| The paper discussed the Muliahi complex and mixed copper ore of China Nonferrous Mining Group Luanshya Copper Co.,Ltd.in Zambia,Africa.The Cu oxidation proportion of the raw ore is approximately 80%and the combined copper proportion is approximately 40%,which make the raw ore recovery difficult to process.A single acid leaching process was used in the field.When the raw ore fineness is-0.074 mm?80%?,the leaching temperature is 65°C,and the leaching time is 4 h,the Cu leaching efficiency is approximately 78%.At present,the on-site process has low leaching efficiency and high heating cost,resulting in poor economic benefits.To solve the problem,the on-site process flow is optimized while attaining minimal changes in the process flow.Efficient,economical,and rational development and utilization of complex and mixed copper resources can not only reduce heating costs and improve the economic benefits of enterprises,but also important for improving the comprehensive utilization of copper resources.Based on extensive literature review,this paper analyzed the process mineralogy of Muliahi complex and mixed copper ore.According to the study of process mineralogy,wrapping of copper oxide in iron mineral and iron-impregnated copper were found.A new process was designed,which includes“grinding-flotation-high gradient magnetic separation-grinding of magnetic concentrates-high-temperature enhanced leaching”.The easily recoverable copper sulfide and some free copper oxide were firstly recovered by flotation.High-gradient magnetic separation was used to enrich the iron impregnation and wrapping of combined copper and oxidized copper ore from the flotation tailings.The magnetic concentrates after grinding,high-temperature leaching of iron impregnation and wrapping of combined copper and oxidized copper ore in magnetic concentrates and medium temperature leaching of oxidized copper ore in magnetic tailings were employed for efficient recovery of complex and mixed copper resources.The process structure and process parameters were optimized,and good technical indexes were obtained.At the same time,the leaching kinetics of iron-impregnated combined copper ore in magnetic concentrates was studied.The porosity and particle size composition of magnetic concentrates and leaching residue were studied by BET and BJH.The leaching mechanism of encapsulated copper oxide and iron-impregnated combined copper ore was also determined.The process mineralogy of raw ore shows that the valuable element is Cu,comprises 1.46%,with SiO2,Al2O3,and MgO contents at 56.60%,14.62%,and 5.53%,respectively.The proportion of copper oxide ore is as high as 76.92%?free copper oxide and combined copper oxide:37.76%and 39.16%,respectively?,and the proportion of copper sulfide ore and others is 23.08%.The copper in the raw ore is mainly distributed in the form of independent minerals,such as chalcopyrite,lanthanite,bornite,covellite,chalcopyrite,cuprite,chrysocolla,and malachite.A copper portion is present in the limonite and biotite in a mechanically mixed form?combined copper?.A phenomenon of iron mineral impregnation with combined copper was found.Experimental studies have shown that single flotation,high-gradient magnetic separation,and leaching cannot maximize the recovery of copper resources.The new process of"grinding-flotation-high gradient magnetic separation-grinding of magnetic concentrates-high temperature enhanced leaching”shows that the raw ore grinding to-0.074 mm accounts for 80%.When the amount of sodium sulfide was 400 g/t and the amount of butyl xanthate was 500 g/t,a concentrate with a Cu grade of 29.37%and a recovery efficiency of 32.22%were obtained by flotation.Flotation tailings were sorted by high-gradient magnetic separation with a magnetic field strength of 1.2T,and a magnetic concentrate with a Cu grade of 2.06%and a recovery efficiency of 48.01%were obtained.The Cu grade of the magnetic tailings was 0.64%,and the loss efficiency was 51.99%.The particle size of the magnetic concentrates after grinding was from–0.074 mm?80%?to-0.044 mm?84.22%?.When the temperature for magnetic concentrate leaching was65°C,the concentrated sulfuric acid dosage was 90 kg/t,the leaching time was 2 h,and the leaching efficiency was 85.03%.When the temperature for magnetic tailing leaching was 40°C,the concentrated sulfuric acid dosage was 45 kg/t,the leaching time was 4 h,and the leaching efficiency was 76.48%.Through the combined proved of integrated flotation,magnetic separation,and leaching,a technical index of Cu comprehensive recovery efficiency of 86.02%was obtained.Process mineralogy analysis of magnetic concentrates further confirmed the phenomenon of iron mineral impregnation with combined copper and wrapping of copper oxide mineral.The process mineralogy study of leaching residue shows that the surface of the leaching residue of magnetic concentrates were seriously eroded,resulting in many new cracks and gaps,while the surface of leaching residue of magnetic tailings had no cracks and gaps.Thus,high temperature can enhance the erosion of the ore surface and create new cracks and gaps.The leaching reaction kinetics of flotation tailings,magnetic concentrates,and magnetic tailings show that the leaching process is based on the shrinkage nucleus model.The process reaction rate is controlled by three-dimensional diffusion,and the equation is[1-?1-?1/3]2=6)8)t.The apparent activation energies are 17.37,13.80,and 21.19 kJ/mol,respectively.It conforms to the kinetic characteristics of low apparent activation energy in diffusion control.The kinetic model of leaching reaction of iron minerals impregnated with copper was determined to provide theoretical guidance for on-site production.The results of laser granulometry of magnetic concentrates and its residues show that the content of coarse fraction and the volume average particle size of residues have decreased,whereas the content of fine fraction has increased.The higher the leaching temperature,the larger the concentrated sulfuric acid dosage and the more obvious the increase of the fine fraction.Thus,high temperature and high concentration of sulfuric acid facilitate the production of thinner particles.The effect of the leaching reaction process on the particle size of the iron-impregnated copper ore was determined.The N2 adsorption–desorption isotherms of magnetic concentrates and its leaching residue belong to type IV,both mesoporous minerals?2–50 nm?,and the isotherms of hysteresis are H3type.Thus,the leaching residue has a mesoporous slit produced by the layered structure aggregate.BET analysis showed that the surface area of the leaching residue was reduced.Moreover,the higher the temperature,the greater the influence of the leaching residue on the surface area.BJH analysis showed that the pore volume of the leaching residue became smaller and the depth of the internal pores became shallower,indicating that a new solid was formed after the chemical reaction inside the ore pores,and the products adhered to the pores.Consequently,the mass transfer is blocked,revealing the mechanism of the change of pores in leaching process of iron-impregnated combined copper. |
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