Purification
Graphite has trace elements. Their composition can be determined by the raw material it contains. The major impurities are eliminated during the final stage of the production. This process is called graphitization. Through thermal treatment at temperature ranging from 2600°C up to 3000°C. With this temperature range, baked carbon transforms electrographite. The extreme temperature can sublime the impurities. The impurity content in most electrographite is significantly below 1000ppm.
Graphite for Higher Purity Application
Numerous applications demand a significantly higher level of purity. The remaining impurities often consist of metals and their compounds, which cannot be eliminated through the elevated temperatures involved in the graphitization process.
To address this, a thermo-chemical purification technique is implemented. This method involves the use of highly reactive gaseous halogens, such as chlorine and fluorine, along with elevated temperatures.
This process facilitates the conversion of metal impurities and their compounds into volatile halogen compounds, which are then expelled from the graphite. As a result, the final ash content can be reduced to less than 5 ppm.
