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Chlorination : a potential approach for the recovery of stategic metals from their bearing materials.

Abstract : This paper summarizes laboratory experimentation results of the chlorination processes developed for the extraction of strategic metals such as tantalum and niobium from slags as well as for the upgrading of chromite concentrates. Multiple tin slag samples containing various contents of (Ta, Nb)2O5 were subjected to enhanced leaching leading to (Ta, Nb)2O5 concentrates before their selective chlorination. A chromite concentrate supplied from an European producer is used for this study without preliminary treatment. The explored temperature range of the experimental tests varied from 20 °C to 1050 °C when the chlorination mixtures used consisted of Cl2+N2, Cl2+CO and Cl2+O2. Qualitative and quantitative analysis methods were used to evaluate the selectivity, efficiency and performance of the different chlorination processes. Extraction of Ta and Nb from a rich concentrate using Cl2+CO (carbochlorination) is significant starting from 200 °C. The carbochlorination of Nb2O5 was complete at about 300 °C and that of Ta2O5 at 500 °C. The condensed reaction products consisted of almost pure Ta and Nb chlorides and/or oxychlorides. Higher temperatures are required for the chlorination in absence of reducing atmosphere. Upgrading of the chromite concentrate is achieved either by its carbochlorination at about 550 °C or by oxychlorination (Cl2+O2) at higher temperatures. Advantages of the dry chlorination in terms of energy saving, flexibility to raw material composition, selectivity of the processes and the extraction efficiency make the chlorination process a potential approach for the extraction of strategic and valuable metals.
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Submitted on : Thursday, April 20, 2017 - 2:38:24 PM
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Eric Allain, Ndue Kanari, Nour-Eddine Menad, Frédéric Diot, Lev Filippov, et al.. Chlorination : a potential approach for the recovery of stategic metals from their bearing materials.. 5th International Conference on Engineering for Waste and Biomass Valorisation, 2014, Rio de Janeiro, Brazil. pp. 212-226. ⟨hal-01511165⟩



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