Method for preparing elemental sulfur as a diffusion-resistant gas and methods for its use in making lime, sulfur dioxide and sulfuric acid from waste gypsum

Publication type: Grant

Application number: US 06/572,301

Publication date: May 28, 1985

Filing date: Jan 20, 1984

The present invention relates to the discovery of a method by which elemental sulfur may be delivered to a reaction zone, for gas-solids reaction, in the form of a concentrated, coherent, diffusion-resistant gas thereby permitting gas-solid reactions of greatly enhanced reaction rates. It has been found that sulfur, which is first vaporized at approximately 1 atmosphere pressure, and then super heated to at least 1270° F. while in transit through a confined space, such as a transfer line, will debouch from said confined space into a reaction zone as a coherent gas which resist diffusion throughout the free space of the reaction zone. This coherent form of sulfur gas exhibits a dark reddish-violet color. The coherent form of sulfur gas, since it resists diffusion throughout the free space of the reaction zone, flows into concentrated contact with, and remains concentrated at, the solids surface, thereby producing a gas-solids reaction of greatly enhanced reaction rate.

Utilizing the above discovery a process has been devised by which the sulfur values present in gypsum, particularly waste by-product gypsum produced by the wet process, may be recovered as SO2 with the concurrent production of lime.