Abstract:
The SmCo5 magnet alloy is a powerful magnet used in defence, aerospace, and automotive transmissions. While shaping to form different magnets, a lot of scraps are produced. These wastes offer a sustainable way to recover the critical metals, Sm and Co, reducing reliance on primary raw materials. This study investigates the recovery of Sm and Co from SmCo5 magnet alloy scrap using solvometallurgical techniques, which utilise organic solvents for metal extraction while minimising water usage compared to traditional methods. Various organophosphorus extractants were tested as lixiviant, with the solvoleaching efficiency order D2EHPA > PC 88 A > Cyanex 572 > Cyanex 272, reflecting their decreasing acidity and influence on metal dissolution. The optimal solvoleaching conditions: 2 mol/L D2EHPA concentration, 80 degrees C temperature, 8 h leaching time, 400 rpm agitation speed, and 10 g/L pulp density resulted in near-complete recovery of samarium and cobalt. Samarium and cobalt were effectively separated from strip leach liquor using the sodium sulfate double salt precipitation method. Samarium was recovered as NaSm(SO4)(2)nH(2)O with a precipitation efficiency of 99.9 % under optimised conditions: 80 degrees C temperature, 90 min reaction time, Na2SO4:Sm molar ratio of 4:1, and pH 1.25. Cobalt in the residual solution was precipitated as cobalt oxalate with an efficiency of 99.7 % at 60 degrees C temperature, 60 min reaction time, and 1.25:1 oxalate to cobalt molar ratio. The precipitated cobalt oxalate was calcined at 450 degrees C, forming cobalt oxide (Co3O4). This study demonstrates solvometallurgical method as high-yield, sustainable solution for efficient SmCo5 magnet recycling with minimal environmental impact.