低质煤煤灰高温熔融机理的试验研究

Experimental study of coal ash fusion mechanism of low-grade coal under high temperature

为充分利用西南地区的煤炭资源,选取西南地区较有代表性的低质煤紫燕煤与低灰分、高热值的汇瑞煤和鲁南煤进行比较,利用X射线衍射(XRD)物相分析研究不同煤灰在不同温度下的矿物组成变化。结果表明:煤灰的熔融温度与高岭石的含量成正比,与方解石、白云母和磁铁矿等成反比。在1 000℃时,莫来石、钙黄长石和钙长石开始形成,莫来石和钙黄长石随着温度的升高先增加后下降。紫燕煤在加热过程中生成大量的莫来石是导致煤灰熔融温度较高的主要原因。汇瑞煤在高温下生成的莫来石和钙黄长石反应生成钙长石,有效的抑制了莫来石的生成,这也是其熔点较低的原因。鲁南煤生成的莫来石含量少且参与钙长石的形成,因此,其煤灰熔点温度介于两者之间。通过对比研究,为应用紫燕煤等低质煤时,有效防止窑系统结皮堵塞及堆"雪人"提供帮助。

The mineral compositions of coal from three different cement plants in Southwest China were studied by X-ray diffraction （XRD） analysis.The results showed that all the samples of coal contain quartz, kaolinite as main minerals and a little of calcite, muscovite, magnetite and so on.The fusion temperature of coal ash tended to be proportional to kaolinite content, and in inverse proportion to the content of calcite, mus- covite,magnetite.Mullite,gehlenite and anorthite started to form at 1 000 ~C .The content of mullite and gehlenite increased at first and decreased then as the temperature rising.It turned out that mullite was the main cause of coal ash fusion temperature rising during heating process of coal in Ziyan cement plant.But in the same process of Huimi cement plant,mullite reacted with gehlenite to product anorthite so the coal ash fusion tem- perature was low.The content ofmullite producted in Lunan cement plant was lower than the other two cement plants and anorthite was product, so the coal ash fusion temperature was between the other two cement plants.The results provided theory reference of effectively preventing buildups jam of kiln system and ＂snowman＂ formation when low-grade coal is used.