JPH0251541B2 - - Google Patents
Info
- Publication number
- JPH0251541B2 JPH0251541B2 JP24017185A JP24017185A JPH0251541B2 JP H0251541 B2 JPH0251541 B2 JP H0251541B2 JP 24017185 A JP24017185 A JP 24017185A JP 24017185 A JP24017185 A JP 24017185A JP H0251541 B2 JPH0251541 B2 JP H0251541B2
- Authority
- JP
- Japan
- Prior art keywords
- edta
- crystals
- crystallization tank
- waste liquid
- acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000013078 crystal Substances 0.000 claims description 38
- 239000007788 liquid Substances 0.000 claims description 31
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 29
- 238000002425 crystallisation Methods 0.000 claims description 26
- 230000008025 crystallization Effects 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 17
- 239000002699 waste material Substances 0.000 claims description 13
- 239000002253 acid Substances 0.000 claims description 10
- 238000011084 recovery Methods 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 6
- 239000012530 fluid Substances 0.000 claims description 3
- 239000000243 solution Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 239000011550 stock solution Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000010979 pH adjustment Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- UEUXEKPTXMALOB-UHFFFAOYSA-J tetrasodium;2-[2-[bis(carboxylatomethyl)amino]ethyl-(carboxylatomethyl)amino]acetate Chemical class [Na+].[Na+].[Na+].[Na+].[O-]C(=O)CN(CC([O-])=O)CCN(CC([O-])=O)CC([O-])=O UEUXEKPTXMALOB-UHFFFAOYSA-J 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Landscapes
- Removal Of Specific Substances (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
産業上の利用分野
本発明は、化学めつき廃液等、エチレンジアミ
ン四酢酸（以下、EDTA又はH4Yと記す）を含
む廃液から有価物であるEDTAを回収する方法
に関する。
従来の技術
従来、EDTA廃液からEDTAを回収するには、
PHを鉱酸を用いて調整し、Na4Y、Na3HY、
Na2H2及びNaH3Yとして存在するEDTAナトリ
ウム塩を不溶性の遊離酸H4Yとして晶析させた
後、固液分離している。
この回収方法においては、晶析槽に撹拌機を取
りつけ、EDTA廃液と添加した酸とを撹拌混合
しながら、H4Yの溶解度が最も低くなるPH１〜
２までPHを低下させてH4Yを析出させ、回収す
る。
発明が解決しようとする問題点
しかしながら、このような従来法にあつては、
析出した結晶粒径が0.05〜0.1cmと小さい上、結
晶形状が樹枝状晶であるものが多く、後段の固液
分離が困難であり、沈澱池が大型化し、また、結
晶を再利用するのに必要な洗浄、脱水工程におい
て、結晶のリークを防ぎ、かつ洗浄効果を向上さ
せるために高価な耐酸性の高速遠心分離機等を用
いなければならなかつた。更に、結晶内への不純
物の込み量も多く、回収品質を悪化するという問
題点もあつた。
EDTAの結晶粒径を増大させるためには、核
発生が起こらず、種晶が存在すると、その成長の
みが起こる準安定域の過飽和度で晶析を行わなけ
ればならない。しかし、従来の晶析法では、
EDTAの過飽和溶液は不安定になりがちであり、
時間の経過及び極めて小さな液の流れの乱れ等が
原因して微小核が多数発生してしまい、粒径を増
大することができなかつた。
従つて、本発明は、前記従来技術の欠点を解消
し、EPTA廃液からH4Yを連続的かつ効率的に、
結晶粒径が大きく、結晶形状が球状に近く、更に
高純度で析出させることにより、後段の固液分離
及び洗浄、脱水工程の設備を簡素化して、高い回
収率でH4Y結晶を経済的に回収しうるEDTA回
収法方法を提供することを目的とする。
問題点を解決するための手段及び作用
本発明は、溶解しているEDTAナトリウム塩
を不溶性のH4Yとして晶析させる場合、H4Y結
晶の成長の阻害要因が結晶と撹拌翼との衝突によ
る結晶の破砕及び撹拌翼による液の剪断作用によ
る多量の微小核発生であることを実験により確認
し、撹拌翼を用いないで結晶を浮遊状態にできる
方法として、処理液の一部を晶析槽の底部より流
入させ、H4Yの種晶を流動化することによつて
前記の問題点を解決したものである。
即ち、本発明によるEDTAの回収方法は、
H4Yの種晶を充填した晶析槽の底部からPH３以
下の処理液の一部を循環液として流入させて、上
向流で種晶を流動下させると同時に底部から
EDTA廃液を供給して晶析を行い、所定の粒径
に成長したH4Yの結晶を底部から抜き出すこと
を特徴とする。
本発明においては、過飽和の生成を、種晶が流
動化されている晶析槽の底部で、原液と処理液の
一部とを混合することによつて行う。本発明方法
において、晶析槽の底部のH4Yの過飽和度（溶
液濃度−飽和濃度）が5000mg／以下になるよう
にEDTA廃液及び／又は処理液の流量を調節す
るのが好ましい。
晶析槽内の温度は、結晶の成長に対して大きく
影響し、高温である程、成長速度が速く、かつ微
小核の発生を抑制でき、一般に20〜80℃であるの
が好ましい。
次に、図面に基づいて本発明を説明する。
第１図は本発明方法を実施する装置のフローシ
ートである。第１図において、EDTA廃液は、
原料供給配管１から晶析槽２へ流入する。晶析槽
２には、H4Y結晶３が充填されており、更に、
底部から循環液９が流入されて、H4Y結晶３を
浮遊状態に維持する。処理液は、晶析槽２の上部
から処理液をPH調整槽５へ導入され、処理液配管
１１から放出されるが、その際、処理液の一部を
循環液として利用するため、PH計６でPHを測定
し、処理液のPHが３より高い場合に、電磁弁１２
を開き、処理液のPHが３以下、好ましくは0.5〜
2.5になるように酸供給配管４から酸を供給する。
PH３以下に調整された処理液の一部を循環ポンプ
７により流量計８を介して循環液供給配管９から
晶析槽２へ流入させる。このよにして所定の粒径
に成長したH4Y結晶は、結晶抜き出し配管１０
から抜き出す。
図面には、円錐型の晶析槽を示したが、円筒型
又は多段の円筒型晶析槽を使用しても、同様に良
好な結晶が得られる。
実施例
高さ３ｍで、空間率一定の円錘型晶析槽を有す
る、図面に示した装置を用いて、EDTA濃度が
H4Y換算で26000mg／であEDTA廃液から
EDTAを回収する実験を行つた。その際、晶析
槽内には、粒径約0.2mmのH4Y結晶を種晶として
充填しておいた。晶析槽の底部から原液を流入さ
せ、更に、晶析槽上部の液のPHが0.5〜2.5になる
ように硫酸を添加し、これを循環液として晶析槽
の底部へ流入させた。H4Y過飽和度と槽内の温
度に対する、抜き出したH4Y結晶の平均粒径及
び微小核発生の関係を測定し、結果を下記の表に
示す。
INDUSTRIAL APPLICATION FIELD The present invention relates to a method for recovering EDTA, which is a valuable product, from a waste liquid containing ethylenediaminetetraacetic acid (hereinafter referred to as EDTA or H 4 Y), such as a chemical plating waste liquid. Conventional technology Conventionally, to recover EDTA from EDTA waste liquid,
Adjust the pH using mineral acids, Na 4 Y, Na 3 HY,
The EDTA sodium salt present as Na 2 H 2 and NaH 3 Y is crystallized as an insoluble free acid H 4 Y, followed by solid-liquid separation. In this recovery method, a stirrer is attached to the crystallization tank, and while stirring and mixing the EDTA waste liquid and the added acid, the pH 1 to 1, where the solubility of H 4 Y is lowest, is
The pH is lowered to 2 to precipitate H 4 Y and collect it. Problems to be solved by the invention However, in the case of such conventional methods,
The precipitated crystal grain size is as small as 0.05 to 0.1 cm, and many of the crystals have a dendrite shape, making subsequent solid-liquid separation difficult, requiring a large settling tank, and making it difficult to reuse the crystals. In the cleaning and dehydration steps required for this process, expensive acid-resistant high-speed centrifuges and the like had to be used to prevent crystal leakage and improve the cleaning effect. Furthermore, there was also the problem that a large amount of impurities were incorporated into the crystals, deteriorating the quality of recovery. In order to increase the grain size of EDTA, crystallization must be performed at a supersaturation degree in the metastable region where nucleation does not occur and only seed crystal growth occurs if seed crystals are present. However, in the conventional crystallization method,
Supersaturated solutions of EDTA tend to be unstable;
Due to the passage of time and extremely small disturbances in the flow of the liquid, many micronuclei were generated, making it impossible to increase the particle size. Therefore, the present invention overcomes the drawbacks of the prior art and continuously and efficiently converts H 4 Y from EPTA waste liquid.
The crystal grain size is large, the crystal shape is close to spherical, and by precipitating with high purity, the equipment for the subsequent solid-liquid separation, washing, and dehydration steps can be simplified, and H 4 Y crystals can be produced economically with a high recovery rate. The purpose of this study is to provide a method for recovering EDTA that can be used to recover EDTA. Means and Effects for Solving the Problems The present invention provides that when a dissolved EDTA sodium salt is crystallized as insoluble H 4 Y, a factor inhibiting the growth of the H 4 Y crystal is collision between the crystal and the stirring blade. It was confirmed through experiments that a large amount of micronuclei was generated due to the crushing of the crystals and the shearing action of the liquid by the stirring blades, and as a method to keep the crystals in a suspended state without using stirring blades, a part of the treated liquid was crystallized. This problem was solved by fluidizing the H 4 Y seed crystals by flowing them from the bottom of the tank. That is, the method for recovering EDTA according to the present invention is as follows:
A part of the processing liquid with a pH of 3 or less is flowed in from the bottom of the crystallization tank filled with H 4 Y seed crystals as a circulating liquid, and the seed crystals are flowed down in an upward flow.
It is characterized by supplying EDTA waste liquid to perform crystallization, and extracting H 4 Y crystals that have grown to a predetermined particle size from the bottom. In the present invention, supersaturation is produced by mixing the stock solution and a portion of the processing solution at the bottom of the crystallization tank, where the seed crystals are fluidized. In the method of the present invention, it is preferable to adjust the flow rate of the EDTA waste liquid and/or treatment liquid so that the degree of supersaturation (solution concentration - saturation concentration) of H 4 Y at the bottom of the crystallization tank is 5000 mg/or less. The temperature in the crystallization tank has a great influence on the growth of crystals, and the higher the temperature, the faster the growth rate and the ability to suppress the generation of micronuclei, and the temperature is generally preferably 20 to 80°C. Next, the present invention will be explained based on the drawings. FIG. 1 is a flow sheet of an apparatus for carrying out the method of the present invention. In Figure 1, the EDTA waste liquid is
The raw material flows into the crystallization tank 2 from the raw material supply pipe 1 . The crystallization tank 2 is filled with H 4 Y crystals 3, and furthermore,
Circulating fluid 9 flows in from the bottom to maintain the H 4 Y crystals 3 in a floating state. The processing liquid is introduced into the PH adjustment tank 5 from the upper part of the crystallization tank 2, and is discharged from the processing liquid piping 11. At this time, a part of the processing liquid is used as a circulating liquid, so a PH meter is used. 6, and if the PH of the processing liquid is higher than 3, the solenoid valve 12
Open and check that the pH of the processing solution is 3 or less, preferably 0.5~
Acid is supplied from acid supply pipe 4 so that the concentration is 2.5.
A part of the processing liquid adjusted to have a pH of 3 or less is caused to flow into the crystallization tank 2 from the circulating liquid supply pipe 9 via the flow meter 8 by the circulation pump 7. The H 4 Y crystals grown to a predetermined grain size in this way are transported to the crystal extraction pipe 10.
extract it from Although a conical crystallization tank is shown in the drawing, good crystals can be similarly obtained by using a cylindrical or multistage cylindrical crystallization tank. Example Using the apparatus shown in the drawing, which has a conical crystallization tank with a height of 3 m and a constant porosity, the EDTA concentration was
26,000mg/H 4 Y equivalent from EDTA waste liquid
An experiment was conducted to recover EDTA. At that time, the crystallization tank was filled with H 4 Y crystals having a particle size of about 0.2 mm as seed crystals. The stock solution was introduced from the bottom of the crystallization tank, and sulfuric acid was added so that the pH of the liquid at the top of the crystallization tank was 0.5 to 2.5, and this was made to flow into the bottom of the crystallization tank as a circulating liquid. The relationship between the H 4 Y supersaturation degree and the temperature in the tank, the average particle size of the extracted H 4 Y crystals, and the generation of micronuclei was measured, and the results are shown in the table below.
【表】
この実験結果から、H4Y結晶の平均粒径を1.0
mm以上にするには、晶析槽底部のH4Y過飽和度
を5000mg／以下とし、この時の温度は20〜80℃
であるのが好ましいことが判つた。また、得られ
た結晶の形状は球形に近く、洗浄、脱水が容易で
あると共に、純度も高く、充分再利用可能な品質
を有していた。
発明の効果
本発明方法によれば、連続的にかつ効率的に
H4Y結晶の粒径を増大することができ、球形に
近い高純度の結晶としてEDTAを回収すること
ができ、後段の洗浄、脱水工程の機器を効率化か
つ簡素化することができる。更に、本発明方法に
よれば、微小核の発生が少ないので、結晶のリー
クも極めて少なく、回収率を向上できるので、設
備費及び回収費も大幅に低減することができる。[Table] From this experimental result, the average grain size of H 4 Y crystals is 1.0
mm or more, the H 4 Y supersaturation degree at the bottom of the crystallization tank should be 5000 mg/or less, and the temperature at this time should be 20 to 80℃.
It was found that it is preferable that In addition, the shape of the obtained crystals was close to spherical, making them easy to wash and dehydrate, as well as having high purity and sufficient reusability. Effects of the invention According to the method of the present invention, continuous and efficient
The particle size of the H 4 Y crystals can be increased, EDTA can be recovered as highly pure crystals with a nearly spherical shape, and the equipment for the subsequent washing and dehydration processes can be made more efficient and simple. Further, according to the method of the present invention, since the generation of micronuclei is small, leakage of crystals is also extremely small, and the recovery rate can be improved, so that equipment costs and recovery costs can be significantly reduced.
第１図は本発明方法を実施する装置のフローシ
ートである。
１……原液供給配管、２……晶析槽、３……
H4Y結晶、４……酸供給配管、５……PH調整槽、
８……流量計、９……循環液供給配管、１０……
結晶抜き出し配管。
FIG. 1 is a flow sheet of an apparatus for carrying out the method of the present invention. 1... Stock solution supply piping, 2... Crystallization tank, 3...
H 4 Y crystal, 4... acid supply piping, 5... PH adjustment tank,
8...Flowmeter, 9...Circulating fluid supply piping, 10...
Crystal extraction piping.
Claims (1)
を含む廃液に酸を添加してPHを３以下に調整し、
EDTAを遊離酸（H4Yと記す）として晶析させ
るEDTAの回収方法において、H4Yの種晶を充
填した晶析槽の底部からPH３以下の処理液の一部
を流入させ、上向流で種晶を流動化させると同時
に底部からEDTA廃液を供給して晶析を行い、
所定の粒径に成長したH4Yの結晶を底部から抜
き出すことを特徴とするEDTA廃液からの
EDTAの回収方法。 ２ 晶析槽上部のPHが0.5〜2.5になるように循環
液に添加する酸の量を制御する特許請求の範囲第
１項記載のEDTAの回収方法。 ３ 晶析槽の底部のH4Yの過飽和度（溶液濃度
−飽和濃度）が5000mg／以下になるように
EDTA廃液の流入量を調節する特許請求の範囲
第１項又は第２項記載のEDTAの回収方法。 ４ 晶析槽の温度を20〜80℃に保持する特許請求
の範囲第１項〜第３項のいずれか１項に記載の
EDTAの回収方法。[Claims] 1. Ethylenediaminetetraacetic acid (referred to as EDTA)
Add acid to the waste liquid containing , adjust the pH to 3 or less,
In an EDTA recovery method in which EDTA is crystallized as a free acid (denoted as H 4 Y), a portion of the treated solution with a pH of 3 or less is flowed from the bottom of a crystallization tank filled with H 4 Y seed crystals, and the upward flow is performed. At the same time, the seed crystals are fluidized by the flow, and EDTA waste liquid is supplied from the bottom to perform crystallization.
A method for extracting H 4 Y crystals that have grown to a predetermined particle size from the bottom of the EDTA waste liquid.
How to recover EDTA. 2. The EDTA recovery method according to claim 1, wherein the amount of acid added to the circulating fluid is controlled so that the pH at the top of the crystallization tank is 0.5 to 2.5. 3. So that the supersaturation degree (solution concentration - saturation concentration) of H 4 Y at the bottom of the crystallization tank is 5000 mg/or less.
3. The method for recovering EDTA according to claim 1 or 2, wherein the inflow amount of EDTA waste liquid is adjusted. 4. The method according to any one of claims 1 to 3, wherein the temperature of the crystallization tank is maintained at 20 to 80°C.
How to collect EDTA.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24017185A JPS62103050A (en) | 1985-10-28 | 1985-10-28 | Method of recovering edta from waste liquor of edta |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24017185A JPS62103050A (en) | 1985-10-28 | 1985-10-28 | Method of recovering edta from waste liquor of edta |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62103050A JPS62103050A (en) | 1987-05-13 |
| JPH0251541B2 true JPH0251541B2 (en) | 1990-11-07 |
Family
ID=17055534
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24017185A Granted JPS62103050A (en) | 1985-10-28 | 1985-10-28 | Method of recovering edta from waste liquor of edta |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62103050A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19619828A1 (en) * | 1996-05-16 | 1997-11-20 | Roger Noero | Process for the preparation of photographic baths from color processes |
| JP4669625B2 (en) * | 2001-03-30 | 2011-04-13 | オルガノ株式会社 | Crystallization reactor equipped with crystallization reaction component recovery means |
| JP4841738B2 (en) * | 2001-03-30 | 2011-12-21 | オルガノ株式会社 | Crystallization reactor filled with high specific gravity seed crystal and crystallization treatment method using the same |
| JP4669624B2 (en) * | 2001-03-30 | 2011-04-13 | オルガノ株式会社 | Crystallization reactor equipped with evaporative concentration means of treated water |
| CN103159637B (en) * | 2013-03-25 | 2015-09-09 | 国药集团化学试剂有限公司 | A kind of method promoting industrial disodium ethylene diamine tetraacetate quality |
-
1985
- 1985-10-28 JP JP24017185A patent/JPS62103050A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62103050A (en) | 1987-05-13 |
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