Leaching of copper from tailings using ammonia/ammonium chloride solution and its dynamics

The leaching of copper from the tailings of Baifang Copper Mine in Hunan province in China by aqueous ammonia/ammonium chloride solutions has been studied. The tailings belong to a low-grade and high-alkaline copper ore. The effect of leaching time, the concentration of ammonia, solid/liquid ratio and temperature were investigated. The main important parameters in ammonia leaching of copper tailings have been prioritized as solid/liquid ratio, leaching time, temperature and the concentration of ammonia. The optimum leaching conditions are found to be: 4/1 liquid/solid ratio, 4h leaching time, 40°C, 3 mol/L NH4 +. More than 75% of copper was effectively recovered. The dynamical equation of ammonia leaching of copper was obtained and the relation expressions between the grains diameter of tailings and the leaching time are fitted. The results show the grains diameter of tailings has good line relationship with the leaching time and has no relations to the original size of tailings.