| Summary: | 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.
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