PURPOSE: To enable the adjustment of a slaking speed at a stable temp. by adopting a construction hating no in-furnace insertion parts for the raw material charging pipe of the prescribed furnace and adopting a structure, such as double structures, for the rotating sealing part of an ore discharging machine.

CONSTITUTION: The vertical type lime calcination furnace having a waste gas passage 7, calcination zone 4, etc., is produced by forming the raw material charging pipe 1 into the construction having no in-furnace insertion parts, forming the rotating sealing part of the ore discharging machine section 5 into the double structures, providing a damper 9 in a chuting section 6 and disposing a piping 10 for cooling having an adjusting mechanism for the quantity of the air to be blown in the ore discharging machine section 5. Shells, such as scallop shells and oyster shells, adjusted to 2 to 60mm grain sizes are charged from the charging pipe 1 and are deposited temporarily in a rack part 3; thereafter, the shells are dropped successively to the calcination zone 4. The shells are then calcined at 1050 to 1250°C to obtain the shell quick lime; thereafter, this quick lime is cooled while the cooling rate is adjusted by blowing air from the piping 10 for cooling of the ore discharging machine section 5, by which the shell quick lime is produced.