JP2007176793A - Method for manufacturing fired product of incineration ash - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To aim at the recycling of incineration ash in which the incineration ash is fired by a limited fired method, and the obtained fired product is effectively used as a material which hardens soil, sludge or the like. <P>SOLUTION: This method for manufacturing a fired product of incineration ash comprises: adding/mixing 20-200 wt.% of a limestone powder with 100 wt.% of an incineration ash from municipal waste and sewage sludge: firing the mixture at a firing temperature range of 1,000-1,050°C; obtaining a fired product containing 5% or more of free calcium in the fired product; and cooling/pulverizing this to make the hydraulic powder having the particle size of 2,000-6,000 cm<SP>2</SP>/g by a Blaine value. In addition, the method for manufacturing a fired product of incineration ash comprises, after making the hydraulic powder, adding a nitrate in the range of 0-15 wt.% with 100 wt.% of the mixture in which one to several kinds of portland cement, slag cement, plaster, blast furnace slag, and lime for using for solidification of soil and sludge are mixed to this powder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is baked by a burning method that limits incineration ash generated when incinerating general waste, sewage sludge, industrial waste, etc., and the obtained baked product is effectively used as a resource for hardening soil, sludge, etc. The present invention relates to a method for burning incinerated ash.

  General waste discharged from ordinary households is incinerated at local incineration facilities, treated with chemicals with cement solidification or chelating action, and landfilled in a managed final disposal site. In recent years, it has become difficult to secure a final disposal site, and technological development has been made to reduce the volume of incinerated ash, render it harmless, and recycle it. The mainstream of this technical development is to melt at a temperature of about 1200 ° C. to 1500 ° C. and collect it as a molten slag, and recycle it as a roadbed material, aggregate, cement raw material, and the like.

  In the cement industry, wastes such as municipal waste incineration ash, lime-treated sewage sludge, and aluminum ash are used as raw materials for cement, and appropriate amounts of clay, meteorite, iron raw material, and limestone powder, which are the original cement raw materials, are mixed It is fired at a temperature of 1300 ° C. or higher, cooled and pulverized, and put into practical use as an ecocement.

  Because the incineration ash of general waste contains toxic heavy metals such as cadmium, lead, and chromium, and the temperature during incineration is low, the incineration fly ash collected by various dust collectors at the incineration facility contains 4 Harmful dioxins such as polychlorinated dibenzoparadioxin and polychlorinated dibenzofuran of chlorinated to octachloride are contained. The melting method for melting the incinerated ash and recovering it as slag requires a high temperature of 1200 ° C. or higher, which results in high energy costs and enormous capital investment.

  Eco-cement also needs to be fired at a temperature of 1300 ° C or higher, and if there are no personnel with special skills and skills due to complex management of cement raw materials and firing techniques, etc. This is extremely difficult and requires a considerable amount of time to spread widely. Furthermore, in the case of newly installing equipment for producing ecocement, enormous capital investment is required as in the melting method.

  Accordingly, the object of the present invention is to decompose harmful dioxins or make them harmless by incorporating them as minerals in the fired product, to save energy and easily with less capital investment, and incinerated ash from which the obtained fired product can be effectively used. It is to provide a firing method, a fired product, and a method of using the fired product.

  The incineration ash firing method of the present invention for achieving the above-described object is achieved by adding 20 to 200% by weight of limestone powder to 100% by weight of incineration ash such as municipal waste and sewage sludge, and the firing temperature is 950. The calcined product is characterized by being calcined at a temperature of from ℃ to 1200 ℃ and containing 5% or more of free calcium in the calcined product.

  In addition, the fired product of the present invention for achieving the above object is that the fired product obtained by the above firing method is cooled and pulverized to form a hydraulic powder having a grain size of 2000 to 6000 cm @ 2 / g. It is a feature.

  Furthermore, the method of using the fired product of the present invention to achieve the above object is a mixture in which one or more of Portland cement, blast furnace cement, gypsum, blast furnace slag and lime is mixed with the incinerated ash fired powder. Nitrate is added in the range of 0 to 15% by weight with respect to 100% by weight, and is used for solidifying soil, sludge and the like.

  As described above, the incineration ash firing method of the present invention decomposes harmful dioxins contained in the incineration ash or renders them harmless as a mineral in the fired product, making it possible to save energy and easily fire with less equipment investment. It is possible, and the obtained fired product can be effectively used as a material for solidifying soil and sludge. From the viewpoint of recycling of waste, the social contribution is high, and the effect of the present invention is remarkable. is there.

  Embodiments of the present invention will be described below. The present invention uses Ca (OH) 2 and CaCO3 for dechlorination and desulfurization in an incineration facility, so that the incineration ash contains 20 to 40% as CaO amount. In addition, limestone powder was added to incinerated ash, and a firing experiment was conducted. The fired product contained 5% or more of free calcium, and was found to be effective in hardening soil and sludge. is there.

  In the incineration ash firing method of the present invention, when the amount of CaO in the incineration ash is as small as about 20%, limestone powder must be added and mixed when firing. Moreover, even if the amount of CaO in the incinerated ash is about 40%, in order to contain 5% or more of free calcium in the fired product, limestone powder is added by 20% by weight or more with respect to 100% by weight of the incinerated ash. It is necessary to fire.

  In addition, when the amount of CaO in the incinerated ash is a small amount of 10% or less, 200% by weight of limestone powder is added to and mixed with 100% by weight of the incinerated ash, and then the free calcium in the fired product is 5%. It can be contained above. Naturally, when burning the incinerated ash, a means of baking without adding and mixing the limestone powder and adding and mixing quick lime having the same effect at a later stage is also possible.

  When the firing temperature is 950 ° C. or lower, harmful dioxins are not completely decomposed. When the firing temperature is 950 ° C. or higher, the dioxins are decomposed and detoxified, and most of the chlorine is calcium chloroaluminate (11CaO · 7A12 O3 · CaC12) or calcium chlorosilicate (2CaO · SiO2 · CaC12 · 3CaO).・ Fixed as a hydraulic mineral such as SiO2 and CaCl2. These hydraulic minerals exist stably at a temperature of 1200 ° C. or lower and decompose at a temperature of 1200 ° C. or higher. Therefore, the firing temperature of the incinerated ash of the present invention is limited to 950 ° C. or more and 1200 ° C. or less.

  The fired product obtained by the incineration ash firing method is cooled and pulverized to form a hydraulic powder. The particle size of the powder is not particularly limited, but it is 2000 to 6000 cm @ 2 / g in terms of brain value, and preferably 3000 cm @ 2 / g or more. Cooling methods include natural cooling, air cooling, indirect cooling using water and direct cooling into water. In the present invention, any cooling method other than direct cooling into water can be used. Can be used, but air cooling methods widely used in the cement industry are preferred.

  Since this 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 with this calcined powder. However, since this calcined powder contains melilite (2CaO.A1 2 O3.SiO2) that hardly hydrates, to solidify soil and sludge with this calcined powder alone, It is necessary to mix a large amount of the fired powder. Therefore, it is more effective to use this fired powder as a mixture in which one to several kinds of Portland cement, blast furnace cement, gypsum, blast furnace slag and lime are mixed.

  Here, the reason why the type and mixing ratio of the mixture to be mixed are not limited is that the type and mixing ratio of the mixture to be mixed greatly differ depending on the type of soil or sludge that is the solidification target. In addition, when calcined powder and a mixture of calcined powder and Portland cement, blast furnace cement, gypsum, blast furnace slag and lime are kneaded with water depending on the form of the alumina component and the amount of metallic aluminum contained in the calcined powder May foam. In order to suppress this foaming, it is necessary to add nitrate in the range of 0 to 15% by weight with respect to 100% by weight of the mixture. Any nitrate such as NaNO3, KNO3, etc. can be used. Since foaming may not occur, in the present invention, nitrate is limited to 0 to 15% by weight with respect to 100% by weight of the mixture.

Furthermore, the mixture thus obtained may cause abnormal coagulation when kneaded with water. In that case, a coagulation retarder such as citric acid or citrate is added to 0.1% by weight with respect to 100% by weight of the mixture. What is necessary is just to add and use in 1 to 1.0 weight% of range. The above-described mixture that suppresses foaming and abnormal condensation can solidify soil, sludge, etc., and has the same performance as a commercially available cement-based solidified material or quicklime-based solidified material. I will explain it. The present invention is not limited in any way by these examples.

  [Example A] The incinerated ash of the general waste in the Mitama area was passed through a 15 mm sieve and used after being magnetically selected. The incinerated ash: limestone powder was mixed at a weight ratio of 2: 1, and the mixture was baked in a laboratory rotary kiln controlled at a calcination temperature of 1000 to 1050 ° C. The firing time was about 10 minutes from when the raw material was charged into the rotary kiln until it was discharged. This fired product was pulverized with a test mill to a brain value of 3500 cm @ 2 / g to obtain a fired product powder. The free calcium in the calcined powder was 12.1%. As other minerals, calcium chloroaluminate and melilite were identified by X-ray diffraction. As a result of analyzing dioxins of the fired powder, it was 0.00057 ng / g (2, 3, 7, 8, -4 chloride dibenzoparadioxin toxicity equivalent equivalent concentration). This fired powder (hereinafter referred to as ash) was used in Example B.

[Example B] The materials used in Example B are as follows.
Ash: calcined powder obtained by calcining, cooling and pulverizing in Example A OPC: normal Portland cement S L: blast furnace slag with a brane value of 4200 cm 2 / g A G: natural anhydrous gypsum with a brane value of 5000 cm 2 / g N N: reagent NaNO3 sludge: Freshwater sludge from Kasumigaura, water content 350%, warm unit volume weight 1.13 1 g / cm3 Soil: Wakaju sandy silt, Tokyo Bay, water content 60%, warm unit volume weight 1.62 8 g / cm3

  The mixture was obtained by changing the mixing ratio of ash, OPC, SL, and AG (described in Table 1 of FIG. 1) to obtain a mixture. When the sludge was solidified, the mixture was 240 kg / m3 with respect to 1 m3 of sludge, and 5 blends were carried out (Examples No. 1 to 5 are described in Table 1 of Fig. 1). In the case of soil, the mixture was 120 kg / m3 with respect to 1 m3 of soil, and 7 blends were carried out (described in Table 1 of Fig. 1 as Example Nos. 7 to 13). When mixing sludge or soil and the mixture, NN was added at 2.5% by weight with respect to 100% by weight of the mixture. In addition, in the case of sludge as a composition containing only ash, Example No. described in Table 1 of FIG. No. 6 is 400 kg / m 3 per 1 m 3 of sludge, and in the case of soil, Example No. described in Table 1 of FIG. No. 14, 200 kg / m 3 was also added to 1 m 3 of soil. When kneading sludge or earth and ash, 5% by weight of NN was added to 100% by weight of ash, and further 0.2% by weight of citric acid was added to 100% by weight of ash and kneaded. Further, in order to confirm the contribution or effect to the strength of ash when a mixture is used as a comparative example, in the case of sludge, Example No. 1 described in Table 1 of FIG. In the case of soil with the formulation of No. 3, Example No. described in Table 1 of FIG. In the case of sludge in the formulation of No. 7, the comparative example No. described in Table 1 of FIG. 1, in the case of soil, Comparative Example No. 1 described in Table 1 of FIG. No. 2 was mixed with sludge or soil without adding NN. The kneaded mixture was molded into a 5φ × 10 cm mold, demolded after 3 days, and then cured in a humidity box at 20 ° C., and a uniaxial compressive strength test was performed. The results are as shown in Table 1 of FIG.

Chart showing uniaxial compressive strength test results in the present invention

Claims (2)

20 to 200% by weight of limestone powder is added to and mixed with 100% by weight of incineration ash of municipal waste and sewage sludge, fired at a firing temperature of 1000 to 1050 ° C., and free calcium is 5% or more in the fired product. A method for producing a calcined product of incinerated ash characterized by obtaining a calcined calcined product, cooling and pulverizing it to obtain a hydraulic powder having a grain size of 2000 to 6000 cm ² / g.   After making it into hydraulic powder, 0% nitrate is added to 100% by weight of the mixture of 1 to several kinds of Portland cement, blast furnace cement, gypsum, blast furnace slag and lime to be used for solidification of soil and sludge. A method for producing a burned product of incinerated ash, which is added in a range of ˜15 wt%.

Images