JP2010051868A - Method and system for washing incineration ash and dust extracted from cement kiln combustion gas with water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress equipment cost and operating cost including chemical cost to a low level while coping with an increase in the amount of generated chlorine bypass dust when washing incineration ash and dust extracted from cement kiln combustion gas with water. <P>SOLUTION: A water washing system 1 includes a dissolving tank 32 for dissolving fly ash A in water, a dissolving tank 22 for dissolving dust D contained in combustion gas extracted from a kiln exhaust gas passage from a cement kiln end to the lowest cyclone, and a vertical filter press 11 for carrying out filtration of slurry S2 supplied from the dissolving tank 32 and filtration of slurry S1 supplied from the dissolving tank 22 separately, and may include water treatment equipment 33-35 for treating the filtrate L3 of the slurry containing the fly ash discharged from the vertical filter press, and water treatment equipment 23-27 for treating the filtrate L1 of the slurry containing the dust discharged from the filtration device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and a system for flushing dust contained in combustion gas extracted from a kiln exhaust gas flow path from a kiln bottom of a cement kiln to a lowermost cyclone when incineration ash generated from incineration of municipal waste or the like About.

  Incineration ash generated when municipal waste is incinerated has recently been recycled as a cement raw material 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 facility is used for extracting chlorine from a part of the kiln exhaust gas flow path to remove chlorine.

  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 exhaust gas, the dust is divided into coarse powder and fine powder by a classifier. Separated, the coarse powder was returned to the cement kiln system, and the fine powder (chlorine bypass dust) containing potassium chloride and the like was collected and added to the cement grinding mill system.

  However, in recent years, the recycling of waste containing incineration ash as cement raw material or fuel has been promoted, and as the amount of waste processed increases, the amount of volatile components such as chlorine brought into the cement kiln also increases. The amount of chlorine bypass dust is increasing. Therefore, all the chlorine bypass dust cannot be used in the cement crushing process, and the chlorine bypass dust is also washed with water.

  In addition, with the increase in the amount of waste processed in cement manufacturing facilities, the amount of heavy metals brought into the cement kiln also increases, and it is predicted that heavy metals will exceed the allowable cement concentration. Therefore, for example, in the waste cement raw material processing method 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 to the waste. Chlorine Bypass Dust without causing environmental pollution by purifying and filtering the chlorine and using the resulting desalted cake as a raw material for cement as well as purifying waste water to remove heavy metals such as copper and lead. Is being used effectively.

  On the other hand, in the cement manufacturing process, selenium (Se) and thallium (Tl) are provided in addition to copper and lead. 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 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, recently, the amount of waste that contains incinerated ash has further increased, and the amount of generated chlorine bypass dust has been increasing. Therefore, when the incineration ash and the chlorine bypass dust are washed simultaneously with the incineration ash treatment method described in Patent Literature 3, heavy metals such as selenium and thallium that are not contained in the incineration ash but are contained in the chlorine bypass dust Since the chemical for removing the substances is dispersed in the whole filtrate after washing with water, there is a problem that a large amount of the chemical is consumed and the cost of the chemical is increased. On the other hand, if separate washing facilities are provided so that the incineration ash and the chlorine bypass dust are washed separately, there is a problem that the equipment cost and the operating cost are doubled.

  Therefore, the present invention has been made in view of the problems in the above-described conventional technology, and in response to an increase in the amount of chlorine bypass dust generated when washing incineration ash and cement kiln combustion gas extraction dust with water. The purpose is to keep operating costs including equipment costs and drug costs low.

  In order to achieve the above object, the present invention provides a method for washing incineration ash and cement kiln combustion gas extraction dust, which is extracted from the incineration ash and the kiln exhaust gas flow path from the bottom of the cement kiln to the bottom cyclone. In washing the dust contained in the burned combustion gas, the incineration ash is dissolved in water, the dust is dissolved in water, a filtration device is shared, the slurry containing the incineration ash is filtered, and the dust is included The slurry is filtered separately.

  And according to the present invention, since the slurry containing the incinerated ash and the slurry containing the dust are separately filtered by a common filtration device, it is possible to perform processing according to the characteristics of each slurry in the subsequent stage, Each of the slurries can be filtered by the above filtration device, and the equipment cost and the operation cost can be kept low in washing the incineration ash and the cement kiln combustion gas extraction dust with water.

  In the water washing method of the incineration ash and the cement kiln combustion gas extraction dust, the filtrate of the slurry containing the incineration ash discharged from the filtration device and the filtrate of the slurry containing the dust may be separately treated with water. it can. Thereby, the water treatment can be performed using the chemicals corresponding to the target components of the water treatment of the filtrate of each slurry, and the chemical cost can be reduced.

  The target component of water treatment of the incinerated ash washing filtrate may be one or more selected from the group consisting of lead, zinc, and copper, and in the water treatment of the incinerated ash washing filtrate, One or more selected from the group consisting of soda, sodium sulfide, liquid chelate, ferrous chloride, ferric chloride, a polymer flocculant, and caustic soda can be used.

  Moreover, the target component of the water treatment of the dust washing filtrate can be one or more selected from the group consisting of selenium, thallium, lead, zinc, and copper, and the water treatment of the dust washing filtrate. , One or more selected from the group consisting of hydrochloric acid, ferrous chloride, sodium hydrosulfide, ferrous sulfate, sodium sulfide, caustic soda, and lime milk can be used.

  Further, in the water washing method of the incineration ash and cement kiln combustion gas extraction dust, after each of the water treatment of the filtrate of the slurry containing the incineration ash and the filtrate of the slurry containing the dust separately, The filtrates can be combined. As a result, it is possible to share the equipment after the filtrates are merged, and the equipment cost and the operating cost can be kept low.

  Moreover, the filtrate of the slurry containing the dust after the water treatment can be discharged while being diluted with the filtrate of the slurry containing the incinerated ash after the water treatment. By diluting chlorine bypass dust containing heavy metals such as selenium and thallium with a filtrate of slurry containing incinerated ash not containing these heavy metals, the concentration of selenium and thallium in the waste water can be kept low.

  Further, in the water washing method of the incinerated ash and cement kiln combustion gas extraction dust, the water washing filtrate of the incineration ash is discharged after drainage treatment, and the water washing filtrate of the dust is used as an industrial material as it is or water washing of the dust. Salt can be recovered from the filtrate and used as an industrial material. Examples of industrial materials include raw materials such as chemical fertilizers, reagents and food additives, cleaning chemicals, and other chemical industrial raw materials. As a result, it is possible to reuse the dust washing filtrate, save time for wastewater treatment, and keep operating costs low.

  Furthermore, the present invention is a flushing system for incineration ash and cement kiln combustion gas extraction dust, an incineration ash dissolution tank for dissolving the incineration ash in water, and a kiln exhaust gas from the bottom of the cement kiln to the bottom cyclone A dust dissolution tank for dissolving dust contained in the combustion gas extracted from the flow path in water, filtration of the slurry supplied from the incineration ash dissolution tank, and filtration of the slurry supplied from the dust dissolution tank, It is characterized by comprising a filtering device that performs each separately. According to the present invention, in the same manner as the above-described invention, when washing incineration ash and cement kiln combustion gas extraction dust with water, facility costs and operation costs can be kept low.

  In the above water washing system, water treatment equipment for water-treating the filtrate of the slurry containing the incinerated ash discharged from the filtration device, and water for water-treating the filtrate of the slurry containing the dust discharged from the filtration device And processing equipment. Thereby, the water treatment can be performed using the chemicals corresponding to the target components of the water treatment of the filtrate of each slurry, and the chemical cost can be reduced.

  Moreover, in the said water washing system, the said filtration apparatus can be used as a batch-type filtration apparatus, and the switching of the filtration of the slurry containing incineration ash and the filtration of the slurry containing dust can be performed easily.

  As described above, according to the present invention, when washing incineration ash and cement kiln combustion gas extraction dust with water, the operating cost including equipment cost and chemical cost can be reduced while corresponding to the increase in the amount of chlorine bypass dust generated. It can be kept low.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a flushing system for incinerated ash and cement kiln combustion gas extraction dust (hereinafter referred to as “water washing system”) according to the present invention. The flushing system 1 is roughly divided into cement kiln kilns. A dust washing system 2 for washing the dust (hereinafter abbreviated as “dust”) D contained in the combustion gas extracted from the kiln exhaust gas passage from the bottom to the bottom cyclone, and incineration ash (hereinafter “ The ash water washing system 3 for carrying out the water washing process of A) and the common system of the vertical filter press 11, the mixing tank 12, and the drum filter 13 which are used in common by both these systems are provided.

  The dust washing treatment system 2 is provided for purifying the filtrate L1 by removing heavy metals from the filtrate L1 generated after washing the dust D with water and removing chlorine, and a dust tank 21 for storing the dust D. And a dissolution tank 22 for adding water to dust D to generate slurry S1, a filtrate tank 23 for storing filtrate L1 generated by solid-liquid separation of slurry S1 by vertical filter press 11, and filtrate L1. It is comprised with the chemical | medical solution reaction tank 24 (24A-24C) for removing heavy metals, the slurry tank 25, the filter press 26, and the filtrate tank 27. FIG.

The chemical reaction tank 24A is provided to add sodium hydrosulfide (NaSH) as a sulfiding agent to the filtrate L1 and sulfidize lead and thallium in the filtrate L1 to generate lead sulfide (PbS) and thallium sulfide. In the chemical reaction tank 24B, a ferrous compound that functions as a flocculant and a selenium reducing agent (in the example shown, ferrous chloride (FeCl ₂ )) is added to the filtrate L1 to which a sulfurizing agent has been added, and then sulfided. It is provided for aggregating lead and thallium sulfide and reducing hexavalent or tetravalent selenium in the filtrate L1 to zero-valent selenium. The chemical reaction tank 24B also has a role of discharging carbonate radical, which is an interference element for removing selenium, as a gas by adding hydrochloric acid to a pH of 4 or less. In the chemical reaction tank 24C, lime milk is added as an alkaline agent to the filtrate L1 to which the pH is adjusted to 4 or less by adding a sulfurizing agent and a ferrous compound, and the pH is adjusted to 7.5 or more and 11 or less. , To provide an optimum pH for the reduction of selenium.

  The filter press 26 is provided for solid-liquid separation of the slurry from the slurry tank 25 and for separating thallium sulfide, lead sulfide and selenium from the slurry.

  On the other hand, the ash / water washing treatment system 3 is provided to remove the heavy metals from the generated filtrate L3 after washing the fly ash A with water and removing chlorine, and to store the fly ash A in order to purify the filtrate L3. Fly ash tank 31, dissolving tank 32 for adding water to fly ash A to generate slurry S 2, and filtrate tank 33 for storing filtrate L 3 produced by solid-liquid separation of slurry S 2 by vertical filter press 11. And a chemical reaction tank 34 (34A to 34C) and a sedimentation separator 35 for removing heavy metals from the filtrate L2.

  The chemical reaction tank 34A is provided for adding sodium hydrosulfide as a sulfiding agent to the filtrate L3 to sulfidize lead in the filtrate L1 to generate lead sulfide. The chemical reaction tank 34B is agglomerated. It is provided for adding heavy metals such as lead by adding ferrous chloride as a reducing agent and reducing agent. The chemical reaction tank 34C is provided for adding a polymer flocculant for the purpose of increasing the cohesiveness of heavy metals or the like and facilitating sedimentation.

  The sedimentation separator 35 is provided for sedimenting and collecting heavy metals and the like. The sedimentation separator 35 is an inclined plate sedimentation separator having a plurality of separation plates inclined at a predetermined angle.

  The vertical filter press 11, the mixing tank 12, and the drum filter 13 are facilities commonly used in the dust water washing treatment system 2 and the ash water washing treatment system 3.

  The vertical filter press 11 is provided to separately perform solid-liquid separation of the slurry S1 supplied from the dissolution tank 22 and solid-liquid separation of the slurry S2 supplied from the dissolution tank 32. The vertical filter press 11 includes a plurality of filter plates that are horizontally arranged and stacked in a vertical direction, a jack (not shown) that raises and lowers each filter plate, and a plurality of guide rollers that are arranged laterally. A batch-type filtration device comprising an endless filter cloth wound around the plurality of guide rollers, and configured to run on the upper surface of each filter plate.

  The mixing tank 12 and the drum filter 13 are provided for collecting suspended substances such as heavy metals remaining in the filtrate from the sedimentation separator 35 and the filtrate tank 27 and purifying the waste water.

  Next, a water washing method according to the present invention using the water washing system 1 will be described with reference to FIG. In the water washing method according to the present invention, the filtration and water treatment of the slurry containing dust D are performed using the dust water washing treatment system 2 and the common system, and the filtration and water treatment of the slurry containing fly ash A are carried out by the ash water washing treatment system. 3 and common system. First, the operation of the dust washing system 2 using the common system will be described.

  When the operation is started, first, in the dissolution tank 22, the dust D from the dust tank 21 is mixed with water to produce a slurry S1, and the chlorine content contained in the dust D is dissolved in water. The slurry S1 is supplied from the dissolution tank 22 to the vertical filter press 11, and the slurry S1 is solid-liquid separated. The cake C1 produced by the vertical filter press 11 is charged into a cement kiln or the like as a cement raw material or the like, while the filtrate L1 containing chlorine is supplied to the filtrate tank 23 and temporarily stored.

Next, the filtrate L1 stored in the filtrate tank 23 is supplied to the chemical reaction tank 24A, and sodium hydrosulfide as a sulfiding agent is added to the filtrate L1 in the chemical reaction tank 24A. Thereby, lead and thallium in the filtrate L1 are sulfided to produce lead sulfide and thallium sulfide. In addition to sodium hydrosulfide, sodium sulfide (Na ₂ S) can be used as the sulfurizing agent.

Next, in the chemical reaction tank 24B, hydrochloric acid is added to the filtrate L1, the pH of the filtrate L1 is adjusted to 4 or less, the dissolved carbonate radical is discharged as a gas, and the pH of the filtrate L1 is adjusted. Ferrous chloride that functions as an aggregating agent and a selenium reducing agent is added to aggregate lead sulfide and thallium sulfide, and hexavalent or tetravalent selenium in the filtrate L1 is reduced to zero-valent selenium. In place of ferrous chloride, ferrous sulfate (FeSO ₄ ) can also be used.

  Next, in the chemical reaction tank 24C, an alkaline agent is added to the filtrate L1 having a pH of 4 or less due to the addition of the above-mentioned chemicals, and the pH is adjusted to 7.5 or more and 11 or less, which is optimal for reducing selenium.

  Next, the filtrate L1 from the chemical reaction tank 24C is solid-liquid separated by the filter press 26 through the slurry tank 25, and lead sulfide, thallium sulfide and selenium are recovered, and the secondary filtrate L2 is removed from the filtrate tank. 27 to supply to the mixing tank 12. The secondary cake C2 generated by the filter press 26 is reused as a cement raw material or the like.

  Next, operation | movement of the ash water washing processing system 3 using a common system is demonstrated.

  When the operation is started, first, in the dissolution tank 32, the fly ash A from the fly ash tank 31 is mixed with water to produce slurry S2, and the chlorine content contained in the fly ash A is dissolved in water. The slurry S2 is supplied from the dissolution tank 32 to the vertical filter press 11, and the slurry S2 is solid-liquid separated. The cake C3 produced by the vertical filter press 11 is put into a cement kiln or the like as a cement raw material or the like, while the filtrate L3 containing a chlorine content is supplied to the filtrate tank 33 and temporarily stored.

  The filtrate L3 from the filtrate tank 33 is supplied to the chemical reaction tank 34A, and lead in the filtrate L3 is sulfided to lead sulfide. Next, in the chemical reaction tank 34B, lead sulfide is precipitated by the aggregating action of ferrous chloride, and in the chemical liquid reaction tank 34C, the precipitate is aggregated into larger particles by the polymer flocculant.

  Next, the sediment is separated by sedimentation by the sedimentation separator 35. The sediment obtained by the sedimentation separator 35 is stored in a sludge pit (not shown), and then solid-liquid separated by a filter press or the like, and the cake can be reused as a cement raw material or the like.

  Next, the supernatant L4 from the sedimentation separator 35 is supplied to the mixing tank 12 and joined with the filtrate L2 from the filtrate tank 27 of the dust water washing treatment system 2.

  In the mixing tank 12, the heavy metal remaining in the supernatant L 4 from the sedimentation separator 35 and the filtrate L 2 from the filtrate tank 27 is collected, and remains in the filtrate from the mixing tank 12 by the drum filter 13. Remove heavy metals and suspended substances, add diluted water and discharge to sewers.

  In the above embodiment, selenium, thallium and lead in the filtrate L1 are removed using the dust water washing treatment system 2 and the common system, but in addition to these, zinc, copper and the like can also be removed. Sodium sulfide can be used instead of soda, and caustic soda can be used instead of lime milk. These can be used simultaneously.

  In addition, even when the filtrate L3 is water-treated using the ash-water washing treatment system 3 and the common system, zinc, copper, etc. can be removed in addition to lead, and sodium sulfide, liquid chelate, and chloride can be used instead of sodium hydrosulfide. Ferric chloride can be used instead of ferrous iron, and these can be used simultaneously. Furthermore, caustic soda can be used for pH adjustment and the like.

  As described above, in the present invention, the filtration of the slurry containing the dust D and the filtration of the slurry containing the fly ash A are performed using the common vertical filter press 11, and the mixing tank 12 and the drum filter 13 are shared. Therefore, the facility cost and the operation cost can be kept low, and the water treatment of the slurry containing dust D and the water treatment of the slurry containing fly ash A are separately performed according to the characteristics of each slurry. Cost can be reduced. The effect of reducing the drug cost will be specifically described by the following test examples.

  Table 1 shows the concentrations of heavy metals contained in the fly ash A plain water washing filtrate. As shown in the table, this filtrate contains lead and zinc, but selenium and thallium are not present, and copper is slightly present.

  Table 2 shows the concentrations of heavy metals in the Dust D plain water wash filtrate. As shown in the table, since this filtrate contains selenium and thallium in addition to lead, it must be discharged after removing them by water treatment.

  Table 3 shows the concentration of heavy metals in the filtrate when the fly ash A and the dust D are mixed and washed with water. Here, the mixing ratio of the fly ash A and the dust D is adjusted to the ratio of each processing amount per day shown in FIG. That is, fly ash A: 85 t / d (processing amount per day (tons)) and dust D: processing amount of 20 t / d, the ratio of dust D to the whole is 20 / (85 + 20) × 100 = 19.1%.

  As shown in the first row of the table, the washing filtrate in the case of mixed water washing contains various heavy metals, so these are discharged as described in the third row of the table by water treatment. Must be below the reference value. In particular, in order to remove selenium, it is necessary to add a large amount of ferrous chloride, and “6000” in the second stage in the table shows that after adding 6000 mg / l of ferrous chloride as Fe. The content of each heavy metal is shown. By adding this amount of ferrous chloride, the selenium concentration almost reaches the discharge standard value, and the other heavy metals have concentrations below the discharge standard value.

  On the other hand, Table 4 shows the concentrations of heavy metals when 6000 mg / l of ferrous chloride is added as Fe to Dust D simple water-washed filtrate and then diluted with Flyash A plain water-washed filtrate. Indicates. “6000” in the second row of the table indicates the concentration of each heavy metal after adding 6000 mg / l ferrous chloride as Fe. “Dilution” in the third stage indicates the concentration of heavy metals after dilution with ferrous chloride and then with a fly ash A plain water washing filtrate. As described in the third column “Dilution”, all heavy metals including selenium have concentrations below the discharge standard value.

  Here, in the case of performing the mixed water washing of the fly ash A and the dust D (case A), and after adding ferrous chloride to the dust D plain water washing filtrate, the fly ash A simple water washing filtrate In the case of dilution (Case B), the amount of ferrous chloride (as Fe) used when the fly ash A filtrate: 340 t / d and the dust D filtrate: 80 t / d are compared. The specific gravity of the water washing filtrate is 1.09 kg / l.

In case A,
6000 mg / l ÷ 1.09 kg / l × (340 + 80) t / d = 2,311 kg / d
Thus, 2,311 kg / d of iron (Fe) is consumed.

On the other hand, in case B,
6000 mg / l ÷ 1.09 kg / l × 80 t / d = 440 kg / d
And 440 kg / d of iron (Fe) is consumed.

From the above, it can be seen that in case B, the amount of (FeCl ₂ ) used is one fifth that of case A.

FIG. 2 is a graph showing the relationship between the amount of ferrous chloride added and the selenium concentration of treated water when selenium (Se) is removed using ferrous chloride (FeCl ₂ ). As shown in the figure, the amount of ferrous chloride to be added increases as the selenium concentration decreases. In particular, in order to reduce the selenium concentration from 0.5 mg / l to 0.1 mg / l, it is necessary to add 6000 mg-Fe / l and a large amount of ferrous chloride. On the other hand, when the selenium concentration is lowered from 3.0 mg / l to 0.38 mg / l, it is necessary to add about 6000 mg-Fe / l of ferrous chloride. After that, by diluting with fly ash A washing filtrate that does not contain selenium, it becomes possible to achieve the discharge standard, and from the difference in the amount of filtrate to be processed, the amount of ferrous chloride added is greatly reduced. be able to.

  In the above embodiment, the case where the batch-type vertical filter press 11 is used as a filtration device for separately performing filtration of the slurry containing fly ash A and filtration of the slurry containing dust D has been described. A batch type horizontal filter press can also be used, and a continuous belt filter can also be used.

  Moreover, in the said embodiment, although the case where the water washing filtrate of fly ash A and the water washing filtrate of dust D are merged in the mixing tank 12, all or one part of the water washing filtrate of dust D is shown. It can be used effectively for other purposes.

  For example, since the potassium D used as a chemical fertilizer is contained in the water washing filtrate of Dust D, this water washing filtrate can be directly used as an industrial material such as a chemical fertilizer raw material. Further, this filtrate can be used as an industrial material after collecting suspended substances such as heavy metals with the drum filter 13 of FIG.

Furthermore, since the salt D of Dust contains salt such as sodium chloride and potassium chloride, the salt can be recovered and used for industrial materials. This salt can be recovered using a crystallizer or the like. The crystallizer is a device that deposits the crystallized particle size of the solute in the water-washed filtrate by enlarging it, and recovers it through a centrifuge. It crystallizes sodium chloride for the heating type and potassium chloride for the cooling type. Can do. Moreover, salt can be collect | recovered after carrying out the waste_water | drain process for removing heavy metal etc. from a water washing filtrate. In the case where a sulfide such as calcium or SO ₂ in the washing filtrate is mixed, it is preferable to remove these after wastewater treatment. For removal of calcium, for example, a method of adding sodium carbonate or potassium carbonate to waste water is used. For removal of sulfides such as SO ₄ , the waste water is supplied to an electrodialyzer using a monovalent anion selective permeable membrane. The method of supplying can be used.

  Moreover, in the said embodiment, although the case where the fly ash was washed with water as incineration ash was illustrated, this invention can be applied also when washing the main ash instead of the fly ash, The main ash can be washed with water at the same time.

  Furthermore, each device, the type of chemical solution, the processing amount per day of the processing object, etc. shown in the above embodiment are merely examples, and can be appropriately changed without departing from the spirit of the present invention. Of course.

It is a flowchart which shows one Embodiment of the water washing system concerning this invention. It is a graph which shows the relationship between the addition amount of ferrous chloride at the time of removing selenium using ferrous chloride, and the selenium density | concentration of treated water.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water washing system 2 Dust water washing processing system 3 Ash water washing processing system 11 Vertical filter press 12 Mixing tank 13 Drum filter 21 Dust tank 22 Dissolution tank 23 Filtrate tank 24 (24A-24C) Chemical reaction tank 25 Slurry tank 26 Filter press 27 Filtrate tank 31 Fly ash tank 32 Dissolution tank 33 Filtrate tank 34 (34A to 34C) Chemical reaction tank 35 Sediment separator A Fly ash C1 to C3 Cake D Dust

Claims (12)

In washing the incinerated ash and the dust contained in the combustion gas extracted from the kiln exhaust gas passage from the bottom of the kiln of the cement kiln to the bottom cyclone,
Dissolving the incineration ash in water;
Dissolving the dust in water,
A washing method for incineration ash and cement kiln combustion gas extraction dust, wherein a filtration device is shared, and the filtration of the slurry containing the incineration ash and the filtration of the slurry containing the dust are performed separately.   2. The incineration ash and cement kiln combustion according to claim 1, wherein the filtrate of the slurry containing the incinerated ash discharged from the filtration device and the filtrate of the slurry containing the dust are each separately treated with water. Water washing method for gas extraction dust.   The incinerated ash and cement kiln combustion gas according to claim 2, wherein the target component of water treatment of the incinerated ash washing filtrate is at least one selected from the group consisting of lead, zinc, and copper. How to wash bleed dust.   One or more selected from the group consisting of sodium hydrosulfide, sodium sulfide, liquid chelate, ferrous chloride, ferric chloride, polymer flocculant, and caustic soda is used in the water treatment of the incinerated ash washing filtrate. The method for washing water of incinerated ash and cement kiln combustion gas bleed dust according to claim 2 or 3.   The incinerated ash and cement according to claim 2, wherein the target component of water treatment of the dust washing filtrate is one or more selected from the group consisting of selenium, thallium, lead, zinc, and copper. Kiln combustion gas extraction dust water washing method.   In the water treatment of the washing solution of the dust, at least one selected from the group consisting of hydrochloric acid, ferrous chloride, ferrous sulfate, sodium hydrosulfide, sodium sulfide, caustic soda, and lime milk is used. The method for washing water of incinerated ash and cement kiln combustion gas extraction dust according to claim 2 or 5.   7. The slurry filtrate containing the incinerated ash and the slurry filtrate containing the dust are separately treated with water, and the filtrates after the water treatment are merged. A method for washing incinerated ash and cement kiln combustion gas extraction dust according to any one of the above.   The incinerated ash and cement kiln according to claim 7, wherein the filtrate of the slurry containing the incinerated ash after the water treatment is discharged while diluting the filtrate of the slurry containing the dust after the water treatment. A method for washing combustion gas bleed dust.   The washed water of the incinerated ash is discharged after drainage treatment, and the washed water of the dust is used as an industrial material as it is, or the salt is recovered from the washed water of the dust and used as an industrial material. The method for washing water of incinerated ash and cement kiln combustion gas bleed dust according to any one of claims 2 to 8. An incineration ash dissolution tank for dissolving the incineration ash in water,
A dust dissolution tank that dissolves dust contained in combustion gas extracted from the kiln exhaust gas passage from the bottom of the kiln of the cement kiln to the bottom cyclone, in water;
Incineration ash and cement kiln combustion gas bleeder comprising a filtration device that separately performs filtration of the slurry supplied from the incineration ash dissolution tank and filtration of the slurry supplied from the dust dissolution tank Dust washing system. A water treatment facility for treating the filtrate of the slurry containing the incinerated ash discharged from the filtration device;
The water washing system for incinerated ash and cement kiln combustion gas bleed dust according to claim 10, further comprising: a water treatment facility for treating the slurry filtrate containing the dust discharged from the filtration device.   12. The washing system for incineration ash and cement kiln combustion gas extraction dust according to claim 10 or 11, wherein the filtration device is a batch-type filtration device.

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