Process for the production of polysulphide pulping liquor from pulp mill recovery smelt

摘要

Sodium polysulphide is formed by reacting sodium sulphide and sodium sulphur-oxygen salts in the presence of carbon and oxygen. The invention is particularly applicable to reacting recovery furnace smelt from a polysulphide pulping process to form a mixture of sodium polysulphide and sodium carbonate which is substantially free from sodium sulphur-oxygen salts, so that dead-load sulphidity is substantially eliminated from the pulping liquor.