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

ABSTRACT

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 São João 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.

KEYWORDS:

• Volta Grande Mine
• plant auditing
• Sn-Ta-Nb-Li ore
• REE by-product
• apatite
• critical-metals
• strategic-metals

Acknowledgements

The authors acknowledge Regional Centre for Innovation and Technological Development (CRTI), Federal University of Goiás (Goiânia, GO) for electron probe microanalyses and the Analytical Chemistry Group at CETEM for chemical analyses. The authors thank A.F. Silva from AMG Mineração for samples, assistance, and discussions at the mine site. Valuable discussions with G.P. Silva and L. Silva are also gratefully acknowledged. The article benefited from critical reviews by G.N. Phillips and an anonymous reviewer, and from the editorial handling by S. Jowitt which are gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

FEAA [grant numbers 168785/2014-5 and 140648/2019-4], CAA [grant numbers 30377/2014-3 and 307260/2017-8], and RN [grant number 315472/2018-9] thank Brazilian National Research Council (CNPq) for financial support, as well as for research grant 406853/2013-4.