碱金属钾对高碱煤灰熔融特性影响研究

Study on the effect of potassium on the ash fusibility of high alkalicoal

中文关键词: 碱金属  高碱煤  灰熔融特性  矿物质演变  液相收缩率  低温共熔

英文关键词: alkali metal, high alkali coal, ash fusibility, mineral evolution, liquid phase shrinkage, low temperature melting

中文摘要:

      为研究碱金属钾对高碱煤灰熔融特性的影响，将不同质量分数的K2SO4添加到制备的煤灰中进行灰熔融特性分析，并使用扫描电子显微镜(SEM)、X射线衍射(XRD)对煤灰微观形貌及其矿物质演变规律进行了研究，结果表明：随着K2SO4添加量的增加，煤灰熔融温度先降后升，体积液相收缩率先升后降，两者相互印证，K2SO4的加入在一定范围内加剧了煤灰熔融性，超过这一范围时会减弱其熔融性。随着温度的升高，添加K2SO4的煤灰由红色变为棕黑色，同时发生烧结，当温度高于1250 ℃时，煤灰由固相逐渐变为液相。煤灰中加入K2SO4份额逐渐增高时，高熔点的石英、莫来石、钙长石等不断减少，产生了白榴石、钾霞石等矿物质形成的低温共熔体，从而降低了灰熔点，加剧液相的形成甚至形成致密烧结体。

英文摘要:

      In order to study the effect of potassium on the ash fusibility of high alkali coal, K2SO4 with different mass fractions was added to the prepared coal ash to analyze the ash fusion characteristics, and the microscopic morphology of coal ash and its mineral evolution law were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that, as the addition of K2SO4 increases, the melting temperature of coal ash decreases first and then rises, and the volume liquid phase shrinkage first increases and then decreases. The two mutually confirm each other. The addition of K2SO4 intensifies the coal ash fusibility within a certain range, and when it exceeds this range will weaken its fusibility. As the temperature increases, the coal ash added with K2SO4 changes from red to brown-black, and sintering occurs at the same time. When the temperature is higher than 1250℃, the coal ash changes from solid phase to liquid phase. When the proportion of K2SO4 added to coal ash increases gradually, the high melting point quartz, mullite, anorthite, etc. continue to decrease, resulting in low-temperature eutectic formed by minerals such as leucite and kalsilite, which reduces ash melting point, and the formation of the liquid phase even forms dense sintered body.