ABSTRACT

Mechanical exfoliation can generate graphene, but a consistent and scalable preparation of few-layer graphene (FLG) continues to be a challenge. We employed a mechanochemical milling technique to achieve maximum shear and frictional force by dual drive mode operation for preparation of FLG directly from beneficiated graphite ore. Low-grade graphite ore from Jharkhand, India, with a carbon content of 9%, was subjected to primary beneficiation by froth flotation technique using the naturally hydrophobic property of graphite as opposed to the associated impurities. The obtained graphite concentrates with an enriched carbon content above 90% after flotation was subjected to chemical treatment process including alkali roasting and acid leaching, which yielded an enriched graphite powder with fixed carbon of about 98.16%. A comparative study regarding the leaching efficiency was carried out between sulfuric acid and hydrochloric acid. The few-layered graphene was successfully prepared by mechanical milling of beneficiated graphite ore with oxalic acid at 20 hours with optimized critical speed. At various milling hours, the amplitude of the peak (002) decreased continuously, suggesting that the graphite size and thickness had decreased. Raman Spectroscopy confirmed the 20 h milled graphite is having single and few layered (<4 layers) graphene sheets.

摘要

机械剥离可以产生石墨烯，但一致且可扩展的少层石墨烯 (FLG) 制备仍然是一个挑战。我们采用机械化学研磨技术，通过双驱动模式操作实现最大剪切力和摩擦力，直接从精选石墨矿石制备 FLG。来自印度贾坎德邦的低品位石墨矿石（碳含量为 9%）通过泡沫浮选技术进行初级选矿，利用石墨的天然疏水特性而不是相关杂质。将浮选后富碳含量在90%以上的石墨精矿进行碱焙酸浸等化学处理工艺，得到固定碳含量约98.16%的富集石墨粉。对硫酸和盐酸的浸出效率进行了比较研究。以优化的临界速度在20小时内用草酸对精选石墨矿石进行机械研磨，成功制备了少层石墨烯。在不同的研磨小时，峰（002）的幅度不断减小，表明石墨尺寸和厚度已经减小。拉曼光谱证实，经过 20 小时研磨的石墨具有单层和少量（<4 层）石墨烯片。峰（002）的幅度不断减小，表明石墨尺寸和厚度已经减小。拉曼光谱证实，经过 20 小时研磨的石墨具有单层和少量（<4 层）石墨烯片。峰（002）的幅度不断减小，表明石墨尺寸和厚度已经减小。拉曼光谱证实，经过 20 小时研磨的石墨具有单层和少量（<4 层）石墨烯片。