Dopson Mark, Halinen Anna-Kaisa, Rahunen Nelli, Boström Dan, Sundkvist Jan-Eric, Riekkola-Vanhanen Marja, Kaksonen Anna H, Puhakka Jaakko A
Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden.
Biotechnol Bioeng. 2008 Mar 1;99(4):811-20. doi: 10.1002/bit.21628.
Silicate minerals are present in association with metal sulfides in ores and their dissolution occurs when the sulfide minerals are bioleached in heaps for metal recovery. It has previously been suggested that silicate mineral dissolution can affect mineral bioleaching by acid consumption, release of trace elements, and increasing the viscosity of the leach solution. In this study, the effect of silicates present in three separate samples in conjunction with chalcopyrite and a complex multi-metal sulfide ore on heap bioleaching was evaluated in column bioreactors. Fe(2+) oxidation was inhibited in columns containing chalcopyrite samples A and C that leached 1.79 and 1.11 mM fluoride, respectively but not in sample B that contained 0.14 mM fluoride. Microbial Fe(2+) oxidation inhibition experiments containing elevated fluoride concentrations and measurements of fluoride release from the chalcopyrite ores supported that inhibition of Fe(2+) oxidation during column leaching of two of the chalcopyrite ores was due to fluoride toxicity. Column bioleaching of the complex sulfide ore was carried out at various temperatures (7-50 degrees C) and pH values (1.5-3.0). Column leaching at pH 1.5 and 2.0 resulted in increased acid consumption rates and silicate dissolution such that it became difficult to filter the leach solutions and for the leach liquor to percolate through the column. However, column temperature (at pH 2.5) only had a minor effect on the acid consumption and silicate dissolution rates. This study demonstrates the potential negative impact of silicate mineral dissolution on heap bioleaching by microbial inhibition and liquid flow.
硅酸盐矿物与矿石中的金属硫化物共生，当硫化物矿物在堆浸中进行生物浸出以回收金属时，硅酸盐矿物会发生溶解。此前有人提出，硅酸盐矿物的溶解会通过消耗酸、释放微量元素以及增加浸出液的粘度来影响矿物的生物浸出。在本研究中，在柱式生物反应器中评估了三个单独样品中存在的硅酸盐与黄铜矿和一种复杂的多金属硫化矿相结合对堆浸生物浸出的影响。在含有黄铜矿样品A和C的柱中，Fe(2+)氧化受到抑制，这两个样品分别浸出了1.79 mM和1.11 mM的氟化物，但在含有0.14 mM氟化物的样品B中没有受到抑制。含有升高氟化物浓度的微生物Fe(2+)氧化抑制实验以及黄铜矿矿石中氟化物释放的测量结果支持，在两种黄铜矿矿石的柱浸过程中Fe(2+)氧化受到抑制是由于氟化物毒性。对复杂硫化矿进行柱式生物浸出时，在不同温度（7 - 50摄氏度）和pH值（1.5 - 3.0）下进行。在pH值为1.5和2.0时进行柱浸导致酸消耗率增加和硅酸盐溶解，以至于难以过滤浸出液且浸出液难以渗过柱子。然而，柱温（在pH值为2.5时）对酸消耗和硅酸盐溶解速率的影响较小。本研究证明了硅酸盐矿物溶解通过微生物抑制和液体流动对堆浸生物浸出可能产生的负面影响。
