燃煤过程煤中有害矿物质的迁变行为研究进展

Research progress onmigration and transformation behavior of hazardous mineral matter in coals during coal combustion

煤中的矿物质是燃煤引起环境问题的主要因素,其种类繁多,在燃煤过程中的迁移转化规律也极其复杂,理清其迁变规律,对燃煤排放控制极为重要。燃煤过程中矿物的热转化涉及蒸发、破碎、分解、融合及凝并等过程,不同矿物会发生不同的反应与转化,最终分布去向可概括为:炉渣、底灰、飞灰和燃烧废气悬浮微颗粒等。燃煤过程矿物质所表现出的性质和行为,主要与煤中矿物质的地质特征和燃煤工艺条件2个因素有关,其中温度和气氛是主控因素。目前对矿物质热演化行为的原生地质影响因素研究较为薄弱,具体为煤中矿物质的天然与燃煤过程的富集分异机理、煤中矿物质的地质特征与其热演化行为之间的潜在关系,地质背景与燃煤工况对矿物质热演化行为的双重影响与控制等。

Minerals and potentially hazardous trace elements in coals are the main origin of negative effects,such as environmental pollu⁃tion,during coal combustion.There are so many minerals and trace elements in coals,and their transformation and migration during coal combustion are extremely complex,which are closely related to their emissions.Based on the previous studies,behavior of common minerals and trace elements in coals during coal combustion was reviewed from a coal geology insight,which can provide a reference for related re⁃searches and for controlling emissions.During coal combustion,thermal transformation of minerals involves of the processes of breaking,de⁃composition,evaporation,agglomeration,fusion,condensation,etc.Similar with minerals,emissions of trace elements during coal combustion also show distinctive differences,mainly depending on their volatiling and combustion conditions.Fate of mineral matter after coal combus⁃tion includes slag,bottom ash,fly ash,and suspended particles in coal-fired flue gas.Behavior of mineral matter during coal combustion is mainly influenced by the geological characteristics of mineral matter in coals and by the conditions of coal combustion process.Temperature and atmosphere are the two mostly significant factors effecting on their behavior.At present,there were some theories about the transforma⁃tions of mineral matter in coals during combustion established preliminarily.Nevertheless,general regularities are rarely proposed and sum⁃marized.And studies on original geology factors affecting on the behavior of mineral matter during coal combustion are inadequate.The specific aspects are as follows.Enrichment and differentiation mechanism of mineral matter in nature and during coal combustion,potential relationship between geological characteristics of mineral matter and their thermal evolution behavior,and the dual effect mechanism of geo⁃logical setting and combustion condition on the thermal behavior of mineral matter require to be studied further.