Effect of Ternary Basicity of Iron Ore-Fluxed Pellets on Melting and Softening Properties in a Blast Furnace

Abstract

The cohesive zone is a region of low permeability in a blast furnace. This study shows the impact of the chemical composition of pellets on the metallurgical processes occurring in this region during the iron ore reduction process. Sixteen pellets containing varying contents of MgO, CaO, and SiO2 were investigated. The results indicate that increasing the MgO content of pellets improves their high-temperature properties; e.g., reduction degree and softening temperature. Modern equipment was used to replicate the phenomena that occur in the cohesive zone to measure the softening temperature, pressure drop, and the reduction degree of pellets at elevated temperatures and different pellet basicities. These experimental results were used to develop mathematical correlations between parameters related to high-temperature properties and the ternary basicity of the pellets ((CaO + MgO)/SiO2). Defining such relationships will facilitate evaluating the effects of pellet chemical composition on blast furnace processes.

Estimation of Iron Ore Pellet Softening in a Blast Furnace with Computational Thermodynamics

“…When compared to studies by other researchers, no major contradictions were seen. Silva et al [3] studied sixteen pellets containing varying contents of MgO, CaO and SiO 2 . They concluded that increasing the pellets' MgO content leads to a higher softening temperature.…”

“…The cohesive zone is an area where ore starts to soften and melt; it has the highest resistance to gas flow, which leads to a high pressure drop over the cohesive zone. A narrow cohesive zone enables a smaller pressure drop and is favourable for BF operation [3].…”

Performance Optimization and Efficient Application of Highly Reactive Iron Coke: Research Progress and Future Trend

“…The melting-dropping properties of the charge directly determine the permeability of the blast furnace, thus affecting the fuel consumption and smelting efficiency in the blast furnace. [111][112][113] Therefore, the investigation of the effect of iron coke on the melting-dropping properties of the charge can provide a theoretical basis for the actual use of iron coke in the blast furnace. The melting-dropping properties of the charge mainly include softening property, melting property, dropping property, permeability, etc.…”

Effect of SiO₂ on the Softening-Melting and Dropping Behavior of Magnesia Flux Pellets

“…It can be seen that MgO can improve the softening-melting property, while SiO 2 has the opposite effect. Silva et al 21) studied 16 pellets and analyzed the role of CaO and MgO in the pellets. The results showed that CaO and MgO promote the formation of dicalcium silicate and wustite and improve the melting point of the slag phase.…”