Reduction of stibnite by hydrogen

Abstract

The reduction of stibnite by hydrogen in the absence and in the presence of sulfur acceptors has been investigated at atmospheric pressure and at temperatures of 200 – 600 °C. The activation energy of these processes has been found to be 17.4 kcal mol −1 (−7.2 × 10 4 J), 20.4 kcal mol −1 (−8.5 × 10 4 J), and 27.7 kcal mol −1 (−11.6 × 10 4 J), in the absence of sulfur acceptors, with calcium oxide and with magnesium oxide, respectively. The calcium and magnesium sulfides can be removed from the reaction residues by leaching with dilute hydrochloric acid solution. The purity of the antimony metal produced in these processes varied between 98.0 and 99.5%. The hydrogen sulfide liberated can be converted into elemental sulfur or sulfuric acid; consequently, this method will not pollute the environment. On the basis of the experimental data of this investigation a flow sheet has been developed for the production of metallic antimony from high grade sulfide-bearing concentrates.