JP4759667B2 - Paper sludge incinerated ash granulated hydrothermal solidified body-aluminum composite material - Google Patents

Description

  The present invention is a high-strength material that suppresses elution of heavy metals from incineration ash generated when paper sludge (hereinafter abbreviated as PS) generated from pulp manufacturing process, paper manufacturing process, waste paper processing process, etc. is incinerated. In addition, a granulated product made from a long-term stable granular hydrothermal solidified material is used as dispersed particles, and an aluminum material that can also be recycled aluminum cans is used as molten metal. The present invention relates to a method for producing a composite material without applying a high pressure by improving the familiarity (wetting) between the granular hydrothermal solidified body and the aluminum 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.

  As a typical manufacturing method of a composite material composed of a metal matrix and a particulate reinforcing material, there are the following conventional techniques. For example, the thixocasting method is a processing technique in which an alloy solidified by solid-liquid coexisting and solidified is heated again in the solid-liquid coexistence region, and molding is performed using this thixotropic property. This is a semi-solid process in the solid-liquid coexistence temperature region.

  In addition, the composting method adds a mechanical rotating stirrer with a stirrer in the solid-liquid coexistence state of the alloy material, and at the same time, administers non-metallic fine particles and fibers to make a metal matrix composite with high homogeneity. Is the method. This is also a semi-solidification process in the solid-liquid coexistence temperature region.

  In addition, the pressure casting method, which is a solution infiltration method, has been conducted many experiments at the laboratory level for a long time as a method for producing a metal-particle composite material. A high-pressure solidification casting method in which pressure is applied is employed. As a pressure casting method, Patent Document 1 describes a method of obtaining a lightweight composite material by press-fitting a molten metal such as aluminum into a fine hollow body such as ceramic filled in a mold with a hydraulic press. ing.

  Also, in Patent Document 2, titania (titanium oxide) particles are mechanically stirred and granulated by spray drying, and aluminum, which is a molten metal, is impregnated with high pressure to obtain a composite material excellent in ductility and fracture toughness. A method is described.

  On the other hand, PS incineration ash is bulky and has a transportation cost, and the ash shape is non-uniform, so that it has few uses as a cement raw material like fly ash. In addition, PS incineration ash contains hazardous materials such as heavy metals, and direct landfill disposal is not possible. It is obliged to carry out landfill disposal at the prevented disposal site. Furthermore, in the case of landfill disposal, an intermediate treatment that suppresses 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.

Japanese Patent Publication No.52-17494 JP-A-8-176703

  As described above, (1) the dispersed particles are a composite material of molten metal that is a granulated hydrothermal solidified product by recycling PS incineration ash, and (2) the dispersed particles and molten metal are mixed from the solid phase. (3) It is a mixing and stirring process in a completely melted state, not a semi-solid process, (4) It is a low pressure casting method that is about a weight rather than a high pressure casting that requires special equipment, There was no technology by.

In view of this situation, as a method for reducing the processing costs by effectively using PS incineration ash, a small amount of solidification material (cement, quicklime, etc.) is added to PS incineration ash, and water is added and stirred with a mixer. Aluminum that can be used as non-fired granulated solidified product produced by reaction (hydrothermal solidification reaction) of granulated product in autoclave curing at high temperature and pressure as dispersed particles, and aluminum can also be used for molten metal, which is also recycled Providing a lightweight and highly heat-insulating composite material without applying high pressure by improving the familiarity (wetting) of PS incinerated ash granulated hydrothermal solidified body and aluminum material, and its production The problem was to provide a method.

  In order to achieve the above-mentioned problems, the method for producing a paper sludge ash granulated hydrothermal solidified body-aluminum composite of the present invention includes water and / or hot water, quick lime, incinerated ash generated when paper sludge is incinerated. In addition, cement is added and cured at room temperature to 98 ° C to form a granulated granulated product, and then the solidified product produced by reaction (hydrothermal solidification reaction) at high temperature and high pressure is dispersed particles. As a molten metal, a material selected from the group consisting of aluminum, aluminum alloys, waste aluminum products, and a mixture of two or more of these can be used alternately in a crucible. By heating the crucible with a heater, the PS incinerated ash granulated hydrothermal solidified body is dried to dissolve the aluminum ingot, and then the whole is stirred with a stirrer. And it was molded by pressurizing the upper (see Fig. 1) with a plunger is configured to solidifying to produce a composite material by slow cooling.

By the above method, the composite material of the present invention is provided, which is composed of a hydrothermal solidified material after granulation of PS incinerated ash, and a material selected from the group consisting of aluminum, aluminum alloys, and mixtures thereof. The hydrothermal solidified material accounts for 50% to 75% of the total volume of the composite material. The hydrothermal solidified body is 50% of the total volume of the composite, and by volume ratio, PS incinerated ash granulated hydrothermal solidified body: aluminum (in the case of an aluminum alloy, the volume of the aluminum alloy) = 50: 50, , as described below, from the PS ash granulation hydrothermal solidified density of (0.855g / cm ³⁾ and aluminum density of (2.7g / cm ^3), the weight ratio, PS ash granulation hydrothermal Solidified body: aluminum = 25: 75. If the hydrothermal solidified body is less than 50% of the total volume of the composite material, the resulting composite material cannot have a light and highly heat-insulating effect. On the other hand, when it exceeds 75%, there is a problem that the molten metal of aluminum is not uniformly permeated between the hydrothermal solidified bodies, and the strength becomes insufficient and a predetermined strength cannot be obtained.

  According to the present invention, PS incinerated ash is used as a raw material, and a small amount of solidified material (cement, quicklime, etc.) and water are granulated by reacting at high temperature and high pressure (hydrothermal solidification reaction) and lightweight and porous. PS incinerated ash granulated hydrothermal solidified product produced as a solidified product is dispersed particles and mixed with aluminum, which is a molten metal, so that the thermal conductivity is about 1/16 that of aluminum alone, and has excellent heat insulation Composite material can be obtained.

  The PS incinerated ash granulated hydrothermal solidified body-aluminum composite thus produced is excellent in vibration control, sound absorption and heat insulation, and has sufficient strength and durability. It can be used for various applications such as vibration control, air conditioner noise control, and building materials.

In addition, it can be said that using PS incineration ash, which has been difficult to use effectively, is very preferable from the viewpoint of reduction of processing costs, reduction of environmental burden, or ecology.

Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications.
First, production of PS incinerated ash granulated hydrothermal solidified product will be described.

PS 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, but in this case, the type is not limited. Further, 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 plastics / waste paper solid fuel), and other general combustibles, as long as the original properties of PS incinerated ash are not impaired. Along with paper sludge, mixed firing in a boiler is acceptable. When coal is used for auxiliary combustion, it is common that PS incineration ash contains heavy metals (hexavalent chromium, arsenic, selenium, fluorine, boron, etc.) even though a small amount.

  The water and / or warm water added to the PS incineration ash is 60 to 100 parts by weight, desirably 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. If the amount of water and / or warm water added to the incinerated ash is increased, the granulation time is shortened. This is thought to be because granulation progresses rapidly as water and / or hot 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 PS incinerated ash is 60 to 100 parts by weight with respect to 100 parts by weight of the incinerated ash. The result was 100 parts by weight, desirably 75 to 95 parts by weight.

Although the amount of quicklime added to PS incineration ash is based also on the amount of quicklime contained in PS incineration ash, the range of 0-20 weight part is desirable with respect to 100 weight part of incineration ash. Moreover, since the amount of quick lime contained in PS incineration ash increases by increasing the calcium carbonate added at the time of combustion for desulfurization of a boiler, the amount of quick lime 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 PS incineration ash, silica (SiO ₂ ), which will be described later, improves the strength in the hydrothermal solidification reaction and suppresses the elution of heavy metals harmful substances It plays an important role. The cement added to the PS 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 added cement has a role of generating strength itself composed of water and / or hot water, and further, the silica content (SiO ₂ ) contained in the cement is the silica originally contained in the PS 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.

  The curing accelerator and dispersant added as necessary have a role of promoting hydration and developing strength early in a mixture with PS incinerated ash, water and / or hot water, quicklime, and cement, which will be described later. It has the effect of shortening the pre-curing and steam curing treatment times. Examples of the hardening accelerator and dispersant include calcium chloride, ferric chloride, aluminum chloride, magnesium chloride, sodium carbonate, potassium carbonate, zinc silicofluoride, magnesium silicofluoride, and sodium silicofluoride.

  The paper sludge is added with incineration ash, water and / or warm water, quicklime, cement, a curing accelerator and a dispersant as necessary, and a mixing step and a granulation step are performed. The temperature of the mixing / granulating step is from normal temperature to 98 ° C., for example, 15 to 98 ° C., desirably 60 to 95 ° C., in order to improve the strength. 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, PS incineration ash, water, quicklime, and cement may be supplied separately to the granulator, or may be supplied in a premixed state.

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. A 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 above to form 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 flake type 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, the particles themselves can be softly formed, and further, they have a certain range rather than a fixed particle size so that they can be easily compacted in construction. A particle size distribution must be obtained and the application must be suitable for mass production. From the above, among the above granulators, the rolling granulator is most suitable.

  After the granulation process, the granulated product needs to be pre-cured. 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.

After pre-curing, hydrothermal solidification reaction is performed by steam curing (autoclave curing with steam at 185 ° C. and 10 atm), so that lime (CaO) and silica (SiO ₂ ) originally contained in PS incineration ash and addition Crystal of calcium silicate (tobermorite, 5CaO · 6SiO ₂ · 5H ₂ O) is generated from the quicklime (CaO) and silica (SiO ₂ ) contained in the cement by a hydrothermal solidification reaction. A long-term stable granular hydrothermal solidified body is obtained. Since only the lime and silica originally contained in PS incinerated ash cannot obtain sufficient strength by the hydrothermal solidification reaction, post-added quick lime and cement are necessary.

The above is description regarding manufacture of PS incineration ash granulation hydrothermal solidification body.
Next, a method for producing a composite material using the above-described SP incinerated ash granulated hydrothermal solidified body as dispersed particles and an aluminum material as a molten metal will be described.

  The composite material manufacturing process includes (a) mixing and charging PS incinerated ash granulated hydrothermal solidified body and aluminum material in the mold, and (b) mixing and charging the two materials mixed in the mold. By heating to 850 ° C., the PS incinerated ash granulated hydrothermal solidified body is dried and preheated and the aluminum material is melted. (C) After the aluminum material is melted, the PS incinerated ash granulated hydrothermal solidified body is stirred. (D) The PS incinerated ash granulated hydrothermal solidified body floating on the top is pushed into the interior to achieve uniform mixing. (E) The composite is gradually cooled to room temperature by furnace cooling so that there is no shrinkage in the center. The manufacturing process of this composite material is shown in FIG.

  The particle size of the PS incinerated ash granulated hydrothermal solidified body is preferably about 2.5 to 10 mm. If the particle is smaller than 2.5 mm, it is difficult for the surface of the particle to get wet with the molten metal, and the properties of the particle cannot be exhibited. On the other hand, if the particles are larger than 10 mm, the wetness of the particle surface with respect to the molten metal is good, but the metal and the particles are not uniform, and this also fails to obtain a predetermined performance as a composite material.

Since the mold shape is heated while stirring, a cylindrical shape is preferable.
The mixing ratio of PS incinerated ash granulated hydrothermal solidified body and aluminum is preferably PS incinerated ash granulated hydrothermal solidified body: aluminum = 50: 50 to 25:75, that is, 1: 1 to 1: 3. . The weight ratio of 50: 50 to 25: 75, from the density of PS ash granulation hydrothermal solidified (0.855g / cm ³⁾ and aluminum density of (2.7g / cm ^3), when the volume ratio, 75:25 to 50:50, that is, 1: (1/3) to 1: 1.

The dissolution has both functions of drying the PS incinerated ash granulated hydrothermal solidified body and dissolving the aluminum material. The melting time is a time for sufficiently melting aluminum.
In the mixing and stirring method, the shear rate and shearing force between aluminum in the melt and PS incinerated ash granulated hydrothermal solidified body are made high. The shear state helps to remove gases and gas bubbles adsorbed from the particle surface by the physical mechanism that the molten metal rubs the particle surface and cleans contaminants such as gases and oxides. This shear also tends to diffuse the molten metal on the particle surface, and when shear forces are applied, helps to overcome other forces that prevent the molten metal from diffusing on the particle surface. Further, the shearing action does not deform or crush the particles other than the molten metal shears the particles.

  Aluminum which is a molten metal wets the PS incinerated ash granulated hydrothermal solidified body, and the aluminum is mixed by a stirrer over a sufficient time so that the PS incinerated ash granulated hydrothermal solidified body is dispersed in the aluminum. The shape of the stirring bar is not particularly limited as long as the PS ash granulated hydrothermal solidified body and aluminum are sufficiently uniformly mixed.

  From the experimental results, the mixing stirring time is 5 to 10 minutes, but the mixing stirring time is not limited to this range as long as the PS incinerated ash granulated hydrothermal solidified body and aluminum are uniformly mixed.

  It is necessary to control the heating temperature so that unnecessary chemical reaction does not occur between the PS incinerated ash granulated hydrothermal solidified body and aluminum. The optimum heating temperature is 800-850 ° C. When heating temperature is higher than 850 degreeC, it will be in the state which a remarkable oxidation reaction generate | occur | produces, and soundness, such as a metal intensity | strength, will be impaired. On the other hand, when the heating temperature is lower than 800 ° C., a place where the temperature is low occurs and partially solidifies, and the uniformity as a composite material is impaired.

The pressure applied by the plunger is 0.26 to 0.52 kg / cm ² as a pressure range from the experimental result.
The cooling method of the composite material eliminates the shrinkage cavity in the center, and in order to obtain a dense composite material with almost uniform granulation distribution, the heating by the heater is stopped and the entire furnace and composite material are gradually brought to room temperature. The slow cooling method is effective.

The paper sludge incinerated ash granulated hydrothermal solidified body-aluminum composite material obtained by the above method has vibration control properties, sound absorption properties, and heat insulation properties.

Although the Example of this invention is shown below, this is illustrative and this invention should not be limited to this.
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 PS incinerated ash having the composition shown in Table 1 as pre-curing 2 Natural curing for a week was performed, and further, steam curing was performed at 180 ° C. for 5 hours as a hydrothermal solidification treatment to obtain a hydrothermal solidified body.

  As the aluminum, pseudo-recycled aluminum melted in almost the same components as recycled aluminum was used. Table 2 shows chemical components of the pseudo aluminum.

  A differential thermal analysis was performed to measure the melting point of the pseudo aluminum. The phase transformation temperature was determined by inserting a thermocouple into the pseudo-recycled aluminum melt and measuring the cooling curve during the slow cooling process. Table 3 shows the phase transformation temperatures of the pseudo-recycled aluminum. These phase transformation temperatures are important in determining the mixing temperature with the PS incinerated ash granulated hydrothermal solidified body in the production of the composite material.

The particle size of the PS incinerated ash granulated hydrothermal solidified product was adjusted and classified into 2.5 mm or less, 2.5 to 5 mm, or 5 mm or more, and combined with pseudo recycled aluminum. The PS incinerated ash granulated hydrothermal solidified body was heated at 100 to 200 ° C. for a long time, and the moisture content was determined from the weight measurement before and after heating. As a result, it was 41%. As a result of measurement of a density after thermal drying PS ash granulation hydrothermal solidification body is 0.855 g / cm ^3, is about three times lighter density of aluminum (2.7g / cm ^3).

The manufacturing process of the composite material is as shown in FIG.
The composite materials produced by the optimum manufacturing process are composed of two short composite materials (composites A and B) and two long composite materials (composites C and D). The origin is shown in Table 4. In any production conditions, the mixing ratio of the PS incinerated ash granulated hydrothermal solidified body and aluminum is 50:50 by weight, and the heating temperature is 800 ° C. The weight ratio of 50:50, the density of PS ash granulation hydrothermal solidified (0.855g / cm ³⁾ and aluminum density of (2.7g / cm ^3), when the volume ratio, 75: 25 and Become.

Regarding the density of the composite material, the density of the short composite material A, the short composite material B, the head portion, the middle portion, and the bottom portion of the long composite material C, and the head portion, the middle portion, and the bottom portion of the long composite material D are shown in FIG.
The compression strength of the composite material was compared using a composite material and a single aluminum material. In this experiment, the load was compared when the sample was compressed and deformed by 30%. FIG. 3 shows the compressive strength of various materials. From this, it can be seen that the higher the mixing ratio of the granulated product, the lower the compressive strength.

The thermal conductivity of the composite material was calculated from the following equation by measuring the temperature difference Δθ between the upper and lower copper plates.
λ = Δθ / (L × A × V)
Δθ: difference in measured value [° C.] L: thickness of material to be measured Here, L is the thickness of the material to be measured, and current A and voltage V are 55 mA and 10 V, respectively.
The measurement results are shown in FIG. 4 in comparison with other materials. Although the thermal conductivity of aluminum is as high as 236 W / mK, the composite material (hybrid B, M, T) contains PS incinerated ash granulated hydrothermal solidified material, so it is about 1/16 of aluminum and has a heat insulation property. Are better.

The results obtained for the composite material of PS incinerated ash granulated hydrothermal solidified material and recycled aluminum are as follows.
(1) The best results were obtained when mixing recycled aluminum and PS incinerated ash granulates when the aluminum was in a molten state.
(2) Since the PS incinerated ash granulated hydrothermal solidified body having a low density floats on the molten aluminum head when mixed, it is necessary to cover it with a highly heat insulating material and apply a load.
(3) When the mixed material is cooled in a liquid phase, there is a high possibility that a shrinkage nest will be formed inside the material unless it is gradually cooled.
(4) The compressive strength of the composite material decreases as the distribution ratio of the PS incinerated ash granulated hydrothermal solidified body increases.
(5) The thermal conductivity of the composite material was about 1/16 that of aluminum, and it was found that the composite material was excellent in heat insulation.

It is the schematic which shows the manufacturing process of the composite material of this invention. It is a graph which shows the density of the head of the short composite material A, the short composite material B, and the long composite material C, the middle part, the bottom part, the head part, the middle part, and the bottom part of the long composite material D. It is the graph which compared the compressive strength of the composite material using the composite material and the aluminum simple substance material. It is the graph which compared the thermal conductivity of the composite material of this invention using the aluminum simple substance material.

Claims (5)

  In the composite material in which the hydrothermal solidified material after granulation of the paper sludge incineration ash occupies 50% to 75% of the total volume of the composite material, from the group consisting of the hydrothermal solidified material, aluminum, aluminum alloy and a mixture thereof Said composite material comprising a selected material.   The hydrothermal solidified material after the granulation of the paper sludge incineration ash is made by adding water and / or hot water, quicklime and cement to the incineration ash generated when the paper sludge is incinerated, and at a temperature from room temperature to 98 ° C. The composite material according to claim 1, wherein the composite material is produced by curing a shaped body that has been mixed and granulated, and then producing a solidified body using a hydrothermal solidification reaction.   The paper sludge incinerated ash granulation hydrolyzed solidified body is heated in a mold together with a material selected from the group consisting of aluminum, aluminum alloys, waste aluminum products, and a mixture of two or more of these, The hydrothermal solidified material after granulation of paper sludge incineration ash is characterized by melting the raw material, stirring and mixing in a molten or semi-solidified state, then pressurizing and then solidifying by cooling slowly. A method of manufacturing the composite material comprising a material selected from the group consisting of the hydrothermal solidified body and aluminum, an aluminum alloy, and a mixture thereof.   The hydrothermal solidified product is formed by adding water and / or hot water, quicklime and cement to incineration ash generated when paper sludge is incinerated, and mixing at a temperature from room temperature to 98 ° C. to form granules. The method according to claim 3, wherein the method is produced by producing a solidified body using a hydrothermal solidification reaction after curing the body.   The method according to claim 3, wherein the pressurization is performed via a plunger.

Images