Separation of molybdenum and nickel from acidic leaching solution of melted alloy of waste hydrogenation catalyst by solvent extraction

Molybdenum and nickel were extracted and recovered from the pressurized oxidation acidic leaching solution of a melted alloy of a waste hydrogenation catalyst by using N235 extraction. This work investigated the effects of SO₄^2‒ concentration, pH value of acidic leaching solution, organic phase composition and V（O）/V（A） ratio on molybdenum extraction and the effects of ammonia concentration and V（O）/V（A） ratio on molybdenum reverse extraction. The results show that the optimal extraction conditions are SO₄^2‒ concentration in the acidic leaching solution of 1.2 mol/L, pH value of the acidic leaching solution of 0.9, organic phase composition (V/V) of 10% N235/15% secoctanol/75% sulfonated kerosene and V（O）/V（A） ratio of 1/1. The extraction rate of single-stage molybdenum reaches 99.80%, while that of nickel is only 2.35%. The optimal reverse extraction conditions are ammonia of 6 mol/L and V（O）/V（A） ratio of 1/1, and the stripping rate of single molybdenum is up to 90.63%. High-purity products of molybdenum trioxide and nickel nitrate are prepared from raffinate containing Ni and strip liquor containing Mo by subsequent conventional purification and crystallization, thus realizing the recycling of valuable metals from waste hydrogenation catalysts.