Effect of Finely Ground Limestone and Dolomite on Compression Strength and Reduction Swelling of Vanadium-Titanium Pellets.

Hao Liu,Lixiang Yan,Ke Zhang,Yuelin Qin,Shihong Peng,Min Chen,Weiqiang Liu,Wenchao He,Fei Meng

doi:10.3390/ma14164433

Abstract

Vanadium−titanium magnetite (VTM) is an important raw material for ironmaking under the situation of increasingly demanding scarce resources. To further improve the metallurgical properties of pellets, and to satisfy the requirements of blast furnace slag basicity, finely ground dolomite and limestone have been added to the pellet. In this study, the effect of finely ground dolomite and limestone on the metallurgical properties (green pellet drop strength, cold compression strength, reduction swelling index, and microscopic mineral structure) of VTM pellets were investigated. With the addition of finely ground dolomite and limestone, the drop strength of the green pellet was improved. The effect of adding finely ground limestone was greater than adding finely ground dolomite. Adding more finely ground dolomite and limestone compared to pellets without limestone and dolomite, the cold compression strength was decreased, which was attributed to the decomposition of limestone and dolomite during the induration of pellets. With the addition of dolomite, the reduction swelling index (RSI) increased firstly and then decreased. When the basicity of the pellet was 0.54 to 0.94, the slag phase with the lowest melting point was formed, corresponding to the maximum of the reduction swelling index. For the pellets with added limestone, the reduction swelling of the pellets deteriorated. The reduction index of the pellets increased and reached the maximum (26.6%) at a basicity of 1.54, which belongs to abnormal swelling.

Highlights

The results showed that the pellets with the addition of limestone had a better reduction degree compared with the pellets without limestone
Pellet limestone green pellets than for the dolomite green pellets, which indicates that theFigure green pellets with finely ground limestone absorbed more water than the dolomite
−titanium ground limestone green pellets than for the dolomite green pellets, which indicates that powder was poor, and the proportion of particle size less than μm was

Summary

Introduction

The large-scale application of VTM is mainly based on the blast furnace and basic oxygen furnace processes [8]. In this process, VTM is fed into a blast furnace mainly in the form of pellets and sintering ore [9,10]. As one of the iron-bearing burdens of blast furnaces, present many advantages, including excellent metallurgical performance, low energy consumption in the production process, and fewer pollution emissions compared with using sintering ore. To further improve the metallurgical properties of pellets, and to satisfy the requirements of blast furnace slag basicity, some fluxing materials have been added to the pellet. Dolomite (MgCO3 and CaCO3 ) and limestone (CaCO3 ) are the most common additives because of their low cost and abundant reserves [15]

Methods

Results

Conclusion