JP2004090004A - Industrial waste treatment plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an industrial waste treatment plant in which industrial wastes W1, W2 containing metals is introduced into and melted in a rotary kiln type melting furnace 2 and molten metals M can be recovered separately from slag S. <P>SOLUTION: The plant comprises the rotary kiln type melting furnace 2 in which the industrial wastes W1, W2 is melted, water granulation means 4 for water granulating a fluid F produced in the melting furnace 2 comprising molten metals M and molten slag S, and a charging mechanism 1 for introducing the industrial wastes W1, W2 and flux into the melting furnace 2, wherein the molten metals M are separated from the molten slag S in the melting furnace 2 due to the specific gravity difference between them by introducing the flux into the melting furnace 2 so as to increase the fluidity of the molten slag S. The water granulation means 4 comprises a water tank 41 in which the fluid F discharged from the melting furnace 2 is water granulated. The molten metals M and the molten slag S separated from each other flow down out of the melting furnace 2 into the water tank 41 and water granulated therein. Thus, metal cakes and slag cakes are recovered separately from each other. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an industrial waste treatment apparatus, and particularly when metal-containing industrial waste is melted in a high-temperature melting furnace, molten metal eluted by this melting can be separated and recovered from slag. The present invention relates to an industrial waste treatment device.

(4) As one method of treating metal-containing industrial waste such as automobiles and home appliances, a method of melting these industrial wastes in a high-temperature melting furnace is used. An example of a processing method using this melting will be described with reference to FIG. In FIG. 2, the industrial waste W1 or the crushed product W2 is introduced from an inlet 62 provided at a base of a rotary kiln 60, and hot air is supplied by a first burner 63 provided at the base. Melted at temperature. This melting causes the combustibles in the industrial waste to be thermally decomposed and gasified, while the non-combustible substances containing metals become a molten or semi-molten fluid F depending on the temperature in the rotary kiln.

The generated gas component is sent from the open end 65 of the rotary kiln to the secondary combustion chamber 3, where the hot air from the second burner 34 and the air supply from the air supply pipe 35 are further supplied to the secondary combustion chamber 3. And decomposes, for example, dioxin and malodorous substances, and is discharged as combustion gas G from an outlet 33 of the secondary combustion chamber. Although not shown, the combustion gas G is further released into the atmosphere through a heat exchange step, a quench step for preventing dioxin regeneration, a dust and harmful gas removal step, and the like.

The fluid F generated in the rotary kiln flows along the inclination of the body 61 of the rotary kiln, and is discharged from the open end 65 to the granulation pit 4. The fluid F introduced into the granulation pit 4 is water-cooled and crushed in the granulation pit 4 to form a crystalline or non-crystalline crushed mass R, which is carried out by the conveyor 42. This crushed mass R has been conventionally used for civil engineering construction such as landfill and construction materials.

In the method for treating industrial waste, the fluid F generated in the rotary kiln by melting is generally a composite of metal and slag. The composition of the slag is _typically a mainly composed of _{SiO 2 / Al 2 O 3 /} CaO, in one example, SiO ₂ is 32 to 45 wt%, _Al 2 _{O 3} is 10 to 30 wt% , CaO accounts for 7 to 14% by weight, and the remainder is Fe oxide or the like. Since the slag having this composition has a high melting temperature and a high viscosity of the melt, for example, in order to flow the inside of the rotary kiln 60 toward the granulation pit 4, the furnace temperature needs to be 1400 ° C or more. Was. To withstand this high temperature, alumina-based refractory bricks have been used as a refractory lining of a rotary kiln.

In the above-mentioned method for treating industrial waste, the obtained crushed mass R contains useful metals or expensive metals such as Fe, Cu, Au and Ag. However, recovery of such useful metals has not been attempted so far. The reason is that the viscosity of the fluid F in the rotary kiln is extremely high due to the high melting temperature and high viscosity of the slag, so that the molten metal and the molten slag form a hybrid and separate in the rotary kiln. This is because the operation of selecting the crushed mass R obtained after crushing the fluid F in the water crushing pit 4 and collecting the metal was not economically satisfactory. Owing to the high temperature, oxidation is promoted in the slag, and particularly, Cu is oxidized, and it has been difficult to form a molten metal layer.
Further, in the above-mentioned industrial waste treatment method, there is also a problem that the inner wall of the rotary kiln is easily melted due to the high melting temperature of the fluid F in the rotary kiln as described above, and the service life of the melting furnace is short. Was.
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a first object of the present invention is to introduce a molten metal which is eluted by melting when metal-containing industrial waste is introduced into a melting furnace and melted. It is an object of the present invention to provide an industrial waste treatment method capable of separating and recovering slag from slag. A second object of the present invention is to prevent the melting of the melting furnace and extend the service life of the melting furnace.

In order to solve the above-described problems, the present invention provides a rotary kiln type melting furnace for melting metal-containing industrial waste, and cooling and crushing for cooling and crushing a fluid comprising molten metal and molten slag generated in the melting furnace. And an industrial waste treatment apparatus comprising means for introducing the industrial waste and the slag melt into the melting furnace, and introducing the slag melt into the melting furnace. The basicity of the slag (CaO / SiO ₂ weight ratio) is adjusted so that the melting temperature of the slag generated by melting the industrial waste in the melting furnace is 1400 ° C. or less, and the fluidity of the molten slag is increased. In the melting furnace, the molten metal and the molten slag are separated from each other by a difference in their specific gravities, and the cooling and crushing means discharges the molten slag from the melting furnace. A water tank for cooling and crushing the fluid to be flowed down from the melting furnace in a state where the molten metal and the molten slag are separated from each other, and cooled and crushed in the water tank to separate the metal and the slag. It is characterized by being obtained as a crushed mass.

Generally, when the industrial waste is introduced into a rotary kiln-type melting furnace and melted, metal contained in the industrial waste is eluted and slag is generated. When the basicity of the slag is adjusted to a specific range, a change in crystal composition occurs, and the melting temperature decreases to 1400 ° C. or lower. It was found that the viscosity of the molten slag was significantly reduced in the region of the crystal composition where the melting temperature was 1400 ° C. or lower. Therefore, if the basicity is adjusted so that the melting temperature of the slag becomes 1400 ° C. or less, the viscosity of the molten slag decreases and the fluidity increases, and as the temperature decreases, the molten metal becomes a lower layer of the slag and comes into contact with oxygen. Therefore, the oxidation is prevented, and the molten slag and the molten metal are separated well in the rotary kiln type melting furnace due to the difference in specific gravity.
If the molten metal and the molten slag are well separated in the rotary kiln type melting furnace, the metal and the slag are separated from each other when they are introduced from this melting furnace into a granulation pit as cooling crushing means and cooled and crushed. Since they are obtained as different crushed masses, crushed metal lumps can be sorted out by, for example, a magnetic separation method, and the metal can be collected at a high recovery rate.
In the case of a rotary kiln type melting furnace, industrial waste is introduced from the upper end of the inclined rotary cylindrical melting furnace and is heated and melted, so that the molten metal and the molten slag are opened downward in a well separated state. Since the metal is continuously discharged from the end, the metal can be collected easily and continuously.

In the above, there is provided a magnetic ore separation apparatus for separating the crushed mass obtained by the cooling crushing means into metal crushed fragments and slag crushed fragments.
In this case, various kinds of metals including noble metals such as copper and gold can be surely recovered at a high recovery rate as crushed metals.
In the above, it is preferable that the basicity of the slag is adjusted within the range of 0.35 to 1.35.
The original melting temperature of slag generated from various industrial wastes is approximately 1400 ° C. or higher as described above, but individually varies depending on the composition of the industrial waste. However, in any of the industrial wastes, if the basicity of the slag is adjusted within the above range, the melting temperature can be lowered to 1400 ° C. or less. If the basicity is less than 0.35, it is difficult to reduce the slag melting temperature to 1400 ° C. or lower. If the basicity exceeds 1.35, the amount of slag flux required for this adjustment increases, the amount of slag discharged increases, and the operating efficiency decreases.

The basicity of the slag is preferably adjusted by adding a slag flux containing CaO.
Generally, the basicity of slag produced upon melting the metal-containing industrial wastes, such as automobiles and household appliances (CaO / SiO ₂ weight ratio) is about 0.15 to 0.3. When this is compared with the basicity (0.35 to 1.35) at which the melting temperature of the slag is 1400 ° C or lower, CaO is insufficient. Therefore, the basicity can be adjusted to the range of 0.35 to 1.35 by adding the slag flux containing CaO to the melting furnace. Examples of CaO-containing slag melting agents include, for example, limestone, slaked lime, neutralized precipitates containing CaO, or slags rich in CaO obtained in other production processes.

A reducing agent containing C (carbon) may be added into the melting furnace.
When the industrial waste is melted in a melting furnace, at least the melt is preferably placed in a reducing atmosphere in order to prevent a shift to slag due to oxidation of the metal. If the industrial waste contains a large amount of C components (combustibles) such as organic substances, there is no problem because these unburned C components are dissolved into the melt in the melting furnace to form a reducing atmosphere, but there is no problem. If the amount is reduced, or if the amount is small, a valuable metal can be reduced by adding a reducing agent containing C in an amount of about 2% to 20% by weight based on the amount of the industrial waste to be processed, and the molten metal is converted into slag by oxidation. The metal loss due to the shift to the side can be prevented. Examples of the reducing agent containing C preferably include coke, pulverized coal, coal, and organic waste materials.

It is preferable that at least a portion of the melting furnace in contact with the slag is coated with a basic magnesia-based refractory material containing MgO as a main component.
When the slag melting agent containing CaO is added to increase the basicity in order to reduce the melting temperature of the slag to 1400 ° C. or less as described above, the alumina-based refractory material conventionally used for the inner wall of the melting furnace is The Al ₂ O ₃ component in the refractory material and the CaO in the slag melting agent react to form a low-melting compound, thereby lowering the durability of the furnace. If the basic magnesia-based refractory material containing MgO as a main component is used as the refractory material for the furnace wall, the furnace wall is not eroded even if the basicity is increased, and the durability of the melting furnace is improved.

The industrial waste treatment apparatus of the present invention can treat regardless of the shape of the treated material, and adjusts the basicity of the slag so that the melting temperature of the slag generated by melting is 1400 ° C. or less. Therefore, when the metal-containing industrial waste is introduced into the melting furnace and melted, the metal and the slag can be easily separated, and the useful metal or the expensive metal can be advantageously recovered.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of the industrial waste treatment apparatus of the present invention. This processing apparatus is basically the same as the conventional processing apparatus shown in FIG. 2, except that the inner wall of the rotary kiln is covered with a basic magnesia brick, specifically, a magnesia-chromia brick.

In FIG. 1, the industrial waste treatment apparatus generally includes a carry-in mechanism 1, a rotary kiln-type melting furnace 2, a secondary combustion chamber 3, and a granulation pit (cooling and crushing means) 4.
The carrying-in mechanism 1 includes a mechanism 11 for carrying in a large-sized industrial waste W1 and a mechanism 12 for carrying in a crushed or small-sized industrial waste W2 according to the state of the industrial waste to be treated. ing.
The rotary kiln type melting furnace 2 is installed such that the cylindrical body 21 is inclined downward from the base toward the open end 25, and is rotated by the rotation mechanisms 24, 24 about the center axis of the cylinder as the rotation axis. Has become. The inner wall of the body 21 is covered with magnesia-chromia brick as described above. An intermediate heating facility (not shown) is provided at an intermediate portion of the body 21.
At the base of the rotary kiln type melting furnace 2, an inlet 22 for industrial waste W 1, W 2 and a first burner 23 are provided, and a lower open end 25 is open to a lower end of the secondary combustion chamber 3. .

The secondary combustion chamber 3 is an upright pipe, and a discharge port 31 for the fluid leading to the granulation pit 4 is provided at the lower end, and the open end 25 of the rotary kiln is provided on the pipe wall above the pipe. Receiving opening 32 is formed. A discharge port 33 is provided at an upper portion of the secondary combustion chamber 3 and is connected to an exhaust gas after-treatment device (not shown) by a duct. An intermediate portion of the secondary combustion chamber 3 is provided with a second burner 34 for burning exhaust gas at a high temperature and an air supply pipe 35. The exhaust gas aftertreatment device includes a heat exchanger, a quench device for preventing dioxin regeneration, a device for removing dust and harmful gases, and the like, and the exhaust gas passing through these devices is finally released into the atmosphere.
The water crushing pit 4 has a water tank 41 for cooling and crushing the fluid discharged from the open end 25 of the rotary kiln, and a conveyor 42 for discharging the crushed lumps R.

Next, an embodiment of the present invention using the industrial waste treatment apparatus will be described.
First, the body 21 of the rotary kiln 2 is rotated, the first burner 23 is ignited, and the inside of the body 21 is heated to an appropriate temperature of 1400 ° C. or less, for example, 1350 ° C.
Next, for example, a press crushed body (industrial waste W2) of a waste car is transported to the base of the rotary kiln by the carrying-in mechanism 12 with a conveyor, and is introduced into the body 21 from the inlet 22. In the case of a rotary kiln system, the shape of the press crushed material does not matter in particular, and any crushed material can be melted as long as it can be charged as a powder or as an integrated material. In other melting furnace systems (eg, gasification melting furnaces), pretreatment is important with respect to the shape, pelletization is preferred, and integral and pressed products are considered unsuitable.

At this time, an amount of slaked lime calculated in advance corresponding to the introduced amount of the industrial waste W2 is simultaneously introduced from the loading mechanism 12 as a slag melting agent. The amount of slaked lime to be introduced is an amount that can adjust the basicity (CaO / SiO ₂ weight ratio) of the slag S so that the melting temperature of the slag S generated by melting is 1400 ° C. or less, for example, 1350 ° C. It is calculated in advance by a composition analysis of the slag S.

The industrial waste W2 introduced into the rotary kiln 2 together with slaked lime is melted by the hot air of the first burner 23, and combustibles are decomposed and gasified, while non-combustible substances including metals are melted by the temperature in the rotary kiln. The fluid F is in a state or a semi-molten state.

The generated gas component is sent from the open end 25 of the rotary kiln 2 to the secondary combustion chamber 3 where the secondary combustion chamber 3 receives hot air from the second burner 34 and air supply from the air supply pipe 35. For example, dioxin and odorous substances are decomposed and discharged from a discharge port 33 as a combustion gas G toward a post-processing step.

The fluid F formed in the rotary kiln 2 flows along the slope of the body portion 21 while the slag S whose basicity is increased by the addition of slaked lime and the fluidity is increased, and Fe as a main component. And the molten metal M containing other metals is separated by a difference in specific gravity. The molten metal M and the molten slag S flow down from the open end 25 of the rotary kiln while being separated from each other, and are cooled and crushed in the water tank 41 of the granulation pit 4 to form a crushed mass R. At this time, the metal and the slag are obtained as separate lumps. The obtained crushed mass R is carried out by the conveyor 42.
The obtained crushed mass R can be easily separated into crushed metal lumps and slag crushed mass by, for example, a magnetic separation device.

(Test example)
In the industrial waste treatment apparatus shown in FIG. 1, a press crushed body of an end-of-life vehicle is used as the industrial waste W2, slaked lime is used as the slag melting agent, and the basicity at this time varies as shown in Table 1. Then, melting was performed at a melting temperature of 1350 ° C. The metal lumps were separated by a magnetic beneficiation apparatus, and the Cu recovery at each basicity was measured. Table 1 shows the results.

As is clear from Table 1, when the basicity of the slag was changed within the range of 0.35 to 1.35 by adding the slag melting agent, a high Cu recovery of 90% by weight or more was obtained. Obtained. In contrast, when the basicity is less than 0.35, the recovery rate of Cu is low, indicating that the molten metal and the slag are not sufficiently separated in the melting furnace.

When metal-containing industrial waste is introduced into a melting furnace and melted, the molten metal eluted by this melting can be separated and recovered from the slag, and the melting furnace can be prevented from being melted and serviceable. The period can be extended.

It is a sectional view showing one embodiment of an industrial waste disposal device of the present invention. It is sectional drawing which shows an example of the conventional industrial waste processing apparatus.

Explanation of reference numerals

1, 11, 12: Loading mechanism 2: Rotary kiln type melting furnace 21: Body 22: Inlet 23: First burner 24; Rotating mechanism 25: Open end 3: Secondary combustion chamber 4: Granulation pit (cooling and crushing) means)
41: Water tank 42: Conveyor W1: Industrial waste W2: Industrial waste or its crushed material F: Fluid S: Slag M: Molten metal R: Crushed lump

Claims (6)

A rotary kiln type melting furnace for melting metal-containing industrial waste,
Cooling and crushing means for cooling a fluid comprising molten metal and molten slag generated in the melting furnace, comprising:
A carry-in mechanism for introducing the industrial waste and the slag melt into the melting furnace,
By introducing the slag melting agent into the melting furnace, the basicity of the slag (CaO / SiO 2) is adjusted so that the melting temperature of the slag generated by melting the industrial waste in the melting furnace is 1400 ° C. or less. ₂ weight ratio), and by increasing the fluidity of the molten slag, the molten metal and the molten slag are separated in the melting furnace by a difference in their specific gravities,
The cooling and crushing means includes a water tank for cooling and crushing the fluid discharged from the melting furnace,
The molten metal and the molten slag are flowed down from the melting furnace in a state where they are separated from each other, cooled and crushed in the water tank, and the metal and the slag are obtained as another crushed mass. Industrial waste treatment equipment. The industrial waste treatment apparatus according to claim 1,
An industrial waste treatment apparatus, comprising: a magnetic ore separation device that separates crushed lumps obtained by the cooling crushing means into metal crushed pieces and slag crushed pieces. The industrial waste treatment apparatus according to claim 1 or 2, wherein the basicity of the slag is adjusted within a range of 0.35 to 1.35. The industrial waste treatment apparatus according to any one of claims 1 to 3, wherein the basicity of the slag is adjusted by adding a slag flux containing CaO. The industrial waste treatment apparatus according to any one of claims 1 to 4, wherein a reducing agent containing C (carbon) is added into the melting furnace. The industrial waste according to any one of claims 1 to 5, wherein at least a portion of the melting furnace in contact with the slag is coated with a basic magnesia-based refractory material containing MgO as a main component. Processing equipment.

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