Mineralogical auditing of the Volta Grande Mine (SE Brazil) Sn-Ta-Nb-Li processing plant, aiming at REE recovery as by-products

Recovering rare earth elements (REE) as by-products of existing mineral operations is a low-investment option to increase supply in short terms. REE-minerals were reported for the Sao Joao del Rei Pegmatitic Province (southern Minas Gerais State, Brazil) since the late 1940s, but data is scarce and dubious. The largest pegmatites project in the Province - Volta Grande mine - has been mined since 1945, producing concentrates of cassiterite, columbite-subgroup minerals, and microlite, and since 2018 spodumene is also recovered. Here we prepare a stream-specific mineralogical characterisation of the beneficiation plants to identify REE-minerals for potential REE recovery. The results analyse the feasibility of reprocessing some streams to generate a high-apatite product adequate for phosphoric acid production with REE recovery as by-products. The further REE speciation also revealed the preferential distribution of heavy-REE into columbite-subgroup minerals and light-REE into microlite, which may represent promising targets for the production of concentrates with high-purity.