Calcium hydroxide manufacture

Maleic Anhydride. The ACGIH threshold limit value in air for maleic anhydride is 0.25 ppm and the OSHA permissible exposure level (PEL) is also 0.25 ppm (181). Maleic anhydride is a corrosive irritant to eyes, skin, and mucous membranes. Pulmonary edema (collection of fluid in the lungs) can result from airborne exposure. Skin contact should be avoided by the use of mbber gloves. Dust respirators should be used when maleic anhydride dust is present. Maleic anhydride is combustible when exposed to heat or flame and can react vigorously on contact with oxidizers. The material reacts exothermically with water or steam. Violent decompositions of maleic anhydride can be catalyzed at high temperature by strong bases (sodium hydroxide, potassium hydroxide, calcium hydroxide, alkaU metals, and amines). Precaution should be taken during the manufacture and use of maleic anhydride to minimize the presence of basic materials. 

Properties Commercial grades Uses Manufacture White to grayish-white solid. Reacts with water to form calcium hydroxide. Commercial lime is available in lump, pebble, ground, and pulverized forms. One of the oldest commercial chemicals. Used in hundreds of applications. The most important uses are for making steel and chemicals, water treatment, pollution control, pulp and paper, and construction. Limestone (calcium carbonate, CaCOj) from mines or quarries is heated in a kiln (calcined). 

Pennwalt Formerly called Pennsalt. A process for making calcium hypochlorite by passing chlorine into an aqueous suspension of calcium hypochlorite and calcium hydroxide. Developed by the Pennsylvania Salt Manufacturing Corporation in 1948. 

The next major raw material for which we discuss the derived chemicals is calcium carbonate, common limestone. It is the source of some carbon dioxide, but, more importantly, it is used to make lime (calcium oxide) and slaked lime (calcium hydroxide). Limestone, together with salt and ammonia, are the ingredients for the Solvay manufacture of sodium carbonate, soda ash. Soda ash is also mined directly from trona ore. The Solvay process manufactures calcium chloride as an important by-product. Soda ash in turn is combined with sand to produce sodium silicates to complete the chemicals in the top 50 that are derived from limestone. Since lime is the highest-ranking derivative of limestone in terms of total amount produced, we discuss it first. Refer to Fig. 2.1, Chapter 2, Section 1, for a diagram of limestone derivatives. 

Obtained from manufacturer of konnyaku, a type of food made from the tuber of the konyak plant (Amorphophallus konjac C. Koch). c Citrus pectin purchased from Tokyo Kasei Co., Tokyo. d 3 mg of calcium hydroxide was added. e n.d. = not determined. 

Calcium hydroxide has wide industrial applications. It is used to make cement, mortar, plaster, and other building materials. It also is used in water soluble paints, and for fireproofing coatings and lubricants. Other applications are in the manufacture of paper pulp as a preservative for egg in vulcanization of rubber as a depilatory for hides and in preparation of many calcium salts. 

Pentaerythritol is made by mixing formaldehyde with calcium hydroxide in an aqueous solution held at 65-70 °C. Nitration of pentaerythritol can be achieved by adding it to concentrated nitric acid at 25-30 °C to form PETN. The crude PETN is removed by filtration, washed with water, neutralized with sodium carbonate solution and recrystallized from acetone. This manufacturing process for PETN results in 95% yield with negligible by-products. The process is summarized in Reaction 7.9 (overleaf). 

Hydroxide. Potassium hydroxide, [CAS 1310-58-3]. caustic potash, potassium hydrate, KOH, white solid, soluble, mp 380 C, formed (1) by reaction of potassium carbonate and calcium hydroxide in H2O, and then separation of the solution and evaporation. (2) by electrolysis of potassium chloride under the proper conditions, and evaporation. Used in the preparation of potassium salts f 1) in solution, and (2) upon fusion. Also used 111 the manufacture of (3) soaps, (4) drugs. (5) dyes, (6) alkaline batteries, (7) adhesives, (8) fertilizers, (9) alkylates, (10) for purifying industrial gases, (11) for scrubbing out traces of hydrofluoric add in processing equipment, (12) as a drain-pipe cleaner, and (13) in asphalt emulsions. 

Calcium hydroxide is a cheap industrial alkali (Figure 13.9). It is used in large quantities to make bleaching powder, by some farmers to reduce soil acidity, for neutralising acidic industrial waste products, in the manufacture of whitewash, in glass manufacture and in water purification. Calcium hydroxide, in its white powder form, is produced by adding an equal amount of water to calcium oxide in a carefully controlled reaction. The control is needed because it is a very exothermic reaction. 

CaO). It is produced by heating limestone. It is used to counteract soil acidity and to manufacture calcium hydroxide (slaked lime). It is also used as a drying agent in industry. Photosynthesis The opposite of respiration. The process by which plants synthesise sugars. 

Calcium acetate is manufactured by the reaction of calcium carbonate or calcium hydroxide with acetic acid. 

Calcium hypochlorite is manufactured by chlorination of calcium hydroxide [CaOH)2] followed by the separation of the calcium hypochlorite [Ca(OCl)2] through salting out from solution with sodium chloride. 

Calcium hypochlorite is also manufactured by the formation under refrigeration of the complex salt Ca(OCl)2 Na0ClNaC112H20, which is prepared by the chlorination of a mixture of sodium hydroxide and calcium hydroxide. The salt is reacted with a chlorinated lime slurry, filtered to remove salt, and dried, resulting finally in a stable product containing 65 to 70% calcium hypochlorite. 

Sodium chlorite (NaC102) is manufactured from chlorine dioxide, sodium hydroxide, and calcium hydroxide. 

Its principal use is in steelmaking, but it also goes into the manufacture of chemicals, water treatment, and pollution control. In the Solvay process, calcium carbonate and sodium chloride are used to produce calcium chloride and sodium carbonate with ammonia (which is recycled) as a medium for dissolving and carbonating the sodium chloride and calcium hydroxide for precipitating calcium chloride from the solution. 

Several addition reactions have been or are currently used on a large scale in industrial chemical plants. For example, an older method for the preparation of ethylene oxide employed the addition of chlorine to ethylene in water to form ethylene chlorohydrin or 2-chloroethanol. (In industry, ethene is almost always called ethylene.) Treatment of the chlorohydrin with calcium hydroxide results in the formation of ethylene oxide, which is an important intermediate in the manufacture of ethylene glycol and other products (see the Focus On box on page 375). However, this method is wasteful of... 

Limestone, chalk, and marble are all forms of calcium carbonate. Limestone rock can be used to build roads, but it is a very important basic compound used in large quantities by chemical industries. For example, limestone is used directly to make concrete and cement. It is also used in the manufacture of glass and in agriculture. Limestone is often processed to make quicklime, CaO, and hydrated lime (calcium hydroxide), Ca(OH)2. 

A primary method for the manufacture of acetylene is to react calcium carbide, the principal raw material, with water to produce acetylene with calcium hydroxide as a byproduct ... 

The process is operated at 80 to 90°C, with a slight excess of the calcium hydroxide. This was the only method used for making sodium hydroxide after the invention of the Leblanc process and before the introduction of the Castner-Kellner process around 1890. The process is still used when the demands for chlorine and sodium hydroxide from the Castner-Kellner process are unbalanced, and for the regeneration of waste pulping liquors in the manufacture of pulp and paper by the Kraft process. See also Lowig. 

The treatment of bleached kraft pulp with sodium borohydride followed by incorporation of basic calcium salts increased the stability of paper made from this pulp by 1.5-2.6 times. When manufactured paper, rather than pulp, was subjected to sodium borohydride treatment followed by washing with an aqueous solution of calcium hydroxide, the stability of the paper increased by as much as 4 times for groundwood paper and 30 times for bleached kraft paper. 

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