RHEOLOGY OF EUCALYPTUS AND PINE KRAFT BLACK LIQUOR

Abstract

Black liquor is a by-product of pulp mill and is the 5th most used fuel in the world. More than 1.3 billion tons of weak black liquor are processed each year and about 200 million tons of dry solids are burned in recovery boilers The objective of this work is to study the chemical, rheological, and behavioral differences between liquors produced from pine and eucalyptus wood, which directly influence transfer work, their use as fuel, and the production of cellulose pulp. The results show that the black liquor of eucalyptus has a higher concentration of lignin and a lower lignin molar mass than the pine liquor. This is because, in the pulping process, the weaker bonds of the lignin contained in eucalyptus wood mean that it has a much higher concentration and becomes more fragmented when it enters the liquor.