Method for extracting sodium lignin sulfonate from papermaking black liquor employing sulphur treatment

Abstract

The invention discloses a method for extracting sodium lignin sulfonate from a papermaking black liquor employing sulphur treatment. The method is characterized by comprising the following steps: 1, injecting a black liquor into a reaction circulating tank, pumping the black liquor to the top of a reaction absorption tower by using a pump, and spraying down from a solution distribution sieve at the top; 2, feeding an SO2 acid gas generated by a burner into the bottom of a reaction tower by using an exhaust fan through a pipeline, and generating reverse gas-liquid reaction by a gas inside the tower and the black liquor sprayed down from the top; 3, absorbing SO2 in a cycle to carry out sulfuration reaction, so as to control the pH value to 3.5-4.0; 4, sulfonating lignin and finishing winterization to sink into the bottom of the tank after foam of reaction liquid disappears in a precipitation tank, and discharging upper brown liquid to obtain lignin pulp; 5, pumping the pulp into a filter press to filter the liquid by a pump, baking and packaging after crushing a filter cake, so as to obtain the product. The method is low in cost, safety production is achieved, the liquid after reaction is a sodium sulfite solution, and a pulping material, and the solution after lignin is filtered and pressed can be prepared into an alkaline pulp. Thus, cyclic utilization of resources is achieved.

Description

technical field [0001] The invention relates to a method for extracting sodium lignosulfonate from papermaking pulping black liquor. The process is a method for extracting sodium lignosulfonate from pulping black liquor through vulcanization treatment. technical background [0002] The main components of wood are cellulose and lignin, of which cellulose accounts for about 60% and lignin accounts for 40%. In the papermaking process, wood is processed into wood chips, mixed with alkali and put into steaming balls for high-temperature cooking, and the decomposed lignin is dissolved into black liquor. After removing the black liquor, the cellulose is used for papermaking, and the lignin is evaporated and concentrated by black liquor. After burning, the remaining ash contains residual alkali, and the remaining ash is converted into dilute lye and repeatedly cooked and pulped. This is the alkali recovery papermaking process. [0003] The main starting point of alkali recovery tec...

AI Technical Summary

Problems solved by technology

The disadvantage of this process is that the reaction is violent during acid analysis, a large amount of foam is generated, sulfuric acid overflows, and it is easy to cause personal injury. In order to prevent overflow, it can only react in a small equivalent state, resulting in low output and high product cost.

Due to the use of sulfuric acid as raw material, the corrosion resistance requirements of equipment are high. More importantly, in actual operation, concentrated sulfuric acid operation will cause great danger to employees, employees will have great psychological pressure, and the reaction of acid mist will also cause damage to the surrounding environment. Pollution