Graphite is one of the highest melting points in nature, melting point of 3 850 ± 50 ℃, boiling point of 4 500 ℃, and silicate mineral boiling point at 2 750 ℃ (quartz boiling point) below, the boiling point of graphite is much higher than Contains the boiling point of the impurity silicate. This feature is the high temperature method of refining the rational basis of graphite.

The graphite powder is directly charged into the graphite crucible, heated to 2 300-3 000 ° C in a purification furnace which is passed with an inert gas and a freon-protected gas, and the impurities in the graphite are overflowed for a period of time to effect the purification of the graphite. High temperature method generally used by flotation or chemical purification of carbon-containing 99% or more high-carbon graphite as a raw material, can be purified to 99.99% graphite, such as by further improving the process conditions to improve the crucible quality, purity can reach 99.995% Above [20].

High temperature method can produce more than 99.99% of ultra-high purity graphite, but requires the fixed carbon of raw materials to more than 99%. And expensive equipment, huge investment, production scale has been limited, electric furnace heating technology requires strict, In the hot air to 450 ℃ when the temperature began to be oxidized, the higher the temperature, the greater the loss of graphite. Only the special quality of graphite industry requirements (such as defense, aerospace, etc.) using high-temperature production of high-purity graphite.

A large number of research and production practices have shown that in many methods of purification of graphite, although the advantages and disadvantages, but the alkaline acid production process is simple, the production environment is loose, low production costs, do not produce toxic and hazardous waste, Liquid treatment easier and so on. In the solution to shorten the roasting and leaching time, improve the purification effect, properly solve the problem of wastewater treatment, alkaline acid method will be the best way to produce graphite in industrial production.