ABSTRACT

Structure .......................................................................................... 119 4.6 Leaching Kinetics of Copper Sulphides ................................................. 120

4.6.1Dissolution Kinetics of Digenite and Covellite ......................... 121

The Zijinshan copper mine is the largest secondary copper sulphide mine in China. It has an ore reserve of more than 400 million tonnes with an average copper grade of 0.43% and geological reserve of metal copper of 1.72 million tonnes. A pilot bioheap leaching plant with a production capacity of 300 t/year of copper cathode was built at the Zijinshan copper mine at the end of 2000, and then the plant was scaled up to a capacity of 1000 t/year of copper cathode by June 2002 (Renman et  al., 2006). In December 2005, a commercial underground mining-bioheapleachingsolvent extraction-electrowinning (SX-EW) plant was commissioned with a capacity of 10,000 t/year of copper cathode. From year 2006 to 2009, the total copper cathode production was 37633.6 t, the average operation cost for copper cathodes was 1.10 USD/lb and the total prot and tax exceeded 149 million USD (Huang, 2010). This plant is the rst commercial application of bioheapleaching in China. The overview of the plant was shown in Figure 4.1. By using bacterial-assisted heapleaching, low production cost was achieved in Zijinshan. Furthermore, life-cycle assessment of the process showed that this technology has advantages of energy savings and less environmental impact when compared with the traditional otation-ash smelter process (Ruan et al., 2010). In 2011, the plant was scaled up to a design capacity of 20,000 t/year of copper cathode. The new plant is capable of treating even a lower grade of the ROM (run of mine) that enables a lower copper cutoff grade that subsequently increases copper’s geological reserve of the mine.