Extraction of rare earths from waste SmCo magnet

Abstract

Due to unique physical and chemical properties, rare earth elements are widely used in various modern applications such as electronics, catalysts, magnets etc. Recently, the demand of rare earths increased worldwide due to its usage in clean energy applications such as electric vehicles, wind turbines etc. In India, it is estimated that the demand of rare earths increased 28 times since year 2016. The primary resources of rare earths are limited and multiple separation stages are required for the extraction of rare earths. In this scenario, secondary resources of rare earths may serve as potential source of rare earths. After NdFeB magnets, the Samarium-Cobalt (SmCo) magnets are the second most important group of rare-earth-based permanent magnets. The magnetic property of SmCo magnet can withstand even at high temperature (upto 800 °C), therefore it is used in defence equipment, satellite, high-end engines etc. The present study is focused on the extraction of rare earths from scrap SmCo magnet. The solid-state roasting followed by leaching process is studied for the recovery of metals from SmCo magnet. Different parameters such as temperature, time etc. are varied to obtain the optimum conditions. The leach residue obtained at different conditions was also characterized by XRD and SEM.