New Process And Theoretical Study On Preparation Of High-purity Electrowinned Copper From Complex Refractory Copper Oxide Ore

The copper oxide ore of Dishui,Xinjiang province is characterized by acid-consuming gangaue minerals,high oxidation ratio and high argillation,and a original process of "pre-concentration by flotation-acid leaching-extraction-electrodeposition has been conducted to recover copper oxide minerals.However,after the practical application,the flotation recovery of copper,which was influenced by the temperature most,was within 70%,and the worst could only be approximately 55%.Found on the situation,the Dishui copper Development Company Limited of Bai Cheng,signed contracts with Kunming University of Science and Technology to develop the whole flotation process and the whole hydrometallurgical process,and the requested index of the whole hydrometallurgical process was that the purity and recovery of electrolytic copper should be higher than 99.95%and 80%,respectively.According to the requested index,a whole hydrometallurgical process of "ammonia leaching-extraction-electrodeposition" has been conducted,which could simplify the process,reduce production cost and raise the production efficiency by removing the flotation process.Based on the characteristics of the ore,conditional tests of the key factors determining copper recovery,compare tests of different effective extractants and so on,the total copper recovery could reach 86.85%with a leaching rate of 86.85,a extraction rate of over 99%and a electrolytic copper purity of 99.95%,which has achieved the object to recover the copper minerals more effectively.The results of multi-element analysis,phase analysis and XRD all suggest that the raw ore is characterized by high content of calcium and magnesium,high oxidation ratio and high argillation,which makes it unsuitable for acid leaching.The ease of the reactions in different ammonia leaching solutions has been discussed by thermodynamics and dynamics.The thermodynamics analysis shows that it is feasible to recover the copper oxides by ammonia leaching,during which the ammonium salt has tremendous effect.The test result shows that only in ammonia-carbamic acid ammonia leaching solution the copper leaching recovery could reach the maximum of 86.65%,and the order of the ammonia salt leaching solutions has been described as:ammonia-carbamic acid ammonia>ammonia-salvolatile>ammonia-ammonium chloride>ammonia-ammonium fluoride>ammonia-ammonium bicarbonate>ammonia-ammonium sulfate.The dynamics analysis shows that the leaching progress was control by the residual solid film diffusion control model with an apparent activation energy of 0.75 kJ/mol,and the leaching process belongs to typical diffusion dynamics law with a dynamic equation:1-3（1-x）^2/3+2（1-x）=k₀c^0.19（L/S）^0.11（d_p）^0.0005e^-0.09/TtBased on the theory and test of solvent extracting in cuprammonia,the extraction and stripping process could be affected by extractant concentration,extract phase proportion,extraction time,pH of solution,sulfuric acid concentration,stripping time and stripping phase proportion.Moreover,the extraction mechanism has been preliminarily discussed,and the OH-of extractant has been considered a main contributing factor.