JPH0283205A - Manufacturing method of high purity graphite fine powder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing high-purity graphite fine powder having an impurity content of less than so ppm.

[Conventional technology]

Fine graphite powder has been widely used as a lubricant and conductive filler since ancient times, but recently it has been applied to fields such as electronics and nuclear power, and the impurity content has increased.
There is an increasing demand for graphite fine powder having high purity of ppm or less.

Conventionally, as a means for producing high-purity graphite fine powder to meet this requirement, a method of pulverizing a graphite material and treating it with high-temperature halogen gas has been adopted, and the following specific processes are known.

(1) High purification treatment in which graphite material is placed in a deashing furnace and heated while feeding halogen-containing gas such as chlorine and freon into the furnace (hereinafter referred to as "high-temperature halogen gas treatment")
After that, it is coarsely crushed using a crusher such as a hammer crusher, and further finely crushed using an atomizer or the like.

(2) The graphite material is first coarsely and finely pulverized using the same means as above, and then filled into a graphite container and subjected to high-temperature halogen gas treatment.

In these processes, "graphite material" has a particle size of 1
Block material of about 0W, "coarse pulverization" means from several to several 10
The term "fine pulverization" refers to pulverization to a powder having a particle size of 0u, and "fine pulverization" refers to pulverization to an average particle size of 1n or less.

[Problem to be solved by the invention]

Among the above-mentioned conventional techniques, process (1) can efficiently and inexpensively purify a block-shaped graphite material (impurity content: 50ρρ- or less) because it can be treated with high-temperature halogen gas as it is. It has the advantage of being able to

However, there is a drawback that the targeted high-purity graphite powder cannot be obtained due to contamination caused by wear of the hammer crusher and atomizer in the subsequent coarse pulverization and fine pulverization steps.

In addition, in the case of process (2), since the coarse pulverization and fine pulverization steps that involve contamination are performed in the first stage, high-purity graphite powder that exceeds the target level can be obtained by the high-temperature halogen gas treatment in the next step. However, the graphite fine powder after pulverization is extremely bulky and difficult to handle, and there are also problems such as a decrease in the amount of graphite packed into a graphite container during high-temperature halogen gas treatment.

The present invention was made to solve these problems, and provides a method for efficiently producing high-purity graphite fine powder containing 150 ppm or less of impurities.

[Means to solve the problem]

That is, the method for producing high-purity graphite fine powder according to the present invention is as follows:
In the method of converting graphite material into high-purity fine graphite powder by crushing and high-temperature halogen gas treatment, the first step is to coarsely crush the graphite material, the second step is to treat the coarsely crushed material to high purity with high-temperature halogen gas, and high purity. The method is characterized in that it comprises a third step of pulverizing the treated coarsely pulverized material to an average particle size of 1 μm or less by jet mill pulverization.

The graphite material used as the raw material is artificial graphite block material obtained by normal manufacturing methods, but for example, leftover materials or processing waste of graphitized products generated in the process of manufacturing large graphite electrodes for electrical steel manufacturing are used. You may use waste materials. These graphite materials are roughly pulverized using a commonly used coarse pulverizer such as a hammer crusher to a particle size ranging from a few ounces to several tens of ounces (first step).

The coarse material is filled into a container made of high-purity graphite material, set in a deashing furnace, and heated to a temperature of approximately 2000°C while feeding halogen-containing gas such as chlorine or freon into the furnace. High purification treatment by heating (second step).

Next, the coarsely pulverized product after the high-purification treatment is pulverized to a particle size of the average particle size In or less using a jet mill pulverizer (third step
There are two types of jet mill crushers: one type in which the raw materials are collided with each other using a jet stream, and the other type in which the raw materials are sprayed onto a collision plate using a jet stream.In this third process, a mechanism belonging to the former type is used. It is preferable to use one.

(Function) In the present invention, the material to be treated with high-temperature halogen gas in the second step is a granular material obtained by coarsely pulverizing a graphite material and having a particle size of about 100 nanometers, so it is easier to handle than a finely pulverized material. This makes it easier and the amount of container filling increases significantly. Therefore, it functions effectively to improve the work efficiency and treatment efficiency of high purification treatment.

In addition, in the subsequent third step, since pulverization is performed by jet mill pulverization, secondary contamination due to impurity contamination from the pulverizer system is effectively prevented. For this reason, the average particle diameter is always 1n+ or less, and the impurity content is 50ρp.
- The following high purity graphite @ powder is produced.

〔Example〕

200 kg of coarsely crushed graphite material with a particle size of 8WD or less
was filled into a cylindrical crucible-shaped high-purity graphite container, set in an electric resistance heating type deashing furnace, and heated at a temperature increase rate of 400°C/hour while circulating chlorine gas at a flow rate of 502°C/hour.
The temperature was raised to °C. After performing high purification treatment by maintaining this temperature for 10 hours, it was allowed to cool naturally.

The graphite powder after the high purity treatment is then pulverized by jet mill 4i! (Gient crusher manufactured by Seishin Enterprises, 5TJ-2
The pulverization process was repeated four times using 000).

In addition, during pulverization, ethanol (special grade reagent) was added to the graphite powder to be treated to improve the pulverization efficiency by increasing its own weight.

The high-purity graphite fine powder thus obtained was analyzed using a particle size analyzer (Micron Fort Sizer 5K, manufactured by Seishin Enterprises).
C-200O8) and the average particle size was measured using ethanol as a dispersion medium. At the same time, a fluorescent X-ray analysis bag Wl (
The impurity content was measured using Rigaku Denki Model 3370.

These measurement results are shown in Table 1 in comparison with the measurement results of commercially available high-purity graphite fine powder according to the prior art.

Table 1 Product of the present invention 0.6 Commercially available AO16 1,0 [Effects of the invention] As described above, according to the present invention, high purity graphite fine powder with an average particle size of 1- or less and an impurity content of 50 pp- or less can be constantly and efficiently produced. Because it can be manufactured, it can be safely supplied to all kinds of applications that require high purity performance, including fields such as electronics and nuclear power.

Patent applicant: Tokai Carbon Co., Ltd.

Claims (1)

[Claims] 1. In the method of converting graphite material into high-purity graphite fine powder by crushing and high-temperature halogen gas treatment, the first step is to coarsely crush the graphite material, the second step is to treat the coarsely crushed material to high purity with high-temperature halogen gas, and high-purity A method for producing high-purity fine graphite powder, comprising a third step of pulverizing the coarsely pulverized material after purification treatment to an average particle size of 1 μm or less by jet mill pulverization.