The gold heap leaching center of Chinese Academy of Geological Sciences has developed a new method for selecting metallurgical ore equipment-pellet coating roasting oxidation method. This method combines the advantages of roasting oxidation method and pressure oxidation method, and eliminates their respective disadvantages. The advantages of roasting-oxidation process, such as mature mineral processing equipment, less investment, low operating cost and strong adaptability, are retained, and the environmental pollution problem is completely solved. The center has completed laboratory experimental research and achieved success. The fixation rate of sulfur and arsenic in the experimental sample is more than 99.98%, and the gold leaching rate of calcine is higher than that of ordinary roasting oxidation method and roasting oxidation method for fixing sulfur and arsenic 10%-20%. In view of the shortcomings of the existing roasting methods, the researchers of the center invented the pellet coating roasting oxidation method. The biggest difference between the pellet roasting oxidation method and the pellet roasting oxidation method is that the pellet of the former is divided into two parts, the inner core is a mixture of mineral powder and binder, and there is a continuous coating layer (called coating layer) composed of sulfur and arsenic fixing agent with a certain thickness outside the inner core. The existence of the coating ensures that the gas generated when arsenic sulfide is oxidized in pellets is captured by the fixing agent when it diffuses outward, thus realizing the complete fixation of arsenic sulfide. The technological process of pellet coating roasting oxidation method includes raw material preparation, batching, mixture granulation, pellet coating, coating ball drying, roasting, roasting ball coating and cyaniding gold extraction. During the experiment, the researchers found that the oxidation rate of pellet coating roasting oxidation method is controlled by gas penetration and diffusion. When the external temperature is higher than the ignition temperature of sulfide, the external temperature has no obvious effect on the oxidation rate. The particles are covered by the coating and are not in direct contact with air. The external air flow rate and velocity have no obvious effect on the oxidation rate. In a wide range of ambient temperature, the fixation rate of sulfur and arsenic and the leaching rate of gold are high. The researchers believe that the roasting oxidation process of pellet coating is simple, the operating cost of gold mine equipment is low, the equipment investment is low, and the roasting flue gas does not need any purification facilities, which can directly realize pollution-free discharge and save the purification and recovery equipment of sulfur dioxide and arsenic trioxide. In addition, the binder and fixative are widely available and cheap, and there are no major technical and equipment problems, so they are suitable for pretreatment of refractory gold ores containing sulfur and arsenic. At present, the center has applied to China National Intellectual Property Administration for two invention patents, of which 1 has passed the substantive examination. References:
wenwen.soso.com/