Gravimetric characterization of Pyrite carbothermic reduction in the presence of lime

Abstract

Pyrite carbothermic reduction studies were conducted on pyrite concentrate (40.75 % iron, 48.04 % sulphur,  0.11 % copper) from the Otjihase Mine in the Repubic of Namibia. Additionally, this research included thermal decomposition and  ion exchange since they cannot be dissociated from carbo-thermic reduction.   The aim was to assess the iron metallization, and the assessement was carried out through mass percent reduction. A factorial research design was adopted, consisting of two factors (time and CaO/C ratio at five levels, and one factor (temperature) at three levels in reducing environment. The analysis of variance (ANOVA) was used for data analysis.  At thermal decomposition stage, metallization increased with treatment time, it was flatter at higher temperature but remained consistently higher than at lower temperatures. At ion exchange stage, metallization was random, yet showing much lower magnitude than the metallization at thermal decomposition stage. At carbo-thermic reduction stage, metallization decreased with increased treatment time at 1273K and 1473K for different C/CaO ratio, however the opposite phenomenon occurred at 1373K. In general, higher carbon to calcium oxide  ratio triggered more metallization.