Hydrometallurgical Processing and Recovery of Nickel from Spent Catalyst with HCl and Aqua Regia

The nickel based catalysts are conventionally used in process of refinery. After periodical use of the catalysts, due to poisoning effect of foreign material and impurities, which deposit on the surface of the catalyst, they will become inactive. In such cases, fresh catalysts have to be substituted and the spent catalyst will be discarded as waste material. Spent catalysts are harmful for the environment and the nickel is a precious element, so the particular attention is paid to the recycling of spent catalyst. This study investigates the possibility of recovering nickel from the spent catalyst (NiO/Al2O3) resulting from the steam reforming in Tabriz refinery. In the extraction process, nickel is recovered using hydrochloric acid and aqua regia as a solvent. The considered parameters effecting nickel recovery were acid concentration, temperature and time of reaction, solid : liquid ratio, particle size and stirring rate, then experimental was performed and determined optimum condition. The results obtained show that extraction of about 87.41% and 81% for HCl and aqua regia is achieved, respectively.