1、Raw materials

The raw materials for producing high purity graphite are mainly aggregate, binder and impregnator. Aggregate is generally used needle petroleum coke and pitch coke. This is because needle petroleum coke has low ash content, easier to graphitize in high temperature environment, and excellent electrical and thermal conductivity, small coefficient of linear expansion, etc.; asphalt coke has relatively large resistivity, but has high mechanical strength, so usually when producing graphitized products, petroleum coke and a certain proportion of asphalt coke are applied, which is beneficial to enhance the mechanical strength of the products.

2、Calcination / purification

The role of calcination is to take various solid carbon raw materials and isolate them from the air for the treatment of high temperature heating. After the selection of aggregates, because their coking temperature and coal geological age is not the same, the internal structure will contain water, impurities or volatiles to varying degrees, these substances need to be removed in advance, otherwise it will have an impact on product quality and performance, so the need to calcine or purify the selected aggregates.

3、Grinding

Because graphite is a solid material, although the size will be reduced after calcination or purification, but the particle size is still relatively large, and not stable enough to uniform composition, the need to crush the aggregate particle size to meet the requirements of the ingredients.

4、Mixing and kneading

The ground powder and coal asphalt binder in accordance with a certain proportion of the configuration, and then added to the heating type kneading machine for kneading treatment, to promote the uniform distribution of materials.

5、Forming

There are four main molding methods: extrusion molding, molding, vibration molding, isostatic molding.

6、Baking

After forming, the carbon products must be roasted, and the raw billet after pressing is heat-treated under isolated air conditions to promote the change of binder carbon into binder coke.

7、impregnation

The role of impregnation is to impregnate the molten asphalt and other impregnating agents, increased to the roasting process of the product formed inside the tiny pores and aggregate coke particles in the open pores, so as to enhance the bulk density of the product, electrical conductivity, mechanical strength, chemical corrosion resistance, etc.

8、Graphitization

Graphitization refers to the high-temperature heat treatment process of converting thermodynamically unstable non-graphitic carbon into graphitic carbon by means of thermal activation.

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