嗜酸氧化亚铁硫杆菌浸出黄铜矿中氧化还原电位、黄铁钾钒和胞外聚合物的关系和影响

摘要

The changes of pH,redox potential,concentrations of soluble iron ions and Cu2+ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different conditions of initial total-iron amount as well as mole ratio of Fe(Ⅲ) to Fe(Ⅱ) in the solutions containing synthetic extracellular polymeric substances (EPS).When the solution potential is lower than 650 mV (vs SHE),the inhibition of jarosites to bioleaching chalcopyrite is not vital as EPS produced by bacteria can retard the contamination through flocculating jarosites even if concentration of Fe(Ⅲ) ions is up to 20 g/L but increases with increasing the concentration of Fe(Ⅲ) ions; jarosites formed by bio-oxidized Fe3+ ions are more easy to adhere to outside surface of EPS space on chalcopyrite; the EPS layer with jarosites acts as a weak diffusion barrier to further rapidly create a high redox potential of more than 650 mV by bio-oxidizing Fe2+ ions inside and outside EPS space into Fe3+ ions,resulting in a rapid deterioration of ion diffusion performance of the EPS layer to inhibit bioleaching chalcopyrite severely and irreversibly.%在合成的胞外聚合物(EPS)溶液中,研究不同起始总铁量、不同Fe(Ⅲ)与Fe(Ⅱ)摩尔比条件下嗜酸氧化亚铁硫杆菌浸出黄铜矿过程中pH、电位、可溶性铁离子和Cu2+浓度随浸出时间的变化.结果表明:当溶液电位低于650 mV (vs SHE)时,因细菌产生的EPS可通过絮凝黄铁钾钒延缓污染,即使铁离子浓度达到20 g/L,黄铁钾钒对细菌浸出黄铜矿的阻碍作用也不是致命的,但随着铁离子浓度的增加而增加；细菌氧化的铁离子容易吸附在黄铜矿表面的EPS表层,有黄铁钾钒的EPS层是弱离子扩散壁垒,细菌通过把EPS空间内外的Fe2+氧化成Fe3+,进一步创造高于650 mV的电位,导致EPS层离子扩散性能的快速恶化,严重地和不可逆地阻碍生物浸出黄铜矿.