Effect of MgO Content on Heat Capacity of Synthetic BF Slag and Heat Release Behavior during Cooling Process

Yanhua Yang,Ting Lei,Yuelin Qin

doi:10.3390/met11081294

Abstract

The differential scanning calorimetry (DSC) sapphire analysis was used to measure the specific heat capacity of the BF (BF) slag and observe the CaO-SiO2-MgO-Al2O3-TiO2 5-element slag system with the binary basicity fixed at 1.17. The specific heat capacity of the BF slag and the cooling heat distribution were obtained during the cooling process when the MgO content changing from 7% to 11%. The results showed that the heat released of BF slag was more than 1.2 GJ/ton during the cooling process from 1400 °C to 35 °C, of which the sensible heat was dominant. At MgO content of 9%, the latent heat of crystallization is maximum. The cooling and heat release law of BF slag is directly associated with the phase precipitated in slag cooling and micromorphology.

Highlights

BF slag is the most important solid waste in the ironmaking process, and its annual emission exceeds 200 million tons per year
It is necessary to clarify the basic data of thermophysical properties of BF slag in different states, such as specific heat capacity, heat release law during the cooling process
· PSample − PBaseline PSapphire − PBaseline where m refers to mass, Cp refers to specific heat capacity (J g−1 ◦C−1), and P refers to heat flow, differential scanning calorimetry (DSC) signal after deducting baseline in relative coordinates (m·W)

Summary

Introduction

BF slag is the most important solid waste in the ironmaking process, and its annual emission exceeds 200 million tons per year. BF slag has dual properties, namely, the source of energy and material resources, and the heat contained is a kind of high-quality energy, the material is important raw materials for cement production. After high-temperature slag particles are obtained on the basis of dry granulation, researchers study physical and chemical recovery methods around the waste heat recovery of high-temperature slag particles [14,15]. No matter which way is used to recover waste heat, the heat release law of the BF slag must be defined in the cooling process, realizing the quantity and quality of waste heat. It is necessary to clarify the basic data of thermophysical properties of BF slag in different states, such as specific heat capacity, heat release law during the cooling process. Where m refers to mass (mg), Cp refers to specific heat capacity (J g−1 ◦C−1), and P refers to heat flow, DSC signal after deducting baseline in relative coordinates (m·W)

Experimental Scheme

DSC Curves of BF Slag with Different Contents of MgO

Results and Discussion

Conclusions