In order to evaluate the effect of alkali concentration on soaking yield and on the properties of the pulp obtained by subsequent oxygen cooking, the oxygen pressure, anthraquinone charge, cooking time, temperature and liquor to bagasse ratio were studied, it can be concluded that, the best delignification results by different alkali soaking and subsequent oxygen cooking in different NaOH concentation are achieved at each of the following, 14% NaOH for experiments which are done at 4%, 8% and 14% NaOH concentration of soaking stage, 16% NaOH in oxygen 14% NaOH concentration of soaking stage, 16% NaOH in oxygen pulping for experiments done at 6% NaOH soaking and 10% and 12% NaOH for experiments done at the same alkali charge of soaking stage. It can be also concluded that, the two-stage alkali-oxygen pulping of bagasse gave higher pulp yield at the same kappa number and R_(10) value, than single-stage alkali-oxygen pulping of bagasse under the same cooking conditions. Generally, this study shows that the impregnation stage before alkali-oxygen cooking of bagasse is represented as a successful process, giving higher screened pulp yield, (4-11%), higher alkali resistance and lower kappa number compared to single stage of alkali oxygen pulping of bagasse.
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