Graphite Mineral Introduction

Graphite is an important non-metallic mineral resource, an allotrope of carbon. Graphite is black-gray, soft, greasy, chemically stable, corrosion-resistant, and does not react easily with chemicals such as acids and alkalis.

Graphite Ore Beneficiation Methods

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

• Crystalline Graphite Beneficiation Methods

Crystalline graphite has good natural flotability, and flotation methods are basically used for ore beneficiation. Since the size of graphite flakes is one of its most important quality indicators, a multi-stage grinding and multi-selection process is used in the selection method to separate large flake graphite as soon as possible.

• Cryptocrystalline Graphite Beneficiation Methods

Cryptocrystalline graphite has very small crystals, so it is also called microcrystalline graphite. Graphite particles are often embedded in clay, which has poor floatability and is difficult to separate. Due to the high grade of the raw ore (generally 60% to 80% carbon content), many graphite mines directly crush the ore, hand-separate it, and then grind it for sale.

Graphite Flotation Beneficiation Flow

The beneficiation methods of graphite are flotation, gravity separation, electric separation, etc. The most widely used method is flotation. The specific steps are raw ore-crushing (coarse crushing, fine crushing)-grinding-flotation-dehydration and drying-classification-packaging.

• Crushing

The hardness of graphite ore is generally medium-hard or medium-hard to soft, and the grade of the original ore is between 2-10%. The crushing process is relatively simple. It often uses a three-stage open-circuit, two-stage open-circuit, or one-stage open-circuit process. If it is small-scale weathered ore, it is possible to grind the ore directly without crushing.

• Grinding and Flotation

Since the hardness of graphite ore is generally medium-hard or medium-hard to soft, and the grade is generally between 2% and 10%, the crushing process is relatively simple, often using three-stage open circuit, two-stage open circuit or one-stage crushing process. Small and medium-sized mines, which mainly process weathered ore, are directly sent to the ball mill without being crushed.

The flotation process is generally a closed-circuit process of multi-stage grinding, multi-stage separation, and sequential (or concentrated) return of middlings. There are three types of multi-stage processes, namely concentrate regrind, medium ore regrind and tailings regrind.

Crystalline graphite mostly adopts the concentrate regrinding process, and the recovery rate of the beneficiation operation can reach about 80% under normal circumstances. Some mines have also tried the middlings regrinding process, but the effect is not obvious. Some small factories also use open-circuit or semi-open-circuit flotation processes, because too many tailings are discarded. The recovery rate of beneficiation is very low, generally only 40% to 50%.

• Dehydration and Drying

In the drying process, the equipment is raised to a certain temperature according to the need for heat, and the material in the cylinder starts to be dehydrated in a large amount. The temperature of the drying is constant as a whole. The graphite rotates continuously with the rotation of the cylinder and exchanges heat and finally plays an excellent dryness.

• Classification

Under certain pressure, the density of the flotation slurry is small, and the solid percentage content is low, so the classification effect is good. The graphite is relatively depleted in the sedimentation and relatively enriched in the overflow, which is very beneficial to improve the regrind efficiency and the efficiency of selection.

• Middlings Processing

Due to the many times of grinding, a lot of medium ore will be produced in the process. Medium ore generally contains a large amount of graphite. If it is not processed, it will inevitably lead to a decline in the recovery rate and cause a waste of resources. Therefore, the separation of graphite medium ore is an indispensable step in the graphite beneficiation process.

There are many processing methods for graphite middlings, mainly the following: centralized return, sequential return, individual processing, and multiple processing methods combined processes.