JP4678762B2 - Method and apparatus for detoxifying heavy metal-containing substances - Google Patents

Description

  The present invention is a technique for detoxifying heavy metals contained in contaminated soil, incinerated ash, fly ash, etc., and in particular, detoxifying heavy metal-containing materials that are detoxified by heating after chlorinating heavy metals. The present invention relates to a processing method and apparatus.

Various types of heavy metals are contained in incineration ash and fly ash generated by incineration of general waste and industrial waste. Incinerators that do not have heavy metal treatment facilities may leak heavy metal-containing substances into the atmosphere, soil, and groundwater. In addition, there are environmental standards in soils such as factory sites and landfills. Heavy metals may be present in concentrations higher than those specified in. Many heavy metals are highly toxic and not only adversely affect the environment but also accumulate in the body and cause harm. In recent years, regulations on heavy metals tend to be stricter, such as the establishment of environmental standards for heavy metals contained in incinerated ash, fly ash, soil, and the like.
As one method for detoxifying substances containing heavy metals, Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-132930) discloses heating in an incinerator ash containing heavy metals at a melting point or lower. However, a method of cooling and separating and recovering after volatilizing heavy metals has been proposed. However, most of the heavy metals contained in the incinerated ash are oxides, and the heavy metals present in the form of oxides are high boiling point compounds, and thus are difficult to remove and remain in the treated product.

As a method for improving this, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-192118), as shown in FIG. 10, a waste containing heavy metals and chlorine stored in a tank 61 is heated in a rotary kiln 60. , A method of chlorinating heavy metals with a chlorine-based gas generated at that time to volatilize the heavy metals is disclosed.
In Patent Document 3 (Japanese Patent Application Laid-Open No. 11-114530), first, a chlorine-based gas is supplied to incineration ash or the like in a heating furnace to chlorinate heavy metals, and then a volatile treatment is performed in a high-temperature furnace. Is disclosed.

A method for purifying contaminated soil containing heavy metals is described in Patent Document 4 (Japanese Patent Laid-Open No. 2003-340426) and the like. In Patent Document 4, either one of a wet process and a dry process is selected in the separation process of heavy metals in the contaminated soil. In the dry process, a halogen source is added to the contaminated soil and heated to remove heavy metals. A method of volatilizing and removing as a halogen compound is disclosed.
In this way, the heavy metal-containing substance is heated in the presence of a chlorine-based gas, and the heavy metal is chlorinated to facilitate volatilization at a low boiling point, and then the temperature is raised, and the chlorinated heavy metal is volatilized and cooled, trapped. Chlorination and volatilization methods for collecting and recovering heavy metals have been proposed as an effective method for separating heavy metals.

  However, in Patent Document 2, the chlorine-based gas generated by the heat treatment is led to the exhaust gas line near the incineration ash inlet to cool the exhaust gas and recover the heavy metals. May not be sufficiently contacted with the metal, resulting in insufficient chlorination of the heavy metal, and heavy metal may remain in the treated product. Further, in Patent Document 3, there is a problem that fuel consumption is large with respect to the temperature rise of the heating furnace, and in the heating furnace, the contact efficiency between the chlorine-based gas and the processed material is poor and heavy metals remain. In Patent Document 4, there is a possibility that the halogen source introduced into the rotary kiln will be discharged together with the contaminated soil before vaporizing into chlorinated gas, and the amount of chlorinated gas generated is small and chlorination of heavy metals is not possible. There is concern about the remaining heavy metals. Furthermore, in Patent Document 5 (Japanese Patent Laid-Open No. 11-179317), as a pretreatment, a chlorine-based gas or incinerator exhaust gas from a chlorine-based gas source decomposition is used, and heavy metals such as incineration ash are heated at less than 600 ° C. A method is disclosed in which it is chlorinated and then heat-treated in a high temperature range of about 600 ° C. to 850 ° C. to volatilize and recover heavy metals. However, in this case, there is a problem that the processing time is long and the temperature control is complicated and time-consuming, and there is a problem that it cannot be applied to equipment not equipped with an incinerator.

JP 2001-132930 A JP 2002-192118 A JP 11-114530 A JP 2003-340426 A Japanese Patent Laid-Open No. 11-179317

  Therefore, in view of the above-mentioned problems of the prior art, the present invention allows heavy metals and chlorine-based gas to sufficiently come into contact with each other to efficiently chlorinate heavy metals, maintaining high removal efficiency of heavy metals and treating the heavy metals after treatment. An object of the present invention is to provide a detoxification method and apparatus for heavy metal-containing substances that can minimize the residue of metals and can simplify the operation by avoiding complications such as temperature control. To do.

Therefore, in order to solve such problems, the present invention heats an object to be processed containing heavy metals together with a chlorine-containing substance in a heating furnace, converts the heavy metals into chloride, volatilizes them, and separates and removes them. In the detoxification method for substances,
A charging hopper for supplying the workpiece into the kiln by the heating furnace ; a cylindrical furnace body having means for transferring the workpiece from the charging hopper to the other end; and the charging hopper of the furnace body; A rotary kiln having an ash discharge port provided on the other end side and a burner portion provided on the ash discharge port side of the furnace body ,
The chlorine-containing substance is a chlorine-based exhaust gas containing a chlorine content volatilized from the object to be processed, and the chlorine-based exhaust gas is provided from a gas inlet provided in the middle or downstream part in the object transfer direction of the rotary kiln. introducing city, exhaust gas was subjected to chlorination prior Symbol heavy metals in the object to be processed feeding direction upstream of and discharged from the discharge port formed in a kiln in an upstream portion the gas inlet,
The heavy metals are volatilized in a reheating furnace provided in the rotary kiln downstream of the gas inlet or on the outlet side of the rotary kiln .

According to the present invention, the chlorine-based exhaust gas and the object to be treated are brought into counter-current contact, the heavy metal is chlorinated on the upstream side in the transfer direction of the object to be treated, and the chlorinated heavy metal is volatilized on the downstream side. As a result, metals such as oxides can be efficiently chlorinated, and the removal efficiency of heavy metals can be improved. The configuration of the present invention in which the chlorine-based gas and the object to be treated are brought into countercurrent contact is the configuration that can maintain the highest reaction efficiency. Furthermore, in the present invention, a rotary kiln is adopted, and a series of treatments of chlorination and volatilization treatment can be performed simultaneously in one apparatus by utilizing the temperature gradient of the rotary kiln. Is not necessary, and the operation can be simplified.
In the present invention, the chlorine-containing substance includes, for example, a gas such as chlorine gas or hydrogen chloride gas, a chlorine-based solvent such as trichloroethylene or tetrachloroethylene, or a solid chlorine gas-generating substance. It may be supplied from other than the above, or it may be guided from within the processing system.

In addition, the introduction position of the chlorine-containing substance is provided in the middle stream portion in the transfer direction, and mainly after the chlorination of heavy metals contained in the workpiece on the upstream side from the middle stream portion, mainly on the downstream side. It volatilization separated chlorination with heavy metals.
Also in the present invention, the reaction efficiency of chlorination of heavy metals can be improved by bringing the material to be treated into countercurrent contact with the chlorine-based gas. Further, in the present invention, by introducing the chlorine-containing substance from the middle part in the transfer direction of the object to be processed, the residence time required for volatilization treatment of the chlorinated heavy metals can be sufficiently taken, and the removal efficiency of heavy metals is improved. be able to.

Furthermore, the introduction position of the chlorine-containing substance is selected based on the component ratio of heavy metals contained in the object to be treated, and when the component ratio of low boiling point heavy metals is large, the introduction position is set to the middle stream side. When the component ratio of the high-boiling heavy metals is large, the introduction position is on the downstream side.
Thus, the reaction efficiency can be further improved by selecting the introduction position of the chlorine-containing substance according to the object to be treated. This is because, in the chlorination reaction of heavy metals, if the temperature is higher than the temperature range suitable for chlorination, the heavy metals may be oxidized by reacting with oxides such as silicon oxide contained in the gas. There is. Therefore, when a large amount of low-boiling heavy metals are contained, chlorination of the heavy metals is performed smoothly by chlorination on the upstream side of the midstream portion where the temperature is relatively low in the rotary kiln, and high-boiling oxides are generated. There is nothing to do.
On the other hand, when a large amount of high-boiling point heavy metals is contained, it is preferable to chlorinate on the downstream side of the midstream portion having a relatively high temperature. At this time, of course, the temperature setting in the rotary kiln may be varied according to the content ratio of heavy metals.

Furthermore, when the introduction position of the chlorine-containing substance is selected based on the moisture content of the object to be treated, and the moisture content is large, the introduction position is the downstream portion side, and the moisture content is small. Is characterized in that the introduction position is on the midstream side.
In the present invention, in the case of an object to be treated having a high water content, by setting the introduction position of the chlorine-containing substance on the downstream side, the object to be treated can be sufficiently dried, and the subsequent chlorination of heavy metals and Volatilization is performed smoothly. In addition, in the case of an object to be treated with a low water content, by setting the introduction position on the middle stream side, a sufficient residence time can be taken for the volatilization treatment reaction of chlorinated heavy metals. Removal efficiency can be improved.

In addition, in a detoxification method for a heavy metal-containing material that is heated in a heating furnace together with a chlorine-containing material as a reference example in a heating furnace, volatilizes the heavy metal, and then volatilizes and removes it,
The chlorine-containing substance is a chlorine-based exhaust gas containing a chlorine component volatilized from the object to be treated,
At least a part of the chlorine-based exhaust gas discharged from the heating furnace is returned to the heating furnace and circulated, and chlorination of heavy metals is performed by contact between the chlorine-based exhaust gas and the object to be treated.

Thus, the reference example can chlorinate heavy metals without increasing the amount of chlorine contained in the exhaust gas by circulating the chlorine-based exhaust gas containing the chlorine-containing substance, and is installed in the latter stage. The load of the desalination treatment in the exhaust gas treatment facility to be performed can be reduced. Moreover, corrosion by chlorine in the piping of exhaust gas treatment equipment and various devices can be suppressed.
In the present invention, when the chlorine content in the chlorinated exhaust gas is insufficient for chlorination, a chlorine-containing substance may be added from the outside.

In addition, as another reference example, a detoxification treatment of a heavy metal-containing material that is heated in a heating furnace together with a chlorine-containing material to remove a heavy metal-containing material that is chlorinated and then separated and removed. In the method
The heating furnace is a rotary kiln, and forms a countercurrent flow of a gas flow with respect to the workpiece transfer direction in the rotary kiln,
A gas flow turbulent flow region is formed on the upstream side in the transfer direction to mainly chlorinate the heavy metal, and a gas flow laminar region is formed on the downstream side to mainly perform the volatilization treatment of the heavy metal. And

According to this reference example , it is possible to adjust the contact efficiency between the chlorine-based exhaust gas and the object to be processed, and the contact efficiency is high in the upstream turbulent region, and chlorination is promoted. In the basin, the contact efficiency is low and the volatilization process is promoted. Therefore, the emission of non-volatile chloride substances can be reduced as in the prior art.

Moreover, in the said invention, the reheating furnace which reheats the said to-be-processed object discharged | emitted from the rotary kiln exit side is provided, The temperature range of the said reheating furnace is maintained in the temperature range of 800-1200 degreeC, and said heavy metals Volatilization treatment is performed.

  According to the present invention, in addition to a heating furnace that performs chlorination, a heating furnace that mainly performs volatilization treatment is provided, so that heavy metals chlorinated in the previous heating furnace remain without volatilization. Even in such a case, it can be completely volatilized by the heating furnace on the rear stage side, and it is possible to suppress heavy metal residues. Moreover, since the high-temperature to-be-processed object already heated and heated is supplied in the said heating furnace of the back | latter stage side, reduction of a thermal energy supply can be anticipated. Further, when the material to be processed is agitated and transferred to the subsequent heating furnace from the preceding heating furnace, unreacted substances existing inside are exposed on the surface, and the chlorination in the subsequent heating furnace is performed. Materialization and volatilization processing will be performed efficiently. In addition, it is good also as a structure which introduce | transduces a chloride containing substance into the said latter heating furnace, and it becomes possible to suppress the residue of heavy metals to the minimum by this.

Furthermore, it is preferable that the heating furnace located on the front stage side is a rotary kiln, and a turbulent flow region of gas flow is formed in the rotary kiln.
As a result, the contact efficiency between the chlorine-based exhaust gas containing the chlorine-containing substance and the object to be processed is improved, and the chlorination of heavy metals can be performed efficiently.

Further, as an invention of an apparatus for suitably carrying out these, a heating furnace having a supply means for an object to be processed containing heavy metals, a heating means for the object to be processed, and an inlet for a chlorine-containing substance, In the detoxification processing apparatus for the heavy metal-containing material that heats the object to be processed and the chlorine-containing material in a heating furnace, volatilizes the heavy metal and then volatilizes and separates and removes it,
A charging hopper for supplying the workpiece into the kiln by the heating furnace ; a cylindrical furnace body having means for transferring the workpiece from the charging hopper to the other end; and the charging hopper of the furnace body; A rotary kiln having an ash discharge port provided on the other end side and a burner portion provided on the ash discharge port side of the furnace body ,
The chlorine-containing substance is a chlorine-based exhaust gas containing a chlorine content volatilized from the object to be processed, and the chlorine-based exhaust gas inlet is provided in the middle or downstream part in the object transfer direction of the rotary kiln, The chlorinated exhaust gas containing the contained material is configured so as to form a counter-current flow with the transfer direction, and a chlorination region of the heavy metal is formed on the upstream side of the inlet, so that the inside of the rotary kiln on the downstream side or the rotary kiln The heavy metal volatilization treatment region is formed in a reheating furnace provided on the outlet side .

In the present invention, the chlorine-containing substance inlet is provided in the middle portion of the transfer direction, the chlorination region of the heavy metal is formed on the upstream side of the inlet, and the volatilization treatment region of the heavy metal is provided on the downstream side. that form shape.
Further, the position of the chlorine-containing substance introduction port is selected based on the component ratio of heavy metals contained in the object to be processed, and when the component ratio of the low boiling point heavy metals is large, the position of the introduction port is set to the middle stream. When the component ratio of the high boiling point heavy metals is large, it is preferable that the inlet position is the downstream part side, and the position of the chlorine-containing substance inlet is the position of the workpiece. It is selected based on the moisture content, and when the moisture content is large, the inlet position is the downstream portion side, and when the moisture content is small, the inlet position is the midstream portion side. good.

Furthermore, a branch flow rate adjusting valve for branching at least a part of the chlorine-based exhaust gas discharged from the rotary kiln , and an exhaust gas circulation line for circulating the branched chlorine-based exhaust gas back to the heating furnace are provided. And chlorination of heavy metals by contact with the object to be treated.
At this time, means for detecting the chlorine content of the workpiece before supply to the heating furnace, the heavy metal content of the processed material discharged from the heating furnace, or the chlorine content of the chlorine-based exhaust gas is provided, and the detection is performed. It is preferable to adjust the circulation amount of the chlorine-based exhaust gas by controlling the branch flow rate adjusting valve based on the obtained value.

Further, as a reference example, it comprises a heating furnace having means for supplying an object to be processed containing heavy metals, a means for heating the object to be processed, and an introduction port for a chlorine-containing substance, and the object to be processed in the heating furnace In a detoxification device for heavy metal-containing material, the product and the chlorine-containing material are heated, the heavy metal is chlorinated, and then volatilized and separated and removed.
The heating furnace is a rotary kiln, and the chlorine-containing substance introduction port is provided at any position from the midstream portion to the downstream portion in the workpiece transfer direction, and the exhaust gas outlet is provided on the workpiece supply means side for the transfer. Form a countercurrent flow of gas flow to the direction,
A turbulent flow region of gas flow is formed upstream of the rotary kiln in the transfer direction to mainly chlorinate heavy metals, and a laminar flow region of gas flow is formed downstream to mainly volatilize the heavy metals. It is characterized by that.

Further, the rotary kiln the discharged from the outlet side comprising a reheating furnace for re-heating an object, the volatilization treatment before Symbol heavy metals to maintain the temperature range of the reheating furnace to a temperature range of 800 to 1200 ° C. It is characterized by performing.
Furthermore, the heating furnace at the front stage is a rotary kiln, and a turbulent flow region of gas flow is formed in the rotary kiln.

  As described above, according to the present invention, the chlorine-based gas and the object to be treated are brought into countercurrent contact, and the heavy metal is chlorinated on the upstream side in the transfer direction of the object to be treated, and the chlorinated heavy metal on the downstream side. By volatilization treatment, metals such as oxides can be efficiently chlorinated, and the removal efficiency of heavy metals can be improved. In addition, the present invention employs a rotary kiln, and by utilizing the temperature gradient of the rotary kiln, it is possible to simultaneously perform a series of treatments of chlorination and volatilization treatment with a single device. Is not necessary, and the operation can be simplified.

Further, in the present invention, by introducing a chlorine-containing substance from the middle part in the transfer direction of the object to be treated, sufficient residence time required for the volatilization treatment of the chlorinated heavy metals on the upstream side can be taken, and the removal of heavy metals Efficiency can be improved.
Furthermore, the reaction efficiency can be further improved by selecting the introduction position of the chlorine-containing substance according to the object to be treated.
Also, by circulating the chlorine-based exhaust gas discharged from the heating furnace, chlorination of heavy metals can be achieved without increasing the amount of chlorine contained in the exhaust gas. The load of salt treatment can be reduced, and furthermore, corrosion of chlorine in exhaust gas treatment equipment piping and various devices can be suppressed.

Further, by forming a turbulent flow region of the gas flow on the upstream side of the workpiece transfer direction in the heating furnace and forming a laminar flow region of the gas flow on the downstream side, contact between the chlorine-based exhaust gas and the workpiece The efficiency can be adjusted, and the emission of non-volatile chloride substances can be reduced.
In addition to the heating furnace that performs chlorination, a heating furnace that mainly performs volatilization treatment is provided, so that heavy metals that have been chlorinated in the previous heating furnace remain without volatilization. However, it can be completely volatilized by a subsequent heating furnace, and the residual heavy metals can be suppressed.
Furthermore, by forming a turbulent flow region in the heating furnace located on the preceding stage side, the contact efficiency between the chlorine-based exhaust gas containing chlorine-containing substances and the object to be treated is improved, and the chlorination of heavy metals is efficiently performed. You can do well.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
FIG. 1 is an overall configuration diagram of an ash treatment system including a heavy metal containing substance processing apparatus according to the first embodiment, FIG. 2 is a configuration diagram of a heavy metal containing substance processing apparatus according to the second embodiment, and FIG. FIG. 4 is an overall configuration diagram of an ash treatment system equipped with a heavy metal containing substance processing apparatus according to the third embodiment. FIG. 4 is an overall configuration diagram of an ash treatment system equipped with a heavy metal containing substance processing apparatus according to the fourth embodiment. 5 and 6 are schematic views of a processing apparatus for heavy metal containing substances according to other Examples 5 and 6, respectively, and FIG. 8 is an apparatus configuration diagram showing a test apparatus simulating the processing apparatus of FIG.
This example is a technique for separating and removing heavy metals such as Pb, Zn, As, Cd, Cr, Se, Hg, Sb, Cu, etc., and examples of treated materials include contaminated soil, incinerated ash, fly ash, etc. In particular, in the present embodiment, the incineration ash detoxification process will be described as an example.

The ash treatment system shown in FIG. 1 is a system for detoxifying incineration ash and fly ash discharged from an incineration facility, and includes a pretreatment device 20 for pulverizing the incineration ash 30 and the like, and a pretreatment incineration. A rotary kiln 10 that heats an object to be processed in which fine ash such as ash 30 and fly ash is mixed, separates and removes heavy metals contained in the object to be processed, and an exhaust gas that processes exhaust gas discharged from the rotary kiln 10. And processing equipment.
The exhaust gas treatment facility combusts exhaust gas containing heavy metals discharged from the rotary kiln 10 by supplying auxiliary fuel 34, decomposes and removes dioxins and the like contained in the exhaust gas, and the re-combustion chamber 21. The high temperature exhaust gas discharged from the combustion chamber 21 and the combustion air 36 are heat-exchanged, the combustion air 36 is preheated and the high temperature exhaust gas is cooled, and the air preheater 22 is cooled. A gas cooling tower 25 that cools the exhaust gas to about 250 ° C. or less by cooling water spray or the like, a bag filter 26 that collects fly ash 37 in the cooled exhaust gas, and an exhaust gas discharged from the bag filter by the induction fan 27 And a chimney 28 for exhausting the air to the outside.

  The rotary kiln 10 includes a charging hopper 11 for supplying an object to be processed including the incinerated ash 30 into the kiln, and a cylindrical furnace body 12 having means for transferring the object to be processed from the charging hopper 11 to the other end side. The ash discharge port 15 provided on the other end side of the charging hopper 11 of the furnace body 12 and the burner portion 13 provided on the ash discharge port 15 side of the furnace body 12 are provided. . The workpiece introduced into the rotary kiln 10 is roasted by the flame generated by the supply of the air 33 and the auxiliary fuel 34 while the burner unit 13 is transferred to the ash discharge port 15. At this time, the rotary kiln 10 has a reducing atmosphere in an oxygen-deficient state or an oxygen-free state so that the object to be processed is not oxidized and burned.

In addition, as a characteristic configuration of the first embodiment, a chlorine-based gas introduction port 14 is provided in the vicinity of the ash discharge port 15 of the furnace body 12, and gas in the furnace body is discharged in the vicinity of the charging hopper 11. An exhaust gas exhaust port is provided. With such a configuration, a counter-current flow of a gas flow is formed in the furnace body opposite to the transfer direction of the workpiece.
Examples of the chlorine-based gas 32 introduced from the chlorine-based gas inlet 14 include chlorine-based gases such as chlorine gas and hydrogen chloride gas. In addition to the chlorine-based gases, chlorine-based solvents such as trichlorethylene and tetrachloroethylene, or solids A liquid or solid that generates a chlorine-based gas at a high temperature, such as a chlorine gas generating substance, can be used.

In the furnace main body 12, the air 33 and auxiliary fuel are set so that the charging hopper 11 side is less than 600 ° C. and the burner portion 13 side is below the melting point of the workpiece, for example, about 500 ° C. to 1200 ° C. 34 is controlled.
In the present embodiment, in the rotary kiln 10, an object to be processed containing heavy metals comes into countercurrent contact with the chlorine-based gas, and heavy metals are chlorinated on the upstream side of the rotary kiln 10 in the object transfer direction, and downstream. The chlorinated heavy metals are volatilized on the side, and the volatilized heavy metals are mixed in the gas and discharged from the exhaust gas outlet.

Thus, by bringing the chlorine-based gas into contact with the object to be processed in a countercurrent flow, heavy metals can be efficiently chlorinated, and the removal efficiency of heavy metals can be improved. Further, in the present embodiment, since the chlorination treatment is performed using the rotary kiln 10, a series of treatments of chlorination and volatile treatment can be performed simultaneously with one apparatus, and the conventional complicated temperature control can be performed. It becomes unnecessary and simplifies the operation.
The exhausted heavy metals contained in the exhaust gas are introduced into the gas cooling tower 25 through the recombustion chamber 21 and the air preheater 22, and are cooled to the melting point of the heavy metals or less by the gas cooling tower 25. The deposited heavy metals are collected and reused or discarded. The ash detoxified in the furnace body 12 is cooled by the ash cooling device 16 and discharged as roasted ash 35.

As another form of the present embodiment, the position of the chlorine-based gas inlet 14 may be selected based on the component ratio of heavy metals contained in the object to be processed. At this time, when the component ratio of the low-boiling point heavy metals in the object to be processed is large, the chlorine gas inlet 14 is set to the midstream part side in the transfer direction of the object to be processed, and the component ratio of the high boiling point heavy metals is large. If it is, it will be the downstream side. This is because, in the chlorination reaction of heavy metals, if the temperature is higher than the temperature range suitable for chlorination, the heavy metals may be oxidized by reacting with oxides such as silicon oxide contained in the gas. Therefore, when a large amount of low-boiling point heavy metals is contained, chlorination of heavy metals is performed smoothly by chlorination on the upstream side of the middle stream portion in the rotary kiln 10 where the temperature is relatively low. There is no production.
On the other hand, when a large amount of high-boiling heavy metals is contained, it is preferable to chlorinate on the downstream side where the temperature is relatively high.

As another embodiment, the position of the chlorine gas inlet may be selected based on the moisture content of the object to be processed. At this time, when the moisture content is large, the chlorine-based gas inlet 14 is on the downstream side, and when the moisture content is small, the chlorine-based gas inlet 14 is on the middle stream side. This is because, in the case of a high water content to-be-treated material, the material to be treated can be sufficiently dried by setting the chlorine-based gas inlet to the downstream side, and then the chlorination and volatilization treatment of heavy metals is performed. In the case of an object to be treated having a low water content, by setting the chlorine-based gas inlet 14 on the middle stream side, a sufficient time for the volatilization reaction of chlorinated heavy metals is achieved. And the removal efficiency of heavy metals can be improved.
Thus, the reaction efficiency can be further improved by selecting the introduction position of the chlorine-containing substance according to the object to be treated.

  FIG. 2 shows an apparatus for detoxifying a heavy metal-containing material according to the second embodiment. As shown in FIG. 2, the apparatus includes a rotary kiln 10 that heats an object to be processed containing heavy metals and separates and removes heavy metals contained in the object to be processed. The rotary kiln 10 includes the object to be processed. A charging hopper 11 for supplying the material into the rotary kiln, a cylindrical furnace body 12 having means for transferring the workpiece from the charging hopper 11 to the other end, and the charging hopper 11 and the other end of the furnace body 12 The ash discharge port 15 provided in the ash discharge port 15 and the burner portion 13 provided on the ash discharge port 15 side of the furnace body 12 are provided. The workpiece introduced into the rotary kiln 10 is roasted by the flame generated by the supply of the air 33 and the auxiliary fuel 34 while the burner unit 13 is transferred to the ash discharge port 15. At this time, the rotary kiln 10 has a reducing atmosphere in an oxygen-deficient state or an oxygen-free state so that the object to be processed is not oxidized and burned.

In the second embodiment, a chlorine-based gas inlet 14 is provided in the middle portion of the furnace body 12 in the workpiece transfer direction, and an exhaust gas outlet for discharging the gas in the furnace body in the vicinity of the charging hopper 11. The counter flow of the gas flow opposite to the transfer direction of the workpiece is formed in the furnace body.
In the furnace body 12, a chlorination region 10A for chlorinating heavy metals in the presence of chlorinated gas on the upstream side of the chlorinated gas introduction port 14 and a volatilization treatment for volatilizing chlorinated heavy metals on the downstream side. Region 10B is formed.
According to the second embodiment, the reaction efficiency of chlorination of heavy metals can be improved by bringing the object to be treated into countercurrent contact with the chlorine-based gas 32 as in the first embodiment. Further, in this embodiment, the chlorine-based gas inlet 14 is provided in the middle portion in the transfer direction of the object to be processed, so that the space of the volatilization processing region 10B can be taken sufficiently and the removal efficiency of heavy metals can be improved. it can.

FIG. 3 shows an ash treatment system equipped with a heavy metal-containing material treatment apparatus according to the third embodiment. In the third embodiment, detailed description of the same configuration as that of the first embodiment is omitted.
The ash treatment system according to the third embodiment includes a pretreatment device 20, a rotary kiln 10, and an ash cooling device 16, and further includes an exhaust gas treatment facility that treats exhaust gas discharged from the rotary kiln 10.
Similar to the first embodiment, the exhaust gas treatment facility includes a recombustion chamber 21, an air preheater 22, a gas cooling tower 25, a bag filter 26, and a chimney 28.

The rotary kiln 10 includes a charging hopper 11 for supplying the incineration ash 30 into the kiln, a cylindrical furnace body 12 having means for transferring the incineration ash 30 from the charging hopper 11 to the other end, and the furnace body 12. The hopper 11 and the ash discharge port 15 provided on the other end side, and the burner portion 13 provided on the ash discharge port 15 side of the furnace body 12 are provided.
Further, an exhaust gas outlet is provided on the charging hopper 11 side of the incinerated ash 30 and a chlorine-based exhaust gas inlet 14 ′ is provided on the ash discharge port 15 side, and at least a part of the chlorine-based exhaust gas discharged from the exhaust gas outlet is disposed. It introduce | transduces into the said chlorine-type waste gas inlet 14 '. In the rotary kiln 10, the chlorinated exhaust gas forms a countercurrent flow with respect to the transfer direction of the incineration ash 30.

In the rotary kiln 10, the incinerated ash 30 containing heavy metals comes into countercurrent contact with the chlorinated gas, and heavy metals are chlorinated on the upstream side with respect to the incineration ash transfer direction of the rotary kiln 10, and the chlorination is on the downstream side. The materialized heavy metals are volatilized, and the volatilized heavy metals are mixed in the gas and discharged from the exhaust gas outlet.
In the exhaust gas discharged from the rotary kiln 10, the chlorine content originally contained in the incineration ash 30 is volatilized and contained. The chlorine-based exhaust gas is supplied to an exhaust gas treatment facility at a subsequent stage through an exhaust gas supply line 40. A branch flow rate control valve 42 for the exhaust gas is provided on the exhaust gas supply line 40, and the branch flow rate control valve is provided. 42, an exhaust gas branching and circulating line 41 is provided at the chlorine-based exhaust gas inlet 14 ′ from the inlet 42 ′, and at least a part of the chlorine-containing gas discharged from the rotary kiln 10 is branched by adjusting the opening of the branch flow rate control valve 42. It is introduced into the kiln via the branch circulation line 41.

The exhaust gas circulation flow rate is controlled by, for example, the content of the chlorine component in the incineration ash 30, the content of the chlorine component in the exhaust gas fed to the exhaust gas treatment facility, or roasting discharged from the rotary kiln 10. It is preferable to detect at least one of the heavy metal contents of the ash 35 and control the branch flow rate control valve 42 based on the detected value to determine the exhaust gas circulation flow rate. At this time, when the chlorine component required for chlorination of heavy metals cannot be supplied only by circulation of the chlorine-based exhaust gas, it is preferable to supply the chlorine-based gas 32 from the outside.
In the third embodiment, in addition to the illustrated rotary kiln 10, any apparatus can be used as long as it can heat the incinerated ash, such as a fluidized furnace and an electric furnace, but a rotary kiln is particularly used. It is preferable that the rotary kiln forms a temperature gradient in the furnace, so that continuous chlorination and volatilization treatment can be performed by a single apparatus.

  As in Example 3, chlorinated exhaust gas is circulated in the kiln, so that chlorination can be achieved without adding a chlorine-containing substance from the outside. Desalination treatment of exhaust gas at an exhaust gas treatment facility installed in the subsequent stage Can reduce the load. Further, since the chlorine content contained in the exhaust gas is reduced, the influence of corrosion of piping and other equipment can be reduced.

FIG. 4 shows an ash treatment system equipped with a heavy metal-containing material treatment apparatus according to the fourth embodiment.
The ash treatment system according to the fourth embodiment includes a pretreatment device 20, a rotary kiln 10, a reheating furnace 17, and an ash cooling device 16, and is further discharged from the heating furnace 10 and the reheating furnace 17. It consists of exhaust gas treatment equipment that treats exhaust gas.
Similar to the first embodiment, the exhaust gas treatment facility includes a recombustion chamber 21, an air preheater 22, a gas cooling tower 25, a bag filter 26, and a chimney 28.

  The rotary kiln 10 has a charging hopper 11, a furnace main body 12, an ash discharge port 15, a burner unit 13, an exhaust gas outlet and a chlorine-based exhaust gas inlet port 14 as in the third embodiment. It is comprised so that the said chlorine-type exhaust gas may form a countercurrent flow with respect to the incineration ash 30 inside. Further, an exhaust gas branch flow rate control valve 42 is provided on the exhaust gas supply line 40 of the chlorine-based exhaust gas discharged from the rotary kiln 10, and the exhaust gas branch circulation from the branch flow rate control valve 42 to the chlorine-based exhaust gas inlet 14 ′. A line 41 is provided to circulate the chlorinated exhaust gas.

Furthermore, a reheating furnace 17 for introducing and reheating roasted ash discharged from the rotary kiln 10 is provided. Examples of the reheating furnace 17 include a rotary kiln, a fluidized furnace, and an electric furnace. A plurality of reheating furnaces 17 may be installed.
In the fourth embodiment, the rotary kiln 10 is configured such that the temperature on the inlet side of the incineration ash 30 is about 500 ° C. and the temperature on the outlet side is about 1200 ° C. On the other hand, the reheating furnace 17 sets the temperature on the inlet side of the workpiece to about 800 ° C. and the temperature on the outlet side to about 1200 ° C.
The rotary kiln 10 mainly chlorinates heavy metals contained in the workpiece, and the reheating furnace 17 mainly volatilizes heavy metals contained in the workpiece.

As another configuration, the chlorine-based exhaust gas or the chlorine-containing substance 32 discharged from the rotary kiln 10 may be introduced into the reheating furnace 17. It is preferable that the chlorine-based gas or the chlorine-containing substance 32 is introduced from the ash discharge port side of the reheating furnace 17 and forms a countercurrent flow with respect to the transfer direction of the workpiece.
Further, the exhaust gas discharged from the reheating furnace 17 is introduced into the exhaust gas treatment facility through the exhaust gas introduction line 43, and the opening degree of the branch flow rate control valve 44 provided on the exhaust gas introduction line 43 is adjusted, thereby It is preferable that at least a part of the exhaust gas is returned to the rotary kiln 10 or the reheating furnace 17 and circulated.

According to the fourth embodiment, the reheating furnace 17 is provided in the subsequent stage of the rotary kiln 10, so that even if heavy metals chlorinated in the rotary kiln 10 remain without volatilization, the heating furnace 17 can be volatilized completely, and the residual heavy metals can be minimized. In the reheating furnace 17, since high-temperature incinerated ash that has already been heated and heated is supplied, a reduction in the supply of thermal energy can be expected. Furthermore, when transferred from the rotary kiln 10 to the reheating furnace 17, the incinerated ash is agitated and unreacted substances existing inside are exposed on the surface, and the chlorination and volatilization treatment in the reheating furnace 17 is efficient. It will be done well.
Further, the techniques described in the third and fourth embodiments can be used in combination with the first and second embodiments described above.

FIG. 5 shows a schematic view of a heavy metal containing substance processing apparatus according to the fifth embodiment.
The apparatus according to the fifth embodiment includes a charging hopper (not shown) for supplying the incinerated ash 30, a cylindrical furnace body 12 having means for transferring the incinerated ash 30 from the charging hopper to the other end, and the furnace The rotary kiln 10 includes the charging hopper of the main body 12 and an ash discharge port (not shown) provided on the other end side, and a burner portion 13 provided on the ash discharge port 15 side of the furnace main body 12.
Further, in the fifth embodiment, an exhaust gas outlet is provided on the charging hopper 11 side of the incinerated ash 30 and a chlorine-based exhaust gas introduction port 14 ′ is provided on the ash discharge port 15 side, and the chlorine-based exhaust discharged from the exhaust gas outlet is provided. At least a part of the exhaust gas is introduced into the chlorine-based exhaust gas inlet 14 '. Then, the chlorine-based exhaust gas forms a countercurrent flow with respect to the incineration ash 30 in the rotary kiln 10. In addition, it is good also as a structure which introduce | transduces a chlorine containing substance instead of the said chlorine-type exhaust gas.

Further, the flow behavior in the rotary kiln 10 is such that the upstream side becomes a turbulent flow region and the downstream side becomes a laminar flow region with respect to the transfer direction of the incineration ash 30. Preferably, the kiln inner diameter is set so that the upstream turbulent flow region has a high Reynolds number and the downstream laminar flow region has a low Reynolds number. At this time, it is preferable to set the kiln inner diameter so that the Reynolds number (gas flow velocity × furnace inner diameter ÷ gas kinematic viscosity coefficient) is 4000 or more on the upstream side and 2100 or less on the downstream side.
As an example, FIG. 7 shows the relationship between the temperature and kiln inner diameter at a gas flow of 800 Nm ³ / h, and the Reynolds number. The lower region of the curve showing the Reynolds number (Re) 4000 is a turbulent flow region, the upper region of the curve showing the Reynolds number (Re) 2100 is a laminar flow region, and the critical region is in between. The chloride region is formed in the turbulent flow region including the boundary layer and is in the temperature range of 500 to 900 ° C., and thus is within the region illustrated, and the kiln inner diameter on the upstream side of the rotary kiln 10 is included in this region. Set to value. On the other hand, the volatilization treatment region is formed in a laminar flow region including a boundary layer and is a temperature region of 900 to 1200 ° C., and thus is within the region illustrated, and the kiln inner diameter on the downstream side of the rotary kiln 10 is within this region. Set to included value.

As in the fifth embodiment, by forming a laminar flow region and a turbulent flow region in the gas flow in the rotary kiln 10, it becomes possible to adjust the contact efficiency of the chlorinated exhaust gas, and a chlorination region (turbulent flow region), a volatilization treatment region (Laminar basin) can be divided. Thereby, chlorinated heavy metals can be volatilized efficiently, and it becomes possible to reduce discharge | emission of the non-volatilized chlorinated substance compared with the past.
The apparatus described in Example 5 can be suitably applied to Examples 1 to 3 in which heavy metals in incineration ash are chlorinated and volatilized by a single heating device.

FIG. 6 shows a schematic view of a heavy metal containing substance processing apparatus according to the sixth embodiment.
The apparatus according to the sixth embodiment includes a charging hopper (not shown) for supplying the incineration ash 30, a cylindrical furnace body 12 having means for transferring the incineration ash 30 from the charging hopper to the other end, and the furnace The rotary kiln 10 includes the charging hopper of the main body 12 and an ash discharge port (not shown) provided on the other end side, and a burner portion 13 provided on the ash discharge port 15 side of the furnace main body 12.
In the sixth embodiment, an exhaust gas outlet is provided on the charging hopper 11 side of the incinerated ash 30 and a chlorine-based exhaust gas inlet 14 ′ is provided on the ash discharge port 15 side, so that the chlorine-based exhaust gas discharged from the exhaust gas outlet is provided. At least a part of the exhaust gas is introduced into the chlorine-based exhaust gas inlet 14 '. In the rotary kiln 10, the chlorine-based exhaust gas forms a countercurrent flow with respect to the transfer direction of the incineration ash 30.

Furthermore, the flow behavior in the rotary kiln 10 is set to be a turbulent region. This is set so that the Reynolds number in the furnace space increases, and the kiln inner diameter is preferably set so as to be 4000 or more.
Thus, by making the gas flow of the rotary kiln 10 a turbulent flow region, the contact efficiency between the chlorinated exhaust gas and the incineration ash 30 is improved, and the chlorination of heavy metals contained in the incineration ash 30 is promoted. Is.

Next, the result of having performed the test which detoxifies Pb containing incineration ash using the test apparatus which simulated the apparatus structure of above-mentioned Example 1 is shown.
As shown in FIG. 8, a tubular electric furnace 50 is used in the test apparatus, incinerated ash 56 is filled in the tubular electric furnace 50 that is made a reducing atmosphere with N ₂ gas 53, and the chlorine addition liquid 51 is pumped 52. Was heated to about 1050 ° C. while being introduced into the tubular electric furnace 50, and the Pb concentration contained in the incinerated ash 56 was measured. At this time, the temperature in the tubular electric furnace 50 is measured by the thermocouple 55. The exhaust gas generated here is passed through an HCl gas absorption bottle 57 to recover HCl.
The test results of the detoxification process using such a test apparatus are shown in FIG.

FIG. 9 shows test results based on the bottom sediment investigation method. (A) is a graph showing the Pb content before and after the heat treatment, and (b) is a graph showing the Pb content with respect to the added HCl concentration. According to this, the Pb content of the incinerated ash before heat treatment is 778 mg / kg, whereas in Run 1 without introducing chlorine gas, the Pb content is reduced to 483 mg / kg, and Run 3 with 600 ppm of HCl added Pb content was reduced to 398 mg / kg, and Run4 to which 2150 ppm of trichlorethylene was added decreased to 397 mg / kg. In Run 2 to which 1200 ppm of HCl was added, the Pb content was greatly reduced to 252 mg / kg.
From these test results, it can be seen that the Pb content is significantly reduced when the chlorine-based gas is supplied compared to the case where the chlorine-based gas is not supplied. It can also be seen that the Pb removal rate improves as the HCl supply amount increases. Furthermore, it was found that the Pb content decreases in proportion to the molar concentration of added HCl.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the ash processing system which comprised the processing apparatus of the heavy metal containing material which concerns on this Example 1. FIG. It is a block diagram of the processing apparatus of the heavy metal containing substance which concerns on the present Example 2. FIG. It is a whole block diagram of the ash processing system which comprised the processing apparatus of the heavy metal containing substance which concerns on this Example 3. FIG. It is a whole block diagram of the ash processing system which comprised the processing apparatus of the heavy metal containing substance which concerns on the present Example 4. FIG. It is the schematic of the processing apparatus of the heavy metal containing substance which concerns on this Example 5. FIG. It is the schematic of the processing apparatus of the heavy metal containing substance which concerns on this Example 6. FIG. It is a graph which shows the relationship between a kiln internal diameter and temperature, and Reynolds number. It is an apparatus block diagram which shows the test apparatus which simulated the processing apparatus of FIG. FIG. 9 is a detoxification treatment test result by the test apparatus of FIG. 8, (a) is a graph showing the Pb content before and after the heat treatment, and (b) is a graph showing the Pb content with respect to the added HCl concentration. It is a block diagram which shows the processing apparatus of the conventional heavy metal containing substance.

DESCRIPTION OF SYMBOLS 10 Rotary kiln 11 Input hopper 12 Furnace main body 14 Chlorine gas introduction port 15 Discharge port 16 Ash cooling device 17 Reheating furnace 20 Pretreatment device 30 Incineration ash 31 Processed object 32 Chlorine gas 35 Roast ash 36 Combustion air 40 Exhaust gas Supply line 41 Exhaust gas branch circulation line 42 Branch flow control valve 43 Exhaust gas introduction line 44 Branch flow control valve

Claims (11)

In the detoxification method of the heavy metal-containing material, the object to be treated containing heavy metals is heated together with the chlorine-containing material in a heating furnace, and the heavy metal is chlorinated and then separated and removed.
A charging hopper for supplying the workpiece into the kiln by the heating furnace ; a cylindrical furnace body having means for transferring the workpiece from the charging hopper to the other end; and the charging hopper of the furnace body; A rotary kiln having an ash discharge port provided on the other end side and a burner portion provided on the ash discharge port side of the furnace body ,
The chlorine-containing substance is a chlorine-based exhaust gas containing a chlorine content volatilized from the object to be processed, and the chlorine-based exhaust gas is provided from a gas inlet provided in the middle or downstream part in the object transfer direction of the rotary kiln. introducing city, exhaust gas was subjected to chlorination prior Symbol heavy metals in the object to be processed feeding direction upstream of and discharged from the discharge port formed in a kiln in an upstream portion the gas inlet,
A detoxification method for a heavy metal-containing material , wherein the heavy metal is volatilized in a reheating furnace provided in the rotary kiln downstream of the gas inlet or on the outlet side of the rotary kiln .   The introduction position of the chlorine-containing material is selected based on the component ratio of the heavy metals contained in the object to be treated, and when the component ratio of the low boiling point heavy metals is large, the introduction position is set to the middle stream side, 2. The method for detoxifying a heavy metal-containing material according to claim 1, wherein, when the component ratio of the high-boiling heavy metals is large, the introduction position is located on the downstream side.   The introduction position of the chlorine-containing substance is selected based on the moisture content of the object to be treated. When the moisture content is large, the introduction position is the downstream portion side, and when the moisture content is small, the introduction position is selected. 2. The method for detoxifying a heavy metal-containing material according to claim 1, wherein the position is on the middle stream side. A reheating furnace for reheating the workpiece discharged from the rotary kiln outlet side is provided, and the temperature range of the reheating furnace is maintained at a temperature range of 800 to 1200 ° C. to volatilize the heavy metals. 2. The method for detoxifying a heavy metal-containing material according to claim 1, wherein: It comprises a heating furnace having means for supplying an object to be processed containing heavy metals, a heating means for the object to be processed, and an inlet for a chlorine-containing substance, and the object to be processed and the chlorine-containing substance are contained in the heating furnace. In a detoxification processing apparatus for heavy metal-containing substances that heats the substance, volatilizes the heavy metal and then volatilizes it to separate and remove it,
A charging hopper for supplying the workpiece into the kiln by the heating furnace ; a cylindrical furnace body having means for transferring the workpiece from the charging hopper to the other end; and the charging hopper of the furnace body; A rotary kiln having an ash discharge port provided on the other end side and a burner portion provided on the ash discharge port side of the furnace body ,
The chlorine-containing substance is a chlorine-based exhaust gas containing a chlorine content volatilized from the object to be processed, and the chlorine-based exhaust gas inlet is provided in the middle or downstream part in the object transfer direction of the rotary kiln, The chlorinated exhaust gas containing the contained material is configured so as to form a counter-current flow with the transfer direction, and a chlorination region of the heavy metal is formed on the upstream side of the inlet, so that the inside of the rotary kiln on the downstream side or the rotary kiln An apparatus for detoxifying a heavy metal-containing substance, wherein a volatilization processing region for the heavy metal is formed in a reheating furnace provided on an outlet side . The position of the chlorine-containing substance introduction port is selected based on the component ratio of heavy metals contained in the object to be treated, and when the component ratio of low boiling point heavy metals is large, the introduction port position is set to the middle stream side 6. The detoxification apparatus for heavy metal-containing substances according to claim 5, wherein when the component ratio of the high boiling point heavy metals is large, the inlet position is on the downstream side. When the position of the chlorine-containing substance inlet is selected based on the moisture content of the object to be treated, when the moisture content is large, the inlet position is the downstream portion side, and when the moisture content is small 6. The heavy metal-containing substance detoxifying apparatus according to claim 5, wherein the introduction port position is on the midstream side. A branch flow rate adjusting valve for branching at least a part of the chlorine-based exhaust gas discharged from the rotary kiln , and an exhaust gas circulation line for returning the branched chlorine-based exhaust gas to the heating furnace are provided. 6. The apparatus for detoxifying a heavy metal-containing material according to claim 5, wherein the heavy metal is chlorinated by contact with the treated material. A means for detecting the chlorine content of the object to be processed before being supplied to the heating furnace, the heavy metal content of the processed material discharged from the heating furnace, or the chlorine content of the chlorine-based exhaust gas is provided, and the detected value is set to the detected value. 6. The apparatus for detoxifying a heavy metal-containing material according to claim 5, wherein the branch flow rate adjusting valve is controlled to adjust the circulation amount of the chlorine-based exhaust gas. The rotary kiln said discharged from the outlet side comprising a reheating furnace for re-heating an object, it performs a volatilization treatment before Symbol heavy metals to maintain the temperature range of the reheating furnace to a temperature range of 800 to 1200 ° C. An apparatus for detoxifying a heavy metal-containing material according to claim 5 . The heavy metal-containing material detoxifying apparatus according to claim 10 , wherein the heating furnace on the front stage is a rotary kiln and forms a turbulent flow region of gas flow in the rotary kiln.

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