PRODUCTION OF CELLULOSE BY THE SODA-ANTHRAQUINONE PROCESS (SAP) WITH RECOVERY OF THE BOILING CHEMICALS

摘要

For the manufacture of cellulose from wood and annual plants, there is provided a boiling formatting process wherein the boiling liquor has a free sodium hydroxide and optionally of sodic salts of alkylbenzenesulfonic acids or carboxylic acids aromatic and aliphatic. By addition of anthraquinone or derivatives of this substance in the boiling liquor, it enhances the delignification. It is no longer necessary to limit the quantities of hydroquinone added, because of the price of this substance, that anthraquinone is resistant to wet oxidation and can be reused in the boiling implementation process. The solubility and therefore the action of the anthraquinone are increased through the use of salts of sulfonic acid. To recover the boiling chemicals present in the black liquor, it is proposed to precipitate the lignin present in the solution with a mineral acid or a carboxylic acid, where appropriate, to separate the hemicelluloses by ultrafiltration and resins by extraction and burning the remaining organic compounds and salts of sulfonic acid and salts of the carboxylic acid by oxidation in aqueous phase with air and / or oxygen. The solution of chemicals released by the decomposition products of the wood can be reintroduced into the liquor after causticizing carbonates, and providing after partial crystallization of salts of aliphatic carboxylic acid, in the production circuit cellulose. The isolated by crystallization sodium acetate can be separated into acetic acid and sodium hydroxide by electrolysis carried out with a membrane. The lye is reintroduced in the cooking process and acetic acid is treated separately.