Salt beds

Sodium is not found ia the free state ia nature because of its high chemical reactivity. It occurs naturally as a component of many complex minerals and of such simple ones as sodium chloride, sodium carbonate, sodium sulfate, sodium borate, and sodium nitrate. Soluble sodium salts are found ia seawater, mineral spriags, and salt lakes. Principal U.S. commercial deposits of sodium salts are the Great Salt Lake Seades Lake and the rock salt beds of the Gulf Coast, Virginia, New York, and Michigan (see Chemicals frombrine). Sodium-23 is the only naturally occurring isotope. The six artificial radioisotopes (qv) are Hsted ia Table 1 (see Sodium compounds). 

Salt acts as a completely mobile plastic below 7600 m of overburden and at temperatures above 200°C (2). Under lesser conditions, salt domes can grow by viscous flow. Salt stmctures originate in horizontal salt beds at depths of 4000—6000 m or more beneath the earth s surface. The resulting salt dome or diapir is typically composed of relatively pure sodium chloride in a vertically elongated, roughly cylindrical, or inverted teardrop-shaped mass. 

A third source of brine is found underground. Underground brines ate primarily the result of ancient terminal lakes that have dried up and left brine entrained in their salt beds. These deposits may be completely underground or start at the surface. Some of these beds ate hundreds of meters thick. The salt bed at the Salat de Atacama in Chile is over 300 m thick. Its bed is impregnated with brine that is being pumped to solar ponds and serves as feedstock to produce lithium chloride, potassium chloride, and magnesium chloride. Seades Lake in California is a similar ancient terminal lake. Brine from its deposit is processed to recover soda ash, borax, sodium sulfate, potassium chloride, and potassium sulfate. 

Lithium brines with commercial potential are found in the Altiplano of BoHvia and Argentina, in salt beds of Chile, and in several salt beds in central and western China. 

Sail-related (raps—formed when the plastic salt formations deform into domelike structures under the overburden forces of the beds above the salt beds. Such plastic flowing (and bulging) of the salt beds deforms the rock formations above producing anticline structures and faults in the rock formation astride the domelike structures (see Figures 2-49 and 2-50). 

The liquid phase of saturated saltwater muds is saturated with sodium chloride. Saturated saltwater muds are most frequently used as workover fluids or for drilling salt formations. These muds prevent solution cavities in the salt formations, making it unnecessary to set casing above the salt beds. If the salt formation is too close to the surface, a saturated saltwater mud may be mixed in the surface system as the spud mud. If the salt bed is deep, freshwater mud is converted to a saturated salt water mud. 

The formation may be reactive and swell. It may be unconsolidated and collapse on the tool joints or drill collars. We may have mobile formations such as gumbo shales or salt beds in a plastic condition. 

Magnesium. Mg, at wt 24.312, at no 12, valence 2. Isotopes 24 (77.4%), 25 (11.5%) 26 (11.1%). Physical properties of 99.9% pure Mg are (riven in the fnllnwino tsKle fRef 10 n 6791 Mg is very abundant in nature, occurring in substantial amounts in many rock-forming minerals such as dolomite, magnesite, olivine, and serpentine. In addition, it is also found in sea water, subterranean brines, and salt beds. 

This series of prohibitions restricts how wastes subject to LDR requirements are handled. The most visible aspect of the LDR program is the disposal prohibition, which includes treatment standards, variances, alternative treatment standards (ATSs), and notification requirements. Land disposal means placement in or on the land, except in a corrective action unit, and includes, but is not limited to, placement in a landfill, surface impoundment, waste pile, injection well, land treatment facility, salt dome formation, salt bed formation, underground mine or cave, or placement in a concrete vault, or bunker intended for disposal purposes. The other two components work in tandem with the disposal prohibition to guide the regulated community in proper hazardous waste management. The dilution prohibition ensures that wastes are properly treated, and the storage prohibition ensures that waste will not be stored indefinitely to avoid treatment. 

Sodium chloride is found in salt beds, salt brines, and sea water throughout the world, and it is also mined is some locations. Consequently, sodium chloride is the source of numerous other sodium compounds. A large portion of the sodium chloride utilized is consumed in the production of sodium hydroxide (Eq. (11.23)). The production of sodium metal involves the electrolysis of the molten chloride, usually in the form of a eutectic mixture with calcium chloride. Sodium carbonate is an important material that is used in many ways such as making glass. It was formerly produced from NaCl by means of the Solvay process, in which the overall reaction is... 

Frantz, J.F., The evaporation of brine solutions in a fluidized salt bed, PhD thesis, Louisiana State University, 1958. 

Similar elements also occur in the same natural environment. For instance, the halogens are markedly concentrated in seawater. (The major salt in ocean brines is sodium chloride.) The other halogens are extracted from seawater that has been further concentrated—bromine from salt beds formed by evaporation and iodine from kelp, which grows in oceans. 

Bromine is obtained from natural brines, salt beds and seawater. The bromide salts extracted from these sources are oxidized by chlorine to yield bromine ... 

In about 1865 Professor B. F. Mudge, first president of the Kansas Academy of Science, gave a geological description of tire salt beds of Kansas in the Republican, Solomon, and Saline valleys. This enormous deposit extends from northern Kansas into Oklahoma and Texas (41). 

The composition of the Stassfurt salt beds.—The deposits about Stassfurt may very roughly be grouped in a series of strata indicated in Fig. I.13 Starting from a basal layer of anhydrite and gypsum there are ... 

Rock salt bed.-—-An immense basal bed of alteres Steinsalz—older rock salt—broken up at fairly regular intervals with two- to five-inch bands of anhydrite, CaS04. 

This project placed encapsulated spent fuel elements from an experimental AEG reactor into storage holes drilled into the floor of the mine located in a salt bed. Valuable experimental information was obtained about the interaction between the waste form and the salt in which the waste was emplaced. It was in fact this experiment, conducted in 1968, which revealed that inclusions of moisture, or brine, in the salt beds have a tendency to migrate up a thermal gradient towards a heat source placed in the salt. Quantities of brine were measured as migrating to the deposited waste canisters and the interaction of this brine with the canis-tered material was observed. 

Local dissolution features are recognized in the Delaware Basin. These may be of either shallow or deep origin, and it is the latter which may pose the greater potential hazard to the repository. These features, often called collapse chimneys or breccia pipes, form when localized dissolution occurs deep in the evaporite section, possibly at the base of the salt beds, resulting in a cavern into which overlying beds... 

Dissolution may also occur through man-made boreholes if these holes penetrate through the salt and establish water circulation by connecting water-bearing rocks above and below the salt beds. To mitigate against this concern, a conservative buffer of one mile between the repository and any such holes has been required. When an adequate borehole plug has been demonstrated, it may be possible to relax this restriction. 

The size distribution of the radioactive debris containing the majority of the fission products may bear little relationship to the size distribution of the environmental soil. Vaporization, agglomeration, condensation, and coagulation will probably lead to particles smaller than and larger than those found in the soil. A striking demonstration of this is found in the size distribution of radioactive debris of a low yield explosion over an alluvial salt bed in Nevada (6). While the mean diameter of the pre-shot soil particles was about 6/, the prompt fallout contained many intensely radioactive particles of 1000/ or greater. 

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