New Approach to the Non-Wood Black Liquor Problem, 2001 Pulping Conference Proceedings
B. Myreen--Silicate ions in black liquor from soda cook of non-wood fiber materials cause problems in the recovery of sodium and energy from the liquor. When adding carbon dioxide to the liquor, the pH of the liquor decreases and the silicate solidifies as silica that can be separated from the liquor by filtration. The new approach differs from previous attempts in three ways: The black liquor is saturated with carbon dioxide, technically pure carbon dioxide is used, and the precipitate is separated from the liquor in efficient variable-chamber filter presses. Black liquor burnt in an oxidizer with oxygen instead of air generates the required carbon dioxide. The oxidizer can be used to burn all the black liquor generated at the mill, or only about 10 % of the liquor that is sufficient to generate the carbon dioxide required for desilication of the total amount of black liquor.
New Approach to the Non-Wood Black Liquor Problem, 2001 Pulping Conference Proceedings