Sulfide Minerals Bio-Oxidation of a Low-Grade Refractory Gold Ore

Abstract

This paper describes the oxidative dissolution kinetics of sulfides with gold occlusion within pyrite and arsenopyrite. Shake flasks tests and column leaching of a low grade gold ore from China were carried out with domesticated mixed acidophiles isolated from acid mine drainage. Both test show that the main factors accelerating sulfide oxidation was mainly temperature and redox potential. Column bio-oxidation of mineral with a particle size less than 10 mm at 60°C resulted in higher mineral decomposition, finer fractions and eventually higher sulfide oxidation than that at 30°C. Sulfide-S dissolution increased from 58% to 77% from 30°C to 60°C after 247 ds of bio-oxidation. Further investigation into microbial community attached to the ore surface and in the leachate during the bio-oxidation was done by Real-time PCR assays. Organism of genera Acidithiobacillus was the most dominant species in both leachate and ore surface at lower temperature. For the Archaea, the iron oxidizing microbial Ferroplasma showed its predominance of 60°C. Mineral dissolution kinetics and microbial community in bio-oxidation was lucubrated in this work and suggestions were provided for pre-treatment of refractory gold ore.