# Experimental

## The Interface Model Calculation of CaO-SiO2-Al2O3-MgO Slag System

It was inevitable to study the surface tension and interfacial tension of slag interface when studying the interface reaction of slag. Butler equation was a surface tension calculation equation, which was based on surface energy and chemical potential. Butler equation has been widely used not only in the calculation of the surface tension between slag and melt but also in the change of internal and surface concentration. At the same time, the Girifalco-Good equation has been widely used in the calculation of interfacial tension. The basic mathematical expressions of both equations were as follows [7-10]:

The calculation model of this paper was calculated by using Butler and Girifalco-Good equations in order to analyze the variation trend of the surface tension of CaO-SiO_{2}-Al_{2}O_{3}-MgO slag system.

## Simulation of Melting Behavior

### Effect of Different Basicity on Melting of Slag

The Multiphase Equilibrium of different basicity (CaO/SiO_{2}) and temperature in CaO-SiO_{2}-Al_{2}O_{3}-MgO slag system was calculated by using the FactSage. Fixing base slag Al_{2}O_{3} = 15%, MgO = 8% and basicity variation range was 1.05-1.25 in experiment. The specific experimental program is showed in the following Table 1.

### The Trace Components Influence on Slag Melting

In order to understand the trace components effect on the melting temperature of molten slag, the influence of various trace components on melting temperature were studied and analyzed.

The experimental method of section “Effect of Different Basicity on Melting of Slag” was used to calculate the melting temperature and total melting temperature of the slag by using the FactSage so that the effect of melting temperature under different conditions was obtained. All base slag compositions were showed in Table 2.