Potash manufacturing

Other processes for making chlorine include sodium manufacture, caustic potash manufacture, hydrogen chloride decomposition, the nitro-syl chloride (NOC1) process, and a process where salt is treated with nitric acid to form sodium nitrate and chlorine with nitrosyl chloride (containing 4 to 10% nitrogen tetroxide) as a by-product. The nitrosyl chloride vapor is placed in contact with oxygen to produce nitrogen tetroxide and chlorine ... 

Alkalies, caustic soda, and potash manufacturing industries... 

Table 7.3 Residual moisture content as provided by different techniques of solid-liquid separation (experiences from potash manufacture) [12].

Chlorine from Potassium Hydroxide Manufacture. One of the coproducts during the electrolytic production of potassium hydroxide employing mercury and membrane ceHs is chlorine. The combined name plate capacity for caustic potash during 1988 totaled 325,000 t/yr and growth of U.S. demand was expected to be steady at 2% through 1990 (68). 

World consumption of potassium salts presentiy exceeds 28 million t of K O equivalent per year. About 93% of that is for fertilizer use (see POTASSIUM compounds). The potash [17353-70-7] industry is essentially a mining and beneftciation industry. The two main fertilizer materials, KCl and K SO are produced by beneftciating ores at the mine sites. The upgraded salts then are shipped to distributors and manufacturers of mixed goods. 

The U.S. domestic commercial potassium nitrate of the 1990s contains 13.9% N, 44.1% I+O, 0—1.8% Cl, 0.1% acid insoluble, and 0.08% moisture. The material is manufactured by Vicksburg Chemical Co. using a process developed by Southwest Potash Division of AMAX Corp. This process uses highly concentrated nitric acid to catalyze the oxidation of by-product nitrosyl chloride and hydrogen chloride to the mote valuable chlorine (68). The much simplified overall reaction is... 

Preparation and Manufacture. Magnesium chloride can be produced in large quantities from (/) camalhte or the end brines of the potash industry (see Potassium compounds) (2) magnesium hydroxide precipitated from seawater (7) by chlorination of magnesium oxide from various sources in the presence of carbon or carbonaceous materials and (4) as a by-product in the manufacture of titanium (see Titaniumand titanium alloys). 

Potassium chloride [7447-40-7] or muriate of potash (MOP) as it is known in the fertilizer industry (at about 97% purity), is the world s most commonly used potash (5). Chemical-grade potassium chloride (99.9%) is the basis for manufactured production of most potassium salts (10). 

Sulfates of sodium are iadustriaUy important materials commonly sold ia three forms (Table 1). In the period from 1970 to 1981, > 1 million metric tons were consumed aimuaHy ia the United States. Siace then, demand has declined. In 1988 consumption dropped to 890,000 t, and ia 1994 to 610,000 t (1,2). Sodium sulfate is used principally (40%) ia the soap (qv) and detergent iadustries. Pulp and paper manufacturers consume 25%, textiles 19%, glass 5%, and miscellaneous iadustries consume 11% (3). About half of all sodium sulfate produced is a synthetic by-product of rayon, dichromate, phenol (qv), or potash (see Chromium compounds Fibers, regenerated cellulosics Potassium compounds). Sodium sulfate made as a by-product is referred to as synthetic. Sodium sulfate made from mirabilite, thenardite, or naturally occurring brine is called natural sodium sulfate. In 1994, about 300,000 t of sodium sulfate were produced as a by-product another 300,000 t were produced from natural sodium sulfate deposits (4). 

Manufacture, Shipment, and Analysis. In the United States, sodium and potassium thiocyanates are made by adding caustic soda or potash to ammonium thiocyanate, followed by evaporation of the ammonia and water. The products are sold either as 50—55 wt % aqueous solutions, in the case of sodium thiocyanate, or as the crystalline soHds with one grade containing 5 wt % water and a higher assay grade containing a maximum of 2 wt % water. In Europe, the thiocyanates may be made by direct sulfurization of the corresponding cyanide. The acute LD q (rat, oral) of sodium thiocyanate is 764 mg/kg, accompanied by convulsions and respiratory failure LD q (mouse, oral) is 362 mg/kg. The lowest pubhshed toxic dose for potassium thiocyanate is 80—428 mg/kg, with hallucinations, convulsions, or muscular weakness. The acute LD q (rat, oral) for potassium thiocyanate is 854 mg/kg, with convulsions and respiratory failure. 

Isosafrol results from the isomerisation of safrol by heating with alcoholic potash, and this conversion is the preliminary step in the manufacture of heliotropine since isosafrol yields considerably more heliotropine on oxidation than safrol does. Isosafrol has the following constitution —... 

Potassium hydroxide (KOH) is commonly referred to as caustic potash or lye because of its extreme alkahnity (high pH value). It is produced in an electrolytic cell reaction (2KC1 + THfD —> Hj + CIj + 2KOH). It is used to manufacture soaps and as a caustic drain cleaner because it is strong enough to dissolve animal fats that clog household and restaurant drains. 

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. 

Long before sodium and potassium metals were isolated, many of their compounds were in common use. Among the most important of these were potash (potassium carbonate), cream of tartar, saltpeter, alum, common salt, Glaubers salt, and soda (sodium carbonate). Both potash and soda have been used since ancient times in the manufacture of glass. 

In an attempt to find out whether the presence of soda or potash depended on a specific difference in the plants which produce them or on the composition of the soils, du Hamel devoted many years to agricultural experiments, at his estate at Denainvilliers, on the culture of the common saltwort (Salsola kali), a plant used for the manufacture of soda ash. The final analyses of the ash of this plant proved that in the first year the mineral alkali still predominated, but that in succeeding years the vegetable alkali rapidly increased until finally, after a few generations, the soda had almost disappeared (50). In these experiments, he had for many years the invaluable and enthusiastic help of his brother, M. de Denainvilliers. In his eulogy of du Hamel in the History of the Academy of Sciences, the Marquis de Condorcet gave the following characterizations of the two brothers ... 

Uses Of the Stassfurt salts.—The magnesium compounds in the Stassfurt salts are used for the preparation of magnesium and of its salts. The potash salts are an essential constituent of many fertilizers used in agriculture, etc. 22 and potassium chloride is the starting-point for the manufacture of the many different kinds of potassium salts used in commerce—carbonate, hydroxide, nitrate, chlorate, chromate, alum, ferrocyanide, cyanide, iodide, bromide, etc. Chlorine and bromine are extracted by electrolysis and other processes from the mother liquids obtained in the purification of the potash salts. Boric acid and borax are prepared from boracite. Caesium and rubidium are recovered from the crude carnallite and sylvite. 

Products resulting from the decay of organic matter—e.g. Indian nitre and South African nitre. The value of saltpetre for the manufacture of gunpowder and in the chemical industries is greatly in excess of its value as a fertilizer and consequently nitre is not usually regarded as a source of potash supply. (6) Blast furnace and cement-kiln dust. (7) The insoluble potash minerals—e.g. felspar, alunite, leucite, etc. 

Wood ashes.—The ash of wood, not coal, contains about 30 per cent, of potassium carbonate. Prior to the exploitation of the Stassfurt salts about the middle of the nineteenth century, the chief source of potash was wood ashes, and the process is still used in certain localities where wood-fuel is employed and where much waste wood is available—e.g. in some parts of Canada, United States, Russia, Spain, etc. The ash of trees, hedge-cuttings, sawdust, etc., can be made to yield potash.5 In the Caucasus, the sunflower is grown on waste land for the sake of its seed. The stalks, leaves, etc., are a by-product and are burnt the ash is used as a source of potash. Nearly 7000 tons per annum of crude potash from this source were exported from Novorossik in Russia. The residues in the manufacture of olive oil and almond shells are also stated by G. l Abate to be exceptionally rich in potash salts F. W. F. Day claims that the roots of the water hyacinth (eiehornia crassipes) have... 

The vinasse of sugar beet.—Sugar beet contains about 0 5 per cent, of potash, K20, largely in combination with organic acids. The potash accumulates in the molasses of the best sugar factories. The molasses are fermented and distilled for alcohol. The residue which remains in the retort—called vinasse—may be used as a manure, or it may be mixed with lime and ignited to form what was once called vinasse cinder, and used in the manufacture of soft-soap. It is, however, more profitably refined for potash by fractional crystallization.6 The product has approximately the composition ... 

Near the end of the eighteenth century the difference between the two fixed alkalies—potassium and sodium carbonates—was known sodium carbonate barilla was largely made from the ashes of sea plants, and potash from the ashes of land plants. The Arabs also had brought some natural soda into Europe, via Spain. These sources were not sufficient to cope with the demand for alkali for the manufacture of soap, glass, etc. Potash was at that time the cheaper and dominant alkali. With the steadily increasing demands for alkali and the very limited sources of supply presented by the incineration of wood, many attempts were naturally made to substitute the base of common salt, because that with a suitable method of extraction nature has provided inexhaustible, abundant, and cheap... 

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