高温弱还原性气氛下MgO的助熔机理

Melting Behavior of Flux MgO in High Temperature and Less Reductive Atmosphere

利用X-射线衍射仪(XRD)和扫描电镜(SEM)观察等现代测试方法,分析添加MgO助熔剂的煤灰中矿物在高温熔融过程中的行为以及微观形貌,并讨论了MgO的助熔机理。结果表明:高温弱还原性气氛下,原煤灰中的主要矿物为莫来石,它的存在使煤灰熔点较高。添加MgO助熔剂后,煤灰中存在的晶体矿物为堇青石、镁橄榄石及假蓝宝石,它们之间发生了低温共熔,1 300℃时,大部分矿物已经熔融,有较多的玻璃相产生,出现的玻璃相不断将周围物料浸润和熔融,导致煤灰熔点降低。

X-ray diffraction coupled with scanning electron microscopy was employed to study behavior and micro-appearance of minerals in coal ash samples with flux MgO in high temperature melting. Mechanism of MgO improving melting was discussed. The results show that the main minerals in row coal ash are mullite, which makes coal ash fusion temperature higher. With addition of MgO, low-tem- perature eutectic melting of cordierite, forsterite and alumina-spinel in coal ash occurred, which lower the ash fusion temperature.