Abstract: Desirable chemicals are recovered from a raw material that is formed in substantial amounts during the production of cellulose pulp from renewable lingo-cellulose material. An ammonia/ammonium-containing methanol/water mixture is acidified with an acid that has the ability of forming ammonium salt with the ammonium. The mixture is circulated and passed through an apparatus that has an indirect heat exchanger combined with an storage volume fitted with a gas collection device.

Abstract: A method is provided for controlling the amount of oxidizing bleaching agents in liquors used within the cellulose industry, as in the bleaching of sulphite, sulphate, mechanical, chemimechanical, semichemical or similar cellulose pulps, and in related industries, and particularly for controlling the addition of oxidizing bleaching agents to the system during the bleaching of cellulose pulp by mixing such liquor with at least one chemiluminescent reagent which reacts with the oxidizing bleaching agents in a manner to emit light. The amount of oxidizing bleaching agents in the liquor is then determined by comparison of the light intensity thus obtained with the light intensity for previously measured calibration values corresponding to known quantities of such oxidizing bleaching agents, and then from such determination controlling the addition of such oxidizing bleaching agents to the liquor.