麦草碱回收绿液铝盐法除硅研究

Silica removal from green liquor with aluminum sulfate in alkali recovery process of wheat straw pulping

非木材纤维原料硅物质含量高,影响碱回收系统的运行。研究了麦草浆绿液铝盐法除硅效果及对绿液的影响,并通过能谱分析对铝盐绿液除硅机理进行了初步探讨。结果表明:绿液铝盐法除硅可有效降低绿液的硅含量,当铝盐用量/绿液硅含量为1∶1时,除硅后麦草浆绿液硅含量为1.62g/L(以SiO2计),除硅率为78%。铝盐与绿液中的硅生成硅铝酸钠沉淀,降低了绿液中的硅含量,这是铝盐除硅机理中的一个重要方面。

The high silicon content in green liquor of non-wood material pulping hindered the progress of alkali recovery and the recycling of lime mud. The desilication rate with aluminum sulfate in green liquor of wheat straw pulping was investigated in this paper. The desilication mechanism of aluminum sulfate was also discussed. The results show that the desilication rate increased rapidly with increasing aluminum sulfate loading. It had a desilication rate of 78% in green liquor of wheat straw pulping when the ratio of aluminum sulfate and silicon content in green liquor was 1：1. Silicon content in green liquor of wheat straw decreased to 1.62g/1 （based on SiOz）. Silicon in the green liquor reacted with aluminum sulfate and to form sodium aluminosilicate precipitation. The lowered silicon content in green liquor can be attributed to the generated sodium aluminosilicate precipitation. This was a significant factor of the desilication mechanism of aluminum sulfate.