Kraft Cooking With Split Sulidity - A Way to Break the Yield Barrier?, 1998 Breaking the Pulp Yield Barrier Symposium Proceedings

In recent years, a number of liquor making processes aimed at improving both conventional and modified kraft cooking, have been proposed. These innovations seek to produce two(or more) white liquors of chemical concentrations optimized for the different phases of the cook. The processes would enable the digester operator to feed the chips a hydrosulfide-rich liquor early in the cook, followed by a hydrosufide-lean (or an alkali-rich liquor, or liquors), later in the cook.

The results of laboratory and other work aimed at elucidating the effects of this improved cooking regime for a variety of base kraft cooking technologies are reviewed. Specifically, the effect on cooking selectivity, wood yield, and pulp strength are covered. The proposed liquor making technologies are described in conceptual terms and practical process options, for integrating the new processes with a variety of conventional and modified pulping systems, are outlined.