Flotation Techniques and Reagents Used in Graphite Beneficiation

flotation beneficiation

Graphite is one of the important carbon allotropes. The growing market requires high-purity graphite with large flakes. As natural high-grade graphite ores are becoming increasingly scarce, low-grade ores must be processed to increase their value to meet the growing demand. Since graphite is hydrophobic in nature, flotation is often used to beneficiate low-grade ores. This article introduces the flotation process of graphite ore.

Graphite is a natural crystalline isotope of carbon, greenish black and shiny. Graphite ore is usually associated with other metals and non-metallic ores, graphite in the common metal impurities including iron, aluminum, calcium, magnesium, potassium, sodium and so on. Iron is the most common metallic impurity, which usually exists in graphite in the form of iron oxide and iron carbonate. Common non-metallic impurities in graphite include elements such as silicon, sulfur, oxygen, and hydrogen. Among them, silicon is the most common non-metallic impurity, which usually exists in graphite in the form of quartz.

Graphite ore generally needs to be beneficiation to increase its fixed carbon content to 90% or even 95% or more to have a high industrial value, because graphite has a good natural flotation, therefore, flotation is the most commonly used beneficiation of graphite.

Flotation is the use of technology to adjust the surface hydrophobicity of ore particles, by improving the surface hydrophobicity of some of the particles and produce bubble collision, so that part of the ore can be separated with the floatation, to achieve selective separation of materials. The flotation process has the advantages of high maturity, simple equipment, low energy consumption and low production cost. In other words, it is able to realize a greater improvement in graphite quality through simple means.

The flotation process mainly includes: multi-stage grinding, multi-stage beneficiation and medium ore return process. The process and principle are as follows: firstly, the original graphite ore is crushed and ground, so that the graphite is physically separated from other minerals. Then the graphite ore is mixed with some chemical reagents, and the surface tension of graphite and other minerals is lowered by soaking, so that they can be easily separated. After roughing, sweeping and selection process, through physical and chemical methods to further improve the purity and quality of graphite.

In order to improve the floatability of graphite ore in the flotation process need to add a certain amount of flotation agent. The types of flotation agent according to its role can be divided into trapping agent, foaming agent, pH adjusting agent, inhibitor. Among them, trapping agents such as diesel oil, kerosene, sulfate and carboxylate, etc.; foaming agents such as turpentine, alcohol ether, butyl ether oil, etc.; pH adjusting agents such as lime, sodium carbonate, etc.; inhibitors commonly used in quartzite, water glass and so on. According to the actual operating environment to choose the appropriate type of flotation agent, as well as the application of new flotation agent is the hot spot of flotation method.

According to the division of flotation, the flotation of scale graphite is the best, followed by dense crystalline graphite, and the flotation of cryptocrystalline graphite is the worst.

In graphite flotation, the quality of graphite concentrate is affected by the flotation rate, and there are many factors affecting the flotation rate, which can be mainly divided into two categories, the first category is the flotation process parameters, such as impeller speed, inflatable volume, bubble size, flotation chemicals and dosage, etc.; the second category is the nature of the mineral particles themselves, such as particle size, hydrophobicity and so on.

The above content is the introduction of graphite ore conventional flotation process and flotation chemicals, in the actual beneficiation plant, can not blindly choose, should be beneficiation test, according to the test analysis, the design of suitable graphite flotation process and the configuration of reasonable flotation chemicals, in order to improve the efficiency of graphite ore beneficiation, and obtain the ideal recovery rate.