温度对CaO-SiO2-Al2O3-MgO高炉渣系Al2O3活度的影响

 Al₂O₃作为熔渣中的主要组元之一,其对熔渣的冶金性能的影响尤为突出。对于高炉炼铁而言,高炉渣中Al₂O₃增加会对炼铁及脱硫造成不利影响。然而,随着中国钢铁工业的不断发展,相对低廉的高Al₂O₃进口铁矿石使用量不断攀升,使得高炉渣中Al₂O₃含量明显增加,高炉渣中Al₂O₃质量分数往往大于15%,更高的甚至大于20%。目前关于高Al₂O₃高炉渣系中Al₂O₃组元的热力学性质(例如采用参考渣法测定Al₂O₃的活度)及其对炉渣冶金性能的影响等研究鲜有报道,而温度是影响冶金熔渣冶金性能的重要热力学因素之一,因此探讨温度对冶金熔渣中Al₂O₃组元活度影响的规律不仅具有重要的研究意义,同时也为现场实践提供坚实的理论依据。采用参考渣法对1 773～1 873 K温度条件下CaO-SiO₂-Al₂O₃-MgO高炉渣系Al₂O₃活度进行测定,并采用Raman光谱对熔渣的结构进行检测。考察了温度对CaO-SiO₂-Al₂O₃-MgO高炉渣系Al₂O₃活度的影响。结果表明,随着温度的增加,熔渣中Al₂O₃的化学势降低,熔渣与铜金属熔液之间的反应向右移动来达到新的平衡,因而Al₂O₃的活度随着温度的增加逐渐降低。温度的增加使熔渣中Al₂O₃与碱性金属氧化物发生反应,使钙铝酸盐(CaO·Al₂O₃和CaO·2Al₂O₃)和镁铝酸盐(MgO·Al₂O₃)等复合物生成量增加,此时熔渣的结构由于O2-的增加而逐渐发生解聚,熔渣中的自由Al₂O₃减少,从而导致Al₂O₃活度逐渐降低。

Effect of temperature on Al2O3 activity in CaO-SiO2-Al2O3-MgO blast furnace slag system

As one of the main components in slag, Al₂O₃ has a particularly prominent impact on the metallurgical properties of slag. For blast furnace ironmaking, the increase of Al₂O₃ in blast furnace slag will have an adverse impact on ironmaking and desulfurization. However, with the continuous development of China's iron and steel industry, the use of relatively low-cost high Al₂O₃ imported iron ore is increasing, which makes the content of Al₂O₃ in blast furnace slag significantly increase compared with the past. The mass percent of Al₂O₃ in blast furnace slag often exceeds 15%, and even higher can reach more than 20%. At present, there are few reports on the thermodynamic properties of Al₂O₃ components in high Al₂O₃ blast furnace slag system (for example, the measurement of Al₂O₃ activity by reference slag method) and their influence on the metallurgical properties of metallurgical slag, and temperature is one of the important thermodynamic factors affecting the metallurgical properties of metallurgical slag. Therefore, to explore the effect of temperature on the Al₂O₃ activity in metallurgical slag not only has important academic research significance, but also provides a solid theoretical basis for field practice. Thus, the activity of Al₂O₃ in CaO-SiO₂-Al₂O₃-MgO blast furnace slag system at 1 773-1 873 K is measured by reference slag method, and the structure of slag is detected by Raman spectrum. The effect of temperature on Al₂O₃ activity of CaO-SiO₂-Al₂O₃-MgO blast furnace slag system was investigated. The results show that with the increase of temperature, the chemical potential of Al₂O₃ in slag decreases, and the reaction between slag and Cu molten metal moves to the right to reach a new equilibrium. Therefore, the activity of Al₂O₃ decreases gradually with the increase of temperature. With the increase of temperature, Al₂O₃ in the slag reacts with alkaline metal oxides, increasing the formation of complexes such as calcium aluminate (CaO·Al₂O₃ and CaO·2Al₂O₃) and magnesium aluminate (MgO·Al₂O₃). At this time, the structure of the slag gradually depolymerizes due to the increase of O2-, and the free Al₂O₃ in the slag decreases, which cause the Al₂O₃ activity decrease gradually.