JP2007268375A - Method for manufacturing porous powder, porous powder, and humidity controlling material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing porous powder by which a manufacturing efficiency is enhanced by drastically saving man-hours for a drying processing, and sludge incineration ash is effectively reused as an excellent humidity controlling material, and to provide the porous powder obtained by the method. <P>SOLUTION: In the method for manufacturing the porous powder, an acid treatment is performed by bringing the sludge incineration ash into contact with an acidic gas, and then a neutralization treatment is performed by using a powder neutralization agent, thereby drastically saving the man-hours for the drying processing. Furthermore, it is preferable that the acidic gas is waster soluble, thereby, the acidic gas is dissolved in moisture in the sludge incineration ash, so as to be efficiently made porous. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a porous powder, a porous powder and a humidity control material, in particular, a method for producing a porous powder excellent in humidity control, which can be efficiently manufactured using sludge incineration ash, The present invention relates to a porous powder excellent in humidity control manufactured by the method, and an application using the porous powder as a humidity control material.

In recent years, the amount of sewage treatment has been increasing year by year with the spread of sewerage, and the amount of sludge generated has been steadily increasing.
In order to treat such increasing sludge, the sludge is reduced (volume reduction), and therefore, the sludge is incinerated or the sludge is melted.
In particular, incineration of sludge is actively carried out, and the amount of incinerated ash generated is increasing accordingly.

Under such circumstances, most of the generated sludge and incinerated ash from which the sludge was incinerated are disposed of in landfills at the final disposal site. Even in small and medium-sized cities, huge landfill costs are a major problem.
Therefore, for example, the incinerated ash of sludge is pressure-molded and then fired to produce bricks, or the incinerated ash is pressure-granulated into artificial aggregate, or obtained by melting the incinerated ash Techniques using slag as roadbed materials have been proposed, but their application is limited.

Recently, the airtightness of a residence has been increased in order to realize a comfortable living environment, specifically, a comfortable living space.
As a result of improving the airtightness of the living space, a temperature difference occurs between the outdoors and indoors, and in particular, dew condensation in winter causes mold and mites, causing not only indoor dirt but also allergies to the human body, etc. There is a problem.

In order to solve these problems, building materials with excellent humidity control are being developed.
Conventionally, these problems have been alleviated by using wood-based building materials as moisture-absorbing / releasing materials, for example, moisture-controlling materials. It is difficult to use.
In addition, for example, in inorganic building materials, materials mainly composed of diatomaceous earth, zonotlite, tobermorite, etc. have been developed, but can be manufactured at a lower cost, and it is difficult to obtain a desired high humidity control property, and a higher humidity control property Development of materials is desired.

In view of this point, JP 2000-263012 A discloses a porous powder having a BET specific surface area of 6.5 m ² / g or more by adding a sulfuric acid aqueous solution to sludge incinerated ash and then drying it. A method is disclosed, and it is described that the porous powder obtained by such a method can be used as a humidity control material or a deodorizing agent.
Further, JP-A-2002-79081 discloses a method for producing a porous powder having a BET specific surface area of 7 m ² / g or more by adding a hydrochloric acid aqueous solution or a nitric acid aqueous solution to sludge incinerated ash and then drying the slurry. This method is disclosed, and further neutralization treatment (sodium hydroxide, calcium hydroxide, or slaked lime) eliminates the need for acid resistance measures for production equipment, and reduces the occurrence of mold by making it weakly alkaline. It is described that it can be suppressed. It is also described that the porous powder obtained by such a method can be used as a humidity control material or a deodorizing agent.

  JP-A-2004-136189 discloses a treated product obtained by acid treatment (sulfuric acid aqueous solution, hydrochloric acid aqueous solution or sulfuric acid aqueous solution) and neutralization treatment (sodium hydroxide, calcium hydroxide or slaked lime) of sludge incineration ash. Describes a method for producing a porous granular molded body by extrusion molding, and the use of a porous powder molded body obtained by the method as a humidity control material or a deodorizing agent.

However, as shown schematically in FIG. 1, these conventional porous powders were produced by drying sludge incineration ash after acid treatment and neutralization treatment in the production thereof. Since the acid treatment is carried out by contact, the water content is increased, and the drying treatment for evaporating the water after the acid treatment / neutralization treatment requires a lot of energy and takes time, resulting in poor production efficiency. There was a problem.
JP 2000-263012 A JP 2002-79081 A JP 2004-136189 A

Therefore, the object of the present invention is to solve the above-mentioned problems, greatly reduce the labor of the drying process, improve the production efficiency, and effectively reuse the sludge incineration ash and apply it as an excellent humidity control material. It is providing the manufacturing method of the porous powder which can be performed, and the porous powder obtained by the said method.
Another object of the present invention is to provide a humidity control material having excellent moisture absorption / release performance using the porous powder of the present invention.

The present invention has found that the above-mentioned problems can be achieved by kneading acid gas with sludge incineration ash in an acid treatment step in preparing sludge incineration ash by acid treatment and neutralization treatment to prepare porous powder. To achieve.
That is, the method for producing a porous powder according to claim 1 of the present invention is characterized in that acid treatment is performed by contact between sludge incineration ash and acid gas, and then neutralization treatment is performed using a powder neutralizer. Manufacturing method.

The method for producing a porous powder according to claim 2 is characterized in that, in the method for producing a porous powder according to claim 1, the acidic gas is water-soluble.
Furthermore, the method for producing a porous powder according to claim 3 is the method for producing a porous powder according to claim 1 or 2, wherein the sludge incineration ash contains 5 to 40% by mass of water. Is.

The porous powder of the present invention is obtained by the production method of the present invention.
Moreover, the humidity control material of the present invention is a humidity control material containing the porous powder as an active ingredient.

  As in the present invention, the method for producing a porous powder includes acid treatment by contact with sludge incineration ash and acid gas, and then neutralization treatment with a powder neutralizer. Labor saving of the drying process for evaporating water after the process is achieved, and it becomes possible to manufacture with excellent manufacturing efficiency.

  In addition, preferably, since the acid gas is water-soluble, the contained moisture reacts with the acid gas due to the contact between the sludge incineration ash and the acid gas, so that the acid gas is partially in the state of an acid aqueous solution. Is acid-treated to facilitate the formation of a porous structure.

The porous powder obtained by the production method of the present invention has uniform pores and characteristics, and has excellent characteristics as a porous powder.
Furthermore, by using this porous powder as an active ingredient of a humidity control material, it becomes possible to exhibit a good and stable humidity control effect.

The present invention will be described by way of preferred examples, but is not limited thereto.
The method for producing a porous powder according to the present invention is such that acid treatment is performed by contact between sludge incineration ash and acidic gas, and then neutralization is performed using a powder neutralizing agent. In particular, acidic gas is water-soluble. It is desirable to use one.
By adopting such a method, the acid treatment is performed by the contact between the sludge incineration ash and the acid gas, and then the neutralization treatment is performed by the powder neutralizer, so that the drying process for evaporating water takes time. This problem can be solved.

As the raw material sludge incineration ash used in the production method of the present invention, in addition to sludge incineration ash incinerated sludge generated in a sewage treatment plant, incineration of sludge generated by human waste, household wastewater, industrial wastewater treatment, etc. Ashes and the like are generally used, and these are generally sludge dehydrated at a treatment plant and then incinerated. In addition, in order to prevent dust generation, the incinerated ash is often subjected to a hydrotreatment, and the incinerated ash to be transported has a water content of about 5 to 40% by mass.
In the present invention, any of these incineration ash can be used, and may be used alone or in combination.
In particular, since the amount of sludge generated at a sewage treatment plant increases with the spread of sewerage year by year as described above, the method of the present invention is extremely useful as effective reuse of sludge.

In general, incineration ash includes incineration of sludge using a polymer flocculant and incineration of sludge using a lime-based flocculant. Many of them are used and both can be used in the present invention. However, when a lime-based flocculant is used, a large amount of lime is generated, which is not preferable.
The form of the sludge incineration ash is not particularly limited as long as a sufficient dissolution reaction is performed by addition of acid, and finally a homogeneous porous granule can be obtained. Even those formed into a shape, plate shape, tablet shape, or the like can be subjected to contact treatment by addition of an acid and can be used in the method of the present invention.

Examples of the acidic gas blended in the sludge incineration ash acid treatment step include acidic gases such as hydrogen chloride, nitrogen oxides, and sulfur oxides. It is particularly desirable to use hydrogen chloride gas exhibiting water solubility.
This is because the water-soluble acidic gas dissolves in the water contained in the sludge incineration ash and can efficiently react with the incineration ash as an aqueous solution.
For example, hydrogen chloride gas can be generated by mixing sulfuric acid and sulfuric acid compounds with chlorine-based compounds such as potassium chloride, sodium chloride, and calcium chloride and heating them. It is also possible to use gas effectively.
When both are brought into contact with each other in the acid treatment process of sludge incineration ash, hydrogen chloride gas dissolves in the water contained in the incineration ash, reacts with the incineration ash as hydrochloric acid, and an acid treatment reaction is efficiently performed. It is made porous.

  By using such acidic gas for the acid treatment of sludge incineration ash, a large amount of water is contained in the sludge incineration ash due to the conventional use of an acidic solution. This eliminates the need for this and saves labor in the drying process.

The amount of acid gas blended in the sludge incineration ash is 1 part by mass or more, preferably 4 parts per 100 parts by mass of the sludge incineration ash in terms of 100% acid (sulfuric acid, hydrochloric acid, nitric acid, etc.). Add from 0 to 25 parts by weight.
This is because if less than 4.0 parts by mass, the dissolution reaction is not sufficient, and the resulting porous powder may have poor humidity control performance. On the other hand, if it exceeds 25 parts by mass, the surface becomes hard after drying. This is because porosity may be hindered and the moisture absorption / release performance obtained may be reduced.
Moreover, the temperature at the time of a mixing | blending is preferable from the surface which accelerates | stimulates reaction at about 10-90 degreeC.

Thus, by adding acid gas to sludge incineration ash and mixing or kneading, acid gas dissolves in the moisture contained in incineration ash, and acid-soluble components contained in incineration ash dissolve. It can be removed to make the acid-treated product porous.
The kneading time of the incineration ash and the acid gas can be arbitrarily set according to the characteristics of the sludge incineration ash.

The pore volume can be changed by adjusting the acid treatment kneading time.
That is, by increasing the kneading time, it is possible to further increase the fine pore volume of, for example, 10 nm or less, particularly 6 nm or less, and the absorption of water vapor or the like increases as the fine pore volume increases. Moisture release performance can be enhanced.
Usually, it is appropriate that the acid gas is added for about 0.1 hour to 10 days, preferably about 0.1 hour to 1 day.

Next, the obtained acid-treated product is neutralized.
This is because, when the porous powder is used as it is, it is necessary to take measures against acid resistance of the powder production facility, and these problems can be solved by performing the neutralization treatment.

The neutralization treatment is performed by adding an acid aqueous solution to the sludge incineration ash and performing a contact treatment, and then adding a powder neutralizer to bring the pH to about 5.5 to 9.0.
Examples of the neutralizing agent include alkaline materials such as sodium hydroxide (NaOH), calcium hydroxide (Ca (OH) ₂ ), slaked lime, ammonia, limestone (limestone) mainly containing CaCO ₃ , and coral sand. In particular, sodium hydroxide, calcium hydroxide and the like are preferable.
Moreover, the addition amount of a neutralizing agent is added so that a processed material may become pH 5.5-9.0.
In this way, by adding a neutralizing agent to the acid-treated product and mixing or kneading, acid resistance measures in the powder production facility are unnecessary, and a powder having good porosity can be obtained.

More specifically, the production method and production apparatus of the porous powder of the present invention will be described with an optimal example.
In order to produce high-quality porous powder, mixing and kneading work of sludge incineration ash and acid gas, mixing and kneading work of acid-treated sludge incineration ash (acid-treated product) and neutralizing agent are sufficient. And preferably continuously.
Moreover, in order to prevent the reduction of the acid treatment effect and maintain a good working environment, it is desirable to suppress the diffusion of water vapor and acidic gas generated during kneading into the atmosphere.

From such a point of view, the method for producing the porous powder of the present invention is particularly preferably carried out by a closed kneader, and a biaxial extrusion kneader is most preferably used as the kneading mechanism.
The specific configuration of a suitable twin-screw extrusion kneader has two or three screws, and the two shafts can be either a parallel type or a conical type, with the screws obliquely crossing the shafts. It is.
The screw flight can be either a meshing type or a non-meshing type, but the former is preferable because the kneading effect is greater.
The screw rotation direction can be either the same direction or a different direction, but the former is preferable because the kneading effect is large.

Using such a twin-screw extrusion kneader, along the same axis of the extrusion kneader, the sludge incineration ash charging section, the acid aqueous solution charging section, and the neutralizing agent charging section are arranged downstream from the upstream side in the extrusion direction. The sludge incineration ash is introduced in order, acid treatment is performed using the acid gas described above, and neutralization treatment is performed using the neutralizer.
In the method of the present invention, it is necessary to continuously carry out each of the above treatments in a sealed state to increase the sealing degree of the entire kneader. For this reason, the following structure is adopted for each charging unit. To do.
In the sludge incineration ash charging unit, the sludge incineration ash is charged into a twin-screw extrusion kneader by a quantitative feeder such as a circle feeder or a rotary feeder.

In the acidic gas mixing section, acidic gas generated separately as described above is injected, for example, with a metering pump.
Further, in the neutralizing agent charging section, a neutralizing agent such as an aqueous sodium hydroxide solution or a slurry of calcium hydroxide or slaked lime is injected with a metering pump.
Note that all of the mechanisms of these charging units can be automated, and it is possible to automate the entire manufacturing process of the porous powder including the biaxial extrusion kneader using these mechanisms.

Sludge incineration ash and acid-treated products are continuously conveyed along the same axis of a twin-screw extrusion kneader, but the delivery density of these conveyed products is usually not constant, and kneading with the part that mainly contributes to conveyance There is a part in
It is preferable that the acidic gas mixing unit and the neutralizing agent charging unit are disposed at a position where the delivery density of the sludge incinerated ash and the conveyed product which is the acid-treated product is the highest with respect to the biaxial extrusion kneader.

A place where the delivery density of the conveyed product is high is a place where the conveyed product is most concentrated, and is also a place where the conveyed product is clogged in the entire cylinder in the biaxial extrusion kneader.
In such a place, the input liquid (including slurry) and solids are strongly pressed against the conveyed product, and can be uniformly mixed with the conveyed product.
In addition, since these acidic gases and neutralizing agents are introduced from the periphery of the cylinder, these charged materials enter the gap between the conveyed product and the cylinder, reducing the frictional force between the conveyed product and the cylinder, and enabling smooth conveyance. Lubrication action to achieve this is also expected.

  A place where the delivery density of the conveyed product is high is a place where the angle with respect to the axis of the screw approaches a right angle, and when the conveying part and the kneading part are separated in the same axial direction, the inlet part entering the kneading part, etc. It corresponds to.

The processed product extruded from the downstream end of the biaxial extrusion kneader is dried and pulverized as it is to be used as a porous powder. Moreover, it is also possible to put the extruded processed material into a molding machine, dry it after molding, and use it.
Further, it may be directly dried, or may be washed once with water and filtered to dry the residue.
By once washing with water and drying, impurities on the surface of the treated product can be removed, and the adsorption performance is also improved.

  The drying method is not particularly limited, and examples include a drying method using a rotary drum dryer, a paddle dryer, a fluidized bed dryer, an air flow dryer, a centrifugal thin film dryer, etc. A drying method using a drier currently used in a treatment plant can also be adequately handled. Moreover, although a drying temperature is not restrict | limited, For example, 90-300 degreeC is preferable.

The moisture content after drying is preferably 5% by mass or less, and an absolutely dry state shows a particularly excellent effect. If the drying is insufficient, the pore volume decreases and the moisture absorption and desorption performance decreases.
Here, the moisture content is based on the sample weight before drying and after drying for 2 hours at 105 to 110 ° C. in accordance with “Sewage test method (1997 version) Chapter 4 Section 6 Evaporation residue and moisture content”. The weight of the sample is measured and expressed as a percentage of (mass before drying-mass after drying) / (mass before drying).

  As described above, the porous powder, which is the dried product obtained by the method for producing a porous powder of the present invention, has sufficiently exhibited the acid treatment and neutralization treatment effects on sludge incineration ash, Since it is a porous material with a fine pore volume increased, it is highly hygroscopic and also has good moisture release properties, so that it can be suitably used as a humidity control material with improved moisture absorption / release performance compared to conventional ones. it can.

The present invention will be described more specifically with reference to the following examples, comparative examples and test examples. However, the present invention is not limited to the following examples.
Reference example 1
A method for measuring the amount of hydrogen chloride gas generated by mixing and heating potassium chloride and sulfuric acid will be described with reference to FIG.
7. A container (1) with a volume of 250 ml was charged with 7.35 g of potassium chloride (Wako Pure Chemical S) and 9.65 g of sulfuric acid (95% of Wako Pure Chemical S), and 150 ml of pure water was added to a container (2) with a volume of 250 ml. 60 ml of pure water was put into a container (3) having a capacity of 100 ml, the pump was operated at 15 to 20 L / min, and the air was sucked.
After operating the pump for 15 minutes, the heater was heated to maintain the temperature at 70 ° C., and the pump was further operated for 15 minutes to suck air.
Thereafter, the operation of the pump was stopped and the heating of the heater was also stopped, and the amount of Cl in each container (1), (2), (3) contents was measured by potentiometric titration with a silver nitrate solution.
The results are shown in Table 1.

  From Table 1 above, it can be seen that about 60% by mass of potassium chloride was converted to hydrogen chloride gas.

Example 1
As sewage sludge incineration ash, sludge dehydrated after adding a polymer flocculant and incinerated in a fluidized bed incinerator was used. 2 g of the sewage sludge incineration ash (water content: 30% by mass) is put into the container (2) of the schematic diagram 2, and hydrogen chloride gas (container (1 in FIG. 2) is generated under the same conditions as shown in the reference example. ) And was sufficiently kneaded and subjected to acid treatment. This is a ratio equivalent to that 7.2 parts by mass of HCl is added to 100 parts by mass of dry ash.

Next, 4.5 g of calcium hydroxide (Wako Pure Chemicals S) was added to the sewage sludge incineration ash to perform neutralization treatment. This is a ratio equivalent to a ratio of 15 parts by mass of calcium hydroxide to 100 parts by mass of dry ash when the sewage sludge incineration ash is converted to dry ash.
The acid-treated ash and calcium hydroxide were sufficiently kneaded and neutralized, then held at 110 ° C. for 2 hours and dried to obtain a porous powder.
The water content of the porous powder was 0% by mass.

(Comparative example)
Acid treatment / neutralization treatment using sewage sludge incinerated ash and calcium hydroxide in the proportions shown in Table 2, and using the 36% hydrochloric acid aqueous solution prescribed in Table 2 in place of hydrogen chloride gas in the proportions shown in Table 2. And dried at 110 ° C. for 4 hours to obtain a porous powder.

Test Example The moisture absorption / release test of each porous powder obtained in the above Examples and Comparative Examples was performed by the following method.
5 g of each porous powder sample placed in a petri dish was placed in a desiccator whose relative humidity (RH) was adjusted by a saturated solution method.
Specifically, in a constant temperature room at 20 ° C., an environment with a relative humidity of 50% is set by putting a saturated salt solution at the bottom of the desiccator, and the mass (preliminary adjustment) after 24 hours when the moisture adsorption amount reaches almost equilibrium. Wet) A was measured.

Next, each porous powder sample that reached the equilibrium state was set in a constant temperature room at 20 ° C. in the same manner as described above, and an environment with a relative humidity of 90% was set by putting a salt saturated solution at the bottom of the desiccator. Hold the sample for a period of time (moisture absorption), and then hold the sample after moisture absorption again in a constant temperature room at 20 ° C. for 24 hours in a desiccator with a relative humidity of 50% (moisture release). Two cycles were repeated.
In the second cycle, the moisture absorption sample mass B and the moisture release sample mass C were weighed, and the moisture absorption / release amount (%) was determined by the following equation.
Moisture absorption / release (%) = (BC) / A × 100

The test results are shown in Table 3.
However, the mass of the sample after pre-humidification after first setting the sample in a constant temperature room at 20 ° C. and setting the environment with a relative humidity of 50% for 24 hours is expressed as a mass change rate of 100%. The rate of change of the mass of each sample in the process was displayed.

  In the examples, the drying time was 2 hours, whereas in the comparative examples, it was 4 hours until the drying state was completely dried. Thus, labor saving in the drying process could be confirmed.

  The method for producing a porous powder of the present invention can effectively use an acid gas from a waste treatment plant or the like, and the porous powder of the present invention is not only a humidity control material but also a malodorous gas adsorbent. It can also be applied effectively.

FIG. 1 is a diagram schematically showing a conventional porous powder manufacturing process. FIG. 2 is a diagram schematically showing an acid treatment step using an acid gas in producing the porous powder of the present invention.

Claims (5)

A method for producing a porous powder, characterized in that an acid treatment is performed by contact between sludge incineration ash and an acidic gas, followed by a neutralization treatment with a powder neutralizer. The method for producing a porous powder according to claim 1, wherein the acidic gas is water-soluble. 3. The method for producing a porous powder according to claim 1, wherein the sludge incineration ash contains 5 to 40% by mass of water. The porous powder obtained by the manufacturing method in any one of Claims 1-3. A humidity control material comprising the porous powder according to claim 4 as an active ingredient.

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