【摘要】 研究了铬酸钠碳氨转化过程中Na+,NH4+//CrO42-,HCO3--H2O体系的溶解度和相图.根据溶解度和相图对铬酸钠的氨水溶液碳氨转化过程固相析出行为进行分析.结果表明:相图中存在NaNH4CrO4·2H2O复盐结晶区,浓度较高的铬酸钠氨水溶液转化过程中NaC(HO)3、(NH4)2CrO4和NaNH4CrO4·2H2O结晶可能同时析出,形成混晶.为避免同时析出铬酸铵、碳酸氢钠结晶,铬酸钠氨水初始溶液浓度应稍低于相图中P2(P2’)对应的组成,即为1gH2O中Na2CrO40.8633～1.1377g,氨0.0611～0.0986g.更多还原

【Abstract】 The solubility and phase diagram of Na+, //, H2O system are determined in this paper. According to the solubility and phase diagram, the solid phases in carbonation process of sodium chromate in ammonia solution are discussed. The results show that a crystalline zone of NaNH4CrO4·2H2O exists, NaHCO3, NaNH4CrO4·2H2O and (NH4)2CrO4 crystallize out in turn during carbonation process as the concentration of sodium chromate in ammonia water exceeds the concentration corresponding to P2(P2′) in phase diagram. Proper concentration is 0.8633～1.1377 g/g H2O for sodium chromate, 0.0611～0.0986 g/g H2O for ammonia, lower than the concentration corresponding to P2(P2′) plot. The NaHCO3 and NaNH4CrO4·2H2O crystals can be separated by hydrocyclone.更多还原