JP4329946B1 - Incineration fly ash treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel stabilization method and apparatus for incineration fly ash capable of efficiently treating elution of heavy metals and reducing dioxins simultaneously.
In the treatment method for stabilizing incineration fly ash, the incineration fly ash 2 includes iron and / or an iron alloy having an iron content of 90% by weight or more, or a transition metal, a reducing sulfur compound, and the like. It is a method of curing a kneaded product obtained by adding water and kneading them 4 while bringing them into contact with the atmosphere for 10 minutes or more in an environment of a temperature of 60 to 100 ° C. and a relative humidity of 70% or more. One or more additions selected from iron, iron alloys, transition metals, and reducing sulfur compounds can be added to the fly ash in the combustion exhaust gas before collecting the incinerated fly ash. The addition to the exhaust gas can be performed by mixing with an alkali agent selected from sodium hydrogen carbonate or slaked lime, or any of carbide, activated coke or activated carbon.
[Selection] Figure 1

Description

  The present invention relates to dioxins and dioxins related to incineration fly ash discharged from waste incinerators and melting furnaces such as municipal waste, industrial waste, sewage sludge, zinc recovery process, aluminum refining process, and steel refining process. The present invention relates to a method and apparatus for treating organic halogen compounds such as compounds and heavy metals. The present invention can also be applied to the treatment of organic halogen compounds such as heavy metals and dioxins contained in contaminated soil and dredged mud soil.

Dioxins are contained in exhaust gas discharged from waste incinerators and melting furnaces such as municipal waste, industrial waste, sewage sludge, zinc recovery process, aluminum refining process, and steel refining process. Dioxins have many isomers and are composed of polychlorinated dibenzopararadioxins (PCDD), polychlorinated dibenzofurans (PCDF), coplanar PCB (co-PCB) and the like. As a method for removing gaseous dioxins in the exhaust gas, a method in which powdered activated carbon is blown into the front stage of the dust collector and adsorbed and removed has become widespread. The fly ash to which dioxins in the exhaust gas adhere and the activated carbon that has adsorbed the dioxins are separated from the exhaust gas as incineration fly ash (dust collection ash) by a dust collector.
As the dust collector, there are an electrostatic dust collector (EP) and a filtration type bug filter (BF), and a bag filter having a high effect of collecting dioxins and fly ash is widely used. Such a dust collector can effectively remove dioxins from the exhaust gas, but incinerated fly ash containing heavy metals and dioxins separated by the dust collector is designated as specially managed municipal waste. . Conventionally, the following methods have been proposed as a method for treating incinerated fly ash containing such dioxins.

(1) A method for decomposing dioxins by holding incinerated fly ash containing dioxins in a reducing atmosphere such as nitrogen gas at 320 ° C. for 2 hours and at 340 ° C. for 1 to 1.5 hours [Hagen Meyer Process, OrganohalogenCompound, 27, 147-152 (1996)]. (2) A method in which dioxin-containing incinerated fly ash is heat-treated at 300 to 500 ° C. in the presence of a dioxin production inhibitor (pyridine) (JP-A-4-241880). (3) A method in which incinerated fly ash is heated to 300 to 500 ° C. under a pressure of 50 kg / cm ² or more while limiting oxygen to decompose dioxins (Japanese Patent Laid-Open No. 4-84777).
These methods reduce dioxins by heating to 300 ° C. or higher, and have the following problems. (A) Since the processing temperature is high and the processing time is long, a large amount of energy is required and the processing cost is high. (B) Dioxins may be re-synthesized during cooling. (C) Although it is necessary to perform the treatment under a reducing atmosphere such as nitrogen gas, the reduction rate of dioxins is low because oxygen cannot be completely blocked.

  Incineration fly ash generated during the incineration of industrial waste and municipal waste is eventually landfilled, but since these incineration fly ash contains heavy metals, after landfill disposal It must be fixed so that heavy metals are not eluted by rainwater. Regarding the immobilization of incineration fly ash, it is obliged to carry out any of the following methods: "Cement solidification method", "Extraction method with acid or other solvent", "Melting fixation", or "Chemical addition method". ing. Among these, the “drug addition method” has been studied in various ways because it is generally easier to handle and handle than other methods. The chemical addition method is a method in which a predetermined amount of water, a chemical and incineration fly ash are kneaded and reacted to fix harmful heavy metals. Examples of the drug used for this purpose include organic chelate heavy metal immobilizing agents that form chelate compounds with heavy metals to form stable immobilization products that are insoluble in water, and inorganic heavy metal immobilizing agents such as iron salts.

As the organic chelate heavy metal immobilizing agent, an alkali metal salt or a transition metal salt of a compound having two or more dialkyldithiocarbamic acid or dialkyldithiocarbamic acid groups in the molecule, specifically, diethyldithiocarbamic acid, N ₁ , N ₂ , There are potassium salts such as N ₃ , N ₅ -tetra (dithiocarboxy) tetraethylenepentamine, piperazine bisdithiocarbamic acid, sodium salts, zinc salts, iron salts and the like. Among the inorganic heavy metal fixing agents, iron salt-based ones include ferrous sulfates such as ferrous sulfate and ferrous chloride, ferrous sulfates such as polyiron sulfate, ferric chloride, and ferric sulfate. There are two iron salts. As a method for treating incineration fly ash using an iron salt, a method of adding ferrous salt and / or ferric salt to the incineration fly ash to immobilize heavy metals has been proposed.
In JP-A-2004-89926, a first heat treatment is performed after adding a solution of a divalent iron compound or a trivalent iron compound to a heavy metal-containing ash, and then a solution of a thiosulfate compound is added to the heavy metal-containing ash. A method for insolubilizing heavy metal-containing ash that is subjected to a second heat treatment after kneading is disclosed.

In JP-A-2005-138049, the treated incineration ash is fed into a first rotary kiln having an ambient temperature of around 600 ° C., moisture is removed and unburned material is burned, the treated product is taken out, pulverized, A precious metal catalyst is set on the inner wall, sent to a second rotary kiln operated in a reducing atmosphere at a temperature around 200 ° C., treated, and the generated chlorine gas is reduced, converted to hydrogen chloride, and calcium in the incineration ash And then, the treated product is taken out and mixed with powder slag containing 0.5 to 1% by weight of sulfur as SO ₃ , and a stabilization furnace having an ambient temperature of around 200 ° C. A method for detoxifying treated incinerated ash is disclosed in which calcium chloride is stabilized as gypsum and is obtained as a product to obtain a porous zeolite-like product.
In any of these methods, heavy metals and dioxins cannot be treated at the same time, the operation is complicated, and the treatment cost is not satisfactory.
JP-A-4-84777 JP-A-4-241880 JP 2004-89926 A JP 2005-138049 A

    In view of the above-described background art, an object of the present invention is to provide a novel stabilization method and apparatus for incineration fly ash capable of efficiently and simultaneously treating elution prevention of heavy metals and reduction of dioxins.

  In order to solve the above problems, in the present invention, in a treatment method for stabilizing incineration fly ash, iron and / or an iron alloy, a reducing sulfur compound and water are added to the incineration fly ash, A method for stabilizing incinerated fly ash, characterized in that the kneaded product obtained by kneading is cured for 10 minutes or more while being in contact with the atmosphere in an environment having a temperature of 60 to 100 ° C. and a relative humidity of 70% or more, or In the treatment method for stabilizing incineration fly ash, a kneaded product obtained by adding iron and / or an iron alloy, a transition metal, a reducing sulfur compound, and water to the incineration fly ash and kneading them, The incineration fly ash stabilization method is characterized by curing for 10 minutes or more in contact with the atmosphere in an environment of 60 to 100 ° C. and a relative humidity of 70% or more.

Moreover, in this invention, in the apparatus which stabilizes incineration fly ash, it has an incineration fly ash inlet and knead | mixes the iron and / or iron alloy, reducible sulfur compound, and water which were added to this incineration fly ash. It has a kneading machine and a curing device equipped with heating, humidifying means, and contact means with the atmosphere for curing the obtained kneaded material in an environment of 60 to 100 ° C. and a relative humidity of 70% or more for 10 minutes or more. An incinerator fly ash stabilization device or an apparatus for stabilizing incineration fly ash, characterized by having an incineration fly ash inlet, and iron and / or iron alloy and transition metal added to the incineration fly ash A kneader for kneading the reducing sulfur compound and water, and heating, humidifying means and atmospheric contact means for curing the obtained kneaded material for 10 minutes or more in an environment having a temperature of 60 to 100 ° C. and a relative humidity of 70% or more. A stabilization device for incineration fly ash characterized by having a curing device equipped with It is obtained by the.
In the present invention, the addition of one or more selected from iron, iron alloys, transition metals, and reducing sulfur compounds to the incineration fly ash can be performed in the combustion exhaust gas before collecting the incineration fly ash. In this case, the addition of iron, iron alloy, transition metal or reducing sulfur compound into one or more combustion exhaust gases is mixed with an alkali agent selected from sodium hydrogen carbonate or slaked lime, or carbide, activated coke or It can be performed by mixing with any of activated carbon.

  The present invention differs from a generally used processing method in which a kneaded product (or a kneaded molded product) humidified at the time of kneading is brought into contact with the atmosphere on a carry-out conveyor or a processing ash pit and is naturally dried. (1) “Iron and / or iron alloy” or “iron and / or iron alloy and transition metal compound”, (2) reductive sulfur compound and (3) water, and kneading them. It is intended to positively give humidity to the object under atmospheric contact and to heat and cure, and according to the present invention, it is possible to prevent elution of heavy metals from fly ash, and at the same time, dioxins cannot be reduced by the conventional method Dioxins can be reduced in a short time even in the low temperature range of 300 ° C. or lower, which has been considered. Furthermore, dioxins can be efficiently treated even in the presence of oxygen. As mentioned above, since the heavy metals and dioxins of incineration fly ash can be processed efficiently simultaneously, processing cost can be reduced.

Hereinafter, various embodiments of the present invention will be described by taking incineration fly ash treatment as an example. The incineration fly ash which is a target in the present invention is not particularly limited, but is collected by incineration fly ash (EP, BF, multi-cyclone, etc.) discharged from incineration facilities for municipal waste, industrial waste, and sewage sludge. ).
The stabilization method of the present invention will be described with reference to FIG. 1, which is a schematic configuration diagram. Incinerated fly ash 2 stored in a storage silo 1 is weighed from the storage silo 1 with a weigh scale 3 and sent to a kneader 4. (1) "Iron and / or iron alloy" or "Iron and / or iron alloy and transition metal compound" and (2) a reducing sulfur compound are added from the chemical reservoir 7 and further from the humidified water tank 8 Humidified water is added and kneaded. Moreover, a transition metal can also be added simultaneously as needed. The kneaded material discharged from the kneader is cured in the atmosphere at a temperature of 60 to 100 ° C. and a relative humidity of 70% or more for 10 minutes or more in the air. In order to cure, the curing apparatus 5 provided with a heating and humidification means can also be used. The treated product is transferred to the treated ash pit 6.

Usually, the kneaded material which came out of the kneader is cured (dried and solidified) until it is carried out on the carry-out conveyor and in the ash pit. The carry-out conveyor is sometimes referred to as a curing conveyor, but is merely a conveyor for carrying the kneaded product from the kneader to the treated ash pit, which is different from the present invention.
Below, a specific example is demonstrated and demonstrated about a curing device. As shown in FIG. 2, a curing device 5 including a blower, a heating device, and a humidifying device can be installed between the kneader 4 and the treated ash pit 6. The curing device is not a mere drying device, but is used to stabilize heavy metals in the kneaded material and reduce the concentration of dioxins while passing through this device. In other words, heavy metals are likely to be eluted from the processed product by simple drying, but there is a great difference that curing with this apparatus can stabilize and fix heavy metals and reduce dioxins.

FIG. 3 shows a schematic diagram of a hopper type curing apparatus. The kneaded material 16 is stored in a hopper that includes a watering device 18 for humidification and an air diffuser 20. If necessary, air, warmed air, or warmed humidified air 21 can be sent from the diffuser tube 20. Moreover, the watering 19 can be sprinkled from the watering apparatus 18 for humidification as needed.
Furthermore, the curing device main body (hopper) can be kept warm and heated. If the kneaded material itself has heat, the temperature is 60 to 100 ° C., and the relative humidity of the atmosphere is 70% or more, it is not necessary to provide a curing device. A water spray nozzle spray can be provided in the watering device 18 for humidification to spray water 19 continuously or intermittently. As heating and humidified air, water vapor generated by passing a high-temperature gas such as incineration exhaust gas through water can be used. Further, warm water can be sprayed from the humidifying watering device 18. Moreover, the heat retention and heating of the curing device body (hopper) can be indirectly performed by introducing incineration exhaust gas or hot water into a jacket provided on the outer wall of the hopper.

  In FIG. 4, the schematic of the kiln type | mold curing apparatus 22 was shown. Fig.4 (a) is a front view and FIG.4 (b) is AA sectional view. The kneaded material 16 on the conveying device (conveyor) 23 is a kiln type curing device provided with a warming / humidifying device (comprising a heating heater, air or humidified air or warmed humidified air discharging device, steam piping, etc.) 24. 22 is sent. Moreover, air, warm air, and warm humid air can be sent as needed. As heating and humidified air, water vapor generated by aeration of exhaust gas discharged from an incineration facility or the like may be used. The heating / humidifying device 24 may be provided in the entire conveying device 23 or may be provided only in a front portion of the conveying device 23. Before and after the curing device is in an open state, air may be naturally ventilated, or in order to improve the ventilation of the curing device, forced ventilation such as a ventilation port or an exhaust fan or a blower device may be provided at the outlet of the curing device. it can.

  Moreover, the chemical | medical agent (1 or more types chosen from iron, an iron alloy, a transition metal, a reducible sulfur compound) concerning this invention can also be added to the combustion exhaust gas of a pre-dust collector. The total amount of the chemical to be added may be added to the flue gas before the dust collector, or a part of the chemical to be added is added to the flue gas before the dust collector and the rest is added to the kneader. May be. A processing method for adding the chemical according to the present invention to the combustion exhaust gas will be specifically described with reference to FIG. In FIG. 5, 9 is an incinerator, 10 is a gas cooling tower, 11 and 11 'are flues, 12 is a dust collector, 13 is a hopper for storing the chemical according to the present invention, and 14 and 15 are chemicals according to the present invention. , 1 is a dust storage ash storage silo, 4 is a kneader, and 8 is a humidified water tank. The flue 11 or 11 ′ is connected to the flue 11 or 11 ′ from the hopper 13 for storing the medicine according to the present invention via pipes 14 and 15, and a predetermined amount of the medicine is supplied into the flue 11 and / or 11 ′. The

The exhaust gas discharged from the incinerator 9 is as high as 850 to 1100 ° C., but is cooled to 300 ° C. or less by the gas cooling tower 10. The exhaust gas cooled by the gas cooling tower 10 is sent to the dust collector 12 through the flue 11 ', where it is collected, and incinerated fly ash containing the chemical according to the present invention is separated from the exhaust gas. . The dust collection ash stored in the dust collection ash storage silo 1 is sent to the kneading machine 4, humidified water and, if necessary, cement added and kneaded, and then processed by a curing device. The kneaded product is cured for 10 minutes or more while being brought into contact with the atmosphere in a curing device equipped with a heating and humidifying means for curing in an environment of a temperature of 60 to 100 ° C. and a relative humidity of 70% or more. When spraying and adding the chemical | medical agent of this invention to the waste gas of an incinerator, you may carry out with respect to the medium temperature waste gas (generally 300-500 degreeC) discharged | emitted from the incinerator, and it is medium to low temperature after cooling with a cooling device. It can also be performed on exhaust gas (generally 140 to 300 ° C.).
According to the method of adding the chemical according to the present invention to the combustion exhaust gas at the upstream of the dust collector, there is an advantage that the mixing of the fly ash and the chemical according to the present invention is made uniform in the flue.

  Furthermore, the chemical | medical agent (1 or more types chosen from iron, an iron alloy, a transition metal, and a reducing sulfur compound) concerning this invention is mixed with the alkali chemicals chosen from sodium hydrogencarbonate or slaked lime, and it becomes a combustion exhaust gas of a pre-dust collector. It can also be added. Furthermore, the chemical | medical agent concerning this invention can also be mixed with a carbide | carbonized_material, activated coke, powdered activated carbon, etc., and can also be added to the combustion exhaust gas of a dust collector front | former stage. According to the above method, dioxins in the exhaust gas can be obtained by a synergistic effect of removing hydrogen chloride in the exhaust gas that contributes to the production of dioxins by the alkaline agent and the adsorption effect of the dioxins precursor by the carbide, activated coke, and powdered activated carbon. It is also possible to reduce heavy metals such as concentration and mercury.

As an average particle diameter of sodium hydrogencarbonate or slaked lime, 10-30 micrometers is preferable. If it is 10 μm or less, it is easy to cause clogging of the filter cloth of the dust collector, and if it is 30 μm or more, the reaction efficiency with the acid gas decreases. As the slaked lime, commercially available products such as special slaked lime and highly reactive slaked lime can be used. The particle size of the carbide, activated coke, and powdered activated carbon is preferably 100 μm or less. Examples of the activated carbon include “Eva Diamond 5AP-2” manufactured by Ebara Engineering Service Co., Ltd.
Examples of elements to be treated in the present invention include harmful heavy metals such as lead (Pb), cadmium (Cd), mercury (Hg), chromium (Cr), arsenic (As), selenium (Se), and boron ( B), fluorine (F) and the like.

  Next, the chemical | medical agent used for this invention is explained in full detail. First, the iron content of “iron and / or iron alloy” is 90% by weight or more. As iron, reduced iron powder and atomized iron powder can be used. As iron alloys, Cr-based alloy iron powder (Cr content of 10 wt% or less, iron content of 90 wt% or more), Ni-based alloy iron powder (Ni content of 10 wt% or less, iron content of 90 wt% or more) Ni-Mo alloy iron powder (Ni + Mo content 10 wt% or less, iron content 90 wt% or more). Transition metals include titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), molybdenum (Mo), Palladium (Pd), tungsten (W), cobalt (Co), and the like can be given. Iron, an iron alloy, and a transition metal can be used as a powder, or can be used by being dispersed in a solvent. As a particle size, 10-300 micrometers is preferable.

When using “iron and iron alloy”, a ratio of iron / iron alloy = 99 to 1/1 to 99 (% by weight) is preferable. When the transition metal is used, the ratio of the transition metal to “iron and / or iron alloy” is preferably 0.1 to 10 (% by weight). The addition rate of “iron and / or iron alloy” is preferably 5 to 30% by weight (to incineration fly ash).
The addition amount of the reducing sulfur compound is preferably 1 to 30% by weight (to incineration fly ash).
Reducing sulfur compounds include thiosulfate compounds such as sodium thiosulfate and ammonium thiosulfate, dithionates such as ammonium thiocyanate, ammonium dithionate, potassium dithionate and calcium dithionate, and sulfite compounds such as sodium sulfite. And bisulfite compounds such as sodium bisulfite. The particle size of the reducing sulfur compound is preferably 10 to 1000 μm. The reducing sulfur compound can be used as a powder, or can be added after being dissolved or dispersed in a solvent such as water.

Moreover, you may process combining the chemical | medical agent illustrated in this invention, the organic chelate heavy metal fixing agent, and cement. Furthermore, the chemicals exemplified in the present invention may be mixed with cement and added to the incineration fly ash for treatment.
About curing temperature, 60-100 degreeC is preferable. When the temperature is lower than 100 ° C., a pressurizing device is not required, the heating device is simplified, the device can be simplified, and it is economical from the viewpoint of energy cost. If it is less than 60 degreeC, fixation of the heavy metal in a kneaded material and decomposition | disassembly reaction of dioxins are slow, and practical use is difficult. When the temperature exceeds 100 ° C., the surface of the kneaded material is rapidly dried and the effect of fixing the heavy metal is reduced. In addition, the heat retaining device and the warming device become heavy and the equipment cost increases, which is not economical. The relative humidity during curing is 70% or more, more preferably 90% or more.

The amount of humidified water to be added at the time of kneading is usually 20 to 40% by weight (against incineration fly ash), but can be appropriately adjusted depending on the state of the kneaded product. If the water content is excessive, the fluidity is increased, and problems such as sticking of the kneaded molded products that do not solidify occur. In addition, when the water content is too low, the reaction of the drug according to the present invention does not proceed sufficiently, and the desired effect cannot be obtained, and scattering of the processed product cannot be prevented.
Although the shape of the kneaded material supplied to this apparatus is not specifically limited, In order to improve curing efficiency, a diameter of 1 to 10 mm, a length of 1 to 30 mm are preferable for pellets, and a diameter of 1 to 10 mm is preferable for granules. Further, the kneaded material may be pulverized and supplied to the apparatus before curing. The kind of the kneader is not particularly limited, and a vibration mixer, a bread granulation mixer, a biaxial bench kneader mixer, or the like can be used as appropriate.

Although it is not clear about the effect expression mechanism of this invention, it estimates as follows. As a result of intensive studies, the present inventors have dissolved or dispersed (1) “iron and / or iron alloy” or “iron and / or iron alloy and transition metal compound” and (2) a reducing sulfur compound in water. When (1) “iron and / or iron alloy” or “iron and / or iron alloy and transition metal compound” are dissolved or dispersed in water alone, or (2) the reducing sulfur compound is used alone. It was found that the oxidation-reduction potential was greatly reduced compared to when dissolved or dispersed in water, and water was in a reduced state (FIG. 6).
FIG. 6 is a graph showing changes in the redox potential when 5 wt% of each drug is added to water.

From this phenomenon, (1) “iron and / or iron alloy” or “iron and / or iron alloy and (transition metal compound)” and (2) reducing sulfur compound are used in combination, and water is added. Rather than simply drying the kneaded mixture of the incinerated fly ash that has been kneaded, it is cured while applying humidity (that is, curing while applying moisture), so that heavy metals and dioxins contained in the incinerated fly ash It is possible to promote the reduction reaction of heavy metals to make the heavy metals hardly soluble and to reduce and dechlorinate dioxins, and the curing atmosphere temperature is set to 60 to 100 ° C. The above reaction is promoted. Add (1) “iron and / or iron alloy” or “iron and / or iron alloy and transition metal compound” and (2) a reducing sulfur compound to ash, add water and knead. The resulting kneaded product is heated at a temperature of 6 To 100 ° C., by curing in contact with the atmosphere at a relative humidity of 70% or more of the environment, leading to the present invention The ability heavy metals immobilization and dioxins reduction in incineration fly ash.
The curing period according to the present invention varies depending on the properties of the incinerated fly ash and the curing conditions and is not generally determined, but is preferably cured for 10 minutes or longer. Further, after curing the kneaded product according to the present invention, it may be further naturally dried, or may be forcedly heated and dried.

The following examples illustrate the invention in more detail.
Test method The test method is as follows.
(1) Sample Table 1 shows the properties of incinerated fly ash.

(2) Dissolution test and concentration analysis 30 g of water was added to 100 g of incinerated fly ash, and a predetermined amount of drug was further added and kneaded sufficiently, followed by curing under predetermined conditions for 10 minutes to 24 hours. After that, it was subjected to a heavy metal dissolution test and dioxin concentration analysis based on the Environmental Agency Notification No. 13 test method. It was measured as the concentration of dioxins (PCDDs, PCDFs Total) by gas chromatograph mass spectrometry, and was shown as a dioxin toxicity equivalent value (ng-TEQ / g) calculated using an international toxicity equivalent coefficient (I-TEF). .
(3) Measurement of dioxin concentration To 100 g of fly ash, add 30 g of water, add a predetermined amount of chemicals, knead thoroughly, and then treat the treated product for 10 minutes to 24 hours under the specified conditions. It was used for analysis. The analysis of dioxins concentration was measured as the concentration of dioxins (PCDDs, PCDFs Total) by gas chromatography mass spectrometry, and the dioxins toxicity equivalent value (ng−) calculated using the international toxicity equivalent coefficient (I-TEF). TEQ / g).

(4) Additive drug Drug A: Iron powder
Type: Atomized iron powder (Reagent)
Particle size: 180μm or less Drug B: Iron powder / molybdenum powder mixture
Content: Iron powder / molybdenum powder = 99/1 (wt%)
Iron powder: Atomized iron powder (particle size 180μm or less, Wako Pure Chemical Industries, Ltd.
Reagents made by a formula company)
Molybdenum powder: 99.5% when particle size is 45μm or less (Wako Pure Chemical Industries Ltd.)
Company reagent)
Drug C: iron powder / nickel powder mixture
Content: Iron powder / Nickel powder = 99/1 (wt%)
Iron powder: Atomized iron powder (particle size 180μm or less, Wako Pure Chemical Industries, Ltd.
Reagents made by a formula company)
Nickel powder: 95% or more with a particle size of 150 μm or less (Wako Pure Chemical Industries, Ltd.)
Reagents made by a formula company)
Agent D: Nickel alloy iron powder
Content (wt%)
C: 0.01 ≧, Si: 0.05 ≧, Mn: 0.12 ≧, P: 0.015 ≧, S: 0.015 ≧,
Ni: 1.8-2.2, Mo: 0.9-1.1, O: 0.12 ≧, Fe: 97 ≦
Drug E: Sodium thiosulfate pentahydrate
Wako Pure Chemical Industries, reagent grade 1 drug F: iron oxide (III)
Wako Pure Chemical Industries, Reagent, Drug G: Iron trioxide
Wako Pure Chemical Industries, Ltd. Reagents Drug H: Iron (II) sulfate heptahydrate (Ferrous sulfate)
Wako Pure Chemical Industries, Ltd. Reagents Drug I: Iron (III) sulfate n-hydrate (ferric sulfate)
Wako Pure Chemical Industries, reagent

Examples 1 to 19 and Comparative Examples 1 to 4
The results of Examples 1 to 19 using Sample A in Table 1 are shown in Table 2, and the results of Comparative Examples 1 to 4 using Sample A are shown in Table 3.

  Comparative Example 3 in which curing treatment was performed at 90 ° C. and 95% relative humidity for 20 minutes without adding the agent of the present invention, and Comparative Examples 2, 4 in which the curing temperature was as low as 30 ° C. although the agent of the present invention was added. For Comparative Example 1 in which the relative humidity was as low as 30%, the concentration of dioxins was 4.2 to 4.3 ng-TEQ / G-, which was substantially equal to the untreated sample A (4.3 ng-TEQ / g-dry). As a result of carrying out the treatment of the present invention, the lead elution concentration was 0. 0, while the lead elution concentration was 2.1 to 3.1 mg / L. The concentration of dioxins was reduced to 0.8 to 3.6 ng-TEQ / g at 23 mg / L or less (Examples 1 to 19).

Examples 20-26 and Comparative Examples 5-15
Examples 20 to 26 using Sample B in Table 1 are shown in Table 4, Comparative Examples 5 to 9 using Sample B are shown in Table 5, and Comparative Examples 10 to 15 using Sample B are shown in Table 6.

  Comparative Examples 8 and 10 to 15 in which curing treatment was performed at 90 ° C. and a relative humidity of 95% or more for 20 minutes without adding the drug of the present invention, the curing agent was added, but the curing temperature was as low as 30 ° C. For Comparative Example 7 and Comparative Example 6 where the relative humidity was as low as 30%, and Comparative Example 5 where the curing time was as short as 5 minutes, the dioxin concentration was 3.7 to 4.0 ng-TEQ / G-dry, lead elution While the concentration was 1.7 to 2.1 mg / L, the treatment of the present invention resulted in a lead elution concentration of less than 0.05 mg / L and a dioxin concentration of 0.8 to 2.5 ng- Reduced to TEQ / G (Examples 20 to 26).

Examples 27-31 and Comparative Examples 16-21
Experiments on the treatment of combustion exhaust gas were conducted using the experimental apparatus shown in FIG. The amount of exhaust gas was 100 m ³ (NTP) / h. The exhaust gas from the incinerator 9 is cooled by the gas cooling tower 10, and after the treatment chemical is blown into the flue gas from the hopper 13 through the pipe 14 into the flue 11 ′ having an exhaust gas temperature of 170 ° C., dust collection processing is performed in the dust collector 12. went. To exhaust 1m ³ (NTP), the agents of the present invention when added 100mg, amount of an agent of the invention for the fly ash 100g was 1.6 wt%. A bag filter was used as the dust collector. The dust ash discharged from the dust collector 12 and stored in the storage silo 1 is sent to the kneader 4, and 30 g of water is added to 100 g of the dust ash, and the temperature is 95 ° C. and the relative humidity is 97% for 30 minutes. Cured. Then, it used for the elution test of heavy metal and the analysis of dioxin density | concentration.
Table 7 shows the results of the chemical addition treatment experiment on the exhaust gas.

Slaked lime: Special slaked lime Sodium bicarbonate: Purity 99% or more, average particle size 20 μm
Activated carbon: EVA Diamond 5AP-2 (manufactured by Ebara Engineering Service), particle size of 45 μm or less is 90% or more, active coke: average particle size of 50 μm

In Comparative Example 16 in which no curing treatment was performed without the addition of a drug, Comparative Example 17 in which curing treatment was performed without the addition of a drug, and Comparative Examples 18 to 21 in which the drug of the present invention was not added, the dioxin concentration was 3.5 to 4 .3 ng-TEQ / g-dry, the lead elution concentration was 8.1 to 11 mg / L, and the dioxins concentration was 2.1 ng-TEQ / as a result of adding and curing the agent of the present invention. The lead elution concentration was reduced to 6.1 mg / L or less under g-dry (Examples 27 to 31).

The schematic block diagram which shows an example of the apparatus which performs the stabilization process of the incineration fly ash of this invention. The flow block diagram which performs the curing process of this invention. The schematic block diagram of the hopper type curing apparatus used for the curing process of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the kiln type curing apparatus used for the curing process of this invention, (a) is a front view, (b) is the sectional view on the AA line of (a). The schematic block diagram at the time of adding a chemical | medical agent in incineration waste gas with the apparatus which performs the stabilization process of this invention. The graph which shows the change of the oxidation reduction potential when a stabilization chemical | medical agent is added.

Explanation of symbols

1: storage silo, 2: incineration fly ash, 3: weighing scale, 4: kneading machine, 5: curing device, 6: treated ash pit, 7: chemical storage tank, 8: humidified water tank, 9: incinerator, 10 : Gas cooling tower, 11 , 11 ': Flue , 12: Dust collector, 13: Hopper for storing treatment agent, 14 and 15: Supply pipe for treatment agent, 16: Kneaded product, 17: Kneaded product during curing , 18: Watering device for humidification, 20: Air diffuser, 21: Air, heated air or heated humidified air, 22: Kirle type curing device, 23: Transport device, 24: Heated humidifier

Claims (7)

  In a treatment method for stabilizing incineration fly ash, iron and / or an iron alloy having an iron content of 90% by weight or more (hereinafter referred to as an iron alloy), a reducing sulfur compound, and water are added to the incineration fly ash The incinerated fly ash stabilization process is characterized in that the kneaded product obtained by kneading them is cured for 10 minutes or more while being brought into contact with the atmosphere in an environment having a temperature of 60 to 100 ° C. and a relative humidity of 70% or more. Method.   In the treatment method for stabilizing incineration fly ash, a kneaded product obtained by adding iron and / or an iron alloy, a transition metal, a reducing sulfur compound, and water to the incineration fly ash and kneading them, A method for stabilizing incineration fly ash characterized by curing for 10 minutes or more while contacting with the atmosphere in an environment of 60 to 100 ° C. and a relative humidity of 70% or more.   The addition of one or more selected from iron, iron alloys, transition metals, and reducing sulfur compounds to the incinerated fly ash is performed in the combustion exhaust gas before collecting the incinerated fly ash. The method for treating incinerated fly ash according to 1 or 2.   The addition to one or more types of combustion exhaust gas selected from the iron, iron alloy, transition metal and reducing sulfur compound is performed by mixing with an alkali agent selected from sodium hydrogen carbonate or slaked lime. 3. A method for treating incinerated fly ash according to 3.   The addition to one or more types of combustion exhaust gas selected from the iron, iron alloy, transition metal and reducing sulfur compound is performed by mixing with any of carbide, activated coke or activated carbon. Of incineration fly ash.   In an apparatus for stabilizing incineration fly ash, a kneader having an incineration fly ash inlet and kneading iron and / or an iron alloy, a reducing sulfur compound and water added to the incineration fly ash is obtained. Incinerated fly ash comprising a curing device equipped with a heating, humidifying means and a means for contacting with the atmosphere for curing the kneaded product in an environment of a temperature of 60 to 100 ° C. and a relative humidity of 70% or more for 10 minutes or more. Stabilization device.   In an apparatus for stabilizing incineration fly ash, a kneader having an incineration fly ash inlet and kneading iron and / or an iron alloy, a transition metal, a reducing sulfur compound, and water added to the incineration fly ash And a curing device equipped with a heating, humidifying means and a contact means with the atmosphere for curing the obtained kneaded material in an environment having a temperature of 60 to 100 ° C. and a relative humidity of 70% or more for 10 minutes or more. Incineration fly ash stabilization device.

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