Study On Arsenopyrite Oxidation And Iron Phosphate Coating On Arsenopyrite

The oxidation of arsenopyrite in nature brings about the generating of acid mine drainage, which poses threat to eco-environment and human health. In this study, we use hydrogen peroxide as major oxidizing agent to investigate the oxidation condition of arsenopyrite. Meanwhile, use bone char and synthetic hydroxyapatite as coating agents to prevent the oxidation of arsenopyrite. We took a series of columns and batch experiments to investigate the influence factors of oxidation such as temperature, pH, grain size and concentration of H₂O₂. By adding different volume of bone char, synthetic hydroxyapatite and slag,we studied the surface passivating conditions. The main consequence of this study include:?1?The oxidation of arsenopyrite could be immensely accelerated by microbial metabolism, and the oxidation rate in aqueous solution is faster than that in air and vacuum, the oxidation rate of different elements obey flowing order: As>Fe>S, the rate oxidized by Fe?III?is faster than dissolved oxygen.?2? The higher the temperature, the smaller the particle size, the higher the concentration of H₂O₂, the more favorable oxidation of arsenopyrite?3? Arsenopyrite oxidation surface coated with a layer of iron-based clad layer under alkaline conditions, preventing oxidation dissolution process continues. arsenopyrite oxidation rate becomes minimum at pH 7-8 range.?4?The influence of bone char on the oxidation of arsenopyrite mainly by the means of change the p H. the arsenopyrite surface coating layer is mainly composed of iron hydroxide and iron phosphate. There is a effectively removal of heavy metal ion by bone char. The removal rate is as high as 90%.?5? the coating results from synthetic hydroxyapatite is discontinuous, and the inhibition efficiency of hydroxyapatite seem to stronger than iron-based layer and iron phosphate.