Sodium nitrate deposits

Another consequence of these films of grease is the prevention of oriented overgrowths .4 It is often found that if a crystal with a clean, freshly cleaved surface, is moistened with a solution of an isomorphous, soluble salt, which is then allowed to evaporate, the crystals deposited from the soluble salt are oriented with their edges parallel to those of the original crystal. Such overgrowths are well shown by sodium nitrate deposited on calcite. They are only obtained in perfection, however, if the surface of the first crystal is free from contamination the power of orienting deposited isomorphous crystals is much diminished if the freshly cleaved surface is left in the air. 

Sodium nitrate deposits are less widespread than the other major types of chemical crust or sediment that are found in different parts of the world. Indeed, the only deposits of any great spatial extent and thickness are those of portions of the hyper-arid Atacama Desert in South America. These materials are, in the words of Ericksen (1983, p. 366), so extraordinary that, were it not for their existence, geologists could easily conclude that such deposits could not form in nature . Ericksen notes a series of features of the deposits that defy rational explanation. These include their restricted distribution in a very salty area, their occurrence in a wide variety of topographic settings, the abundance of nitrate minerals, and the presence of a series of other minerals, such as perchlorate, that do not occur in any other saline complexes and the origin of which is obscure. 

Figure 12.1 The distribution of sodium nitrate deposits in northern Chile.

Between 1982 and 1986, the world iodine production remained fairly stable and amounted to approximately 12 500 tons per year. Japan accounted for 57% of the world s production, followed by Chile (23%) and the former Soviet Union (15%). In Japan, iodine is produced entirely as a byproduct of natural gas production. Chile has large reserves of iodine associated with sodium nitrate deposits (Lyday 2002). 

These elemental states do not occur naturally. Fluorine, chlorine and bromine are found almost exclusively as solutions or minerals containing halide ions, X". Furthermore, most iodine is obtained from iodide solutions, but some occurs as iodates (e.g. NaI03) in, for example, the famous sodium nitrate deposits in the Atacama desert near the west coast of South America. In industry, the halogens are obtained primarily from halide ions. 

Potassium Nitrate. Potassium nitrate, known but Httle used as a fertilizer for many years, may be reclaimed as a by-product of the production of sodium nitrate from natural deposits of caflche in Chile. KNO also has been produced by the double decomposition reaction between sodium nitrate and potassium chloride ... 

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). 

Sodium nitrate nitrate [7631-99-4] NaNO, is found in naturally occurring deposits associated with sodium chloride, sodium sulfate, potassium chloride, potassium nitrate, magnesium chloride, and other salts. Accumulations of sodium nitrate have been reported in several countries, but the only ones being commercially exploited are the unique nitrate-rich deposits in Chile, South America. Natural sodium nitrate is also referred to as Chilean saltpeter or Chilean nitrate. 

The Chilean nitrate deposits are located in the north of Chile, in a plateau between the coastal range and the Andes mountains, in the Atacama desert. These deposits are scattered across an area extending some 700 km in length, and ranging in width from a few kilometers to about 50 km. Most deposits are in areas of low rehef, about 1200 m above sea level. The nitrate ore, caUche, is a conglomerate of insoluble and barren material such as breccia, sands, and clays (qv), firmly cemented by soluble oxidized salts that are predominandy sulfates, nitrates, and chlorides of sodium, potassium, and magnesium. Cahche also contains significant quantities of borates, chromates, chlorates, perchlorates, and iodates. 

The nitrate deposits are made up of several layers (Fig. 1). The ore bodies are very heterogeneous and variable in size, thickness, composition, and hardness. The overburden may include chuca a layer of unconsoHdated sand, silt, and clay, andpanqueque a layer of semiconsoHdated and porous material poody cemented by salts over poody cemented gravel. The ore composition has degraded considerably since the eady days of the industry, when it was reported that ores of up to 50% sodium nitrate were mined. There are stiU reserves that can be commercially mined well into the twenty-first century (1). 

As of 1996 world production of sodium nitrate was about 520,000 metric tons annually. Of this quantity, some 450,000 t (86%) are produced in Chile from natural deposits by SQM Nitratos and distributed worldwide by several affOiates, eg, Chilean Nitrate Corporation in the United States and Nitrate Sales International in Belgium. The remainder, ca 70,000 t, is manufactured mainly in Europe, Japan, and Russia, generally as a by-product of nitric acid production. Additionally, China is known to manufacture some unknown but significant volumes of sodium nitrate for domestic use. 

The main metals in brines throughout the world are sodium, magnesium, calcium, and potassium. Other metals, such as lithium and boron, are found in lesser amounts. The main nonmetals ate chloride, sulfate, and carbonate, with nitrate occurring in a few isolated areas. A significant fraction of sodium nitrate and potassium nitrate comes from these isolated deposits. Other nonmetals produced from brine ate bromine and iodine. 

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... 

Ores of nitrogen are relatively rare. The best mineral is sodium nitrate, NaNOj, found in large deposits in Chile. We now prepare the nitrogen compounds we desire from the nitrogen of the... 

Sodium naphthalene, 74 247 Sodium naphthalene complex, 22 764 Sodium niobate, 77 153 Sodium nitrate, 22 843-853, 860-862 applications of, 22 843, 852-853 commercial grades of, 22 850t crystallization of, 22 848 deposits of, 22 843-845 described, 22 843 economic aspects of, 22 849... 

Before World War I, tbe main source of nitrates for human use was from large deposits of bird droppings in Peru and sodium nitrate from Chile. These sources were becoming scarce and expensive. Then Fritz Haber (1868-1934), a lecturer in a technical college in Germany, began to experiment with ways to manufacture ammonia. Haber knew that ammonia could he easily converted to nitrates and other useful nitrogen... 

Soda niter or sodium nitrate (NaNO ) is the most abundant of the nitrate minerals. It is used for fertilizer, explosives, and preservatives. The natural deposits are located in northern Chile, which was the original source for many years. More recently, nitrogen fixation, which extracts nitrogen from air, has been used for producing sodium nitrate. This synthetic process has greatly increased the availability of this useful sodium salt by ehminating the need for the natural source. It is used to preserve and cure meats and is used in photography, in pharmaceuticals, and as a color fixative in fabrics. 

There are several natural deposits of sodium nitrate in various parts of the world, including Chile, Mexico, Egypt, and the United States. The most important application of sodium nitrate is its use as a fertilizer in agriculture. It is an effective fertilizer for cotton, tobacco, and vegetable crops. Its agricultural applications, however, have dwindled considerably in recent years because of the growth of ammonium nitrate and other fertilizers. 

Costra is a kind of low-grade nitre rock or caliche running 5 to 17 per cent, sodium nitrate which does not pay to work the caliche runs 18 to 25 per cent., and in exceptional cases 50 to 60 per cent, sodium nitrate—the average runs 20 to 30 per cent. The deposits are close to the surface, and naturally vary a little in composition in different places. R. F. Blake and V. I OliVier s, and L. Dieulafait s analyses 5 of costra and caliche show ... 

---