碱性介质多元体系中钒酸钠结晶分离

Separation of Sodium Vanadate in Alkaline Multi-component System

测定了NaOH-NaNO_3-NO_3VO_4-Na_2CrO_4-H_2O五元体系各盐在碱中的相平衡浓度,根据所得数据对该体系中的Na_3VO_4进行了冷却结晶分离.通过研究NaOH浓度、NaNO_3浓度、结晶终点温度、降温速度、搅拌速度、晶种对钒酸钠结晶分离的影响,得到的最优实验条件为：结晶液中NaOH浓度200~250g/L,NaN0_3浓度200g/L左右,搅拌转速200r/min,80~40℃自然降温,添加晶种量1%（ω）,该条件下Na_3VO_4结晶率为61%,晶体纯度可达95%,且晶体颗粒人（147μm）,沉降分离速度快（〈10min）.

The phase equilibrium of sodium salts in the NaOH-NaNO_3-Na_3VO_4-Na_2CrO_4-H_2O systems was determined.Based on the solubility data,sodium vanadate can be separated by cooling from the solution.By examination of NaOH concentration,NaNO_3 concentration,crystallization end temperature,cooling rate,stirring speed,and seeds on the crystallization of sodium vanadate from multi-component alkaline solutions,the optimal experimental conditions for separation of sodium vanadate were obtained as follows：NaOH concentration 200~250 g/L,NaNO_3 concentration 200 g/L,stirring speed 200 r/min,temperature from 80℃ to 40℃ with natural cooling,and seed addition 1%（ω）.Under the optimal conditions,the sodium vanadate yield of 61% was obtained,and the purity of the crystal was about 95%.The obtained crystal particles with large size（147 μm） exhibited excellent sedimentation and separation property（sedimentation speed 10 min）.