Role of the reducing agent in tungsten extraction by chlorination with chlorine from an ore enriched by physical means

• Autor(a) principal: Menéndez,Carlos J.
• Data de Publicação: 2022
• Outros Autores: Tavani,Eduardo L.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: REM - International Engineering Journal
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2448-167X2022000400329
• topic: sulphur dioxide; pyrite; carbon; scheelite-wolframite concentrate; free energy change.

Abstract The effect of three reducing agents (sulphur dioxide, pyrite and carbon) on tungsten extraction from a scheelite-wolframite concentrate with chlorine gas was assessed. A low-grade ore (0.9% w/w WO3) was collected in the San Martín department, San Luis Province, Argentina, and subsequently enriched by physical means (65.73% w/w WO3). The minerals identified and their reactivities with chlorine were: scheelite (reactive), wolframite (reactive), pyrite (reactive), quartz (inert) and feldspars (inert). The metal recovered as WO2Cl2, with the different reagent combinations, was in increasing order: Cl2 + N2 < Cl2 + SO2 < pyrite + Cl2 + N2 < pyrite +Cl2 + SO2 < carbon + Cl2 + N2. It was proved that, according to its content, the pyrite initially present in the ore improves chlorination performance. At the same time, the non-volatile reaction products formed - CaCl2 and/or CaSO4 - and the manner of removing the nascent (desorbed) oxygen change depending on the reducing agent tested.