Bio-oxidation of Gold from Refractory Sulfide Ores: A Journey Ahead

Biomining through bioleaching and bio-oxidation aims at recovering desired metals at the required specifications with lower environmental impact and costs from ores and waste streams. Research and developments related to the process technology and efficient implementation of this approach are advanced worldwide. Small particles of gold, a metal of higher interest, are mostly found in a matrix of sulfide-based minerals and not affordably recovered with conventional approaches encompassing cyanidation, pyrometallurgy, extreme heating (roasting), oxidation of ore samples at high pressure. Recently, advances in bio-oxidation have been made in addressing scientific and technical challenges that arise during the pilot and demonstration scales in the operations units in bioreactors and heaps. Through including high-throughput bacterial growth data and better process knowledge of the extraction and recovery approaches, bio-oxidation becomes more economically feasible and efficient. More advancements are necessary to evaluate the wide range of mineralogical structure of ores being processed, microbiological, and physicochemical that can significantly influence the bio-oxidation reaction within the different types of reactors (heap and continuously stirred tank reactors), the microbial interactions between metal and microbes, geographical localizations of the mining sector, economic as well as data interpretation by using advanced artificial intelligence methods toward obtaining optimized operation and efficiency. This review covers important advances and developments and associated industrial and academic research and challenges from the past few years for gold bio-oxidation.