Nitrate caliche

Diluted iodate solution is obtained by hydrothermal vat leaching of caliche ore during nitrate recovery. Concentrated iodide solutions are obtained by heap leaching of old waste dumps (tailings) and low grade nitrate caliche, such as blasted overburden, left over by former nitrate producers. 

Anon. Patents of Invenrions Referring to the Extraction of Nitrate. Caliche i, 25, 64 (1919). 

Gr. iodes, violet) Discovered by Courtois in 1811, Iodine, a halogen, occurs sparingly in the form of iodides in sea water from which it is assimilated by seaweeds, in Chilean saltpeter and nitrate-bearing earth, known as caliche in brines from old sea deposits, and in brackish waters from oil and salt wells. 

Sodium Nitrate (Chile Saltpeter, Cubic or Soda Niter, Caliche, Nitratine). NaN03, mw 85.01,... 

Na nitrate occurs native in large deposits in the rainless districts of Chile, hence it is often called Chile saltpeter or Chile niter . The Na nitrate in the deposits constitutes from 20 to 50% in a distinct stratum of earth known as caliche . The caliche is crushed and lixiviated in large tanks of w heated by steam. The settled soln is run off to crystallizers, where crude nitrate separates, the mother liquors being run back to the lixiviators. The crysts are washed with a little w and dried in the sun they contain 95—96% Na nitrate (Ref 1)... 

Guggenheim A process for extracting sodium nitrate from caliche, a native sodium nitrate found in Chile. The ore is leached at 40°C with water containing controlled concentrations of magnesium and calcium sulfates. Operated on a large scale in Chile. See also Shanks. 

Shanks An obsolete process for extracting sodium nitrate from caliche, a Chilean mineral. The ore was leached with sodium chloride solution at 70°C and the sodium chloride and nitrate were separated by fractional crystallization. See also Guggenheim. 

Urbansky ET, Brown SK, Magnuson ML, Kelty SK (2001) Perchlorate levels in samples of sodium nitrate fertilizer derived from Chilean caliche. Environ Pollut 112 299-302... 

Guggenheim Process. A process for the manuf of Na nitrate from Chilean nitrate ore, caliche, in which heat is efficiently utilized and handling costs are kept to a minimum... 

Formerly all the iodine was made from the ash of seaweed, and potash was a remunerative appendix to the iodine industry but just as the Stassfurt salts killed those industries which extracted potash from other sources, so did the separation of iodine from the caliche mother-liquors threaten the industrial extraction of iodine from seaweed with extinction. Iodine in a very crude form was exported from Chili in 1874—e.g. a sample was reported with iodine 52-5 per cent. iodine chloride, 3-3 sodium iodate, 13 potassium and sodium nitrate and sulphate, 15 9 magnesium chloride, 0 4 insoluble matter, 1 5 water, 25-2 per cent. About that time much of the iodine was imported as cuprous iodide. This rendered necessary the purification of the Chilian product but now the iodine is purified in Chili before it is exported. The capacity of the Chilian nitre works for the extraction of iodine is greater than the world s demand. It is said that the existing Chilian factories could produce about 5100 tons of iodine per annum whereas the... 

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 ... 

Potassium nitrate, essential in the manufacture of black gun powder, was produced by the Chinese, who had developed gun powder by the tenth century AD. The process involved the leaching of soil in which nitrogen from urine had combined with mineral potassium. By the early 1800s, potassium nitrate had become a strategic military chemical and was still produced, primarily in India, by using the ancient Chinese method. The caliche deposits in Chile are the only natural source of potassium nitrate (2). These deposits are not a rich source of potassium nitrate, purifying only to about 14% as K O. 

Among the properties sought in the solvent are low cost, availability, stability, low volatility at ambient temperature, limited miscibility in aqueous systems present in the process, no solvent capacity for the salts, good solvent capacity for the acids, and sufficient difference in distribution coefficient of the two acids to permit their separation in the solvent-extraction operation. Practical solvents are C4, C5, and C6 alcohols. For industrial process, C5 alcohols are the best choice (see Amyl ALCOHOLS). Small quantities of potassium nitrate continue to be produced from natural sources, eg, the caliche deposits in Chile. 

CALICHE (Nitrate). The gravel, rock. soil, or alluvium cemented with soluble salts of sodium in the nitrate deposits of the Atacama Desert of northern Chile and Peru. The material contains from 14 to 25% sodium nitrate, 2 to 3% potassium nitrate, and up to I i sodium iodaic. plus some sodium chloride, sulfate, and borate. At one time, this was an important natural fertilizer. 

Nitrate. Sodium nitrate, nitrate of soda, Chile saltpeter, caliche, [CAS 7631-99-4], NaN03, white solid, soluble, mp 308°C. source in nature is Chile, in the fixation of atmospheric nitrogen HN03 is frequently transformed by sodium carbonate into sodium nitrate, and the solution evaporated. Used tl) as an important nitrogenous fertilizer, (2) as a source of nitrate and HNO3, (3) in pyrotechnics, (4) in fluxes,... 

Caliche or Nitre- Bed. A term used in Chile for a layer of gravel or rocks contg Na nitrate (Chile saltpeter) together with Na sulfate (salt cake), Na chloride (table salt) small amts of other salts. Caliche varies in depth from 2 to 20ft and is covered by 1 to 12ft of sand overburden. The deposits are found in a desert in Atacama of province Tarapaca (Northern Chile) extending 400 miles north and south with a width of 5 to 40 miles. Deposits of Na nitrate, on a smaller scale have been found in Argentina, Bolivia, California and Peru (Ref 1, 2 3)... 

Mineral Deposits. The only iodine obtained from minerals has been a by-product of the processing of nitrate ores in Chile. Caliche occurs in the Atacama desert of Northern Chile and west of the Andes mountains. The Atacama desert is known as the driest of the world s deserts, where measurable (>1 mm) rainfalls may be as infrequent as once every 5—29 years (58). The caliche deposits occur in an area averaging 700 km (north—south) by 30 km (east—west). The iodine may total over 5 x 106 t (59). 

The first iodine recovery from caliche occurred in 1852 the first iodine was exported to Europe in 1868, becoming the most important by-product of the nitrate production in terms of value. There are two ways for producing iodine from caliche iodates first, from solutions containing more equivalent iodine than its solubility as elemental iodine in the same solution of about 0.4 g/L at 25°C and second, from more diluted equivalent iodine solutions. 

Sodium nitrate, NaN03.—Immense deposits of sodium nitrate are situated in Chile, hence the name Chile saltpetre. The local name is Caliche. The origin of the deposits is a matter of dispute.2 The crude product is contaminated with clay and sand, and is purified by crystallization from water. An important impurity is sodium iodate, a valuable source of iodine.8 Analyses have been given by Machattie 4 (I.) and Schulze5 (II.), the numbers expressing percentages ... 

Fig. 1. Schematic of a nitrate ore bed, detailing the various overburden layers. The overburden thickness can vary from 0 to 2.5 m, where chuca = 0.1 0.5 m, panqueque = 0.1 0.4 m, and poorly cemented gravel = 1.5—2.5 m. Caliche ranges from 0.8 to 8 m.

Numerous theories exist as to how the Chilean deposits formed and survived. It has been postulated that the unique nitrate-rich caliche deposits of northern Chile owe diein existence to an environment favorable to accumulation and preservation of the deposits, rather than to any unusual source of the saline materials (2). The essential conditions are an extremely arid climate similar to that of the Atacama desert in the 1990s, slow accumulation during the late Tertiary and Quaternary periods, and a paucity of nitrate-utilizing plants and soil microorganisms. 

SQM Nitratos (Chile) operates two sodium nitrate plants in northern Chile Pedro de Valdivia and Marna Elena, about 30 km distant from one another. The caliche is mined in open-pit areas. A solar evaporation plant, Coya Sur, Hes in between. A flow sheet of the processing operations for sodium nitrate production is shown in Figure 2. 

Most of the iodine of commerce is derived from the ashes of certain varieties of seaweed, or from the mother-liquor—aqua vieja— remaining after the extraction of sodium nitrate from the caliche of Chili. Methods have been also proposed for extracting iodine from blast furnace gases, from natural waters,2 and from natural phosphates but they have not proved to be of any commercial importance in view of the relative abundance of the Chilian supply. Not much progress has been made by electrolytic processes. T. Parker and A. E. Robinson proposed to electroylze a soln. of the alkali iodide acidified with sulphuric acid, in a cell with a diaphragm separating the platinum or carbon anode from the iron cathode. The iodine which separated at the anode was to be washed with water, and dried by hot air. 

The extraction of iodine from caliche.—The mother-liquor—aqua vieja— remaining after the extraction of sodium nitrate from caliche in Chili, contains sodium nitrate, chloride, sulphate, and iodate as well as magnesium sulphate. The iodine content of this liquid amounts up to about 0 3 per cent, as the original caliche has about 0 02 per cent., the iodine thus accumulates in the mother liquid during the extraction of the nitrate. The mother liquid is run into wooden vats,... 

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