Artificial graphite particles are materials made by synthetic methods with excellent physicochemical properties such as lightweight, high-temperature resistance, acid and alkali resistance, self-lubrication, and good electrical and thermal conductivity. It is similar to polycrystalline in crystallography and is usually made from carbonaceous raw materials with low impurity content, such as petroleum coke, asphalt coke, etc. aggregate, and coal pitch, etc. as binder, through the processes of batching, mixing and kneading, molding, carbonization, and graphitization. China's manmade graphite market has exceeded 50 billion yuan in 2022, a year-on-year growth of 100.99%, and shipment has risen to 1.15 million tons, a year-on-year growth of 88.98%.
The following is the method of making artificial graphite pellets:
1. Raw material preparation
1.1 Selection of raw materials: we usually use petroleum coke or asphalt coke as the main raw material, the better is the calcined needle coke.
1.2 Crushing and spheronization: The raw materials are crushed to achieve certain particle size requirements, such as the median particle size control in 7-9μm.
2 . Mixing and granulation
2.1 Mixing: the crushed raw materials and binder (such as asphalt) according to a certain proportion of mixing, such as raw materials and asphalt mass ratio of 100:16. Mixing time can be 90-120 minutes, preferably 100 minutes.
2.2 Pelletizing: pelletizing is carried out in a drum furnace at a controlled temperature of 300-400°C, such as 300°C, 350°C or 400°C. The pelletizing time is 4-6 hours. The granulation time is 4-6 hours, preferably 5 hours. During the granulation process, bonding occurs between the raw material particles to form the initial granular structure.
3. Carbonization and graphitization
3.1 Carbonization: The granulated material is carbonized in a non-oxidizing atmosphere, usually held at about 1250°C for a certain period. This step helps to remove excess volatiles and allows the binder to melt and impregnate the voids of the granules to form a denser structure.
3.2 Graphitization: The carbonized material is graphitized at high temperatures (e.g. 3000°C). Graphitization is a key step in converting the char material into a graphite structure and usually requires long periods of holding at high temperatures.
4 . Post-processing
4.1 Ball milling and sieving: The graphitized material is further physically mixed and ball milled through a ball mill, and then sieved to obtain artificial graphite particles that meet the requirements. The powder from the ball mill is piped to a sieving machine for screening, and the sieved material is metered and packaged using an automatic baling and metering device.
The whole process requires precise control of the parameters of each step, such as temperature, time, etc., to ensure that the artificial graphite particles prepared have excellent properties to meet the needs of different applications, such as lithium batteries, process manufacturing, and other fields.
