JP2002220617A - Method for charging plastic or compact including plastic into furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent plastics or compacts including plastics from remaining in a chute, which have been obtained from plastics waste, and which are charged into a smelting furnace through the chute as a heat source or reducing agents. SOLUTION: This method for charging the plastics or the compacts including plastics into the furnace 2 through the chute 9, comprises blowing gas for purge into the chute. It is preferable, on that occasion, to blow the gas for purge to a vertically downward direction, to blow the gas for purge from several points of the chute, and to blow the gas for purge at a vertically lower side than a gate valve 10 which is arranged in the chute, in a state that the gate valve is closed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing plastics and the like from remaining in a chute when charged into a furnace when recycling plastic wastes in a metallurgical furnace such as a converter.

[0002]

2. Description of the Related Art In converter refining of steel, the main raw materials are hot metal and iron scrap, and the sensible heat of the hot metal and the heat generated by the oxidation of C and Si contained in the hot metal are used as heat sources for the next process. To ensure the molten steel temperature. Then, the ratio of the hot metal in the main raw material (referred to as “hot metal mixing ratio”) is changed so as to always be the optimum condition from the fluctuation of the production amount and the fluctuation of the price of iron scrap.

However, when the mixing ratio of molten iron is reduced, the heat source in converter refining is reduced. Therefore, when it is difficult to secure the molten steel temperature required in the next process, Fe-Si is used as the heat source.
Carbon materials such as alloys and coke were additionally charged into the furnace to compensate for the lack of heat sources. In particular, with the decrease of C and Si in hot metal due to hot metal pretreatment for desiliconization and dephosphorization in recent years,
The shortage of heat sources in converter refining has become even more pronounced.

[0004] However, the additional charging of the Fe-Si alloy requires F
The e-Si alloy itself is expensive and the Si in the slag
O ₂ amount increases, in order to adjust the response to SiO ₂ of increment in slag basicity (CaO / SiO _2),
The amount of flux charged such as quicklime and dolomite increases, leading to an increase in the amount of slag in the furnace, resulting in a decrease in iron yield.
In addition, additional charging of carbonaceous material such as coke involves contamination of molten steel by S and N contained in the carbonaceous material, and the target steel type and usage amount are limited. As described above, there was no convenient additive to make up for the shortage of the heat source, and smelting was unavoidably performed with a higher molten metal mixing ratio.

On the other hand, in recent years, synthetic resin waste such as plastic has been rapidly increasing as industrial waste and general waste. These synthetic resins contain C, H, and O as main components, and generate a large amount of heat during combustion. If incinerated, the incinerator may be damaged or the atmosphere may be warmed. It is difficult and many of them have been dumped in landfills. However, landfill dumping of synthetic resins that are extremely difficult to decompose is not preferable in terms of environmental measures, and development of an effective recycling method has been desired.

[0006] Against this background, Japanese Patent Application Laid-Open No. H10-140223 discloses a method for recycling waste plastics and other synthetic resins as auxiliary fuel. In the same publication, a mixture of plastic and a coolant such as iron ore or mill scale or a briquetted molded body is charged from a converter furnace port to burn the plastic, and the combustion heat is used to melt the slag or molten slag in the furnace. The hot metal is heated. According to this method, it is possible to control the temperature of the molten steel without having to worry about the pickup of S and N in the molten steel, and a large amount of synthetic resin and other waste materials such as plastics are recycled and used. It greatly contributes to the protection of the natural environment.

[0007]

By the way, in a converter, auxiliary materials such as quicklime and plastics and plastic-containing molded articles are temporarily stored in a furnace hopper for storage provided on the converter furnace. A predetermined amount is cut out from the furnace hopper, and is put into the furnace from the furnace port via a chute. This chute is connected to a hood that is installed above the converter furnace opening and collects exhaust gas from the converter.Around the chute, the air heated by the converter and the converter when the converter tilts A high-temperature atmosphere is created by the discharged high-temperature gas.

The density of plastics and molded articles containing plastics is smaller than that of other auxiliary materials such as quicklime and iron ore, and tends to remain in the chute. The plastic softens and melts at a relatively low temperature of 100 ° C to 200 ° C, depending on its composition. Therefore, when the entire amount of the plastic or the plastic-containing molded body does not fall into the converter and remains in the chute, the plastic melts and adheres to the inner wall of the chute. When the plastic gets inside the chute,
It becomes an obstacle to the newly introduced plastic or plastic-containing molded article, and the adhesion increases, and eventually the chute is closed and the introduction becomes impossible. Regarding this point, the above publication does not take any measures.

The present invention has been made in view of the above circumstances,
The purpose is to put plastic or plastic-containing molded products obtained from plastic waste in a converter or other metallurgical furnace as a heat source or a reducing agent into the furnace through a chute. It is an object of the present invention to provide a method for preventing a plastic or a plastic-containing molded article from remaining in the apparatus.

[0010]

According to a first aspect of the present invention, there is provided a method for charging a plastic or plastic-containing molded article into a furnace through a chute. In this case, the purging gas is blown into the chute, and the method for charging a plastic or a plastic-containing molded article into a furnace according to the second invention is characterized in that, in the first invention, the purging gas is blown vertically downward. According to a third aspect of the present invention, in the method for charging a plastic or a plastic-containing molded article into a furnace according to the third aspect of the present invention, the purging gas is blown from a plurality of locations of the chute in the first aspect of the invention.

The method for charging a plastic or plastic-containing molded article into a furnace according to the fourth invention is the method according to any one of the first to third inventions, wherein the purging gas is supplied while the plastic or plastic-containing molded article is charged. The method according to the fifth invention is characterized in that the chute is provided with a gate valve, and the gate valve is provided with the gate valve. In a closed state, a purge gas is blown vertically below the gate valve.

In the present invention, when a plastic or plastic-containing molded product obtained from plastic waste is charged into a furnace through a chute as a heat source or a reducing agent, a purging gas is blown into the chute. The plastic or the molded plastic-containing product is discharged into the furnace together with the purge gas and does not remain in the chute. As a result, adhesion of plastic in the chute can be prevented beforehand, and a predetermined amount of plastic waste can be stably recycled in the metallurgical furnace.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing an example of an embodiment of the present invention, and is a schematic view of a converter equipment. FIG. 2 is an enlarged view of a part A in FIG. 1. As shown in FIG. A converter body 2 for decarburizing and smelting hot metal, and a furnace hopper 3 for temporarily storing a lump or granular plastic or plastic-containing molded body obtained from plastic waste above the converter body 2 And

The plastic or plastic-containing molded product put into the converter body 2 is obtained by melting or semi-melting plastic waste collected as industrial waste or general waste and then solidifying it. Crushed and granulated, and plastic waste mixed with iron ore, Mn ore, mill scale, iron-made dust, etc., melted plastic and briquetted or extruded. The size can be used from several mm to several hundred mm. here,
A plastic-containing compact is a mixture of plastic waste and iron ore, Mn ore, mill scale, steelmaking dust, steel cuttings, etc., and is molded using a melted plastic as a binder. It is a generic term for molded cylindrical ones. If the recovered waste can be used as it is, it does not need to be melted and solidified or crushed, and can be used as it is.

[0015] The plastic or plastic-containing molded article (hereinafter referred to as "plastics") processed and molded from the plastic waste as described above is stored on a storage bunker (shown in the figure) provided on a ground by a transport vehicle such as a truck. ) Is temporarily stored therein, and then supplied from the storage bunker into the furnace hopper 3 via a belt conveyor (not shown) or the like. Although not shown in FIG. 1, around the furnace hopper 3, furnace hoppers for storing other auxiliary materials such as quicklime and iron ore are arranged side by side.

A cutting device 4 such as an electromagnetic feeder is installed at the bottom of the furnace hopper 3. Plastics in the furnace hopper 3 are weighed by the cutting device 4 under the furnace hopper 3. In the hopper 5,
The predetermined amount is cut out. An on-off valve 6 is installed at the bottom of the weighing hopper 5, and a fixed-quantity cut-out device 7 such as an electromagnetic feeder is installed immediately below the on-off valve 6. Plastics in the weighing hopper 5 are opened and closed. With the valve 6 opened, the fixed amount is put into the converter main body 2 by the fixed amount cutout device 7.

Here, the fixed-quantity cutting device 7 includes a chute 9
The chute 9 is connected to a hood 8 installed so as to cover the furnace opening of the converter main body 2, and the plastics cut out by the fixed amount cutout device 7 slide down in the chute 9, It is thrown into the converter body 2 from the mouth.
The hood 8 is a facility disposed as a passage for sending exhaust gas generated from the converter main body 2 to a dust collector.

The chute 9 is provided with a gate valve 10 for shutting off the passage of the chute 9 vertically below the fixed quantity cutting device 7. By closing the gate valve 10, the air sucked into the hood 8 through the chute 9 and the converter exhaust gas discharged through the chute 9 can be extremely reduced. A chute (not shown in FIG. 1) is provided between the furnace hopper 3 and the weighing hopper 5 and between the weighing hopper 5 and the fixed-quantity cutting device 7, and plastics are supplied through the chute. Is done.

A blow nozzle 13 is provided on the chute 9 vertically below the gate valve 10 as shown in FIG. The blowing nozzle 13 is connected to the purge gas supply pipe 11, and a shutoff valve 12 is installed in the purge gas supply pipe 11. The purge gas supplied from the purge gas supply pipe 11 is supplied to the blow nozzle 13. Is blown into the chute 9. Although nitrogen is shown in FIG. 1 as the purge gas, it is preferable to use a nonflammable gas such as nitrogen or carbon dioxide gas. Although it is possible to use air as a purge gas, the inside of the
If the air is filled with CO gas exhausted from the air, there is a possibility that the CO gas may burn or explode in the chute 9, which is not preferable.

It is preferable that the blowing direction of the blowing nozzle 13 be vertically downward from the viewpoint of rapidly feeding plastics to the converter body 2 side. That is, it is preferable to blow the plastics along the falling direction in the chute 9. Further, from the viewpoint of preventing the plastics from remaining in the chute 9, it is preferable to provide a plurality of the blowing nozzles 13 in the direction in which the plastics fall.

The present invention is carried out in the converter equipment 1 having such a configuration as follows. First, furnace hopper 3
A predetermined amount of plastics is cut out from the hopper 5 and stored in the weighing hopper 5. Then, when it is time to input the plastics, the gate valve 10 that has been closed is released, the on-off valve 6 is opened, and the fixed quantity cutout device 7 is operated to put the plastics into the converter body 2. . Before and after the plastics are put into the converter body 2, the shut-off valve 12
Is released, and a purge gas is supplied from the blowing nozzle 13.

During the charging period of the plastics, it is preferable that the blowing of the purge gas be continued in order to prevent the plastics from remaining in the chute 9. And, when the input of the predetermined amount of plastics is completed,
It is preferable to close the gate valve 10 and continue blowing the purge gas. Since the entire amount of the purge gas blown by closing the gate valve 10 flows toward the hood 8, the plastics are pushed out toward the hood 8 by the purge gas, and the plastics remain in the chute 9. Is efficiently prevented. It is sufficient that the blowing time of the purge gas after the charging is completed is about 1 to 3 minutes. After a predetermined time has elapsed after the completion of the charging of the plastics, the shutoff valve 12 is closed. Purging gas chute 9
Since the effect of preventing plastics from remaining increases as the flow rate in the inside increases, it is preferable to set the blowing flow rate so that the average flow rate of the purge gas in the chute 9 is at least 1 m / sec or more. The average flow velocity is a value obtained by dividing the blown particle flow rate by the inner area of the chute 9.

By putting plastics into the converter body 2 in this way, the plastics are prevented from remaining in the chute 9 and a predetermined amount of plastics is stably recycled in the converter equipment 1. can do. As a result, control of molten steel temperature in converter refining becomes easier,
Improvements in iron yield and increased exhaust gas recovery are achieved.

The present invention is not limited to the above description. For example, electric furnace equipment or ladle refining furnace equipment may be used instead of the converter equipment 1, and a hopper is further provided below the weighing hopper 5. Is also good. The number of the blowing nozzles 13 is not limited to three, but may be any number as long as it is one or more.

[0025]

According to the present invention, in a metallurgical furnace such as a converter, a plastic or plastic-containing molded product obtained from plastic waste is introduced into a furnace through a chute as a heat source or a reducing agent through a chute. It is possible to prevent large amounts of plastic waste from being stably recycled and to use a large amount of plastic waste stably. As a result, it becomes easier to control the temperature of molten steel in converter refining, improve iron yield and increase exhaust gas recovery, and stably process large amounts of plastic waste, which is an industrially beneficial effect. Is brought.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention and is a schematic view of a converter facility.

FIG. 2 is an enlarged view of a portion A in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Converter equipment 2 Converter main body 3 Furnace upper hopper 5 Weighing hopper 7 Quantitative cut-out device 8 Hood 9 Chute 10 Partition valve 11 Purging gas supply pipe 12 Shut-off valve 13 Blow nozzle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Yokoyama 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. 4K002 AB04 BE10

Claims (5)

[Claims] 1. A method for charging a plastic or plastic-containing molded article into a furnace, wherein a purging gas is blown into the chute when the plastic or plastic-containing molded article is charged into the furnace via the chute. 2. The method according to claim 1, wherein the purging gas is blown vertically downward. 3. The method according to claim 1, wherein the purging gas is blown from a plurality of locations of the chute. 4. The plastic or plastic-containing molded article according to any one of claims 1 to 3, wherein the purging gas is continuously blown while the plastic or plastic-containing molded article is charged. Input method. 5. A gate valve provided on a chute, wherein a purge gas is blown vertically below the gate valve in a state where the gate valve is closed.
The method for charging the plastic or the plastic-containing molded article according to any one of the above, into a furnace.