JPH1060432A - Method for producing backfill soil using polymer sewage sludge incineration ash - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an inexpensive method for producing backfill soil using high-polymer sewage sludge incineration ash. SOLUTION: A method for producing backfill soil using incineration ash of polymer sewage sludge characterized by comprising the following steps. (A) a step of kneading a mixture containing polymer-based sewage sludge incineration ash, a calcium compound in an amount of 5 to 30 parts by weight based on 100 weight of the polymer-based sewage sludge incineration ash, and (b) mixing the kneaded mixture; Granulating step for granulation (c) A step of curing the granulated material by a carbonation curing reaction

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the effective use of sewage sludge incineration ash generated from a sewage purification plant, and more particularly to a method for producing backfill soil for civil engineering work using polymer sewage sludge incineration ash. .

[0002]

2. Description of the Related Art Conventionally, sewage sludge has been dehydrated using a lime-based dehydration aid obtained by adding iron chloride or the like to lime and then incinerated. In recent years, instead of such lime-based dewatering aids, dehydration treatment using a polymer-based flocculant that has a large effect of coagulating sewage sludge and a large volume reduction effect after incineration by combustion and has a small load on incinerators has become mainstream. It is becoming.

[0003] Incineration ash using a lime-based dehydration aid is called lime-based sewage sludge incineration ash, and incineration ash using a polymer-based flocculant is called polymer-based sewage sludge incineration ash. Has a particle size of D50 of 0.1 to several μm, which is extremely fine and easily scattered. In the near future, the shortage of such sewage sludge incineration ash, which will be generated in large quantities every day, will inevitably become a serious problem, and it is inevitable that it will be used for inexpensive treatment technology for solidifying it and making it easier to handle. There is a strong demand for the development of utilization technologies to be used.

Japanese Patent Application Laid-Open No. 56-2899 discloses that lime-based sewage sludge incineration ash is molded by using water or the like as a binder and then hardened by a carbonation hardening reaction using a calcium component contained in the incinerated ash. There is disclosed a method of performing a solidifying treatment on a lump having the same.

On the other hand, there is no disclosure of a method of solidifying the polymer-based sewage sludge incineration ash, which will become the mainstream in the future, and some techniques for using the same have been proposed. Not something.

[0006] Therefore, if polymer sewage sludge incineration ash can be applied to backfill soil in civil engineering work, it is expected that its effective use will be promoted and lead to mass consumption.

[0007]

However, there is no disclosure of a method for applying incinerated polymer sewage sludge ash to backfill soil in civil engineering work.

[0008] An object of the present invention is to provide a method for producing backfill soil using incinerated ash from a polymer sewage sludge.

The characteristics required for backfill soil are not always clearly defined, but the subgrade soil bearing capacity ratio CBR, which indicates the strength of subgrade soil specified in JIS A 1211 as a measurement method thereof, is required. Since it has been confirmed that 10% or more of them are often applied to backfill soil, CBR ≧ 1
0% was used as an evaluation criterion for applying backfill soil.

[0010]

The above object is achieved by a method for producing backfill soil using incinerated ash from a polymer sewage sludge, comprising the following steps. (B) a step of kneading a mixture containing a polymer-based sewage sludge incineration ash, 5 to 30 parts by weight of a calcium compound with respect to 100 weight of the sewage sludge incineration ash, and water (b) granulating the kneaded mixture (C) a step of curing the granulated product by a carbonation hardening reaction A mixture containing incinerated polymer sewage sludge ash, a calcium compound and water is kneaded, and after granulation, hardened by a carbonation hardening reaction. In this case, the particle size distribution can be easily controlled, and the backfill soil can be produced without causing the coagulation of the secondary particles during the carbonation hardening reaction. Sewage sludge incineration ash weight 10
It is necessary to be 5 to 30 parts by weight based on 0. If it is less than 5 parts by weight, the CBR does not become 10% or more. Further, adding more than 30 parts by weight is not preferable because not only the effect is saturated, but also the utilization rate of incinerated ash decreases.

When soil or sand having a particle size of 5 mm or less is added after the granulation step (b), the filling rate when compacting the backfill soil, that is, compacting property is improved. Particle size is 5mm
When the soil or sand exceeds the limit, the continuity of the particle size distribution of the produced soil is lost, and the site used as the soil is limited. In addition, if the addition time is before the granulation step, the granular material is coarsened at the time of granulation, so it is necessary to perform the addition after the granulation step. Therefore, it is preferable to add it after the carbonation hardening reaction, since it increases the amount of carbon dioxide and the amount of carbon dioxide gas used.

The amount of addition is preferably 20 to 40 parts by weight based on the total weight of sewage sludge incineration ash and calcium compound of 100. If the amount is less than 20 parts by weight, sufficient compactibility cannot be ensured, and if the amount exceeds 40 parts by weight, the effect is saturated and the utilization rate of incinerated ash decreases.

In order to improve the compaction property, water may be added after the step (c) of curing by a carbonation curing reaction. When the water is added before the granulation step, granulation cannot be performed, and before the carbonation hardening reaction, the carbonation hardening reaction time significantly increases. Therefore, it is necessary to add water after the carbonation hardening reaction. When the amount of addition is defined as the difference between the water content of 80 to 120% of the optimum water content of the granular material cured by the carbonation hardening reaction measured by JIS A1210 and the water content after the carbonation hardening reaction, 0.9 The above compaction filling ratio is obtained.

As the calcium compound, cements,
One or a mixture of two or more selected from slaked lime, quicklime, converter slag, electric furnace slag, and calcium ferrites can be applied.

When the content of water is 30 to 60 parts by weight based on the total weight of the incinerated ash and the calcium compound of the polymer sewage sludge, the mixture can be easily granulated by the particle size distribution required for the backfill soil. When the content of water exceeds 60 parts by weight, the mixture may be in a slurry state and may not be granular, and when the content is less than 30 parts by weight, the binder effect may be weak and aggregation may not be performed.

[0016] To a mixture containing incinerated polymer sewage sludge, a calcium compound and water, 15 parts by weight or less of gel-like particles are added to a total weight of 100 of the polymerized sewage sludge incinerated ash, calcium compound and water, Increased water retention and viscosity,
The backfill soil required of such characteristics can be manufactured. 1
If the amount exceeds 5 parts by weight, the particle size distribution required for the backfill soil may be too fine when the amount of the calcium compound added is small.

[0017] The carbonation curing reaction, 10 vol of CO _2.
% Or more in an atmosphere temperature range of 20 to 90 ° C. and an atmosphere humidity of 30 to 80% Rh, within 24 hours, which is the upper limit of a practical reaction time, C 10% or more.
BR is obtained.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A mixture containing incinerated polymer sewage sludge ash, a calcium compound, and water is kneaded with a mixer such as a pan type, a tilting type, a forced biaxial type, and a rocking type.

Granulation of the kneaded mixture can be performed by the above mixer, rotary drum, dish granulator, rolling granulator, oscillating granulator, fluidized bed granulator, or the like.

The carbonation hardening reaction can be performed using the above-mentioned mixer, granulator, rotary pot, belt conveyor, moving basket, or the like as a reaction tank.

As a CO ₂ gas source required for the carbonation hardening reaction, not only purified CO ₂ gas but also exhaust gas from a sewage sludge incinerator may be used.

The humidity of the reaction tank for the carbonation hardening reaction can be adjusted by blowing steam, spraying mist, flowing a humidifying gas, flowing a drying gas, or the like.

[0023]

【Example】

(Example 1) A mixture obtained by adding 0 to 30 parts by weight of cement to polymer sewage sludge incineration ash to polymer incineration ash by weight was added to a pan-type mixer and mixed for 30 seconds. Total weight of sewage sludge incineration ash and cement 1
00 After 1 minute kneaded water 50-52 parts by weight with respect to, 5 minutes after granulation in 30rpm in a drum granulator, CO ₂ 20 vol in a drum granulator. %, Ambient temperature 40
The carbonation curing reaction was carried out at a temperature of 20 ° C. for 20 to 1440 minutes. Then, the CBR and the particle content of 75 μm or less were measured.

The results are shown in Table 1. In a sample obtained by adding 5 to 30 parts by weight of a cement, which is a calcium compound, to the polymer sewage sludge incineration ash prepared by the method of the present invention, the reaction time is within 300 minutes. Yields a CBR of 10% or more. On the other hand, when 3 parts by weight of cement is added or not added, CBR of 10% or more cannot be obtained even when the reaction is performed for 1440 minutes (24 hours).

In a sample having a CBR of 10% or more, 7
The particle content of 5 μm or less is small and suitable as backfill soil.

[0026]

[Table 1]

Example 2 5-15 parts by weight of cement, slaked lime, quicklime, converter slag, electric furnace slag and calcium ferrite were added to the polymer-based sewage sludge incineration ash with respect to 100 weight of the polymer-based sewage sludge incineration ash. The mixture to which the calcium compound was added was put into a pan-type mixer and mixed for 30 seconds. Then, 49 to 64 parts by weight of water was added to the total weight of the incinerated ash and the cement of polymer-based sewage of 100 and kneaded for 1 minute. After granulating for 5 minutes at 30 rpm with a granulator, CO ₂ 20 vol. %, 60 at ambient temperature of 40 ° C
The carbonation hardening reaction was performed for minutes. And CBR and 75μ
The particle content of not more than m was measured.

The results are shown in Table 2. In each of the samples to which various calcium compounds prepared by the method of the present invention were added, CBR of 10% or more was obtained, and 75% of 30% or less was obtained.
The following particle content is obtained: In particular, the addition of a compound having a high calcium content such as slaked lime or quick lime has a large effect even in a small amount.

[0029]

[Table 2]

(Example 3) A mixture obtained by adding 5 to 20 parts by weight of cement to the polymer sewage sludge incineration ash with respect to the weight of the polymer sewage sludge incineration ash was put into a pan mixer and mixed for 30 seconds. 49 to 52 parts by weight of water are added to the total weight of the polymer sewage sludge incineration ash and cement, and 5 to 15 weight is added to the total weight of the polymer sewage sludge incineration ash, cement and water. Part of the clay, which is a gel-like particle, was added and kneaded continuously for 1 minute, and then 30 minutes with a drum granulator.
After granulation for 5 minutes at rpm, CO ₂ 20
vol. %, And the carbonation hardening reaction was performed at an ambient temperature of 40 ° C. for 40 minutes and 300 minutes depending on the amount of cement added.
Then, the CBR and the particle content of 75 μm or less were measured.

The results are shown in Table 3. In each of the samples to which the clay prepared by the method of the present invention was added, CB of 10% or more was used.
R is obtained, and the particle content of 75 μm or less is small. In addition, these samples have excellent water retention and viscosity.

[0032]

[Table 3]

Example 4 A mixture obtained by adding 10 parts by weight of cement to 100 parts by weight of polymer-based sewage sludge incineration ash to polymer-based sewage sludge incineration ash was charged into a pan-type mixer.
After mixing for 0 seconds, 45 parts by weight of water was added to the total weight of the polymer sewage sludge incineration ash and cement, followed by kneading for 1 minute, granulation at 30 rpm with a drum granulator for 5 minutes,
CO ₂ 20 vol. %, And a carbonation hardening reaction was performed at an ambient temperature of 40 ° C. for 25 minutes. Then, Kanto loam soil or mountain sand having a particle size of 5 mm or less is used in an amount of 5 to 5 with respect to the total weight of the incineration ash of polymer sewage sludge and cement, 100
0 parts by weight, CBR, particle content of 75 μm or less,
The filling factor after compaction was measured.

In the case where 30 parts by weight of mountain sand is added, the addition time is set at the time of initial kneading, before the carbonation hardening reaction,
The effect of the time of addition was investigated by measuring the filling factor after compaction instead of after the carbonation hardening reaction.

The results are shown in Tables 4 and 5. When Kanto loam soil or mountain sand is added after the carbonation hardening reaction, the compaction property is improved as compared with the case where it is not added. In particular, when the addition amount is 20 parts by weight or more with respect to the total weight of the incineration ash of polymer sewage sludge and cement, the filling factor after compaction becomes 0.9 or more, and excellent compactibility is exhibited. Further, even if the added amount exceeds 40 parts by weight with respect to the total weight of the incineration ash of polymer sewage sludge and cement, the effect is saturated. Even if Kanto loam soil or mountain sand is added, 1
A CBR of 0% or more and a particle content of 75% or less of 31% or less can be obtained, and a satisfactory backfill soil can be obtained.

If the mountain sand is added during the initial kneading, the particles become coarse during granulation and cannot be used as backfill soil.
Also, before the carbonation hardening reaction, no problem occurs in the compaction property, but the processing time becomes longer and inefficient as compared with the case where it is added after the carbonation hardening reaction.

[0037]

[Table 4]

[0038]

[Table 5]

Example 5 A mixture obtained by adding 10 parts by weight of cement to 100 parts by weight of polymer sewage sludge incineration ash to polymer sewage sludge incineration ash was put into a pan mixer.
After mixing for 0 seconds, 45 parts by weight of water (referred to as initial added water) is added to the total weight of the incineration ash of polymer sewage sludge and cement for 100 minutes, kneaded for 1 minute, and 30 rpm by a drum granulator.
After granulating for 5 minutes at 20 m, CO _{2 20} vo in a drum granulator
l. %, And a carbonation hardening reaction was performed at an ambient temperature of 40 ° C. for 25 minutes. Then, water (referred to as post-addition water) is added to the polymer-based sewage sludge incineration ash and cement in a total weight of 5 to 2 to 100%.
5 parts by weight, CBR, particle content of 75 μm or less,
The filling factor after compaction was measured.

Table 6 shows the results. When post-addition water is added after the carbonation hardening reaction, compaction properties are improved as compared with the case where no water is added. In particular, the amount of addition is at least 10 parts by weight based on the total weight of the polymer sewage sludge incineration ash and cement, that is, J of the particulate matter hardened by the carbonation hardening reaction.
The optimal water content of 80 to 12 measured by IS A 1210
When the difference between the water content of 0% and the water content after the carbonation hardening reaction is determined, the filling factor after compaction becomes 0.9 or more, and excellent compactibility is exhibited. In addition, even if the post-addition water is added, a CBR of 10% or more and a particle content of 75% or less of 20% can be obtained, and no problem can be obtained as backfill soil.

[0041]

[Table 6]

Example 6 Sample No. 1 shown in Table 1 was used. Using the sample after granulation of Example 4, CO
₂ is 3-80 vol. %, Ambient temperature is 10 to 100
The reaction time dependency of CBR was investigated by changing the temperature and the ambient humidity to 20 to 90% Rh. In addition, CO ₂ 10 vol.
%, An atmospheric temperature of 60 ° C., and an atmospheric humidity of 60% Rh as standard conditions, and other conditions when certain conditions are changed are performed under the standard conditions.

FIG. 1 shows the reaction time dependence of CBR when CO ₂ is changed. FIG. 2 shows the reaction time dependence of CBR when the ambient temperature is changed.

FIG. 3 shows the CBR when the atmospheric humidity was changed.
Shows the reaction time dependence of From Fig, 10Vo the CO ₂
l. % Or more, an atmosphere temperature of 20 to 90 ° C., and an atmosphere humidity of 30 to 80% Rh, CBR of 10% or more can be obtained within 24 hours, which is the upper limit of a practical reaction time.

[0045]

As described above, the present invention is configured as described above, so that it is possible to provide a method for producing backfill soil using incinerated ash from polymer sewage sludge.

[Brief description of the drawings]

FIG. 1 is a diagram showing the reaction time dependence of CBR when CO ₂ is changed.

FIG. 2 is a diagram showing the reaction time dependence of CBR when the ambient temperature is changed.

FIG. 3 is a diagram showing the reaction time dependence of CBR when the atmospheric humidity is changed.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C09K 17/12 F23J 1/00 A F23J 1/00 B09B 3/00 301M // C09K 103: 00

Claims (10)

[Claims] 1. A method for producing backfill soil using incinerated ash from polymer sewage sludge, comprising the following steps: (A) a step of kneading a mixture containing a polymer-based sewage sludge incineration ash, 5 to 30 parts by weight of a calcium compound with respect to 100 weight of the sewage sludge incineration ash, and water (b) granulating the kneaded mixture (C) a step of curing the granulated material by a carbonation curing reaction 2. The backfill soil using the polymer sewage sludge incineration ash according to claim 1, wherein soil or sand having a particle size of 5 mm or less is added after the granulation step (b). Manufacturing method. 3. The total weight of sewage sludge incinerated ash and calcium compound is 100 when soil or sand having a particle size of 5 mm or less is added.
The method for producing backfill soil using incinerated ash of polymer sewage sludge according to claim 2, wherein the amount is 20 to 40 parts by weight based on the weight of the incinerated ash. 4. The method according to claim 1, wherein water is added after the step (c) of curing by a carbonation curing reaction.
A method for producing backfill soil using the polymer sewage sludge incineration ash according to any one of claims 1 to 3. 5. The amount of water to be added is the difference between the water content of 80 to 120% of the optimum water content ratio measured by JIS A 1210 of the granules hardened by the carbonation hardening reaction and the water content after the carbonation hardening reaction. A method for producing backfill soil using the polymer sewage sludge incineration ash according to claim 4. 6. The method according to claim 1, wherein the calcium compound is one or a mixture of two or more selected from cements, slaked lime, quicklime, converter slag, electric furnace slag, and calcium ferrites. A method for producing backfill soil using the polymer sewage sludge incineration ash according to claim 5. 7. The content of water in the mixture containing incinerated polymer sewage sludge ash, calcium compound and water is 30 to 60 based on the total weight of sewage sludge incinerated ash and calcium compound of 100.
The method for producing backfill soil using the polymer sewage sludge incineration ash according to any one of claims 1 to 6, which is part by weight. 8. A mixture containing incinerated ash of a polymer-based sewage sludge, a calcium compound and water is added to the mixture in an amount of 1 to 100% by weight of the mixture.
8. The method for producing backfill soil using polymer sewage sludge incineration ash according to claim 1, wherein 5 parts by weight or less of gel-like particles are added. 9. 9. The method according to claim 8, wherein the gel particles are silica gel or clay mineral. 10. The carbonation hardening reaction is performed by adding 10 vol of CO ₂ .
l. The polymer system according to any one of claims 1 to 9, wherein the polymerization is performed in an atmosphere containing 20% to 90% Rh at an atmosphere temperature of 20 to 90 ° C and an atmosphere humidity of 30 to 80% Rh. A method for producing backfill soil using sewage sludge incineration ash.