Reduction of a concentrate of willemite by charcoal for its use in the Waelz process

Authors

  • Vitor Silva Coimbra Pyrometallurgy and Thermal Analysis Laboratory, Department of Metallurgical and Materials Engineering, Universidade Federal de Ouro Preto – Ouro Preto - Minas Gerais – Brazil – CEP 35400-000.
  • Geraldo Magela de Lima Coordination Chemistry Laboratory, Department of Chemistry, Universidade Federal de Minas Gerais – Belo Horizonte – Minas Gerais – Brazil – CEP 31270-901
  • Versiane Albis Leão Bio&Hidrometalurgia Laboratory – Department of Metallurgical and Materials Engineering, Universidade Federal de Ouro Preto – Ouro Preto - Minas Gerais – Brazil – CEP 35400-000.
  • Rodrigo Fernandes Magalhães de Souza Pyrometallurgy Research Group – Department of Chemical and Materials Engineering, Pontifícia Universidade Católica do Rio de Janeiro – Rio de Janeiro – Rio de Janeiro – Brazil – CEP 22451-900.
  • Víctor de Andrade Alvarenga Oliveira Pyrometallurgy and Thermal Analysis Laboratory, Department of Metallurgical and Materials Engineering, Universidade Federal de Ouro Preto – Ouro Preto - Minas Gerais – Brazil – CEP 35400-000.

DOI:

https://doi.org/10.17159/

Abstract

A willemite concentrate (CW) sample was characterized by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Diffractometry of X-Ray (DRX), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). Quantitative mineralogical analysis of the sample was performed using the Rietveld method and the main minerals constituents of the sample were willemite (55.3 %) and dolomite (15.6 %). Reduction experiments were carried out using a tube furnace and charcoal (CV) was used as reducing agent. The effect of temperature and ratio CV/CW on zinc extraction was studied. The best zinc extraction value was found in the following experimental conditions: 20 % CV and 1100 °C, under these conditions it was possible to extract ≈ 86 % of zinc. The results also showed that, during sample reduction, the calcium oxide generated through the calcination of the dolomite mineral promoted the decomposition of the willemite. Thus, the reduction of the sample by charcoal took place at lower temperatures. Reduction experiments were carried out in tube furnace in the presence of 5, 10, 20, 30, and 40 % CaO and the presence of this chemical improved the zinc extraction at all temperatures studied. Finally, the best zinc extraction result (93 %) was obtained for experiments performed in the presence of 5 % CaO, 20 % CV and at temperature of 1100 °C. The results showed that the willemite concentrate studied has great potential to be used as a raw material for the Waelz process.

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Published

2026-04-15

Issue

Vol. 124 No. 8 (2024): SAIMM Journal

Section

Papers of General Interest

License

Copyright (c) 2024 Vitor Silva Coimbra, Geraldo Magela de Lima, Versiane Albis Leão, Rodrigo Fernandes Magalhães de Souza, Víctor de Andrade Alvarenga Oliveira

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