JP2005313032A - Manufacturing method for hydrothermally solidified material of paper sludge incineration ash - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a granular solidified material enhanced in strengths and suppressed in the elution of a harmful component of heavy metals without damaging microporosity/porosity being the original property of paper sludge incineration ash and suitable for a soil improving material having hygroscopicity or water retention. <P>SOLUTION: Water and/or hot water, quick lime and cement are added to incineration ash obtained at the time of incineration treatment of paper sludge and mixed therewith at a temperature from the normal temperature to 98°C to form a granulated molded material. After the molded material is aged, it is subjected to hydrothermal solidifying reaction to manufacture a hydrothermally solidified material of paper sludge incineration ash having a microporous/porous structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention suppresses elution of heavy metals from incineration ash generated when incineration of paper sludge generated from pulp manufacturing process, paper manufacturing process, waste paper processing process, etc., is stable with high strength and long-term The present invention relates to a method for producing a hydrothermal solidified material suitable for a granular soil improvement material. Paper sludge generally refers to industrial waste generated when recycling used paper, but here includes waste generated from a pulp manufacturing process, a paper manufacturing process, a used paper processing process, and the like.

Paper sludge incineration ash is bulky and has a transportation cost, and the ash shape is not uniform, so it does not have a use as a cement raw material like fly ash.
In addition, paper sludge incineration ash contains hazardous substances such as heavy metals, and direct landfill disposal is not possible. When landfilling is performed, osmotic water discharges to the outside with a water shielding sheet called a managed disposal site. It is obliged that landfill disposal must be done at the disposal site that prevents this.
Or in the case of landfill disposal, an intermediate treatment to suppress the elution of harmful substances is necessary. There are chemical (chelate) treatment and melt solidification treatment as intermediate treatment, but expensive chelating agents require several percent of the ash to be treated, and melt solidification treatment requires equipment costs and a lot of energy. This intermediate treatment method increases the cost of incineration ash treatment.
In addition, securing a landfill site itself has become increasingly difficult in recent years.

Therefore, a method for producing a solidified body using a hydrothermal solidification reaction has been proposed as one method for reducing the processing cost by effectively using incineration ash and waste other than paper sludge.
In Patent Document 1, paper sludge discharged from a paper mill is pretreated at 200 to 1000 ° C., and then added as silicon oxide, sodium hydroxide and calcium oxide, and then hydrothermally synthesized to be useful as an ion exchanger. A method for producing a tobermorite mixture is disclosed.

  In Patent Document 2, active calcium such as quick lime and slaked lime is included in ceramic waste, glaze sludge, green waste, foundry sand waste, municipal waste incineration ash, sewage sludge incineration ash, coal ash, fly ash, slag, etc. A method for producing a solidified body that can be used as a construction material such as a paving material by hydrothermal synthesis after adding and mixing a source and press-molding the obtained mixture is disclosed.

  In Patent Document 3, a process for suppressing expansion when producing a solidified body from incineration fly ash generated when incineration of waste such as municipal waste, industrial waste, and solid waste fuel (RDF) is performed. Waste incineration fly ash solidified body that can produce a solidified body with high strength and can be used for high-quality roadbed materials that are stable in the long term and have no strength reduction or collapse A manufacturing method is disclosed.

Patent Document 4 relates to a method for producing a hydrothermal solidified product made of a crushed stone by-product. Specifically, a calcium compound is added to a muddy water cake or stone powder that is a crushed stone by-product containing silica (SiO ₂ ) generated in a crushed stone plant. A method for producing a hydrothermal solidified product such as a high-quality building block from a crushed stone by-product by mixing and finally hydrothermally solidifying the raw material mixture is disclosed.
JP-A-3-159913 JP-A-10-296205 JP 2000-308867 A Japanese Patent Laid-Open No. 2002-137756

In the method described in Patent Document 1, since it is merely for obtaining a powdery product from a slurry reaction, it is not possible to obtain a granular or block solidified body.
In the methods described in Patent Document 2 and Patent Document 4, a solidified body is manufactured by pressure molding rather than granulation.
In the method described in Patent Document 3, a solidified body is produced by molding or granulation.
Although there is a method for obtaining a solidified body by pressure molding that suppresses the elution of toxic components of heavy metals with long-term stable strength from incineration ash, fly ash, etc. of general waste, paper is provided. The present condition is that the effective method of manufacturing a solidified body from sludge incineration ash is not provided.

  The present invention has been made in view of the above-mentioned points, and the object of the present invention is to elute harmful components of heavy metals with high strength without impairing the porosity and porosity that are the original properties of paper sludge incineration ash. It is providing the manufacturing method of the granular solid body suitable for the soil improvement material which has hygroscopicity and water retention which suppressed water | moisture content.

In order to achieve the above object, the method for producing a paper sludge incinerated ash solidified body according to the present invention includes (a) adding water and / or hot water to incinerated ash generated when paper sludge is incinerated. (C) Further, quicklime and cement are added, (d) a curing accelerator and a dispersing agent are added if necessary, and supplied to a granulator. (G) After pre-curing the granulated product, (g) in a curing room such as a thermostat or autoclave at 40 to 250 ° C. for 3 to 24 hours High strength and stable long-term hydrothermal power that suppresses the elution of harmful substances of heavy metals from paper sludge incinerated ash, preferably by steam curing at 180 ° C for 5 hours It is comprised so that a solidified body may be manufactured.

Since this invention is comprised as mentioned above, there exist the following effects.
(1) In the case of paper sludge incineration ash, it consists of woody organic matter (fine fibers, soft cells, organic pigments and fillers used in paper, etc.) having an appropriate size, so that the gap and silica are at an appropriate distance. Therefore, a hydrothermal solidification reaction with added quicklime is easy, and a stable granular hydrothermal solidified body with higher strength can be obtained. Therefore, water and / or warm water, quick lime and cement are added to paper sludge incineration ash, pre-cured and then granulated into a granulated product, and steam curing is performed in a curing room such as a thermostatic bath or autoclave. Thus, it is possible to produce a high-quality hydrothermal solidified body having high strength and stable for a long period of time, which suppresses the elution of harmful substances such as heavy metals from paper sludge incineration ash.
(2) Paper sludge incineration ash is inherently porous and porous, as is clear from the above structural description, and the resulting hydrothermal solidified product is also porous and porous and absorbs water. It has properties and water retention. In addition, because it is granular, it has a large surface area, so it has a greater water absorption and water retention effect, it can improve drainage and control land subsidence, and can improve crop cultivation, and it can also be a hazardous substance such as heavy metals The quality and properties required for soil improvement materials such as satisfying the elution standards of

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications.
The figure shows a method for producing a paper sludge incinerated ash water heat-solidified product according to an embodiment of the present invention.
(1) Paper sludge incineration ash is incineration ash obtained by incinerating paper sludge generated from a pulp manufacturing process, paper manufacturing process, waste paper processing process, and the like with a boiler. There are various types of boilers such as a fluidized bed boiler and a stoker incinerator. In this case, the type is not limited. In addition, heavy oil or coal may be co-fired in a boiler together with paper sludge as long as it is used for auxiliary combustion.
Furthermore, RDF (garbage solid fuel), RPF (industrial waste plastic / waste paper solid fuel), and other general combustible materials, as long as the original properties of paper sludge incineration ash are not impaired. As well as paper sludge, mixed firing in a boiler is acceptable.
When coal is used for combustion, paper sludge incineration ash generally contains trace amounts of heavy metals (hexavalent chromium, arsenic, selenium, fluorine, boron, etc.).

(2) The water and / or warm water added to the paper sludge incineration ash is 60 to 100 parts by weight, preferably 75 to 95 parts by weight with respect to 100 parts by weight of the incineration ash.
The addition amount of water and / or warm water affects the granulation conditions and the strength after granulation.
When the amount of water and / or warm water added to the incinerated ash is increased, the granulation time is shortened. This is considered to be because granulation progresses rapidly as water and / or warm water quickly penetrates the incineration ash. However, the strength after granulation tends to be low. On the other hand, when the amount of water and / or warm water added to the incinerated ash is reduced, the granulation time becomes longer, but the strength after granulation tends to increase.
From this, after pursuing a desirable range where the strength after granulation is high and the production efficiency is also high, the water and / or hot water added to the paper sludge incineration ash is 60 parts by weight with respect to 100 parts by weight of the incineration ash. It was obtained to be -100 parts by weight, desirably 75-95 parts by weight.

(3) Although the amount of quick lime added to paper sludge incineration ash is based also on the amount of quick lime contained in paper sludge incineration ash, the range of 0-20 weight part with respect to 100 weight part of incineration ash is desirable. Moreover, since the amount of quicklime contained in paper sludge incineration ash increases by increasing the calcium carbonate added at the time of combustion for desulfurization of a boiler, the amount of quicklime added at the time of mixing can be decreased. The quicklime is preferably granular or powdery so that it can be well mixed with the incineration ash. The added quicklime (CaO), together with the lime (CaO) originally contained in the paper sludge incineration ash, silica (SiO ₂ ), which will be described later, improves strength in the hydrothermal solidification reaction and elutes harmful substances such as heavy metals It plays an important role in suppression.
The cement added to the paper sludge incineration ash is preferably 0 to 20 parts by weight with respect to 100 parts by weight of the incineration ash, although it depends on the required strength. The cement to be added has a role of generating strength itself composed of water and / or warm water, and further, the silica content (SiO ₂ ) contained in the cement is originally contained in the paper sludge incineration ash. Together with the component (SiO ₂ ), the lime component (CaO) and the hydrothermal solidification reaction play an important role in improving the strength and suppressing the elution of harmful substances such as heavy metals.

(4) The curing accelerator and dispersant added as necessary have a role of promoting strength in a mixture with paper sludge incineration ash, water and / or warm water, quicklime, and cement to promote strength early. There is an effect of shortening the treatment time of the precuring and steam curing described later.
Examples of the curing accelerator and dispersant include calcium chloride, ferric chloride, aluminum chloride, magnesium chloride, sodium carbonate, potassium carbonate, zinc silicofluoride, magnesium silicofluoride, and sodium silicofluoride.

(5) The paper sludge is added with incineration ash, water and / or hot water, quicklime, cement, and if necessary, a hardening accelerator and a dispersing agent, and a mixing step and a granulation step are performed.
In order to improve the strength, the temperature of the mixing and granulating step should be maintained at room temperature to 98 ° C, desirably 60 to 95 ° C.
As described above, the mixing / granulation time is affected by the amount of water and / or warm water added, and is also affected by the mixing device (such as the rotational speed and size of the stirrer). desirable.
In addition, paper sludge incineration ash, water, quicklime, and cement may be supplied separately to the granulator, or may be supplied in a premixed state.

When using a soil improvement material, it is desirable that the particle diameter of 1.18 mm to 16 mm has 70% or more of the total weight.
The soil improvement material is applied in a layered manner (for example, about 50 to 150 cm thickness) in the soil, and further, the top soil (for example, about 100 cm) is applied to improve drainage.
In order to obtain good drainage such as rainwater from the topsoil, it is necessary that there are gaps between the particles of the soil amendment and there is a way for water to escape. It is also necessary that the soil improvement material layer under the topsoil has water retention and can be rehydrated when the topsoil moisture is reduced. For that purpose, it is necessary that the soil improvement material particles have a water absorption property and a water retention property because the particles are porous or porous. Since the soil improvement material layer has water retention, it can also prevent crop damage and winter damage. A larger particle surface area is more advantageous for water absorption and water retention, and the smaller the particle size, the larger the particle surface area. However, when the particles are nearly spherical, it is difficult to compact with a small particle size alone, and conversely, it is difficult to compact with a large particle size as well. It becomes easy to compact by filling a gap between large particles with a small particle size. From this, as a soil improvement material, it will be easy to compact on construction, and the particle size range which has the aptitude required for a soil improvement material will be prescribed | regulated.

Examples of the granulator include an extrusion granulator, a rolling granulator, a roll molding machine, a tableting granulator, and a flaker granulator. An extrusion granulator forcibly extrudes a material from a die having a constant hole diameter. The rolling granulator is suitable for producing a large amount of relatively soft and well-formed spheres while the materials supplied to the rotating body adhere and grow to each other by rotational movement. The roll forming machine is a device in which a concave pocket is carved in a pair of opposed rotating rolls, and a material is supplied from the top to make a granulated product having a constant shape. The tableting granulator continuously performs this process, in which a material is filled in a metal mold arranged in a radial pattern on a disk, compressed by a push bar, and then the granulated product is discharged. The flaker granulator is a granulator that forms a flake by adhering a melt or slurry-like material to a rotating drum or a steam belt and cooling or heating.
Since the granulator of the present invention needs to maintain the porosity and porosity suitable for the soil improvement material, the particles themselves can be softly molded, and the particle size is not constant so that it can be easily compacted in construction. A particle size distribution with a certain range should be obtained, and it should be suitable for mass production in terms of use. From the above, among the above granulators, the rolling granulator is most suitable.

  (6) After the granulation step, the granulated product needs to be precured. This pre-curing is important because the pre-curing increases the hardness of the granulated product, thereby increasing the hardness of the subsequent hydrothermal solidified body. There are two types of curing methods: natural curing and forced curing. Natural curing is a curing method that takes time without any particular changes. Forced curing is an efficient curing method in a short time while maintaining a high temperature state. In the present invention, either curing method may be used.

(7) After pre-curing, by performing steam curing, the lime content (CaO) and silica (SiO ₂ ) originally contained in the paper sludge incineration ash and the silica (SiO ₂ ) added to the quick lime (CaO) and cement to be added (SiO ₂ ) ₂ ) From the above, crystals of calcium silicate (tobermorite, 5CaO · 6SiO ₂ · 5H ₂ O) are produced by hydrothermal solidification reaction, which is suitable for high-strength and long-term stable granular soil improvement materials A hydrothermal solidified body is obtained.
Since only the lime and silica originally contained in the paper sludge incineration ash cannot obtain sufficient strength by the hydrothermal solidification reaction, post-added quick lime and cement are necessary.

Examples and Comparative Examples will be shown below to further clarify the features of the present invention.
A granulated granulated product obtained by mixing and granulating 91 parts by weight of water, 10 parts by weight of quick lime, and 10 parts by weight of cement with 100 parts by weight of paper sludge incineration ash having the composition shown in Table 1 as pre-curing A hydrothermal solidified body obtained by performing natural curing for 2 weeks and further performing water vapor curing at 180 ° C. for 5 hours as hydrothermal solidification treatment, fly ash having the same composition, and a structure not subjected to hydrothermal solidification treatment Table 2 shows a comparison of the leaching analysis values of harmful substances in the granules. Fly ash and granulated products have fluorine values exceeding the soil environmental standards, but hydrothermal solidified products are also within the soil environmental standards in other analysis items including fluorine, and the effect of suppressing the release of harmful substances can be confirmed. .

  Each sample was allowed to stand at constant temperature and humidity (23 ° C., 50% RH) for a whole day and night as a pretreatment to be in a constant weight state. In the test method, 25 g was taken from each sample in a constant weight state, 100 ml of distilled water was added, lightly mixed, allowed to stand for about 1 hour, and naturally filtered until water droplets did not fall on the filter paper (5A). The sample was dried (105 ° C.), the weight was measured, and the water content was calculated. Table 3 shows the result of comparing each sample. In the state of fly ash, paper sludge incineration ash (PS ash) was higher in moisture than coal ash, that is, the result was higher in water absorption. Similarly, the granulated product of paper sludge incineration ash obtained higher water absorption than the ash granulated product in which coal ash and paper sludge incineration ash were mixed at 7: 3.

It is process drawing which shows the manufacturing method of the hydrothermal solidification body of paper sludge incineration ash by embodiment of this invention.

Claims (4)

Water and / or warm water, quick lime and cement are added to the incinerated ash generated when paper sludge is incinerated, and after curing the molded body granulated into granules by mixing at a temperature from room temperature to 98 ° C., water A method for producing a heat-solidified paper sludge incinerated ash water having a porous and porous structure, characterized by producing a solidified body using a heat-solidifying reaction. The manufacturing method of the incineration ash hydrothermal solidification body of Claim 1 in which the incineration ash contains the incineration ash which generate | occur | produces when incinerating coal. The method for producing a paper sludge incinerated ash hydrothermal solidified body according to claim 1, wherein the water and / or warm water, the quicklime and the cement are added to the incinerated ash one component at a time in any order. The method for producing a paper sludge incinerated ash hydrothermal solidified body according to claim 1, further comprising adding a curing accelerator and / or a dispersant to the incinerated ash.

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