APPARATUS AND METHOD OF RECOVERING UNBLEACHED KRAFT PULP FROM OLD CORRUGATED CARDBOARD

摘要

A method and an apparatus for recovering unbleached Kraft pulp are provided to reduce the residual amount of lignin and remove petrochemical materials, thereby improving the quality of products manufactured by the unbleached Kraft pulp. Waste corrugated paper and white water are continuously inputted into a roughening pulper(1). The waste corrugated paper is roughened into recycled corrugated cardboard, corrugated media, and Kraft linerboard pieces within the roughening pulper, and then discharged to a first rotary screen(8). Undischarged large Kraft linerboard pieces and waste are shattered, and then discharged to the first rotary screen. The Kraft linerboard pieces are separated into recycled corrugated cardboard, corrugated media, and Kraft linerboard pieces. The recycled corrugated cardboard and the corrugated media are discharged to a single fiber chest(10), and the Kraft linerboard pieces are discharged to a bleaching pulper(11). The Kraft linerboard pieces are roughened by water containing caustic soda in the bleaching pulper, and at the same time, the residual amount of lignin of unbleached Kraft pulp is reduced by making residual lignin of unbleached Kraft pulp react with oxygen contained in air. External particles and waste are removed from the unbleached Kraft pulp stuff. Petrochemical materials are removed from the unbleached Kraft pulp stuff. The white water is removed from the unbleached Kraft pulp stuff. The resultant unbleached Kraft pulp stuff is discharged to a pulp chest.