So2 and so3 atmospheric pollutants are removed from industrial waste gases by passing the latter over an absorption bed at approximately 300 deg.-600 Deg. C. The bed consists of red mud, retorted oil shale treated with naoh, or a mixture of retorted oil shale and red mud treated with naoh. Lower temperatures and less absorbent may be used by prior oxidation of the so2 to so3. The apparatus used for this process, as well as the absorbent origins, compositions, and preparations are described. The spent absorbent can be regenerated with a reducing gas such as h2 at 500 deg.-1,000 Deg. C, and the recovered h2s converted to useful s by commercial means. The efficiency of these absorbents in their original and regenerated states are demonstrated by numerous examples using simulated flue gas. This gas contains so2 0.316, H2o 6.700, Co2 13.000, O2 6.000, and n2 73.984 pct. Thus, red mud granules were contacted with the simulated flue gas at 130 deg., 330 Deg., 450 Deg., and 500 deg. C. At each temperature interval 90 pct so2 removal was achieved with loading capacities of 4.0, 4.0, 7.1, and 18.4 G so2/100 g absorbent, respectively.
U.S. Pat. 3,580,702; May 25, 1971; Chem Abstr. 75:52,527V