JP3415065B2 - Method for producing desalted solidified waste incineration ash - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to municipal waste, industrial waste, and RDF (Refuse Derived Fue).
desalination of waste incineration ash and / or waste incineration fly ash (hereinafter collectively referred to as "waste incineration ash" or "incineration ash") generated when incinerating waste such as l, solid waste fuel) (Dechlorinated product) The present invention relates to a method for producing a solidified product.

[0002]

2. Description of the Related Art Incinerated ash contains heavy metals such as Pb and Cd, and inorganic chlorides (hereinafter, chlorides) mainly composed of alkali metal and alkaline earth metal chlorides such as calcium chloride, potassium chloride and sodium chloride. Many are included. In particular, incineration fly ash contains a lot of heavy metals and chlorides,
Due to this heavy metal, direct landfill disposal is not possible, and as specially controlled general waste, melting and solidification, cement solidification, chemical (chelate) treatment, as treatment to suppress elution of heavy metals,
Although an intermediate treatment by either solvent extraction is obligatory, no special treatment for elution is performed for chlorides because there is no regulation value based on landfill standards.

Among these treatments, most of the chlorides in the melting treatment go to the molten fly ash side, so the chlorides are hardly contained in the slag, which is the object of effective use, and the elution is also eliminated, but the equipment cost and many Energy is needed. In addition, various methods for producing a solidified body using a hydrothermal reaction have been proposed in order to effectively utilize the incinerated ash, but these are focused on the development of strength and the stabilization of heavy metals. The elution of chloride at this time is not considered. Further, as disclosed in JP-A-55-134687, a method of washing incinerated ash with water or the like before solidification and solidifying in the presence of a calcium component through a dehydration step is also conceivable. 1) The components necessary for solidification in ash are also eluted in the wash water. (2) Since heavy metals are not stabilized, heavy metals may be eluted in large amounts. (3) A device for dehydrating ash is required. There are problems such as.

[0004]

As described above, the incinerated ash contains a large amount of chloride, and when this ash is solidified by utilizing the hydrothermal reaction, most of the chloride is It exists in the solidified body. Therefore, when the solidified body is effectively used as it is as a civil engineering material, chloride may be eluted from the solidified body by rainwater or the like, which may cause salt damage to nearby soil. The present invention has been made in view of the above points,
The object of the present invention is to add an alkaline agent such as slaked lime or cement as an additive to the incinerated ash, a substance containing silica or alumina, for example, silica fume, clay, dredged sludge, etc. After manufacturing, the solidified body is dechlorinated (dechlorinated) with water by immersing the solidified body in water for a certain period of time to obtain a solidified body without elution of heavy metals and chlorides. An object of the present invention is to provide a method for producing a desalted and solidified waste incineration ash that can effectively utilize the desalted and solidified body.

[0005]

In order to achieve the above object, the method for producing a waste incineration ash desalted and solidified product of the present invention comprises:
Waste incineration ash was added to <br/> Substance containing an alkali agent and silica or alumina as an additive, by using the hydrothermal solidification reactions, or solid material in contact with the washing water to disintegrate, in the wash water After forming a solidified body with a compressive strength of 50 kgf / cm ² or more so that the heavy metal does not elute, the solidified body is brought into contact with water to dissolve the chloride in the solidified body and remove it to remove heavy metal and It is configured to be a desalted and solidified body in which chloride is not eluted.

In the method of the present invention, as described above, the additive and an appropriate amount of water are added to the incinerated ash, and the mixture is kneaded to produce a solidified body by utilizing hydrothermal reaction, and the strength required for effective utilization is expressed. After stabilizing the solid metal and heavy metals, the solidified body and water (hereinafter referred to as desalination washing water or washing water may be referred to as desalination washing water for a certain period of time in order to elute and remove chloride in the solidified body by elution into water. ) Contact. In this way, the solidified body obtained by elution of chloride to a certain value or less is effectively used as a civil engineering material or the like. At this time, since harmful substances such as heavy metals other than chlorides are not eluted in the wash water, the treatment is easy. When carrying out the method of the present invention, if the strength of the solidified product is insufficient, the solidified product may collapse during contact with the wash water, or a large amount of heavy metals may be eluted in the wash water. ,
The compressive strength of the solidified body before contact with water is at least 50
It is necessary that the pressure is at least kgf / cm ² , preferably at least 100 kgf / cm ² .

In the above method, at least one of slaked lime, quick lime, limestone, gypsum, steel slag and cement is used as the alkaline agent. Further, as the substance containing silica or alumina, silica fume,
At least one of clay, coal ash, silica sand, slag, and dredging sludge is used.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and can be appropriately modified and implemented. FIG. 1 shows an apparatus for carrying out a method for producing a waste incineration ash desalted and solidified body according to a first embodiment of the present invention. This apparatus includes a solidified body manufacturing apparatus 10 for kneading and curing waste incineration ash, an alkaline agent and at least one additive of a substance containing silica or alumina, and water to form a solidified body, and a solidified body manufacturing apparatus. A cleaning tank 12 for contacting the solidified body obtained by the apparatus 10 with water to dissolve chloride in the solidified body in water, and water in which chloride is dissolved is extracted from the cleaning tank 12 to obtain clean water and chloride. And a wastewater treatment device 14 for separating into 16 is a solidified body. Examples of the discharge treatment device 14 include a device using an ion exchange membrane, a distillation device using waste heat from an incinerator, and the like. The wash water from the discharge treatment device 14 is either recycled or discharged. It is also possible to discharge the waste water from the cleaning tank 12 without providing the discharge processing device 14.

FIG. 2 shows a solidified body manufacturing apparatus 10 in FIG.
Shows the manufacturing process in. Waste incineration ash, an alkali agent, a substance containing silica and alumina, and water are supplied to a kneader and kneaded. These may be supplied to the kneading machine separately, or may be supplied to the kneading machine in a state where two or more kinds are mixed in advance. The kneaded product is introduced into a molding machine (for example, a mold molding machine) to be molded, then pre-cured in a pre-curing chamber, and then demolded. The demolded pre-cured organism is steam-cured in the main curing room to become a solidified body. Further, the solidified body may be crushed by a crusher to form a crushed stone-like solidified body. A solidified body manufacturing apparatus (hydrothermal solidification reaction apparatus) is constituted by these series of apparatuses. It should be noted that it is possible to omit the molding step and the demolding step, omit the pre-curing step, add a granulation step, a pressure molding step, or the like. By curing the kneaded product, ettringite (3CaO.Al ₂ O ₃ 3CaSO ₄ .3) is formed by hydration solidification reaction (hydrothermal solidification reaction).
2H ₂ O), C—S—H (calcium silicate hydrate), etc. are generated and solidified to be a solidified body by a hydration reaction (hydrothermal reaction). Then, it is crushed if necessary. The obtained solidified body is stable and has high strength, and since it is a desalted solidified body without elution of heavy metals and chlorides, it can be effectively used as a civil engineering material such as a roadbed material or a construction material. it can.

FIG. 3 shows an apparatus for carrying out the method for producing a waste incineration ash desalted and solidified product according to the second embodiment of the present invention. The present embodiment is configured to use rainwater as cleaning water. Other configurations and operations are similar to those of the first embodiment.

[0011]

EXAMPLES Examples and comparative examples will be shown below to further clarify the features of the present invention. Example 1 and Comparative Example 1 Tests were carried out using RDF incineration fly ash having the composition shown in Table 1.

[0012]

[Table 1]

The solidified bodies (solidified bodies 1 and 2) used in the test were manufactured according to the flow shown in FIG. Note that slaked lime was used as the alkaline agent, and silica fume was used as the substance containing silica and alumina. Table 2 shows the properties of the solidified bodies 1 and 2.
In the test, 100 g of the granular solidified body whose particle size was adjusted to 9.5 to 16.0 mm was put in the glass column 20 of the column test apparatus shown in FIG. 5 and immersed in 250 ml of water of pH 4 (adjusted with nitric acid). . This is done at room temperature for a certain period (in this case 2
After elution was carried out by standing still, the eluate was extracted, 250 ml of water having a new predetermined pH (pH 4) was further added, and the same operation was repeated 6 times in total. In FIG. 5, 22 is a solidified body, 24 is water, and 26 is a membrane filter (0.45 μm).
m). The reason for adjusting the pH to 4 is that it is assumed that rainwater will be used.

[0014]

[Table 2]

Table 3 shows the properties of the solidified bodies 1 and 2 before and after the immersion.
Table 4 shows the properties of the wash water. Further, FIG. 6 shows the relationship between the amount of water and the amount of heavy metal eluted when the solidified body 1 is washed.
Fig. 8 shows the relationship between the amount of water when the solidified body 1 was washed and the elution amount of Cl, etc., Fig. 8 shows the relationship between the amount of water when the solidified body 2 was washed and the elution amount of heavy metals, and Fig. 9 shows the solidified body 2 The relationship between the amount of water and the amount of Cl and the like eluted when washed is shown.

[0016]

[Table 3]

[0017]

[Table 4]

From Table 3, it can be seen that the weight of both solidified bodies is reduced by washing, but the elution of chloride is the main factor from the elemental composition. Further, the higher the initial compression strength, the less the collapse of the solidified body due to washing, and the lowering of the strength due to washing was not observed. From Table 4 showing the properties of the wash water and Figs. 6 to 9, the chloride elution was remarkable at the initial stage, and it was sharply reduced each time the wash water was changed.
It decreases to less than 00 mg / l (500 ppm), and the higher the initial compressive strength of the solidified body, the lower the chlorine concentration.
The elution of d) did not show any significant change with the initial properties.

From the above, the performance (strength, strength, etc.) of the solidified body can be obtained by using the method of the present invention for the appropriately manufactured solidified body.
It is possible to remove chloride only while maintaining the suppression of heavy metal elution, and to obtain a solidified product without chloride elution. In addition, harmful heavy metals other than chloride are eluted in the cleaning liquid. Since it does not occur, the treatment of washing water is easy. The water used as washing water is not particularly limited, such as general tap water, industrial water, and rainwater.

[0020]

Since the present invention is configured as described above, it has the following effects. (1) After the solidified body is formed by utilizing the hydrothermal solidification reaction, desalting treatment is performed by bringing it into contact with water, so that the strength of the solidified body does not decrease and the desalination is performed without elution of heavy metals into the wash water. Therefore, the cleaning wastewater can be easily treated. (2) Since there is no chloride elution from the solidified body, when this solidified body is effectively used as a civil engineering material, there is no risk of causing salt damage to the soil in the vicinity, and as a result, the effective use range is greatly increased. Spread to.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an apparatus for carrying out a method for producing a waste incineration ash desalted and solidified body according to a first embodiment of the present invention.

FIG. 2 is a process drawing showing a manufacturing process in the solidified body manufacturing apparatus in FIG.

FIG. 3 is a schematic configuration diagram showing an apparatus for carrying out a method for producing a waste incineration ash desalted and solidified body according to a second embodiment of the present invention.

FIG. 4 is a process drawing showing a method for producing a solidified waste incineration ash in Examples and Comparative Examples.

FIG. 5 is an elevational explanatory view of a column test apparatus used in Examples.

FIG. 6 is a graph showing the relationship between the amount of water and the amount of heavy metal eluted when the solidified body 1 is washed.

FIG. 7 is a graph showing the relationship between the amount of water and the amount of Cl and the like eluted when the solidified body 1 is washed.

FIG. 8 is a graph showing the relationship between the amount of water and the amount of heavy metal eluted when the solidified body 2 is washed.

FIG. 9 is a graph showing the relationship between the amount of water and the amount of Cl and the like eluted when the solidified body 2 is washed.

[Explanation of symbols]

10 Solidified body manufacturing equipment 12 washing tank 14 Wastewater treatment equipment 16,22 Solidified 20 glass columns 24 water 26 Membrane Filter

Continuation of front page (56) Reference JP-A-7-155724 (JP, A) JP-A-9-94548 (JP, A) JP-A-10-99816 (JP, A) JP-A-9-271752 (JP , A) JP-A-10-28950 (JP, A) Actual development 2-1292 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B09B 3/00 301-304 C04B 7 / 24-7/28 C04B 18/06-18/08

Claims (3)

(57) [Claims] 1. A added quality ones containing an alkali agent and silica or alumina in waste incineration ash as an additive, by using the hydrothermal solidification reaction, or collapse solidified body in contact with the wash water, the wash water Compressive strength is 50kgf / c so that heavy metals do not elute
After forming a solidified body of m ² or more, the solidified body is brought into contact with water to dissolve the chloride in the solidified body and remove it to obtain a desalted solidified body that retains strength and does not elute heavy metals and chlorides. A method for producing a waste incineration ash desalination solidified product, which is characterized by the above. Wherein the alkali agent is slaked lime, quick lime, limestone, gypsum, manufacturing method of waste incineration ash desalted solidified body according to claim 1, wherein at least one of steel slag and cement. 3. A material containing silica and alumina, the production of silica fume, clay, coal ash, silica sand, slag and at least either of dredging sludge claim 1 or 2 waste incineration ash desalted solidified body according Method.