Sulfuric acid leaching of SmCo alloy waste and separation of samarium from cobalt

The SmCo alloy waste is considered to be one of the most valuable wastes for recycling, primarily due to the value of the Co and Sm metals. The two metals were extracted from the SmCo alloy waste by sulfuric acid leaching, and Sm(III) was separated by sodium sulfate as a precipitate of sodium samarium sulfate. It was found that 99.9% of the Co and 24.1% of the Sm were extracted into the leach solution under the most suitable conditions: liquid-solid ratio of 6:1, leaching temperature of 60 °C, leaching time of 75 min and H2SO4 concentration of 4 mol/L. A high fraction of 93.4% Sm was precipitated at 80 °C, and the Na2SO4 to Sm molar ratio was 4:1 with 60 min of precipitation time. Thus, sulfuric acid leaching followed by sodium sulfate precipitation is feasible for recovering Co and Sm from the SmCo alloy waste.