JP3527149B2 - Industrial waste treatment method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating industrial waste, and in particular, when melting metal-containing industrial waste in a high temperature melting furnace, the molten metal eluted by this melting is separated from slag. The present invention relates to a method for treating industrial waste, which enables recovery by collection.

[0002]

2. Description of the Related Art As a method of treating metal-containing industrial wastes such as automobiles and home electric appliances, a method of melting these industrial wastes in a high temperature melting furnace is used. An example of this melting treatment method will be described with reference to FIG. Figure 2
In the above, the industrial waste W1 or the crushed product W2 thereof is introduced from an inlet 62 provided at the base of the rotary kiln 60, and hot air is supplied by a first burner 63 installed at this base, for example, at a temperature of 1400 ° C. or higher. To be melted. By this melting, the combustible substances in the industrial waste are thermally decomposed and gasified, while the incombustible substance containing metal becomes a fluid F in a molten state or a semi-molten state depending on the temperature in the rotary kiln.

The produced gas component is sent from the open end 65 of the rotary kiln to the secondary combustion chamber 3, and in this secondary combustion chamber 3, the hot air from the second burner 34 and the air supply pipe 35 are further supplied.
The air is supplied from the combustion chamber and burned at a high temperature to decompose, for example, dioxins and odorous substances and the like, and discharged as combustion gas G from the discharge port 33 of the secondary combustion chamber. Although not shown, the combustion gas G is further released into the atmosphere through a heat exchange process, a quench process for preventing dioxin regeneration, a dust and harmful gas removal process, and the like.

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 water granulation pit 4. The fluid F introduced into the water granulation pit 4 is
It is water-cooled inside and is crushed to be 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 above industrial waste treatment method, the fluid F produced in the rotary kiln by melting is generally a mixture of metal and slag. The composition of this slag is usually composed mainly of SiO ₂ / Al ₂ O ₃ / CaO. For example, SiO ₂ is 32 to 45% by weight and Al ₂ O ₃ is 10 to 30% by weight. , CaO is 7-14
It accounts for weight% and the balance is Fe oxide. Since the slag having this composition has a high melting temperature and a high viscosity of the melt, for example, in order to make the inside of the rotary kiln 60 flow toward the granulation pit 4, it is necessary to set the furnace temperature to 1400 ° C. or higher. It was Alumina refractory bricks have been used as refractory linings in rotary kilns to withstand this high temperature.

[0006]

In the above industrial waste treatment method, the crushed mass R obtained contains C including Fe and C.
It contains useful or expensive metals such as u, Au, Ag. However, recovery of these 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 molten slag form a composite body in the rotary kiln and are separated from each other. This is because the work of collecting the metal by selecting the crushed mass R obtained after crushing this fluid F in the water crushing pit 4 was not economically attractive. Owing to the high temperature, oxidation is also promoted in the slag, and in particular Cu is oxidized, which may make it difficult to form a molten metal layer. Further, in the above industrial waste treatment method, there is 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 life of the melting furnace is short. It was The present invention has been made to solve the above problems, and therefore, a first object thereof is to melt molten metal which is eluted by the melting when the metal-containing industrial waste is introduced into a melting furnace and melted. An object of the present invention is to provide a method for treating industrial waste, in which the slag can be separated and recovered. A second object of the present invention is to prevent melting damage of the melting furnace and extend the service life of the melting furnace.

[0007]

Means for Solving the Problems The present invention to solve the foregoing problems, industrial waste containing metal (hereinafter, simply referred to as "industrial waste") is introduced into the rotary kiln type melting furnace melting And a cooling crushing step of cooling and crushing a fluid consisting of molten metal and molten slag generated by this melting step, wherein the melting step is performed by this melting. So that the melting temperature of the generated slag becomes 1400 ° C or lower,
Adjust the basicity (CaO / SiO ₂ weight ratio) of this slag
By increasing the fluidity of the molten slag,
The molten metal and the molten slag in the melting furnace
Separation by the difference in specific gravity of the
In a state where the metal and the molten slag are separated from each other,
It is made to flow from the melting furnace and cooled and crushed in the water tank of the water granulation pit.
And to provide the resulting Ru industrial waste processing method and a metal and slag as separate delumped.

Generally, the industrial waste is treated with a rotary kiln.
When it is introduced into a type melting furnace and melted, the metal contained in the industrial waste is eluted and slag is generated. When the basicity of this slag is adjusted within a specific range, the crystal composition changes, and the melting temperature decreases to 1400 ° C or lower. Then, it was found that the viscosity of the molten slag is remarkably reduced in the region of the crystal composition where the melting temperature is 1400 ° C. or lower. Therefore, if the basicity is adjusted so that the melting temperature of the slag is 1400 ° C. or less, the viscosity of the molten slag decreases and the fluidity increases, and the molten metal becomes a lower layer of the slag and contacts oxygen with the temperature decrease. Therefore, the oxidation is prevented, and the molten slag and the molten metal are well separated in the rotary kiln type melting furnace due to the difference in specific gravity. If the molten metal and molten slag are well separated in the rotary kiln type melting furnace, when the molten metal and the slag are introduced into the water granulation pit from this melting furnace and cooled and crushed, the metal and the slag will form different lumps. Since it can be obtained, it is possible to collect the metal at a high recovery rate by selecting the crushed metal ingot by, for example, the magnetic beneficiation method. Also, rotary kill
In the case of an internal melting furnace, the upper end of the inclined rotary tubular melting furnace
By introducing industrial waste from the department and heating and melting
When the molten metal and molten slag are well separated, the lower opening
Since it is continuously discharged from the discharge end, it is easy and continuous.
The metal can be recovered.

In the above, the basicity of the slag is 0.3.
It is preferably adjusted within the range of 5 to 1.35. The original melting temperature of slag generated from various industrial wastes is approximately 1400 ° C. or higher as described above, but it differs depending on the composition of the industrial waste. However, in any industrial waste, if the basicity of the slag is adjusted within the above range, the melting temperature can be lowered to 1400 ° C or lower. When the basicity is less than 0.35, it is difficult to set the melting temperature of the slag to 1400 ° C or lower.
When the basicity exceeds 1.35, the amount of the slag melting agent 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 melting agent containing CaO. Generally, the basicity (CaO / Si) of slag produced when metal-containing industrial waste such as automobiles and home appliances is melted.
O ₂ weight ratio) is about 0.15 to 0.3. Comparing this with the basicity (0.35 to 1.35) that makes the melting temperature of the slag 1400 ° C. or lower, CaO is insufficient. Therefore, the basicity can be adjusted within the range of 0.35 to 1.35 by adding the slag melting agent containing CaO to the melting furnace. Examples of CaO-containing slag melting agents include, for example, limestone, slaked lime, neutralized precipitates containing CaO, or CaO-rich slag obtained in other manufacturing processes.

A reducing agent containing C (carbon) may be added to the inside of the melting furnace. When the industrial waste is melted in the melting furnace, at least the melt is preferably placed in a reducing atmosphere in order to prevent the metal from being oxidized and converted into slag. If the industrial waste contains a large amount of C components (combustible substances) such as organic substances, these unburned C components will melt into the melt in the melting furnace to form a reducing atmosphere, but there is no problem, but it has already been incinerated. 2% to 20% by weight based on the amount of industrial waste treated, if treated or small
By adding a reducing agent containing about C, valuable metal can be reduced, and it is possible to prevent metal loss due to migration of molten metal to the slag side by oxidation. Preferable examples of the reducing agent containing C include coke, pulverized coal, coal, and waste organic material.

At least a portion of the melting furnace which is in contact with the slag is preferably covered with a basic magnesia refractory material containing MgO as a main component. As described above, when the slag melting agent containing CaO is added to increase the basicity in order to make the melting temperature of the slag 1400 ° C. or lower, the alumina-based refractory material conventionally used for the inner wall of the melting furnace is
Al ₂ O ₃ component in the refractory material and C in the slag melting agent
It reacts with aO to form a low melting point compound, which lowers the durability of the furnace. When 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.

[0013]

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an industrial waste melting apparatus used in the method of the present invention. This melting device is basically the same as the conventional melting device shown in FIG.
However, the inner wall of the rotary kiln is covered with basic magnesia bricks, specifically magnesia chromia bricks.

In FIG. 1, this industrial waste melting apparatus generally comprises a carry-in mechanism 1, a rotary kiln 2, a secondary combustion chamber 3 and a water granulation pit 4. Loading mechanism 1
Is equipped with a mechanism 11 for carrying in large industrial waste W1 and a mechanism 12 for carrying in crushed or small industrial waste W2 by a conveyor according to the state of industrial waste to be processed. The rotary kiln 2 is installed so that the cylindrical body portion 21 inclines downward from the base portion toward the open end portion 25, and is rotated by the rotation mechanisms 24 and 24 with the center axis of the cylinder as the rotation axis. . The inner wall of the body portion 21 is covered with magnesia-chromia brick as described above. An intermediate heating facility (not shown) is provided in the middle of the body 21. At the base of the rotary kiln 2, an inlet 22 for the industrial wastes W1 and W2 and a first burner 23 are provided, and the lower open end 25 is open to the lower end of the secondary combustion chamber 3.

The secondary combustion chamber 3 is an upright tube body,
A discharge port 31 for the fluid that communicates with the water granulation pit 4 is provided at the lower end portion, and an opening 32 for receiving the open end portion 25 of the rotary kiln is formed in the pipe wall above the discharge port 31. In addition, a discharge port 33 is provided above the secondary combustion chamber 3,
It is connected to an exhaust gas aftertreatment device (not shown) by a duct. A second burner 34 and an air supply pipe 35 for burning exhaust gas at a high temperature are provided in an intermediate portion of the secondary combustion chamber 3. The exhaust gas post-treatment device includes a heat exchanger, a quench device for preventing dioxin regeneration, a dust / toxic gas exclusion device, and the like, and the exhaust gas passing through these devices is finally released into the atmosphere. Granulation pit 4
It 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 carrying out the crushed crushed mass R.

Next, an embodiment of the present invention using the industrial waste melting 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 lower, for example, 1350.
Heat to ℃. Next, for example, a press crushed body of an abandoned automobile (industrial waste W2) is conveyed to the base of the rotary kiln by the carry-in mechanism 12 with a conveyor and introduced into the body 21 from the introduction port 22. In the rotary kiln system, the press crushed body does not have any particular problem in shape, and can be melt-processed as long as it can be added in the form of powder or an integrated product. In other melting furnace systems (eg gasification melting furnace),
Pretreatment is important in terms of shape, pelletization is preferred, and monoliths and pressed products are inappropriate.

At this time, a precalculated amount of slaked lime corresponding to the amount of industrial waste W2 introduced is simultaneously introduced from the carry-in mechanism 12 as a slag melting agent. The amount of slaked lime introduced is such that the melting temperature of the slag S produced by melting is 140
It is an amount by which the basicity (CaO / SiO ₂ weight ratio) of the slag S can be adjusted so as to be 0 ° C. or lower, for example, 1350 ° C., and is calculated in advance by the 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, the combustibles are decomposed and gasified, while the non-combustible substance containing metal is the above-mentioned in the rotary kiln. The fluid F is in a molten state or a semi-molten state depending on the temperature.

The generated gas component is sent from the open end 25 of the rotary kiln 2 to the secondary combustion chamber 3, where hot air from the second burner 34 and air from the air supply pipe 35 are further fed. When supplied, it is burned at a high temperature to decompose, for example, dioxins and malodorous substances, and is discharged from the discharge port 33 as combustion gas G toward the post-treatment process.

The fluid F formed in the rotary kiln 2 flows along the inclination of the body portion 21, while the slag S and Fe which have increased basicity and increased fluidity due to the addition of slaked lime during this period. Is separated from the molten metal M containing as a main component and containing other metal due to the difference in specific gravity. The molten metal M and the molten slag S flow down from the open end 25 of the rotary kiln in a state where they are separated from each other, and the molten metal M and the molten slag S flow into the water tank 41 of the water granulation pit 4.
It is cooled inside and crushed into crushed mass R. At this time, the metal and slag are obtained as separate lumps. The obtained crushed mass R is carried out by the conveyor 42. The obtained crushed mass R is
For example, a magnetic beneficiation device or the like can be used to easily separate the crushed lumps of metal and crushed slag.

(Test Example) In the industrial waste melting apparatus shown in FIG. 1, a press crushed body of an abandoned automobile was used as the industrial waste W2, and slaked lime was used as the slag melting agent. As shown in (1), various changes were made and melting was performed at a melting temperature of 1350 ° C. The metal crushed mass was separated by a magnetic beneficiation apparatus, and the Cu recovery rate at each basicity was measured. The results are shown in Table 1.

[0023]

[Table 1]

As is apparent from Table 1, when the slag melting agent was added to change the basicity of the slag within the range of 0.35 to 1.35, the high Cu content was 90% by weight or more. A recovery rate was obtained. Compared to this, the basicity is 0.35
When it is less than 1, the Cu recovery rate is low, indicating that the molten metal and the slag are not sufficiently separated in the melting furnace.

[0025]

INDUSTRIAL APPLICABILITY The industrial waste treatment method of the present invention is capable of treating irrespective of the shape of the treated matter, and the basicity of the slag is controlled so that the melting temperature of the slag produced by melting is 1400 ° C. or lower. Since 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. Become.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a melting apparatus used in the industrial waste treatment method of the present invention.

FIG. 2 is a sectional view showing an example of a melting device used in a conventional industrial waste treatment method.

[Explanation of symbols]

1, 11, 12: loading mechanism 2: Rotary kiln 21: trunk 22: Inlet 23: First burner 24; Rotation mechanism 25: Open end 3: Secondary combustion chamber 4: Granulation pit 41; water tank 42: conveyor W1: Industrial waste W2: Industrial waste or crushed products F: Fluid S: Slag M: Molten metal R: lump

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Fumihiko Ogino 4049, Naoshima-cho, Kagawa-gun, Kagawa 1 Mitsubishi Material Corporation Naoshima Smelter (72) Inventor Noboru Iwata 5-9-11 Kitashinagawa, Shinagawa-ku, Tokyo No. Sumitomo Heavy Industries, Ltd. (72) Inventor Yoshitaka Ishikawa 5-9-11 Kitashinagawa, Shinagawa-ku, Tokyo Sumitomo Heavy Industries, Ltd. (56) Reference JP-A-9-108651 (JP , A) JP-A-7-155728 (JP, A) JP-A-6-293580 (JP, A) JP-A-11-1725 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) B09B 3/00

Claims (5)

(57) [Claims] A melting step of melting by introducing industrial waste rotary kiln melting furnace containing 1. A metal produced by the melting process, molten metal and molten slag
A method of treating industrial waste, comprising cooling and crushing a fluid consisting of slag, wherein the melting step is performed so that the melting temperature of the slag produced by this melting is 1400 ° C. or lower. The molten slag by adjusting the degree (CaO / SiO ₂ weight ratio)
In the melting furnace by increasing the fluidity of
The molten metal and the molten slag are separated by the difference in specific gravity between them.
Separate, the cooling and crushing step, the molten metal and the molten slag
Are separated from each other and allowed to flow down from the melting furnace,
Cool and crush in the water tank of the crushing pit to separate metal and slag from each other.
A method for treating industrial waste, characterized in that it is obtained as a crushed mass . 2. The basicity of the slag is 0.35 to 1.
The industrial waste treatment method according to claim 1, wherein the industrial waste treatment method is adjusted within the range of 35. 3. The industrial waste treatment method according to claim 1, wherein the basicity of the slag is adjusted by adding a slag melting agent containing CaO. 4. The industrial waste treatment method according to claim 1, wherein a reducing agent containing C (carbon) is added to the inside of the melting furnace. 5. The basic magnesia-based refractory material containing MgO as a main component is coated on at least a portion of the melting furnace, which is in contact with the slag, in any one of claims 1 to 4. The described industrial waste treatment method.