Lime

- If you are trying the common French, you see Lime (France).

lime it is in material from construction (but also with others it uses) famous the antiquity since

The lime is introduced in two shapes distinguished:

Index

History

Already i and i before they had learned to use the lime like material from construction, stirred with the sand to form malta. Inizialmete used in the aerial lime shape (that it hardens alone if to contact with air) came subsequently mischiata with clay pieces cotta(vasellame, mattoni etc.) or with pozzolana a rich sand of silice that of it alter the characteristics of resistance, impermeability and above all of it concurs taken also in atmospheres the not with contact with air (typically sott' water). The hydraulic lime was born therefore. In 1850 English John Smeaton it discovered that some argillaceous or silicee limestone marls contain to their inner impurità; from these minerals the natural hydraulic lime in how much can be obtained contains already the characteristics of idraulicità without the added one of external parts. , in its work De architectura of it it describes the production beginning from stones white women, cooked in I affixed furnaces to you where forgiveness weight (today we know in consequence of the liberation of ). The obtained material, the lime alive, was then extinguished throwing it in appropriate full bathtubs of .

Preparation

The raw materials for the production of the lime is limestone, one sedimentaria cliff rich of (CaCO3 ) that it comes extracted from appropriate hollow. they are historically and geologically rich in so far as. It can be used also or other minerals.
The material, roughly crushed, is introduced in affixed furnaces to you or furnaces where it comes heated to 500-1000° for tens of hours. In this phase a chemical reaction happens that door to the liberation of and production of lime oxide:

CaCO3 -> CaO + CO2

After the baking the stone fragments reduce their weight of approximately a third party because of the atoms of and lost, and they assume one porosa consistency. They constitute the lime alive that, commercialized therefore com' or is reduced in powder, it must be conserved in perfectly watertight containers, since are much hygroscopic one.

In order to obtain the definitive lime, or extinguished lime, the material comes dipped in full water bathtubs where a idratazione reaction happens, accompanied from a violent release of heat that crushes stones (the procedure is said extinction):

CaO + H2Or -> Ca(OH)2

The material that has not reacted during the baking remains on the bottom of the bathtub, while the lime in suspension (grassello of lime) it comes captured for means of a channel communicating with one bathtub of collection. An obtained watery mixture can be used endured in yard or can be packed in watertight bags and be conserved for years. The water that is separated from the mixture is said latte of lime.

hydraulic lime rich limestone cliff is prepared beginning from of silicati and composed of the aluminum and magnesium.
The name derives from the fact that, difference of the normal lime, is in a position to making taken in little hours also to contact with the water.

Carbonatazione

To difference of concrete that it begins the taken one to the first contact with the water, the lime can be conserved in water for years.
The taken one begins instead with the removal of the water and the successive drying. That renders it for the applications to contact with the water (bridges unusable, wharves), but it renders it preferibile to the concrete where the drying happens quickly, like in the application of . The concrete in fact would not have instead to dry before that the taken phase is finished of.

Once that the lime essiccata, to contact with present carbon dioxide in it begins a slow process that transforms it in limestone (carbonatazione), the original compound from which it has been produced. The reaction is:

Ca(OH)2 + CO2 -> Ca(CO3) + H2Or

Even if the previous reaction is corrected from the formal point of view, the real reaction is more complex. Observing the previous reaction in fact, the process would seem to happen between a solid Ca(OH)2 and one gas CO2, while in truth the reaction happens in watery phase thanks to the water of paste of the lime.

The idrossido of soccer in fact is melted in water, thanks to a good solubility, the carbon dioxide melts anch' it in water, forming one species indicated like carbonic acid H2CO3, from which for reaction acid base form yourself knows them little soluble, that is the soccer carbonate. The correct shape is therefore:

Ca2+ + 2OH- + 2H+ +CO32- -> Ca(CO3) + 2 H2Or

It employs

The lime alive is used:

  • for dealing waters in order to reduce the acidity
  • in the depurazione in order to remove phosphates and other impurità (flocculante) and for desolforizzare exhaust gaseses
  • in the fabrication of in order to dissolve fibers of
  • like turning white candeggiante and
  • in order to disinfect atmospheres
  • in in order to correct lands acids
  • in chemistry it is used in order to purify and , like essiccante and absorber of

The extinguished lime is used:

  • like material from construction joined to the sand (stabilitura)
  • stirred to concrete in order to produce a malta plastic adapted for the intonaci
  • in tannery of skins
  • inpetrochemical industry in order to produce it points out to you for lubricating
  • for the production of stereato of soccer
  • for the neutralization and the absorption of
  • for the treatment of the water used in the food industry
  • in order to correct the acidity of lands
  • in agriculture, joined to branch sulfate it is used like fungicide (bordolese mixture)
  • in the druggist industry in order to prepare it knows them of soccer and magnesium

Emergency

The lime, and particularly that one lives, introduces one strongly alkalinity and causticità. The contact with the skin with anhydrous oxide can provoke serious ustioni as it happens with hard caustic. The contact with little water (not sufficient to absorb the produced heat) can provoke one violent boiling and the projection of caustic sketches and hot.
for these reasons it is important to use gloves and it glances at them protected to you when handlings the lime, is solid that in solution, it is the malta of lime.

The ingestion of idrossido of soccer can provoke serious symptoms, between which respiratory difficulty, gastrointestinal hemorrhages, hypotension and dangerous alterations in of .

 

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