JPH09155319A - Method for processing for making heavy metal-containing incineration ash, etc., and shredder dust pollution-free and manufacture of reuse material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make heavy metal-contg. incineration ash, etc., pollution-free by a method wherein sodium carbonate or potassium carbonate, iron (II) sulfate and cements are compounded with heavy metal-contg. bottom ash and a dust and water is added and the mixture is kneaded and cured. SOLUTION: When heavy metal-contg. incineration ash such as shredder dust incineration ash, sewage sludge incineration ash and industrial waste water treated sludge incineration ash are treated to pollution-free, at least one selected from sodium carbonate and potassium carbonate (a), at least one selected from iron (II) sulfate, aluminum sulfate and aluminum hydroxide (b) and becomes (c) are compounded into the incineration ash and water is added therein and the mixture is kneaded and cured. In this case, the compounding ratios of (a)-(c) are pref. 0.5-1.0wt.% inorg. salt (a), 0.5-1.0wt.% inorg. salt (b) and 15-20wt.% cements (c). In addition, water content during kneading is 25-35wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decontaminating incineration ash containing heavy metals such as shredder dust incineration ash, a method for decontaminating shredder dust and a method for producing a recycled material. .

[0002]

2. Description of the Related Art Electric furnace dust is roughly classified into those containing mainly iron oxides and those containing mainly oxides of iron, zinc, lead, cadmium, etc. There are more If such electric furnace dust is directly landfilled, harmful heavy metal ions will be eluted by rainwater, so it cannot be landfilled.

Therefore, a method has been adopted in which coke powder, which is a reducing substance, is mixed with electric furnace dust, granulated, and incinerated in a rotary kiln or the like to recover volatile zinc and lead. In addition to high treatment costs, zinc, lead, etc., which do not completely volatilize, remain in the residual pellets, so there remains a problem that residual heavy metals are eluted when they are landfilled.

Cement, blast furnace water slag powder, ferrous sulfate and ferrous chloride are added to such electric furnace dust, and the mixture is kneaded to be disposed of in landfill. Viscosity and melting point of molten steel slag are added. It is known that in order to prevent deterioration and elution, dust is bubbled in together with silicate rocks, minerals, kalami, etc. to recover volatile zinc and lead, and the rest is fixed in slag. However, the current situation is that it has hardly been put to practical use.

[0005] Further, the incinerated ash of municipal waste is directly landfilled in mountainous areas, coasts or the like, or a part of it is mixed with cement and mixed with water and then kneaded, and then hardened for landfilling.

Although sewage sludge and industrial wastewater sludge are rapidly increasing with the progress of urbanization and industrialization, they are usually incinerated as they are or mixed with cements, sprinkled after sprinkling and hardened to make them non-polluting, and landfill disposal. Has been done.

Hazardous heavy metal ions and the like are eluted in shredder dust generated when crushing automobile scraps and household electric appliance scraps. Shredder dust is a synthetic resin such as vinyl chloride or polystyrene, rubber,
Despite containing wood chips, batteries, and paints, they were inexpensively landfilled in mountainous areas, coasts, etc. like ordinary harmless waste.

However, although the law was amended to dispose of shredder dust at a controlled disposal site from January 1996, no measures have been taken against harmful heavy metal ions and the like.

[0009]

Conventionally, it was thought that harmful heavy metals would not be eluted from shredder dust, but when heavy metals were measured by the Environmental Agency Notification Method,
It was found that the amount of toxic heavy metals such as Cd, Pb, Zn, Hg and As eluted was more than the regulation value. Therefore, in the conventional landfill disposal, harmful heavy metals are released into the ground, which is extremely dangerous. Therefore, the country is legal by 1996.
Since January 2012, Shredder Dust has issued a policy that it must be disposed of in a managed disposal site, but there is a major problem of lack of a managed disposal site.

Incineration can be considered as a method of disposing of shredder dust. However, shredder dust contains synthetic resins such as vinyl chloride, polyurethane, polystyrene, etc., and combustible materials such as rubber.
It is not preferable to incinerate the shredder dust, because the vinyl chloride gas is burned out and vinyl chloride is combusted and decomposed to generate hydrochloric acid gas, which damages the furnace wall and the heat exchange pipe.

Further, sewage sludge and industrial wastewater sludge also contain heavy metal ions, and have an appropriate amount of heat (about 2000).
Despite having kcal / kg), it is landfilled in a managed landfill site as it is or hardened with cement or the like, but securing landfill sites is still a problem here.

In addition, the amount of municipal waste is increasing in the disposable age and the number of garbage incinerators is increasing.
Synthetic resins such as polyurethane, flammable materials such as rubber, waste batteries, etc. are also incinerated, and harmful heavy metals also increase. Again, securing landfill sites is a problem here.

Similarly, the electric furnace dust contains Cd, Pb, and Zn.
It contains a large amount of heavy metal oxides such as, and even if it is solidified with cements, the effluent regulation value (particularly Pb
Is difficult to clear from 3.0 mg / l to 0.3 mg / l), and prevention of elution of Pb ions having amphoteric properties has been demanded. On the other hand, imported ore products have become cheaper due to the appreciation of the yen, and the method of recovering crude zinc etc. by reduction treatment has become costly and cannot be recovered.

In the conventional cement hardening method, there is a problem that calcium ions in the cement gradually react with CO ₂ in the atmosphere and neutralize to lose alkalinity, and heavy metals are redissolved. . In addition, Pb shows both sexes and the environmental standard becomes strict, and the landfill standard value is 3 mg /
It can be as severe as 1 to 0.3 mg / l, or even 0.1 mg / l. It is becoming difficult to prevent the elution by containing it as a hydroxide.

Furthermore, it will become more difficult to secure landfill sites in the future, and incineration will be carried out to reduce the amount of waste,
There is a demand for a technology of reusing the pollution-free materials for lower layer board materials and backfill materials.

[0016] The problem to be solved by the present invention is to provide a method for making pollutants such as incineration ash containing heavy metals and shredder dust pollution-free, and a method for producing recycled materials thereof.

[0017]

Means for Solving the Problems The present inventor has earnestly studied a method for decontaminating incineration ash containing heavy metals, and found that two or more kinds of inorganic salts are allowed to coexist when the incineration ash is solidified with cement. The inventors have found that the above problems can be solved by this, and have completed the present invention. That is, in the present invention, incineration ash and / or dust containing a heavy metal is selected from (a) at least one selected from sodium carbonate and potassium carbonate, and (b) selected from ferrous sulfate, aluminum sulfate and aluminum hydroxide. At least one and (c) cements are blended, water is added, and the mixture is kneaded and cured, and a pollution-free treatment method for heavy metal-containing incineration ash, shredder dust, (a) sodium carbonate and At least one selected from potassium carbonate, (b) at least one selected from ferrous sulfate, aluminum sulfate and aluminum hydroxide, and (c) cements are blended, and water is added and kneaded to cure. A method for decontaminating shredder dust, which is characterized in that
At least one selected from (a) sodium carbonate and potassium carbonate, and (b) at least one selected from ferrous sulfate, aluminum sulfate, and aluminum hydroxide in incinerated ash and / or dust containing and heavy metals.
The present invention relates to a method for producing a recycled material such as a roadbed material, which comprises mixing seeds and (c) cements, adding water, kneading and curing.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The incineration ash containing heavy metal in the invention according to claim 1 is at least selected from shredder dust incineration ash, sewage sludge incineration ash, municipal waste incineration ash and industrial wastewater treatment sludge incineration ash. It is one kind.
The incinerated ash may be fly ash. Also,
Examples of the dust include electric furnace dust.

The shredder dust in the invention of claim 4 is obtained by crushing scraps such as automobiles and household electric appliances, and is usually crushed to 15 mm or less.

The inorganic salt to be added to the incineration ash or shredder dust containing heavy metals is (a) at least one selected from sodium carbonate and potassium carbonate, and (b)
It is at least one inorganic salt selected from ferrous sulfate, aluminum sulfate and aluminum hydroxide.

Among the inorganic salts added in the present invention,
The carbonate ions of (a) sodium carbonate and potassium carbonate react with heavy metals to form water-insoluble cadmium carbonate and lead carbonate. The potassium ion and sodium ion of the component (a) form a heavy metal hydroxide as an alkali source.

Even if these potassium ions and sodium ions react with carbon dioxide gas in the atmosphere to form potassium carbonate and sodium carbonate again, these compounds are soluble in water and are alkaline, so that the incineration ash is alkaline. It is possible to prevent the elution of heavy metals without losing

Further, the anions such as As and Cr ions react with Fe ^{2+ of} ferrous sulfate and Al ^{3+ of} aluminum sulfate in the component (b) to form hydroxides, and these heavy metals Elution can be prevented.

Further, the cements used in the method of the present invention are used for imparting solidification strength and react with calcium ions to form hydroxides and make them insoluble in water. Be stable in the long term. The cements used in the present invention are not particularly limited, and examples thereof include Portland cement and blast furnace cement.

The blending ratio of (a) to (c) in the present invention is 0.5 to 1.0% by weight of the inorganic salt of (a) and 0.5 to 1.0% by weight of the inorganic salt of (b). %, And the cements of (c) may be blended in an amount of 15 to 20% by weight.

In the method of the present invention, incinerator ash or shredder dust containing heavy metals may be mixed with the components (a) to (c) in the above-mentioned proportions, and water may be added thereto and kneaded to cure. The amount of water is not particularly limited, but may be added so that the water content during kneading is 25 to 35% by weight.

In the present invention, sodium sulfide may be used in combination to adjust the pH of incinerated ash or electric furnace dust to mainly form sulfides and prevent elution.

The incinerated ash or shredder dust which has been rendered pollution-free by the method of the present invention can be roughly crushed by a crusher or the like and reused as a roadbed material or a backfill material. In addition, when it is solidified, it may be poured into a mold to manufacture a roadbed tile.

[0029]

Example 1 Using various incineration ash containing heavy metals shown in Tables 1 and 2, inorganic salts and cement were blended at a blending ratio shown in Table 3, and water was added and kneaded. , Put it in a plastic bag and let it solidify. The hardness was judged by pushing the solidified state after 7 days by hand. Table 3 shows the results.

After kneading, representative ones were aged in a moist air curing box (20 ° C. ± 1 ° C., humidity 65%) for 7 days, 6 months and 12 months, and notified by the Environment Agency (Environment Agency Notification). Thirteen
No. 2) was used to measure the elution amount of heavy metals. The results are shown in Tables 4 and 5.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

As is clear from the results shown in Tables 3 to 5, the cement solidified alone (formulation No. 1 to No. 1)
6) and cemented ferrous sulfate and sodium sulfide in combination (compound No. 7 to 12) were found to increase the elution amount of heavy metals such as lead and cadmium and exceed the regulation value. It was

On the other hand, in the case of using two kinds of inorganic salts of the component (a) and the component (b) as in the present invention, harmful heavy metals such as lead, cadmium and hexavalent chromium do not elute, and are rendered harmless. You can see that it is done.

Example 2 Shredder dust (15 m) having the physical properties shown in Table 2
m or less), various inorganic salts and cement were mixed as shown in Table 6, water was added, and the mixture was kneaded and solidified. The solidified state and the concentration of eluted ions were measured, and the results are shown in Tables 6 to 8.

[0039]

[Table 6]

[0040]

[Table 7]

[0041]

[Table 8]

As is clear from the results shown in Tables 6 to 8, by using shredder dust in combination with two kinds of inorganic salts (a) component and (b) component and solidifying with cement, lead, cadmium and It can be seen that harmful metals such as hexavalent chromium can be prevented from being eluted, and shredder dust can be made pollution-free.

Example 3 Electric furnace dust 825 kg, ferrous sulfate 5 kg, aluminum sulfate 10 kg, sodium carbonate 5 kg, potassium carbonate 5
Kg was put into an Eirich mixer, mixed for 10 minutes, water was added and kneaded for about 5 minutes, then 150 kg of cement was added, kneaded for about 10 minutes, taken out from the mixer and naturally cured. After 7 days, it was coarsely crushed with a jaw crusher, a sample for aggregate test was taken, and its physical properties were examined according to JIS method. Table 9 shows the results.

The kneaded product taken out from the mixer is
The specimen was prepared by packing in an IS form (10 cmφ × 20 cm), and the uniaxial compressive strength was measured. In addition, a heavy metal dissolution test was conducted in accordance with the notification method of the Environment Agency. Table 9 also shows the results.

Example 4 Electric furnace dust 215 kg, shredder dust incineration ash 2
00 kg, sewage sludge incineration ash 200 kg, industrial wastewater sludge incineration ash 200 kg, ferrous sulfate 5 kg, sodium sulfide 10 kg
g, aluminum sulfate 10 kg, sodium carbonate 10 kg, put in an Erich mixer and mix for 10 minutes, add water and knead for about 5 minutes, then add 150 kg of cement,
After kneading for about 10 minutes, the mixture was taken out from the mixer and naturally cured. After 7 days, it was roughly crushed with a jaw crusher and various tests were carried out according to Example 2. Table 9 shows the results.

[0046]

[Table 9]

[0047]

Industrial Applicability According to the present invention, various incineration ash and shredder dust containing harmful heavy metals such as lead, cadmium and hexavalent chromium can be treated to be pollution-free. Since harmful heavy metals are not eluted from the incineration ash and shredder dust treated to be pollution-free according to the present invention, these can be effectively reused as roadbed materials and backfill materials. Further, since the incineration ash and shredder dust that have been rendered pollution-free by the method of the present invention can be backfilled even if they are not managed disposal sites, the disposal sites can be easily secured.

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Claims (5)

[Claims] 1. Incinerator ash and / or dust containing a heavy metal is selected from (a) at least one selected from sodium carbonate and potassium carbonate, and (b) selected from ferrous sulfate, aluminum sulfate and aluminum hydroxide. A method for decontaminating a heavy metal-containing incinerated ash or the like, which comprises blending at least one type of cement and (c) cement, and then kneading the mixture by adding water and curing the mixture. 2. The incineration ash containing heavy metals is at least one selected from shredder dust incineration ash, sewage sludge incineration ash, municipal waste incineration ash, and industrial wastewater treatment sludge incineration ash. Pollution-free treatment method for ash, etc. 3. The pollution-free treatment method for incineration ash containing heavy metals according to claim 1, wherein the dust containing heavy metals is electric furnace dust. 4. Shredder dust, and (a) at least one selected from sodium carbonate and potassium carbonate,
(B) At least one selected from ferrous sulfate, aluminum sulfate and aluminum hydroxide, and (c) cements are blended, and water is added and kneaded to cure the shredder dust. Processing method. 5. The incineration ash and / or dust containing heavy metals is selected from (a) at least one selected from sodium carbonate and potassium carbonate, and (b) selected from ferrous sulfate, aluminum sulfate and aluminum hydroxide. A method for producing a reusable material such as a roadbed material, which comprises blending at least one kind of cement and (c) cement, adding water, kneading and curing.