Study on purification of flake graphite by heat activation and hydrofluoric acid

Abstract

ABSTRACT Graphite is an allotropic type of carbon composed of hexagonally organised carbon atom layers in a planar condensed ring structure (graphene layers). In recent years, researchers have reported the purification of graphite using various separation techniques, leading to the development of many methods for purifying graphite to separate it from the ore mixture. However, the majority of these methods are time-consuming, detrimental to the environment, expensive, need much energy, and have rather difficult manufacturing conditions. Although graphite is an essential strategic resource, and China has the world’s largest deposits and output of graphite, China’s graphite processing technology is very low, restricting the area of application. Therefore, the purpose of this study is to investigate the heat-activated hydrofluoric acid method (HAH), which is a simple and quick protocol that is often used to purify flake graphite. The optimum reaction parameters for purifying graphite are also explored, including hydrofluoric acid (HF) concentration, activation temperature, activation time, and sulphuric acid concentration. The results showed that the HAH process could purify raw flake graphite up to 99 %. As a result, the purification method in this study is applicable to the production of high-purity graphite.