Experimental Studies on Metal Extraction Improvement in Bacterial leaching

细菌浸出比非生物常规工艺具有低能耗和低操作成本的优点，目前已被商业上用于从低品位硫化物矿石中回收铜，否则这些矿石将成为废物。然而，浸出速率一般较慢，金属提取不完全。为了获得更高的浸出率和金属回收率，确定影响浸出行为的因素是很重要的。研究了细胞外磷脂和单月酸山梨醇聚氧乙烯对氧化亚铁硫杆菌浸出黄铜矿的影响。磷脂酰甘油和磷脂酰乙醇胺是铁氧化菌培养中检测到的主要磷脂类。前者抑制了硫酸铁和氧化亚铁对黄铜矿的化学浸出。随着磷脂酰甘油添加量的增加，细菌浸出铜的最终提取率降低。另一方面，磷脂酰磷脂添加更多的氨胺略微加速了化学浸出，对亚铁氧化没有影响。磷脂酰乙醇胺对细菌浸出铜的提取率没有影响。单月桂酸山梨醇聚氧乙烯是一种非离子表面活性剂。在没有表面活性剂的情况下，氧化铁霉的大部分细胞粘附在黄铜矿表面，可溶性铁主要以亚铁形式存在。表面活性剂抑制了细胞对矿物表面的粘附，随着添加量的增加，液相中的细胞数量增加。当加入20 ~ 50 g/m^3的表面活性剂时，液相中的细胞将亚铁离子迅速氧化为铁离子，黄铜矿被铁离子化学氧化，铜的萃取量明显增加。但过量的添加抑制了细菌亚铁氧化和铁离子对黄铜矿的化学浸出，从而降低了铜的浸出。此外，作者还开发了一种简单快速的氧化亚铁霉细胞生长估计方法。少

Bacterial leaching has the advantages of low energy consumption and operation costs over abiological conventional processes, and is now used commercially to recover copper from low-grade sulfide ore which would otherwise be waste. However, the leaching rate is generally slow and metal extraction is incomplete. To achieve higher leaching rates and metal recovery, it is important to establish the factors influencing leaching behavior. The authors have investigated the effects of extracellular phospholipids and polyoxyethylene sorbitan monolaurate on bacterial leaching of chalcopyrite by Thiobacillus ferrooxidans.Phosphatidylglycerol and phosphatidylethanolamine are main phospholipids detected in the cultures of iron-oxidizing bacteria. The former depressed chemical leaching of chalcopyrite with ferric sulfate and ferrous oxidation by T.ferrooxidans. The final copper extraction in bacterial leaching decreased with increasing phosphatidylglycerol addition.On the other hand, phosphatidyleth … More anolamine accelerated slightly the chemical leaching and had no effect on the ferrous oxidation. The copper extraction in bacterial leaching was not affected by phosphatidylethanolamine.Polyoxyethylene sorbitan monolaurate is a nonionic surfactant. Without the surfactant, most cells of T.ferrooxidans adhered to chalcopyrite surfact and soluble iron was dominantly present in ferrous form. The surfactant depressed the cell adhesion to the mineral surface and number of cells in the liquid phase increased with increasing addition. When adding 20 to 50 g/m^3 of the surfactant, the cells in the liquid phase rapidly oxidized ferrous ions to ferric ions and chalcopyrite was chemically oxidzed by the ferric ions, as a result the amount of extracted copper increased markedly. However, the excessive addition depressed the bacterial ferrous oxidation and the chemical leaching of chalcopyrite with ferric ions, consequently copper extraction was decreased.Moreover, the authors have developed a simple and rapid cell growth estimation method for T.ferrooxidans. Less