Delihowski Jurij, Gajek Marcin, Izak Piotr, Jarosz Marcin
Faculty of Materials Science and Ceramics, AGH University of Science and Technology, 30-059 Krakow, Poland.
Comex Polska Sp. z o.o., 30-644 Krakow, Poland.
Materials (Basel). 2024 Jul 12;17(14):3464. doi: 10.3390/ma17143464.
Coal fly ash (CFA), a by-product of coal combustion, is a valuable raw material for various applications. However, the heterogeneous nature of the composition and properties of CFA provides challenges to its effective usage and utilisation. This study investigates the thermal behaviour of the fly ashes of lignite (FA1) and brown coal (FA2) and their fractions obtained by dry aerodynamic separation. Thermal analysis techniques, including thermogravimetry (TG), differential scanning calorimetry (DSC), and evolved gas analysis (EGA), were used to characterise the behaviour of the fly ash fractions while heating up to 1250 °C. The results reveal distinct differences in the thermal behaviour between ash types and among their different size fractions. For the FA1 ashes, the concentration of calcium-rich compounds and the level of recrystallisation at 950 °C increased with the decrease in particle size. The most abundant detected newly formed minerals were anhydrite, gehlenite, and anorthite, while coarser fractions were rich in quartz and mullite. For the FA2 ashes, the temperature of the onset of melting and agglomeration decreased with decreasing particle size and was already observed at 995 °C. Coarser fractions mostly remain unchanged, with a slight increase in quartz, mullite, and hematite content. Recrystallisation takes place in less extension compared to the FA1 ashes. The findings demonstrate that the aerodynamic separation of fly ashes into different size fractions can produce materials with varied thermal properties and reactivity, which can be used for specific applications. This study highlights the importance of thermal analysis in characterising fly ash properties and understanding their potential for utilisation in various applications involving thermal treatment or exposure to high-temperature conditions. Further research on advanced separation techniques and the in-depth characterisation of fly ash fractions is necessary to obtain materials with desired thermal properties and identify their most beneficial applications.
煤飞灰（CFA）是煤炭燃烧的副产品，是一种可用于多种用途的宝贵原材料。然而，CFA成分和性质的不均匀性给其有效使用和利用带来了挑战。本研究调查了褐煤飞灰（FA1）和褐煤飞灰（FA2）及其通过干式空气动力学分离获得的级分的热行为。采用热重分析（TG）、差示扫描量热法（DSC）和逸出气体分析（EGA）等热分析技术，对飞灰级分在加热至1250℃时的行为进行了表征。结果表明，不同类型飞灰及其不同粒径级分的热行为存在明显差异。对于FA1飞灰，950℃时富钙化合物的浓度和重结晶程度随粒径减小而增加。检测到的最丰富的新形成矿物是硬石膏、钙黄长石和钙长石，而较粗的级分富含石英和莫来石。对于FA2飞灰，熔化和团聚开始的温度随粒径减小而降低，在995℃时就已观察到。较粗的级分大多保持不变，石英、莫来石和赤铁矿含量略有增加。与FA1飞灰相比，重结晶程度较低。研究结果表明，将飞灰通过空气动力学分离成不同粒径级分可以产生具有不同热性质和反应活性的材料，可用于特定应用。本研究强调了热分析在表征飞灰性质以及理解其在涉及热处理或高温条件的各种应用中的利用潜力方面的重要性。有必要对先进的分离技术和飞灰级分的深入表征进行进一步研究，以获得具有所需热性质的材料并确定其最有益的应用。
