Defining the benefits of high-kappa kraft pulps for ECF bleaching operations

Today's pulp and paper industry competes on a global basis and pulp manufacturers need to maximize fiber retention and mill productivity while minimizing bleaching costs and addressing all of societal's environmental requirements. Over the past year, our research team has documented the benefits of halting the kraft cook earlier than typically accomplished in most modern pulp mills. Employing modified O and/or OO treatments we have documented process benefits for integrated pulping and oxygen delignification operations. This paper reviews these accomplishments and men examines how high-kappa kraft and single and/or double oxygen stage delignified pulps perform under ECF bleaching conditions employing an D(E+O+P)D sequence. The fully bleached pulps were assessed for their physical strength and optical properties. Differences in bleaching were shown to be due to fundamental changes in the structure of lignin and the pulping and O-conditions employed. These results provide new in-sights into how modern ECF bleaching operations can be improved while reducing costs and enhancing the performance of the final product.