高温弱还原气氛下高硅铝比煤灰变化行为的研究

利用XRD和FT-IR考察了两种高硅铝比煤(小龙潭褐煤、府谷烟煤)灰中矿物质在高温(1 100~1 500 ℃)弱还原气氛下的演变行为。通过FACT sage对煤中矿物质主要组分在高温下的变化进行了计算,并与XRD和FT-IR结果进行了比较和验证。结果表明,两种高硅铝比煤中矿物质在高温下的演变行为具有很大的差异,高温下,氧化钙含量较高的煤灰主要生成钙镁黄长石和钙长石等长石类矿物质,氧化钙含量较低的煤灰主要生成铝硅酸盐和少量的钙长石、拉长石等。氧化铁对晶体组成影响不明显;二氧化硅的含量随着温度的升高逐渐减少;低温共熔体系的存在降低了高硅铝比煤灰的灰熔点,同时,增加了高温煤灰中非晶体的含量。FACT sage热力学计算结果与XRD、FT-IR分析结果一致。

Evolution of coal ash with high Si/Al ratio under reducing atmosphere at high temperature

The transformation behavior of mineral matter in two coals(Xiaolongtan lignite and Fugu bitumite) with a high Si/Al ratio in coal ash was investigated under reducing atmosphere at high temperature by XRD and FT-IR.Furthermore,the theoretical changes of the main mineral composition at high temperatures were calculated using the thermodynamic software package FACT sage.It is found that the transformation behavior of mineral matter in the two high Si/Al ratio coals is different.The content of CaO has different effects on the transformation behavior of mineral.The major mineral matter formed at high temperature for the coal ash with high Ca content may be anorthite or gehlenite that maybe includes Mg,Na and K elements,while the major mineral formed for the coal ash with low Ca content maybe contains a large amount of aluminosilicate and a little anorthite.Iron oxide has little effect on the components of mineral matter in coal ash.The content of quartz decreases with increasing temperature.The forming of eutectic mixture leads to the decrease of the fusion temperature of coal ash,and the increase of the amorphous phase as well.The results of FACT sage calculation are consistent with the analysis of XRD and FT-IR.