KR100492619B1 - a Process Method for Scatter Ash following burn up Living Wastes - Google Patents

Abstract

The present invention relates to a method for treating fly ash according to household waste incineration.

This is especially harmful to cement such as chlorine and heavy metals contained in the fly ash by injecting carbon dioxide gas generated in the incinerator or in the manufacture of cement when the fly ash collected in the dust collector is washed or washed with water as various household wastes are incinerated. By dissolving or removing carbonate feed materials such as sodium carbonate to reduce the elution of heavy metal ions below environmental regulations.

Accordingly, the wastewater generated during the washing process is treated stably and at the same time, the environmental pollution caused by the landfill of fly ash is solved, and the solid matter remaining after the washing process is recycled into the cement raw material.

Description

{A Process Method for Scatter Ash following burn up Living Wastes}

The present invention relates to a method for treating fly ash according to household waste incineration, and more particularly, by injecting a carbonate feed material such as carbon dioxide and sodium carbonate into the ash when flushing the fly ash generated during incineration with water. The present invention relates to a method for treating fly ash according to incineration of household wastes, which removes chlorine components, makes heavy metals poorly solubilized and stabilizes fly ash, thereby stably treating wastewater generated and recycling fly ash as cement raw material.

In recent years, in the method of disposal of household waste, which has emerged as one of the new urban problems, in the past, mainly landfilling has become increasingly difficult to secure land for landfills in countries with a small land area. It is emerging as a major alternative for the longevity of landfills.

In addition, incineration ash generated after incineration of household waste is classified into floor ash and fly ash. In particular, fly ash is less generated than floor ash, but has a relatively high content of chlorine and heavy metals. It is declared as a waste and must be landfilled in a managed landfill.

As a result, landfill costs are increasing, and the hazards associated with their landfills are much higher than those for flooring and are not suitable for recycling.

In order to landfill such fly ash, a solidification method for putting solidified material and incineration ash into a mixer, mixing with water to solidify, and adding a chemical and a chemical stabilization method for stabilizing heavy metals in the incinerated ash to reduce the elution amount are used.

However, the solidification method as described above, the weight loss effect is rather less according to the addition of the solidified material, when the pH is less than the alkali or weak acidity, the heavy metal is likely to be eluted again and the solidification treatment cost is also high.

On the other hand, the chemical stabilization method has a disadvantage that the chemical (mainly chelating agent) used as a stabilizer is expensive.

An object of the present invention for improving this, to ensure the stable recycling of municipal waste fly ash as a cement raw material, to dissolve and remove heavy metals and chlorine components contained in the fly ash generated during the municipal waste incineration process, contained in the incineration ash The present invention provides a method for treating fly ashes according to incineration of domestic wastes, which precipitates heavy metals with poorly soluble compounds such as hydroxides and carbonates to stabilize and inhibit leaching of heavy metals.

In order to achieve the above objectives, fly ash containing the main components of cement such as CaO, SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ and chlorine compounds such as KCl and NaCl to be used as cement raw materials A method of treating fly ash according to incineration of household wastes, which is washed with water, filtered and discharged to solidify the filtrate.

In addition, by injecting carbonate ions into fly ash generated during incineration of domestic waste, the fly ash: water ratio of 1:10 to 1: 1 is washed at least once with water in the temperature range of 5 to 50 ° C. to remove chlorine and heavy metals. Provided is a method for treating fly ash from incineration of domestic waste that is to be removed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Raw materials for cement production include limestone as calcium oxide (CaO), silica as source of silicon oxide (SiO ₂ ), clay as source of aluminum oxide (Al ₂ O ₃ ), and iron ore as source of iron oxide (Fe ₂ O ₃ ). Mainly used.

However, for the shortage and preservation of such raw materials, research and use records for using waste containing CaO, Al ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ as raw materials are increasing. By using these wastes to manufacture cements, cement raw materials are secured and wastes, which have been a source of pollution, can be treated at low cost, thus reducing environmental damage caused by landfills and reducing disposal costs by eliminating landfills. There are several advantages that can be achieved together.

On the other hand, fly ash discharged from domestic waste incineration contains a large amount of cement, CaO, Al ₂ O ₃ and SiO ₂ , which can be used as a cement raw material, but since fly ash contains a large amount of chlorine, cement is manufactured. In this case, volatilization of these chlorine compounds and heavy metal compounds causes process anxiety, or they are contained in clinker, which lowers the properties of cement.

Tables 1, 2, and 3 illustrate the chemical composition, chlorine content, heavy metal content, and the chemical composition of fly ash emitted from domestic waste incinerators in Ilsan and Busan, where the composition of fly ash is different. The amount of elution was shown.

First, 41.86 wt%, 7.10 wt% and 3.51 wt% of CaO, SiO ₂ and Al ₂ O ₃ are contained in fly ash in Ilsan area, 8.85 wt%, 6.07 wt% and 3.28 weight in fly ash in Busan area respectively. As it contains about%, the content of these components varies greatly depending on the flue-gas treatment method of the incinerator.

However, it was found that the chlorine component, which volatilizes during cement production and causes problems in the cement manufacturing process, is very high at 22.9 wt% and 26.0 wt%, respectively, in Ilsan and Busan fly ash.

TABLE 1

sample Chemical composition (% by weight) CaO SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ MgO TiO ₂ Na ₂ O K ₂ O MnO P ₂ O ₅ Cl Ilsan fly ash 41.86 7.10 3.51 0.77 2.21 0.91 5.47 4.60 0.05 2.16 22.90 Fly ash fly ash 8.85 6.07 3.28 0.64 1.60 0.92 9.58 12.37 0.10 2.31 26.00

In the case of heavy metal content, fly ash in Ilsan area contained 568mg / kg Cu, 166mg / kg Cd, 2,130mg / kg Pb, 318mg / kg Cr, and 1,370mg / kg Cu in Busan fly ash, It was found that Cd contained 507 mg / kg, Pb 5,800 mg / kg and Cr as high as 671 mg / kg.

As a result of the heavy metal elution, as shown in Table 3, in the case of Ilsan fly ash, Pb is 17.86ppm, Busan fly ash is 10.38ppm and Cd is 36.63ppm. Appeared to be.

TABLE 2

sample Heavy metal content (mg / kg) Cu CD Pb Cr As Ilsan fly ash 568 166 2,130 318 13 Fly ash fly ash 1,370 507 5,800 671 62

TABLE 3

Fly ash Heavy Metal Elution (ppm) Cu Cr Pb CD As Ilsan fly ash Not detected 0.17 17.86 Not detected Not detected Busan fly ash Not detected 0.20 10.38 36.63 Not detected

That is, as can be seen from the above experimental results, the trace amount of heavy metals and chlorine present in the domestic waste is volatilized / concentrated when incinerated and collected in the dust collecting facility, so the concentration of heavy metals and chlorine is higher than that of the floor ash in the municipal waste incineration. Concentrated to high concentration.

If these incineration materials are landfilled or utilized without pretreatment, the heavy metals and chlorine contained in them will cause secondary pollution such as soil and groundwater contamination. In order to landfill or recycle, the following pretreatment was required to remove or stabilize these substances.

In the present invention, while treating the fly ash to be scattered during incineration, the ash collected at this time is used as a cement raw material. When this is explained, as shown in FIG. 1, when incineration fly ash generated in a municipal waste incinerator is washed, it is generated in an incinerator and cement manufacturing process. Carbonate ion-containing substances such as carbon dioxide gas and sodium carbonate are added to adjust the pH of the solution in the range of 8 to 11.

At this time, the chlorine component that affects the cement manufacturing process and cement quality is removed and the heavy metal is stabilized to dissolve the amount of heavy metal ions in the wastewater below the environmental regulations, so that the fly ash can be used together with the wastewater treatment. do.

In addition, the chlorine content of the raw materials used to manufacture the cement as described above is limited to 100 mg / kg or less, as described above, chlorine is contained in the fly ash more than 2,000 times the limit value in order to use them as raw materials for cement Appropriate pretreatment to remove the components is required.

Figure 1 shows the results of fly ash XRD analysis in the areas of Ilsan and Busan, where chlorine components in fly ash exist mainly as compounds such as potassium chloride (KCl), sodium chloride (NaCl), and chlorine content is about 22.9% by weight and 26.0% by weight. .

Since these chlorides have very high solubility in water, KCl dissolves about 34.4g (20 ℃) per 100g of water, and NaCl dissolves 35.7g (20 ℃) per 100g of water. It seems to be.

In addition, Table 4 and Figure 2 shows the solubility of the major heavy metal hydroxides and carbonates at 25 ℃ according to the pH and solubility of the heavy metal hydroxides can be seen that their solubility changes with pH.

TABLE 4

 Heavy metal ions Hydroxide (K _sp ) Carbon dioxide (K _sp ) Cr ⁺² Cr (OH) ₂ - 7.1 × 10 ^-2 - Cr ⁺³ Cr (OH) ₃ - 6.3 × 10 ^-4 - Pb ⁺² Pb (OH) ₂ PbCO ₃ 7.1 × 10 ² 3.8 × 10 ^-2 Cd ⁺² Cd (OH) ₂ CdCO ³ 1.1 2.6 × 10 ^-1 Hg ⁺ - Hg ₂ CO ₃ - 1.1 Hg ⁺² Hg (OH) ₂ - 2.4 × 10 ^-1 - Cu ⁺ CuOH - 8.1 × 10 ^-3 - Cu ⁺² Cu (OH) ₂ CuCO ₃ 1.1 × 10 ^-2 7.5 × 10 ^-1

As a result, these heavy metal compounds exhibit the lowest solubility between pH 8 and 11, so that the pH is controlled in the range of 8 to 11, particularly in the case of Pb, making Pb ions into carbonates having lower solubility than hydroxides, thereby generating wastewater. The concentration of heavy metal ions in the solution can be dissolved at or below environmental regulations.

Therefore, the pH of the solution is adjusted to about 8 to 11 while injecting carbonic acid gas into the water when the fly ash is agitated with water (washing) or injecting a carbonate such as sodium carbonate that can supply carbonic acid ions when dissolved in a low pH solution. If so, remove chlorine, which has a major impact on the cement manufacturing process.

In addition, since heavy metals such as copper, lead, and cadmium dissolved in the solution are precipitated by poorly soluble carbonates or hydroxides, the waste metals have an effect of dissolving heavy metals below environmental regulations and not requiring separate wastewater treatment.

In addition, the washing process has a high solubility of chloride, so that the stabilization rate is faster than that of aging in an ordinary atmosphere, and the process is simple, and the incinerator (about 10% by volume) and the cement manufacturing process (no need for a separate carbon dioxide gas supply) By using the carbon dioxide gas generated in about 20% by volume), the carbon dioxide gas can be economically utilized while preventing air pollution by the carbon dioxide gas.

And, Figure 3 is a process diagram schematically showing a method of washing the fly ash according to the present invention, by putting the fly ash generated during the incineration of domestic waste into the washing tank to supply carbonate ion-containing materials such as carbon dioxide and sodium carbonate to wash for a predetermined time After filtration, the filtrate is discharged and the solids from which harmful components such as chlorine are removed are used as cement raw materials.

Treatment of municipal waste incineration fly ash through the process of the present invention as described above lowers the concentration of heavy metal ions contained in waste water at the time of washing, while removing chlorine components that adversely affect process anxiety and cement quality during the manufacture of cement. To do that.

By pretreatment by treatment with carbon dioxide and sodium carbonate during the flushing of such fly ash can be used as a raw material of cement as well as stabilizing fly ash and wastewater treatment can be expected to be utilized as a filling material.

In addition, by selectively using the carbon dioxide gas generated in the municipal waste incinerator and cement manufacturing process, the carbon dioxide gas can be utilized while suppressing the generation of carbon dioxide in the incineration and manufacturing process.

EXAMPLE

Stainless steel cylindrical reactors with a diameter of 26cm and a height of 60cm were installed to remove chlorine from the incineration of household wastes and to stabilize heavy metals by treatment with water and carbon dioxide.

The experimental apparatus is composed of a reactor, a filter, a carbon dioxide ion inlet such as carbon dioxide and sodium carbonate, a filtration device, and a filtrate storage tank.

3 to 30 kg of fly ash generated from the domestic waste incinerators of Ilsan and Busan were put into the experimental apparatus, and 30L of water was injected and stirred.

Table 5 shows the result of measuring the chlorine content of solids after washing with water from 15 minutes to 60 minutes. There was no difference in chlorine removal rate after 15 minutes of washing time regardless of fly ash generation area.

TABLE 5

Fly ash type Washing time 15 minutes 30 minutes 1 hours Ilsan Fly Ash 96.5% 96.5% 96.5% Busan fly ash 94.7% 94.7% 94.7%

In other words, Ilsan fly ash lowers the chlorine content from about 22.9% to about 0.8% by weight after 15 minutes of washing, and Busan fly ash falls from about 26.0% to about 1.4% by weight, respectively, 96.5% by weight and 94.7% by weight of the initial chlorine content. Removal rate was shown.

In addition, as shown in Table 2, the concentration of heavy metals in the filtrate after filtration significantly exceeded the standard values of 17.8 ppm of lead in ilsan fly ash and 10.28 ppm and 35.5 ppm of cadmium in Busan fly ash, respectively.

In addition, Table 6 shows the result of examining the influence on the water washing temperature, when the solid: liquid ratio of 1:10, washed with water at 5 ℃, 20 ℃, 50 ℃ 30 minutes, the higher the temperature, the higher the chlorine removal rate It can be seen.

TABLE 6

Fly ash Water washing temperature (℃) 5 20 50 Ilsan Fly Ash 92.5% 96.5% 98.0% Busan fly ash 90.7% 94.7% 97.0%

  In addition, Table 7 shows that the chlorine removal rate is almost the same even if the solid ratio is increased as a result of experiment by varying the solid to liquid ratio at a temperature of 50 ° C. and a water washing time of 30 minutes.

TABLE 7

Fly ash Solid: Liquid Ratio (Weight Ratio) 1: 10 1: 5 1: 1 Ilsan Fly Ash 98.0% 97.8% 97.7% Busan fly ash 97.0% 96.5% 96.3%

That is, when the carbonic acid gas and sodium carbonate were supplied with carbonate ions at 50 ° C. with a solid to liquid ratio of 1: 1, the chlorine removal was 97.7 wt% and 96.3 wt%, respectively. As shown in Table 8, heavy metal concentrations were not detected or trace amounts were detected, indicating that they were environmentally stabilized.

TABLE 8

sample Whether carbon dioxide and sodium carbonate are injected pH Concentration of heavy metals in solution (ppm) cadmium lead Copper Crumb Ilsan fly ash No injection 12.5 0.09 17.8 0.11 0.21 Infusion 10.1 Not detected Not detected ND 0.17 Busan fly ash No injection 6.8 35.5 10.28 0.10 0.29 Sodium carbonate 10.0 0.08 Not detected Not detected Not detected

Therefore, considering that the chlorine content limit in the cement raw material is 100mg / kg, it is possible to use the fly ash less than 10% by weight of the cement raw material by removing the chlorine component by washing the municipal waste incineration fly ash with washing or injecting carbonate ions. Will be.

As described above, according to the present invention, the incineration fly ash generated during the incineration of domestic wastes is washed with water or supplied with carbonate-containing substances such as carbon dioxide and sodium carbonate to be washed with water, thereby safely treating the cement without generating pollution. It can be used as a raw material to be manufactured, the washing process of the fly ash is simple, the processing time is quick, and most of the chlorine component in the treated fly ash is removed.

In addition, since the content of heavy metal ions in the waste water is dissolved below the environmental regulations, it is not necessary to treat the waste water separately, so that the flushed fly ash can be used as a filler for ascon as well as cement raw materials.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as provided by the following claims. I would like to clarify that those who have knowledge of this can easily know.

1 is a diagram showing the results of XRD analysis of fly ash in household waste incinerator

2 is a diagram showing the solubility according to the pH of the heavy metal hydroxide

3 is a washing process of the fly ash in the municipal waste incineration ash according to the present invention

Claims (5)

In the method of treating incineration ash, A method for treating fly ash according to incineration of domestic waste in which the fly ash generated from the domestic waste incinerator is used as a raw material for cement to be washed while supplying a carbonic acid supply material, and the solids are collected after filtration. The method of claim 1, wherein the fly ash is rinsed with water for 15 minutes or more in a temperature range of 5 to 50 ° C. at a fly ash: water ratio of 1:10 to 1: 1. delete delete The method of claim 1, wherein the carbonic acid ion feed material is selected from the flue gas containing carbon dioxide gas generated during the incineration of municipal waste and the flue gas containing carbon dioxide gas generated in the cement manufacturing process is used for incineration of municipal waste. Treatment method of fly ash according to.