Research on silicon removal with oxides addition in kraft pulping of bamboo

Abstract

High silica content of bamboo results in a silica problem during the chemical recovery process. The lime mud of bamboo cannot be reused after the causticization process due to its high silica content. Therefore, it was discharged as solid waste. To solve this problem, adding oxides (Al 2O 3, MgO, CaO) in the kraft pulping of bamboo was studied. The effect of adding oxides on the characteristics of the pulp and black liquor was analyzed. The results showed that the addition of oxides could reduce most of the silicon content in bamboo black liquor. Five percent of the above mentioned oxides were added to the kraft process, respectively, which results in at least of 80% removal of silicon. Considering the cost and quality of pulp and black liquor, 1% Al 2O 3 or 3% MgO or 3% CaO are appropriate dosages for bamboo kraft pulping, which helps to reduce the silicon accumulation of lime mud in bamboo pulp.