Graphite is an allotrope of the element carbon. Each carbon atom is surrounded by three other carbon atoms (arranged in multiple hexagons in a honeycomb pattern) to maximize the valence. Bonded together to form a highly valent molecule. Because each carbon atom emits an electron, and those electrons can move freely, graphite is a conductor of electricity. Graphite is one of the softest minerals and its uses include making pencil leads and lubricants. Carbon is a non-metallic element located in Group IVA, the second period of the periodic table of elements. Purification methods
Graphite purification: chemical purification and physical purification. Chemical purification takes advantage of graphite's acid, alkali, and corrosion resistance to treat graphite concentrate with acids and alkali to dissolve impurities and then wash them away to improve the grade of the concentrate. High carbon graphite with grade 99 can be obtained through chemical purification. There are many methods for chemical purification. The most widely used method in China is the high-temperature melting method of sodium hydroxide. The basic principle is to react impurities in graphite (mainly silicate minerals) with caustic soda, i.e. NaOH, under high temperature conditions above 500°C to generate water-soluble reactants. Part of the reactants can be eliminated by leaching the reactants with water. Impurities, another part of the impurities, such as iron oxides, are neutralized with HCl after alkali fusion to generate water-soluble ferric chloride, which can be removed by washing with water. In the above process flow, the concentration of NaOH is about 50, and it is mixed with graphite in a ratio of 1:0.8, that is, the production of 1 t of high-carbon graphite consumes about 0.4t of NaOH. The amount of HCl added is about 30 times that of graphite. The coal used as fuel is about 0.6 to 0.7 tons. The equipment used in the alkali fusion method mainly includes anchor mixers, melting furnaces, propeller mixers, V-shaped washing tanks, etc. The recovery rate is 85-90%, and the investment is 150,000-200,000 yuan. Although this kind of technology is more advanced, it also has shortcomings such as large water consumption, large graphite loss, low productivity, large alkali consumption, and the discharged waste liquid pollutes the environment. For the above reasons, the cost is higher. In order to solve or improve the above shortcomings, the Rock and Mineral Testing Center of the Henan Provincial Department of Geology and Mineral Resources developed a new process for purifying high-carbon graphite, replacing the V-shaped washing tank with centrifugal washing, and recycling the waste liquid after treatment. Using this new process, material costs can be reduced by about 50%, water can be saved by about 50%, productivity can be increased by about 10%, and the environmental pollution of waste liquids can be reduced. The fixed carbon content of graphite is greater than 99, and the recovery rate reaches 92.8. Physical purification refers to high-temperature purification. Taking advantage of the high-temperature resistance of graphite, it is placed in an electric furnace and heated to 2500°C while isolating air to volatilize the ash (i.e. impurities), thus improving the grade of the concentrate. High-purity graphite with a grade of 99.9 can be obtained through high-temperature purification. ?