Recovery of Co(II) and Ni(II) from hydrochloric acid solution of alloy scrap

Abstract

A hydrometallurgical process was developed for recovery of nickel and cobalt from the hydrochloric acid leaching solution of alloy scraps. The process consists of five major unit operations: 1) leaching with 6 mol/L hydrochloric acid under the L/S ratio of 10:1 at 95 °C for 3 h; 2) copper replacement by iron scraps under pH value of 2.0 at 80 °C, and stirring for 1 h; 3) removal of iron and chromium by chemical precipitation: iron removal under pH value of 2.0 at 90 °C by dropwise addition of sodium chlorate and 18% sodium carbonate solution, then chromium removal under pH value of 4.0 at 70 °C by addition of nickel carbonate solution, stirred by air flow for 2 h; 4) selective separation of cobalt from nickel by extraction using 30% trialkyl amine+50% kerosene (volume fraction) and tri- n-butylphosphate (TBP) as a phase modifier with the O/A ratio of 2:1, and stripping of cobalt with 0.01 mol/L HCl; 5) crystallization of nickel chloride and electrodeposition of cobalt. It is found that the nickel recovery of 95% and the cobalt recovery of approximately 60% with purity over 99.9% are obtained by this process.