Method for cooking grass raw materials at two stages with soda anthraquinone by adding black liquor

Abstract

The invention discloses a method for cooking grass raw materials at two stages with soda anthraquinone by adding black liquor. According to the characteristic of quick delignifying of the grass raw materials by adopting alkaline cooking, low temperature and normal pressure are adopted in a first stage, and black liquor is added for cooking at the two stages. A cooking result indicates that the Kappa number of paper pulp, the yield of screened pulp, the residual alkali in the black liquor and the like are uniform and stable, and stable operation can be realized. Compared with the conventional soda anthraquinone cooking method, the two-stage cooking method disclosed by the invention has the advantages: operation can be performed under low temperature condition, and the alkali amount is reduced, the yield of screened pulp is increased and the residue sieving rate is low under the condition that the Kappa number is basically the same. Moreover, O-DQ-P and O-Q-P-P bleaching are performed on pulp obtained by using the two-stage cooking method and the conventional soda anthraquinone cooking method, and the physical property of the pulp is detected. A result indicates that the whiteness and the viscosity of bleach pulp obtained by the two-stage cooking are higher than those of bleach pulp obtained by the conventional cooking, and the bleach pulp has better bleachability and higher mechanical intensity, and can be used for making writing paper, offset printing book paper and the like.

Description

technical field [0001] The invention belongs to the technical field of pulping and papermaking, in particular to a two-stage cooking method of grass raw material caustic soda anthraquinone added with black liquor. Background technique [0002] Today's paper industry in the world uses wood as the main raw material, but because my country is a country with a relative shortage of forest resources, the supply of wood pulp for papermaking has been seriously insufficient for a long time, and a large amount of commercial wood pulp has to be imported every year. In order to better develop my country's papermaking industry, we must face up to the particularity of our country's papermaking raw material structure, strive to make good use of grass pulp, and do everything possible to make good use of our country's large quantity and relatively low-priced grass resources. This will affect the development of my country's papermaking industry. has a pivotal role. Wheat straw, bagasse and re...

AI Technical Summary

Problems solved by technology

The method is to add all the cooking alkali at the beginning of cooking. Since the concentration of alkali in the early stage of cooking is high, it is easy to cause the degradation of hemicellulose, so the yield of pulp is low; Continuous consumption, the alkali concentration in the later stage of cooking is low, so it is not conducive to the removal of lignin, resulting in higher hardness of pulp

The existing two-stage cooking method of caustic soda anthraquinone of grass raw materials added with black liquor in scientific research is mostly cooked according to the cooking process of wood, that is, the first stage of cooking or black liquor pretreatment is carried out at a temperature above 120°C. The temperature of liquid pretreatment is higher, all above 100°C, so the energy consumption of cooking is higher

In addition, it is well known that due to the fast delignification rate of grass raw materials, the temperature of a large amount of delignification is raised below 100°C, so it is not reasonable to carry out black liquor pretreatment or first-stage cooking at a temperature exceeding 100°C

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