Electrochemical flotation of sulfides: Reactions of chalcocite in aqueous solution

Walker, G. W.; Stout, J.V.; Richardson, Patricia A.

doi:10.1016/0301-7516(84)90022-x

Cited by 55 publications

(10 citation statements)

References 6 publications

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“…In acidic solution, an almost monolayer coverage of adsorbed oxygen, water and hydroxide groups was found. While, in neutral and basic solutions, the surface consisted mainly of copper(I) and copper(II) hydroxides and of some copper(II) carbonate, which is generally consistent with previous studies by Walker et al (1984). The amount of these products increased with the pH of the solution.…”

Section: Chalcocite Oxidation and Flotationsupporting

confidence: 90%

“…Most of these species are hydrophilic, which is believed to be the main reason why chalcocite shows a significantly lower floatability than chalcopyrite in the absence of collectors. Sulphur rich surfaces may be formed at some conditions, which may increase the hydrophobicity, as reported by Walker et al (1984), however, it has not been confirmed by surface analysis techniques. …”

Section: Chalcocite Oxidation and Flotationmentioning

confidence: 82%

“…Similar to pyrite and chalcopyrite discussed in the previous sections, the state of the oxidized chalcocite surface influences the surface hydrophobicity and the adsorption process of the flotation reagent and hence the mineral floatability. Walker et al (1984) Hayes et al (1987), borate ions can form complexes with frothers, and influence the floatability of minerals. Therefore, it is important to take proper precautions to ensure that it is not a contributor to the apparent hydrophobicity of the system.…”

Section: Chalcocite Oxidation and Flotationmentioning

confidence: 99%

“…The oxidation species of chalcocite at alkaline conditions include Cu(OH)2, metal-deficient sulphide or polysulphide, elemental sulphur, and sulphur species of higher oxidation state, such as sulphate (Walker et al 1984). Metal-deficient sulphide, elemental sulphide and polysulphide are hydrophobic, and improve chalcocite floatability.…”

Section: Oxidation Of Mineral Surfacesmentioning

confidence: 99%

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The effect of regrinding chemistry and particle breakage mechanisms on subsequent cleaner flotation

Chen¹

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Regrinding rougher flotation concentrates is typically used to liberate valuable minerals from gangue prior to the cleaner separation stage in processing of low grade ores. Compared to the rougher flotation after primary grinding, it is usually more challenging to achieve a satisfactory performance in post-regrind cleaner flotation especially when fine particles are generated. One main factor which results in this reduction in flotation is the unsuitable particle surfaces produced after regrinding. However, this factor is not usually considered when designing and optimizing the regrinding process.Extensive studies have demonstrated that grinding chemistry can influence mineral floatability.However, earlier studies focused on primary grinding and rougher flotation rather than regrinding and cleaner flotation. In addition, different types of regrind mills are used in industry, and these provide different particle breakage mechanisms which may also influence mineral floatability.Therefore, the overall objective of this thesis study is to investigate the effects of regrinding chemistry and particle breakage mechanisms on the cleaner flotation. The implementation of regrinding in the copper and pyrite flotation circuits at Telfer gold mine was taken as a case study and four research areas were addressed with the objective of developing fundamental understanding to provide practical guidance for the plant operation. The four areas investigated are:1. Effect of regrinding chemistry on copper activation of pyrite and its flotation; 2. Separation of different copper sulphide minerals from pyrite after regrinding; 3. Importance of pulp chemistry during regrinding rougher concentrates; 4. Effect of particle breakage mechanisms on subsequent flotation.In this study, it was found that copper activation of pyrite and its flotation in the cleaner stage were affected by regrinding. In general, a decrease in surface concentration of collectors due to the increased surface area after regrinding contributed to the low pyrite recovery in the cleaner. Surface analysis revealed that both the surfaces that were carried from the rougher flotation concentrate and those which were freshly created were modified by the strong electrochemical reactions occurring inside the regrind mill. Stainless steel media promoted pyrite oxidation, especially on the copper activated surfaces. Mild steel media produced a greater amount of iron oxidation species which could adsorb on the carried surfaces. It was also found that mild steel media generated a reducing condition which favoured the copper activation on the freshly created surfaces.ii The research has also shown that the separability of chalcopyrite and chalcocite from pyrite was significantly different after regrinding, which was related to their electrochemical properties.Chalcocite was more active and therefore presented a stronger galvanic interaction with pyrite.Consequently chalcocite was more oxidised, which not only depressed its flotation but also produced sufficient copper ions...

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Section: Chalcocite Oxidation and Flotationsupporting

confidence: 90%

Section: Chalcocite Oxidation and Flotationmentioning

confidence: 82%

Section: Chalcocite Oxidation and Flotationmentioning

confidence: 99%

Section: Oxidation Of Mineral Surfacesmentioning

confidence: 99%

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The effect of regrinding chemistry and particle breakage mechanisms on subsequent cleaner flotation

Chen¹

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“…Most of the species on chalcocite surface are hydrophilic, which is believed to be the main reason why chalcocite shows a significantly lower floatability than chalcopyrite in the absence of collectors. Sulphur rich surfaces may be formed at some conditions, which may increase the hydrophobicity, as reported by Walker et al (1984), however, it has not been confirmed by surface analysis techniques. Barzyk et al (1981) identified that chalcocite surface oxidation had a strong effect on both xanthate adsorption and chalcocite floatability, and the most oxidized chalcocite sample required 100 times more collector consumption to obtain the same flotation results than the least oxidized sample.…”

Section: Chalcopyrite Flotationmentioning

confidence: 82%

Slime coating mitigation on mineral surfaces in froth flotation by saline water

Zhao¹

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Fine and ultra-fine particle flotation is central to the mining industry as a result of the need to treat low grade and difficult ores which require fine grinding to liberate valuable minerals from gangue minerals. However, the flotation of fine and ultra-fine particles is not efficient and a slime coating with slime gangue particles attaching to valuable minerals is one of the most popular barriers. A slime coating prevents the adsorption of collectors on the surface of valuable minerals resulting in low flotation recovery or low product quality.Saline water is also an important issue in the mining industry. In Western Australia, bore water with a high ionic strength has to be used at mine sites for production, site rehabilitation, and downstream processing because fresh water is not available locally. In Queensland, most mine sites have adopted water re-use as a means for making freshwater savings. However, water re-use results in increased salinity in site water stores, which is driven largely by evaporation and ongoing salt inputs from spoil, minerals and groundwater. Flotation relies on a large amount of water and therefore the impact of saline water on flotation performance has gained more and more attention.In this research, the role of saline water in the mitigation of slime coatings was studied and a generic approach to improve fine and ultra-fine particle flotation by using saline water was developed, building on the previous research. A model slime coating system was established by using copper minerals in the presence of clay particles. It was found that chalcocite flotation was depressed in the presence of bentonite slimes while chalcopyrite flotation was less affected.Electrostatic interactions between copper minerals and clay particles were found to be responsible for the different flotation of chalcocite and chalcopyrite in the presence of clay minerals. It was found that surface oxidation occurred during II grinding and changed the surface properties of chalcopyrite and chalcocite.Chalcocite was strongly oxidized while chalcopyrite was slightly oxidized after the grinding with stainless steel media. The different extent of surface oxidation resulted in the different electrical property of chalcocite and chalcopyrite surfaces.The strongly oxidized chalcocite surface became positively charged after grinding at the same pH and electrostatically attractive to bentonite particles resulting in the depressed chalcocite flotation. In contrast, the slightly oxidized chalcopyrite surface remained negatively charged after grinding at pH 9.0 and entropically repulsive from bentonite slime particles. Therefore, bentonite slimes did not influence chalcopyrite flotation as much as chalcocite flotation.Mitigation of slime coatings on chalcocite in flotation by using electrolytes was further investigated and kaolinite was used to introduce the slime. The results indicated that in tap water, the presence of kaolinite slimes depressed chalcocite flotation. With the addition of electrolytes to the flotation...

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