A green and efficient utilization of refractory cyanide tailings containing inclusion gold by microwave roasting

Abstract

In order to achieve green and efficient utilization of refractory cyanide tailings, the synergistic effect of chlorinating agent, atmosphere and microwave fields was explored in this paper. As per the thermodynamic calculation results, CaCl2 and O2 were selected as the most appropriate chlorinating agent and atmosphere in the experiment. Compared with cyanide tailings, the dielectric properties of the material after adding CaCl2 were significantly improved, especially at high temperature, the dielectric loss was increased by 31.03 %. The microwave penetration depth of cyanide tailings more stable at different temperatures, only between 5 and 10 cm. The heating time is shortened by 25 %. Under best experimental conditions, the gold recovery and chlorine removal rates achieved 81.87 % and 94.85 %, respectively. The participation of CaCl2 led to the generation of new components with a low melting point in gangue, and the surface pores and cracks of the material increased significantly. Air is the cheapest gas, which contained enough oxygen to oxidatively decompose the CaCl2 and assist in the oxidative destruction of gold inclusions by microwave action. The application of CaCl2 and air accelerates the industrialization process of cyanide tailings recovery and treatment.