Filter for industrial waste gas purifn. - from sulphur cpds. and hydrogen halides based on calcined limestone, borate and silicate

摘要

The compsn. for the removal of gaseous pollutants, esp. 5 oxides, H2S and H halides, from industrial waste gases consists of limestone calcineda at 400 degrees C, crushed to a particle size of 20-30 mu, mixed with H3BO3 or borates and liquid Na2SiO3 or K2SiO3, granulated to 0.4-2 mm granules and heated to 190-450 degrees C. 10-15% chrysotile asbestos, asbestos fibres or Mg silicate can be added (to improve the filtration effect and activity). The pref. compsns. are (A) 50 (wt.)% limestone, 10-15% asbestos, 7-12% H3BO3 or 3.5-6% borax and 30-40% Na2Sio3 (as water glass); or (B) 50-60% limestone, 15-20% borax and 25-35% Na2SiO3 (as water glass). Complex processes are avoided and the use of this compsn. as filter makes it possible to sorb H halides, H2S and mercaptans besides S oxides at waste gas temps. of up to 200 degrees C.