JPH09189412A - Method for burning and melting shredder dust - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the volume of shredder dust through burning and melting to reduce the load of a disposal site, and to collect valuable metals. SOLUTION: Shredder dust containing valuable metals, and lump fuel or briquette containing ore powder and fuel powder are charged from a charging port of an air blast furnace, the oxygen source for combustion is fed from a tuyere, the height of the heaped shredder dust in the air blast furnace is kept low, the secondary air is blown to keep a combustion chamber at high temperature, the in-furnace melt is continuously discharged with the gas pressure at a furnace bottom part without keeping it in a hearth, the discharged melt is separated into the slag and the mat containing valuable metals, and the dust containing valuable metals is collected from the exhaust gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for burning and melting shredder dust containing valuable metals, and more particularly to a method for burning and melting shredder dust for recovering valuable metals and converting combustion waste into slag. .

[0002]

2. Description of the Related Art Waste plastics, metal scraps, glass scraps, etc. generated by crushing and sorting wastes such as automobiles (including bicycles with motors), electric machinery, etc. (shredder dust is used in this specification. In general, heavy metals such as lead are contained in it, and it is obligatory to shift from the conventional stable landfill landfill to the managed landfill landfill. However, since the shredder dust contains valuable metals such as copper, lead and zinc,
It is desirable to recover them and to combust and melt them for the purpose of reducing the volume in order to reduce the load on the landfill disposal site.

In Japanese Unexamined Patent Publication (Kokai) No. 6-129618, shredder dust is charged together with a lumpy carbonaceous combustible substance into a shaft furnace type waste melting furnace, and the superficial velocity in the melting furnace is set to 0.1 Nm / s or more. However, a method of melt processing is disclosed. However, the shaft furnace has a large thermal gradient in the height direction of the furnace, for example, 300 ° C in the upper part of the furnace and 1700 to 1800 ° C in the melting zone. Since the shredder dust gradually descends from the upper part of the shaft furnace, it undergoes efficient heat exchange, so even shredder dust with a high water content can be dried in the upper part of the furnace and efficiently processed. However, it is difficult to discharge low-temperature volatile substances such as zinc, lead, and chloride generated in the reaction in the high-temperature part of the furnace to the outside of the furnace because they rise in the furnace and condense in the low-temperature zone at the top of the furnace. Is. At present, there is no established technology for recovering valuable materials generated by combustion and melting of shredder dust.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The present inventor has diligently studied in order to reduce the volume of shredder dust by burning and melting the shredder dust in order to reduce the load on the landfill disposal site and to collect valuable metals. It was found that the above object can be achieved by utilizing an air blast furnace disclosed in Japanese Patent Publication No. 46-6681, and the present invention has been completed.

[0005]

That is, the method of combustion and melting of shredder dust according to the present invention is to install shredder dust containing valuable metal, and lump fuel or ore powder and briquettes containing fuel powder in an blast furnace. Charge from the inlet, supply the combustion oxygen source from the tuyere, keep the load height of the shredder dust in the blast furnace low, blow secondary air to the load height surface to maintain the combustion chamber at a high temperature, To continuously discharge the melt in the furnace by the gas pressure at the bottom without accumulating in the hearth, separate the melt discharge into slag and mat containing valuable metal, and recover dust containing valuable metal from exhaust gas. Is characterized by.

In the present invention, the shredder dust is charged into the blast furnace as it is without being solidified. Therefore, when the blast furnace is charged, scattering of the shredder dust at the time of charging and combustion is prevented, and the blast furnace is also provided. It is necessary to ensure ventilation inside and continue combustion at high temperatures. Therefore, in the present invention, it is preferable to take the following measures.

(1) A control damper is installed in the gas passage in order to adjust the pressure in the blast furnace and the gas speed to prevent the scattering of lightweight powder. (2) As a composition of the blast hearth, ore powder, fuel powder, binder, and if desired, flux is compounded and molded into a briquette (in this specification, a briquette is molded into a briquette). Ore) and coke and other massive fuel to form a grate, and shredder dust and briquette or coke are used in combination to secure ventilation in the blast furnace. (3) Regarding the combustion of shredder dust, the combustion chamber temperature shall be a high temperature of 800 ° C or higher in accordance with the guidelines of the Ministry of Health and Welfare in order to prevent the generation of dioxins, which may occur due to the thermal decomposition of plastics. It is necessary to burn at a high oxygen concentration of 6% or more, and for this purpose, in the blast furnace, the load height is always kept low, and secondary air is efficiently blown to the load height surface, so that the inside of the blast furnace is improved. Keep the bed and combustion chamber at high temperatures above 800 ° C. (4) For the purpose of efficiently carrying out the reaction in the blast furnace,
Along with shredder dust, one or several kinds of calcium carbonate, calcium hydroxide, gypsum and silica are charged as flux. In particular, gypsum is effective in recovering copper in shredder dust as a sulfide.

The present invention will be described below with reference to the drawings.
FIG. 1 is a process diagram showing an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the main part of a blast furnace used in the method for combustion and melting shredder dust of the present invention in a used state. The shredder dust 1 containing valuable metal is supplied to the charging port of the blast furnace and held by the charging damper 2 provided at the charging port of the blast furnace. The charging damper 2 is divided into a plurality of parts in the horizontal direction of the blast stove and installed, and the shredder dust 1 is loaded into the blast furnace by sequentially opening and closing them.
A combustion oxygen source, such as air or oxygen-enriched air, is supplied from the tuyere 3 to maintain combustion in the blast furnace. In order to carry out this combustion effectively, it is important to maintain ventilation in the blast furnace. For this purpose, the briquette 4 containing the lump fuel or the ore powder and the fuel powder is used together with the shredder dust 1, and the load of the shredder dust in the blast furnace is kept low.

Not only can ventilation resistance be reduced by keeping the load height low, but also shredder dust 1
It is possible to efficiently remove and collect volatile substances by keeping the load-bearing surface at a high temperature of 800 ° C. or higher. However, if the load is too low, the gas pressure at the bottom of the furnace, which is brought by the air supplied from the tuyere, does not rise so much, and as a result, the gas pressure at the bottom of the furnace prevents the molten material in the furnace from accumulating continuously in the furnace floor It becomes difficult to discharge it. On the other hand, if the load height is maintained higher than necessary, the reaction gas that has become hot in the reaction zone near the tuyere will be heat-exchanged with the raw materials while rising, and the temperature inside the combustion chamber will drop, resulting in ineffective volatilization . Further, ventilation resistance becomes high, and problems such as uneven flow of gas in the furnace occur. Therefore, the load of shredder dust in the blast furnace is preferably 100.
Maintain about 500 mm.

At the start of the operation of the blast furnace, only the briquette fuel or ore powder and the briquettes 4 containing the fuel powder are charged, and the shredder dust 1 is discharged when they rise to a predetermined temperature to form a grate. Charge, then shredder dust 1,
And a briquette 4 containing bulk fuel or ore powder and fuel powder, either simultaneously or separately. It is also possible to mix them in advance and to charge them. The briquette 4 containing this lump fuel or ore powder and fuel powder ignites at the upper part of the load in the blast furnace, moves downward while burning, and reaches the bottom of the blast furnace before it burns out, forming a grate. However, the shredder dust 1 ignites at the upper part of the load in the blast furnace, moves downward while burning, and burns out the combustible components and melts the incombustible components before reaching the bottom of the blast furnace. Therefore, during normal operation, a layer composed of the burning high-temperature lump fuel or ore powder and the briquettes 4 containing the fuel powder is formed in the lower part of the blast furnace, and the upper part does not burn. A layer mainly composed of the shredder dust 1 is formed.

Since the shredder dust 1 is extremely lightweight, the scattering during charging and burning becomes a problem. To prevent this, a control damper is installed in the exhaust gas passage to control the pressure in the blast furnace and adjust the gas speed in the blast furnace. Further, as shown in FIG. 2, the structure of the combustion chamber 5 is widened toward the upper part so that the gas speed is reduced toward the upper part to prevent the shredder dust 1 from scattering. . Further, for the purpose of preventing clogging of the flue, it is preferable to provide a dust chamber 6 between the blast stove and the control damper to collect heavy dust scattered from the combustion chamber.

When the pressure in the combustion chamber is higher than the atmospheric pressure, there is a risk that the hot gas in the combustion chamber will flow back to the charging port and ignite the shredder dust 1 retained in the charging port. If it is too much, the light shredder dust 1 may be carried over by the air entering the furnace from the charging damper at the time of charging, and may be discharged to the furnace outlet with insufficient combustion. Therefore, the degree of decompression in the combustion chamber by the exhaust fan is controlled by the control damper with gauge pressure-
It is preferable to adjust to about 10 mmAq to -20 mmAq.

During normal operation, the surface of the shredder dust 1 is constantly exposed to a high temperature of 800 to 1300 ° C. In addition, the air from the secondary air blowing port 7 has a high load surface, and the combustion chamber 5 has a high load surface.
Since the shredder dust 1 is rapidly burned and melted, low-temperature volatile substances such as zinc, lead and chloride volatilize and are easily discharged to the outside of the blast furnace. On the other hand, the combustion residue gathers as a melt in the hearth. This melt is continuously discharged using the pressure of the air supplied from the tuyere 3, that is, without being accumulated in the hearth due to the gas pressure at the bottom of the blast furnace, through the discharge gutter 8. When this melted discharge is put in the settler 9, it is separated into a slag 10 and a mat 11 containing valuable metal due to the difference in specific gravity. This slag 10 is transported to the landfill as a volume-reduced waste, or used as a civil engineering material, and valuable metal is recovered from the mat by known means. Also, dust containing valuable metals is recovered from the exhaust gas.

[0014]

Next, the present invention will be described based on examples.
The invention is not limited by these examples. Example 1 Shredder dust processing capacity is about 130 kg
/ H, and the coke was loaded into a small blast furnace in which a refractory was used on the inner surface of the furnace wall and ignited. Approximately 1 hour after ignition, a thermocouple (Hereus Electronite Co., Ltd. N
After measuring the combustion temperature using SL300-300A) and confirming that the surface temperature of the coke has reached 1200 ° C, while supplying tuyere air at a flow rate of about 3000 m ³ / hour, a cotton-like material is introduced from the charging port. Fiber 12.0%, Plastics 23.1%, Rubber 6.0%, Papers 3.4%, Polyethylene film 7.0%, Wood pieces 1.1%, Substrate pieces 1.6
%, Glass 3.2%, copper wire 1.9%, metal piece 11.9
%, And shredder dust (water content about 4%, bulk specific gravity 0.3) consisting of 24.8% of powder of -4.7 mesh and 13
0 kg / hour, 9.1 kg / hour of calcium carbonate, 8.5 kg / hour of silica, and 12 k of coke.
Combustion melting treatment was performed while adding at a rate of g / hour. At the same time, fine powder of slaked lime was continuously sprayed to the bag filter inlet flue to neutralize SO _x and HCl in the exhaust gas.

The molten material of the combustion residue gathering in the hearth is
Using the pressure of the air supplied from the tuyere, the gas pressure at the bottom of the blast furnace did not allow it to accumulate in the hearth, but it passed through the discharge gutter and was continuously discharged into the settler. The discharged melt was separated into slag and a mat containing copper and iron due to the difference in specific gravity. Bag dust containing valuable metals was recovered from the exhaust gas.
The composition (% by weight) of the obtained slag, matte and bag dust was as follows, and the elution values of the harmful substances by the extraction test based on the Environmental Agency Notification No. 13 regarding the molten slag cleared all the regulated values. .

[0016]

[0017]

[0018]

The analysis values of the exhaust gas at the inlet of the bag filter (% in the table is the moisture content standard volume%) are as follows, and the smoke concentration CO concentration of 50 ppm (O ₂ 12%, which is a guideline of the Ministry of Health and Welfare). The converted value) and below were cleared.

Example 2 A coke oven similar to the one used in Example 1 was used and coke was used.
The coke surface temperature is 1220 ° C.
From the time it reaches ^Three/of time
While supplying at a flow rate, 32.2% cotton-like fiber
Rustics 25.0%, rubber 17.6%, papers
2.4%, polyethylene film content 1.9%, wood chips 1.
0%, substrate piece 0.1%, glass 0.8%, copper wire 1.5
%, Metal pieces 5.9%, and -4.7 mesh powder 1
Shredder dust consisting of 1.6% (water content 10.4
%) At a rate of 150 kg / hour and 18 kg / hour of gypsum
While adding coke at a rate of 15 kg / hour
Burned and melted. At the same time, bag filter inlet flue
Is continuously sprayed with fine powder of slaked lime, and SO in exhaust gas_x
And HCl were neutralized. Operation in Example 1
Slag, mat and bag dust obtained in the same manner as
The composition (% by weight) was as follows.

[0021]

[0022]

[0023]

[0024]

By carrying out the method for combustion and melting shredder dust of the present invention, the volume of waste can be reduced and valuable metals can be efficiently recovered.
Further, it is possible to maintain the combustion condition in the combustion chamber in accordance with the guidelines of the Ministry of Health and Welfare for preventing the generation of dioxins.

[Brief description of the drawings]

FIG. 1 is a process drawing showing an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the main part of the blast furnace used in the shredder dust combustion and melting treatment method of the present invention in a used state.

[Explanation of symbols]

 1 Shredder dust 2 Charging damper 3 Tuyere 4 Lump containing fuel or ore powder and fuel powder 5 Combustion chamber 6 Dust chamber 7 Secondary air inlet 8 Discharge gutter 9 Settler 10 Slag 11 Mat

Claims (5)

[Claims] 1. A shredder dust containing valuable metals and a lump fuel are charged from a charging port of an air blast furnace, an oxygen source for combustion is supplied from a tuyere, and the load of the shredder dust in the air blast furnace is kept low. Secondary air is blown onto the load-bearing surface to maintain the combustion chamber at a high temperature, and the gas pressure at the bottom of the furnace continuously discharges the molten material in the furnace without accumulating it in the furnace floor. A method for combusting and melting shredder dust, which comprises separating dust containing valuable metal from exhaust gas and separating it into a mat containing dust. 2. A shredder dust containing valuable metals and a briquettes containing ore powder and fuel powder are charged from the inlet of the blast furnace, and an oxygen source for combustion is supplied from the tuyere, and inside the blast furnace. Keep the load of shredder dust at a low level, blow secondary air to the load surface to maintain a high temperature in the combustion chamber, and continuously discharge the melt in the furnace by the gas pressure at the bottom of the furnace without accumulating it in the furnace floor. A method for combusting and melting shredder dust, characterized in that the melt discharge is separated into slag and a mat containing valuable metal, and dust containing valuable metal is recovered from the exhaust gas. 3. The load of shredder dust is 100 to 50.
3. The method for combustion melting treatment of shredder dust according to claim 1, wherein the method is maintained at 0 mm. 4. The pressure in the combustion chamber is -10 mmA in gauge pressure.
The method for combustion melting treatment of shredder dust according to claim 1, 2 or 3, wherein the method is adjusted to about q to -20 mmAq. 5. A shredder dust containing copper is used, and together with the shredder dust, at least one selected from the group consisting of calcium carbonate, calcium hydroxide, gypsum and silica stone.
The method for combusting and melting shredder dust according to claim 1, 2, 3 or 4, wherein different types of flux are charged and copper is recovered from the mat.