Experimental Studies on Metal Extraction Improvement in Bacterial leaching

与非生物常规浸出相比，细菌浸出具有能耗低、操作成本低的优点，目前已被用于从低品位硫化矿石中回收铜，否则这些铜将成为废物。然而，浸出速度普遍较慢，金属提取不完整。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。研究了胞外磷脂和月桂酸聚氧乙烯山梨醇单月桂酸酯对氧化亚铁硫杆菌细菌浸出黄铜矿的影响。前者抑制了硫酸铁对黄铜矿的化学浸出，抑制了氧化亚铁硫杆菌对亚铁的氧化。细菌浸出的最终铜浸出量随着磷脂酰甘油加入量的增加而降低，而磷脂酰甘油的…较高剂量的氨酚胺对亚铁的化学浸出有轻微的促进作用，对亚铁的氧化没有影响。细菌浸出中铜的提取不受磷脂酰乙醇胺的影响。聚氧乙烯山梨醇单月桂酸酯是一种非离子表面活性剂。在没有表面活性剂的情况下，氧化亚铁硫杆菌的大部分细胞附着在黄铜矿表面，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黏附，且随着加入量的增加，细胞数量增加。当加入20~50g/m~3的表面活性剂时，溶液中的细胞迅速将亚铁离子氧化成铁离子，黄铜矿被铁离子化学氧化，铜的浸出量显著增加。然而，过量的添加抑制了细菌亚铁的氧化和黄铜矿与铁离子的化学浸出，从而降低了铜的浸出量，同时，作者开发了一种简单、快速的氧化亚铁假单胞菌细胞生长估计方法。较少

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