Abstract
Slag beads with different crystal content could be obtained through the gas quenching blast furnace slag (BFS) process. In order to increase the additional value of the slag beads as much as possible, it was necessary to restrain the crystallization of the slag beads as much as possible. In this paper, the mineral types and crystallization temperatures of BFS with different basicities and cooling rates were studied by using Factsage thermodynamic software, XRD, and differential scanning calorimeter (DSC) experiments, which obtained the gas quenching temperature and the cooling rate needed to restrain crystallization behavior in the gas quenching process; The crystallization mechanism was studied by calculating crystallization activation energy (Ec) using the DSC experiment, at the same time, the thermodynamic results were verified. The proper basicity and cooling rate of BFS were found to be conducive to the preparation of amorphous slag beads. The results showed that the initial crystallization temperature decreased with decreasing the basicity and increasing the cooling rate, which could increase the amorphous content of slag beads in the gas quenching process. The crystallization activation energy (Ec) increased with decreasing basicity, which increased the crystallization barrier.
Highlights
Blast furnace slag (BFS) is a type of by-product produced in the process of iron-making production, whose use has always been a matter of concern to the metallurgical sector
The degree of amorphousness of BFS is mainly affected by its components, so the effect of different slag components on crystallization behavior was studied by adding different conditioning agents, and the component structure conducive to the preparation of amorphous slag beads was studied
When the basicity decreased to 1.0 in Figure 4b, the precipitation phase was almost amorphous phase when the samples cooled to 1150 °C, and when the temperature continued to decrease to 1100 °C, the melilite phase began to precipitate; when the temperature decreased to 1000 °C, a large amount of crystallization phase was precipitated in the BFS, and the main crystallization phase was the melilite and the anothite
Summary
Blast furnace slag (BFS) is a type of by-product produced in the process of iron-making production, whose use has always been a matter of concern to the metallurgical sector. It is necessary to study the crystallization behavior of BFS and to restrain the crystallization of BFS to obtain high-content amorphous slag beads. The degree of amorphousness of BFS is mainly affected by its components, so the effect of different slag components on crystallization behavior was studied by adding different conditioning agents, and the component structure conducive to the preparation of amorphous slag beads was studied. Fredericci [10] has studied the crystallization process of BFS and the crystalline phase and crystallization peak were verified after heat treatment. Has studied the capability of the blast furnace slag to be vitrified and calculated the crystallization activation energy and the Avrami exponent. The crystallization activation energy were calculated through DSC experiment to study the crystallization mechanism of BFS, which further verified the thermodynamic results
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