Studies on the Silica Removal by Calcium Oxide Addition from the Black Liquor of Bamboo Sulphate Pulping

摘要

In the sulphate pulping of Grasses such as bamboo, a large amount of silica from the raw materials dissolves in the black liquor. The method of calcium oxide addition as the procedure of silica removal was examined. Calcium oxide addition into the unoxidized black liquor was more effective, and in 120% of calcium oxide addition of the theoritical amount against the silica contents in the black liquor, a considerable quantity of silica was removed from the black liquor. That is, 67～83% of silica in the black liquor was removed and the silica contents in the treated black liquor decreased to 1.8～1.0g/l from 5.0～7.2g/l. During the process of silica removal by calcium oxide addition, the decreases of organic matter and sodium content in the black liquor were not recognized.