Straw cutting-free method for preparing straw pulp by spherical digester alkali digestion

Abstract

The invention provides a straw cutting-free method for preparing straw pulp by spherical digester alkali digestion. The method comprises the following steps of: washing a straw raw material; adding a hot alkali solution, adding water, mixing uniformly, and heating; performing digestion by adopting a conventional sulfate method or a caustic soda anthraquinone method; stopping the digestion when the lignin discharged from the straw raw material by the digestion reaches 75 to 90 percent, discharging a black liquor I, and thus obtaining straw pulp; and adding the hot alkali solution into the straw pulp, performing digestion and conventional washing and thus obtaining unbleached pulp, wherein the thin black liquor discharged during washing is a black liquor II, the black liquor II and water are added into the new straw raw material together, and the unbleached pulp is continuously obtained by repeating. The straw cutting process is eliminated in the method, so that the flow for preparing the pulp by using the straw is simplified; and on the premise of ensuring the digestion effect, the concentration of the solid matter of the black liquor can be improved to over 13 percent, the stock loss of the raw material is reduced by about 5 percent, the single-pot digestion capacity is improved by 10 to 15 percent, and the yield and the viscosity of the formed pulp are raised with different degrees.

Description

[0001] technical field

[0002] The invention relates to a method for preparing straw pulp, in particular to a method for preparing straw pulp by direct steaming and boiling without cutting the grass, and belongs to the technical field of papermaking. Background technique

[0003] Rice straw and wheat straw, as crop residues, have an annual output of hundreds of millions of tons in my country. They are a huge treasure house of papermaking resources, and once became the main plant fiber raw materials relied on by my country's papermaking industry. However, due to the inherent shortage of rice and wheat straw raw materials, it is difficult to compete with the wood pulping process, and the grass pulping industry is gradually shrinking with the development of my country's paper industry. At the same time, limited wood resources are difficult to form an important support for the raw materials of my country's paper industry, making my country's paper industry more and more depende...