Two-step straw processing a new concept of silica problem solution
Paul Daniel Fleming III.
Department of Paper Engineering, Chemical Engineering, and Imaging
Western Michigan University, A-231 Parkview, Kalamazoo MI 49008
Two-step wheat, and rice straw processing, as a new concept of agricultural by-product utilization, is
presented. The first step includes wet removal of ash/silica, the second step includes conventional non-sulfur
high-yield pulping. The strength properties are shown and compared with the properties of conventional
hardwood high yield pulp (fluting). The beneficial effect of alkali pretreatment of straw on ash/silica removal
was confirmed. Under the same experimental conditions of impregnation step, the desilication rate of the
wheat straw sample (WS I) reached the value of 90.8%, based on acid insoluble ash (AISA) content, while the
desilication rate of rice straw samples were determined to be 32.7% (RS I) and 51.0% (RS II) respectively.
The lower number for RS I was caused, most likely, by a lower charge of impregnation chemical. Also, the
positive effect of the impregnation, that causes more extensive combined degree of delignification and
desilication, was demonstrated. The fact that the most of the strength properties of impregnated and delignified
straw samples exceed the strength properties of commercial pulp, as well as the properties of the laboratory
samples (red oak, wheat straw) processed without the impregnation, is another positive finding.