铝酸钠溶液蒸发过程中的结垢与防垢

以氧化铝生产中种分母液为对象，研究铝酸钠溶液蒸发过程中碳酸钠和硫酸钠等杂质盐的析出行为及其影响因素。采用对比实验法，研究防垢添加剂对减缓铝酸钠溶液蒸发过程中加热面结垢的影响。研究结果表明：随着苛性碱浓度的升高，铝酸钠溶液中碳酸钠和硫酸钠的平衡浓度明显降低：随着温度降低，碳酸钠和硫酸钠的平衡浓度下降；根据实验结果提出铝酸钠溶液中碳酸钠和硫酸钠平衡浓度与氢氧化钠浓度、温度等因素的定量变化关系式：GR-12、GR-3、GR-4等添加剂防垢效果明显，可降低结垢量60％-70％，有效减缓加热面结垢的形成速度，并抑制溶液中硅的析出。

Scaling and anti-scale in evaporation process of sodium aluminate solutions

Precipitation behavior of Na2CO3 and Na2SO4 in the evaporation process of sodium aluminate solutions and its influencing factors were respectively investigated. Simultaneously, the effects of various anti-scale additives on retarding scaling of heating surface in the evaporation process of sodium aluminate solutions were studied by adopting the contrast experimental method. The quantitative relation of the equilibrium concentrations of Na2CO3 and Na2SO4 of spent liquors in the evaporation process with NaOH concentration and temperature was presented based on all the experimental data, The results show that the equilibrium concentrations of Na2CO3 and Na2SO4 in the sodium aluminate solutions markedly decrease along with the increase of caustic alkali concentration and the decrease of temperature, Addictives types GR- 12, GR-3 and GR-4 possess good effectiveness, which can reduce the scale quantity by 60%-70% and effectively retard the formation rate of scaling on the heating surface and restrain SiO2 from precipitating.