PURPOSE: To reduce the degree of wear and tear of a grate and to obtain quick lime excellent in the burning degree by supplying limestone wherein coke breeze is added and moisture is regulated to a calcination equipment equipped with the grate and calcining limestone while sucking air at low negative pressure.

CONSTITUTION: The mixed material M is obtained by adding coke breeze C to limestone having 4-15mm particle diameter and adding water by a drum washer 3 to regulate moisture. Then the material M is supplied on the grate 10A of a calcination equipment via a PH hopper 7 so that the thickness is regulated to 300-700mm. A pilot burner 9 is fired and also the mixed material M is burned by sucking air at low negative pressure of -80 to -120mmAg. Quick lime is obtained by calcining limestone without rolling the material M. Then this quick lime is sifted by a product screen 17. Oversize quick lime M' is returned to the inlet side of a preheater via a carrier line 18 and supplied to a sole hopper 19 provided before the hopper 7 and spread on the upper face of the grate 10A. The material M is supplied thereon. Quick lime M" passed through the screen 17 is sent to a pneumatic carrier tank via a product tank 13.