碳纳米管超细粉碎分级的特性研究

Characteristics of carbon nanotube ultrafine grinding and classification

为了制备超细碳纳米管粉体,利用机械磨和气流磨对碳纳米管粉体进行超细粉碎,通过调控设备运行时分级机和引风机的转速,对不同运行参数下制备的超细碳纳米管的粒度、能耗、形貌特征进行测试与分析。研究发现,常温下气流磨分级机转速在2100~7200 r/min时,所制备的碳纳米管细粉粒度d_(50)在10.127~2.540μm;高温(200℃)下气流磨转速在4800~6000 r/min时,所制备的碳纳米管细粉粒度d_(50)在5.061~2.831μm。机械磨风量在339.757~688.903 m^(3)/h时,所制备的碳纳米管细粉粒度d_(50)在4.892~11.443μm。当粉碎到相同粒度d_(50)分别为5、10μm时,机械磨的产能分别为气流磨的1.6、2.1倍,而气流磨的单位吨能耗分别为机械磨的3、3.9倍。机械磨粉碎后的碳纳米管颗粒粒度明显减小,大多呈规则形状;气流磨粉碎后的碳纳米管颗粒粒径相对于机械磨粉碎后的颗粒粒度明显减小,大多呈无规则形状。因此,在工业生产中,综合考虑粉碎的粒度、能耗和形貌特征,可以选择机械磨进行粉碎,通过选择恰当的运行参数,既能满足粒度要求,又能实现节能的目的。

Carbon nanotubes powder is ultra-finely pulverized by mechanical mill and jet mill respectively to prepare ultrafine carbon nanotubes powder.Through adjusting the rotating speed of the classifier and the induced draft fan when the equipment runs,ultrafine carbon prepared under different operating parameters is controlled.The particle size,energy consumption,and morphological characteristics of the nanotubes are tested and analyzed.It is found that the particle size d_(50) of ultrafine carbon nanotubes powder is in the range of 10.127-2.540μm when it is prepared at room temperature and the jet mill classifier rotates at a speed of 2100-7200 r·min^(-1).The d_(50) is in the range of 5.061-2.831μm when the preparation temperature is at 200℃and the rotating speed of jet mill classifier is between 4800 r·min^(-1)and 6000 r·min^(-1).The d_(50) is in the range of 4.892-11.443μm when the air volume of mechanical mill is in the range of 339.757-688.903 m^(3)·min^(-1).As the d_(50) of nanotube powder reaches 5μm and 10μm,the productivity of mechanical mill needs to be 1.6 times and 2.1 times respectively that of jet mill,while the energy consumption per ton of the jet mill is 3 times and 3.9 times respectively that of the mechanical mill.The particles of the carbon nanotube become smaller after mechanical milling and most of them have regular shapes.The particles of carbon nanotubes after jet milling have an obviously smaller size than that after mechanical milling,and most of them are in irregular shapes.By comparing particle size,energy consumption and morphological characteristics,a mechanical mill is suggested for crushing carbon nanotubes in industrial production.Through selecting appropriate operating parameters,mechanical mill can meet the requirement in particle size and achieve the purpose of energy saving.