不同变质程度的煤具有不同的自燃倾向性,研究煤的微观结构特征,对揭示和表征不同变质程度煤自燃的内在属性具有重要意义。以巴拉普库利亚、张家口、龙固、埠康等7个矿区的煤样为研究对象,分析了不同变质程度煤的表面特性、微晶结构和官能团的变化规律,进一步揭示了煤自燃性的内在微观机理。结果表明:煤表面性质参数随变质程度加深先减小后增大,微晶结构阶段性是导致这种变化的关键,且煤Cdaf为90%左右是转折点;随变质程度加深,煤分子内部微晶结构排列逐渐有序化,芳香环深度缩合,脂肪层结构含量减少,煤自燃性减弱;随煤变质程度加深,煤分子中羟基、羰基、烷基醚和芳香醚等官能团的含量均逐渐降低,这些官能团数量的差异决定了煤内在自燃性的难易程度。
The present paper takes it as the target to make an experi mental study on the characteristic features of the minute particles and the microstructures of the coal in the different structure levels and their tendency towards the spontaneous combustion varies greatly from a kind of coal to another. Therefore, it is of great benefit to make an exploration of the characteristic features of the microstructure of coal both in theory and in practice, especially to disclose the secret of the intrinsic nature and properties of the coal spontaneous combustion. To increase the study results as much as comprehensive and inclusive, we have chosen coal samples to be adopted in this paper from seven coal mines, including Barapukuria mine, Zhangjiakou mine, Longgu mine, Bukang mine, Dongshan mine, Wangcun mine and Baijiao mine, through which we have analyzed the changes of the microcrys tallistic structures and the functional groups of various ranks and sorts of coal in hoping to disclose the inherent potentiality and microscopic mechanisms of the said varieties of coal in coal spontaneous combus tion and the other physicochemical features and properties both in in dustry and social service values. The experimental results indicate that the parameters of the spontaneous combustion on the coal surface tend to decrease at the beginning of the combustion and then increase further and later. The staged characteristic of the microcrystalline structure is the key factor that contributes to the aforementioned physicochemical changes, with the carbon content of 90% spent as the juncture of the turning point. As the coal rank increased, the in ternal molecular arrangements gradually became ordered and aromatic rings condenced deeply. Meanwhile, the content of fat layer structure was reductive and mierocrystalline structures gradually turned to graphite, representing a low tendency of coal towards spontaneous combustion. In addition, the contents of functional groups such as hydroxyl, carbonyl, alkyl ether and aromatic ether reduced gradu