Salt from domes

Clear Fork, Texas, salt from salt dome 1 2... 

Solution mining is more effective with salt domes than with stratified deposits, and Fig. 7.21 is drawn for a domal deposit. It is the favored process for extraction of NaCl from domes, and it is also widely used with deep-lying strata, where the cost of... 

Figure 7.26 gives an example of the effectiveness of SSI-2(X) when dissolving rock salt from a Texas dome. The addition of 15 ppm reduces the sulfate concentration of the solution formed by about 80%. Figure 7.27 gives a second example, at the standard inhibitor concentration of 12 ppm. This shows the general effectiveness of the product... 

Sulfur is commercially recovered from wells sunk into the salt domes along the Gulf Goast of the U.S. Using the Frasch process heated water is forced into the wells to melt the sulfur, which is then brought to the surface. 

Salt-Dome Sulfur Deposits. The sulfur deposits associated with salt domes in the Gulf Coast regions of the southern United States and Mexico have historically been the primary sources of U.S. sulfur. These remain an important segment of both U.S. and world sulfur supply. Although the reserves are finite, many are large and voluntary productive capacity ensures the importance of these sources for some time to come. In 1994, the output from the salt domes in the U.S. was about 2.09 million metric tons (21). 

Solution mining produced nearly 23 million metric tons of salt in 1989 representing more than half of the total U.S. salt production (14). Salt brine is made from bedded salt at more than 18 different locations and from 17 salt domes (15). Bedded salt of the salina formation is the most widely and intensively exploited by solution mining. Enormous reserves of salina salt are available. Cost of solution mining salt is usually less than the cost of salt produced by dry mining. The method is particularly good where salt deposits are deep and dry mining would not be feasible. 

The ingenious process of melting suhlerranean sulfur with superheated water and forcing it to the surface with compressed air was devised and perfected by Herman Frasch in the period 1891-4. Oiiginally designed to overcome the problems of recovering sulfur from the caprock of salt domes far below the swamps and quicksands of Louisiana, the method is now also extensively used elsewhere To extract native sulfiu. ... 

Numerous technical and human failures allowed gas to release from a salt dome storage facility. Lack of fail safe devices contributed to the explosion of the resulting vapor cloud. 

The economics of PRO systems using brines and fresh water sources and current membranes are more favorable, with estimated power outputs as high as 200 watt/m. However, surface brines exist in deserts where there is limited fresh water, and brines that might be produced from salt domes pose a difficult effluent disposal problem. If PRO systems can be produced at an installed cost of 100/m2 of membrane, the projected economics are competitive with other power-generating techniques. This appears to be the only salinity gradient resource worthy of further study. 

The Carboniferous sediments of the Maritimes Basin were originally deposited as red-green interstratified continental to marginal siliciclastics, marine limestone, dolostone, gypsum, anhydrite, halite, and locally, potash. The salt deposits vary from stratified, with only minor structural complications, to those that have been tectonized into pillows, anticlines e.g., Penobsquis Deposit) and diapirs or domes. In the latter cases, structural complexities make the stratigraphic position of many of these deposits uncertain. 

Elemental sulfur is recovered from its ore deposits found throughout the world. It is obtained commercially by the Frasch process, recovery from wells sunk into salt domes. Heated water under pressure is forced into the underground deposits to melt sulfur. Liquid sulfur is then brought to the surface. Sulfur is recovered by distillation. Often the ore is concentrated by froth flotation. 

Salt caverns are developed by solution mining, a process (leaching) in which water is injected to dissolve the salt. Approximately 7 to 10 units of fresh water are required to leach 1 unit of cavern volume. Figure 10-190 illustrates the leaching process for two caverns. Modern salt dome caverns are shaped as relatively tall, slender cylinders. The leaching process produces nearly saturated brine from the cavern. Brine may be disposed into nearby disposal wells or offshore disposal fields, or it may be supplied to nearby plants as a feedstock for manufacturing of caustic (NaOH) and chlorine (CI2). The final portion of the produced brine is retained and stored in artificial surface ponds or tanks to be used to displace the stored liquid from the cavern. 

Sulfur is a very important industrial chemical. Current consumption ranks sulfur with the top five inorganic and organic chemicals produced in the U.S. The U.S. is the largest producer and consumer of sulfur in the world. The U.S. position in sulfur production resulted from the development of the Frasch process toward the end of the 19th century for mining the large sulfur deposits associated with salt domes in Texas and Louisiana. 

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