High purity molybdenum concentrate production method

Flotation molybdenum concentrates from copper-molybdenum processing plants usually contain more than 0.5% copper, and the lead and calcium oxide content often exceeds the standard. Molybdenum processing plant output flotation molybdenum concentrate containing impurities, sometimes also difficult to meet the high quality standards.

In order to produce high-quality high-purity molybdenum concentrate, common production processes are as follows.

I. Enhanced beneficiation

Canadian Endeco obtains two kinds of products in the selection process: high-quality molybdenum concentrate containing 56.88% molybdenum and ordinary molybdenum concentrate containing 51% molybdenum. Beijing Tianhe Chemical Plant adopts flotation column for molybdenum concentrate to carry out seven-stage open-circuit flotation, and while obtaining high-quality molybdenum concentrate (containing 97% MoS, molybdenum recovery rate of 37%), a part of molybdenum intermediate ore is also produced. El Salvador used nine-stage concentration to separate a high-quality molybdenum concentrate (97% MoS2 and 65% molybdenum recovery) from a conventional molybdenum concentrate, while also producing a portion of ordinary molybdenum concentrate. Using TL chemicals to enhance flotation, from the molybdenum concentrate containing 47% molybdenum, to produce high-quality molybdenum concentrate containing 57%~58% molybdenum, molybdenum recovery ≥ 97%, while also producing a small portion of molybdenum in the middle of the ore (Mo ≤ 2%).

Hydrochloric acid leaching

Hydrochloric acid leaching can be used when the flotation concentrate contains high CaO and PbS. Common calcium-containing minerals for calcite (CaCO3), followed by fluorite (CaF2). They do not float easily by themselves and usually go into the molybdenum tailings. However, hyphenated bodies, contaminated by oil and medicine or mechanical inclusions and other reasons, often a small amount of molybdenum concentrate, so that its CaO content exceeds the standard.

III. Chlorine salt leaching

Chlorine leaching is the use of high oxidation performance of FeCl3 or CuCl2 oxidation of chalcopyrite or galena:

CuFeS2+4FeCl3=CuCl2+5FeCl2+2S

PbS+2FeCl3=PbCl2+2FeCl2+S

Fe3+ ions oxidize the sulfide and precipitate S at the standard potential Eo(V) of:

Sulfide FeS ZnS CuFeS2 FeS2 Cu2S CuS

E0(V) 0.06 0.264 0.264 0.42 0.56 0.59

In fact, the order of difficulty of leaching sulfide minerals is: magnetite pyrite < chalcopyrite < galena < sphalerite < chalcopyrite < pyrite. In addition to ferric chloride or copper chloride in the leaching solution, it is often necessary to add chloride salts of alkali metals (such as NaCl) or alkaline earth metal chloride salts (such as CaCl2), which can not only increase the boiling point of the leaching solution, so that the leaching can be carried out at a high temperature of 100 ~ 110 ℃; but also provide a large number of Cl- ions for the PbCl2, CuCl, so that insoluble PbCl2, CuCl to generate soluble complex ions into the liquid phase, Cu, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb, Pb and PbCl. liquid phase, Cu, Pb leaching can be realized:

PbCl2+Cl-→ PbCl3-

CuCl+Cl-→ CuCl2-

HCI is also added to the leach solution to maintain a certain acidity. Chlorinated leaching of molybdenum concentrate has long been implemented in Brenda, in production. The process is also often called the Brenda method. The Brenda copper-molybdenum mine is a worldwide low-grade copper-molybdenum plant, the raw ore contains 0.183% copper and 0.049% molybdenum. The copper minerals in the ore are mainly chalcopyrite. The flotation molybdenum concentrate from Brenda averaged 54.97% molybdenum, 0.32% copper and 0.38% lead (1974). Obviously the copper and lead content are high, in 1974 Brenda processing plant adopted the Noranda company research center research of the chlorine salt leaching process, the molybdenum concentrate grade rose to 55.89% Mo, 0.054% Cu, 0.033% Pb. Its high quality at that time is rare in the world. The leaching solution formula is usually: CuCl2 1%, FeCl3 10%, CaCl2 (or NaC1) 30%, HCl 10%. Leaching is carried out under atmospheric pressure and temperature, and the leaching temperature is usually controlled at 100~110℃. The leaching is intermittent operation, each time 2~3 h. After leaching, CuCl2- and PbCl3- are separated by filtration. The filtrate contains the reaction products CuCl2, PbCl3, FeCl2..., and also contains unfinished chemicals. Usually 30% of the filtrate is discarded to avoid the accumulation of Cu, Pb, etc. in the leach solution, and the rest of the filtrate is passed through chlorine gas to regenerate FeCl2 into FeCl3 and then recycled. The leaching cost is about 9~11 cents/kg molybdenum, and the selling price is increased by 95 cents/kg molybdenum. Brenda's annual profit increase is about US$3 million.