JP5105993B2 - Detoxification treatment apparatus and method for treated ash - Google Patents

Description

  The present invention is a technology for detoxifying harmful substances contained in treated ash such as contaminated soil, incinerated ash, fly ash, etc., and in particular, chlorinated heavy metals in the treated ash and then volatilized by heating to be harmless. The present invention relates to a detoxification process method and apparatus for treated ash.

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, environmental regulations for heavy metals contained in incineration ash, fly ash, soil, etc. have been established, and regulations on heavy metals have become stricter. It can no longer be reused as roadbed material.
In particular, with regard to heavy metals in molten slag, which is a resource product derived from incineration ash, in addition to the conventional elution standards, the content standards have been newly set by local governments, so heavy metals are also used for effective use of molten slag. There is a need for a method of detoxifying a substance containing nitrogen. Various methods for volatilizing and separating the contained heavy metals by chlorination have been proposed for this problem.

As one method for detoxifying substances containing such heavy metals, Patent Document 1 (Japanese Patent Laid-Open No. 2003-290758) discloses an invention for purifying soil contaminated with lead or a lead compound. Yes. According to Patent Document 1, a chlorine compound is added to contaminated soil, and this is heat-treated and volatilized as chloride. The heat processing temperature at this time is 950-1800 degreeC.
Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-181323) proposes an invention in which heavy metals contained in incineration ash are volatilized as chlorides. According to Patent Document 2, combustion exhaust gas containing hydrogen chloride derived from a waste incinerator is introduced into an ash treatment, and heavy metals contained in the incineration ash in the ash treatment furnace are volatilized as chloride. It has been proposed to heat the incinerated ash in the ash treatment furnace at this time to 700 ° C. or higher.

Further, Patent Document 3 (Japanese Patent Application Laid-Open No. 2005-288433) proposes an invention in which an object to be processed containing heavy metals is heated together with a chlorine-containing substance in a heating furnace, and the heavy metals are chlorinated and volatilized. Yes.
According to Patent Document 3, a chlorine-containing substance is introduced from any position downstream from the midstream portion of the heating furnace in the workpiece transfer direction, and exhaust gas is discharged from the upstream portion to form a countercurrent flow of gas flow. In addition, the object to be treated containing heavy metals is brought into counter-current contact with a chlorine-based exhaust gas containing a chlorine content from a chlorine-containing substance to perform chlorination. Oxide is efficiently obtained by counter-contacting the chlorine-based exhaust gas and the object to be treated, converting the heavy metal into chloride on the upstream side in the transfer direction of the object to be treated, and volatilizing the chlorided heavy metal on the downstream side. Such as metals can be converted into chloride, and the removal efficiency of heavy metals can be improved. At this time, the heating furnace located on the downstream side maintains a temperature range of 800 to 1200 ° C. Furthermore, by adopting a rotary kiln as the heating furnace and utilizing the temperature gradient of the rotary kiln, a series of treatments of chlorination and volatilization treatment can be simultaneously performed with one apparatus.

Examples of the chlorine-containing substance in Patent Document 3 include gases such as chlorine gas and hydrogen chloride gas, chlorine-based solvents such as trichloroethylene and tetrachloroethylene, and solid chlorine gas generating substances. The chlorine-containing substance is a chlorine-based exhaust gas containing a chlorine component volatilized from the object to be treated, and at least a part of the chlorine-based exhaust gas discharged from the heating furnace is returned to the heating furnace and circulated.
As described above, there has been proposed an invention in which a chlorine-containing substance is added to contaminated soil containing heavy metals, incinerated ash, fly ash, etc., and the heavy metals are chlorinated and then removed by heating and stripping.

Furthermore, Patent Document 4 (Japanese Patent Application Laid-Open No. 11-193911) proposes an invention by waste treatment by heat, more specifically by reprocessing slag and ash from heat treatment of waste.
According to Patent Document 4, as a first step, waste is pyrolyzed / gasified or partially burned, and at that time, heavy metal-containing slag and ash having a relatively high carbon content are generated. Next, as a second step, the above-described slag and ash are heated by an oil burner disposed in front of the rotary kiln in the rotary kiln. The heavy metals contained in the slag and ash are converted into a metal form by reduction of the slag with the carbon content of the slag, and the easily evaporable heavy metals are transferred to the gas phase and discharged from the rotary kiln together with the flue gas. The carbon content in the slag and ash at this time is included for the purpose of reduction.

JP 2003-290758 A JP 2004-181323 A JP 2005-288433 A Japanese Patent Laid-Open No. 11-193911

However, in the invention disclosed in Patent Document 1, the heat treatment temperature is 950 to 1800 ° C., which is considered to be a temperature sufficient to volatilize lead or chlorides of lead compounds, but it is increased to 1200 ° C. or higher. As a result, there is a problem that clinker is generated.
In the invention disclosed in Patent Document 2, the incineration ash in the ash treatment furnace is set to 700 ° C. or more, more preferably 950 ° C. or more, and the temperature in the ash treatment furnace is set to 1000 ° C. or more and 1200 ° C. in order to prevent melting of the incineration ash. Although the following has been proposed, specific conditions for preventing melting of incineration ash incineration ash are not disclosed.
In the invention disclosed in Patent Document 3, the heavy metal contained in the object to be treated and the chlorine-based gas are sufficiently in contact with each other to efficiently chlorinate the heavy metal, and maintain the high removal efficiency of the heavy metal after the treatment. Although the residual of heavy metals can be minimized, as in Patent Document 2, the temperature range in which the melting of the object to be processed is prevented and the heavy metals contained in the object to be processed are chlorinated and volatilized. Is only disclosed.
In the invention disclosed in Patent Document 4, the burner is disposed in front of the rotary kiln, and the temperature at the rotary kiln inlet is the highest and gradually decreases toward the outlet. Therefore, when using solids such as incinerated ash that requires minutes per minute to raise the temperature, it is possible that the ash will move before it rises sufficiently (away from the entrance), and a temperature layer in which heavy metals do not volatilize. May be generated. Further, even if the burner output is increased in order to raise the ash temperature, there is a risk that the ash will melt because the temperature rises too much, and it is difficult to control the ash temperature when the burner is placed in front of the rotary kiln.
In order to detoxify and recycle heavy metals contained in treated ash such as contaminated soil, incinerated ash and fly ash, it is necessary to satisfy the elution standard for heavy metals and the content standard. For this reason, in the method of chlorinating and separating the heavy metals contained in the incinerated ash, it is important to surely volatilize the chlorinated heavy metals, and the conditions are required. It must also be taken into account to prevent clinker generation and incineration ash melting due to excessive heating.

  Therefore, in view of the above-described problems of the prior art, the present invention provides a detoxification treatment apparatus for treated ash that can suppress melting of treated ash and can efficiently volatilize and separate heavy metals contained in the treated ash, and It aims to provide a method.

Therefore, in order to solve such problems, the present invention adds a chlorine-containing substance to the treated ash containing heavy metals, converts the heavy metals into chloride in a roasting furnace, and heats and volatilizes them to separate and remove them. In detoxification processing equipment for treated ash,
As the roasting furnace, using a rotary kiln with a refractory material lined, provided with a supply port for treated ash at one end, and a combustion burner and a discharge port for discharging roasted ash at the other end,
Mixing means for mixing the treated ash and carbide before supplying the treated ash into the rotary kiln, the peripheral speed of the rotary kiln and the input air are controlled , and the carbide is added to raise the temperature from the treated ash layer. And a roasting furnace control means for generating a state that does not float on the surface of the ash to be treated, wherein the heavy metal is separated and removed by heating to 950 to 1200 ° C. in the exit area of the rotary kiln.

According to the present invention, the carbide mixed in the ash to be treated exists in a state where it does not float on the surface of the ash to be treated. Therefore, the internal temperature of the ash layer is reduced by the thermal energy generated when the carbide burns. To rise. By raising the temperature inside the ash layer, which tends to be lower than the surface layer, the ash layer temperature in the rotary kiln is uniformly 950 to 1200 ° C., so that chlorinated heavy metals are volatilized without remaining in the treated ash. The removal rate of heavy metals (Pb) increases.
Also, by using a rotary kiln equipped with a combustion burner on the other end side (rotary kiln rear side) of the treated ash supply port, the treated ash and combustion gas become countercurrent, and the temperature distribution is lowest on the rotary kiln supply port side, The exit side behind the rotary kiln is the highest. Therefore, since the ash to be treated is gradually heated from the supply to the rotary kiln until reaching the outlet, the risk of melting is low and the amount of heat is not wasted.

Furthermore, by mixing carbide with the ash to be treated, the ash layer temperature rises slowly without exceeding the melting temperature of the ash to be treated in the rotary kiln, so that the chlorinated heavy metal is suppressed while suppressing the melting of the ash to be treated. The optimal temperature range of 950 to 1200 ° C. from which the compound (PbCl ₂ ) evaporates can be kept longer.
Moreover, by having a heating source in the to-be-processed ash in a rotary kiln, the fuel amount of a combustion burner required at the time of roasting can be reduced, and the fuel consumption of a roasting furnace improves. Furthermore, carbides have a reducing action on heavy metals contained in the ash to be treated in the rotary kiln, and particularly suppress the generation of harmful hexavalent chromium and promote the volatilization of chlorinated heavy metals. it can.

Moreover, the said exit area | region is a state by which the to-be-processed ash in a rotary kiln is maintained for 5 to 15 minutes at ash layer temperature 950-1200 degreeC, and is maintained for 5 to 15 minutes at ash layer temperature of this exit area | region 950-1200 degreeC. condition being, characterized in that the generated controlled by selection of the amount of the carbide to by that the treated ash to the mixing means. In this way, it is possible to sufficiently volatilize chlorinated heavy metals (PbCl ₂ ) even in solid ash that requires time for temperature rise. Moreover, by maintaining the ash layer temperature of 950 to 1200 ° C. for 5 to 15 minutes, volatilization from the inside of the treated ash which is not easily volatilized is sufficiently performed, and the residual of heavy metals contained in the treated ash is minimized. Can be suppressed.

Moreover, in this invention, the addition amount of the carbide | carbonized_material is selected based on the amount of unburned content contained in the said to-be-processed ash in the said mixing means, The carbide | carbonized_material in the to-be-processed ash in the said rotary kiln is ash layer temperature 700-800 degreeC. The ash to be treated and carbide are mixed so that a state of 3 to 7% by weight is generated.
Thus, in this invention, the carbide | carbonized_material which exists 3-7 weight % at ash layer temperature 700-800 degreeC contributes as a heat source which raises ash layer internal temperature. Carbides is preferably 3 to 7 wt%, 3 wt% not increase value, if the ash layer temperature is sufficiently less, if the excessive portion of the surface is likely to melt. When the ash layer temperature is 700 to 800 ° C. and 3 to 7 wt % of carbide is present, the above-described exit region (maintained at an ash layer temperature of 950 to 1200 ° C. for 5 to 15 minutes) is achieved.
Here, the carbide may be added from the outside so that 3 to 7% by weight is present in the state described above, or the untreated ash that has been adjusted in advance to leave 3% by weight or more of unburned matter by a dryer. The fuel may be used as a carbide.

  Further, the roasting furnace is a rotary kiln in which a refractory material having a thickness t is lined and a ratio t / D with respect to the inner diameter D of the roasting furnace is 0.1 to 0.25. Thereby, the ash layer temperature rise in the rotary kiln is good and the removal rate of heavy metals (Pb) increases.

  The roasting furnace is a rotary kiln having a ratio L / D between the roasting furnace length L and the roasting furnace inner diameter D of 8 to 20. By designing the rotary kiln in this way, it becomes easy to ensure the residence time of the ash layer, and the removal rate of heavy metals (Pb) increases.

In addition, as an invention of a method for suitably carrying out these, after adding a chlorine-containing substance to the ash to be treated containing heavy metals, the heavy metals are chlorinated in a roasting furnace and removed by heating and volatilizing. In the detoxification method of the ash to be treated, as the roasting furnace, a refractory material provided with a supply port of the ash to be treated at one end of the furnace and a combustion burner and an outlet for discharging the roasted ash at the other end. Before supplying to the rotary kiln using the lining rotary kiln, the treated ash and carbide are mixed, the peripheral speed and input air of the rotary kiln are controlled, and the carbide does not float on the treated ash surface layer in the rotary kiln. It generates and causes leaving 3-7% of the carbide ash layer temperature 700 to 800 ° C. and maintained 5-15 minutes ash layer temperature 950 to 1200 ° C., heated vaporized heavy metals min Characterized in that the removal.

According to the present invention, as in the apparatus invention, chlorinated heavy metals are volatilized without staying in the ash to be treated, and the removal rate of heavy metals (Pb) is increased.
Further, by mixing carbide into the ash to be treated, the rise in the ash layer temperature in the rotary kiln becomes moderate, and the ash does not rise rapidly until 1200 ° C. at which the ash starts to melt, so that chlorinated heavy metals (PbCl ₂ ) The optimal temperature range of 950 to 1200 ° C. where evaporates can be kept longer, and ash melting can be prevented. Furthermore, the amount of fuel (heavy oil) of the combustion burner required at the time of roasting can be reduced, and the fuel consumption of the roasting furnace is improved.

As described above, according to the present invention, the carbide mixed in the ash to be treated exists in a state where it does not float on the surface of the ash to be treated, so that the ash layer is generated by the thermal energy generated by the burning of the carbide. The internal temperature of the rises. By raising the temperature inside the ash layer, which tends to be lower than the surface layer, the ash layer temperature in the rotary kiln is uniformly 950 to 1200 ° C., so that chlorinated heavy metals are volatilized without remaining in the treated ash. The removal rate of heavy metals (Pb) increases.
Also, by using a rotary kiln equipped with a combustion burner on the other end side (rotary kiln rear side) of the treated ash supply port, the treated ash and combustion gas become countercurrent, and the temperature distribution is lowest on the rotary kiln supply port side, The exit side behind the rotary kiln is the highest. Therefore, since the ash to be treated is gradually heated from the supply to the rotary kiln until reaching the outlet, the risk of melting is low and the amount of heat is not wasted.
Furthermore, by mixing carbide with the ash to be treated, the ash layer temperature rises slowly without exceeding the melting temperature of the ash to be treated in the rotary kiln, so that the chlorinated heavy metal is suppressed while suppressing the melting of the ash to be treated. The optimal temperature range of 950 to 1200 ° C. from which the compound (PbCl ₂ ) evaporates can be kept longer.
Moreover, by having a heating source in the to-be-processed ash in a rotary kiln, the fuel amount of a combustion burner required at the time of roasting can be reduced, and the fuel consumption of a roasting furnace improves. Furthermore, carbides have a reducing action on heavy metals contained in the ash to be treated in the rotary kiln, and particularly suppress the generation of harmful hexavalent chromium and promote the volatilization of chlorinated heavy metals. it can.
Moreover, by mixing carbide into the treated ash, the ash layer temperature is controlled to be maintained at 950 to 1200 ° C. for 5 to 15 minutes, and even solid treated ash that takes time to raise the temperature is converted to chloride. Heavy metal (PbCl ₂ ) can be sufficiently volatilized. Moreover, by maintaining the ash layer temperature of 950 to 1200 ° C. for 5 to 15 minutes, volatilization from the inside of the treated ash which is not easily volatilized is sufficiently performed, and the residual of heavy metals contained in the treated ash is minimized. Can be suppressed. The state in which the ash layer temperature of 950 to 1200 ° C. is maintained for 5 to 15 minutes is achieved by the presence of 3 to 7% by weight of carbides at the ash layer temperature of 700 to 800 ° C.

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 equipped with a detoxification treatment apparatus for treated ash according to the first embodiment, and FIG. 2 is a configuration diagram of a detoxification treatment apparatus for treated ash according to the first embodiment. 3 (a) is a schematic diagram of the furnace body of the rotary kiln according to the first embodiment, FIG. 3 (b) is an ash layer temperature distribution diagram of the furnace body of the rotary kiln according to the first embodiment, and FIG. FIG. 5 is a diagram showing the test conditions in the ash treatment system equipped with the detoxification processing apparatus for treated ash and the results corresponding thereto. is there.
This embodiment is a technique for separating and removing heavy metals such as Pb, Zn, As, Cd, Cr, Se, Hg, Sb, and Cu. Here, the separation and removal of Pb will be described in particular.
Examples of the granular material to be treated include contaminated soil, incinerated ash, fly ash, etc. In particular, in this embodiment, the incineration ash detoxification process will be described as an example.
The chlorine-containing substance used in the examples described below is a chlorine-containing liquid or a chlorine-containing liquid containing hydrochloric acid, and examples thereof include a slurry containing hydrochloric acid, iron chloride, and calcium chloride. In addition, only chlorine-based exhaust gas or chlorine-containing solids discharged from the roasting furnace can be used as the chlorine-containing material.
(Embodiment 1)

First, the ash treatment system including the heavy metal-containing material treatment apparatus according to the first embodiment will be described with reference to FIGS. 1, 2, and 3.
The ash treatment system shown in FIG. 1 is a system for detoxifying the incineration ash discharged from the incineration facility, and is provided on each of the dryer 2 for drying the incineration ash 20 and the inlet side and the outlet side of the dryer 2. The obtained moisture meter 2a and moisture meter 2b, the mixer 3 in which the carbide 21 is added to the incinerated ash 20 whose moisture has been adjusted by the dryer 2 and mixed with stirring, and the incinerated ash 20 supplied from the mixer 3 is stored in chlorine The hopper 4 that mixes the contained material 22, the rotary kiln 1 that separates and removes heavy metals contained in the incinerated ash 20, and the cooling device 5 that cools the ash discharged from the rotary kiln 1 are configured. In addition, an exhaust gas treatment facility 6 for treating the exhaust gas 25 discharged from the rotary kiln 1 is also provided.

In the dryer 2, the incineration ash 20 is dried by direct heating with a heating gas for drying. The heating gas for drying used at this time uses exhaust gas 25 discharged from the rotary kiln 1. Although not shown, it is possible to use, for example, exhaust gas discharged from an incinerator provided as the heating gas for drying, or it is possible to provide a separate hot air furnace and use the heated gas.
In the dryer 2, the moisture change rate of the incinerated ash 20 on the inlet side and the outlet side of the dryer 2 is detected by the moisture meter 2a and the moisture meter 2b. By detecting the moisture change before and after drying of the incinerated ash 20, the air volume of the exhaust gas 25 discharged from the rotary kiln 1 is controlled, and the incinerated ash 20 is dried with the moisture content constant. In addition, 0-20% of the water | moisture content of an exit side is preferable with respect to the water | moisture content of an entrance side 20-20%, and generation | occurrence | production of dust is prevented.

The air volume control is adjusted by the opening degree of the damper 8 provided in the circulation path of the exhaust gas 25 circulated from the rotary kiln 1 to the dryer 2. The target moisture content of the incinerated ash 20 is determined in advance, and when it is greater than the target moisture content, the damper 8 is opened and the exhaust gas 25 is sent into the dryer 2 to dry the incinerated ash 20.
When the moisture content is lower than the target moisture content, the damper 8 is tightened to limit the amount of the exhaust gas 25 fed into the dryer 2 so that the incineration ash 20 is not excessively dried.
The exhaust gas discharged from the dryer 2 is sent to the exhaust gas treatment facility 6 and processed in the same manner as a part of the exhaust gas 25 discharged from the rotary kiln 1.

  In the mixer 3, the incinerated ash 20 and the carbide 21 whose moisture has been adjusted by the dryer 2 are stirred and mixed. Here, the carbide 21 to be used is preferably fine-grained coal whose particle size has been selected in advance or commercially available fine-grained coal. Moreover, it is also suitable to use the unburned part contained in the incineration ash 20 as a carbide. The mixing amount of the carbide 21 is controlled by the unburned amount contained in the incinerated ash 20 and the ash layer temperature in the rotary kiln 1, and is mixed so that 3 to 7% remains at an ash layer temperature of 700 to 800 ° C.

  The incinerated ash 20 to which the carbide 21 is added by the mixer 3 is stored in the hopper 4 and mixed with the chlorine-containing substance 22 and stirred. At this time, the chlorine-containing substance 22 is preferably sprayed and mixed on the incinerated ash 20 stored in the hopper 4, but the chlorine-containing substance 22 may be added as it is and stirred and mixed. The addition amount of the chlorine-containing material 22 is adjusted in accordance with the amount of the incineration ash 20, and it is preferable to add 5 times the amount that reacts with Pb contained in the incineration ash 20.

As shown in FIG. 2, the mixture 27 of the incinerated ash 20, the carbide 21, and the chlorine-containing material 22 mixed in the hopper 4 is supplied to the furnace body 12 from the supply port 14 of the rotary kiln 1.
As shown in FIG. 2, the rotary kiln 1 includes a cylindrical furnace body 12 having a supply port 14 provided at one end, a means for transferring the mixture 27 from the supply port 14 to the other end side, and a second end side. The exhaust port 15 is provided, and the burner portion 13 is provided on the discharge port 15 side. The mixture 27 introduced from the supply port 14 is roasted by the flame of the burner unit 13 generated by the supply of the air 26 and the auxiliary fuel 24 while being transferred to the discharge port 15.
At this time, the inside of the rotary kiln 1 is a reducing atmosphere in an oxygen-deficient state or an oxygen-free state. Further, examples of the auxiliary fuel 24 used here include heavy oil, kerosene, and regenerated oil.

  Further, the rotary kiln 1 is provided with an exhaust gas exhaust port for exhausting the gas in the furnace body 12 in the vicinity of the supply port 14, and exhausts the exhaust gas 25. In the furnace main body 12, heavy metals contained in the ash to be treated are chlorinated, and after being chlorinated, can be volatilized and separated and removed. Thereafter, it is discharged from the discharge port 15, cooled by the cooling device 5, and made harmless roasted ash 23 and discharged.

  Although not shown, the rotary kiln 1 is provided with a thermocouple thermometer and an infrared camera for measuring the ash layer temperature. A thermocouple thermometer and an infrared camera are used in combination to measure the gas temperature in the rotary kiln, which is easy to measure. The ash layer temperature is obtained from the gas temperature in the rotary kiln.

Here, the rotary kiln 1 used in the present embodiment will be described with reference to FIG.
In the present invention, a rotary kiln 1 having a refractory material t lined as a roasting furnace, provided with a supply port 14 for treated ash at one end, and a burner portion 13 and a discharge port 15 for discharging roasted ash at the other end. Use. The roasting furnace length L, the roasting furnace inner diameter D, and the refractory material thickness t are defined as shown in FIG. In addition, a is a transfer direction of ash (mixture 27).

FIG. 3B is an ash layer temperature distribution diagram of the furnace body of the rotary kiln 1 according to the first embodiment. Incinerated ash to which chlorine-containing substances are added is heated in the rotary kiln 1, and the heavy metals contained are chlorinated and volatilized, separated and rendered harmless. However, if the ash layer temperature does not rise to a certain temperature, it will be volatilized sufficiently. It remains without being. For example, Pb is chlorinated at 500 ° C. to produce PbCl _2, but PbCl ₂ is not volatilized unless heated at 950 ° C. or more for 5 minutes or more.
However, since the temperature inside the ash layer is less likely to rise than the surface layer, and the temperature distribution is as shown by the broken line in FIG. 3B, PbCl ₂ inside the ash layer may remain without being volatilized. . On the other hand, when the temperature in the rotary kiln is increased in order to volatilize PbCl ₂ present in the ash layer, it is suggested that the incinerated ash present in the surface layer is melted.
Then, when carbide was mixed with incineration ash, it became temperature distribution like the continuous line part of FIG.3 (b). Since the carbide mixed with the incinerated ash becomes a heating source that burns at 800 ° C. or higher, the temperature can be increased from the inside of the ash layer without increasing the temperature in the rotary kiln. Therefore, the ash layer temperature in the rotary kiln is uniformly 950 to 1200 ° C. without melting the incinerated ash, PbCl ₂ is volatilized without staying in the ash layer, and the Pb removal rate increases.

At this time, it is important that the carbide mixed in the incineration ash exists in a state where it does not float on the surface of the incineration ash in order to raise the temperature from the inside of the ash layer. Therefore, the peripheral speed and input air of the rotary kiln are controlled. Further, the rotary kiln 1 has a ratio t / D of the refractory material thickness t to the roasting furnace inner diameter D of 0.1 to 0.25, and a ratio L / D of the roasting furnace length L to the roasting furnace inner diameter D. It sets so that it may become 8-20. By setting the rotary kiln as described above, the ash layer temperature rise in the rotary kiln is improved and the residence time of the ash layer is easily secured. Therefore, the state maintained for 5 minutes or more in the temperature range of 950 to 1200 ° C. is generated, and stable heavy metal reduction performance can be expected.
(Embodiment 2)

Next, the ash treatment system provided with the heavy metal-containing material treatment apparatus of Example 2 will be described with reference to FIG. In the second embodiment, detailed description of the same configuration as that of the first embodiment will be omitted.
The ash treatment system according to the second embodiment is a system for detoxifying the incinerated ash discharged from the incineration facility as in the first embodiment, and the dryer 2 that dries the incinerated ash 20 and the inlet side of the dryer 2. And a moisture meter 2a and a moisture meter 2b provided on the outlet side, a rotary kiln 1 for separating and removing heavy metals contained in the incinerated ash 20, and a cooling device 5 for cooling the ash discharged from the rotary kiln 1. Is done. In addition, an exhaust gas treatment facility 6 for treating the exhaust gas 25 discharged from the rotary kiln 1 is also provided.

  In addition to the above configuration, the hopper 4 stores the incinerated ash 20 whose water content is adjusted by the dryer 2, and the screw conveyor 7 that supplies the incinerated ash from the hopper 4 to the rotary kiln 1.

As in the first embodiment, in the dryer 2, the incinerated ash 20 is dried by direct heating with a heating gas for drying, and the exhaust gas 25 discharged from the rotary kiln 1 is used in FIG. Although not shown, it is possible to use, for example, exhaust gas discharged from an incinerator provided as the heating gas for drying, or it is possible to provide a separate hot air furnace and use the heated gas.
In the dryer 2, the moisture meter 2a and the moisture meter 2b detect moisture changes before and after drying the incinerated ash 20, control the air volume of the exhaust gas 25 discharged from the rotary kiln 1, and keep the moisture content of the incinerated ash 20 constant. And let it dry. In addition, 0-20% of the water | moisture content of an exit side is preferable with respect to the water | moisture content of an entrance side 20-20%, and generation | occurrence | production of dust is prevented.

  The air volume control is adjusted by the opening degree of the damper 8 provided in the circulation path of the exhaust gas 25 circulated from the rotary kiln 1 to the dryer 2 as in the first embodiment. Further, the exhaust gas discharged from the dryer 2 is sent to the exhaust gas treatment facility 6 and processed in the same manner as a part of the exhaust gas 25 discharged from the rotary kiln 1.

The incinerated ash 20 whose moisture has been adjusted by the dryer 2 is stored in the hopper 4, conveyed while being stirred by the screw conveyor 7, and conveyed to the rotary kiln 1. At this time, the carbide 21 and the chlorine-containing substance 22 are added to the incinerated ash 20 being conveyed on the screw conveyor 7. Since the screw conveyor is used as the conveying means, the incinerated ash 20, the carbide 21 and the chlorine-containing substance 22 are sufficiently stirred and mixed before being supplied to the rotary kiln 1. The above-described mixture supplied to the rotary kiln 1 is heated and cooled by the cooling device 5 to be detoxified roasted ash 23 and discharged.
Here, the carbide 21 to be used is preferably fine-grained coal whose particle size has been selected in advance or commercially available fine-grained coal, but crushed wood chips, RDF fuel, or the like may be used. Moreover, it is also suitable to use the unburned part contained in the incineration ash 20 as a carbide. The mixing amount of the carbide 21 is controlled by the unburned amount contained in the incinerated ash 20 and the ash layer temperature in the rotary kiln 1, and is mixed so that 3 to 7% remains at an ash layer temperature of 700 to 800 ° C. The addition amount of the chlorine-containing material 22 is adjusted in accordance with the amount of the incineration ash 20, and it is preferable to add 5 times the amount that reacts with Pb contained in the incineration ash 20.

  Although not shown, as another form of the mixing means for the incineration ash 20 and the carbide 21 described above, a means for selecting the particle size of the carbide 21 is provided, the particle size-selected carbide is conveyed by the screw conveyor 7, and the incineration ash 20 is transferred there. It is good also as a structure which throws in and mixes.

Finally, with reference to FIG. 5, the test conditions in the ash treatment system equipped with the detoxification device for the ash to be treated and the corresponding results will be described. Here, in order to separate and remove Pb contained in the incinerated ash, a chlorine-containing substance was added, heated in a rotary kiln, converted to chloride, and then volatilized and separated.
Further, the rotary kiln 1 has a ratio t / D of the refractory material thickness t and the roasting furnace inner diameter D of 0.1 to 0.25, and a ratio L / D of the roasting furnace length L and the roasting furnace inner diameter D. Is set to 8-20. Furthermore, the specific gravity of incinerated ash is 2.1 kg / L (bulk specific gravity 1.4 kg / L), the specific gravity of carbide is 1.7 kg / L (bulk specific gravity 1.2 kg / L), and the particle size of carbide is about 0.5 to 25 mm, the carbide addition rate was 3%, and the residence time of the entire rotary kiln was 90 minutes.

When the incineration ash temperature was respectively set and the test was performed for Comparative Examples 1 to 3 of only the incineration ash and Examples 1 to 3 of the incineration ash + carbide, the results shown in FIG. 5 were obtained.
As shown in FIG. 5, in Example 3 in which carbides were mixed, the Pb content after roasting was 140 mg / kg less than in Comparative Example 3 with only incineration ash, and the Pb removal rate was improved. . Further, it can be seen that the amount of heavy oil, which is the fuel required for the combustion burner, is reduced to 240 L / h in spite of the incineration ash temperature range. This also shows that the carbide contained in the incinerated ash acts as a heating source to raise the temperature inside the ash layer, to make the ash layer temperature uniform, and to contribute to improvement in fuel consumption.
Similarly, Example 1 and Comparative Example 1, Example 2 and Comparative Example 2 show that the carbide promotes the volatilization of Pb.

  According to the present invention, it is possible to increase the temperature inside the ash layer without increasing the temperature in the roasting furnace by mixing the carbide with the ash to be processed without floating on the surface layer to be processed. Since melting of ash can be suppressed and heavy metals contained in the ash to be treated can be volatilized and separated, it is useful as a means for efficiently detoxifying the ash to be treated.

It is a whole block diagram of the ash processing system which comprised the detoxification processing apparatus of the to-be-processed ash which concerns on this Embodiment 1. FIG. It is a block diagram of the detoxification processing apparatus of the to-be-processed ash which concerns on this Embodiment 1. FIG. (A) is the schematic of the furnace main body of the rotary kiln which concerns on this Embodiment 1, (b) is the ash layer temperature distribution map of the furnace main body of the rotary kiln which concerns on this Example 1. FIG. It is a whole block diagram of the ash processing system which comprised the detoxification processing apparatus of the to-be-processed ash which concerns on this Embodiment 2. FIG. It is a figure which shows the test condition in the ash processing system provided with the detoxification processing apparatus of to-be-processed ash, and the result corresponding to it.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Dryer 5 Cooling device 6 Exhaust gas treatment equipment 11 Refractory material 13 Burner part 14 Supply port 15 Outlet 20 Incinerated ash 21 Carbide 22 Chlorine-containing substance 23 Roasted ash 24 Auxiliary fuel 25 Exhaust gas L Roasting furnace length D Roasting Furnace inner diameter t Refractory material thickness

Claims (6)

In the detoxification processing apparatus of the to-be-processed ash which adds a chlorine-containing substance to the to-be-processed ash containing heavy metals, chlorinates the above-mentioned heavy metals in a roasting furnace and separates and removes them by heating and volatilizing,
As the roasting furnace, using a rotary kiln with a refractory material lined, provided with a supply port for treated ash at one end, and a combustion burner and a discharge port for discharging roasted ash at the other end,
Mixing means for mixing the treated ash and carbide before supplying the treated ash into the rotary kiln, the peripheral speed of the rotary kiln and the input air are controlled, and the carbide is added to raise the temperature from the treated ash layer. Roasting furnace control means for generating a state that does not float on the surface of the treated ash, and heated to 950 to 1200 ° C. in the exit area of the rotary kiln to separate and remove heavy metals. Detoxification processing equipment. The outlet region is a state in which the ash to be treated in the rotary kiln is maintained at an ash layer temperature of 950 to 1200 ° C. for 5 to 15 minutes, and is maintained at an ash layer temperature of the outlet region of 950 to 1200 ° C. for 5 to 15 minutes. 2. The detoxification apparatus for treated ash according to claim 1, wherein the state is generated and controlled by selecting the amount of carbide added to the treated ash by the mixing means. The mixing means selects the amount of carbide added based on the unburned content contained in the treated ash, and the carbide in the treated ash in the rotary kiln is 3 to 7% by weight at an ash layer temperature of 700 to 800 ° C. The to-be-processed ash detoxification processing apparatus according to claim 1 or 2, wherein the to-be-processed ash and the carbide are mixed so that an existing state is generated. 2. The roasting furnace according to claim 1, wherein the roasting furnace is a rotary kiln in which a refractory material having a thickness t is lined and a ratio t / D with respect to the inner diameter D of the roasting furnace is 0.1 to 0.25. Detoxification equipment for treated ash. The detoxification processing apparatus for ash to be treated according to claim 1, wherein the roasting furnace is a rotary kiln having a ratio L / D of the roasting furnace length L to the roasting furnace inner diameter D of 8 to 20. . In the detoxification treatment method of the ash to be treated, after adding a chlorine-containing substance to the ash to be treated containing heavy metals, the chlorination of the heavy metals in a roasting furnace and heating and volatilization to separate and remove them,
As the roasting furnace, using a rotary kiln lined with a refractory material provided with a supply port for treated ash at one end of the furnace and a combustion burner and a discharge port for discharging roasted ash at the other end,
Before supplying to the rotary kiln, the to-be-treated ash and carbide are mixed, the peripheral speed of the rotary kiln and the input air are controlled , and the carbide in the to- be-treated ash layer raises the temperature from inside the to-be-treated ash layer. A state where it does not float on the surface layer is generated, and 3 to 7% by weight of carbide is left at an ash layer temperature of 700 to 800 ° C. and maintained at an ash layer temperature of 950 to 1200 ° C. for 5 to 15 minutes. A method for detoxifying ash to be treated, characterized by being separated and removed.

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