ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Fundamentals of High Temperature Processes
Dissolution Kinetics of Synthetic FeCr2O4 in CaO–MgO–Al2O3–SiO2 Slag
Kangji WeiLijun Wang Shiyuan LiuXiaobo HeYiyu XiaoKuochih Chou
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2022 Volume 62 Issue 4 Pages 617-625

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Abstract

Cleaner production of alloys is of great significance to the protection of the ecological environment. At present, it has received widespread attention all over the world. Chromite smelting reduction direct alloying is an important production process in the production of stainless steel, which can make full use of chromite resources, thereby reducing production costs and preventing environmental damage caused by traditional processes. In order to reveal the dissolution mechanism of chromite ore, pure phase of synthetic FeCr2O4, the main component of chromite ore, was used to replace the real chromite with a complex composition and the dissolution process of it was investigated. The effects of basicity (w(CaO) + w(MgO)/w(SiO2) + w(Al2O3)), Al2O3 content and temperature on the dissolution of FeCr2O4 in CaO–MgO–Al2O3–SiO2 refining slag were studied under high purity argon atmosphere. The composition range of the slag sample is 35%–55%SiO2, 15–35%CaO, 10–20%Al2O3 and 10%MgO. The results show that the solubility of FeCr2O4 increases with the decrease of basicity of slag from 1 to 0.54 and then the solubility of FeCr2O4 decreases with the decrease of slag basicity from 0.54 to 0.33. In the low basicity slag (B = 0.54), the solubility of FeCr2O4 will decrease with the increase of w(SiO2)/w(Al2O3) from 2.25 to 5.50. The slag system with the best dissolution is 45% SiO2, 25% CaO, 20% Al2O3 and 10% MgO. The solubility of FeCr2O4 increases with increasing temperature from 1500 to 1600°C. Meanwhile, distribution of elements in interface of FeCr2O4 and slag was analyzed by EDS. During the dissolution process, Fe, Mg and Al elements form a concentration gradient on the surface of the FeCr2O4. The width of the gradient interval is inversely proportional to the reaction time and solubility. The dissolution kinetic of FeCr2O4 was also investigated. The dissolution reaction on the surface of FeCr2O4 was the controlled step in the dissolution process. The activation energy of the dissolution reaction of FeCr2O4 in this slag is 266.05 kJ·mol−1.

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