Technical Bulletin No. 0153: Black Liquor Oxidation

The advantages of black liquor oxidation in the kraft pulping recovery system for improving sulfur recovery and reducing air pollution has long been recognized and is employed at a number of mills cooking woods low in fatty substances. However, attempts to apply this process to liquor obtained from fatty woods, such as pine, have not been successful due to the severe foaming problem incurring on oxidation of weak black liquor. The attached Technical Bulletin, which was presented by Mr. Gerald Hawkins at the Annual Meeting of Members of the National Council, describes a new approach to this problem in that the heavy rather than the weak liquor is reacted with atmospheric oxygen. The installation described was based on the observation that foaming of heavy liquor can be controlled by a combination of careful design and the addition of a foam control agent. This bulletin describes in detail the installation at the Pasadena mill of the Champion Paper and Fiber Company's Texas Division, which is the first of its type in the industry.