Extraction of nickel from spent nickel catalyst involves direct leaching with sulfuric acid in presence of small amount of persulfate-based additive

摘要

Nickel is extracted from spent nickel catalyst by direct leaching with sulfuric acid in the presence of a small amount of a persulfate-based additive. Extraction of nickel (Ni) from spent Ni catalyst involves: (a) adding a persulfate-based additive along with fine sized Ni catalyst in the sulfuric acid solution and stirring by a magnetic needle/glass stirrer and maintaining the solid liquid ratio at 1/2-1/10 (wt./vol.); (b) keeping the slurry at 40-100[deg]C for 0.5-6 hours; (c) allowing the slurry to settle, and then filtering the slurry to obtain leach liquor containing Ni and alumina as solid residue; (d) washing the solid residue to remove entrapped liquor and drying at 110-120[deg]C to form a by-product containing high alumina; (e) purifying the leach liquor by precipitating iron (Fe) and other impurities using lime, and filtering to obtain pure Ni sulfate solution; (f) crystallizing or precipitating the leach liquors to obtain Ni sulfate crystal or Ni hydroxide; and (g) reducing Ni hydroxide to obtain Ni metal powder or Ni oxide.