Abstract Self-heating of coal waste is a major problem in the leading coal-producing and consuming countries, independent of the recent or past coal exploitation history. The phenomenon of self-heating is dependent on many factors such as the properties of organic matter (maceral composition and rank), moisture and pyrite content, climate effects, and storage conditions (shape of the dump or compaction of the coal waste). Once deposited, coal waste undergoes oxidation, which can lead to self-heating with the overall temperatures exceeding 1000 °C. During these self-heating processes, both organic and mineral matter undergo oxidative and thermal alterations, being influenced, among others, by the rate of heating as well as by the access of air and moisture. The morphological features of organic matter in coal waste at microscopic scale reflect the thermal conditions within the waste dump. Since 2008, several exercises designed to establish a petrographic classification system of oxidatively- and thermally-altered morphological forms of organic particles present in self-heated coal waste dumps have been carried out within the Self-heating of Coal and Coal Waste Working Group (Self-Heating WG), in Commission III of the International Committee for Coal and Organic Petrology (ICCP). Based on the degree of oxidative and thermal alteration, all assessed organic particles were divided into unaltered particles (huminite, vitrinite, liptinite, and inertinite macerals), altered particles, and newly formed particles (pyrolytic carbon, bitumen, chars, graphite, and coke). Altered particles were further divided according to their optical properties (porous, massive; isotropic, anisotropic). For altered particles the following specific features were distinguished: fractures, fissures, cracks; brighter rims; darker rims; plasticised edges; bands; devolatilisation pores; paler in colour particles. The final petrographic classification of oxidatively- and thermally-altered morphological forms of organic particles in coal waste dumps was established as a result of the successively performed Round Robin Exercises 2008–2017. The selected criteria and categories proved the high performance of the analysts characterised by a minor bias. The proposed petrographic classification system based on petrographic methods represents a useful way to characterize the undesirable phenomena occurring in coal waste dumps. Microscopic analyses and application of the petrographic classification system for organic particles affected by self-heating in coal waste offers the identification, documentation and monitoring of coal waste oxidation, self-ignition and combustion processes. It also enables a selection and application of appropriate measures to delay or even prevent undesired environmental impacts. The established classification system may assist in the air quality monitoring and assessment of burning waste dump sites and, thus, provide a relevant support in the environmental management of the disposal sites related to coal mining. The classification system can provide an important instrument for environmental protection agencies to increase the effectiveness of measures applied in fire hazard combating. The proposed classification of oxidatively- and thermally-altered morphological forms of organic particles in coal waste dumps can be applied on self-heating coal waste or mining dumps research, being a useful tool for coal waste managements performed by environmental agencies responsible for the landfill managements and monitoring of waste dumps.

中文翻译：

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煤废料中受自热影响的有机颗粒的岩相分类系统的开发。（ICCP 分类系统，自热工作组 - 委员会 III）

摘要 废煤自热是主要煤炭生产国和消费国的主要问题，与近期或过去的煤炭开采历史无关。自热现象取决于许多因素，例如有机物的特性（微晶成分和等级）、水分和黄铁矿含量、气候影响和储存条件（煤废料的倾倒或压实的形状）。一旦沉积，废煤会发生氧化，这会导致整体温度超过 1000 °C 的自热。在这些自加热过程中，有机物和矿物质都会发生氧化和热变化，尤其受到加热速率以及空气和水分进入的影响。煤废料中有机物的微观形态特征反映了垃圾场内的热状况。自 2008 年以来，煤炭和废煤自热工作组（自热）开展了多项旨在建立自热煤垃圾堆中存在的有机颗粒的氧化和热改变形态形式的岩相学分类系统的练习。 -加热工作组），在国际煤炭和有机岩石学委员会 (ICCP) 的第三委员会中。根据氧化和热蚀变的程度，所有评估的有机颗粒分为未蚀变颗粒（腐殖质、镜质体、锂铁质和惰性微晶）、蚀变颗粒和新形成的颗粒（热解碳、沥青、焦炭、石墨和焦炭） ）。改变的粒子根据它们的光学特性（多孔、块状；各向同性、各向异性）进一步划分。对于变质颗粒，可以区分以下具体特征：断裂、裂缝、裂纹；更亮的轮辋；较暗的边缘；塑化边缘；乐队; 脱挥发孔；颜色颗粒较淡。作为 2008-2017 年连续进行的循环练习的结果，确定了废煤堆中有机颗粒的氧化和热改变形态形式的最终岩相学分类。选定的标准和类别证明了分析师的高绩效，其特点是轻微的偏见。提出的基于岩相学方法的岩相学分类系统代表了一种有用的方法来表征发生在废煤堆中的不良现象。煤废料中受自热影响的有机颗粒的岩相分类系统的微观分析和应用提供了对煤废料氧化、自燃和燃烧过程的识别、记录和监测。它还可以选择和应用适当的措施来延迟甚至防止不良的环境影响。建立的分类体系可以辅助焚烧垃圾倾倒场的空气质量监测和评估，从而为煤矿相关处置场的环境管理提供相关支持。分类系统可以为环境保护机构提供重要的工具，以提高火灾危害防治措施的有效性。