JPS6034489B2 - Manufacturing method for 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 compact using a material having an oxidation temperature lower than the oxidation temperature of the raw coke as the coke filling in the firing furnace when raw coke is molded and fired as raw material coke. In recent years, it has been reported that a high-density, high-strength carbon molded body can be obtained by using raw coke as a raw material for coke, and by grinding it, molding and firing without adding a binder.

(For example, Samurai Kaisho 51-150505 and “Prototype production of high-density hard carbon material using ground coke as raw material” Carbon” No. 93, (1978 Wang), pp. 57-62)
) This method is a secondary boiling method, in which after pulverizing coke, a binder is added, the mixture is thickened under heating, and then pressure molded. In order to reduce the carbon content, the binder pitch is impregnated under reduced pressure heating, fired again in the same manner as before, and after repeating the above-mentioned impregnation and firing operations several times, it is further heated to around 300,000 to graphitize it. In comparison, it has the advantage that a high-density, high-strength carbon molded body can be obtained economically with extremely simple operations.

The present inventors were studying the method for producing high-density, high-strength carbon compacts by the above method for the purpose of further research, and found that the firing conditions in the firing process of raw coke compacts, that is, the temperature increase rate. I encountered a fatal flaw in that there is a lower limit to .

As is well known, when firing a raw carbon molded product, a firing furnace such as a lead hammer furnace, an erema furnace, or a top charge furnace is used. In order to prevent deformation of the raw carbon molded product and to prevent oxidation, it is generally filled with time-baked petroleum coke, casting coke, etc. (hereinafter referred to as "filling coke") sized to a size of 20 or less. After firing, the filled coke is taken out by a suction machine, and then the fired carbon molded product is taken out from the firing furnace chamber. During firing, as the size of the compact increases, the internal temperature gradient increases, so in order to reduce the distortion of the compact, it is necessary to make the temperature distribution in the firing furnace as uniform as possible. Therefore, it is necessary to reduce the firing rate. Nevertheless, in the firing of compacts using raw coke as raw coke, if the heating rate is reduced, the
・Irrespective of the method, the problem of cracks occurring in the molded body was encountered.

The existence of a lower limit on the heating rate means that it is impossible to fire a large compact, which is fatal to the firing of a compact made from raw coke.

The inventors of the present invention conducted intensive studies to find out what causes this phenomenon, and found that the raw material coke for conventional compacts and the filling coke used during firing are fried coke. The oxidation initiation temperature at is approximately 4000
0 and oxidation starts at the same time, so the oxygen in the firing furnace has almost no effect on the compact. However, if the raw material coke is raw coke, oxidation starts at around 1000C, so it is difficult to use as filling coke. When using Akatsuki coke,
Filled coke does not exhibit a substantial oxidation-preventing effect up to approximately 40,000 ml of coke, and the green coke compact may be preferentially oxidized and cracks may occur, or the degree of oxidation differs between the surface layer and the inside of the compact, resulting in a decrease in the shrinkage rate during the firing process. It has been speculated that the cause of the difference is the occurrence of cracks.

Based on such speculation, the present inventors conducted extensive studies on how to prevent the oxidation of green coke molded bodies and obtain crack-free fired bodies. The present inventors have discovered that a high-density carbon molded body free of the above-mentioned defects can be obtained by using a mixture of the substance and fried coke as filling coke, and have completed the present invention.

That is, in producing a high-density carbon compact by pulverizing raw coke, molding and firing, the present invention uses a substance having an oxidation temperature lower than the oxidation temperature of the filled coke during firing, or a mixture of the substance and shrimp coke. An object of the present invention is to provide a method for producing a high-density carbon molded body, which is characterized by using and firing a mixture of the following.

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

The raw carbon molded body to which the method of the present invention is applied is a raw coke carbon molded body using raw coke as the raw coke, and the proportion of raw coke in the raw coke is at least 5% by weight, more preferably 8% by weight. % or more, there are no restrictions regardless of whether or not a binder is used, but
Normally, raw coke with a volatile content of 5% or more is ground and the crushed product is 1
It is suitable for firing so-called pindaleless carbon molded bodies which are spherical particles with rounded corners when observed under a microscope and are pressure-molded without adding a binder.

The firing furnace used for firing may be any known furnace used for firing raw carbon compacts, such as a lead hammer furnace, top charge furnace, elema furnace, or tunnel kiln.The raw carbon compact is inserted into the firing furnace, and the surrounding It is used by filling the void with filler coke to prevent oxidation and deformation. In carrying out the method of the present invention, a substance having an oxidation temperature lower than the oxidation temperature of raw raw coke or a mixture of the substance and burnt coke is used as the filling coke.

Such materials include raw coke, fingers, pulp layers, wood chips, grains, charcoal, carbon black, polymer compounds, and the like.

However, when the substance is used alone as filling coke, only raw coke is used, and other substances are used as a mixture with roasted coke. The amount of the above-mentioned substances to be mixed and present in the baked coke cannot be determined unambiguously because it varies depending on the oxygen concentration in the firing furnace, the amount of packed coke and its particle size distribution, and the rate of temperature increase during firing, but at least it depends on the total amount of packed coke. It is sufficient if the amount is 5% by weight or more.

If the mixing amount is small, the effect of preventing cracks will be small, which is not preferable.

The time-baked coke to be mixed and used as filling coke may be any type of coke conventionally known as filling coke in this technical field, and usually petroleum coke or cash coke sized to a size of 2 or less is used. .

On the other hand, the shape of a substance that has an oxidation temperature lower than that of raw coke is paper-like and cannot be generalized, but it is usually cut into pieces of two ships or less so that they can be separated from each other or eaten by shrimp. It is suitable because it is easy to mix with burnt coke and has improved oxygen blocking ability.

After filling the void around the raw carbon compact in the firing furnace with raw coke in this way, or mixing the raw coke with raw coke and/or a substance other than raw coke that has a lower oxidation temperature than raw coke. After filling with at least 400
The temperature increase rate to oo is 100℃/Hr or less, usually 70℃
Calculating the green coke molded body at a temperature of 0 to 140,000,
Just boil it out.

According to the method of the present invention described in detail above, raw coke or a substance having an oxidation temperature lower than the oxidation temperature of raw coke is mixed with burnt coke and applied as filling coke, which is extremely simple. This method has made it possible to obtain crack-free carbon compacts without reaching the lower limit of the temperature increase rate, regardless of the size of the raw carbon compact to be fired, and its industrial value is extremely large. be.

Example 1 Commercially available petroleum raw coke with a volatile content of 13%, S content of 0.6, and ash content of 0.1% was placed in an alumina bowl 2 on the 20th side.
．． 200 g of the above-mentioned raw coke and 6 g of methyl alcohol were placed in a 6 kg ball mill with a capacity of 3 g and ground for 1 hour.

Raw coke after crushing (average particle size 5 french) is 200k9/
A molded product with a diameter of 7 cm and a height of 6 cm was obtained by manual embossing.

Using an electric resistance furnace having a core tube with an inner diameter of 13.5 cm and a height of 35 cm, a 14 cm filled coke was inserted into the bottom of the core tube, the molded body was placed in the center, and the surrounding area was After covering the void with filling coke, 14
After inserting the skin filling coke and covering the filling coke with bricks, the temperature was raised to 100,000 at 500/Hr.

The filled coke used at this time was the same raw coke (average particle size: 1 Yanagi) as used for the molded body, but the fired body obtained had an apparent specific gravity of 1.72, no cracks, and a metallic luster on the surface. Was. When the compact was fired in the same manner as above except that burnt petroleum coke (average particle size: 1 Yanagi) was used as the filling coke, the obtained compact broke into two due to cracks, and the surface Numerous small cracks were also observed. Example 2 Molding and firing were carried out in the same manner as in Example 1, except that the size of the molded body, the temperature increase rate during firing, and the filling coke were changed to the conditions listed in Table 1.

The results are shown in Table 1. Table 1: Appearance of fired body ○......Cracks △...
...Some cracks ×...Cracks As shown in Table 1, when the temperature rise rate is low and when bran coke is used as filling coke, cracks occur in the fired body regardless of the size of the compact. According to the method of the present invention using raw coke, even when the temperature increase rate is low, it is possible to sinter the compact without causing cracks in the compact.

Example 3 When the molded body was fired in the same manner as in Example 1 except that a mixture of casting coke (average particle size 1 bar) and wood chips were used at a weight ratio of 8:2 as the filling coke, the molded body cracked. I was able to bake it without any problems.

Claims (1)

[Scope of Claims] 1. A substance or substance having an oxidation temperature lower than the oxidation temperature of raw coke as filling coke during firing when raw coke is pulverized, molded and then fired to produce a high-density carbon compact. A method for producing a high-density carbon molded body, characterized by firing a mixture of and burnt coke. 2. The high-density carbon molded article according to claim 1, wherein the substance having an oxidation temperature lower than the oxidation temperature of raw coke is raw coke, paper, pulp waste, wood chips, grain, charcoal, carbon black, or a polymer compound. manufacturing method. 3. The method for producing a high-density carbon molded body according to claim 1, wherein the substance having an oxidation temperature lower than the oxidation temperature of raw coke is raw coke.