JP6809915B2 - Heavy metal recovery method for incineration ash and heavy metal recovery processing system for incineration ash - Google Patents

Description

The present invention relates to a method for recovering heavy metals from incineration ash generated during incineration of municipal waste and the like, and a system for recovering heavy metals from incineration ash.

In general, most of the incineration ash, which is the residue when incinerated to reduce the volume of combustible waste such as municipal waste, is landfilled at the final disposal site after being treated with chemicals. This incineration ash contains fly ash, which is a soot and dust removed from the waste incineration exhaust gas by a bag filter or the like, and the fly ash includes lead, zinc, which have a high vapor pressure and are condensed and solidified from the above waste incineration exhaust gas. Heavy metals such as copper are contained, and a method for treating incineration ash including recovery of these useful heavy metals is required.

On the other hand, incineration ash as a raw material for cement is an effective treatment method for incineration ash from the viewpoint of prolonging the life of the final disposal site and effective use of resources, but recovering heavy metals from incineration ash in the cement manufacturing process is a process. Therefore, it is desired to prepare incineration ash in which heavy metals have been recovered when using incineration ash as a raw material for cement.

Regarding the method for recovering heavy metals from incineration ash, for example, Patent Document 1 states that molten fly ash is suspended in water and the suspension is adjusted to an appropriate value in the alkaline range by adding an acid or an alkali. Discloses a method of precipitating and recovering heavy metals in molten fly ash as hydroxides. Further, for example, in Patent Document 2, water is added to fly ash to repulp, and then a neutralizing agent is added to adjust the pH to 8.0 to 11.0, and then a heavy metal-containing residue and a salt-containing filtrate are used. A method for treating fly ash, which includes a step of solid-liquid separation, is disclosed. Further, for example, in Patent Document 3, after neutralizing a slurry composed of fly ash and mineral acid to produce a heavy metal-containing compound, the heavy metal-containing compound is washed and re-pulped with mineral acid, and then re-introduced. In addition, a method for recovering heavy metal products is disclosed.

Japanese Unexamined Patent Publication No. 7-109533 Japanese Unexamined Patent Publication No. 8-141339 Japanese Unexamined Patent Publication No. 2001-11342

However, in the conventional method as described in Patent Documents 1 to 3, when a large amount of post-treatment effluent generated in the heavy metal recovery treatment is discharged to a river or the like, it is discharged after being appropriately treated to prevent water pollution. There is a problem that the cost for the waste liquid treatment is increased.

Therefore, an object of the present invention is to efficiently recover useful heavy metals such as lead, zinc, and copper from incineration ash, and for incineration ash after recovery treatment of heavy metals and drainage after treatment, a cement manufacturing process. It is an object of the present invention to provide a heavy metal recovery method for incineration ash and a heavy metal recovery treatment system for incineration ash, which can be effectively used in the above.

In order to solve the above problems, the heavy metal recovery method for incineration ash of the present invention includes a slurrying step of adding glycol to the incineration ash to form a slurry, and an elution step of stirring the slurry to elute the heavy metals contained in the incineration ash. A solid-liquid separation step of solid-liquid separation of the slurry in which the heavy metal is eluted, and a neutralization step of neutralizing the liquid portion after the solid-liquid separation to form an agglomerate / precipitate containing the heavy metal. It is characterized by including a recovery step of recovering the agglomerated / sediment by solid-liquid separation.

According to the method for recovering heavy metals in incineration ash of the present invention, glycol is added to the incineration ash to form a slurry, the slurry is stirred to elute the heavy metals contained in the incineration ash, and then the liquid portion is obtained by solid-liquid separation. Furthermore, the liquid part is neutralized to form agglomerates / precipitates containing heavy metals, which are recovered by solid-liquid separation. Therefore, even in a relatively simple treatment step, lead, zinc, from incineration ash, Useful heavy metals such as copper can be efficiently recovered. The incinerated ash after the recovery treatment of heavy metals can be suitably used as a raw material for cement clinker and the like. Further, the post-treatment effluent (waste glycol) generated in the heavy metal recovery treatment can be suitably used as a fuel substitute or a pulverizing aid substitute in the cement manufacturing process.

In the method for recovering heavy metals from incineration ash of the present invention, it is preferable that the glycol is at least one selected from the group consisting of ethylene glycol, propylene glycol and diethylene glycol.

In the method for recovering heavy metals from incinerated ash of the present invention, it is preferable to use a glycol-containing composition having a glycol content of 20% by mass or more as the source of the glycol. According to this, even waste antifreeze (waste coolant) or the like can be effectively used.

The heavy metal recovery method for incinerated ash of the present invention further includes a step of recovering the solid portion after solid-liquid separation in the solid-liquid separation step, and the incinerated ash in which the heavy metal recovered as the solid portion is eluted is a cement raw material. It is preferable that it is used in the manufacturing process of cement. According to this, the incineration ash after the recovery treatment of heavy metals is used as a raw material for cement clinker, which contributes to the effective use of resources.

The heavy metal recovery method for incineration ash of the present invention further includes a step of recovering the liquid portion after solid-liquid separation in the recovery step, and the used glycol recovered as the liquid portion can be used as a fuel substitute or a pulverizing aid substitute. It is preferably intended for use in the cement manufacturing process. According to this, by reusing the post-treatment waste liquid (waste glycol) generated in the recovery treatment of heavy metals in the cement manufacturing process, resources can be effectively used and the cost of the waste liquid treatment can be suppressed. ..

In the method for recovering heavy metals from incinerated ash of the present invention, the pH of the slurry in the elution step is preferably 10 or more and 13 or less. According to this, heavy metals can be eluted more effectively, and as a result, useful heavy metals such as lead, zinc and copper can be recovered from the incineration ash even more efficiently.

On the other hand, the other of the present invention is a mixing and stirring device that stirs a slurry containing incineration ash and glycol to elute heavy metals from the incineration ash, and a first solid-liquid separation of the slurry containing incineration ash after elution of heavy metals. The solid-liquid separator, a neutralization reaction tank that neutralizes the liquid portion recovered through the first solid-liquid separator to form an agglomerate / precipitate containing the heavy metal, and the above-mentioned including the agglomerate / precipitate. The present invention provides a heavy metal recovery treatment system for incinerated ash, which comprises a second solid-liquid separation device for solid-liquid separation of the liquid portion after neutralization.

According to the heavy metal recovery treatment system for incinerated ash of the present invention, a mixing and stirring device that stirs a slurry containing incinerated ash and glycol to elute heavy metals from the incinerated ash and a slurry containing incinerated ash after heavy metal elution are solid-liquid. A first solid-liquid separation device for separation, a neutralization reaction tank for neutralizing the liquid portion recovered through the first solid-liquid separation device to form aggregates and precipitates containing heavy metals, and a neutralization reaction tank formed by neutralization thereof. Since it is equipped with a second solid-liquid separation device that solid-liquid separates aggregates and precipitates containing heavy metals from the liquid part after neutralization, useful heavy metals such as lead, zinc, and copper from incineration ash even with a simple configuration. Kinds can be collected efficiently. The incinerated ash after the recovery treatment of heavy metals can be suitably used as a raw material for cement clinker and the like. Further, the post-treatment effluent (waste glycol) generated in the heavy metal recovery treatment can be suitably used as a fuel substitute or a pulverizing aid substitute in the cement manufacturing process.

In the heavy metal recovery processing system for incinerated ash of the present invention, a transport device for transporting the incinerated ash in which heavy metals are eluted, which has been recovered as a solid portion thereof through the first solid-liquid separation device, is further provided. It is preferable to prepare.

In the heavy metal recovery treatment system for incinerated ash of the present invention, it is preferable to further include a storage tank for storing the after-use glycol recovered as the liquid part thereof through the second solid-liquid separation device.

According to the method for recovering heavy metals in incineration ash of the present invention, glycol is added to the incineration ash to form a slurry, the slurry is stirred to elute the heavy metals contained in the incineration ash, and then the liquid portion is obtained by solid-liquid separation. Furthermore, the liquid part is neutralized to form agglomerates / precipitates containing heavy metals, which are recovered by solid-liquid separation. Therefore, even in a relatively simple treatment step, lead, zinc, from incineration ash, Useful heavy metals such as copper can be efficiently recovered. The incinerated ash after the recovery treatment of heavy metals can be suitably used as a raw material for cement clinker and the like. Further, the post-treatment effluent (waste glycol) generated in the heavy metal recovery treatment can be suitably used as a fuel substitute or a pulverizing aid substitute in the cement manufacturing process.

According to the heavy metal recovery treatment system for incinerated ash of the present invention, a mixing and stirring device that stirs a slurry containing incinerated ash and glycol to elute heavy metals from the incinerated ash and a slurry containing incinerated ash after heavy metal elution are solid-liquid separated. The first solid-liquid separator, the neutralization reaction tank that neutralizes the liquid part recovered through the first solid-liquid separator to form aggregates and precipitates containing heavy metals, and the neutralization reaction tank. Since it is equipped with a second solid-liquid separation device that solid-liquid separates aggregates and precipitates containing heavy metals from the liquid part after neutralization, useful heavy metals such as lead, zinc, and copper from incineration ash even with a simple configuration. Can be efficiently recovered. The incinerated ash after the recovery treatment of heavy metals can be suitably used as a raw material for cement clinker and the like. Further, the post-treatment effluent (waste glycol) generated in the heavy metal recovery treatment can be suitably used as a fuel substitute or a pulverizing aid substitute in the cement manufacturing process.

It is a schematic block diagram which shows one Embodiment of the heavy metal recovery processing system of incineration ash which concerns on this invention.

The incineration ash to which the present invention is applied is a residue when incinerated to reduce the volume of combustible waste such as municipal waste, and refers to cinders generated in so-called waste incineration facilities, etc., but is not limited to this, for example. Including flying ash, which is dust removed from exhaust gas by pollution control equipment such as bag filters, and incineration ash excavated from the final disposal site where incineration ash is buried. More specifically, it is applied to incineration ash having a heavy metal content (dry mass basis) of, for example, 300 ppm or more for lead, 500 ppm or more for zinc, and / or 300 ppm or more for copper. Is preferable. For the content of heavy metals in incineration ash, for example, the fundamental parameter method of general fluorescent X-ray analysis, JIS R 5202 "Chemical analysis method of Portland cement", JIS R 5204 "Fluorescent X-ray analysis method of cement", etc. It can be measured by applying it mutatis mutandis. In general, examples of heavy metals contained in incineration ash include cadmium, chromium, manganese, and the like in addition to the above.

In the heavy metal recovery method for incinerated ash of the present invention, first, glycol is added to the incinerated ash to form a slurry (slurry step).

At that time, the incineration ash may contain metals such as empty cans and wires, glass, and unburned materials such as paper and wood chips, and it is preferable to remove these in advance. Further, since the incinerated ash is a lump, from the viewpoint of improving the heavy metal recovery efficiency, it is preferable to adjust the average particle size to 500 μm or less by using an appropriate pulverizing means or a sieve in advance, and adjust it to 200 μm or less. It is more preferable to use it. Further, in the work of adjusting the particle size of the incinerated ash, it is preferable to perform the work of removing the foreign substances in parallel from the viewpoint of work efficiency.

The glycol may be any glycol that belongs to a glycol compound, and the type thereof is not particularly limited. Typically, for example, ethylene glycol, propylene glycol, diethylene glycol and the like can be mentioned. One type of glycol may be used alone, or two or more types may be used in combination. Further, the glycol can be effectively used in the present invention as long as the content is about 20% by mass or more. Therefore, as the source of the glycol, for example, a glycol-containing composition such as waste antifreeze (waste coolant) may be used. In this case, it is preferable to use a glycol having a glycol content of 20% by mass or more and less than 100% by mass, and more preferably 40% by mass or more and less than 100% by mass. By using a glycol-containing composition in such a range, effective use of waste antifreeze liquid (waste coolant) and the like can be achieved. On the other hand, if the glycol content is less than the above range, it may be difficult to elute heavy metals such as lead, zinc and copper from the incineration ash. Alternatively, hydrous glycol can be used as a source of glycol. In this case, it is preferable to use a glycol having a glycol content of 20% by mass or more and less than 100% by mass, and more preferably 20% by mass or more and 80% by mass or less. By using a glycol-containing composition in such a range, the amount of glycol used can be suppressed, and at the same time, heavy metals such as lead, zinc, and copper contained in the incineration ash in the form of a water-soluble salt can be efficiently eluted. It often happens.

As for the ratio of incinerated ash to glycol in the above slurrying step, the mass of incinerated ash (usually solid) is A parts by mass, and the mass of glycol (usually liquid) (when a glycol-containing composition is used, the composition is concerned). The A / B mass ratio is preferably 1/2 to 1/20, and more preferably 1/2 to 1/10, when the mass of the entire object is taken as parts of B mass. If the amount of incineration ash exceeds the above range, it becomes difficult to form a slurry, and the elution efficiency of heavy metals such as lead, zinc, and copper from the incineration ash may deteriorate. If the amount of glycol (glycol-containing composition) exceeds the above range, the efficiency of heavy metal recovery is not so improved, but the amount of post-treatment effluent (waste glycol) is unnecessarily increased.

In the heavy metal recovery method for incineration ash of the present invention, the slurry is then stirred to elute heavy metals such as lead, zinc and copper contained in the incineration ash (elution step).

The temperature of the slurry in the elution step is preferably 5 ° C. or higher and 100 ° C. or lower, and more preferably 50 ° C. or higher and 100 ° C. or lower. When the temperature of the slurry is within the above range, heavy metals such as lead, zinc and copper in the incineration ash can be eluted more efficiently. On the other hand, if the temperature of the slurry is lower than 5 ° C., the time required for a sufficient amount of heavy metals to elute from the incineration ash may become long. Further, when the temperature of the slurry exceeds 100 ° C., special equipment for temperature control is required.

The pH of the slurry in the elution step is preferably 10 or more and 13 or less, and more preferably 11 or more and 13 or less. When the pH of the slurry is within the above range, heavy metals such as lead, zinc and copper in the incineration ash can be eluted more efficiently. On the other hand, if the pH of the slurry is lower than 10, heavy metals such as lead, zinc and copper in the incineration ash may be insolubilized and elution may be difficult. Normally, incineration ash is basic, so that the pH of the slurry is 10 or more and 13 or less without using a pH adjuster, but a high pH at which heavy metals such as lead, zinc, and copper are efficiently eluted. The pH of the slurry may be adjusted using a general pH adjuster such as caustic soda so as to be in the range. In this case, caustic soda is preferably used as an aqueous solution. If the pH of the slurry exceeds 13, the amount of the pH adjuster used will be excessive and the work efficiency will be deteriorated.

The stirring time of the slurry in the elution step is preferably 15 minutes to 150 minutes, more preferably 30 minutes to 60 minutes. When the stirring time of the slurry is within the above range, heavy metals such as lead, zinc and copper in the incineration ash can be sufficiently eluted. On the other hand, if the stirring time of the slurry is less than 15 minutes, a sufficient amount of heavy metals may not be eluted from the incineration ash. Further, if the stirring time of the slurry exceeds 150 minutes, the work efficiency of the heavy metal recovery process is lowered because the time required for the elution step is long.

The means for stirring the slurry in the elution step is not particularly limited as long as it can stir the slurry. For example, a mixing and stirring device such as a complete mixing tank with a stirring device or a rotary drum type mixing tank can be preferably used. When using a complete mixing tank, the mixing tank may be a single tank type or a double tank type (series or parallel), and when using a rotary drum type mixing tank, the slurry may be stirred as it is, or the pulverizing medium may be used. You may use it. The means for stirring the slurry may also serve as a mixing and stirring means for adding glycol to the incineration ash to form a slurry in the slurrying step.

The mixing and stirring device may be further provided with a heating device for heating the slurry. As a result, the temperature of the slurry can be controlled to the optimum temperature for elution of heavy metals such as lead, zinc and copper, and the heavy metal recovery process from the incineration ash can be performed more efficiently.

In the method for recovering heavy metals from incineration ash of the present invention, the slurry in which heavy metals such as lead, zinc, and copper are eluted is then solid-liquid separated (solid-liquid separation step).

The means for solid-liquid separation of the slurry in the solid-liquid separation step is not particularly limited as long as the slurry can be solid-liquid separated. For example, a general-purpose solid-liquid separator such as a filter press, a pressure drum filter, a roll press, and a belt filter can be preferably used. However, from the viewpoint of both solid-liquid separation performance and ease of operation, a pressurized type such as a filter press or a pressurized drum filter is more preferable.

The solid portion (incineration ash in which heavy metals are eluted) separated by the solid-liquid separation step after the solid-liquid separation preferably has a solid content of 50% by mass or more, preferably 60% by mass or more. Is more preferable. If the solid content is less than the above range, the separated heavy metals such as lead, zinc, and copper may be insufficiently separated, and the purpose of recovering the heavy metals may not be sufficiently achieved.

The higher the concentration of heavy metals, the higher the recovery efficiency of heavy metals in the liquid part after solid-liquid separation (containing glycol and dissolved heavy metals such as lead, zinc, and copper) separated in the solid-liquid separation step. However, specifically, for lead or copper, 1 mg / L or more is preferable, and 10 mg / L or more is more preferable. Speaking of zinc, 5 mg / L or more is preferable, and 25 mg / L or more is more preferable.

Dissolved concentration of heavy metals such as lead, zinc and copper in the liquid part after solid-liquid separation (containing glycol and dissolved heavy metals such as lead, zinc and copper) separated in the solid-liquid separation step. Can be confirmed by a test according to JIS K 0102 "Factory wastewater test method", and one of the frame atomic absorption method, the electrically heated atomic absorption method, the ICP emission spectroscopic analysis method, and the ICP mass analysis method. Using the method, for example, all analysis of lead, zinc and copper is possible. However, regardless of which method is used, the pretreatment of the analysis sample is complicated, and it is necessary to prepare an analyzer that is not installed in a general cement manufacturing factory. High precision is rarely required for values. Therefore, from the viewpoint of the convenience of the analysis operation and the convenience of obtaining the measurement result in a short time, for example, the use of a simple analysis method such as "Pack Test (registered trademark)" manufactured by Kyoritsu Rikagaku Kenkyusho Co., Ltd. is used. preferable. Specifically, when this "Packtest (registered trademark)" is used, "Packtest SPK-Pb" (trade name, manufactured by Kyoritsu Rikagaku Kenkyusho Co., Ltd.) for lead and "Packtest WAK-" for zinc. Zn "(trade name, manufactured by Kyoritsu Rikagaku Kenkyusho Co., Ltd.) and copper can be analyzed using" Packtest WAK-Cu "(trade name, manufactured by Kyoritsu Rikagaku Kenkyusho Co., Ltd.).

In a preferred embodiment of the present invention, the liquid portion after the solid-liquid separation (containing glycol and heavy metals such as lead, zinc, and copper are dissolved) separated in the solid-liquid separation step is subjected to the elution step. As the glycol (or glycol-containing composition) used in the above, it may be reused. By reusing or repeating glycol (or glycol-containing composition) in the above elution step, the dissolved concentration of heavy metals such as lead, zinc, and copper contained in the liquid part after the solid-liquid separation is increased, and this It is possible to increase the amount of heavy metal recovered per operation in the neutralization step and the recovery step, which are the subsequent steps of the solid-liquid separation step.

In a preferred embodiment of the present invention, the solid portion after solid-liquid separation in the solid-liquid separation step may be recovered. Then, the incinerated ash in which the heavy metal recovered as the solid part is eluted may be used as a raw material for cement clinker in the cement manufacturing process. According to this, it is possible to provide a cement raw material obtained by using incineration ash containing heavy metals as a raw material and reducing the heavy metals, which contributes to effective use of resources.

In the method for recovering heavy metals from incineration ash of the present invention, the liquid portion (containing glycol, lead, zinc, copper, etc.) separated in the solid-liquid separation step after the solid-liquid separation is dissolved. ) Is neutralized to form aggregates / precipitates containing heavy metals such as lead, zinc and copper (neutralization step).

The means for neutralization in the neutralization step is the liquid portion after the solid-liquid separation separated in the solid-liquid separation step (containing glycol, and heavy metals such as lead, zinc, and copper are dissolved). It is not particularly limited as long as it can neutralize. For example, an acid is added as a neutralizing agent to shift the pH of the liquid portion to the acidic side. As a result, heavy metals such as lead, zinc, and copper dissolved in the liquid portion can be precipitated and precipitated as, for example, hydroxides thereof, and eventually, aggregates and precipitates containing the heavy metals can be precipitated. Can be formed. It is more preferable that the pH after neutralization is 8 or more and 9.5 or less. On the other hand, when the pH is lower than 8 or higher than 9.5, it may be difficult to efficiently form the aggregate / precipitate containing the heavy metal.

The acid used in the neutralization step is not particularly limited, but typically examples thereof include sulfuric acid, nitric acid, hydrochloric acid, acetic acid, and formic acid. Of these, sulfuric acid, nitric acid, and hydrochloric acid are preferably used from the viewpoint of reaction rate, and nitric acid and hydrochloric acid are more preferable from the viewpoint of not producing by-products with dissolved calcium. One type of acid may be used alone, or two or more types may be used in combination.

The temperature condition in the neutralization step is preferably 0 ° C. or higher and 40 ° C. or lower, and more preferably 10 ° C. or higher and 30 ° C. or lower. When the temperature condition is within the above range, heavy metals such as lead, zinc, and copper dissolved in the liquid portion can be effectively precipitated and precipitated as, for example, hydroxides thereof. .. On the other hand, if the temperature condition in the neutralization step is lower than 0 ° C., the neutralization reaction rate may be lowered and the efficiency may be lowered, and if it is further higher than 40 ° C., the acid added as the neutralizing agent volatilizes. May reduce efficiency.

In the above neutralization step, neutralization may be performed with stirring for the purpose of increasing the efficiency of the neutralization reaction. The means for stirring is not particularly limited, and a mixing / stirring device such as a complete mixing tank with a general stirring device or a rotary drum type mixing tank can be preferably used.

The neutralization time in the neutralization step is preferably 15 minutes to 120 minutes, more preferably 30 minutes to 90 minutes. When the neutralization time is within the above range, heavy metals such as lead, zinc, and copper dissolved in the liquid portion can be effectively precipitated and precipitated as, for example, hydroxides thereof. it can. On the other hand, if the neutralization time is less than 15 minutes, the neutralization reaction becomes insufficient, and it may be difficult to efficiently form agglomerates / precipitates containing the heavy metals. Further, if the neutralization time exceeds 120 minutes, the work efficiency of heavy metal recovery is lowered because the time required for the neutralization step is long.

In the heavy metal recovery method for incinerated ash of the present invention, the aggregate / precipitate containing the heavy metal formed in the neutralization step is then recovered by solid-liquid separation (recovery step).

In the recovery step, the means for recovering the aggregate / precipitate containing the heavy metal may be any means capable of separating the aggregate / precipitate, and the method is not particularly limited. For example, a general-purpose solid-liquid separator such as a filter press, a pressure drum filter, a roll press, and a belt filter can be preferably used. However, from the viewpoint of both solid-liquid separation performance and ease of operation, a pressurized type such as a filter press or a pressurized drum filter is more preferable.

In a preferred embodiment of the present invention, the liquid portion (containing glycol and heavy metals such as lead, zinc and copper are recovered and removed) after solid-liquid separation in the recovery step may be recovered. Then, the post-treatment effluent (waste glycol) recovered as the liquid part can be used as a fuel substitute within the range where stable operation of the cement clinker firing process is ensured, and the chlorine content of the cement to be manufactured is of good quality. It can be reused as a substitute for a crushing aid in the finishing crushing process of cement within an allowable range. At that time, even if the composition has a water content of about 80% by mass and also contains other components in a complex manner, the cement manufacturing process directly or in whole amount thereof, if necessary. It is possible to process it by effectively using it. Therefore, in the past, heavy metal recovery treatment from incineration ash using mineral acid or the like was indispensable as a complicated work, and a large amount of post-treatment effluent generated in heavy metal recovery treatment was optimized so as to meet the wastewater standard. The work to be done can be omitted, or at least labor saving.

Hereinafter, the present invention will be described in more detail with reference to the drawings. However, the scope of the present invention is not limited to the embodiments described below.

FIG. 1 is a schematic configuration diagram showing an embodiment of a heavy metal recovery treatment system for incinerated ash according to the present invention. The heavy metal recovery treatment system 1 for incineration ash according to this embodiment (hereinafter, may be simply referred to as “treatment system 1”) comprises a supply device 2 for incineration ash A1 and a glycol or glycol-containing composition, and elutes heavy metals. Mixing and stirring device 4 that generates and stirs slurry S from the supply device 3 of glycols G1 used as a solvent for the above, the incineration ash A1 supplied from the supply device 2, and the glycols G1 supplied from the supply device 3. And heavy metals such as lead, zinc, and copper collected as solid parts through the first solid-liquid separation device 5 for solid-liquid separation of the slurry S discharged from the mixing and stirring device 4 and the first solid-liquid separation device 5. The transport device 6 for transporting the incineration ash A2 in which the above is eluted to the cement manufacturing process such as the clinker firing step in the rotary kiln, and the glycols G2 (containing glycol and lead) discharged from the first solid-liquid separation device 5. , Zinc, heavy metals such as copper are dissolved) in the neutralization reaction tank 7, and glycols G3 (containing glycol, heavy metals such as lead, zinc, copper, etc.) discharged from the neutralization reaction tank 7 A second solid-liquid separator 8 for solid-liquid separation (including agglomerates and precipitates) and waste glycols G4 (including glycols, heavy metals such as lead, zinc, and copper) discharged from the second solid-liquid separator 8. It is provided with a relay tank 9 which is a storage tank for storing (collected and removed). In the heavy metal recovery treatment system for incinerated ash according to the present invention, among the configurations of the embodiment shown in FIG. 1, at least the mixing and stirring device 4, the first solid-liquid separation device 5, the neutralization reaction tank 7, and the second solid By providing the liquid separation device 8, the minimum required configuration can be satisfied.

In the embodiment shown in FIG. 1, the supply device 2 has a hopper and a supply mechanism for supplying the incineration ash A1 with a predetermined mass or a predetermined volume, and supplies the incineration ash A1 to the mixing and stirring device 4. .. The supply device 2 may be provided with a storage tank for incineration ash A1 in the hopper, and further, a foreign matter removing facility for removing metals and the like from the incineration ash and incineration ash are specified on the upstream side of the storage tank. A crushing and classifying facility may be provided to achieve the particle size of. These foreign matter removing equipment and crushing classification equipment may be appropriately used depending on the state of the received incineration ash. Examples of the supply method of the incinerated ash A1 by the supply device 2 include a belt type, a screw type, a vibration type, and a table type.

In the embodiment shown in FIG. 1, the supply device 3 makes the glycols G1 in the storage container, for example, about 2 to 20 times the mass of the incinerated ash A1 supplied by the supply device 2. I am trying to supply it. The supply device 2 or the storage container for the glycols G1 may be provided with a heating facility for heating the glycols G1. As the heating equipment, an in-line type or shell type general-purpose liquid heating heater or the like may be used.

In the embodiment shown in FIG. 1, in the mixing and stirring device 4, a process of mixing incineration ash A1 and glycols G1 to generate a slurry S, and lead, zinc, and copper from the incineration ash A1 in the slurry S. The process of eluting heavy metals such as the above is being carried out. That is, the mixing and stirring device 4 is provided with a stirring blade 41 as a slurry stirring device inside the mixing and stirring device 4, and the incineration ash A1 and glycols G1 are mixed by the stirring blade 41, and the slurry S produced by the mixing is mixed. Can be agitated. As the stirring blade 41, for example, a general screw type or the like may be used.

Further, in the mixing / stirring device 4 of this embodiment, a heating facility 42 and a thermometer 43 are attached to the inside thereof, and the temperature of the slurry S measured by the thermometer 43 can be controlled by the heating facility 42. I am trying to do it. As the heating facility 42, for example, a device that supplies a high-temperature gas such as exhaust gas into the slurry S by using an air diffuser, a general low-frequency induction heating device, or the like may be used.

In the embodiment shown in FIG. 1, the slurry S discharged from the mixing / stirring device 4 is conveyed to the first solid-liquid separation device 5 by a slurry transport device (not shown). As the slurry transport device, a general slurry pump, piston pump, mono pump, or the like may be used. Then, in the conveyed slurry S, the incineration ash A2 in which heavy metals are eluted and the heavy metals such as lead, zinc, and copper eluted from the incineration ash A1 are dissolved by the first solid-liquid separation device 5. It is separated from glycols G2. As the first solid-liquid separation device 5, a general filtration device such as a filter press, a pressurized phyllodes filtration device, a screw press, or a belt press may be used.

In the embodiment shown in FIG. 1, a transport device 6 is continuously provided in the first solid-liquid separation device 5, and incineration ash A2 recovered as a solid part after solid-liquid separation is clinker-fired in a rotary kiln. It is transported to the cement manufacturing process such as the process. As the transfer device 6, a general-purpose transfer device or the like related to low water content powder transportation such as a belt conveyor or a screw conveyor may be used.

In the embodiment shown in FIG. 1, the glycols G2 recovered as the liquid part after the solid-liquid separation through the first solid-liquid separation device 5 are brought into the neutralization reaction tank 7 by a liquid feeding device (not shown). It is designed to be transported. As the liquid feeding device for that purpose, a general liquid feeding pump such as a centrifugal pump, a propeller pump, or a rotary pump may be used. Then, as a result of the conveyed glycols G2 being neutralized in the neutralization reaction tank 7, heavy metals such as lead, zinc, and copper dissolved in the glycols G2 are typically, for example, their hydroxides. Etc., and precipitates.

Further, in the embodiment shown in FIG. 1, a liquid feeding pipe L1 for transporting the glycols G2 to the supply device 3 is provided. The glycols G2 can be conveyed to the supply device 3 and reused as the glycols G1 through the liquid feed pipe L1. As the liquid feeding device for that purpose, a general liquid feeding pump such as a centrifugal pump, a propeller pump, or a rotary pump may be used. By reusing or repeating glycols G2 as glycols G1, the dissolved concentration of heavy metals such as lead, zinc, and copper in glycols G2 increases, and the recovery efficiency of heavy metals per operation in the subsequent steps is increased. Can be enhanced.

In the embodiment shown in FIG. 1, the neutralization reaction tank 7 is provided with a storage container 71 for the acids a used for neutralization, and a supply device 72 for supplying the acids a to the neutralization reaction tank 7 is attached. The neutralization reaction tank 7 is supplied with an appropriate amount of the acid a. Further, a pH meter 73 is attached to the inside of the neutralization reaction tank 7, and depending on the pH of the glycols G2 measured by the pH meter 73, the acids a are supplied to the neutralization reaction tank 7 as needed. The amount can be controlled.

Further, the neutralization reaction tank 7 may be provided with a stirring blade 74 as a stirring device for glycols G2 in the tank. Since the neutralization reaction of glycols G2 is carried out evenly in the entire tank by the stirring blade 74, the neutralization treatment can be carried out more efficiently. As the stirring blade 74, for example, a general screw type or the like may be used.

In the embodiment shown in FIG. 1, the glycols G3 after the neutralization treatment are conveyed to the second solid-liquid separation device 8 by a liquid feeding device (not shown). As the liquid feeding device for that purpose, a general liquid feeding pump such as a centrifugal pump, a propeller pump, or a rotary pump may be used. Then, the conveyed glycols G3 are agglomerates / precipitates containing heavy metals such as lead, zinc, and copper formed in the neutralization reaction tank 7 by the second solid-liquid separation device 8, and waste liquid which is a residual liquid. It is separated into glycols G4. As the second solid-liquid separation device 8, a general filtration device such as a filter press, a pressurized phyllodes filtration device, a screw press, or a belt press may be used.

In the embodiment shown in FIG. 1, the waste glycols G4 recovered as the liquid portion after the solid-liquid separation through the second solid-liquid separation device 8 are conveyed to the relay tank 9 by a liquid feeding device (not shown). It is supposed to be done. As the liquid feeding device for that purpose, a general liquid feeding pump such as a centrifugal pump, a propeller pump, or a rotary pump may be used. Then, for example, when the glycol content of the waste glycols G4 is 20% by mass or more, the glycols G1 supply device is passed through the relay tank 9 and, if necessary, the liquid feed pipe L1. It can be transported to 3 and reused. The glycols G1 may be directly transported from the second solid-liquid separation device 8 to the glycols G1 supply device 3 and reused without passing through the relay tank 9. Alternatively, it may be subjected to a purification treatment before being transported to the supply device 3 to increase the glycol content, and then transported to the supply device 3 of the glycols G1 for reuse. As the method of the purification treatment, for example, a general distillation method or the like may be used.

In addition, the waste glycols G4 can be reused in the cement manufacturing process. For example, one of the uses for reuse is the replacement of cement clinker firing fuel. This utilizes the flammability of the glycols G4. At that time, even if the composition has a water content of about 80% by mass and also contains other components in a complex manner, it can be effectively reused as a substitute for the firing fuel of cement clinker. ..

Furthermore, as another application for the reuse of glycols G4, there is an alternative application of a pulverizing aid in the finishing pulverization step of cement. Usually, for the purpose of improving crushing efficiency, 0.01 to 0.05 parts by mass of a crushing aid such as diethylene glycol is added to 100 parts by mass of the total amount of cement clinker and gypsum in the finishing crushing step of cement. .. As this pulverizing aid, for example, as disclosed in JP-A-2009-78953, a wide range of glycol-containing compositions such as a mixture of ethylene glycol and diethylene glycol can be used. At that time, even if the composition has a water content of about 80% by mass and also contains other components in a complex manner, it can be effectively reused as a substitute for a pulverizing aid in the finishing pulverization step of cement. Is possible.

In the embodiment shown in FIG. 1, a liquid feeding pipe L2 for transporting the glycols G4 to the cement manufacturing facility is provided. That is, the glycols G4 are transported to a facility where a cement manufacturing process such as a clinker firing process is performed through the liquid feeding pipe L2. As the liquid feeding device for that purpose, a general liquid feeding pump such as a centrifugal pump, a propeller pump, or a rotary pump may be used.

As described above, in the conventional heavy metal recovery treatment from incineration ash using mineral acid or the like, it has been necessary to optimize a large amount of post-treatment effluent generated in the process, whereas in the present invention, Since glycol is used as the solvent for the heavy metal recovery treatment, the entire amount of the post-treatment effluent (waste glycol) after the heavy metal recovery treatment can be effectively used in the cement manufacturing process, if necessary. Therefore, it is possible to omit, or at least save labor, the work of optimizing the large amount of post-treatment effluent generated in the heavy metal recovery process so as to meet the wastewater standard, which has been indispensable as a complicated work in the past. it can.

The heavy metal obtained by the present invention is very useful as a heavy metal raw material used for various purposes. The recovered heavy metal is typically in the form of, for example, a hydroxide thereof, or may contain components other than the target heavy metal in a complex manner. Therefore, this may be added as necessary. Further, of course, it may be subjected to treatments such as washing, sorting and refining to obtain a refined raw material.

Hereinafter, the present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited to these examples.

<Test Example 1>
The test was performed by the processing system 1 described above. Specifically, the test was conducted as follows.

The incineration ash A1 is from a waste incineration facility in which the amount of PbO in fluorescent X-ray analysis (based on dry mass) is 0.19% by mass, the amount of ZnO is 1.26% by mass, and the amount of CuO is 0.10% by mass. The incinerated ash of No. 1 was prepared and used by subjecting it to pulverization and classification after removing foreign substances and passing through a 500 μm sieve, and ethylene glycol was used as the glycols G1.

After stirring the produced slurry S for 60 minutes under each condition of the solvent composition, temperature, pH, and mass ratio of solvent / incineration ash shown in Table 1 below, a filter press was used as the first solid-liquid separation device 5. Solid-liquid separation was performed, and glycols G2 were recovered as the liquid part, and incineration ash A2 was recovered as the solid part.

The pH of the obtained glycols G2 was adjusted to pH 9 using nitric acid as a neutralizing agent, and the neutralization treatment was carried out under the respective conditions of the predetermined temperature and the predetermined time shown in Table 1 below to obtain aggregates and precipitates. After obtaining the generated glycols G3, the glycols G3 are solid-liquid separated using a filter press as the second solid-liquid separator 8, and waste glycols G4 is used as the liquid part and heavy metal is used as the solid part. Each of the agglomerates and precipitates contained was collected.

The incineration ash A2 obtained above was subjected to fluorescent X-ray analysis after the drying treatment to confirm the contents of lead, zinc and copper. Separately, with respect to the waste glycols G4 obtained above, lead, zinc and copper dissolved in the waste glycols G4 were analyzed by using ICP emission spectroscopy. As a result, in all the samples, only a very small amount of lead, zinc and copper was detected in the waste glycols G4, and lead and zinc dissolved in the glycols G2 by the neutralization treatment and the subsequent solid-liquid separation. And it was judged that almost all of the copper could be recovered. That is, the difference between the incineration ash A1 and the incineration ash A2 could be regarded as the amount of lead, zinc, and copper recovered. The results are shown in Table 2.

As shown in Table 2, in Examples 1 and 2 in which 100% ethylene glycol was used as the solvent for slurrying, the recovery rates of lead, zinc or copper all exceeded 50%, and 50% ethylene glycol was used. In Example 3 as well, a recovery rate of at least 45% or more was obtained, and in Examples 4 and 5 using 20% ethylene glycol, a recovery rate of at least 30% or more was obtained. This recovery rate was significantly superior to that of Comparative Example 1 in which water was used as the solvent, especially in copper and zinc. It is considered that this is because lead, zinc or copper contained in the incineration ash in a form insoluble in water could be eluted more efficiently by using a solvent containing at least glycol. It was.
Further, from the comparison of Examples 4 and 5, the elution effect of lead, zinc or copper from the incineration ash is better as the pH is higher, and further, from the comparison of Examples 1 and 2, the effect of the pH is glycol. It became clear that it can be replaced by increasing the amount used. Therefore, it is considered that the amount of glycol used can be optimized by adjusting the pH of the slurry according to the amount of glycol that can be used or the amount of glycol that can be processed in the cement manufacturing process. It was.

1 Heavy metal recovery processing system for incinerated ash 2 Supply device for incineration ash A1 3 Supply device for glycols G1 4 Mixing and stirring device 5 First solid-liquid separation device 6 Conveyor device 7 Neutralization reaction tank 8 Second solid-liquid separation device 9 Relay Tank 41 Stirring blade 42 Heating equipment 43 Thermometer 71 Storage container for acids a 72 Supply device for acids a 73 pH meter 74 Stirring blade A1 Incineration ash (before heavy metal recovery treatment)
A2 Incineration ash (after heavy metal recovery treatment)
G1 glycols (solvent)
G2 glycols (dissolved heavy metals)
G3 glycols (containing heavy metal deposits)
G4 waste glycols (after separation of heavy metal deposits)
S Slurry L1 Liquid supply pipe (for liquid supply to supply device 3)
L2 liquid supply pipe (for liquid supply to cement manufacturing equipment)

Claims (7)

Slurry process by adding glycol to incineration ash to make a slurry,
An elution step in which the slurry is stirred to elute heavy metals contained in incineration ash, and
A solid-liquid separation step of solid-liquid separation of the slurry in which the heavy metal is eluted, and
A neutralization step of neutralizing the liquid portion after the solid-liquid separation to form an agglomerate / precipitate containing the heavy metal.
It is provided with a recovery step of recovering the agglomerate / precipitate by solid-liquid separation .
As a source of the glycol, the heavy metal recovery method of the ash content of the glycol is characterized in that there use a glycol-containing composition is at least 20 mass%. In the method for recovering heavy metals from incineration ash according to claim 1.
A method for recovering heavy metals from incineration ash, wherein the glycol is at least one selected from the group consisting of ethylene glycol, propylene glycol and diethylene glycol. In the method for recovering heavy metals from incineration ash according to claim 1 or 2 .
The incineration ash obtained by eluting the heavy metal recovered as the solid part is further provided with a step of recovering the solid part after the solid-liquid separation in the solid-liquid separation step, and is used as a cement raw material in the cement manufacturing process. A method for recovering heavy metals from incineration ash, which is characterized by being present. In the method for recovering heavy metals from incineration ash according to any one of claims 1 to 3 .
A step of recovering the liquid part after solid-liquid separation in the recovery step is further provided, and the used glycol recovered as the liquid part is to be used in the cement manufacturing process as a substitute for fuel or a pulverizing aid. A method for recovering heavy metals from incineration ash. In the method for recovering heavy metals from incineration ash according to any one of claims 1 to 4 .
A method for recovering heavy metals from incinerated ash, wherein the pH of the slurry in the elution step is 10 or more and 13 or less. A mixing and stirring device that stirs a slurry containing incineration ash and glycol to elute heavy metals from the incineration ash.
The first solid-liquid separation device that solid-liquid separates the slurry containing incineration ash after elution of heavy metals,
A neutralization reaction tank that neutralizes the liquid portion recovered through the first solid-liquid separator to form an agglomerate / precipitate containing the heavy metal.
A second solid-liquid separation device that solid-liquid separates the neutralized liquid portion containing the agglomerates / precipitates .
A heavy metal recovery treatment system for incinerated ash, which comprises a storage tank for storing after-use glycol recovered as a liquid portion thereof through the second solid-liquid separation device . In the heavy metal recovery processing system for incinerated ash according to claim 6 .
A heavy metal recovery processing system for incinerated ash, which further comprises a transport device for transporting incineration ash in which heavy metals are eluted, which has been recovered as a solid portion thereof through the first solid-liquid separation device, to a cement manufacturing facility. ..