JPS6034488B2 - Method for manufacturing high-density carbon molded bodies - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing a high-density carbon molded body.

More specifically, the present invention relates to a method for producing a high-density carbon molded body without using a binder by crushing raw coke. In recent years, raw coke has been used as a coke raw material,
It has been reported that by grinding this, a high-density, high-strength carbon molded body can be obtained by molding and firing without adding a binder.

(For example, JP-A-51-150505 and “Prototype production of high-strength hard carbon material using ground coke as raw material” (“
Carbon”, M. 93 (1971), pp. 57-62]) This method is a conventional method in which the coke is crushed, a binder is added, the mixture is kneaded under heat, and the molded product is formed under pressure. 1
After firing at 000 to 1400oC, impregnating the fired product with binder pitch under reduced pressure heating to reduce pores, and firing again in the same manner as before, repeating the above impregnation and firing operations several times, Furthermore, it has the advantage of being more economical and easier to operate than the method of graphitizing by heating to around 300,000 ℃.

However, the above-mentioned method for producing carbon molded bodies without using a binder requires the raw coke to be finely pulverized by a grinding method, and the grinding method using an industrially common ball mill etc. It has been reported that the shape is irregular and angular, making it difficult to pack tightly, and even when molded, it must be held under high pressure for a long time in order to obtain a high-density product.

Examples of grinding-type grinders include foot thickeners, day-grinding grinders, and centrifugal mills, but compared to conventional ball mills and other grinders, these types of grinders have a faster relationship between the material to be ground and the grinding media. Because the contact area is extremely small, the grinding capacity per unit time is extremely low and is not practical for grinding that requires long grinding.
In addition, when raw coke, which has a certain degree of viscosity and silkiness, is ground, it tends to form cracker-like lumps, which also has disadvantages in terms of handling.

In view of this situation, the inventors of the present invention conducted intensive studies to establish a method for crushing raw coke as a raw material for carbon molded bodies without using an industrial binder, and as a result, they decided to make the raw coke contain a specific additive. The inventors have now completed the present invention by discovering that the desired raw coke powder can be obtained even when a ball mill with high crushing capacity is used.

That is, the present invention provides a high-density carbon molded body, which is characterized by adding at least one of methyl alcohol, ethyl alcohol, and propyl alcohol to raw coke, pulverizing it in a ball mill, and then molding and firing without using a binder. To provide a manufacturing method.

The method of the present invention will be explained in more detail below.

The raw coke used in the present invention usually has a volatile content of 5% or more, and more preferably has a volatile content of 10 to 10%.
16% raw coke is suitable.

If the volatile content is less than 5%, the raw coke from which high-density carbon compacts can be obtained will not be obtained even if it is finely pulverized; It is undesirable because it causes blisters on the body. Examples of such raw coke include petroleum raw coke calcined at about 50,000 ℃. Grinding of the raw coke is carried out in the same manner as in conventional grinding methods, by inserting the raw coke into a ball mill and adding at least one of methyl alcohol, ethyl alcohol, and propyl alcohol.

The amount of alcohol added to the raw coke is 0.1% by weight or more, more preferably 0.5 to 7% by weight.

If the amount of the alcohol relative to the raw coke is less than 0.1% by weight, it will not be possible to obtain a product with substantially uniform pulverized particle size and high apparent specific gravity after molding, and on the other hand, the upper limit of the amount of alcohol to be added is particularly limited. However, if the amount added is too large, the condition will be similar to wet pulverization, and an extra step of removing alcohol after pulverization will be required, so the decision should be made in consideration of economic efficiency. Generally, in the field of grinding, glycerin, paraffin, polyethylene glycol, butyl alcohol, amyl alcohol, hexyl alcohol, cyclohexanol, acetone, hexane, stearic acid, oleic acid, cod liver oil, etc. are used as grinding aids for cement clinker, alumina, etc. Beef tallow, aluminum stearate,
Mixtures of arylalkylsulfosic acids, trietanolamin salts, and calcium salts of guninsulfonic acid are known, but even if raw coke is crushed using these known crushing aids, high coke can be obtained without using a binder. It is not possible to use raw coke to obtain dense carbon compacts.

In the present invention, the pulverization is carried out for 2 hours or more, preferably 5 hours or more, and the pulverized product usually has a size of 5 to 10 particles or less, and the particle shape should be spherical with rounded corners when observed under a microscope.

The crushed raw coke may then be pressure-formed by a known method such as molding, rubber press molding, etc., and then fired.

Of course, it is also possible to add small amounts of polyethylene glycol, water, stearic acid, coal tar pitch, and other molding aids during molding. The carbon material obtained in this way has high density and high strength, and can be used for electric discharge machining electrodes, electrical applications such as contacts, mechanical fittings such as mechanical seals and rings, metallurgical applications such as continuous casting nozzles, or cores of nuclear reactors. It can be conveniently applied to materials, moderators, etc.

According to the method of the present invention described in detail above, compared to a grinding-type grinder, a carbon molded product is produced without using a binder by using a ball mill with a large grinding capacity and using a very simple method of adding a specific grinding aid. It has made possible the production of , and its industrial value is enormous.

The method of the present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Volatile content 12%, SO. 8%, ash 0.1%,
After drying the commercially available raw coke containing 0.8% ratio for 1 hour at 10,000 to reduce the ratio to 0.1% or less, 200g of the above-mentioned raw coke and methyl alcohol were placed in a ball mill with 2.6k9 alumina balls of 2.0%. Insert the key 15
Time crushed.

The raw coke after pulverization (average particle size: 5 French) was compression molded using a mold with an inner diameter of 2Q◇ at a pressure of 2000 k9/m, and then the molded body was salted to 1000 k9/h at a heating rate of 3000 C/Hr. Then, the obtained fired body was further heated at 2800oC.
graphitized. Table 1 shows the physical properties of the sample obtained at this time.

In addition, as a comparative example, raw coke was crushed using the same ball mill without adding methyl alcohol, and raw coke was crushed using a Tachibana thickener as a crushing means, and was molded, fired, and graphitized in the same manner as above. The physical properties of the samples obtained are also shown in Table 1. Table 1 As is clear from Table 1, when methyl alcohol is used as a grinding aid, powdered raw coke is obtained which has physical properties comparable to those obtained by grinding with a kettle. It turns out that it is possible.

Example 2 Raw petroleum coke was crushed, molded, and calcined in the same manner as in Example 1, except that the crushing aid shown in Table 2 was used, and the appearance of the molded body and the apparent specific gravity of the 1000oo calcined product were measured. It was measured.

The results are shown in Table 2. Table 2 Appearance evaluation is based on the following criteria.

◎ Smooth outer surface with no unpulverized powder mixed in ○ Smooth outer surface although slightly rough △ Rough skin due to some unpulverized powder mixed in × Rough skin all over Example 3 Volatile content 14%, SO. 4%, ash 0.15%, day 207
A commercially available raw coke containing LK9 was inserted into a ball mill with 13K9 alumina balls (2 x ◇) without drying, and pulverized for 1 hour after adding 2 portions of ethyl alcohol.

Claims (1)

[Claims] 1. A high-density carbon characterized by adding at least one of methyl alcohol, ethyl alcohol, and propyl alcohol to raw coke, pulverizing it in a ball mill, and then molding and firing without using a binder. Method for manufacturing a molded object. 2. The method for producing a high-density carbon molded body according to claim 1, wherein the ball mill is a normal ball mill, a rod mill, a tube mill, a vibrating ball mill, or a conical mill.