高铁煤灰的黏温特性及熔渣矿物质研究

摘要

以七种高铁煤灰为研究对象,采用高温黏度计测试煤灰的黏温特性,按煤灰黏温特性的特征对样品进行分组,采用X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)和扫描电子显微镜及能谱(SEM-EDS)研究黏温特性与熔渣矿物质的关系.结果表明:高铁煤灰存在低灰熔点高黏度现象,样品的黏温特性曲线均呈现出结晶渣或接近结晶渣的特征,且存在不同程度的波动.Fe含量与煤灰黏温曲线的波动程度有一定的关联,随着煤灰中铁钙镁比(w(Fe2 O3)/w(CaO+MgO))的增加,其黏温曲线的波动增大.当铁钙镁比2.0时,煤灰黏温曲线有较大的波动.样品熔渣的背散射(BSE)照片表现出明暗相间部分,明暗不同的区域元素的富集程度不同.Fe和Mg主要富集于明亮区域,Si和Ca主要富集于较暗区域,Al在两种区域中均有较多分布.研究证实高铁煤灰黏温曲线波动与铁尖晶石或镁铝铁氧化物的生成有关.%Seven kinds of high-iron coal ash were selected as samples.The viscosity-temperature characteristics of high-iron coal ash were tested by high-temperature rotational visco-simeter.The samples were grouped according to the viscosity-temperature characteristics of coal ash.X-ray fluorescence (XRF),X-ray diffraction (XRD)and scanning electron microscope cou-pled with energy dispersive spectroscopy (SEM-EDS)were adopted to study the relationship between the viscosity-temperature characteristics and slag mineral.The results indicate that although the ash melting temperatures of high-iron coal ashes employe in this study are low,their critical viscosity temperatures are oppositely high.The viscosity-temperature curves of these samples show the characteristics of crystal slag and exhibit different fluctuation.The mass frac-tion of iron is related to the fluctuation of coal ash viscosity-temperature curve.With the increase of the ratio of w (Fe2O3 )/w (CaO+MgO),the viscosity-temperature curves of coal ashes show more obvious fluctuation,which is mainly due to the formation of hercynite or magnesium aluminium iron oxide.When the ratio of w (Fe2O3 )/w (CaO + MgO)is lower than 0.7,the viscosity-temperature curve shows none/little fluctuation.When the ratio of w(Fe2 O3 )/w(CaO+MgO)is between 0.7 and 1.0,certain fluctuation concentrated on viscosity value from 15 Pa·s to 60 Pa·s is exhibited.When the ratio of w(Fe2O3 )/w(CaO+MgO)is higher than 2.0,significant fluctuation on the viscosity-temperature curve is observed.The brightness difference of back scat-tered electron (BSE)images indicates the variation of element enrichment.Fe and Mg are mainly enriched in brighter area,Si and Ca are mainly enriched in darker area,and Al is detected in these two areas.