Industrial soda ash

Industrial soda ash (sodium carbonate) is produced from natural reservoirs (e.g., in the USA) or by the Solvay process. The brutto reaction of the Solvay process is the conversion of NaCl and CaC03 into Na2C03 and CaCl2. Figure 5.2.1 shows the process scheme and the number of unit operations. The key achievement in the historic development of the process ( . Solvay) was to realize a quantitative regeneration of ammonia. This point was essential for economic success as the price of ammonia is typically higher than the prize of soda ash. 

United States Caustic Soda Production. In 1987 U.S. production of caustic soda increased to 10.4 million tons (fig. 1), more than 10% over that of the previous year, furthermore, 1988 production was up another 6.7% to 11.1 million tons. The demand for caustic soda has been very strong in recent years as evidenced by both increased U.S. consumption and a strong export demand. In 1987 the United States exported 1.5 million tons, 14.5% of the total caustic soda production (6), representing a 25.5% increase over exports in 1986. Then, in 1988, caustic soda exports grew by another 4.1%. A weak doUar helped boost the 1987 exports. Growth slowed in 1988, however, as a result of an industry (and world) wide caustic soda shortage, which was caused by lower U.S. chlorine consumption and forced allocations. Because industries switched from caustic to soda ash where possible, the lower 1988 export growth was not indicative of caustic soda s export potential. 

Alkalies. In the 1960s, 3.2-34 x 10 t /yr of lime was captively produced by the U.S. alkaH industry for manufacturing soda ash and sodium bicarbonate via the Solvay process. Electrolytic process caustic soda and natural soda ash (trona) from Wyoming have largely replaced the Solvay process. Three of the trona producers in Wyoming now purchase quicklime for producing caustic soda. 

In industrial production of acid-modified starches, a 40% slurry of normal com starch or waxy maize starch is acidified with hydrochloric or sulfuric acid at 25—55°C. Reaction time is controlled by measuring loss of viscosity and may vary from 6 to 24 hs. For product reproducibiUty, it is necessary to strictly control the type of starch, its concentration, the type of acid and its concentration, the temperature, and time of reaction. Viscosity is plotted versus time, and when the desired amount of thinning is attained the mixture is neutralized with soda ash or dilute sodium hydroxide. The acid-modified starch is then filtered and dried. If the starch is washed with a nonaqueous solvent (89), gelling time is reduced, but such drying is seldom used. Acid treatment may be used in conjunction with preparation of starch ethers (90), cationic starches, or cross-linked starches. Acid treatment of 34 different rice starches has been reported (91), as well as acidic hydrolysis of wheat and com starches followed by hydroxypropylation for the purpose of preparing thin-hoiling and nongelling adhesives (92). 

The efforts of the detergent industry toward solution of its part of the eutrophication problem are, at this point, less complete than its response to the biodegradabihty problem. Soda ash, Na2C02, sodium siUcate, and, to a lesser extent, sodium citrate formed the basis of the early formulations marketed in the areas where phosphates were harmed. Technically, these substances are considerably less effective than sodium tripolyphosphate. As a precipitant builder, soda ash can lead to undesirable deposits of calcium carbonate on textiles and on washing machines. 

Inorga.nicNIa.teria.ls. These include acids (sulfuric, nitric, hydrochloric, and phosphoric), bases (caustic soda, caustic potash, soda ash, sodium carbonate, ammonia, and lime), salts (sodium chloride, sodium nitrite, and sodium sulfide) and other substances such as chlorine, bromine, phosphoms chlorides, and sulfur chlorides. The important point is that there is a significant usage of at least one inorganic material in all processes, and the overall toimage used by, and therefore the cost to, the dye industry is high. 

The sodium bicarbonate produced is heated to 175 °C in rotary dryers to give light soda ash (Na2C03). Floles are left in the crystals obtained, as the carbon dioxide is liberated. Dense soda ash used by the glass industry is manufactured from the light ash by adding water and drying. 

Under hot BW conditions this reaction is reversible, leading to a serious risk of carbonate scale depositing on heat transfer surfaces. Consequently, many large water utilities and industries around the world continue to use the old established, but effective lime (calcium hydroxide) and soda ash (sodium carbonate) processes to soften water by precipitating out insoluble hardness salts. 

Soda ash (sodium carbonate) is less expensive than phosphate and so tends to be used as a BW treatment in some developing countries for basic industrial processes such as mashing of farm products for animal foods, palm oil extraction, rendering plants, tanneries, and textile washing and dyeing. Often there is little or no condensate return. 

The newly developed modified alkyl hydroxamate reagents (from Cytec Industries) tested in this study include S-8704, S-8704D, S-8705, S-8706, S-8706D and S-8765, while the reference collectors used were Aero Promoter 6493 (also from Cytec) and tall oil. The crude clays were dispersed using sodium silicate while soda ash was used to adjust the pH. The frother used in the flotation tests was Aerofroth 70. 

Lime is used in the paper industry to produce the bleaching agent calcium hypochlorite (Ca(OCl)2). Slaked lime is used to recover sodium hydroxide from soda ash after the pulping process ( )2( ) + Na2C03(a(i) —> 2NaOH(a(j) + CaC03(s). The recovered calcium carbonate can be used to regenerate lime. Lime is also used to treat process water in the paper industry. 

Sodium chloride has numerous uses one major producer lists more than 1,400 uses for its salt. Global production of salt is about 230 million tons annually about 50,000 tons are produced in the United States. The largest consumer of salt is the chemical industry, which uses approximately 60% of total production. The major chemical industry that uses salt is the chlor-alkali industry to produce soda ash (in countries that do not obtain it from natural deposits), caustic soda (NaOH), and chlorine (see Sodium Carbonate and Sodium... 

Castner turned his interest to gold extraction, which required high-quality sodium hydroxide. Castner developed a three-chambered electrolytic cell. The two end chambers contained brine and graphite electrodes. The middle chamber held water. The cells were separated excepted for a small opening on the bottom, which contained a pool of mercury that served as the cell s cathode. When current flowed through the cell and the cell was rocked, sodium reduced from the brine came into contact with water in the middle cell to produce a sodium hydroxide solution. As Castner built his mercury cell, Kellner was working on a similar design. Rather than compete with each other, Castner and Kellner joined forces to establish the Castner-Kellner Alkali Company to produce sodium hydroxide, which competed with soda ash and potash as an industrial base, and chlorine, which was used primarily to make bleach. 

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