Controlled black liquor viscosity reduction through salting-in
- North Carolina State Univ., Raleigh, NC (United States)
Black liquor viscosity increases exponentially with solids content and therefore causes processing problems for the paper industry by being a limiting factor in the Kraft pulp process. This study investigates a new approach for achieving viscosity reduction by salting-in black liquor through the addition of thiocyanate salts. These salts generally increase the solubility of the polymer constituents in black liquor, leading to a decrease in its viscosity. Several thiocyanate salts capable of reducing liquor viscosity by more than two orders of magnitude have been identified, with viscosity reduction greatest at high solids content. Salting-in of black liquor depends on the cation paired with the thiocyanate anion, as well as on solution pH and temperature. Comparative studies reveal the most effective viscosity-reducing agent of the series examined and that lignin plays an important role in the viscosity behavior of both unmodified and salted-in black liquor at high solids concentrations. These experimental findings are interpreted in terms of the underlying principles that describe salting-in and how it affects aqueous solution structure.
- OSTI ID:
- 367868
- Journal Information:
- AIChE Journal, Vol. 42, Issue 8; Other Information: PBD: Aug 1996
- Country of Publication:
- United States
- Language:
- English
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