Bacterial heap-leaching: Practice in Zijinshan copper mine

Zijinshan copper mine is the largest chalcocite deposit in China. The attempt to recover copper from the ore by bioleaching began at the end of 1998. Following the metallurgical studies carried out over 2 years, a pilot plant consisting of bio-heap leaching and SX–EW was built at the Zijinshan Copper Mine at the end of 2000, with a production capacity of 300 t/a copper cathode. After its successful operation for 1.5 years, the plant was scaled up to a capacity of 1000 t/a copper cathode by June 2002. Currently a commercial bio-heap leach plant with a capacity of 10,000 t/a is under construction and is scheduled to be commissioned by the end of 2005.This paper describes metallurgical studies and pilot plant tests for Zijinshan Copper ore. A brief introduction to the mineralogy, bacterial culture, shake flask tests and column tests on bioleaching is presented. The performance of bio-heap leaching and SX–EW, acid and iron balance, operational cost of the pilot plant are discussed. A brief summary of the process flow sheet and the estimated capital cost of the commercial plant of 10,000 t/a are presented at the end of the paper.