Industrial Test, Vacuum Refining Of Crude Cadmium

The cadmium in earth's crust content is 2 ×10^-5%, when nature all take compound form existence, essential mineral as greenockite(CdS), with zinc ore, lead-zinc mine, copper lead-zinc mine para genesis, flotation process majority of enters the zinc ore concentrate, concentrates in the roasting process in the mist and dust. Builds up the hydrometallurgy of zinc, the cadmium exists in the copper cadmium dregs. 95% cadmium are approximately recycles from the zinc production process, therefore the cadmium is the zinc lead production sideline product.Along with the vacuum technique development, the vacuum metallurgy has the good application prospect. The non-ferrous metal vacuum metallurgy technology uses each kind of metallic element the gasification and the condensation heterogeneity, achieves the metal depuration and the alloy various components separation goal. The vacuum refining thick metal, has the flow short, consumes, the metal returns-ratio few is high, basically does not have the three wastes (waste residue, waste water, waste gas) does not have the pollution, the initial cost province, the processing charge low status characteristic to the environment, enables it to have the very good prospects for development.In the thick cadmium impurity element mainly has Pb, Zn, Ni, Cu, Fe, Sn, Sb, Tl, As and so on, the cadmium boiling point is low, has high steams the barometric pressure, through calculates when the thick cadmium distillation impurity detached coefficient and separation degree, when distillation Pb, Ni, Cu, Fe, Sn, Sb, Tl, As and so on can separate well with the cadmium, the impurity very little volatilizes, keeps in the remaining alloy, the cadmium volatility enters the gas phase, in has the water cooling wall the condensation to cover the condensation to get down, Zn when evaporating has the part to enter the distillation cadmium, Passable per alkaline fining except that. The cadmium in the temperature 450 ℃, under the vacuum degree 20MPa condition has high evaporates the speed, in 300 ℃ under can the condensation be the solid. Therefore, vacuum distillation thick cadmium in theoretically feasible, the operating condition is also easy to realize.According to the Northwest Lead Zinc Smelter actual situation, uses level of distillation, a level receives the dust, the intermittent working technical process, the equipment investment province, does not have the pollution, the operation is simple, the distillation cadmium which delivers besides Zn, other impurities conform to the quality requirement, the process alkalinity fining except Zn, the final product achieves 1 (99.99%) the above fine cadmium quality specification.After the commercial test, the Northwest Lead Zinc Smelter took the finecadmium to the thick cadmium vacuum distillation system to accumulate the certain production practice experience. The aqueous method produces the thick cadmium and the vacuum distillation two simple operating processes, may guarantee the production quality qualified product, to operator's technical level not special request, the process monitor and the control is not complex, can be able to withstand the foreign inclusion undulation, the operational site hygienic condition well, the cost is low. After the investment movement, may create the considerable economic efficiency.