Nickel recovery from spent nickel catalyst

摘要

A process for nickel recovery from a spent catalyst of definite composition has been developed using the hydro-metallurgical route. The processing steps includes direct sulphuric acid leaching followed by separation of iron as well as silica and other impurities. For a 152 mu m particle size catalyst, extraction, of about 98 percent nickel was achieved at 363 K in 2 h using a sulphuric acid concentration (v/v) of 8 percent and a pulp density of 10 percent. The dissolution of nickel followed diffusion-controlled leaching kinetics. Increase in temperature and sulphuric acid concentration resulted in increase in the nickel recovery. The activation energy for nickel dissolution was calculated to be 62.8 kj mol~(-1). Finally, nickel was recovered as value-added products such as sulphide and oxalate with overall recovery of 90 and 88 percent of nickel, respectively.