JPS607554B2 - Method for solidifying fine powder incineration residue - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for solidifying finely powdered incineration residue produced by incineration of sludge discharged from various water treatment processes.

However, in large cities, large amounts of fine powder incineration residue are generated as a result of waste disposal, making it extremely difficult to find land for landfill. ing.

In addition, these fine powdered incineration residues may contain harmful substances such as heavy metals, and if they are dumped as landfill materials, they may be scattered by wind and rain, or the heavy metals may be leached into groundwater or rainwater, resulting in poor water quality. This will lead to pollution problems such as air pollution. Therefore, recently these fine powdered incineration residues are sintered,
Consideration has been given to disposing or reusing it in a stable form as a resultant material. However, when pulverized incineration residue is solidified, the pulverized incineration residue is constantly fused to each other as soon as it reaches the dawning temperature in the dawn feeding furnace, and becomes enlarged in a so-called snowball style. It becomes a lump, which impedes the smooth operation of the feeder and makes it difficult to discharge, and may even cause damage such as damage to the discharge mechanism. Furthermore, in order to reuse such agglomerated products, a separate crushing mechanism is required and reprocessing is required, which is a disadvantage. In addition, when attempting to directly freeze sludge to obtain a solids, even if the sludge is shaped into a shape that is convenient for handling and reuse before being fed into the dawning furnace, there is generally a considerable amount of material in the sludge. Because it contains organic matter, the molded product will foam or expand significantly in the sintering furnace, become deformed, or crack, making it impossible to obtain a delicate corpse that is convenient for reuse. I have no choice but to give up on sintered wire production.

In other words, ``In order to obtain a fine agglomerate by agglomerating the pulverized incineration residue, the incineration furnace is raised and maintained at a condensation temperature, and the product is fused and agglomerated, so it cannot be reused as a fine agglomerate. The temperature range (hereinafter referred to as the sintering temperature range) in which a sintered material that is convenient for use can be obtained may not be present at all or may be extremely narrow.Also, it is possible to directly sinter the sludge to obtain a dense sintered material. Therefore, if the sludge sintering furnace is raised and maintained at the sintering temperature of the sludge, the sludge foams, expands, and forms a fused lump, making it impossible to obtain a sintered product that is delicate and easy to reuse.

In many cases, it is actually impossible to sinter the pulverized incineration residue, so even though it is known that it is effective to sinter the pulverized incineration residue, it is inconvenient and uneconomical that it cannot be easily used. was there.

The present invention eliminates these conventional drawbacks and has developed a method for processing fine powder incineration residue by autoclaving at low temperatures (100 to 30,000 ℃).
We have developed an effective solidification method that uses a two-stage process of sintering and high-temperature (700-1400°C) processing using a sintering furnace to easily obtain a dense and strong sintered product that is easy to landfill or reuse. The purpose is to provide

The present invention involves adding and mixing a sintering binder to the finely powdered incineration residue produced by incineration of sludge discharged from various water treatment processes, and adding and mixing a solidification accelerator as necessary to eliminate the presence of calcium components. After molding, the molded product is subjected to steam autoclave treatment to increase the strength of the molded product, and the molded product is then placed in a sintering furnace to obtain a sintered product.

In addition, in order to sinter the molded product whose strength has been increased by performing the steam autoclave treatment, there is no need to provide a separate competitive furnace; It is also possible to carry out sintering using the so-called closed circuit method.At this time, the sintered material is discharged from the incinerator together with the incinerated ash (incineration ash), so the sintered material is divided into knots.

In addition, when a sintering furnace is installed separately from an incinerator, a rotary kiln, an overturned flame round (square) leaf furnace, an electric furnace, or other continuous or discontinuous incinerator may be used as the sintering furnace. can. The carbon-feeding binder used in the present invention is preferably a powder or granular material with a melting point lower than that of the finely powdered incineration residue itself, such as glasses, water glass, shelf element compounds, carbonates of alkali metals, There are feldspars, cryolite, etc., and incineration residue having a lower melting point than the above-mentioned fine powder incineration residue can also be used, and the amount added is 5 to 5% by weight, preferably 10 to 5%.
3% by weight is preferred.

Furthermore, in the present invention, it is necessary that a calcium component be present in the fine powdered incineration residue in the autoclave treatment, and for this reason, it is preferable that the fine powdered incineration residue contains sufficient calcium components. However, if it is insufficient, it is necessary to add a calcium component, and in this case, it is desirable that the proportion of calcium component in the residual liquid is 1% by weight or more (calculated as quicklime).

The calcium component to be added can be in the form of calcium carbonate, quicklime, calcium sulfate, calcium chloride, and slaked lime. Of these, slaked lime is the most suitable, and in some cases, various types of sludge that have been dehydrated using calcium components can be added. It is also possible to use the residue obtained by incineration. In addition, even if the calcium component is sufficient in the finely powdered incineration residue in the autoclape process, if necessary, as a solidification accelerator, diatom, poppy, flower, poppy/acid clay, kaiseki, etc.
Poppy seeds such as quartz, poppy, acid glass, water glass, sand, acid-purifying substances, clays such as kaolinite, pentonite, barite, zeolite, hallosite, aluminum compounds such as aluminum hydroxide, aluminum oxide, or fried foods containing the above substances. A suitable amount (for example, 1 to 3% by weight, preferably 10 to 2% by weight) of waste such as ash or red mud may be added alone or in combination, and a solidification accelerator may also be added to the sintered binder. If there is a substance that serves both purposes, there is no need to add a solidification accelerator.

In this way, the finely powdered incinerated isosumi, which contains a sintered binder and a calcium component, and is mixed with a solidification accelerator if necessary, is molded into an appropriate size to increase the number of contact points between solids. For this molding, conventional techniques such as pressure pressing, rolling granulation, and extrusion molding can be used as they are.

The thus formed Zanwan is placed in an autoclave using steam as a medium, solidified by being left in the presence of pressurized steam, and the autoclaved product is further sintered. The sintering temperature to be applied depends on the state of the autoclaved product, in particular on the components constituting the sintering binder, but is approximately 700 to 1000 sintered.
oo, 1000-1400qo in special cases, 5-6
Effective treatment can be achieved by burning for about a minute. As described above, according to the present invention, since the fine powder incineration residue can be sintered at a temperature lower than the sintering temperature of the fine powder incineration residue itself, the molded product does not become a fused lump in the competitive process. In addition, since it does not foam and expand, it is possible to obtain a compact and strong competitor that is easy to landfill or reuse, and it can be disposed of without causing secondary pollution, and the sintering temperature range can be widened considerably. This makes it extremely easy to control the temperature of the sintering furnace, making it possible to process the pulverized incineration residue into a state convenient for disposal or reuse, and to solidify it extremely easily and at low cost. There are benefits such as

In other words, the properties of the resulting compacted material are significantly superior to that of the solidified material obtained only by autoclaving, so it can be reused in a wide range of areas, and the solid material entering the incineration process has a high strength, making it far superior to conventional solidified material. Since the powdering phenomenon observed in the sintering method does not occur, there is no dust fusion to the brazing furnace or dust scattering outside the furnace, and operation is easy.

In addition, since the reduction treatment of Cr60 was carried out by autoclave treatment before the dawn, the C+ during the burning process was
It has remarkable effects such as being able to prevent the occurrence of. Next, examples of the method of the present invention will be shown.

Example 1 The composition of the incineration residue obtained by dewatering, drying, and incinerating wastewater sludge from a certain city sewage treatment plant was as shown in Table 1.

Table 1 Add 20% sodium borate to this residual liquid as a competitive binder.
wt was added and mixed, and molded using a compression molding machine at a pressure of 500k9f' to obtain a molded product with a length of 1 rib and a diameter of 10 skins.

This molded body was placed in an autoclave at a pressure of 5 atm.
Hydrothermal treatment was performed for 0 minutes to obtain a solidified product. This solidified product was further sintered in a small batch kiln for 1100 hours,
I got baked twill. The properties of the burnt material are shown in Table 2. Also shown is a sample to which no Akatsuki binder was added for comparison.

This shows that the addition of the sintered mackerel binder increases the strength of the sintered product and improves the elution of heavy metals (CR). Choichi 2 * Meltability is determined by Environment Agency Notification No. 5 (March 14, 1972).
In addition to the Akatsuki binder, we also added 10%w of glass powder as a solidification accelerator.
Table 3 shows the strength and portability of the sintered product obtained by subjecting the sample to which T was added to exactly the same hydrothermal treatment and freezing treatment.

Table 3 This shows that when a solidification accelerator is added and mixed, the strength is further increased and the amount of elution is reduced.

Example 2 The sludge used in Example 1 was dehydrated and dried, and then incinerated in a small continuous rotary kiln to obtain a residue.

(Maximum furnace temperature 1100qo) The composition of this residual liquid is shown in the table below.
It was exactly the same as shown in 1. To this residual liquid, 20% wt of sodium borate as a sintering binder and 10% M of glass powder as a solidification accelerator were added and mixed, and a solidified product was produced under the same molding and autoclaving conditions as in Example 1. .

This solidified material is put into the small-sized continuous rotary kiln, where the sludge is incinerated and the solidified material is solidified at the same time. I got it.

The strength of this sintered material was 240 kgf', and the amount of Cr elution was less than 0.01 leg, and the properties were the same as those of the sintered material obtained in Example 4.

As a result, it is not necessarily necessary to use a furnace for sludge incineration and a furnace for feeding solidified material separately as in Example 1, and it is possible to proceed with two processes at the same time in one furnace as in this example. Equipment construction costs and operating costs can be significantly reduced. Example 3 The incineration residue used in Example 1 was treated with Table 4 as a competitive binder.
Table 4 shows the strength and dissolution properties of a compact obtained by adding and mixing a predetermined amount of the materials shown in Table 4 and processing it under the same molding conditions, autoclave conditions, and sintering conditions as in Example 1. Ta.

Table-4 The melting point of this leftover sake is 1200°C.

As a result, incineration residues with a lower melting point than incineration residues of glasses, water glass, yellow compounds, alkali metal carbonates, feldspars, cryolite, or substances to be solidified, as shown in Table 4, are It can be seen that when used as a binding agent, the properties of the sintered product are significantly improved.

Example 4 In a certain urban sewage treatment plant, an organic polymer flocculant is used for dewatering sludge.

The dehydrated cake discharged from this treatment plant is dried and
The chemical composition of the shallow thin layer obtained by incineration for 2 hours at OO is shown in Table 5.
It was as follows. Table 5 Add 10% of soda glass powder to this afterglow as a pseudo-binding agent.
% wt was added, and as a calcium component, quicklime in the amount shown in Table 6 was added and mixed, and formed into a charcoal shape with a length of 2 ribs, a middle rib of 2 ribs, and a thickness of 10 willows using a briquetting machine.

This molded product was placed in an autoclave at a pressure of 20 k9f/s for 2 hours and subjected to hydrothermal treatment to obtain a solidified product, and the solidified product was further sintered in a small batch kiln for 1,100,003 hours to obtain a sintered product. The properties of this roasted product are shown in Table 6.
Table 6 From these results, it can be seen that when a calcium component is added to the residual liquid, the properties of the crystallites are improved, and this effect is remarkable when the calcium component in the residual liquid is 10% or more.

Example 5 To the incineration residue used in Example 4, 10% wt of soda glass powder was added as an agglomeration binder, and various calcium components were added so that the Ca content in the shallow thin layer was 10%. The materials were mixed and treated under the same molding conditions, autoclave conditions, and dawning conditions as in Example 4 to obtain sintered products as shown in Table 7.

Table 7 It can be seen that all of the various calcium components shown in Table 7 are effective, but the effect of slaked lime is particularly remarkable.

Example 6 At a certain human waste treatment plant, excess sludge is dehydrated using slaked lime slurry.

The chemical composition of the residue obtained by drying and incinerating this dehydrated cake is shown in Table 8. Taiichi 8 Adding a predetermined amount of this residue to the incineration residue used in Example 4,
Soda glass powder was added in an amount of 10% M, and the mixture was treated under the same molding conditions, autoclave conditions, and sintering conditions as in Example 4, to obtain a compacted product having the properties shown in Table 9.

Table 9 From this, it can be seen that when the incineration residue of sludge containing a calcium component is added and mixed into other residual liquid as a calcium component, the strength of the sintered product increases and the amount of sintered material decreases.

Furthermore, the effect is remarkable when the calcium component in Zanwan is 10%M or more in terms of quicklime. Example 7 A predetermined amount of the solidification accelerator shown in Table 10 was added to and mixed with the incineration residue used in Example 1, and 10%M calcium borate (colemanite) was added to produce the same solution as in Example 1. Competitive products were obtained by processing under molding conditions, autoclave conditions, and sintering conditions.

The properties of the crystallites are shown in Table 10. Table 10 As shown in Table 10, remarkable effects can be obtained by using poppy seeds, acidic substances, clays, aluminum compounds, or wastes containing these substances as solidification accelerators.

Claims (1)

[Scope of Claims] 1. A sintered binder is added and mixed to the finely powdered incineration residue generated by incineration of sludge discharged from various water treatment processes, a solidification accelerator is added and mixed as necessary, and a calcium component is added and mixed. A method for solidifying finely powdered incineration residue, which comprises shaping it in the presence of a substance, solidifying it in a steam autoclave, and sintering it in a sintering furnace. 2. Claim 1, wherein the sintering step is performed using the incinerator used for incineration of the sludge.
Solidification method described in section. 3. The solidification method according to claim 1 or 2, wherein the sintered binder is treated with a substance having a lower melting point than the finely powdered incineration residue. 4 The ratio of calcium component in the fine powder incineration residue is 1
The solidification method according to claim 1, 2, or 3, wherein the solidification method is adjusted to 0% by weight (calculated as quicklime) or more. 5. Claims 1 and 2, in which the solidification promoter is treated using silicic acid substances, clays, aluminum compounds, or sludge containing these substances alone or in combination.
The solidification method according to item 3, item 3 or item 4. 6 Claims 1 and 2, in which the calcium component is treated by adding slaked lime to the finely powdered incineration residue.
The solidification method described in Section 4 or Section 4. 7. The method according to claim 1, 2, or 4, wherein the calcium component is treated by adding a residue obtained by incinerating dehydrated sludge containing calcium to the finely powdered incineration residue. Solidification method.