TREATMENT OF BLAST FURNACE SLAG AND APPARATUS THEREOF

PROBLEM TO BE SOLVED: To separately produce crystallized slag grains and glassy slag grains from molten blast furnace slag with a single apparatus. SOLUTION: In producing the blasting fine grains by blasting the gas jet 2 to the molten blast furnace slag S, the high temp. slag grains are rapidly cooled at the vitrified cooling speed or more and formed as the slag grains in the range from the re-fusing lower limit temp. or lower to the crystallized lower limit temp. or higher. Successively, the slag grains are introduced to a heat holding vessel 4 and in the case of producing the crystallized slag grains, the slag grains are held in the temp. range of the crystallized lower limit temp. or higher for >=1 min, and in the case of producing the glassy grains, the slag grains are continuously cooled to the crystallized lower limit temp. or lower at the cooling speed of >=0.3 deg.C/sec by introducing the cooling air into the heat holding vessel 4.