Dead Sea salts

When the results of the yellow limestone clay and the red field clay analyses were processed by the potstat routine (10), an average of data from the two clays yielded a pattern that matched (except for sodium) the analytical pattern of pottery made of a mix of the two clays. In the first case, the two raw clays were simply ground and analyzed separately in the second case, the two clays were mixed in a water bath, sand and Dead Sea salt were added, a vessel was formed, dried, and fired, and this finished product was analyzed. The sand temper did not contribute significantly to the relative test element concentrations, but the salt addition did, of course, raise the sodium concentration. These results are graphed in Figure 2. 

Proksch, E. Nissen, H-P. Bremgartner, M. Urquhart, C., Bathing in a magnesium-rich Dead Sea salt solution improves skin barrier function, enhances skin hydration, and reduces inflammation in atopic dry skin. Int. J. Dermatol. 44, 151-157, 2005. 

Sodium chloride occurs naturally as the mineral halite, commonly called rock salt, in large underground deposits on every continent. Seawater contains about 3.5 percent dissolved minerals, of which 2.8 percent is sodium chloride and the other 0.7 percent is primarily calcium, magnesium, and sulfate ions. Natural brines, or salty waters other than seawater, are foxmd in wells and lakes, such as the Great Salt Lake of Utah and the Dead Sea. Salt is also found in surface deposits in regions subject to arid climates. 

Both damp evaporated salts and water from the Dead Sea produce a quantity of precipitate. Reconstituted Dead Sea salt water is far more concentrated, produces a much greater amount of precipitate and requires much more lye (dilute NaOH) to bring it up to the desired pH level. 

Bromides of sodium, potassium, magnesium and calcium occur in sea water (about 0.07 % bromine) but the Dead Sea contains much more (5% bromine). Salt deposits (e.g. at Stassfurt) also contain these bromides. Silver bromide, AgBr, is found in South America. 

Soluble Salt Flotation. KCl separation from NaCl and media containing other soluble salts such as MgCl (eg, The Dead Sea works in Israel and Jordan) or insoluble materials such as clays is accompHshed by the flotation of crystals using amines as coUectors. The mechanism of adsorption of amines on soluble salts such as KCl has been shown to be due to the matching of coUector ion size and lattice vacancies (in KCl flotation) as well as surface charges carried by the soflds floated (22). Although cation-type coUectors (eg, amines) are commonly used, the utUity of sulfonates and carboxylates has also been demonstrated in laboratory experiments. 

Occurrence. Magnesium bromide [7789-48-2] MgBr2, is found in seawater, some mineral springs, natural brines, inland seas and lakes such as the Dead Sea and the Great Salt Lake, and salt deposits such as the Stassfurt deposits. In seawater, it is the primary source of bromine (qv). By the action of chlorine gas upon seawater or seawater bitterns, bromine is formed (see Chemicals frombrine). 

Total solar salt, NaCl, produced in the world is 90 million tons. Well over that amount of salt is produced in preconcentration ponds as an intermediate step in the production of other chemicals such as potassium chloride. For example, the Dead Sea faciUties produce 40 million tons of salt each year but sell none because of the high cost of transportation to markets. 

Economic Aspects and Uses. Total world production of potassium products is 29,000,000 tons per year (65). Potassium chloride is removed from brine at Moab, and Wendover, Utah, and at Seades Lake, California. Potassium sulfate is made from Great Salt Lake brine by Great Salt Lake Minerals Corp., which is the largest producer of solar potassium sulfate in the wodd. Combined, these U.S. faciUties stiU produce a relatively small percentage of potash fertilizers in the wodd. Production from the Dead Sea, for example, is 10 times greater than production of potassium from brines in the United States. More than 95% of all the potassium produced is used in fertilizer blends. The remainder is converted to other potassium chemicals for industdal use (see Potassium compounds). 

Sodium, 22 700 ppm (2.27%) is the seventh most abundant element in crustal rocks and the fifth most abundant metal, after Al, Fe, Ca and Mg. Potassium (18 400 ppm) is the next most abundant element after sodium. Vast deposits of both Na and K salts occur in relatively pure form on all continents as a result of evaporation of ancient seas, and this process still continues today in the Great Salt Lake (Utah), the Dead Sea and elsewhere. Sodium occurs as rock-salt (NaCl) and as the carbonate (trona), nitrate (saltpetre), sulfate (mirabilite), borate (borax, kemite), etc. Potassium occurs principally as the simple chloride (sylvite), as the double chloride KCl.MgCl2.6H2O (camallite) and the anhydrous sulfate K2Mg2(S04)3 (langbeinite). There are also unlimited supplies of NaCl in natural brines and oceanic waters ( 30kgm ). Thus, it has been calculated that rock-salt equivalent to the NaCl in the oceans of the world would occupy... 

Chlorine is the twentieth most abundant element in crustal rocks where it occurs to the extent of 126 ppm (cf. nineteenth V, 136 ppm, and twenty-first Cr, 122 ppm). The vast evaporite deposits of NaCl and other chloride minerals have already been described (pp. 69, 73). Dwarfing these, however, are the inconceivably vast reserves in ocean waters (p. 69) where more than half the total average salinity of 3.4 wt% is due to chloride ions (1.9 wt%). Smaller quantities, though at higher concentrations, occur in certain inland seas and in subterranean brine wells, e.g. the Great Salt Lake, Utah (23% NaCl) and the Dead Sea, Israel (8.0% NaCl, 13.0% MgCU, 3.5% CaCU). 

Local conditions may modify this profoundly in special areas. In the Arctic and Antarctic, and where there is dilution by large rivers, the salinity may be considerably less, and it may vary greatly according to season. Salinity is well below normal in the Baltic, and may fall nearly to zero at the head of the Gulf of Bothnia. In enclosed seas like the Mediterranean, Black Sea and Red Sea, on the other hand, where there is rapid evaporation, salinity may reach 40 parts per thousand. The total salt content of the inland Dead Sea is 260 g/kg compared to 37 g/kg for the Atlantic Ocean. 

The evaporation of water from a saturated solution leaves a solution in which the ion concentrations exceed the solubility limit. To return to equilibrium, the salt must precipitate from the solution. Evaporation is used to mine sodium chloride and other salts from the highly salty waters of inland seas such as Great Salt Lake in Utah and Israel s Dead Sea. 

It depends on local hydrographic conditions whether a playa is wet around the year or dries out. A playa may stay (almost) permanently wet if it is part of a closed basin that is under the influence of groundwater. Some playas such as the Dead Sea are fed by perennial rivers and will not dry out either but their water is so salty that salts precipitate. Laminated evaporates of considerable thickness can form in this way, with lamination reflecting the periodicity of the seasons. 

There are many natural sources of chlorine compounds, which is not surprising considering that it is the 20th most abundant element. Salt and salt water are widely available the Great Salt Lake contains 23% salt, and the Dead Sea contains about 30%. Because salt is so abundant, most minerals that contain chlorine are not important sources for economic reasons. Bromine is found in some salt brines and in the sea, as are some iodine compounds. 

Balneotherapy (and climatotherapy) involves bathing in waters containing certain salts, often combined with natural sun exposure. The salts in certain waters (e.g., the Dead Sea) reduce activated T cells in skin and may be remittive for psoriasis. 

Herodotus (484-425 B.C.) mentioned the occurrence of many lumps of bitumen in the River Is, a small tributary of the Euphrates (10). The Babylonians heated this bitumen and used it instead of mortar for cementing together the bricks of their walls and buildings (11). Herodotus also spoke of a well near Susa (the Shushan of the Bible) which yielded bitumen, salt, and oil (11). Cornelius Tacitus, a friend of Pliny the Younger, described the bitumen of the Dead Sea (12). R. J. Forbes states in his book Bitumen and Petroleum in Antiquity that the ancients used tar and pitch for waterproofing pottery, for caulking ships, and for making torches, paint for roofs and walls, and lampblack for paints and ink (13). 

In this case, BrO should be generated, and indeed, it has been observed by DOAS under these conditions at concentrations up to 30 ppt (Tuckermann et al., 1997). Figure 11.16 shows a DOAS spectrum taken at polar sunrise at Alert in April 1992 and a reference spectrum of BrO (instrument features are included in this) clearly, BrO is present, in this case at a concentration of 17 ppt (Platt and Hausmann, 1994). BrO has also been detected at the Dead Sea, Israel, and attributed to heterogeneous reactions of the sea salt. CIO has also been detected at concentrations up to 40 ppt under these conditions using DOAS (Tuckermann et al., 1997), and IO in a midlatitude coastal marine... 

The TDS of lake waters can be high because of evaporation, as in the Great Salt Lake of Utah or the Dead Sea (Israel/Jordan). Well waters often contain high concentrations of electrolytes leached from the rocks—notably iron salts, which are a major nuisance—and the highly saline waters associated with oil- or gas-bearing formations are frequently better described as brines. 

Salt is very widely diffused in the waters of the globe. Most rivers carry traces, and when they discharge into land-locked basins, and when the waters are cone, by evaporation, salt-lakes are formed. The waters of the Baltic Sea contain between 02 and 08 per cent, of saline matters, whereas the waters of the Dead Sea contain up to 25 per cent. It has been estimated that next to water, salt is one of the most abundant mineral substances on the crust of the earth. The composition of the solids held in soln. in the waters of a number of oceans and seas is indicated in Table XIV. 

In summary, we can conclude that at moderate salt concentrations typical for seawater ( 0.5 M), salinity will affect aqueous solubility (or the aqueous activity coefficient) by a factor of between less than 1.5 (small and/or polar compounds) and about 3 (large, nonpolar compounds, n-alkanals). Hence, in marine environments for many compounds, salting-out will not be a major factor in determining their partitioning behavior. Note, however, that in environments exhibiting much higher salt concentrations [e.g., in the Dead Sea (5 M) or in subsurface brines near oil fields], because of the exponential relationship (Eq. 5-28), salting-out will be substantial (see also Illustrative Example 5.4). 

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