Abstract: The invention relates to a process of producing chlorine dioxide comprising the steps of reducing chlorate ions in an acid reaction medium maintained in a reaction zone of a chlorine dioxide generator, which reaction medium contains alkali metal ions and sulfate ions, so to form chlorine dioxide and a solid salt of acidic alkali metal sulfate. The process further comprises the steps of separating said solid acidic alkali metal sulfate from the reaction medium, contacting said solid acidic alkali metal sulfate with an aqueous medium in a mixing tank to effect at least partial conversion to neutral solid alkali metal sulfate, separating the at least partially neutralized solid alkali metal sulfate from the aqueous medium on a rotary drum filter operating with vacuum inside and with part of the drum submerged in a slurry of the at least partially neutralized solid alkali metal sulfate and the aqueous medium, and forming an acid filtrate.

Abstract: The invention relates to a process for production of an alkaline hydrogen peroxide solution and an acidified alkali metal salt solution containing chlorate in an electrochemical cell including an anode compartment provided with an anode and a cathode compartment provided with an oxygen reducing cathode. In the cathode compartment an aqueous alkali metal hydroxide and hydrogen peroxide is formed, wherein the molar ratio MOH:H2O2 for the net production thereof is maintained from about 0.1:1 to about 2:1. Also a process for simultaneous production of chlorine dioxide is disclosed.

Abstract: A substantial and increasing problem with the pulping chemical recovery system, is the presence of chloride and potassium in the spent liquor entering the recovery boiler. Chloride and potassium increase the stickiness of carryover deposits and dust particles to the recovery boiler tubes, which accelerate fouling and plugging in the upper part of the recovery boiler. The present invention relates to a process by which the content of potassium ions in a recovery system for pulping chemicals can be reduced. The process comprises bringing spent liquor to a recovery boiler, burning said spent liquor, collecting precipitator dust formed, forming a solution by dissolving the precipitator dust in a liquid, where the solution of precipitator dust is subjected to a treatment with an inorganic ion exchange material in order to remove at least a part of the potassium therein.

Abstract: An increasing problem with the pulping chemical recovery system, is the presence of chloride and potassium in the recovery boiler. Chloride and potassium increase inter alia the stickiness of carryover deposits and dust particles to the recovery boiler tubes, which accelerate fouling, corrosion and plugging of the recovery boiler. As the environmental legislation becomes more stringent, the degree of system closure increases. The present invention relates to a process by which the collected precipitator dust is leached, at a temperature exceeding 50.degree. C., for a residence time sufficient to get a chloride and potassium enriched leach solution and to remove at least a part of the content of metal ions in a solid phase. Said leach solution is electrochemically treated, preferably in an electrodialysis cell, in order to remove at least a part of the chloride and potassium therein. By the present process, the problem of sticky deposits in the recovery boiler can be substantially reduced.

Abstract: The invention relates to a process of producing chlorine dioxide comprising the steps of reducing chlorate ions in an acid reaction medium maintained in a reaction zone of a chlorine dioxide generator, which reaction medium contains alkali metal ions and sulfate ions, so to form chlorine dioxide and a solid salt of acidic alkali metal sulfate.

Abstract: Disclosed is a process of producing chlorine dioxide having the steps of providing a reactor with an aqueous acidic reaction medium containing alkali metal chlorate and phosphate; reducing chlorate ions in the reaction medium to form chlorine dioxide; withdrawing chlorine dioxide gas from the reaction medium; withdrawing reaction medium from the reactor and transferring it to an electrochemical cell; treating the reaction medium electrochemically to increase the acidity and decrease the content of alkali metal ions; recycling the acidified reaction medium to the reactor; and adding make up alkali metal chlorate to the reaction medium before or after the electrochemical cell.

Abstract: A process for producing chloric acid, which involves introducing a metal chlorate solution and an acid into separate compartments of an electrodialysis cell to produce a chloric acid solution.