Aa. Zaman et Al. Fricke, EFFECT OF PULPING CONDITIONS AND BLACK LIQUOR COMPOSITION ON NEWTONIAN VISCOSITY OF HIGH SOLIDS KRAFT BLACK LIQUORS, Industrial & engineering chemistry research, 35(2), 1996, pp. 590-597
The influence of black liquor composition and solids concentrations on
the Newtonian viscosity of slash pine black liquors over wide ranges
of temperature (up to 140 degrees C) and solids concentrations (betwee
n 50% and 83% solids) has been studied. It was found that the zero she
ar rate viscosity of high solids black liquors depends strongly on the
cooking conditions and/or black liquor composition. Not only is high
solids viscosity affected by lignin molecular weight and lignin concen
tration in the liquor but other organic and inorganic constituents of
black liquor also make a significant contribution to viscosity. The de
pendency of zero shear rate viscosity on solids concentrations, and te
mperature is defined. The Newtonian viscosities vary over a wide range
depending on temperature, solids concentrations and solids compositio
n. The results indicate that, at fixed levels of effective alkali and
sulfidity, the zero shear rate viscosities can be described as a funct
ion of both Lignin concentration and lignin molecular weight. The visc
osity of black liquor is an increasing function of the organics-to-ino
rganics ratio and is a decreasing function of the concentration of sod
ium and chloride ions and pH of the liquor.