Purification method for high-purity natural graphite

Abstract

The invention discloses a purification method for high-purity natural graphite. A method for purifying graphite at high temperature is adopted, and the high-purity graphite is prepared by high temperature reaction, chemical purification, washing and dehydration. An oxidizer and a complexing agent are reacted with the natural graphite, impurities in the raw material are removed, and the graphite with low content of trace element and stable properties is obtained. In the process, the graphite raw material with the carbon content of more than 60 percent is purified, and the graphite with the purity of over 99.9991 percent, ash content of less than 1PPM and the trace elements of less than 0.5PPM is obtained; and the method has the advantages that: the process is simple, and is easy to operate; the production efficiency is high; the power consumption is low; large processing equipment is not needed; and the production cost is saved.

Description

technical field [0001] The invention relates to a method for purifying graphite, in particular to a method for purifying high-purity natural graphite. Background technique [0002] Graphite has the function of lubrication, and has good high temperature resistance, excellent electrical conductivity, thermal conductivity and other characteristics, and has a wide range of applications. In the electrical industry, it is used to produce carbon electrodes, electrode carbon rods, batteries, etc.; in the mechanical field, it is often used as a lubricant for high-speed machinery; in the chemical industry, it is used to manufacture various anti-corrosion vessels and equipment; natural graphite particles The shape, crystal structure, surface structure, and impurity content of graphite are closely related to the lithium intercalation performance of graphite materials. Common natural graphite shapes are mainly dense crystalline graphite, flake graphite, and aphanitic graphite. Pure natu...

AI Technical Summary

Problems solved by technology

Graphite is used as an industrial raw material, especially in some special industries and high-tech industries such as atomic energy industry, automobile industry, aerospace technology, biotechnology, etc., not only requires extremely high carbon content of graphite, but also requires that graphite should not contain too much Trace elements must be high-purity graphite above 99.9%. However, the carbon content of general natural graphite cannot meet the requirements of these industries for high-purity graphite. Therefore, natural graphite must be purified

The current purification method for natural graphite is still to use the high temperature resistance of graphite to improve the purity of graphite by high temperature electrothermal method. Due to the complexity of this process, it is necessary to build a large electric furnace, which is a serious waste of power resources. At the same time, it is necessary to continuously feed inert gas. costly

It is especially important that when the purity of graphite reaches 99.93%, the limit has been reached, and the fixed carbon content of graphite cannot be continuously increased.

Chinese patent application number 200410015267.4 discloses a method for purifying natural flake high-purity graphite, using oxidant and complexing agent to purify natural flake graphite under high temperature conditions, the product purity of this purification method is low, and the recovery efficiency of graphite is also low

Chinese patent application No. 94105051.3 discloses the chlorination purification process of natural graphite. This process uses the chlorine gas and the bulk material layer of the material to infiltrate or fluidize in the reaction furnace to carry out high-temperature chlorination purification under the action of permeation catalyst or reducing agent. , the purification technology is complicated and there are certain safety hazards, and the purity of the purified graphite is 98% to 99.9%. At present, no industrial production has been formed for the purification of chlorine gas.

Chinese patent application number 200610127388.7 discloses a method for the purification of ultra-high purity natural graphite. This method utilizes oxidation treatment, high temperature melting, and dealkalization to obtain 99.999% graphite. This technology has disadvantages such as complicated process and excessive selection of raw material particles.

In addition, high-temperature purification of natural flake graphite is also used at home and abroad, that is, natural graphite is put into a graphite crucible that has been graphitized for graphitization and purification. The graphite crucible has good electrical conductivity, thermal conductivity and high temperature resistance. Graphite ash powder is above 2700 °C High-temperature gasification escape, this method can increase the purity to more than 99.99%, but high-temperature graphite purification has long purification time, complicated process flow, high temperature requirements and serious waste of power resources. However, the method of chemical purification of graphite is due to backward technology , small particles of graphite cannot be recovered well, causing pollution to the environment, and the purity cannot meet the market demand for products