Study on the Manufacturing of Ultra-Fine Ore Briquettes for Charging in a Sintering Machine

Abstract

In ironmaking, the optimal size of the iron ore charged into a blast furnace is generally 10-30 mm. Oversized ores, which have a smaller reaction surface area, are crushed, while undersized ores, which decrease permeability, undergo a sizing process before being charged into the blast furnace. Recently, however, iron ore has been micronized, and there is less high-quality iron ore. Also, in accordance with the Paris climate change accord, the Republic of Korea must reduce CO2 gas emissions by about 39% before 2030 to conserve the environment. In response, steelmakers have researched a sinter-briquette complex firing process which employs a method of charging where the raw materials are sintered together with briquettes made of ultra-fine ore. Extra heat is needed to sinter the briquettes. If the briquettes are broken during transporting and charging, the sinter bed permeability decreases, which decreases productivity. In this study, briquettes were made by changing manufacturing conditions such as moisture content, feeding speed, and size, and were simulated by changing the pocket depth in a numerical analysis. Consequently, it was determined that the compressive strength of the briquette was highest when moisture in the briquette was 6 wt%, in proportion to feeding speed and large particle size. Briquette density was in inverse proportion to pocket depth, and when the depth was over 15 mm, the briquette was broken in the pocket.