Carbonation of lime

Dagaonkar MV, Mehra A, Jain R, Heeres HJ (2004) Synthesis of CaC03 nanoparticles by carbonation Of lime solutions in reverse micellar systems. Chem Eng Res Des 82 (11) 1438-1443... 

Karatasios, I., Katsiotis, M.S., Likodimos, V., Kontos, A.I., Papavassiliou, G., Falaras, P. and Kilikoglou, V. (2010) Photo-induced carbonation of lime-Ti02 mortars. Applied Catalysis B Environmental, 95, 78-86. 

In the following year Sir Everard Home interested Mr. Hatchett in the chemical composition of dental enamel (7, 8). Since the tooth of the elephant is composed of three different structures, Sir Everard wished to know whether the materials themselves were different or only differently arranged. Hatchett showed that the enamel was composed of calcium phosphate. The enamel, said he, has been supposed not a phosphate but a carbonate of lime. This error may have arisen from its solubility in acetous acid or distilled vinegar but the effects of the acetous acid are in every respect the same on powdered bone as on the enamel (8). 

Hatchett then investigated the composition of shell and bone. When it is applied to the cuttle-bone of the shops. . . , said he, the term bone is here misapplied. .. for this substance in composition is exactly similar to shell, and consists of various membranes hardened by carbonate of lime, without the smallest mixture of phosphate (8). 

Mr. Hatchett observed that the external skeleton of crustaceans and the egg shells of birds contain more calcium carbonate than calcium phosphate but that in bones the phosphate predominates. It is possible, said he, .. . that some bones may be found composed only of phosphate of lime and that thus shells containing only carbonate of lime and bones containing only phosphate of lime will form the two extremities in the chain.. . . ... 

The only significant production process today is by carbonation of lime slurry, itself obtained by calcination and hydration of a calcium carbonate mineral. The process is set out below and it can be seen that this is another example of using a chemical method to achieve a particle size reduction ... 

Cap.honic Acid exista in the atmosphere os a product of combustion, and of the respiration of animals. Combined with metallic oxides, it forms tire numerous olnss of nativo earthy and metallic carbonates, of which the carbonate of lime is much the most important. 

The reactions which take place in the pot or crucible aro very easy to understand. For example, if the silica has been mixed with carbonate of soda and carbonate of lime, tho silica, at a high temperature, seizes on the soda and lime, and the carbonic acid is disengaged, In the same manner, if silica has been mixed with carbonate of potassa and minium, this last returns to the state of massicot, and the silica then combines with It and the potassa. There is, therefore, in this case, first a disengagement of oxygen, thon an elimination of carbonic acid. 

After its subsidence, the dear liquid is decanted into another receptacle, in which it is boiled out of contact with the rnr, and stirred at the some time by some mechanical arrangement. - This ebullition expels all the volatile fatty impurities which may be present, and, consequently, the liquid loses both color and odor. As soon as the solution arrives at a density of 14s Twad-dell, it is allowed to cool, when the precipitation of a further portion of sulphate of lime occurB. Should an excess of acid be present, as may be known by its action on tincture of litmus, some chalk or powdered limestone must he added fractionally till the liquid is neutral. After this the boiling is continued as before out of contact with air, during which time the contents of tho vessel must be actively stirred, till the solution marks 37-5° Twaddcll. The sulphate and carbonate of lime are now collected on a filter, and the filtrate reduced by evaporation, till,-upon cooling, it marks 49°, care... 

When alumina is combined with the silica, forming a natural clay, a much more compact and fusible compound is formed with the lime than when the silica is alone. Indeed, it has been observed as a general principle, that tire point of fusion is materially affected by the relation and number of bases the whole materials contain thus, a more liquid scoria is obtsined by the addition of a limestone containing magnesia than with a pure limestone. But experience is against the use of a magnesieu limestone, because it deteriorates the iron produced, while the purity of the metal iB the primary consideration. That which contains much silica should also be used sparingly, as silica combines with the iron and injures its quality, -The purest limestones are the most suitable for flux. Common marble is nearly a pnre carbonate of lime but is too rare and expensive to be used as a flux. 

Oolite limestone, which-derives its name from its being composed of small round grains like the roe of a fish, is another excellent and pure carbonate of lime. 

Carbonate of lime Carbonate of magno i, , Oxide of iron aaa aluiujas, A 7Bt... 

This oxide occurs in nature as carbonate, forming immense masses of roclr in various parts of the globe also associated with carbonate of lime under the forms of dolomite and maguosian limestone and as sulphate of magnesia—Epsom salts—occurring in many saline springs. 

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