硅铝比对钙镁耦合作用降低煤灰熔融性的影响研究

利用化学试剂配制不同硅铝比的模拟煤灰,探究不同硅铝比模拟灰的流动温度随灰中钙镁配比的变化规律;并借助XRD、SEM-EDX分析矿物转化过程,初探钙镁耦合作用发生机理.结果表明:随着硅铝比的增加,钙镁耦合作用降低煤灰熔融性的强度先增大后减弱,且在Si/Al为1.5时最大;钙长石与镁橄榄石发生低温共熔是钙镁耦合作用降低煤灰熔融性的主要原因.Si/Al为1.0和4.0时,随着模拟灰中镁钙比的增大,钙长石低温共熔体系及辉石类矿物低温共熔体系的建立,使得煤灰流动温度一直下降,未表现出耦合作用.钙镁含量相同的灰渣中,随硅铝比的增加,灰渣由片块状向团聚状、絮状转变;SEM-EDX分析结果与XRD分析结果一致.

Influence of Si/Al Ratio on Coupling Intensity of Calcium and Magnesium in Reducing Coal Ash-Fusibility

Factitious ash of different Si/Al ratio were prepared by using chemical reagents, and law of their flow temperature were studied with the change of compound proportion of CaO and MgO.Mineral transformation process was analyzed, and mechanism of coupling interaction of calcium and magnesium were explored by using XRD and SEM-EDX.The results show that with increasing of Si/Al ratio, the strength of coupling intensity of calcium and magnesium on reducing coal ash-fusibility increased at first and then decreased.It reaches maximum when Si/Al ratio is 1.5.Interacting between anorthite and forsterite at low temperature is main reason why coupling intensity of calcium and magnesium can reduce coal ash-fusibility.When Si/Al ratio is 1.0 or 4.0,with the proportion of MgO increasing in compound flux,the ash fusion temperatures come down because of the establishment of anorthite's reaction system and diopside's reaction system at low temperature.It does not show coupling effect of calcium and magnesium.With the increase of Si/Al ratio, schistose ash slag transformed macroaggregate or flocculatidn in ash slag of same Si/Al ratio.SEM-EDX analysis results are consistent with XRD analysis results.