Abit et al. obtained a patent for copper - molybdenum separation using an oxidant and inhibitor combination as early as the 1950s.
A commonly used oxidizing agent is sodium hypochlorite (NaOCl) or hydrogen peroxide (H 2 O 2 ). They can be adsorbed to the collector of the oxidized copper surface, and the damage; also the ferrous sodium [Na 4 Fe (CN) 6] doublet of copper oxide, iron sulfide more inhibitory properties Sodium ferricyanide [Na 3 Fe(CN) 6 ]. But the two are different. The practice of the SanManuel plant confirmed that hydrogen peroxide not only oxidizes the collector, but also oxidizes the surface of the chalcopyrite to enhance the inhibition.
The inhibitors compatible with the oxidizing agent are mainly sodium ferrocyanide (yellow blood salt), sodium ferricyanide (red blood salt) and sodium zinc cyanide (Na 4 Zn(CN) 6 ). When combined with an oxidizing agent, they may be used singly or in combination, which is quite effective in suppressing copper minerals mainly composed of chalcopyrite. The suppression of copper minerals dominated by chalcopyrite is worse. At this time, sodium cyanide or Knox Pharmacy must be added.
Sodium zinc cyanide can be added directly, but sodium cyanide and zinc sulphate are often added to form zinc cyanide by the reaction of the two in a flotation medium.
6NaCN+ZnSO 4 =Na 4 Zn(CN) 6 +Na 2 SO 4
Sodium zinc cyanide combines with hydrogen peroxide to produce hydrocyanic acid and removes the collector film from the mineral surface.
The South Peruvian Copper Company's Tokpara Copper and Molybdenum Concentration Plant concentrates the concentrate to 55% to 60% and then adds sodium hypochlorite when separating copper and molybdenum mixed concentrate containing 31% copper and 0.3% molybdenum. Sodium ferrocyanide slurry. Prior to sorting, the pH of the slurry was adjusted to 7.0 to 8.6 with sulfuric acid. Ferrocyanide before joining the pulp had been oxidized iron sodium hypochlorite, in order to suppress the amount of dressing 85% to 90% by mass, both agents are necessary, so are easy to be suppressed chalcocite . Add 11.0~2.2kg of sodium ferrocyanide and 0.6~1.3kg of sodium hypochlorite per ton of mixed concentrate. Tokpara adds them to the rough selection and the first three selections. In the next few selections, a mixture of sodium cyanide and zinc sulfate was added, and the two were mixed after 2:1 to form zinc sodium cyanide. Not only does it inhibit chalcopyrite well, but the pH of the pulp is also lower than that of sodium plus sodium cyanide, which makes the foam better and the amount of gangue inclusions reduced. Tokpara uses a sodium hypochlorite-sodium ferrocyanide process to obtain a flotation molybdenum concentrate containing NoS 2 87% and containing 1.2% copper. In order to obtain high-quality molybdenum concentrate, they added a new process of sodium cyanide leaching to the flotation molybdenum concentrate to further remove copper (impregnated copper ore).
In the US by-product molybdenum mine, St. Manuel is second only to Utah Bingham. The copper-molybdenum mixed concentrate containing 28% copper and 0.95% molybdenum was first concentrated and removed to 55% solids. The crude molybdenum is controlled by hydrogen peroxide-zinc cyanide to inhibit copper minerals. The molybdenum is selected by sodium hypochlorite-sodium ferrocyanide to further suppress copper, and the third time is to add sodium ferricyanide. After six times of selection, the flotation molybdenum concentrate containing MoS 2 85 %~92% and containing 1% copper was obtained, and then the cyanide leaching was carried out to reduce the copper in the molybdenum concentrate to less than 0.5%.
In St. Manuel, the oxidants and inhibitors are not added at the same time, but separately. Roughly select the first stirred tank plus zinc cyanide, the second plus hydrogen peroxide; the first selection of sodium ferrocyanide, the second selection plus sodium hypochlorite, the third selection Add sodium ferricyanide. Davyd believes that sodium zinc cyanide is a stripping agent for collectors. It is first added to cyanide the surface of the chalcopyrite, and hydrogen peroxide is used to maintain the redox potential required for cyanide stability.
Oxidizer plus inhibitors are also used as an effective means for the separation of copper-molybdenum. However, due to the strong corrosive nature of the oxidant, this process has not been widely promoted.
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