A Review of Recent Advances in Depression Techniques for Flotation Separation of Cu–Mo Sulfides in Porphyry Copper Deposits

Abstract

Porphyry copper deposits (PCDs) are some of the most important sources of copper (Cu) and molybdenum (Mo). Typically, the separation and recovery of chalcopyrite (CuFeS2) and molybdenite (MoS2), the major Cu and Mo minerals, respectively, in PCDs are achieved by two-step flotation involving (1) bulk flotation to separate Cu–Mo concentrates and tailings (e.g., pyrite, silicate, and aluminosilicate minerals) and (2) Cu–Mo flotation to separate chalcopyrite and molybdenite. In Cu–Mo flotation, chalcopyrite is depressed using Cu depressants, such as NaHS, Na2S, Nokes reagent (P2S5 + NaOH), and NaCN, meaning that it is recovered as tailings, while molybdenite is floated and recovered as froth product. Although conventionally used depressants are effective in the separation of Cu and Mo, they have the potential to emit toxic and deadly gases such as H2S and HCN when operating conditions are not properly controlled. To address these problems caused by the use of conventional depressants, many studies aimed to develop alternative methods of depressing either chalcopyrite or molybdenite. In this review, recent advances in chalcopyrite and molybdenite depressions for Cu–Mo flotation separation are reviewed, including alternative organic and inorganic depressants for Cu or Mo, as well as oxidation-treatment technologies, such as ozone (O3), plasma, hydrogen peroxide (H2O2), and electrolysis, which create hydrophilic coatings on the mineral surface.

The Effects of Coexisting Copper, Iron, Cobalt, Nickel, and Zinc Ions on Gold Recovery by Enhanced Cementation via Galvanic Interactions between Zero-Valent Aluminum and Activated Carbon in Ammonium Thiosulfate Systems

“…There are surely mines containing high Au concentrations such as 150 g/t in Australia [16], 94 g/t in Korea [17], and 60 g/t in China [18], but those mines with high Au contents have been actively explored; hence, currently operating/investigating mines mainly deal with refractory or complex ores with relatively low Au concentrations such as 6 g/t in Laos [19], 6.2 g/t in China [20], 6.2 g/t in Iran [21], or 11.2 g/t in Ghana [22]. Furthermore, Au ore contains minerals such as pyrite, arsenopyrite, chalcopyrite, and/or malachite in which various elements (e.g., Cu, Fe, Co, Ni, and Zn) are incorporated [23][24][25][26][27][28]. Once these elements are dissolved in the solution, they can affect Au recovery by competing and/or co-depositing with Au during the recovery process.…”

“…Cu ions are an essential catalyst in ammonium thiosulfate systems, increasing Au dissolution in ammonium thiosulfate systems 20-to 25-fold (Equation ( 1)) [1,4]; • Cu ions could be introduced via the dissolution of Cu minerals such as chalcopyrite and malachite [23][24][25][26][27][28] found in Au ores.…”

Enhanced Flotation Recovery of Fine Molybdenite Particles Using a Coal Tar-Based Collector

“…[1,2]. Molybdenite is the principal mineral in molybdenum extraction, and it is recovered from Mo-Cu ores or molybdenum ores using the froth flotation technique [3][4][5]. However, molybdenite is an anisotropic mineral with two types of surfaces.…”

Flotation Separation of Chalcopyrite and Molybdenite Assisted by Microencapsulation Using Ferrous and Phosphate Ions: Part I. Selective Coating Formation

“…After this, the Cu-Mo bulk concentrates are treated with chalcopyrite depressant (e.g., sodium hydrosulfide (NaHS), sodium sulfide (Na 2 S), and Nokes reagent (P 2 S 5 + NaOH)) in order to depress chalcopyrite while floating molybdenite [5]. These reagents function as chalcopyrite depressants by producing HSthat desorbs the adsorbed xanthate on the chalcopyrite surface and/or reduces the pulp potential, in which chalcopyrite does not float [7].…”

“…Although the conventional chalcopyrite depressants are effective in separating Cu and Mo minerals from bulk Cu-Mo bulk concentrates, these have the potential to generate toxic hydrogen sulfide gas (H 2 S (g) ) when pulp pH is not properly controlled [3,5,8]. At a pH below 10, for example, H 2 S (aq) species starts forming and it is readily vaporized due to its high vapor pressure [7]. Thus, the flotation circuits should consist of covered flotation cells with an active ventilation system to avoid the accident that is caused by H 2 S emission [5,7,9].…”