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US 5,399,332 AGranted
Dynamic leaching procedure for metathesis
AssigneeSterling Canada, Inc.
InventorChunmin Pu
Life of this patent
Estimating the term…
Abstract
Solid sodium sesquisulfate is metathesized by water to neutral anhydrous sodium sulfate and to recover the acid values therefrom by employing a dynamic leaching of the solid phase sodium sesquisulfate, to provide an acid medium for recycle to a chlorine dioxide generating process producing the sodium sesquisulfate without significantly increasing the evaporative load on the generator.
Claims14
A process for the conversion of sodium sesquisulfate to neutral anhydrous sodium sulfate, which comprises:
- conveying a bed of said solid crystalline sodium sesquisulfate on a horizontal vacuum filter belt, and
- spraying water at a temperature of about 40.degree. to about 100.degree. C. onto said bed at a plurality of longitudinally-adjacent locations along the length of said conveyor to leach said sodium sesquisulfate in solid crystalline form in a plurality of individual leaching steps with said sprayed water, to effect conversion of at least a substantial proportion of said solid crystalline sodium sesquisulfate to neutral anhydrous sodium sulfate at least partially in crystalline form and to form an aqueous acid containing medium having a total acid normality of up to about 6.5 normal, and
- drawing said aqueous acid containing medium from said bed on the conveyor.
A process for the production of chlorine dioxide, which comprises:
- reducing chlorate ion in an aqueous acid medium having a total acid normality of from about 5 to about 11 normal and containing sulfuric acid to form chlorine dioxide in a reaction zone from said aqueous acid reaction medium,
- maintaining said aqueous acid reaction medium at its boiling point under a subatmospheric pressure applied to said reaction zone and precipitating a by-product acid sulfate in said reaction zone from said aqueous acid reaction medium,
- removing said precipitated by-product acid sulfate from said reaction zone,
- effecting a plurality of individual leaching steps on said solid crystalline sodium sesquisulfate by spraying water at a temperature of about 40.degree. to about 100.degree. C. onto a bed of said solid crystalline sodium sesquisulfate to effect conversion of at least a substantial proportion of said solid crystalline sodium sesquisulfate to neutral anhydrous sodium sulfate at least partially in crystalline form to form an aqueous acid containing medium having a total acid normality of up to about 6.5 normal, and
- drawing said aqueous acid containing medium from said bed and recycling said aqueous acid containing medium to said reaction zone.
2 more elements
Dependencies are inferred from the claim text.