JP2001129509A - Heavy metal elution preventive agent and method for treating heavy metal-containing waste using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heavy metal elution preventive agent for effectively and stably fixing heavy metals in a heavy metal-containing waste and preventing elution of the heavy metals, and a method for treating the heavy metal- containing waste using the same. SOLUTION: 1) A heavy metal elution preventive agent comprises sulfer A, alkali metal compound B and water C; 2) a heavy metal elution preventive agent comprises a reaction mixture of the sulfur A with the alkali metal compound B and the water C; 3) a heavy metal elution preventive agent is a reaction mixture of the sulfur A with the alkali metal compound and having 0.2-2.5 in the mol ratio of the component B to the component A; and 4) a method for treating a heavy metal-containing waste comprises the steps of adding the heavy metal elution preventive agent to the heavy metal-contained waste, adjusting the water content and them kneading the same as occasion demands.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a heavy metal elution inhibitor and a method for treating heavy metal-containing waste using the same.
More specifically, the present invention relates to a heavy metal eluting agent capable of efficiently and stably immobilizing heavy metals such as lead, cadmium, and chromium in heavy metal-containing waste, and a method for treating heavy metal-containing waste using the same.

[0002]

2. Description of the Related Art In recent years, as garbage and waste generated from cities and factories have increased remarkably, heavy metals are contained in incinerated ash and fly ash discharged by incineration of these wastes. In terms of environmental measures, safe detoxification of incinerated ash and fly ash is desired.

[0003] As a treatment method, there has been proposed a method of sulfurizing heavy metals with a sulfurizing agent such as sodium sulfide to prevent elution. For example, JP-A-53-39262, JP-A-55-1830, and JP-A-59-730.
No. 91 discloses that heavy metals such as lead and cadmium in incineration ash are insolubilized by mixing and kneading water-soluble sulfides such as sodium sulfide and calcium sulfide with incinerator ash discharged from a general incinerator. A treatment method for detoxification is disclosed. However, although the reason is not always clear, elution prevention by alkali metal sulfide such as sodium sulfide is not sufficient. For example, it is generally known that in the case of insolubilization of mercury or the like by sulfurization, if potassium sulfide is present in excess, mercury polysulfide is generated and redissolved. JP-A-2-203981 discloses a method of adding a polymer containing an organic carboxylic acid as a method for improving sulfuration with an alkali metal sulfide, and JP-A-9-248540 discloses a method of adding a porous inorganic adsorbent. Although the addition method is disclosed, all of them require a new additive, which is economical and goes against the reduction of the processed material.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made from the above viewpoints, and has a heavy metal elution inhibitor capable of efficiently and stably immobilizing heavy metals in heavy metal-containing waste and preventing elution of heavy metals. It is an object of the present invention to provide a method for treating heavy metal-containing waste using the same.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that those containing a mixture or reaction mixture of (A) sulfur and (B) an alkali metal compound are effective as heavy metal elution inhibitors. It has been found that the present invention has been completed.

That is, the gist of the present invention is as follows. 1. A heavy metal elution inhibitor comprising (A) sulfur, (B) an alkali metal compound, and (C) water. 2. A heavy metal elution inhibitor comprising (A) a reaction mixture of sulfur and (B) an alkali metal compound, and (C) water. 3. The molar ratio of the component (B) to the component (A) is 0.2 to
3. The heavy metal elution inhibitor according to the above 1 or 2, which is 2.5. 4. A heavy metal elution inhibitor comprising a reaction mixture of (A) sulfur and (B) an alkali metal compound, wherein the molar ratio of component (B) to component (A) is 0.2 to 2.5. . 5. A method for treating heavy metal-containing waste, comprising adding the heavy metal elution inhibitor according to any one of the above 1 to 4 to the heavy metal-containing waste, adjusting the water content as necessary, and kneading the mixture.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The first invention of the present application is a heavy metal elution inhibitor comprising (A) sulfur, (B) an alkali metal compound, and (C) water.

First, there is no particular limitation on the sulfur of the component (A).
Examples include those produced by desulfurization of natural gas and petroleum fractions. It is not necessary to use a particularly high sulfur purity.

Next, the alkali metal compound as the component (B)
Is particularly limited as long as it is a compound containing an alkali metal.
No, alkali metal oxides, hydroxides, carbonates, etc.
Can be mentioned. Specifically, NaOH, Na
_TwoO, Na_TwoCO_Three, KOH, K _TwoO and others
Can be used alone or in combination of two or more
Wear. Of these, NaOH and KOH are preferred. Arca
There is no particular limitation on the form of use of the remetal compound.
Any of liquid, powder, and granules can be used.

There is no particular limitation on the water used as the component (C), and river water, tap water, and distilled water can be used. here,
The molar ratio of the component (B) to the component (A) is from 0.2 to
2.5 is preferable, and more preferably 0.5-2.
It is in the range of 0. When it is larger than 2.5, when used for treating heavy metal-containing waste, the effect of immobilizing heavy metals may not be sufficient. When it is smaller than 0.2, excess sulfur may adversely affect the treated material. There is no particular limitation on the water component (C). By kneading appropriate amounts of the components (A), (B) and (C) at room temperature, the heavy metal elution inhibitor of the present invention can be obtained.

[0011] The second invention of the present application relates to (A) sulfur and (B)
It is a heavy metal elution inhibitor comprising a reaction mixture with an alkali metal compound and (C) water. (A), (B), (C)
The contents and amounts of the components are the same as in the first invention.
There are two methods for its production. In the first method, an appropriate amount of the components (A), (B) and (C) is placed in an autoclave at a temperature of preferably 50 to 170 ° C (more preferably 60 to 150 ° C), usually for 1 to 60 minutes. In this method, a reaction mixture is obtained by reacting. If the reaction temperature is lower than 50 ° C., the sulfurization reaction of the alkali metal compound may be extremely slow. If the reaction time is less than 1 minute, the sulfurization reaction of the alkali metal compound may not proceed, and if it exceeds 60 minutes, no further reaction can be expected. The reaction mixture contains several kinds of sodium sulfide compounds represented by Na ₂ S _x (x is 1 to 5) and Na ₂ S
It is a mixture of ₂ O ₃ , Na ₂ SO ₃ and the raw material components (A) and (B), the composition of which depends on the reaction conditions. As for the charged amount, as in the first invention, the molar ratio of the component (B) to the component (A) is preferably in the range of 0.2 to 2.5. If it is less than 0.2, the sulfurizing ability per unit weight of sulfur may decrease. If it exceeds 2.5, the alkali metal compound of the component (B) may remain, which is not economical. The mixture consisting of the reaction mixture and water produced by the above reaction is cooled by means such as cooling, air cooling, or water cooling and used as a heavy metal elution inhibitor.

In the second method, an appropriate amount of the components (A) and (B) is added in an autoclave, preferably at 50 to 170 ° C.
(More preferably 60 to 150 ° C.), usually 1 to
In this method, a reaction mixture is obtained by reacting for 60 minutes, and an appropriate amount of water is added thereto and kneaded. Regarding the charged amount,
Just do not put water in the other conditions, the reason is the same.

The third invention of the present application relates to (A) sulfur and (B)
A heavy metal elution inhibitor comprising a reaction mixture with an alkali metal compound, wherein the molar ratio of the component (B) to the component (A) is 0.2 to 2.5. This is the same as the reaction mixture of the second method of the second invention, except that water is not added, and other conditions are the same.

In particular, it is essential that the molar ratio of the component (B) to the component (A) is 0.2 to 2.5. 0.2
By weight, it may sulfide capacity per unit weight of sulfur is reduced, and when it exceeds 2.5, Na ₂ as a sulfide
S is mainly contained, and the amount of sodium polysulfide of x = 2 or more in Na ₂ S _x is small.
It is not economical because the alkali metal compound of the component may remain.

The fourth invention of the present application is a method for treating heavy metal-containing waste, comprising adding the above-mentioned heavy metal elution inhibitor to heavy metal-containing waste, adjusting the water content as necessary, and kneading the mixture. . First, the heavy metal-containing waste to be treated in the present invention refers to waste incineration ash, fly ash, sludge, slag, lime (fly ash) containing heavy metals such as chromium, copper, cadmium, mercury, and lead. And waste such as sludge.

With respect to the heavy metal elution inhibitor of the first invention, the heavy metal-containing waste and the heavy metal elution inhibitor containing the component (B) in an equimolar amount or more of the amount of the heavy metal are mixed in an autoclave or the like, and then mixed. Alternatively, after adjusting the water content by further adding water, the reaction is preferably carried out at a temperature of 50 to 170 ° C., usually for 1 to 60 minutes.

In the second and third inventions, the heavy metal elution preventing agent is mixed with a heavy metal containing waste and a heavy metal elution preventing agent containing the component (B) in an amount equal to or more than the equimolar amount of the heavy metal in a container or the like. As it is or after adding water to adjust the water content, the reaction is carried out at room temperature for usually 1 to 60 minutes.

It should be noted that the above-mentioned adjustment of the water content may be carried out in such an amount that the heavy metal-containing waste is sufficiently wetted. The heavy metal-containing waste treated as described above is fixed with heavy metal, passes the landfill standard, and can be used for landfill as it is.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the invention thereto. Examples 1 to 11, Comparative Examples 1 to 9 and Reference Examples 1 and 2 [Example 1] In a separable flask having an internal volume of 500 ml, 48 g of sulfur (reagent first grade) powder, caustic soda 7
After adding 2 g, the mixture was heated to 100 ° C. in an oil bath while kneading. At this stage, the sample was in a brown, opaque, flowing state. After the reaction for 10 minutes, the mixture was allowed to cool, and the obtained solid was pulverized to a size of 0.5 to 5 mm to obtain a dissolution inhibitor A. Next, 30 g of fly ash A (at a water content of 0.1% by weight or less, the same applies hereinafter), 13 g of water, and 8 g of a dissolution inhibitor A were added to a Labo Plastomill at room temperature, and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of the obtained powder was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate was 0.2 mg / liter, which was lower than the landfill standard (0.3 mg / liter).

Example 2 At room temperature, 30 g of fly ash A, 14 g of water and 1 g of the dissolution inhibitor A of Example 1 were added to a Labo Plastomill at room temperature.
2 g was added and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of water obtained by adjusting 30 g of the obtained powder to pH 6.0.
In addition to 0 ml, the mixture was shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate was 0.05 mg / liter or less.

Example 3 At room temperature, 30 g of fly ash A, 15 g of water and 2 g of anti-elution agent A of Example 1 were put in a Labo Plastomill.
4 g was added and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of water obtained by adjusting 30 g of the obtained powder to pH 6.0.
In addition to 0 ml, the mixture was shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate was 0.05 mg / liter or less.

Example 4 8 of dissolution inhibitor A of Example 1
g was dissolved in 13 g of water to prepare 21 g of a liquid treating agent. At room temperature, 21 g of the previously prepared liquid treating agent was added to 30 g of fly ash A in a Labo Plastomill and kneaded for 10 minutes. After kneading, the solidified body obtained by allowing to stand at room temperature for one week is 0.5 to 5 m
m. 30 g of the obtained powder was adjusted to pH 6.
The mixture was added to 300 ml of water adjusted to 0, and shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate was 0.05 mg / liter, which was below the landfill standard.

Example 5 32 g of sulfur (reagent first grade) powder was placed in a separable flask having an internal volume of 500 ml.
80 g of caustic soda was added, and the mixture was heated to 100 ° C. in an oil bath while kneading. At this stage, the sample became a reddish brown and opaque fluid state. After the reaction for 10 minutes, the mixture was allowed to cool, and the obtained solid was pulverized to a size of 0.5 to 5 mm to obtain a dissolution inhibitor B. Next, fly ash A was added to Labo Plastomill at room temperature.
30 g, 13 g of water and 8 g of the dissolution inhibitor B were added and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. The obtained powder 3
0 g was added to 300 ml of water adjusted to pH 6.0, and the mixture was shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate is
It was less than 0.05 weight mg / liter.

Example 6 At room temperature, 30 g of fly ash A, 14 g of water, and 12 g of anti-elution agent B were added to Labo Plastomill.
Kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of the obtained powder was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. afterwards,
The contents were filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate was 0.05 mg / liter or less.

Example 7 A separable flask having an internal volume of 500 ml was charged with 64 g of sulfur (reagent first grade) powder.
40 g of caustic soda was added, and the mixture was heated to 100 ° C. in an oil bath while kneading. After the reaction for 10 minutes, the mixture was allowed to cool, and the obtained solid was pulverized to a size of 0.5 to 5 mm to obtain a dissolution inhibitor C. Next, fly ash A3 was added to Labo Plastomill at room temperature.
0 g, 13 g of water and 8 g of the dissolution inhibitor C were added and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. The obtained powder 30
g was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate is
It was less than 0.05 mg / liter.

Example 8 30 g of fly ash A, 15 g of water and 24 g of an anti-elution agent C were added to Labo Plastomill at room temperature.
Kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of the obtained powder was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. afterwards,
The contents were filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate was 0.05 mg / liter or less.

Example 9 At room temperature, 30 g of fly ash B (water content 0.1% by weight or less, the same applies hereinafter) was added to a Labo Plastomill at room temperature.
13 g of water and 6 g of anti-elution agent A were added and kneaded for 10 minutes. After kneading, the mixture was allowed to stand at room temperature for one week, and
It was pulverized to a size of 5 to 5 mm. 30 g of the obtained powder was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the P contained in the filtrate was removed.
The concentration of b was measured. The concentration of Pb in the filtrate is 0.05
mg / liter or less.

Example 10 At room temperature, 30 g of fly ash B, 14 g of water and 12 g of anti-elution agent A were added to a Labo Plastomill and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of the obtained powder was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. After that, the contents were filtered through a 1 micron glass filter,
The concentration of Pb contained in the filtrate was measured. Pb in filtrate
Was 0.05 mg / liter or less.

Example 11 A 500 ml autoclave was charged with 16 g of sulfur (reagent first grade) powder, 20 g of caustic soda and 64 g of water, and heated to 100 ° C. After the reaction for 20 minutes, the mixture was allowed to cool to room temperature to obtain a brown liquid. Next, at room temperature, 30 g of fly ash B was added to Labo Plastomill.
Then, 25 g of the reaction solution obtained in the previous reaction was added and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. The obtained powder 3
0 g was added to 300 ml of water adjusted to pH 6.0, and the mixture was shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured. The concentration of Pb in the filtrate is
It was less than 0.05 mg / liter.

[Comparative Example 1] In a separable flask having an internal volume of 500 ml, powder of sulfur (reagent first grade) 32 g was prepared.
120 g of caustic soda was added, and the mixture was heated to 100 ° C. in an oil bath while kneading. At this stage, the sample became a reddish brown and opaque fluid state. It was left to cool after the reaction for 10 minutes.
The obtained solid was pulverized to a size of 0.5 to 5 mm to obtain a dissolution inhibitor D. Next, 30 g of fly ash A, 15 g of water, and 4 g of anti-elution agent D were added to Labo Plastomill at room temperature, and
Kneaded for minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of the obtained powder was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was 370 mg / l.

[Comparative Example 2] The same treatment as in Comparative Example 1 was carried out except that the dissolution inhibitor D was changed to 8 g. The concentration of Pb in the filtrate was 15 mg / liter, which was higher than the landfill standard.

Comparative Example 3 The same treatment as in Comparative Example 1 was carried out except that the amount of the dissolution inhibitor D was changed to 12 g. The concentration of Pb in the filtrate was 5.5 weight mg / liter, which was higher than the landfill standard.

Comparative Example 4 30 g of fly ash A, 15 g of water and a commercially available anhydrous sodium sulfide (Na ₂
S) 4 g was added and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of the obtained powder was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. Thereafter, the content was filtered through a 1-micron glass filter, and the concentration of Pb contained in the filtrate was measured.
The concentration of Pb in the filtrate was 31 mg / liter.

Comparative Example 5 6 g of commercially available anhydrous sodium sulfide
The processing was performed under the same conditions as in Comparative Example 4, except that The concentration of Pb in the filtrate was 5.2 mg / liter, which was higher than the landfill standard.

Comparative Example 6 8 g of commercially available anhydrous sodium sulfide
The processing was performed under the same conditions as in Comparative Example 4, except that The concentration of Pb in the filtrate was 8.3 mg / liter, which was higher than the landfill standard.

Comparative Example 7 Commercially available anhydrous sodium sulfide was
The treatment was carried out under the same conditions as in Comparative Example 4 except that g was used. The concentration of Pb in the filtrate was 4.1 mg / liter, which was higher than the landfill standard.

Comparative Example 8 At room temperature, 30 g of fly ash B, 15 g of water and 2 g of commercially available anhydrous sodium sulfide were added to a Labo Plastomill and kneaded for 10 minutes. After kneading, the solidified body was allowed to stand at room temperature for one week and pulverized to a size of 0.5 to 5 mm. 30 g of the obtained powder was added to 300 ml of water adjusted to pH 6.0, and shaken with a shaker for 6 hours. After that, the contents were filtered through a 1 micron glass filter,
The concentration of Pb contained in the filtrate was measured. Pb in filtrate
Was 5.0 mg / liter.

Comparative Example 9 8 g of commercially available anhydrous sodium sulfide
The processing was performed under the same conditions as in Comparative Example 8, except that The concentration of Pb in the filtrate was 7.0 mg / liter, which was higher than the landfill standard.

Reference Example 1 50 g of alkaline fly ash A (lead content: 4.9% by weight) was taken, 500 ml of water adjusted to pH 6.0 was added, and the mixture was continuously shaken for 6 hours with a shaker. did. Next, the lead concentration in the solution filtered with a 1-micron glass filter paper was measured. That P
The b concentration was 1,200 mg / liter, which was much higher than the landfill standard.

Reference Example 2 Neutral fly ash B (lead content: 3.
8% by weight), and adjusted to pH 6.0 with 5 g of water.
After adding 00 ml, the mixture was continuously shaken with a shaker for 6 hours. Next, the Pb concentration in the solution filtered with a 1-micron glass filter paper was measured. The Pb concentration was 22 mg / liter, which was much higher than the landfill standard. The above is summarized in Table 1.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

According to the present invention, when a heavy metal-containing waste is treated using the heavy metal elution inhibitor of the present invention, the heavy metal is fixed and falls below the landfill standard and can be used for landfill.

Claims (5)

[Claims] 1. A heavy metal elution inhibitor comprising (A) sulfur, (B) an alkali metal compound, and (C) water. 2. A heavy metal elution inhibitor comprising (A) a reaction mixture of sulfur and (B) an alkali metal compound, and (C) water. 3. The heavy metal elution inhibitor according to claim 1, wherein the molar ratio of the component (B) to the component (A) is from 0.2 to 2.5. 4. A reaction mixture of (A) sulfur and (B) an alkali metal compound, wherein the molar ratio of component (B) to component (A) is 0.2 to 2.5. Heavy metal elution inhibitor. 5. A heavy metal-containing waste, characterized in that after adding the heavy metal elution inhibitor according to any one of claims 1 to 4 to the heavy metal-containing waste, the water content is adjusted and kneaded as required. Processing method.