Burned lime

Qualitative examples abound. Perfect crystals of sodium carbonate, sulfate, or phosphate may be kept for years without efflorescing, although if scratched, they begin to do so immediately. Too strongly heated or burned lime or plaster of Paris takes up the first traces of water only with difficulty. Reactions of this type tend to be autocat-alytic. The initial rate is slow, due to the absence of the necessary linear interface, but the rate accelerates as more and more product is formed. See Refs. 147-153 for other examples. Ruckenstein [154] has discussed a kinetic model based on nucleation theory. There is certainly evidence that patches of product may be present, as in the oxidation of Mo(lOO) surfaces [155], and that surface defects are important [156]. There may be catalysis thus reaction VII-27 is catalyzed by water vapor [157]. A topotactic reaction is one where the product or products retain the external crystalline shape of the reactant crystal [158]. More often, however, there is a complicated morphology with pitting, cracking, and pore formation, as with calcium carbonate [159]. 

Phenol should not be allowed to come into contact with the skin for it causes painful burns. The best antidote for phenol burns is a saturated solution of bromine in glycerine if all undi.ssolved bromine is allowed to settle out before the solution is used, there is no danger of bromine burns. Lime water may also be employed. 

Hard-burned lime is a quicklime that is calcined at high temperature and is generally characterized by relatively high density and moderate-to-low chemical reactivity. 

Both of the above extremes are undesirable for most lime uses. Usually, the objective is to produce a completely calcined but soft-burned lime having no core or no more than 1—2% core. Such limes are more porous and chemically reactive. 

Calcium Oxide. Also called lime or quicklime (4,5), calcium oxide [1305-78-8] (Class 1, nonregenerative), is relatively iaexpensive. It is prepared by roasting calcium carbonate (limestone) and is available ia a soft and a hard form according to the way ia which it was burned. For desiccant service, soft-burned lime should always be used. Calcium oxide is most commonly used to dehydrate Hquids and is most efficient when it can be heated to speed the reaction rate. The reaction product is calcium hydroxide, which cmmbles as it picks up moisture. 

Oyster Shells and Lime Rock Operating characteristics for hammer mills grinding oyster shells and burned lime for agricultural purposes are given in Table 20-30. 

TABLE 20-30 Operating Data for Grinding Oyster Shells and Burned Lime in Hammer Mills... 

Brennerei, /. distillery distillation, distilling plant (for burning lime, etc.) kiln burning (of lime, brick, etc.), -betrieb, m. distillery management or operation, -hefe,/. distillery yeast, -maische, /. distillery mash. 

Sample Inherent Viscosity dl/g %P Oxygen Level for Burn lime of ... 

Instead of roasting the ore in open heaps, the same operation is sometimes performed in kilns, similar to those used for burning lime. In some districte, this method is found more convenient than large open lumps, covering often several hundred square yards. 

Later man started to build with blocks of dried clay. The first (baked) bricks were found in and near the area which is now called the Middle East. Catal Hiiyiik used to be a city on the Anatolia plateau in the centre of Turkey. According to archeologists it probably dates from approximately 8300 BC. For reasons as yet unknown the city was abandoned at around 5600 BC. Its houses had cornerposts of wood and cross beams. The rest of the wall consisted of loam bricks. However, loam has the annoying property that it disintegrates easily in a humid atmosphere. For that reason the houses needed to be repaired after every rainy season. At approximately 8000 BC a people in Jericho built round houses of hand-made loam bricks which were dried in the sun. Around 7500 BC people already knew how to make mortar. They probably heated limestone and mixed the thus formed burned lime with sand and water. In that case the following reactions occur ... 

Two additional sources of lime are noteworthy, especially when a rapid change in soil pH is desired. Calcium oxide (CaO), called quicklime or burned lime, and calcium hydroxide [Ca(OH)2], called hydrated lime, are more irritating to handle, and more expensive, than is limestone, but are sometimes favored by gardeners who desire to adjust soil pH quickly. 

Ground limestone (CaC03) Hydrate lime (Ca(OH)2) Burned lime (CaO) Caustic soda (NaOH) Potassium hydroxide (KOH) Sodium bicarbonate (NaHC03) NH3 (anhydrous) NH4OH (aqueous)... 

Fig.3.29 Burning lime vs speed of wind 421 (5) The effect of the velocity of air...

XI. Eighteen parts of saltpetre, 3 of sulphide of antimony, 10 of sulphur, 4 of burned lime (unslaked). 

Imatra Also called the Solid Lime Process. A method for desulfurizing steel made by an electric arc process. Additions are made of burned lime (calcium oxide), fluorspar (mineral calcium fluoride), and ferro-silicon. 

Calcium oxide, burned lime, quicklime, or simply lime as it is known in industry, is the largest single use for limestone and dolomite [2]. It is obtained by heating (calcining) calcium carbonate to a temperature of 900-1,000°C to cause loss of carbon dioxide (Eq. 7.5, Table 7.1). 

Calcium oxide (burned lime) can be slaked with a theoretical amount of water to form calcium hydroxide (slaked lime) as a white powder, but this must be conducted with care. The highly exothermic reaction can produce sufficiently high temperatures that it could slow the rate of hydration [7] (Eq. 7.6). 

FIGURE 7.4 Cross section through the drum and slurry trough of a drum filter, used for the continuous separation of a solid from a liquid suspension. This version includes a water wash for scavenging the last traces of a solution of value. Sodium hydroxide washings are retained in the process by collecting them separately in the filter and using this to dissolve fresh sodium carbonate, and to slake burned lime. (Modified from Codd et al. with permission [35]). 

The lime kiln in the causticization circuit of the chemical recovery operation for a large kraft mill produces 100 tonnes (1 tonne = 1000 kg) of burned lime (CaO) daily. 

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