PROCESS FOR CONVERTING SO{sub}2 TO SULFUR WITHOUT GENERATING POLLUTANTS THROUGH REACTIONS INVOLVING BaS AND BaSO{sub}4

摘要

Nonferrous smelters and coal gasification processes generate sulfur dioxide streams, most of which are treated to produce sulfuric acid with the accompanying problems of market shortage and transportation difficulties. While the conversion of sulfur dioxide to elemental sulfur has many environmental advantages, no processes exist that are environmentally acceptable and economically viable. A method for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium or barium sulfide and calcium or barium sulfate without generating solid wastes has been developed. In this process, the sulfate, as the starting raw material, is reduced by a suitable reducing agent such as hydrogen to produce the sulfide, which is used to reduce sulfur dioxide producing elemental sulfur vapor and regenerating the sulfate. The latter is then reduced to reproduce the sulfide. This paper describes work on the BaS/BaSO{sub}4 system. Thermodynamic analysis and experimental results indicated that the BaS-SO{sub}2 reaction produces mainly sulfur vapor and solid barium sulfate and that the gaseous product from the BaSO{sub}4-H{sub}2 reaction is mainly water vapor. The rates of the two reactions are reasonably rapid in the temperature range 700-1050°C.