JPH09314092A - Incinerated ash solidification method, incinerated ash solidified reclaimed material and concrete composition - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method for decontaminating incineration ash such as shredder dust in which aluminum remains. SOLUTION: The incineration ash in which aluminum and / or aluminum alloy remains is treated with an alkaline aqueous solution,
A method for solidifying incinerated ash, which comprises dehydrating aluminum and / or aluminum alloy, then dehydrating, and adding cement to solidify.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of solidifying pollution-free municipal solid waste or incinerated ash of shredder dust, in which aluminum or the like remains, in a pollution-free manner.

[0002]

2. Description of the Related Art As a method for decontaminating incineration ash and fly ash obtained by incinerating municipal waste, etc., the incineration ash and fly ash are mainly composed of cement, with ferrous sulfate, sodium sulfide, etc. A common method is to add water and knead and then solidify. Further, in recent years, a method of adding water and a heavy metal solidifying agent to fly ash and kneading (JP-A-2-6889), a chelating agent and an iron salt are added to a fly ash while adding a pH adjusting agent as necessary. (JP-A-63-278987), a method of making aluminum hydroxide, ferric sulfate, etc. pollution-free by using a heavy metal elution inhibitor and cement together has been proposed.

Further, shredder dust obtained by cutting automobiles and home electric appliances contains harmful metals, synthetic resins such as vinyl chloride and polystyrene, rubber, wood chips, paints, oils, etc., and harmful metals are eluted. Despite this, ordinary harmless waste was easily landfilled in the mountains and coasts as well.

[0004]

However, in the method described in Japanese Patent Application Laid-Open No. 2-6889, lead is often eluted due to insufficient treatment of heavy metals such as lead in fly ash. There is a problem. Even if the treatment of heavy metals such as lead is sufficiently performed, there is a problem that the amount of heavy metal ion fixative used is large and the running cost becomes high.

Further, according to the method disclosed in Japanese Patent Laid-Open No. 63-278589, the fly ash is treated with an iron salt or an acid such as hydrochloric acid as a pH adjusting agent even if the lead ash in the fly ash is sufficiently treated. If added, a violent exothermic reaction will occur, and there is a risk of scattering and causing burns.

Further, since municipal waste and shredder dust contains a large amount of aluminum cans and aluminum alloys, part of aluminum or aluminum alloys is melted into aluminum particles during the incineration process.
It remains in the aluminum ash or in the incinerated ash as aluminum alloy cut pieces. When solidified incineration ash of municipal waste or shredder dust is solidified with cement, aluminum contained in the incinerated ash reacts with calcium in the cement, hydrogen gas is generated, and solidified solids are cracked or expand and collapse. If roadbed materials and sidewalk boards such as interlocking blocks are manufactured using the incinerated ash, they will be destroyed in about 6 months to 1 year and cannot be effectively used. Therefore, municipal waste and shredder dust are incinerated, iron such as steel cans is sorted by a magnetic separator, and non-ferrous metals such as copper, aluminum, and aluminum alloys are removed by a non-ferrous metal sorter (eddy electromagnetic sorter). Are recycled as these raw materials. However, fine aluminum and aluminum alloys cannot be removed by screening, so they remain in the incineration ash and generate hydrogen gas when solidifying with cement, avoiding cracking or expansion collapse of the cement solidified product. I can't.

[0007] Furthermore, due to the revision of the Waste Management Law,
Since April 2004, it was obliged to dispose of shredder dust at a managed landfill site, so measures to prevent elution of harmful heavy metal ions and volume reduction treatment are being considered. In addition, waste incineration fly ash is also solidified with cement, and landfill disposal is also obligatory. Especially, the lead ion elution regulation value is 3 mg / l.
It has been strengthened to 0.3 mg / l, making it difficult to secure a managed landfill.

An object of the present invention is to provide a method for decontaminating incineration ash such as shredder dust in which aluminum or the like remains.

[0009]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors to solve the above problems, as a result of treating the incinerated ash containing aluminum and / or aluminum alloy with an alkaline aqueous solution, the solidified ash is solidified. The inventors have found that there is no occurrence of cracks or swelling and collapse, and have completed the present invention.

That is, according to the present invention, incineration ash in which aluminum and / or aluminum alloy remains is treated with an alkaline aqueous solution to convert aluminum and / or aluminum alloy into hydroxide, which is then dehydrated and cemented to be solidified. The present invention relates to a method for solidifying incinerated ash, which is characterized in that

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Subject to the solidification method of the present invention,
The incineration ash in which aluminum and / or aluminum alloy remains is, for example, incineration ash obtained by incinerating shredder dust or municipal solid waste. More specifically, the incineration residue obtained by incinerating shredder dust and municipal solid waste is sieved to remove iron, aluminum, aluminum alloy, and other large substances, washed with water if necessary, and then subjected to magnetic separation and non-ferrous sorting. It is an incinerated ash from which ferrous and non-ferrous metals have been removed by a machine.

Since fine aluminum and aluminum alloy remain in the incineration ash treated as described above,
If it is solidified with cement as it is, the remaining aluminum or aluminum alloy reacts with calcium in the cement to generate hydrogen gas, which leads to cracking or expansion destruction of the solidified material.

In the present invention, in order to prevent generation of hydrogen gas after solidification of cement, the incinerated ash in which aluminum and / or aluminum alloy remains is treated with an alkaline aqueous solution, and the aluminum and / or aluminum alloy is treated with aluminum hydroxide or the like. It is characterized in that it is a hydroxide. To treat with an alkaline aqueous solution, the above-mentioned pretreated incinerated ash may be added to a previously prepared alkaline aqueous solution, or both the above-mentioned pretreated incinerated ash and alkali may be added to water for treatment. The alkali used for the treatment is not particularly limited, but examples thereof include sodium hydroxide and the like. As the pH of the alkaline aqueous solution, for example, an alkaline aqueous solution having a pH of about 9 to 10 may be used.

The alkaline aqueous solution added with incinerated ash in which aluminum or the like remains may be occasionally stirred for 36 to 48 hours.

It should be noted that the aluminum or the like remaining in the incinerated ash may be treated with an acid such as sulfuric acid or hydrochloric acid and treated with an acid such as sulfuric acid or hydrochloric acid instead of the alkaline aqueous solution to form aluminum sulfate, aluminum chloride or the like. Since it is used, it is necessary to neutralize the acidic solution to make it alkaline and to filter it, which is costly and not preferable.

After completion of the reaction, the product is dehydrated to give a cake.
Fly ash may be added as a water content adjusting agent for the dehydrated cake. Since fly ash is mainly composed of fine aluminum oxide, it does not become a source of hydrogen gas even if it is added to the dehydrated cake and cemented.

Next, a heavy metal ion fixing agent, aggregate, and water are added to the dehydrated cake together with cement, and they are kneaded and solidified.

Examples of the cement used as the solidifying material include ordinary cement, fast cement, fly ash, blast furnace cement, silica cement, and super fast cement, and inexpensive blast furnace cement is preferable.

The heavy metal ion fixing agent is added to prevent elution of heavy metal ions such as lead contained in incinerated ash, and is not particularly limited as long as it can fix heavy metal ions. For example, anionic arsenic In order to fix hexavalent chromium ions, ferrous sulfate, cations of lead, zinc, copper ions and the like can be used, and sodium carbonate, aluminum sulfate, aluminum hydroxide and the like can be used.

The aggregate includes, for example, sand and gravel. As an alternative to these, coarsely crushed products of incombustible waste such as glass, concrete crushed material, earth and sand, and crucifixion may be used.

The mixing ratio of the dehydrated cake, the aggregate, the heavy metal ion fixing agent and the cement is not particularly limited. For example, (a) incineration ash containing aluminum and / or aluminum alloy is treated with an alkaline aqueous solution to obtain aluminum and Dehydrated cake obtained by dewatering aluminum hydroxide or / and aluminum alloy: 95 to 63% by weight (b) Incinerator fly ash: 0 to 42% by weight (c) Aggregate: 0 to 20% by weight ( d) Cement: 5 to 15% by weight (e) Heavy metal ion fixing agent: 0 to 2% by weight may be appropriately selected.

To solidify the cement, 40 to 55 wt% of water may be added to the above composition and kneaded.

When cement is solidified, an auxiliary agent such as carboxymethyl cellulose or polyvinyl alcohol may be added for the purpose of increasing viscosity.

Since the cement solidified product solidified by the method of the present invention does not generate hydrogen gas due to a reaction between aluminum and the like and a calcium compound in the cement, the solidified product is not cracked or cracked. It can be used as backfill material, roadbed material, sidewalk board, and backfill material for landfill sites.

[0025]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 JIS incineration ash and shredder dust incineration ash
After sieving with a 2.5 mm sieve, the incineration ash having a size of 2.5 mm or less was removed of iron and non-ferrous metal with a magnetic separator and a non-ferrous separator (eddy current). The obtained residue is dipped in a 200 L drum at a pulp density of about 40%, and a 30% sodium hydroxide solution is added to adjust the pH to 9 to 10 while stirring with a screw-type stirrer, and an interval of 15 to 30 minutes is added. After stirring for about 48 hours, it was dehydrated by a centrifugal dehydrator to obtain a dehydrated cake. The dehydrated cake is dried in a constant temperature oven (105 ℃ ~ 11
After drying at 0 ° C. for about 48 hours, powder X-ray analysis and chemical analysis (JIS cement raw material chemical analysis method) were performed. Table 1 shows the results.

Similarly, each of the raw materials is dried in a constant temperature dryer (105 ° C to
It was dried at 110 ° C.) for 24 hours and a heavy metal dissolution test was carried out (Environmental Agency Notification No. 13B). The results are shown in Table 2.

Next, the respective raw materials were blended in the blending ratios shown in Tables 3 and 4, and a JIS mortar mixer for testing (10
Liter), weighed, put about 40% of water, mixed, put in a plastic bag and solidified.

The solidified state after about 7 days was judged by pushing by hand. The results are shown in Tables 3 and 4. Furthermore, about 7
After a day, remove it from the plastic bag, cure it in water for about 30 days, leave it outdoors and let it air dry, and visually observe the occurrence of cracks on the specimen on the date of evaluation, and evaluate according to the following criteria. did. The results are shown in Tables 3 and 4. In addition, the solidified product was roughly crushed and an elution test was carried out by the method announced by the Environment Agency, and the concentration of the eluted heavy metal ions was measured and shown in Table 5.

(Hardness) ◎ ... Very hard ○ ... Hard Δ ... Slightly hardened × ... Not hardened (cracks) ○ ... Not generated △ ... 2 to 3 occurrences × ... Significant occurrence XX ... Significant occurrence And is cracked

[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 and 4, the formulation No. containing the dehydrated cake obtained by subjecting shredder dust or municipal waste incineration ash to alkali treatment. 2,5
The cement solidified product of No. had a sufficient hardness, and cracks did not occur even one year after solidification, whereas the compound No. containing Shredder dust or municipal waste incineration ash as it was. The cement solidification products of Nos. 1 and 4 were cracked and cracked after one year.

It should be noted that even if fly ash itself is blended, cracks do not occur in the cement solidified product (compound No. 3, 6),
When fly ash is compounded as a water content adjusting agent for the dehydrated cake when the solidifying method of the present invention is carried out, cracks do not occur (compound No. 14, 16 to 21, 23 to 26).

As is clear from the results of Table 5, the compound No. in which the incinerated ash treated with alkali and the heavy metal ion fixing agent were used in combination. 9, 11, 12, 14, 16 to 21,2
The cement solidified products of 4-26) did not crack even after one year, and the elution of heavy metal ions was suppressed, and the regulated value of 0.3 mg / l could be cleared.

Example 2 Both shredder dust incinerated ash and municipal solid waste incinerated ash (stalker type) were sieved in the same manner as in Example 1, and after removing iron and non-ferrous metals with a magnetic separator and a non-ferrous separator, 6
Put 0 kg in a drum and add an alkaline solution (10
0 kg, pH = 9.5) was added and treated to prepare a dehydrated cake. After mixing the composition such as dehydrated cake shown in the concrete composition below in a concrete mixer and mixing, water is added and kneaded, and then poured into a JIS concrete form (10 cmφ × 20 cm) using a vibrator for about 7 hours. Capping later, demolding after about 24 hours, curing in water for about 30 days, then leaving it to stand outdoors for natural curing.
The compressive strength is measured by the 0t pressure resistance test), the heavy metal elution test is performed by the method announced by the Environment Agency, and the surface dry specific gravity and the water absorption rate are measured according to the JIS test method of the concrete aggregate. Shown in.

(Concrete composition) ・ Incinerator ash dehydration cake 455 kg ・ Municipal solid waste incinerator fly ash 410 kg ・ Blast furnace cement (Type B) 120 kg ・ Sodium carbonate 10 kg ・ Ferrous sulfate 5 kg Example 3 Municipal waste according to Example 2 A dehydrated cake of incinerated ash was prepared, and a compound such as a dehydrated cake shown in the following concrete composition was kneaded in a concrete mixer in the same manner to prepare a test sample, and the compressive strength after curing and heavy metal were cured in the same manner as in Example 2. The elution amount, surface dry specific gravity and water absorption were measured. The results are shown in Tables 6 and 7.

(Concrete composition) ・ Dehydrated cake 435 kg ・ Municipal solid waste incinerator fly ash 435 kg ・ Blast furnace cement (B type) 120 kg ・ Sodium carbonate 10 kg Example 4 Was treated to prepare a dehydrated cake. As the aggregate, non-magnetic material (concrete debris, glass bottle, gravel, etc.) having a size of 3 mm or more in municipal waste incineration ash was crushed with a jaw crusher to a size of about 7 mm or less. A concrete specimen was prepared according to Example 2 from a mixture such as dehydrated cake shown in the following concrete composition, and after curing, compressive strength, heavy metal elution amount, surface dry specific gravity and water absorption were measured. The results are shown in Tables 6 and 7.

(Concrete composition) -Municipal waste dewatering cake 195 kg-Municipal waste incinerator fly ash 190 kg-Shredder dust dewatering cake 195 kg-Shredder dust incinerator fly ash 185 kg-Aggregate 100 kg-Common cement 120 kg-Sodium carbonate 12 kg-Hydroxyhydroxide Aluminum 3 kg Comparative Example 1 A concrete specimen was prepared by using shredder dust incinerated ash and municipal solid waste incinerated ash that were merely sieved to 3 mm or less, and at a mixing ratio of dehydrated cake and the like shown in the following concrete composition. After curing as in Example 2,
The compression strength, heavy metal elution amount, surface dry specific gravity and water absorption were measured. The results are shown in Tables 6 and 7.

(Concrete composition) ・ Incinerator ash 250 kg ・ Municipal refuse incinerator fly ash 150 kg ・ Shredder dust incinerator ash 250 kg ・ Shredder dust incinerator fly ash 195 kg ・ Common cement 12 kg ・ Sodium sulfide 10 kg ・ Ferrous sulfate 5 kg ・Sodium carbonate 10kg-Aluminum sulfate 10kg

[0044]

[Table 6]

[0045]

[Table 7]

As is clear from the results shown in Tables 6 and 7, the cement solidification products of Examples 2 to 4 in which the dehydrated cake obtained by subjecting the municipal solid waste and shredder dust to the alkali treatment and the heavy metal ion fixing agent were mixed, were solidified. Cracks do not occur even after one year has passed, elution of heavy metal ions is suppressed, and the regulation value can be cleared. On the other hand, the cement solidified product of Comparative Example 1 to which the incinerated ash of municipal solid waste and shredder dust was added as it was, had cracks already generated after 6 months had passed and had cracked after 1 year had passed.

[0047]

EFFECTS OF THE INVENTION By solidifying incinerated ash of municipal waste or shredder dust by the method according to claim 1 or 2, it is possible to obtain a cement solidified product which is free from cracks or cracks over time.

By the solidifying method according to the third aspect of the present invention, it is possible to obtain a cement solidified product which is free from cracks and cracks over time and from which heavy metal ions are not eluted.

Since the incineration ash solidified reclaimed material according to claim 6 does not cause cracks or cracks over time and does not elute heavy metal ions, it is used as a backfill material, a roadbed material, a sidewalk board, or a backfill material for landfill sites. Can be used.

According to the cement composition of claim 7,
It is possible to obtain a cement solidified product that does not crack or crack over time.

Claims (7)

[Claims] 1. An incineration ash in which aluminum and / or aluminum alloy remains is treated with an alkaline aqueous solution to convert aluminum and / or aluminum alloy into hydroxide, which is then dehydrated and cemented to be solidified. Method for solidifying incinerated ash. 2. An incineration ash in which aluminum and / or aluminum alloy remains is treated with an acid, aluminum and / or aluminum alloy is converted to an aluminum salt, neutralized and dehydrated, and cement is added to solidify. Solidification method of incinerated ash. 3. The method for solidifying incinerated ash according to claim 1, wherein a heavy metal ion fixing agent is added when the cement is added and solidified. 4. The incinerator ash according to claim 3, wherein the heavy metal ion fixing agent is at least one selected from the group consisting of aluminum hydroxide, aluminum sulfate, ferrous sulfate and sodium carbonate. Solidification method. 5. The incineration ash in which aluminum and / or aluminum alloy remains is an incineration ash obtained by incinerating municipal waste or shredder dust and sieving the incineration residue to remove iron and non-ferrous metals. The method for solidifying incinerated ash according to claim 1 or 2. 6. A dehydrated cake, a heavy metal ion fixing agent, and the like obtained by treating incineration ash in which aluminum and / or aluminum alloy remains with an alkaline aqueous solution to convert aluminum and / or aluminum alloy into hydroxide, and then dehydrating. A reclaimed ash solidified reclaimed material containing a wash surface. 7. A concrete composition containing the following components (a) to (e). (A) Dehydrated cake obtained by treating incinerated ash containing aluminum and / or aluminum alloy remaining therein with an aqueous alkali solution to form aluminum and / or aluminum alloy into hydroxide, and then dehydrating the mixture: 95 to 63% by weight (b ) Incinerator fly ash: 0 to 42% by weight (c) Aggregate: 0 to 20% by weight (d) Cement: 5 to 15% by weight (e) Heavy metal ion fixing agent: 0 to 2% by weight