Effectiveness of Jet Milling for Producing Superfine Powders from Blast-Furnace Slag

The paper examines the effect of ball (drum) grinding and jet milling on the particle size distribution and specific surface area of the powders produced from blast-furnace slag. The effectiveness of jet milling, providing relatively equal powder particles (more than 85% of the fractions is 0–10 μm in size), is shown. Decrease in the average particle size leads to greater specific surface area of the powder and to a sharp increase in activity (strength of the samples prepared with use of blastfurnace slag). Hydraulic activity σ ≥ 30 MPa can be reached by the powder produced from slag with an average particle size to 12 μm and specific surface area S = 0.6–0.8 m2/g, which increases the sample strength. The strength of cemented compositions based on blast-furnace slag can be improved to 40–43 MPa by adding 15–20% Portland cement to the starting mixture.