Production of gypsum hemihydrate with waste heat, aqueous H/sub 2/SO/sub 4/ and sulfuric acid salts

Patent · Tue Feb 21 04:00:00 EST 1984

OSTI ID:6917781

Quante, H

Alpha gypsum hemihydrate is obtained by calcining calcium sulfate dihydrate, generated with flue-gas desulfurization of power plants or by chemical process, e.g. in the production of phosphoric acid. The calcining process comprises producing initially a dispersion from calcium sulfate dihydrate and diluted, sulfuric acid solution and heating same at a predetermined rate to about 373 K with industrial dust-free waste heat, whereupon the solid components are separated from the aqueous sulfuric acid and are dried. An alpha gypsum hemihydrate practically free from anhydrite II is obtained from a solution of sulfuric salts in the diluted sulfuric acid. An addition of magnesium oxide yields a hemihydrate with a high degree of fineness and avoids blooming effects.

• Assignee: EDB-84-139876
• Patent Number(s): US 4432954
• OSTI ID: 6917781
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
200105 -- Fossil-Fueled Power Plants-- Heat Utilization
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400105* -- Separation Procedures
ALKALINE EARTH METAL COMPOUNDS
CALCINATION
CALCIUM COMPOUNDS
CALCIUM SULFATES
CHALCOGENIDES
CHEMICAL PLANTS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CONTROL
DECOMPOSITION
DESULFURIZATION
ENERGY
FLUE GAS
GASEOUS WASTES
GYPSUM
HEAT
HEAT TREATMENTS
HYDRATES
HYDROGEN COMPOUNDS
INDUSTRIAL PLANTS
INORGANIC ACIDS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MEDIUM TEMPERATURE
MINERALS
OXIDES
OXYGEN COMPOUNDS
POWER PLANTS
PRODUCTION
PYROLYSIS
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
SULFURIC ACID
TEMPERATURE CONTROL
THERMOCHEMICAL PROCESSES
WASTE HEAT
WASTE HEAT UTILIZATION
WASTE PRODUCT UTILIZATION
WASTES
YIELDS