ABSTRACT
A variety of low-grade ore deposits such as copper, nickel, gold, uranium and others available throughout the world are dumped as wastes due to the unsuitability of conventional methods of metal recovery. As a result of the gradual depletion of the oxide as well as the high-grade ore deposits, particular concern is being raised to process the low-grade/run-off mine ores. Low-grade ore deposits are otherwise treated as waste due to the associated
CONTENTS
8.1 Introduction ................................................................................................ 209 8.2 Microorganisms in Waste Treatment and Their Area of Application ............................................................................................. 210
8.2.1 Autotrophic ..................................................................................... 211 8.2.2 Heterotrophic ................................................................................. 212 8.2.3 Thermophilic .................................................................................. 212
8.3 Mechanism of Microbial Action .............................................................. 213 8.4 Methods of Microbial Leaching ............................................................... 216
8.4.1 Shake Flask Leaching .................................................................... 216 8.4.2 Percolation Column Leaching ...................................................... 217 8.4.3 Heap Leaching ............................................................................... 219
8.5 Downstream Methods of Metal Extraction ........................................... 220 8.5.1 Solvent Extraction .......................................................................... 220 8.5.2 Electrowinning ...............................................................................222
