RAPID SODA PULPING OF WHEAT-STRAW BY THE IMPREGNATION RAPID-STEAM-PULPING PROCESS

Production of chemical pulp from wheat straw was studied at the bench scale using a conventional soda process and a two-stage cooking sequen ce. The two-stage sequence involves impregnation of the straw with cau stic liquor, withdrawal of excess liquor, and rapid (less than or equa l to 4 min) steam treatment of the impregnated material at 160-215 deg rees C. The impregnation-rapid-steam-pulping (IRSP) sequence for wheat straw shortens the total processing (impregnation + cooking) time to less than 15 min. Strength properties of IRSP pulps are comparable wit h those of both conventional wheat-straw soda pulps and hardwood kraft pulps when refined to a freeness of 300 mL CSF.