Ultra-high purity purifying technique for native graphite

Abstract

The invention discloses a hyper-high purity extracting technology of natural graphite, which comprises the following steps: (1) putting natural graphite in the container to do oxidizing disposal with low-middle carbon content more than 98%; (2) fusing at high temperature; (3) inputting in the metal erosion-proof container; proceeding dealkalization; (4) deacidifying to wash to neutral; (5) proceeding electromagnetic black metal removing disposal in the floating pool; (6) heating in the autoclave from 118 deg, 206 deg and 220 deg separately; (7) using pure water to dispose; (8) dehydrating; (9) drying until the water content is less than 0.1%.

Description

technical field [0001] The invention relates to an ultra-high-purity purification method of natural graphite, in particular to an ultra-high-purity purification process of natural flake graphite. Background technique [0002] At present, the purification methods of natural graphite known at home and abroad are divided into low-purity purification and high-purity purification. In the industry, people usually refer to graphite with a carbon content of less than 94% as medium and low-carbon graphite, and refer to graphite with a carbon content of 94%. -99.8% is called high-carbon graphite; the carbon content of 99.9%-99.99% is called high-purity graphite, and the carbon content of more than 99.99% is called ultra-high-purity graphite. In high-purity purification, high-temperature electrothermal method and alkaline purification with sodium hydroxide at a temperature of 700°C to 800°C are commonly used. The former uses the high-temperature resistance of graphite, puts it in an el...

AI Technical Summary

Problems solved by technology

In high-purity purification, high-temperature electrothermal method and alkaline purification with sodium hydroxide at a temperature of 700°C to 800°C are commonly used. The former uses the high-temperature resistance of graphite, puts it in an electric furnace, and heats it to 2500°C without air The ash in the graphite is volatilized above to produce more than 99.9% of high-purity graphite. This process is complex and requires the construction of a large-scale electric furnace. The power consumption is also quite large, and the inert gas needs to be continuously introduced, which is costly and especially important. When the purity of graphite reaches 99.93%, the purification limit has been reached, and the fixed carbon content cannot continue to increase

Alkaline purification using sodium hydroxide at a temperature of 700°C to 800°C, due to the reaction of impurities such as Si, Fe, Al, Ca, K, Na, Mg and other elements in graphite with sodium hydroxide at high temperature to form soluble Wash the water with a large amount of water to remove some water-insoluble substances. The reagents used in this method are strong alkali and strong acid corrosion. At the same time, the density of graphite is small and the floatability is good. It causes a large loss of products, and the increase of waste is not conducive to recycling, resulting in higher costs. At the same time, due to the defects of the process itself, the purity of natural graphite can only be purified to 98-99.8%.

In addition, the chlorination purification process of natural graphite disclosed in Chinese patent application number 94105051.3, this process is to adopt chlorine gas and bulk material layer infiltration or fluidization mode to carry out high-temperature chlorination under the action of catalyst and reducing agent in the reaction furnace. The process is complicated, and there are great potential safety hazards. The purity after treatment is only 98% to 99.9%. This process has not been industrialized, and no one in the industry uses it.

The carbon content of graphite used in the aerospace industry, the automotive industry, and the biotechnology industry must be high-purity graphite that must be above 99.9%, and some industries require that the carbon content must be above 99.99%. and defects, so that the carbon content can never reach 99.99%