Sulfur
Sulfur (S) is a pale yellow nonmetallic element with a low melting point and low specific gravity (~2.0). Sulfur is used in the manufacture of chemical fertilizer. Numerous industrial applications arise from conversion of sulfur to sulfuric acid.
A source of sulfur for early pioneers was the mineral pyrite (FeS2). Sulfur was important because of its use in black powder (gun powder). During the Civil War, a deposit of pyrite at Magnet Cove was investigated by the Confederacy as a source of sulfur. A pyrite deposit near Berryville in Carroll County was explored during 1937 and 1938 as a possible source of sulfur. The pyrite is in a highly fractured zone of the Cotter Formation (Ordovician). This deposit contains 482,000 long tons of ore ranging in grade from 6.5 to 32.4 percent sulfur, averaging 24.3 percent. A second major resource of sulfur is the gypsum deposits of Pike and Howard Counties in southwest Arkansas. Presently, processed sulfur from other sources is so inexpensive, the development of commercial sulfur from gypsum is not feasible.
The first experimental plants in the United States for the recovery of sulfur from natural gas were located in Columbia and Lafayette Counties in Arkansas. Analyses of oil field gases were first published in 1940 and helped bring attention to this resource. Pilot plants built in 1941 led to the construction of two full-scale production facilities, one in each county, in 1943. The Columbia County plant served the Dorcheat-Macedonia field for about 15 years and was dismantled and moved to Texas in 1958. In the Dorcheat-Macedonia area, the hydrogen sulfide content of natural gas was as high as 2,400 grains per 100 cubic feet. The Columbia County plant had a production capacity of 10 long tons per day of free sulfur. The plant in Lafayette County served the McKamie field. The gas from the McKamie field contained as much as 4,500 grains of hydrogen sulfide per 100 cubic feet of natural gas. This "sour" gas was purified to a hydrogen sulfide content of 0.05 grains per 100 cubic feet in the pilot-plant operation. The ensuing commercial plant was producing 65 tons of free sulfur daily by the end of 1943 and recovering 97 percent of the sulfur in the gas. In 1960, the McKamie facility had a production capacity of 110 long tons per day and is presently in operation.
The start of full-scale operations in the McKamie field marked the initial use of the Claus process for sulfur recovery in the United States, which was the first process for recovering sulfur from hydrogen sulfide. The Claus process involves burning one-third of the hydrogen sulfide to form sulfur dioxide, which then reacts with the unburned hydrogen sulfide in the presence of a surface-active catalyst to form sulfur and water vapor. The sulfur is condensed to liquid form and shipped or stored in that manner, or is allowed to solidify for handling as a solid.
Prior to the development of sulfur-extraction units, natural gas containing appreciable amounts of hydrogen sulfide was flared because of its corrosive nature and unpleasant odor. If used as a boiler fuel, gas may contain as much as 360 grains of hydrogen sulfide per 100 cubic feet and still not be too objectionable. However, natural gas used for domestic purposes is not permitted to contain more than 1.5 grains of hydrogen sulfide per 100 cubic feet.
Sulfur has been produced by one petroleum refinery in Union County for years. The source of the sulfur is gas freed at the refinery during the production of other petroleum products. Production capacity was rated at 10 long tons per day in 1960. In 1984, a company near Magnolia, Columbia County, began recovering sulfur during bromine extraction and continues today.
References
Blade, O. C., and Branner, G. C., 1940, Survey of crude oils of the producing fields of Arkansas: U. S. Bureau of Mines Report of Investigations 3486, 40 p.
Grandone, Peter, and McHarg, R. E., 1952, Oil, gas, and sulfur in the Arkansas and Red River basins, Arkansas: U. S. Inter-agency Committee on Arkansas-White-Red River Basins, Minerals and Geology Workgroup, Preliminary Report, 12 p.
Netzeband, F. F., Early, T. R., Ryan, J. P., and Miller, W. C., 1964, Sulfur resources and production in Texas, Louisiana, Missouri, Oklahoma, Arkansas, Kansas, and Mississippi, and markets for the sulfur: U. S. Bureau of Mines Information Circular 8222, 77 p.