METHOD FOR PRODUCING GYPSUM FROM SMELTING WASTE GAS

• Main Author: KUROKAWA HARUMASA
• Format: Patent
• Language: English
• Published: 12.06.2001
• Edition: 7
• Subjects: CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM,CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THERARE-EARTH METALS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; INORGANIC CHEMISTRY; METALLURGY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TRANSPORTING

PROBLEM TO BE SOLVED: To provide a method by which the regulation of sulfur trioxide concentration in a smelting waste gas is facilitated and the production of a gypsum in a process for treating a waste acid can optionally be regulated. SOLUTION: A diluting gas at >=250 deg.C and >=15 vol.% oxygen concentration, e.g. an off-gas from a furnace scarcely accompanying a smelting reaction such as a slag smelting furnace or a refining furnace is used in an inlet of a waste heat boiler in the method for producing the gypsum from the smelting off-gas comprising treating a waste gas from the nonferrous metal smelting furnace at >=10 vol.% sulfurous acid gas concentration with the waste heat boiler, removing dust with a cyclone or a dry type electric dust collector, then washing the waste gas, bringing the resultant wash liquid into contact with a calcium source and providing the gypsum.