Patent ID: 6183598
Filing Date: 2001-02-06
Classification: D21C,Y02P

Abstract:
A process for recovering alkali and energy from soda process black liquor containing silicate comprising the steps of:(a) neutralizing said soda process black liquor containing silicate with a surplus of a gas containing over 60% by volume of carbon dioxide, to obtain a precipitate rich in silica and black liquor poor in silicate;(b) separating said precipitate rich in silica from said black liquor poor in silicate;(c) evaporating said black liquor poor in silicate to an evaporated black liquor; and(d) burning said evaporated black liquor with pure oxygen gas or oxygen-enriched air after said evaporated black liquor has been brought to a temperature near its boiling point under substantial over-pressure to recover a sodium carbonate melt and to form a gas containing mainly carbon dioxide which supplies the carbon dioxide of step a).