Xiangxi Lead And Zinc, The Process Of Preparation Of Nano-zinc Oxide Of Zinc Calcine

This research,taking advantage of the local resources,focuses on the development of production process of ZnO nanoparticles via a direct precipitation route with the ZnSO₄ solution obtained by H₂SO₄ leaching and impurities removals of zinc calcine of Xiangxi Pd-Zn mineral as the starting material and Na₂CO₃ or NH₄HCO₃ as the precipitator.In the process of H₂SO₄ leaching of zinc calcine,the effects of H₂SO₄ concentration,ratio of liquid and solid,leaching temperature and leaching time on the leaching rate of Zn were investigated.The results show that the leaching rate of Zn is 96.70%under the conditions of H₂SO₄ concentration of 20%,ratio of liquid and solid of 4:1,leaching temperature of 60℃and leaching time of 1 h.The stable impurities removal process of the leaching solution was the addition of H₂O₂ for the removals of Fe and Mn,the addition of Zn powders for the removals of Cu and Cd,and the addition of CaF₂ for the removals of Ca and Mg, respectively,and purified ZnSO₄ solution could be obtained.With the purified ZnSO₄ solution as the starting material and Na₂CO₃ as the precipitator,ZnO nanoparticles were prepared by the direct precipitation method.The effects of Zn²⁺ concentration,CO₃^2- concentration,mol ratio of CO₃^2- and Zn²⁺,and reaction time on the size and precipitation rate of ZnO nanoparticles,the effects of drying time and temperature of precursor and dispersant on the size of ZnO nanoparticles, together with the effects of calcination temperature and time on the size and purity of ZnO nanoparticles were investigated.TG/DTA,IR,laser grain size analyzer,XRD and SEM were employed to characterize the thermal decomposition,size,morphology and crystal type of ZnO nanoparticles.The results show that the ZnO nanoparticles with hexagonal structure,spherical or spherical-like morphologies,25 nm of average crystal size and 99.2%of ZnO purity are obtained and the recovery of Zn is 96.8%.With the purified ZnSO₄ solution as the starting material and NH₄HCO₃ as the precipitator,ZnO nanoparticles were also synthesized via the direct precipitation route.The effects of Zn²⁺ concentration,CO₃^2- concentration,mol ratio of CO₃^2- and Zn²⁺,and reaction time on the size and precipitation rate of ZnO nanoparticles,the effects of drying time and temperature of precursor and dispersant on the size of ZnO nanoparticles, together with the effects of calcination temperature and time on the size and purity of ZnO nanoparticles were investigated.TG/DTA,IR,laser grain size analyzer,XRD and SEM were employed to characterize the thermal decomposition,size,morphology and crystal type of ZnO nanoparticles.The results show that the ZnO nanoparticles with hexagonal structure,spherical or spherical-like morphologies,40 nm of average crystal size and 97.5%of ZnO purity are obtained and the recovery of Zn is 96.2%.The Main technical indices of ZnO nanoparticles prepared by the above-mentioned two routes met or exceeded GB/T19589-2004 National Standard productⅢ.The processes are simple and easy for industrialization and have signicant economic benefit.Undoubtedly,the research achievements will provide references and technical supports for the industrialization of ZnO nanomaterials in Xiangxi.