Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Including recovery of organic by-product
Patent
1994-11-21
1997-08-26
Czaja, Donald E.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Including recovery of organic by-product
162 301, 162 31, 162 51, D21C 1112, D21C 1106
Patent
active
056606850
ABSTRACT:
A method of preparing a digesting liquor having high sulphidity from a spent liquor obtained from digesting cellulosic fiber material, optionally without a conventional causticizing step is provided. Thermal decomposition of the spent liquor is conducted under reducing conditions in a reactor at a pressure of from atmospheric pressure up to about 150 bar and at a temperature of about 500.degree. to 1600.degree. C. so that a combustible gas phase containing hydrogen sulphide is formed in the reactor and extracted therefrom, and a phase of solid or molten material of substantially sodium sulphide or potassium sulphide, or mixtures thereof. The solid or molten material is dissolved in an aqueous liquid to produce said digesting liquor. The invention hydrogen sulphide is recovered from the gas phase and returned to the reactor to be present during the thermal decomposition of the spent liquor.
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Chemrec Aktiebolag
Czaja Donald E.
Nguyen Dean T.
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