Holopulping

Name:
Holopulping
Detailed information:
A method for making paper pulp without use of sulfur compounds that has been proposed as an eventual replacement for the kraft process (sodium sulfate). More selective delignification of the wood fibers is obtained by alkaline oxidation of extremely thin (0.03 inch) wood chips at low temperature and pressure, followed by solubilization of the lignin fraction. Holopulping has other advantages over the kraft process: (1) A 65–80% carbohydrate yield compared to 45–50% for kraft. (2) Holopulp may be used for a dense paper such as glassine or for a bulky board. Its use in tissue and printing grades offers improved strength. (3) Low temperatures and atmospheric pressure. (Kraft pulping is carried out at 170C and under pressure.) Readily adaptable to continuous operation and automatic control. (4) Air pollution is greatly reduced because the organic materials are burned and few odorous compounds are formed. Stream pollution is minimized by countercurrent washing. The remaining calcium sludge waste is easily disposed of without harmful effects.