A simple method for separating ni from ni-cd batteries and other scrap starts with melting at approximately 350 deg. C in quartz or graphite, fusing almost any common chloride flux mixture on the surface, in an amount 9-12 pct by weight of the contaminated cd, and adding to the salt approximately 0.8X as much red p as ni in the cd by weight. This can be done in air, but less p is needed in ar. The p diffuses through the molten salt and forms insoluble ni phosphide in the cd below. Without salt, this reaction is much less complete. After allowing approximately 1 h for reaction, the salt is removed by decantation or in any way, and the metal is filtered at 350 deg. C through glass cloth or similar porous material to remove the precipitated ni phosphide. Filtration usually requires 1- 3 h even if suction, or pressure from above, is applied. Various suitable ways and means for operation are described, and details of 7 operations are reported. Suitable salt covers were 41.8 G kcl + 19 g licl, or 30 g each of zncl2 and nh4cl, or 25 g zncl2 + 15 g kcl + 10 g nacl. When 2 g of p was used, the filtrate after p treatment was cd containing 0.01-0.04 pct ni, but with only 0.5 G p, the residual ni was 0.11 pct with the same time period. Ni was recovered in the filter cakes. The cd recovery in the filtrate was approximately 90 pct. By especially complete filtration through 2 filters, final ni contents <0.001 pct were achieved.
U.S. Pat. 3,577,232; May 4, 1971; Chem. Abstr. 75:39,159G