Abstract:

Recycled SiO₂ micropowder solid waste (SiO₂<85 mass%) was heat treated at 400,500,600,700,800,900,and 1 000 ℃ for 5 h,respectively,and then the heat treated powders were analyzed.The results show that the samples are gradually sintered as the heat treatment temperature increases.Below 800 ℃,the original structure of granular and spherical SiO₂ aggregates remains.However,at 500 ℃ or below,the aggregates strength is low.Above 800 ℃,SiO₂ micropowder agglomerates seriously and cristobalite is precipitated.When the heat treatment temperature is in the range of 600-800 ℃,the spherical SiO₂ micropowder with a certain strength and the bulk density of 0.73-0.95 g·cm ^-3 and a core-shell structure can be prepared,which can be used as a lightweight raw material for low temperature insulation castables and as a filler for other industries.

Key words: silica micropowder, solid waste, aggregates, cristobalite

摘要：

对回收的w(SiO₂)<85%的低硅含量SiO₂微粉固废进行了不同温度(400、500、600、700、800、900和 1 000 ℃)保温5 h的热处理,并对热处理后的粉体进行了分析。结果表明:随着热处理温度升高,试样逐渐烧结。热处理温度低于800 ℃时,SiO₂微粉保持原有粒状、球状SiO₂颗粒团聚体结构。但热处理温度为500 ℃及以下时,团聚体强度较低。热处理温度800 ℃以上结块严重,并析出方石英相。热处理温度控制在600~800 ℃ 可制得具有一定强度,体积密度在0.73~0.95 g·cm ^-3的球壳结构的球状粉体,该粉体可以作为轻质原料用在低温保温浇注料,也可以作为其他行业填料。

关键词: 二氧化硅微粉, 固废, 团聚体, 方石英