稻草制浆黑液除硅工艺的研究

Research on Silica Removal from Black Liquor of Rice Straw Pulping

将烟道气和石灰除硅工艺结合起来,提出二级除硅法。一级除硅,利用模拟烟道气中的CO_2,将黑液中硅酸钠转化为二氧化硅水合物沉淀;二级除硅,用石灰与硅酸钠反应生成硅酸钙沉淀。二级除硅法提高了除硅效率,降低黑液再碱化费用,既回收利用了二氧化碳碳资源,又消除了硅干扰。探讨了p H值、石灰加入量、反应温度对硅去除率的影响,当pH值为9.0,反应温度为20℃时,一级除硅率达到65.21%。CaO投入量与黑液中硅含量的摩尔比为5,反应温度为20℃时,总除硅率达到82.49%。

Two steps method of flue gas and lime was used to remove silicon in black liquor. In the first step, CO2 simulated from flue gas was reacted with sodium silicate to form silica hydrate sediment. In the second step,lime was used to react with sodium silicate to form calcium silicate sediment. Two steps silicon removal can improve the efficiency of silicon removal,decrease the cost of making alkaline in black liquor. It can a-chieve the recycle of carbon resource in carbon dioxide and efficient silicon removal. The effects of pH,input a-mount of lime and temperature on the silicon removal percentage have been investigated in detail. When pH value reached 9. 0,the percentage of silicon removal during the first step could reach 65. 21% at the tempera-ture of 20℃. When the mole ratio of CaO/Si was 5,the total silicon removal percentage reached 82. 49% at the temperature of 20℃.