Effect of Boron Iron Concentrate on the Strength of Preheated Iron Ore Pellets

Pellet is one of the important feeds to iron blast furnace and increased proportion of the pellet is used around the world. Pellet production is cleaner than sinter and its uniform properties allow stable blast furnace operations. Boron iron concentrate is a by-product during production of boron and contains approximately 54% Fe, 3–6% B₂O₃, and 10% MgO. B₂O₃ can form liquid binding phase inside the pellet at relatively lower temperature which reduces the fuel and refractory consumption during the pellet production. MgO can reduce the reduction expansion rate of the pellets. Effects of boron iron concentrate, preheating temperature, and time on the strength of the preheated pellet have been investigated. It was found that the compressive strength of the preheated pellet with addition of boron iron concentrate was increased with increasing preheating temperature and time. When the pellets were preheated at 1030 °C for 25 min, the strength of the pellets with 50% boron iron concentrate can reach more than 600 N/P. The optimized parameters can significantly increase the strength of the pellet and reduce the loop formation of the rotary kiln.