5N high-purity carbon dust preparation process

The invention belongs to the field of material preparation, and particularly relates to a 5N high-purity carbon dust preparation process. The 5N high-purity carbon dust preparation process comprises the following steps: using 3N industrial carbon dust as a raw material, and then sequentially carrying out wet-process carbon dust purification, low-temperature volatilization and superhigh-temperature calcination to prepare 5N high-purity carbon dust. The wet-process carbon dust purification particularly comprises the following steps: using a certain concentration of hydrochloric acid, nitric acid and hydrofluoric acid to mix, then placing the carbon dust raw material in a mixed acid solution for soaking for more than 96 hours, introducing argon in the soaking process and stirring, wherein argon flow is determined in the way that the mixed solution cannot spill out of a PTFE barrel. Through the temperature control during the low-temperature volatilization process, a sulfur element volatilizes through temperature rising, and the sulfur element in carbon dust is removed. The condition that a sulfide with higher boiling point is generated through reaction of sulfur and ferrum, magnesium and carbon during the high-temperature calcinations process, so that the carbon dust purifying difficulty is improved is avoided. The preparation process can enable the carbon dust purity to be improved by 99.999%.