Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgium.
Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgium.
Waste Manag. 2023 Apr 15;161:234-244. doi: 10.1016/j.wasman.2023.02.015. Epub 2023 Mar 8.
Large volumes of steel slag are produced annually, leading to significant environmental protection and sustainable development issues. An online technology to monitor the solidification process of steel slag can assist in obtaining the right mineralogy to valorize these slags or render them harmless. For this purpose, we investigated the electrical properties and microstructural relationships of a CaO-AlO-SiO-MgO (CASM) slag during cooling using an innovative setup. The electrical impedance was determined over the frequency range of 20 Hz to 300 kHz at two cooling rates, and the solidification behaviour was observed simultaneously by confocal scanning laser microscopy (CSLM). Four zones can be distinguished in the conductivity-temperature curves for the slag cooled at 10 °C/min, whereas only two distinct zones are visible at 100 °C/min. The liquid fraction of the slag has a significant impact on the slag conductivity during cooling. The electrical conductivity is, therefore, an accurate indicator of the solidification degree. Different theoretical and empirical models were evaluated on their ability to relate the bulk conductivity of the slag to the liquid fraction. The empirical Archie's model proved to be the most suitable model for relating the bulk conductivity of the slag to the liquid fraction. In-situ electrical conductivity measurements during cooling can provide an online assessment of the slag solidification process, including indicating the appearance of solid precipitates, monitoring the growth of crystals, indicating complete solidification when no liquid phase remains, and indicating the cooling rate.
每年都会产生大量的钢渣，这导致了重大的环境保护和可持续发展问题。一种在线监测钢渣固化过程的技术，可以帮助获得合适的矿物学特性，从而实现这些炉渣的增值利用或无害化处理。为此，我们使用创新的装置研究了 CaO-AlO-SiO-MgO（CASM）渣在冷却过程中的电性能和微观结构关系。在两个冷却速率下，通过阻抗分析仪在 20 Hz 至 300 kHz 的频率范围内确定了电阻抗，同时通过共焦扫描激光显微镜（CSLM）观察了凝固行为。在以 10°C/min 冷却的渣的电导率-温度曲线上可以区分出四个区域，而在以 100°C/min 冷却的渣中仅可见两个明显的区域。渣的液相分数对冷却过程中的渣电导率有显著影响。因此，电导率是凝固程度的准确指示。评估了不同的理论和经验模型，以确定它们将渣的体电导率与液相分数相关联的能力。经验的 Archie 模型被证明是将渣的体电导率与液相分数相关联的最合适模型。冷却过程中的原位电导率测量可以在线评估渣的固化过程，包括指示固相析出的出现、监测晶体的生长、当没有液相残留时指示完全固化、以及指示冷却速率。
