Graphite: with diverse mineral properties

Graphite is an allotrope of carbon. The following is a detailed introduction to graphite:

1. Basic properties

a. Chemical formula and molecular weight: The chemical formula of graphite is C, with a molecular weight of 12.01.

b. Physical state: Graphite is a gray black, opaque solid with a greasy feel that can contaminate paper. Its hardness is relatively small, ranging from 1 to 2, and can increase to 3 to 5 along the vertical direction with the increase of impurities. The specific gravity ranges from 1.9 to 2.3.

c. Gloss and Transparency: Graphite has a metallic luster, but is opaque.

d. Density: The relative density of graphite is 2.256g/cm ³.

e. Melting point and heat resistance: Under oxygen free conditions, the melting point of graphite is above 3000 ℃, making it one of the most temperature resistant minerals.

2. Special properties

a. Conductivity: Graphite is a conductor with good conductivity.

b. Thermal conductivity: Graphite has good thermal conductivity.

c. Chemical stability: Graphite has stable chemical properties, is corrosion-resistant, and does not easily react with chemicals such as acids and bases. But burning in oxygen will generate carbon dioxide, which can also be oxidized by strong oxidants such as concentrated nitric acid, potassium permanganate, etc.

3. Alias and Classification

a. Nickname: Graphite, also known as Black Lead, Shine, Shihei, Shiluo, Shidai, and Huamei Stone.

b. Classification: Graphite can be classified into various forms such as crystalline, flaky, scaly, striped, and layered according to its shape.

4. Application Fields

a. Refractory materials: Graphite and its products have the properties of high temperature resistance and high strength. They are mainly used in the metallurgical industry to manufacture graphite crucibles, and graphite is commonly used as a protective agent for steel ingots and lining for metallurgical furnaces in steelmaking.

b. Conductive materials: Graphite is used in the electrical industry to manufacture electrodes, brushes, carbon rods, carbon tubes, positive electrodes for mercury rectifiers, graphite gaskets, telephone parts, coatings for television tubes, etc.

c. Wear resistant lubricating material: Graphite is often used as a lubricant in the mechanical industry, which can work at high sliding speeds at temperatures of 200-2000 ℃ without the need for lubricating oil. Many devices that transport corrosive media widely use graphite materials to make piston cups, sealing rings, and bearings, which do not require the addition of lubricating oil during operation. Graphite emulsion is also a good lubricant for many metal processing (wire drawing, tube drawing).

d. Chemical equipment materials: Specially processed graphite has the characteristics of corrosion resistance, good thermal conductivity, and low permeability. It can be used to make equipment such as heat exchangers, reaction tanks, condensers, combustion towers, absorption towers, coolers, heaters, filters, pumps, etc. It is widely used in industrial sectors such as petrochemicals, wet metallurgy, acid and alkali production, synthetic fibers, and papermaking.

e. Casting metallurgical materials: Due to the small thermal expansion coefficient of graphite and its ability to withstand rapid cooling and heating changes, it can be used as a mold for glassware. The castings obtained from black metal after using graphite have precise dimensions, smooth surfaces, and high yield rates. They can be used without processing or with slight processing, saving a lot of metal. Graphite can also be used to manufacture ceramic boats for powder metallurgy processes such as hard alloys, as well as for crystal growth crucibles, regional refining vessels, support fixtures, induction heaters, etc. for single crystal silicon. In addition, graphite can also be used as graphite insulation boards and bases for vacuum smelting, as well as components such as high-temperature resistance furnace tubes, rods, plates, and grids.

f. Atomic energy industrial materials: Graphite has excellent neutron deceleration performance and can be used in atomic reactors. Uranium graphite reactor is a widely used type of atomic reactor. The deceleration material used in atomic reactors for power generation should have high melting point, stability, and corrosion resistance, and graphite can fully meet the above requirements. However, the purity requirements for graphite used in atomic reactors are very high, and the impurity content should not exceed dozens of PPM, especially the boron content should be less than 0.5PPM.

g. Anti scaling and anti rust materials: Adding a certain amount of graphite powder (approximately 4-5 grams per ton of water) to water can prevent scaling on the surface of the boiler. In addition, coating graphite on metal chimneys, roofs, bridges, and pipelines can also prevent corrosion and rust.

h. Pencil leads and pigments: Graphite can also be used to make pencil leads and pigments.

In summary, graphite is a mineral with various excellent properties and has a wide range of applications in various fields. With the continuous development of technology, the potential application areas of graphite will continue to expand.