关键词: 碱酸法, 高纯石墨, 硅酸钠

Abstract:  The alkali-acid method is a main way of purifying graphite，which is widely applied，but the refining effect is not very good.The fixed carbon content of the graphite product which was achieved by the alkali-acid method was generally less than 99.9%.In this study，the restrictive factors of refining effect were obtained through the analysis and detection of graphite samples and filtrates in the different stages of technological process.After immersion and washing treatment，Si impurity wasn't complete removed，but it was easy to form silica gel which was very difficult to be eliminated.So it would limit the graphite purity to be enhanced.The test material with high ash content also affected refining effect.

Key words: Alkali-acid method, High purity graphite, Sodium silicate