JP2019093372A - Treatment method for treating object including organic halide and heavy metal - Google Patents

Abstract

To provide a method for treatment of waste and the like including harmful organic halide and heavy metals, capable of inhibiting gas flue block.SOLUTION: There is provided a method for treatment of the object to be treated including organic halide and heavy metals using a blast furnace. The blast furnace 4 comprises a melting section 20, a furnace top space 24, a collection part 22 and a discharge part 28. The object to be treated includes at least lead and zinc, and the lead content of the object is 0.1 wt.% or more but 20 wt.% or less based on total weight of lead and zinc in the object. The treatment method includes: a process of melting at least a part of the object by the melting section 20; a process of decomposing the organic halide in the furnace top space 24; a process of collecting a powdery product including lead monoxide and zinc oxide discharged from the discharge part 28; and a process of collecting a melting material from the melting section 20.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method of treating objects to be treated containing harmful organic halides and heavy metals in a blast furnace.

  In recent years, the disposal of wastes containing harmful organic halides such as polychlorinated biphenyls (PCBs) and dioxins has become a problem. As wastes containing such harmful organic halides, for example, coating scraps such as bridges, etc. in which paints containing PCB and lead etc. were used from the mid 1960's to the early 1970's Low-concentration PCB waste containing heavy metals such as waste electrical equipment (eg, transformers, capacitors, OF cables) contaminated with a trace amount of PCB-contaminated insulating oil is known.

  The coating film wastes of the said bridge etc. generate | occur | produce when repainting the bridge etc. with which the coating material containing PCB was used. In repainting, first, the existing coating containing lead and PCB is peeled off, and another safe coating is newly applied. When such repainting is performed, a large amount of peeled coating film is generated in a large building such as a bridge, so that the treatment has been a problem.

  As a means to solve this problem, a processing method of separating the generated fly ash and recovering the lead while making the PCB harmless by incinerating the coating film waste with a processing device having an incinerator (see, for example, Patent Document 1) Alternatively, while supplying the coating film waste to a thermal decomposition furnace and performing at least one treatment selected from combustion, gasification, and melting in the presence of chlorine or a chlorine compound and in a reducing atmosphere, the PCB is made harmless, A treatment method (see, for example, Patent Document 2) for recovering lead chloride as fly ash dust is known.

JP, 2017-664, A JP, 2016-19947, A

As described above, in the processing methods described in Patent Documents 1 and 2, lead is concentrated to fly ash by using chloride volatilization, but harmful organic halogen compounds such as PCB are heated to a high temperature (for example, 850 ° C. or higher) Since the melting point 501 ° C of lead chloride (PbCl ₂ ) is a relatively low melting point, chlorides such as lead chloride do not solidify quickly in the exhaust gas cooling step, and fly ash is generated. May adhere to and accumulate in the flue, resulting in flue obstruction.

  An object of the present invention is to provide a treatment method capable of suppressing flue clogging in a method for recovering heavy metals while detoxifying organic halides by treating harmful organic halides and wastes containing heavy metals and the like. To provide.

The present inventors diligently studied to solve the above problems. As a result, in a method of treating an object to be treated containing an object to be treated containing an organic halide and a heavy metal using a blast furnace, lead is not a chloride (PbCl ₂ ) but a high melting point (886 ° C.) oxide (PbO ), And it is found that the above problems can be solved by adjusting the content of lead in the object to be treated to a specific range with respect to the total weight of lead and zinc in the object. We came to complete the invention. Examples of aspects of the invention are given below.

[1] A method of treating an object to be treated containing an object to be treated (A) containing an organic halide and a heavy metal, using a blast furnace,
The blast furnace comprises a melting section, a furnace top space, a recovery section and a discharge section.
The object to be treated contains at least lead and zinc, and the content of lead in the object to be treated is 0.1% by weight to 20% by weight based on the total weight of lead and zinc in the object to be treated Less than
Melting at least a portion of the object in the melting section;
Decomposing the organic halide in the furnace top space;
Recovering a powdered product containing lead monoxide and zinc oxide discharged from the discharge part;
And a step of recovering the molten material from the melting portion.

  [2] The section characterized in that the content of lead in the object to be treated is 0.1% by weight or more and 10% by weight or less based on the total weight of lead and zinc in the object to be treated ] The processing method as described in.

  [3] The heavy metal concentration in the object to be treated is 15% by weight or more and 45% by weight or less based on the total weight of the object to be treated, and the chlorine concentration in the object to be treated is The treatment method according to Item [1] or [2], which is 4% by weight or less with respect to the total weight.

  [4] The heavy metal concentration in the object to be treated is 25% by weight or more and 35% by weight or less, and the chlorine concentration in the object to be treated is 2% by weight or less. Processing method.

  [5] The temperature of the furnace top space at the time of charging the processing object (A) is 850 ° C. or more and 1300 ° C. or less, and the residence time of generated gas in the furnace top space is 2 seconds or more and 10 seconds The processing method according to any one of Items [1] to [4], which is as follows.

  [6] The temperature of the furnace top space at the time of charging the processing object (A) is 950 ° C. or more and 1100 ° C. or less, and the residence time of the generated gas in the furnace top space is 3 seconds or more and 5 seconds The processing method according to Item [5], which is as follows.

[7] A ratio [CO / CO ₂ ] of CO concentration (unit: volume%) to CO ₂ concentration (unit: volume%) in the atmosphere of the furnace top space is 0.1 or more and 4 or less. The processing method according to any one of Items [1] to [6].

[8] A ratio [CO / CO ₂ ] of CO concentration (unit: volume%) to CO ₂ concentration (unit: volume%) in the atmosphere of the furnace top space is 0.1 or more and 2 or less. The processing method according to Item [7].

  [9] The processing method according to any one of items [1] to [8], wherein the heavy metal contained in the object to be treated (A) contains lead and / or copper.

  [10] The processing method according to any one of items [1] to [9], wherein the organic halide contained in the object to be treated (A) contains polychlorinated biphenyl (PCB).

  [11] Item [1] to [10, wherein the object to be treated (A) is charged into the blast furnace separately from the other object to be treated (B) contained in the object to be treated. The processing method as described in any one of.

  [12] The apparatus according to item [11], wherein the object to be treated (A) is charged from a different charging inlet from the other object to be treated (B) in a state of being sealed in a container. How to handle

  [13] The treatment method according to Item [11] or [12], wherein the other object to be treated (B) is a briquette containing zinc and lead.

  According to the present invention, it is possible to prevent flue clogging in a method of recovering heavy metals while detoxifying organic halides by treating waste containing harmful organic halides and heavy metals in a blast furnace.

It is a figure for demonstrating an example of the processing flow which makes a processing object a briquette. It is a schematic block diagram of an example of the processing apparatus used for the processing method of this invention. It is a principal part enlarged view of the processing apparatus of FIG.

The treatment method of the present invention is a treatment method of an object to be treated containing an organic halide and a heavy metal-containing treatment object (A) using a blast furnace.
[Object to be processed]
In the treatment method of the present invention, the article to be treated means the entire article to be treated including the article to be treated (A) containing an organic halide and a heavy metal and the other article to be treated (B).

  The object to be treated contains at least lead and zinc, and the content of lead in the object to be treated is at least 0.1% by weight based on the total weight of lead and zinc in the object to be treated. % Or less, preferably 0.1% by weight or more and 10% by weight or less. By adjusting the content of lead in the object to be treated within the above range, the adhesion of the generated powdery product is alleviated, and the clogging of the flue can be effectively suppressed. This is considered to be due to the following reason. As described above, lead monoxide has a higher melting point than lead chloride, but high temperature gas discharged from the discharge part through the furnace top space may contain lead monoxide in a liquid state, When the proportion is high, the adhesion of the generated powdery product tends to be high. On the other hand, the melting point (1975.degree. C.) of zinc oxide is higher than the melting point (886.degree. C.) of lead monoxide, and becomes solid when it is formed. Therefore, by increasing the proportion of zinc oxide to be produced, it is considered that lead monoxide in a liquid state is adsorbed to zinc oxide to become a mixture of zinc oxide and lead monoxide, and the adhesion of the mixture becomes weak. In addition, content of the lead in the said to-be-processed object can be carried out in the said range by adjusting the quantity of the to-be-processed object (A) mentioned later and another to-be-processed object (B).

  The content of heavy metals and the like in each object to be treated can be measured by, for example, fluorescent X-ray analysis or ICP emission spectrometry of alkaline melting pretreatment, after collecting a sample by random sampling such as systematic sampling. .

  The heavy metal concentration contained in the object to be treated is preferably 15% to 45% by weight, more preferably 25% to 35% by weight, based on the total weight of the object to be treated. The heavy metal can be recovered at a high concentration by adjusting the heavy metal concentration contained in the object to be treated within the above range. Here, the total weight of the object to be treated in the continuous operation mode is the total weight of each object to be treated in a certain period of time, and the amount of each object to be treated, the operation system and For example, 8 hours, 12 hours, or 24 hours can be used depending on the analysis system, etc., and it is not particularly limited. The heavy metal concentration contained in the object to be treated can be brought into the above range by adjusting the amounts of the object to be treated (A) and the other object to be treated (B) described later.

  The heavy metals contained in the object to be treated are not particularly limited except lead and zinc, and examples thereof include gold, silver, copper, iron, tin, indium, antimony, bismuth, selenium, tellurium, platinum, palladium, nickel and manganese , Chromium, cadmium, mercury, and arsenic. The heavy metals other than lead and zinc may not be contained in the object to be treated, may be contained only one kind, or may be contained two or more kinds. In addition, although there is no clear definition of heavy metal, generally, a specific gravity says the metallic element of 4-5 or more. Moreover, the said to-be-processed object may contain light metals, such as magnesium, calcium, aluminum.

  The concentration of chlorine contained in the object to be treated is preferably 4% by weight or less, more preferably 2% by weight or less, based on the total weight of the object to be treated. By adjusting the concentration of chlorine contained in the object to be treated within the above range, the binding of heavy metals such as lead and zinc to chlorine is inhibited to suppress the generation of chlorides of heavy metals (that is, the chlorine volatilization reaction). (Especially lead and zinc) can be recovered as oxides. As a result, when the gas or the like discharged from the discharge part after passing through the furnace top space is cooled, lead monoxide and zinc oxide solidify quickly, so that clogging of the flue can be suppressed. In addition, chlorine in a to-be-processed object is volatilized as sodium chloride or hydrogen chloride, and is removed at the time of cooling or desulfurization of waste gas. The concentration of chlorine contained in the object to be treated can be brought into the above range by adjusting the amounts of the object to be treated (A) and the other object to be treated (B) described later.

  The chlorine concentration in each processing object can be measured by, for example, fluorescent X-ray analysis or ion chromatography of combustion pretreatment after collecting a sample by random sampling such as systematic sampling.

<Processing object (A)>
The object to be treated (A) is not particularly limited as long as it contains an organic halide and a heavy metal.

  Although the organic halide contained in the said process target object (A) will not be specifically limited if it is an organic compound which has a carbon-halogen covalent bond, For example, PCB, dioxins, brominated dioxins, organic chlorine agrochemical etc. Can be mentioned.

  The concentration of the organic halide contained in the object to be treated (A) is not particularly limited, but is within the range when it is determined by a law or the like. For example, in the case of low concentration PCB waste, it is 5,000 mg / kg or less.

  The heavy metals contained in the object to be treated (A) are not particularly limited, and examples thereof include gold, silver, copper, lead, zinc, iron, tin, indium, antimony, bismuth, selenium, tellurium, platinum, palladium, nickel , Manganese, chromium, cadmium, mercury, arsenic and the like. The object to be treated (A) may contain only one type of such heavy metal, or may contain two or more types of heavy metal.

Although the heavy metal concentration contained in the said process target object (A) is not specifically limited, For example, it is the range of 0.1 weight%-80 weight%.
Specific examples of the object to be treated (A) include, but are not limited to, coating scraps containing PCB and lead, OF cables containing PCB and copper, transformers, capacitors, various PCB deposits, etc. It can be mentioned. These may be used alone or in combination of two or more. In the treatment method of the present invention, an aspect in which the heavy metal contains lead and / or copper as the object to be treated (A), an aspect in which the organic halide contains PCB, and the organic halide contains PCB and the heavy metal is The aspect containing lead and / or copper can be suitably processed.

<Other processing object (B)>
The object to be treated in the present invention usually includes another object to be treated (B) other than the above object to be treated (A). The other object to be treated (B) is not particularly limited, and various objects to be treated can be used, for example, wastes containing heavy metals such as steelmaking smoke ash and molten fly ash etc. Be Here, the steelmaking smoke ash is smoke ash containing mainly heavy metals such as lead, zinc and iron, which are generated when steel scraps and the like are melted to manufacture steel in a steelmaking electric furnace. Is a fly ash mainly containing heavy metals such as lead and zinc which are generated when the wastes are melted and processed in a gasification melting furnace or an ash melting furnace.

  The heavy metals contained in the other object to be treated (B) are not particularly limited, and examples thereof include gold, silver, copper, lead, zinc, iron, tin, indium, antimony, bismuth, selenium, tellurium, platinum, palladium, Examples include nickel, manganese, chromium, cadmium, mercury, and arsenic. The other object to be treated (B) may contain only one type of such heavy metal or may contain two or more types of heavy metal.

The heavy metal concentration in the other object to be treated (B) is not particularly limited as long as the heavy metal concentration in the object to be treated can be adjusted to the above-mentioned range.
The other object to be treated (B) may be a briquette in consideration of handling property and operation stability at the time of charging to a blast furnace. A briquette is a compacted and solidified powdery mineral or the like. An example of a method for producing briquettes is shown below.

  First, it is necessary to make the raw material to be briquettes into a composition, shape and strength suitable for processing. Examples of main raw materials of briquette include wastes such as steelmaking smoke ash and molten fly ash, fluxes such as silica stone, coal, and other treated raw materials (for example, sludge and the like). These raw materials are mixed, dried and crushed as shown in FIG. 1, and then compression-molded by a machine (not shown) to produce briquettes. By this organization (pretreatment), it is possible to make the other processing object (B) into a shape and strength suitable for melt processing.

  In the treatment method of the present invention, zinc and lead containing briquettes can be suitably treated as the other treatment object (B). The more specific composition of the other object to be treated (B) is determined from many constraints such as slag melting point, slag fluidity, metal recovery rate, reducibility, heat quantity, exhaust gas properties, etc. Adjusted by mixing ratio of raw materials.

  However, depending on the composition of various raw materials and the degree of variation thereof, the overall composition may not be adjusted by the mixing ratio alone. Exhaust gas properties are one of the particularly important constraint conditions. That is, if low-melting point chloride is present in the exhaust gas, it will be present as a liquid when the exhaust gas is cooled, and will adhere and deposit firmly on the flue, thereby clogging the flue. In order not to form such chlorides, it is desirable to remove or reduce chlorine from the raw material.

  As a method of removing or reducing chlorine, for example, dechlorination treatment in which molten fly ash (high chlorine content) is washed at pH 10 or more and 12 or less and dehydrated is mentioned. In the molten fly ash after the dechlorination treatment, most of the chlorine is removed. Although a part remains in the form of sodium chloride or the like, when viewed from the whole object to be treated, the above-mentioned chlorine concentration in the object to be treated can be satisfied by adjusting the mixing ratio of the raw materials at the time of pretreatment. .

  In addition, if PCB wastes such as coating scraps and OF cables are subjected to the above-mentioned pretreatment, the PCBs will scatter in the working environment. Therefore, as will be described later, resin sealing is usually performed separately from briquettes. It is placed in a container etc. and charged into the blast furnace. On the other hand, when the organic halide contained in the object to be treated (A) is other than a compound such as PCB where scattering into the working environment is a problem, the object to be treated (A) is added to the other object It may be a briquette together with the object to be treated (B).

[Processing device]
Hereafter, the processing apparatus used for the processing method of this invention is demonstrated.
FIG. 2 is a schematic view showing an example of a processing apparatus that can be used in the processing method of the present invention. As shown in FIG. 2, the processing apparatus 2 includes a blast furnace 4, a boiler 6, a cooling tower 8, a bag filter 10, a fan 12, a desulfurization tower 14, and a chimney 16. By treating the material to be treated in the blast furnace 4, heavy metals are recovered while harmlessizing organic halides, and gas (exhaust gas) and the like generated in the blast furnace 4 are cooled by waste heat recovery in the boiler 6, and further cooling towers 8 Water is sprayed to quench the reaction to below 200 ° C in order to prevent the resynthesis of dioxins. Thereafter, the powdery product contained in the exhaust gas is recovered by the bag filter 10, and the exhaust gas after the powdery product is recovered is washed by the desulfurization tower 14 and discharged from the stack 16 to the outside air. In addition, although the suppression of the flue blockage is mentioned as a solution subject of the present invention, the flues in the processing apparatus 2 are passages such as exhaust gas from the boiler 6 to the chimney 16 and passage is likely to occur. , Is a flue from the boiler 6 to the bag filter 10.

<Composition of a blast furnace>
Hereinafter, the structure of the blast furnace used for the processing method of this invention is demonstrated.
FIG. 3: is the figure which expanded the part of the blast furnace 4 and the boiler 6 in the processing apparatus 2 shown in FIG. As shown in FIG. 3, the blast furnace 4 includes a melting unit 20, a furnace top space 24, a recovery unit 22, and a discharge unit 28. More specifically, the blast furnace 4 has a vertically long three-dimensional shape extending in the vertical direction, and the charging portion 4a for charging the treatment object such as briquette 5 and the treatment object such as PCB waste are charged A loading port 26, a furnace top 30, a melting section 20 for melting at least a part of the object to be treated, a melt discharge section 21 for discharging the melt from the furnace bottom, and a position above the melting section 20, A furnace top space 24 for retaining the generated gas (exhaust gas), and a discharge unit 28 for discharging exhaust gas and the like passing through the furnace top space 24 to the boiler 6 are provided. In addition, a supply unit 32 for feeding a gas such as air to the melting unit 20 is connected to the melting furnace 20 via the tuyere 18, and a recovery unit for collecting the molten material discharged from the furnace bottom in the vicinity of the melting furnace 4 22 are arranged.

[Processing method]
In the treatment method of the present invention, a step of melting at least a part of the object to be treated in the melting portion 20 (hereinafter also referred to as a “melting step”) and a step of decomposing the organic halide in the furnace top space 24 (Hereinafter also referred to as “decomposition step”), a step of recovering a powdery product containing lead monoxide and zinc oxide discharged from the discharge unit 28 (hereinafter also referred to as “recovery step 1”), and And a step of recovering the molten material from the melting portion 20 (hereinafter, also referred to as “recovery step 2”).

  In the treatment method of the present invention, the temperature of the furnace top space 24 at the time of charging the treatment object (A) is preferably 850 ° C. or more and 1300 ° C. or less, more preferably 950 ° C. or more and 1100 ° C. or less And residence time of generated gas (exhaust gas) and the like in the furnace top space 24 is preferably 2 seconds or more and 10 seconds or less, more preferably 3 seconds or more and 5 seconds or less. Thereby, the organic halide can be properly decomposed. The temperature of the furnace top space 24 can be measured by, for example, a thermocouple, and can be adjusted by the amount of air or the like blown, temperature, oxygen concentration, and the like. In addition, the residence time of the generated gas in the furnace top space 23 can be calculated by dividing the volume of the furnace top space by the amount of generated gas per time, and is adjusted by the amount of air blown, oxygen concentration, etc. Can.

In the treatment method of the present invention, the ratio [CO / CO ₂ ] (hereinafter “CO / CO ₂ ”) of the CO concentration (unit: volume%) and the CO ₂ concentration (unit: volume%) in the atmosphere of the furnace top space 23. The ratio is also preferably 0.1 or more and 4 or less, and more preferably 0.1 or more and 2 or less. Thereby, the oxidation reaction is promoted and lead and zinc oxides can be more reliably formed. The CO / CO ₂ ratio in the furnace top space 24 can be calculated by measuring the gas concentration using a commercially available flue gas measuring device (for example, a flue gas analyzer “ENDA-5000” manufactured by HORIBA) It can be adjusted by the amount of air etc. which can be blown, the oxygen concentration, etc.

  In the treatment method of the present invention, the treatment object (A) may be charged into the blast furnace 4 together with the other treatment object (B), and with the other treatment object (B) May be separately charged to the blast furnace 4. When separately charged into the blast furnace 4, the object to be treated (A) may be charged from a different loading port 26 different from the object to be treated (B) while being sealed in a container. As described above, when the object to be treated (A) is a PCB waste, there are cases where the shape is not suitable for the purpose of preventing the worker's exposure due to the scattering of PCB and mixing with the object to be treated (B). It is preferable to charge from the loading port 26 different from the said other process target object (B) in the state sealed to the container from existing things etc. In addition, when processing the object to be treated including dioxins as well as the PCB waste as the object to be treated (A), the object to be treated including dioxins and the like is sealed in a container together with the PCB waste. In the state, the blast furnace 4 may be charged from the inlet 26 different from the other object to be treated (B), and separately from the PCB waste, briquette 5 with the other object to be treated (B) 5 It may be treated as

  Hereinafter, the respective steps will be more specifically described based on the case where the object to be treated (A) is a PCB waste and the other object to be treated (B) is treated as briquette. Because each process is closely related, some of the matters described in any process may be matters belonging to other processes. Therefore, the processing method of the present invention is not limited to the contents to be described later, and should be judged in consideration of the entire description of the present specification and technical common knowledge.

<Melting process>
When the briquettes 5 are charged into the charging part 4a, the blast furnace 4 is heated, and the air preheated from the supply part 32 through the tuyere 18 to a temperature of preferably 100 to 250 ° C, more preferably 150 to 250 ° C. And the like are blown into the melting portion 20. As a result, the molten state is maintained at a temperature in the molten portion 20 of 1150 ° C. or more, and preferably in the range of 1200 to 1400 ° C., and the layer separation of slag, mat and metal becomes good. When the temperature in the melting portion 20 becomes higher than 1400 ° C., the wear of the furnace body tends to be remarkable. In addition to air, the gas blown from the tuyere 18 may be oxygen or oxygen-enriched air. By increasing the oxygen concentration, the reaction between carbon and oxygen is promoted.

When air is blown from the tuyere 18 in a state where the coal ore 5 is melted in the melting portion 20, carbon (coal) contained in the coal ore 5 reacts with air, as shown in the following reaction formula 1, Gas is generated, and the melting portion 20 becomes a reducing atmosphere.
2C + O ₂ → 2CO ... Reaction formula 1

  After the briquettes 5 are charged into the melting section 20, the PCB waste contained in the closed vessel is directly loaded into the furnace top space 24 from a loading port 26 separate from the briquettes 5. The treatment of this PCB waste is not carried out alone, but in parallel with the treatment of briquettes 5. When the PCB waste is charged into the furnace top space 24, heavy metals such as lead and copper contained in the PCB waste are melted together with the briquettes 5 in the melting section 20. Here, the reason for putting the PCB waste in the closed container is to prevent the scattering of the PCB waste during the transportation until the loading. Also, by loading from another loading port 26, it is possible to prevent the container from being exposed to high temperature for a long time and being damaged.

<Decomposition process>
When PCB waste is charged into the furnace top space 24, the PCB contained in the PCB waste is volatilized and retained in the furnace top space 24 maintained in the above-mentioned temperature range for 2 seconds or longer to be decomposed and detoxified. Be done. The upper limit of the residence time is not particularly limited, but is usually 10 seconds or less in consideration of the size of the apparatus.

Here, "decomposition" of organic halides such as PCB means to convert harmful organic halides into harmless substances (eg carbon dioxide, water, hydrogen chloride etc.) by chemical reaction, “If the organic halide is PCB, the amount of PCB contained in the exhaust gas discharged from the treatment device is 0.1 mg / m ³ or less, when the organic halide is PCB. It also means that the amount of PCB contained in the waste water discharged from the treatment apparatus is 0.003 mg / L or less.

<Recovery process 1>
In the melting furnace 4, various gases (exhaust gases) and the like are generated in the melting process and the decomposition process, and are discharged from the discharge unit 28 together with the air and the like blown into the melting unit 20.

As described above, since the melting portion 20 has a reducing atmosphere, zinc oxide (ZnO) contained in the object to be treated is reduced and volatilized as shown in the following reaction formula 2, and a metal vapor of zinc is generated.
ZnO + CO → Zn (g) + CO ₂ ... Reaction formula 2
In addition, if the above-mentioned reaction formula 1 and reaction formula 2 are combined, it will become like following reaction formula 3.
ZnO + 2C + O ₂ → Zn (g) + CO + CO ₂ ... Reaction formula 3

Further, by introducing secondary air into the furnace top space 24, as shown in the following reaction formulas 4 and 5, the metal vapor of zinc and the CO gas are oxidized, and the zinc vapor becomes zinc oxide (ZnO).
Zn (g) + 1/2 O ₂ → ZnO ... Reaction formula 4
CO + 1/2 O ₂ → CO ₂ ... Reaction formula 5

Similarly, the lead component contained in the object to be treated becomes lead monoxide (PbO) in the furnace top space 24. The CO / CO ₂ ratio in the atmosphere of the furnace top space 24 is controlled to be in the above-mentioned range.

Here, zinc oxide (ZnO) has a melting point of 1975 ° C., lead monoxide (PbO) has a melting point of 886 ° C., and these melting points are the melting point of zinc chloride (ZnCl ₂ ) 275 ° C. and lead chloride (PbCl ₂ ) The melting point is higher than the melting point of 501 ° C. and solidifies quickly in the process of cooling the exhaust gas, so the adhesion to the flue becomes weak, falling off the flue becomes easy, and clogging of the flue can be prevented.

  As described above, the exhaust gas discharged from the discharge unit 28 contains lead monoxide and zinc oxide, which solidifies and is contained in the powdery product, and is recovered by the bag filter 10. The recovered powdery product (crude zinc oxide) has a zinc concentration of about 60% and a lead concentration of about 5%, and is used as a smelting raw material in a zinc smelter.

<Recovery process 2>
The molten material melted in the melting section 20 separates into slag, mat and metal. Slag refers to a substance that separates from molten metal and floats, and is mainly an oxide of iron, silicon and calcium, and is discharged from the melt discharge part 21 to a recovery part 22 such as a settler. A mat is a mixture of metal sulfides generated by melting in a furnace, mainly containing copper sulfide, and also discharged from the melt discharge portion 21 to the recovery portion 22. Metal refers to a substance in a metallic state, which is mainly made of zinc and lead, and is produced after being reduced at the melting portion 20. Metals such as lead and zinc are volatilized, but metal components not volatilized are dissolved or suspended in the slag or mat, and are discharged together with these from the melt discharge unit 21 to the recovery unit 22.

The discharged melt is separated into slag and mat again in the recovery unit 22 (settler), and each is recovered.
Slag is crushed into water by grinding and then recycled as cement raw material. The mat is cooled and solidified and then used as a smelting raw material such as copper, gold, silver and the like in a copper smelter. The copper concentration is around 10% although it varies depending on the raw material composition.

  According to the treatment method of the present invention, detoxifying PCB using the furnace top space 24 of the blast furnace 4, recovering heavy metal at high concentration and making it as smelting raw material, making iron as cement raw material as slag It is possible to simultaneously suppress the adhesion to the flue by reducing and volatilizing zinc and lead and oxidizing them, and simultaneously recovering it as crude zinc oxide to obtain a smelting raw material.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.
Example 1
Steelmaking smoke ash 176t, demineralized molten fly ash 140t, silica stone 16t, coal 76t, and other processing raw material 160t were mixed, dried and crushed to produce 550t of briquettes having a diameter of about 100 mm by a machine making machine. The analytical grade of the obtained briquettes by fluorescent X-ray analysis is shown in Table 1.

  Using a processing apparatus as shown in FIG. 2 including a Mitsui-type zinc semi blast furnace (MF furnace) as shown in FIG. 3, the air preheated to 200 ° C. from the supply part 32 through the tuyere 18 is melted. The temperature of the melting portion 20 is increased to 1200 ° C. or higher by blowing into 20, and the briquette 150t obtained above is charged from the charging portion 4a into the blast furnace 4 for 6 hours, and the coating film scraps of the grade shown in Table 2 6 t was charged into the blast furnace 4 from the inlet 26 in a sealed state in a resin container over 6 hours. The content of lead in the object to be treated consisting of briquette and coating film scrap was 8.1% by weight based on the total weight of lead and zinc in the object to be treated. Further, the heavy metal concentration and the chlorine concentration in the object to be treated were 31.4% by weight and 1.7% by weight, respectively, with respect to the total weight of the object to be treated.

  The PCB content of the coating film waste shown in Table 2 is measured by the method described in the guideline “Measuring method for low concentration PCB containing waste (third edition)” of the Ministry of the Environment, and the content of lead and chlorine is fluorescence X It was measured by line analysis.

The temperature is maintained at about 1000 ° C., the CO / CO ₂ ratio is controlled to 0.2 to 1.3, and the residence time of the gas generated in the blast furnace is adjusted to about 4 seconds in the furnace top space 24 did. The exhaust gas and the like discharged from the discharge unit 28 were cooled by the waste heat recovery in the boiler 6 and further quenched in the cooling tower 8, and then the powdery product (crude zinc oxide) was recovered by the bag filter 10. On the other hand, the molten material melted in the melting unit 20 was discharged from the molten material discharge unit 21 to the collection unit 22 (settler), separated into slag and mat, and then collected. The grade and amount of the recovered crude zinc oxide, mat and slag are shown in Table 3. The powdery product was slightly attached to the flue after the treatment of the object to be treated and could be easily removed.

2 processing apparatus 4 blast furnace 4a charging part 5 briquette 6 boiler 8 cooling tower 10 bag filter 12 fan 14 desulfurization tower 16 chimney 18 tuyere 20 melting part 21 molten material discharge part 22 collection part 24 furnace top space 26 inlet 28 discharge Unit 30 furnace top 32 supply unit

Claims (13)

What is claimed is: 1. A method of treating an object to be treated comprising an organic halide and an object to be treated containing heavy metal (A) using a blast furnace comprising:
The blast furnace comprises a melting section, a furnace top space, a recovery section and a discharge section.
The object to be treated contains at least lead and zinc, and the content of lead in the object to be treated is 0.1% by weight to 20% by weight based on the total weight of lead and zinc in the object to be treated Less than
Melting at least a portion of the object in the melting section;
Decomposing the organic halide in the furnace top space;
Recovering a powdered product containing lead monoxide and zinc oxide discharged from the discharge part;
And a step of recovering the molten material from the melting portion.   The content of lead in the object to be treated is 0.1% by weight or more and 10% by weight or less based on the total weight of lead and zinc in the object to be treated. Processing method.   The heavy metal concentration in the object to be treated is 15% to 45% by weight based on the total weight of the object to be treated, and the chlorine concentration in the object to be treated is the total weight of the object to be treated The treatment method according to claim 1 or 2, which is 4 wt% or less.   The processing method according to claim 3, wherein the heavy metal concentration in the object to be treated is 25 wt% or more and 35 wt% or less, and the chlorine concentration in the object to be treated is 2 wt% or less.   The temperature of the furnace top space at the time of charging the processing object (A) is 850 ° C. or more and 1300 ° C. or less, and the residence time of generated gas in the furnace top space is 2 seconds or more and 10 seconds or less The processing method according to any one of claims 1 to 4, characterized in that.   The temperature of the furnace top space at the time of charging the processing object (A) is 950 ° C. or more and 1100 ° C. or less, and the residence time of generated gas in the furnace top space is 3 seconds or more and 5 seconds or less The processing method according to claim 5, characterized in that: The ratio [CO / CO ₂ ] of CO concentration (unit: volume%) and CO ₂ concentration (unit: volume%) in the atmosphere of the furnace top space is 0.1 or more and 4 or less. The processing method as described in any one of -6. 8. The apparatus according to claim 7, wherein a ratio [CO / CO ₂ ] of CO concentration (unit: volume%) to CO ₂ concentration (unit: volume%) in the atmosphere of the furnace top space is 0.1 or more and 2 or less. The treatment method described in.   The processing method according to any one of claims 1 to 8, wherein the heavy metal contained in the processing object (A) contains lead and / or copper.   The processing method according to any one of claims 1 to 9, wherein the organic halide contained in the processing object (A) contains polychlorinated biphenyl (PCB).   The said processing object (A) is separately charged to the said blast furnace separately from the other processing object (B) contained in the said to-be-processed object. The treatment method described in.   The processing method according to claim 11, characterized in that the processing object (A) is charged from a loading port different from the other processing object (B) in a state of being sealed in a container.   The treatment method according to claim 11 or 12, wherein the other object to be treated (B) is a briquette containing zinc and lead.

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