硅锌矿在(NH_4)_2SO_4-NH_3-H_2O体系中高液固比下的浸出动力学

Leaching kinetics of willemite in(NH_4)_2SO_4-NH_3-H_2O system at higher mass ratio of liquid to solid

通过实验研究硅锌矿在（NH4）2SO4-NH3-H2O体系中高液固比下的浸出动力学。采用粒径为96~109μm的纯硅锌矿样品,在液固质量比为200时,考察搅拌速度、反应温度及总氨浓度对锌浸出率的影响。研究结果表明：提高温度和总氨浓度能显著提高浸出速率,而当搅拌速度大于250 r/min时,其对浸出速率的影响较小;浸出过程遵循孔隙扩散控制粒子模型,扩散与化学反应并非仅发生于颗粒外表面,而是发生在整个外表面及孔隙内部,浸出速度受孔隙扩散控制;浸出过程的表观活化能与反应级数分别为71.35 kJ/mol和4.27。

Leaching kinetics of willemite in（NH4）2SO4-NH3-H2O system were investigated by using pure mineral of willemite as raw materials when mass ratio of liquid to solid was 200.The effects of factors on the leaching rate,such as stirring speed,temperature and total ammonium concentration,were studied experimentally.The results show that increasing temperature and total ammonium concentration can enhance the leaching rate remarkably,while when the speed is larger than 250 r/min,the stirring has no obvious effect on the leach.The leach process obeys the grain model with porous diffusion control,indicating that the diffusion and chemical reaction take place,not only on the outer surface of the particles,but also on the out surface together with the cavities of the porous particles.Kinetic studies demonstrate that the leach process is controlled by the porous diffusion,determining the apparent active energy and reaction order to be 71.35 kJ/mol and 4.27,respectively.