Potential Sulfur-Free Pulping Methods

摘要

The current kraft pulping process has several significant advantages and a number of disadvantages. It can pulp essentially all wood species while producing strong pulps. Over the years, the kraft method has reached a very high state of development. Its major disadvantages are that it produces low yields of hard-to-bleach pulps and it generates odoriferous compounds, such as methyl mercaptan, which are very difficult to suppress or contain. Many alternative sulfur-free pulping methods have been proposed and some of them have been thoroughly investigated. However, none of these methods, to date, has been found to produce a kraft quality pulp at a cost comparable to that of kraft pulp. Anthraquinone catalyzed soda pulping has been proposed as a replacement for kraft pulping. Under practical conditions, this method requires a longer cooking time than does kraft pulping and produces a lower yield of a somewhat weaker pulp.