PROCESS AND APPARATUS FOR BLEACHING OF PULP

摘要

A process for the rapid bleaching of pulp in which chlorinated pulp is formed into a sheet on a moving foraminous surface and subjected to chlorination stage washing, a rapid first alkaline extraction, and further washing after the extraction. The treatments involve displacement of one liquid by another. The first alkaline extraction may be performed in two steps with the alkaline liquor used in the second of the steps comprising a mixture of a) recycled alkaline liquor displaced from the sheet by the washing water, b) washing water which has passed through the sheet, and c) fresh caustic. The rapid alkaline extraction replaces a complete alkaline extraction stage which would include a steam mixer, a retention tower and a washer.