碳酸氢铵溶液中偏钒酸铵的冷却结晶

Cooling crystallization of ammonium metavanadate from ammonium bicarbonate solution

针对钒渣空白焙烧-铵化浸出新工艺产生的浸出液,在对NH_4HCO_3-NH_4VO_3-H_2O溶解度数据进行分析的基础上,采用冷却结晶分离方法分离溶液中偏钒酸铵。采用程序控温冷却方式考察了碳酸氢铵浓度、降温速率、搅拌速率、晶种添加量等因素对偏钒酸铵从70℃冷却结晶至40℃时结晶率、产品粒度、形貌等的影响,明确了偏钒酸铵冷却结晶规律,建立了偏钒酸铵从碳酸氢铵母液中高效结晶分离方法,获得了结晶最佳工艺条件。在碳酸氢铵浓度10g/L、降温速率0.36℃/min、搅拌速率200r/min、晶种添加量1.0%时偏钒酸铵结晶率可达94.28%,得到的偏钒酸铵晶体纯度为99.5%,产品粒度均匀,平均粒径约为152μm,晶体成规则棱柱状结构。

Based on the solubility data of NH_4HCO_3-NH_4VO_3-H_2O ternary leaching solution which obtained from the vanadium slag roasting-ammonium leaching reaction,the present study established a high-efficiency crystallization and separation method of ammonium metavanadate from ammonium bicarbonate solution by programmed temperature controlling method when ammonium metavanadate solution cooling from 70℃ to 40℃. The effects of ammonium bicarbonate concentrations,cooling rate,agitation speed and seed load on crystallization rate,particle size and micro-structure of crystallized ammonium metavanadate were studied and discussed. The optimized separation condition showed that when ammonium bicarbonate concentration was 10 g/L,cooling rate was 0.36℃/min,agitation speed was 200 r/min and seed load was 1.0%,crystallization rate reached to 94.28% while the purity increased to 99.5%. The average particle size of the epigranular crystal was 152μm with a shape of prismatic structures.