The Process Research And Simulation Of Zn O Preparation By Ammoniaand Waste Water Recovery

Activated ZnO is a very important chemical raw material, which displays more excellent properties than ordinary ZnO in light absorbing and catalytic activity, activated ZnO has a wide application in ceramics, defence, spin, etc. Recently, with increasing demand for activated ZnO in various industries, activated ZnO has a wide application prospect.Presently, activated ZnO prepared by ammonia complex method was widely used for its lower cost, higher purity product and strong currency. Meanwhile, it had some shortcomings, including low yield, high energy consumption, large amount of wastewater.In response to these problems, the characteristics of ammonia complex and ammonia distillation was combined in this paper, zinc ammonia leaching solution entered stripper column after it was produced through ammonia complex method, and the ammonia was recovered through ammonia absorption column and ammonia desorption column.The zinc ammonia leaching solution is a complex system, the complex formation mechanism was analyzed according to chemical bond theory in this paper, the thermodynamic model of ZnO-NH3-NH4HCO3-H2 O system was developed. The effects of ammonia concentration, pH value with different temperature on the solubility of zinc oxide were studied, the results of theoretic calculations at 298 K and 333 K were verified by experiments. The process was reasonably simplified according to the feature of ZnO leaching, ammonia distillation and ammonia recovery system. To improve calculation accuracy, the vapor-liquid equilibrium of NH3-CO2-H2 O system was calculated with modified electrolyte packet in Aspen, the temperature parameters of ZnO dissolve and zinc ammonia complex reaction equilibrium constant was regressed. Finally, the flowsheet of ZnO leaching, ammonia distillation and ammonia recovery was built up and optimized with Aspen, the result shows that the anticipated effect of ammonia distillation and ammonia recovery was achieved, the waste gas from the top of ammonia absorption column and the waste water at the bottom of ammonia desorption column reached discharge standard. This can provide theoretical basis and guiding significance for industrial production procedure.