麦草浆黑液除硅工艺研究

Study on Silicon Removal Process for Wheat Straw Pulping Black Liquor

用沉淀法和气浮法进行麦草浆黑液除硅工艺研究。结果表明,两种方法均能有效地降低黑液中的硅含量。在实验条件下,优选出的沉淀法除硅条件为:MgO用量5g/L,Ca(OH)2用量16 g/L,Fe2(SO4)3用量60mg/L,温度40℃;在此条件下,黑液的Si去除率可达89%。优选出的气浮法除硅条件为:Al(NO)3用量8g/L,月桂酸用量1g/L,乙醇用量100mL/L,温度60℃;在此条件下,黑液的除硅率达90%以上。适当调节黑液的pH值,对改善气浮法的除硅效果有利,既可提高硅的去除率,又能维持黑液中较低的Al元素含量,有利于黑液碱回收的进行。

The silicon removal of wheat straw pulping black liquor by means of both processes of the sedimentation and the air-floatation was studied. The results showed that each process used could effectively decrease the content of silicon of black liquor. The optimal silicon removal conditions for sedimentation process are; MgO dosage 5 g/L, Ca（OH）2 dosage 16 g/L,Fe2（SO4）3 charge 60 mg/L,temperature 40℃ and the silicon removal rate can reach 89% under these conditions. On the other hand, the optimal conditions for air-floatation process are as follows： Al（NO）3 charge 8 g/L, lauric acid dosage 1 g/L, ethanol dosage 100 ml/L, temperature 60℃, and silicon removal rate is higher than 90%. In the meantime, an appropriate adjustment of the pH of black liquor will not only considerably increase the removal rate of silicon, but also maintain a lower residual content of aluminum in the air-floatation process. It is of benefit to the successful operation of the alkali recovery of straw pulping black liquor.