JP2013202463A - Phosphorus recovery material, phosphorus recovery method and producing method of fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphorus recovery material capable of suppressing the increase of the alkalinity of a phosphoric solution and improving phosphorus recovery performance, and to provide a phosphorus recovery method and a producing method of a fertilizer.SOLUTION: A phosphorus recovery material is the phosphorus recovery material which is a hardened body containing coal ash, gypsum and an alkaline solution, and is capable of suppressing the increase of the alkalinity of a phosphoric solution and improving a phosphorus recovery performance.

Description

  The present invention relates to a phosphorus recovery material that adsorbs phosphorus contained in a solution, a phosphorus recovery method, and a fertilizer manufacturing method.

  Conventionally, phosphorus contained in eutrophic water is one of the water pollution factors in closed water areas such as lakes. As one of the methods for reliably adsorbing such phosphorus to prevent drought nutrition, a cement-based phosphorus adsorbent is introduced into phosphorus-containing wastewater to adsorb phosphorus.

  For example, a phosphorus adsorbent containing 100 parts by weight of an apatite-forming substance, 3 to 100 parts by weight of a hydraulic binder, and 2 to 50 parts by weight of an aqueous resin emulsion is added to a solution containing phosphorus. However, a cement-based phosphorus adsorbent that is immersed for a time sufficient to substantially reduce the phosphorus concentration in the solution containing phosphorus is disclosed (for example, see Patent Document 1).

JP 2003-47974 A

  By the way, it is known that cement-based phosphorus adsorbent reacts with phosphorus (phosphoric acid) to generate calcium phosphate (hydroxyapatite) to adsorb phosphorus, which is included in cement-based phosphorus adsorbent. This is because calcium hydroxide generated by the hydration reaction of the calcium component dissolves in water and calcium reacts with phosphorus. However, calcium hydroxide is a strong alkali, and when dissolved in water, the pH of water quality such as lakes and marshes is greatly increased, and the alkalinity becomes high. In particular, in fresh water or still water, the pH value increases and the environment may be deteriorated.

  The present invention has been made in view of the above, and suppresses an increase in alkalinity of a solution containing phosphorus, and improves a phosphorus recovery performance, a phosphorus recovery material, a phosphorus recovery method, and manufacture of a fertilizer It aims to provide a method.

  A first invention of the present invention for solving the above-described problem is a phosphorus recovery material, which is a mixture containing coal ash, gypsum, and an alkaline solution.

  A second invention is a phosphorus recovery material according to the first invention, wherein the mixture is pulverized or granulated to a size within a predetermined range.

  A third invention is the phosphorus recovery material according to the first or second invention, further comprising slag.

  In a fourth aspect of the invention, there is provided a cured body preparation step for preparing a mixture containing coal ash, gypsum, and an alkaline solution, and the mixture is immersed in a solution containing phosphorus for a predetermined time, or a solution containing phosphorus in the mixture is predetermined. And a phosphorus adsorption process for passing water for a period of time.

  5th invention produces | generates fertilizer by phosphorus collection | recovery method as described in 4th invention, and the phosphorus collection | recovery material which adsorb | sucked the phosphorus obtained by the said phosphorus collection | recovery method as it is, or grind | pulverizes, or scrapes an outer surface And a fertilizer production process.

  According to a sixth invention, in the fifth invention, the fertilizer generating step reuses the residue of the phosphorus recovery material from which the outer surface containing phosphorus is scraped off as a new phosphorus recovery material or earthwork material. It is the manufacturing method of the fertilizer characterized.

  According to the phosphorus collection | recovery material of this invention, while showing that the alkaline property of the solution containing phosphorus becomes high, there exists an effect that phosphorus collection | recovery performance can be improved.

FIG. 1 is an X-ray diffraction diagram of the phosphorus recovery material according to the present embodiment before and after phosphorus adsorption. FIG. 2 is a diagram showing processing steps of the phosphorus recovery method according to the present embodiment. FIG. 3 is a diagram illustrating the processing steps of the fertilizer manufacturing method according to the present embodiment. FIG. 4 is a diagram showing the change over time in the phosphorus recovery rate and the change over time in pH of the phosphorus recovery material according to this example. FIG. 5 is a diagram showing the change over time in the phosphorus recovery rate and the change over time in pH of the phosphorus recovery material according to this example. FIG. 6 is a graph showing changes in the phosphorus recovery rate and pH over time of the cement-based cured body according to the comparative example. FIG. 7 is a diagram showing a change over time in the passage flow rate of the phosphorus recovery material according to the present example and a change over time in the passage flow rate of the cement-based cured body of the comparative example.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the following modes for carrying out the invention (hereinafter referred to as embodiments). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be appropriately combined.

<Phosphorus recovery material>
The phosphorus collection | recovery material which concerns on this embodiment is a hardening body containing coal ash, gypsum, and an alkaline solution. In addition, although it is set as the hardening body in this embodiment, the mixture containing coal ash, gypsum, and an alkaline solution may be sufficient.

(Coal ash)
The coal ash contained in the phosphorus recovery material according to the present embodiment is not particularly limited, and generally known coal ash can be used. Examples of the coal ash include coal ash generated when coal is burned in a coal-fired power plant or the like. This coal ash is generated when finely pulverized coal is burned in a boiler. Coal ash includes, for example, a clinker that pulverizes massive porous ash that has fallen to the bottom of the boiler after ash particles melted and solidified when coal is burned, and an electric dust collector that floats with combustion gas. And fly ash of fine spherical particles collected in. Generally, clinker and fly ash occur at a ratio of about 1: 9. There are various components included in the coal ash, and the main components are silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), and iron oxide (Fe ₂ O ₃ ). Further, it is known that coal ash has a phosphorus adsorption ability because it contains a calcium component in a small amount. As the coal ash used in the present embodiment, fly ash that is generated in large quantities among coal ash is preferably used from the viewpoint of effective utilization of by-products.

  The content of coal ash (hereinafter also referred to as “fly ash”) is preferably 30 parts by mass or more and 60 parts by mass or less, with respect to 100 parts by mass of the total amount of each component of the phosphorus recovery material according to the present embodiment. Preferably they are 35 to 55 mass parts. It can have sufficient intensity | strength at the time of hardened | cured material manufacture as content of coal ash is in the said range.

  In addition, when fly ash is mixed with conventional cement-based phosphorus adsorbents, silicon dioxide contained in fly ash reacts with calcium hydroxide produced by the hydration reaction to produce calcium silicate hydrates (pozzolana). Calcium hydroxide is consumed for the reaction), the calcium component for reacting with phosphorus is gradually reduced, and the cement-based phosphorus adsorbent is reduced in its ability to adsorb phosphorus. On the other hand, since the phosphorus collection | recovery material which concerns on this embodiment can contain many calcium which reacts with phosphorus by containing many gypsum, it can improve a phosphorus collection | recovery rate.

(plaster)
The gypsum (CaSO ₄ ) contained in the phosphorus recovery material according to the present embodiment is not particularly limited, and generally known gypsum can be used. Examples of the gypsum include flue gas desulfurization gypsum that is a by-product generated in a flue gas desulfurization process for removing sulfur oxides in exhaust gas in a coal-fired power plant or the like. Note that the gypsum of this embodiment is not limited to flue gas desulfurization gypsum, and general gypsum and waste gypsum board may be reused.

  The phosphorus recovery material of the present embodiment is different from the case where calcium hydroxide produced during cement hydration reaction is eluted to show strong alkali, but this is the basic despite using sodium hydroxide which is strong alkali. Therefore, it is considered that a significant increase in pH is suppressed by reducing the amount of strong alkali that is basically eluted by being incorporated as a part of a new product.

  The content of gypsum is preferably 15 parts by mass or more and 40 parts by mass or less, more preferably 20 parts by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the total amount of each component of the phosphorus recovery material according to this embodiment. . If the gypsum content is within the above range, the effect on the strength of the cured body is small, and a large amount of calcium components that can be reacted with phosphorus can be contained, so that phosphorus can be sufficiently adsorbed.

(Alkaline solution)
Examples of the alkaline solution contained in the phosphorus recovery material according to the present embodiment include aqueous solutions of water glass, alkali metal hydroxides, alkaline earth metal hydroxides, and the like. Examples of the alkali metal hydroxide include solutions of sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and the like.

The water glass is, for example, a concentrated aqueous solution of sodium silicate (sodium salt of metasilicate: Na ₂ SiO ₃ ), and is obtained by dissolving sodium silicate in water and heating. In addition to the sodium salt of metasilicic acid, Na ₄ SiO ₄ , Na ₂ Si ₂ O ₅ , Na ₂ Si ₄ O _{9 and the} like can be mentioned. The alkali component contained in the water glass generally contains sodium oxide Na ₂ O (in some cases potassium oxide K ₂ O), the composition is Na ₂ OnSiO ₂ (n = 2 to 4), and a small amount of iron oxide. Fe ₂ O _{3 and the} like are contained, and the moisture is about 10% to 30%. As the sodium hydroxide (NaOH) solution, for example, 25% caustic soda solution commercially available for industrial use can be suitably used because it is easily available and easy to handle.

The content of the alkaline solution is preferably 20 parts by mass or more and 30 parts by mass or less, more preferably 25 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the total amount of each component of the phosphorus recovery material according to the present embodiment. is there. When the content of the alkaline solution is within the above range, the phosphorus recovery material according to this embodiment is cured by promoting elution of fly ash SiO ₂ and Al ₂ O ₃ and dissolution of gypsum, and is stable in water. The shape can be kept.

An alkaline solution has the effect | action which hardens a mixture by mixing with coal ash and gypsum. That is, elution of silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ) contained in coal ash and calcium components contained in gypsum proceeded in the presence of strong alkali, and polymerization reaction or hydration reaction By doing so, a cured body is formed.

  Since the phosphorus recovery material according to the present embodiment mixes coal ash, gypsum, and an alkaline solution to form a hardened body, it is not necessary to use cement or lime that generates a large amount of carbon dioxide during production. Considered phosphorus recovery material.

  Moreover, the phosphorus collection | recovery material which concerns on this embodiment grind | pulverizes or granulates the hardened | cured material of the mixture of coal ash and gypsum with an alkaline solution to the size of a predetermined range. The size is not determined, but if it is too large, the surface area of the material is reduced and the phosphorus recovery rate is lowered, so that it is preferably 3 mm or more and 5 mm or less. When the size of the phosphorus recovery material is within the above range, the phosphorus recovery material according to the present embodiment is easy to handle and can maintain a high phosphorus recovery rate. In addition, the shape of the pulverized or granulated phosphorus recovery material is not particularly limited to a spherical shape.

  When a large amount of gypsum is added to a conventional cement-based phosphorus adsorbent, it is considered that the hardened body collapses due to the formation of ettringite and the strength of the hardened body is reduced, but in the phosphorus recovery material of this embodiment, ettringite is Almost no generation. Therefore, a large amount of desulfurized gypsum can be contained.

Further, the phosphorus recovery material according to the present embodiment, by adding the alkali solution to the coal ash and gypsum new product _{(Sesanaito: Ca 1 + xNa 4-x} (SO 4) 3 (OH) X (1-x) H ₂ O can be generated, and this new product (sesanite) elutes from the phosphorus recovery material on the surface of the cured body in a relatively short time and reacts with phosphorus to immobilize phosphorus. However, conventional desulfurized gypsum has low solubility and very low ability to adsorb phosphorus, whereas the phosphorus recovery material according to this embodiment uses coal ash. Since sesanite produced from a mixture of gypsum and gypsum and an alkaline solution elutes on the surface of the cured body and reacts with phosphorus, it is considered that phosphorus recovery performance can be improved.

  FIG. 1 is an X-ray diffraction pattern of the phosphorus recovery material before and after phosphorus adsorption in the present embodiment. Table 1 shows the chemical composition analysis results before and after phosphorus adsorption of the phosphorus recovery material in this embodiment. As shown in FIG. 1, in the phosphorus recovery material before phosphorus adsorption, sesanite was recognized in addition to mullite derived from coal ash, quartz, and gypsum derived from desulfurized gypsum, which were recognized as crystalline substances. This sesanite is a sulfate mineral of Na and Ca. On the other hand, it is presumed that the phosphorus recovery material after phosphorus adsorption has solubility because sesanite is not observed. Moreover, as shown in FIG. 1, hydroxyapatite was recognized from the X-ray diffraction result of the surface part of the phosphorus collection | recovery material after phosphorus adsorption | suction. Therefore, it is considered that the Ca component due to the dissolution of gypsum and sesanite precipitated as hydroxyapatite and recovered phosphorus.

The phosphorus recovery material according to the present embodiment can further include slag. The slag contained in the phosphorus recovery material according to the present embodiment is not particularly limited, and generally known slag can be used. As slag, blast furnace slag can be mentioned, for example. Blast furnace slag is a blast furnace at a steelworks. A molten blast furnace slag produced simultaneously with pig iron is quenched with water, dried and ground, and is a sandy amorphous material (glassy). Blast furnace slag is mainly composed of CaO, SiO ₂ and Al ₂ O ₃ and has chemical components similar to cement. This blast furnace slag has a latent hydraulic property that causes a rapid reaction when contacted with an alkaline solution. As the slag used in the present embodiment, a blast furnace slag that reacts with an alkali solution and hardens can be suitably used. Therefore, since the phosphorus recovery material according to the present embodiment further contains slag, the component of the slag reacts with the alkaline solution, so that the strength of the hardened body of the mixture obtained by mixing coal ash, gypsum and the alkaline solution is increased. Can be improved. In addition, since this slag is added to prevent strength reduction when a large amount of desulfurized gypsum is added, the amount of slag can be reduced by reducing the amount of desulfurized gypsum.

  The phosphorus collection | recovery material of this embodiment is a hardening body containing coal ash, gypsum, and an alkaline solution. As the coal ash and gypsum contained in the phosphorus recovery material, coal ash and desulfurized gypsum, which are by-products generated in large quantities in a coal-fired power plant or the like, can be used. Conventionally, coal ash, which is a by-product, has been used effectively as a concrete admixture when producing concrete, and desulfurized gypsum is effectively used as a raw material for gypsum board, a raw material for cement, a soil improvement material, etc. Since coal ash and desulfurized gypsum are produced in large quantities, further effective use expansion is desired. As the phosphorus recovery material according to the present embodiment, coal ash or desulfurized gypsum as a by-product generated in a large amount in a coal-fired power plant can be suitably used. Moreover, the phosphorus collection | recovery material of this embodiment has the characteristics that it can suppress that the solution containing phosphorus becomes alkaline while adsorbing phosphorus. Therefore, the phosphorus collection | recovery material of this embodiment can utilize effectively coal ash, desulfurization gypsum, etc. which generate | occur | produce in large quantities as a by-product in a coal-fired power plant.

  Since the phosphorus collection | recovery material of this embodiment is a hardening body which can be easily manufactured only with coal ash, gypsum, and an alkaline solution, very cheap manufacture is attained. Therefore, although the phosphorus adsorption amount of the phosphorus collection material of this embodiment is slightly small, it can be suitably used as an economical phosphorus collection material.

(Method for producing phosphorus recovery material)
A method for producing a phosphorus recovery material according to the present embodiment includes a predetermined amount of the above fly ash, desulfurized gypsum, and an alkaline solution, which are sufficiently kneaded using a stirring device such as a mixing mixer, and uniformly Mix by dispersing. Next, a cured product containing coal ash, gypsum, and an alkaline solution can be obtained by steaming or drying curing the obtained mixture at a predetermined temperature for a predetermined time. Then, the obtained cured body can be pulverized or granulated into a predetermined range of size to produce a phosphorus recovery material. In addition, the grinder and granulator used for grind | pulverizing or granulating the hardening body of this embodiment are not specifically limited, A well-known apparatus can be applied.

  The predetermined temperature is preferably 50 ° C. or higher and 70 ° C. or lower, more preferably 55 ° C. or higher and 65 ° C. or lower, and further preferably 60 ° C. The predetermined time is preferably 24 hours or longer and 72 hours or shorter, more preferably 36 hours or longer and 60 hours or shorter, and even more preferably 48 hours. When the temperature and curing time are within the above ranges, the phosphorus recovery material according to the present embodiment can express the same strength as the conventional cement-based phosphorus recovery material, and is easy to handle, and phosphorus A stable shape can be maintained in the solution.

<Phosphorus recovery method>
An example of a phosphorus recovery method using the phosphorus recovery material according to this embodiment having the above-described configuration will be described with reference to the drawings. FIG. 1 is a flowchart showing an example of processing steps of the phosphorus recovery method according to the present embodiment. As shown in FIG. 1, the phosphorus collection | recovery method of this embodiment has the following processes.
(A) Hardened body preparation process (step S11) which produces the mixture (hardened body) containing coal ash, gypsum, and an alkaline solution
(B) Phosphor recovery material molding step for crushing or granulating the cured body into a predetermined size range (step S12)
(C) Phosphor recovery material filling step of filling the container with phosphorus recovery material (step S13)
(B) A phosphorus adsorption step in which a container filled with phosphorus recovery material is immersed in a solution containing phosphorus for a predetermined time, or a solution containing phosphorus is passed through a container filled with phosphorus recovery material for a predetermined time (step S14).

(Curing body manufacturing process: Step S11)
As described above, the hardened body preparation step mixes a predetermined amount of coal ash, desulfurized gypsum, and an alkaline solution, and after mixing these, the mixture is dried and cured at a predetermined temperature for a predetermined time (step S11). Thereby, handling is facilitated by forming a cured body obtained by curing a mixture containing coal ash, gypsum, and an alkaline solution. Here, the predetermined temperature is preferably 50 ° C. or higher and 70 ° C. or lower, more preferably 55 ° C. or higher and 65 ° C. or lower, and further preferably 60 ° C.

  The predetermined time is preferably 24 hours or longer and 72 hours or shorter, more preferably 36 hours or longer and 60 hours or shorter, and even more preferably 48 hours. When the temperature and curing time are within the above ranges, the phosphorus recovery material according to the present embodiment can express the same strength as a conventional cement-based phosphorus adsorbent, and is easy to handle. A stable shape can be maintained in the solution.

(Phosphorus recovery material molding process: Step S12)
In the phosphorus recovery material forming step, the obtained cured body is pulverized or granulated into a predetermined range of size to form a phosphorus recovery material (step S12). In addition, the grinder and granulator used in order to grind | pulverize or granulate the hardening body of this embodiment are not specifically limited, A well-known apparatus can be applied.

(Phosphorus recovery material filling step: step S13)
In the phosphorus recovery material filling step, the phosphorus recovery material obtained in the phosphorus recovery material molding step (step S12) is filled in a container that can be easily replaced and through which water can flow (step S13). The container is not particularly limited as long as it can hold a phosphorus recovery material in a predetermined range and can circulate water, and a known container such as a mesh shape or a perforated shape can be used. . Further, the shape of the container is not particularly limited.

(Phosphorus adsorption process: Step S14)
In the phosphorus adsorption process, a container filled with a phosphorus recovery material is immersed in a solution containing phosphorus, such as a wastewater treatment in a river, a lake, or a manufacturing plant, for a predetermined time that can sufficiently adsorb phosphorus, or a solution containing phosphorus at a predetermined flow rate Is continuously passed through the container filled with the phosphorus recovery material for a predetermined time, and phosphorus is adsorbed on the surface of the phosphorus recovery material and recovered (step S14). The time for dipping in the solution containing phosphorus can be set as appropriate based on the concentration of phosphorus in the solution containing phosphorus to be treated.

When phosphorus is recovered by passing a solution containing phosphorus through a container filled with a phosphorus recovery material, the space velocity (SV) of the processing solution passing through the container is preferably 15 h ⁻¹ or more. 35 h ⁻¹ or less. If the space velocity is reduced, the container (or the processing apparatus) can be made compact, which contributes to cost reduction. If the space velocity is too high, the phosphorus recovery process is not sufficiently performed. Therefore, when the space velocity is within the above range, the phosphorus recovery method of the present embodiment can sufficiently adsorb phosphorus to the phosphorus recovery material and improve the phosphorus recovery performance.

  In addition, the linear velocity (LV) of the treatment solution that passes through the container filled with the phosphorus recovery material is preferably 10 m / hr or more and 20 m / hr or less. If the linear velocity is reduced, the container can be made compact, which contributes to cost reduction. If the linear velocity is too high, the phosphorus recovery process is not sufficiently performed. Therefore, when the linear velocity is within the above range, the phosphorus recovery method of the present embodiment can sufficiently adsorb phosphorus to the phosphorus recovery material and improve the phosphorus recovery performance.

  The predetermined time and the predetermined flow rate can be appropriately set based on the processing amount of the solution containing phosphorus, the concentration of phosphorus in the solution containing phosphorus to be processed, and the like.

  By applying the phosphorus recovery method using the phosphorus recovery material according to the present embodiment, for example, an expensive phosphorus recovery facility is not required in a wastewater treatment process in a manufacturing plant that handles high-concentration phosphorus-containing water. Since it can suppress that the alkalinity of the solution to contain becomes high, it is not necessary to adjust pH of the waste_water | drain discharged | emitted, and phosphorus can be collect | recovered with a phosphorus collection | recovery material.

<Manufacturing method of fertilizer>
An example of a fertilizer manufacturing method using the phosphorus recovery material according to the present embodiment having the above-described configuration will be described with reference to the drawings. FIG. 2 is a flowchart showing an example of processing steps of the fertilizer manufacturing method according to the present embodiment. As shown in FIG. 2, the manufacturing method of the fertilizer of this embodiment has the following processes.
(A) Hardened body production process for producing a mixture (hardened body) containing coal ash, gypsum, and an alkaline solution (step S21)
(B) Phosphor recovery material molding step (step S22) for crushing or granulating the cured body into a predetermined size range
(C) Phosphor recovery material filling step of filling the container with phosphorus recovery material (step S23)
(D) Phosphorus adsorption process in which a container filled with phosphorus recovery material is immersed in a solution containing phosphorus for a predetermined time, or a solution containing phosphorus is passed through a container filled with phosphorus recovery material for a predetermined time (step S24).
(E) Fertilizer generation step (step S25) in which the phosphorus recovery material that has adsorbed phosphorus in the phosphorus adsorption step (step S24) is directly or pulverized, or scrapes the outer surface to generate fertilizer.

(Curing body production process (step S21) to phosphorus adsorption process (step S24))
Since the cured body preparation process (step S21) to the phosphorus adsorption process (step S24) are the same as the cured body preparation process (step S11) to the phosphorus adsorption process (step S14) of the above-described phosphorus recovery method, description thereof is omitted. To do.

(Fertilizer production process: Step S25)
In the fertilizer generation step, the phosphorus recovery material that has sufficiently adsorbed phosphorus in the above-described phosphorus recovery method is taken out of the container, and the phosphorus recovery material is directly fertilized or crushed to fertilize or scrape the surface to generate fertilizer. (Step S25). When the phosphorus recovery material is used as it is as a fertilizer, for example, it is a case where the particle diameter is granulated to about 3 mm to 5 mm, and is reused as it is as a fertilizer. Moreover, when pulverizing to make a fertilizer is, for example, solidified in a lump shape, all of the pulverized phosphorus recovery material is reused as fertilizer. In addition, when scraping the surface of the phosphorus recovery material to make a fertilizer, only the surface of the phosphorus recovery material is scraped, and only the portion that has been adsorbed and filled with phosphorus is reused as the fertilizer. The remaining residue is reused as new phosphorus recovery material, raw material of phosphorus recovery material, or earthwork materials such as road materials, ground improvement materials, and landfill materials.

  In addition, when scraping the surface of the phosphorus collection | recovery material of this embodiment and collect | recovering phosphorus, it is possible to adjust the scraping amount so that the reference | standard of byproduct phosphate fertilizer may be satisfied.

  By using the fertilizer manufacturing method of the present embodiment, when recovering a phosphorus recovery material that has sufficiently adsorbed phosphorus, it is possible to easily recover the phosphorus recovery material by recovering a container filled with the phosphorus recovery material. it can.

  Therefore, according to the fertilizer manufacturing method of the present embodiment, the phosphorus recovery material adsorbing phosphorus can be easily recovered, and the fertilizer can be easily manufactured from the recovered phosphorus recovery material. Recycling can be performed. In addition, by reusing phosphorus recovery material as fertilizer, it is useful as an unprecedented new method of using industrial by-products such as coal ash and desulfurized gypsum.

  Although the use of the phosphorus collection | recovery material which concerns on this embodiment is not specifically limited, Since the phosphorus collection | recovery material which concerns on this embodiment has the above outstanding characteristics, it is various manufacture which handles high concentration phosphorus containing water. It is suitably used for wastewater treatment in plants, sewerage, livestock industry and the like.

  As described above, the phosphorus recovery material, the phosphorus recovery method, and the fertilizer manufacturing method of the present invention have been described in detail. However, the present invention is not limited to the above examples, and various modifications and improvements can be made without departing from the gist of the present invention. May be performed.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these.

<Production of phosphorus recovery material>
Each component shown in Table 2 below was blended in the mass ratio (parts by mass) shown in Table 2, and these were uniformly mixed, and then the mixture was dried and cured at 60 ° C. for 48 hours to obtain the phosphorus recovery material of each Example. A cured product was obtained. And after grind | pulverizing the obtained hardening body, it grind | pulverized to the size of 3 mm-5 mm, and obtained the phosphorus collection | recovery material of each Example. The cement-based cured body of Comparative Example 1 was prepared by blending the components shown in Table 2 below in the mass ratio (parts by mass) shown in Table 2, and uniformly mixing them, followed by curing at 60 ° C. under saturated steam for 24 hours. By doing so, a cement-based cured body was obtained. The obtained cement-based cured body was pulverized and then crushed to a size of 3 mm to 5 mm to obtain a cement-based cured body of Comparative Example 1. About each Example and the comparative example, the compressive strength was measured by the method shown below. Table 3 shows the measurement results.

(Compressive strength)
The compressive strength test was performed according to JIS A1108. The compressive strength was judged to be good on the basis of 10 MPa or more as the strength with which the cured product can maintain stability in water.

  Example 1 is an example which does not contain blast furnace slag, and is obtained by dissolving sodium hydroxide powder in water as an alkaline solution. The obtained phosphorus recovery material 1 of Example 1 had a compressive strength comparable to that of the cemented cured body.

  Example 2 is an example which does not contain blast furnace slag, in which sodium hydroxide powder is added as an alkaline solution to improve the strength and a 25% sodium hydroxide solution. The resulting phosphorus recovery material 2 of Example 2 had a compressive strength comparable to that of the cemented cured body.

  In Example 3, blast furnace slag was further added to improve the strength of the cured body. The resulting phosphorus recovery material 3 of Example 3 had a compressive strength comparable to that of the cemented cured body.

  Therefore, it was confirmed that the phosphorus collection | recovery materials 1-3 of Examples 1-3 have the intensity | strength comparable as a cement hardening body. Therefore, since the phosphorus collection | recovery material of a present Example has the intensity | strength comparable as a cement-type hardened | cured material, it can be easily handled and can maintain a stable shape in the solution containing phosphorus.

<Phosphorus recovery test and passing flow rate test>
The phosphorus collection | recovery material 1 obtained above as Example 1 and the phosphorus collection | recovery test and the passage flow rate test were done about the cement-type hardening body as the comparative example 1. FIG. The change over time in the phosphorus recovery rate, the change over time in pH, and the change over time in the passage flow rate were measured by the following methods. The test results are shown in FIGS.

[Phosphorus recovery test]
A solution containing phosphorus having the following concentration was passed through a container filled with a phosphorus recovery material, and the phosphorus recovery rate was determined from the outlet concentration relative to the inlet concentration. At the same time, the change in pH with time was measured. The results are shown in FIGS. 3 shows the case of the water flow rate of 0.2 L / min in Example 1, FIG. 4 shows the case of the water flow rate of 0.15 L / min in Example 1, and the water flow rate of Comparative Example 1 is 0. FIG. 5 shows the case of 2 L / min.
-Phosphorus concentration of the solution containing phosphorus that has passed through: 23 ppm
・ Water flow rate: 0.2L / min, 0.15L / min
・ Phosphor recovery material size: Maximum diameter 3mm ~ 5mm
-Filling container: φ35mm x 500mm cylindrical container (0.8ton / m ³ )

(Evaluation)
-The phosphorus recovery rate was judged to be good when it was 20% or more, and the recovery performance was judged to be poor when it was below 20%.

[Passing flow test]
A solution containing phosphorus having the concentration shown below was passed through a container filled with a phosphorus recovery material, and the flow rate was measured. The results are shown in FIG. In addition, the water flow rate of Example 1 was 0.2 L / min and 0.15 L / min, and the water flow rate of Comparative Example 1 was 0.2 L / min.
-Phosphorus concentration of the solution containing phosphorus that has passed through: 23 ppm
・ Water flow rate: 0.2L / min, 0.15L / min
・ Phosphor recovery material size: Maximum diameter 3mm ~ 5mm
-Filling container: φ35mm x 500mm cylindrical container (0.8ton / m ³ )

(Evaluation)
-The passage flow rate was judged good if the flow rate after 15 hours maintained 80% or more of the initial flow rate.

(Test results)
FIGS. 3 and 4 are diagrams showing the change over time in the phosphorus recovery rate and the change over time in pH of the phosphorus recovery material according to this example. FIG. 5 is a graph showing changes over time in the phosphorus recovery rate and pH of the cement-based cured body according to the comparative example. FIG. 6 is a diagram showing a change over time in the passage flow rate of the phosphorus recovery material according to the present example and a change over time in the passage flow rate of the cement-based cured body of the comparative example.

  FIG. 3 shows a case where the water flow rate is 0.2 L / min in Example 1. The left vertical axis indicates phosphorus recovery rate (%), the right vertical axis indicates pH, and the horizontal axis indicates elapsed time. The solid line represents the phosphorus recovery rate and the dotted line represents the pH. As shown in FIG. 3, the phosphorus recovery material of Example 1 has an initial phosphorus recovery rate of about 90%, and gradually decreases with the passage of time. After 5 hours, the phosphorus recovery rate is about 30%. Become. However, after that, the phosphorus recovery rate was maintained at 20% or more, and thus it was confirmed that the phosphorus recovery rate was good. Further, the accumulated phosphorus recovery amount after 16 hours obtained from the inlet phosphorus concentration, phosphorus recovery rate and water passage time is about 16545922 mg, and the phosphorus recovery amount per 1 g of phosphorus recovery material is about 4.3 mg / g. In view of the fact that the phosphorus recovery material of Example 1 is extremely inexpensive, it can be seen that it has a sufficient amount of adsorption. Moreover, although pH of Example 1 exceeded pH11 immediately after the start of a test, it fell after that, and it became about pH 7 after 5 hours progress, and it was confirmed that it was maintaining neutrality after that.

  Therefore, the phosphorus collection | recovery material of Example 1 can maintain that the collection | recovery performance of phosphorus while being able to suppress that the solution containing phosphorus becomes alkaline in the case of a water flow rate of 0.2 L / min. I can say that.

  FIG. 4 shows the case of the water flow rate of 0.15 L / min in Example 1, the left vertical axis shows the phosphorus recovery rate (%), the right vertical axis shows the pH, and the horizontal axis shows the elapsed time. The solid line represents the phosphorus recovery rate and the dotted line represents the pH. As shown in FIG. 4, the phosphorus recovery material of Example 1 has an initial phosphorus recovery rate of 90% or more and gradually decreases with time, but after 5 hours, the phosphorus recovery rate becomes 40%. It will be higher. However, after that, although the phosphorus recovery rate gradually decreased, the phosphorus recovery rate was maintained at 20% or more, and thus it was confirmed that the phosphorus recovery rate was good. When compared with FIG. 3, it was confirmed that since the flow rate of water was small, the decrease in the phosphorus recovery rate was slow, and a high phosphorus recovery rate was maintained. Further, the accumulated phosphorus recovery amount after 17.5 hours obtained from the inlet phosphorus concentration, phosphorus recovery rate and water passage time of Example 1 is about 1408.857 mg, and the phosphorus recovery amount per 1 g of phosphorus recovery material Is about 3.6 mg / g, and it can be seen that the phosphorus recovery material of Example 1 has a sufficient amount of adsorption considering that it is extremely inexpensive. In addition, although the pH of Example 1 exceeded pH 11 immediately after the start of the test, it decreased after that, and after about 5 hours, it was about pH 8, and after that, it was confirmed that the pH was almost neutral at about pH 7. It was done.

  Therefore, when the phosphorus collection | recovery material of Example 1 is water flow volume 0.15L / min, while being able to suppress that the solution containing phosphorus becomes alkaline, it can maintain the collection | recovery performance of phosphorus. I can say that.

  FIG. 5 shows a case where the water flow rate of the cementitious cured body of Comparative Example 1 is 0.2 L / min. The vertical axis left indicates the phosphorus recovery rate (%), the vertical axis right indicates the pH, and the horizontal axis indicates the elapsed time. ing. The solid line represents the phosphorus recovery rate and the dotted line represents the pH. As shown in FIG. 5, it was confirmed that the cement-based cured body of Comparative Example 1 had a maximum initial phosphorus recovery rate of about 60%, and decreased almost linearly over time. Accordingly, after 10 hours, the phosphorus recovery rate is less than 20% and the phosphorus recovery performance is lowered, so that the phosphorus recovery rate is judged to be inferior. Further, the accumulated phosphorus recovery amount after 9 hours obtained from the inlet phosphorus concentration, phosphorus recovery rate and water passage time of Comparative Example 1 is about 1186.591 mg, and the phosphorus recovery amount per 1 g of phosphorus recovery material is 3 It was about 1 mg / g, and it was confirmed that the amount of adsorption was smaller than that of Example 1. Further, the pH of Comparative Example 1 exceeded pH 12 immediately after the start of the test, and thereafter gradually decreased, and after about 10 hours, the pH was about 10, and the phosphorus-containing solution was not suppressed from becoming alkaline. It was confirmed.

  Therefore, it can be said that the cementitious hardened body of Comparative Example 1 cannot suppress the phosphorus-containing solution from becoming alkaline, and the phosphorus recovery capability is inferior to the phosphorus recovery material of Example 1.

  In FIG. 6, the vertical axis represents the water flow rate (L / min) of the solution containing phosphorus, and the horizontal axis represents the elapsed time. As shown in FIG. 6, the flow rate of the phosphorus recovery material of Example 1-1 is about 16 hours from the initial flow rate of about 0.22 L / min when the water flow rate is 0.2 L / min (open square). After the elapse of time, it was confirmed that a sufficient flow rate was maintained although it decreased to about 0.18 L / min and about 82%. In addition, the time-dependent change of the passage flow rate of the phosphorus collection | recovery material of Example 1-1 was substantially the same as the case of the cement-type hardened body (water flow rate 0.2L / min, black square) of the comparative example 1.

  In addition, when the flow rate of the phosphorus recovery material of Example 1-2 is a water flow rate of 0.15 L / min (square x), the flow rate is about 0 after about 17 hours from the initial flow rate of about 0.14 L / min. It was confirmed that a sufficient flow rate was maintained although it decreased to about 93% at .13 L / min.

  Therefore, since it is possible to maintain a flow rate equal to or higher than that of a conventional cement-based hardened body having low phosphorus adsorption performance, the phosphorus recovery materials of Examples 1-1 and 1-2 can be used even when water containing a solution containing phosphorus is passed. It can be said that phosphorus recovery performance can be maintained because phosphorus can be sufficiently adsorbed.

  Therefore, the phosphorus collection | recovery material which is a hardening body containing the coal ash of an Example, gypsum, and an alkaline solution can suppress that the alkalinity of the solution containing phosphorus becomes high, and is excellent in the collection | recovery performance of phosphorus. It has been found.

  As described above, the phosphorus recovery material according to the present invention can suppress an increase in the alkalinity of the solution containing phosphorus and maintain the phosphorus recovery performance. It can be suitably used as a phosphorus recovery material in wastewater treatment containing phosphorus at a concentration.

S11, S21 Cured body preparation process S12, S22 Phosphorus recovery material molding process S13, S23 Phosphorus recovery material filling process S14, S24 Phosphorus adsorption process S25 Fertilizer generation process

Claims (6)

  A phosphorus recovery material, which is a mixture containing coal ash, gypsum, and an alkaline solution.   The phosphorus recovery material according to claim 1, wherein the mixture is pulverized or granulated into a predetermined range of size.   The phosphorus recovery material according to claim 1, further comprising slag. A cured body preparation step of preparing a mixture containing coal ash, gypsum, and an alkaline solution;
Phosphorus adsorption step of immersing the mixture in a solution containing phosphorus for a predetermined time, or passing a solution containing phosphorus in the mixture for a predetermined time;
The phosphorus collection | recovery method characterized by including this. The phosphorus recovery method according to claim 4,
A fertilizer generating step of generating fertilizer by directly or pulverizing the phosphorus recovery material adsorbing phosphorus obtained by the phosphorus recovery method or scraping the outer surface;
The manufacturing method of the fertilizer characterized by including.   The said fertilizer production | generation process reuses the residue of the phosphorus collection | recovery material by which the outer surface containing phosphorus was scraped off as a new phosphorus collection | recovery material or earthwork material, The manufacture of the fertilizer of Claim 5 characterized by the above-mentioned. Method.

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