Influence of SiO2 on the Compressive Strength and Reduction-Melting of Pellets

He Guo,Fengman Shen,Xin Jiang,Xin Zhang,Haiyan Zheng,Qiangjian Gao

doi:10.3390/met9080852

Abstract

The effects of SiO2 content on the compressive strength, reduction behavior and melting-dripping properties of the pellets were investigated under experimental conditions. The experimental results indicated that the compressive strength of pellets gradually decreased with increasing SiO2 content, mainly because the pellets with high SiO2 had poor crystallization capacity, a more liquid phase and more pores. With increasing SiO2 content from 2.19 wt% to 8.13 wt%, the reduction degree of pellets descreased due to the generation of 2FeO·SiO2. Based on the morphology analysis, inside of the pellets, 2FeO·SiO2 caused the compact structure and fewer microspores with increasing SiO2 content, which was unfavorable for the reduction process and resulted in the decrease of the reduction degree. Also, increasing the SiO2 content had negative effects on the melting-dripping properties of pellets. The melting-dripping properties can be improved by adding some sinter with high basicity in the mixed burden. The current work established the relation between SiO2 content and reduction-melting behavior of pellets, which can provide theoretical and technical support for the effective utilization of pellets with different SiO2 content in blast furnace process.

Highlights

Iron-bearing materials should enable the reliable production of hot metal from a balst furnace (BF) or directly reduction iron (DRI) from a shaft furnace, at minimum cost and at a large scale
The particle size of a pellet is relatively uniform, which is favorable for burden permeability in the BF; the pellet iron-grade is higher, which is favorable for effective iron content input in burden column and enhancing production efficiency; the reduction of pellets is easy, which is favorable for increasing gas utilization rate of BF, etc
The reduction degree was 75.22% and 46.19% for 2.19 wt% and 8.13 wt% SiO2 contents in pellets, respectively

Summary

Introduction

Iron-bearing materials should enable the reliable production of hot metal from a balst furnace (BF) or directly reduction iron (DRI) from a shaft furnace, at minimum cost and at a large scale. Acid pellets matching with high basicity sinters are main burden compositions of BF in China. Pellets are a kind of artificial iron ore and have many preferable metallurgical properties. The particle size of a pellet is relatively uniform, which is favorable for burden permeability in the BF; the pellet iron-grade is higher, which is favorable for effective iron content input in burden column and enhancing production efficiency; the reduction of pellets is easy, which is favorable for increasing gas utilization rate of BF, etc. Many references had studied the metallurgical properties of pellets with different chemical compositions and categories [1,2,3,4,5,6,7]

Methods

Results

Conclusion