Electrolysis destroyed the O-containing bonds of muscovite for the purification of natural flake graphite and its applications

The muscovite is arranged in parallel and tightly combined with the natural graphite layer, which forms a stable structure and impedes the diffusion of hydrofluoric acid in graphite. It requires large quantities of hydrofluoric acid and long diffusion time for effective purification of natural graphite, which leads to increased production costs and significant environmental impact. Therefore, it is necessary to reduce the amount of hydrofluoric acid used and improve purification efficiency. In this work, electrolysis was used to enhance acid leaching purification process and destroy the structure of muscovite to reduce the amount of hydrofluoric acid used. After hydrochloric acid leaching and heat treatment, the purity of natural flake graphite was increased from 95.27 % to 96.60 %, and the remaining impurities were mainly muscovite and quartz. Through electrolysis, the interlayer spacing of muscovite was increased, and the C-O bond between graphite and muscovite was destroyed, making it easier for hydrofluoric acid to enter and react with the muscovite layers. Compared with acid leaching, 99.9 % high-purity graphite was obtained by electrolysis, and the ratio of 40 wt% hydrofluoric acid to natural graphite was decreased from 1.0 mL/g to 0.7 mL/g, reducing the amount of hydrofluoric acid used by 30 %.