Ammonia soda production

Sodium bicarbonate precipitates from solution and is recovered by filtration. Ammonium chloride is then crystallised from the filtrate, separated, washed, and dried. The exact proportion of ammonium chloride recovered depends on the relative demands for sodium carbonate and ammonium chloride. If economic conditions requite, part of the ammonia can be recovered and returned to the hrine-ammoniation step by distillation of the ammonium chloride solution ia the presence of lime. The spent calcium chloride Hquor, a final product ia manufacture of sodium carbonate by the ammonia—soda process, can also be used to obtain ammonium chloride. This Hquor is treated with ammonia and carbon dioxide... 

Ammonia-soda Also called the Solvay process. A process for making sodium carbonate. The basic process was invented and partially developed in the first half of the 19th century by several workers, but the key invention was made by E. Solvay in Belgium in 1861. The first plant was built at Couillet, Belgium, in 1864 and thereafter the process became accepted worldwide, displacing the Leblanc process. The raw materials are limestone and salt calcium chloride is a waste product. The overall reaction is ... 

The black product was extracted with water and the sodium carbonate in it was recovered by concentration and crystallization. The residue, chiefly calcium sulfide, known as galigu, was dumped on land and created an environmental nuisance for many years because it never hardened. The process was invented by N. Leblanc in France in 1789, in response to a competition organized by the French Academy of Sciences. Operation of the first factory was delayed for several years because of the French Revolution. The process was operated widely until it was progressively superseded by the Ammonia-soda process in 1872. But it was still in use in Bolton, UK, until 1938, and the last plant in Europe closed in 1992. See also Black ash. 

Ammonia or its salts are employed in a variety of ways in many trades. From it nitric acid, the vital necessity for the manufacture of all high explosives, can be made it is an essential for the Brunner Mond or Solvay ammonia soda process for the production of alkali in the liquid form it is employed all over the world in refrigerating machinery, but its enormous and increasing use is in agfriculture, where, in the form of sulphate of ammonia, it constitutes one of, if not the most important chemical manures known to man. During the year 1916 350,000 tons of ammonium sulphate were produced in this country, the larger proportion of which was consumed in agriculture—a proportion likely to increase and not diminish if the demand for home production of food continues. 

Calcium chloride is obtained as a by-product in the manufacture of sodium carbonate (soda ash) by ammonia-soda (Solvay) process. The process involves the reaction of sodium chloride with calcium carbonate and ammonia. Calcium chloride is currently produced in bulk amounts by evaporation of natural underground brines. In the laboratory, calcium chloride can be prepared by treating bmestone with hydrochloric acid followed by evaporation of solution to obtain crystals. The crystals are dehydrated to obtain anhydrous salt. Calcium oxide or hydroxide may be used instead of carbonate. 

Sodium carbonate at present is mostly mined from its natural deposits. It also is manufactured syntheticallly by Solvay (or ammonia-soda) process. The natural production of sodium carbonate currently has supassed its synthetic production. 

The LeBlanc process was the principal method of producing soda ash until 1860 when the Belgian Ernest Solvay (1838-1922) developed the process that bears his name. The Solvay process, sometimes called the ammonia method of soda production, utilized ammonia, NH3, carbon dioxide, and salt to produce sodium bicarbonate (baking soda), NaHCOj. Sodium bicarbonate was then heated to give soda ash. The series of reactions representing the Solvay process are... 

The direct product of the ammonia-soda process and its modifications is Sodium hydrocarbonate, NaHC03 and as indicated in connection with the occurrence of sodium carbonate, it occurs in alkaline spring waters in association... 

Calcium Chloride, CaCl2 mw 110.99, col, delq cubic crysts, mp 772°, bp >1600°, d 2.5 12, nD1.52 at 20° sol in w or ale forms mono-, di-, tetra- hexa-hydrates. This salt is obtd as a by-product in several manufg processes, such as the ammonia-soda process the production of KC1. It is used as a drying agent in the lab, and commercially as an antifreeze, antidust conditioning agent... 

The resulting cyanomethyl compound is insoluble in water and is therefore easily separated from excess reactants and by-products that remain in the water. The ammonia by-product is removed by distillation. The purified cyanomethyl compound is then hydrolyzed with caustic soda in a separate step to make pure tetrasodium EDTA250. 

Sodium hydrogen carbonate, NaHC03.—The primary salt is an intermediate product in the ammonia-soda process, and can be prepared... 

Manufacture. Sodium carbonate is an important product of the alkali industry. It is obtained naturally by the purification of sal soda which is found in the water of lakes Magadi of Kenya in East Africa, Owens of California in the USA etc. Industrially it is obtained by the Solvay process (ammonia-soda process) sodium chloride solution is saturated by ammonia which is forced into the solution. Carbon dioxide gas is then blown into the solution to form the bicarbonate (NaHCO 3) and ammonium chloride (NH<,.C1). When the bicarbonate is separated and heated, water and carbon dioxide are driven off and sodium carbonate is obtained. The ammonium chloride is mixed with milk of lime and distilled to form calcium chloride and ammonia solution. The recovered ammonia is used repeatedly. 

Derivation (1) As a by-product of the ammonia-soda process, (2) reaction of ammonium sulfate and sodium chloride solutions. 

A shift to the processing of substantial alternate natural mineral sources of sodium carbonate in the U.S. has eliminated the calcium chloride disposal problems of the Solvay process for sodium carbonate production. Coupling this advantage to the much lower capital cost of a natural sodium carbonate plant has contributed to the shift away from synthetic sodium carbonate in the U.S. [13] (Table 7.3). Kenya is the only other country reported to be recovering natural sodium carbonate and was operating at 260,000 metric toimes in 2001 [19]. China, the second largest producer, and all other world producers still rely heavily on the ammonia-soda process [17, 24] (Table 7.4). 

Calcium Chloride. Irtergravin -Orales. CaCI. mo] wt 110,99. Ca 36.11%, Cl 63.89%. Forms mono-, di -, tetra -and hexahydrates. Obtained as a byproduct of the ammonia-soda (Solvay) process and as a joint product from natural salt brines Faith, Keyes Clark s Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley-Intersci-ence, New York, 4th ed., 1975) pp 186-190. Acute toxicity I. B. Syed, F. Hosain, Toxicol. Appl. Pharmacol. 22, 150 (1972). 

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