矿物质对褐煤低温氧化过程中微结构的影响

Effects of minerals on microstructure of lignite during low-temperature oxidation

利用盐酸脱除褐煤中的矿物质,对其进行了不同温度下的低温氧化性能测试和结构表征,同时与原煤的研究结果作对比,主要考察矿物质对褐煤低温氧化过程中微结构和质量变化的影响。研究结果表明:矿物质对褐煤低温氧化过程中的质量变化有较大的影响,脱除矿物质后的褐煤在氧化温度高于230℃时,质量发生突变,而原煤质量发生突变的温度低于脱矿煤,且质量变化率高出脱矿煤25%—35%。表征结果显示,脱矿煤在230℃氧化后的煤样中出现了苯醌类结构,较原煤滞后10℃左右,且矿物质的存在促进了环烷烃或脂肪烃的氧化,使煤样表面碳氧结构的质量分数增加,同时增加了晶体结构中的缺陷位,降低了石墨化程度。综上分析煤样质量在某温度范围内的突变主要与苯醌类结构的氧化分解有关。

The minerals of Shengli lignite were demineralized by HCl leaching.The low-temperature oxidation experiments and structural characterization were carried out at different temperatures on demineralized coal,and the results were compared with raw coal.The effects of minerals on the microstructure and mass change of Shengli lignite during low-temperature oxidation was mainly investigated.The results show that the minerals have a significant influence on mass change of Shengli lignite during low-temperature oxidation.The mass of demineralized coal changes suddenly,when temperature is higher than 230℃.However,the jump temperature of raw coal is lower than that of demineralized coal and the mass change rate is 25%—35% higher than that of demineralized coal.The characterization results show that the obvious analogous benzoquinone structure is formed in the demineralized coal after oxidized at 230℃,about 10℃higher than raw coal.The presence of minerals can promote the oxidation of cycloalkanes or aliphatic hydrocarbons,increase the content of carbon-oxygen structures on coal surface and the defects in the crystal structure,and reduce the graphitization degree.In summary,the jump of mass of coal in a certain temperature is mainly related to the oxidation decomposition of analogous benzoquinone structure.