JP2005035854A - Porous body and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the strength of a porous body produced by using incineration ash of sewage sludge and to simplify the production method of the porous body. <P>SOLUTION: The porous body is produced through a mixing process for mixing an inorganic powder such as the incineration ash of sewage sludge and the like and a binder, a granulation process for granulating the mixture mixed in the mixing process, a forming process for forming the granule granulated in the granulation process, and a firing process for firing the formed body formed in the forming process. Thereby, the porous body having high strength can be easily obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a porous body formed from an inorganic material, particularly sewage sludge incineration ash, and a method for producing the same.

  A large amount of sewage sludge generated during sewage treatment is generated from municipal sewage. In general, as a method of treating sewage sludge, a method is known in which sludge is incinerated in an incinerator to reduce the volume, and then the incinerated ash is landfilled as waste. However, since it is difficult to secure a landfill, attempts have been made to reuse sewage sludge incineration ash as a resource in order to extend the life of the landfill.

  As a method of reusing sewage sludge incineration ash (hereinafter simply referred to as incineration ash), the incineration ash is kneaded with a binder and granulated, and the dried granulated material is introduced into a firing furnace at a high temperature (eg, 1050 ° C.). There is known a method of obtaining a particulate lightweight aggregate containing bubbles by heating to a gas and gasifying and foaming volatile components in the incinerated ash.

  In addition, the incinerated ash is granulated, dried, and then fired into a particulate fired body as a secondary raw material. This is mixed with other ceramic powders and binders, press-molded, fired again, and porous. A method of forming a body and using it for paving blocks has been proposed (see Patent Document 1).

JP-A-10-67579

  However, according to the above technique, since the binder is added to the incinerated ash and granulated and fired, the binder is added to the particulate fired body, and then molded and fired. There is a problem that the baking process is performed twice, and the manufacturing process becomes complicated.

  Moreover, since the particulate fired body fired once is fired again, there is a problem that the particles are not sufficiently welded to each other and the strength of the fired body is limited.

  It is an object of the present invention to increase the strength of a porous body produced using sewage sludge incineration ash and to simplify the production method.

  As a result of intensive studies to solve the above problems, the inventor first added a binder to an inorganic powder such as incinerated ash, kneaded, granulated, and dried, and then a granulated body was first formed into a predetermined shape. It was found that a porous body that retains its shape can be obtained by molding into a green body and firing the molded body. That is, when the granulated body is fired as in the conventional method, it is necessary to add the binder again to form the molded body and fire it, but according to the present invention, the granulated body is directly molded. Thus, both the addition of the binder and the firing are all performed once. Thereby, the manufacturing process is simplified, the manufacturing cost is reduced, the particles are appropriately welded, and the strength of the porous body is increased.

In this case, the binder is composed of a binder, a surfactant, water, and the like, and the blending ratio is appropriately determined depending on the properties of the incinerated ash. Molding refers to, for example, obtaining a desired shape by filling a granule into a mold. Here, at the time of filling the granulated body or after filling, it is desirable to mold the granulated body while applying pressure. Thereby, the filling of the granulated body becomes dense, and the shape retention of the molded body during firing is improved. Furthermore, in consideration of the shape retention of the molded body and the releasability from the mold, the pressure for pressing the granulated body is more preferably adjusted to a pressure range of 150 to 400 kgf / cm ² per projected area. .

  The porous body produced according to the present invention is formed by molding and firing a particle group mainly composed of an inorganic substance such as sewage sludge incineration ash into a predetermined shape. And a gap formed in the gap. The porosity of the porous body can be adjusted within a predetermined range by appropriately adjusting, for example, the pressure for pressing the granulated body and the firing temperature in the molding step. That is, when the pressing pressure is lowered, the gap between the granulated bodies is increased, so that the porosity of the porous body is increased after firing. On the other hand, when the pressing pressure is increased, the porosity is decreased.

  ADVANTAGE OF THE INVENTION According to this invention, the intensity | strength of the porous body manufactured using sewage sludge incineration ash becomes high, and a manufacturing process becomes simple.

  Hereinafter, the present invention will be described based on embodiments. The porous body according to the present embodiment generally uses powdered sewage sludge incineration ash (hereinafter simply referred to as incineration ash) discharged when sewage sludge discharged from a city or the like is incinerated in an incinerator or the like. It is manufactured using. That is, it is manufactured by adding a binder to the incinerated ash, kneading, granulating and drying the dried granulated material directly into a mold or the like and molding, and firing the molded product. .

  FIG. 1 shows a process diagram of a method for producing a porous body according to an embodiment of the present invention. As shown in the figure, this manufacturing process includes step S1 for receiving a predetermined amount of incinerated ash, step S2 for adding a binder to the incinerated ash and kneading to obtain a mixture, and granulating the mixture to granulate. Step S3 for obtaining the step, Step S4 for regulating the granulated body, Step S5 for drying the granulated body, Step S6 for obtaining the molded body by molding the dried granulated body, The process includes step S7 for firing the molded body and step S8 for commercializing the fired body. Hereinafter, the steps will be described step by step.

  First, in step S1, the incineration ash taken out from the incinerator is further finely pulverized by, for example, a vibration mill, and a predetermined amount of incineration ash having a adjusted particle size is prepared.

  Next, in step S2, the incinerated ash is kneaded so as to be uniformly mixed while adding appropriate amounts of a binder, a surfactant, and water as a binder. As the binder, yeast culture concentrate and molasses liquid are preferably used, and the main components thereof are, for example, cellulose, hemicellulose, lignin, etc., but are limited to this as long as they bind incineration ash. is not. The water added at the time of kneading is used to stably maintain the wet state of the mixture, and is used appropriately when it cannot be adjusted only with the binder. As the surfactant, for example, it is desirable to use an anionic surfactant. Thereby, the wettability of the incinerated ash surface is improved, and wetting of the binder and water is promoted. That is, in terms of stabilizing or improving the properties and functions of the porous body, it is effective to add a binder, water, and a surfactant to the incinerated ash and uniformly mix or suspend them.

Further, additives other than the above effective for the properties and functions of the porous body include hydroxides such as KOH, NaOH, Ca (OH) ₂ , SiO ₂ , P ₂ O ₅ , Al ₂ O ₃ , CaO, Examples thereof include oxides such as K ₂ O, SO ₃ , Ni ₂ O ₃ and MnO, chlorides such as KCl and NaCl, and inorganic and organic compounds thereof.

  Next, in step S3, the mixture obtained in step S2 is supplied to a granulator composed of, for example, a roller, a screen, and a retainer, and extruded downward from the opening of the screen by roller rolling. Then, it is cut into a predetermined size with a blade or the like to obtain a granulated body.

  In step S4, this granulated body is supplied onto a rotating disk (for example, a Malmo plate), and rolled on the granule to be granulated. In addition, the particle size distribution at the time of sizing is widely distributed from 1 mm to over 20 mm.

  In step S5, the sized granulated material is supplied to a dryer or the like, and dried for several hours while flowing hot air at 200 ° C., for example. This dried granulated product is subjected to particle size selection by a sieve, and a particle group having a particle size in the range of 0.6 mm to 1.7 mm (hereinafter referred to as a fine particle) and in a range of 1.7 mm to 3.4 mm. It is sorted into a particle group (hereinafter referred to as coarse particles) and stored as a dry granulated body. In addition, the fine particle size and coarse particle size range of the dry granule in the present embodiment is appropriately selected in consideration of functions required for the final product, etc., and does not prescribe the particle size of the dry granule itself. Absent. Moreover, although the drying temperature is prescribed | regulated to 200 degreeC, if the water | moisture content of a dry granulation body is fully evaporated and it is the temperature which does not start sintering of incineration ash, it will not be limited to this. By the way, this dried granulated product can be commercialized as a granular product by, for example, supplying it directly to a multistage jet furnace or a rotary kiln furnace and firing it.

  Next, in step S6, the dried granulated material is filled in a mold and molded. In the present embodiment, for example, uniaxial compression molding is applied as a known compression molding method. Specifically, a dry granulated body (hereinafter referred to as “particles” as appropriate) is supplied into a slightly punched die and vibrated for a short time to enhance the filling state. Press to compress it. When compression is completed, the pressing mold is removed, and the molded body is extracted from the mold.

  In this case, if the molded body has a simple shape such as a cylinder or a cube, for example, it can be manufactured by a single molding. The compression ratio of the particles with respect to the pressing movement amount of the mold is different. Therefore, when applying the uniaxial compression method, it is desirable to divide the bottom surface portion and the side surface portion into two portions and compress each. Further, when compression molding, particles slide on the inner surface of the mold, but in order to reduce the influence, it is preferable to apply, for example, biaxial or more compression molding. Further, in order to improve the releasability from the mold, it is preferable to apply a release agent to the inner wall of the mold.

The pressing pressure in the compression molding of the present embodiment is preferably 150 to 400 kgf / cm ² and more preferably 170 to 250 kgf / cm ² per projected unit area of the dried granulated body, that is, the material to be compressed. preferable. This pressure range varies depending on the properties of the powder and the properties of the binder to be added, but if the pressing pressure is excessive, the gaps between the particles in the molded body will be reduced or eliminated, realizing the porosity of the final product. become unable. On the other hand, when the pressing pressure is too low, the strength of the molded body is lowered, and the shape of the molded body cannot be maintained during the transport process and the firing process.

  Next, in step 7, the compact is put into a firing furnace and fired. In this case, the firing condition is that the temperature is increased at a relatively fast rate (for example, 200 ° C./hour) until the temperature before the incineration ash starts to be sintered (for example, 650 ° C.). It is preferable to raise the temperature up to the maximum temperature at a relatively slow rate (for example, 50 ° C./hour). The maximum temperature is, for example, 1060 to 1100 ° C., and a sufficient time is maintained. As a result, the particles constituting the molded body start to be fused from the portions in contact with each other, while the unfused space remains as a void, thereby forming a porous body.

  Finally, the fired porous body taken out from the firing furnace is subjected to post-processing described later according to the product application in Step 8 to be a final product.

  Next, an example of how to use the porous body produced in the present embodiment will be specifically described. The porous body of the present embodiment has certain water permeability and water retention, depending on the porosity. On the other hand, when a well-known water repellent (for example, hydrocarbon-based, fluorine-based, etc.) is allowed to act on the porous body, the air permeability is maintained, but the water permeability and water retention are extremely lowered. . Therefore, for example, a porous body in which a part of the side surface is coated with a water repellent has porosity as a whole, while part of the porous body maintains water permeability and water retention, and the other part has almost water permeability and water retention. It becomes a characteristic that does not have. The porous body in the present embodiment can be used as, for example, a flower pot. In other words, by applying the water repellent only to the side surface portion of the porous container, the water permeability is suppressed while the portion has air permeability, water does not ooze out from the inside, and the water repellent is not applied from the bottom. Only drainage and water absorption are performed. In addition, the range which performs a water-repellent process in a porous body is not limited to a part of outer surface, According to a use, you may make it make the whole water-repellent process.

  In addition, by attaching, for example, a well-known organic fertilizer (for example, a compound containing nitrogen, phosphoric acid, potassium, etc.) to the voids of the porous body, the organic component as planting can be obtained by water permeability and water retention. For example, it can be used as a porous material for rooftop greening. In addition, by impregnating the porous body with water containing the above organic matter, for example, it is suitable as a rooftop greening tile in which moss and ground cover are planted.

  As described above, in this embodiment, by adding a binder to the powder that is sewage sludge incineration ash, kneading, granulating, and drying, the dried granulated body is directly pressed and molded. A molded body having a desired shape is formed. Moreover, even if this molded body is fired, a fired product having a porous structure in which the shape of the molded body is maintained can be obtained. Thus, unlike the conventional method, it is not necessary to add the binder and perform the baking process twice, so that the manufacturing process is simplified and economical. Further, since the firing process is performed only once, the particles are easily fused with each other, and the strength (for example, breaking strength) of the fired body is increased.

  Further, in the present embodiment, the sewage sludge incineration ash has been described as an example, but the present invention is not limited thereto, and other inorganic powders may be granulated, molded, and fired. Similar effects can be achieved.

  In the present embodiment, an example in which compression molding is applied in the molding of a dried granulated body has been described. However, the present invention is not limited to this. For example, the dried granulated body is placed in a mold having an open top. May be fired in a state where there is a spread (no pressure state), and taken out from the mold after firing. According to this, the porosity is increased and the breaking strength is reduced as compared with the above porous body, but it can be used for products that require air permeability.

  Hereinafter, the present invention will be described more specifically with reference to examples.

(Examples 1-8) Based on the manufacturing process of FIG. 1 described above, the dried granulated material is compression molded and fired using sewage sludge incineration ash (manufactured by the Tokyo Sewerage Bureau) as a raw material. A test piece was prepared. The binding material used in this case was yeast culture concentrate (manufactured by Oriental Yeast Co., Ltd.), and the surfactant used was Sannol DL-1430 (manufactured by Lion Corporation). The amount of the binder added was 27 parts by weight with 100 parts by weight of sewage sludge incineration ash. Moreover, the coarse granule mentioned above or the fine grain was used for the dry granulated body, respectively. Detailed test conditions are shown below.
(Test conditions)
Press: hydraulic press (Riken power P1B-041, manufactured by Riken Seiki Co.), the piston cylinder pressure receiving area: 33.18Cm ²
Mold dimension: Inner diameter φ25mm
Press pressure: 200 kgf / cm ² , granulated pressure receiving area: φ25 mm
Firing furnace: Muffle furnace (NMR-14-SK, manufactured by Isuzu Manufacturing Co., Ltd.)
Weight measurement: Electronic balance (FX-300N, manufactured by AND Corporation)
Firing temperature: 1060 ° C or 1100 ° C
Firing time: 6 hours or 12 hours FIG. 2 shows a press die used for compression molding. As shown in the figure, first, a cylindrical tube frame 1 is placed on a press stand 2, a piece 3 is placed as an underlay on the bottom of the filling portion of the tube frame 1, and then a dry granulated body 4 that is weighed is put in. Then, the dried granulated body 4 is sandwiched in the cylindrical frame 1 by putting the piece 5 as a pressing die. And the piece 5 is compressed and molded by a press machine through the piston 6. After molding, the molded body is taken out from the tube frame 1 and fired.

  Table 1 shows the results (Examples 1 to 8) produced by changing the particle size, firing temperature, and holding time based on the above conditions.

実施例１〜８において、成型に使用する乾燥造粒体は、粗粒、細粒に関わらず、新たに結合材を添加しなくても成型が可能であり、焼成においても、その形状が維持され、十分に焼結されることが確かめられた。また、焼成体の重量、吸水量および外径寸法を測定した結果を表１に示す。各試験片とも、焼成による収縮が認められ、さらに、焼成温度を１０６０℃から１１００℃に上昇させることにより、収縮率が大きくなっている。これにより、焼成温度を溶融域温度まで昇温させなくても焼結することが判明した。

In Examples 1-8, the dried granulated material used for molding can be molded without adding a new binder regardless of whether it is coarse or fine, and its shape is maintained even during firing. And was confirmed to be fully sintered. Table 1 shows the results of measuring the weight, water absorption and outer diameter of the fired body. In each test piece, shrinkage due to firing was observed, and the shrinkage rate was increased by raising the firing temperature from 1060 ° C. to 1100 ° C. As a result, it has been found that sintering is performed without raising the firing temperature to the melting region temperature.

  The amount of water absorption was determined by supplying water to the test piece by dropping the water with a dropper and setting the end point as the time when water began to ooze from the test piece. In all the test pieces, water was rapidly sucked and capillary action was observed. From the above, it was confirmed that all of the examples had sufficient water permeability and water retention.

  (Example 9) A test piece (see Table 1) obtained by molding a coarse dry granulated body under the above conditions and firing at a firing temperature of 1060 ° C. and a holding time of 12 hours was used as a siloxane-based water repellent (Aqua The surface was dipped in Seal 1300CR, Chugai Furnace Industry Co., Ltd. to make the surface water-repellent, and then water droplets were dropped on the surface in a dried state. As a result, it was confirmed that the water droplets were rounded on the surface and did not penetrate at all.

  (Example 10) A dry granulated body made of coarse particles was molded, and a test piece (using the test piece of Example 3) fired under conditions of firing temperature: 1060 ° C and holding time: 12 hours was naturally dried, and then organic matter In a state of impregnating moisture sufficiently containing moss and adhering moss, it was sealed in a sufficiently large container and left in a dark room for about 1 month. After that, when the container was opened, it was confirmed that the moss remained alive in blue.

(Example 11) Next, the molded product was evaluated at the press pressure of compression molding. The gauge pressure of the press to compress the mold, (when converted to granule pressing pressure, about each ^{167,200,400,1000,2000kgf / cm 2) 25,30,60,150,300kgf / cm} 2 and As a result of changing and compressing the dried granulated product (15 g, coarse product), the particles were crushed at a gauge pressure of 60 kgf / cm ² or more, which was the same as that obtained by directly compacting the incinerated ash. On the other hand, at a gauge pressure of 25 kgf / cm ² , the adhesion between the particles was weak, and the corner portion easily dropped off. In contrast, in the gauge pressure 30 kgf / cm ^2, without collapse dried granules, moldings in close contact with a relatively good state was obtained. By the way, when this molded body having a gauge pressure of 30 kgf / cm ² was fired (1060 ° C. and 1100 ° C.), slight firing shrinkage was observed, but it was confirmed that the shape was maintained.

  (Example 12) The dried granulated material in Example 1 was spread in a mold having an open top without being pressurized, and baked together with the mold to produce a porous test piece. This test piece was made into seven types with a firing temperature of 1000 ° C. and 1050 ° C. to 1100 ° C. at intervals of 10 ° C. and holding times of five types of 1, 3, 6, 12, 24 h. The ligation was evaluated. As a result, at 1080 ° C. × 12 h, it was confirmed that 90% or more of the particles of the test piece were fused, and the glass was uniformly generated on the surface. Further, it was confirmed that the holding time required for the fused state can be shortened by further increasing the firing temperature.

It is process drawing of the manufacturing method of the porous body which concerns on this invention. It is a block diagram of the press die of the dry granulated body which concerns on the Example of this invention.

Explanation of symbols

1 Cylinder frame 2 Press stand 3, 5 pieces 6 Piston

Claims (8)

A mixing step of mixing the inorganic powder and the binder, a granulating step of granulating the mixture mixed by the mixing step, and a molding step of molding the granulated body granulated by the granulating step And a method for producing a porous body comprising a firing step of firing the molded body molded by the molding step. The said powder is a sewage sludge incineration ash, The manufacturing method of the porous body of Claim 1 characterized by the above-mentioned. The method for producing a porous body according to claim 1 or 2, wherein the molding step is performed by pressurizing the granulated body. The method for producing a porous body according to claim 3, wherein in the molding step, pressurization is performed at a pressure of 150 to 400 kgf / cm ² per projected area of the granulated body. A porous body formed by molding and firing a particle group containing an inorganic substance as a main component, and having a fusion part where the particles are fused together and a gap part between the particles. The porous body according to claim 5, wherein the particle group is a collection of particles formed from sewage sludge incineration ash. The porous body according to claim 5 or 6, wherein a part or all of the outer surface of the porous body is subjected to water repellent treatment. The porous body according to claim 5 or 6, wherein the porous body is formed by attaching an organic substance to the void portion.

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