Four pulping methods-Kraft (KS), Kraft-Anthraquinone (KSAQ), Polysulfide (PS) and Polysulfide-Anthraquinone (PSAQ) were used in laboratory to produce pulp and black liquor. Differential thermal analysis was then used to evaluate the activation energies of the black liquors. These data were used to study the burning characteristics of black liquor and improvement of pulping method. Commercial black liquors were also used for evaluation and comparison. Some important conclusions resulting from this research are summarized bellow:
Differential thermal analysis method can be used to measure the activation energy of black liquor and the data can be used to study the burning characteristics of black liquor.
The lower the O/I ratio of black liquor, the higher the activation energy of black liquor, and more difficult to burn the black liquor in furnace.
For the same sulfate pulping process with a low optimum alkali, a high pulp yield and low activation energy of black liquor can be obtained.
The pulp yields of the four pulping methods used in the laboratory with the same alkali dosage are in the following sequence:
PSAQ>PS>KPAQ>KP of
The activation energies of the four black liguors are in the following sequence:
PSAQThe activation energies of the black liquors from two commercial pulp mills are rather high. It indicated that the pulping methods of the mills could be improved.
