Progress of research in copper bioleaching technology in China

Mineral resources are the mainstay industries supporting the development of the national economy. Due to its excellent ductility, electrical and thermal conductivity, copper is widely used in construction, power, transportation, and manufacturing as an important strategic metal resource. According to statistics, in terms of output and consumption of ten kinds of non-ferrous metals such as copper, aluminum, and zinc, China has ranked first in the world for more than ten consecutive years. China's copper resources are poorly endowed, being low grade, highly ore-deficient, and of poor ore floatability; the use of conventional separation methods has been costly and caused serious environmental pollution due to difficulties with residue disposal. Bioleaching is a special mining technology that leaches and yields valuable metal elements from inside ores using leaching bacteria. Copper metal resources inside low-grade ores, waste ores, and boundary ores are recycled efficiently using bioleaching technology, which is efficient, and both environmentally-friendly and economical. Currently, more than a quarter of the world's copper production depends on this technology. However, the microbial copper leaching process has always been regarded as a "black box", being difficult to effectively monitor and regulate. This paper reviews the history of bioleaching technology in China, reviews those copper mines that have carried out exploration into or application of bioleaching technology, and introduces two typical copper bioleaching industrial cases, the Zijinshan and Dexing Copper Mines. This paper explores (a) the main process of isolation, identification and enrichment of leaching bacteria, (b) the bioleaching mechanism and interface reaction, (c) the multistage seepage behavior of leaching systems, (d) the reconstruction and quantification of pore structures, (e) the multi-field coupling and process simulation of leaching systems, and (f) copper metal recycling from waste printed circuit boards. Finally, along with the current status of copper bioleaching, major challenges such as environmental protection, security, and future trends in copper bioleaching are discussed as a basis for further research.