A continuous process is provided that has the primary purpose of removing nh3, h2s, hcn, and (cn)2 from the subject gas mixtures and the secondary purpose of producing (nh4)2so4 and iron oxide for industrial uses. The gas mixture, which contains tar and other condensible vapors, nh3, h2s, hcn, and (cn)2 together with small volumes of gas from the ammonia still of the system, and gas from a system h2so4 plant, is contacted in a single three-stage reaction chamber in the presence, if need be, of a tar solvent, additional nh3, and the reagent fe(oh)2, which itself is a product of a concurrent reaction between nh3 and feso4. The unpurified gas mixture's condensible vapors are largely prevented from condensing by maintaining a steady, elevated temperature, while the mixture is essentially freed of hcn, (cn)2, nh3, and h2s in the reactor before the gas mixture passes through a primary gas cooler. The gas then passes through a benzene, toluene, and xylene absorber before being pressurized and distributed. The spent reaction chamber reagent is separated to produce tar and solvent; (nh4)2so4 solution; and iron precipitates. Sulfur dioxide released by the iron oxide production process is used to produce h2so4, which in turn is either reacted with scrap iron, or used in a metal pickling operation to produce feso4 for use in preparation of the reaction chamber reagent.
U.S. Pat. 3,993,730, Nov. 23, 1976; Chem. Abstr. Not Found