Molecular Dynamics Study of Structural Properties of Refining Slag with Various CaO/Al2O3 Ratios

Hongxuan Zhao,Wei Liu,Shufeng Yang,Jie Liu,Jingshe Li

doi:10.3390/min11040398

Abstract

SiO2-Al2O3-CaO-MgO is the main type of refining slag in a ladle furnace. Here the effects of the CaO/Al2O3 mass ratio on the structural properties of the refining slag system are studied by molecular dynamics simulations. The pair distribution function, coordination number, micro-structure unit and diffusion capacity were analyzed. An increase in the CaO/Al2O3 ratio did not change the bond lengths of these units. However, an increase of the CaO/Al2O3 ratio caused more charge compensators to be introduced into the refining slag system, which led to conversion of free oxygen and non-bridging oxygen to tricluster oxygen and bridging oxygen in the system. Moreover, this augmented the content of relatively stable 4- and 5-coordinate Al. As the micro-structure of the system became more complex, the overall diffusion capacity of the refining slag became poorer. In the micro-structure, the diffusion capabilities of different atoms decreased in the following order: Mg > Ca > O > Al > Si.

Highlights

Developments in industry and civil engineering have placed higher requirements on steel quality [1,2]
Yu et al studied the desulfurization ability of refining slag with medium basicity. They found that SiO2-CaO-MgO-Al2O3 system slag with a basicity of approximately 3.5–5.0 and Al2O3 content of approximately 20 wt% has strong desulfurization ability, which meets the requirements of High Strength Low Alloys (HSLA) steel [10]
The pair distribution function (PDF) shows that the bond lengths of Ca-O and Mg-O were approximately 2.344 and 1.969 Å, respectively

Summary

Introduction

Developments in industry and civil engineering have placed higher requirements on steel quality [1,2]. The composition of refining slags must be adjusted. By adjusting the contents of CaO and SiO2 in the refining slag, the basicity of the refining slag can be accurately controlled. Yu et al studied the desulfurization ability of refining slag with medium basicity. They found that SiO2-CaO-MgO-Al2O3 system slag with a basicity of approximately 3.5–5.0 and Al2O3 content of approximately 20 wt% has strong desulfurization ability, which meets the requirements of High Strength Low Alloys (HSLA) steel [10]. Al2O3 in the refining slag can effectively adjust the melting point of the CaO-SiO2-Al2O3 ternary slag system, such that the refining slag is in a low melting point region [11]

Methods

Results

Conclusion