Oxidation of arsenopyrite in bacterial ferric solutions

Abstract

In this study the oxidation of arsenopyrite in bacterial ferric solutions is examined. Leaching tests were conducted in air-stirred pachuca reactors in order to define the major factors influencing the oxidation of arsenopyrite and to underline the importance of indirect leaching of the mineral by bacterially generated acid ferric sulphate solutions. The parameters studied were the particle size of the mineral concentrate and the initial ferric ion concentration in solution. The rate of oxidation of arsenopyrite during leaching was found to be almost directly proportional to the surface area of the concentrate. In addition, an initial ferric ion concentration of 10 g/1 Fe³⁺ is considered mostly efficient for achieving high arsenopyrite oxidation degrees over a short leach period. The experimental data was used to predict the rate of arsenic release for the Olympias refractory arsenopyrite concentrate, assaying 13% As.