Civil Engineering - Building Materials - Discussion

What is the difference between fat and quick lime?

@Jay, calcination is the process by which we can get quick lime(CaO) from its combined state (Ore) i.e. from CaCO3. If CaCO3 is burned( calcined) at a temperature of 900°c we will get.

CaCO3 ---> calcination@900°C-------> CaO + CO2.

Quicklime is correct.

Types of quicklime (CaO+impurities in the form of clay etc)-

1. Rich lime/fat lime/white lime- The quicklime in which 95% to 100% pure lime (CaO), 0-5% impurity.
2. Hydraulic lime- The quicklime in which 70 to 95% pure lime (CaO), 5-30% impurity.
3. Poor lime/Lean lime- the quicklime in which up to 70% (CaO), more than 30% impurity.

Quick lime is obtain from calcination of pure lime.

caco3 -> cao + co2.

Here cao is called quick lime which slacks with water gives fat lime.

cao + H20 -> ca(oH)2 (slacking).

Here ca (oH) 2 is called fate lime or white lime.

Fat lime contains 95% of calcium oxide. So fat lime is the answer.

Quick lime is correct as it is capable of slacking with water and the major part is calcium oxide and minor magnesium oxide.

Yes, Quick lime is correct Major part is calcium oxide which is quick to react with H2O and cause slacking.

Behavior of slaking:.

Fat lime slakes rapidly when water is added giving out considerable heat and making hissing and cracking noise and increases 2 to 3 times its original volume. Fat lime if exposed to air, it absorbs moisture and CO2 from the atmosphere and becomes inert CaCO3 or chalk again and loses its cementing power. For developing the cementing power, quick lime must be slaked with water as early as possible, after it is obtained from the kiln.

What is calcination?

Calcination is process when cao react with water forms ca(oh2).