The reaction ${\mathrm{CaCO}}_3\left(\mathrm{s}\right)\rightleftharpoons \mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$ goes to completion in lime kiln because

of the high temperature.

CO₂ escapes continuously

CaO is not dissociated

$\mathrm{CaO}\text{ is more stable than }{\mathrm{CaCO}}_3$