JP2013141622A - Crystallization reactor - Google Patents

Crystallization reactor Download PDF

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JP2013141622A
JP2013141622A JP2012001632A JP2012001632A JP2013141622A JP 2013141622 A JP2013141622 A JP 2013141622A JP 2012001632 A JP2012001632 A JP 2012001632A JP 2012001632 A JP2012001632 A JP 2012001632A JP 2013141622 A JP2013141622 A JP 2013141622A
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crystallization reaction
solid
liquid separation
raw water
crystallization
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JP5917917B2 (en
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Toru Nakano
徹 中野
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Organo Corp
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Japan Organo Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a crystallization reactor recovering a hardly soluble salt at high recovery rate without increasing a supply amount of seed crystals.SOLUTION: This crystallization reactor includes a crystallization reaction tank 10 having a crystallization reaction part 28 adding a calcium preparation to raw water containing a crystallization objective substance to generate crystals of the hardly soluble salt. In the crystallization reaction tank 10, there is disposed an inner circumferential wall 26 facing to the outer circumferential wall of the crystallization reaction tank 10, and there is provided a solid-liquid separation part 30 forming an upward flow between the inner circumferential wall and the outer circumferential wall, and performing solid-liquid separation between the crystals and treatment water. A valve 18 provided in a raw water conduction line 16 is opened such that the water conduction time of the raw water into the crystallization reaction tank 10 becomes 1 time or above and 2 times or below a residence time in the solid-liquid separation part 30, and the valve 18 provided in the raw water conduction line 16 is closed such that the water conduction stop time of the raw water into the crystallization reaction tank 10 becomes a time of 1/4 times or above and 1/2 times or below the residence time in the solid-liquid separation part 30 after the raw water conduction.

Description

本発明は、フッ素、リン等の晶析対象物質を難溶性塩として処理する晶析反応装置の技術に関する。   The present invention relates to a technique of a crystallization reaction apparatus for treating a crystallization target substance such as fluorine or phosphorus as a hardly soluble salt.

従来、フッ化カルシウムやリン酸カルシウム等の難溶性塩を回収再利用する方法として晶析法等が用いられる。晶析法としては、例えば、フッ素含有原水中のフッ素をフッ化カルシウムとして回収する場合、反応槽にフッ素含有原水を流入させ、またカルシウム剤を注入することにより、それらを反応させ、反応槽内の種晶表面にフッ化カルシウムを析出させる方法等である。   Conventionally, a crystallization method or the like is used as a method for recovering and reusing hardly soluble salts such as calcium fluoride and calcium phosphate. As the crystallization method, for example, when fluorine in the fluorine-containing raw water is recovered as calcium fluoride, the fluorine-containing raw water is allowed to flow into the reaction tank, and the calcium agent is injected to react them, and in the reaction tank For example, calcium fluoride is precipitated on the seed crystal surface.

従来、晶析法には、フッ素含有原水等の晶析対象物質を含む原水を反応槽に上向流で供給し、反応槽内の難溶性塩の結晶を流動させながら処理する流動床式晶析反応装置(例えば、特許文献1)、反応槽内に攪拌機を設け、攪拌機の攪拌により反応槽内の難溶性塩の結晶を流動させながら処理する攪拌式晶析反応装置(例えば、特許文献2)等が用いられている。なお、通常、反応槽内の難溶性塩の結晶がある程度大きく成長すると、反応槽内から難溶性塩の結晶の一部を引き抜く引き抜き工程と、新たに種晶を補給する補給工程を繰り返し行い、連続的に難溶性塩の結晶を得る方法が採用されている。   Conventionally, in the crystallization method, the raw water containing the crystallization target material such as fluorine-containing raw water is supplied to the reaction tank in an upward flow, and the fluidized bed type crystal is processed while flowing the hardly-soluble salt crystals in the reaction tank. An agitation reaction apparatus (for example, Patent Document 1), a stirrer type crystallization reaction apparatus (for example, Patent Document 2) in which a stirrer is provided in the reaction tank, and the hardly soluble salt crystals in the reaction tank are flowed by the agitation of the agitator. ) Etc. are used. Normally, when the hardly soluble salt crystals in the reaction vessel grow to a certain extent, the drawing step of drawing a part of the hardly soluble salt crystals from the reaction vessel and the replenishment step of newly replenishing seed crystals are repeated. A method of continuously obtaining crystals of poorly soluble salts is employed.

特開2003−225680号公報JP 2003-225680 A 特開2008−73589号公報JP 2008-73589 A 特開2002−292202号公報JP 2002-292202 A 特開2009−226232号公報JP 2009-226232 A 特開2010−207755号公報JP 2010-207755 A

ところで、晶析反応装置において、高い回収率で難溶性塩を回収するためには、反応槽内の難溶性塩結晶等の表面積を高く保つこと、すなわち、反応槽内の難溶性塩結晶の粒子を細かい粒径に保つことが重要である。反応槽内の難溶性塩結晶の粒子(粒径分布)を細かく保つ方法としては、細かい粒径分布を有する種晶を多く槽内に補給することが考えられるが、種晶の補給量が増加する分だけ処理コストが上昇してしまう。   By the way, in the crystallization reaction apparatus, in order to recover the hardly soluble salt at a high recovery rate, the surface area of the hardly soluble salt crystal or the like in the reaction tank is kept high, that is, the particles of the hardly soluble salt crystal in the reaction tank. It is important to keep the particle size fine. As a method of keeping the particles (particle size distribution) of the sparingly soluble salt crystals in the reaction tank fine, it is conceivable to supply a large amount of seed crystals having a fine particle size distribution in the tank, but the amount of seed crystals supplied increases. As a result, the processing cost increases.

そこで、本発明の目的は、種晶の補給量を増加することなく、高い回収率で難溶性塩を回収することができる晶析反応装置を提供することである。   Accordingly, an object of the present invention is to provide a crystallization reaction apparatus capable of recovering a hardly soluble salt at a high recovery rate without increasing the replenishment amount of seed crystals.

本発明の晶析反応装置は、攪拌翼を有する攪拌手段を備え、晶析対象物質を含む原水にカルシウム剤を添加して難溶性塩の結晶を生成させる晶析反応部を有する晶析反応槽と、前記晶析反応部へ前記原水を通水する通水手段と、を備え、前記晶析反応槽内には、前記晶析反応槽の外周壁に対向する内周壁を配置し、内外周壁間で上向流を形成して、前記結晶と処理水との固液分離を行う固液分離部が設けられ、前記通水手段は、前記晶析反応部への前記原水の通水を間欠的に行う。   The crystallization reaction apparatus of the present invention comprises a crystallization reaction tank having a crystallization reaction section that includes a stirring means having a stirring blade and generates a hardly soluble salt crystal by adding a calcium agent to raw water containing a crystallization target substance. And a water passage means for passing the raw water to the crystallization reaction part, and an inner peripheral wall facing the outer peripheral wall of the crystallization reaction tank is disposed in the crystallization reaction tank, and the inner and outer peripheral walls are arranged. A solid-liquid separation unit that forms an upward flow between the crystals and the treated water is provided, and the water flow means intermittently passes the raw water through the crystallization reaction unit. Do it.

前記晶析反応装置において、前記通水手段による間欠通水時の前記原水の通水時間は、前記固液分離部における滞留時間の1倍以上2倍以下であり、前記通水手段による間欠通水時の前記原水の通水停止時間は、前記固液分離部における滞留時間の1/4倍以上1/2倍以下の時間であることが好ましい。   In the crystallization reaction apparatus, the flow time of the raw water at the time of intermittent water flow by the water flow means is 1 to 2 times the residence time in the solid-liquid separation unit, and the intermittent water flow by the water flow means. It is preferable that the flow stop time of the raw water at the time of water is not less than 1/4 times and not more than 1/2 times the residence time in the solid-liquid separation unit.

前記晶析反応装置において、前記固液分離部が設けられている前記晶析反応槽の外周壁に、前記処理水を排出する排出口が形成され、前記内周壁の上端は、前記排出口と同じ高さ、又は前記処理水の一部が前記排出口から排出可能な範囲で前記排出口より低い位置にあり、前記固液分離部内の処理水の一部は、前記内周壁を越えて前記晶析反応部に返送されることが好ましい。   In the crystallization reaction apparatus, a discharge port for discharging the treated water is formed on an outer peripheral wall of the crystallization reaction tank provided with the solid-liquid separation unit, and an upper end of the inner peripheral wall is connected to the discharge port. The same height or a part of the treated water is in a position lower than the outlet in a range where the part of the treated water can be discharged from the outlet, and a part of the treated water in the solid-liquid separation part exceeds the inner peripheral wall and It is preferably returned to the crystallization reaction section.

本発明によれば、種晶の補給量を増加することなく、高い回収率で難溶性塩を回収することができる。   According to the present invention, a hardly soluble salt can be recovered at a high recovery rate without increasing the replenishment amount of seed crystals.

本発明の実施形態に係る晶析反応装置の一例を示す模式図である。It is a schematic diagram which shows an example of the crystallization reaction apparatus which concerns on embodiment of this invention. 参考例の晶析反応装置の構成の一例を示す模式図である。It is a schematic diagram which shows an example of a structure of the crystallization reaction apparatus of a reference example. 実施例1の晶析反応部内の結晶の粒径分布を示す図である。2 is a graph showing the particle size distribution of crystals in the crystallization reaction part of Example 1. FIG. 実施例2の晶析反応部内の結晶の粒径分布を示す図である。4 is a graph showing a particle size distribution of crystals in a crystallization reaction part of Example 2. FIG. 実施例3の晶析反応部内の結晶の粒径分布を示す図である。6 is a graph showing the particle size distribution of crystals in the crystallization reaction part of Example 3. FIG. 実施例4の晶析反応部内の結晶の粒径分布を示す図である。6 is a graph showing a particle size distribution of crystals in a crystallization reaction part of Example 4. FIG. 比較例1の晶析反応部内の結晶の粒径分布を示す図である。2 is a graph showing a particle size distribution of crystals in a crystallization reaction part of Comparative Example 1. FIG. 比較例2の晶析反応部内の結晶の粒径分布を示す図である。6 is a graph showing a particle size distribution of crystals in a crystallization reaction part of Comparative Example 2. FIG. 比較例3の晶析反応部内の結晶の粒径分布を示す図である。6 is a graph showing a particle size distribution of crystals in a crystallization reaction part of Comparative Example 3. FIG.

本発明の実施の形態について以下説明する。本実施形態は本発明を実施する一例であって、本発明は本実施形態に限定されるものではない。   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.

図1は、本発明の実施形態に係る晶析反応装置の一例を示す模式図である。図1に示すように、晶析反応装置1は、晶析反応槽10、種晶サイロ12、カルシウム剤を晶析反応槽10へ添加する添加手段の一例としてのカルシウム剤添加ライン14、原水を晶析反応槽10へ流入させる流入手段の一例としての原水通水ライン16及びバルブ18、種晶添加ライン20、処理水排出ライン22、難溶性塩排出ライン24、を備えている。   FIG. 1 is a schematic diagram showing an example of a crystallization reaction apparatus according to an embodiment of the present invention. As shown in FIG. 1, the crystallization reaction apparatus 1 includes a crystallization reaction tank 10, a seed crystal silo 12, a calcium agent addition line 14 as an example of addition means for adding a calcium agent to the crystallization reaction tank 10, and raw water. As an example of inflow means for flowing into the crystallization reaction tank 10, a raw water passage line 16 and a valve 18, a seed crystal addition line 20, a treated water discharge line 22, and a hardly soluble salt discharge line 24 are provided.

晶析反応槽10には、原水貯槽(不図示)からの原水通水ライン16、カルシウム剤貯槽(不図示)からのカルシウム剤添加ライン14が接続されている。また、種晶サイロ12と晶析反応槽10との間は、種晶添加ライン20が接続されている。さらに、晶析反応槽10の処理水排出口21には、処理水排出ライン22が接続され、晶析反応槽10の難溶性塩排出口には、難溶性塩排出ライン24が接続されている。   The crystallization reaction tank 10 is connected with a raw water passage line 16 from a raw water storage tank (not shown) and a calcium agent addition line 14 from a calcium agent storage tank (not shown). A seed crystal addition line 20 is connected between the seed crystal silo 12 and the crystallization reaction tank 10. Further, a treated water discharge line 22 is connected to the treated water discharge port 21 of the crystallization reaction tank 10, and a hardly soluble salt discharge line 24 is connected to the hardly soluble salt discharge port of the crystallization reaction tank 10. .

晶析反応槽10内には、難溶性塩の結晶を生成させる晶析反応部28と、難溶性塩結晶と処理水との固液分離を行う固液分離部30とが設けられている。晶析反応槽10内には、晶析反応槽10の外周壁に対向する内周壁26が設けられており、この外周壁と内周壁26間を固液分離部30としている。本実施形態の内周壁26は晶析反応槽10の外周壁の所定区間に設けられているが、内周壁26は外周壁の全周にわたって設けられていてもよい。   In the crystallization reaction tank 10, there are provided a crystallization reaction section 28 for generating a hardly soluble salt crystal and a solid / liquid separation section 30 for performing a solid / liquid separation between the hardly soluble salt crystal and the treated water. In the crystallization reaction tank 10, an inner peripheral wall 26 facing the outer peripheral wall of the crystallization reaction tank 10 is provided, and a solid-liquid separation unit 30 is formed between the outer peripheral wall and the inner peripheral wall 26. Although the inner peripheral wall 26 of this embodiment is provided in the predetermined area of the outer peripheral wall of the crystallization reaction tank 10, the inner peripheral wall 26 may be provided over the perimeter of the outer peripheral wall.

晶析反応部28と固液分離部30とは内周壁26により区画されており、内周壁26の下部には、晶析反応部28と固液分離とが連通する連通口32が形成されている。また、前述した処理水排出口21は、固液分離部30が形成されている晶析反応槽10の外周壁に設けられており、この処理水排出口21に処理水排出ライン22が接続されている。   The crystallization reaction part 28 and the solid-liquid separation part 30 are partitioned by an inner peripheral wall 26, and a communication port 32 is formed in the lower part of the inner peripheral wall 26 for communication between the crystallization reaction part 28 and the solid-liquid separation. Yes. Further, the treated water discharge port 21 described above is provided on the outer peripheral wall of the crystallization reaction tank 10 where the solid-liquid separation unit 30 is formed, and the treated water discharge line 22 is connected to the treated water discharge port 21. ing.

晶析反応槽10の晶析反応部28には、ドラフトチューブ36、晶析反応部28内の流体を撹拌する攪拌手段の一例としての攪拌装置34を備える。攪拌装置34は攪拌翼38を備え、攪拌翼38は、ドラフトチューブ36内に配置され、撹拌軸を介して伝達されるモータが発生する回転力によって回転する。   The crystallization reaction section 28 of the crystallization reaction tank 10 includes a draft tube 36 and a stirring device 34 as an example of a stirring means for stirring the fluid in the crystallization reaction section 28. The stirring device 34 includes a stirring blade 38, and the stirring blade 38 is disposed in the draft tube 36 and is rotated by a rotational force generated by a motor that is transmitted through the stirring shaft.

本実施形態に係る晶析反応装置1の動作について説明する。   The operation of the crystallization reaction apparatus 1 according to this embodiment will be described.

まず、原水通水ライン16のバルブ18を開放し、原水通水ライン16を通して、フッ素、リン等の晶析対象物質を含有する原水(以下、単に「原水」と呼ぶ場合がある。)を晶析反応槽10の晶析反応部28に通水する。また、カルシウム剤添加ライン14を通して、カルシウム剤を晶析反応部28に添加する。さらに、モータにより種晶サイロ12中の種晶が種晶添加ライン20を通して晶析反応部28に添加されることが好ましい。   First, the valve 18 of the raw water passage line 16 is opened, and the raw water containing the substance to be crystallized such as fluorine and phosphorus (hereinafter sometimes simply referred to as “raw water”) is crystallized through the raw water passage line 16. Water is passed through the crystallization reaction section 28 of the crystallization reaction tank 10. Further, the calcium agent is added to the crystallization reaction part 28 through the calcium agent addition line 14. Further, the seed crystal in the seed crystal silo 12 is preferably added to the crystallization reaction unit 28 through the seed crystal addition line 20 by a motor.

そして、晶析反応槽10の晶析反応部28において、原水に含まれるフッ素、リン等の晶析対象物質がカルシウム剤と反応して、フッ化カルシウム、リン酸カルシウム(難溶性カルシウム塩)が生成して、種晶表面に析出し、難溶性塩(難溶性カルシウム塩)の結晶が生成する。   And in the crystallization reaction part 28 of the crystallization reaction tank 10, the crystallization target substances such as fluorine and phosphorus contained in the raw water react with the calcium agent to produce calcium fluoride and calcium phosphate (slightly soluble calcium salt). As a result, it precipitates on the surface of the seed crystal and forms a hardly soluble salt (slightly soluble calcium salt) crystal.

晶析反応部28内で生成したフッ化カルシウム、リン酸カルシウム等の難溶性カルシウム塩の結晶は、例えば定期的に難溶性塩排出ライン24から引き抜かれ、系外へ排出される。難溶性カルシウム塩の結晶の引き抜き方法は、特に制限されるものではないが、チューブポンプ等のスラリ用ポンプを用いて、晶析反応槽10から難溶性カルシウム塩の結晶を引き抜く方法でも良いし、図1に示すように難溶性塩排出ライン24にバルブ24aを取り付け、単に重力によって晶析反応槽10から難溶性カルシウム塩の結晶を引き抜く方法でもよい。   Crystals of sparingly soluble calcium salts such as calcium fluoride and calcium phosphate generated in the crystallization reaction unit 28 are, for example, periodically pulled out from the sparingly soluble salt discharge line 24 and discharged out of the system. The method of extracting the hardly soluble calcium salt crystal is not particularly limited, but may be a method of drawing the hardly soluble calcium salt crystal from the crystallization reaction tank 10 using a slurry pump such as a tube pump, As shown in FIG. 1, a method may be used in which a valve 24a is attached to the hardly soluble salt discharge line 24 and the crystal of the hardly soluble calcium salt is simply pulled out from the crystallization reaction tank 10 by gravity.

一方、晶析反応部28内の晶析反応後の処理水は、連通口32から固液分離部30に流入する。この際、処理水と共に、難溶性塩の結晶の一部が固液分離部30に流入するが、固液分離部30では、晶析反応後の処理水が上向流を形成して固液分離部30を通過し、処理水中に含まれる難溶性塩結晶と処理水とが固液分離される。固液分離された処理水は、処理水排出ライン22を通して、本実施形態の最終処理水として系外に排出される。   On the other hand, the treated water after the crystallization reaction in the crystallization reaction unit 28 flows into the solid-liquid separation unit 30 from the communication port 32. At this time, some of the crystals of the hardly soluble salt flow into the solid-liquid separation unit 30 together with the treated water. In the solid-liquid separation unit 30, the treated water after the crystallization reaction forms an upward flow to form a solid-liquid solution. The hardly soluble salt crystal and the treated water contained in the treated water are solid-liquid separated after passing through the separation unit 30. The treated water subjected to the solid-liquid separation is discharged out of the system through the treated water discharge line 22 as the final treated water of the present embodiment.

ここで、晶析反応部28への原水の通水を継続すると、晶析反応部28内の難溶性カルシウム塩の結晶(種晶表面に析出できなかった難溶性カルシウム塩結晶等も含む)や種晶サイロ12から補給された種晶等の一部は、晶析反応後の処理水と共に固液分離部30に流れたまま、固液分離部30内に溜められる。これらの結晶や種晶のうち特に粒径の細かい結晶や種晶は固液分離部30に流れやすい。したがって、晶析反応槽10への原水の通水を継続すると、晶析反応部28内に粒径の細かい結晶や種晶を保持することが困難となるため、晶析反応部28内に存在する結晶や種晶の単位重量当たりの表面積を大きく保つことができずに、難溶性カルシウム塩の結晶の回収率が低下してしまう。   Here, if the raw water flow to the crystallization reaction part 28 is continued, crystals of the hardly soluble calcium salt in the crystallization reaction part 28 (including the hardly soluble calcium salt crystals that could not be precipitated on the seed crystal surface), Part of seed crystals and the like replenished from the seed crystal silo 12 is stored in the solid-liquid separation unit 30 while flowing into the solid-liquid separation unit 30 together with the treated water after the crystallization reaction. Among these crystals and seed crystals, crystals and seed crystals having a particularly small particle diameter are likely to flow to the solid-liquid separation unit 30. Accordingly, if the raw water flow into the crystallization reaction tank 10 is continued, it becomes difficult to maintain crystals and seed crystals having a small particle size in the crystallization reaction unit 28, and therefore, the crystallization reaction unit 28 exists in the crystallization reaction unit 28. The surface area per unit weight of the crystal or seed crystal to be kept cannot be kept large, and the recovery rate of the hardly soluble calcium salt crystal is lowered.

そこで、本実施形態では、晶析反応部28への原水の通水を間欠的に行う、すなわち通水と通水停止を繰り返し行うことにより、難溶性カルシウム塩の結晶の回収率を向上させている。まず、本実施形態では、晶析反応部28への原水の通水を行い、難溶性カルシウム塩の結晶を得る。この際、得られる難溶性カルシウム塩の結晶(種晶も含む)の一部、特に細かい粒径の難溶性カルシウム塩の結晶は、前述したように固液分離部30内に流れ、固液分離部30内に溜められる。しかし、本実施形態では、晶析反応槽10への原水の通水停止を行い、固液分離部30内に滞留した細かい粒径の難溶性塩の結晶等を自然沈降させ、少なくともその結晶等の一部を晶析反応部28に戻す操作を行う。このように原水の通水を間欠的に行うと、次の原水の通水の開始の際には、細かい粒径の難溶性カルシウム塩の結晶等が晶析反応部28内に保持されているため、種晶サイロ12から種晶の補給量を増やすことなく、晶析反応部28内の難溶性カルシウム塩の結晶等の単位重量当たりの表面積が大きくなり、難溶性塩結晶の回収率を向上させることができる。本実施形態における原水の通水時間及び通水停止時間は、例えば、難溶性カルシウム塩の結晶を生成させる時間及び固液分離部30内に滞留する結晶等を自然沈降させる時間を確保するために適宜設定されるものであるが、原水の通水時間及び通水停止時間は以下の条件に設定されることが好ましい。   Thus, in the present embodiment, the raw water is intermittently passed through the crystallization reaction unit 28, that is, the water recovery and the water supply stop are repeated, thereby improving the recovery rate of the hardly soluble calcium salt crystals. Yes. First, in the present embodiment, raw water is passed through the crystallization reaction unit 28 to obtain a hardly soluble calcium salt crystal. At this time, a part of the crystals (including seed crystals) of the poorly soluble calcium salt obtained, particularly the crystals of the poorly soluble calcium salt having a fine particle diameter, flow into the solid-liquid separation part 30 as described above, and are separated into solid and liquid. It is stored in the part 30. However, in the present embodiment, the flow of the raw water to the crystallization reaction tank 10 is stopped, and crystals of a slightly soluble salt having a fine particle size staying in the solid-liquid separation unit 30 are naturally precipitated, and at least the crystals etc. An operation is performed to return a part of this to the crystallization reaction unit 28. When the raw water is intermittently passed in this way, crystals of a slightly soluble calcium salt having a fine particle size are retained in the crystallization reaction unit 28 at the start of the next raw water flow. Therefore, without increasing the replenishment amount of the seed crystal from the seed crystal silo 12, the surface area per unit weight of the hardly soluble calcium salt crystal in the crystallization reaction unit 28 is increased, and the recovery rate of the hardly soluble salt crystal is improved. Can be made. The flow time and flow stop time of the raw water in the present embodiment are, for example, to ensure the time for generating crystals of sparingly soluble calcium salt and the time for naturally sedimenting the crystals etc. staying in the solid-liquid separation unit 30. Although appropriately set, it is preferable to set the water passage time and the water passage stop time under the following conditions.

まず、原水通水ライン16のバルブ18を開放し、晶析反応部28への原水の通水時間を固液分離部30における滞留時間の1倍以上2倍以下の範囲で、原水を晶析反応部28へ通水する。その後、原水通水ライン16のバルブ18を閉じ、晶析反応部28への原水の通水停止時間を固液分離部30における滞留時間の1/4倍以上1/2倍以下の範囲で、晶析反応部28への原水の通水を停止する。これにより、細かい粒径の難溶性カルシウム塩の結晶等が晶析反応部28内に沈降する時間が十分に確保され、晶析反応部28内で保持されるため、難溶性カルシウム塩の結晶の回収率をより向上させることができる。晶析反応部28内には、主に50μm以下の細かい粒径の結晶がより多く保持されるため、難溶性カルシウム塩の結晶の回収率をより向上させることができる。仮に、装置内の粒子が全て同じ大きさだとすると、粒子1個当たりの表面積は、粒子径の2乗に比例して大きくなるが、単位重量当たりの粒子個数は、粒子径の3乗に反比例して大きくなる。そのため、単位重量当たりの表面積は、(粒子径)/(粒子径)=粒子径に反比例して大きくなるため、本実施形態の条件で原水の通水及び停止を行い、粒径の小さい難溶性カルシウム塩の結晶等を晶析反応部28内により多く存在させることにより、晶析反応部28内の結晶の単位重量当たりの表面積は飛躍的に上昇し、難溶性塩結晶の回収率を大幅に向上させることができる。ここで、固液分離部30おける滞留時間とは、晶析反応槽10へ流入する原水の滞留時間であり、固液分離部30の容積を晶析反応槽10へ流入する原水の流入量で割った値で表される。なお、本実施形態のバルブ18の開閉は手動であっても自動であってもよい。 First, the valve 18 of the raw water flow line 16 is opened, and the raw water is crystallized in a range where the flow time of the raw water to the crystallization reaction unit 28 is 1 to 2 times the residence time in the solid-liquid separation unit 30. Water is passed to the reaction unit 28. Thereafter, the valve 18 of the raw water flow line 16 is closed, and the water stoppage time of the raw water to the crystallization reaction unit 28 is in the range of 1/4 to 1/2 times the residence time in the solid-liquid separation unit 30, The flow of the raw water to the crystallization reaction unit 28 is stopped. As a result, a sufficient time for the crystals of the slightly soluble calcium salt having a small particle size to settle in the crystallization reaction part 28 is secured and retained in the crystallization reaction part 28. The recovery rate can be further improved. Since a larger number of crystals having a fine particle size of 50 μm or less are mainly retained in the crystallization reaction part 28, the recovery rate of the hardly soluble calcium salt crystals can be further improved. If all the particles in the device are the same size, the surface area per particle increases in proportion to the square of the particle diameter, but the number of particles per unit weight is inversely proportional to the cube of the particle diameter. Become bigger. Therefore, since the surface area per unit weight increases in inverse proportion to (particle diameter) 3 / (particle diameter) 2 = particle diameter, the raw water is passed and stopped under the conditions of this embodiment, and the particle diameter is small By causing more crystals of hardly soluble calcium salt or the like to exist in the crystallization reaction portion 28, the surface area per unit weight of the crystals in the crystallization reaction portion 28 is dramatically increased, and the recovery rate of the hardly soluble salt crystals is increased. It can be greatly improved. Here, the residence time in the solid-liquid separation unit 30 is the residence time of raw water flowing into the crystallization reaction tank 10, and the inflow amount of raw water flowing into the crystallization reaction tank 10 from the volume of the solid-liquid separation unit 30. It is expressed as a divided value. Note that the valve 18 of the present embodiment may be opened or closed manually or automatically.

晶析反応部28への原水の通水時間が固液分離部30における滞留時間の1倍未満であると、通水時間が短く、装置で処理できる水量が少なくなり、難溶性カルシウム塩の結晶を回収する効率が悪くなる場合がある。また、晶析反応部28への原水の通水時間が固液分離部30における滞留時間の2倍超であると、細かい粒径の難溶性カルシウム塩の結晶等が系外へ多く排出され、晶析反応部28内に細かい粒径の結晶を十分に保持することができない場合があり、難溶性カルシウム塩の結晶の回収率を向上させることが困難となる。晶析反応部28への原水の通水停止時間が固液分離部30における滞留時間の1/4倍未満であると、固液分離部30内に滞留している粒径の細かい結晶が晶析反応部28内へ戻りきれず、晶析反応部28内に細かい粒径の結晶を十分に保持することができない場合があり、難溶性カルシウム塩の結晶の回収率を向上させることが困難となる。また、晶析反応部28への原水の通水停止時間が固液分離部30における滞留時間の1/2倍超であると、停止時間が長く、装置で処理できる水量が少なくなり、難溶性カルシウム塩の結晶を回収する効率が悪くなる場合がある。   When the flow time of raw water to the crystallization reaction section 28 is less than 1 time of the residence time in the solid-liquid separation section 30, the flow time is short, the amount of water that can be processed by the apparatus is reduced, and crystals of sparingly soluble calcium salts are obtained. There is a case where the efficiency of recovering is deteriorated. Further, if the flow time of the raw water to the crystallization reaction unit 28 is more than twice the residence time in the solid-liquid separation unit 30, a large amount of finely-spared crystals of insoluble calcium salt are discharged out of the system, Crystals with a fine particle size may not be sufficiently retained in the crystallization reaction unit 28, and it becomes difficult to improve the recovery rate of the hardly soluble calcium salt crystals. When the flow stoppage time of the raw water to the crystallization reaction unit 28 is less than ¼ times the residence time in the solid-liquid separation unit 30, fine crystals having a small particle size staying in the solid-liquid separation unit 30 are crystallized. It is difficult to improve the recovery rate of the hardly soluble calcium salt crystals because it may not be possible to fully return to the crystallization reaction part 28 and the fine crystallization crystals may not be sufficiently retained in the crystallization reaction part 28. Become. In addition, when the water passage stop time of the raw water to the crystallization reaction unit 28 is more than ½ times the residence time in the solid-liquid separation unit 30, the stop time is long, and the amount of water that can be treated by the apparatus decreases, resulting in poor solubility. The efficiency of collecting calcium salt crystals may deteriorate.

次に、固液分離部30で処理水と分離されず、処理水と共に通過してしまう微細な難溶性カルシウム塩の結晶等について考える。   Next, let us consider fine, insoluble calcium salt crystals that are not separated from the treated water by the solid-liquid separation unit 30 and pass along with the treated water.

例えば、補給した種晶のうち微細すぎる粒径のものや、種晶表面に析出できなかった難溶性カルシウム塩の結晶等の微細粒子は、固液分離部30で分離しきれず、上向流によって処理水と共に流出し、系外に排出されてしまう。一般的に、この排出された微細粒子は、回収されずに汚泥として処分されてしまうが、この微細粒子を固液分離可能な粒径にまで成長させることができれば、発生汚泥量を削減することができ、かつ種晶の補給量も削減することが可能となる。従来、処理水と共に流出する微細粒子を固液分離可能な粒径にまで成長させるために、処理水中の微細粒子を晶析反応部に戻す方法が提案されている(例えば、特開2002−292202、特開2009−226232、特開2010−207755)。   For example, fine particles such as those of a replenished seed crystal having a too small particle diameter or crystals of a hardly soluble calcium salt that could not be precipitated on the surface of the seed crystal cannot be separated by the solid-liquid separation unit 30, and are caused by upward flow. It flows out with treated water and is discharged out of the system. In general, the discharged fine particles are disposed of as sludge without being recovered, but if the fine particles can be grown to a particle size capable of solid-liquid separation, the amount of generated sludge can be reduced. It is possible to reduce the replenishment amount of seed crystals. Conventionally, a method for returning fine particles in the treated water to the crystallization reaction part has been proposed in order to grow the fine particles flowing out together with the treated water to a particle size capable of solid-liquid separation (for example, JP-A-2002-292202). JP 2009-226232 A, JP 2010-207755 A).

本実施形態では、図1に示す晶析反応装置1のように、固液分離部30と晶析反応部28とを隔てる内周壁26の上端が、処理水排出口21と同じ高さか、または処理水の一部が処理水排出口21から排出可能な範囲で処理水排出口21より低い位置に設定する。   In the present embodiment, as in the crystallization reaction apparatus 1 shown in FIG. 1, the upper end of the inner peripheral wall 26 that separates the solid-liquid separation unit 30 and the crystallization reaction unit 28 is the same height as the treated water discharge port 21 or A part of the treated water is set at a position lower than the treated water discharge port 21 within a range where the treated water can be discharged from the treated water discharge port 21.

一般的に、晶析反応部28の水位は処理水排出口21と同じ高さであるため、内周壁26の上端を処理水排出口21と同じ高さかその高さより低くしてしまうと、晶析反応部28内の難溶性カルシウム塩の結晶等が内周壁26を越えて固液分離部30側に越流してしまう。しかし、本実施形態の晶析反応装置1においては、晶析反応部28内の結晶の表面積を高く維持するために、結晶濃度が高い状態で運転するため、晶析反応部28内の流体の単位体積当たりの比重は固液分離部30内の流体の比重より高くなり易い。このように、晶析反応部28と固液分離部30に比重差が生じると、晶析反応部28と固液分離部30に水位差が生じる。この水位差は、装置の大きさ等によって数mの水位差となる場合がある。したがって、本実施形態のように、内周壁26の上端の位置を上記のように下げても、晶析反応部28内の原水が固液分離部30に越流することはなく、固液分離部30内の処理水の一部を晶析反応部28に戻せることになる。これにより、処理水中に含まれる微細粒子(難溶性カルシウム塩の結晶や種晶等)を、何の動力機器も使うことなく、晶析反応部28に返送することが可能となるため、より晶析反応部28内の難溶性カルシウム塩の結晶や種晶の粒径分布を細かく維持することが可能となる。その結果、更に難溶性カルシウム塩の結晶の回収率を向上させることが可能となる。   Generally, since the water level of the crystallization reaction unit 28 is the same height as the treated water discharge port 21, if the upper end of the inner peripheral wall 26 is made the same height as the treated water discharge port 21 or lower than that height, Crystals or the like of the hardly soluble calcium salt in the precipitation reaction part 28 will flow over the inner peripheral wall 26 and to the solid-liquid separation part 30 side. However, in the crystallization reaction apparatus 1 of the present embodiment, in order to keep the surface area of the crystals in the crystallization reaction unit 28 high, the crystallization reaction unit 1 is operated in a state where the crystal concentration is high. The specific gravity per unit volume tends to be higher than the specific gravity of the fluid in the solid-liquid separation unit 30. Thus, when a specific gravity difference occurs between the crystallization reaction unit 28 and the solid-liquid separation unit 30, a water level difference occurs between the crystallization reaction unit 28 and the solid-liquid separation unit 30. This water level difference may be a water level difference of several meters depending on the size of the apparatus. Therefore, as in this embodiment, even if the position of the upper end of the inner peripheral wall 26 is lowered as described above, the raw water in the crystallization reaction unit 28 does not flow over to the solid-liquid separation unit 30, and the solid-liquid separation is performed. A part of the treated water in the part 30 can be returned to the crystallization reaction part 28. This makes it possible to return fine particles (refractory calcium salt crystals, seed crystals, etc.) contained in the treated water to the crystallization reaction unit 28 without using any power equipment. The particle size distribution of the hardly soluble calcium salt crystals and seed crystals in the precipitation reaction portion 28 can be maintained finely. As a result, it becomes possible to further improve the recovery rate of crystals of the hardly soluble calcium salt.

次に、本実施形態の晶析反応装置1のその他の条件等について説明する。   Next, other conditions of the crystallization reaction apparatus 1 of the present embodiment will be described.

本実施形態において、カルシウム剤及び原水の晶析反応部28への添加(注入点)は、攪拌翼38の近傍に行われることが好ましい。カルシウム剤及び原水を攪拌翼38の近傍に添加することにより、カルシウム剤及び原水は、晶析反応部28へ注入されると直ちに拡散せしめられ、カルシウム剤濃度やフッ素、リン等の晶析対象物質濃度が素早く低下する。このため、形成された難溶性塩が液中に直接析出することが少なくなり、晶析反応部28内の種晶上の難溶塩結晶として液中の晶析対象物質(フッ素、リン等)をじっくり取り込むことができる。   In the present embodiment, the addition (injection point) of the calcium agent and raw water to the crystallization reaction unit 28 is preferably performed in the vicinity of the stirring blade 38. By adding the calcium agent and the raw water in the vicinity of the stirring blade 38, the calcium agent and the raw water are immediately diffused when injected into the crystallization reaction unit 28, and the crystallization target substances such as the calcium agent concentration, fluorine, phosphorus, etc. Concentration drops quickly. For this reason, the formed hardly soluble salt is less likely to be directly deposited in the liquid, and the crystallization target substance (fluorine, phosphorus, etc.) in the liquid as the hardly soluble salt crystal on the seed crystal in the crystallization reaction unit 28. Can be captured carefully.

本実施形態においては、筒内に攪拌装置34の攪拌翼38が位置するようにドラフトチューブ36を設置することが好ましい。このとき、攪拌翼38は下降流を形成するものであることが好ましい。このようにドラフトチューブ36を設置すると、チューブ下部に向けて下降流が生じ、拡散流速が比較的大きいゾーンが形成される。このため、原水やカルシウム剤等をより素早く拡散させることができ、原水やカルシウム剤の濃度が局所的に濃い領域同士が接触せずに、難溶性カルシウム塩粒子の直接生成が抑制される。   In the present embodiment, it is preferable to install the draft tube 36 so that the stirring blade 38 of the stirring device 34 is positioned in the cylinder. At this time, the stirring blade 38 preferably forms a downward flow. When the draft tube 36 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, raw | natural water, a calcium agent, etc. can be diffused more rapidly, and the direct production | generation of a sparingly soluble calcium salt particle | grain is suppressed, without the area | regions where the density | concentration of raw | natural water or a calcium agent is locally concentrated.

また、上記のようにドラフトチューブ36および攪拌翼38を設置すると、チューブ外周部には流れのゆるやかな上向流ゾーンが形成される。このゾーンでは、粒子が分級されて小粒径の粒子はチューブ外側面に沿って上昇すると共に、チューブ上端からチューブ内部に再侵入して下降し、原水やカルシウム剤等の注入点付近やその下部の撹拌ゾーンへと再循環する。これら小粒径の結晶が核となって晶析反応を促進せしめるため、難溶性塩結晶の回収率を向上させることができる。   Moreover, when the draft tube 36 and the stirring blade 38 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, the particles are classified and small 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. Recirculate to the stirring zone. Since these small-sized crystals serve as nuclei to promote the crystallization reaction, the recovery rate of the hardly soluble salt crystals can be improved.

さらに、晶析反応が進んで粒径が大きくなった結晶は、チューブ外周部の上向流によっては上昇せず、下に沈んで再びドラフトチューブ36内には入り込まないため、成長した結晶が攪拌翼38との衝突により破壊されてしまうことを防止することができるため、難溶性塩結晶の回収率の向上に寄与することができる。   Further, the crystal having a larger particle size due to the progress of the crystallization reaction does not rise due to the upward flow at the outer periphery of the tube, sinks down and does not enter the draft tube 36 again. Since it can prevent being destroyed by the collision with the blade 38, it can contribute to the improvement of the recovery rate of the hardly soluble salt crystal.

本実施形態では、晶析反応部28に酸又はアルカリを添加し、晶析反応部28における晶析反応液のpHを0.8〜3の範囲とすることが好ましく、1〜1.5の範囲とすることがより好ましい。酸又はアルカリを添加して晶析反応部28のpHを0.8〜3の範囲で運転することにより、例えば、処理水のフッ素、リン等の晶析対象物質濃度を低減させることができる。   In this embodiment, it is preferable to add acid or alkali to the crystallization reaction part 28, and to make pH of the crystallization reaction liquid in the crystallization reaction part 28 into the range of 0.8-3, It is more preferable to set the range. By adding an acid or an alkali and operating the pH of the crystallization reaction part 28 in the range of 0.8 to 3, for example, the concentration of a substance to be crystallized such as fluorine or phosphorus in the treated water can be reduced.

本実施形態におけるフッ素、リン等の晶析対象物質含有原水は、晶析処理により除去されるフッ素、リン等を含むものであれば、如何なる由来の原水であっても良く、例えば、半導体関連産業をはじめとする電子産業、発電所、アルミニウム工業等から排出される原水が挙げられるが、これらに限定されるものではない。   The raw water containing crystallization target substances such as fluorine and phosphorus in the present embodiment may be raw water of any origin as long as it contains fluorine, phosphorus and the like removed by crystallization treatment, for example, semiconductor related industries. Raw water discharged from the electronics industry, including power plants, power plants, aluminum industries, etc., but is not limited thereto.

晶析対象物質となるフッ素、リン等は、晶析反応により晶析するのであれば、任意の状態で原水中に存在することが可能である。原水中に溶解しているという観点から、晶析対象物質はイオン化した状態であるのが好ましい。   Fluorine, phosphorus, and the like that are crystallization target substances can be present in the raw water in an arbitrary state as long as they are crystallized by a crystallization reaction. From the viewpoint that it is dissolved in the raw water, the crystallization target substance is preferably in an ionized state.

本実施形態において用いられるカルシウム剤としては、例えば塩化カルシウム、水酸化カルシウム等が用いられる。カルシウム剤を添加する形態としては、粉末状態でもよいし、スラリ状態であってもよい。   As the calcium agent used in the present embodiment, for example, calcium chloride, calcium hydroxide and the like are used. As a form which adds a calcium agent, a powder state may be sufficient and a slurry state may be sufficient.

カルシウム剤の注入量としては、カルシウムの化学当量としてフッ素、リンの0.8倍〜2倍、1倍〜2倍までがよいが、1倍〜1.2倍がよりよい。カルシウムの化学当量が原水のフッ素、リンの化学当量の2倍より多いとフッ化カルシウム、リン酸カルシウムが種晶上に析出せずに微粒子として生成しやすく、処理水にフッ化カルシウム、リン酸カルシウムが混入する場合があり、0.8倍より少ないと、原水中のフッ素、リンのうちフッ化カルシウム、リン酸カルシウムとならない割合が多くなり、処理水にフッ素、リンが混入する場合がある。   The injection amount of the calcium agent is preferably 0.8 to 2 times or 1 to 2 times that of fluorine or phosphorus as the chemical equivalent of calcium, but more preferably 1 to 1.2 times. When the chemical equivalent of calcium is more than twice the chemical equivalent of fluorine and phosphorus in the raw water, calcium fluoride and calcium phosphate are not easily deposited on the seed crystal and are easily formed as fine particles, and calcium fluoride and calcium phosphate are mixed into the treated water. If the ratio is less than 0.8 times, the proportion of fluorine and phosphorus in raw water that does not become calcium fluoride and calcium phosphate increases, and fluorine and phosphorus may be mixed into the treated water.

本実施形態においては、原水とカルシウム剤とを晶析反応部28に添加する前に、あらかじめ、晶析反応部28に種晶が存在していてもよいし、あらかじめ晶析反応部28内に種晶が存在していなくてもよい。安定した処理を行うためには、晶析反応部28にあらかじめ種晶が存在していることが好ましい。   In the present embodiment, before adding raw water and calcium agent to the crystallization reaction unit 28, seed crystals may exist in advance in the crystallization reaction unit 28, or in the crystallization reaction unit 28 in advance. There may be no seed crystals. In order to perform a stable treatment, it is preferable that a seed crystal is present in the crystallization reaction unit 28 in advance.

種晶は、その表面に生成した難溶性カルシウム塩の結晶を析出させることができるものであればよく、任意の材質が選択可能であり、例えば、ろ過砂、活性炭、およびジルコンサンド、ガーネットサンド、サクランダム(商品名、日本カートリット株式会社製)などをはじめとする金属元素の酸化物を含んで構成される粒子、ならびに、晶析反応による析出物である難溶性カルシウム塩を含んで構成される粒子等が挙げられるが、これらに限定されるものではない。より純粋な難溶性塩をペレット等として入手できるという観点から、晶析反応による析出物である難溶性塩を含んで構成される粒子が好ましい。晶析反応による析出物である難溶性カルシウム塩を含んで構成される粒子としては、例えば、フッ化カルシウムを析出させる場合には蛍石等が挙げられ、リン酸カルシウムを析出させる場合にはリン鉱石等が挙げられる。   The seed crystal may be any material as long as it can precipitate a hardly soluble calcium salt crystal formed on the surface thereof, and any material can be selected, for example, filtration sand, activated carbon, zircon sand, garnet sand, It is composed of particles containing oxides of metal elements such as Sac Random (trade name, manufactured by Nihon Cartrit Co., Ltd.) and hardly soluble calcium salts that are precipitates 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 composed of the hardly soluble salt which is a precipitate by a crystallization reaction are preferable. Examples of the particles comprising a hardly soluble calcium salt that is a precipitate by crystallization reaction include fluorite when depositing calcium fluoride, and phosphate ore when depositing calcium phosphate. Is mentioned.

晶析反応部28へ通水する原水の流量は、晶析反応を良好に行う観点から、滞留時間1〜4時間の範囲であることが好ましく、2〜4時間であることがさらに好ましい。   The flow rate of the raw water flowing into the crystallization reaction unit 28 is preferably in the range of residence time 1 to 4 hours, and more preferably 2 to 4 hours, from the viewpoint of satisfactorily performing the crystallization reaction.

固液分離部30を流れる処理水の流速(LV)は、固液分離を良好に行う観点から、0.1〜2.0m/hの範囲が好ましく、0.2〜1.0m/hの範囲がより好ましい。   The flow rate (LV) of the treated water flowing through the solid-liquid separation unit 30 is preferably in the range of 0.1 to 2.0 m / h, preferably 0.2 to 1.0 m / h, from the viewpoint of satisfactorily performing solid-liquid separation. A range is more preferred.

図2は、参考例の晶析反応装置の構成の一例を示す模式図である。図2に示す晶析反応装置100は、晶析反応槽110、種晶サイロ112、カルシウム剤を晶析反応槽110へ添加する添加手段の一例としてのカルシウム剤添加ライン114、原水を晶析反応槽110へ流入させる流入手段の一例としての原水通水ライン116、種晶添加ライン118、処理水排出ライン120、難溶性塩排出ライン122、を備えている。   FIG. 2 is a schematic diagram showing an example of the configuration of a crystallization reaction apparatus of a reference example. A crystallization reaction apparatus 100 shown in FIG. 2 includes a crystallization reaction tank 110, a seed crystal silo 112, a calcium agent addition line 114 as an example of addition means for adding a calcium agent to the crystallization reaction tank 110, and a crystallization reaction of raw water. A raw water flow line 116, a seed crystal addition line 118, a treated water discharge line 120, and a hardly soluble salt discharge line 122 are provided as an example of an inflow means for flowing into the tank 110.

晶析反応槽110には、原水貯槽(不図示)からの原水通水ライン116、カルシウム剤貯槽(不図示)からのカルシウム剤添加ライン114が接続されている。また、種晶サイロ112と晶析反応槽110との間は、種晶添加ライン118が接続されている。さらに、晶析反応槽110の処理水排出口111には、処理水排出ライン120が接続され、晶析反応槽110の難溶性塩排出口には、難溶性塩排出ライン122が接続されている。   The crystallization reaction tank 110 is connected to a raw water passage line 116 from a raw water storage tank (not shown) and a calcium agent addition line 114 from a calcium agent storage tank (not shown). A seed crystal addition line 118 is connected between the seed crystal silo 112 and the crystallization reaction tank 110. Further, a treated water discharge line 120 is connected to the treated water discharge port 111 of the crystallization reaction tank 110, and a hardly soluble salt discharge line 122 is connected to the hardly soluble salt discharge port of the crystallization reaction tank 110. .

晶析反応槽110内には、難溶性塩の結晶を生成させる晶析反応部126と、難溶性塩結晶と処理水との固液分離を行う固液分離部128とが設けられている。晶析反応槽110内には、晶析反応槽110の外周壁に対向する内周壁124が設けられており、この外周壁と内周壁124間を固液分離部128としている。本実施形態の内周壁124は晶析反応槽110の外周壁の所定区間に設けられているが、内周壁124は外周壁の全周にわたって設けられていてもよい。   In the crystallization reaction tank 110, there are provided a crystallization reaction unit 126 for generating hardly soluble salt crystals and a solid / liquid separation unit 128 for performing solid / liquid separation between the hardly soluble salt crystals and the treated water. In the crystallization reaction tank 110, an inner peripheral wall 124 facing the outer peripheral wall of the crystallization reaction tank 110 is provided, and a space between the outer peripheral wall and the inner peripheral wall 124 serves as a solid-liquid separation unit 128. Although the inner peripheral wall 124 of this embodiment is provided in a predetermined section of the outer peripheral wall of the crystallization reaction tank 110, the inner peripheral wall 124 may be provided over the entire periphery of the outer peripheral wall.

晶析反応部126と固液分離部128とは内周壁124により区画されており、内周壁124の下部には、晶析反応部126と固液分離部128とが連通する連通口130が形成されている。また、前述した処理水排出口111は、固液分離部128が形成されている晶析反応槽110の外周壁に設けられており、この処理水排出口111に処理水排出ライン120が接続されている。   The crystallization reaction unit 126 and the solid-liquid separation unit 128 are partitioned by an inner peripheral wall 124, and a communication port 130 through which the crystallization reaction unit 126 and the solid-liquid separation unit 128 communicate with each other is formed below the inner peripheral wall 124. Has been. Further, the treated water discharge port 111 described above is provided on the outer peripheral wall of the crystallization reaction tank 110 where the solid-liquid separation unit 128 is formed, and the treated water discharge line 120 is connected to the treated water discharge port 111. ing.

また、固液分離部128と晶析反応部126とを隔てる内周壁124の上端は、処理水排出口111と同じ高さか、または処理水の一部が処理水排出口111から排出可能な範囲で処理水排出口111より低い位置に設定する。   Further, the upper end of the inner peripheral wall 124 that separates the solid-liquid separation unit 128 and the crystallization reaction unit 126 is the same height as the treated water discharge port 111 or a range in which a part of the treated water can be discharged from the treated water discharge port 111. Is set to a position lower than the treated water discharge port 111.

晶析反応槽110の晶析反応部126には、ドラフトチューブ134、晶析反応部126内の流体を撹拌する攪拌手段の一例としての攪拌装置132を備える。攪拌装置132は攪拌翼136を備え、攪拌翼136は、ドラフトチューブ134内に配置され、撹拌軸を介して伝達されるモータが発生する回転力によって回転する。   The crystallization reaction section 126 of the crystallization reaction tank 110 includes a draft tube 134 and a stirring device 132 as an example of a stirring means for stirring the fluid in the crystallization reaction section 126. The stirring device 132 includes a stirring blade 136. The stirring blade 136 is disposed in the draft tube 134 and is rotated by a rotational force generated by a motor transmitted through the stirring shaft.

本実施形態に係る晶析反応装置100の動作について説明する。   The operation of the crystallization reaction apparatus 100 according to this embodiment will be described.

まず、原水通水ライン116を通して、フッ素、リンの晶析対象物質を含有する原水(以下、単に「原水」と呼ぶ場合がある。)を晶析反応部126に通水する。また、カルシウム剤添加ライン114を通して、カルシウム剤を晶析反応部126に添加する。さらに、モータにより種晶サイロ112中の種晶が種晶添加ライン118を通して晶析反応部126に添加されることが好ましい。   First, raw water containing a substance to be crystallized from fluorine and phosphorus (hereinafter sometimes simply referred to as “raw water”) is passed through the raw water flow line 116 to the crystallization reaction unit 126. Further, the calcium agent is added to the crystallization reaction part 126 through the calcium agent addition line 114. Furthermore, it is preferable that the seed crystal in the seed crystal silo 112 is added to the crystallization reaction unit 126 through the seed crystal addition line 118 by the motor.

そして、晶析反応槽110の晶析反応部126において、原水に含まれるフッ素、リンの晶析対象物質がカルシウム剤と反応して、フッ化カルシウム、リン酸カルシウム(難溶性カルシウム塩)が生成して、種晶表面に析出し、難溶性塩(難溶性カルシウム塩)の結晶となる。   Then, in the crystallization reaction part 126 of the crystallization reaction tank 110, the fluorine and phosphorus crystallization target substances contained in the raw water react with the calcium agent to produce calcium fluoride and calcium phosphate (slightly soluble calcium salt). , Precipitated on the seed crystal surface to form crystals of a hardly soluble salt (hardly soluble calcium salt).

晶析反応部126内で生成したフッ化カルシウム、リン酸カルシウムの難溶性カルシウム塩の結晶は、例えば定期的に難溶性塩排出ライン122から引き抜かれ、系外へ排出される。難溶性カルシウム塩の結晶の引き抜き方法は、特に制限されるものではないが、チューブポンプ等のスラリ用ポンプを用いて、晶析反応槽110から難溶性カルシウム塩の結晶を引き抜く方法でも良いし、図1に示すように難溶性塩排出ライン122にバルブ122aを取り付け、単に重力によって晶析反応槽110から難溶性カルシウム塩の結晶を引き抜く方法でもよい。   The crystals of the poorly soluble calcium salt of calcium fluoride and calcium phosphate generated in the crystallization reaction unit 126 are, for example, periodically extracted from the hardly soluble salt discharge line 122 and discharged out of the system. The method of extracting the hardly soluble calcium salt crystal is not particularly limited, but may be a method of extracting the hardly soluble calcium salt crystal from the crystallization reaction tank 110 using a slurry pump such as a tube pump, As shown in FIG. 1, a method may be used in which a valve 122a is attached to the hardly soluble salt discharge line 122 and the crystal of the hardly soluble calcium salt is simply extracted from the crystallization reaction tank 110 by gravity.

一方、晶析反応部126内の晶析反応後の処理水は、連通口130から固液分離部128に流入する。この際、処理水と共に、難溶性塩の結晶の一部が固液分離部128に流入するが、固液分離部128では、晶析反応後の処理水が上向流を形成して固液分離部128を通過し、処理水中に含まれる難溶性塩結晶と処理水とが固液分離される。固液分離された処理水は、処理水排出ライン120を通して、本実施形態の最終処理水として系外に排出される。   On the other hand, the treated water after the crystallization reaction in the crystallization reaction unit 126 flows into the solid-liquid separation unit 128 from the communication port 130. At this time, a part of the crystals of the hardly soluble salt flows into the solid-liquid separation unit 128 together with the treated water. In the solid-liquid separation unit 128, the treated water after the crystallization reaction forms an upward flow to form a solid-liquid liquid. After passing through the separation unit 128, the hardly soluble salt crystal and the treated water contained in the treated water are separated into solid and liquid. The treated water subjected to the solid-liquid separation is discharged out of the system through the treated water discharge line 120 as the final treated water of the present embodiment.

ところで、補給した種晶のうち微細すぎる粒径のものや、種晶表面に析出できなかった難溶性カルシウム塩の結晶等の微細粒子は、固液分離部128で分離しきれず、上向流によって処理水と共に流出し、系外に排出されてしまう。一般的に、この排出された微細粒子は、回収されずに汚泥として処分されてしまうが、この微細粒子を固液分離可能な粒径にまで成長させることができれば、発生汚泥量を削減することができ、かつ種晶の補給量も削減することが可能となる。従来、処理水と共に流出する微細粒子を固液分離可能な粒径にまで成長させるために、処理水中の微細粒子を反応部分に戻す方法が提案されている(例えば、特開2002−292202、特開2009−226232、特開2010−207755)。   By the way, fine particles such as those of a replenished seed crystal having a too small particle diameter or crystals of a hardly soluble calcium salt that could not be precipitated on the seed crystal surface could not be separated by the solid-liquid separation unit 128, It flows out with treated water and is discharged out of the system. In general, the discharged fine particles are disposed of as sludge without being recovered, but if the fine particles can be grown to a particle size capable of solid-liquid separation, the amount of generated sludge can be reduced. It is possible to reduce the replenishment amount of seed crystals. Conventionally, a method for returning fine particles in the treated water to the reaction portion has been proposed in order to grow the fine particles flowing out together with the treated water to a particle size that can be solid-liquid separated (see, for example, JP-A-2002-292202, 2009-226232, JP 2010-207755).

本実施形態では、図2に示す晶析反応装置100のように、固液分離部128と晶析反応部126とを隔てる内周壁124の上端が、処理水排出口111と同じ高さか、または処理水の一部が処理水排出口111から排出可能な範囲で処理水排出口111より低い位置に設定する。   In the present embodiment, as in the crystallization reaction apparatus 100 shown in FIG. 2, the upper end of the inner peripheral wall 124 that separates the solid-liquid separation unit 128 and the crystallization reaction unit 126 is the same height as the treated water discharge port 111, or A part of the treated water is set at a position lower than the treated water discharge port 111 within a range where the treated water can be discharged from the treated water discharge port 111.

一般的に、晶析反応部126の水位は処理水排出口111と同じ高さであるため、内周壁124の上端を処理水排出口111と同じ高さかその高さより低くしてしまうと、晶析反応部126内の難溶性カルシウム塩の結晶等が内周壁124を越えて固液分離部128側に越流してしまう。しかし、フッ化カルシウム、リン酸カルシウムの結晶を得る場合、晶析反応部126内の流体の単位体積当たりの比重は固液分離部128内の流体の比重より高くなり易い。例えばフッ化カルシウムの結晶を得る場合、晶析反応部126内の結晶を含んだ原水1L当たりの重さは2.0kg/Lになり得る。これに対し、固液分離部128内の比重はせいぜい1.0kg/L〜1.2kg/L程度である。   Generally, since the water level of the crystallization reaction part 126 is the same height as the treated water discharge port 111, if the upper end of the inner peripheral wall 124 is made the same height as the treated water discharge port 111 or lower than that height, Crystals or the like of the hardly soluble calcium salt in the precipitation reaction portion 126 will flow over the inner peripheral wall 124 to the solid-liquid separation portion 128 side. However, when obtaining crystals of calcium fluoride and calcium phosphate, the specific gravity per unit volume of the fluid in the crystallization reaction unit 126 tends to be higher than the specific gravity of the fluid in the solid-liquid separation unit 128. For example, when obtaining calcium fluoride crystals, the weight per liter of raw water containing the crystals in the crystallization reaction part 126 can be 2.0 kg / L. On the other hand, the specific gravity in the solid-liquid separator 128 is at most about 1.0 kg / L to 1.2 kg / L.

このように、晶析反応部126と固液分離部128に比重差が生じると、晶析反応部126と固液分離部128に水位差が生じる。したがって、本実施形態のように、内周壁124の上端の位置を上記のように下げても、晶析反応部126内の原水が固液分離部128に越流することはなく、固液分離部128内の処理水の一部を晶析反応部126に戻せることになる。これにより、処理水中に含まれる微細粒子(難溶性カルシウム塩の結晶や種晶等)を、何ら動力機器を使用することなく晶析反応部126に返送することが可能となるため、より晶析反応部126内の難溶性カルシウム塩の結晶や種晶の粒径分布を細かく維持することが可能となる。その結果、更に難溶性カルシウム塩の結晶の回収率を向上させることが可能となる。   Thus, when a specific gravity difference occurs between the crystallization reaction unit 126 and the solid-liquid separation unit 128, a water level difference occurs between the crystallization reaction unit 126 and the solid-liquid separation unit 128. Therefore, as in this embodiment, even if the position of the upper end of the inner peripheral wall 124 is lowered as described above, the raw water in the crystallization reaction unit 126 does not flow into the solid-liquid separation unit 128, and the solid-liquid separation is performed. A part of the treated water in the unit 128 can be returned to the crystallization reaction unit 126. This makes it possible to return fine particles (crystals or seed crystals of sparingly soluble calcium salt) contained in the treated water to the crystallization reaction unit 126 without using any power equipment. The particle size distribution of the hardly soluble calcium salt crystals and seed crystals in the reaction section 126 can be maintained finely. As a result, it becomes possible to further improve the recovery rate of crystals of the hardly soluble calcium salt.

次に、本実施形態の晶析反応装置100のその他の条件について説明する。   Next, other conditions of the crystallization reaction apparatus 100 of this embodiment will be described.

本実施形態における晶析対象物質含有原水は、晶析処理により除去されるフッ素、リンを含むものである。しかし、フッ素、リンを含むものであれば、如何なる由来の原水であっても良く、例えば、半導体関連産業をはじめとする電子産業、発電所、アルミニウム工業等から排出される原水が挙げられるが、これらに限定されるものではない。   The crystallization target substance-containing raw water in the present embodiment contains fluorine and phosphorus that are removed by crystallization treatment. However, raw water of any origin may be used as long as it contains fluorine and phosphorus, for example, raw water discharged from the electronics industry including the semiconductor-related industry, the power plant, the aluminum industry, It is not limited to these.

晶析対象物質となるフッ素、リンは、晶析反応により晶析するのであれば、任意の状態で原水中に存在することが可能である。原水中に溶解しているという観点から、フッ素、リンはイオン化した状態であるのが好ましい。   Fluorine and phosphorus as crystallization target substances can be present in the raw water in any state as long as they are crystallized by a crystallization reaction. From the viewpoint of dissolving in raw water, fluorine and phosphorus are preferably in an ionized state.

本実施形態において、カルシウム剤及び原水の晶析反応部126への添加(注入点)は、攪拌翼136の近傍に行われることが好ましい。カルシウム剤及び原水を攪拌翼136の近傍に添加することにより、カルシウム剤及び原水は、晶析反応部126へ注入されると直ちに拡散せしめられ、カルシウム剤濃度やフッ素、リン濃度が素早く低下する。このため、形成された難溶性塩が液中に直接析出することが少なくなり、晶析反応部126内の種晶上の難溶塩結晶として液中のフッ素、リンをじっくり取り込むことができる。   In the present embodiment, the addition (injection point) of the calcium agent and raw water to the crystallization reaction unit 126 is preferably performed in the vicinity of the stirring blade 136. By adding the calcium agent and the raw water in the vicinity of the stirring blade 136, the calcium agent and the raw water are immediately diffused when injected into the crystallization reaction unit 126, and the calcium agent concentration, the fluorine concentration, and the phosphorus concentration are quickly lowered. For this reason, the formed hardly soluble salt is less likely to be directly deposited in the liquid, and fluorine and phosphorus in the liquid can be taken in well as the hardly soluble salt crystal on the seed crystal in the crystallization reaction unit 126.

本実施形態においては、筒内に攪拌装置132の攪拌翼136が位置するようにドラフトチューブ134を設置することが好ましい。このとき、攪拌翼136は下降流を形成するものであることが好ましい。このようにドラフトチューブ134を設置すると、チューブ下部に向けて下降流が生じ、拡散流速が比較的大きいゾーンが形成される。このため、原水やカルシウム剤等をより素早く拡散させることができ、原水やカルシウム剤の濃度が局所的に濃い領域同士が接触せずに、難溶性カルシウム塩粒子の直接生成が抑制される。   In the present embodiment, it is preferable to install the draft tube 134 so that the stirring blade 136 of the stirring device 132 is positioned in the cylinder. At this time, the stirring blade 136 preferably forms a downward flow. When the draft tube 134 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, raw | natural water, a calcium agent, etc. can be diffused more rapidly, and the direct production | generation of a sparingly soluble calcium salt particle | grain is suppressed, without the area | regions where the density | concentration of raw | natural water or a calcium agent is locally concentrated.

また、上記のようにドラフトチューブ134および攪拌翼136を設置すると、チューブ外周部には流れのゆるやかな上向流ゾーンが形成される。このゾーンでは、粒子が分級されて小粒径の粒子はチューブ外側面に沿って上昇すると共に、チューブ上端からチューブ内部に再侵入して下降し、原水やカルシウム剤等の注入点付近やその下部の撹拌ゾーンへと再循環する。これら小粒径の結晶が核となって晶析反応を促進せしめるため、難溶性塩結晶の回収率を向上させることができる。   Moreover, when the draft tube 134 and the stirring blade 136 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, the particles are classified and small 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. Recirculate to the stirring zone. Since these small-sized crystals serve as nuclei to promote the crystallization reaction, the recovery rate of the hardly soluble salt crystals can be improved.

さらに、晶析反応が進んで粒径が大きくなった結晶は、チューブ外周部の上向流によっては上昇せず、下に沈んで再びドラフトチューブ134内には入り込まないため、成長した結晶が攪拌翼136との衝突により破壊されてしまうことを防止することができるため、難溶性塩結晶の回収率の向上に寄与することができる。   Furthermore, the crystals whose particle size has increased due to the progress of the crystallization reaction does not rise due to the upward flow at the outer periphery of the tube, sinks down and does not enter the draft tube 134 again. Since it can be prevented from being destroyed by the collision with the blade 136, it can contribute to the improvement of the recovery rate of the hardly soluble salt crystal.

本実施形態では、晶析反応槽110に酸又はアルカリを添加し、晶析反応部126における晶析反応液のpHを0.8〜3の範囲とすることが好ましく、1〜1.5の範囲とすることがより好ましい。酸又はアルカリを添加して晶析反応部126のpHを0.8〜3の範囲で運転することにより、例えば、処理水のフッ素、リンの晶析対象物質濃度を低減させることができる。   In this embodiment, it is preferable to add acid or alkali to the crystallization reaction tank 110, and to make pH of the crystallization reaction liquid in the crystallization reaction part 126 into the range of 0.8-3, It is more preferable to set the range. By adding an acid or alkali and operating the crystallization reaction section 126 at a pH in the range of 0.8 to 3, for example, the concentration of the crystallization target substance of fluorine and phosphorus in the treated water can be reduced.

本実施形態において用いられるカルシウム剤としては、例えば塩化カルシウム、水酸化カルシウム等が用いられる。カルシウム剤を添加する形態としては、粉末状態でもよいし、スラリ状態であってもよい。   As the calcium agent used in the present embodiment, for example, calcium chloride, calcium hydroxide and the like are used. As a form which adds a calcium agent, a powder state may be sufficient and a slurry state may be sufficient.

カルシウム剤の注入量としては、カルシウムの化学当量としてフッ素、リンの0.8倍〜2倍、1倍〜2倍までがよいが、1倍〜1.2倍がよりよい。カルシウムの化学当量が原水のフッ素、リンの化学当量の2倍より多いとフッ化カルシウム、リン酸カルシウムが種晶上に析出せずに微粒子として生成しやすく、処理水にフッ化カルシウム、リン酸カルシウムが混入する場合があり、0.8倍より少ないと、原水中のフッ素、リンのうちフッ化カルシウム、リン酸カルシウムとならない割合が多くなり、処理水にフッ素、リンが混入する場合がある。   The injection amount of the calcium agent is preferably 0.8 to 2 times or 1 to 2 times that of fluorine or phosphorus as the chemical equivalent of calcium, but more preferably 1 to 1.2 times. When the chemical equivalent of calcium is more than twice the chemical equivalent of fluorine and phosphorus in the raw water, calcium fluoride and calcium phosphate are not easily deposited on the seed crystal and are easily formed as fine particles, and calcium fluoride and calcium phosphate are mixed into the treated water. If the ratio is less than 0.8 times, the proportion of fluorine and phosphorus in raw water that does not become calcium fluoride and calcium phosphate increases, and fluorine and phosphorus may be mixed into the treated water.

本実施形態においては、原水とカルシウム剤とを晶析反応部126に添加する前に、あらかじめ、晶析反応部126に種晶が存在していてもよいし、あらかじめ晶析反応部126内に種晶が存在していなくてもよい。安定した処理を行うためには、晶析反応部126にあらかじめ種晶が存在していることが好ましい。   In the present embodiment, before adding raw water and calcium agent to the crystallization reaction unit 126, seed crystals may exist in advance in the crystallization reaction unit 126, or in the crystallization reaction unit 126 in advance. There may be no seed crystals. In order to perform a stable process, it is preferable that a seed crystal is present in the crystallization reaction unit 126 in advance.

種晶は、その表面に生成した難溶性カルシウム塩の結晶を析出させることができるものであればよく、任意の材質が選択可能であり、例えば、ろ過砂、活性炭、およびジルコンサンド、ガーネットサンド、サクランダム(商品名、日本カートリット株式会社製)などをはじめとする金属元素の酸化物を含んで構成される粒子、ならびに、晶析反応による析出物である難溶性塩を含んで構成される粒子等が挙げられるが、これらに限定されるものではない。より純粋な難溶性塩をペレット等として入手できるという観点から、晶析反応による析出物である難溶性塩を含んで構成される粒子が好ましい。晶析反応による析出物である難溶性塩を含んで構成される粒子としては、フッ化カルシウムを析出させる場合には、例えば蛍石等が挙げられ、リン酸カルシウムを析出させる場合には、例えばリン鉱石等が挙げられる。   The seed crystal may be any material as long as it can precipitate a hardly soluble calcium salt crystal formed on the surface thereof, and any material can be selected, for example, filtered sand, activated carbon, zircon sand, garnet sand, It is composed of particles composed of oxides of metal elements such as sacrandom (trade name, manufactured by Nihon Cartrit Co., Ltd.) and the like, and hardly soluble salts that are precipitates by crystallization reaction. Examples thereof include, but are not limited to, particles. From the viewpoint that a purer hardly soluble salt can be obtained as a pellet or the like, particles composed of the hardly soluble salt which is a precipitate by a crystallization reaction are preferable. Examples of the particles composed of a hardly soluble salt that is a precipitate by a crystallization reaction include fluorite when depositing calcium fluoride, and when depositing calcium phosphate, for example, phosphate ore. Etc.

以下、実施例および比較例を挙げ、本発明をより具体的に詳細に説明するが、本発明は、以下の実施例に限定されるものではない。   Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

(実施例1)
実施例1では、図1に示す晶析反応装置を用い、以下の条件で、フッ素含有原水からフッ化カルシウムの回収を行った。
Example 1
In Example 1, the crystallization reaction apparatus shown in FIG. 1 was used, and calcium fluoride was recovered from the fluorine-containing raw water under the following conditions.

<晶析反応装置>
晶析反応部サイズ:130L(440mmφ×880mmH)
固液分離部サイズ:230L(440×590×880mmH)
<試験条件>
フッ素含有原水流量:50L/h
フッ素含有原水のフッ素濃度:10000mg/L
カルシウム剤:消石灰10%スラリを塩酸で溶解した溶液
晶析反応部内のpH:pH2(NaOHを添加して調整)
晶析反応部内の初期充填種晶:20kg(その後の種晶の補給無し)
晶析反応部内のスラリ濃度:30〜35v/v%(難溶性塩排出管から適宜引き抜く)
<Crystal crystallization reactor>
Crystallization reaction part size: 130 L (440 mmφ × 880 mmH)
Solid-liquid separation part size: 230L (440 × 590 × 880mmH)
<Test conditions>
Fluorine-containing raw water flow rate: 50 L / h
Fluorine concentration of raw water containing fluorine: 10000 mg / L
Calcium agent: A solution in which 10% slurry of slaked lime is dissolved in hydrochloric acid. PH in the crystallization reaction part: pH 2 (adjusted by adding NaOH)
Initially filled seed crystals in the crystallization reaction section: 20 kg (without replenishment of seed crystals thereafter)
Slurry concentration in the crystallization reaction part: 30 to 35 v / v% (appropriately withdrawn from the hardly soluble salt discharge pipe)

実施例1の固液分離部の滞留時間は4.6h(230(L)/50(L/h))となり、晶析反応部の滞留時間は2.7hとなった。   The residence time in the solid-liquid separation part of Example 1 was 4.6 h (230 (L) / 50 (L / h)), and the residence time in the crystallization reaction part was 2.7 h.

実施例1では、原水を晶析反応部へ9.2時間通水した後、2.3時間通水を停止した。通水時間が400時間に達するまで、この通水及び通水停止を繰り返した。通水時の固液分離部の処理水の流速(LV)は0.2m/hであった。   In Example 1, the raw water was passed through the crystallization reaction part for 9.2 hours, and then stopped for 2.3 hours. This water flow and water flow stop were repeated until the water flow time reached 400 hours. The flow rate (LV) of the treated water in the solid-liquid separation part during water flow was 0.2 m / h.

(実施例2)
実施例2では、原水を晶析反応部へ4.6時間通水した後、1.15時間通水を停止したこと以外は実施例1と同様の条件で試験を行った。
(Example 2)
In Example 2, the test was performed under the same conditions as in Example 1 except that the raw water was passed through the crystallization reaction section for 4.6 hours and then stopped for 1.15 hours.

(実施例3)
実施例3では、原水を晶析反応部へ4.6時間通水した後、2.3時間通水を停止したこと以外は実施例1と同様の条件で試験を行った。
(Example 3)
In Example 3, the test was performed under the same conditions as in Example 1 except that the raw water was passed through the crystallization reaction section for 4.6 hours and then the water supply was stopped for 2.3 hours.

(実施例4)
実施例4では、固液分離部サイズを23L(440×60×880mmH)に変更した晶析反応装置を用いた。また、実施例4では、原水を晶析反応部へ0.46時間通水した後、0.23時間通水を停止した。通水時間が400時間に達するまで、この通水及び通水停止を繰り返した。なお、通水時の固液分離部の処理水の流速(LV)は2.0m/hであった。
Example 4
In Example 4, a crystallization reaction apparatus in which the solid-liquid separation part size was changed to 23 L (440 × 60 × 880 mmH) was used. In Example 4, the raw water was passed through the crystallization reaction section for 0.46 hours and then stopped for 0.23 hours. This water flow and water flow stop were repeated until the water flow time reached 400 hours. In addition, the flow rate (LV) of the treated water of the solid-liquid separation part at the time of water flow was 2.0 m / h.

(比較例1)
比較例1では、原水の通水停止を行わず、原水を晶析反応部へ400時間通水したこと以外は実施例1と同様の条件で試験を行った。通水時の固液分離部の処理水の流速(LV)は0.2m/hであった。
(Comparative Example 1)
In Comparative Example 1, the test was performed under the same conditions as in Example 1 except that the raw water was not stopped and the raw water was passed through the crystallization reaction part for 400 hours. The flow rate (LV) of the treated water in the solid-liquid separation part during water flow was 0.2 m / h.

(比較例2)
比較例2では、固液分離部サイズを23L(440×60×880mmH)に変更した晶析反応装置を用いて、原水の通水停止を行わず、原水を晶析反応部へ400時間通水したこと以外は実施例1と同様の条件で試験を行った。通水時の固液分離部の処理水の流速(LV)は2.0m/hであった。
(Comparative Example 2)
In Comparative Example 2, using the crystallization reaction apparatus whose solid-liquid separation part size was changed to 23 L (440 × 60 × 880 mmH), the raw water was passed through the crystallization reaction part for 400 hours without stopping the flow of the raw water. The test was performed under the same conditions as in Example 1 except that. The flow rate (LV) of the treated water in the solid-liquid separation part during water flow was 2.0 m / h.

(比較例3)
比較例3では、図2に示す晶析反応装置のように、周壁の上端を処理水排出口と同じ高さに設定した晶析反応装置を用いて、原水の通水停止を行わず、原水を晶析反応部へ400時間通水したこと以外は実施例1と同様の条件で試験を行った。通水時の固液分離部の処理水の流速(LV)は0.2m/hであった。
(Comparative Example 3)
In Comparative Example 3, as in the crystallization reaction apparatus shown in FIG. 2, the crystallization reaction apparatus in which the upper end of the peripheral wall is set to the same height as the treated water discharge port is used. The test was conducted under the same conditions as in Example 1 except that water was passed through the crystallization reaction part for 400 hours. The flow rate (LV) of the treated water in the solid-liquid separation part during water flow was 0.2 m / h.

表1に、実施例1〜4及び比較例1〜3の固液分離部の処理水の流速、晶析反応部への原水の通水時間、通水停止時間、及び通水400時間経過後のフッ化カルシウムの回収率をまとめた。   Table 1 shows the flow rate of treated water in the solid-liquid separation parts of Examples 1 to 4 and Comparative Examples 1 to 3, the water passage time of raw water to the crystallization reaction part, the water passage stop time, and the passage of water for 400 hours. The recovery rates of calcium fluoride were summarized.

Figure 2013141622
Figure 2013141622

図3は、実施例1の晶析反応部内の結晶の粒径分布を示す図であり、図4は、実施例2の晶析反応部内の結晶の粒径分布を示す図であり、図5は、実施例3の晶析反応部内の結晶の粒径分布を示す図であり、図6は、実施例4の晶析反応部内の結晶の粒径分布を示す図であり、図7は、比較例1の晶析反応部内の結晶の粒径分布を示す図であり、図8は、比較例2の晶析反応部内の結晶の粒径分布を示す図であり、図9は、比較例3の晶析反応部内の結晶の粒径分布を示す図である。晶析反応部内の結晶の粒径分布は、通水400時間後の晶析反応部内の粒径分布を、粒度分布計(ベックマン・コールター社製 LS230)を用いて測定した。   3 is a diagram showing the particle size distribution of crystals in the crystallization reaction part of Example 1, and FIG. 4 is a diagram showing the particle size distribution of crystals in the crystallization reaction part of Example 2, and FIG. These are diagrams showing the particle size distribution of crystals in the crystallization reaction part of Example 3, FIG. 6 is a diagram showing the particle size distribution of crystals in the crystallization reaction part of Example 4, and FIG. FIG. 8 is a diagram showing the particle size distribution of crystals in the crystallization reaction part of Comparative Example 1, FIG. 8 is a diagram showing the particle size distribution of crystals in the crystallization reaction part of Comparative Example 2, and FIG. 9 is a comparative example. FIG. 3 is a diagram showing a particle size distribution of crystals in a crystallization reaction part of 3. The particle size distribution of the crystals in the crystallization reaction part was measured using a particle size distribution meter (LS230 manufactured by Beckman Coulter, Inc.) after 400 hours of water flow.

種晶の補給を行わず原水の連続通水によりフッ化カルシウムを回収した比較例1では、図7及び表1の結果から判るように、晶析反応部内に、粒径が100μm以上の結晶が多く存在し、回収率も65%と低かった。さらに、固液分離部の処理水の流速を2.0m/hに上げた比較例2では、図8及び表1の結果から判るように、晶析反応部内に、粒径が125μm以上の結晶が多く存在し、回収率も50%とさらに低くなった。一方、原水の通水を間欠的に行った実施例、具体的には、原水の通水を固液分離部の滞留時間の1倍以上2倍以下の時間行い、通水停止を固液分離部の滞留時間の1/4倍以上1/2倍以下の時間行った実施例1〜4では、図3〜6及び表1の結果から判るように、晶析反応部内に、粒径が100μm以下の結晶が多く存在し、回収率も75%以上となり比較例1及び2より高い回収率を得ることができた。特に、原水の通水を固液分離部の滞留時間の1倍の時間、通水停止を固液分離部の滞留時間の1/2倍の時間の間行った実施例3、原水の通水を固液分離部の滞留時間の1倍の時間、通水停止を固液分離部の滞留時間の1/2倍の時間行った実施例4では、図5、図6及び表1の結果から判るように、晶析反応部内に、50μm以下の粒径の結晶が存在するようになり、回収率も90%以上と実施例1,2より高い回収率を得ることができた。すなわち、原水の通水を固液分離部の滞留時間の1倍の時間行い、通水停止を固液分離部の滞留時間の1/2倍の時間行うことにより、より細かい粒径の結晶を晶析反応部内に保持することができ、フッ化カルシウム結晶の回収率もより向上することがわかった。比較例3は原水を連続通水したものであるが、固液分離部の処理水を晶析反応部に返送しているため、晶析反応部内に、50μm以下の粒径の結晶が存在するようになり、回収率も90%以上となった。   In Comparative Example 1 in which calcium fluoride was recovered by continuous flow of raw water without replenishing seed crystals, as can be seen from the results of FIG. 7 and Table 1, crystals having a particle size of 100 μm or more were formed in the crystallization reaction part. Many were present and the recovery rate was as low as 65%. Furthermore, in Comparative Example 2 in which the flow rate of the treated water in the solid-liquid separation part was increased to 2.0 m / h, as can be seen from the results of FIG. 8 and Table 1, crystals having a particle size of 125 μm or more were formed in the crystallization reaction part. There were many, and the recovery rate was further reduced to 50%. On the other hand, an example in which the raw water was intermittently passed, specifically, the raw water was passed for 1 to 2 times the residence time of the solid-liquid separation unit, and the water flow was stopped for solid-liquid separation. In Examples 1 to 4, which were performed for a period of ¼ to ½ times the residence time of the part, as can be seen from the results of FIGS. 3 to 6 and Table 1, the particle size was 100 μm in the crystallization reaction part. Many of the following crystals existed, and the recovery rate was 75% or more, and a higher recovery rate than Comparative Examples 1 and 2 could be obtained. In particular, Example 3 in which the raw water was passed for one time the residence time of the solid-liquid separation unit, and the water passage was stopped for half the residence time of the solid-liquid separation unit. In Example 4 where the residence time of the solid-liquid separation unit was 1 time, and the water flow was stopped for 1/2 time of the residence time of the solid-liquid separation unit, the results shown in FIGS. As can be seen, crystals having a particle size of 50 μm or less are present in the crystallization reaction part, and the recovery rate is 90% or higher, which is higher than in Examples 1 and 2. That is, the raw water is passed through for a time that is one time the residence time of the solid-liquid separation part, and the water passage is stopped for a time that is one-half the residence time of the solid-liquid separation part. It was found that it could be retained in the crystallization reaction part, and the recovery rate of calcium fluoride crystals was further improved. In Comparative Example 3, the raw water was continuously passed, but since the treated water in the solid-liquid separation part was returned to the crystallization reaction part, crystals having a particle size of 50 μm or less exist in the crystallization reaction part. As a result, the recovery rate was 90% or more.

1,100 晶析反応装置、10,110 晶析反応槽、12,112 種晶サイロ、14,114 カルシウム剤添加ライン、16,116 原水通水ライン、18,24a,122a バルブ、20,118 種晶添加ライン、21,111 処理水排出口、22,120 処理水排出ライン、24,122 難溶性塩排出ライン、26,124 内周壁、28,126 晶析反応部、30,128 固液分離部、32,130 連通口、34,132 攪拌装置、36,134 ドラフトチューブ、38,136 攪拌翼。   1,100 crystallization reaction apparatus, 10,110 crystallization reaction tank, 12,112 seed silo, 14,114 calcium agent addition line, 16,116 raw water flow line, 18, 24a, 122a valve, 20,118 species Crystal addition line, 21,111 treated water discharge port, 22,120 treated water discharge line, 24,122 sparingly soluble salt discharge line, 26,124 inner peripheral wall, 28,126 crystallization reaction section, 30,128 solid-liquid separation section , 32, 130 communication port, 34, 132 stirring device, 36, 134 draft tube, 38, 136 stirring blade.

Claims (3)

攪拌翼を有する攪拌手段を備え、晶析対象物質を含む原水にカルシウム剤を添加して難溶性塩の結晶を生成させる晶析反応部を有する晶析反応槽と、前記晶析反応部へ前記原水を通水する通水手段と、を備え、
前記晶析反応槽内には、前記晶析反応槽の外周壁に対向する内周壁を配置し、内外周壁間で上向流を形成して、前記結晶と処理水との固液分離を行う固液分離部が設けられ、
前記通水手段は、前記晶析反応部への前記原水の通水を間欠的に行うことを特徴とする晶析反応装置。
A crystallization reaction tank having a crystallization reaction section that includes a stirring means having a stirring blade and adds a calcium agent to raw water containing a crystallization target substance to form crystals of a hardly soluble salt, and to the crystallization reaction section Water flow means for passing raw water,
In the crystallization reaction tank, an inner peripheral wall facing the outer peripheral wall of the crystallization reaction tank is disposed, and an upward flow is formed between the inner and outer peripheral walls to perform solid-liquid separation between the crystal and treated water. A solid-liquid separation unit is provided,
The crystallization reaction apparatus, wherein the water passing means intermittently passes the raw water through the crystallization reaction section.
前記通水手段による間欠通水時の前記原水の通水時間は、前記固液分離部における滞留時間の1倍以上2倍以下であり、前記通水手段による間欠通水時の前記原水の通水停止時間は、前記固液分離部における滞留時間の1/4倍以上1/2倍以下の時間であることを特徴とする請求項1記載の晶析反応装置。   The flow time of the raw water during intermittent water flow by the water flow means is 1 to 2 times the residence time in the solid-liquid separation unit, and the flow of the raw water during intermittent water flow by the water flow means is 2. The crystallization reaction apparatus according to claim 1, wherein the water stop time is a time that is not less than 1/4 times and not more than 1/2 times the residence time in the solid-liquid separation unit. 前記固液分離部が設けられている前記晶析反応槽の外周壁に、前記処理水を排出する排出口が形成され、
前記内周壁の上端は、前記排出口と同じ高さ、又は前記処理水の一部が前記排出口から排出可能な範囲で前記排出口より低い位置にあり、前記固液分離部内の処理水の一部は、前記内周壁を越えて前記晶析反応部に返送されることを特徴とする請求項1又は2記載の晶析反応装置。
A discharge port for discharging the treated water is formed on the outer peripheral wall of the crystallization reaction tank provided with the solid-liquid separation unit,
The upper end of the inner peripheral wall is at the same height as the discharge port or at a position lower than the discharge port within a range in which a part of the treated water can be discharged from the discharge port, and the treated water in the solid-liquid separation unit The crystallization reaction apparatus according to claim 1 or 2, wherein a part of the crystallization reaction apparatus is returned to the crystallization reaction section beyond the inner peripheral wall.
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Publication number Priority date Publication date Assignee Title
JPS61141996A (en) * 1984-12-17 1986-06-28 Ataka Kogyo Kk Treatment of waste water
JP2001038370A (en) * 1999-08-03 2001-02-13 Maezawa Ind Inc Waste water treatment device
JP2002292204A (en) * 2001-03-30 2002-10-08 Japan Organo Co Ltd Crystallization reaction apparatus provided with means for controlling amount of raw water to be supplied and crystallization method to use the same
DE102004020528A1 (en) * 2004-04-27 2005-11-24 Kali-Umwelttechnik Gmbh Continuous reaction and precipitation crystallization reactor, with central stirred, loop flow part, annular clarification zone and truncated conical annular partition to increase clarification surface
JP2010046608A (en) * 2008-08-22 2010-03-04 Kurita Water Ind Ltd Crystallizer and crystallization method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61141996A (en) * 1984-12-17 1986-06-28 Ataka Kogyo Kk Treatment of waste water
JP2001038370A (en) * 1999-08-03 2001-02-13 Maezawa Ind Inc Waste water treatment device
JP2002292204A (en) * 2001-03-30 2002-10-08 Japan Organo Co Ltd Crystallization reaction apparatus provided with means for controlling amount of raw water to be supplied and crystallization method to use the same
DE102004020528A1 (en) * 2004-04-27 2005-11-24 Kali-Umwelttechnik Gmbh Continuous reaction and precipitation crystallization reactor, with central stirred, loop flow part, annular clarification zone and truncated conical annular partition to increase clarification surface
JP2010046608A (en) * 2008-08-22 2010-03-04 Kurita Water Ind Ltd Crystallizer and crystallization method

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