Potassium chloride sources

Phosphorus-nitrogen arsenic-chlorine type Alkali metal salt thermionic type Potassium chloride source for phosphorus compounds, rubidium source for nitrogen compounds [397]... 

The element is much more abundant than was thought several years ago. It is now considered to be the 16th most abundant element in the earth s crust. Rubidium occurs in pollucite, leucite, and zinnwaldite, which contains traces up to 1%, in the form of the oxide. It is found in lepidolite to the extent of about 1.5%, and is recovered commercially from this source. Potassium minerals, such as those found at Searles Lake, California, and potassium chloride recovered from the brines in Michigan also contain the element and are commercial sources. It is also found along with cesium in the extensive deposits of pollucite at Bernic Lake, Manitoba. 

Potassium Chloride. The principal ore encountered in the U.S. and Canadian mines is sylvinite [12174-64-0] a mechanical mixture of KCl and NaCl. Three beneficiation methods used for producing fertilizer grades of KCl ate thermal dissolution, heavy media separation, and flotation (qv). The choice of method depends on factors such as grade and type of ore, local energy sources, amount of clay present, and local fuel and water availabiUty and costs. 

A variety of shale-protective muds are available which contain high levels of potassium ions (10). The reaction of potassium ions with clay, well known to soil scientists, results in potassium fixation and formation of a less water-sensitive clay. Potassium chloride, potassium hydroxide, potassium carbonate [584-08-7] (99), tetrapotassium pyrophosphate [7320-34-5] (100), and possibly the potassium salts of organic acids, such as potassium acetate [127-08-2] (101) and formate, have all been used as the potassium source. Potassium chloride is generally preferred because of its low cost and availabihty. 

Approximately 98% of the potassium recovered ia primary ore and natural brine refining operations is recovered as potassium chloride. The remaining 2% consists of potassium recovered from a variety of sources. Potassium produced from these sources occurs as potassium sulfate combiaed with magnesium sulfate. Prom a practical point of view, the basic raw material for ak of the potassium compounds discussed ia this article, except potassium tartrate, is potassium chloride. Physical properties of selected potassium compounds are Hsted ia Table 3, solubkities ia Table 4. 

Potassium Nitrate. Potassium nitrate [7757-79-17, KNO, is produced commercially in the United States based on the reaction of potassium chloride and nitric acid (qv) (35). Ammonia (qv) oxidation is the source for the nitric acid and the reaction is manipulated chemically to yield chlorine as a co-product. The process is operated at an elevated temperature to drive the reaction to completion according to the following equation ... 

Devising an economical method of producing agricultural-grade potassium phosphates from potassium chloride and wet-process phosphoric acid has been the subject of intense agricultural—chemical research (37—39). Limited quantities have been produced industrially. The impact on the overall quantities of phosphoms and potassium compounds consumed by the fertilizer industry is small. Because potassium phosphates are an excellent source of two essential fertilizer elements, this research is expected to continue. 

A second source of brine is found in terminal lakes. The Dead Sea in Israel and Jordan is an example of a large terminal lake with almost unlimited supphes of magnesium chloride, potassium chloride, and sodium chloride. Mote than two and a half million tons of potassium chloride ate extracted from the Dead Sea each year. 

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. 

There has been much interest in making chemicals from brine because of the low expense compared to alternative methods. Lithium, for example, had been mostly produced from spodumene ore, but now most is produced from brine. Those now producing from ore are seriously researching brine reserves and contemplating converting to brine sources before the turn of the century. Similady, solar salt has cost advantages over mined rock salt. Potassium chloride produced from brine has more than doubled from 1980 to 1990. 

The catalyst, and the source of the oxygen, is cupric oxide dissolved in a molten mixture of cupric chloride and potassium chloride. Developed by Lummus Corporation. 

Large deposits of sylvinite (42.7% KCl, 56.6% NaCl) near Carlsbad, New Mexico, account for 85% of the potassium products produced in the U.S. The potassium chloride can be separated by either fractional crystallization or flotation. Potassium chloride is also obtained from the brines of Searles Lake, California. All these sources give potash (97% potassium chloride) with a 60% K2O equivalent for fertilizer use. A chemical-grade product can be obtained to a purity of 99.9% potassium chloride. Almost all potash produced is potassium chloride. Potash is used mainly as fertilizer (88%) with a small amount (12%) used in chemical manufacture. 

This chapter is concerned with the three primary nutrients making up most fertilizers nitrogen, phosphorus, and potassium. The usual sources of nitrogen are ammonia, ammonium nitrate, urea, and ammonium sulfate. Phosphorus is obtained from phosphoric acid or phosphate rock. Potassium chloride is mined or obtained from brine and the sulfate is mined in small amounts. Potassium nitrate is made synthetically. These chemicals have already been described under inorganic chemicals of the top 50. Sources for the three primary nutrients are given in Fig. 21.1. 

Potassium chloride is the most important salt of potassium from the perspective of its abundant occurrence and apphcations. This salt, along with potassium sulfate, is used heavily in fertilizers as the primary source of potassium, an essential element for crops. Over 90% salt manufactured is consumed as fertilizer. Also, potassium chloride is a raw material for producing potassium metal and several important potassium salts including potassium nitrate, potassium hydroxide, and potassium sulfate. Other applications are in electrode cells photography buffer solutions and measurement of salinity in water. 

Potassium sulfate is used in fertilizers as a source of potassium and sulfur, both of which are essential elements for plant growth. Either in simple form or as a double salt with magnesium sulfate, potassium sulfate is one of the most widely consumed potassium salts in agricultural apphcations. It is preferred over potassium chloride for certain types of crops such as, tobacco, citrus, and other chloride—sensitive crops. Some other applications include making gypsum cements to make potassium alum in the analysis of Kjeldahl nitrogen and in medicine. 

The experimental apparatus consists essentially of a narrow vertical glass tube down the inner surface of which one liquid is made to flow, the other liquid emerges from a fine glass tip in the form of a narrow jet down the axis of the tube. The two solutions are connected with calomel electrodes employing potassium chloride or nitrate as junction liquids. The E.M.F. of the cell is measured by means of a sensitive quadrant electrometer. The greatest source of error in the method is the elimination of or the calculation of the exact values of the liquid-liquid junction potentials in the system. For electrolytes which are not very capillary active, the possible error may amount to as much as fifty per cent, of the observed E.M.F. 

In the latter half of the nineteenth centuiy the United States was dependent on the vast Stassfurt deposits of Germany for the potassium compounds needed as fertilizers. In 1911 Congress appropriated funds for a search for domestic minerals, salts, brines, and seaweeds suitable for potash production (67). The complex brines of Searles Lake, California, a rich source of potassium chloride, have been worked up scientifically on the basis of phase-rule studies with outstanding success. Oil drillers exploring the Permian Basin for oil became aware of the possibility of discovering potash deposits through chemical analysis of the cores of saline strata. A rich bed of sylvinite, a natural mixture of sylvite (potassium chloride) and halite (sodium chloride), was found at Carlsbad, New Mexico. At the potash plane near Wendover, Utah, the raw material, a brine, is worked up by solar evaporation (67). 

The first ratio gives the relation between the mol. wt. of oxygen as standard and the mol. wt. of potassium chloride the second gives the relation between potassium chloride and silver and the third the relation between silver and chlorine. J. S. Stas work on at. wt. has been deservedly eulogized. For many years it was considered to be so near perfection as was possible to man. J. S. Stas seemed to have taken the most subtle precautions to exclude errors of manipulation, and to ensure the purity of his materials. He also followed the advice of J. J. Berzelius, for, in order to eliminate constant errors, he used materials from different sources, and followed many different paths in arriving at his results. Only when consistent values were obtained by different methods did he assume that the results were reliable. The following outline will give an idea of the plan of J. S. Stas work ... 

Preparation of Potassium Hydroxide by the Electrolysis of a Potassium Chloride Solution. Assemble an electrolyzer (see Fig. 130, p. 231). Place small cylinder 2 (8 cm in height and 4 cm in diameter) made from uncalcined clay into 0.5-litre thick-walled beaker 1. Pour a saturated potassium chloride solution into both vessels so that the level of the liquid in them will be the same. Add a few drops of phenolphthalein to the electrolyte. Use carbon rod 4 as the anode and thick iron wire 3 as the cathode. Secure both electrodes with corks in the electrolyzer lid. A d-c source at 10 V is needed for the experiment. After assembling the electrolyzer, switch on the current. What happens in the anode and cathode compartments Write the equations of the reactions. What substances can form in the absence of a diaphragm ... 

Lenher 6 determined the atomic weight of tellurium by decomposing weighed amounts of potassium telluribromide, K2TeBr6, by means of chlorine and hydrogen chloride, and weighing the potassium chloride which remained. Using tellurium ores from three different sources, the oxide obtained was converted into the double bromide by the action of hydrobromic acid and potassium bromide the telluribromide formed was crystallised repeatedly from water. As a mean of sixteen concordant experiments Lenher obtained the value 127-55. 

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