| Zinc is mainly used for galvanizing protection and battery manufacturing industry, its production mainly using zinc sulfide as the raw materials. As zinc sulphide resource are increasingly drying up, more attention has been paid to the development and utilization of zinc oxide ore. However acidic solvent processing zinc oxide ore make a large number of alkaline gangue and silicate by dissolution, not only the great amount of acid consumption, and pulp of liquid-solid separation difficult, and the ammonia kind of solvent can avoid alkaline gangus and leaching of silicate. Deep Eutectic Solvents (DESs) is developed in recent years as a new type green solvent, some DESs can be selectively dissolved of ZnO ability, thus can be used as a potential solvent leaching of zinc oxide ore. With application in ammonia method smelting non-ferrous metal, ammoniacal leaching in zinc smelting process draws more and more attention. In this paper with low grade zinc oxide ore of LanPing as the raw material, respectively adoptCholine Chloride-Urea (ChCl:Urea), Choline Chloride hydrate(1ChCl:1H2C2O4·2H2O) DESs Ionic liquids system and NH3-(NH4) 2SO4-H2O solution as leaching agent leaching of zinc oxide ore. The main contents and conclusions are as follows:(1) Synthesized 1ChCl:2Urea and 1ChCl:1H2C2O4·2H2O DESs, and the deter-mination of the physical and chemical properties such as melting point, viscosity, density. Investigated the influence of different factors on the zinc leaching rate, analysis shows that within 150℃,200℃ is thermal stability.(2) 1ChCl:2UreaDESs is adopted to leach of zinc oxide ore, through the single factor experiment and orthogonal design of experiment to obtained the optimal technological conditions:liquid-solid ratio 20:1, leaching temperature 80℃, leaching time 16h, stirring speed 300 r·min-1, zinc leaching rate can reach 65%. For mineral raw material and the leaching slag of XRD, XRF, FTIR test results shows that smithsonite is leached, leaching mechanism is that 1ChCl:2Urea system’s Cl- and Urea with smithsonite coordination, [ZnClO·Urea]- complex ion is present in the system.(3) 1ChCl:1H2C2O4·2H2O DES is adopted to leach of garde zinc oxide ore, leach-ing of zinc oxide ore, the mineral zinc with DES in oxalic acid in reaction to generate ZnC2O4soluble in the DES, in 3～10 times of distilled water dilute pulp, Zn2C2O4 to precipitate out, so can the body before the preparation of zinc oxide. The optimal technological conditions is obtained through single factor experiment:liquid-solid ratio of 10:1, leaching temperature 50℃, leaching time2h, stirring speed 300 r. min-1, zinc leaching rate of more than 90%. XRD, FTIR and thermal analysis of the test results show that the zinc oxide ore with 1ChCl:1H2C2O4·2H2O DES reaction to generate Zn2C2O4, particle size to 10 microns.(4)NH3-(NH4)2SO4-H2O is adopted to leach of zinc oxide ore. Through the single factor experiment and Response Surface Design Method to design experiment investi-gated the liquid-solid ratio, leaching temperature, leaching time and the concentration of total ammonia process parameters on the system of NH3-(NH4)2SO4-H2O leaching zinc oxide ore’s leaching rate order:solid-liquid ratio> leaching time> leaching temperature> total ammonia concentration.(5)Studying the leaching mechanism that the system of NH3-(NH4)2SO4-H2O leaching of the zinc oxide ore, zinc oxide ore of smithsonite and hemimorphite with ammonia complexing, form zinc complexes into ammonia leaching.The digestion of leaching zinc from zinc oxide ore with NH3-(NH4)2SO4-H2O roasting process is studied. This process follows the shrinking unreacted core model, and follows the rules of solid product layer diffusion control, The activation energy of the stage is calculated to be 10.21 kJ·mol-1。... |
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