Graphite Manufacturing Process

The manufacturing process of graphite includes two types: natural graphite and artificial synthetic graphite. There are several important steps in its production process to ensure its quality, which is related to the application of graphite materials in industry. In this blog, we will take you through the entire process of graphite manufacturing.

What Is Graphite?

Graphite is natural carbon. Black, silky, and slippery. It is in pencils, batteries and lubricants. Graphitic material with the highest electrical & thermal conductivity. It is also stable at elevated temperatures, which makes it more widely used in industry.

We have two ways to get graphite. It can be extracted from mines on the earth, or it can be produced synthetically.

Natural graphite is mined, ground, and processed to produce a dense structure. Among them, flake graphite has the characteristics of high temperature resistance and good conductivity. Its properties based on where it has been sourced and how it has been processed.

The production process of synthetic graphite is higher quality, more uniform and more flexible. The raw materials are processed in multiple stages to produce the final product. That process requires a lot of steps, but the end result is indeed quality. Synthetic graphite can be manufactured to a specification, and therefore is used for specific, critical applications, e.g., batteries and electronics.

Raw Materials: Graphite Manufacturing Process What Do You Need

It begins with raw materials. For example, you require carbon materials such as petroleum coke, needle coke, or pitch coke. These are critical raw materials as they are a source of high contained carbon, essentially the base element in graphite. Petroleum coke is derived from oil refining, while needle coke is a premium product used in graphite electrode production.

These cokes are then baked, and combined with binders. Binders provide the connection between particles leading to cohesion. Common binders are coal tar pitch, or petroleum pitch, which makes a tough, durable product. Depending on the final use of the graphite product, additives like silica or iron might be required as well. All of the materials are necessary to get to the final product graphite, and influence how the characteristics are set.

Step 1: Mixing Raw Materials

In a first step, the raw materials are mixed. The coke powder is crushed very finely, so that the binder can mix itself very evenly with the coke. Then the fine coke powder is mixed with the binder at elevated temperatures. The binder holds it all together, coating every particle of coke and ensuring they stick. This avoids heterogeneous mixing of the components and produces easily moldable constituents.

Mixing grade is another aspect too. In this case the mixture is non-homogeneous it can cause some weak points in process product. The temperature and timing have to be carefully controlled to ensure the binder is evenly distributed. This combination is fundamental for the shape of the product, impacting the density, porosity and strength of the graphite.

Step 2: Forming the Shape

Molding:

The slurry is poured into a mold and compressed. This technique tends to be good for building simple solid shapes (blocks, discs, etc). Molding works great for high-volume manufacturing where you need the same thing over and over.

Extrusion:

The material is extruded through a die to produce long rods, tubes, or other elongated shapes. In the case of graphite electrodes, for example, where consistent cross-sections are required, extrusion is adopted. It is possible to establish a constant manufacturing process of graphite in continuity and is appropriate for objects that should be getting peculiar figures.

Isostatic Pressing:

This process allows more complex shapes to be made without internal stress utilizing equal pressure all around. It is used for producing specific dense graphite with homogenous characteristics. When the end product has to resist high pressure or the production of complex precise shapes, compaction is usually carried out using Isostatic Pressing.

Step 3: Baking the Product

It needs to be baked to take out moisture and set the product after shaping. This process is known as baking or carbonization. It is like to put the shaped product into a baking oven, where the product is heated in high temp, normally to around 1,000 to 1,200°C, and druvking action will happen in the release of pyrolysis.

It can take weeks to the baking, when the precipitation is large and thick. It’s hooked up to something that brings temperature up slowly to not crack it or otherwise damage it. Once the mixture’s baked, the material dries out and hardens to the necessary hardness and density. It is one of the most important processes in the manufacturing process as it plays a key role in forming the strength, density and porosity of the product. Once baked, it goes by “carbonized material” or “carbon artifact.”

Step 4: Impregnation

The subsequent step is impregnation for enhancing the quality of the carbonized product. Impregnation — filling with another substance the pores of the baked product.Used in order to increase its density and strength.

Asphalt Impregnation:

You’re filling those pores of the carbonized material with asphalt. The density and mechanical strength of the product is improved by impregnation of asphalt. This also has the ultimate effect of reducing the porosity of the material, which results in not only a more durable but also a more wear resistant product.

Resin Impregnation:

The product has been impregnated with synthetic resin in resin impregnation. This method is used in obtaining a product with good electrical insulation properties or where a higher resistance to select chemicals is needed. Resin immersion also makes the graphite stronger and more resilient.

Metal Impregnation:

Metals such as copper or silver are also used for impregnation in some instances. Metal impregnation increases electrical and thermal conductivity. Like, it is used in the sole applications that require a highly conductive material like some electric components.

Once impregnated, the product is typically baked once more to cure the impregnation material. This second baking step also helps the impregnation substance to adhere better to the carbonized material, leading to a stronger and more durable product.

Step 5: Graphitization

The fifth step is graphitization. In graphitization, manufacturers heat the carbonized product in a resistance furnace at extremely high temperatures, typically more than 3000 °C. By altering the atomic structure of carbon, the hope is to turn it into graphite. Under these high temperatures, the atoms rearrange into a crystalline structure, called layers of carbon atoms that define graphite.

And the high temperatures kill off any residual impurities, making the product highly pure. Graphitization is an important process during which graphite is defined with variation properties of low lubrication, high electrical conductor, and high heat resistant ability. Therefore the product realised is a much more stronger and stable material as compared to carbonized material and can be used in highly demanding engineering applications.

Step 6: Machining

The final shape and size of the graphite are machined after graphitization. Graphite is softer than almost any other industrial ingredient, so it is easy to machine. The product you get may require cutting, drilling or milling to some dimensions and requirements.

High-precision machining must be done on graphite electrodes used in electric arc furnaces for them to be a good fit work well. Based on the application, also provides us with the possibility of producing customized shapes and designs during our machining process. Many graphite parts may not capable of being Machined and could have threads, bores or other precision machining — which need for skilled operators and specialized equipment.

Quality Control: Checking the Product

After machining, inspection takes place. Quality-control is a must in the synthetic graphite manufacturing process, as crucial specs have to be obtained. Manufacturers must complete tests on density, strength, porosity, conductivity and other specifications for each batch of materials.

They also undergo visual inspection to look for defects including cracks, uneven surface or imperfections. Special equipment is used to measure the conductivity and thermal conductivity of the graphene. These tests are used to claim that the product satisfies the expectations measured from an industrial point of view and comply with the needs and wants from targeted customers. Manufacturing that has quality assurance ensures consistency of quality, and this is successful in preventing the sale of defective products into the marketplace.

Purification: Optional for High Purity

There’s a need at times for ultra-pure graphite for specialty applications, such as in the semiconductor or electronics industries. If that is the case, an extra purification step is used to eliminate impurities. Regarding the purification process, manufacturers generally perform chemical treatment or high-temperature thermal treatment.

Chemical purification uses acids or other chemical agents for the solution of impure components. On the other hand, in high temperature thermal treatment graphite is heated at such high temperatures that impurities can evaporate (solids). High purity graphite,exactly purified graphite are employedi n applications like nuclear reactors, batteries and some aerospace components. Its official name is purified graphite, or high-purity graphite.

Recycling Scrap Graphite

Graphite is a precious material and recycling is a key method for its production. Manufacturers can collect, recycle and utilize graphite scrap. If manufacturers crush the recycled graphite into fine powder and add it to the raw material mixture, they can produce new graphite products or carbon products.

Graphite recycling promotes sustainability while preserving resources. And it cuts costs, since processing recycled graphite costs less than extracting and processing fresh raw materials. Recycled graphite is used in many industries to reduce environmental impact and increase sustainability.

Key Applications of Manufactured Graphite

Graphite Electrodes: Used in the electric arc furnaces, to smelt scrap metal. They have always been the core of the steelmaking and other metals refining sectors.

Graphite Used as Anode Material: Graphite is currently the only anode material that can be used in lithium-ion batteries. Its great electrical conductivity property makes it a suitable material for storing energy.

Graphite as Expandable: This type of graphite tiles serve as fire retarded. Expandable graphite expands when heat is applied and forms an insulating layer that effectively prevents fire from spreading.

Lubricants and Seals: The lubrication properties of graphite makes it ideal for lubricants. It prevents friction and wear in machinery, which helps to prolong the life of equipment.

Refractory Materials: High-temperature applications such as refractory bricks and crucibles are made of stable graphite.

Electronics / Semiconductor: People commonly use the high purity graphite in the manufacture of electronic components and semiconductors where stable conductivity and thermal stability are required.

Conclusion

Graphite is time-taking and complex process that needs many stages to obtain the desired qualities– Graphite quality is determined by mixing raw materials, graphitization, and machining.

Graphite manufacturing efficiency and sustainability are enhanced through quality control, optional purification and recycle of scrap graphite. Its manufacture ensures a uniform, stable graphite product for industrial, electronics, or high-purity use. Jinsun is one of the leading graphite manufacturing companies in China, and you are always welcome to contact us.