ABSTRACT
Pulping is the process of separating the fibers, suitable for papermaking, from the non-fibrous material of wood or other fibrous sources. Papermaking is the process of consolidating individual fibers in the pulp into an integrated sheet structure. In the refiner mechanical pulping (RMP) process, wood chips are shredded and ground between the rotating discs of a refiner. New RMP processes employ thermal and/or chemical presoftening of the chips. In the chemical pulping method, the chips are cooked with water and chemicals in a large pressure cooker called a digester which removes lignin and other impurities from the wood. In the sulfite process, a mixture of sulfurous acid and bisulfite ion is used to remove lignin. The sulfite process produces bright pulp that is easy to bleach and refine, but with less strength than kraft pulp. Important properties of pulp for good papermaking are ease of refining, dewatering ability, wet web strength, and dry strength.
