JP3509667B2 - Method for determining the amount of chemicals for incineration fly ash treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the incineration fly ash generated from the incineration facility is processing the flue gas by a high reactivity lime containing an amine and / or alcohol based component, phosphorus
The present invention relates to a method for quickly and accurately determining an appropriate addition amount of a chemical agent capable of reliably preventing elution of heavy metals from the incineration fly ash when an acid heavy metal-immobilized chemical agent is added.

[0002]

[Background Art] HCl generated when garbage is incinerated
It is obliged to treat the acidic exhaust gas containing etc. so that the contained HCl becomes a certain concentration or less prior to release from the chimney. Conventionally, neutralization with slaked lime (JIS special slaked lime) has been a common method for treating the acidic exhaust gas concentration below the regulation value.

On the other hand, incineration fly ash generated from a garbage incinerator or the like prevents elution of heavy metals such as lead contained in the incineration fly ash, whether it is dumped or reused. (Immobilization) is obligatory, and as a simple and reliable method, a method of treating with a heavy metal immobilization agent is adopted. When treating incineration fly ash with this heavy metal immobilization agent, add heavy metal immobilization agent to the incineration fly ash without excess or deficiency to ensure elution of heavy metals from the incineration fly ash with the minimum amount of chemicals required. In order to prevent this, it is necessary to know the appropriate addition amount in advance.

Conventionally, a method for measuring the acid consumption of fly ash has been proposed in order to grasp the appropriate amount of such a heavy metal-immobilizing agent (Japanese Patent Laid-Open No. 8-101186).

By the way, in the treatment of acidic exhaust gas by the above-mentioned JIS special slaked lime, since JIS special slaked lime has poor reactivity, in order to neutralize the acidic exhaust gas so as to be below the regulation value, It is necessary to add an excessive amount of JIS special slaked lime. As a result, unreacted residual slaked lime remains, which increases the volume and weight of the incinerated fly ash collected by a dust collector or the like, and further increases the amount of waste.

In order to solve this problem, in recent years, highly reactive slaked lime has been developed which has a fine particle size and thus a large specific surface area, and thus has higher contact efficiency with incinerated fly ash than JIS special slaked lime. It has come to be used frequently. This highly reactive slaked lime is obtained by adding alcohol and amine in the production process and increasing the reactivity by controlling the particle size and specific surface area (JP-A-9-110425, 9).
-156969, 10-101331,
10-95613, 10-25112).

[0007]

The incineration fly ash discharged from an incinerator that treats acidic exhaust gas with JIS special slaked lime is subjected to an acid according to the method described in JP-A-8-101186. When the amount of consumption is measured and the amount of drug added is predicted based on the amount of acid consumed, the appropriate amount added can be quickly and accurately known. Even if this method is applied as it is to incineration fly ash discharged from an incinerator that treats acidic exhaust gas with slaked lime, it is not possible to obtain an appropriate addition amount that can reliably prevent elution of heavy metals. There was found.

The present invention solves the above-mentioned conventional problems, and phosphoric acid heavy metals are added to incineration fly ash generated from incineration facilities treating exhaust gas with highly reactive slaked lime containing amine and / or alcohol components. It is an object of the present invention to provide a method for quickly and accurately determining an appropriate addition amount of the drug, which can surely prevent elution of heavy metals from the incinerated fly ash when the immobilized drug is added.

[0009]

The method for determining the amount of chemicals for treating incineration fly ash according to the present invention is generated from an incineration facility treating exhaust gas with highly reactive slaked lime containing amine-based and / or alcohol-based components. The acid consumption is 300 mg-C
Addition of phosphate heavy metal immobilizing chemical to incineration fly ash below aCO ₃ / g-ash to prevent elution of heavy metals from the incineration fly ash
A method for determining an appropriate addition amount of the chemical for the treatment to stop , wherein the acid consumption A (mg-C of the incinerated fly ash is determined.
ACO ₃ / g- ash) was measured, based on this value, the following formula
According, and determines the該適positive amount T (% by weight / ash). T = (0.1-0.3) × A

The present inventors have incinerated fly ash derived from highly reactive slaked lime generated from an incinerator treating exhaust gas with highly reactive slaked lime containing amine and / or alcohol components (hereinafter referred to as “highly reactive slaked lime”). In the same manner as incinerated fly ash discharged from an incinerator that treats acidic exhaust gas with JIS special slaked lime (hereinafter sometimes referred to as “normal fly ash”). As a result of investigating the reasons why heavy metal elution cannot be reliably prevented when processing with different chemical specifications, it was found that highly reactive slaked lime contained amine and alcohol-based components contained in incineration fly ash. It was found that there is an effect of promoting elution of heavy metals. This effect is presumed to be due to the fact that amines and alcohol components form complexes with heavy metals in the incineration fly ash.

In accordance with the method of the present invention, highly reactive slaked lime is
Acid consumption was usage 300mg-CaCO ₃ / g- ash less
The acid consumption of incineration fly ash was measured and this acid consumption A (mg
-CaCO ₃ / g- ash) on the basis, phosphorus according to the following following formula
By determining the appropriate addition amount T (wt% / ash) of the acid heavy metal immobilization chemical and performing chemical treatment of the incineration fly ash based on this result, the minimum amount of chemical addition from the incineration fly ash is required. Elution of heavy metals can be reliably prevented.

[0012] T = (0. 1 ~0. 3) × A

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail below.

In the present invention, the mixing ratio of water and incinerated fly ash is indicated by the solid-liquid ratio, that is, the weight ratio of water to the incinerated fly ash (hereinafter sometimes referred to as “L / S”).

First, a method for measuring the acid consumption of incinerated fly ash will be described.

The acid consumption is measured according to JIS K0101 acid consumption (pH 8.3) for the solution obtained by mixing fly ash to be measured with water.

Here, the mixing ratio of water and fly ash, that is,
The solid-liquid ratio (L / S) is 10 to 1000, particularly 100 to 1.
000, particularly about 500 to 1000 is preferable.

Specifically, it is carried out according to the following procedures (i) to (iii).

(I) First, a certain amount of fly ash is sampled.

(Ii) For this fly ash, for example, L / S
Add water (preferably pure water or distilled water) so that becomes 1000, and stir well.

(Iii) The suspended liquid is removed by a method such as filtering the mixed solution using filter paper, and the acid consumption of the filtrate is measured according to the acid consumption (pH 8.3) of JIS K0101. This measured value (mg-CaCO ₃ / L) corresponds to the acid consumption in 1 g of fly ash.

The series of operations (i) to (iii) are usually completed within 30 minutes.

In the present invention, the acid consumption A (mg-CaCO ₃ / g) of the highly reactive fly ash thus obtained is determined.
-Based on (ash), the appropriate addition amount T (wt% / ash) of the phosphate-based heavy metal fixing agent is determined. Equation to determine the proper amount, the type of phosphate heavy metal immobilization agents used, it varies depending on the presence or absence of a combination of pH-adjusting agent such as, you calculated under <br/> SL (1).

T = (0.1 to 0.3) × A ( 1 )

Example 1 Highly reactive fly ash No. 1 discharged from a municipal waste incinerator in which acidic exhaust gas is neutralized with highly reactive slaked lime added with an amine-based chemical. Normal fly ash No. 1 discharged from a municipal waste incinerator that neutralizes acidic exhaust gas with K-1, K-2, K-3 and JIS special slaked lime. T-1, T-2, T-3
In addition, an experiment was conducted to measure the acid consumption and to investigate the elution prevention effect of heavy metals by the phosphate heavy metal immobilization agent.

The contents of amine components in the highly reactive slaked lime and JIS special slaked lime used for the treatment of acidic exhaust gas are as shown in Table 1.

[0027]

[Table 1]

[0028] "Ashnite R303 (registered trademark)" manufactured by Kurita Kogyo Co., Ltd. was used as the phosphate heavy metal fixing agent.

For each highly reactive fly ash and normal fly ash used as a sample, pure water was added according to the above-mentioned methods (i) to (iii) (however, the solid-liquid ratio L / S was 1000). Table 2 shows the measured acid consumption and other component contents.
As shown in

[0030]

[Table 2]

In addition, for each fly ash sample, the results of the elution test by the Environmental Agency Notification No. 13 test method without treatment (without adding heavy metal immobilizing chemical) and the landfill standard values are shown in Table 3.
As shown in

[0032]

[Table 3]

To each fly ash sample, 20% by weight of pure water and a predetermined amount of phosphoric acid heavy metal immobilizing agent were added to the fly ash and stirred thoroughly with a spatula. The dissolution test was performed by the method, and the results are shown in Table 4 together with the case of no treatment.

Further, from the results of Table 4, the relationship between the acid consumption of each fly ash sample and the addition amount of the phosphate heavy metal immobilizing agent is shown in FIG.
Summarized in

[0035]

[Table 4]

From FIG. 1, it is clear that the amount of phosphoric acid heavy metal immobilization agent that satisfies the landfill reference value is higher in the high-reactive fly ash than the normal fly ash, and the high-reactive fly ash is normally fly ash. It can be seen that different proper addition amounts are shown. In addition, for highly reactive fly ash, there is a correlation between the acid consumption and the amount of heavy metal immobilization agent that satisfies the landfill standard value, and a calibration curve showing the relationship between the acid consumption and the appropriate amount of addition is prepared. Thus, it can be seen that the appropriate addition amount of the heavy metal-immobilized drug can be easily known based on the calibration curve.

Example 2 Based on the calibration curve of FIG. 1 prepared in Example 1, a test for confirming the appropriate addition amount was conducted.

First, a highly reactive fly ash K-4 different from the highly reactive fly ash K-1 to K-3 was prepared.

Example 1 of this highly reactive fly ash K-4
The acid consumption was measured in the same manner as in 141 mg-C.
It was aCO ₃ / g- ash. About this highly reactive fly ash K-4, the appropriate addition amount of a phosphate heavy metal fixed chemical | medical agent is determined to be about 18 weight% from the calibration curve of FIG.

On the other hand, for this highly reactive fly ash K-4,
In the same manner as in Example 1, a predetermined amount of a phosphate heavy metal immobilizing agent was added, and a dissolution test was conducted by the Environmental Agency Notification No. 13 test method. The results are shown in Table 5, and the phosphate heavy metal When 18% by weight of the immobilized drug was added, the landfill standard value was satisfied, and it was confirmed that the appropriate addition amount could be determined from the acid consumption.

[0041]

[Table 5]

[0042]

As described in detail above, according to the method of the present invention, incineration fly ash generated from an incineration facility treating exhaust gas with highly reactive slaked lime containing amine and / or alcohol components, When the phosphoric acid heavy metal-immobilized chemical is added and processed, it is possible to quickly and accurately determine the appropriate amount of the chemical that can reliably prevent elution of heavy metals from the incineration fly ash.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the acid consumption of fly ash and the appropriate addition amount of a heavy metal immobilizing agent.

──────────────────────────────────────────────────── ─── Continued from the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B09B 3/00-5/00

Claims (2)

(57) [Claims] 1. Acid consumption generated from an incineration facility treating exhaust gas with highly reactive slaked lime containing amine-based and / or alcohol-based components is 300 mg-CaCO ₃ /
Treatment to prevent elution of heavy metals from the incineration fly ash by adding a phosphoric acid heavy metal immobilizing agent to the incineration fly ash below g-ash
Is a method for determining an appropriate amount of the chemical to be added, the acid consumption A (mg-CaCO ₃ / g-ash) of the incinerated fly ash
And determining the appropriate addition amount T (wt% / ash) according to the following formula based on this value. T = (0.1-0.3) × A 2. The method of claim 1, the addition amount determining method of incineration fly ash treatment agent heavy metal and said lead der Rukoto.