| Abstract:The oxidized copper ore from Xinjiang, has low grade of copper, and contains a large quantity of mud and alkaline gangue. The mineral composition of the ore is complex. It’s a typical refractory oxidized copper ore.Targeted at its mineral properties, the paper aims at developing a economical and effective process of copper extraction, to achieve the recovery of copper from the ore. The main contents of the thesis include:the study on the kinetics of ammonia leaching of oxidized copper ore, the sulphidizing flotation-acid leaching combined process, and the ammonia leaching in different ammonia-ammonium leaching system. The main conclusions of the paper are as follows:1. The results of the research about the sulphidizing flotation-acid leaching combined process show that:By using oxidative acid leaching directly, the leaching rate of copper is able to achieve88.49%. But the acid consumption is too high (up to600kg/t). The calcium sulfate and magnesium sulfate, produced in the leaching process, make the pulp become stiff, and the leaching liquor is too little (only40%of ammonia leaching leaching liquor), which is very difficult to separate the solids and liquids. It’s able to achieve the accumulation of copper by sulphidizing flotation, however, due to poor selectivity of pharmacy, the content of calcium and magnesium in the rough concentrate of sulfide flotation has not been effectively reduced, that leads to poor indicators of the subsequent acid leaching process, and can’t effectively recover copper from the ore.2. The results of study on the leaching kinetics show that:The process was controlled by both interface mass transfer and the diffusion of solid residual film (or product layer). The factors which affecting the leaching rate of copper Include temperature, the concentrations of leaching agent, particle size and liquid-solid ratio, etc. The apparent activation energy of the reaction is12.32kJ/mol, and the semi-empirical equation of kinetics of the oxidative ammonia leaching is as follows:1/3ln(1-x)+(1-x)-1/3-1=8.9×10-2c0.25氨水(L/S)0.355c0.175过硫酸c0.258硫酸铵(d0)-0.154e(-1506.78/T)t.3. The results of study on the oxidative ammonia leaching of the ore in ammonia-ammonium sulfate leaching system show that:The leaching rate and recovery can be improved by increasing the concentration and temperature of leaching solution, proper raising the liquid-solid ratio or reducing the particle size of ore can get better leaching index, which are in good agreement with the conclusions of kinetics of ammonia leaching. On the condition of liquid-solid ratio is5:1, in45℃, it can obtain the best leaching rate of copper that is84%. When the liquid-solid ratio is reduced to2:1, it is unable to obtain satisfactory leaching index, no matter how to adjust the experimental factors such as oxidants, leaching time and leaching agent concentration.4. The results of study on the oxidative ammonia leaching of the ore in ammonia-ammonium sulfate leaching system show that:By using two-stage oxidative ammonia leaching in the leaching system, it is able to achieve the recycling of copper from the ore at ambient temperature and pressure. The optimal conditions are as follows:86%of the particle sizes of the sample finer than0.074mm, temperature25℃, stirring speed200r/min, in the first leaching stage the concentrations of ammonia, ammonium sulfate and ammonium persulfate are3mol/L,1.5mol/L and0.15mol/L, respectively, the liquid-to-solid ratio is2:1, agitation leaching1.5hours and non-stirring leaching half an hour; in the second leaching stage the amount of ammonia, ammonium sulfate and ammonium persulfate are halved, agitation leaching1.5hours and non-stirring leaching0.5hour; in the last leaching stage the amount of ammonia, ammonium sulfate and ammonium persulfate are same as the second leaching stage, agitation leaching2hours and non-stirring leaching4hours. Under the conditions, the fine index of the copper leaching rate is more than86%. The leaching index is better than in the ammonia-ammonium chloride leaching system, and significantly reduces the reaction temperature and liquid-solid ratio, which creates the possibility for practical industrial recovery of copper from the ore at room temperature and normal pressure. |
PDF Full Text Request