JP2009286639A - Apparatus and method for recovering fluorine and ammonia - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recovery apparatus which recovers both fluorine and ammonia from raw water containing fluorine and ammonia. <P>SOLUTION: The recovery apparatus which recovers fluorine and ammonia from raw water containing fluorine and ammonia includes: a crystallization reaction vessel for forming crystals of calcium fluoride by adding a calcium agent to raw water; a calcium agent adding means to add the calcium agent to the raw water; and an ammonia concentrating means to concentrate ammonia contained in the crystallization-treated water from which fluorine has been removed in the crystallization reaction vessel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recovery apparatus and a recovery method for recovering fluorine and ammonia from raw water containing fluorine and ammonia.

  Wastewater containing fluorine and ammonia may be discharged from manufacturing processes of electronic products such as semiconductors and liquid crystal display devices and parts thereof, and other industries. For such wastewater, in general, after adding an alkali agent such as sodium hydroxide to wastewater containing fluorine and ammonia, evaporating and concentrating it, separating it into ammonia water and sodium fluoride water, Concentrate and collect. In this method, an evaporative concentration apparatus is used to remove fluorine. However, the evaporative concentration apparatus must use a large amount of steam and chemicals, and the cost required for recovery is enormous. On the other hand, sodium fluoride water is treated by a coagulation sedimentation treatment or the like.

  The sludge containing sodium fluoride generated during the wastewater treatment is dehydrated by a dehydrator or the like to become a dehydrated cake and is treated as waste. The amount is large, increasing the environmental load. In addition, wastewater discharged from the ammonia distillation tower is directly processed by a wastewater treatment apparatus using microorganisms.

  Various proposals have been made for the treatment of fluorine-containing water (for example, Patent Documents 1 to 3).

JP 2004-174416 A JP 2007-117874 A Japanese Patent No. 3284260

  Thus, a recovery apparatus and a recovery method for recovering both fluorine and ammonia from raw water containing fluorine and ammonia have not been known.

  The present invention is a recovery apparatus and recovery method for recovering both fluorine and ammonia from raw water containing fluorine and ammonia.

  The present invention is a recovery device for recovering fluorine and ammonia from raw water containing fluorine and ammonia, comprising a crystallization reaction tank for generating calcium fluoride crystals by adding a calcium agent to the raw water, and the calcium Fluorine and ammonia recovery device comprising calcium agent addition means for adding an agent to the raw water and ammonia concentration means for concentrating ammonia contained in the crystallization treated water from which fluorine has been removed in the crystallization reaction tank .

  Further, in the fluorine and ammonia recovery apparatus, it is preferable that a control means for controlling the amount of calcium agent added by the calcium agent addition means is provided, and a calcium agent having a chemical equivalent to or less than the fluorine concentration contained in the raw water is added. .

  The fluorine and ammonia recovery device further includes a crystallization treatment water pH adjuster addition means for adding a pH adjustment agent to the crystallization treatment water, and adjusts the pH of the crystallization treatment water to a range of 12-13. It is preferable to do.

  In the fluorine and ammonia recovery apparatus, an ammonia evaporating and concentrating means for evaporating and concentrating ammonia from the crystallization treated water may be provided before the ammonia concentrating means.

  Further, the present invention is a recovery method for recovering fluorine and ammonia from raw water containing fluorine and ammonia, comprising a crystallization reaction step of adding calcium agent to the raw water to produce calcium fluoride crystals; And an ammonia concentration step of concentrating ammonia contained in the ammonia-containing water from which fluorine has been removed in the precipitation reaction step.

  In the method for recovering fluorine and ammonia, in the crystallization reaction step, it is preferable to add a calcium agent having a chemical equivalent to or less than the fluorine concentration contained in the raw water.

  The fluorine and ammonia recovery method preferably includes a pH adjustment step of adjusting the pH of the crystallization treated water to a range of 12-13.

  In the method for recovering fluorine and ammonia, an ammonia evaporating and concentrating step of evaporating and concentrating ammonia from the crystallization treated water may be included before the ammonia concentrating step.

  In the present invention, a calcium agent is added to raw water containing fluorine and ammonia to produce calcium fluoride crystals to remove fluorine, and by concentrating ammonia contained in the crystallization treated water from which fluorine has been removed, Both fluorine and ammonia can be recovered from raw water containing fluorine and ammonia.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  In the recovery method according to the present embodiment, a calcium agent is added to raw water containing fluorine and ammonia to generate calcium fluoride crystals to remove fluorine (crystallization reaction step), and the crystallization treatment from which fluorine has been removed Fluorine and ammonia are recovered by concentrating ammonia contained in water (ammonia concentration step).

  FIG. 1 shows a schematic configuration of an example of a recovery apparatus according to an embodiment of the present invention. 1 includes a raw water tank 10, a pH adjustment tank 12, a crystallization reaction tank 14, a slurry storage tank 16, a dehydration apparatus 18, a crystallization treatment water tank 20, and a crystallization treatment water pH adjustment tank. 22 and an ammonia distillation apparatus 24 which is an ammonia concentration means.

  In the recovery device 1 of FIG. 1, a raw water pipe from the raw water tank 10 is connected to the pH adjustment tank 12 via a pump 26. A pH adjusting liquid pipe from the pH adjusting tank 12 is connected to the crystallization reaction tank 14 via a pump 28. The crystallization water tank 20 is connected to the crystallization water pipe from the crystallization reaction tank 14. A crystallization water pipe from the crystallization water tank 20 is connected to the crystallization water pH adjustment tank 22 via a pump 36. The ammonia distillation apparatus 24 is connected to a pH adjustment liquid pipe from the crystallization treated water pH adjustment tank 22 via a pump 38, and an ammonia water pipe is connected to the outlet of the ammonia distillation apparatus 24 via a pump 40. ing. The slurry storage tank 16 is connected to a slurry pipe from the lower part of the crystallization reaction tank 14 via a pump 30. A slurry pipe from the slurry storage tank 16 is connected to the dehydrator 18 via a pump 32, and a pellet pipe is connected to the outlet of the dehydrator 18 via a pump 34. The pH adjusting tank 12 and the crystallization treated water pH adjusting tank 22 are agitators 44 and 54 which are stirring means equipped with a motor and a stirring blade for stirring the fluid in the pH adjusting tank 12 or the crystallization treated water pH adjusting tank 22. Further, pH meters 42 and 52 as pH measuring means are respectively installed. The crystallization reaction tank 14 is provided with a stirring device 46 which is a stirring means including a motor and a stirring blade 48 for stirring the fluid in the crystallization reaction tank 14, and includes a draft tube 50. The raw water tank 10 and the crystallization treatment water tank 20 may be provided with a stirring device.

  The fluorine and ammonia recovery method and the operation of the recovery apparatus 1 according to this embodiment will be described.

  Fluorine / ammonia-containing raw water containing fluorine and ammonia (hereinafter sometimes simply referred to as “raw water”) is fed from the raw water tank 10 to the pH adjustment tank 12 through the raw water pipe by the pump 26. In the pH adjusting tank 12, while being stirred by the stirring device 44, a pH adjusting agent is added by pH adjusting agent adding means such as a pump to adjust the pH to a predetermined range (pH adjusting step). The addition amount of the pH adjusting agent may be adjusted by controlling a pump or the like based on the pH of the liquid in the pH adjusting tank 12 measured by the pH meter 42.

  Further, in the pH adjusting tank 12, while being stirred by the stirring device 44, dilution water is added by a pump or the like, and the fluorine concentration is adjusted to a predetermined range (fluorine concentration adjusting step). Even if the fluorine concentration is measured by a fluorine concentration measuring means such as a fluorine concentration meter and the pump is controlled based on the measured fluorine concentration of the liquid in the pH adjusting tank 12, the amount of dilution water added can be adjusted. Good.

  The pH adjusting liquid whose pH and fluorine concentration are adjusted in the pH adjusting tank 12 is sent to the crystallization reaction tank 14 by the pump 28 through the pH adjusting liquid pipe. Next, the calcium agent is added to the crystallization reaction tank 14 through the calcium agent pipe by calcium agent addition means such as a pump (calcium agent addition step). In the crystallization reaction tank 14, the fluorine contained in the raw water reacts with the calcium agent to produce calcium fluoride crystals (crystallization reaction step). The crystallization reaction liquid is stirred by the stirring device 46.

  The crystallization treatment water with reduced fluorine generated by the crystallization reaction in the crystallization reaction tank 14 is sent to the crystallization treatment water tank 20 through the crystallization treatment water pipe.

  When calcium fluoride crystals generated by the crystallization reaction in the crystallization reaction tank 14 grow to a certain extent, at least a part of the slurry containing calcium fluoride is drawn out from the crystallization reaction tank 14 through the slurry pipe by the pump 30 ( Drawing process). The drawn crystal is in the form of a slurry, and after being sent to the slurry tank 16 and stored, it is sent to the dehydrator 18 through the slurry pipe by the pump 32, and dehydration is performed (dehydration process). The dehydrated calcium fluoride pellets are discharged out of the system by the pump 34 and reused as a raw material for hydrofluoric acid. In the slurry tank 16, the drawn slurry may be stirred by a stirring device.

  The dehydrated calcium fluoride may be washed with washing water or the like. Washing and dehydration may be repeated as necessary. Further, the drawing slurry may be neutralized before the dehydration step.

  On the other hand, the crystallization treatment water sent to the crystallization treatment water tank 20 is sent to the crystallization treatment water pH adjustment tank 22 by the pump 36 through the crystallization treatment water pipe. In the crystallization treated water pH adjusting tank 22, while being stirred by the stirring device 54, a pH adjusting agent is added by a crystallization treated water pH adjusting agent adding means such as a pump to adjust the pH within a predetermined range (crystallization). Treatment water pH adjustment step). The addition amount of the pH adjusting agent may be adjusted by controlling a pump or the like based on the pH of the liquid in the crystallization treated water pH adjusting tank 22 measured by the pH meter 52.

  The ammonia-containing pH adjusting liquid whose pH has been adjusted in the crystallization treated water pH adjusting tank 22 is sent to the ammonia distillation apparatus 24 by a pump 38 through a pH adjusting liquid pipe. In the ammonia distillation apparatus 24, ammonia is concentrated from the ammonia-containing pH adjusting solution to obtain a recovered ammonia-containing water having a predetermined concentration (for example, 20 to 25% by weight) (ammonia concentration step). It is discharged out of the system and reused.

  FIG. 2 shows a schematic configuration of another example of the recovery apparatus according to the embodiment of the present invention. The recovery device 3 in FIG. 2 includes a raw water tank 10, a pH adjustment tank 12, a crystallization reaction tank 14, a slurry storage tank 16, a dehydration device 18, a crystallization treatment water tank 20, and a crystallization treatment water pH adjustment tank. 22, an evaporation concentrating device 56 that is an ammonia concentrating means, and an ammonia distillation device 24 that is an ammonia concentrating means.

  In the recovery device 3 of FIG. 2, a pH adjusting liquid pipe from the crystallization treated water pH adjusting tank 22 is connected to the evaporation concentrating device 56 via a pump 38, and the ammonia concentrating device 24 is connected to the evaporation concentrating device 56 from the evaporation concentrating device 56. These ammonia water pipes are connected via a pump 58. The other configuration is the same as that of the recovery device 1 of FIG.

  The fluorine / ammonia-containing raw water containing fluorine and ammonia is treated in the crystallization reaction step in the same manner as in the recovery apparatus in FIG. 1 to obtain crystallization treated water. The crystallization treated water sent to the crystallization treated water tank 20 is fed to the crystallization treated water pH adjusting tank 22 by the pump 36 through the crystallization treated water piping, and stirred in the crystallization treated water pH adjusting tank 22. While being stirred by the apparatus 54, a pH adjusting agent is added by a crystallization treatment water pH adjusting agent adding means such as a pump and adjusted to a pH within a predetermined range (crystallization treatment water pH adjustment step).

  The ammonia-containing pH adjusting liquid whose pH has been adjusted in the crystallization treated water pH adjusting tank 22 is sent to the evaporation concentrator 56 by the pump 38 through the pH adjusting liquid pipe. In the evaporation concentrator 56, ammonia is evaporated and concentrated from the ammonia-containing pH adjusting solution, and is separated into ammonia-containing water and fluorine-containing water (ammonia evaporation and concentration step).

  The ammonia-containing water separated in the evaporative concentration device 56 is sent to the ammonia distillation device 24 by the pump 58 through the ammonia water pipe. Before the ammonia distillation device 24, the pH of the ammonia-containing water may be adjusted within a predetermined range in order to promote the ionization of ammonia with a pH adjuster such as an alkali such as sodium hydroxide. In the same manner as in the recovery apparatus 1 of FIG. 1, the ammonia is concentrated to obtain recovered ammonia-containing water having a predetermined concentration (for example, 20 to 25% by weight) (ammonia concentration step). About fluorine-containing water, processes, such as a coagulation sedimentation process, may be performed as needed.

  In this method, since the fluorine of the raw water is first removed by the crystallization reaction method, the concentration of fluorine in the crystallization treatment water is, for example, less than 100 mg-F / L. Therefore, as in the recovery device 1 in FIG. 56 can be omitted, and equipment costs, operating costs, and the like can be reduced. However, as in the recovery device 3 of FIG. 2, the evaporative concentration device 56 is provided in the subsequent stage of the crystallization treated water pH adjusting tank 22 and in the preceding stage of the ammonia distillation apparatus 24, so that fluorine is added to the crystallization treated water, for example. Even if 100 mg-F / L or more remains, the ammonia can be concentrated without any problem. In addition, even if raw | natural water contains ammonia, it is thought that it has little influence on a crystallization reaction.

In the recovery apparatuses 1 and 3 and the recovery method of FIGS. 1 and 2 according to the present embodiment, the raw water containing fluorine and ammonia is recovered after recovering fluorine by a crystallization reaction. For this reason, scales such as calcium fluoride and calcium carbonate may be generated due to the calcium agent added in the crystallization reaction in the subsequent evaporative concentration apparatus or ammonia distillation apparatus. Therefore,
(1) In the crystallization reaction, the addition amount of the calcium agent to be added is controlled, and the addition amount of calcium is controlled to be equal to or less than the chemical equivalent of fluorine.
Or
(2) The pH of the crystallization treated water is made high alkali (pH 12-13).
Thus, the generation of scale can be prevented. You may combine the method of (1) and (2).

  The amount of calcium added in the crystallization reaction can be not more than the chemical equivalent of fluorine, for example, preferably 0.9 to 1 times the fluorine equivalent of fluorine. By controlling the addition amount of the calcium agent within this range, it is possible to prevent scales and the like from being generated in the evaporating and concentrating device 56, the ammonia distillation device 24, and the like by leaving almost no calcium content in the crystallization water. it can. If the amount of calcium agent added is 1 or less, the total amount of fluorine in the raw water will not be calcium fluoride, and fluorine may be mixed into the crystallization water, but the fluorine concentration is preferably 100 mg / L or less. If present, the downstream evaporation concentrating device 56 can be omitted, and the downstream ammonia distillation device 24 can prevent fluorine from being mixed into the ammonia-containing water. Therefore, equipment cost, operation cost, etc. can be reduced. The adjustment of the calcium addition amount may be performed by providing a control means for controlling the addition amount of the calcium agent by the calcium agent addition means such as a pump.

  Further, the amount of calcium added is preferably more than 1 to 2 times, more preferably more than 1 to 1.2 times that of fluorine as a chemical equivalent. If the chemical equivalent of calcium is more than twice the chemical equivalent of fluorine in raw water, calcium fluoride is likely to be produced as fine particles, and calcium fluoride may be mixed into the treated water. When the amount of calcium added is more than 1 to 2 times, calcium may remain in the crystallization treated water. Therefore, as shown in FIG. A concentrating device 56 is preferably provided. Further, in the crystallization treated water pH adjusting tank 22, by adjusting the pH to the range of 12 to 13, even if calcium remains in the crystallization treated water, the scale etc. in the evaporation concentrating device 56, the ammonia distillation device 24, etc. Can be prevented.

  In this way, by controlling the amount of calcium added in the crystallization reaction within a predetermined range, or by controlling the pH of the crystallization treated water within a predetermined range, the crystallization reaction method can be used directly from the raw water containing fluorine / ammonia. Fluorine can be recovered, and ammonia can be recovered from the crystallization water.

  The raw water containing fluorine / ammonia in the present embodiment may be raw water of any origin as long as it contains fluorine and ammonia, for example, a manufacturing process of electronic products such as semiconductors and liquid crystal display devices and parts thereof, Examples include raw water discharged from other industries, but are not limited thereto.

  In the pH adjusting step of the pH adjusting tank 12, it is preferable to adjust the pH of the liquid to a range of 2-3. When the pH of the liquid is less than 2, in the fluorine recovery step by the subsequent crystallization reaction method, the proportion of fluorine in the raw water that does not become calcium fluoride increases, and the amount of soluble fluorine in the crystallization treated water increases. In some cases, the recovery rate of fluorine may decrease, and if it exceeds 3, the calcium agent becomes difficult to dissolve, and fine calcium fluoride is formed due to the rapid reaction between the undissolved calcium agent and fluorine. May be generated.

  As the pH adjuster, an acid such as hydrochloric acid or sulfuric acid or an alkali such as sodium hydroxide can be used.

  In the fluorine concentration adjusting step, the fluorine concentration of the raw water is not particularly limited, but for example, it is preferably adjusted in the range of 1,000 mg / L to 100,000 mg / L, and 5,000 mg / L to 20 It is more preferable to adjust to the range of 000 mg / L. When the fluorine concentration of the raw water is less than 5,000 mg / L, the recovery rate may decrease in the fluorine recovery step by the subsequent crystallization reaction method. Further, when the amount exceeds 20,000 mg / L, fine calcium fluoride crystals are formed in the fluorine recovery step by the subsequent crystallization reaction method, the fluorine recovery rate is lowered, and the quality of the treated water is deteriorated. There is.

In the crystallization reaction step, fluorine as a crystallization target substance can be present in the raw water in any state as long as it is crystallized by the crystallization reaction. From the viewpoint of being dissolved in raw water, the crystallization target substance is preferably in an ionized state. Examples of the state in which the substance to be crystallized is ionized include, but are not limited to, those in which F ^{− and the} like are ionized and those in which a compound containing fluorine is ionized.

  In the present embodiment, calcium agents such as calcium chloride and slaked lime are used as the crystallization agent, but the form of adding the calcium agent may be a powder state or a slurry state. The preferable aspect of addition of a calcium agent is an aspect added as a calcium agent slurry.

  In the present embodiment, a calcium solution in which slaked lime and an acid are mixed may be used as the crystallization chemical solution. The “calcium solution” in the present specification is a liquid obtained by adding an acid to slaked lime (calcium hydroxide) and having a certain range of pH. The “calcium solution” may be in a solution state in which slaked lime is completely dissolved, or may contain solid particles of slaked lime. The acid can be added to the slaked lime by any known method as long as the acid is added to the slaked lime. For example, the acid is added to the slaked lime slurry, and the acid is added to the dried slaked lime solid. Embodiments, or combinations thereof, but are not limited thereto. The preferable aspect of addition of the acid to slaked lime is an aspect which adds an acid to slaked lime slurry.

  In this specification, “slaked lime slurry” refers to a slurry formed by adding water or an aqueous solution to dry solids of slaked lime, and the water used is any source such as distilled water, purified water, tap water, etc. As the aqueous solution, an aqueous solution in which an arbitrary compound such as an acid, an alkali, or a salt thereof is added to the water can be used. In addition, the “dry slaked lime solid” in the present specification indicates a concept for the slaked lime slurry, and may be any solid, such as powder, granule, or lump, that does not form a slurry. It does not mean the anhydride.

  As the slaked lime used for preparing the calcium solution, any grade of slaked lime can be used, and it is not particularly limited. It does not specifically limit as an acid used for preparation of a calcium solution, Arbitrary acids can be used. Preferably, it is an arbitrary acid that does not contain a component that forms a sparingly soluble salt with calcium, such as hydrochloric acid, but is not limited thereto. More preferably, the acid is hydrochloric acid. One type of acid may be used, or a plurality of types of acids may be used. The concentration and addition amount of the acid used are appropriately set so that the calcium solution has a desired pH. For example, it is convenient to use slaked lime slurry that is mixed with water and circulated in the factory for the purpose of neutralization in various facilities in the factory.

  In this embodiment, the pH range of the calcium solution is preferably pH 9 or less, more preferably pH 8 or less, still more preferably pH 8 to 4, and particularly preferably pH 7 to 5. . By adjusting the pH of the calcium solution to the above range, slaked lime can be dissolved to some extent. Here, it is considered that conditions under which slaked lime slurry is completely dissolved, that is, a lower pH is better in the crystallization treatment. However, the present inventors have found that it is effective to set the pH of the calcium solution within a predetermined range in order to further reduce the concentration of the crystallization target component in the treated water obtained by the crystallization treatment. It was. That is, rather than lowering the pH of the calcium solution to less than pH 4, the concentration of fluorine in the treated water can be remarkably reduced by making the pH in the range of 8 to 4 as described above, and further in the range of pH 7 to 5. The existence of the optimum pH does not completely dissolve slaked lime fine particles by making the pH within a certain range, but by leaving a certain amount of slaked lime fine particles in the calcium solution, This is probably because the fine particles increase the reaction area of the crystallization reaction to improve the crystallization reaction efficiency and reduce the concentration of fluorine in the treated water.

  The concentration of the calcium agent in the calcium agent solution such as a calcium solution is appropriately set according to the fluorine concentration of the raw water, the treatment capacity of the crystallization reaction tank 14, and the like, and is not particularly limited.

  In this embodiment, before adding the pH adjusting solution and the calcium agent to the crystallization reaction tank 14, seed crystals may exist in the crystallization reaction tank 14 in advance, or the crystallization reaction tank 14 in advance. There may be no seed crystals inside. In order to perform a stable treatment, it is preferable that seed crystals exist in the crystallization reaction tank 14 in advance. The amount of seed crystals filled in the crystallization reaction tank 14 is not particularly limited as long as fluorine can be removed by a crystallization reaction. The concentration of fluorine in raw water, the concentration of calcium, and the crystallization reaction are not limited. It is set as appropriate according to the operating conditions of the tank 14.

  The seed crystal may be any material as long as it can precipitate a hardly soluble salt (calcium fluoride) crystal formed on the surface, and any material can be selected, for example, filtration sand, activated carbon, and zircon sand. , Including particles composed of oxides of metal elements such as garnet sand and sac random (trade name, manufactured by Nihon Cartrit Co., Ltd.), and calcium fluoride which is a precipitate by crystallization reaction However, it is not limited to these. From the viewpoint that a purer hardly soluble salt can be obtained as a pellet or the like, particles (for example, fluorite in the case of calcium fluoride) configured to contain a hardly soluble salt that is a precipitate by a crystallization reaction are preferable. The shape and particle size of the seed crystal are appropriately set according to the flow rate in the crystallization reaction tank 14, the concentrations of fluorine and calcium, and are not particularly limited.

  When the crystallization reaction tank 14 is filled with seed crystals in advance, for example, a calcium agent is added to the pH adjusting solution in the crystallization reaction tank 14, and calcium fluoride is deposited on the seed crystals in the crystallization reaction tank 14. To form a pellet to produce treated water with reduced fluorine. On the other hand, when a seed crystal does not exist in the crystallization reaction tank 14 in advance, calcium fluoride precipitated in the crystallization reaction tank 14 forms pellets by adding a calcium agent to the pH adjusting solution. And will grow. In any case, when the crystals in the crystallization reaction tank 14 grow to a certain extent, a drawing operation for drawing a part of the crystals from the crystallization reaction tank 14 and a seed crystal having a smaller particle diameter than the drawn crystals are newly added. A method is adopted in which crystals are continuously obtained by repeatedly performing a replenishment operation for replenishing.

  The crystallization reaction tank 14 may be any reaction tank that can react with fluorine in the raw water and the calcium agent to precipitate calcium fluoride, which is a hardly soluble salt, to generate treated water with reduced fluorine. The length, the inner diameter, the shape, and the like can be arbitrarily selected and are not particularly limited.

  As the crystallization reaction tank, as shown in FIG. 1, the crystallization reaction tank 14 is provided with a stirring device 46 having a stirring blade 48 and the like, and the inside of the crystallization reaction tank 14 is stirred by the stirring device 46 to flow the pellets. And a stirring type crystallization reaction tank. The stirring blade 48 may be anything as long as the contents can be stirred in the crystallization reaction tank 14, and the installation mode of the stirring blade, the size of the stirring blade, and the like are not particularly limited.

  Further, as the stirring type crystallization reaction tank 14, an inner peripheral wall is disposed so as to face the peripheral wall of the crystallization reaction tank 14, and a treatment water discharge path is formed between the inner and outer peripheral walls, and the calcium fluoride particles and the crystallization treatment are performed. It may have a separation zone that improves separation performance from water and prevents calcium fluoride particles from flowing out into the crystallization treated water. In this aspect, an aspect in which the crystallization water pipe is connected to the upper part of the crystallization water discharge path is preferable. In addition, in order to improve the separation performance of the pellets, this crystallization treated water discharge passage is provided with a buffer plate composed of a plurality of baffle plates and a plurality of rectifying plates at the entrance of the crystallization treatment water discharge passage. A configured buffer plate may be positioned. Details of this aspect are described in JP-A-2005-230735 and JP-A-2005-296888, and crystallization reaction tanks described in these patent documents can also be used in this embodiment.

  Examples of the crystallization reaction tank include a fluidized bed type crystallization reaction tank in which an upward flow is formed in the crystallization reaction tank, and pellets flow through the upward flow.

  In the present embodiment, the calcium agent is preferably added to the crystallization reaction tank 14 in the vicinity of the stirring blade 48. On the other hand, the raw water (pH adjusting liquid) can be added to the crystallization reaction tank 14 in any manner as long as the pH adjusting liquid can be added to the crystallization reaction tank 14. It can be connected to any part of the reaction vessel 14. In the case of a stirring type crystallization reaction tank as shown in FIG. 1, the pH adjusting liquid pipe is preferably connected to the upper part of the crystallization reaction tank 14 from the viewpoint of separation of precipitates and crystallization treated water. . Moreover, in FIG. 1, although the pH adjustment liquid piping and the calcium agent addition piping are each one, it is not limited to this, A plurality of these may be provided. In the case of a fluidized bed type crystallization reaction tank, from the viewpoint that an crystallization reaction can be efficiently performed by forming an upward flow in the crystallization reaction tank, It is preferably connected to the lower part of the crystallization reaction tank, particularly to the bottom part.

  In this method, the fluorine concentration of the crystallization water can be reduced by adding a calcium agent in the vicinity of the stirring blade 48. The reason for this is that by adding the calcium agent slurry in the vicinity of the stirring blade 48, the calcium agent slurry is instantly diffused, so that the rapid reaction between the calcium agent and fluorine is suppressed, and fine calcium fluoride is generated. It is thought that there is an effect that can be reduced.

  In this specification, “near” the stirring blade 48 means a region where the crystallization reaction liquid in the crystallization reaction tank 14 can be quickly diffused by the stirring flow of the stirring blade 48. For example, the calcium agent injection point is preferably provided in a region where the stirring flow rate by the stirring blade 48 is large. In particular, the height of the injection point of the calcium agent in the rotation axis direction of the stirring blade 48 is preferably a distance within two times the rotation radius of the stirring blade 48 from the rotation center of the stirring blade 48. Further, the position of the stirring blade 48 in the direction of the rotation diameter is preferably a distance within twice the rotation radius of the stirring blade 48 from the rotation center of the stirring blade 48. Furthermore, it is preferable that the center is provided in a spherical region whose center is the rotational center of the stirring blade 48 and whose radius is twice the rotational radius of the stirring blade 48. As a result, when the calcium agent is injected into the crystallization reaction tank 14, the calcium agent is immediately diffused, and the concentration thereof quickly decreases. For this reason, a calcium agent becomes easy to melt | dissolve, the rapid reaction of the calcium agent and fluorine which are not dissolved can be suppressed, and the production | generation of fine calcium fluoride can be reduced. Further, the formed calcium fluoride is less likely to be directly deposited in the liquid, and the fluorine in the liquid can be taken in carefully as crystals of a hardly soluble salt (calcium fluoride) on the granular seed crystal. Therefore, the amount of fine calcium fluoride mixed in the crystallization treated water can be extremely reduced, calcium fluoride having a large particle size can be stably obtained, and the fluorine recovery rate can be greatly improved.

  In the present embodiment, as shown in FIGS. 1 and 3, it is preferable to install a draft tube 50 below the water surface of the crystallization reaction tank 14 so that the stirring blade 48 of the stirring device 20 is positioned in the cylinder. At this time, the stirring blade 48 preferably forms a downward flow. When the draft tube 50 is thus installed, a downward flow is generated toward the lower portion of the tube, and a zone having a relatively large diffusion flow rate is formed. For this reason, it is possible to diffuse the pH adjusting solution and calcium agent more quickly, and the region where the concentration of the pH adjusting solution and calcium agent is locally concentrated contact each other, and the direct generation of calcium fluoride occurs as much as possible. It becomes possible to suppress.

  Moreover, when the draft tube 50 and the stirring blade 48 are installed as described above, an upward flow zone with a gentle flow is formed on the outer periphery of the tube. In this zone, particles are classified so that small-sized particles rise along the outer surface of the tube and re-enter from the upper end of the tube to the inside of the tube and descend, near the injection point of pH adjusting liquid, calcium agent, etc. Recirculate to the lower stirring zone. These small-sized crystals serve as nuclei to promote the crystallization reaction. For this reason, it becomes possible to stably form a calcium fluoride crystal having a large particle size, and to improve the fluorine recovery rate.

  Further, the crystal having a larger particle size due to the progress of the crystallization reaction does not rise by the upward flow at the outer periphery of the tube, sinks down and does not enter the draft tube 50 again. It can be prevented from being destroyed by the collision with the blade 48. Such an advantage also contributes to stably obtaining a calcium fluoride crystal having a large particle diameter, which in turn can contribute to an improvement in the recovery rate of fluorine.

  In order to form a zone with a relatively large stirring flow velocity at the lower part of the tube and to stably form an upward flow at the outer periphery of the tube, the stirring blade 48 should be located somewhere in the lower half of the tube in the tube. preferable. More preferably, a position slightly above the lower end of the tube is good. With such an arrangement, a zone with a high stirring flow rate is formed like a vortex near the lower end of the tube, and an upward flow is stably formed along the outer periphery of the tube. Therefore, it is possible to effectively promote the diffusion of the pH adjusting liquid and the calcium agent and the classification of the particles.

  When the draft tube 50 is provided, the injection points of the pH adjusting liquid and the calcium agent may be arranged in the cylinder of the draft tube 50 in order to quickly and effectively diffuse them on the downward flow in the draft tube 50. preferable. A more preferable position is in the cylinder of the draft tube 50 and above the stirring blade 48.

  In the present embodiment, it is preferable to deposit calcium fluoride under the conditions of pH 2 to 11 in the crystallization reaction tank 14 using a calcium agent. It is preferable to deposit calcium fluoride under conditions of pH 2 to 3 from the viewpoint of suppressing fine particle production. When pH changes with calcium fluoride production reaction, it is preferable that a pH adjusting agent can be appropriately added to the crystallization reaction tank 14. The pH at the time of calcium fluoride precipitation is determined by measuring the pH of the reaction field in the crystallization reaction tank 14 using a pH measuring means such as a pH meter, and depending on the measured pH, the pH of acid or alkali or the like. The pH can be controlled by adding a regulator to the tank. The pH meter may be installed in any part of the crystallization reaction tank 14 as long as it can monitor the pH of the reaction field of the calcium fluoride precipitation reaction. There is no particular limitation on the vicinity of the exit of the crystallization treated water from

  In addition, the reaction may be performed at a room temperature of about 10 ° C. to 30 ° C. in the crystallization reaction tank 14, but the reaction is performed at a temperature in the range of 40 ° C. to 70 ° C. in that a crystal having a high purity and a large particle size can be obtained. May be.

  In order to measure the soluble fluorine concentration in the crystallization reaction tank 14 or in the crystallization treated water, a fluorine concentration measuring means such as a fluorine concentration meter may be installed in the crystallization reaction tank 14 or the crystallization treated water pipe. . Further, in order to measure the calcium concentration such as soluble calcium in the crystallization reaction tank 14 or in the crystallization treated water, a calcium concentration measuring means such as a calcium concentration meter is installed in the crystallization reaction tank 14 or the crystallization treated water pipe. May be. The installation position of the fluorine concentration meter, the calcium concentration meter and the like in the crystallization reaction tank 14 is not particularly limited. For example, when measuring the concentration in the crystallization treated water, It can be installed near the exit.

  In the obtained crystallization treated water, for example, the fluorine concentration is usually about 500 mg-F / L or less as total fluorine including insoluble fluorine such as calcium fluoride, and usually about 50 mg-F / L or less as soluble fluorine ions. is there. The calcium concentration is pH 2-3, and is usually about 50 mg-Ca / L as soluble calcium ions, but is not limited thereto.

  Crystallized water obtained by treating raw water may be further treated in a precipitation tank. In the precipitation tank, for example, the crystallization treated water having a further reduced fluorine concentration is obtained by generating calcium fluoride by adjusting the pH to 3 to 12, preferably 4 to 11, and precipitating and removing fluorine. Obtainable.

  As the dehydrating device 18, a filter press type, a centrifugal dehydrating type, or the like is adopted. However, since the generated crystal particles have a large particle size of several tens of μm and good dehydrating properties, gravity is used in addition to centrifugal force and pressure. A filtration-type dehydrator (such as non-woven fabric) is also employed.

  Thus, by precipitating the calcium fluoride crystals of the hardly soluble salt in the crystallization reaction tank 14, the fluorine in the raw water is recovered as the hardly soluble salt crystals. In the present embodiment, the fluorine recovery rate (1- (fluorine content in treated water / fluorine content in raw water)) is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. Can be achieved. In addition, calcium fluoride having a purity of 90% to 98% can be obtained.

  In the crystallization treated water pH adjusting tank 22, it is preferable to adjust the pH to an alkaline range in order to promote the ionization of ammonia. As described above, especially when the amount of calcium added in the crystallization reaction exceeds the chemical equivalent of fluorine. It is more preferable to adjust the pH within the range of 12-13. If the pH is less than 7, the recovery rate may decrease in the subsequent ammonia concentration step. By adjusting pH to the range of 12-13, it can prevent that a scale etc. generate | occur | produce in the ammonia distillation apparatus 24 grade | etc.,. If the pH exceeds 13, a scale may be generated in the ammonia distillation apparatus 24 or the like.

  The ammonia distillation device 24 is not particularly limited as long as it concentrates ammonia from an ammonia-containing pH adjusting solution.

  The temperature in the ammonia distillation apparatus 24 is, for example, in the range of 90 ° C to 100 ° C.

  When the evaporation concentrating device 56 is used, the pH of the ammonia-containing water may be adjusted within the range of 11 to 13 in order to promote the ionization of ammonia in the previous stage of the ammonia distillation device 24.

  In the ammonia distillation apparatus 24, waste water with reduced fluorine and ammonia contents is generated. The pH of this waste water is usually in the range of 11 to 13, the water temperature is usually in the range of room temperature to 70 ° C., and the ammonia content is usually 100 mg / L or less. The fluorine concentration is, for example, usually about 500 mg-F / L or less as total fluorine including insoluble fluorine such as calcium fluoride, and usually about 50 mg-F / L or less as soluble fluorine ions. This waste water can be treated by, for example, a coagulation sedimentation method.

  The evaporative concentration device 56 is not particularly limited as long as it is capable of evaporating and concentrating ammonia from the ammonia-containing pH adjusting solution and separating it into ammonia-containing water and fluorine-containing water. For example, steam is introduced into the device. And an evaporative concentration apparatus for evaporating and concentrating ammonia under reduced pressure.

  The temperature and pressure in the evaporation concentrator 56 are not particularly limited as long as the conditions allow ammonia to evaporate.

It is a schematic structure figure showing an example of a recovery device concerning an embodiment of the present invention. It is a schematic block diagram which shows the other example of the collection | recovery apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows an example of the crystallization reaction tank in the crystallization reaction apparatus which concerns on embodiment of this invention.

Explanation of symbols

  1,3 recovery device, 10 raw water tank, 12 pH adjustment tank, 14 crystallization reaction tank, 16 slurry storage tank, 18 dehydration apparatus, 20 crystallization treatment water tank, 22 crystallization treatment water pH adjustment tank, 24 ammonia distillation apparatus, 26 28, 30, 32, 34, 36, 38, 40, 58 Pump, 42, 52 pH meter, 44, 46, 54 Stirrer, 48 Stirrer blade, 50 Draft tube, 56 Evaporative concentrator.

Claims (8)

A recovery device for recovering fluorine and ammonia from raw water containing fluorine and ammonia,
A crystallization reaction tank for adding calcium agent to the raw water to produce calcium fluoride crystals;
Calcium agent addition means for adding the calcium agent to the raw water;
Ammonia concentration means for concentrating ammonia contained in the crystallization water from which fluorine has been removed in the crystallization reaction tank;
A fluorine and ammonia recovery apparatus comprising: The fluorine and ammonia recovery device according to claim 1,
Control means for controlling the amount of calcium agent added by the calcium agent addition means,
An apparatus for recovering fluorine and ammonia, wherein a calcium agent having a chemical equivalent or less of a fluorine concentration contained in the raw water is added. The fluorine and ammonia recovery device according to claim 1,
Fluorine and ammonia recovery characterized by comprising crystallization treatment water pH adjustment agent addition means for adding a pH adjustment agent to the crystallization treatment water, and adjusting the pH of the crystallization treatment water to a range of 12-13. apparatus. The fluorine and ammonia recovery device according to any one of claims 1 to 3,
An apparatus for recovering fluorine and ammonia, comprising ammonia evaporating and concentrating means for evaporating and concentrating ammonia from the crystallization treated water in a preceding stage of the ammonia concentrating means. A recovery method for recovering fluorine and ammonia from raw water containing fluorine and ammonia,
A crystallization reaction step of adding calcium agent to the raw water to produce calcium fluoride crystals and removing fluorine;
An ammonia concentration step of concentrating ammonia contained in the crystallization treated water from which fluorine has been removed in the crystallization reaction step;
A method for recovering fluorine and ammonia. A method for recovering fluorine and ammonia according to claim 5,
In the crystallization reaction step, a calcium agent having a chemical concentration equal to or less than the chemical concentration of fluorine contained in the raw water is added. A method for recovering fluorine and ammonia according to claim 5,
A method for recovering fluorine and ammonia, comprising a crystallization treatment water pH adjustment step of adjusting the pH of the crystallization treatment water to a range of 12 to 13. A method for recovering fluorine and ammonia according to any one of claims 5 to 7,
A method for recovering fluorine and ammonia, comprising an ammonia evaporating and concentrating step of evaporating and concentrating ammonia from the crystallized water before the ammonia concentrating step.

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