Selective Extraction Of Cobalt From Anode Solution In Nickel Electrolyte

The high purity nickel electrolyte demand has recently risen due to its promising use in super-alloys, electroplating technology, petrochemical engineering, catalysts and rechargeable batteries, etc. In addition, cobalt is more expensive than nickel and the waste of cobalt resource in nickel electrolyte makes direct economy losses. So cobalt recovery from nickel containings is necessary as a by-product of the seperation of nickel.But the recovery is particularly difficult because of their similar properties in aqueous medium. Solvent extraction is being applied in the industry to separate and purify metals such as nickel, copper, cobalt, and zinc from each other and from other impurities. As the process is simple, it is mainly used in analysis and separation.In the present study, the extraction of cobalt from the anode solution in nickel electrolyte using the sodium salt of PC-88A, Alamine336 and organophosphorus mixed extractants diluted in sulfonated kerosene as extractant were investigated. The effect of modifier, concentration of solvent in organic phase, phase ratio, equilibrium pH, equilibrium time on the extraction of cobalt and nickel were studied in addition to stripping and multi-stage counter-current extraction, and the optimal conditions for extraction were obtained. By using centrifugal extractor and controlling the thoughput to keep phase entrainment under 1% , the high purity nickel electrolyte can be obtained.The experimental result indicates that using P507 and P204 organophosphorus mixed extractants, under conditions that the organic ingredient is 30% extractant,60% sulfonation kerosene, the volume ratio of P204 and P507 is 4:1, 10%TBP, pH is 4.7, O/A is 1:1, the equilibrated time is 15min., the total flux of centrifugal extractor is 4.5L/h, single-stage extraction efficiency of cobalt achieved 88.69 % .And by 2 stages counter-current cascade extraction, the nickle-to-cobalt ratio of raffinate is up to 8000.