PRODUCTION OF SAND FROM GRANULATED BLAST FURNACE SLAG

PROBLEM TO BE SOLVED: To obtain sands having excellent quality equal to or more than the quality of natural sands by crushing a granulated blast furnace slag raw material having a specified apparent specific gravity and a specified coarse grain ratio, then grinding the crushed raw materials while rubbing them with each other, drying the resulting grains and classifying. SOLUTION: The granulated blast furnace slag, which is obtained by cooling molten slag discharged from a blast furnace with water and has an apparent specific gravity of >=2.6, preferably >=2.7 and a ratio of coarse grains of 3.0 to 3.9, is used as the raw material, and the raw material is crushed. The crushed raw materials are ground while rubbing them with each other. At this time, the grinding processing is preferably carried out under the wet condition such that the water content of the raw material is 3 to 5 wt.%. The water content of the ground raw material is controlled to be not more than 0.2 wt.%. The classification of the grains having grain sizes of >=1.2 mm is carried out using a vibrating screen, and the classification of the grains having grain sizes of