Treating method for pulping black liquor

Abstract

The invention relates to a treating method for pulping black liquor. According to the invention, a novel process of separating the pulping black liquor from an aqueous solution containing acid by using a diaphragm is utilized, wherein the diaphragm comprises a cation permselective membrane, a filter cloth or a filter screen, a variety of by products with a high added-value such as lignin, white carbon black, salt, sugar, reusable water and the like are separated from the pulping black liquor, so economic feasibility and industrial applicability of process flow are improved, particularly the problem of great consumption of acid in a traditional acid precipitation method is overcome, production cost is reduced, and secondary pollution of acidic waste water is avoided, e.g., waste of acid and cost of lime during neutralization of waste water produced in acid precipitation by using lime in a traditional method are avoided; moreover, the purpose of economical and effective neutralization treatment of acidic waste water without bringing of new pollutants is achieved.

Description

technical field

[0001] The present invention relates to a processing method of pulping black liquor, which relates to the extraction of lignin by acid precipitation treatment of black liquor, and the use of black liquor to neutralize the acid-containing aqueous solution (including other industrial waste acid solutions or newly prepared Acid solution) diaphragm neutralization treatment method to solve the problem of black liquor pollution in pulping enterprises and the secondary pollution of acid-containing aqueous solution after black liquor acid analysis, and to obtain high value-added products. Background technique

[0002] In the process of alkaline pulping, including chemical pulp, semi-chemical pulp or chemical mechanical pulp, the main chemical reaction is that caustic soda reacts with lignin in raw materials to form alkali lignin, which dissolves in lye. The waste liquid obtained from cooking contains a large amount of degradation products such as lignin and hemicellu...