JP2003212615A - Method for melt treatment of sludge incineration ash and method for manufacturing rigid aggregate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely lower the viscosity of slag when sludge incineration ash is subjected to melt treatment. <P>SOLUTION: The basicity (CaO/SiO<SB>2</SB>) of the slag formed by the melt treatment is controlled in the range of 0.5-1.0 and also the magnesium content in the slag is regulated in 3-20 mass% expressed in terms of MgO by the addition of a magnesium component. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melting treatment method useful for treating sludge incineration ash, and a method for producing hard aggregate using this treatment method.

[0002]

2. Description of the Related Art Conventionally, sludge (sewage sludge, etc.) is incinerated in an incinerator such as a circulation furnace for sanitization and volume reduction, and the obtained incinerated ash is melted in a melting furnace (swirl melting furnace, electric melting furnace). Furnace etc.)
It is melted and slag is made. In such a melting process, it is required to reduce the viscosity of the slag in order to improve the handleability of the molten slag in the melting furnace.

For example, in Japanese Unexamined Patent Publication No. 10-176822, a basicity adjusting agent is added to the furnace to adjust the basicity of the molten slag to 0.5 to 0.7 to reduce the viscosity of the molten slag. It is disclosed.

[0004]

However, according to the studies by the present inventors, even if the basicity of the molten slag is adjusted to 0.5 to 0.7, the viscosity of the slag may not be sufficiently lowered. It turned out to be.

The present invention has been made in view of the above circumstances, and an object thereof is to surely reduce the viscosity of slag or to increase the value of slag obtained by melt processing.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that when the basicity is adjusted to a predetermined range and magnesium is contained in a predetermined amount or more, it melts. You can surely reduce the viscosity of the slag,
Moreover, they have found that when the molten slag having a low viscosity is solidified, an extremely hard slag can be obtained, and an extremely useful aggregate can be obtained, and the present invention has been completed.

That is, the sludge incineration ash melting treatment method according to the present invention controls the basicity (CaO / SiO ₂ ) of the slag produced by the melting treatment within the range of 0.5 to 1.0, and the magnesium component. Is added to adjust the magnesium content in the slag to 3 to 20 mass% in terms of MgO. In the melting treatment, it is desirable that the total content of silicon, calcium, and magnesium is 45% by mass or more in terms of SiO ₂ + CaO + MgO. Further, when a swirling melting furnace is used, it is desirable to add a basicity adjusting agent having a density or a ratio of particles having a particle size of 10 μm or more which is equal to or higher than that of the incinerated ash.

The present invention also includes a method for producing a hard aggregate by cooling and solidifying the slag obtained by the above-mentioned melt processing method.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION [Apparatus] The melting treatment of the present invention can be carried out, for example, according to the apparatus shown in FIG. In the example of FIG. 1, the cake hopper 1 and the residue hopper 2 receive the sludge cake, and the sludge cake is supplied to an incinerator (circulation furnace in this example) 3 and burned. The incineration ash produced by the combustion is extracted from the upper part of the incinerator together with the exhaust gas, and separated into the incineration ash and the exhaust gas by the cyclone 4. The exhaust gas from the cyclone 4 is supplied to the second combustion chamber 5 to be completely combusted, and then the plurality of (two in this example) heat exchangers 6a and 6b are used to collect dust (in this example, an electric power). It is supplied to the dust collector) 7 to remove a little residual incinerated ash. Then, after removing harmful components such as HCl and SO _x in the smoke exhaust treatment tower 8, they are released into the atmosphere from the chimney 9.

Then, the incinerated ash separated by the cyclone 4 and the dust collector 7 is supplied to a melting furnace (in this example, a swirling melting furnace) 10 to form slag.

[Incineration Treatment] In the incinerator 3, various sludges can be incinerated. The sludge is not particularly limited as long as it is a sludge containing organic and inorganic components, and includes tap water sludge, sewage sludge (lime-based sludge, polymer-based sludge, etc.), and residue. The sludge is usually incinerated in an incinerator after it is dehydrated into a dehydrated cake.

[Melting Treatment] The incinerator ash produced in the incinerator is separated from the exhaust gas in the cyclone 4 and the dust collector 7 and then in the melting furnace 10 at a temperature of about 1100 to 1500 ° C. (preferably about 1100 to 1400 ° C., further It is preferably melted at 1100 to 1300 ° C.) to form a slag. When converting to slag, the basicity of slag [CaO /
SiO ₂ (mass ratio)] is 0.5 or more (preferably 0.6)
As described above, more preferably 0.7 or more) and 1.0 or less (preferably 0.9 or less). If the basicity of the slag is adjusted within the above range, the viscosity of the slag can be lowered as compared with the case where the basicity deviates from the above range.

When adjusting the basicity, it is not necessary to do anything if the basicity of the incinerated ash is in the above range, but if the basicity of the incinerated ash is out of the above range, a basicity adjusting agent is used. Adjust the basicity by adding (calcium component, silicon component, etc.). For example, the incineration ash of lime-based sewage sludge often has a basicity of about 1 to 8, and therefore a silicon component is often added to reduce the basicity, and the incineration ash of polymer-based sewage sludge has a basicity. Since it is often about 0.1 to 0.5, a calcium component is often added to increase the basicity.

Examples of the calcium component include inorganic compounds [calcium carbonate compounds (inclusive of calcium carbonate, double salts thereof, hydrates thereof, and the like; the same applies hereinafter; for example, limestone), calcium oxide compounds ( Quicklime, etc.), calcium hydroxide compounds (slaked lime, etc.), calcium sulfate compounds, calcium phosphate compounds, calcium chloride compounds, calcium fluoride compounds, etc.], organic compounds (calcium succinate, calcium lactate, etc.) Can be used. The calcium component also includes a composition containing the calcium compound, for example, lime-based incinerated ash, a product (or waste) containing a large amount of the calcium compound (for example, 50 mass% or more), and the like.

The calcium components may be used alone or in combination of two or more. Preferred calcium components are inorganic calcium compounds, particularly CaO-containing components (quick lime etc.) and Ca (OH ₂ ) -containing components (slaked lime etc.).

As the silicon component, a silicon compound,
For example, a silicon oxide compound (such as silica sand) and a silicate compound (such as a sodium silicate compound and a potassium silicate compound) can be exemplified. Further, the silicon component may also be a composition containing a silicon compound, like the calcium component. Examples of the composition include high-polymer incineration ash and products (or waste) containing a large amount (for example, 50% by mass or more) of a silicon compound.

The silicon components may be used alone or in combination of two or more. A preferred silicon component is a silicon oxide compound (such as silica sand).

In the present invention, a compound (or a composition thereof) containing both calcium and silicon may be used as the calcium component or the silicon component. Examples of compounds containing both calcium and silicon include calcium silicate compounds.

When a swirling melting furnace is used as the melting furnace,
As the basicity adjusting agent, the density and the proportion of large particles (in the present invention, the proportion of particles having a particle diameter of 10 μm or more; hereinafter, simply referred to as particle diameter) are equal to or higher than those of incinerated ash. It is desirable to use some. In the swirling melting furnace, the incineration ash is collected on the wall surface and melted by the centrifugal force due to the swirling, so the centrifugal force can be increased reliably and sufficiently by increasing the density and particle size of the basicity adjusting agent. Since the degree adjusting agent can be prevented from coming out of the furnace without being collected on the wall surface, the basicity of the slag can be adjusted more reliably.

The ratio of particles having a particle size of 10 μm or more in the basicity adjusting agent is, for example, about 1.0 to 2.5 times the ratio of particles having a particle size of 10 μm or more in the incineration ash,
It is preferably about 1.0 to 1.5 times. The median particle size of the basicity adjusting agent (50% particle size of the integrated particle size distribution curve)
Is usually about 30 to 100 μm, preferably 30 to 5
It is about 0 μm.

The density of the basicity adjusting agent is not particularly limited as long as it is equal to or higher than the density of the incineration ash, but in relation to the particle size of the basicity adjusting agent or the incineration ash, the basicity adjusting agent has a larger centrifugal force than the incineration ash. The density at which force is generated is preferable.

In the present invention, in the melting process, not only the basicity is controlled, but also the magnesium component is added to increase the magnesium content in the slag. While the viscosity of the slag may not be sufficiently reduced by controlling the basicity alone, the viscosity of the slag can be reliably reduced by increasing the magnesium content after controlling the basicity.

Specifically, according to the present invention, the viscosity of the slag can be set to, for example, about 2.0 Pa · s or less. The viscosity is about 1500 ° C. (preferably about 1400 ° C., more preferably about 13 ° C.).
It is desirable to achieve this (at about 00 ° C.).

The content of magnesium in the slag is Mg
In terms of O, for example, 3 mass% or more (preferably 5 mass%
Or more, more preferably 7 mass% or more, especially 10 mass%
Or more), 20 mass% or less (preferably 15 mass% or less)
It is a degree.

Examples of the magnesium component include magnesium compounds such as inorganic compounds [magnesium carbonate compounds (magnesite, dolomite, balintonite, Neskehonite, lancefortite, etc.), magnesium oxide compounds (magnesia, periclase, kudocanlan). Stone, jammonite, raw dolomite, etc.), magnesium hydroxide-based compound, magnesium sulfate-based compound (epsomite, etc.), magnesium silicate-based compound (monticelic olivine), magnesium chloride-based compound (magnesium chloride, carnallite, etc.), Magnesium bromide compounds, etc.], organic compounds (magnesium acetate compounds, etc.) and the like can be used. The magnesium component contains a composition containing the magnesium compound, for example, a large amount of the magnesium compound (for example, 50% by mass).
Above) The product (or waste) contained is also included.

The magnesium components may be used alone or in combination of two or more. Preferred magnesium component is an inorganic compound (magnesium carbonate compound, magnesium oxide compound, magnesium hydroxide compound,
Magnesium silicate). Particularly preferred magnesium components include magnesium, calcium, and / or
Alternatively, it is a component containing silicon (magnesium / calcium component such as dolomite and raw dolomite, magnesium / silicon component such as magnesium silicate). The magnesium / calcium component and the magnesium / silicon component are useful because they not only increase the magnesium content but can also be used as the basicity adjusting agent.

In the present invention, it is preferable to increase the total content of silicon, calcium and magnesium when adding the basicity adjusting agent and the magnesium component.
If the total content of these elements is increased, the viscosity of the slag can be reduced more reliably.

The silicon, calcium, and the total content of _magnesium, SiO 2, CaO, and in terms of MgO (i.e. SiO _2, CaO, and the total amount of MgO),
It is 45 mass% or more, preferably 55 mass% or more, and more preferably 65 mass% or more. The total amount (SiO
₂ + CaO + MgO) is usually about 90% by mass or less (preferably 80% by mass or less).

When the melting treatment is performed as described above, the viscosity of the slag is lowered, so that the defoaming property of the slag can be enhanced and a dense slag can be obtained. Therefore, the strength of the slag can be increased and the usefulness as an aggregate for concrete can be increased. The hard aggregate manufactured in this manner can reliably satisfy, for example, the specific gravity (2.5 or more), water absorption rate (3% or less), and abrasion loss (40% or less) defined by JISA5005.

When a swirling melting furnace is used as the melting furnace, it is desirable to use a magnesium component having a median particle size and density larger than that of incinerated ash, as with the basicity adjusting agent. The median particle size of magnesium component is
For example, the median particle size of the basicity adjusting agent is preferably about the same.

In the present invention, separate compounds may be used for the basicity adjusting agent and the magnesium component, and one compound (magnesium / calcium component, magnesium / silicon component, etc.) may be used as the basicity adjusting agent and the magnesium component. You may also combine.

The place of addition of the basicity adjusting agent and the magnesium component is not particularly limited, and the incinerator, any place from the incinerator to the melting furnace (for example, incineration ash hopper described later), or anywhere in the melting furnace. You may add.

In the present invention, various devices other than the device shown in FIG. 1 can be used. That is, in the present invention, at least an incinerator, an incinerator ash separator (a cyclone, a dust collector, etc.) and a melting furnace may be provided, and other equipment (cake hopper, residue hopper, heat exchanger, second combustion chamber, exhaust gas) Smoke treatment towers, chimneys, etc.) may be replaced with other equipment capable of performing equivalent functions, shared with other equipment on the same site, or not used.

As the melting furnace, it is desirable to use a swirling melting furnace, but another melting furnace (for example, an electric furnace type furnace) may be used.

Further, in order to easily supply the incineration ash to the melting furnace, an incineration ash hopper, an incineration ash feeder, etc. may be attached.

[0036]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately applied within the scope of the above and the following points. It is of course possible to make changes and implement them, and all of them are included in the technical scope of the present invention.

Experimental Examples 1 to 3 Polymeric sewage sludge was incinerated using the apparatus shown in FIG. 1 and the resulting incinerated ash was melted. More specifically, the additives (basicity adjusting agent, magnesium component) shown in Table 1 were added to the incinerator 3 together with the polymeric sewage sludge so that the composition of the incinerated ash was as shown in Table 1 below. This incineration ash is swirling and melting furnace 10
The viscosity of the slag that was melted and discharged was measured. The results are shown in Figure 2.

[0038]

[Table 1]

As is clear from FIG. 2, the higher the MgO content, the higher the MgO content and CaO + SiO.
_The larger the total amount of ₂ + MgO, the lower the viscosity of the slag can be.

Table 2 shows the characteristics of the aggregate obtained by cooling and solidifying the slag slag.

[0041]

[Table 2]

As is clear from Table 2, the higher the MgO content in the melting process, especially the higher the MgO content and the higher the total amount of CaO + SiO ₂ + MgO, the harder the aggregate obtained, and JIS A5005. Satisfies the standards specified in.

Experimental Examples 4 to 7 Using the apparatus of FIG. 1, together with the polymeric sewage sludge (polymeric sewage sludge having a different composition from Experimental Examples 1 to 3) in the incinerator 3,
By adding the additives shown in Table 3, the basicity of incineration ash and CaO
The amount of + SiO ₂ is set as shown in Table 3 below. In addition, when adding the said additive, the magnesium component was also added and variously changed the magnesium content in incineration ash. The obtained incinerated ash was treated in the same manner as in Experimental Examples 1 to 3, and the viscosity of slag was measured at a temperature of 1400 ° C. The results are shown in Fig. 3.

[0044]

[Table 3]

As is clear from FIG. 3, the basicity is 0.5.
In the range of 1.0 to 1.0 (Experimental Examples 5 to 7), the viscosity of the slag can be reduced as compared with the other cases (Experimental Example 4). Moreover, as the MgO content increases (and CaO + SiO ₂ + MgO increases),
The viscosity of the slag can be further reduced. The graph of FIG. 3 is the measurement result at high temperature, and the basicity is 0.
7 (Experimental Examples 6 and 7), a relatively low viscosity (for example, 0.2 Pa · s) may be obtained even if the MgO content is low, but as shown in FIG. Since the viscosity becomes extremely high, the usefulness of increasing the MgO content is further increased.

Experimental Examples 8 to 10 In the incinerator 3, an additive (slaked lime, limestone, or dolomite) having a particle size distribution shown in FIG. 4 was added together with the sludge.
Then, the incineration ash obtained in the incinerator 3 was melted and processed in the swirling and melting furnace 10. When slaked lime (Experimental Example 8) or limestone (Experimental Example 9) in which the proportion of particles having a particle size of 10 μm or more is smaller than that of incinerated ash, the incinerated ash and the additive are separated in the swirling and melting furnace 10. It was Therefore, in the case of slaked lime (Experimental Example 8), the basicity of incinerated ash = 0.70, the basicity of slag = 0.45, and in the case of limestone (Experimental Example 9), the basicity of incinerated ash = 0. .7, basicity of slag = 0.5, and in each case, the basicity of the incinerated ash and the basicity of slag were significantly different. On the other hand, the ratio of particles having a particle size of 10 μm or more is larger than that of incinerated ash (Experiment 1
When 0) is used, the incineration ash and the additive are not separated in the swirling melting furnace 10, and the basicity of the incineration ash (0.7
0) and the basicity of slag (0.65) were almost the same.

[0047]

According to the present invention, the basicity (CaO / Si
Since not only the O ₂ ) is controlled but also the MgO content is adjusted, the slag viscosity during the melting process of the incineration ash can be surely lowered. The slag obtained by this melting treatment is very useful as an aggregate because it is hard.

[Brief description of drawings]

FIG. 1 is a schematic flow chart showing an example of an apparatus used in the present invention.

FIG. 2 is a graph showing the relationship between temperature and viscosity of slag in Experimental Examples 1 to 3.

FIG. 3 is a graph showing the relationship between MgO content and slag viscosity in Experimental Examples 4 to 7.

FIG. 4 is a graph showing the particle size distribution of additives used in Experimental Examples 8 to 10.

[Explanation of symbols] 3: Incinerator 4,7: Incinerated ash separator 10: melting furnace

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F23J 1/00 B09B 3/00 ZAB (72) Inventor Hiroshi Miyamoto 1-3-18 Wakihama-cho, Chuo-ku, Kobe-shi No. Stock Company Kobe Steel Works, Kobe Head Office (72) Inventor Kunio Kataoka 1-3-18 Wakihamacho, Chuo-ku, Kobe City Kobe Steel Co., Ltd. Kobe Head Office (72) Inventor Takahiro Kuno 1 Wakihamacho, Chuo-ku, Kobe City C-No. 3-18 Kobe Steel, Ltd. Kobe Head Office F-term (reference) 3K061 AA05 AB03 AC03 BA05 DA12 NB01 NB06 NB11 NB20 4D004 AA36 BA02 CA29 CA32 CB02 CB31 CC11 DA02 DA03 DA10 DA20 4G012 JF03 JL03 JM04

Claims (4)

[Claims] 1. A method of melting incineration ash of sludge, comprising the basicity (CaO) of slag produced by the melting process.
/ SiO ₂ ) in the range of 0.5 to 1.0, and a magnesium component is added to adjust the magnesium content in the slag to 3 to 20% by mass in terms of MgO. Method. 2. The total content of silicon, calcium, and magnesium is 45 in terms of SiO ₂ + CaO + MgO.
The melt processing method according to claim 1, wherein the content is at least mass%. 3. The melting treatment is performed in a swirling melting furnace, and the basicity adjusting agent has a density and a particle size of 10 μm.
The melt processing method according to claim 1 or 2, wherein a ratio of particles having a particle size of m or more is equal to or more than that of the incinerated ash. 4. A method for manufacturing a hard aggregate by cooling and solidifying slag obtained by the melt processing method according to claim 1.