Influence of B2O3 on the thermophysical properties of molten blast furnace slag

Abstract

The thermophysical characteristics of blast furnace molten slags have crucial implications for their smelting process and the subsequent utilization of resources. To efficiently recover molten slag waste heat resources, the thermodynamic properties and viscous flow characteristics of molten blast furnace slag systems with various B2O3 contents were investigated. The stability of the slag at high temperatures was evaluated by calculating its heat capacity and critical heat release. The structural evolution of the melt under varying B2O3 contents was comprehensively studied using Raman spectroscopy and Nuclear Magnetic Resonance. From the perspective of viscous flow characteristics, the impact of B2O3 resulted in a reduction in viscosity of the slag, while the electrical conductivity of the slag increased. Concerning the thermodynamic properties, the break temperature decreased from 1377 °C to 1280 °C with an increase in B2O3 content in the range of 0 to 6 wt.%, while heat capacity and critical heat release of the slag both increased. The introduction of B2O3 facilitated smoother the blast furnace smelting conditions while enhancing the superiority of the granulated product and the efficiency of heat recovery. Adding B2O3 to the molten slag disrupted part of chain structure (Si-O-Si) to create a more flowable cyclic borosilicate structure (Si-O-B).