Graphite Beneficiation Process

Graphite ore can be divided into two types: earthy graphite ore and flake graphite ore. Natural flake graphite, when mined, often contains impurities and requires mineral processing. Here are the main methods used for processing each type:

1. Crystalline (flake) graphite: Crystalline graphite typically has a fixed carbon content of 2 to 10% and is of medium to medium-soft hardness. The ore grade is generally low, so it needs to undergo beneficiation for industrial use. Flotation is commonly used for this type of graphite due to its good buoyancy.
2. Aphanitic (earthy) graphite: Aphanitic graphite has a relatively high grade, with a fixed carbon content of 60-80%. However, it is difficult to sort the ore. To meet industry requirements for high-grade graphite, the raw ore is directly processed into powder. The process usually involves simple hand selection, crushing, drying, grinding, grading, and packaging.

For both types of graphite, there are specific processing methods:

• Hand selection: Aphanitic graphite with a high raw ore grade of 60-80% can be obtained through hand selection, crushing, and grinding.
• Gravity separation: Graphite ore contains various symbiotic minerals such as pyrite, pyrrhotite, limonite, zircon, white titanium, monazite, scheelite, diopside, and sometimes apatite. Gravity separation, often combined with flotation, is used to separate heavy minerals and obtain a rough concentrate primarily composed of graphite.
• Flotation separation: By using multi-stage grinding and separation, the grade of flotation graphite concentrate can usually reach 80-90%, with a purity of around 98%. This process effectively protects graphite flakes and improves the overall graphite grade.
• Electric separation: Graphite ore exhibits good conductivity, while gangue minerals like feldspar, quartz, and pyrite have poor conductivity. Electric separation takes advantage of this difference to separate graphite from other minerals.

Graphite Processing Plant

The general process flow for graphite mining includes several steps: crushing, screening, grinding, flotation, dehydration, drying, grinding, grading, and packaging.

1. Preparatory Process (Crushing, Screening, and Grinding):
   Graphite ore, with a medium-hard to soft hardness and a grade between 2% and 10%, undergoes a crushing process to avoid damage to the graphite flakes. It typically involves three-stage open circuit, two-stage open circuit, or one-stage crushing. Screening is done using a vibrating screen. Grinding is carried out using a ball mill and spiral classifier.
2. Flotation Process (Rough Selection, Sweeping, and Selection):
   For graphite ore containing heavy minerals, a combination of gravity separation and flotation can be used for separation. The flotation process involves a closed-circuit method with multi-stage grinding, sorting, and sequence of middle ore or centralized return.

There are three forms of multi-stage regrinding and re-separation: concentrate regrinding, middling ore regrinding, and tailings regrinding. The specific method of middling treatment depends on the beneficiation process design.

3. Concentrate Treatment (Dehydration, Drying, Screening, and Packaging):
   Dehydration of graphite ore concentrates is typically done using dewatering screens, filter presses, or rotary dryers. After dehydration, the concentrates are dried, screened, and then packaged.