Effect of Unburned Pulverized Coal on the Melting Characteristics and Fluidity of Blast Furnace Slag

Dongwen Xiang,Xin Jiang,Fengman Shen,Haiyan Zheng,Qiangjian Gao

doi:10.3390/cryst11060579

Abstract

A substantial amount of attention has been paid to viscosity due to its substantial effect on the fluid dynamics of molten blast furnace slag and slag metal reaction kinetics during the pyrometallurgy process. To clarify the influence mechanism of unburned pulverized coal (UPC) on blast furnace (BF) slag viscosity, the effects of different contents of UPC on the BF slag viscosity, free-running temperature and viscous flow activation energy were investigated. The slag viscosity was measured by the rotating cylinder method, and the microstructure of the cooled slag was observed by SEM. As a result, the main reason for a change in the slag viscosity, free-running temperature and viscous flow activation energy was that the UPC entering the slag formed a large number of white particles that predominantly comprised deposited carbon and a high melting point solid solution. In addition, the disintegration or polymerization of the SixOyz- structure was also a contributing factor. When the content of the UPC was 0.6%, the free-running temperature and viscous flow activation energy of slag were 1623 K and 120.969 kJ/mol, respectively, which are lower than those of the slag without UPC. However, the free-running temperature and viscous flow activation energy increased to 1668 K and 286.625 kJ/mol, respectively, when the content of UPC increased to 4%, which are higher than those of slag without UPC.

Highlights

It is widely known that the development of pulverized coal injection (PCI) technology is of revolutionary significance for modern blast furnace (BF) ironmaking
Ning et al [2] investigated the catalytic behavior of alkali vapor on unburned pulverized coal (UPC) prepared from bituminous coal, anthracite, semi coke and coke, and the results showed that the alkali metal vapor had a catalytic effect on the gasification reaction of UPC
The above results illustrate that the UPC can dilute the slag viscosity when its content is low; that is, a low UPC content can reduce the slag viscosity

Summary

Introduction

It is widely known that the development of pulverized coal injection (PCI) technology is of revolutionary significance for modern BF ironmaking. Due to the increasing depletion of coking coal resources and the rising price of metallurgical coke, the production cost of steel enterprises is increasing [2]. Ning et al [2] investigated the catalytic behavior of alkali vapor on UPC prepared from bituminous coal, anthracite, semi coke and coke, and the results showed that the alkali metal vapor had a catalytic effect on the gasification reaction of UPC. The research results of Liang et al [18] showed that a small amount of UPC can decrease the viscosity and melting temperature of BF slag. The mechanism of the effect of UPC on the BF slag viscosity is revealed by using slag ionic theory and phase diagram theory

Materials

Experimental Equipment and Methods

Results and Discussion

Theoretical Analysis