JPH11104591A - Valuable material recovery from incineration ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of recovering a valuable material stable in characteristics from incineration ash to effectively utilize the incineration ash of municipal refuse or the like. SOLUTION: The incineration ash of the municipal refuse is treated under heating at 800-1100 deg.C (process P1), next, an eluting treatment to water (step P2) is carried out and, after that, a solid material generated in a filtrate obtained by a filtration treatment (process P3) is separated and dried (process P4-P6). By the heat treatment, CaSiO3 is formed in the incineration ash and the incineration ash containing a large quantity of an Al component separated from Ca or Si is obtained. A water soluble material containing Al, dissolved in a filtrate, obtained by eluting the ash and filtering, is oxidized and turned to an alumina deposit. A high purity alumina capable of being supplied to a ceramic field as raw material powder is obtained by separating and drying the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering valuable resources from incinerated ash of municipal solid waste and other waste.

[0002]

2. Description of the Related Art Waste such as municipal solid waste and sewage sludge is first incinerated at about 800 ° C. for volume reduction, and the incinerated ash generated thereby is landfilled. In recent years, incinerated ash has been heated to 1250 to 1500 ° C and melted, and then poured into water to be solidified, thereby further reducing the volume of the molten slag, which has become a landfill. I have. In addition, development has been promoted for effectively utilizing incinerated ash by crushing the molten slag finely and mixing it into an interlocking block or the like.

[0003]

However, the conventional effective use of incinerated ash is limited to the use state in which it is added as a raw material for the above-mentioned interlocking block and the like, and the effective use range is limited. It has become. In other words, incinerated ash from municipal solid waste and the like has a wide variation range in composition, and even if it is converted into molten slag, its mechanical or chemical characteristics vary widely. It is limited to use in products that can be manufactured as such.

[0004] The present invention has been made in view of the above-mentioned problems. For example, valuable materials having stable quality that can be used as a main raw material in the field of ceramics and the like are recovered from incinerated ash.
Accordingly, it is an object of the present invention to provide a method for recovering valuable resources from incinerated ash that can utilize the incinerated ash more effectively.

[0005]

In order to achieve the above object, the present invention provides a method for recovering valuable resources from incinerated ash, which comprises heating waste incinerated ash such as municipal waste to 800 ° C. to 1100 ° C. The water-soluble substances in the incineration ash are eluted in water,
It is characterized in that solids generated in the filtrate after filtration of water are separated and dried (claim 1).

That is, according to the above method, first, the incinerated ash is heat-treated at 800 ° C. to 1100 ° C. The main constituent elements of incineration ash are Si, Ca, and Al, but the bonding form of these elements varies depending on the heat treatment temperature.In the temperature range of 800 ° C to 1100 ° C, CaSiO ₃ is easy to form. As a result, Al separated from Si and Ca by the above heat treatment
Ingredients increase.

When the incineration ash subjected to such a heat treatment is subjected to an elution treatment using water, the above-mentioned CaSiO ₃
Does not elute due to poor solubility, and elutes a water-soluble substance containing Al.
In the filtrate obtained by filtering this water, for example, by simply leaving this, the Al component is gradually oxidized and precipitated, and this is separated and dried to obtain high-purity alumina (Al ₂
O ₃₎ can be obtained.

As described above, according to the above method, Al, which is a main component element of incinerated ash, can be separated from Si and Ca and recovered as high-purity alumina. This can be used as a raw material powder having stable properties, for example, in the ceramic industry. Incineration at existing municipal solid waste incineration plants is performed at around 800 ° C, and the incineration ash generated by this process includes ash after burning at temperatures higher than 800 ° C. It is considered that the above-described separation of the Al component from Si and Ca has occurred at this stage.
It also contains a large amount of incinerated ash after burning at a temperature lower than 800 ° C. Therefore, when such incinerated ash is used, it is possible to obtain alumina at a higher recovery rate by performing the heat treatment at 800 ° C. to 1100 ° C. as described above.

On the other hand, the incineration of waste is controlled so as to be carried out under the above-mentioned heat treatment conditions, that is, in the temperature range of 800 ° C. to 1100 ° C., and the incineration ash obtained thereby is subjected to the elution treatment in the same manner as described above. It is also possible to recover the alumina by the method (claim 2). Since the incineration ash in this case does not need to be subsequently subjected to a heat treatment, the overall treatment cost is lower.

[0010]

Next, an embodiment of the present invention using incineration ash formed in an existing municipal solid waste incineration plant will be described with reference to the drawings. At the municipal waste incineration plant,
For example, municipal solid waste is incinerated at a temperature of about 800 ° C in a fluidized bed incinerator, and the incinerated ash generated by this is stored in a storage tank and then humidified with water when it is carried out. In Table 1,
An example of the result of component analysis of such municipal waste incineration wet ash by X-ray fluorescence analysis is shown for each detected element in terms of oxide.

[0011]

[Table 1]

On the other hand, the X-ray diffraction pattern of the above incinerated wet ash, which was separately measured for composition analysis, shows that SiO ₂ , gehlenite (= Ca ₂ SiAl ₂ O ₇ ), anorthite (= CaSi ₂ Al
Peaks such as ₂ O ₈ ) and CaCO ₃ are detected. In other words, the main constituent elements of the incinerated ash are Si, Ca, and Al as shown in Table 1. In particular, Al is a composition mainly bonded to Si or Ca in the above incinerated wet ash. It exists in a state that has been taken in.

By sequentially performing the treatments of the first to sixth steps (P1 to P6) shown in FIG.
Finally, high-purity alumina (Al ₂ O ₃ ) is obtained, and specific processing contents and actions in each step at this time are as follows.
This will be described below. First, as a first step P1, a process of heating the above incinerated wet ash to 800 ° C. to 1100 ° C. using an electric furnace was performed in an air atmosphere. In addition, after heating up to 300 ° C / Hr up to the heating set temperature, holding at the set temperature for 30 minutes,
Furnace cooled.

By performing such a heat treatment, a reaction occurs such that the Al component is separated from Si and Ca in the incinerated ash. In other words, as described above, incineration ash is melted when heated to a temperature exceeding 1250 ° C., but even in the heat treatment at a temperature lower than the melting temperature, the bonding form of Si, Ca, Al in the incineration ash becomes the heating temperature. It changes variously according to it. For example, at a temperature exceeding 1100 ° C., the formation ratio of gohrenite (Ca ₂ SiAl ₂ O ₇ ) increases. On the other hand, in the temperature range from 800 ° C to 1100 ° C, Ca and Si
: It is formed CaSiO ₃ bound easier, as a result, Si, Ca
Al component separated from the alloy increases.

Next, as shown in a second step P2, the incinerated ash after the above-mentioned heat treatment was introduced into water to perform an elution treatment. Specifically, using an infiltrator having a vertical cylindrical mixing tank, the incineration ash was poured into 10 times the volume of water, and then mechanical stirring was continued for 6 hours. In this elution treatment, the above-mentioned CaSiO ₃
Is hardly soluble and does not elute, and a water-soluble substance containing an Al component elutes in water.

Thereafter, as shown in the third step P3, the water after the above-mentioned elution treatment was subjected to suction filtration using, for example, a filtration device equipped with a 1 μm glass filter. The resulting filtrate was colorless and transparent. Next, as shown in the fourth step P4, the above filtrate was allowed to stand at room temperature for 24 hours, for example. A white solid precipitated in the filtrate after standing, and was changed to a sol-like liquid.

This solution is suction-filtered again using a filtration device equipped with a 1 μm glass filter as shown in a fifth step P5, and the residue is removed, for example, by 100 μm as shown in a sixth step P6. ℃ -1Hr dried by heating. FIG. 2 shows the solids finally obtained from the incinerated ash when the heat treatment temperature in the first step P1 was 1000 ° C.
The result analyzed by (energy dispersive X-ray spectroscopy) is shown as an example. From the figure, although Ca is contained as an impurity slightly, it is recognized that the alumina is extremely high-purity as is clear from the difference in the count value between Al and Ca. FIG. 3 is an SEM (scanning electron microscope) photograph of this solid.

In the first step P1, 750 ° C. or less, or 11
Even if the incineration ash subjected to the heat treatment at 50 ° C. or higher was subjected to the same treatment as above, almost no alumina was obtained. When the heat treatment temperature is in the range of 800 ° C to 1100 ° C,
The recovery rate of alumina is maximum at 1000 ° C,
At this time, about 10 g of alumina was obtained from 10 kg of incinerated ash (recovery rate: 0.1%).

As described above, in this embodiment, before the incinerated ash is heated to a temperature of 1250 ° C. or more to form a molten slag, the incineration is performed at a temperature of 800 ° C. to 1100 ° C. lower than the melting temperature. The ash is heated and then the water-soluble substances in the incineration ash are eluted into water, thereby separating Al, the main component element of the incineration ash, from Si and Ca to produce high-purity alumina. It can be recovered. Therefore, since this high-purity alumina can be provided as a raw material powder having stable characteristics in, for example, the ceramic industry, the effective use range of incinerated ash can be further expanded.

In the above embodiment, an example is shown in which the humidified ash of municipal solid waste incinerated at about 800 ° C. is used as a starting material, and the humidified ash is used as a starting material. By using dry ash before performing, alumina can be obtained at a higher recovery rate. In other words, the above incinerated ash includes incinerated ash with a combustion temperature lower than 800 ° C and incinerated ash that has been incinerated at a temperature higher than 800 ° C and has caused a separation reaction of the Al component from Si and Ca. Is also included. It is considered that the water-soluble substance containing the Al component at this time was already eluted to some extent in the water during the humidification treatment, and this is not contained in the alumina recovered in the above embodiment.

Therefore, by using the dry ash before the humidification treatment and performing the treatment of heating to 800 ° C. to 1100 ° C., the incineration formed at a temperature at the time of incineration exceeding 800 ° C. The Al component in the ash is kept as it is, and the incinerated ash formed at a temperature of less than 800 ° C. is heated to the above temperature range, so that a separation reaction of the Al component from Si and Ca occurs. The recovery rate of alumina is improved.

Further, it is also possible to incinerate the municipal solid waste under the above heat treatment conditions, that is, at a temperature in the range of 800 ° C. to 1100 ° C., and to perform the above-mentioned elution treatment on the incinerated ash obtained thereby. It is. In this case, since there is no need to perform a heat treatment separately from the incineration treatment, the overall treatment cost is lower. The present invention is not limited to the incineration ash of municipal solid waste illustrated in the above-described embodiment, but can be applied to incineration ash of other waste such as sewage sludge.

[0023]

As described above, according to the method for recovering valuable resources from incinerated ash of the present invention, Al, which is one of the main constituent elements of incinerated ash, is separated from Si and Ca to obtain high-purity alumina. Can be collected. Therefore, this can be provided as a raw material powder having stable properties in the field of ceramics and the like, and the effective use of incinerated ash can be promoted.

[Brief description of the drawings]

FIG. 1 is a process chart showing a procedure for treating incinerated ash in one embodiment of the present invention.

FIG. 2 ED of a solid finally obtained by the above treatment
9 is a graph showing an example of an analysis result by XS.

FIG. 3 is a scanning electron micrograph of the solid (magnification: 20000 times).

Claims (2)

[Claims] 1. Incineration ash of waste such as municipal waste is 800
After heating to 1100 ° C., water-soluble substances in the incinerated ash are eluted in water, and then solids generated in the filtrate after filtering the water are separated and dried. Object collection method. 2. Wastes such as municipal solid waste are stored at 800.degree.
Heat incineration at 00 ° C., then elute water-soluble substances in the incineration ash into water, and then separate and dry solids generated in the filtrate after filtering the water. Object collection method.