| With the rapid development of economy, the increasing demand for zinc metal resources and dwindling sulfide ore resources disposable in traditional process can not meet need, there is an urgent need for mixed one, metallurgical slag dust and other non-traditional resources to carry out the study on selective separation and efficient extraction, forming a new clean and efficient metallurgical method of processing zinc metal non traditional resources.A complex of zinc resources of low grade of zinc oxide was used as the staring material in this paper. In ammonium sulphate solution leaching system, the effect of each component to leaching rate was investigated by phase and morphology analysis. The method of coaxial probe reflection was utilized to measure the content of each compound in ammonium sulphate system, the influence caused by the different initial concentration of each compound was also considered. At last, the leaching experiment of low grade zinc oxide ore with microwave strengthen in the ammonia-ammonium sulfate and ammonium citrate system was conducted. The main conclusions are as follows:(1) The dielectric constant of the ammonium sulfate solution is studied in the range of 63-74, the dielectric loss is between 3-12, the penetration depth is between 1.4-4cm, all dielectric parameters are between the dielectric parameters of water and zinc oxide ore. The value of dielectric constant, dielectric loss and loss tangent angle decrease,while the value of the penetration depth increases with the increasing concentration of total ammonia. This is attributed to the decreasing percentage of water in aqueous solution with the increasing concentration of total ammonia.(2) The characterization including chemical composition, physical phase, valence bond structure and surface morphology analysis are investigated. It shows that the content of zinc in zinc oxide ore is low, only 6.01%, oxidation is higher,98.47%. Zinc silicate and zinc carbonate are the main form of zinc in low grade zinc ore, zinc silicate in zinc distribution rate is as high as 67.55%, making difficult treatment for raw ore. The ore is mainly made up of gangue (SiO2), the main crystal form of zinc is hemimorphite (Zn4Si2O7(OH)2(HO)), zinc carbonate (ZnCO3) and zinc silicate that may exist in amorphous form.(3) The conventional leaching in ammonia-ammonium sulphate-sodium citrate system for low grade zinc oxide ore has a high leaching rate, we add microwave-assited technology on this basis, which makes the shorter leaching time and more efficient. It is difficult to leach zinc from zinc silicate in conventional ammonium sulphate system, because sodium citrate has good coupling effect,so after adding sodium citrate, the leaching rate increases. The optimum leaching conditions:the molar amount of ammonia ammonium sulphate is 1:1, total ammonia concentration is 7.5mol/L, sodium cetrate concentration is 0.2mol/L, solid-liquid ratio is 5:1, the temperature is 30℃, stirring speed is 300r/min, two leaching stage, leaching time of each stage is lh, the leaching rate can reach 93.4%.(4) The related parameter of leaching low grade oxide zinc ore calcinated by microwave-assited in the ammonia-ammonium sulfate and sodium citrate system is studied, each stage leaching time is 45min, significantly decreased 25%, which can reduce the energy consumption. |
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