污泥与煤混燃中含K、Na、Ca元素的矿物演变

Evolution of minerals containing K,Na,Ca in the mixedcombustion of sludge and coal

针对污泥混煤燃烧过程中由矿物熔融引起的结渣与沾污问题,采用X射线荧光光谱(XRF)对污泥混煤的灰成分进行了分析,通过XRD实验明确了矿物组分并进行了分析,运用Gibbs最小自由能法,通过FactSage软件模拟了污泥与煤混燃过程含K、Na、Ca元素矿物的迁移演变。结果表明,城市污泥与煤混合物中含K、Na、Ca3种元素的矿物分别为白云母、片钠铝石、片沸石。燃烧过程中含K元素矿物迁移过程主要在白云母与钾芒硝(或硫酸钾石)和透长石之间;含Na元素矿物迁移过程主要在片钠铝石、无水芒硝、低温型钠长石及高温型钠长石之间;含Ca元素矿物的迁移主要在硬石膏和钙长石之间。温度达到900℃以上时,分别含K、Na、Ca元素的矿物物相都不再发生改变,且此时矿物质含量分别为透长石、高温钠长石以及钙长石。

In order to provide a basis for solving the problem of slagging and contamination in the combustion of sludge mixed coal from a micro level,the ash composition of sludge mixed coal was analyzed by X-Ray Fluorescence Spectrometer(XRF),and the mineral composition and the mineral composition were clarified by X-Ray Diffraction(XRD)experiment.The analysis was carried out,and the migration and evolution of minerals containing K,Na,and Ca during the co-firing process of sludge and coal were simulated using the Gibbs minimum free energy method and FactSage software.The results show that the three elemental minerals containing K,Na and Ca in the mixture of urban sludge and coal are muscovite,dawsonite and zeolite.During the combustion process,the migration process of K-containing minerals is mainly between muscovite and potash thenardite(or potash sulfate)and diaspermite;the migration process of Na-containing minerals is mainly in dawsonite,anhydrous thenardite,and low-temperature sodium between feldspar and high-temperature albite;the migration of Ca-containing minerals is mainly between anhydrite and anorthite.At temperatures above 900°C,the mineral phases containing K,Na,and Ca elements will no longer change,and the mineral content in this order will be feldspar,high temperature sodium feldspar and anorthite.