蒸汽动能磨制备超细高岭土及其应用

Preparation and application of ultrafine kaolin by steam jet mill

通过调节蒸汽动能磨粉碎工艺参数,制备出3种超细高岭土样品,并对样品进行粒度、形貌和矿物分析;将超细高岭土样品作为阻燃剂添加到琼脂气凝胶中,测试琼脂-高岭土复合气凝胶的阻燃性能。结果表明:在粉碎压力为0.5 MPa、蒸汽温度为260℃的条件下,蒸汽动能磨分级机转速分别为700、 1 400、 3 500 r/min时,制备的超细高岭土样品的中位径分别为3.717、 3.034、 1.929μm;超细高岭石层状晶体的直径和厚度明显减小,粒度变得更加均匀,粒度分布更为集中;蒸汽动能磨能有效地破坏高岭石的晶体层状结构的连接键,但并未改变矿物物相;与高岭土原料相比,超细高岭土在气凝胶材料中分散得更加均匀,获得的琼脂-高岭土复合气凝胶保温材料的阻燃性能更佳,其极限氧指数从26.3%提升到32.2%,垂直燃烧UL-94等级从V-1提升到V-0级。

Three kinds of ultrafine kaolin samples were prepared by adjusting the process parameters of the steam jet mill. The particle size, morphology and mineral analysis were carried out on them. The ultrafine kaolin samples were added into agar aerogel as flame retardant, and the flame retardant properties of agar-kaolin composite aerogel were tested. The results show that the median diameters of the prepared ultrafine kaolin samples are 3.717, 3.034, 1.929 μm when the speed of the steam jet mill classifier is 700, 1 400, 3 500 r/min respectively, under the premise that the crushing pressure is 0.5 MPa and the steam temperature is 260 ℃. The diameter and thickness of ultrafine kaolinite layered crystals are significantly reduced, the particle size becomes more uniform, and the particle size distribution is more concentrated. The steam jet mill can effectively destroy the bonding bonds of the crystalline layered structure of kaolinite without changing the mineral phases. Compared with kaolin raw material, the ultrafine kaolin is more uniformly dispersed in the aerogel material, and the obtained agar-kaolin composite aerogel insulation material has better flame retardant performance, with its limiting oxygen index increased from 26.3% to 32.2% and vertical combustion UL-94 rating increased from V-1 to V-0 grade.