Graphite has good characteristics including high temperature resistance, electrical conductivity, thermal conductivity, lubricity, chemical stability and thermal shock resistance, etc. It’s an important raw material not only in aerospace, defense and military industry, high-end equipment manufacturing, new energy, new materials, information technology, energy conservation and environmental protection industry, but also for traditional industrial fields such as refractory materials, electrode brushes, pencils, casting, sealing, and lubrication. China is the country with the largest graphite reserves and output in the world, and its graphite beneficiation technology and equipment have long been in a leading position in the world. At present, there are more than 50 graphite beneficiation companies in my China, and more than 200 various processing companies, forming a production capacity of about 1.6 million t/a graphite concentrate. From 2014 to 2019, the global graphite concentrate production has been hovering at 900 to 1.2 million t/a, of which China accounted for about 60% of the global output. It can be seen that the in-depth research on graphite beneficiation technology and equipment is of great significance to enhance the international influence of Chinese graphite products.

Research progress of graphite beneficiation technology

Unlike most minerals, crystalline graphite beneficiation requires both high grade graphite concentrate and protection of the crystal structure of graphite minerals as much as possible. Therefore, graphite beneficiation technology and equipment have distinct characteristics.

Crushing technology

Because the hardness of graphite ore is generally medium-hard or medium-hard to soft, the crushing process is relatively simple, often using three-stage open-circuit, two-stage open-circuit or even one-stage open-circuit crushing process, and some use three-stage one closed-circuit crushing. process.

Grinding technology

In order to protect the crystalline morphology of the graphite flakes and increase the large flake rate of the concentrate, researchers have carried out a lot of research work, which can be summarized as the shape of the grinding medium, the form of the mill, the form of the flotation machine, and the flotation process. . On the basis of a large number of research and production practices, the currently widely used technology has been formed.

Beneficiation/processing technology

Crystalline graphite mostly adopts closed-circuit process of multi-stage regrinding of coarse concentrate, multi-stage beneficiation, and sequential (or concentrated or segmented concentrated) return of middling’s. Under normal circumstances, the beneficiation recovery rate can reach more than 85%, and some mines can reach more than 90%; the grade of concentrate is usually more than 90%, and the grade of fine flake graphite concentrate is usually more than 93%. Some mines have also tried the centralized or partially centralized regrinding process. In the 1980s, most graphite processing plants in my China used 3 to 5 regrind and redressing processes for coarse concentrates. At present, most of the graphite processing plants use more than 8 regrind and redress processes, and some even use 11 regrinds. The main reason for using multiple grinding is to protect the large scale graphite flakes from damage and increase the yield of large flake graphite in the concentrate.

According to the characteristics of the original ore, the types of crystalline graphite beneficiation processes can be divided into the following types:

1. Coarse flake graphite ore. This type of ore is characterized by large graphite flakes and good floatability. The primary graphite particle size is generally 0.6-2 mm, the fixed carbon is normally 1%-10%, and it contains a certain amount of mica. The beneficiation is mainly to protect the large flakes, and the concentrate grade is controlled at about 87% or even higher, in order to improve the yield of large scales, and the final concentrate +80 mesh content is 40% to 60%.
2. Medium flake graphite ore. The graphite flakes of this type of ore are medium in size and have good floatability. The primary graphite particle size is 0.2 to 0.6 mm, the fixed carbon is normally 4% to 15%, and the mica content is low. The graphite flakes are mainly to be protected, and the yield of large flakes is maximized. The grade of concentrate can be controlled at 86%～90%, and the content of +100 mesh is around 40%～60%.
3. Fine flake graphite ore. The graphite flakes of this type of ore are small and have medium floatability. The primary graphite particle size is 0.03 to 0.2 mm and the fixed carbon content is 6% to 15%. The product is focused on improving the purity, but it must also protect the large flakes even by reducing the recovery rate. The grade of concentrate is generally around 90%, some as high as 98%, and the content of +100 mesh is between 5% and 20%. This type of ore should strengthen the beneficiation process, and the beneficiation adopts multi-stage grinding and multi-stage separation processes.
4. Cryptocrystalline graphite ore. The crystal size of cryptocrystalline graphite is usually less than 1 μm. Therefore, it is often difficult to have obvious effects to improve the concentrate grade by flotation. At present, the mining volume of cryptocrystalline graphite in China is not large, and the method of manual selection is usually used to obtain higher-grade graphite concentrate. The grade of raw ore of Lutang Graphite Mine in Hunan is 65%～68%, the grade of hand-dressed concentrate is 70%～88%, and the grade of tailings is less than 60%. Southern Graphite Company has built a production line with an annual output of 200,000 tons of microcrystalline graphite. The recovery rate of microcrystalline graphite in the first phase of the project is greater than 92%, and the concentrate grade is about 82%.

With decades experience in graphite processing technology research and study, Prominer (Shanghai) Mining Technology Co., Ltd now have a professional technical team in advancing processing technology for graphite processing plants to preserve big flakes and improve the concentrate grade. Prominer (Shanghai) Mining Technology Co., Ltd can give graphite mining companies complete support for graphite processing plants!