JPH02221108A - Production of activated carbon - Google Patents

Abstract

PURPOSE:To easily and inexpensively produce good quality activated carbon from caking coal by adding rice bran to pulverized coal, carbonizing the mixture, crushing and grading the carbonized material and then activating the graded material. CONSTITUTION:Rice bran is added by 1-40wt.% to pulverized coal having preferably <=74mum grain size. The mixture is charged into a carbonization furnace, heated to about 700 deg.C and carbonized. When the caking property is low, the mixture is press-formed, and the granulated coal is heated to about 600 deg.C in the carbonization furnace and carbonized. The carbonization product is preferably graded to 5.0-0.3mm grain size in accordance with the grain size of the desired activated carbon. When the granulated coal is oxidized and carbonized, the granulated coal is charged into a reaction vessel held at 100-310 deg.C and carbonized in the gaseous mixture contg. 1-22vol.% O2. The carbonization product is then activated by the conventional method to obtain activated carbon. The activated carbon is used in water treatment and as a solvent adsorbent and a gasoline adsorbent.

Description

[Detailed description of the invention] Field of use in Ea industry] The present invention relates to a method for producing activated carbon.

Activated carbon produced by this method is used to remove harmful substances in water and wastewater, and to absorb volatile organic substances such as gasoline or odors.

[Prior Art] Activated carbon using coal as a raw material is produced by producing a carbide and activating this carbide using various methods.

In this case, in order to produce high-quality activated carbon, it is important to select raw material coal and process it in the process of producing carbide so that the coal does not soften and melt, forming carbides with thick pore walls and a small specific surface area. .

For this reason, various methods have been proposed in the past. That is, JP-A-50-51996 discloses the production of activated carbon by retiring coal having weak or no caking properties, such as abrasive coal such as lignite, which does not soften or melt even when heated. However, when these brown coals are used as raw materials, a binder is required. In addition, JP-A-50-125989 shows an example using Black Creek coal from Alabama, USA, but in this case, a naphthalene sulfonic acid formalin condensate or its salt was added in the presence of water. It is used as a binding agent. Thus, some kind of binder is used in these methods of producing activated carbon. The use of these binders complicates the activated carbon manufacturing process and increases cost. On the other hand, JP-A-50-152993 proposes a method in which agglomerated granulated coal is treated with an oxygen-containing gas without using a binder.

As described above, currently known methods for producing activated carbon include a method using coal that does not melt during the carbonization process, or a method in which caking coal is made infusible with an oxygen-containing gas and then carbonized and activated to produce activated carbon. It is.

[Problems to be Solved by the Invention] However, in these known activated carbon production methods, the selection range of activated carbon raw material coal is narrowed. In addition, when caking coal is used, it is made infusible by oxygen-containing gas, so the progress of oxidation differs between the surface and inside of the agglomerated coal, making it difficult to produce homogeneous infusible agglomerated coal. If agglomerated coal is to be produced, the oxidation treatment time must be prolonged, which is not economical. From the above points, it is important and strongly desired to establish a method for simply and inexpensively producing high-quality activated carbon from coking coal.

[Means for Solving the Problems] In order to achieve the object, the present invention adds 1% or more but less than 40% by weight of rice bran to pulverized coal, carbonizes it in a carbonization furnace, and crushes and granulates it. After that, activating the coal, and adding 1% by weight or more and less than 40% by weight of rice bran to the pulverized coal, making it into granulated coal, carbonizing it in a carbonization furnace, and then activating it, or adding rice bran to the pulverized coal. 1% by weight or more, 4
After adding less than 0% by weight, the granulated coal is made into granulated coal using an oxidizing gas with an oxygen concentration of 1% by volume or more and less than 22% by volume,
It is characterized in that it is oxidized at 100° C. or higher and lower than 310° C., then carbonized in a carbonization furnace, and then activated.

The present invention will be explained in detail below.

A wide range of coals, from lignite to anthracite, are used as raw materials for coal-based activated carbon. However, in the production of high-grade activated carbon, granulated coal is used, which is made by finely pulverizing coking coal and granulating it.

Therefore, in order to prevent the softening and melting phenomenon of granulated coal during the carbonization process, the granulated coal is infusible using an oxygen-containing gas. This has the disadvantage that the treatment time becomes long and it becomes difficult to achieve homogeneous infusibility treatment.

Therefore, the present invention makes it possible to uniformly and quickly infusify the granulated coal by performing the infusibility treatment of the caking coal from the inside of the granulated coal, or from the inside and outside simultaneously, or by using oxygen. This discovery was made after conducting various studies to safely conduct the process without infusibility treatment.

The pulverized coal according to the present invention may be slightly caking coal, caking coal alone, or non-caking coal or coal blended with caking coal, etc., and is pulverized coal, preferably pulverized to a size smaller than 74 μm. Coal is good.

The reason why rice bran is added is because of the generation of oxidizing gas during the heating process of rice bran, and because it does not soften or melt, it prevents strong fusion between coal particles and creates macro pores that allow activation gas to easily diffuse into the interior of carbides when activating carbides. This is to form.

The amount added to coal is specified to be 1% by weight or more and less than 40% by weight, because if it is less than 1% by weight, sufficient macropores cannot be formed in the carbide.

The upper limit is set to less than 40% by weight because if it is added in an amount of 40% by weight or more, the mechanical strength of the granulated carbon decreases, pulverization occurs during the activated carbon manufacturing process, and the yield of activated carbon decreases significantly, which is not economical. The average particle size of rice bran is 100.
Although a particle size of less than μm is preferable, since rice bran is compressed when pressure molded, the particle size produced during current rice milling may be used.

Mixed charcoal of coal and rice sugar is charged as it is or compressed into a carbonization furnace and heated to approximately 700℃ to carbonize it, or if it has low caking properties or requires a dense charcoal, it is pressed and molded. The granulated coal is then heated to approximately 600°C in a carbonization furnace and carbonized. Furthermore, when mechanical strength is required, a binder such as tar or pitch may be added.

The particle size of the generated carbide must be adjusted according to the particle size of the target activated carbon. Its particle size is S, Omm~0.3m
In addition, when granulated coal is carbonized by oxidation treatment, it is charged into a reaction vessel maintained at a temperature of 100°C or higher and lower than 310°C, and an oxygen concentration of 1% or more by volume and 22% by volume of ungrooved coal is used. Granulated coal is oxidized with mixed gas. Granulated coal with oxygen concentration of 1
The reason why the oxidation treatment is carried out using an oxidizing gas of vol.% or more and less than 22 vol.% is to quickly make the outer surface of the granulated coal infusible, prevent the granulated coal from fusion with each other, and speed up the infusibility of the coal. be. In this case, the temperature of the reaction treatment equipment is set to 100°C or higher,
The reason for specifying the temperature to be less than 310°C is that if it is less than 100°C, the oxidation of the granulated coal will be difficult to proceed, and if it is more than 310°C, the oxidation reaction will rapidly proceed and generate heat, making it difficult to control the temperature 11J, which is not preferable. The reason why the oxygen concentration of the gas was specified to be 1% by volume or more and less than 22% by volume was because if the oxygen concentration was around 1%, the oxidation reaction would be slow and it would take a long time to oxidize the granulated coal, making it uneconomical. If it is more than % by volume, the oxidation reaction will proceed rapidly and the temperature will become high, making it difficult to control the temperature, which is not preferable.

When oxidizing granulated coal in this way, the oxygen concentration of the mixed gas, the temperature, and the heating conditions of the reaction vessel must be adjusted so that the temperature of the granulated coal in the reaction vessel is maintained at 100°C or higher and 310°C. However, in the present invention, since the coal becomes infusible from inside the granulated coal, homogeneous infusible granulated coal is produced. In addition, residual carbon in rice bran prevents coal particles from fusing together and forms pores suitable for activation and adsorption. The reaction vessel may be either a batch type or a continuous type such as a rotary furnace.

The infusible granulated carbon is carbonized to about 600° C. by a conventional method, and then activated by a conventional method to produce activated carbon.

As described above, the present invention is to simplify the infusibility of coal and produce carbide by adding rice bran to finely pulverized coal. The carbide produced by the method of the present invention is activated by a known method such as steam or CO to obtain activated carbon.

[Example] Next, the present invention will be explained based on an example. Table 1 shows the properties of the coking coal and rice bran used.

Table 1 Example 1 Coal A pulverized to 74 μl or less 50% by weight, Coal 8
Add 20% by weight of rice bran to 30% by weight to make an internal volume of 400+a
200g of the material was charged into an ffi carbonization furnace, heated to 700°C at a heating rate of 3°C/akin, held for 30 minutes, and taken out to form a carbide. The carbide produced in this way was sized to 3 to 0.5 cm, and 50 g was charged into a reaction tube with an internal volume of 200 (1 mfi), heated at 900°C, and the amount of water vapor was 4 g/so in.
It was time-activated and made into activated carbon. The specific surface area of the produced activated carbon was measured and found to be 1231 m" and 7 g.

Example 2 - 85% by weight of coal pulverized to less than 74 μm and rice s15
After adding % by weight, pressure molding and agglomeration, 5 to 0.5 ■■
The coal was sized and made into granulated charcoal. This granulated coal is placed in an electric furnace with a layer thickness of 5cm.
Charge N2 gas so that it is about 1041/m1n
While passing 1. The temperature was raised to 600° C. at a heating rate of s° C./sin to form a carbide. This carbide was activated in the same manner as in Example 1 to obtain activated carbon. The specific surface area of the produced activated carbon was measured and found to be 7 g.

Example 3 After oxidizing the granulated coal produced under the conditions of Example 2 at an oxidation temperature of 250°C and an oxygen concentration of 5% by volume for 2 hours,
The material was charged into an electric furnace so that the layer thickness was about 5 layers, and the temperature was raised to 600° C. at a heating rate of 3° C./+gln while passing N2 gas at 1 ON/min to form a carbide. This carbide was activated by the method of Example 1 to obtain activated carbon. The specific surface area of the produced activated carbon was measured x: +37 m'/g.

Example 4 Granulated coal produced under the conditions of Example 2 was oxidized for 2 hours at an oxidation temperature of 300°C and an oxygen concentration of 1.5% by volume, and then charged into an electric furnace to a layer thickness of approximately 5 mm. ShiN
2 gas 104! /2.5℃/win while passing through rain
The temperature was raised to 600° C. at a heating rate of 200° C. to form a carbide. This carbide was activated by the method of Example 1 to obtain activated carbon. The specific surface area of the produced activated carbon was measured and found to be 1185 m" and 7 g.

Example 5 30% by weight of rice bran was added to 70% by weight of coal A pulverized to 74 μm or less, and after pressure molding and agglomeration, 5 to 0.5 μm
The charcoal was sized to give granulated charcoal. This granulated carbon is oxidized at a temperature of 12
After oxidation treatment for 0.5 hours at 0°C and oxygen concentration of 20% by volume, the electric furnace was charged so that the C layer thickness was approximately 5Ilra, and heated at 2.5°C while passing N2 gas IO exchange/+in.
The temperature was raised to 600°C at a heating rate of /min to form a carbide. This carbide was activated by the method of Example 1 to obtain activated carbon.

The specific surface area of the generated activated carbon was measured and was 1323 m.
, 'g.

Example 6 5% by weight of rice bran was added to 95% by weight of coal A pulverized to 74 μl or less, and the mixture was pressure-molded and agglomerated, and then 5 to 0.5 m
The charcoal was sized to obtain granulated charcoal. This granulated carbon is oxidized at a temperature of 280
After being oxidized for 3 hours at ℃ and oxygen concentration of 8% by volume, it was charged into a carbonization furnace with an internal volume of 400mM and heated at 2℃.
The temperature was raised to 600° C. at a heating rate of /min, maintained for 30 minutes, and then taken out to form a carbide. The carbide produced in this way is sized to a size of 3 to 0.5 mm, and 50 g is sized to an inner volume of 2 ooom.
The amount of water vapor is 4gz at 900℃.
'mtn for 3 hours to obtain activated carbon. The specific surface area of the produced activated carbon was measured and found to be 1211 m'/g.

Comparative Example 1 55% by weight of rice bran was added to 45% by weight of coal A pulverized to 74 μm or less, and the internal volume was 200 iF! 100 in the carbonization furnace
The temperature was raised to 600° C. at a heating rate of 2° C./min, held for 30 minutes, and then taken out to form a carbide. The thus produced carbide was sized to a size of 3 to 0.5 mm, 50 g of it was charged into a reaction tube with an internal volume of 2000 mL, and activated at 900° C. for 3 hours at a steam rate of 4 g/min to obtain activated carbon. Most of the generated activated carbon was pulverized and could not become granular activated carbon.

Comparative Example 2 399.7% by weight of coal crushed to 74 μm or less was mixed with rice
o, 3% of Ji was added to a carbonization furnace with an internal volume of 200.
0 g was charged, the temperature was raised to 600° C. at a heating rate of 2° C./1 lin, and after holding for 30 minutes, it was taken out and made into a carbide.

The thus produced carbide was sized to 3~0.5+nn+, 50g was charged into a reaction tube with an internal volume of 2000a+ffi, and the amount of water vapor was 4g/min at 900℃.
It was activated for 3 hours to make activated carbon. The specific surface area of the produced activated carbon was measured and found to be 340 m" and 7 g, indicating that the activated carbon could not be of good quality.

Comparative Example 3 When an attempt was made to oxidize the granulated carbon produced under the conditions of Example 2 at an oxidation temperature of 280° C. and an oxygen concentration of 25% by volume, the granulated carbon generated heat, making it impossible to produce activated carbon.

Comparative Example 4 For comparison with the present invention, an attempt was made to produce activated carbon using a conventional method. That is, caking coal A crushed to −74 μm or less was pressure molded and then crushed to size 2 to 0.5 μm to obtain granulated coal. This granulated carbon was heated at an oxidation temperature of 280℃ and an oxygen
After being oxidized for 5 hours at 5% by volume, it was charged into an electric furnace with a layer thickness of about 5mm and heated with N2 gas ION/
The temperature was raised to 600° C. at a heating rate of 3° C./min while the temperature was increased to form a carbide. This carbide was activated by the method of Example 1 to obtain activated carbon. The specific surface area of the produced activated carbon was measured and found to be 803+27 g.

As shown in the Examples and Comparative Examples above, a carbide for activated carbon can be simply produced by the method of the present invention, that is, by adding rice bran to pulverized coal.

As explained above, by the method of the present invention, that is, by adding rice bran to pulverized coal, a carbide for activated carbon can be easily produced, and the activated carbon produced from this carbide can be used as activated carbon for water treatment, solvent adsorption, or Can be used as a gasoline adsorbent.

4 others

Claims (1)

[Claims] 1. Rice bran added to finely ground coal at 1% by weight or more, 40% by weight
1. A method for producing activated carbon, which comprises adding less than 100% of activated carbon, carbonizing it in a carbonization furnace, crushing and sizing it, and then activating it. 2. Add rice bran to finely ground coal at 1% by weight or more, 40% by weight.
1. A method for producing activated carbon, which is characterized in that after adding less than 10% of carbon, the carbon is granulated, carbonized in a carbonization furnace, and then activated. 3 Add rice bran to finely ground coal at 1% by weight or more, 40% by weight
After adding less than
above, using less than 22% by volume of oxidizing gas at 100°C.
As described above, the method for producing activated carbon is characterized in that after being oxidized at a temperature of less than 310°C, carbonization is performed in a carbonization furnace, followed by activation.