Preparation of high-purity graphite from a fine microcrystalline graphite concentrate: Effect of alkali roasting pre-treatment and acid leaching process

Removal of silicate minerals from microcrystalline graphite ores is important to achieve high-purity graphite product. Alkali roasting pre-treatment and acid leaching process was used to prepare high-purity graphite from a fine microcrystalline graphite concentrate. The results showed that the alkali roasting pre-treatment and acid leaching process could enhance the fixed carbon of microcrystalline graphite to a higher level. Under the optimum conditions selected, a graphite product with fixed carbon content of 99.0% was obtained from microcrystalline graphite concentrate with carbon content of 90.2%. According to XRD and SEM-EDS analysis, impurities mainly composed of Fe, Si, and Al were decomposed to water soluble or acid soluble components during alkali-roasting pre-treatment and acid leaching process. The crystal structure and surface topography of microcrystalline graphite showed no change.