JPH10218645A - Burning of burnt ash/burnt material and use of burnt material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for burning a burnt ash aiming at the utilization of the burnt ash as a resource and effectively utilizing the obtained burnt material as a material for solidifying a soil or a sludge. SOLUTION: This method for burning a burnt ash is constituted by adding 20-200wt.% lime source powder to 100wt.% burnt ash of an urban waste material, a sewage sludge, etc., and burning the mixture at >=950 deg.C and <=1200 deg.C so as to contain >=5wt.% free calcium in the burnt material. To 100wt.% mixture obtained by mixing a burnt material powder obtained by cooling and crushing the burnt material burnt by the above burning method, with one to several kinds selected from a Portland cement, a blast furnace cement, a gypsum, a blast furnace slag and a lime stone, a nitrate salt is added in 0-15wt.% range and used for solidifying a soil or a sludge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for firing incinerated ash generated when incinerating general waste, sewage sludge, industrial waste, etc., by a limited firing method.
The present invention relates to a method of burning incinerated ash and a method of using the burned material for effectively utilizing soil, sludge, and the like as a solidifying resource.

[0002]

2. Description of the Related Art General waste discharged from general households is incinerated in an incineration facility of a local government, treated with a chemical having a solidifying or chelating action for cement, and disposed of at a final disposal site of a controlled type. Also, in recent years, it has become difficult to secure a final disposal site, and technology has been developed to reduce, detoxify, and recycle incinerated ash. The mainstream of this technology development is to melt at a temperature of about 1200 ° C. to 1500 ° C., collect it as molten slag, and to reuse it as a roadbed material, an aggregate, a raw material for cement, and the like.

In the cement industry, wastes such as municipal waste incineration ash, quicklime-treated sewage sludge, and aluminum ash are used as raw materials for cement, and clay, silica, iron raw materials, and limestone powder, which are the original cement raw materials, are used. Are mixed in a suitable amount, fired at a temperature of 1300 ° C. or more, cooled and pulverized, and put to practical use as ecocement.

[0004]

The incineration ash of municipal waste contains harmful heavy metals such as cadmium, lead, and chromium, and the temperature at the time of incineration is low. The incinerated fly ash contains harmful dioxins such as polychlorinated dibenzoparadioxin and polychlorinated dibenzofuran of tetrachloride to octachloride. The melting method for melting incinerated ash and collecting it as slag is as follows.
It is necessary to raise the temperature to 200 ° C. or higher, resulting in high energy costs and enormous capital investment.

[0005] In addition, ecocement must be fired at a temperature of 1300 ° C. or higher, and the management of the preparation of cement raw materials and the firing technology are complicated. It is extremely difficult to manage and takes considerable time to spread. Furthermore, when a new facility is installed to produce eco-cement, enormous capital investment is required as in the case of the melting method.

Accordingly, it is an object of the present invention to decompose harmful dioxins or to make them harmless by taking them as minerals in a fired product, to be able to easily burn with little capital investment and to save energy, and to effectively use the obtained fired product. It is an object of the present invention to provide a method for burning incinerated ash, a method for using the fired material, and a method for using the fired material.

[0007]

According to the present invention, there is provided a method for burning incinerated ash, which comprises at least 20 to 2 limestone powders based on 100% by weight of incinerated ash such as municipal waste and sewage sludge.
And sintering temperature of 950 ° C. or more,
It is characterized in that it is fired at a temperature of 200 ° C. or lower and that the fired product contains 5% or more of free calcium.

In order to achieve the above object, a fired product of the present invention is obtained by cooling and pulverizing the fired product obtained by the above-described firing method, and has a particle size of 2000 to 6000 cm ² / g in Blaine value.
Characterized in that it is a hydraulic powder.

Further, the method for using the calcined product of the present invention for achieving the above object is as follows:
A mixture 100 in which one to several kinds of Portland cement, blast furnace cement, gypsum, blast furnace slag and lime are mixed
It is characterized in that nitrate is added in the range of 0 to 15% by weight with respect to% by weight and used for solidifying soil, sludge and the like.

[0010]

Embodiments of the present invention will be described below. The present invention, in the incineration facilities, dechlorination, contains 20-40% as CaO content in the ash in order to use Ca (OH) ₂ and CaCO ₃ for desulfurization, paying attention to the amount of CaO Then, limestone powder was added to the incinerated ash and mixed, and a firing experiment was performed.
It has been found that it is effective to harden the soil and sludge by containing more than 10%.

In the method for firing incinerated ash of the present invention, when the amount of CaO in the incinerated ash is as small as about 20%, limestone powder must be added and mixed during firing. Also,
Even if the amount of CaO in the incinerated ash is about 40%, in order to make the calcined material contain 5% or more of free calcium, limestone powder is added at 20% by weight or more with respect to 100% by weight of the incinerated ash and calcined. There is a need.

When the amount of CaO in the incinerated ash is as small as 10% or less, 200% by weight of limestone powder is added to 100% by weight of the incinerated ash and calcined. 5% or more. As a matter of course, it is also possible to use a method in which when incinerated ash is fired, limestone powder is fired without being added and mixed, and quick lime having the same effect is added and mixed in the subsequent stage.

When the firing temperature is lower than 950 ° C., harmful dioxins are not completely decomposed. When the firing temperature is 95
0 ℃ becomes higher when the dioxins with the harmless decomposed, most of the chlorine, calcium chloroaluminate _{(11CaO · 7A1 2 O 3 ·} CaC1 2) and calcium chlorosilicate (2CaO · SiO ₂ · CaC1 _{2
· 3CaO · SiO 2 · CaC1 2} ) is fixed as a hydraulic minerals such. These hydraulic minerals are stably present at a temperature of 1200 ° C. or lower and decompose at a temperature of 1200 ° C. or higher. Therefore, the burning temperature of the incinerated ash of the present invention is 95%.
The temperature was limited to 0 ° C or more and 1200 ° C or less.

The fired product obtained by the above-described method for firing incinerated ash is cooled and pulverized into a hydraulic powder. The particle size of the powder is not particularly limited, but the Blaine value is from 2000 to 60.
00 cm ² / g, and preferably 3000 cm ² / g or more. Examples of the cooling method include natural cooling, air cooling, indirect cooling using water and direct cooling in water.In the present invention, any cooling method other than direct cooling in water is used. However, air cooling methods widely used in the cement industry are preferred.

The calcined powder contains 5% or more of free calcium and contains a small amount of hydraulic minerals such as calcium chloroaluminate and calcium chlorosilicate.
Soil and sludge can be hardened only by this fired material powder. However, this calcined powder, to include not hydrated little water melilite _{(2CaO · A1 2 O 3 ·} SiO 2), only this calcined powder, to solidify the soil and sludge is solidified object 1m ^In contrast to ³ , it is necessary to mix a large amount of fired powder. Therefore, it is more effective to use this fired product powder as a mixture of one or more of Portland cement, blast furnace cement, gypsum, blast furnace slag, and lime.

The reason why the types and mixing ratios of the materials to be mixed are not limited is that the types and mixing ratios of the materials to be mixed greatly differ depending on the types of soil and sludge to be solidified. In addition, the mixture of Portland cement, blast furnace cement, gypsum, blast furnace slag and lime mixed with the fired material powder and the fired material powder is kneaded with water depending on the form of the alumina component and the amount of metallic aluminum contained in the fired material powder. May foam. In order to suppress this foaming, nitrate is added in an amount of 0 to 1 with respect to 100% by weight of the mixture.
It must be added in the range of 5% by weight. As the nitrate, any nitrate such as NaNO ₃ or KNO ₃ can be used. In the present invention, the nitrate is limited to 0 to 15% by weight based on 100% by weight of the mixture because foaming may not occur.

Further, the mixture thus obtained may cause abnormal coagulation when kneaded with water,
In this case, a setting retarder such as citric acid or citrate may be added in the range of 0.1 to 1.0% by weight based on 100% by weight of the mixture. The mixture in which the above-mentioned foaming and abnormal coagulation are suppressed can solidify soil and sludge, and has the same performance as a commercially available cement-based solidification material or quick lime-based solidification material.

[Example A] The incinerated ash of general waste in the Mitama district was passed through a 15 mm sieve and used by magnetic separation. The incinerated ash: limestone powder was mixed at a weight ratio of 2: 1 and fired in a laboratory rotary kiln while controlling the firing temperature in the range of 1000 to 1050 ° C. The calcination time was about 10 minutes from the input of the raw materials to the rotary kiln until the discharge. This calcined product was subjected to a Blaine value of 3500 cm ^{2 in a} test mill.
/ G to obtain a fired product powder. The free calcium in the fired powder was 12.1%. As other minerals, calcium chloroaluminate and melilite are X
Identified by line diffraction. The calcined product powder was analyzed for dioxins, and as a result, 0.00057 ng / g (2,
3,7,8, -4 dibenzoparadioxin chloride). This fired product powder (hereinafter referred to as ash) was used in Example B.

Example B The materials used in Example B are as follows. Ash: Example fired at A, cooled, calcined powder OPC was obtained by grinding: Ordinary portland cement S L: Blaine 4200cm ² / g of blast furnace slag A G: Blaine value 5000 cm ² / g natural anhydrite of N N : NaNO ₃ sludge of reagent: Freshwater sludge of Kasumigaura, water content: 350%, unit weight of wetting 1.13 1 g / cm ³ Soil: Tokyo Bay Wakashu sandy silt, water content 60%, unit weight of wetting 1 0.62 g / cm ³

The ash, OPC, SL, and AG were mixed at different mixing ratios (described in Table 1 in FIG. 1) to obtain a mixture. When the sludge was solidified, the mixture was 240 kg / m ³ with respect to 1 m ³ of the sludge, and five blends were carried out (Examples Nos. 1 to 5 are described in Table 1 in FIG. 1). In the case of soil, the mixture was 120 kg / m ³ per 1 m ^{3 of} soil, and 7 blends were carried out (Examples Nos. 7 to 13 are shown in Table 1 of FIG. 1). When kneading the mixture with sludge or soil, NN is added in an amount of 2.5 to 100% by weight of the mixture.
% By weight. In the case of sludge as a composition containing only ash, Example No. described in Table 1 of FIG. And 400 kg / m ³ relative to the sludge 1 m ³ as 6, example in the case of soil were listed in Table 1 of FIG. 1 No. As 14, No. 200 kg / m ³ was added to 1 m ³ of soil. When kneading sludge or soil with ash, add 5% by weight of NN to 100% by weight of ash, and add 0.2% by weight of citric acid to 100% by weight of ash
And kneaded. Further, as a comparative example, in order to confirm the contribution or effect to the strength of the ash when the mixture was used, in the case of sludge, Example No. 1 shown in Table 1 of FIG. In the case of soil with the composition of Example No. 3 described in Table 1 of FIG. In the case of sludge in the composition of Comparative Example No. 7 shown in Table 1 of FIG. In the case of soil, Comparative Example No. 1 shown in Table 1 of FIG. As No. 2, kneaded with sludge or soil without adding NN except for each ash. The mixture kneaded in this way is 5φ
It was molded into a × 10 cm mold, demolded after 3 days of material age, then cured in a 20 ° C. humidity box and subjected to a uniaxial compressive strength test. The results are as shown in Table 1 of FIG.

[0021]

As described above, the method for burning incinerated ash of the present invention decomposes harmful dioxins contained in incinerated ash or takes them as minerals in the burned material, renders them harmless, saves energy and is easy with little equipment investment. And the resulting fired material can be effectively used as a material for solidifying soil and sludge, and has a high social contribution from the viewpoint of recycling waste. The effect is remarkable.

[Brief description of the drawings]

FIG. 1 is a table showing the results of a uniaxial compressive strength test in the present invention.

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[Procedure amendment]

[Submission date] March 24, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a view showing the results of a uniaxial compressive strength test in the present invention .
table

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C09K 17/10 B09B 3/00 301E // C09K 103: 00 303L (72) Inventor Hiroshi Shimazu 971-410 Momokasa, Hino-shi, Tokyo

Claims (3)

[Claims] 1. A limestone powder is added and mixed in an amount of 20 to 200% by weight with respect to 100% by weight of incinerated ash such as municipal garbage and sewage sludge, and baked at a firing temperature of 950 ° C. or more and 1200 ° C. or less. A method for burning incinerated ash, characterized in that free calcium is contained therein in an amount of 5% or more. 2. A fired product fired by the firing method according to claim 1 is cooled and pulverized to a particle size of 2000 to 6 as Blaine value.
A burned material of incinerated ash, characterized in that it is a hydraulic powder of 000 cm ² / g. 3. A mixture 1 in which one or several kinds of Portland cement, blast furnace cement, gypsum, blast furnace slag and lime are mixed with the incinerated ash powder according to claim 2.
A method for using a fired product, wherein nitrate is added in an amount of 0 to 15% by weight with respect to 00% by weight and used for solidifying soil, sludge, and the like.