SEPARATION OF Ni, Co AND Cu IN PILOT-SCALE CUPROUS AMMONIA LEACHING SOLUTION OF OCEAN POLYMETALLIC NODULES

摘要

In the cuprous ammonia leaching solution of polymetallic nodules, the main metal values are Ni, Co and Cu, while hte contents of Fe, Mn, Si and Ca are low. In this paper, LIX84 is adopted to extract and separate Ni, Co and Cu from ammonia media. Cu and Ni are coextracted via five stages of countercurrent extraction, while cobalt remains in the raffinate. The organic phase loaded with Ni and Cu is scrubbed to remove the entrained ammonia. The spent nickel electrolyte is used to strip selectively nickel via seven stages of stripping, and achieve primarily the separation of Ni from Cu. The stripped organic phase is then stripped to produce a pure copper sulphate solution. The Ni strip liuor contains small amount of copper, which is subjected to extraction with Lix84 again to separate Ni and Cu completely. The separation of Ni,Co and Cu from ammonia media, thus ,has been achieved with one solvent reagent. The pilot test result indicates that good separation and high metal recovery can be obtained via this process 99.02%Ni, 99.67%Co and 99.97%Cu can be recovered.