Effect of thermal activation on recovery of copper using microorganisms from ball mill spillage

Malanjkhand Copper Project (MCP), India is designed for excavating 2 million tons (MT)/annum of copper ore. The beneficiation plant of MCP utilizes Cu - 0.45 % and above for production of concentrates thereby generating reject (mill spillage) from its ball mill unit. This waste contains mainly chalcopyrite which is recalcitrant to hydrometallurgical process. Economic and eco-friendly extraction of copper from such waste will definitely contribute to country’s copper output. A novel technique using activation of the surface by thermal means aims on efficient copper recovery which is dealt in the present investigation. This process of activation modifies the surface morphology developing cracks, micro pores helping bacterial solution to penetrate and leach out copper efficiently. In the present work, the leaching ability of mesophillic acidophiles consortium consisting predominantly At. ferrooxidans towards this waste was studied in columns at 1 Kg scale. It was found that copper could be recovered at a faster rate compared to the raw ore. 59% copper was recovered through this activation technique as compared to a 4% and 9% from raw ore-ungrounded and grounded respectively. Bacterial leaching parameters such as pH, iron concentration and count of inoculum were monitored during the process.