机械粉磨对固硫灰中Ⅱ-CaSO_4晶体特性的影响

Influence of Mechanical Grinding on Properties of Ⅱ-CaSO_4 Crystal Residing in Circulating Fluidized Bed Combustion Fly Ashes

采用SM-500型水泥试验磨机对固硫灰进行粉磨改性,并利用FESEM/EDS、XRD、FTIR、HRTEM/SADP和化学滴定法表征了机械粉磨对固硫灰中Ⅱ-CaSO4晶体表面形貌、晶体结构和溶解特性的影响。结果表明,Ⅱ-CaSO4属多晶体,由形态各异的不规则的晶粒紧密堆积而成,晶粒尺寸约为几百纳米,粉磨后不易再观察到其清晰的晶体形貌,主要是由于超细化的含Si、Al的氧化物在其表面覆盖所致。粉磨能引起Ⅱ-CaSO4晶体迅速细化,晶粒内能增加,缺陷增多,逐渐趋向无定型化。同时,粉磨能提高Ⅱ-CaSO4晶体的溶解速率,但粉磨时间与其溶解特性之间却无明显规律。

Circulating Fluidized Bed Combustion Fly Ashes （CFAs） were ground by SM-500 cement ball mill. The morphology, structure and dissolution characteristic of CFAs samples were characterized by FESEM/EDS, XRD, FTIR, HRTEM/SADP and the chemical titration. The results indicate that 1/- CaS04 is a polycrystal which is composed of closely packed grains with all kinds of irregular shape. The grain size is about 100-1000 nm in diameter. The plain crystal morphology of Ⅱ-CaSO4 is not easily observed after grinding, which is because Ⅱ-CaSO4 crystal is covered with ultrafine oxide particles containing Si and A1 elements. Grinding can result in the fast refinement of Ⅱ-CaS04 crystal and the increase of internal energy and crystal defects, and Ⅱ-CaSO4 crystal gradually tends to undefined structures with the grinding time increasing. Grinding can enhance the dissolution rate of Ⅱ-CaS04 crystal, but the relation between grinding time and its dissolution characteristics is lack of regularity.