JP2006224025A - Method for immobilizing fluorine and/or boron - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insolubilizing agent capable of insolubilizing fluorine and/or boron, more particularly rapidly and efficiently and selectively insolubilizing or immobilizing the fluorine and/or the boron even in the coexistence of miscellaneous ions in a wide concentration range from a high concentration to a low concentration. <P>SOLUTION: The method for insolubilizing the fluorine and/or boron of a solid content containing the fluorine and/or boron comprises insolubilizing the fluorine and/or boron by using the insolubilizing agent containing calcium aluminate and calcium silicate and curing the fluorine and/or boron by allowing moisture of 5 to 250wt% to coexist in the total of the solid content and the insolubilizing agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides an insolubilization method that effectively insolubilizes fluorine and / or boron. In the presence of moisture, an insolubilizing agent is added to and mixed with solid components such as coal ash, incineration ash, or sludge. Provided is an insolubilization method capable of insolubilizing and immobilizing fluorine and / or boron quickly and efficiently even in the presence of coexisting ions.

  Conventionally, coal ash after using coal as an energy source has been used as a cement raw material, a soil improvement material, and the like from the viewpoint of effective use of resources.

  However, in coal ash, fluorine and / or boron may be contained in excess of environmental standards, which includes the possibility of secondary contamination due to elution. Also, industrial waste sludge and the like contain fluorine and / or boron above the environmental standard, and in some cases above the judgment standard (hereinafter referred to as “landfill standard”) related to landfill disposal in the Waste Management Law. And even landfill disposal can be a problem.

  Many environmental technologies that insolubilize and immobilize harmful ions in water and soil have been proposed in the past. However, a wide range of concentrations of harmful anions such as fluorine and / or boron can be used efficiently without causing environmental impact. There are currently no known materials that can be processed selectively and inexpensively.

  Therefore, a material that is harmless and inexpensive and that efficiently insolubilizes and immobilizes fluorine and / or boron in solid contents such as coal ash is required.

  Conventionally, techniques for reducing and insolubilizing fluorine and boron using calcium compounds, aluminum compounds, or calcium aluminates are known (Patent Documents 1 to 8).

JP-A-57-27191 JP-A-57-81881 JP 2000-246267 A JP 2000-225383 A JP 2000-335946 A JP 2001-239273 A JP 2002-66548 A JP 2002-136965 A

  A material that can efficiently insolubilize fluorine and / or boron in a solid content such as coal ash is currently most demanded, but an insolubilizing agent and an insolubilizing method that satisfy this requirement have not yet been provided.

  That is, in the above-mentioned Patent Document 1, it is described that wastewater of about 200 mg / L can be reduced to about 1 mg / L as fluorine ions, but it is very complicated such as pH adjustment of wastewater and a multistage process. It requires processing.

  In the above-mentioned patent document 2, it is described that simulated waste water containing about 10 to 500 mg / L as boron ions can be reduced to about 3 mg / L, but the level that can satisfy the currently required environmental standards. It's hard to say.

  Patent Documents 3 to 5 described above describe immobilizing fluorine using a calcium aluminate compound, but a large amount of immobilizing agent is required, and it cannot be said that fluorine can be sufficiently insolubilized. Is. Moreover, it cannot be said that boron can be sufficiently insolubilized simultaneously with fluorine.

  In the above-mentioned Patent Document 6, it is described that fluorine and boron can be processed at a high level, but it is difficult to say that the level can satisfy the currently required environmental standards. Moreover, since embodiment is complicated, the place to utilize is limited.

  In the aforementioned Patent Documents 7 and 8, there is described a method of using rock salt type oxides containing magnesium or the like for wastewater treatment, but there is no mention of a method for removing low concentrations of fluorine ions and boron ions. . In addition, this method uses a large amount of harmful nitrate ions in the production of the insolubilizing agent, and is not necessarily a recommended production method.

  The technical problem can be achieved by the present invention as follows.

  That is, the present invention is a method for insolubilizing fluorine and / or boron containing solids containing fluorine and / or boron, using an insolubilizing agent containing calcium aluminate and calcium silicate, and insolubilizing with solids. This is a method for insolubilizing fluorine and / or boron, characterized by curing in the presence of 5 to 250% by weight of water relative to the total amount of the agent (Invention 1).

  Further, the present invention is the fluorine and / or boron insolubilization method of the present invention 1, wherein the insolubilizing agent is one or more selected from calcium oxide, calcium hydroxide and calcium carbonate together with calcium aluminate and calcium silicate. It is a fluorine and / or boron insolubilization method characterized by containing (Invention 2).

Further, the present invention is the fluorine and / or boron insolubilization method according to the present invention 1 or 2, wherein the calcium aluminate is Ca ₁₂ Al ₁₄ O ₃₃ and / or Ca ₃ Al ₂ O ₆ (present Invention 3).

Further, the present invention is the fluorine and / or boron insolubilization method according to any one of the present inventions 1 to 3, wherein the calcium silicate is either Ca ₃ SiO ₅ or Ca ₂ SiO ₄ (this Invention 4).

  Further, the present invention is the fluorine and / or boron insolubilization method according to any one of the present inventions 1 to 4, wherein the insolubilizing agent further contains calcium sulfate and / or calcium sulfate hydrate. This is a method for insolubilizing fluorine and / or boron (Invention 5).

  Further, the present invention is the fluorine and / or boron insolubilization method according to any one of the present inventions 1 to 5, wherein the solid content containing fluorine and / or boron is coal ash, incineration ash or sludge. There is (Invention 6).

  Further, the present invention is the fluorine and / or boron insolubilization method according to any one of the present inventions 1 to 6, wherein the curing is performed at room temperature (this invention) 7).

  The method for insolubilizing fluorine and / or boron according to the present invention can insolubilize and immobilize fluorine and / or boron in a wide concentration range, so when used for detoxifying solids such as coal ash, incineration ash or sludge. By adding an insolubilizing agent to solids such as coal ash in the presence of moisture and curing for a certain period of time, elution of fluorine and / or boron from the solids can be suppressed below the environmental standard value, and fluorine and / or Or even if it is solid content with a remarkably high content of boron, it can be reduced below the landfill standard, so it is suitable as a method for insolubilizing fluorine and / or boron.

  In addition, solid content such as coal ash treated by the fluorine and / or boron insolubilization method according to the present invention is harmless / non-toxic even when the insolubilizer itself used is reused for roadbed materials, soil improvement materials, etc. Therefore, the load on the environment is small. In addition, the solid content obtained by insolubilizing and immobilizing fluorine and / or boron by the fluorine and / or boron insolubilization method according to the present invention does not form a strong lump, so it should be used in powder form according to the intended application. Can do.

  The configuration of the present invention will be described in more detail as follows.

  First, an insolubilizing agent (hereinafter referred to as “insolubilizing agent”) for insolubilizing fluorine and / or boron in the present invention will be described.

The insolubilizing agent in the present invention contains calcium silicate together with calcium aluminate.
If necessary, it may further contain one or more selected from calcium oxide, calcium hydroxide or calcium carbonate, or may contain calcium sulfate, so that the effect of insolubilization becomes higher.

Calcium aluminate _{is Ca 12 Al 14 O 33, Ca} 3 Al 2 O 6 and CaAl ₂ O ₄ or the like, preferably a _{Ca 12 Al 14 O 33, Ca} 3 Al 2 O 6.

The calcium silicate in the present _{invention, CaSiO 3, Ca 2 SiO 4} , Ca 3 SiO 5 , etc., or a hydrate thereof are preferable, and more preferably _{Ca 3 SiO 5, Ca 2 SiO} 4 are preferred.

  When the insolubilizing agent in the present invention contains calcium sulfate, the insolubilizing effect becomes higher.

The calcium sulfate in the present invention, CaSO ₄ or CaSO ₄ · nH ₂ O is preferable.

Further, the insolubilizing agent in the present invention, when subjected to composition analysis by X-ray fluorescence to be described later, the silicon content is preferably 10 to 50 wt% in terms of SiO _2. When the silicon content in the insolubilizing agent is outside the above range, fluorine can be insolubilized / immobilized, but boron insolubilization / immobilization is not sufficient. More preferably, it is 10 to 40% by weight.

Further, the insolubilizing agent in the present invention, when subjected to composition analysis by X-ray fluorescence to be described later, the aluminum content is preferably 10 to 40 wt% in terms of Al ₂ O _3. When the aluminum content in the insolubilizing agent is outside the above range, insolubilization / immobilization of fluorine and boron is not sufficient. More preferably, it is 10 to 30% by weight.

Moreover, in the insolubilizing agent in this invention, when the composition analysis by the fluorescent X ray mentioned later is performed, 40-80 weight% of calcium content is preferable in conversion of CaO. When the calcium content in the insolubilizing agent is outside the above range, insolubilization / immobilization of fluorine and boron is not sufficient.
In particular, when it contains calcium oxide, calcium hydroxide or calcium carbonate, 50 to 80% by weight is more preferable.

In the insolubilizing agent in the present invention, when composition analysis by fluorescent X-ray described later is performed, the content ratio of silicon and aluminum is the weight ratio of SiO ₂ conversion and Al ₂ O ₃ conversion (SiO ₂ / Al ₂ O _{3, respectively).} ) And 40/60 to 70/30 are preferable. When the content ratio of silicon and aluminum is outside the above range, it becomes difficult to sufficiently insolubilize and fix fluorine and / or boron.

Further, the insolubilizing agent in the present invention, when subjected to composition analysis by X-ray fluorescence to be described later, the content of calcium and aluminum, the weight ratio of the respective terms of CaO and _Al 2 _{O 3} in terms of (CaO / _Al 2 _{O 3} ) And 60/40 to 95/5 are preferable. When the content ratio of calcium and aluminum is out of the above range, it becomes difficult to sufficiently insolubilize and fix fluorine and / or boron.
In particular, when calcium oxide, calcium hydroxide or calcium carbonate is contained, the content ratio of calcium and aluminum (CaO / Al ₂ O ₃ ) is preferably 70/30 to 95/5.

Further, the insolubilizing agent according to the present invention, when subjected to composition analysis by X-ray fluorescence to be described later, the content of sulfur and aluminum, the weight ratio of each converted to SO ₃ and _Al 2 _{O 3} in terms of _(SO 3 / Al ₂ O ₃ ) is preferably 10/90 to 40/60. When the content ratio of calcium and aluminum is out of the above range, it becomes difficult to sufficiently insolubilize and immobilize fluorine and / or boron.

  When the insolubilizing agent in the present invention is analyzed by X-ray diffraction according to the method described later, the total content of calcium aluminate is 5 to 1000 when the total content of calcium silicate is 100. It is preferable. If it is less than 5, there are few sites for fixing the harmful anions of calcium aluminate, and the progress of the hydration reaction involving calcium aluminate becomes insufficient, making it difficult to exert a sufficient insolubilizing effect. . If it exceeds 1000, the hydration reaction or pozzolanic reaction mainly composed of calcium silicate does not proceed sufficiently, and it is difficult to exert a sufficient effect of insolubilization. More preferably, it is 10-500.

  Moreover, the insolubilizing agent in this invention WHEREIN: When the sum total of the content rate of a calcium silicate is set to 100, 0-200 are preferable for the content rate of a calcium oxide, a calcium hydroxide, or a calcium carbonate.

  The insolubilizing agent in the present invention preferably has a calcium sulfate content of 1 to 100 when the total content of calcium silicate is 100.

  The particle shape of the insolubilizing agent in the present invention is indefinite or granular.

  The average particle diameter of the insolubilizing agent in the present invention is preferably 0.2 to 50.0 μm. Since the insolubilizing agent according to the present invention is prepared by baking at a high temperature of 850 to 1450 ° C., it is difficult to industrially produce particles having a size of 0.2 μm or less. Even if the average particle size is less than 0.2 μm, there is no functional problem, but it is difficult to handle the powder. When it exceeds 50 μm, it is not preferable in terms of work, cost, and the like in that uniformity during mixing with solids containing fluorine and / or boron such as coal ash is deteriorated and a large amount of addition is required. Preferably it is 0.5-40.0 micrometers.

The BET specific surface area value of the insolubilizing agent in the present invention is preferably from 0.1 to 10 m ² / g. When the BET specific surface area value is less than 0.1 m ² / g, work such as reduction in uniformity during mixing with solids containing fluorine and / or boron, such as coal ash, increases the amount added This is not preferable in terms of cost and cost. Since the insolubilizing agent in the present invention is prepared by baking at a high temperature of 850 to 1450 ° C., it is difficult to industrially produce an insolubilizing agent exceeding 10 m ² / g. An insolubilizer having a BET specific surface area value exceeding 10 m ² / g has no functional problem, but is difficult to handle as a powder. More preferably, it is 0.3-5 m < ² > / g.

  Next, the manufacturing method of the insolubilizer in this invention is described.

  First, the manufacturing method of the calcium aluminate in this invention is described.

  The calcium aluminate in the present invention can be obtained by mixing a calcium compound and an aluminum compound and then heat-treating at a temperature of 850 to 1200 ° C. in an oxidizing or atmospheric atmosphere. Further, if necessary, a pulverization treatment or a surface treatment with an inorganic substance, an organic substance or a polymer can be performed.

  As the calcium compound, calcium hydroxide (slaked lime), calcium carbonate, calcium oxide, calcium nitrate and the like can be used, and calcium hydroxide and calcium carbonate are preferred. The average particle size of the calcium compound is preferably 0.2 to 20 μm.

  As the aluminum compound, aluminum hydroxide, aluminum oxide, aluminum nitrate or the like can be used, and aluminum hydroxide is preferable. The average particle size of the aluminum compound is preferably 0.1 to 20 μm.

  What is necessary is just to mix the mixing ratio of a calcium compound and an aluminum compound so that it may become a predetermined | prescribed composition ratio.

  As a mixer in the manufacturing method, a raking machine, a roller type mixer, a vibration mill, a bead mill, a disk type wet stirring and mixing tank, or the like can be used.

  In the mixing state of the mixture which is a precursor of the insolubilizing agent in the present invention, the subsequent solid phase reaction is caused uniformly and promptly. Therefore, it is important to select a mixer and mixing conditions. It is preferable to use a machine in terms of uniform mixing.

  When the heating temperature is less than 850 ° C., the dehydration reaction, decarboxylation reaction and solid phase reaction of the mixed powder do not proceed, or the proceeding speed is extremely slow, which is not preferable. On the other hand, when the heating temperature exceeds 1200 ° C., the particle size of the generated composite oxide particles increases, and the reactivity with harmful anions in the aqueous system decreases, which is not preferable. The heating temperature is more preferably 900 to 1150 ° C. In consideration of industrial productivity, the heating time is preferably 30 minutes to 180 minutes. The heating atmosphere may be an oxidizing or atmospheric atmosphere. When a large amount of carbonate ions are contained in the heated product particles, the reactivity with harmful anions in the aqueous system is lowered, so heat treatment in carbon dioxide gas is not preferable.

  In the present invention, the powder after the heat treatment may be dry-pulverized and surface-treated with an inorganic material, an organic material, or a polymer.

  Since the dry pulverization treatment can reduce the average particle size of the powder after the heat treatment, the reactivity with fluorine and / or boron in the solid content of the insolubilizing agent can be improved. As an apparatus that can be used for the dry pulverization treatment, a free pulverizer, a hammer mill, or the like can be used.

  In addition, by subjecting the powder after the heat treatment to a surface treatment with an inorganic substance, an organic substance, a polymer, or the like, the reactivity with fluorine and / or boron and the dispersibility in a solid content can be controlled. As the surface treatment agent, a hydrophilic organic material, polymer, or inorganic material can be used to promote reactivity. It can also be controlled so that the reaction proceeds gradually by making it hydrophobic with a rosin compound, a silane coupling agent, a higher fatty acid or the like. The coating amount of the surface treatment agent on the insolubilizer powder is preferably 0.1 to 5% by weight with respect to the composite oxide particle powder. As the surface treatment machine, it is possible to use a roughing machine, a vibration mill, a roller type mixer, a wet tank equipped with a stirrer, or the like.

  The insolubilizing agent containing calcium silicate in the present invention is a mixture of calcium aluminate and an amount of calcium silicate produced together with calcium aluminate in the calcium aluminate production method, and then 850 to A method of manufacturing by heating at 1450 ° C. in an oxidizing or atmospheric atmosphere, mixing a pre-manufactured calcium aluminate and a pre-manufactured calcium silicate or a material mainly composed of calcium silicate such as Portland cement It can obtain by the method of doing.

  The insolubilizing agent containing calcium oxide, calcium hydroxide or calcium carbonate in the present invention is produced by adjusting the ratio of the calcium compound and the aluminum compound in the calcium aluminate production method so that calcium is present in excess. It can be obtained by a method, a method in which calcium aluminate prepared in advance and calcium oxide, calcium hydroxide or calcium carbonate are mixed. Calcium hydroxide and calcium carbonate are produced by the reaction of calcium oxide with moisture or carbon dioxide, and may be produced by changing from calcium oxide in the process of preserving the insolubilizer in the present invention. .

  The insolubilizing agent containing calcium sulfate in the present invention can be obtained by a method in which a calcium compound and a sulfuric acid component are reacted and mixed with calcium aluminate prepared in advance.

  If necessary, pulverization and surface treatment with an inorganic substance, an organic substance, or a polymer can be further performed.

  Next, the insolubilization method according to the present invention will be described.

  In the insolubilization method according to the present invention, an insolubilizing agent is allowed to coexist with a solid substance (such as coal ash) that may release harmful anions, and water is present to suppress the elution of harmful anions into an aqueous system. Hereinafter, the method for insolubilizing fluorine and / or boron in the present invention will be described.

  In the present invention, the amount of the insolubilizing agent added to the solid content is preferably 0.1 to 25% by weight. If it is less than 0.1% by weight, the progress of the insolubilization reaction is slow, which is not preferable. If it exceeds 25% by weight, the effect is saturated, so there is no point in adding more than necessary. More preferably, it is 0.5 to 18% by weight.

  In the present invention, 5 to 250% by weight of water is present with respect to the total amount of the solid content and the insolubilizing agent. If the amount of water present is less than 5% by weight, the progress of the insolubilization reaction is slow, which is not preferable. When it exceeds 250% by weight, the effect is saturated, and the mixture of the treatment object and the insolubilizing agent becomes a paste or a slurry due to excessive moisture, which is not preferable as a soil decontaminating agent, and the weight is increased even in landfill disposal. Since it increases, it is not preferable. More preferably, it is 10 to 200% by weight.

  In the present invention, the temperature when contacting the insolubilizing agent (curing temperature) is not particularly limited, but in the present invention, fluorine and / or boron can be easily insolubilized at room temperature. When the temperature is extremely low, for example, when the temperature is 5 ° C. or lower, the reaction rate of the insolubilizing agent is small, and the trapping rate of harmful anions is small. The normally used temperature range is preferably 5 to 90 ° C, more preferably 10 to 50 ° C.

  In the present invention, it is not necessary to control the pressure during curing, and the insolubilization process may be performed under normal pressure (atmospheric pressure).

  The time for curing may be changed according to the content of fluorine and / or boron in the solid content, but is usually about 12 hours to 10 days.

<Action>
An important point in the present invention is that insolubilizing agents in the present invention can be used to insolubilize and immobilize low to high concentrations of harmful anions such as fluorine and / or boron eluted from solids in the presence of moisture. It is a fact.

  In the present invention, calcium aluminate adsorbs monovalent or divalent anions containing fluorine ions, boron ions, or fluorine ions and boron ions, and is insolubilized and immobilized by a rapid curing reaction.

  In addition, the function of calcium silicate has not yet been fully elucidated. However, after calcium aluminate adsorbs monovalent or divalent anions containing fluorine ions, boron ions or fluorine ions and boron ions, it continues further. In particular, the inventor presumes that the curing reaction proceeds to promote insolubilization and immobilization.

  Although the functions of calcium oxide, calcium hydroxide or calcium carbonate and calcium sulfate have not yet been fully elucidated, each compound once binds reversibly to fluorine and / or boron, and calcium aluminate or calcium silicate and moisture. The present inventor presumes that a function of bridging fluorine and / or boron is exhibited in the curing reaction.

  In this invention, since solid content, such as coal ash, and an insolubilizing agent are made to contact in presence of a water | moisture content, a fluorine and / or boron can be insolubilized efficiently.

  As described above, since the insolubilizing agent used in the present invention has high reactivity, fluorine and / or boron in the solid content can be firmly fixed and insolubilized even when used in a small amount.

  In the present invention, insolubilized solid matter such as coal ash does not harden, so that it can be handled as a powder and used for applications such as a soil conditioner.

  A typical embodiment of the present invention is as follows.

  The average particle diameter of the insolubilizing agent is indicated by the average value of numerical values measured from electron micrographs.

  The content of each metal element in the insolubilizing agent was expressed in terms of weight percentage in terms of oxide by using a “fluorescent X-ray apparatus (manufactured by Rigaku Corporation, RIX2100)”.

  The crystal phase of the insolubilizer is identified by “X-ray diffractometer RINT2500 (manufactured by Rigaku Corporation)” (tube: Cu, tube voltage: 40 kV, tube current: 300 mA, goniometer: wide angle goniometer, sampling width: 0.010 °, scanning speed: 4.00 ° / min, diverging slit: 1/2 °, scattering slit: 1/2 °, light receiving slit: 0.15 mm). The content ratio of each crystal phase was determined by a simple quantitative method based on diffraction data.

  The BET specific surface area value was shown as a value measured by the BET method.

  The content of the constituent elements in the solid content was expressed as a percentage by weight in terms of oxide by using a “fluorescent X-ray apparatus (manufactured by Rigaku Corporation, RIX2100)”.

The fluorine ion concentration in the solid content was measured by an alkali fusion ion chromatographic method.
The boron ion concentration in the solid content is determined by dissolving the powder with an acid such as hydrochloric acid or melting with an alkali such as K ₂ S ₂ O ₇ or Na ₂ CO _3. (Inc.) ”.

  The amount of carbon and sulfur in the coal ash or sludge were measured with a “carbon / sulfur analyzer (EMIA-820W, manufactured by Horiba, Ltd.)”.

The concentration of fluorine ions eluted from the solid content was measured by ion chromatography.
The boron ion concentration eluted from the solid content was evaluated using the above-mentioned “Plasma Optical Emission Spectrometer SPS4000 (Seiko Electronics Co., Ltd.)”.

Properties of coal ash Two types of coal ash and one type of sludge were prepared as targets for insolubilization treatment. About these, the density | concentration of the fluorine and boron which were eluted by the shaking test according to Environment Agency notification 46 was measured.

  Table 1 shows the composition of coal ash and sludge used for the insolubilization treatment.

<Evaluation method of elution amount of fluorine and boron in coal ash to which insolubilizing agent is applied>
Measurements were made in accordance with Environmental Agency Notification No.46.
That is, the object after curing was air-dried, 100 g was measured, 10 times the amount of ion-exchanged water was added, and the mixture was shaken for 6 hours with a shaker (200 shakes / min, shake width 4.5 cm). Then, the solid content was filtered off from the aqueous solution. The fluorine ion concentration in the filtrate was measured by an ion chromatograph method, and the boron ion concentration was evaluated using the above-mentioned “plasma emission spectroscopic analyzer SPS4000 (Seiko Electronics Co., Ltd.)”.

Insolubilizer 1: Production of insolubilizer 50.0 g of slaked lime powder (JIS special name, BET specific surface area value 15 m ^{2 /} g, equivalent to Ca = 0.67 mol) and 68.6 g of aluminum hydroxide (C-301, manufactured by Sumitomo Chemical) BET specific surface area value of 2.0 m ^{2 /} g, equivalent to Al = 0.88 mol) was mixed for 1 hour using a Reika machine. 70 g of the obtained mixed powder was put in an alumina crucible and heat-treated in a muffle furnace at 1000 ° C. for 2 hours in air.
30 g of the powder powder after heat treatment and 170 g of ordinary Portland cement were pulverized and mixed for 1 hour using a Leica machine. The obtained particle powder was grayish white.

Constituent elements of the obtained insolubilizer were 71.6% CaO, 10.2% Al ₂ O ₃ , 10.5% SiO ₂ , 1.5% SO ₃ , and 4% Fe ₂ O ₃ . 0% and others were 2.2%. The SiO ₂ / Al ₂ O ₃ ratio was 1.0, the CaO / Al ₂ O ₃ ratio was 7.0, and the SO ₃ / Al ₂ O ₃ ratio was 0.15.
Moreover, as a result of identification of the crystal phase constituting the insolubilizing agent, calcium aluminate of Ca ₁₂ Al ₁₄ O ₃₃ and Ca ₃ Al ₂ O ₆ , calcium silicate of Ca ₂ SiO ₄ and Ca ₃ SiO ₅ , Ca (OH) ₂ and a mixed phase of CaSO ₄ · nH ₂ O. The proportion of each crystal phase is 19 in which the total amount of calcium aluminate of Ca ₁₂ Al ₁₄ O ₃₃ and Ca ₃ Al ₂ O ₆ is 19, and the total amount of calcium silicate of Ca ₂ SiO ₄ and Ca ₃ SiO ₅ is 67, Ca (OH) 2 was 3, CaSO ₄ · nH ₂ O was 4, and others were 7.
The average particle size was 0.8 μm, and the BET specific surface area value was 2.0 m ² / g.

Insolubilizer 2-6,
An insolubilizing agent was obtained in the same manner as in Example 1 except that the type of calcium aluminate raw material, the Ca / Al ratio, and the heating temperature were variously changed, and the type of calcium silicate raw material and the content ratio thereof were variously changed.

  Various properties of the obtained insolubilizer are shown in Table 2.

<Insolubilization test>
Example 1
3% by weight of the insolubilizing agent 1 was added to the coal ash 1, and then 25% by weight of water was added to the total amount of the coal ash and the insolubilizing agent. Thereafter, it was kept for 5 days and cured.
With respect to the solid content after the insolubilization treatment, the elution amounts of fluorine and boron were measured according to the above <Method for evaluating the elution amount of fluorine and boron in coal ash to which an insolubilizing agent was applied>.

Examples 2-11, Comparative Examples 1-7:
The insolubilization test was conducted in the same manner as in Example 1 except that the type of the object, the type and addition amount of the insolubilizing agent, the addition amount of water, and the curing period were variously changed. Table 3 shows the conditions of insolubilization treatment and the elution amounts of fluorine and boron in each object after the insolubility test.

Since the insolubilization method according to the present invention can insolubilize and fix fluorine and / or boron in a wide concentration range, it is suitable as an insolubilization method for fluorine and / or boron, which are harmful anions contained in coal ash and the like.
In addition, the insolubilization method according to the present invention is a simple processing method without requiring a complicated processing step. Furthermore, the insolubilization method according to the present invention is also applicable to insolubilization and immobilization of fluorine compounds and boron compounds in solids such as coal ash in which fluorine compounds, boron compounds and chloride ions, sulfate ions, carbonate ions coexist. Is valid.

  Furthermore, since the insolubilizing agent in the present invention is composed of harmless elements or compounds, even when the solid content containing the insolubilizing agent is disposed of in landfill, the burden on the environment is small.

X-ray diffraction pattern of insolubilizer 2.

Claims (7)

A method for insolubilizing solid fluorine and / or boron containing fluorine and / or boron, wherein an insolubilizing agent containing calcium aluminate and calcium silicate is used, and the total amount of the solid and insolubilizing agent is used. A method for insolubilizing fluorine and / or boron, comprising curing in the presence of 5 to 250% by weight of water. 2. The method for insolubilizing fluorine and / or boron according to claim 1, wherein the insolubilizing agent contains at least one selected from calcium oxide, calcium hydroxide and calcium carbonate together with calcium aluminate and calcium silicate. A method for insolubilizing fluorine and / or boron. Fluorine and / or boron method of insolubilization of claim 1 or 2, wherein the calcium aluminate is _Ca 12 _Al 14 _{O 33} and / or _Ca 3 _Al 2 _{O 6.} The method for insolubilizing fluorine and / or boron according to any one of claims 1 to 3, wherein the calcium silicate is either Ca ₃ SiO ₅ or Ca ₂ SiO ₄ . 5. The method for insolubilizing fluorine and / or boron according to claim 1, wherein the insolubilizing agent further contains calcium sulfate and / or calcium sulfate hydrate. Alternatively, boron insolubilization method. The method for insolubilizing fluorine and / or boron according to any one of claims 1 to 5, wherein the solid content containing fluorine and / or boron is coal ash, incinerated ash, or sludge. The method for insolubilizing fluorine and / or boron according to any one of claims 1 to 6, wherein curing is performed at room temperature.

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