准格尔电厂高铝粉煤灰直接制备M50莫来石的实验研究

PREPARATION OF M50 MULLITE DERIVED DIRECTLY FROM HIGH-ALUMINA FLY ASH:A CASE STUDY FOR THE JUNGAR POWER PLANT IN INNER MONGOLIA,NORTHERN CHINA

利用粉煤灰制备莫来石是粉煤灰高附加值资源化利用研究的一个重要方面,但由于普通粉煤灰中Al2O3含量较低,使得制备过程中必须添加大量工业氧化铝,从而增加了合成成本。采用正交实验的方法,利用准格尔电厂高铝粉煤灰直接制备M50莫来石,并用阿基米德法测定莫来石样品的物理性能,经过XRD和SEM对制备的莫来石样品进行物相组成和显微结构研究,结果表明:利用高铝粉煤灰直接制备M50莫来石的物理性能可以满足《烧结莫来石》标准的质量要求,烧结样品其物相组成主要是莫来石和少量的玻璃相。影响烧结合成莫来石的主要因素是烧结温度,其次是恒温时间和试样的成型压力,高温下缩短恒温时间比低温下延长恒温时间有利于莫来石的形成,利用高铝粉煤灰直接制备M50莫来石适宜的烧结温度为1 400℃~1 500℃,恒温时间以2 h^3 h为宜。

Preparation of mullite derived from coal fly ash is an important research field for value-adding utilization of the fly ash. However,this technique is restricted duo to the high cost resulted from adding a large amount of Al2O3 to the fly ash in order to increase a deficient alumina composition to mullite. In this paper, M50 mullite derived directly from high-alumina fly ash of the Jungar power plant was prepared based on orthogonal test. The physical properties of the mullite samples were determined by Archimedes＇ method, and the phase constitutes and micro- structures were analyzed by using XRD and SEM. It was showed that these M50 mullites could meet the demand of quality for sintered mullite. The phase constitutes of the sintered samples are dominantly composed of mullite and a small amount of glassy materials. The major factor affecting the preparation of mullite is sintering temperature, followed by holding time and molding pressure. Decrease of the holding time at a higher temperature is more profitable than increase of the holding time at a lower temperature during the formation of mullite. The feasible sintering temperature and holding time are 1 400 ℃ -1 500 ℃ and 2 h-3 h respectively for preparation of M50 mullite derived directly from high-alumina fly ash.