黄铁矿对煤自然氧化影响的实验研究

Experimental research on the influence of pyrite on natural oxidation of coal

黄铁矿是促进煤自燃的重要影响因素,当黄铁矿氧化放热促进煤升温时,其形成的氧化产物也持续保存于煤体中。本文针对黄铁矿的主要氧化产物对煤自燃的影响展开研究,在煤中添加4类黄铁矿自然氧化产物进行程序升温实验,通过分析TG-DSC曲线的特征温度和放热量来判断不同氧化产物对煤自然氧化的影响。通过实验可知:不同浓度的Fe^(3+)和Fe^(2+)均降低了煤的3个特征点的温度,且随着浓度的升高,3个特征点的温度降低的越大,促进了煤放热;H^(+)的氧化煤中矿物质导致TG曲线特征温度点不能明显看出;Fe(OH)_(3)对煤低温氧化具有抑制作用。通过不同特征温度下煤样的FTIR测试,分析了黄铁矿氧化产物促进煤自然氧化的机理:Fe^(3+)和Fe^(2+)均加速了煤中活性结构含氧官能团(C=O、—CO—O—、—OH)、脂肪烃(—CH_(3)、—CH_(2)—)的氧化,H^(+)对—OH、—CH_(2)—的氧化具有一定促进作用,而Fe(OH)_(3)对煤中活性基团的影响变化不大,对煤自然氧化起物理阻化作用。

Pyrite is an important factor that promotes spontaneous combustion of coal.While the heat released by the oxidation reaction promotes the heating of the coal,the oxidation products formed by pyrite are also continuously maintained in the coal.This paper focuses on the influence of the main oxidation products of pyrite on the natural oxidation of coal.Four types of natural oxidation products of pyrite are added to coal to carry out temperature-programming experiments.By analyzing the characteristic temperature and heat release on the TG-DSC curve,the influence of different oxidation products on the natural oxidation of coal can be judged.Experiments show that different concentrations of Fe^(3+)and Fe^(2+)reduce the temperature of the three characteristic points of coal,and as the concentration increases,the temperature of the three characteristic points decreases,which promotes the heat release of coal.The characteristic temperature points on the TG curve cannot be clearly seen due to the minerals in the H^(+)oxidized coal.Fe(OH)_(3) has an inhibitory effect on low-temperature oxidation of coal.Through the FTIR test of coal samples at different characteristic temperatures,the mechanism of pyrite oxidation products promoting the natural oxidation of coal is analyzed.Both Fe^(3+)and Fe^(2+)accelerate the oxidation of active structural oxygen-containing functional groups(C=O,—CO—O—,—OH)and aliphatic hydrocarbons(—CH_(3),—CH_(2)—)in coal.H^(+)can promote the oxidation of—OH and—CH_(2)—to a certain extent.Fe(OH)_(3) has little effect on the active groups in coal,and has a physical inhibitory effect on the natural oxidation of coal.