FLOTATION OF MINERAL MATERIALS

1. FLOTATION OF MINERAL MATERIALS

2. Class 2. Native metals and sulfides A) Metals occurring in nature: iron, mercury, copper, gold, platinum B. Sulfides lead (galena, PbS) copper (chalcocite, covellite, chalcopyrite, bornite) silver (argentite) zinc (sphalerite)

3. Class 2. Native metals and sulfides A) Metals occurring in nature: iron, mercury, copper, gold, platinum flotation with sulphydryl collectors (5 or more CH2 groups) dithiophosphates as well as xanthate + mercaptobenzothiazole, and dithiophosphate+ mercaptobenzothiazole mixtures can be used for flotation electrochemical character of adsorption of sulphydryl collectors on the surface of metals

4. Solubility products of metal xanthates(after Aplan and Chander, 1988)

5. Class 2. Native metals and sulfides B. Sulfides lead (galena, PbS) copper (chalcocite, covellite, chalcopyrite, bornite) silver (argentite) zinc (sphalerite)

6. Collectors for flotation of sulfides

7. sulphides hydrophobization mechanism is complex and not well understood because there are many reactions between sulphide and sulphydryl collectors Woods (1988) and others: hydrophobization of sulfides with sulphydryl collectors results from electrochemical reactions electrons are transmitted from a collector to a sulfide mineral (anodic process), and then the electrons return to aqueous solution due to catodic reduction of oxygen

8. anodic oxidation, mechanism • chemisorbed xanthate Xad created from X- ion coming from • aqueous solution and a metal ion crystalline structure of sulfide: • X– Xad + e • b) dixanthogene X2, as a result of X- ion oxidation • 2X–  X2 + 2e • c) metal xanthate MeX2, due to reaction of X- ion with metal sulfide MS • 2X– + MS  MX2 + S + 2e • elemental sulfur Scannextform thiosulfate, sulfate(IV) or sulfate(VI) • 2X– + MS + 4H2O  MX2 + SO4-2 + 8H++ 8e other compounds xanthogenic acid HX, hydroxyxanthates, perxanthates, disulfide carbonates, etc. are possible catodic reduction of oxygen: O2 + 2H2O + 4e = 4OH-

9. Hu at al., 2009

10. Eh–pH diagram for galena + ethyl xanthate. Total amount of xanthate species was 10–4 M. Formation of S is assumed (after Woods, 1988)

11. xanthate flotation of pyrite

12. Galena flotation with ethyl xanthate at pH = 8 as a function of applied potential to a platinum electrode in solution: a – galena kept in oxidizing environment before flotation, b – kept in reducing environment (Richardson, 1995; Guy and Trahar, 1985)

13. Activation reaction of sphalerite with selected metal cations and calculated free enthalpy of the reactions 0 D Activation reaction free enthalpy, (kJ/mol) G r 2+ 2+ ZnS +Fe =FeS+Zn 35.2 2+ 2+ ZnS +Pb =PbS+Zn – 17.3 2+ 2+ ZnS +Cu =CuS+Zn – 62.9 + 2+ ZnS +2Ag =Ag S+Zn – 142.3 2 Free enthalpy of the activation reactions for sulfides reacting with metal ions 2+ 2+ 2+ 2+ + Fe Zn Pb Cu Ag FeS – 35.2 – 52.5 – 98.1 – 177,5 ZnS 35.2 – 17.3 – 62.9 – 142,3 PbS 52.5 17.3 – 45.6 – 125,0 CuS 98.1 62.9 45.6 – 79,4 Cu S 170.7 136.1 118.2 – 6,8 2 Ag S 177.5 142.3 125.0 79.4 2 Complications Activation pyrrhotite (FeS) can be activated with all considered cations (∆Gr0 is negative), sphalerite with all cation except Fe3+, galena (PbS) only with Cu2+, and Ag+ ions.Both copper sulfides can be activated only with Ag+, while argentite (Ag2S) cannot be activated at all (∆G0f is positive). Conclusion:

14. Galvanic effects Bakalarz, Ph.D. thesis 2012, Rao 2004 two sulphides Bakalarz, Ph.D. thesis 2012, Greet et al., 2005 sulphide and Fe grinding medium

15. Rest potentials (SHE) for sulfides at pH=4 (Bakalarz 2012, Ph.D. thesis) formula potential , mV mineral 1 2 pyrite Fe S 660 , 630 2 1 marcasite (Zn, Fe)S 630 2 1,3 2 chalkopyrite CuFeS 560 , 530 2 5 pyrrothite FeS 310 1,3 sphalerite ZnS 460 1 3 covellite CuS 450 , 420 3 1 bornite Cu FeS 400 , 420 5 4 5 pentlandite (Fe,Ni) S 350 9 8 3 1 galena PbS 280 , 400 1,3 argentite Ag S 280 2 2 4 chalcocite Cu S 440 , 310 2 1,3 antymonite Sb S 120 2 3 1,3 molybdenite MoS 110 2 4 heazlewoodite Ni S – 60 3 2 1 – Dettre i Johnson, 1964, za Witika i Dobiasem, 1995 2 – Hiskey i Wadsworth, 1981 3 – Kocabag i Smith, 1985 4 – Bozkurt i in., 1994, za Rao, 2004 5 – Bozkurt i in., 1998

16. galena>bornite>shale>chalcocite >covellite>chalcopyrite chalcopyrite>bornite> covelline >shale>chalcocite, galena model sulfide (5%), dolomite (47.5%) and quartz (47.5%) mixture, flotation with z n-dodecane 200 g/Mg copper ore, n-dodecane 600 g/Mg, 10 min flot. (Bakalarz 2012, Ph.D. thesis Conclusion: flotation of sulfides depends on system

17. Class 3. Oxidized minerals of non-ferrous metals cerussite (PbCO3) vanadinite (Pb5[Cl(VO4)3]) anglesite (PbSO4) malachite (CuCO3·Cu(OH)2 azurite (2CuCO3·Cu(OH)2) chrysocolla (hydrated copper silicate) tenorite (CuO) cuprite (Cu2O) smithsonite (ZnCO3)

18. Class 3. Oxidized minerals of non-ferrous metals Approaches: 1. Sulfidization 2. Flotation using either cationic or anionic collectors (as in the case of oxide-type minerals)

19. Sulfidization reaction -MO + S2- + 2H+ = -MS + H2O Influence of conditions of flotation on recovery of malachite sulfidized with 960 mg/dm3 of Na2S·9H2O in the presence of frother (amyl alcohol 60 mg/l): 1 – flotation when after sulfidization the solution is replaced with pure aqueous, 2 – flotation after 25 minutes of air bubbling through the solution containing sulfide ions, 3 – flotation directly after sulfidization in the presence of sulfide ions (after Soto and Laskowski, 1973) also anionic and cationic collectors can be used (as for oxides and hydroxides

20. Class 4. Oxides and hydroxides Consists of simple oxides (Fe2O3, SnO2), oxyhydroxides (AlOOH) as well as complex oxides and complex hydroxides (spinels, silicates, aluminosilicates).

21. Oleate flotation of oxide and silicates

22. Concentration - pH diagram for sodium oleate aqueous solutionsshowing predominance of various oleate species (Drzymala, 1990): c – activity of oleate species, mol/dm3, B (or ) – degree of binding oleate with sodium ions in associated species (number of sodium ions per one oleate ion in the associate)

23. Comparison of pH ranges of oleate flotation of minerals as well as activated quartz and pH of existence of metal monohydroxy complexes a – Fuerstenau and Palmer (1976), b – Daellenbach and Tiemann (1964). * The participation of FeOH+ ions in widening the pH range of flotation of activated quartz activated with FeOH++ ions cannot be ruled out.

24. Fatty acids adsorption Schematic illustration of modes of adhesion of a colloidal collector (here as an oil drop) to solid surface: a – contactless (heterocoagulation), b – contact, c – semicontact adhesion

25. Zr[SiO4] At high oleate species concentrations flotation decreases even though the oleate adsorption increases. It is assumed that it results from adsorption of hydrophilic micelles (based on data of Dixit and Biswas, 1973)

26. Al2[OSiO4] Kyanite flotation with 10–4 kmol/m3 of fatty acids (Choi and Oh, 1965). Applied acids: laurate (C11H23COOH), linoleic (C5H11–CH=CH–CH2–CH=CH–(CH2)7COOH), linolenic CH3–[CH2–CH=CH]3(CH2)7COOH and oleic (C17H33COOH)

27. Adosrption of oleates on calcium minerals According to Rao and Forssberg (1991), depending on the sign of surface potential and its value for calcium minerals, the following reactions, leading to the formation of mono- and double layers of compounds, take place:  on electrically neutral sites: –CaOH + –OOCR = –Ca+ –OOCR + OH– –CaOH + Na+ –OOCR + OH– = –CaO Na OOCR– + H2O –CaOH + Ca++ –OOCR + OH– = –CaO Ca OOCR– + H2O  on positively charged sites: –CaOH2+ + –OOCR + OH– = –Ca+ –OOCR + H2O  on negatively charged sites: –CaO– Na+ + –OOCR = –CaO Na OOCR, where  < 1, –CaO–Ca++ + –OOCR = –CaO Ca OOCR, where <or = 1.

28. AMINES dissociation/adsorption

29. quaternary ammonium compounds permanetly charged R groups can be alkyl, aryl, the same or different

30. AMINES Equilibrium constants of selected reactions, iep and CMC for dodecylamine in aqueous (after Laskowski, 1988) Diagram of predomination of various forms of dodecylamine as a function of pH of solution (data after Laskowski, 1988)

31. Relationship between quartz flotation with amine and pH. Following good flotation in alkaline solutions there is a drop in flotation as a result of precipitation of coagulating amine. At high pH an increase of flotation is caused by stable of amine suspension (after Laskowski et al., 1988)

32. Flotation of particles increases with increasing concentration of collector in the systemand is proportional to collector adsorption and hydrophobicity caused by the adsorption. Collector adsorption is manifested by the increase of zeta potential of particles (after Fuerstenau et al., 1964 and Fuerstenau and Urbina, 1988), pH = 6–7

33. Amine flotation of quartz

34. Class 5. Sparingly soluble salts

35. NaOl - sodium oleate, DDA-dodecylamine, SDS,- sodium dedecyl sulfite

36. Class 5. Sparingly soluble salts Flotation with potassium octylohydroxymate

37. the same minerals - different flotation response Flotation of sparingly soluble minerals with oleic acid: a – after Finkelstein (1989), natural pH, b – after Parsonage et al., (1982)

38. Influence of different collectors and depressants on barite and fluorite flotation (table after Pradel, 2000 based on Sobieraj, 1985)

39. Influence of depressant (70 mg/dm3 Al2(SO4)3 and 70 mg/dm3 Na2SiO3) on flotation of fluorite and calcite mixture (dashed line) in the presence of sodium oleate (100 mg/dm3) (after Abeidu, 1973). Solid line indicates flotation in the absence of depressant

40. Class 6. Soluble salts

41. Soluble salts

42. depressants are called blinders Application of depressants for removing fines of gangue minerals during amine flotation of KCl (after Alonso and Laskowski, 1999). CMC denotes carboxymethylcellulose PAM - polyacrylamide of low molecular weight, while guar is a natural polysaccharide