Development direction of natural graphite: comprehensive improvement of deep processing technology, mining technology and management planning
Natural graphite is an allotrope of carbon elements and an important inorganic non-metallic material. It is black-gray, has a metallic luster, is soft, and has a smooth feel. It can be divided into natural graphite and artificial graphite. Natural graphite is usually divided into flake graphite and cryptocrystalline graphite. It is generally formed in high-temperature geological conditions and is widely distributed in metamorphic deposits. It is formed by regional metamorphism of sedimentary rocks rich in organic matter or carbonaceous matter. It has excellent thermal shock resistance, chemical stability, ultra-high lubricity, small thermal expansion coefficient, large thermal conductivity, high temperature resistance, and good electrical conductivity. It is a new type of carbon material with excellent performance. Natural graphite is widely used in various fields of the national economy, such as machinery, metallurgy, petrochemical industry, light industry, electronics, electrical appliances, national defense, military industry, aerospace, etc.. It is known as one of the "universal" non-metallic materials.
The development direction of natural graphite mainly focuses on the following aspects:
High-end product deep processing technology: With the continuous breakthroughs in deep processing technologies such as chemical and thermal purification technology, coating technology, and carbonization technology, high-end graphite products such as spherical graphite, expanded graphite, high-purity graphite, flexible graphite, and graphene are mass-produced and widely The application will be implemented in the near future. To obtain ultra-high purity graphite, fine impurities between the graphite layers must be removed, which can be achieved by single-stage or multi-stage pickling using different acids or combinations. An alternative to acid treatment is thermal purification by heating graphite to temperatures above 2000 degrees Celsius. High-end graphite products have become indispensable key materials in strategic emerging industries such as aerospace, nuclear energy, new energy vehicles, energy storage, nuclear power, environmental protection, and new materials.
Improvements in graphite mining technology: In the graphite mining process, the application of technologies such as automation, the Internet of Things, and underground drone three-dimensional mapping is becoming more and more popular, improving safety, improving performance and productivity, and reducing mining costs. The application of highly automated and efficient equipment for rough processing and flotation of graphite is beneficial to the beneficiation of high carbon content flake graphite concentrate without seriously damaging the graphite crystals.
Management and planning: China's Ministry of Industry and Information Technology proposed the "Graphite Industry Access Conditions" and began to curb low-level duplication of graphite mining. It planned graphite project construction, production scale, and product quality and changed the multiple, small, scattered, and chaotic market structure of China's graphite mining industry has entered a period of consolidation. Since then, the State Council of China has approved that six departments, including the Ministry of Land and Resources will jointly issue and implement the National Mineral Resources Plan (2016-2020), which will include graphite in the strategic mineral resources catalog and further strengthen the management of the mining and utilization of graphite resources.
Where can natural graphite be used?
Natural graphite has excellent electrical conductivity and thermal conductivity, generally iron black, metallic luster and low hardness. In addition to this, the graphite flakes are also flexible. The purity of natural graphite ore is generally low, and the fixed carbon content is between 10% and 25%.
Natural graphite is widely used in many fields, including but not limited to the following aspects:
Manufacturing refractory materials: Because graphite has good thermal and electrical conductivity, it is used to manufacture refractory materials, such as refractory bricks, crucibles, etc. In the steel industry, graphite is also used as a carburizing agent. A wide range of carbonaceous materials are used for carburizing, including artificial graphite, petroleum coke, metallurgical coke and natural graphite.
Conductive material: Graphite is extensively utilized in the electric industry as electrodes, brushes, carbon poles, carbon tubes, positive electrodes of mercury rectifiers, graphite gaskets, telephone components, finishings for television picture tubes, and so on. Amongst them, graphite electrodes are the most widely used. When smelting various alloy steels and iron alloys, graphite electrodes are used. At this time, strong current is introduced into the smelting area of the electric furnace through the electrodes, generating an arc and converting electrical energy into heat energy.
New energy field: In the new energy field, graphite can be used as an anode material for lithium-ion batteries. Negative electrode materials have high requirements on the performance of graphite, which usually requires spheroidizing the graphite and purifying it to more than 99.9%.
Nuclear energy field: In the nuclear energy field, natural graphite also plays an important role. In the spherical fuel elements of the pebble-bed high-temperature gas-cooled reactor, natural graphite accounts for 64%.
New carbon materials: In recent years, graphene has become a hot new carbon material. Due to its good electrical conductivity, thermal conductivity, lubrication, wear resistance, high temperature resistance, corrosion resistance, radiation protection and many other excellent properties, graphite is used in various industries of the national economy.
The above are some of the main applications of natural graphite. In addition, natural graphite is also widely used in nuclear industry, machinery manufacturing, metal smelting and other fields.
What advantages does natural graphite have?
Natural graphite has excellent electrical conductivity and thermal conductivity, generally iron black, metallic luster and low hardness. In addition to this, the graphite flakes are also flexible. The purity of natural graphite ore is generally low, and the fixed carbon content is between 10% and 25%.
How to get natural graphite?
Purification is generally carried out by a flotation method, a chemical method, a chloride roasting method, a high temperature method, etc., wherein the flotation method is applied to natural flake graphite.
Chemical methods include acid-base melting and hydrofluoric acid methods. The acid-base melting method utilizes a strong acid, a strong base, or other compound to act on impurities in natural graphite to convert it into a water-soluble substance, thereby improving the purity of the graphite. In the chloride roasting method, the graphite powder is doped with a certain amount of reducing agent and chlorine gas is introduced, and the chloride in the gas phase is released from the impurities in the graphite by high temperature conditions.
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