Effects of Fine MgO-Bearing Flux on the Strength of Sinter before and after Low-Temperature Reduction

Abstract

Decreasing the MgO content can improve most of the metallurgical properties of sinter, but the low-temperature reduction disintegration index (RDI) property will be worse. In order to improve the RDI property of sinter under certain MgO contents, the effects of fine MgO-bearing flux on the strength of sintered samples before and after reduction in three systems (Fe 2 O 3 -MgO, Fe 2 O 3 -MgO-CaO, and Fe 2 O 3 -MgO-CaO-SiO 2 ) were investigated in the present work. The experimental results show that (1) in the three systems, the percentage of fine light calcined magnesite (LCM) increases from 0 to 100%, and the compression strength of the samples before reduction increases from 0.140 to 0.187 MPa, from 0.115 to 0.175 MPa, and from 0.121 to 0.164 MPa, respectively. The compression strength of the samples after reduction increases from 0.062 to 0.151 MPa, from 0.100 to 0.156 MPa, and from 0.099 to 0.151 MPa, respectively. (2) The fundamental reason is that the fine powders can increase the specific surface area and the surface energy of the interface. It is beneficial to promoting the mineralization of MgO-bearing flux. More formation of MgO•Fe 2 O 3 may increase the strength of samples before reduction. Less transformation from Fe 2 O 3 to Fe 3 O 4 may increase the strength of samples after reduction. The microstructures of samples are more compact and uniform. Therefore, fine LCM can improve the strength of sinter before and after reduction. The outcomes of the present work can improve the sintering quality by using the fine MgO-bearing flux in the sintering process.

Dual effect of MgO on softing–melting performance of high gangue sinter: changes of slag viscosity and phase composition

“…Sinter is the primary raw material for blast furnaces, its unique chemical composition has emerged as the primary research challenge for enterprise research. Therefore, the effect mechanism of MgO on the softening–melting behaviour of sinter was researched, and the optimum quantity of MgO in sinter was found in order to increase the production of typical long-process iron producing and decrease energy consumption [4].…”

Simulation of the Internal Temperature Field and Flow Field in a Double-Layer Sintering Bed

“…By 2015, the average thickness of the burden bed in iron and steel enterprises was about 720 mm, − which was about 2.5 times higher than that in 1950, and the sinter yield also greatly increased. Of course, a high sinter bed has many advantages in improving sinter production efficiency, but some technical problems are difficult to solve, such as poor permeability of the bed. , It is necessary to reduce the moving speed of the sinter trolley or increase the exhaust volume of the blast to increase the oxygen supply, which will reduce the production efficiency of the sinter and fail to achieve the effect of increasing the sinter yield. Moreover, for some sinter plants, the exhaust volume of the blast has reached the limit, so it is difficult to increase the air volume, and the vertical sintering speed decreases, so it is impossible to increase production.…”