A parameters study of the novel atmospheric pyrite oxidation process with Lewatit® AF 5 catalyst

Abstract

A previous study conducted by the authors introduced a novel process for atmospheric pyrite oxidation with Lewatit® AF 5, a micro/mesoporous carbonaceous bead. This paper presents a parameters study of the atmospheric oxidation of the AF 5 catalysed pyrite oxidation process, promoting maximum pyrite oxidation and maximizing the elemental sulphur generation. Tests were conducted in 2 L jacketed reactors with controlled conditions. The study consisted of multiple tests investigating the effect of temperature (75, 80, 85 and 90 °C), initial sulphuric acid concentration (0.25, 0.5 and 1.0 M), initial ferric concentration (0, 1, 5 and 10 g/L), pyrite concentrate to catalyst mass ratio (4:1, 2:1, 1:1 and 1:2), and test slurry solid pulp density (5, 10 and 20 wt%) on the atmospheric leaching of a pyrite concentrate assisted by AF 5. The study indicated that the most effective parameters in the pyrite oxidation are the test temperature and concentrate to catalyst mass ratio. The best tests in terms of overall pyrite oxidation and elemental sulphur production were those with a 1:2 concentrate to catalyst ratio at 90 °C. These tests had an average of 96.2% overall pyrite oxidation and an elemental sulphur yield on average of 51.0%. Increasing temperature from 75 to 90 °C improved overall pyrite oxidation from 71.9 to 93.6%, however elemental sulphur yields of approximately 46.3% were experienced at temperatures below 90 °C versus 43.3% at 90 °C. Other trends experienced in the investigation of the various parameters will be further discussed.