Recovery of Strongly Alkaline Chemicals for the NovaCell Process, 2004 International Chemical Recovery Conference

The NovaCell process is a new and sulfur-free alkaline pulping process under development by a consortium of research institutes and industrial actors. Key process steps for softwood applications include wood chips treatment with anthraquinone and delignification using alkaline cooking liquors formed by partial or full autocausticizing of alkali borates. The objective with this paper is to quantitatively establish and report on the amount of alkali available for cooking and oxygen delignification using different borate autocausticizing recovery schemes. Without substantially increasing the inorganic material flow in the mill liquor cycle relative to kraft pulping, it is possible to produce about 12 –16% effective alkali per ton of wood, which would be sufficient for many applications of the new sulphur free process. To achieve the desired effective alkali generation, the Na/B molar ratio in the cooking liquor should be in the range of 3-5 or expressed as weight ratio Na/B, about 6-10.