JP2005231945A - Production method for woody granular active carbide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a woody granular active carbide having a high strength and a large specific surface area from a woody raw material. <P>SOLUTION: A raw material prepared by adding a binder to a mixture of a woody carbide powder and a coal powder is subjected to kneading, molding, carbonization, and activation, thus producing the woody granular active carbide. Preferably, 100 pts.mass woody carbide powder is compounded with 10-100 pts.mass coal powder. Preferably, 100 pts.mass as the sum of the woody carbide powder and the coal powder is compounded with 40-90 pts.mass binder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a wood-based granular activated carbide using wood as a raw material, and in particular, a high-strength wood-based granular activated carbide excellent in adsorption characteristics, which can use various wood such as waste wood as a main raw material. It relates to a manufacturing method.

  Activated carbon has various forms depending on its production method and application, and in general, powdered activated carbon, granular activated carbon, fibrous activated carbon, sheet-like activated carbon and the like are well known. Of these, granular activated carbon is most widely used in various fields such as exhaust gas purification and water purification because of its ease of handling when used.

  The most well-known raw materials for activated carbon include coconut husk and coal. Recently, active carbon production utilizing various wastes has been actively studied from the viewpoint of effective use of resources. In particular, wood waste such as building wastes, scraps generated from sawmills, sawdust, thinned wood, felled trees, and pruned waste are suitable as raw materials for activated carbon because they do not contain undesired impurities.

  However, it is extremely difficult to obtain high-strength granular activated carbon from these woods, and the current situation is that it remains in powdered activated carbon. This is because the porosity of the obtained carbide is large and the bulk density is low because the cellular structure of the wood has many voids. A method of obtaining granular activated carbon with high strength by destroying such a woody structure by pulverization has also been proposed, but considering such pulverization energy, it is considered to be impractical.

On the other hand, in Patent Document 1, organic waste such as waste wood, waste bamboo, waste paper, corn core and used plastic is used as a raw material, and crushing, preliminary dry distillation, humidity conditioning, binder addition, kneading, molding, dry distillation A method for producing granular activated carbon by performing each treatment is disclosed. In this method of producing granular activated carbon, in order to improve the cold strength of the molded product and the strength of the carbonized carbon after carbonization, the binder is used as a binder, such as cement for inorganic systems, and coal tar heavy oil, pitch, coal for organic systems. Selection is made from liquefied oil, petroleum-based vacuum residue from a specific oil system, ethylene bottom oil, reformed oil, etc., and the addition ratio is adjusted.
JP 2003-183667 A

However, although the granular activated carbon obtained by the above method can secure a certain level of strength, its specific surface area is as low as around 250 m ² / g, so that the use as activated carbon is limited.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a method for producing a wood-based granular activated carbide using wood as a raw material and having a high strength and a large specific surface area.

  As a result of intensive studies to solve the above problems, the present inventors added an appropriate amount of coal powder known as a raw material for high-strength granular activated carbon to the wood carbide powder, We have found that a wood-based granular activated carbide with high strength and a large specific surface area can be obtained by molding, carbonizing and activating, using as a raw material a mixture of an appropriately selected binder in the mixture, and completing the present invention. It came to do.

  That is, the first aspect of the present invention is a method for producing a granular activated carbide, characterized in that, in the method for producing a granular activated carbide, a material obtained by adding a binder to a wood carbide powder and a coal powder is used as a raw material. (Claim 1).

  In the said invention (invention 1), it is preferable to mix | blend 10-100 mass parts of coal powder with respect to 100 mass parts of wood carbides (invention 2).

  Moreover, in the said invention (invention 1 and 2), it is preferable to mix | blend 40-90 mass parts of binders with respect to 100 mass parts of total amounts of wood carbide powder and coal powder (invention 3).

  In the above invention (Inventions 1 to 3), the binder is at least one selected from the group consisting of coal tar, anhydrous tar, soft pitch, hard pitch, creosote oil, wood tar, wood tar oil and wood tar pitch. A seed binder is preferred (claim 4).

  2ndly this invention provides the wood type granular activated carbide manufactured by the manufacturing method which concerns on the said invention (Invention 1-4) (Invention 5). The wood-based granular activated carbide according to the present invention includes wood-based granular activated carbide produced by a method different from the production method according to the above inventions (inventions 1 to 4) as long as they are the same as the product. And

  According to the method for producing a wood-based granular activated carbide of the present invention, wood, building dismantling waste wood, millwood generated from sawmills, chips, sawdust, or wood such as felled trees and pruned trees are mainly used. It can be used as a raw material, and a wood-based granular activated carbide having a high strength and a large specific surface area equivalent to granular activated carbon obtained from coal can be produced.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a process flow diagram showing an embodiment according to the method for producing a woody granular activated carbide of the present invention.

  Regardless of whether it is waste or virgin material, the wood used as the raw material for the wood carbide used in this manufacturing method is all timber, building dismantling waste wood, scraps generated from sawmills, Any woody material such as chips, sawdust, or felled trees or pruned trees can be used. However, according to the present invention, the desired woody granular activated carbide can be obtained by using any woody material. Therefore, considering the recent environmental problems of resources, waste with low utility value such as construction waste wood can be obtained. It is preferable to utilize.

  First, the raw material wood is crushed (step 1). At this time, since the wood can be carbonized more uniformly and efficiently if it is crushed as finely as possible, it is preferable to crush the wood so that its size (long side or long diameter) is 100 mm or less, particularly 50 mm or less. In addition, when the wood is extremely hydrated, the wood is dried before crushing or after crushing (step 2), and the moisture content of the wood is usually 30% or less, preferably 10% or less.

  When the crushed and dried wood is obtained as described above, the wood is carbonized (primary carbonization) to obtain wood carbide (step 3). The primary carbonization treatment is preferably performed at 200 to 800 ° C., and the treatment method may be a continuous method or a batch method. The heating method may be either an external heating method or an internal heating method.

  Further, the atmosphere in the furnace for performing the carbonization treatment is preferably an anaerobic atmosphere in which oxygen does not exist or a partially oxidized atmosphere having an oxygen concentration of 10% or less. By making the furnace atmosphere anaerobic, combustion of the raw material is suppressed, and the recovery rate of the wood carbide is improved. On the other hand, in the partially oxidized atmosphere, a part of the raw material is combusted, so that the recovery rate of the wood carbide is reduced.

  In the primary carbonization treatment, the volatile content contained in the obtained wood carbide is preferably 30% or less, particularly preferably 20% or less. Considering that the granular activated carbide obtained by this production method is used at high temperatures such as for exhaust gas treatment in industrial furnaces, the activated carbon of the activated carbon that is produced has a low igniting point and the activated carbon is ignited. Therefore, it is preferable to reduce the volatile content in the wood carbide as much as possible in the primary carbonization step.

  Further, the carbonization degree of the wood by the primary carbonization treatment is preferably set to such a degree that the fibrous material in the wood is carbonized and disappears to such an extent that the next pulverization treatment is not hindered.

  The wood carbide discharged from the furnace in the primary carbonization treatment is quickly cooled to prevent combustion (step 4).

  After the wood carbide is cooled, a pulverization process is then performed to obtain a wood carbide powder (step 5). In this pulverization treatment, pulverization is performed so that the particle size of the wood carbide is usually 50 μm or less, preferably 30 μm or less. The smaller the particle size of the wood carbide, the higher the strength of the granular activated carbide obtained. The degree of pulverization may be appropriately determined in relation to the pulverization cost. The grinding method of the wood carbide is not particularly limited, and a general ball mill or roller mill used for coal grinding can be used.

  When the wood carbide powder is obtained as described above, coal powder is added to the wood carbide powder (step 6). There are no particular restrictions on the classification or brand of coal, but generally ash has a small specific surface area, so in order to increase the specific surface area of the granular activated carbide obtained, coal with a low ash content, specifically Specifically, it is preferable to use coal having an ash content of 20% or less. The particle size of the coal powder is usually 50 μm or less, preferably 30 μm or less, like the particle size of the wood carbide.

  The amount of coal powder added to 100 parts by mass of the wood carbide powder is preferably 10 to 100 parts by mass. The effect which improves the intensity | strength of the granular activated carbide obtained as the addition amount of coal powder is less than 10 mass parts is small. On the other hand, if the amount of coal powder added is less than 100 parts by mass, the physical properties of the obtained granular activated carbide will not be deteriorated, but the amount of wood used as a raw material will be reduced, making it impossible to effectively use the wood. In addition, when a waste material is used as wood, the cost increases due to a decrease in the amount of wood used.

  Next, a molding binder is added to the mixture of the wood carbide powder and the coal powder and kneaded (step 7). As the molding binder, a coal-based oil which is a general binder for producing activated carbon, such as coal tar, anhydrous tar, soft pitch, hard pitch or creosote oil, or wood-based oil such as wood tar, wood tar oil or It is preferable to use one or more of wood tar pitches.

  In order to produce a high-strength molded activated carbide, it is very important to select the binder and adjust the addition amount. In general, a binder with a higher fixed carbon content such as soft pitch increases the strength of the activated carbide, but the viscosity increases as the fixed carbon content of the binder increases, and the kneadability and moldability are increased. Since it worsens, the uniformity of carbide powder and a binder falls, and it becomes difficult to obtain a high-strength activated carbide. As an improvement measure, there is a method in which low viscosity oil such as creosote oil is used as a viscosity modifier. That is, the various binders can be used singly or in a suitable combination of two or more.

  The amount of the binder for molding is preferably 40 to 90 parts by mass with respect to 100 parts by mass of the total amount of the wood carbide powder and the coal powder. If the addition amount of the molding binder is less than 40 parts by mass, the plasticity of the kneaded product is lowered due to the liquid phase being excessive, and if the addition amount of the molding binder exceeds 90 parts by mass, the liquid phase is excessive. The fluidity increases, and in any case, it is difficult to obtain a good molded product.

  As the kneading machine used for kneading, since the viscosity of the mixture of the carbide powder and the molding binder is high, a kneader-like strong kneading force is preferable, but it is particularly limited as long as it can be homogeneously mixed. is not.

  The mixture kneaded as described above is then molded by a molding machine (step 8). As a molding machine, a pressure molding machine such as an extrusion molding machine is suitable for obtaining a high-strength granular activated carbide, but if it can be molded into a shape and size according to the use of the granular activated carbide. It is not particularly limited.

  The obtained molded product is usually dried at 200 ° C. or less (step 9) and then secondary carbonized (step 10) in order to prevent adhesion between the molded products. Drying and secondary carbonization may be performed continuously in the same equipment, but it is preferable to perform them separately in order to prevent adhesion of molded products and a decrease in strength of the carbide due to rapid heating.

  The secondary carbonization treatment may be performed in the same manner as the primary carbonization treatment, but the volatile content contained in the obtained secondary carbide is preferably 20% or less, particularly preferably 15% or less. The reason is as described above, and it is preferable to reduce the volatile matter in the carbide as much as possible before the activation which is the final heat treatment step.

  When the secondary carbide is obtained as described above, the secondary carbide is activated to form a granular activated carbide (step 11). In order to stably obtain a granular activated carbide having a high strength and a large specific surface area, the activation treatment is preferably performed at a temperature of 800 to 1000 ° C. If the activation treatment temperature is less than 800 ° C., the activation reaction is delayed, so it takes time. If the activation treatment temperature exceeds 1000 ° C., the activation reaction is accelerated and the activated carbide becomes inhomogeneous. Control becomes difficult.

  The treatment method of the activation treatment may be a continuous method or a batch method, and the heating method may be either an external heat method or an internal heat method. Further, the activation treatment atmosphere is usually an anaerobic atmosphere in which oxygen is not present, and is performed by a generally known gas activation method using water vapor, carbon dioxide gas, or a composite gas thereof.

  In this activation treatment, the volatile content contained in the obtained activated carbide is preferably 10% or less, particularly 7.5% or less, and the reason is as described above.

  The activated carbide obtained by the activation treatment as described above is rapidly cooled to prevent ignition (step 12).

  Finally, since the obtained activated carbide contains powder generated in the manufacturing process in addition to the granular material, it is appropriately sieved (step 13). The sieved powder can be returned to the raw material and used again.

  The wood-based granular activated carbide obtained as described above has high strength and large specific surface area while using wood as a raw material.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to the following Example at all.

[Examples 1 to 12, Comparative Examples 1 and 2]
Waste wood from the house (water content: 5%) is used as a raw material. After crushing the raw material so that the size is 50 mm or less, carbonization is performed at a temperature of 600 to 700 ° C. for 20 minutes using an internal heat rotary kiln. Processed. The obtained carbide was cooled and then pulverized by a batch type ball mill to obtain a wood carbide powder having a particle size of 30 μm or less. The equipment and treatment conditions used for this primary carbonization treatment are shown below.

Processing furnace: Internal heat type rotary kiln (572mmφ × 7000mmL)
Heat source: Combustion of A heavy oil by burner Processing temperature: 600-700 ° C
Processing time: 20 minutes Processing amount: 180 kg / h
In-furnace oxygen concentration: 1-5%

  Table 1 shows the properties of the wood carbide powder obtained by the above method. The analysis value is a result of measurement according to JIS M8812 “Coal and cokes—industrial analysis method”.

  On the other hand, as coal powder, the coal for fuel was pulverized by a batch type ball mill so as to have a particle size of 30 μm or less. Table 1 shows the properties of the coal powder.

  The wood carbide powder and coal powder and the molding binder were kneaded at the ratio shown in Table 2. Examples 1 to 5 are examples in which the addition ratio of coal powder to the wood carbide powder is gradually increased, and Examples 6 to 8 are examples in which the addition ratio of the binder to the carbide mixture is gradually increased. No. 12 is an example in which the type and addition ratio of the binder are changed. Comparative Example 1 is an example using a wood carbide powder alone, and Comparative Example 2 is an example using a coal powder alone.

  Kneading was performed until the kneaded material became homogeneous by a grinder. The obtained kneaded product was molded at a pressure of 20 atm using a mold so that the molded product was a cylindrical shape having a diameter of 5 mm and a height of 10 mm, assuming an extrusion molding machine. The obtained molded product was dried at 100 ° C. until it became absolutely dry.

  Next, the molded product was subjected to secondary carbonization treatment at 600 ° C. for 1 hour in a nitrogen atmosphere using a tubular furnace. The equipment and processing conditions used for this secondary carbonization treatment are shown below. In addition, the volatile matter contained in the secondary carbide obtained by the secondary carbonization treatment was 10% or less in all cases.

Processing furnace: Magnetic tube furnace (100mmφ × 500mmL)
Heat source: Externally heated electric furnace Processing temperature: 600 ° C
Processing time: 1 hour Processing amount: 50 g (1 batch)
Atmosphere: Nitrogen circulation atmosphere

  Subsequently, the obtained secondary carbide was cooled after being subjected to a steam activation treatment. This activation treatment was performed at 900 ° C. for 120 minutes under a water vapor concentration of 26% (in a nitrogen atmosphere).

  The specific surface area, compressive strength, and volatile content of the wood-based granular activated carbide thus obtained (a cylindrical shape having a diameter of 5 mm and a height of 10 mm) were measured. The specific surface area was measured by the BET method, and the compressive strength was measured by a uniaxial compressive strength test. The results are shown in Table 3.

  From the above measurement / test results, the following was found. That is, the activated carbide of Comparative Example 2 using only coal powder as a raw material has high strength and a large specific surface area. However, for the activated carbide of Comparative Example 1 using only wood carbide powder as a raw material, the specific surface area is the same as that of Comparative Example 2. Although the strength was the same, the strength was extremely low, and the surface was in a state of being easily broken.

  As for the activated carbides of Examples 1 to 5, the specific surface areas are almost the same, but activated carbides with a higher proportion of coal powder added have higher strength. In particular, the activated carbides of Examples 3 to 5 have the same strength and specific surface area as those of the activated carbide of Comparative Example 2. On the other hand, the activated carbides of Examples 1 and 2 with a small addition ratio of coal powder were in a state where the surface collapsed when strongly touched.

  For the activated carbides of Examples 6 to 8, the strength and specific surface area were the same as those of the activated carbide of Comparative Example 2. However, in Example 6, since the addition ratio of the binder with respect to the carbide mixture was small, the plasticity of the kneaded material was low and the molding process was slightly difficult. On the other hand, in Example 7, the plasticity of the kneaded product is being lost due to a small liquid phase content, and in Example 8, the liquid phase content is high and fluidity is being imparted, but both have good kneadability. , Showed moldability.

  As for the activated carbides of Examples 9 to 12, both the strength and the specific surface area were comparable to those of the activated carbide of Comparative Example 2.

  The method for producing a wood-based granular activated carbide of the present invention is effective for the use of wood, especially waste wood, wood from scraps, chips, sawdust, or felled trees, pruned wood, etc. Can contribute.

It is a process flow figure showing one embodiment concerning a manufacturing method of wood type granular activated carbide of the present invention.

Claims (5)

  In the method for producing granular activated carbide, a method for producing a wood-based granular activated carbide comprising using wood carbide powder and coal powder with a binder added as a raw material.   The method for producing a wood-based granular activated carbide according to claim 1, wherein 10 to 100 parts by mass of coal powder is blended with 100 parts by mass of the wood carbide.   The method for producing a wood-based granular activated carbide according to claim 1 or 2, wherein 40 to 90 parts by mass of a binder is blended with respect to 100 parts by mass of the total amount of the wood carbide powder and the coal powder.   The binder is at least one binder selected from the group consisting of coal tar, anhydrous tar, soft pitch, hard pitch, creosote oil, wood tar, wood tar oil, and wood tar pitch. The manufacturing method of the wood type granular activated carbide in any one of claim | item 1-3. A wood-based granular activated carbide produced by the production method according to claim 1.

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