JPH0375213A - Preparation of active carbon - Google Patents

Abstract

PURPOSE:To simply and inexpensively prepare good active carbon from coal by mixing finely ground caking coal with a specific finely ground non-caking coal, press-molding the mixture, carbonizing the molded products, crushing the carbonized products into even size granules and subsequently activating the granules. CONSTITUTION:Finely ground caking coal is mixed with 20-70wt.% of finely ground non-caking coal having a volatile content of >=45% (d, a, f,) and subsequently press-molded. The molded products as such or after crushed to adjust the granule sizes are carbonized in a chamber oven type carbonization oven, crushed for the uniforming of the granules and subsequently activated to provide the objective active carbon. By the method described above, the mechanical strength of the non-caking coal mainly comprising brown coal having >=45% (d, a, f,) of volatile contents is improved and the melting characteristics of the caking coal are utilized without lowering the melting characteristics by oxidation as in conventional techniques, thereby forming networks having high mechanical strengths in the caking coal and providing a carbonized product capable of being readily activated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing activated carbon. Activated carbon produced by this method removes harmful substances in water and wastewater,
Used to absorb volatile organic substances such as gasoline, toxic gases in exhaust gas, 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 was considered important to select raw material coal and to process it in the process of producing carbide so that the coal would not soften and melt and form carbide with thick pore walls.

For this reason, various methods have been proposed in the past. That is, in JP-A-50-51996, activated carbon is produced by selecting coal that has weak or no caking properties, such as low-degree 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. As described above, 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.

In this way, the currently known methods for producing activated carbon include using coal that does not melt during the carbonization process, or when using coking coal, making it infusible with an oxygen-containing gas and then activating it to produce activated carbon. It's a method.

[Problems to be Solved by the Invention] However, in these known activated carbon production methods, when caking coal is used, it becomes infusible with oxygen-containing gas, so the progress of oxidation is different between the surface and inside of the agglomerated coal. It is difficult to produce a homogeneous infusible process, and if one attempts to produce a homogeneous infusible process, the oxidation treatment time must be prolonged, which is not economical. Additionally, a special carbonization furnace such as a rotary kiln is required as a device for producing carbide. Furthermore, activated carbon made from non-caking coal mainly composed of brown coal has low mechanical strength. From the above points, it is important and strongly desired to establish a method for simply and inexpensively producing high-quality activated carbon from coal.

[Means for Solving the Problem] In order to achieve the object, the present invention adds finely powdered non-caking coal having a volatile content of 45% (d, a, f,) or more to finely pulverized coking coal. It is characterized by mixing 20% by weight or more and less than 70% by weight, pressure molding, as it is or after crushing and adjusting the particle size, carbonizing in a room furnace carbonization furnace, making a carbide, crushing and sizing, and activating. do.

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, which is obtained by finely pulverizing coking coal and granulating it, is used.

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.

On the other hand, activated carbon produced from non-caking coal, mainly lignite with a volatile content of 45% (d, a, f,) or more, has excellent properties in absorbing harmful substances, but has poor mechanical strength. It is weak and easily powders during handling or recycling, which is undesirable.

Therefore, the present invention uses caking coal with a volatile content of 45% (d.

a, f,) or more non-caking coal mainly composed of lignite,
After being finely pulverized and pressure-molded, it is charged into a room furnace type carbonization furnace for carbonization, either as it is or after being crushed.

Therefore, the step of making the coking coal infusible becomes unnecessary. Further, the mechanical strength of the carbide in the non-caking coal portion, which is mainly lignite with a volatile content of 45% (d, a, f,) or more, increases significantly due to the reaction with the coking coal.

On the other hand, the coking coal part shows a melting phenomenon and has a volatile content of 45% (d
, a, f,) or more, a large number of non-caking coals mainly composed of lignite particles are fixed in the coke wall. This is due to the difference in shrinkage rate between caking coal and non-caking coal, which causes countless gaps between the two.

This gap facilitates the diffusion of activation gas into the coke wall of the coke formed by softening and melting during activation, and even if the coke coal melts, it will not have any effect on activation. It was revealed.

As described above, the mechanical strength of non-caking coal, which is mainly lignite with a volatile content of 45% (d, a, f,) or more, is strengthened and the melting characteristics of coking coal are reduced by oxidation as in the conventional technology. Through extensive research, we have discovered that we can make use of the melting properties of coking coal to form a network with strong mechanical strength, and to form a carbide that is easy to activate, leading to the present invention.

Furthermore, no special equipment is required for producing carbide, and a normal coke oven can be used.

Caking coal according to the invention and volatile content 45% (d.

The above non-caking coals a, f,) are mixed after being pulverized, but it is also possible to pulverize them to a certain particle size, for example, about -fomm, then mix and pulverize them. However, sufficient consideration must be given to the crushing characteristics of both. That is, if the pulverization characteristics of the two materials are significantly different, it is better to pulverize them and then mix them as shown in the present invention. The particle size of these coals is preferably smaller than 74 μm.

Finely ground coking coal with 45% volatile content (d, a.

70% by weight or more of finely pulverized non-coking coal of
Less than 20% by weight of non-caking coal is mixed.
If it is less than 100%, the amount of non-caking coal dispersed within the coke pore walls of coking coal will be reduced, the micro cracks that will occur at the boundary between caking coal and non-caking coal will be reduced, and it will be difficult to diffuse the activation gas during activation. This is because the carbide generated from the coking coal portion cannot be activated. In addition, the upper limit of the amount of non-coking coal mixed is set at 70%.
The reason why it is specified as less than 70% by weight is that if 70% by weight or more of non-caking coal is mixed, the mechanical strength of the produced carbide becomes weak. It is preferably 30% by weight or more and less than 50% by weight.

Pressure molding of mixed coal involves adding 20% of finely powdered non-caking coal with a volatile content of 45% (d, a, f,) or more to finely pulverized coking coal.
This is because the caking property of the mixed coal decreases because the amount of the mixed coal is mixed in a proportion of more than 70% by weight and less than 70% by weight, and it is necessary to keep the distance between coal particles small in order to form lump coke (carbide). Furthermore, crushing the pressure-formed agglomerates is necessary because if the agglomerates are of a certain size, the charging density will not be high when charged into the carbonization furnace, so the particle size distribution that will increase the charging density is This is for the purpose of

Carbonizing agglomerated coal in a room furnace type carbonizing furnace has the ability to process the largest amount of carbonization among the various types of carbonizing furnaces currently available, and it is also a machine that produces non-caking coal using coking coal during the carbonization process. This is because it is easy to modify the physical strength. The carbonization temperature in this case is 700
Preferably, the temperature is between 1100°C and 1100°C. However, even in a continuous rotary kiln or the like, carbide can be easily produced by subjecting agglomerated coal to oxidation IA treatment using a conventional method and then carbonizing it.

Incidentally, when activated carbon with extremely high mechanical strength is required, it is advisable to add a binder such as tar or pitch.

The particle size of the generated carbide is adjusted according to the particle size of the target activated carbon, and then activated by conventional means to produce activated carbon.

As described above, the present invention provides finely pulverized coking coal with a volatile content of 45%.
% (d, a, f,) or more of pulverized non-caking coal is mixed with 20% by weight or more and less than 70% by weight, pressure molded, and then carbonized as it is or after being crushed in a room furnace type carbonization furnace. , is a method for producing activated carbon characterized by making it into a carbide, crushing it, sizing it, and activating it, omitting the step of making the coking coal infusible, and simply using an existing indoor coke oven. It manufactures carbide. The carbide produced by the method of the present invention is activated by a known method such as steam or CO2 to form activated carbon.

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

In addition, volatile content C%, d, a, f,) is JISM881
This is the value obtained by converting the volatile content measured according to 2-1972 on a pure coal basis.

Table 1 Caking coal and non-caking coal crushed to 74 μm or less were mixed at the mixing ratio shown in Table 2, pressure-molded to agglomerate, and this agglomerated coal was crushed under the conditions shown in Table 2. 350g was charged into a carbonization furnace with a volume of 500mJl and heated at a heating rate of 3°C/ffl1n to 70%
The temperature was raised to 0° C., held for 30 minutes, and then taken out to form a carbide.

Table 2 Table 3 shows the results of measuring the black strength.

Table 3 These carbides formed lump coke except for Runs No. 1 and 2. This point shows that if 70% by weight or more of non-caking coal is mixed with caking coal, lump coke will not be formed and it will be difficult to discharge it from a room furnace type coke oven.

The produced carbide was sized to a size of 3 to 0.5 mm, 150 g was charged into a reaction tube with an internal volume of 2000+n4, and activated at 900° C. for 4 hours at a steam rate of 7 g/min to obtain activated carbon. The specific surface area and micro strength of the generated activated carbon were determined by using a stainless steel tube with an inner diameter of 25 mm and a length of 305 mm, and 10 stainless steel balls with a diameter of 8 mm.
■ Add 10g of activated carbon and turn at 25 rpm.
The yield of activated carbon after rotation for 0 minutes is 0.35 mm or more.

From the results in Table 3, the specific surface area increases as the amount of non-caking coal increases, which is preferable to activated carbon, but the micro strength decreases. When compared with commercially available activated carbon, the upper limit for non-caking carbon is 70% by weight in terms of micro strength. On the other hand, based on the specific surface area, the lower limit of non-caking coal is 20% by weight.

As shown in the Examples and Comparative Examples above, a carbide for activated carbon can be easily produced by the method of the present invention.

The activated carbon produced from the carbide of the method of the invention can be used as activated carbon for water treatment, solvent adsorption, gasoline, toxic gases, or as a deodorizing agent.

Claims (1)

[Claims] 1 Finely ground coking coal with 45% volatile content (d, a, f,)
The above finely pulverized non-caking coal is mixed at 20% by weight or more and less than 70% by weight, pressure molded, and then either as it is or after being crushed to adjust the particle size, carbonized in a room furnace carbonization furnace to form a carbide, A method for producing activated carbon, characterized by crushing, sizing, and activating.