Fu Xiang, Liu Xuan, Wu Qixuan, Xiao Bin, Fan Chaojun
College of Mining, Liaoning Technical University, Fuxin, 123000, China.
Sci Rep. 2024 Mar 28;14(1):7396. doi: 10.1038/s41598-024-58186-5.
Magma intrusion has an important influence on the physical and mechanical properties of coal and rock. In the area of magma intrusion, disasters such as gas outburst are prone to occur. Revealing its invasion law will be conducive to disaster management and energy development. For this purpose, changes in industrial analysis components of coal, mineral composition, major oxides, trace elements, and rare earth elements of coal under the thermal metamorphism of magma intrusion were analyzed. It is found that the moisture and volatile matter contents of the thermally affected coals in the mining face are generally lower than that of normal coals, while moisture and volatile matter contents are reduced towards to the magma intrusion contact. For example, the moisture and volatile matter of coal sample M01 decreased by 64.6% and 38.6% respectively compared with coal sample M05. During magma intrusion, some minerals remain on the surface of the coal body, resulting in changes in the mineral composition of the coal body. The decrease in carbon atom net spacing, the increase in crystallite aggregation and ductility, and aromaticity in thermally affected coals have a positive impact on the improvement of coal metamorphism. Due to the influences of magmatic intrusion, the variation rules of major oxides in coal are different, and the closer to the magmatic intrusion zone, the easier the major oxides are to be depleted. However, magma intrusion will not lead to the loss of all major oxides in thermally affected coals, such as content of CaO is 54.8%, which is higher than that of coal not affected by magmatic hydrothermal fluid. Most of the trace elements in the thermally affected coals of the No. 9 coal seam are depleted. The contents of rare earth elements are low on the whole coalbasis, with an average of 29.48 μg/g, and the distribution pattern towards to magmatic intrusion shows a wide and gentle "V" curve with left high and right low, showing the characteristics of enrichment of light rare earth elements.
岩浆侵入对煤岩的物理力学性质有重要影响。在岩浆侵入区域，容易发生瓦斯突出等灾害。揭示其侵入规律将有利于灾害治理和能源开发。为此，分析了岩浆侵入热变质作用下煤的工业分析成分、矿物组成、主要氧化物、微量元素和稀土元素的变化。研究发现，采面受热影响煤的水分和挥发分含量普遍低于正常煤，且水分和挥发分含量向岩浆侵入接触带方向降低。例如，煤样M01的水分和挥发分与煤样M05相比分别降低了64.6%和38.6%。岩浆侵入过程中，部分矿物残留在煤体表面，导致煤体矿物组成发生变化。受热影响煤中碳原子净间距减小、微晶聚合度和延展性增加以及芳香性增强，对煤变质程度的提高有积极影响。由于岩浆侵入的影响，煤中主要氧化物的变化规律不同，离岩浆侵入带越近，主要氧化物越容易亏损。然而，岩浆侵入不会导致受热影响煤中所有主要氧化物的流失，如CaO含量为54.8%，高于未受岩浆热液流体影响的煤。9号煤层受热影响煤中的大部分微量元素亏损。稀土元素在全煤基上含量较低，平均为29.48μg/g，向岩浆侵入方向的分布模式呈宽缓的左高右低“V”形曲线，显示出轻稀土元素富集的特征。
