Environmentally friendly bagasse pulping with NH 4OH–KOH–AQ

Abstract

Bagasse pulping trials were carried out with NH 4OH–KOH in the presence of anthraquinone for the purpose of reducing or eliminating the black liquor problem in pulping processes. The operating conditions, such as the composition of the cooking liquor, the liquid to bagasse ratio, the maximum cooking temperature and the cooking time at the maximum temperature during the pulping process were investigated systematically to establish optimal pulping conditions. The experimental results indicated that this pulping process is particularly well suited for the pulping of bagasse, where the bagasse was delignified to a low Kappa number value of 11.3, the percentage delignification was 80%, and the pulp yield was 65%. This newly developed pulping process provided a high tensile index of 51.6 N.m/g. The laboratory-scale experimental results were replicated on a pilot-scale process successfully, demonstrating the initial stages of scale-up and also demonstrating a degree of repeatability. There is a good prospect that this process can utilize black liquor, which contains nitrogen, phosphorus, potassium and ammoniacal lignin, as a fertilizer for agricultural production. Hence the black liquor problem associated with the pulping industry can potentially be turned into a benefit through this environmentally friendly bagasse pulping process.