Graphite is a kind of allotrope of elemental carbon.
Each carbon atom is surrounded by three other carbon atoms (multiple hexagons arranged in a honeycomb pattern) that are covalently bonded to form a covalent molecule. Since each carbon atom emits an electron, those electrons can move freely, so graphite is a conductor.
Melting point: 3652 ℃ Boiling point: 4827 ℃
Classification of graphite:
Characteristics of graphite:
● High temperature resistance: the strength of graphite increases with the increase of high temperature. At 2000 ℃, the strength of graphite doubles
● Conductivity and thermal conductivity: the conductivity of graphite is 100 times higher than that of ordinary non-metallic ores. The thermal conductivity exceeds that of steel, iron, copper and other metal materials Material. The thermal conductivity decreases with the increase of temperature, even at extremely high temperatures, graphite becomes an insulator.
● Lubricity: The lubricating performance of graphite depends on the size of graphite flakes. The larger the flakes, the smaller the friction coefficient, and the better the lubricating performance.
● Chemical stability: graphite has good chemical stability at room temperature, and can resist acid, alkali and organic solvent corrosion.
● Plasticity: Graphite has good toughness and can be rolled into very thin sheets.
● Thermal shock resistance: when graphite is used at room temperature, it can withstand sharp changes in temperature without damage. When the temperature changes suddenly, the volume of graphite changes little without cracks.
Use of graphite：
Refractory materials, conductive materials, petrochemical industry, wear-resistant lubricating materials, electrode materials, high-temperature metallurgical materials.
Distribution of graphite in china:
The reserves of graphite in China rank first in the world, but the graphite purification technology has always restricted the development of the graphite deep processing industry, especially the reserves and its rich microcrystalline graphite. Because of the complex mineral composition and the difficulty of purification, its application is limited.
Graphite purification method:
Acid base method, hydrofluoric acid method, chlorination roasting method and traditional high-temperature method
Comparison of graphite purification methods:
Acid base method:
Advantages: ◎ Low one-time investment ◎ Strong process adaptability ◎ Strong universal equipment
Disadvantages: ● High energy consumption, long reaction time ● Serious impact on equipment and environment ● The purity of purified graphite is not high
Hydrofluoric acid method:
Advantages: ◎ High efficiency, purity up to 99.9wt% ◎ Little influence on the performance of graphite products
Disadvantages: ● Great harm to human body ● Great environmental pollution ● Strong corrosivity ● High operation requirements
Chlorination roasting method:
Advantages: ◎ Low production cost ◎ Strong applicability in combination with Acheson furnace high temperature method ◎ High product yield
Disadvantages: ● Great harm to human body ● Great environmental pollution ● Strong corrosivity ● Insufficient reaction ● Unstable product quality
High temperature purification equipment
Acheson furnace high temperature purification furnace
Advantages: simple equipment, large output.
Disadvantages: long production cycle; High energy consumption; It is easy to oxidize, the quality is different in different regions, and the tail gas is discharged unorganized, causing serious pollution.
Pushboat type continuous high temperature purification furnace developed by ACME
★ Adopt the latest heating technology, with high operating temperature and long service life;
★ Continuous feeding and discharging, good sealing performance, less gas consumption;
★ For powder materials, fully automatic boat loading, boat pushing, discharging and boat dumping mechanisms can be selected, with stable product quality and low labor intensity.
Indirect high temperature purification furnace developed by ACME
★ This equipment adopts the exclusive ultra-high temperature and high current power introduction technology of Top Technology, which can be used stably for a long time under 2600 ℃;
★ Special high-temperature infrared measurement technology is adopted, which ensures accurate temperature control and small error;
★ Induction heating is adopted, and the maximum temperature can reach 3000 ℃.
Continuous high temperature graphite purification furnace developed by ACME
★ It can purify 95wt% of graphite raw materials to more than 99.95wt% at one time, realizing continuous large-scale production;
★ The maximum temperature of the equipment can reach 3000 ℃, and the long-term use temperature can reach 2800 ℃;
★ Low energy consumption and large output requirements;
★ The exhaust emission of the equipment meets the environmental requirements.