Cold Soda and Alkaline Peroxide Chemimechanical Pulping of Cotton Stalk, 2002 Fall Technical Conference

Egyptian cotton stalks were pulped in a blender, using cold soda and alkaline peroxide chemimechanical (APMP) processes. Overall yields for both processes were low, but comparable to values found for semichemical pulping in the literature. Strength values were lower than for chemical pulping but comparable to literature values for semichemical pulping. For the cold soda process, the alkali concentration during soaking decreased the yield for both the soaking and refining stages, but it had little effect on fiber development during and sheet properties after secondary refining. A similar effect was found for soaking time. Higher soaking temperature increased the freeness level at a given secondary refining time and improved tear strength, but it had no effect on tensile or burst strength. An increase in primary refining time caused a decrease in tear strength. Pulps produced from the APMP process were 50 % brighter and slightly weaker than for the cold soda process, and they required significantly less secondary refining to reach a given freeness level. An increase in the concentration of alkali and peroxide caused a decrease in both soaked and refined yields. Increased chemical concentration slightly reduced the secondary refining time required to reach a given freeness level, but it had no effect on strength at a given freeness. An increase in the alkali/peroxide ratio during soaking caused a decrease in screened rejects and an increase in screened yield. Higher ratios resulted in slightly higher freeness values at a given secondary refining time, and they also produced slightly higher tensile and moderately lower tear strength. Brightness was decreased as the ratio increased.