Method for removing silicon in green liquid through cooperation of calcium oxide and aluminum salt

Abstract

The invention relates to a method for reducing the silicon content in a green liquid of a non-wood fiber material pulping causticization section through the cooperation of calcium oxide and aluminum salt. In the method, calcium oxide and aluminum sulfate, aluminum oxide, aluminum hydroxide or sodium metaaluminate are sequentially added into the green liquid of the causticization section, the temperature is 90-100 DEG C in the reaction process, a stirrer is used for continuous stirring in the reaction process, the reaction time is 25-30 minutes, and insoluble precipitate is removed by filtration after the reaction is completed. The method is provided for the green liquid produced during non-wood fiber material pulping, and comprises the following steps: adding calcium oxide and aluminum salt into the green liquid of the pulping causticization section to react with silicate in the green liquid so as to generate insoluble precipitate, then filtering to remove the generated insoluble precipitate from the green liquid. The method can achieve a silicon removal rate higher than 87%, and ensures that white slime can be used for calcining and recycling lime after causticization.

Description

technical field [0001] The invention belongs to a process for removing silicon from green liquor recovered from pulping alkali in the papermaking industry, and in particular relates to a method for synergistically reducing the silicon content of green liquor by using calcium oxide and aluminum salts. Background technique [0002] Non-wood fiber papermaking raw materials are an important renewable fiber resource in my country. Especially in today's society with enhanced awareness of environmental protection and energy crisis awareness, it is very important to correctly understand the importance and position of non-wood fiber raw materials in my country's pulp and papermaking. necessary. Due to the special reasons of the non-wood fiber raw material itself, the content of hemicellulose is higher than that of wood, there are more miscellaneous cells, and the ash content is high. Silica accounts for more than 60% of the ash content, resulting in the problem of "silicon interferenc...

AI Technical Summary

Problems solved by technology

2. Add lime to the green liquor, that is, the two-step causticization method for silicon removal technology, that is, in the first step, only 30% of lime is added for causticization, and white mud is discharged outside the plant, and in the second step, 70% lime is added for causticization , the resulting lime mud is calcined and reused for causticization, the removal rate of silicon in this method is 56%, but the white mud obtained in the second step of causticization still contains a large amount of silicon

In addition, the generated sediment has fine particle size and high viscosity, which is not easy to separate from the green liquor, and the residual alkali value of white mud is relatively high

None of the above methods solve the "silicon interference" problem