Thermally decomposing waste pulp soln. - at elevated temp. and pressure to give charcoal-contg. slurry and filtering to recover sodium bi:sulphite

摘要

Waste soln. i.e. a waste black soln. obtd. by pulping vegetable fibres (e.g. straw or reeds) is thermally treated at 490 degrees F to 700 degrees F and a pressure of 1,000 to 3,500 psig to give a mixt. of charcoal and slurry. The mixt. is filtered to recover sodium bisulphite. Process is used for recovering valuable material during kraft pulp prodn.