煤灰中矿物质组成对煤灰熔融温度的影响

Effect of mineral composition on coal ash fusion temperature

选取九种不同灰熔融温度的煤样,利用X射线衍射分析方法,研究了煤灰的矿物质组成及含量对灰熔融温度的影响,以及弱还原性气氛下不同温度煤灰熔融过程中的矿物演变过程及其对灰熔融温度的影响。结果表明,815℃煤灰的主要晶体矿物质组成为石英、硬石膏、赤铁矿、氢氧钙石和石灰等。一般情况下,煤灰中氢氧钙石含量低,硬石膏和赤铁矿含量高的煤,灰熔融温度较低。在还原性气氛下,随着温度的升高,煤灰中的石英、硬石膏、氢氧钙石等结晶矿物含量逐渐减少,生成新的矿物质。莫来石的生成是导致煤灰熔融温度高的主要原因。低灰熔融温度煤灰在加热过程中,在1 100℃时,钙长石和铁钙辉石的生成起到了降低煤灰熔融温度的作用。

Nine different fusion temperature coals were selected,and the relationship between ash fusion temperature and ash mineral composition and content were studied by using XRD.The mineral transformation of typical coal ashes in reducing atmosphere was also investigayed.The results show that the mineral phases of coal ashes which are ashed at 815℃ mainly include quartz,anhydrite,hematite,portlandite,lime and potash feldspar.Higher anhydrite and hematite content and lower portlandite content would result in lower ash fusion temperature.As the heating temperature increases,the content of quartz,anhydrite and portlandite in coal ash decreases in reducing conditions and some new mineral phases are formed.Mullite is formed,which leads to higher ash fusion temperature.However,the formation of anorthite and hedenbergite at 1100℃ in the heating process is the main reason for the ash melting temperature lowing.