冷冻-蒸发对超高盐浓度工业废水的分盐效果

Effect of Freezing and Evaporation on Salt Separation of Industrial Wastewater with Ultra-High Salt Concentration

采用冷冻-蒸发耦合工艺,研究经机械式蒸汽再压缩(MVR)工艺浓缩后的废水中硫酸钠和氯化钠的分盐过程.首先,在-5~-15℃时探究冷冻温度及停留时间对硫酸钠和氯化钠结晶的影响.结果表明,当冷冻温度为-12.5℃、停留时间为4 h时,模拟废水中硫酸钠和氯化钠的分盐效果最好.其次,将此操作条件应用于实际废水实验后,每100 g硫酸钠结晶的纯度为97.46%,达到GB/T 6009—2014《工业无水硫酸钠》Ⅱ类合格品标准;每100 g氯化钠结晶的纯度为96.86%,达到GB/T 5462—2015《工业盐》精制工业湿盐优级标准.

By adopting the coupling freezing and evaporation technology,this paper researches the salt separation process between sodium sulfate and sodium chloride from wastewater after the mechanical vapor recompression(MVR)concentration.Firstly,the effects of freezing temperature and residence time on the crystallization of sodium sulfate and sodium chloride were studied at-5~-15℃.The results showed that when the freezing temperature was-12.5℃and residence time was 4 h,the salt separation effect was the best.Secondly,after the operation conditions were applied to the actual wastewater experiment,the purity of sodium sulfate crystal per 100 g was 97.46%which reached the standard of GB/T 6009—2014"Industrial Anhydrous Sodium Sulfate"Ⅱclass qualified product standards;meanwhile the purity of sodium chloride crystal per 100 g was 96.86%,which reached the excellent grade standard of refined industrial wet salt of GB/T 5462—2015"Industrial Salt".