Abstract: A sparger system for removing sodium chlorate crystal and other crystalline particulate material in slurry form from a tank car comprises a plurality of spray nozzles from which water is expelled as a flat spray initially to dissolve sodium chlorate so as to cavitate the mass of sodium chlorate crystals, which break off in lumps into the cavity and then to impact the walls and roof of the tank car to flush off residual sodium chlorate crystal. The slurry is collected in a sump and is discharged therefrom, with additional sprays agitating the sump to break up clumps of sodium chlorate and to maintain the particulates in suspension.

Abstract: The formation of sodium sulfate by-product in sulfuric acid-based chlorine dioxide generating processes is decreased and preferably eliminated entirely, by effecting electrochemical treatment of sodium ion-containing feed materials for the generator to remove sodium ions and to add hydrogen ions. Sodium hydroxide may be produced as a by-product. The process is generally applicable to the electrochemical treatment of alkali metal chlorates, alkali metal sulfates and mixtures thereof to produce acidified solutions useful in providing chlorate ion-containing feeds to such chlorine dioxide generating processes or for other purposes.

Abstract: Chlorine dioxide, useful as a pulp mill chemical, is produced without producing sodium sulfate effluent for disposal, by effecting reduction of chloric acid in an aqueous reaction medium in a reaction zone at a total acid normality of up to about 7 normal in the substantial absence of sulfate ion and in the presence of a dead load of sodium chlorate added to and subsequently removed from the reaction medium. Chloric acid for the process is produced electrolytically from an aqueous solution of the deadload sodium chlorate and make-up quantities of sodium chlorate. The chloric acid reduction to produce chlorine dioxide may be effected using methanol or electrolytically.

Abstract: The formation of sodium sulfate by-product in sulfuric acid-based chlorine dioxide generating processes is decreased and preferably eliminated entirely, by effecting electrochemical treatment of sodium ion-containing feed materials for the generator to remove sodium ions and add hydrogen ions. Sodium hydroxide is produced as a by-product. The process is generally applicable to the electrochemical treatment of alkali metal chlorates, alkali metal sulfates and mixtures thereof to produce acidified solutions useful in providing chlorate ion-containing feeds to such chlorine dioxide generating processes.

Abstract: Sodium sesquisulfate produced in crystalline form in a high acidity methanol-based highly efficient chlorine dioxide generating process is converted by metathesis to crystalline anhydrous neutral sodium sulfate and the acid recovered as a result is recycled to the chlorine dioxide generating step. The metathesis is effected by contacting the crystalline sodium sesquisulfate with aqueous sodium chlorate solution, aqueous sodium chloride solution, aqueous methanol or water alone. The metathesis is effected in such manner as to minimize the additional evaporative load imposed on the chlorine dioxide generating process by the metathesis medium.

Abstract: A sparger system for removing sodium chlorite crystal and other crystalline particulate material in slurry form from a tank car comprises a plurality of spray nozzles from which water is expelled as a flat spray initially to dissolve sodium chlorite so as to cavitate the mass of sodium chlorite crystals, which break off in lumps into the cavity and then to impact the walls and roof of the tank car to flush off residual sodium chlorite crystal. The slurry is collected in a sump and is discharged therefrom, with additional sprays agitating the sump to break up clumps of sodium chlorite and to maintain the particulates in suspension.

Abstract: Chlorine dioxide is produced from sodium chlorate, sulphuric acid and methanol at the boiling point of the reaction medium under a subatmospheric pressure applied to a reaction zone. High purity of chlorine dioxide production is retained while the proportion of acid sodium sulphate in the product is decreased by effecting the reaction at high acidity in a physically-separate reaction zone from which the reaction products discharge into a mass of recycling sodium chlorate solution.

Abstract: A sparger system for removing sodium chlorate crystal and other particulate material in slurry or solution form from a tank car comprises a plurality of spray nozzles from which water is expelled as a flat spray initially to dissolve sodium chlorate so as to cavitate the mass of sodium chlorate chlorate crystals, which break off in lumps into the cavity and then to impact the walls and roof of the tank car to flush off residual sodium chlorate crystal. The slurry is collected in a sump and is dicharged therefrom, with additional sprays agitating the sump to break up clumps of sodium chlorate and to maintain the particulates in suspension.

Abstract: A sparger system for removing sodium chlorate crystal and other particulate material in slurry or solution form from a tank car comprises a plurality of spray nozzles from which water is expelled as a flat spray initially to dissolve sodium chlorate so as to cavitate the mass of sodium chlorate chlorate crystals, which break off in lumps into the cavity and then to impact the walls and roof of the tank car to flush off residual sodium chlorate crystal. The slurry is collected in a sump and is discharged therefrom, with additional sprays agitating the sump to break up clumps of sodium chlorate and to maintain the particulates in suspension.

Abstract: Phosphorous acid is formed by gaseous phase oxidation of phosphorus with water vapour to form predominantly P.sub.2 O.sub.3 and dissolving the P.sub.2 O.sub.3 so-formed in water. The P.sub.2 O.sub.3 also can be recovered as the product by quenching the P.sub.2 O.sub.3 to a stable temperature using an inert cooling medium rather than water. Oxygen also may be used in conjunction with the water vapour. Sufficiently rapid quenching of reaction products may result in the formation of red amorphous phosphorus from unreacted phosphorus.

Abstract: Chlorine dioxide is generated at high efficiency from feeds of chlorate cell liquor, sulphuric acid and methanol by a hybrid of reaction of sodium chlorate with sulphuric acid and methanol and reaction of sodium chlorate with sulphuric acid and sodium chloride. The reaction medium is maintained at its boiling point under a subatmospheric pressure while sodium sesquisulphate precipitates from the reaction medium.

Abstract: Chloric acid is produced in an electrolytic-electrodialytic process in which chlorate ions from a sodium chlorate solution are transferred through an anion-exchange membrane to combine with electrolytically-produced hydrogen ions in a compartment of a cell, from which the resulting chloric acid is recovered. The sodium ions are transferred through a cation-exchange membrane to combine with electrolytically-produced hydroxyl ions in another compartment of the cell, from which the resulting sodium hydroxide is recovered.

Abstract: Chlorine dioxide is produced electrolytically in the cathode compartment of an electrolytic cell using a three-dimensional high surface-area cathode. The cathode compartment is separated from an anode compartment by a cation-exchange membrane. Sodium chlorate is reacted with hydrogen ions and chloride ions in the cathode compartment and chlorine dioxide is vented from the cathode compartments. Chlorine co-produced with the chlorine dioxide is reduced at the cathode to provide chloride ions for the reaction while electrolytically-produced hydrogen ions are transferred across the membrane from the anode compartment to the cathode compartment to provide hydrogen ions for the reaction.

Abstract: Dichromate values, or other soluble hexavalent chromium values, are removed from cell liquor or other aqueous media containing the same by cathodically reducing the same to trivalent chromium, which deposits on the cathode as chromium hydroxide. The cathode has a high surface area three-dimensional structure which exposes the electrolyte to electrolysis for a relatively long period of time. An electrode potential of about 0 volts vs. SCE is applied to the cathode. Once the electroconductive sites on the cathode become exhausted, the cathode is regenerated chemically or electrochemically for reuse in further dichromate removal.

Abstract: A hydrochloric acid-based chlorine dioxide generating process is integrated with an electrolytic process for sodium hydroxide production. Generator liquor in the form of a sodium chloride-enriched solution from the chlorine dioxide generator is passed to the central compartment of a three-compartment cell. Hydrogen ions formed in the anode compartment of the three-compartment cell migrate through a cation-exchange membrane to the central compartment to form hydrochloric acid with the sodium chloride solution while sodium ions migrate through a further cation-exchange membrane to form sodium hydroxide with hydroxyl ions produced in the cathode compartment of the three-compartment cell. The acidified generator liquor containing the hydrochloric acid formed in the central compartment is forwarded to the chlorine dioxide generator to provide half the acid requirement therefor.

Abstract: Peroxydisulfuric acid and its salts are produced electrochemically from an aqueous acid sulfate solution using a glassy carbon anode in the presence of fluoride ions dissolved in the anolyte. A low cost alternative to platinum is provided and high current efficiencies are obtained.

Abstract: Chlorine dioxide is formed by reduction of sodium chlorate in a sulphuric acid-containing reaction medium. Sulphuric acid is introduced to the reaction medium in air atomized form to promote rapid and efficient mixing of the sulphuric acid, thereby avoiding chlorine dioxide decomposition at hot spots resulting from inefficient mixing of acid with the reaction medium.

Abstract: By-product hypochlorite from the electrolytic production of chlorates, notably sodium chlorate, is used to form hexavalent chromium for use in the electrolysis process by oxidation of trivalent chromium compounds by the hypochlorite. The hypochlorite may be the condensate produced by treatment of the chlorate cell by-product gas stream and/or present in the cell liquor.

Abstract: Hypochlorite present in cell liquor or other aqueous chlorate solution is reduced electrolytically in the presence of dischromate using a high surface area cathode having a three-dimensional electrolyte-contacting surface. An electrode potential more positive than -1 volts vs. SCE is applied to the cathode.

Abstract: Chlorine dioxide is formed by an autocatalytic electrochemical process from highly acidic chlorate solution containing a residual concentration of chlorine dioxide. Cathodic current is applied to the solution by an electrode which does not otherwise catalyze the chemical formation of chlorine dioxide from the acidic chlorate solution. High purity chloride dioxide is obtained while half the acid is consumed and half the water is produced as compared with a conventional chemical chlorine dioxide generating process.