Litihium ion battery

Graphite Chemical Processing

Application of graphite in high tech products such as lithium ion batteries or fuel cells demands higher purity than is typically achieved by flotation. For further purification of a graphite concentrate to natural high purity graphite products with carbon contents of up to 99,99 wt.-% advanced chemical and thermal processes have to be applied.

Several procedures for purification of graphite concentrates are available. A basic process is thermal treatment in the presence of caustic reagents to dissolve siliceous impurities such as quartz, feldspar or mica. The graphite flotation concentrate is mixed with caustic reagent and baked at elevated temperatures. After baking the graphite is leached with water to wash away dissolved impurities.

In case ultimate purity levels are targeted, the more finely intergrown mineral phases residing in between the graphite layers, have to be removed. Typically an additional one or multi-stage acid washing with different acids or combinations thereof to remove impurities that are insoluble at alkaline conditions, is applied.

Optimal reaction conditions and reagent uses have to be matched by considering type and level of impurities present in the respective graphite concentrate, targeted product quality, markets and finally economics of the process.