Title of Invention	TREATMENT AGENT AND PROCESS FOR PRODUCTION THEREOF, AND TREATMENT METHOD
Abstract	The present invention provides a treatment agent and a treatment method capable of simply and efficiently removing fluorine in an effluent. The treatment agent includes calcium hydrogen phosphate dihydrate (A) ; and particles (B), wherein the particles (B) carry the calcium hydrogen phosphate dihydrate (A). The present invention also relates to a treatment method including allowing the treatment agent according to make contact with a fluorine-containing water to be treated, to thereby remove the fluorine from the water to be treated. The present invention further relates to a treatment method including mixing the treatment agent with a fluorine-containing soil, to thereby insolubilize the fluorine in the soil.

Title of Invention

TREATMENT AGENT AND PROCESS FOR PRODUCTION THEREOF, AND TREATMENT METHOD

Abstract

The present invention provides a treatment agent and a treatment method capable of simply and efficiently removing fluorine in an effluent. The treatment agent includes calcium hydrogen phosphate dihydrate (A) ; and particles (B), wherein the particles (B) carry the calcium hydrogen phosphate dihydrate (A). The present invention also relates to a treatment method including allowing the treatment agent according to make contact with a fluorine-containing water to be treated, to thereby remove the fluorine from the water to be treated. The present invention further relates to a treatment method including mixing the treatment agent with a fluorine-containing soil, to thereby insolubilize the fluorine in the soil.

Full Text	DESCRIPTION TREATMENT AGENT AND PROCESS FOR PRODUCTION THEREOF, AND TREATMENT METHOD TECHNICAL FIELD [0001] The present invention relates to a treatment agent, a method of producing the treatment agent, and a treatment method. BACKGROUND ART [0002] Fluorine is contained in effluents discharged in the processes of aluminum electrolytic refining, phosphorus fertilizer production, pickling of metal such as stainless steel, and washing of electric parts such as silicone; fume cleaning effluent from garbage incinerators; effluent of coal-fired flue gas desulfurization; or the like. Meanwhile, effluent standards have been implemented, and disposal treatment has been performed to meet the standards. [0003] The methods of disposing fluorine generally practiced at present are as follows: A method including adding a calcium salt to generate calcium fluoride (CaF2) , which is poorly soluble, and precipitating and separating the calcium fluoride; a method including adding an aluminum salt so that fluorine coprecipitates with aluminum hydroxide (A1(OH)3), and separating the fluorine; or a combination method of the coagulation and precipitation with a calcium salt and the coagulation and precipitation with an aluminum salt (see, for example, Non-Patent Document 1). [0004] Due to the stricter effluent standard and environmental standard for fluorine these days, a fluorine-containing effluent needs to be highly disposed. However, the conventional coagulation and precipitation with a calcium salt can very hardly achieve the effluent standard for fluorine of 8 mg/L or less. [0005] In the method of coprecipitation with aluminum hydroxide, a technique of adding aluminum sulfate (Al2 (SO4) 316H2O) as a coagulation agent is known (see, for example, Patent Document 1). However, this conventional technique requires separation of the treated water and sludge formed of the coprecipitate in an amount of not less than the added aluminum sulfate, and further requires cumbersome treatment processes such as treatment of the separated sludge to avoid elution of fluorine therefrom and then burying the treated sludge in the ground. [0006] In order to solve the problems involved in the conventional art, a method is disclosed which includes use of a poorly soluble phosphoric acid salt, as a fluorine treatment agent capable of achieving the effluent standard, to fix and remove fluorine in an effluent as fluoroapatite (see, Patent Documents 2 and 3). [0007] Patent Document 2 discloses that addition of only a phosphoric acid salt and/or a phosphoric acid compound can reduce the fluorine concentration in an effluent to 0.S mg/L or less. [0008] In general, however, the method of treating a fluorine-containing effluent with a phosphoric acid salt and/or a phosphoric acid compound is characterized in that fluorine and the phosphoric acid salt and/or phosphoric acid compound form a complex salt at a ratio determined by the chemical compositions thereof, and the method can remove a stoichiometric amount of fluorine at maximum. For this purpose, the phosphoric acid salt and/or phosphoric acid compound need to be used in a fine powder form. [0009] A method in which a dispersive contactor is used may be listed as one example of the treatment process for allowing the finely-powdered phosphoric acid salt and/or phosphoric acid compound to contact with the fluorine-containing effluent include (see, for example, Patent Documents 4 and 5). [0010] As a simpler treatment method, a process is normally employed in which a fluorine-containing effluent is flown through a packed bed densely filled with the finely-powdered phosphoric acid salt and/or phosphoric acid compound so as to remove fluorine. [0011] Meanwhile, as a technique for suppressing elution of fluorine, an agent which is produced by suspending powdered calcium hydrogen phosphate dihydrate in water so that the surface of the powder is activated is disclosed (see, for example, Patent Document 6) as a treatment agent for insolubilizing fluorine in fluorine-contaminated soil. Moreover, as a method of treating gypsum for suppressing elution of the contained fluorine, a method is disclosed which includes aging a fluorine-containing gypsum for a predetermined period in water in the presence of calcium hydrogen phosphate dihydrate in an amount of 1 to 5 parts by mass for 100 parts by mass of calcium sulfate dihydrate in the gypsum, and collecting the gypsum (see, for example, Patent Document 7). [Patent Document] [0012] Patent Document 1: JP-A 2005-324137 Patent Document 2: JP-B 3504248 Patent Document 3: JP-A 2004-358309 Patent Document 4: JP-A 2004-122113 Patent Document 5: JP-A 2006-305555 Patent Document 6: JP-A 2007-216156 Patent Document 7: JP-A 2008-297172 [Non-Patent Document] [0013] NON-PATENT DOCUMENT 1: Hiroyuki ASADA, Yoshihiro ETOH "Fusso to Houso no Shori-gijyutsu," Journal of Environmental Conservation Engineering, 2000, vol. 29, No.A, p.283-289 SUMMARY OF INVENTION [0014] The method of dispersing a finely-powdered phosphoric acid salt and/or a phosphoric acid compound in a contactor, as disclosed in Patent Documents 4 and 5, is characterized by reacting the phosphoric acid salt and/or phosphoric acid compound with fluorine so that elution of those substances is suppressed. However, the phosphoric acid salt and/or phosphoric acid compound need to be powdered as finely as possible in order to fix the fluorine at the stoichiometric ratio to the phosphoric acid salt and/or phosphoric acid compound. Such fine powders may problematically reduce the treatment speed. [0015] Moreover, as described earlier, the method of removing fluorine by allowing a fluorine-containing effluent to flow through a packed bed densely filled with the finely-powdered phosphoric acid salt and/or phosphoric acid compound has the following problems. Namely, since finer powdering of the phosphoric acid salt and/or phosphoric acid compound leads to not only worse permeability of the packed bed but also higher pressure loss, the packed bed needs to be pressure-resistant. Also, the finely-powdered phosphoric acid salt and/or phosphoric acid compound are suspended in water, and are thus hardly separable from water. [0016] In contrast, in the case where the packed pad used is filled with the phosphoric acid salt and/or phosphoric acid compound granulated in a manner to have a larger grain size so that the permeability of the packed pad is increased, the phosphoric acid salt and/or phosphoric acid compound react with fluorine on the surfaces of the grain. Problematically the amount of the fluorine to be removed per unit weight of the phosphoric acid salt and/or phosphoric acid compound decreases. [0017] The present invention aims to solve the foregoing problems involved in the conventional techniques and to provide a treatment agent and a treatment method which can simply and effectively remove fluorine in an effluent. MEANS FOR SOLVING THE PROBLEMS [0018] The present invention relates to a treatment agent including: calcium hydrogen phosphate dihydrate (A) ; and particles (B) , wherein the particles (B) carry the calcium hydrogen phosphate dihydrate (A). [0019] The present invention also relates to a method of producing the treatment agent, including mixing the calcium hydrogen phosphate dihydrate (A) and the particles (B) with a tilting gravity mixer. [0020] The present invention further relates to a treatment method including allowing the treatment agent to make contact with a fluorine-containing water to be treated, to thereby remove the fluorine from the water to be treated. [0021] The present invention further relates to a treatment method including mixing the treatment agent with a fluorine-containing soil, to thereby insolubilize the fluorine in the soil. The following describes the present invention in more detail. [0022] The present invention relates to a treatment agent containing calcium hydrogen phosphate dihydrate (A) and particles (B) (provided that particles of calcium hydrogen phosphate dihydrate (A) are excluded) . Since the particles (B) carry the calcium hydrogen phosphate dihydrate (A) , the flowing of a fluorine-containing water to be treated through the treatment agent of the present invention can substantially prevent the powdered calcium hydrogen phosphate dihydrate (A) from eluting off for a long period of time. Also, excellent permeability can be kept for a long period of time, and is further possible to maintain the fluorine concentration of the water to be treated at 0.8 mg/L or less for a long period of time. The "carry" used herein refers to a state where the particles (B) as a carrier support the calcium hydrogen phosphate dihydrate (A) in a manner that the particles hold the calcium hydrogen phosphate dihydrate (A). [0023] The treatment agent of the present invention can be obtained by mixing the powdered calcium hydrogen phosphate dihydrate (A) with the particles (B) . Since the particles (B) carry the calcium hydrogen phosphate dihydrate (A), the particle diameter is large. For this reason, the treatment agent of the present invention tends not to form lumps (coagulation) and exhibits excellent permeability. Moreover, since the particles (B) carry the calcium hydrogen phosphate dihydrate (A) , the treatment agent of the present invention is not easily scattered, and thus exhibits excellent handleability. Further, since the calcium hydrogen phosphate dihydrate (A) itself keeps the particle diameter small (fine powder state), a sufficient amount of fluorine can be removed. [0024] The treatment agent of the present invention contains the calcium hydrogen phosphate dihydrate (A). Therefore, when the treatment agent is allowed to contact with water and the like, fluorine in the water and the like can be removed. Moreover, mixing the treatment agent with fluorine-contaminated soil can insolubilize fluorine in the fluorine-contained soil as fluorine apatite so that the fluorine in the soil can be prevented from eluting. The calcium hydrogen phosphate dihydrate (A) has an excellent effect especially in insolubilizing the fluorine in the fluorine-contaminated soil as fluorine apatite. For example, although calcium phosphate (Ca3(PO4)2) has an effect of insolubilizing fluorine in fluorine-contaminated soil, the effect is inferior to that of the calcium hydrogen phosphate dihydrate (A). [0025] Fluorine apatite itself is a main component of natural phosphate rocks. The treatment agent of the present invention does not contain other organic substances, heavy metals, or the like. Therefore, the treatment agent can reduce the elution amount of fluorine from fluorine-contaminated soil to 0.8 mg/L or less in a simple, cost-effective, and assured manner without causing any secondary environmental pollution. [0026] In the treatment agent, the amount of the calcium hydrogen phosphate dihydrate (A) is preferably 1 to 100 parts by mass for 100 parts by mass of the particles (B). If the amount is set in this range, the particles (B) can efficiently carry the calcium hydrogen phosphate dihydrate (A) . As a result, the treatment agent has improved permeability with an excellent capability of removing fluorine. The amount of the calcium hydrogen phosphate dihydrate (A) is more preferably 5 to 50 parts by mass and further preferably 7 to 15 parts by mass for 100 parts by mass of the particle (B). [0027] The calcium hydrogen phosphate dihydrate (A) is preferably in a powder form, and more preferably has an average particle diameter of 30 to 70 µm. If the average particle diameter is in the above range, the particles (B) efficiently carry the calcium hydrogen phosphate dihydrate (A), and thus the treatment agent has an excellent fluorine-removing ability. [0028] The average particle diameter of the calcium hydrogen phosphate dihydrate (A) was measured with a Microtrack 9320HRA (product of Nikkiso Co., Ltd.) according to a laser diffraction-scattering method. [0029] The particle surface of the calcium hydrogen phosphate dihydrate (A) may be activated, which is one of the preferable embodiments. The fluorine-insolubilizing action is further enhanced when the particle surface is activated by suspending the powders of the calcium hydrogen phosphate dihydrate in water. [0030] After suspending the powder particles of the calcium hydrogen phosphate dihydrate (A) in water, followed by stirring or shaking, the resulting particles collected from the suspension have, on the surfaces, a large number of uniformly-deposited fine crystals having a size of approximately several tens nm. The surfaces of such particles are activated, and thereby, for example, fluorine in fluorine-contaminated soil can be more efficiently insolubilized. For this reason, the particle surface of the calcium hydrogen phosphate dihydrate (A) to be contained in the treatment agent of the present invention is preferably activated by suspending the powder particles of the calcium hydrogen phosphate dihydrate (A) in water. [0031] The particles (B) are particles capable of carrying the calcium hydrogen phosphate dihydrate (A). If the particles (B) carry the calcium hydrogen phosphate dihydrate (A), the treatment agent excellent in permeability and fluorine-removing action can be obtained. [0032] Examples of the particles (B) include filter sand and filter gravel generally used for purifying water, but are not limited thereto. Sand is also preferably used as the particles (B) . [0033] Preferably, the particles (B) substantially have a particle diameter of 0.3 to 3.0 mm. More preferably, the particles (B) consist only of particles substantially having a particle diameter of 0.3 to 3.0 mm. In the particles (B) , preferably 90% by mass or more, more preferably 99% by mass or more, and further preferably 99. 9% by mass or more of the total particles have a particle diameter of 0.3 to 3.0 mm. The particles (B) especially preferably do not include particles having a particle diameter of less than 0.3 mm and particles having a particle diameter of more than 3.0 mm. The particles (B) having a particle diameter within the above range can efficiently carry the calcium hydrogen phosphate dihydrate (A) , resulting in the treatment agent with excellent permeability and excellent action of removing fluorine-containing compounds. The particles (B) most preferably do not substantially include particles having a particle diameter of more than 2.8 mm. [0034] The particle diameter of the particles (B) is determined by a manual sieving test with a standard wire sieve (JIS Z8801, nominal dimension: 0.3 to 3.0 mm, sieve size: 200, depth: 45 mm) . In the case of avoiding particles having a particle diameter of more than 2.8 mm, a sieve having a nominal dimension of 2.8 mm is used. [0035] The particles (B) preferably have a uniformity coefficient of 1.5 or less. The particles (B) having a uniformity coefficient in the above range can efficiently carry the calcium hydrogen phosphate dihydrate (A) , resulting in the treatment agent having better permeability and excellent action of removing the fluorine-containing compounds. The uniformity coefficient of the particles (B) is measured according to JWWA A103-l:2004. [0036] The treatment agent of the present invention may contain, if desired, a component other than the calcium hydrogen phosphate dihydrate (A) and the particles (B) within the range not adversely affecting the purpose of the present invention. However, the total amount of the calcium hydrogen phosphate dihydrate (A) and the particle (B) is preferably 99% by mass or more in the treatment agent of the present invention. [0037] The treatment agent of the present invention is preferably a treatment agent for a fluorine-containing water or preferably a treatment agent for a fluorine-containing soil. [0038] The present invention also relates to a method of producing the treatment agent, including mixing the calcium hydrogen phosphate dihydrate (A) and the particles (B) with a tilting gravity mixer. [0039] The tilting gravity mixer is not particularly limited, as long as the mixer is so-called a tilting gravity mixer having a structure in which a mixing container for mixing the calcium hydrogen phosphate dihydrate (A) and the particles (B) is attached to a tilting mechanism. The tilting mechanism is a mechanism to tilt the mixing container. [0040] One example of the configuration of the tilting gravity mixer is a mixer including: a frustroconical-shaped container, with one of its end opened and the other end closed, which is attached as a mixing container to a tilting mechanism; and mixing blades attached to the inner wall of the mixing container, or the like may be exemplified. The mixing container is preferably rotatable. [0041] Upon mixing the calcium hydrogen phosphate dihydrate (A) and the particles (B), normally the following operations are performed: The tilting gravity mixer is operated so that an opening month of the drum faces upward; while the mixing container is rotated on a certain direction, the calcium hydrogen phosphate dihydrate (A) and the particles (B) are introduced thereinto; the introduced materials are lifted by a blade and are dropped off, and are mixed by repetition of the operation. Mixing with the tilting gravity mixer is promoted depending on the behavior of the introduced materials. Therefore, the mixing can be performed while favorably keeping the state of the calcium hydrogen phosphate dihydrate (A) being carried by the particles (B). In this manner, the tilting gravity mixer has an excellent effect on production of the treatment agent. [0042] A preferable method of producing the treatment agent includes introducing the calcium hydrogen phosphate dihydrate (A) and the particles (B) in the mixing container of the tilting gravity mixer, adding water depending on the need, and mixing the materials. [0043] The present invention further relates to a treatment method including allowing the treatment agent to make contact with fluorine-containing water to be treated so as to remove the fluorine in the water to be treated (hereinafter, also referred to as "fluorine-removing treatment method"). [0044] The contact between the water to be treated and the treatment agent may be a batch-type contact of adding the treatment agent to the water to be treated, or may be a continuous-type contact of flowing the water to be treated through a column filled with the treatment agent. Moreover, the treatment may include several times of the batch-type contact, or several times of the continuous-type contact, or a combination of the batch-type contact and the continuous-type contact. The filling column used in the continuous-type contact may be of any type among a moving-bed type, fixed-bed type, and fluidized-bed type. [0045] The fluorine-removing treatment method of the present invention may include a step of collecting a treated water having a fluorine concentration of 0.8 mg/L or less. Since the treatment agent is excellent in permeability and reaction efficiency, it can remove fluorine in the water to be treated efficiently enough to reduce the fluorine concentration to 0 . 8 mg/L or less in the water. In the treatment agent, the calcium hydrogen phosphate dihydrate (A) is carried by the particles (B) having a relatively large particle diameter. For this reason, the water to be treated can be prevented from suspending, and thus the treatment agent and the treated water can be easily separated. [0046] The amount of fluorine in the water to be treated is not particularly limited. The treatment agent can exert excellent fluorine-removing ability even if the fluorine concentration is high or low; for example, the fluorine concentration is preferably 0.1 mg/L or more. In order to exert a greater effect of the present invention, the water to be treated having a fluorine concentration of more than 0 . 8 mg/L is more preferable. [0047] In the present invention, the fluorine ion concentration in the fluorine-containing water can be measured by a method in accordance with JIS K0102. [0048] The water to be treated to which the treatment agent is to contact is not particularly limited as long as the water contains fluorine (fluorine-containing water), and examples thereof include industrial effluent, spring water, and river water. Examples of the industrial effluent include fluorine-containing effluent discharged from silicon wafer plants, semiconductor plants, or the like, acid-cleaning effluent discharged from metal plants, effluent resulting from aluminium surface treatment, effluent resulting from hydrofluoric acid production, fertilizer production effluent, and garbage incineration effluent. [0049] The water to be treated preferably has a pH of 3 or higher in the point that high fluorine ion-removing efficiency is achievable with the pH value. Therefore, the treated water obtained by the fluorine-removing treatment method of the present invention (hereinafter, also simply referred to as "treated water") also preferably has a pH of 3 or higher. Both of the pH values are more preferably 4 or higher. In the case that the pH value of the water to be treated or the treated water is lower than 3, or the pH value reaches less than 3 in the steps, the pH value may be adjusted to 3 or higher with sodium hydroxide, calcium hydroxide, or the like. [0050] The water to be treated and the treated water preferably have a pH of 11 or lower. A pH value higher than 11 may hinder progress of reaction between the calcium hydrogen phosphate dihydrate (A) and fluorine ion. In the case that the fluorine-containing water or the treated water has a pH higher than 11, or the pH exceeds 11 in the steps, the pH value may be adjusted to 11 or less with hydrochloric acid, or the like. [0051] The fluorine-removing treatment method mentioned earlier can achieve the fluorine-removing amount for 1 g of the calcium hydrogen phosphate dihydrate (A) of 1 mg-F/g or more, and more preferably 10 mg-F/g or more. [0052] The fluorine-removing treatment method of the present invention may include a step of adding calcium ion to the water to be treated to generate calcium fluoride (CaF2) , and a step of removing the generated calcium fluoride to collect the water to be treated with reduced fluorine ion concentration. These steps are preferably performed before the step of allowing the treatment agent to make contact with the fluorine-containing water to be treated to remove the fluorine in the water to be treated. Since relatively cost-effective calcium compounds are used in the steps, the cost can be reduced especially if the fluorine ion concentration is high in the water to be treated. The calcium ion is preferably added as a calcium compound such as calcium hydroxide (Ca(OH)2), calcium carbonate (CaCO3) , and calcium chloride (CaCl2) [0053] Fluorine is sufficiently removed from the treated water. Accordingly, the treated water has a low fluorine concentration (for example, 0 . 8 mg/L or less) , and thereby meets environmental standards. [0054] The present invention further relates to a treatment method including mixing the treatment agent and a fluorine-containing soil so that the fluorine in the soil is insolubilized (hereafter, referred also to as "fluorine insolubilizing treatment method"). Upon mixing the treatment agent and the fluorine-containing soil, the calcium hydrogen phosphate dihydrate (A) reacts with soluble fluorine ion in the soil to form an insoluble fluoroapatite described as Ca10(PO4)6F2. In the case that the calcium hydrogen phosphate dihydrate (A) alone is mixed with the fluorine-containing soil, the calcium hydrogen phosphate forms agglomerates (coagulations) , which hinders sufficient dispersion. Meanwhile, since the particles (B) carry the calcium hydrogen phosphate in the treatment agent of the present invention, the treatment agent is excellent in dispersibility and can be efficiently mixed with the fluorine-containing soil. [0055] The fluorine-insolubilizing treatment method preferably includes, for example, a step of mixing the calcium hydrogen phosphate dihydrate (A) and the particles (B) to produce the treatment agent, a step of adding the treatment agent to a fluorine-containing soil, and a step of mixing the added treatment agent and the fluorine-containing soil. [0056] The production method of the treatment agent by mixing the calcium hydrogen phosphate dihydrate (A) and the particles (B) is not particularly limited, and may include, for example, a method using the tilting gravity mixer, or the like. [0057] The fluorine elution amount from the fluorine-containing soil is not particularly limited, and may be, for example, 0.1 mg/L or more, and may further be 0.8 mg/L or more. [0058] The soil may be preferably, for example, earth or sludge. [0059] The earth is not particularly limited as long as it is one generally called earth. Any of sandy soil, sandy loam, loam, clay loam, clay soil, and the like can be used. Other examples of the earth include earth prepared by appropriately mixing and adjusting ground aqueous rocks, ground pumice rocks, volcanic ash soils, and the like. Moreover, earth used as a soil for horticulture and the like may be used as well. [0060] Examples of the sludge include a solid formed by coagulation of organic final products which have been generated in the process of sewage disposal treatment or in the process of industrial effluent treatment. The solid is also called a sludge. Other examples of the sludge include an activated sludge, that is an agglomeration of microorganisms resulting from water treatment with microbial community such as aerobic bacteria. EFFECTS OF THE INVENTION [0061] Since the treatment agent of the present invention has the aforementioned structure, it can simply and cost-efficiently produce a treated water in which fluorine has been sufficiently removed, and also can treat a soil in a manner that the fluorine elution amount of the treated soil is 0.8 mg/L or less of the soil environmental standards. BRIEF DESCRIPITON OF THE DRAWINGS [0062] Fig. 1 is a schematic diagram showing the filtration apparatus in Example 1. Fig. 2 is a schematic diagram showing the filtration apparatus in Comparative Example 1. MODES FOR CARRYING OUT THE INVENTION [0063] The present invention will be described in more detail with reference to examples; however, the present invention is not limited to the examples. [0064] (Example 1) A tilting gravity mixer (capacity: 110 L) was charged with rapid filtration sand (product of Tohkemy Corporation, standardized by "Japan Water Works Association Standard, JWWA A103-l:2004 standardized product, effective diameter: 0.6 mm, uniformity coefficient: at most 1.5, maximum diameter: at most 2.8 mm, minimum diameter: at least 0.3 mm"), and calcium hydrogen phosphate dihydrate powder (product of Taihei Chemical Industrial Co., Ltd., "average particle diameter: 54 µm" (hereinafter, referred to as DCPD) ) , at a mass ratio of 90 parts by mass of the rapid filtration sand and 10 parts by mass of the DCPD for 100 parts by mass in total, followed by mixing for three minutes. [0065] Fig. 1 is a schematic diagram showing the filtration apparatus in Example 1. As shown in Fig. 1, a mixture 2 of the rapid filtration sand and the DCPD obtained by the foregoing mixture and a glass wool 3 were charged in a glass column casing 1 (10 cm) so that a filtration apparatus 5 was prepared. Next, a fluorine-containing water to be treated was poured at a flow rate of 50 ml/min into a tube 6 that was communicated with an upper portion of the filtration apparatus 5, and thereby a treated water was obtained from a tube 7 connected to a lower portion of the apparatus. As shown in Fig. 1, the fluorine-containing water to be treated 4 is treated by permeation through the mixture 2 in the column casing 1. In this Example, the permeability of the mixture 2 was evaluated based on changes in the water level of a water surface 8. Table 1 shows the flow rate, fluorine concentration, and water level of the water to be treated, and the flow rate and fluorine concentration of the treated water. The fluorine concentration of the fluorine-containing water and the treated water was measured by a method according to JIS K0102. [0066] [Table 1] The fluorine concentration of the treated water was maintained below the environmental standards after 120 days from the beginning of permeation. The water level did not change 120 days after the beginning of permeation. That is, the permeability did not change. [0068] (Example 2) A tilting gravity mixer (capacity: 110 L) was charged with ordinary sand for mortar, concrete, and the like (effective diameter: 0.1 to 5 mm, maximum diameter: more than 3.0 mm, at most 5.0 mm) used for civil engineering and construction purposes, and DCPD, at a mass ratio of 90 parts by mass of the sand and 10 parts by mass of the DCPD for 100 parts by mass in total, followed by mixing for three minutes. [0069] In the same manner as in Example 1, the following steps were performed: charging the resulting mixture into a glass column casing, preparing a filtration apparatus, pouring a fluorine-containing water to be treated from the upper portion of the filtration apparatus, evaluating the permeability, and measuring the fluorine concentration. Table 2 shows the result. [0070] [Table 2] Comparison between the result of Example 1 and that of Example 2 shows that superior permeability is achieved in the case where the DCPD is carried by the rapid filtration sand to the case where the DCPD is carried by the ordinary sand. The results reveal that the diameter of the particles (B) functioning as a carrier is a key factor for improving the permeability. Moreover, an attention should be paid on the fact that the rapid filtration sand contains a larger amount of water than the ordinary sand. However, in the inventors' experiments, when ordinary sand which had been soaked in pure water was mixed with the DCPD, partial coagulations of the DCPD were observed. [0072] (Comparative Example 1) An experiment was performed in the same manner as in Example 1, except that DCPD alone was used instead of the mixture of the rapid filtration sand and the DCPD. As shown in Fig. 2, DCPD 9 and the glass wool 3 were charged in the glass column casing 1 ( 10 cm) so that a filtration apparatus 5a was prepared. The DCPD was the same as that used in Example 1. Next, a fluorine-containing water to be treated was poured at a flow rate of 50 ml/min from a tube 6 communicated with an upper portion of the apparatus, and shortly after the pouring, the water surface 8 of the fluorine-containing water to be treated elevated to the upper surface of the apparatus. Thus, a treated water was not obtained. Table 3 shows the flow rate, fluorine concentration, and water level of the water to be treated, and the flow rate and fluorine concentration of the treated water. As the treated water was not obtained, the fluorine concentration of the treated water was not measured. [0073] [Table 3] (Comparative Example 2) A tilting gravity mixer (capacity: 110 L) was charged with glass and resin beads (effective diameter: 2 to 4 mm) generally used for handicraft and decoration, and DCPD, at a mass ratio of 90 parts by mass of the beads and 10 parts by mass of the DCPD for 100 parts by mass in total, followed by mixing for three minutes. [0075] A glass column casing was filled with the resulting mixture in the same manner as in Example 1 so that a filtration apparatus was prepared. Upon pouring a fluorine-containing water to be treated from an upper portion of the filtration apparatus, beads began floating, and the treated water in the upper portion of the filtration apparatus became cloudy. The permeability was evaluated, and the fluorine concentration was measured in the same manner as in Example 1. Table 4 shows the results. The results reveal that the DCPD is not sufficiently carried by the beads. [0076] [Table 4] INDUSTRIAL APPLICABILITY [0077] The treatment agent of the present invention has the structure mentioned earlier, and thus can be preferably used in the fields where fluorine-containing water or fluorine-containing soil is generated, such as electroplating industry, semiconductor producing industry, electronic valve producing industry, and glass industry. EXPLANATION OF SYMBOLS [0078] 1: Glass column casing 2: Mixture of rapid filtration sand and DCPD 3: Glass wool 4: Fluorine-containing water to be treated 5, 5a: Filtration apparatus 6, 7: Tube 8: Water surface 9: DCPD WE CLAIM 1. A treatment agent comprising: calcium hydrogen phosphate dihydrate (A); and particles (B), wherein the particles (B) carry the calcium hydrogen phosphate dihydrate (A). 2. The treatment agent according to claim 1, wherein the particles (B) are substantially particles having a particle diameter of 0.3 to 3.0 mm. 3. The treatment agent according to claim 1 or 2, wherein the particles (B) have a uniformity coefficient of 1.5 or less. 4. The treatment agent according to claim 1, 2, or 3, wherein the calcium hydrogen phosphate dihydrate (A) has an average particle diameter of 30 to 70 µm. 5. A method of producing the treatment agent according to claim 1, 2, 3, or 4, comprising mixing calcium hydrogen phosphate dihydrate (A) and particles (B) with a tilting gravity mixer. 6. A treatment method comprising allowing the treatment agent according to claim 1, 2, 3, or 4 to make contact with a fluorine-containing water to be treated, to thereby remove the fluorine from the water to be treated. 7. A treatment method comprising mixing the treatment agent according to claim 1, 2, 3, or 4 with a fluorine-containing soil, to thereby insolubilize the fluorine in the soil. 8. The treatment method according to claim 7, wherein the soil is earth or sludge. The present invention provides a treatment agent and a treatment method capable of simply and efficiently removing fluorine in an effluent. The treatment agent includes calcium hydrogen phosphate dihydrate (A) ; and particles (B), wherein the particles (B) carry the calcium hydrogen phosphate dihydrate (A). The present invention also relates to a treatment method including allowing the treatment agent according to make contact with a fluorine-containing water to be treated, to thereby remove the fluorine from the water to be treated. The present invention further relates to a treatment method including mixing the treatment agent with a fluorine-containing soil, to thereby insolubilize the fluorine in the soil.

Full Text

DESCRIPTION
TREATMENT AGENT AND PROCESS FOR PRODUCTION THEREOF, AND
TREATMENT METHOD
TECHNICAL FIELD
[0001]
The present invention relates to a treatment agent, a
method of producing the treatment agent, and a treatment method.
BACKGROUND ART
[0002]
Fluorine is contained in effluents discharged in the
processes of aluminum electrolytic refining, phosphorus
fertilizer production, pickling of metal such as stainless
steel, and washing of electric parts such as silicone; fume
cleaning effluent from garbage incinerators; effluent of
coal-fired flue gas desulfurization; or the like. Meanwhile,
effluent standards have been implemented, and disposal
treatment has been performed to meet the standards.
[0003]
The methods of disposing fluorine generally practiced at
present are as follows: A method including adding a calcium salt
to generate calcium fluoride (CaF2) , which is poorly soluble,
and precipitating and separating the calcium fluoride; a method
including adding an aluminum salt so that fluorine
coprecipitates with aluminum hydroxide (A1(OH)3), and
separating the fluorine; or a combination method of the
coagulation and precipitation with a calcium salt and the
coagulation and precipitation with an aluminum salt (see, for
example, Non-Patent Document 1).
[0004]
Due to the stricter effluent standard and environmental
standard for fluorine these days, a fluorine-containing
effluent needs to be highly disposed. However, the

conventional coagulation and precipitation with a calcium salt
can very hardly achieve the effluent standard for fluorine of
8 mg/L or less.
[0005]
In the method of coprecipitation with aluminum hydroxide,
a technique of adding aluminum sulfate (Al2 (SO4) 316H2O) as a
coagulation agent is known (see, for example, Patent Document
1). However, this conventional technique requires separation
of the treated water and sludge formed of the coprecipitate in
an amount of not less than the added aluminum sulfate, and
further requires cumbersome treatment processes such as
treatment of the separated sludge to avoid elution of fluorine
therefrom and then burying the treated sludge in the ground.
[0006]
In order to solve the problems involved in the
conventional art, a method is disclosed which includes use of
a poorly soluble phosphoric acid salt, as a fluorine treatment
agent capable of achieving the effluent standard, to fix and
remove fluorine in an effluent as fluoroapatite (see, Patent
Documents 2 and 3).
[0007]
Patent Document 2 discloses that addition of only a
phosphoric acid salt and/or a phosphoric acid compound can
reduce the fluorine concentration in an effluent to 0.S mg/L
or less.
[0008]
In general, however, the method of treating a
fluorine-containing effluent with a phosphoric acid salt and/or
a phosphoric acid compound is characterized in that fluorine
and the phosphoric acid salt and/or phosphoric acid compound
form a complex salt at a ratio determined by the chemical
compositions thereof, and the method can remove a
stoichiometric amount of fluorine at maximum. For this purpose,
the phosphoric acid salt and/or phosphoric acid compound need
to be used in a fine powder form.

[0009]
A method in which a dispersive contactor is used may be
listed as one example of the treatment process for allowing the
finely-powdered phosphoric acid salt and/or phosphoric acid
compound to contact with the fluorine-containing effluent
include (see, for example, Patent Documents 4 and 5).
[0010]
As a simpler treatment method, a process is normally
employed in which a fluorine-containing effluent is flown
through a packed bed densely filled with the finely-powdered
phosphoric acid salt and/or phosphoric acid compound so as to
remove fluorine.
[0011]
Meanwhile, as a technique for suppressing elution of
fluorine, an agent which is produced by suspending powdered
calcium hydrogen phosphate dihydrate in water so that the
surface of the powder is activated is disclosed (see, for
example, Patent Document 6) as a treatment agent for
insolubilizing fluorine in fluorine-contaminated soil.
Moreover, as a method of treating gypsum for suppressing elution
of the contained fluorine, a method is disclosed which includes
aging a fluorine-containing gypsum for a predetermined period
in water in the presence of calcium hydrogen phosphate dihydrate
in an amount of 1 to 5 parts by mass for 100 parts by mass of
calcium sulfate dihydrate in the gypsum, and collecting the
gypsum (see, for example, Patent Document 7).
[Patent Document]
[0012]
Patent Document 1: JP-A 2005-324137
Patent Document 2: JP-B 3504248
Patent Document 3: JP-A 2004-358309
Patent Document 4: JP-A 2004-122113
Patent Document 5: JP-A 2006-305555
Patent Document 6: JP-A 2007-216156
Patent Document 7: JP-A 2008-297172

[Non-Patent Document]
[0013]
NON-PATENT DOCUMENT 1: Hiroyuki ASADA, Yoshihiro ETOH
"Fusso to Houso no Shori-gijyutsu," Journal of Environmental
Conservation Engineering, 2000, vol. 29, No.A, p.283-289
SUMMARY OF INVENTION
[0014]
The method of dispersing a finely-powdered phosphoric
acid salt and/or a phosphoric acid compound in a contactor, as
disclosed in Patent Documents 4 and 5, is characterized by
reacting the phosphoric acid salt and/or phosphoric acid
compound with fluorine so that elution of those substances is
suppressed. However, the phosphoric acid salt and/or
phosphoric acid compound need to be powdered as finely as
possible in order to fix the fluorine at the stoichiometric
ratio to the phosphoric acid salt and/or phosphoric acid
compound. Such fine powders may problematically reduce the
treatment speed.
[0015]
Moreover, as described earlier, the method of removing
fluorine by allowing a fluorine-containing effluent to flow
through a packed bed densely filled with the finely-powdered
phosphoric acid salt and/or phosphoric acid compound has the
following problems. Namely, since finer powdering of the
phosphoric acid salt and/or phosphoric acid compound leads to
not only worse permeability of the packed bed but also higher
pressure loss, the packed bed needs to be pressure-resistant.
Also, the finely-powdered phosphoric acid salt and/or
phosphoric acid compound are suspended in water, and are thus
hardly separable from water.
[0016]
In contrast, in the case where the packed pad used is
filled with the phosphoric acid salt and/or phosphoric acid
compound granulated in a manner to have a larger grain size so

that the permeability of the packed pad is increased, the
phosphoric acid salt and/or phosphoric acid compound react with
fluorine on the surfaces of the grain. Problematically the
amount of the fluorine to be removed per unit weight of the
phosphoric acid salt and/or phosphoric acid compound decreases.
[0017]
The present invention aims to solve the foregoing
problems involved in the conventional techniques and to provide
a treatment agent and a treatment method which can simply and
effectively remove fluorine in an effluent.
MEANS FOR SOLVING THE PROBLEMS
[0018]
The present invention relates to a treatment agent
including: calcium hydrogen phosphate dihydrate (A) ; and
particles (B) , wherein the particles (B) carry the calcium
hydrogen phosphate dihydrate (A).
[0019]
The present invention also relates to a method of
producing the treatment agent, including mixing the calcium
hydrogen phosphate dihydrate (A) and the particles (B) with a
tilting gravity mixer.
[0020]
The present invention further relates to a treatment
method including allowing the treatment agent to make contact
with a fluorine-containing water to be treated, to thereby
remove the fluorine from the water to be treated.
[0021]
The present invention further relates to a treatment
method including mixing the treatment agent with a
fluorine-containing soil, to thereby insolubilize the fluorine
in the soil.
The following describes the present invention in more
detail.
[0022]

The present invention relates to a treatment agent
containing calcium hydrogen phosphate dihydrate (A) and
particles (B) (provided that particles of calcium hydrogen
phosphate dihydrate (A) are excluded) . Since the particles (B)
carry the calcium hydrogen phosphate dihydrate (A) , the flowing
of a fluorine-containing water to be treated through the
treatment agent of the present invention can substantially
prevent the powdered calcium hydrogen phosphate dihydrate (A)
from eluting off for a long period of time. Also, excellent
permeability can be kept for a long period of time, and is further
possible to maintain the fluorine concentration of the water
to be treated at 0.8 mg/L or less for a long period of time.
The "carry" used herein refers to a state where the particles
(B) as a carrier support the calcium hydrogen phosphate
dihydrate (A) in a manner that the particles hold the calcium
hydrogen phosphate dihydrate (A).
[0023]
The treatment agent of the present invention can be
obtained by mixing the powdered calcium hydrogen phosphate
dihydrate (A) with the particles (B) . Since the particles (B)
carry the calcium hydrogen phosphate dihydrate (A), the
particle diameter is large. For this reason, the treatment
agent of the present invention tends not to form lumps
(coagulation) and exhibits excellent permeability. Moreover,
since the particles (B) carry the calcium hydrogen phosphate
dihydrate (A) , the treatment agent of the present invention is
not easily scattered, and thus exhibits excellent handleability.
Further, since the calcium hydrogen phosphate dihydrate (A)
itself keeps the particle diameter small (fine powder state),
a sufficient amount of fluorine can be removed.
[0024]
The treatment agent of the present invention contains the
calcium hydrogen phosphate dihydrate (A). Therefore, when the
treatment agent is allowed to contact with water and the like,
fluorine in the water and the like can be removed. Moreover,

mixing the treatment agent with fluorine-contaminated soil can
insolubilize fluorine in the fluorine-contained soil as
fluorine apatite so that the fluorine in the soil can be
prevented from eluting. The calcium hydrogen phosphate
dihydrate (A) has an excellent effect especially in
insolubilizing the fluorine in the fluorine-contaminated soil
as fluorine apatite. For example, although calcium phosphate
(Ca3(PO4)2) has an effect of insolubilizing fluorine in
fluorine-contaminated soil, the effect is inferior to that of
the calcium hydrogen phosphate dihydrate (A).
[0025]
Fluorine apatite itself is a main component of natural
phosphate rocks. The treatment agent of the present invention
does not contain other organic substances, heavy metals, or the
like. Therefore, the treatment agent can reduce the elution
amount of fluorine from fluorine-contaminated soil to 0.8 mg/L
or less in a simple, cost-effective, and assured manner without
causing any secondary environmental pollution.
[0026]
In the treatment agent, the amount of the calcium hydrogen
phosphate dihydrate (A) is preferably 1 to 100 parts by mass
for 100 parts by mass of the particles (B). If the amount is
set in this range, the particles (B) can efficiently carry the
calcium hydrogen phosphate dihydrate (A) . As a result, the
treatment agent has improved permeability with an excellent
capability of removing fluorine. The amount of the calcium
hydrogen phosphate dihydrate (A) is more preferably 5 to 50
parts by mass and further preferably 7 to 15 parts by mass for
100 parts by mass of the particle (B).
[0027]
The calcium hydrogen phosphate dihydrate (A) is
preferably in a powder form, and more preferably has an average
particle diameter of 30 to 70 µm. If the average particle
diameter is in the above range, the particles (B) efficiently
carry the calcium hydrogen phosphate dihydrate (A), and thus

the treatment agent has an excellent fluorine-removing ability.
[0028]
The average particle diameter of the calcium hydrogen
phosphate dihydrate (A) was measured with a Microtrack 9320HRA
(product of Nikkiso Co., Ltd.) according to a laser
diffraction-scattering method.
[0029]
The particle surface of the calcium hydrogen phosphate
dihydrate (A) may be activated, which is one of the preferable
embodiments. The fluorine-insolubilizing action is further
enhanced when the particle surface is activated by suspending
the powders of the calcium hydrogen phosphate dihydrate in
water.
[0030]
After suspending the powder particles of the calcium
hydrogen phosphate dihydrate (A) in water, followed by stirring
or shaking, the resulting particles collected from the
suspension have, on the surfaces, a large number of
uniformly-deposited fine crystals having a size of
approximately several tens nm. The surfaces of such particles
are activated, and thereby, for example, fluorine in
fluorine-contaminated soil can be more efficiently
insolubilized. For this reason, the particle surface of the
calcium hydrogen phosphate dihydrate (A) to be contained in the
treatment agent of the present invention is preferably
activated by suspending the powder particles of the calcium
hydrogen phosphate dihydrate (A) in water.
[0031]
The particles (B) are particles capable of carrying the
calcium hydrogen phosphate dihydrate (A). If the particles (B)
carry the calcium hydrogen phosphate dihydrate (A), the
treatment agent excellent in permeability and
fluorine-removing action can be obtained.
[0032]
Examples of the particles (B) include filter sand and

filter gravel generally used for purifying water, but are not
limited thereto. Sand is also preferably used as the particles
(B) .
[0033]
Preferably, the particles (B) substantially have a
particle diameter of 0.3 to 3.0 mm. More preferably, the
particles (B) consist only of particles substantially having
a particle diameter of 0.3 to 3.0 mm. In the particles (B) ,
preferably 90% by mass or more, more preferably 99% by mass or
more, and further preferably 99. 9% by mass or more of the total
particles have a particle diameter of 0.3 to 3.0 mm. The
particles (B) especially preferably do not include particles
having a particle diameter of less than 0.3 mm and particles
having a particle diameter of more than 3.0 mm. The particles
(B) having a particle diameter within the above range can
efficiently carry the calcium hydrogen phosphate dihydrate (A) ,
resulting in the treatment agent with excellent permeability
and excellent action of removing fluorine-containing compounds.
The particles (B) most preferably do not substantially include
particles having a particle diameter of more than 2.8 mm.
[0034]
The particle diameter of the particles (B) is determined
by a manual sieving test with a standard wire sieve (JIS Z8801,
nominal dimension: 0.3 to 3.0 mm, sieve size: 200, depth: 45
mm) . In the case of avoiding particles having a particle
diameter of more than 2.8 mm, a sieve having a nominal dimension
of 2.8 mm is used.
[0035]
The particles (B) preferably have a uniformity
coefficient of 1.5 or less. The particles (B) having a
uniformity coefficient in the above range can efficiently carry
the calcium hydrogen phosphate dihydrate (A) , resulting in the
treatment agent having better permeability and excellent action
of removing the fluorine-containing compounds.
The uniformity coefficient of the particles (B) is

measured according to JWWA A103-l:2004.
[0036]
The treatment agent of the present invention may contain,
if desired, a component other than the calcium hydrogen
phosphate dihydrate (A) and the particles (B) within the range
not adversely affecting the purpose of the present invention.
However, the total amount of the calcium hydrogen phosphate
dihydrate (A) and the particle (B) is preferably 99% by mass
or more in the treatment agent of the present invention.
[0037]
The treatment agent of the present invention is
preferably a treatment agent for a fluorine-containing water
or preferably a treatment agent for a fluorine-containing soil.
[0038]
The present invention also relates to a method of
producing the treatment agent, including mixing the calcium
hydrogen phosphate dihydrate (A) and the particles (B) with a
tilting gravity mixer.
[0039]
The tilting gravity mixer is not particularly limited,
as long as the mixer is so-called a tilting gravity mixer having
a structure in which a mixing container for mixing the calcium
hydrogen phosphate dihydrate (A) and the particles (B) is
attached to a tilting mechanism. The tilting mechanism is a
mechanism to tilt the mixing container.
[0040]
One example of the configuration of the tilting gravity
mixer is a mixer including: a frustroconical-shaped container,
with one of its end opened and the other end closed, which is
attached as a mixing container to a tilting mechanism; and
mixing blades attached to the inner wall of the mixing container,
or the like may be exemplified. The mixing container is
preferably rotatable.
[0041]
Upon mixing the calcium hydrogen phosphate dihydrate (A)

and the particles (B), normally the following operations are
performed: The tilting gravity mixer is operated so that an
opening month of the drum faces upward; while the mixing
container is rotated on a certain direction, the calcium
hydrogen phosphate dihydrate (A) and the particles (B) are
introduced thereinto; the introduced materials are lifted by
a blade and are dropped off, and are mixed by repetition of the
operation.
Mixing with the tilting gravity mixer is promoted
depending on the behavior of the introduced materials.
Therefore, the mixing can be performed while favorably keeping
the state of the calcium hydrogen phosphate dihydrate (A) being
carried by the particles (B). In this manner, the tilting
gravity mixer has an excellent effect on production of the
treatment agent.
[0042]
A preferable method of producing the treatment agent
includes introducing the calcium hydrogen phosphate dihydrate
(A) and the particles (B) in the mixing container of the tilting
gravity mixer, adding water depending on the need, and mixing
the materials.
[0043]
The present invention further relates to a treatment
method including allowing the treatment agent to make contact
with fluorine-containing water to be treated so as to remove
the fluorine in the water to be treated (hereinafter, also
referred to as "fluorine-removing treatment method").
[0044]
The contact between the water to be treated and the
treatment agent may be a batch-type contact of adding the
treatment agent to the water to be treated, or may be a
continuous-type contact of flowing the water to be treated
through a column filled with the treatment agent. Moreover,
the treatment may include several times of the batch-type
contact, or several times of the continuous-type contact, or

a combination of the batch-type contact and the continuous-type
contact. The filling column used in the continuous-type
contact may be of any type among a moving-bed type, fixed-bed
type, and fluidized-bed type.
[0045]
The fluorine-removing treatment method of the present
invention may include a step of collecting a treated water
having a fluorine concentration of 0.8 mg/L or less. Since the
treatment agent is excellent in permeability and reaction
efficiency, it can remove fluorine in the water to be treated
efficiently enough to reduce the fluorine concentration to 0 . 8
mg/L or less in the water. In the treatment agent, the calcium
hydrogen phosphate dihydrate (A) is carried by the particles
(B) having a relatively large particle diameter. For this
reason, the water to be treated can be prevented from suspending,
and thus the treatment agent and the treated water can be easily
separated.
[0046]
The amount of fluorine in the water to be treated is not
particularly limited. The treatment agent can exert excellent
fluorine-removing ability even if the fluorine concentration
is high or low; for example, the fluorine concentration is
preferably 0.1 mg/L or more. In order to exert a greater effect
of the present invention, the water to be treated having a
fluorine concentration of more than 0 . 8 mg/L is more preferable.
[0047]
In the present invention, the fluorine ion concentration
in the fluorine-containing water can be measured by a method
in accordance with JIS K0102.
[0048]
The water to be treated to which the treatment agent is
to contact is not particularly limited as long as the water
contains fluorine (fluorine-containing water), and examples
thereof include industrial effluent, spring water, and river
water. Examples of the industrial effluent include

fluorine-containing effluent discharged from silicon wafer
plants, semiconductor plants, or the like, acid-cleaning
effluent discharged from metal plants, effluent resulting from
aluminium surface treatment, effluent resulting from
hydrofluoric acid production, fertilizer production effluent,
and garbage incineration effluent.
[0049]
The water to be treated preferably has a pH of 3 or higher
in the point that high fluorine ion-removing efficiency is
achievable with the pH value. Therefore, the treated water
obtained by the fluorine-removing treatment method of the
present invention (hereinafter, also simply referred to as
"treated water") also preferably has a pH of 3 or higher. Both
of the pH values are more preferably 4 or higher. In the case
that the pH value of the water to be treated or the treated water
is lower than 3, or the pH value reaches less than 3 in the steps,
the pH value may be adjusted to 3 or higher with sodium hydroxide,
calcium hydroxide, or the like.
[0050]
The water to be treated and the treated water preferably
have a pH of 11 or lower. A pH value higher than 11 may hinder
progress of reaction between the calcium hydrogen phosphate
dihydrate (A) and fluorine ion. In the case that the
fluorine-containing water or the treated water has a pH higher
than 11, or the pH exceeds 11 in the steps, the pH value may
be adjusted to 11 or less with hydrochloric acid, or the like.
[0051]
The fluorine-removing treatment method mentioned earlier
can achieve the fluorine-removing amount for 1 g of the calcium
hydrogen phosphate dihydrate (A) of 1 mg-F/g or more, and more
preferably 10 mg-F/g or more.
[0052]
The fluorine-removing treatment method of the present
invention may include a step of adding calcium ion to the water
to be treated to generate calcium fluoride (CaF2) , and a step

of removing the generated calcium fluoride to collect the water
to be treated with reduced fluorine ion concentration. These
steps are preferably performed before the step of allowing the
treatment agent to make contact with the fluorine-containing
water to be treated to remove the fluorine in the water to be
treated. Since relatively cost-effective calcium compounds
are used in the steps, the cost can be reduced especially if
the fluorine ion concentration is high in the water to be treated.
The calcium ion is preferably added as a calcium compound such
as calcium hydroxide (Ca(OH)2), calcium carbonate (CaCO3) , and
calcium chloride (CaCl2)
[0053]
Fluorine is sufficiently removed from the treated water.
Accordingly, the treated water has a low fluorine concentration
(for example, 0 . 8 mg/L or less) , and thereby meets environmental
standards.
[0054]
The present invention further relates to a treatment
method including mixing the treatment agent and a
fluorine-containing soil so that the fluorine in the soil is
insolubilized (hereafter, referred also to as "fluorine
insolubilizing treatment method"). Upon mixing the treatment
agent and the fluorine-containing soil, the calcium hydrogen
phosphate dihydrate (A) reacts with soluble fluorine ion in the
soil to form an insoluble fluoroapatite described as
Ca10(PO4)6F2.
In the case that the calcium hydrogen phosphate dihydrate
(A) alone is mixed with the fluorine-containing soil, the
calcium hydrogen phosphate forms agglomerates (coagulations) ,
which hinders sufficient dispersion. Meanwhile, since the
particles (B) carry the calcium hydrogen phosphate in the
treatment agent of the present invention, the treatment agent
is excellent in dispersibility and can be efficiently mixed with
the fluorine-containing soil.
[0055]

The fluorine-insolubilizing treatment method preferably
includes, for example, a step of mixing the calcium hydrogen
phosphate dihydrate (A) and the particles (B) to produce the
treatment agent, a step of adding the treatment agent to a
fluorine-containing soil, and a step of mixing the added
treatment agent and the fluorine-containing soil.
[0056]
The production method of the treatment agent by mixing
the calcium hydrogen phosphate dihydrate (A) and the particles
(B) is not particularly limited, and may include, for example,
a method using the tilting gravity mixer, or the like.
[0057]
The fluorine elution amount from the fluorine-containing
soil is not particularly limited, and may be, for example, 0.1
mg/L or more, and may further be 0.8 mg/L or more.
[0058]
The soil may be preferably, for example, earth or sludge.
[0059]
The earth is not particularly limited as long as it is
one generally called earth. Any of sandy soil, sandy loam, loam,
clay loam, clay soil, and the like can be used. Other examples
of the earth include earth prepared by appropriately mixing and
adjusting ground aqueous rocks, ground pumice rocks, volcanic
ash soils, and the like. Moreover, earth used as a soil for
horticulture and the like may be used as well.
[0060]
Examples of the sludge include a solid formed by
coagulation of organic final products which have been generated
in the process of sewage disposal treatment or in the process
of industrial effluent treatment. The solid is also called a
sludge. Other examples of the sludge include an activated
sludge, that is an agglomeration of microorganisms resulting
from water treatment with microbial community such as aerobic
bacteria.

EFFECTS OF THE INVENTION
[0061]
Since the treatment agent of the present invention has
the aforementioned structure, it can simply and
cost-efficiently produce a treated water in which fluorine has
been sufficiently removed, and also can treat a soil in a manner
that the fluorine elution amount of the treated soil is 0.8 mg/L
or less of the soil environmental standards.
BRIEF DESCRIPITON OF THE DRAWINGS
[0062]
Fig. 1 is a schematic diagram showing the filtration
apparatus in Example 1.
Fig. 2 is a schematic diagram showing the filtration
apparatus in Comparative Example 1.
MODES FOR CARRYING OUT THE INVENTION
[0063]
The present invention will be described in more detail
with reference to examples; however, the present invention is
not limited to the examples.
[0064]
(Example 1)
A tilting gravity mixer (capacity: 110 L) was charged with
rapid filtration sand (product of Tohkemy Corporation,
standardized by "Japan Water Works Association Standard, JWWA
A103-l:2004 standardized product, effective diameter: 0.6 mm,
uniformity coefficient: at most 1.5, maximum diameter: at most
2.8 mm, minimum diameter: at least 0.3 mm"), and calcium
hydrogen phosphate dihydrate powder (product of Taihei Chemical
Industrial Co., Ltd., "average particle diameter: 54 µm"
(hereinafter, referred to as DCPD) ) , at a mass ratio of 90 parts
by mass of the rapid filtration sand and 10 parts by mass of
the DCPD for 100 parts by mass in total, followed by mixing for
three minutes.

[0065]
Fig. 1 is a schematic diagram showing the filtration
apparatus in Example 1. As shown in Fig. 1, a mixture 2 of the
rapid filtration sand and the DCPD obtained by the foregoing
mixture and a glass wool 3 were charged in a glass column casing
1 (10 cm) so that a filtration apparatus 5 was prepared.
Next, a fluorine-containing water to be treated was
poured at a flow rate of 50 ml/min into a tube 6 that was
communicated with an upper portion of the filtration apparatus
5, and thereby a treated water was obtained from a tube 7
connected to a lower portion of the apparatus. As shown in Fig.
1, the fluorine-containing water to be treated 4 is treated by
permeation through the mixture 2 in the column casing 1. In
this Example, the permeability of the mixture 2 was evaluated
based on changes in the water level of a water surface 8. Table
1 shows the flow rate, fluorine concentration, and water level
of the water to be treated, and the flow rate and fluorine
concentration of the treated water. The fluorine
concentration of the fluorine-containing water and the treated
water was measured by a method according to JIS K0102.
[0066]
[Table 1]

The fluorine concentration of the treated water was
maintained below the environmental standards after 120 days

from the beginning of permeation. The water level did not
change 120 days after the beginning of permeation. That is,
the permeability did not change.
[0068]
(Example 2)
A tilting gravity mixer (capacity: 110 L) was charged with
ordinary sand for mortar, concrete, and the like (effective
diameter: 0.1 to 5 mm, maximum diameter: more than 3.0 mm, at
most 5.0 mm) used for civil engineering and construction
purposes, and DCPD, at a mass ratio of 90 parts by mass of the
sand and 10 parts by mass of the DCPD for 100 parts by mass in
total, followed by mixing for three minutes.
[0069]
In the same manner as in Example 1, the following steps
were performed: charging the resulting mixture into a glass
column casing, preparing a filtration apparatus, pouring a
fluorine-containing water to be treated from the upper portion
of the filtration apparatus, evaluating the permeability, and
measuring the fluorine concentration. Table 2 shows the
result.
[0070]
[Table 2]

Comparison between the result of Example 1 and that of
Example 2 shows that superior permeability is achieved in the
case where the DCPD is carried by the rapid filtration sand to
the case where the DCPD is carried by the ordinary sand. The
results reveal that the diameter of the particles (B)
functioning as a carrier is a key factor for improving the
permeability. Moreover, an attention should be paid on the fact

that the rapid filtration sand contains a larger amount of water
than the ordinary sand. However, in the inventors' experiments,
when ordinary sand which had been soaked in pure water was mixed
with the DCPD, partial coagulations of the DCPD were observed.
[0072]
(Comparative Example 1)
An experiment was performed in the same manner as in
Example 1, except that DCPD alone was used instead of the mixture
of the rapid filtration sand and the DCPD. As shown in Fig.
2, DCPD 9 and the glass wool 3 were charged in the glass column
casing 1 ( 10 cm) so that a filtration apparatus 5a was prepared.
The DCPD was the same as that used in Example 1.
Next, a fluorine-containing water to be treated was
poured at a flow rate of 50 ml/min from a tube 6 communicated
with an upper portion of the apparatus, and shortly after the
pouring, the water surface 8 of the fluorine-containing water
to be treated elevated to the upper surface of the apparatus.
Thus, a treated water was not obtained. Table 3 shows the flow
rate, fluorine concentration, and water level of the water to
be treated, and the flow rate and fluorine concentration of the
treated water. As the treated water was not obtained, the
fluorine concentration of the treated water was not measured.
[0073]
[Table 3]

(Comparative Example 2)
A tilting gravity mixer (capacity: 110 L) was charged with
glass and resin beads (effective diameter: 2 to 4 mm) generally
used for handicraft and decoration, and DCPD, at a mass ratio
of 90 parts by mass of the beads and 10 parts by mass of the

DCPD for 100 parts by mass in total, followed by mixing for three
minutes.
[0075]
A glass column casing was filled with the resulting
mixture in the same manner as in Example 1 so that a filtration
apparatus was prepared. Upon pouring a fluorine-containing
water to be treated from an upper portion of the filtration
apparatus, beads began floating, and the treated water in the
upper portion of the filtration apparatus became cloudy. The
permeability was evaluated, and the fluorine concentration was
measured in the same manner as in Example 1. Table 4 shows the
results. The results reveal that the DCPD is not sufficiently
carried by the beads.
[0076]
[Table 4]

INDUSTRIAL APPLICABILITY
[0077]
The treatment agent of the present invention has the
structure mentioned earlier, and thus can be preferably used
in the fields where fluorine-containing water or
fluorine-containing soil is generated, such as electroplating
industry, semiconductor producing industry, electronic valve
producing industry, and glass industry.
EXPLANATION OF SYMBOLS
[0078]
1: Glass column casing
2: Mixture of rapid filtration sand and DCPD
3: Glass wool

4: Fluorine-containing water to be treated
5, 5a: Filtration apparatus
6, 7: Tube
8: Water surface
9: DCPD

WE CLAIM
1. A treatment agent comprising:
calcium hydrogen phosphate dihydrate (A); and
particles (B),
wherein the particles (B) carry the calcium hydrogen
phosphate dihydrate (A).
2. The treatment agent according to claim 1,
wherein the particles (B) are substantially particles
having a particle diameter of 0.3 to 3.0 mm.
3. The treatment agent according to claim 1 or 2,
wherein the particles (B) have a uniformity coefficient
of 1.5 or less.
4. The treatment agent according to claim 1, 2, or 3,
wherein the calcium hydrogen phosphate dihydrate (A) has
an average particle diameter of 30 to 70 µm.
5. A method of producing the treatment agent according
to claim 1, 2, 3, or 4, comprising
mixing calcium hydrogen phosphate dihydrate (A) and
particles (B) with a tilting gravity mixer.
6. A treatment method comprising
allowing the treatment agent according to claim 1, 2, 3,
or 4 to make contact with a fluorine-containing water to be
treated, to thereby remove the fluorine from the water to be
treated.
7. A treatment method comprising
mixing the treatment agent according to claim 1, 2, 3,
or 4 with a fluorine-containing soil, to thereby insolubilize
the fluorine in the soil.

8. The treatment method according to claim 7,
wherein the soil is earth or sludge.

The present invention provides a treatment agent and a
treatment method capable of simply and efficiently removing
fluorine in an effluent. The treatment agent includes calcium
hydrogen phosphate dihydrate (A) ; and particles (B), wherein
the particles (B) carry the calcium hydrogen phosphate
dihydrate (A). The present invention also relates to a
treatment method including allowing the treatment agent
according to make contact with a fluorine-containing water to
be treated, to thereby remove the fluorine from the water to
be treated. The present invention further relates to a
treatment method including mixing the treatment agent with a
fluorine-containing soil, to thereby insolubilize the fluorine
in the soil.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=f/hf7jiqMNCIX4uoZ2rQUQ==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

277145

Indian Patent Application Number

4509/KOLNP/2011

PG Journal Number

47/2016

Publication Date

11-Nov-2016

Grant Date

11-Nov-2016

Date of Filing

02-Nov-2011

Name of Patentee

DAIKIN INDUSTRIES, LTD.

Applicant Address

UMEDA CENTER BUILDING, 4-12, NAKAZAKI-NISHI 2-CHOME, KITA-KU, OSAKA-SHI, OSAKA 530-8323, JAPAN

Inventors:

#	Inventor's Name	Inventor's Address
1	MATSUOKA TAKAHARU	C/O DAIKIN INDUSTRIES, LTD., YODOGAWA PLANT, 1-1, NISHIHITOTSUYA, SETTSU-SHI, OSAKA 566858 JAPAN
2	MAEDA IWAO	C/O DAIKIN INDUSTRIES, LTD., YODOGAWA PLANT, 1-1, NISHIHITOTSUYA, SETTSU-SHI, OSAKA 5668585 JAPAN
3	KOIZUMI MICHINOBU	C/O DAIKIN INDUSTRIES, LTD., YODOGAWA PLANT, 1-1, NISHIHITOTSUYA, SETTSU-SHI, OSAKA 5668585 JAPAN
4	OTOI KENJI	C/O DAIKIN INDUSTRIES, LTD., YODOGAWA PLANT, 1-1, NISHIHITOTSUYA, SETTSU-SHI, OSAKA 5668585 JAPAN

PCT International Classification Number

C02F 1/58

PCT International Application Number

PCT/JP2010/058536

PCT International Filing date

2010-05-20

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2009-122969	2009-05-21	Japan