Magnesium limes

MgC03 + Ca(OH)2 -> Mg(OH)2 + CaC03 magnesium lime magnesium calcium... 

Other methods for analyzing combustion products can be substituted for chromatography. Gravimetry can be used, for example, after a series of absorption on different beds, as in the case of water absorption in magnesium perchlorate or CO2 in soda lime infra-red spectrometry can be used for the detection of CO2 and water. 

In the case of lubricant detergents, the hydrophilic or polar part is a metallic salt (calcium, magnesium) and at the center of the micelle it is possible to store a reserve of a metal base (lime or magnesia) the detergent will be able therefore to neutralize the acids produced by oxidation of the oil as soon as they are created. 

For temporary hardness due to magnesium carbonate, more lime is required, since the magnesium precipitates as the hydroxide (less soluble than the carbonate) ... 

It is thus important to determine the relative amounts of calcium and magnesium, for addition of too much lime means that calcium ions are reintroduced into the water, i.e. it becomes hard again, the hardness being permanent. 

Brine Preparation. Sodium chloride solutions are occasionally available naturally but they are more often obtained by solution mining of salt deposits. Raw, near-saturated brines containing low concentrations of impurities such as magnesium and calcium salts, are purified to prevent scaling of processing equipment and contamination of the product. Some brines also contain significant amounts of sulfates (see Chemicals FROMBRINe). Brine is usually purified by a lime—soda treatment where the magnesium is precipitated with milk of lime (Ca(OH)2) and the calcium precipitated with soda ash. After separation from the precipitated impurities, the brine is sent to the ammonia absorbers. 

The term lime also has a broad coimotation and frequently is used in referring to limestone. According to precise definition, lime can only be a burned form quicklime, hydrated lime, or hydraiflic lime. These products are oxides or hydroxides of calcium and magnesium, except hydraiflic types in which the CaO and MgO are chemically combined with impurities. The oxide is converted to a hydroxide by slaking, an exothermic reaction in which the water combines chemically with the lime. These reversible reactions for both high calcium and dolomitic types are Quicklime... 

Mir-slaked lime contains various proportions of the oxides, hydroxides, and carbonates of calcium and magnesium which result from excessive exposure of quicklime to air that vitiates its quaUty. It is partially or largely decomposed quicklime that has become hydrated and carbonated. 

Thermal Properties. Because all limestone is converted to an oxide before fusion or melting occurs, the only melting point appHcable is that of quicklime. These values are 2570°C for CaO and 2800°C for MgO. Boiling point values for CaO are 2850°C and for MgO 3600°C. The mean specific heats for limestones and limes gradually ascend as temperatures increase from 0 to 1000°C. The ranges are as follows high calcium limestone, 0.19—0.26 dolomitic quicklime, 0.19—0.294 dolomitic limestone, 0.206—0.264 magnesium oxide, 0.199—0.303 and calcium oxide, 0.175—0.286. 

Miscellaneous. Both whiting and hydrated lime are used as diluents and carriers of pesticides, such as lime—sulfur sprays, Bordeaux, calcium arsenate, etc. The most widely used bleach and sterilizer, high test calcium hypochlorite, is made by interacting lime and chlorine (see Bleaching AGENTS). Calcium and magnesium salts, such as dicalcium phosphate, magnesium chloride, lithium salts, etc, are made directly from calcific and dolomitic lime and limestone. 

Recovery from Brines. Natural lithium brines are predominately chloride brines varying widely in composition. The economical recovery of lithium from such sources depends not only on the lithium content but on the concentration of interfering ions, especially calcium and magnesium. If the magnesium content is low, its removal by lime precipitation is feasible. Location and avadabiHty of solar evaporation (qv) are also important factors. 

In preparation of MgCl2 from seawater, magnesium hydroxide, Mg(OH)2, is first precipitated from seawater by the addition of dolime or lime. This is then treated with hydrochloric acid to produce a neutralized magnesium chloride solution. The solution obtained is evaporated and converted into soHd magnesium chloride hexahydrate (60,61). 

Manufacture and Processing. Most commercial-grade magnesium hydroxide is obtained from seawater or brine using lime or dolomitic... 

The lower equivalent weight of magnesium hydroxide compared to caustic soda, hydrated lime, and soda ash reduces the stoichiometric amounts necessary to neutralize a given amount of acid. Depending on relative alkah costs, magnesium hydroxide can offer the advantage of lower chemical costs. 

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