The best fit line passing through the origin, as well as the associated R2 value is as shown. This curve was generated at a wavelength of 236 nm.
-70- 2
0^ , , , 1 , , ! , 1 , , r—n h 0 50 100 150 Lignosulfonate Concentration [mg/L] Figure II-8: Calibration curve for D-701. The best fit line passing through the origin, as well as the associated R2 value is as shown. This curve was generated at a wavelength of 236 nm.
3
°H— • > 1-^—1 -—^ ' ' h 0 50 100 Lignosulfonate Concentration [mg/L] Figure II-9: Calibration curve for D-748. The best fit line passing through the origin, as well as the associated R2 value is as shown. This curve was generated at a wavelength of 229 nm.
-71 - 3 —| I I I I I I I I 1 I I I L
H ' ' ' ' 1 ' ' ' ' 1 ' r 0 50 100 150 Lignosulfonate Concentration [mg/L] Figure 11-10: Calibration curve for D-750. The best fit line passing through the origin, as well as the associated R2 value is as shown. This curve was generated at a wavelength of 308 nm.
-72- J i 1 302: Y = 0 10498 * X • 302 nm R-squared = 0.999986 + 229 nm 229: Y = 0 5 051379 *X 233nm e R-squared = 0.99999 236 nm 13 233: Y = 0 040716 * X 308 nm. > R-squared = 0.999987 03 236: Y = 0 029564 * X .o R-squared = 0.999988 03 308: Y = 0 08208 * X > R-squared = 0.999997 03 i 1 r 10 15 Xanthate Concentration [mg/L] Figure 11-12: Calibration curves for potassium ethyl xanthate. These curves were taken at different wavelengths, in order to be able to calculate the xanthate contribution at the given wavelengths when simultaneously calculating a sample's xanthate and lignosulfonate concentration. The equations given on the figure indicate the best fit lines passing through the origin, as well as the associated R2 value. -73 - Appendix III: Size Exclusion Chromatography Plots The plots below show the results of the size exclusion chromatography tests. These were carried out by Borregaard LignoTech, per the procedure alluded to on page 34. The principles of size exclusion chromatography were briefly touched upon on page 55. Figures III-1 through 111-30 show the standard elutions, as well as the results of the chalcopyrite tests. In the case of chalcopyrite, the initial lignosulfonate concentration was held constant at 75 mg/L. Figures 111-31 to 111-78 show the results of the molybdenite tests; the initial lignosulfonate concentrations for these tests are as indicated in the captions. Pk. Ret Component Concentration Height Area Bl. SDelta Num Time Name . . Code 1 12.92 0 .000 12769 ':5853'21 - 2- 2 14.92 0.000 64507 11919420 2 3 .17.,33' ;:V::..;.-:-;.:- o.ooo 156034 17994315 2 4, -•18.92:V •• 0.000 249288 27901691 2 5 . 26.58 ::V,- 57.3':-: ;38580J V i Totals''::::-:/;';. 0,000; 483171 • 58439327; '•- ' D-619 Sample 0.4 . AU 0 5 10 15 20 25 30 Figure III-l: D-619 standard elution. -74- ,+**,*'*•*.* **'**'*.**,* *+-* + * ^ ;''. All Peaks• • •*>.*y**'*l**^#***?**^**f •pfcVRet Component:- . Concerttratioh' .'Height; .'Area' • Bl %'Delta ••:Code • v :\. Num'; ./' ./Time Name :,:;..'.:> 0.000: 1295 ; : 2S9S& :; : : •v:: 2< :i^ :-a3:;'^,:%--,i.:.v-:' •Ov.'0'Op'-:. 3373, '•28660?;:: ; Tdta-1 s 0.000 3668: '"'315595/ D-619, after adsorption on chalcopyrite pH5.25 (natural) 0.10; 0.08 0.06 0.04 0.02 0.00 AU -0 02 -0.04 -0 06 -0.08 -0.10 10 15 20 25 : 30: Minutes Figure III-2: D-619, after adsorption on chalcopyrite at a natural pH of 5.3. Concentration:: •Height:- Area/. Bl •. % Dei fca'-.- ttuiav' ^Tlme/NameV:: • •:. :; :••:• :-:':Cbde ;;':. ' 18.00 0.000 98 3708: 19^75';; 0.000 : 361422: 0.000 5033 160087: rot.al-s- /0.;.000; ;• 10097/ •' 5252:i7;. D-619, after adsorption on Chalcopyrite 0.10 pH 10.9 (CaO) 0 08 0.06 0.04 0 02 0.00 AU -0.02 -0.04 -0.06 -0,08 -0.10 10 15 20 25 30 •: • Minutes: ••':,'.•:•*.• Figure III-3: D-619, after adsorption on chalcopyrite at pH 10.9 using CaO -75- *************************** peak Report: All Peaks **+************************* Pk. Ret Component Concentration Height Area Bl. %Delta Hum Time Name Code 1 16.00 ' 0.000 •2151 209366 • 2 2 17.00 0.000 818 59177 2 3 17.92 . ' 0.000- 584 32707 2 A 19.83 0.000 6094 606513 2 5 21.25 o.ono , 5047 163459 '."> Totals' 0.000 14694 1071222 D-619, after adsorption on chalcopyrite 0.10 pHll(KOH) 0 08 006 0.04 O O CM S JQ to f- r- <- ?J 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 10 15 20 25 30 Figure III-4: D-619, after adsorption on chalcopyrite at pH 11.0 using KOH. % *********** ***:**.****** * * ***:• peak. - Report -All •:• Peaks X*'*'-*^**-^*-^^^**^'*-*.*^**^-*****-^ Pk.:--:- Ret Component: • • - GdricSntratioriHeight'-: - . Are'a : BI;:--..%Deltas ,: : Num Time Name' ^';' '::.:::'/Gode.::•:-•::•:.: 1 15.CO 0.000 1578 281819 /::2' .2 17.33 0.000 4275 0^496032':: '•*:2: : -3 .19v08:'-,:v>V:.:-.V 0.000 7763 :: 84'2558-:'-- ZZ : ; : : : 0 ; 252519 4 21.25 ZZ-Z :--v Z ffife-ZZ! V:v,:' :'#i'f 9 °>:• £" :I;;;:;-^7?6;6V-,: ZM Totals 0.000 :::iyi8729:27:;'':::' D-619, after adsorption on chalcopyrite, pH 11.1 (soda ash) 0.10 0.08 0.06 0.04 0 02 0 00 AU -0 02 -0.04 -0.06 -0,08 -0.10 .•'10':: 15;; ZZ:m\ '25 i 30 : Minutes: ;': :. Figure III-5: D-619 after adsorption on chalcopyrite, at pH 11.1 using soda ash. -76- Peak Report: All Peaks *********************+*.*****' . Pk, Ret Component. Con cenfcfat i on : Height.:." : 'Area- "Bl. * Delta Nwrt .Time Name : • 'Code . ' 1 14.00- ... 0.000 15883 16870324 2 2 17.33 '.' 0.000 388295 43769702 2 3 19.00 0.000 600801 71577377 2 0,000 : K 'i00.4:979. 132217403/ -. :'.\ D-648 09 , 0.8 - 0.7 0.6 0.5 ! 0.4 : AU 0.3 02 0.1 ! 0.0 i -0.1 -T7T' 0 5 10 15. 20 '' 25. • 30 A- Minutes Figure III-6: D-648 standard elution. Peak: Report :• All' Peaks :'''**:.********.***'+***+.*..*.** Pk. : Ret:.. Component' /: 'Concentration Height Area Bl. %Delta . Mvurt Time Name Code 19.83 •>••;• 0.000 4713 280485 2 Totals. 0.000 4713 280485 D-648, after adsorption on chalcopyrite, 0.10 , pH 6.5 (natural) 0.08 : 0.06 ! 0 04 • 0.02 | 0.00 !- AU -0.02 -0.04 -0.06 -0.08 -0.10 0 10 15 20 25 30 Minutes Figure III-7: D-648, after adsorption on chalcopyrite at a natural pH of 6.5. -77- .*•* *'*•*'?* *****.*.•****:*.*•••*****• * * Peak Report: - All" Peaks- ************** *V*«*i+**#*ii#*'*' Pk". Ret Component 'Concentration.-. '..'Height,'-' Area; . Bl.,% Delta.;. Nina '•'.; Time Name . '-/Code: - 1 17.42 0.000 648 ; 71869 2 2 19.83 0.000 7344 '•'.531192.,' 2 3 21.25 0.000 4654 153359 2 Totals-' c-.ooe 12646 .75.6420.^ D-648, after adsorption on chalcopyrite 0.10 pH 11.0 (CaO) 0.08 0.06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 0 10 15 20 25 30 Minutes Figure HI-8: D-648, after adsorption on chalcopyrite at pH 11.0 using CaO. ****-*********•**************• E>ea k Repor t:: Al 1 Peak s * * * * * * * **;*•*•'* ********* *'*;*'*•' *;i *•'' : Pk. '., Ret Component Concentration ;. Height •• • Area Bl. Nura • • Time .Name/ Code. "'. 1- - 16.33 ,:•..•"•-v. 0.000-x'v •;>."i432-;'": ":::';' 91955: 2 2 16.92 0.000 893 ':/. 5075 5 2 3 17.92 :.:. o.ooo/.r 683 ,"'/ 369.95 . 2 /• 19.75 ' . 0.000:/ 8160 i '.••700038:: //. ,2;; 21,'. 1.7 v ';/': / • :-:";o..qoot,::-:-: /;• ./\34:01v V •'•I 10125- Totals . 0.000 .':':' .••14568/--; i :989868:' D-648, after adsorption on chalcopyrite pH 11.0 (KOH) 0.10 0.08 ! 0.06 1 0.04 i 0.02 1 0.00 AU -0.02 -0.04 -0.06 -0.08 -0:10 10 15 20 25 •3o; Minutes .. Figure III-9: D-648 after adsorption on chalcopyrite at pH 11.0 using KOH -78- ********************* Peak Report: All Peaks .*********+************.*.****•'* Pk.. Ret Component Concentration '. Height.-:-.':: Area-' Bl. fDelta Nura , .Time Name .-. Code./. .:'••.:' 1 15 25- . ' 0,000 : 759 13730.7 .; . 2 2 17 33 •:- 0.000 . 4285 '490304 2 3 ' 19 75 '-. 0.000 8797 937355 2 4. 21 25'. .. 0.000 . 5664 .' 178404 2 .-Totals. . • . • 0.000 ••' .'. 19506... /1743370- • D-648, after adsorption on chalcopyrite 0.10 pH 11.1 (soda ash) 0.08 0.06 '.• 0.04 0.02 0.00 AU •0.02 ! -0.04 -0.06 -0.08 ! -0.10 f~ 0 10 15 20 25 30 Minutes Figure 111-10: D-648, after adsorption on chalcopyrite at pH 11.1 using soda ash. : .'**-***r**************.*'*****<**. P'_-^'.:-DA_ 1. : .,;:^' ,-. ".,'•./,'•:•, .',-.';'-'• •• \ reaic Heport: All. Peaks,-**-?,* **************** ****** /Pk. . Ret Component: : : : Area;;' 01 .;,%Del:ta : :Kum Time Name Concentration:: Height:/, • ; . •:. /Code/:/'::';:/:;:/ /'/•': 12. 92 0.000 "'•:'• '7495 . 445294 2 14. 92 0.000 30794 7164412 2 17,33: 0.000 258466 32459321 2 19.42 0,000 :,'/'-:«13 07i;/ 54836240 : :;/>2/'.::: •IS, 83/ ; :; : /:p;000 // 863001 : : : : / :4.6;541523 ''::' 2/ Totals 0.000 ./'1972'82'6/-' •: 14 144 6.790' '':••'• D-701 1.8 1-6 ; 1.4 1.2 1.0 AU 0.8 0.6 0.4 0.2 0.0 0 10 15 20 25 30 Minutes : Figure III-ll: D-701 standard elution. -79- + ******+************.*****-* peajj Report: All- Peak's ***'****•**********•*.**«£+ Pk. Ret Component Concentration Height •, Area Bl... ,%DeltS/ •Nuni' • Time Name. •, Code"-v,--'-;= • •'.•••:"•'' 1 17.67 0.000 308 26372 2 19.83 0.000 7056 517773 Totals 0.000 7364 544145 D-701, after adsorption on chalcopyrite 0 10 pH 5.5 (natural) 0.08 i 0.06 0.04 i 0.02 ; 0.00 — AU -0.02 -0.04 , -0.06 -o.o8 ; -o.io L -p-r-^^..:p...^ r;...:.—Tr; 0 5 10 15 20 25 30 Minutes .. Figure 111-12: D-701 after adsorption on chalcopyrite at a natural pH of 5.5. *'**•*'**>*,***>•'*;******•****•**;'peak Report.; All Peaks. ***'*****•*-**.*.*>.****.**********";' Pk. Ret Component ::':'// Concentration - Height Area;'•'',.B'l:i; jsBeltja:/: : ; v : . Hum .Time Name:'- :: ' ' •;'Code: /.?..'";^;: '. .:••• 2 19.83 0.000 8095 522334 2 3 21.25 0.000 2912 103761 2 ; : : : ; : ...Totals ':":':••'•:"'\,'"''0.000 ••••.' . ::i 1008: •':.l- • • /': 626oM^• ; D-701, after adsorption on chalcopyrite, 0.10 pH 11.0 (CaO) 0.08 0.06 0.04 19.8 3 21.2 5 0.02 18.1 7 0.00 •.• ..:•'• ' '• '.•^-^v...-. '• • AU -0.02 -0 04 -0.06 -0.08 ••': •- • .: -.. : -0.10 —t-T"T- j.. i •, ;i • .5... i •- j , 5 - i . ! | ' k; •< . I • i !; . ! i i • ' • I . .1. -:. 0 5 10 15 20 25 30 Minutes -; Figure 111-13: D-701, after adsorption on chalcopyrite at pH 11.0 using CaO. -80- Area. Bl. '%Delta p'k'. Ret Component '•• 'Concentration .Height- Code - ' Mum- . Time-Name .165 '- 10208 17.92: 0.000 10079 789891 19.83 0.000: 4 377 164662 21.25 0.000 Totals 0.000: 14620 964760: D-701, after adsorption on chalcopyrite, pHll.l (KOH) 0.10 0 08 0.06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 10 15 20 25 30 Minutes Figure 111-14: D-701, after adsorption on chalcopyrite at pH 11.1 using KOH. A #<.+* * * * # * * » v »•> , *i * *-* + *•**.***-*.*.**** ***** * *>:*. -. Eea k Report:. ;ftli: .Peaks Area'vBl.-:.% Delta- Pk. Ret Component Concentration Height ";.'•::::: -'--ebdev - •":;"',- : ; Num' :' -:Time' Name 78 16.17 0 .000 ••-. .000 1114 160278 17.33 0 0 .000 10976 107962b 19.83: 183499 .000 ,;:: 5oi3::::.'. •.21.33- 0 : : ;. •1426419::;- rotals 0 .000 - 17l8Ci:.:. ' D-701 after adsorption on chalcopyrite, pH 11.1 (soda ash) 0.10 0.08 0.06 0.04 | r- jo 0.02 I 0.00 AU -0.02 ' -o.04 ; -0.06 [ -0.08 :j -0.10 L- 30 6 10 15 20 25 Minutes Figure 111-15: D-701, after adsorption on chalcopyrite at pH 11.1 using soda ash. -81 - Figure 111-16: D-748 standard elution. .**.***>*;***>•*;***•***>:+ .Peak Report: All- Peaks;**•**•' k * •*- * * * * * * * *•*: *** ********;• Pk. • Ret Component'. • Concentration Height Area Bl. %Delta Num? : Time Name.'- ;-.;:-::'::.•;''::. Code 1/ 15 42 0.000 1072 99650 2 : 2 16 67:.;;-. 0.000 /S-:-123>: : 3063 2 3.' 19 42 0.000 1198 90233 .•r-i/.; • 'TOtal'S. :;: • p. 0,00'.;; ;•; 2392 ZZ1'SZ9aZ : D-748, after adsorption on chalcopyrite, 0.10 pH 5.1 (natural) 0.08 0.06 ' 0.04 i CM K.: 0.02 0.00 - AU -0.02 ; -0.04 ! -0.06 1 -0.08 ; -0.10 - 6 10 15 20 25 30 Minutes Figure 111-17: D-748, after adsorption on chalcopyrite at a natural pH of 5.1. -82- +**+*V******************** peak Report: All Peaks **************************** Pk. Ret Component Concentration Height Area,- Bl. % Delta Num: Time Name Code ; 1. 18.08 0.000 74 2315V. •. 2 19.25 0.000 2265 214418, •3 21.33 • • 0.000 3475 126616. Totals o. odo 5834:' 343349' D-748, after adsorption on chalcopyrite, pHll.l (CaO) 0.10 0.08 0.06 0.04 0.02 * 2 £ 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 10 15 20 25 30 Minutes Figure 111-18: D-748, after adsorption on chalcopyrite at pH 11.1 using CaO ************ * * *.* ******»,••***, peak Report: All Peaks ****•*,*************** + *** *-*** ' Pk. '• Ret Component.: Concentration : • Height ";..,'• Area' :;;B1V. Num : Time Name Cbde, ::: 1: 14.83 0.000 2700 : ; 602370 • 2'- :V -2- 16.50 0.000 .:-.;'.':.:727l':^::: 441215 is: ••'•V,3':':' •18.00: 0.000 :•• 4160 :: 130204; •:'•:- - :2. 18.75' 0.000 6169 541273 2 "'4' :••;: ; ; : ; ii :5:' ',21 .-33' ,';' •••'!"::.''::-:'' o.oq,o,'.:/ .;.;•'•;•: ' 36 4 7 'X: •; /':' ;i258to; 2 ; '.. Totals'".' '• 0.000 •"'.• :':-';l2394 6,; v ..1840955 D-748, after adsorption on chalcopyrite, pHll.l (KOH) 0.10 ; 0.08 I 0.06 ' 0.04 I <0 *i(B 0.02 ' 0.00 AU •0.02 -0:04 "! -0 06 ! -0 08 | -0.10 • . 0 10 15 20 25 30 Minutes Figure 111-19: D-748, after adsorption on chalcopyrite at pH 11.1 using KOH. - 83 - ***** ********************* *-'-peak\ Report: All Peaks ******** ******************** Pk. Ret Component Concentration . , Height . Area . Bl; •%Delta Nuni .. Time Name ' • . :• Code ' 1 14.8 3 :.. 0.000 : 2810 636682 2 2 18.00 : 0.000 10174 : 1061859 2 3- 19.50 0.000 4198 :• 720543 : 2 4 21.33 0.000 6029 215253 2 ; : : Totals • '. ::0.000' /V 23210' " 2634337 D-748, after adsorption on chalcopyrite pH 11.0 (soda ash) 0.10 , 0.08 • 0.06 ! o 0.04 I o « . o .tft .CO 0.02 t 00 0:00 AU -0.02 -0.04 i -0.06 -0.08 -0.10 10 15 20 25 30 Minutes. Figure 111-20: D-748, after adsorption on chalcopyrite at pH 11.0 using soda ash. .*********'***********'****:*** Peak' Report: 'All Peaks **'******.****.**************-*j 1 Pk. Ret' Component '':•••''•'. Concentration^ '• Height Area Bl. %Delta Num Time Name Code 1 15.33 0.000 7840 5668170 2 17.33 0.000 1040685 121558534 3 18.50 0.000 2017053 181757594 Totals: .0..000 3065577',:.' 3089.84296:; D-750 4.0 3.0 AU 2.0 1.0 0.0 5 10 15 20 ' 25'v.'';;'/;' 30 Minutes Figure 111-21: D-750 standard elution. - 84- »»'»»«»» w* ******* i*****.,^,^ * PeaJc Report; All Peaks • **v*******>*V************« Pk,; Ret Component Concentration Mum• Time Name . Height Area Bl. %Delta • Code 1 19.92 . .0.000 2442 180450 1 • Totals 0.000 2442 180450 D-750, after adsorption on chalcopyrite, 0.10 , pH 5.2 (natural) 0.08 j 0.08 I 0.04 I 3 0.02 ! 0.00 j- AU -0.02 ; -0.04 -0.06 -0.08 -0.10 .. —i r™' | i. "r r'j ' i—-1—t—r:-j— • I | i r "T 10 15 20 2S 30 Minutee Figure 111-22: D-750 after adsorption on chalcopyrite at a natural pH of 5.2. • ******* *****•••*•>•>***+*.** 'Peak Report: .All Peaks ************** ******* Pk. Ret Component Concentration Height Area Bl. %Delta Num Time Name ••• Code-. 2 19.83 0.000 9670 662177 3 21.25 0.000 . 3323 121125 Totals 0.000 12992 783302 D-750, after adsorption on chalcopyrite, 0.10 pHll.l (CaO) 0.08 0.06 0.04 «6 0.02 .i 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 I- I I j I I t I, - | — 10 15 20 25 30 Minutes Figure 111-23: D-750, after adsorption on chalcopyrite at pH 11.1 using CaO. -85- Peak Report: Ali• Peaks.; *»•**.. Pk., Ret Component Concentration . Height Num.;;.-: ; Time. Name Area Bl. %Delta Code 1 15.67 0.000 2 17.33 798 133885 2 3 19.06 o.ooo 12625 1313837 2 4 21.33 0.000 24495 2524738 3 0.000 3248 78729 4 Totals 0.000: 41166 4051188 D-750, after adsorption on chalcopyrite, pHll.l (KOH) T-1 .^.T-T't-TT 15 20 Minutes Figure 111-24: D-750, after adsorption on chalcopyrite at pH 11.1 using KOH »•**•*** * * * ***** ** * * *********' peak . Report':'- All Peaks; Pk. .... Ret Component . Concentration.... Height . Area .: Bl. Num. • Time Name Code .' i 15.67 0.000 :' 711 130381 . -,:' 2 '2- 17.33 0.000 19367 ' 2255157: 2 3 18.58 o.ooo 38173 3535270 • :".'. 3 .v';:4' 21.33 0.000 • 3193 :• 81176 4: Totals,. 0.000 61444 6001983 D-748, after adsorption on chalcopyrite, pH 11.1 (soda ash) 0.10 0.08 0.08 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 , •TTT- I . i . i i; i •;| -v.r-'Trr.~r'~.n-T—i • i. j—r~i 10 15-:::{;.:-•' 20 25. 30 ":' Minutes?. Figure 111-25: D-748 after adsorption on chalcopyrite at pH 11.1 using soda ash. - 86- ********* **'.** ********** **** '.'Peak'; Report':.; All Peaks *******************.********.* : : ; : : : Pfc. "•: ' "Ret;"Component-;','.• :' Concentration:-: •" - Height;; : ;y.; : Area • '-Blv- :..%Delta:;..; ; : V; : : Nwrt.' :'; fitti®'; Name :;' :';. ;; - 1'-;iv •. '- . '.•:' Code'y-^-y. './'' , :;..-• 5i'o 9;v: 1 •y-Uiit'-'' 0.000 5787570 2 2 • -17.•33'. •.. 0.000 314888 37930364 2 3 . 19.00.; ;/::;A:;' 0.000 723369 85894606 2 is . • 0.000 /v':".10433;67'|: 123612^0 D-912 0.9 0.8 ' i'f',;: 0.7 , : ;".::>/#--;;;.:';;: :/;;\:V-c;.,;:i:;:,;v ';:,/vv. 0.6 ' • - '..••••;;:.-:: ;: «•»:•/ 05 . 04 ym::yy~. AU > yyyyyyyy , : : 0.3 ;;•^V;. ;^•:v.r;s^}| H i-V-y'• \-yi >:•'. •::'•' 0.2 I •: .11:;, • ;'• :\.. :,,. V V •• :': 0.1 ' •••' •••:'••;'.: ::-m;. .: i^*; ?: ...0. : ,: 0.0 I ' '^^i;'' • ' - ~yy 5 10 15 20 25 30 Minutes Figure 111-26: D-912, standard elution. *************************** Peak Report: All Peaks****************************.* : Concentration Height. Area Bl. % Delta Pk . : '•:''' Ret:.Component: 1 : : ; ;,.,.. .;;'; -y-yy:;k.- :>,v;-: - ;';;•'; ••'Code v • y >.'•• •Num:, - Time;: Name; v v : : : yyyWi^:s»-yyy:y-yy-y-.yy-:, •^yy. '\y :yyyy • dvooo^ ;..;:-• ^,yryyyyyyy 2 19.92 0.000 7349 621280 2 ; : : ; : .Totals'^' |:;-.;-'';-?.5v:V^ -•'. 77^2;X % -'66535:0/;.;:' D-912, after adsorption on chalcopyrite, pH 5.1 (natural) 0.10 0.08 0.06 yyy.'yy^y:: '•y^.y^yyy^-'hyyy- 'yy.-] .. 0.04 | tri 0.02 : •••<**«««•••<••• —-:—~r~—. —- _ y^^«!!^yy.....y^^..:_ .... •••'".•,.."•'.' AU°^ - - -0.02 -0.04 ; -0.06 J -0.08 j ! -0.10 | , -r 1 i - - - - • r- . • ' '• \ 6 5 10 15 20 25 30 Minutes Figure 111-27: D-912, after adsorption on chalcopyrite at a natural pH of 5.1. -87- ****************.***** All Peaks, >*.** *,**•***•*••«•**** *• **•***•*#* + * Pk. • Ret Component; . Concentration Height ,: Area' - Bl.; %DeltaV : Num Time, Name..; ' Code •';. • 2 17.42. 0.000 395 42349. 2 19.83 0.000 8507 563253 2 21.25 0.000: 3297 104384 totals 0.000. •i2l9;9,: 7.099.86' D-912, after adsorption on chalcopyrite, pHll.l (CaO) 0.10 0.08 0.06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 5 10 15 20 25 30 Minutes Figure IH-28: D-912 after adsorption on chalcopyrite at pH 11.1 using CaO ^;******** ******** ********** peak -Report:: All. Peaks .:.***+**^ : Pk. Ret Component: .. Concentration Height;; Area... Bl. %Delta:: Num Time Name • • •Code - 17.92 0.000 •• 140.. 10700 19.83 0.000 10416 797742 21.25 0.000 4 618 140640 : ; : ' Totals -S-.qoo:; .i.517.4;' •:94:9062v D-912, after adsorption on chalcopyrite, 0.10 pHll.l (KOH) 0.08 0.06 0.04 0.02 0.00 AU -0.02 -0.04 : -0.06 -0.08 -0.10 0 5 10 15 20 25 30 Minutes Figure 111-29: D-912 after adsorption on chalcopyrite at pH 11.1 using KOH. -88- **++**********************••• peak Report: All Peaks ***********************:****it Pk. Ret Component Concentration Height . Area 31. %Delta Num • . Time .Name. .'. • ..'.'••'. , Code; • • 1' 16.17 " 0.000 103 4205 2 2 17.33 0.000 1667 237725 ' 2 . 3.'.' 19.75/ .—/,/'.:- : 0.000; 12026 1215198 ; 2 : 4 21.. 2.5; •/,//,' , 0; ooo; 4803 . 172054 2 ; : • :: ':' ^ './'.'totals ; /';"'' 0.000 .v 18599; ; •''1.629182 . D-912, after adsorption on chalcopyrite, pH 11.1 (soda ash) 0.10 0.08 0.06 0.04 0.02 0.00 AU -0.02 -0.04 -0 06 -0 08 -0.10 5 10 15 20 • 25 30 •••••••• •'• Minutes. Figure 111-30: D-912 after adsorption on chalcopyrite at pH 11.1 using soda ash. -89- ••>**«»****#***«******•***« Peak Report:' All Peaks- ,*>**>***•***.***•*****.***#*****. :pk. Ret Component Concentration .Height. Area'' Bl.' %Delta:-' Num '/Time Name Code.:.' l' •' 15 67' - 0 000 100- • 12637":.-' •' .2 '. 2 ' 17 33 0 000 2004 250921 2 3 -18 58 0 000 4736 .39.7861..: 2 Totals. - 0 000 ; 6841 "' 661420 D-619, after adsorption on molybdenite, pH 4.2 (natural) 0.10 ? .0.08 I 0.06 0.04 0.02 0.00 - AU -0.02 , -0.04..J: -0 06 i -0.08 ! -0.10 . 6 10 15 20 25 30 Minutes Figure 111-31: D-619 after adsorption on molybdenite at a natural pH of 4.2. The initial D-619 concentration was 5 mg/L. «•****-«.***.•»**:**-**•*•**+***•*•*-*•+• peak' Report:! All Peaks ****>'*'*• ***'*'*.*******,*****.*,*'* ••Pk. :• .-.Ret -Component, •!; Concentration:: •'Height.':-!:!''' Area;,- Bl!-.-ADelta • 5 ' Num - 'V. Time- Name': :'. :•'!'"!.!":' Code :' !/ !l.::."V.17 . 92 "O.'OOO : 24 9; - 1.4.18"4:.: •2!':: .19,33 : 0.000 '22;2281;:::!: 2498;: Totals ;OVOQQ; ':236'4:6'5;!': ;27 47':" D-619, after adsorption on molybdenite, 0.10 pH 4.4 (natural) 0.08 0 06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 "TTT~ 10 15 20 25 30 Minutes Figure 111-32: D-619 after adsorption on molybdenite at a natural pH of 4.4. The initial D-619 concentration was 30 mg/L. -90- ******************* * **** *** Peak Report:'All Peaks Pk. '". Ret Component • '' . .Concentration .. / Height. ' Area. Bl. ,%Delta •Num; "Time Name ,-'/ - • / ' -'.-/ -.'••',,'- Code: : • •:'-/-iv-:'I5;'jC.o\'' ••"•'•••}:• ••.'/•• :o.ooo•'• •;.1450'-••:',•238.4.93''.'-' 2 .;. 2 17.33 0.000 2253 284467 2 ,.: 3.;.;: 19/33• ..' 0.000: 6132. . .- 597735 '. '.7 2.-"- '' ,-:.'';.' "V To'ta'lV :. '• 0.000 -98 35 1120695 :; .•:.;•:• D-619, after adsorption on molybdenite 010 pH 4.4 (natural) 0.08 i 0.06 0.04 i 0.02 ; 0.00 L— AU -0.02 -0.04 | -0.06 | -0 08 \ :-0.l6:M*:-:/i:T: .0 5 10 15 20 25 30 Minutes Figure 111-33: D-619 after adsorption on molybdenite at a natural pH of 4.4. The initial D-619 concentration was 75 mg/L. ********** ************ A * * * *" Peak Report:. All Peaks''•*•*• *:**'••*****.***'***,• *•**•>* *' **.*-i Pky :. Ret Component Concentration-:? • Height '. • . Area Bl.^Oelta : Num:. .-- Time. Name,' •:••':'•• ' Code. • :•:.;'! ;; 2&.;1T: • / :./:-V/. :'":"'.' OV.QOQ,; -': •'/'-•; 925". '.'• '67 690 • iZC.xZ-,:. ZZi^}ZWZ-kXiJ^ •::."•; Totals^ ':;/. • "/•'•';• ::'6Vo0.o','.-.- -.'';\;.-;v-:7925,:;; v '. .$769Q7-7 D-619, after adsorption on molybdenite, o.io pH 11.4 (CaO) 0.08 i 0.06 i o.o4: t 0.02 I 8 0.00 ' AU -0.02 -0.04 -0.06 -0,08 -0.10 10 \;:.~~15'••"""ab.---:'.25 . 30 : Minutes __ Figure 111-34: D-619 after adsorption on molybdenite at a pH of 11.4 in the presence of lime. The initial D-619 concentration was 5 mg/L. -91 - >***•* * ** * * *********** * *.* ** •*.. peak Report: Ail Peaks.-,** ************ ************* * PJc>." . Ret- Component •' 'Concentration ;:. Height:-:-:. Area- Bl.;. %.Delta : Code::" Mum.Time : Name:- 2 .17.33 .0,000 430 48108 3 19.58 0.000.. 2308 172108' Totals 0.000 2738 220216 D-619 after adsorption on molybdenite, 0.10 . pH 11.3 (CaO) 0.08 ! 0.06 I 0.04 ' 0.02 0.00 AU -0.02 ' -0.04 ; -0.06 ' -0.08 -0.10 !- 0 10 15 20 25 30 Minutes Figure 111-35: D-619 after adsorption on molybdenite at a pH of 11.3 in the presence of lime. The initial D-619 concentration was 30 mg/L. ;***********'*:**•*************• peak Report':' All Peaks .**'***'*»..**•**.*••*#•*#•**'****.**•****. Pk. ':. ; .Ret.' Component; Concentration. ' Height. •'. Area Bl.: % Delta'. Num Time Name'-: : Code ' 1 1.7.58": "\' 0.000 4io.:: • 40'52 9;-' '•'•;• ,2- • 2 19.67 0.000 '6371;; 574066 2 Totals: 0.000 :67'8i::; :-6145:95^:'--:::': ::'!l^;::.::-':----.'.',' D-619, after adsorption on molybdenite;, 0.10 pH 11.2 (CaO) 0.08 i 0 06 '' 0.04 , 0.02 ! 0.00 f- AU -0.02 -o.o4; -0.06 -0.08 -0.10 • 10 15 20 25 30 Minutes Figure 111-36: D-619 after adsorption on molybdenite at a pH of 11.2 in the presence of lime. The initial D-619 concentration was 75 mg/L. -92- + * pesk Report: All Pesks Pk. Ret Component Concentration Height. Area Bl. %Delta Num .. Time Name * Code . . 15.00 0.000 13 9 4-. • 290710 17.33 0..000-. 5771 649833 19.25 0 .000 ,1.0932.'. 1.152794 Totals' 0.000 -180.9.7'- "2093338, D-619, after adsorption on molybdenite, 0.10 pH 11.3 (KOH) 0.08 0.06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 10 15 20 25 30 Minutes Figure 111-37: D-619 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH. The initial D-619 concentration was 5 mg/L. »******.».**-**.****•«*.*•* teaks *"**••' . Pkv. -. Ret Component- Concentration, .. Height -Area 31. %Delta Hum •. -Time Mame'V- • ::V,\ -Code •'.', : 15.25'.' ::o-.oo'o., 1088. .178848 17..33 o.ooo. '• :4107, '474745 19.25 o.ooo 1014 3;; 999115 ..Totals'' 0.000- ' 15338;-.: 1.65270fcV D-619, after adsorption on molybdenite, 0.10 , pH 11.2 (soda ash) 0 08 i 0.06 0.04 0.02 0.00 i- AU -0.02: -0.04 : -0.06 -0.08 -0.10 0 10 25: 30 Minute? Figure 111-38: D-619 after adsorption on molybdenite at a pH of 11.4 in the presence of soda ash. The initial D-619 concentration was 75 mg/L. -93 - ,****************'**•*****+** .peak Report:. All Peaks *********-*************;***** Pk. Ret Component :• i ;, Concentration Height Area. Bl. SDelta Num. Time Name; . Code 1 .16 •25 • 0.000' 52 .: 1396 . • 2 2 . 17 33., o.ooo 1230 ., 155178 . 2 3 18 33/'' 0.000 " 2943 • .222476; • 2 Totals •:,.'";.' •-• : 0.000 . 4224 . '37 9050':' D-648, after adsorption on molybdenite, 010 pH 4.4 (natural) 0.08 0.06 0.04 to r~- » 0.02 0.00 AU -0.0nM2 -0.04 -0.06 j -0.08 : -0.10 ' 0 5 10 15 20 25 30 • Minutes • Figure 111-39: D-648 after adsorption on molybdenite at a natural pH of 4.4. The initial D-648 concentration was 5 mg/L. *>** *;* ******* + *•***** * * *.*• + *.* pea k. Report: All Peaks Pk. ; Ret-Component:;;, {.• ''^Concentration ^ ,'. Height: Area-:, .Bl'v. %'Deifi'a . Num'' Time Name .-';•' ' ...' .;: Code ' l'..- '17.75 .'.•' ' :0.000 :','.' ••:::•: 235 '." .274S'9:\'" ?. 2 19.50 0.000 3624 304291 2 : : : : ; •> :;•!••:'•.:';;>::: 'v; ;••:/• " *qtais. o'iopo:•.;••„:;': .v 38&9" D-648, after adsorption on molybdenite, 0.10 pH 4.4 (natural) 0.08 ' 0 06 . 0.04 £ ° '•: ••".•{••. i^: ™ .... 0.02 0.00 I—. ;.. "."' '. :~~ ;•..".;• - :..';..-L:.^_„_.,_„^..;^• ;' -' AU -0.02 -0.04.1 . . -0,06 ; -0 08 . -0 10 ' • . 0 5 10 15 20 25 30 Minutes Figure 111-40: D-648 after adsorption on molybdenite at a natural pH of 4.4. The initial D-648 concentration was 30 mg/L. -94- '***'*****.***.**************.** ' pQatk- Report i Al 1 Peaks .•'**-**-*•*******'**.************** •Pk; 1 .• 'Ret -Component'', Concentration v...-. Height'-.1- -;< '.Area':,- Bl.' ••%Delta.-. : /Num i'- •'Time. Name •; ';: "•'. '"V • ' ••;, -";-/; '.% v':/ 7 ..•.'•';,.••;,"•;. Code;. •'• • ::. .: : : YM : : Y : :; : : .••••"•' •i:..' 'i5v33 C . ^: -:^-' > ^'> -; -,:-.' W-v •o.ooo'-::::. "V; ' 753V-:,. ••:;:'.-:i'io"l29S' •;•::::,''2'>•: :::v';2V':i7;33:::-S^ ;•::•;' ; O.OOO.:':.: -.-:--" 2431--•-:--V'331287:/-,, 2 ; : ; :'.:-'3-.\ 19 .:58 ::'•->' -' '.'.'.:•': v:- / J:..t::V:,:- 0 . 000-?;v "x;:. 92,12M ;.v .917735 -• -: •'• : : : I'- . V- :;•• :;v .:.V;I ; :Totals':.V;.." ' 0.' 000 • ••'.';•' :'123'9'6v' O 1359318 ' •: D-648, after adsorption on molybdenite, o 10 pH 4.5 (natural) 0 08 0.04 3 « 2 ai t *" 0.02 o oo AU -0.02 -0 04 -0.06 -0.08 • —r~~~- r • • ' ~- j 1 ----1 —- i—i -0.10 0 5 10 15 20 25 30 Minutes Figure 111-41: D-648 after adsorption on molybdenite at a natural pH of 4.5. The initial D-648 concentration was 75 mg/L. **•*-* **** *.*.**.* * * *•* * ***** * peak "Report't: :Aii:': Peaks'1 •*•** »•***:* *•*•*.* ****** ****** #.« Pk. Ret. Component Concentration Height Area El. % Delta Num' : Time Name:-. •- • ':• - - :.-•.'.•.,.-••:••.-.-. '.Coder. ••• 1 19.75 O.GOO 677 571C3 1 Totals O.GOO 877 471C3 D-648, after adsorption on molybdenite, 0.10 pH 11.3 (CaO) 0.08 0.06 0.04 P 0.02 0.00 ------AU -0.02 -0.04 -0,06 -0.08 -0 10 10 15 20 25 30 Minutes Figure 111-42: D-648 after adsorption on molybdenite at a pH of 11.3 in the presence of lime. The initial D-648 concentration was 5 mg/L. -95- Peak Report.: AiT Pea ks w»• * * * » « *» ;pk'.:',:' .Ret Component; ..; Concentration., Height:;.,. ... Area Bl. "IDelta : : : Num : Time Name . /..''' ,, ,'•'•/' ./'-.'' ' ;.' :-. ;: Code - - 1 19/75 0.000 • V 3129 '.'• 173715 • 1 -'•", • 2 29.17 ..0.000;. ' • 678-, 125765 1 -•Totals' 0.000 3806 3054 80 D-648, after adsorption on molybdenite, 0.10 pH 11.3 (CaO) 0.08 0.04 : ^ ^ 0.02 ! • . ' • . " ., o.oo ' — • k —-—— AU „ . -0.02 , -0.04 ' -0.06 , : :. -0.08 : . -0 10 ' - 6 5 10 15 20 25 30 Figure 111-43: D-648 after adsorption on molybdenite at a pH of 11.3 in the presence of lime. The initial D-648 concentration was 30 mg/L. jr + peak- Report:' All Peaks *'******.*>*^^ Pk...:7 Ret Component; .-. . ' Concentration: ;; Height. : .Area Bl./%Delta Num '. Time Name/'-. . Coder:''-' ":'r i&.oo '.',• .-: o.ooo 36'-,:. ;•-'/'2657, z':- '-.'.- ; ; L ;-::-2" ;:19'.67, '' ,0.000 ,;-."- 815& '. :--523678 ' - • "2 - '7-'7:/-,7f v:: Totals o^ooo •,'.' ''':;'••;'•.;'8-191-•': .-:- -." 5263357/ .'..'/://'. • D-648, after adsorption on molybdenite, 0.10 pH 11.2 (CaO) 0.08 0.06 o <9 0.04 o o> 00 T- 0.02 -,: o:00 !"'r;'"-":' '':."'-..'...:..•.' :'-• ::--"'! '"••'- ''_L^g2=^_r_^_.,:' :.:.1L..::.:L.::IIL---.'- V '-'' ' AU '-. -0.02 -0.04 -0.06 -0.08 -0.10 - • - - 0 5 10 15 20 25 30 Minutes ; Figure 111-44: D-648 after adsorption on molybdenite at a pH of 11.2 in the presence of lime. The initial D-648 concentration was 75 mg/L. -96- ***•*»****************'****** peak-Report.;. All Peaks Pk. ' Ret Component Concentration ; Height Area Bl. %Delta Num .Time Name. • • •' • Code' • • ' :.15.4 2 • 0.000 524 93180- -:-' 2 17.33- • ••: 0.000 4547. 518058 . 3 19.50 0.000 • 12760 114702 0Y Totals 0.000 17 631 1758258. D-648, after adsorption on molybdenite., 0.10 , pH 11.3 (KOH) 0.08 I 0.06 0.04 0.02 0.00 AU -o;o2 -0.04 -0,06 -0 08 i -0.10 r 0 10 15 20 25 30 Minutes Figure 111-45: D-648 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH. The initial D-648 concentration was 75 mg/L. b * *r* *•# *. *• * >•,' * * *' * #> ** Peak,Report; All; Peaks• ********************** : :• Pk.-.:,'.. ;.-Ret,.Component Concentration:' .-Height. \ :Area: : Bl'.;. %Delt< NumV • Time Name : .- Code -15.67 O.OOO 56.6-.: :.: .,65384'-, : 17.33 0.000. 3793 44 5508 : ; :il23219: -19.42-' 0;000 '12415: ' : Totals• o.ooo:; .167-74': •i634"iiO-' D-648, after adsorption on molybdenite, 0.10 , pH 11.2 (soda ash) 0.08 i 0.06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 ,- ' • i. 30 0 10 15 20 25 Minutes Figure 111-46: D-648 after adsorption on molybdenite at a pH of 11.2 in the presence of soda ash. The initial D-648 concentration was 75 mg/L. -97- *,**«•***-'*•.*.******•*• *•«'****##*• •• Pea^ Report:. All Peaks•;:*.*^*** + * + ************'.*** : Pk. Ret Component ' Concentration Height Area: Bl. %Delta Num Time Name •' Code ':" .1' "l9.6?- : ' -;.':.0;000 ... ••.929 \, 67988/:--' / 1- -,' :'•...';..: Totals-/ ::;,.Q;.QQ0: •'••••'••.''•/:;:' '929 . 67988: > D-701, after adsorption on molybdenite, 0.10 , pH 4.4 (natural) 0.08 j 0.06 0.04 :••''.••••/ .. •»••:.,••:•••••:••.••:•••:•:••••,•.,.h- ••:•••• ' '• • 0.02 o> ;:.>.:•:.:•••/••..• 0.00 >- '•'•••'- 7:/'' : •:/ :-•:"'• ' '';v/.0//.A-= 'K"'---;: /'.','- ;- AU -0.02 -0.04 -0.06 -0.08 -0.10 T^L,:^ 'T^^^ii^' 0 5 10 15 20 25 Minutes Figure 111-47: D-701 after adsorption on molybdenite at a natural pH of 4.4. The initial D-701 concentration was 5 mg/L. '* Peak Report.:- All Peaks :**,** ******* * ***•*.*-* ******** + •»- Pk.;- - Ret Component/- /'•:.. Concentration ' Height.'. Area Bl. % Delta- Num; .Time Name ;" Code' '••'• .0.000 4 6 " . -2 914, 19.:7.5::: 9;-000; 3729//::v.272111:: Totals' b:.ouo; •31.7:5, 27502 D-701 j after adsorption on molybdenite;, pH 4.4 (natural) 0.10 0.08 0 06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 10 15 20 25 30 Minutes Figure 111-48: D-701 after adsorption on molybdenite at a natural pH of 4.4. The initial D-701 concentration was 30 mg/L. -98- .•••*****•« * * *•*-* **********#**.* Peak RepOXt: An Peaks ****** *.*.* ******* ******* ***** Pk. Ret: Component Concentration Height- 'Area- 81,'' ;% Delta' Num Time Name- ; •; ':. .Cade '.' : 1 17.58 . . :", • 0.Q00- ' •'•• ,436.'-' .66115.,..,''-' % •'•'"/-. 2 ; 19.67 0.000 • • 10120- - v 887940 .2 Totals .0.000 : •..'• -'10556: : • 954055 : :' D-701, after adsorption on molybdenite, 0.10 , pH 4.5 (natural) 0.08 0.06 I 0.04 19. 6 0.02 17 .6 8 o.oo • AU -0 02 -0.04 -0.06 -0.08 -0.10 - 0 5 10 15 20 25 30 Minutes Figure 111-49: D-701 after adsorption on molybdenite at a natural pH of 4.5. The initial D-701 concentration was 75 mg/L. *********** *,* * * *•* * * * * * ***** peak/ Report,::'All" Peaks; *************.*,**.****'***;*.*^ :;. Pk.'- '.' Ret .Component-:- • \ -. '. Concentration,.:. '/.;•;. Height v '•• "/ Area': Bl'.-:. % Delta/,', ', Num';;. Time Name;- .,/ ;••/;', /:;•• '''./. r-,-//-. Code. ./'•.// •'• 1 •: 20,17 •;,/.;',.•;' : . ,'. -.-y- y 0;00py :;?••'•..•-. ':316 y/;/-:'-/,52655y'7-'V.;;!^;--.''-;/- •Totals ; y y • 0,.000-'..'/: •';••;; 916";•/-;' \ ''^2^Z;Z^^^;r.^ D-701, after adsorption on molybdenite, 0.10 pH 11.2 (CaO) -::-';;:-:'--'o.08':i /-;.;: •:•:/' 0.06 f •'.'••;-•:' "0.04;.{ "'••> 0.02 : : ; — -r—r? ' 1:,.''' ':-,"';••- ,'- ••'' -;- , • ,7- • AU 000: -O.02 i -0.04 -o.o6 . -°08' -610 ; ! I • 1 . 1 1 : ! :•:••'•--•'.'-• 6 .. : •• 5;--' 10 15 20 25 30 • - Minutes;/ •/ Figure 111-50: D-701 after adsorption on molybdenite at a pH of 11.2 in the presence of lime. The initial D-701 concentration was 5 mg/L. -99- ** * * * * *'* ********* *.* * * ****** pgak Report: All Peaks +*************************** Pk.: . Ret Component ' Concentration... Height.' Area . Bl%Delta:'V Num .; Time. Name .-.; ; : ; , ' .' -U/'-V'. '•'•.v":." .- ' Code: '7 •.;>.;. '-• : :v: ; 7 .1- ' 'lT.5b, ":-• .?'.:' : : ,." ;:'::•:,."'"; .> • 0.0 6 0 :,'.r •, -/'i. -35 7:'. • V 367.84 : V- zJ-2 .-' : •;.'.2 ;: ;19..67 0.000 3133 203076 2 '.''Totals':'. :' 0.000::: ^734917 : 239860:; '•[.'< :':"S ;;: • D-701, after adsorption on molybdenite, 0.10 pH 11.1 (CaO) 0.08 0 06 0.04 0.02 ' 0 00 • -—-::'" --v' :. '. •>•'•::.; AU -0 02 -0 04 -0 06 -0.08 -0.10 • , -,- .— ,—„.„ ! ,( (. 0 5 10 15 20 25 30 . Minutes.. Figure 111-51: D-701 after adsorption on molybdenite at a pH of 11.1 in the presence of lime. The initial D-701 concentration was 30 mg/L. *************** * * * * * *.* ***** • ^ Report: All Peaks- - -*-*•* * * *•** **.******.******* ** *•*•* - • Pk. ' •': "Ret:Componen t Concentration Height ; Area- Bl'.Welta: .Num . .' Time Name / v.-:: '. ;.: ;'.-, : /'•• , ; . ..Code.: ; . . .. '• ; : : :< • ',." 2..:-i9v67;- '••.";,". ' ••'.;,:.'.' 0. 000 \ : ' " .8 930 ,;7 ;';5591'24-v:' '2-7-7.:-7 ''• 77 ; :; ; : : ;Tota 1 S::- •'. :'.;:: •.. 0'.: 000'7? '• -.. V' 8 930 ':••/• "" • .559124y ••:;• 7'{,: 7 • 7; 7 D-701, after adsorption on molybdenite, 0.10 pH 11.1 (CaO) 0.08 0.06 r~ • • •. o 0.04 | O oa:-. 0.02 -0.10 :\ . j; J • y,,,' . y l 7'.:7 1 ': ;7 . 7. -7,l'i'.<. ••- 7:.. i... J ::::/7 !~:':.' 7- 7 — 0 5 10 15 20 25 30 • •• Mmutes •':.••"• Figure 111-52: D-701 after adsorption on molybdenite at a pH of 11.1 in the presence of lime. The initial D-701 concentration was 75 mg/L. -100- • **•******#•***#«•******>'**•**.- Peak. Report:• All Peaks ******* ************ ********* Pk/ '• Ret,Component Concentration Height Area Bl. % Delta- Num ' Time Name Code . 4347 .1 16.08'. 0.000 . 2 17.33 0.000 1020 143153 0.0'00'V 12513 985543 Totals 0.000 13606 1133043 D-701, after adsorption on molybdenite, 0.10 pH 11.3 (KOH) 0.08 0.06 , 0.04 : to > •••• 0.02 1 0.00 AU r -0.02 | -0.04 | -0.06 ; -0.08 i -0.10 10 15 20 25 30 Minutes Figure 111-53: D-701 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH. The initial D-701 concentration was 75 mg/L. »** *.** ******* *** *.*******.*.*>-.peak Report;-. All. Peaks1******************;**** *****, .•Pk-.. :: Ret Component ; Concentration Height; Area Bl. % Delta' Num' ' Time'Name : Code 16.00 '. 0 .-.000- .63'. - - : -4 7-7-1: 17.33 •0.000' '..1032 ,.:Y 158073- •.19-.50- O.vQO.6:: .13423: . .:• 1141076: Totals :.o;ooo. • 145IB 1,303915 D-701, after adsorption on molybdenite, 0.10 ; pH 11.2 (soda ash) 0.08 ! 0.06 : 0.04 I 0.02 ! <0 I-' ' : 0.00 AU r -O.02 : -0.04 I -0.06 -0.08 -0.10 o 10 15 20 25 30 Minutes Figure 111-54: D-701 after adsorption on molybdenite at a pH of 11.2 in the presence of soda ash. The initial D-701 concentration was 75 mg/L. - 101 - : t******* ******************* Peak Report: All Peaks *********.*****-*********•*** 'Pk-.-.- Ret Component /-.Concentration:1... Height., Area-'. Bl. % Delta; Bum - : Time; Name V:.i:\' Code. "• 0 .000 1209 1-55501; .8.42 0.000 3073 198798 '0.000- 4282. D-748, after adsorption on molybdenite, 0.10 pH 4.3 (natural) 0.08 0.06 0.04 nrt «•» 2 Sr~ 0.02 0.00 AU -0 02 -0.04 -0.06 -0.08 -0.10 10 15 20 25 30 Minutes Figure 111-55: D-748 after adsorption on molybdenite at a natural pH of 4.3. The initial D-748 concentration was 5 mg/L. *************************** Peak' -Report': -. All:.: Peak's- ******* A * ********* ********** Ret, 'Component;' .:;:•:.-'- ...Concentration ;- .';:• Height,' - - Area- NUJl;. Time Name:--.'; Code: 1 ,. ie.,i7 '''..'•• :.-"'. - '••O.OOO"-'•'?' •" • ".1169 ••' 111-14 9 '.- '2: 2 .16.92 7o;ooo;:: "'• 521 27901 2 ':'- • ,17.. 92. .:•:'.• •'.' O.OQO":: ':';;;:} 310 ' :,184.24j ,:,- '2 ..-4; 18.'6.7 c : : .:••-•.'•'• ":-..'.-V'',7-P>.°-9 !i':.':'' '.'.16.56,.'.' ;.:.135088;. '••2 : Totals;- - ...Q'/OOG.;" ••' •'-.-';.' '3.656 ;';.-' 2 9 2.5 63- D-748, after adsorption on molybdenite, 0 10 , pH 4.3 (natural) 0.08 0.06 0.04 0.02 0 00 AU -0.02 -0.04 -0.06 -0.08 -0.10 ' 10 15 20 25 30 Minutes Figure III-S6: D-748 after adsorption on molybdenite at a natural pH of 4.3. The initial D-748 concentration was 30 mg/L. - 102- t****************:********** Peak Report':' All; Peaks * ****** * * * ***** ****** * * * * * **. : PkV Ret Component '• .• :; ...Concentration ';';.'.•/• Height "/••'•.' • 'Area^Bi;. .'%Del'ta' Num. : Time Name:.-., /,;•' ' • . '::.;::.' ' '• 7,C6de.:;;';':.; :'l"i 14 :'92." ' " ''•'':': '\'^ - 0*OOO'.:''^':-":v K-13i7 '•. ^ :263058:":'^,:-2'.''';:-' : : ; : ^ .2,;.i6.83:.;: .,v' '-':;V\: ';o'OOO:;;V";:V:J<;'2863. yy\i64i52y:y-zy:-.r';^ : : '•[:• -Totals^/' " .0.000 '-V.'41.5p'',:-"'': ;;'42724p, ;/ . " '^ .-' D-748, after adsorption on molybdenite, o.io pH 4.3 (natural) 0.08 0.06 • « 0.04 5 • 0.02 0.00 '- - • "~ . . —. AU-0.02 -0.04 -0.06 -0.08 -0.10 0 5 10 15 20 25 30 Minutes Figure 111-57: D-748 after adsorption on molybdenite at a natural pH of 4.3. The initial D-748 concentration was 75 mg/L. & *.* * **** * * * * ** •* * *.* * ** :'. ^ ReDort:/ All : P&a ks * * *.** *.*.* * *'•*. * ***** * * *.**'* * * * * * Pk.' ':'V'-::Ret .Component'''... v "'/ Concentration .'- •' Hei'gKt'.:: ;';'::',Area:-; ..• Bl. ' %belta" .: Y: : ;Num.:. Time Name ::.;:;'c y/: I \- ;\ /..';:' ::.< ,/ .^^ Code. -. ; : : : : : y^'k-iy ^M'- ' "'Totals^X: ;.::;; ::;.'V :.::-P> 00p;,:,.';,:XyMyyi^0X:y,,: ".' .v::;:--0 A :y:-;V; D-748, after adsorption on molybdenite, pHll.l (CaO) 0.10 0.08 . 0.06 0.04 0.02 0.00 — - AU i -0.02 ' " . -0.04 : -0.06 -0.08 -0.10 - - - - • , , 0 5 10 15 20 25 30 Minutes Figure 111-58: D-748 after adsorption on molybdenite at a pH of 11.1 in the presence of lime. The initial D-748 concentration was 5 mg/L. - 103- *************** ****.** * **•* *•* p^^|^ Report "* Ail' Pea ks" * * **:*•*•*•*** * *************- Pk". Ret:.. Component ' ^Concentration, • • •' Height:; ././Area ••''Bl> ' %Delta Num-' Time'Name ;'••--.:')••- Code •' : ; ;: ;1 '-19,,7 5 >,•"•::• - , • ;j •' • yy:,/"'0.:0Q0;-.' .12 69- •::.''; ' 90.7.4'5:.V;; : 1:; -V"":' : : : :v : ••'--::'•'.y' • '"Totals• Z..Vv">' 6*QOvV— v \ -:,1269-;/7;;790745Vv ••: ; D-748, after adsorption on molybdenite, pHll.l (CaO) 0.10 0.08 0.06 0 04 0.02 0.00 AU -0.02 -0.04 -0.06 -0 08 -0.10 , , • > - - 0 5 10 15 20 25 30 Minutes Figure 111-59: D-748 after adsorption on molybdenite at a pH of 11.1 in the presence of lime. The initial D-748 concentration was 30 mg/L. ******** ************* **•* * *.*. k ReportAil- Peaks1 •---*** ************ ****** *.**.* *** Pk. Bet Component Concentration Height Area Bl. %Delta Num -Time - Name Code •• Z - 17.33 0.000 621 91156 2 3 19.00 0.000 3742 361954 2 Totals 0.000 4363 443109 D-748, after adsorption on molybdenite, 0.10 pH 11.0 (CaO) 0.08 0 06 0.04 - -.-'::. CO CO 2 ..•.:•-•:-:-.-... CO CO ::> • • 0.02 CO J- 0 00 AU -0.02 -0.04 -0 06 -0.08 -0 10 -- - - 0 5 10 15 20 25 30 Minutes Figure 111-60: D-748 after adsorption on molybdenite at a pH of 11.0 in the presence of lime. The initial D-748 concentration was 75 mg/L. - 104- * *************** * ********* * peak Report:: All- Peaks .**************************** ; Pk. Ret Component- Concentration - ;" Height ; Area Bl. IDeita- Num Time Name.. Code • . i 15^00 o.ooo i9'2o:.. 491565 2' 2 17.92 • 0.000 , 13838 . 1350284. 2 : :3. 19.50. 0-000.' .7719:: ; '.. . 1095756 ' : - 2V : •' Totals' : 0.0q0"7 . :2347S 2937605 ''•'.'' D-748, after adsorption on molybdenite, pH 11.3 (KOH) 0.10 0.08 0.06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 0 5 10 15 20 25 30 • •••••• ••• '—— • •••••• • ••• Minutes Figure 111-61: D-748 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH. The initial D-748 concentration was 75 mg/L. * ********'*'*'*****'******•*-*** * pea k Report: All' Peaks ******* *:** ********* ********* Pk. 1 Ret Component , Concentration'-^' ;-' Height.; : /"' Af ea • /Bl;. SDelta' Num 'Time Name Code '•':!' 15.00 ' '• /O.OOO ... 7 ;.1958';" ' 479231 2 2 18.00: ..O.OOO: 12309 .122735.4 .. 2 ."'.. 3 19. 50 •"'...'•';" 0.000 7216 1018438. 2 Totals :": OV'OP'6: '/''•-. 21483 .-. 2725.073 ,. .- D-748, after adsorption on molybdenite, pH 11.3 (soda ash) 0.10 0.08 0.06 i 0.04 !. 0.02 " ' 0.00 . AU -0.02 -0.04 / -0.06 -0.08 -0.10 0 5 10 15 20 25 30 2 Minnhae : : • ' - Figure 111-62: D-748 after adsorption on molybdenite at a pH of 11.3 in the presence of soda ash. The initial D-748 concentration was 75 mg/L. - 105- **************************** Peak. Report: Al1 Pea ks ********************* ***** *-* 'Pk; Ret Component Concentration; .Height .: ' Area. Bl-. ."%'Delta. Num Time Name- :..',.' Code - : 19.42 ' 0.000" 827. '.;"•'' 47355- - i. : ';• ' ;: Totals 0.000 •'. ' 827/.'•'' 47355' "•• ' . D-750, after adsorption on molybdenite, 0.10 pH 4.3 (natural) 0.08 0.06 0.04 0.02 AU 000 -0.02 -0.04 -0 06 : -0.08 :P -0.10 0 5 10 15 20 25 30 • ••• ; MinilteS • : •• •: ' - • •• • • V. Figure 111-63: D-750 after adsorption on molybdenite at a natural pH of 4.3. The initial D-750 concentration was 5 mg/L. **•*******.**.* *.*^ *.*'*•** i *• ***** Peak .Report: ;• All • Peaks'';*^*-*^ ; • :pk.••'••• 'Ret' Component 'V"-.. •Concentration:;:-; .He"ign't': :;; ' A^e.a:V';.:Bl'.;;..%b^lta •;• •'• Num '.Time Name -\ •/:.'" . \'.v ';.; ; Ccide..--- • 1' :15.:7.5: ' "•'•' 0.000.. : 132'. .'• 18093'"; 2 2 .'•17.42 0.000 •'-. •• 11.99'••'••: •-.-'. 97857j.::-.:- 3 : : : vV. ;'3113 :.-":;i9;8-735:::.'-: 4'. •:: 19.33:. •'•:••:: .':.;.;:.•-.:'. •'•-':. i :%r. [i ., 0:. 0 00: i; • • V ; :; '; " 31'4 68 5:.;..:• '•'•i'•":•:. '''.Tbt ai sv: • o ; oca; -: '!•'•?•' 4'444>,; D-750, after adsorption on molybdenite, o.io pH 4.4 (natural) ; .0.08 •! 0 06 • 0.04 j"-,'-' « 3 a S 0.02 i ' t <° 2 AU. 000 f"™ —^ -0.02 j '•'••' -0.04 ; ••' -0.06 ! • .0.10 • |^r-^:--T^r-t--r.-^ 0 5 10 15 20 25 30 Minutes Figure 111-64: D-750 after adsorption on molybdenite at a natural pH of 4.4. The initial D-750 concentration was 30 mg/L. - 106- *:************************** Peak Report: All' Beaks- ***-***v#***#-* Pk. Ret .'Component Concentration'• Helght: . .Area" 81. % Delta" Num Time Name- Code 1- 15.50 0.000 .1239 . 246475- 2" . 2 17.83.. • 0.000. 18339 1655168 . 2'. .'.. 3'- 20.25::; {• 0 .000 .•:.:'.;. .32 37' : •'; .1577867 "• ,." Z!'.':: /Totals .'V./;;.: \0.0<30yy:'-:X D-750, after adsorption on molybdenite, do pH 4.6 (natural) 0.08 0.06 CO 0.04 : CN O 0.02 ; ;^:b:6b. -0.02 i; -0.04 -0.06 -0.08 0 5 10 'IS'/ '•'.•/• 20 : • ""^"O,''• <: 30\ . . : •• •. ... - - •• . : •• • - : - ' • •, •• Minutes.' - . .• • Figure 111-65: D-750 after adsorption on molybdenite at a natural pH of 4.6. The initial D-750 concentration was 75 mg/L. t'+ * * * *.* * ^ *•*-*:* ****** * * ****** peak Report: All Peaks. ************* ************** » Pk.:''' Ret Component ':;• Concentration.. : •': Height':1' '• Area:."Bl'. % Delta'. Num.. Time Name--' ";•'••••. Code : : : '""•r"' 20,17"••;;;'';;;;-'.'•;::•.•• •/ v.' o.o'oo; -:-y •• sep- /.: :..44A2Sj.:i"±}. \- Totals 0.000 880 44425 D-750, after adsorption on molybdenite, o.io pH 11.2 (CaO) 0.08 0.06 , 0 04 - ' 0.02 | ° 0.00 }-^..:-'\ '/. - .',' : ^^.^-^ ' : > AU -0.02 -0.04 -0.06 ; -0.08 j -0.10 j- 0 5 10 : 15 20 25 30 • • • ' .' • • •' • • ". Minntcg Figure 111-66: D-750 after adsorption on molybdenite at a pH of 11.2 in the presence of lime. The initial D-750 concentration was 5 mg/L. - 107- *************************** 'Peak'' Report: All Peaks *******************+******** Pk. Ret Component Concentration . Height . Area, Bl. IDelta Num Time. Name ; Code-' T 19-.6.:. ''.'.'.'.. .;p.000 • .', -.3436: • /2164 78', • .•, • 1'-•'. ' rTotals -V"'.0.000 ' ' 3436- \V- -216478:>,;•' D-750, after adsorption on molybdenite, 0.10, pH 11.2 (CaO) . • v.. o.08 ; 0.06 ! 0.04 : '• . ' ^CO 0.02 i o» AU-0.02 • -0.04 -0.06 ; -0 08 -0.10 10 15 20 25 30 Minutes Figure 111-67: D-750 after adsorption on molybdenite at a pH of 11.2 in the presence of lime. The initial D-750 concentration was 30 mg/L. • ****** * ,*.*•*******.**;**'*'*•**.*;* Beak. Bepbr't:- .All. Peaks ***************** + *******;< '•;Pk.' ' '•:'•;• :Ret: Component.[ ';Cdhcsntrat'ion,:: . '.. .Height; 1 Area-:' Bl..: %-Dei.ta• ;: Niun /'• Time :.Name•'..'"'.'.:.' ..:.'.'.':. .v '••/'•''•V\V. v Code : : ; ; •i' - 17:75 ••: .•'•':'•...:• 'v:. :'',,'''''0.000-' •• 157 ''' '• '' .1218-2 - • • 2 .. .• : y y / ;2::-:a9.58 \:.Z' -:--. ' 0,000 ' v'- 9485;: •.. 7.69263'. 2 Totals ,O.,0Q0: 9642 •' ••.'. '7S;i445\ D-750, after adsorption on molybdenite, o.io pHll.l (CaO) 0.08 0 06 • 0.04 : 0.02 ; AU 000 - -0.02 -0.04 -0.06 ' -0 08 . -010 <~ 10 15 20 25 30 Minutes Figure 111-68: D-750 after adsorption on molybdenite at a pH of 11.1 in the presence of lime. The initial D-750 concentration was 75 mg/L. - 108- *************************** peak Report:' All Peaks to*************.************** Pk. Ret Component. Concentration Height. Area Bl. %Delta Num' Time Name Code. • 1 lb.7 5 . 0.000 . 517 84124 2 2 17.33 '.'•:••:;.':•'. 0.000 16290 1907250 '2 : , 3 . 18.50 : 0.000 ' 31443 28911.89 .2 ' : v. Totals 0.000: .''". 48250 4882563' .... : D-750, after adsorption on molybdenite, 010 pH 11.3 (KOH) 0.08 V;-;-'... 0.06 • : V'' r-^'' - Vv :;-'v'.';. 0 04 krk:' ' 0.02 ***A-*.****'**•*'**.************* Peak Report:'All: Peaks *'******'*********'***"********.* Pk.: ;. Ret Component ;•: :•;'.<:;.'• Concentration. Height' ''.Area Bl •'.;,'. %.p'elta' '• Num .Time Name Code' • 1 ' 15.83 : 0.000 •'•..'. 6.93-..• •-• ''8427.1'.; ... ' ;2: '•• 2 17.33 .• 0.000--..-. 16095:'-. 1799701 "; 2:' 18.50 ::':': .'••'o.oo'6.'': .. 27749' ..: 2456856 2 V ; : : : .":",'V4'.'- '27.33 .':,":":.' .yY'VV.V'0 O.•OO0^• 45'6.::'' :',-'.; 77.59b '-W'l ' : "Totals,,: / ;/.'.;.;>V 0 ;000. '.•'•••••' . 44994.:-;- ";.'44.18418 : D-750, after adsorption on molybdenite, pH 11.2 (soda ash) '0.10 ..: 0.08 0.06 i' . « 0.04 St in. 0.02 • - / AU-0.02 ! : -0.04 I -0.06 I ."' -0.08 -0.10 • 0 '-. 5 "" 10 15 20 25 30 , ••. . : - •• ..•••:•.•..•'.'• Minutes • .:...• • • : •• .. •. Figure 111-70: D-750 after adsorption on molybdenite at a pH of 11.2 in the presence of soda ash. The initial D-750 concentration was 75 mg/L. - 109- r + *********** * ***** ******** peak •. Report; All. Peaks' it*************************' Pk./ Ret Component Concentration Height .Area Bl'..: %pelta Num' Time Name..: • Code 2 18.17 O.OOO'-- 988 602£0 '-2 / .•'3.': 1?:V42.;-::;:V./.'//: ;;" 0/000/.' / :. 917 "... ..' 99223 '•'•:'. 2. ,''-.•; '//": '/•.' :•:,':' Totals:':' •- / 0.000// "' .;1905./'.. '.; 159484:/ D-912, after adsorption on molybdenite, 010 pH 4.4 (natural) •'":.''....' 0.08 i .. ' /.,:'•":'/'.'/ ../ 0.06; //:".":- o:.04i:'://'/''V:;'::/.:/''.': • s t s 0.02 | ~ - - -002 : • • • . • •' -0.04 ' •.'':••'• -0.06 1 •••'• ", •: -0.08 .010 - -..„..., 0 5 10 15 20 25 30 Minutes Figure 111-71: D-912 after adsorption on molybdenite at a natural pH of 4.4. The initial D-912 concentration was 5 mg/L. f*******'**.*.*.********.******* peak Report:. All Peaks;. **>*******.* + ********;********| Pk. Ret-Component- .. . Concentration Height Area' Bl. % Delta . Num.-V Time-.-Name.. ? v':..-:-Code,,//•/' • 1 17 92. //," 0.000,: .'•' .. "112 .1219; -"' 2' "/:","' •'" "2" 19.75- /:"/-'::' ' ' . 0.000 .'.:..:•.,,•.•:•.'•: - 3783 • 293001 ; 2/;.//://''•':'•; : ; ///////"••, . /:///••''•/• /;// Totals//'•;". :'///' . P..000;;/,/. //;/ ,3895, /// •: '.::30p2 2;0/; / / D-912, after adsorption on molybdenite, 0.10 pH 4.4 (natural) 0.08 0.06 f- 0.04 0.02 0.00 All -0.02 -0.04 -0.06 -0.08 -0.10 10 15 20 25 30 Minutes Figure 111-72: D-912 after adsorption on molybdenite at a natural pH of 4.4. The initial D-912 concentration was 30 mg/L. - 110- » + * + ***************.********: Peak Report:. • All Peaks Height Area Bl. ,%De,lta- Pk. ' Ret Component • Concentration code:- : Num: time Name . 620. ^ 112112 -, :2-. • 1 17.42' . '-, 0.000 10309- 9744 65:.: 2. • 2 19.67 0-00° .. 10929'. ' 10865.78,.;,,".: ./ :• Totals-' ;: 0.000 D-912, after adsorption on molybdenite, pH 4.5 (natural) 0.10 . f \ / 0.08 | 0.06 ; 0.04 i * 19,6 7 0.02 •~'V.'- •:-''i\'''-:';' :--':'••• F'- • F::.: QQO.}_•_.„•:•_ __..;„,__;_:^^—— AU -0.02 -0.04 -0.06 -0.08 • -0.10 - -- —rrf-T^T^^r: -; -' - •• '•': ; 0 5 10 15 20 25 30 Minutes Figure 111-73: D-912 after adsorption on molybdenite at a natural pH of 4.5. The initial D-912 concentration was 75 mg/L. .#****»*+.*•****'•*''***«•*'*•****-.peajc Report:- All' Peaks Pk.: Ret Component ;: Concentration Height ' , Area. Bl. %Delta Co( e ; 1 Num. - Time Name- .:'•'-• .':-• ":' i ;''... ' • •.I'v 20.17 . ;'.'"••"b-: '•• 0.006. .:.'•' "89.6-'.' -47898 :.!'; : : ; •Totals - ;: O.obo \--v- ''896; • ;-..-.•'. 4 7.8; 98 ; _|:...,-:;;! ;:;y. :•*:•'• D-912, after adsorption on molybdenite, 0.10 pH 11.3 (CaO) 0.08 • 0.06 [• 0.04 ( ... I 0.02 ' ° ' ••' • 0.00v AU-0.02 -0.04 j -0.06 ! -0.08 j -0.10 -T^l-T^T^^ 5 10 15 20 25 30 Minutes Figure 111-74: D-912 after adsorption on molybdenite at a pH of 11.3 in the presence of lime. The initial D-912 concentration was 5 mg/L. - Ill - ...*«»»**»*«**»*•*••*•«*«** + Peak Report: All Peaks ****************************! v : - Area -•Bl. %Delta. Pk, vRet-: Component.- ' Concentration • Height- Code Num Time Name 1 1/.42 G.000 5y i > 233658 2 19.67 0.000 3183: Totals •• 0.000 3689 295718 D-912, after adsorption on molybdenite, 0.10 pH 11.2 (CaO) 0.08 0.06 0.04 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 10 15 20 25 30 Minutes Figure 111-75: D-912 after adsorption on molybdenite at a pH of 11.2 in the presence of lime. The initial D-912 concentration was 30 mg/L. ******* **************** *.*• .*•*»•.*»***•**•.**•***»«**« Peak Report: All Peaks *** Area Bl. %Delta pk. Ret Component Concentration Heiqht Code Num Time Name 0.000 41 1262 2 1 18.08 500318 2 2 19 . 67 0.000 7995 501580 Totals 0.000 8036 D-912; after adsorption on molybdenite, 0.10 pH 11.1 (CaO) 0.08 0.06 0.04 o o> 0.02 0.00 AU -0.02 -0.04 -0.06 -0.08 -0.10 0 10 15 20 25 30 Minutes Figure 111-76: D-912 after adsorption on molybdenite at a pH of 11.1 in the presence of lime. The initial D-912 concentration was 75 mg/L. - 112- ****** + *******************. Peak-Report: All peaks •***""".""" pk.' Ret Component Concentration , Height .• Area Bl. * Delta' Code Num Time Name : 16.00- : 0 000. V'- .24. . 2895 2' 17.33' 0 000 1332 185302 2 19.58 0 ooo : 14155 1209058 .2 .27.50. 0 000 ;:• 448 83795 ' 1 Totals .'•0 .000 • 15959 ' 14 81050. : D-912, after adsorption on molybdenite, pH 11.3 (KOH) 0.10 , 0.08 , 0.06 j 0.04 | g 0.02 • 0.00 AU -0.02 -0.04 l -0.06 \ -0.08 ' -0.10 - 0 10 15 20 25 30" Minutes Figure 111-77: D-912 after adsorption on molybdenite at a pH of 11.3 in the presence of KOH. The initial D-912 concentration was 75 mg/L. kr * * * ** * # # +1 • *'*'* *•!* t * *• * * ?•*> %* Peak'Report: -All. Peaks. ».«•**» • Concentration:.-.. Height Area'! Bl..%Delta pk-. Ret. Component '- :. Code : Num' . Time Name:"; . 21 ' 1820'- 16.08, ' 0.000:: 0.000 . 1086 173685 17 .3.1 1281890: 19.50' 0;000: 14600 •-14573.95:- Totals; ': b".-00'6; ••:.i57'08/ D-912, after adsorption on molybdenite, at pll 11.2 (soda ash) 0.10 008 0.06 s 0.04 o *7 - *— 0.02 0.00 AU :o.02 • 0.04 -0.06 • -0.08 • -0.10 , 0 10 15 20 25 30 . Minutes Figure 111-78: D-912 after adsorption on molybdenite at a pH of 11.2in the presence of soda ash. The initial D-912 concentration was 75 mg/L. - 113 - Appendix IV: Xanthate Concentrations from Chalcopyrite Adsorption Tests The table below summarize the xanthate concentrations in equilibrium with chalcopyrite upon completion of the adsorption tests. Note that LS stands for lignosulfonate, and nat stands for natural pH values. Table IV-1: Summary of xanthate and lignosulfonate concentrations in equilibrium with chalcopyrite. Xanthate LS LS Initial Equilibrium LS initial Equilibrium Equilibrium type: pH reagent pH pH concentration Concentration Concentration 619 none nat 5.6 10.10 0 3.02 619 none nat 5.69 24.67 0.08 4.73 619 none nat 5.66 49.88 0.17 8.15 619 none nat 5.41 74.94 0.15 13.52 619 none nat 5.75 74.38 0.00 15.33 619 none nat 5.82 98.62 0.00 32.17 619 CaO 11.54 11.11 10.16 6.47 1.45 619 CaO 11.54 11.11 25.06 7.29 3.76 619 CaO 11.54 11.07 49.77 7.01 7.94 619 CaO 11.54 11.07 72.40 6.48 13.01 619 CaO 11.54 11.06 100.40 10.71 23.99 619 Na2C03 11 10.63 51.32 7.68 51.32 619 KOH 11 11.19 49.94 6.98 37.41 648 none 5.07 5.09 10.00 0.00 2.62 648 none 5.07 5.11 25.13 0.00 4.63 648 none 5.07 5.18 50.16 0.36 11.79 648 none 5.07 5.22 75.13 0.20 18.55 648 none 5.07 5.28 99.92 0.93 35.03 648 none 5.07 5.33 125.06 0.49 54.40 648 CaO 11.55 11.08 25.05 6.39 7.48 648 CaO 11.55 11.05 49.96 6.01 11.22 648 CaO 11.55 11.03 75.08 6.21 19.46 648 CaO 11.55 11 100.09 6.33 30.71 648 CaO 11.55 10.98 125.06 6.33 44.92 648 Na2C03 11.07 10.84 50.19 4.15 50.19 648 KOH 11.55 11.25 50.13 5.96 50.13 701 none 5 5.21 25.02 0.08 5.89 701 none 5 5.25 49.90 0.00 12.67 - 114- Xanthate LS LS Initial Equilibrium LS initial Equilibrium Equilibrium type: pH reagent pH pH concentration Concentration Concentration 701 none 5 5.31 75.01 0.00 19.50 701 none 5 5.34 96.81 0.09 29.15 701 none 5 5.33 100.08 0.08 32.12 701 none 5 5.44 124.76 0.00 41.33 701 CaO 11.55 11.12 25.24 6.72 6.09 701 CaO 11.55 11.12 50.11 5.89 12.22 701 CaO 11.55 11.1 74.94 7.01 18.30 701 CaO 11.55 11.09 99.85 6.94 29.47 701 CaO 11.55 10.89 124.97 3.81 46.91 701 Na2C03 11.12 10.87 50.72 7.86 41.15 701 KOH 11.4 11.06 " 49.90 6.55 24.62 748 none 5 5.07 9.99 0.27 1.93 748 none 5 5.1 24.99 0.44 2.37 748 none 5 5.13 49.96 0.94 4.45 748 none 5 5.17 74.90 1.41 14.78 748 none 5 5.22 100.11 0.69 32.18 748 none 5 5.22 124.98 0.00 50.25 748 CaO 11.55 11.05 24.93 4.50 7.47 748 CaO 11.55 11.03 49.96 5.18 8.39 748 CaO 11.55 10.99 75.00 5.00 12.83 748 CaO 11.55 10.95 99.85 4.75 29.67 748 CaO 11.55 10.91 125.02 4.42 54.28 748 Na2C03 11.06 10.8 50.08 5.43 50.08 748 KOH 11.56 11.33 50.02 5.83 36.79 750 none 5.01 5.05 9.97 0.27 1.42 750 none 5.01 5.12 25.00 0.00 5.36 750 none 5.01 5.16 49.92 0.00 20.54 750 none 5.01 5.26 74.88 0.00 33.26 750 none 5.01 5.35 100.71 0.00 34.97 750 none 5.01 5.51 127.20 0.00 53.33 750 CaO 11.55 11.12 9.96 6.25 1.22 750 CaO 11.55 11.15 25.24 6.19 6.07 750 CaO 11.55 11.12 50.08 4.25 15.53 750 CaO 11.55 11.1 74.93 2.32 29.58 750 CaO 11.55 11.07 100.02 1.24 35.30 750 CaO 11.55 11.03 124.95 0.00 56.06 750 Na2C03 11.08 10.8 50.13 0.00 50.13 - 115- Xanthate LS LS Initial Equilibrium LS initial Equilibrium Equilibrium type: pH reagent pH pH concentration Concentration Concentration 750 KOH 11.51 11.14 50.04 0.00 50.04 912 none nat 5.32 25.16 0.10 5.76 912 none nat 5.38 49.87 0.00 10.72 912 none nat 5.36 75.10 0.00 18.06 912 none nat 5.39 99.89 0.36 28.62 912 none nat 5.43 125.20 0.13 41.03 912 CaO 11.5 10.93 25.26 5.96 5.67 912 CaO 11.5 10.89 50.07 5.79 10.09 912 CaO 11.5 10.85 75.04 6.03 19.05 912 CaO 11.5 10.79 104.58 5.37 27.04 912 CaO 11.5 10.75 125.06 5.35 32.60 912 Na2C03 11.1 10.81 50.62 8.77 34.19 912 KOH 11.5 11.27 49.86 9.11 27.54 - 116- Appendix V: Electro-acoustic Measurements on Chalcopyrite The plot below shows the results of electro-acoustic measurements taken on the adsorption chalcopyrite used in these tests. As seen below, the KOH adjusted sample becomes more and more negatively charged as pH increases. The same cannot be said for the CaO adjusted sample, which goes through an isoelectric point at pH of 10.5, and becomes positively charged. 4 6 8 10 12 pH Figure V-l: Electroacoustic measurement of chalcopyrite, using KOH and CaO. - 117 -