Behavior and mechanism of enhanced leaching of copper from refractory oxidized copper ore by microwave preheating
The copper of a refractory oxidized copper ore in Africa mainly exists in the mica interlayer structure. The heating-stirring acid leaching process was used by the local hydrometallurgical plant to treat the ore,but the leaching time was long and the leaching temperature was high,resulting in high energy consumption. In order to increase the leaching rate of copper,reduce the leaching temperature and shorten the leaching time,microwave preheating was carried out to strengthen the leaching of copper oxide. Firstly,the process mineralogy characteristics of the raw ore was studied. Secondly,the leaching behavior of the refractory copper oxide ore under different influences was studied. Finally,the mechanism of microwave preheating to strengthen the leaching of copper oxide ore was analyzed. The results show that there is a large amount of copper in the biotite of the ore,while there is no copper in sericite. Increasing the microwave preheating power and extending the microwave preheating time will enhance the copper leaching rate. However,if the preheating duration is excessively prolonged,the increase of the copper leaching rate may be negligible,while energy consumption will rise. Furthermore,increasing the concentration of sulfuric acid,the leaching temperature and duration can be positively contributes to the leaching process,and the parameters can be further optimized on the basis of microwave preheating treatment. The leaching rate of copper is the highest with 77.05％ under the conditions of microwave power of 350 W,microwave preheating time of 10 min,sulfuric acid dosage of 75 kg/t,leaching temperature of 55 ℃ and leaching time of 200 min. Compared with the heating-stirring acid leaching process adopted by the local hydrometallurgical plants,the amount of sulfuric acid decreases by 15 kg/t,the copper leaching rate increases by 1.92％,the leaching temperature decreases by 10 ℃,the leaching time is shortened by 40 min,and the energy consumption of leaching decreases. Microwave preheating can enlarge the spacing of biotite layers in raw ore and increase the specific surface area of biotite,which is conducive to sulfuric acid entering into the biotite layers to directly contact and react with more copper,and improve the copper leaching rate.
copper oxide orecupriferous biotiteheating-stirring acid leachingmicrowave preheatingleaching energy consumption
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