Upgrading of Old Corrugated Cartons to Bleached Pulp Using TCF and ECF Delignification and Bleaching Sequences, 1994 Pulping Conference Proceedings

Steven T. Haywood

There is an increasing demand for recycled fibre content in all grades of pulp and paper products. A potential source of recycled fibre for the production of chemical pulps is old corrugated containers (OCC). Reports in the literature suggest that the most effective manner of upgrading this furnish is to use a kraft cook initially to decrease their high lignin content (kappa number ranges between 80 and 100). Laboratory trials show that well fractionated OCC pulps can be successfully upgraded to bleached kraft pulp using a combination of oxygen delignification and chlorine dioxide or hydrogen peroxide and ozone. TCF bleaching sequences yielded pulps with ISO brightness values of 70-75%, but with a large decrease in pulp viscosity. Oxygen delignification combined with a chlorine dioxide stage yielded a pulp with an ISO brightness >80% and a much smaller decrease in pulp viscosity. These sequences were use to upgrade recycled fibres to produce a pulp with properties similar to those of a bleached kraft pulp.