Lime CaO

Maintenance of conditions ia the culture environment that keep stress to a minimum is one of the best methods of a voiding diseases. Vacciaes have beea developed agaiast several diseases and more are under development. Selective breeding of animals with disease resistance has met with only limited success. Good sanitation and disiafection of contaminated faciUties are important avoidance and control measure. Some disiafectants are Hsted ia Table 6. Poad soils can be sterilized with burnt lime (CaO), hydrated lime [Ca(OH)2], or chlorine compounds (12). 

Lime Soda. Process. Lime (CaO) reacts with a dilute (10—14%), hot (100°C) soda ash solution in a series of agitated tanks producing caustic and calcium carbonate. Although dilute alkaH solutions increase the conversion, the reaction does not go to completion and, in practice, only about 90% of the stoichiometric amount of lime is added. In this manner the lime is all converted to calcium carbonate and about 10% of the feed alkaH remains. The resulting slurry is sent to a clarifier where the calcium carbonate is removed, then washed to recover the residual alkaH. The clean calcium carbonate is then calcined to lime and recycled while the dilute caustic—soda ash solution is sent to evaporators and concentrated. The concentration process forces precipitation of the residual sodium carbonate from the caustic solution the ash is then removed by centrifugation and recycled. Caustic soda made by this process is comparable to the current electrolytic diaphragm ceU product. 

Raw juice is heated, treated sequentially with lime (CaO) and carbon dioxide, and filtered. This accomplishes three objectives (/) microbial activity is terminated (2) the thin juice produced is clear and only lightly colored and (J) the juice is chemically stabilized so that subsequent processing steps of evaporation and crystalliza tion do not result in uncontrolled hydrolysis of sucrose, scaling of heating surfaces, or coprecipitation of material other than sucrose. 

Other Phases in Portland and Special Cements. In cements free lime, CaO, and periclase, MgO, hydrate to the hydroxides. The in situ reactions of larger particles of these phases can be rather slow and may not occur until the cement has hardened. These reactions then can cause deleterious expansions and even dismption of the concrete and the quantities of free CaO and MgO have to be limited. The soundness of the cement can be tested by the autoclave expansion test of Portiand cement ASTM C151 (24). 

Other Processes. Other methods iaclude reaction of lime, (CaO) with hydrogen cyanide (24) and reaction of limestone, (CaCO ), with ammonia (25). 

Cement and concrete are used in construction on an enormous scale, equalled only by structural steel, brick and wood. Cement is a mixture of a combination of lime (CaO), silica (SiOj) and alumina (AI2O3), which sets when mixed with water. Concrete is sand and stones (aggregate) held together by a cement. Table 15.4 summarises the most important facts. 

The nature of chemical coagulants are such that the macrofloc may possess certain charges for example lime (CaO), alum (A1203) and flocculating polyvalent cations cany positive charges, which interact with proteins. The interactions are simply illustrated in Figure 7.6. 

Calcium Oxide (lime, Quicklime, Burnt Lime, Calx, Unslaked Lime, Fluxing Lime). CaO, mw 56.08, white or greyish-white lumps or powd, mp 2580°, bp 2850°, d 3.25-3.40g/cc. SI sol in w with formation of calcium hydroxide and evolution of large amts of heat sol in acids, and insol in ethanol. Coml prepn consists of heating calcium carbonate in kilns at 1000—1100° until all of the C02 is driven off. Lab prepn is by burning calcium carbonate or calcium oxalate at about 800° using a quartz crucible in an electric furnace... 

Moisture absorbents or desiccants are required. These are spread on trays and distributed throughout the boiler, so that circulating air passes over them. Quick lime (CaO) is used at 8 to 10 lb for every 1,000 lb/hr of steaming capacity. Alternatively, silica gel is used at 4 to 6 lb per 1,000 lb of steaming capacity. 

Equation applies to individual substances. To see how these equations affect A.S for a chemical reaction, consider the decomposition of limestone (CaC03) to produce lime (CaO), carried out industrially in kilns in which the partial pressure of CO2 is different from 1 bar CaC03(5 ) CaO (.S ) + C02(g)... 

Preparation. Industrially, cobalt is normally produced as a by-product from the production of copper, nickel and lead. The ore is roasted to form a mixture of metals and metal oxides. Treatment with sulphuric acid leaves metallic copper as a residue and dissolves out iron, cobalt and nickel as the sulphates. Iron is separated by precipitation with lime (CaO) while cobalt is produced as the hydroxide by precipitation with sodium hypochlorite. The trihydroxide Co(OH)3 is heated to form the oxide and then reduced with carbon (as charcoal) to form cobalt metal. 

One of the most important discoveries in the history of the chemical industry in Ontario was accidental. Thomas Carbide Willson (1860-1915) was trying to make the element calcium from lime, CaO, by beating tbe lime with coal tar. Instead, he made the compound calcium carbide, CaC2. This compound reacts with water to form a precipitate of calcium hydroxide and gaseous ethyne (acetylene). Willson s discovery led to the large-scale use of ethyne in numerous applications. 

Calcium - the atomic mmiber is 20 and the chemical symbol is Ca. The name derives from the Latin calx for lime (CaO) or limestone (CaCOj) in which it was foimd. It was first isolated by the British chemist Humphry Davy in 1808 with help from the Swedish chemist Jons Jacob Berzelius and the Swedish court physician M.M. af Pontin, who had prepared calcimn amalgam. 

Calcium hydroxide [Ca (OH) ] is known as slaked or hydrated lime and is formed by exposing calcium oxide to water. Slaked lime is less caustic than quick lime. Therefore, it is used to line football fields. (Unslaked lime, CaO, is very caustic when wet, and if it is used on playing fields, players may receive caustic burns.) Calcium hydroxide has many uses, including as an ingredient for stonemasons mortar, cements, whitewash, and soil conditioner (high pH), as a food additive, and as a human depilatory. 

Neutralize with agricultural lime (CaO), crushed Limestone (CaC03), or sodium bicarbonate (NaHC03). 

Common (dry) cement consists of anhydrous crystalline calcium silicates (the major ones being tricalcium silicate, CasSiOs, and (3-dicalcium silicate, Ca2Si04), lime (CaO, 60%), and alumina (a complex aluminum silicate, 5%). While cement is widely used and has been studied in good detail, its structure and the process whereby it is formed are not completely known. This is due to at least two factors. First, its three-dimensional arrangement of various... 

Exhaust gases are treated to minimize SO2 emissions into the atmosphere. Removal of SO2 is achieved by the utilization of a scrubber system and will be discussed below in greater detail. Although numerous variations of both wet and dry scrubbers are commercially available, most rely on the adsorption of S02 onto A1-, Na-, or Ca-based adsorbents. Ca-based adsorbents, such as lime (CaO) or calcite (CaC03), are usually preferred due to their low cost and high availability. 

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