| 摘要 |
<p>The recovery of Ni, Co, Zn and/or Cu from sulphate solns. contg. them is carried out by simultaneously introducing H2S and a calceferous base into the soln. in amts. such that the dissolved metal is pptd. as sulphide at the same time as CaSO4 is pptd., maintaining the soln. at a pH of 2.5-3.5, and subjecting the ppte. to forth flotation to isolate the sulphides. The process can be used to isolate the metals from sulphate solns. obtd. by oxidising sulphide ores. Inexpensive lime (limestone, qicklime or slaked lime) is used; good sepns. can be achieved in large-scale operations (e.g. with >99% of the metal recovered in the concentrate). A suitable starting soln. contains 5-50 g Ni/1. Pptn. is pref. effected at 40-80 degrees C (esp. 50-75 degrees C) using limestone. In a continuous process, pptn. is effected in a series of tanks through which the soln. is circulated in countercurrent to the H2S, the lime being added to each tank so as to maintain a pH of 2.5-3.5. After pptn., the mixt. is pref. degassed by reducing the ambient pressure, the H2S-risk gas obtd. being recycled to the pptn. step. The mixt. can then be concd. to form a thick slurry, or the ppte. can be filtered off and slurried in H2O. Flotation is pref. effected in the presence of a sulphhydryl collector, e.g. K amyl xanthate.</p> |
