JPS59174512A - Regenerating method of waste powdered activated carbon - Google Patents

Abstract

PURPOSE:To regenerate efficiently used activated carbon into molded activated carbon by adding an organic caking material to the dried, pulverized used activated carbon and molding with a pellet mill. CONSTITUTION:The waste powdered activated carbon is crushed to <= about 10mm. particle size, and dried to about 30-40wt% water content, and further pulverized. Then about 0.5-5wt% hydrophilic organic sizing agent such as powdered carboxymethyl cellulose sodium salt is added to the above-mentioned powdered activated carbon as a caking agent, and mixed. The obtained mixture is stored temporarily, then sent to a pellet mill, extruded from a die hole, and cut in about 10-15mm. length with a cutter knife. Then the obtained pellet is cooled at first, then heated, carbonized, and activated in a high-temp. steam to obtain the molded activated carbon. In addition, wood flour may be used as an organic caking material instead of the above-mentioned hydrophilic synthetic sizing material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recycling waste powder activated carbon.

Powdered activated carbon is used in fields such as water and sewage treatment equipment, food industry such as alcoholic drinks, and chemical industry such as drug refining. Powdered activated carbon, which is used in large quantities in the fields mentioned above, is mostly discarded without being recycled. Discarded used powdered activated carbon contains a lot of organic matter, so it can decompose and emit a bad odor, so it needs to be disposed of properly to prevent pollution. The reason why it is difficult to recycle powdered activated carbon is that recycling is inefficient and expensive. In other words, when dry, used powdered activated carbon is heated as a powder in an air stream, the powder becomes even finer.
This is because it scatters together with the exhaust gas from the collector, resulting in extremely poor collection efficiency.

The present invention was made by focusing on the above-mentioned problems in the conventional method for recycling waste powdered activated carbon, and involves adding an organic caking agent to dried and crushed used powdered activated carbon.
This is molded into molded activated carbon or powdered activated carbon using a pellet mill, and the purpose is to efficiently recycle waste powdered activated carbon.

The following description will be made based on FIGS. 1 and 2 of the accompanying drawings.

First, an embodiment of the first invention according to the present application will be described. That is, a method of using a wood-philic paste as the organic binder to be added will be explained.

The steps of this method are shown in FIG. Powdered activated carbon is mainly used for liquid phase adsorption, and then subjected to treatments such as coagulation sedimentation and mechanical dehydration to form a dehydrated mass. First, this lump of waste activated carbon powder is crushed to a diameter of about 10 mm or less. This is to facilitate drying of the mass of waste powder activated carbon containing 55 to 70% (by weight) of water. Next, the crushed waste powder activated carbon is dried using a hot air drying device. This drying brings the moisture content to 30 to 40% (by weight). If the moisture content is more than 40% (by weight), the pellets will become soft in the subsequent pelletizing process, and if the moisture content is less than 30% (by weight), the die holes will become tightly plugged. This is because the pellet mill becomes overloaded. Next, the dried waste activated carbon powder is further pulverized, and a hydrophilic synthetic sizing agent, which is an organic caking agent, is added thereto and mixed uniformly. As the hydrophilic synthetic glue, 0.5 to 5.0 (weight)% of powder of carboxymethylcellulose sodium salt, sodium alginate, or polyvinyl alcohol is added. The reason for adding the hydrophilic synthetic glue is to give the pellets sufficient strength so that they do not break during the recycling process.

The reason why the amount of hydrophilic synthetic glue added was set at 0.5 to 5.0% (by weight) was because if the amount added was less than 0.5% (by weight), the strength of the pellets would be insufficient. This is because if the amount exceeds % by weight, the die hole becomes tightly plugged and the pellet mill becomes overloaded. There is no problem as long as the amount of water and the hydrophilic synthetic glue is within the above range, but if the water content is 35% (by weight) and the amount of the hydrophilic synthetic glue is 3.
(wt)%, it was possible to obtain pellets with the most appropriate strength. The mixed raw material obtained as above is
After being stored for a while, it is supplied in a fixed amount to a pellet mill. A pellet mill consists of a cylindrical die that is rotationally driven by a motor, multiple rolls placed in contact with the inner diameter of the die, and a mixed raw material that is evenly distributed between the inner diameter of the die and each roll. It has a spreader. The die has a number of radial die holes extending from the inner diameter to the outer circumferential surface. The die hole has a diameter of 6.
Although a 35 mm one was used, any length in the range of 5 to 7 mm will do. The mixed raw material supplied in a fixed amount to the inner diameter of the die is compressed by being bitten between the inner peripheral surface of the die and the outer peripheral surface of the roll, and is plasticized by the heat generated by this compression and the heat generated by internal friction of the mixed raw material during compression. , is continuously extruded from the die hole. In the die hole, the mixed raw materials form a plug flow (i.e., a flow of solid material in the tube), and the temperature in this part reaches 60~60 b/cm2, and the pellets are mixed with the added hydrophilic synthetic glue. As a result, it has sufficient strength not to be destroyed in the subsequent carbonization and activation steps. The cylindrical molded product extruded from the die hole is cut by a cutter knife provided close to the outer periphery of the die.
Cut into lengths of mm. The pellets thus obtained are sent to the carbonization process, during which they are cooled by forced ventilation.

This cooling significantly improves the mechanical strength of the pellets. The pellets sent to the carbonization process are heated to 400-600 ml in a heating furnace with no or little oxygen.
It is heated for about 30 minutes at a temperature of 00°C. The heating temperature is most preferably around 550"0. By doing so, most of the moisture and volatile matter in the pellets are lost,
Beret / ) has a porous structure. The carbonized pellets are then sent to an activation process. That is, Pere Soto was heated to 850'0 (850'0) in a rotary kiln without oxygen.
It is heated to 850-90.0°C) and steam is blown into it. The activation time is 1.5 to 2.0 hours, and the amount of water vapor blown is 1.2 to 2.0 kg (steam) /
kg (pellets) was appropriate.

Through this activation step, the porous structure of the pellets is further developed, and recycled activated carbon with high porosity is obtained. After activation, the regenerated activated carbon (which contains some soft and broken pellets) is pulverized to produce powdered activated carbon as the final product. Note that the loss of powdered activated carbon in the above regeneration step was about 10%.

Next, an embodiment of the second invention related to the present applicant, namely:
Describe the method of using wood as an organic binder.

The steps of this method are shown in FIG. 2. A lump of waste powder activated carbon is crushed and dried so that the moisture content becomes 20 to 30% (by weight). If the moisture content is more than 30% (by weight), the pellets will become soft in the pelletizing process described below, and if the moisture content is less than 20% (by weight), the pellet mill will be overloaded. state. Then,
20 to 70% (by weight) of wood flour is added to the dried powdered activated carbon and thoroughly mixed in a continuous mixing device. Wood flour is made by crushing and drying wood waste, sawdust, bark, etc. Sift the wood flour through a mesh with a gap of about 4 to 6 mm. This is mainly to remove relatively large pieces of wood, etc., which may be mixed into the wood powder with a maximum diameter of about 1 mm or less. Wood flour is dried by drying equipment before adding. The moisture content of wood flour after drying should be 10% (by weight) or less, but it should be 4 to 7%.
(weight)% is most preferable. lO (weight)%
If it contains more water than

It is not possible to obtain sufficient strength of the pellets after molding.

It is also possible to dry the wood to a state where the water content is almost O, but in this case, care must be taken not to ignite the wood powder. The added wood flour is plasticized at high temperature and high pressure in a pellet mill, which will be described later, and oozes out lignin, wax, etc., and serves as a caking agent. In addition, the amount of wood flour added to the waste cormorant powder activated carbon was 20 to 70 (
(wt)% is used because if the amount of wood flour added is less than 2.0%, plug flow will not occur in the die hole of the pellet mill (described later), so pelletization will be difficult due to blade scratches and the amount added. When the amount is more than 70%, the pellets become soft because the predetermined pressure cannot be reached in the die hole. The amount of wood flour added may be within the above range, but the most preferred mixing ratio was 50% (by weight). The above-mentioned mixed raw material is once stored and then supplied in a fixed amount to the pellet mill. The mixed material supplied in a fixed amount to the inner diameter of the die is compressed by being bitten between the inner circumferential surface of the die and the outer circumferential surface of the roll, and is plasticized by the heat generated by this compression and the heat generated by internal friction of the raw material during compression. It is continuously extruded from the die hole. The mixed raw materials form a plug flow in the die hole, and the temperature of this part is 10
0~170℃ and pressure 1000~6000kg/C
reaches m2. Under such conditions, oils, fats, lignin, etc. in the wood flour ooze out and bind the waste activated carbon powder, resulting in pellets with excellent caking and compacting properties. The cylindrical molded product extruded from the die hole is cut into 1O10N1 by a cutter knife provided close to the outer periphery of the die.
Cut into 3 lengths. Thereafter, the carbonization and activation steps are performed under the same conditions as in the above case. Since the pellets in this case have sufficient strength even after activation, the powdered activated carbon and the shaped activated carbon are sieved to obtain shaped activated carbon and powdered activated carbon as final products. In addition,
In this case as well, it is of course possible to pulverize the shaped activated carbon and regenerate it as powdered activated carbon.

As explained above, according to the present invention, the powdered waste activated carbon dehydrated after dehydration has a moisture content of 30 to 40% (by weight) or 2%.
0 to 30% (by weight), and then pulverized to a powder, and this powder is added to an organic binder that can be plasticized by pressure (in the example described, the water content is 30 to 40%).
(weight) % indicates a hydrophilic synthetic glue, and the water content is 20~20%.
In the case of 30% (by weight), wood flour) is added and mixed, and the mixed raw material thus obtained is fed to a pellet pellet, and the mixed raw material is extruded at a temperature and pressure that plasticizes, and at the same time it is cut. The pellets are made into pellets, the pellets are carbonized by heating, and the carbonized pellets are then activated in high-temperature steam to produce recycled activated carbon.This enables efficient recycling of used powdered activated carbon into molded activated carbon or powdered activated carbon. This makes it possible to obtain high-quality recycled activated carbon at a low price. This also solves the pollution problem associated with the disposal of used powdered activated carbon. Moreover, the method of the present invention can be implemented by adding a pellet mill or the like to a conventional activated carbon manufacturing apparatus, and can be implemented at relatively low equipment costs.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the steps of the first invention according to the present application. FIG. 2 is a diagram showing the steps of the second invention according to the present application. Patent Applicant Nikki Steel Co., Ltd. Agent Patent Attorney Toshiyuki Miyauchi No. 1
1:i Figure 2

Claims (1)

[Claims] 1. Waste powdered activated carbon that has been dehydrated and crushed has a moisture content of 30 to 40 (
% by weight, then pulverized into a powder, an organic binder that can be plasticized by pressure is added to this powder and mixed, and the mixed raw material thus obtained is fed into a pellet mill. The mixed raw material is extruded at a temperature and pressure that plasticizes, and at the same time it is cut into pellets.The pellets are carbonized by heating.Then, the carbonized pellets are activated in high-temperature steam to produce recycled activated carbon. Method for recycling waste powdered activated carbon. 2. The method for regenerating waste powder activated carbon according to claim 1, wherein the organic caking agent is a wood-loving synthetic glue. 3. After dehydration, crush the waste powder and powdered activated carbon to a moisture content of 20 to 30.
(weight)%, then pulverized into powder, an organic binder that can be plasticized by pressure is added to this powder and mixed, and the mixed raw material thus obtained is pellet milled. The mixed raw material is extruded at a temperature and pressure that plasticizes, and at the same time it is cut into pellets. The pellets are heated to carbonize them, and then the carbonized pellets are activated in high-temperature steam to produce recycled activated carbon. A method for recycling waste powdered activated carbon. 4. The method for recycling waste powder activated carbon according to claim 3, wherein the organic binder is wood.