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US 6,503,474 B1Granted
Process for the preparation of anhydrous sodium sulfide
AssigneeDegussa AG
InventorsRobert Magiera, Hans Christian Alt, Gerhard Rasig, Jörg Münzenberg, Christoph Batz-Sohn, Ralf Goedecke, Ulrich Deschler, Volker Knapp, Karl-Heinz Rützel
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Abstract
A process is disclosed for the preparation of anhydrous sodium sulfide by heating sodium sulfide having a water content of from 38 to 40% in a contact drier in vacuo, the temperature of the solid to be dried being increased from approximately 20° C. at the solid inlet to ≧180° C. at the solid outlet.
Claims25
A process for the preparation of anhydrous sodium sulfide comprising:
- heating water-containing sodium sulfide having a water content of from 35 to 45% by conveying said sodium sulfide with mixing, through a drier apparatus in which the temperature of the sodium sulfide rises continuously from approximately 20° C. at the point at which the sodium sulfide is fed in to said drier up to ≧180° C. at the point of the outlet, at a low pressure of <20 torr maintained in the process, wherein a drying cycle of any given part of the sodium sulfide is completed within a time interval of less than about 4 hours, and wherein the mass flow of the sodium sulfide in said process is more than about 25 kg/h.
A process for the preparation of anhydrous sodium sulfide comprising:
- heating water-containing sodium sulfide having a water content of from 35 to 45% by conveying said sodium sulfide with mixing, in contact with a heated surface and transferring heat to said sodium sulfide in contact with said surface so as to raise the temperature of said sodium sulfide continuously from approximately 20° C. at the point at which the sodium sulfide contacts the heated surface up to ≧180° C., at a low pressure of <20 torr, which is maintained during the heating wherein a drying cycle of any given part of the sodium sulfide is completed within a time interval of from 10 minutes to less than 4 hours, and wherein the mass flow rate of the sodium sulfide in contact with the heated service is within the range of 25 kg/h to 100,000 kg/h.
Dependencies are inferred from the claim text.