The grade of crystalline graphite ore in China varies greatly. The ore grade of most deposits is 3-15%, the beneficiation grade is about 5%, and the schistosity is between 0.1-1.5mm. The ore washability is usually good.
1、 Graphite mining
The graphite deposit has the advantages of simple mining and convenient transportation. Open pit mining is usually adopted for crystalline graphite mine. According to the different terrain conditions of the mine, there are two methods: hillside open-pit mining and excavation open-pit mining. Hillside open-pit mining is adopted for graphite mines in mountainous and hilly areas such as Inner Mongolia, Shanxi and Heilongjiang; Open pit mining is adopted in plain areas such as Shandong. Among them, open-pit mining can obtain high recovery rate and low dilution rate, the recovery rate can reach more than 90%, and the ore dilution rate can be controlled below 10%.
2、 Introduction to beneficiation process of graphite
Due to the good floatability of graphite, flotation method is mostly used for graphite beneficiation. Under the current technical conditions, the purity (fixed carbon content) can only be increased to about 94 ~ 98% by flotation method; In order to produce higher purity high carbon graphite and high purity graphite, other methods such as chemical purification need to be used.
The main processes of graphite beneficiation include crushing, classification and flotation.
In the beneficiation of crystalline graphite, in order to protect and recover large flakes, the flotation process adopts the closed-circuit process of multi-stage grinding, multi-stage separation, medium ore sequence or centralized return; There are three forms of multi-stage regrinding and beneficiation: concentrate regrinding, middling regrinding and tailings regrinding.
3、 Deep processing products and production methods of graphite
At present, the deep-processing products of graphite mainly include high-purity graphite, expandable graphite, flexible graphite, fluorinated graphite, spherical graphite and graphite emulsion.
According to many years of experience, Fodamon engineers introduce and analyze the process of spherical graphite.
Spherical graphite is an elliptical spherical graphite product with different fineness produced by using high-quality high-carbon natural flake graphite as raw material and adopting advanced processing technology to modify the graphite surface.
Spherical graphite has the properties of low porosity, good oxidation resistance, uniform and fine structure, small cavity defects, moderate elasticity and easy molding. It is an important part of lithium ion battery cathode material.
Spherical graphite takes high-quality high-carbon graphite as raw material. In the process of spherical graphite processing, the higher the carbon content of raw materials, the higher the cost. However, if the carbon content of raw materials is too low, the number of times of spherical graphite purification process increases, the degree of equipment wear increases, and the total cost also increases. Through experimental accumulation, the raw materials with carbon content of 95-96% have the most economical comprehensive cost. During the processing of spherical graphite, there are also requirements for the particle size of raw materials. Too coarse and too fine will affect the output rate of spherical graphite, and too many auxiliary products will also increase the cost of raw materials. The results show that the raw material with particle size of – 100 mesh is the most suitable to produce spherical graphite.
In the production process of spherical graphite, the natural flake graphite powder is first crushed into appropriate particle size, and then processed for de angularization to finally form an ellipsoid or similar spherical shape. At the same time, the spherical particles are separated from the fine powder stripped in the de angularization process by using the grading device, and the normally distributed spherical graphite can be obtained.
Common technical equipment for graphite beneficiation
Jaw crusher are mostly used for coarse crushing of crystalline and amorphous graphite ores, cone crusher or hammer crushers are mostly used for medium and fine crushing, and ball mill, grinders or vibratory mills are used for grinding. A type or XJK type flotation machine is often used for flotation. Various centrifugal dehydrators or belt filters are often used for product dehydration.
The high square screen is mostly used for product classification, and a few use plane shaking screen and rotary screen. The high square screen is originally the finalization equipment of grain industry, and it is the unique screening equipment for graphite product classification in mineral processing.
Raymond mill, high-speed impact pulverizer and air flow pulverizer are used for ultra-fine grinding of graphite.