The application of graphite and the classification of natural graphite

1. The application of graphite

Graphite is one of the crystalline minerals of carbon element. It has excellent properties such as lubricity, chemical stability, high temperature resistance, electrical conductivity, special thermal conductivity, plasticity, and coatability. Its application fields are very wide. Graphite is mainly used as a refractory material in the metallurgical industry; It is used as a mold and an anti-rust coating in the foundry industry; It is used in the electrical industry to produce carbon electrodes, electrode carbon rods, and batteries. Its resulting graphite milk can be used as a TV set Picture tube coatings. Other carbon products made from graphite can be used in many aspects such as generators, motors, communication equipment, etc.; In the machinery industry, it is used as lubricants for high-speed machines such as aircraft, ships, and trains; In the chemical industry, it is used to manufacture various Corrosion-resistant utensils and equipment; It is used as neutron moderators and protective materials in atomic reactors in the nuclear industry; In the aerospace industry, it can be used as rocket engine nozzle throat lining, rocket, missile heat insulation, heat-resistant materials and Radio-connected signals and conductive structural materials on artificial satellites. In addition, graphite is also a polishing agent and rust inhibitor for glass and paper in light industry, and a raw material for making pencils, ink, black paint, ink and synthetic diamond.

2. Classification of natural graphite

Graphite minerals with different crystal forms have different industrial values and uses. In industry, natural graphite is divided into three categories according to different crystalline forms.

2.1 Bulk graphite

Bulk graphite is also called dense crystalline graphite. Such graphite crystals are clearly visible to the naked eye. The particle diameter is greater than 0.1 mm, the specific surface area is concentrated in the range of 0.1-1m2/g, the crystal arrangement is disorderly, and the structure is dense block. This: graphite is characterized by a high grade, generally with a carbon content of 60 to 65%, sometimes 80 to 98%, but its plasticity and smoothness are not as good as flake graphite.

2.2 Flake graphite

Flake graphite’s crystals are scaly; This is metamorphosed under high-intensity pressure, and there are large flakes and fine flakes. This kind of graphite ore is characterized by low grade, generally between 2 to 3%, or 10 to 25%. It is one of the most floatable ores in nature, and high-grade graphite concentrate can be obtained after multiple grinding and multiple selection. The floatability, lubricity, and plasticity of this type of graphite are superior to other types of graphite; Therefore, it has the greatest industrial value.

2.3 Cryptocrystalline graphite

Cryptocrystalline graphite is also known as microcrystalline graphite or earthy graphite. The crystal diameter of this graphite is generally less than 1 micron, and the specific surface area is concentrated in the range of 1-5m2/g. It is an aggregate of microcrystalline graphite. The crystal form can only be seen under the electron microscope. This type of graphite is characterized by an earthy surface, lack of luster, and slightly less lubricity than flake graphite. Higher grade. General 60 to 85%. A few are as high as 90% or more. It is generally used in the foundry industry. With the improvement of graphite purification technology, earthy graphite is more and more widely used.