JP5355431B2 - Method and apparatus for treating incinerated fly ash and cement kiln combustion gas bleed dust - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recover a high purity heavy metal, gypsum and an industrial salt while suppressing operation cost and equipment cost to be low when treating incineration fly ash and dust extracted from cement kiln combustion gas. <P>SOLUTION: An apparatus 1 for treating the incineration fly ash and the dust extracted from cement kiln combustion gas includes: a dissolving tank 19 for the incineration fly ash A; a first (S2) solid-liquid separator 21 for the solid-liquid separation of a slurry S2 from the dissolving tank; an extractor 6 to extract a combustion gas from a kiln end 25a while cooling; a wet dust collector 11 to wet-collect dust D2 contained in an extracted gas G1 while utilizing a filtrate W1 from the first (S2) solid-liquid separator and to adjust the pH of the slurry to dissolve the heavy metal contained in the slurry S1 produced in wet dust collection into the liquid phase of the slurry; a first (S1) solid-liquid separator 21 for the solid-liquid separation of a slurry whose pH is adjusted in the wet dust collector; a regulating tank 22 to settle the heavy metal in a filtrate W2 separated by the first (S1) solid-liquid separator; and a second solid-liquid separator 23 for the solid-liquid separation of a slurry S3 supplied from the regulating tank. The apparatus and the like are provided. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention is a method of treating dust contained in combustion gas extracted from kiln exhaust gas passages from the kiln bottom of a cement kiln to the lowest cyclone, and incineration fly ash generated when incineration of municipal waste and the like Relates to the device.

  Incineration ash generated when municipal waste is incinerated has recently been recycled as a raw material for cement in view of the danger of depleting the final disposal site. Of municipal incineration ash, fly ash that is carried with gas and collected by the dust collector contains 10 to 20% chlorine, so it is necessary to remove the chlorine before recycling as cement raw material. . Therefore, water-washing desalination equipment such as a belt filter is used to wash away water-soluble chlorine compounds contained in the incineration fly ash and use them as cement raw materials.

  On the other hand, from chlorine, sulfur, alkali, etc. that cause problems such as blockage of preheaters in cement manufacturing facilities, paying attention to the problem of chlorine, from the kiln bottom of the cement kiln to the bottom cyclone A chlorine bypass system for extracting a part of combustion gas and removing chlorine from the kiln exhaust gas flow path is used.

  In this chlorine bypass facility, for example, as described in Patent Document 1, since chlorine is unevenly distributed on the fine powder side of the dust generated by cooling the extracted flue gas, the dust is separated into coarse powder and fine powder by a classifier. The coarse powder was returned to the cement kiln system, and the fine powder (chlorine bypass dust) containing potassium chloride (KCl) and the like was collected and added to the cement grinding mill system.

  However, in recent years, as the amount of lead brought into the cement kiln increases as the amount of waste processed increases, the recycling of waste from cement raw materials or fuel is promoted, and the amount of lead brought into the cement kiln increases. There is also a risk of exceeding. Therefore, for example, in the method for treating cement waste as described in Patent Document 2, chlorine bypass dust or the like that has been conventionally washed with water is desalted, and water is added to the waste containing chlorine to add waste to the waste. In addition to using the resulting desalted cake as a raw material for cement, the wastewater is purified to remove heavy metals such as lead and copper, without causing environmental pollution. We plan effective use.

  On the other hand, in the cement manufacturing process, selenium (Se) and thallium (Tl) are provided in addition to lead and copper. For example, pulverized coal supplied to kilns and calcining furnaces contains about 1 ppm of thallium and waste tires contain about 8 ppm of thallium. This thallium has a low boiling point, volatilizes between the kiln and the preheater of the cement baking apparatus, and most of the thallium is concentrated in the preheater, so that it is contained in the waste water treated with chlorine bypass dust.

  As mentioned above, conventionally, when recycling municipal waste incineration fly ash etc. as cement raw material, it is necessary to remove chlorine from fly ash and chlorine bypass dust, and heavy metals such as thallium, lead, selenium etc. from chlorine bypass dust Since there are cases where it is necessary to remove water, a plurality of processing facilities are required, and there is a problem that facility costs and operation costs increase, such as the need to be assigned to each processing facility.

  Therefore, Patent Document 3 discloses that incineration ash and chlorine bypass dust are washed with water at the same time, and at least one substance selected from thallium, lead, and selenium eluted in the filtrate obtained after washing with a sulfiding agent and / or A method has been proposed for reducing the facility cost and the operating cost when recycling municipal waste incineration ash or the like as a cement raw material by removing it by adding a reducing agent.

International Publication No. 97/21638 Pamphlet JP 2000-281398 A JP 2007-268398 A

  However, if the incineration fly ash and the chlorine bypass dust are washed simultaneously with the incineration ash treatment method described in Patent Document 3, since the washing equipment can be shared, the equipment cost can be kept low. For example, substances contained only in either incineration fly ash or chlorine bypass dust or substances contained in a large amount only in either one are dispersed throughout the filtrate after washing with water, There was a problem that the cost of the drug increased due to consumption.

Further, since a large amount of calcium chloride (CaCl ₂ ) is dissolved in the filtrate after the incineration fly ash is washed with water, it is difficult to recover industrial salt having high potassium chloride purity.

  In addition, heavy metals such as lead and gypsum can be recovered when the chlorine bypass dust is washed with water, but the problem is that it is not easy to reuse because the purity of the recovered heavy metals and gypsum is low. there were.

  Therefore, the present invention has been made in view of the problems in the above-described conventional technology, and in the treatment of incineration fly ash and cement kiln combustion gas extraction dust, the operation cost and the equipment cost including the chemical cost are kept low. At the same time, the purpose is to recover high-purity industrial salts, heavy metals and gypsum.

  In order to achieve the above object, the present invention is a method for treating incinerated fly ash and cement kiln combustion gas extraction dust, and is a method for treating combustion gas from a kiln exhaust gas passage from a kiln bottom of a cement kiln to a lowermost cyclone. Extracting while cooling the part, collecting the dust contained in the extraction gas wet, dissolving the incineration fly ash in water, and using the filtrate obtained by filtration for the wet dust collection, The pH of the slurry is adjusted so that heavy metals contained in the slurry generated by dust collection are dissolved in the liquid phase of the slurry, and the pH-adjusted slurry is subjected to solid-liquid separation. It is characterized by recovering heavy metals in the liquid.

And according to the present invention, in order to use the filtrate of the slurry containing incinerated fly ash for wet collection of cement kiln combustion gas extraction dust, the incineration fly ash washing process system, the extraction dust washing process system, Can be shared, and facility costs and operation costs can be reduced. In addition, heavy metals contained in the incineration fly ash and cement kiln combustion gas extraction dust are dissolved in the liquid phase of the slurry generated by wet dust collection, and the slurry is subjected to solid-liquid separation. Can be separated into gypsum contained in the solid phase, and the purity of each can be increased. Further, the filtrate obtained by washing the incinerated fly ash with water has a high pH of 11 to 12, and desulfurization is performed to desulfurize the hydroxide ions (OH ⁻ ) contained in the filtrate by wet dust collection. It can also be used as an auxiliary agent, and operation costs including drug costs can be kept low.

  In the method for treating incinerated fly ash and cement kiln combustion gas extraction dust, salt can be recovered from the filtrate obtained by recovering heavy metals. Moreover, by using the filtrate of the slurry containing incinerated fly ash for wet dust collection, calcium chloride contained in the filtrate of the slurry containing incinerated fly ash can be changed to calcium sulfate and recovered. Thereby, it can avoid that calcium chloride mixes in salt water, and the collection | recovery salt with high potassium chloride purity can be obtained.

  In the incineration fly ash and cement kiln combustion gas extraction dust treatment method, the apparatus for filtering the incineration fly ash and the apparatus for solid-liquid separation of the slurry can be shared, thereby further reducing the equipment cost and operation cost. Can be reduced.

  Further, the pH of the slurry generated by the wet dust collection can be adjusted to 1 or more and 6 or less, thereby more heavy metals contained in the slurry after the wet dust collection can be dissolved in the slurry, The recovery rate of heavy metals can be increased.

  Furthermore, in the method for treating incinerated fly ash and cement kiln combustion gas extraction dust, the recovery of heavy metals in the filtrate can be performed by a sulfurization reaction or pH adjustment, or a combination of a sulfurization reaction and pH adjustment.

  In the cement kiln combustion gas extraction dust processing method, gypsum can be recovered from the slurry generated by the wet dust collection and desulfurization and added to the cement clinker. Since this gypsum has high purity, it can be used without worrying about an increase in the concentration of heavy metals in the cement.

  Moreover, chlorine removal efficiency can be improved by removing the coarse powder in the extraction gas before performing the wet dust collection.

  Furthermore, the operation cost can be further reduced by reusing the waste water after the salt recovery for dissolving the incineration fly ash.

  The present invention also relates to a treatment apparatus for incineration fly ash and cement kiln combustion gas extraction dust, a dissolution tank for dissolving the incineration fly ash in water, and a first solid-liquid separation of the slurry from the dissolution tank. Included in liquid separator, extraction device for extracting air while cooling a part of the combustion gas from the kiln exhaust gas passage from the bottom of the kiln of the cement kiln to the lowermost cyclone, and the extraction gas extracted by the extraction device The dust is wet collected using the filtrate from the first solid-liquid separator, and the heavy metal contained in the slurry generated by the wet dust collection is dissolved in the liquid phase of the slurry. A wet dust collector for adjusting the pH of the slurry, a second solid-liquid separator for solid-liquid separation of the slurry whose pH is adjusted by the wet dust collector, and heavy metals in the filtrate separated by the second solid-liquid separator. An adjustment tank for precipitation; Characterized in that it comprises a third solid-liquid separator for solid-liquid separation of the supplied slurry adjusting tank. According to the present invention, high-purity gypsum and heavy metals can be obtained while processing the incineration fly ash and cement kiln combustion gas extraction dust as well as the above-described invention, while keeping the equipment cost and operation cost low.

  Further, the incineration fly ash and cement kiln combustion gas extraction dust processing apparatus can further include a salt recovery apparatus for recovering salt in the filtrate separated by the third solid-liquid separator. A high purity industrial salt can be obtained.

  In the incineration fly ash and cement kiln combustion gas extraction dust processing apparatus, the first solid-liquid separator and the second solid-liquid separator are separated from the solid-liquid slurry of the dissolution tank and the wet dust collector. Thus, the solid-liquid separation of the slurry whose pH has been adjusted in a time-sharing manner can be made into one solid-liquid separator, and the equipment cost and the operation cost can be further reduced.

  Further, a classification device for removing coarse powder in the extraction gas is provided between the extraction device and the wet dust collector, and fine powder and extraction gas classified by the classification device can be introduced into the wet dust collector. The chlorine removal efficiency can be increased.

  As described above, according to the present invention, when processing incineration fly ash and cement kiln combustion gas extraction dust, high-purity heavy metals, gypsum, and industrial salts are added while keeping operating costs and equipment costs including chemical costs low. It can be recovered.

It is a flowchart which shows one Embodiment of the processing apparatus of the incineration fly ash and cement kiln combustion gas extraction dust concerning this invention.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an embodiment of a processing apparatus for incineration fly ash and cement kiln combustion gas extraction dust according to the present invention. This processing apparatus 1 is roughly divided into a gas extraction section 2, a gas processing section 3, It comprises an incineration fly ash water washing processing section (hereinafter referred to as “fly ash water washing processing section”) 4 and a separation processing section 5.

  The gas extraction unit 2 is provided for extracting a part of the combustion gas from the kiln exhaust gas passage from the kiln bottom 25a of the cement kiln 25 to the lowermost cyclone (not shown). The gas extraction unit 2 includes a probe 6 for extracting combustion gas, a cooling fan (not shown) for rapidly cooling the extracted combustion gas by supplying cold air into the probe 6, and an extraction gas G 1 discharged from the probe 6. It comprises a cyclone 7 as a classifier for separating coarse powder D1 in the contained dust, a fan 8 for supplying a gas containing fine powder separated by the cyclone 7 to the scrubber 13, and the like.

  The gas processing unit 3 is provided to collect fine powder D2 and trace components such as sulfur oxides, heavy metals, and organic components contained in the exhaust gas G2 discharged from the fan 8. The gas processing unit 3 includes a wet dust collector 11 that wet-collects and removes fine powder D2 and sulfur oxides, heavy metals and organic components contained in the exhaust gas G2, and the exhaust gas G3 of the wet dust collector 11 in the cement kiln 25. In addition to returning to the exhaust gas system, the exhaust gas G3 is constituted by an exhaust fan 12 or the like for introducing the exhaust gas G3 into the dissolution tank 19.

The wet dust collector 11 collects the fine powder D2 in the exhaust gas G2 and removes chlorine from the exhaust gas G2, and the sulfur content (SO ₂ ) in the exhaust gas G2 and quick lime (CaO) contained in the fine powder D2 react with water. The slaked lime (Ca (OH) ₂ ) generated in this manner and the slaked lime supplied to make up for the shortage of slaked lime generated from the fine powder D2 are reacted to produce gypsum (CaSO ₄ .2H ₂ O). The wet dust collector 11 includes a scrubber 13, a circulating liquid tank 14, and a cleaning tower 15, and a pump 14 a for circulating the slurry is provided between the scrubber 13 and the circulating liquid tank 14. The circulating liquid tank 14 is supplied with sulfuric acid to adjust the pH value of the circulating slurry to 1 to 6, the sulfuric acid storage tank 16 and the pump 16a, and lime milk for supplying lime milk to make up for the lack of slaked lime. A storage tank 17 and a pump 17a are provided.

  The fly ash water washing processing unit 4 includes a fly ash tank 18 for temporarily storing the received incinerated fly ash (hereinafter referred to as “fly ash”) A, and a dissolution tank for dissolving the fly ash A in warm water to generate a slurry S2. 19 and a first solid-liquid separator 21 for solid-liquid separation of the slurry S2 from the dissolution tank 19.

  The separation processing unit 5 is provided for recovering heavy metals such as lead, gypsum and salt from the slurry S1 generated by the wet dust collector 11. The separation processing unit 5 includes an adjustment tank 20 that stores the slurry S1 from the wet dust collector 11, and a first solid-liquid separator 21 (first solid-liquid separator that separates the slurry S1 from the adjustment tank 20 into a solid and a liquid. 21 also performs the solid-liquid separation of the slurry S2 from the dissolution tank 19 in a time-sharing manner. Therefore, when the solid-liquid separator of the slurry S1 is performed thereafter, the “first (S1) solid-liquid separator 21”. When the solid-liquid separator of the slurry S2 is used, it is referred to as “first (S2) solid-liquid separator 21”) and the filtrate W2 from the first (S2) solid-liquid separator 21 is hydrosulfurized. The adjustment tank 22 for adding a sulfurizing agent such as soda (NaSH) and / or a pH adjusting agent such as sodium hydroxide (NaOH), and the slurry S3 after the addition of the sulfurizing agent, etc. are solid-liquid separated to contain heavy metals. Second solid-liquid separator (section) that collects cake C3 and filtrate (brine) W3 Constituted by corresponding) 23 and the "third solid-liquid separator" described in the column of means and claims to solve.

  For the first and second solid-liquid separators 21 and 23, any of the existing conventional techniques such as a filter press, a belt filter, a lamella separator, a microfilter, and a thickener can be used. These can also be used in combination. For salt recovery from salt water, any of the existing conventional techniques such as electrodialysis and spray dryer (heat treatment) can be used, and these can be used in combination.

  Next, the operation of the processing apparatus 1 will be described with reference to FIG.

  A part of the combustion gas is extracted by the probe 6 from the kiln exhaust gas passage from the kiln bottom 25a of the cement kiln 25 to the lowermost cyclone, and at the same time, the extracted combustion gas is cooled by the cold air from a cooling fan (not shown). Rapid cooling to 700 ° C. or lower, which is the melting point of the chlorine compound. Next, the extraction gas G1 from the probe 6 is separated into the coarse powder D1 and the exhaust gas G2 containing the fine powder D2 by the cyclone 7, and the coarse powder D1 is returned to the cement kiln system.

On the other hand, the exhaust gas G2 containing fine powder D2 is supplied to the scrubber 13 of the wet dust collector 11 through the fan 8, and the slurry S1 is circulated between the scrubber 13 and the circulating liquid tank 14. In the slurry S1 produced by the wet dust collector 11, slaked lime (Ca (OH) ₂ ) generated by the reaction of CaO in the fine powder D2 with water is present, and the sulfur content (SO ₂ ) present in the exhaust gas G2 is It reacts with slaked lime as follows.
SO ₂ + Ca (OH) ₂ → CaSO ₃ .1 / 2H ₂ O + 1 / 2H ₂ O
CaSO ₃ · 1 / 2H ₂ O + 1 / 2O ₂ + 3 / 2H ₂ O → CaSO ₄ · 2H ₂ O
Thereby, the sulfur content in the exhaust gas G2 is decomposed and gypsum (CaSO ₄ .2H ₂ O) is generated. Further, when slaked lime is insufficient, slaked lime is appropriately added from the lime milk storage tank 17, and when it becomes higher than a predetermined pH, sulfuric acid is appropriately added from the sulfuric acid storage tank 16.

Here, the pH varies depending on the sulfur content (SO ₂ ) contained in the exhaust gas G2 and the calcium content (CaO) brought in, but the amount of slaked lime from the lime milk storage tank 17 and the amount of sulfuric acid from the sulfuric acid storage tank 16 are adjusted. The pH of the slurry S1 is adjusted to 1-6. Table 1 shows the solubility of each heavy metal in the solution that was dissolved in water 4 with respect to fine powder 1 by weight ratio, adjusted with sulfuric acid while stirring for 30 minutes, and filtered as pH 7.3 and pH 4.4. As shown in Table 1, by lowering the pH, more heavy metals such as lead contained in the slurry S1 can be dissolved in the liquid phase in the slurry S1.

  The exhaust gas G3 discharged from the cleaning tower 15 is returned to the kiln exhaust gas system via the exhaust fan 12, and a part thereof is introduced into the dissolution tank 19.

On the other hand, hot water is added to the fly ash A from the fly ash tank 18 in the dissolution tank 19 to generate slurry S2, and the exhaust gas G3 discharged from the cleaning tower 15 via the exhaust fan 12 is supplied to the dissolution tank 19. Introduce. By introducing the exhaust gas G3, the calcium content contained in the fly ash A can be precipitated in the slurry as calcium carbonate (CaCO ₃ ), and it is possible to suppress the generation and growth of calcium scale in the downstream equipment. Note that the exhaust gas (final exhaust gas) of the cement kiln 25 after dust collection may be introduced into the dissolution tank 19 together with the exhaust gas G3 or instead of the exhaust gas G3.

Next, the slurry S2 discharged from the dissolution tank 19 is subjected to solid-liquid separation by the first (S2) solid-liquid separator 21, and the filtrate W1 obtained by solid-liquid separation is used by the wet dust collector 11. Thereby, in the wet dust collector 11, the sulfur content (SO ₂ ) in the exhaust gas G2 or the sulfuric acid supplied from the sulfuric acid storage tank 16 and the calcium chloride in the filtrate W1 react as follows.
CaCl ₂ + H ₂ SO ₄ → CaSO ₄ + 2HCl
In this way, calcium chloride can be changed to calcium sulfate, and calcium sulfate is contained in the cake C2 in the first (S1) solid-liquid separator 21 in the subsequent separation processing unit 5. The purity of potassium chloride can be increased. Further, hydroxide ions (OH ⁻ ) contained in the filtrate W1 can also be used as a desulfurization aid for desulfurizing the slurry S1 in the wet dust collector 11. On the other hand, the fly ash cake C1 obtained by solid-liquid separation in the first (S2) solid-liquid separator 21 is reused as a cement raw material in the cement kiln 25.

  Next, the slurry S1 is temporarily stored in the adjustment tank 20, and then solid-liquid separated by the first (S1) solid-liquid separator 21, and the filtrate W2 is separated from the slurry S1 to recover the cake C2 (gypsum). . Since the heavy metal in the slurry S1 is dissolved in the liquid phase of the slurry S1 by adjusting the pH of the wet dust collector 11, the cake C2 contains almost no heavy metal. Thereby, the purity of the gypsum recovered as the cake C2 can be increased, and it can be used as auxiliary gypsum having a low heavy metal content in the cement grinding step.

  Next, in the adjustment tank 22, sodium hydrosulfide as a sulfiding agent is added to the filtrate W2 from the first (S1) solid-liquid separator 21 to sulfidize lead chloride, lead oxide, etc. in the filtrate W2. To produce heavy metal sulfides such as lead sulfide. Further, instead of the sulfurizing agent, an alkali source such as sodium hydroxide may be added to adjust the pH of the filtrate W2 to a pH that lowers the solubility of each heavy metal, thereby reducing the concentration of each heavy metal in the solution. Furthermore, by combining sulfurization and pH adjustment, or by adding an auxiliary agent such as iron chloride, the recovery efficiency can be improved, and therefore the number of adjustment tanks 22 can be increased.

  Table 2 shows the weight ratio of water powder 4 dissolved in water 4 and stirring for 30 minutes to adjust the pH to 4.5 with sulfuric acid. Add soda, dissolve each heavy metal concentration in the filtrate and weight ratio, dissolve in fine powder 1 with water 4 and adjust pH to 4.5 with sulfuric acid while stirring for 30 minutes, then pH with sodium hydroxide Is adjusted to 10.5, and the concentration of each heavy metal in the filtrate is shown. From the table, it can be seen that the addition of these promotes precipitation of heavy metals such as lead contained in the filtrate W2, and can reduce the concentration of heavy metals in the filtrate W2.

  Next, in the second solid-liquid separator 23, the slurry S3 from the adjustment tank 22 is subjected to solid-liquid separation, and the heavy metal precipitated in the slurry S3 is recovered as a cake C3. Table 3 shows the recovery rate of each heavy metal. That is, from the concentration of each heavy metal in the solution after filtration at pH 4.4 in Table 1 and the concentration in the solution after filtration when sodium hydrosulfide or sodium hydroxide in Table 2 was added, The recovery rate is calculated. The table shows that the recovery rate of each heavy metal is extremely high. On the other hand, since the filtrate W3 separated by the second solid-liquid separator 23 contains almost no heavy metal, wastewater treatment can be performed and discharged after recovering industrial salt having a high potassium chloride content. Further, the filtrate W3 after the salt recovery can be reused for dissolving the fly ash A in the dissolution tank 19, or can be added to the clinker or cement grinding step so as to be within the cement chlorine concentration standard range.

As described above, according to the present embodiment, the filtrate W1 of the slurry S2 containing the fly ash A is used for wet dust collection of the fine powder (chlorine bypass dust) D2 contained in the exhaust gas G2 in the wet dust collector 11. The washing process system for fly ash A and the washing process system for fine powder D2 can be shared, and the equipment cost can be reduced. In addition, the hydroxide ions (OH ⁻ ) contained in the filtrate W1 obtained by washing the fly ash A with water can also be used as a desulfurization aid for desulfurizing the slurry S1 generated by wet dust collection. The operation cost including the drug cost can be reduced.

  In addition, as described above, the heavy metal contained in the fly ash A and the fine powder D2 dissolves in the liquid phase of the slurry S1 generated by wet dust collection, and the slurry S1 is solid-liquid separated into the filtrate W2. It can isolate | separate into heavy metals, such as lead contained, and the gypsum contained in the cake C2, and can raise the purity of the gypsum and heavy metal to collect | recover.

  Furthermore, since calcium chloride contained in the filtrate W1 of the slurry S2 containing fly ash A is changed to calcium sulfate and recovered, it is avoided that calcium chloride is mixed into the filtrate W3 of the second solid-liquid separator 23. A recovered salt having a higher potassium chloride purity than the filtrate W3 can be obtained.

  In the above embodiment, after separating the coarse powder D1 with the cyclone 7, the exhaust gas G2 containing the fine powder D2 is introduced into the wet dust collector 11. However, the extraction gas G1 extracted by the probe 6 without providing the cyclone 7 is used. May be introduced directly into the wet dust collector 11.

  In addition, it is preferable to perform solid-liquid separation of both of the slurries S1 and S2 by using the first solid-liquid separator 21 in a time division manner. However, two solid-liquid separators are installed, and chlorine bypass dust D2 and flying The ash A can also be separately solid-liquid separated.

DESCRIPTION OF SYMBOLS 1 Processing apparatus of incineration fly ash and cement kiln combustion gas extraction dust 2 Gas extraction part 3 Gas processing part 4 Fly ash washing process part 5 Separation processing part 6 Probe 7 Cyclone 8 Fan 11 Wet dust collector 12 Exhaust fan 13 Scrubber 14 Circulating fluid tank 14a Pump 15 Washing tower 16 Sulfuric acid storage tank 16a Pump 17 Lime milk storage tank 17a Pump 18 Fly ash tank 19 Dissolution tank 20 Adjustment tank 21 First solid-liquid separator 22 Adjustment tank 23 Second solid-liquid separator 25 Cement kiln 25a Kiln Bottom G1 Extraction gas G2, G3 Exhaust gas D1 Coarse powder D2 Fine powder S1 to S3 Slurry C1 to C3 Cake W1 to W3 Filtrate

Claims (12)

Extracting while cooling a part of the combustion gas from the kiln exhaust gas flow path from the bottom of the kiln of the cement kiln to the bottom cyclone,
Wet dust collection of the dust contained in the extraction gas;
After dissolving incineration fly ash in water, the filtrate obtained by filtration is used for the wet dust collection,
Adjusting the pH of the slurry so that heavy metals contained in the slurry generated by the wet dust collection are dissolved in the liquid phase of the slurry;
Solid-liquid separation of the pH adjusted slurry,
A method for treating incinerated fly ash and cement kiln combustion gas bleed dust, characterized by recovering heavy metals in the filtrate obtained by the solid-liquid separation.   The method for treating incinerated fly ash and cement kiln combustion gas bleed dust according to claim 1, wherein salt is recovered from the filtrate obtained by recovering the heavy metal.   The method for treating incinerated fly ash and cement kiln combustion gas bleed dust according to claim 1 or 2, wherein a device for filtering the incinerated fly ash and a device for solid-liquid separation of the slurry are shared.   The method for treating incinerated fly ash and cement kiln combustion gas extraction dust according to claim 1, 2, or 3, wherein the pH of the slurry produced by the wet dust collection is adjusted to 1 or more and 6 or less.   The method for treating incinerated fly ash and cement kiln combustion gas extraction dust according to any one of claims 1 to 4, wherein the heavy metal in the filtrate is recovered through a sulfurization reaction or / and pH adjustment. .   The method for treating cement kiln combustion gas extraction dust according to any one of claims 1 to 5, wherein gypsum is recovered from the slurry generated by the wet dust collection and desulfurization and added to the cement clinker.   The method for treating incinerated fly ash and cement kiln combustion gas extraction dust according to any one of claims 1 to 6, wherein coarse powder in the extraction gas is removed before the wet dust collection.   The method for treating incineration fly ash and cement kiln combustion gas extraction dust according to any one of claims 1 to 7, wherein the waste water after the salt recovery is reused for dissolution of the incineration fly ash. A dissolution tank for dissolving incineration fly ash in water;
A first solid-liquid separator for solid-liquid separation of the slurry from the dissolution tank;
A bleeder that bleeds while cooling part of the combustion gas from the kiln exhaust gas flow path from the bottom of the kiln of the cement kiln to the bottom cyclone,
The dust contained in the bleed gas extracted by the bleeder is wet-collected using the filtrate from the first solid-liquid separator, and the heavy metal contained in the slurry generated by the wet dust-collecting is collected. A wet dust collector that adjusts the pH of the slurry to dissolve in the liquid phase of the slurry;
A second solid-liquid separator for solid-liquid separation of the slurry adjusted in pH by the wet dust collector;
An adjustment tank for precipitating heavy metals in the filtrate separated by the second solid-liquid separator;
A processing apparatus for incineration fly ash and cement kiln combustion gas bleed dust, comprising: a third solid-liquid separator for solid-liquid separation of the slurry supplied from the adjustment tank.   10. The apparatus for treating incinerated fly ash and cement kiln combustion gas extraction dust according to claim 9, further comprising a salt recovery device that recovers salt in the filtrate separated by the third solid-liquid separator. .   The first solid-liquid separator and the second solid-liquid separator are configured to time-divide the solid-liquid separation of the slurry from the dissolution tank and the solid-liquid separation of the slurry adjusted in pH by the wet dust collector. The incinerator fly ash and cement kiln combustion gas bleed dust processing apparatus according to claim 9 or 10, wherein the apparatus is a single solid-liquid separator.   A classification device for removing coarse powder in the extraction gas is provided between the extraction device and the wet dust collector, and fine powder and extraction gas classified by the classification device are introduced into the wet dust collector. The incinerator fly ash and cement kiln combustion gas bleed dust processing apparatus according to claim 9, 10 or 11.

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