JP2003027275A - Method for electrochemically recovering heavy metal from fly ash - Google Patents
Method for electrochemically recovering heavy metal from fly ashInfo
- Publication number
- JP2003027275A JP2003027275A JP2001219262A JP2001219262A JP2003027275A JP 2003027275 A JP2003027275 A JP 2003027275A JP 2001219262 A JP2001219262 A JP 2001219262A JP 2001219262 A JP2001219262 A JP 2001219262A JP 2003027275 A JP2003027275 A JP 2003027275A
- Authority
- JP
- Japan
- Prior art keywords
- fly ash
- lead
- liquid
- copper
- zinc
- 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.)
- Granted
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、廃棄物の再資源化
技術として焼却飛灰、溶融飛灰から金属類、とりわけ
銅、鉛、カドミウム、亜鉛等の有害な金属類を電気化学
的に回収する方法に関する。通常、廃自動車、廃家電製
品などはシュレッダーにより破砕して金属を回収する
が、その際残ったシュレッダーダストは焼却減容し、発
生する焼却飛灰あるいは焼却飛灰をさらにプラズマなど
で溶融処理する。本発明は、このようにシュレッダーダ
ストの焼却の際に発生する焼却飛灰、あるいはこの焼却
飛灰の溶融の際に発生する溶融飛灰から、各種金属を分
離回収する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an electrochemical technique for recovering metals, particularly harmful metals such as copper, lead, cadmium and zinc, from incineration fly ash and molten fly ash as a technology for recycling waste. On how to do. Usually, scrapped automobiles, discarded home appliances, etc. are crushed by a shredder to recover metal, but the shredder dust remaining at that time is incinerated and reduced in volume, and the generated incinerated fly ash or incinerated fly ash is further melted by plasma etc. . The present invention relates to a method for separating and recovering various metals from incineration fly ash generated during incineration of shredder dust, or molten fly ash generated during melting of the incineration fly ash.
【０００２】[0002]
【従来の技術】ごみ焼却施設などから排出される飛灰中
には有害な金属類類が高濃度で含有されている。そのた
め、飛灰は厚生労働省の定めるつぎの４方法溶融法
セメント固化薬剤処理酸抽出のうちいずれかで中間
処理することが定められている。中間処理された飛灰は
最終処分地で埋め立て処分されるが、有害な金属類の除
去、浸出水中の塩類による悪影響、最終処分量の減容
化、あるいは金属類の再資源化の観点から、飛灰中の金
属類を回収する技術の確立が望まれている。例えば、湿
式処理によって金属を溶出し、次いで金属の種類ごとに
これを濃縮し、各金属を非鉄精錬用原料として使用でき
る程度の濃縮物として回収し、精錬する方法（特開平７
−１３８６３０号公報参照）などが提案されている。2. Description of the Related Art Fly ash discharged from a refuse incineration facility contains a high concentration of harmful metals. Therefore, it is stipulated that fly ash should be subjected to intermediate treatment by one of the following four methods defined by the Ministry of Health, Labor and Welfare, the melting method, cement solidification chemical treatment, and acid extraction. The fly ash after the intermediate treatment is landfilled at the final disposal site, but from the viewpoint of removing harmful metals, adverse effects of salts in leachate, reducing the volume of final disposal, or recycling metals, It is desired to establish a technology for recovering metals in fly ash. For example, a method of eluting a metal by a wet process, then concentrating the metal for each type of metal, recovering each metal as a concentrate enough to be used as a raw material for non-ferrous metal refining, and refining the metal (Japanese Patent Laid-Open No. HEI 7-18753).
No. 138630) is proposed.
【０００３】しかし、この方法では、金属溶出用の液に
高価な薬品を使用しなければならず、工程が複雑であ
り、加えて濃縮物が水酸化物や硫化物からなるスラッジ
であるため、容積が大きく、また有害物であることから
運搬面上多くの問題を抱えている。However, in this method, an expensive chemical must be used in the liquid for eluting the metal, the process is complicated, and the concentrate is sludge consisting of hydroxide or sulfide. Since it has a large volume and is a harmful substance, it has many problems in terms of transportation.
【０００４】[0004]
【発明が解決しようとする課題】本発明の課題は、シュ
レッダーダスト等の廃棄物を焼却した際に発生する焼却
飛灰、あるいは焼却飛灰をさらにプラズマなどで溶融し
た際に発生する溶融飛灰から、各種金属を効率よくかつ
簡単に分離回収することができる方法を提供することで
ある。An object of the present invention is to produce incinerated fly ash generated when incinerating waste such as shredder dust, or molten fly ash produced when the incinerated fly ash is further melted by plasma or the like. Therefore, it is to provide a method capable of efficiently and easily separating and recovering various metals.
【０００５】[0005]
【課題を解決するための手段】本発明は、飛灰をｐＨ４
以下の硫酸水溶液で抽出処理して同液に銅、カドミウム
および亜鉛を溶出させ、生じた飛灰含有スラリーの固液
分離により得られた分離液中で陽極と陰極の間で電気分
解を行い、陰極電位を徐々にまたは段階的に負の方向に
変化させることにより、陰極に銅、カドミウムおよび亜
鉛を分別して電解析出させ、その後、上記固液分離で残
った残渣をチオ硫酸ソーダやチオ硫酸カリウムのような
チオ硫酸塩の水溶液で抽出処理して同液に鉛を溶出さ
せ、生じた残渣含有スラリーの固液分離により得られた
分離液中で陽極と陰極の間に直流電力をかけて、液中の
鉛を硫化鉛として沈殿させることを特徴とする飛灰から
の重金属の電気化学的回収方法である。According to the present invention, fly ash is adjusted to pH 4
Copper, cadmium and zinc are eluted in the same solution by extraction with the following sulfuric acid aqueous solution, and electrolysis is performed between the anode and the cathode in the separated liquid obtained by solid-liquid separation of the resulting fly ash-containing slurry, By gradually or stepwise changing the cathode potential in the negative direction, copper, cadmium and zinc are separated and electrolytically deposited on the cathode, and then the residue remaining in the above solid-liquid separation is treated with sodium thiosulfate or thiosulfate. Extraction treatment with an aqueous solution of thiosulfate such as potassium was used to elute lead in the same solution, and DC power was applied between the anode and cathode in the separation liquid obtained by solid-liquid separation of the resulting residue-containing slurry. The method for electrochemically recovering heavy metals from fly ash is characterized by precipitating lead in liquid as lead sulfide.
【０００６】本発明者らは、飛灰中の金属類の分離回収
を行うために鋭意研究を進めた結果、先に、各種飛灰中
の重金属を塩酸酸性水溶液などで溶出した後、各種金属
の電気化学的析出電位に差異がある点を利用し、陰極電
位を貴な電位から卑な電位へ徐々にまたは段階的に変化
させ、銅、鉛、カドミウム、亜鉛等の重金属を金属イン
ゴットの形態で析出させることが可能であることを知見
した（特願２０００−３７０８７７号明細書）。また、
その改良発明として、ｐＨ１以上の水溶液で飛灰中の
銅、カドミウム、亜鉛などの重金属を抽出した後に、各
種金属の電気化学的析出電位に差異がある点を利用し、
陰極電位を貴な電位から卑な電位へ段階的に移行させ、
銅、カドミウムおよび亜鉛を電解析出させた後、ｐＨを
１以下にして鉛を抽出し、抽出液の電気分解で鉛を析出
させる方法を見出した（特願２００１−００３３８４号
明細書）。さらに、その改良発明として、飛灰からｐＨ
１２以上の水溶液で鉛と亜鉛を抽出した後に、各種金属
の電気化学的析出電位に差異がある点を利用し、陰極電
位を貴な電位から卑な電位へ段階的に移行させ、鉛、亜
鉛を電解析出させた後、ｐＨ１２以上で抽出できなかっ
た銅、カドミウムを含む残渣をｐＨ１〜５にして銅、カ
ドミウムを抽出させ、貴な電位から卑な電位へ電位を段
階的に移行させ、銅、カドミウムを電解析出させる方法
を見出した（特願２００１−０３７８１９号明細書）。The present inventors have conducted extensive research to separate and recover metals in fly ash. As a result, the heavy metals in various fly ash were first eluted with hydrochloric acid acidic aqueous solution and then various metals were extracted. By utilizing the difference in the electrochemical deposition potential of, the cathode potential is gradually or gradually changed from a noble potential to a base potential, and heavy metals such as copper, lead, cadmium, and zinc are formed into a metal ingot. It has been found that it is possible to precipitate it by (Japanese Patent Application No. 2000-370877). Also,
As an improved invention, utilizing the fact that after extracting heavy metals such as copper, cadmium, and zinc in fly ash with an aqueous solution of pH 1 or more, there is a difference in the electrochemical deposition potential of various metals,
The cathode potential is gradually shifted from the noble potential to the base potential,
We have found a method of electrolytically depositing copper, cadmium and zinc, then adjusting the pH to 1 or less to extract lead, and electrolyzing the extract to deposit lead (Japanese Patent Application No. 2001-003384). Furthermore, as an improved invention, the pH from fly ash
After extracting lead and zinc with an aqueous solution of 12 or more, utilizing the fact that there are differences in the electrochemical deposition potentials of various metals, the cathode potential is gradually shifted from a noble potential to a base potential, and lead and zinc are extracted. After electrolytically depositing, the residue containing copper and cadmium that could not be extracted at pH 12 or higher was adjusted to pH 1 to 5 to extract copper and cadmium, and the potential was gradually transferred from the noble potential to the base potential, A method for electrolytically depositing copper and cadmium was found (Japanese Patent Application No. 2001-037819).
【０００７】ここで、飛灰中の重金属の内で廃棄規制の
観点から重要なものは、鉛と亜鉛の回収であり、これら
を分別して回収することが重要である。Here, among the heavy metals in the fly ash, the important one from the viewpoint of waste regulation is the recovery of lead and zinc, and it is important to separate and recover them.
【０００８】一番目と二番目の発明では、いずれも酸性
水溶液で抽出を行うが、薬剤として硫酸を使用すると不
溶性の硫酸鉛が析出するため、これを以後の電解析出へ
供することができない。従ってこの場合には必然的に塩
酸あるいは硝酸を使用することになるが、この場合は抽
出液を電解すると有害な塩素ガスや、亜硝酸ガスが発生
する問題が生ずる。また、三番目の発明では、ｐＨ１２
以上の水溶液で抽出をする場合に、苛性ソーダなどの薬
剤がアルミニウムや鉄の抽出のためにも多量に消費され
てしまいコスト高を招く上に、抽出した鉛と亜鉛を電解
する場合に、陰極電圧を制御しても一部は鉛と亜鉛の合
金として電解析出し、析出物の資源価値が落ちるという
問題があった。In both the first and second inventions, the extraction is carried out with an acidic aqueous solution. However, when sulfuric acid is used as a chemical, insoluble lead sulfate is deposited, so that it cannot be subjected to subsequent electrolytic deposition. Therefore, in this case, hydrochloric acid or nitric acid is inevitably used, but in this case, when the extract is electrolyzed, harmful chlorine gas or nitrous acid gas is generated. Further, in the third invention, pH12
When extracting with the above aqueous solution, chemicals such as caustic soda are consumed in large amounts for the extraction of aluminum and iron, leading to high costs, and when electrolyzing the extracted lead and zinc, the cathode voltage However, there is a problem that a part of the alloy is electrolytically deposited as an alloy of lead and zinc and the resource value of the deposit is reduced.
【０００９】本発明においては、飛灰抽出処理用の酸と
してｐＨ４以下の硫酸水溶液を使用するので、抽出液に
は鉛が含まれず、電解析出した亜鉛は鉛を含まない。ま
た、電解を硫酸水溶液で行うので、電解中には有害な塩
素ガスや亜硝酸ガスが発生しない。さらに、硫酸抽出後
の残渣にはＰｂＳＯ４、ＣａＳＯ４、アルミナ、シリカ
しか残っていないので、鉛を抽出する場合の薬剤使用量
が少なくてすむ。In the present invention, since an aqueous sulfuric acid solution having a pH of 4 or less is used as the acid for the fly ash extraction treatment, the extract does not contain lead, and the electrolytically deposited zinc does not contain lead. Further, since the electrolysis is carried out with a sulfuric acid aqueous solution, no harmful chlorine gas or nitrous acid gas is generated during the electrolysis. Furthermore, since only PbSO 4 , CaSO 4 , alumina, and silica remain in the residue after extraction with sulfuric acid, the amount of chemicals used for extracting lead can be small.
【００１０】本発明においては、また、固液分離で残っ
た残渣をチオ硫酸塩水溶液で抽出処理して同液に鉛を溶
出させ、生じた残渣含有スラリーの固液分離により得ら
れた分離液中で陽極と陰極の間に直流電力をかけて、液
中の鉛を硫化鉛として沈殿させるので、錯体の形態で溶
解していた鉛イオンがチオ硫酸塩中のイオウと非常に高
い効率で反応を起こして硫化鉛を生じる。この反応は水
溶液中の鉛イオン濃度が１０−５ｍｏｌ／ｌ以下まで高
い効率で進行する。また、従来の発明と同様に、硫酸水
溶液中で銅、亜鉛およびカドミウムの電解析出を行う
と、電解析出反応が進行するにつれて水溶液中の金属イ
オンの濃度が薄くなり、析出に関する電流効率が低下す
るので、電解析出により溶液中の金属イオン濃度を減少
させる際の目安を１０−４〜１０−２ｍｏｌ／ｌ程度に
置き、あまり低い濃度まで反応を行わないで、低濃度の
金属イオンを含有する水溶液を循環再利用する。In the present invention, the residue remaining in the solid-liquid separation is subjected to an extraction treatment with an aqueous thiosulfate solution to elute lead in the same solution, and a separation liquid obtained by solid-liquid separation of the resulting residue-containing slurry. Since DC power is applied between the anode and the cathode to precipitate lead in the liquid as lead sulfide, the lead ions dissolved in the form of a complex react with sulfur in thiosulfate with extremely high efficiency. Causes lead sulfide. This reaction proceeds with high efficiency until the lead ion concentration in the aqueous solution is 10 −5 mol / l or less. Further, similarly to the conventional invention, when electrolytic deposition of copper, zinc and cadmium is performed in a sulfuric acid aqueous solution, the concentration of metal ions in the aqueous solution becomes thin as the electrolytic deposition reaction proceeds, and the current efficiency related to deposition is reduced. Therefore, the standard for reducing the metal ion concentration in the solution by electrolytic deposition is set at about 10 −4 to 10 −2 mol / l, and the reaction is not performed to a too low concentration, and the low concentration of metal ion is reduced. The aqueous solution containing is recycled.
【００１１】また、当然ながら硫化鉛の析出後に濾過し
た残液（チオ硫酸ソーダ、チオ硫酸カリウムなどのチオ
硫酸塩を含む液）も循環再使用することができる。Of course, the residual liquid (a liquid containing thiosulfates such as sodium thiosulfate and potassium thiosulfate) filtered after the deposition of lead sulfide can be reused by circulation.
【００１２】本方法によると、本方法によると、析出に
関する電流効率を下げずに効率よく電解析出を行うこと
ができる。According to this method, electrolytic deposition can be carried out efficiently without lowering the current efficiency relating to deposition.
【００１３】[0013]
【発明の実施の形態】第１工程で、抽出槽で飛灰を水の
添加によりスラリーとし、このスラリーを攪拌しながら
硫酸水溶液を添加してｐＨを４以下にする。ここで、硫
酸の添加でｐＨを４以下にするのは、銅、カドミウムお
よび亜鉛を溶解させるが、鉛は溶解させないためであ
る。上記ｐＨを維持しての攪拌時間は、３０分以上であ
ればよく、温度は室温でもよいが溶解速度を促進するた
めには５０℃以上にするのが望ましい。次いで、上記ス
ラリーを濾過槽やフィルタープレスなどの濾過装置で濾
過して固液分離する。BEST MODE FOR CARRYING OUT THE INVENTION In the first step, fly ash is made into a slurry by adding water in an extraction tank, and an aqueous sulfuric acid solution is added to the slurry while stirring the slurry to adjust the pH to 4 or less. Here, the reason why the pH is adjusted to 4 or less by adding sulfuric acid is that copper, cadmium and zinc are dissolved but lead is not dissolved. The stirring time while maintaining the above pH may be 30 minutes or longer, and the temperature may be room temperature, but it is preferably 50 ° C. or higher in order to accelerate the dissolution rate. Next, the slurry is filtered with a filtering device such as a filter tank or a filter press to perform solid-liquid separation.
【００１４】第２工程では、濾液を陽極と陰極との間で
電気分解により銅、カドミウムおよび亜鉛を析出させ
る。ここで、陽極としては、チタンあるいは白金めっき
したチタンからなる電極を使用し、陰極としては、銅の
電解析出時には銅電極を、カドミウムの電解析出時には
アルミニウム電極を、亜鉛の電解析出時にはチタン電極
を使用する。さらに、電解析出により溶液中の金属イオ
ン濃度を減少させる際の目安を１０−４〜１０−２ｍｏ
ｌ／ｌ程度に置き、あまり低い濃度まで反応させないよ
うにする。なぜなら、溶液中の金属イオン濃度が１０
−４ｍｏｌ／ｌ以下になると、電流効率が２０％以下と
小さくなるからである。In the second step, copper, cadmium and zinc are deposited on the filtrate by electrolysis between the anode and the cathode. Here, as the anode, an electrode made of titanium or platinum-plated titanium is used, and as the cathode, a copper electrode is used for electrolytic deposition of copper, an aluminum electrode is used for electrolytic deposition of cadmium, and an electrolytic electrode of zinc is used for electrolytic deposition of zinc. Use titanium electrodes. Furthermore, a guideline for reducing the metal ion concentration in the solution by electrolytic deposition is 10 −4 to 10 −2 mo.
Place it at about 1 / l so that it does not react to a too low concentration. Because the metal ion concentration in the solution is 10
This is because if it is -4 mol / l or less, the current efficiency is reduced to 20% or less.
【００１５】第３工程では、第１工程で固液分離した後
の残査から、チオ硫酸ソーダ、チオ硫酸カリウムなどの
チオ硫酸塩を含む液を用いて鉛を抽出する。In the third step, lead is extracted from the residue obtained after the solid-liquid separation in the first step using a solution containing thiosulfate such as sodium thiosulfate and potassium thiosulfate.
【００１６】第４工程では、第３工程で抽出により生じ
た残渣含有スラリーの固液分離により得られた分離液中
で陽極と陰極の間に直流電力をかけて、液中の鉛とイオ
ウを反応させて、硫化鉛を析出させる。直流電力をかけ
る際に、陽極にはチタンあるいは白金めっきしたチタン
からなる電極を使用し、陰極にはチタン、ステンレス鋼
または炭素鋼からなる電極を使用するのが望ましい。本
反応は、錯イオンであるＰｂ（Ｓ２ Ｏ３ ）３ ４＋
イオンが陰極上で分解反応してＰｂＳに変化するものと
考えられる。In the fourth step, DC power is applied between the anode and the cathode in the separated liquid obtained by solid-liquid separation of the residue-containing slurry produced in the third step to remove lead and sulfur in the liquid. React to precipitate lead sulfide. When applying DC power, it is desirable to use an electrode made of titanium or platinum-plated titanium for the anode and an electrode made of titanium, stainless steel or carbon steel for the cathode. This reaction is a complex ion of Pb (S 2 O 3 ) 3 4+
It is considered that the ions are decomposed on the cathode and converted into PbS.
【００１７】第５工程では、第２工程により銅、カドミ
ウムおよび亜鉛の回収を終えた後の、これらの金属イオ
ン濃度が１０−４ｍｏｌ／ｌ以下になった液を第１工程
の飛灰の抽出に、第４工程により鉛の回収を終えた後
の、鉛イオン濃度が１０−５ｍｏｌ／ｌ以下になった液
を第３工程の残渣の抽出にそれぞれ循環再使用して、新
たな飛灰に対し、第１〜第４工程を行う。なお、このよ
うな操作を繰り返し行うと、アルミニウム、カリウム、
ナトリウムなどは次第に濃縮してこれら自身の溶解度ま
で達して、第４工程において自然に溶解しなくなる。ま
た、鉄、クロムはカドミウムめっき時に合金鍍金として
析出する。In the fifth step, after the copper, cadmium and zinc have been recovered in the second step, the liquid containing these metal ions at a concentration of 10 -4 mol / l or less is used as a fly ash in the first step. After extraction of lead in the fourth step, the liquid having a lead ion concentration of 10 −5 mol / l or less was circulated and reused in the extraction of the residue in the third step to extract a new fly. The first to fourth steps are performed on the ash. If such an operation is repeated, aluminum, potassium,
Sodium and the like are gradually concentrated and reach the solubility of themselves, so that they do not spontaneously dissolve in the fourth step. Further, iron and chromium are deposited as alloy plating during cadmium plating.
【００１８】つぎに、本発明を実施例に基づいて具体的
に説明する。Next, the present invention will be specifically described based on examples.
【００１９】実施例
（第１工程）まず、５００ｍｌビーカーに溶融飛灰２０
ｇを入れ、その中に１Ｎ硫酸水溶液を２００ｍｌ入れて
全体を５０℃で１時間攪拌し、生じたスラリーを固液分
離した。得られた分離液のｐＨは１．２であった。Example (First Step) First, molten fly ash 20 was placed in a 500 ml beaker.
g was added, 200 ml of a 1N sulfuric acid aqueous solution was added, and the whole was stirred at 50 ° C. for 1 hour, and the resulting slurry was subjected to solid-liquid separation. The pH of the obtained separated liquid was 1.2.
【００２０】（第２工程）その後、分離液中に、陽極と
して面積５０ｃｍ２ の白金めっきしたチタン電極を、
陰極として面積５０ｃｍ２ の銅板を入れて、２．５Ａ
の一定電流で電解を行った。その時、陰極電位は−０．
２３Ｖ（ｖｓ．標準水素電位）から−０．３０Ｖ（ｖ
ｓ．標準水素電位）まで徐々に低下し、銅の濃度は表１
に示すように０．１７（ｇ／ｌ）から０．０１２（ｇ／
ｌ）まで減少した。(Second step) Thereafter, a platinum electrode having a surface area of 50 cm 2 and being platinum-plated was used as an anode in the separated liquid.
Put a copper plate with an area of 50 cm 2 as a cathode, and
Electrolysis was carried out at a constant current. At that time, the cathode potential was −0.
23 V (vs. standard hydrogen potential) to -0.30 V (v
s. The standard hydrogen potential) gradually decreases, and the copper concentration is shown in Table 1.
As shown in 0.17 (g / l) to 0.012 (g / l)
l).
【００２１】その後、陰極を面積５０ｃｍ２ のチタン
電極に変えて同じく２．５Ａの一定電流で電解を行っ
た。その時、陰極電位は−１．２９Ｖ（ｖｓ．標準水素
電位）から−１．３８Ｖ（ｖｓ．標準水素電位）まで徐
々に低下し、亜鉛の濃度は表１に示すように３．４５
（ｇ／ｌ）から０．０４８（ｇ／ｌ）まで減少した。After that, the cathode was changed to a titanium electrode having an area of 50 cm 2 , and electrolysis was performed at the same constant current of 2.5 A. At that time, the cathode potential gradually decreased from −1.29 V (vs. standard hydrogen potential) to −1.38 V (vs. standard hydrogen potential), and the zinc concentration was 3.45 V as shown in Table 1.
(G / l) to 0.048 (g / l).
【００２２】（第３工程）第１工程で固液分離した後の
固体残渣７．８ｇを５００ｍｌのビーカーに入れ、その
中に、１Ｎチオ硫酸ソーダ水溶液を１７０ｍｌ入れて５
０℃で１時間攪拌し、生じたスラリーを固液分離した。
得られた分離液のｐＨは５．４であった。(Third step) 7.8 g of the solid residue obtained after the solid-liquid separation in the first step was put into a 500 ml beaker, and 170 ml of 1N sodium thiosulfate aqueous solution was put thereinto for 5 times.
The resulting slurry was stirred for 1 hour at 0 ° C., and the resulting slurry was subjected to solid-liquid separation.
The pH of the obtained separated liquid was 5.4.
【００２３】（第４工程）第３工程で得た分離液中に、
陽極として面積５０ｃｍ２ の白金めっきしたチタン電
極を、陰極として面積５０ｃｍ２ のチタン電極を入れ
て、２．５Ａの一定電流で電解を行った。その時、陰極
電位は−１．２〜１．３Ｖ（ｖｓ．標準水素電位）まで
徐々に低下し、鉛の濃度は表１に示すように１．４８
（ｇ／ｌ）から０．００５（ｇ／ｌ）まで減少した。ま
た、電流効率も９５％以上を示し、鉛の苛性ソーダ水溶
液から電解析出させる場合の電流効率５０％と比較して
かなりの効率向上が見られた。(Fourth step) In the separated liquid obtained in the third step,
The platinum plated titanium electrode with an area of 50 cm 2 as the anode, put the titanium electrode with an area of 50 cm 2 as a cathode, subjected to electrolysis at a constant current of 2.5A. At that time, the cathode potential gradually decreased to -1.2 to 1.3 V (vs. standard hydrogen potential), and the lead concentration was 1.48 as shown in Table 1.
(G / l) to 0.005 (g / l). Further, the current efficiency was 95% or more, showing a considerable improvement in efficiency as compared with the current efficiency of 50% when electrolytically depositing a caustic soda aqueous solution of lead.
【００２４】（第５工程）第２工程により銅、カドミウ
ムおよび亜鉛の回収を終えた後の、これらの金属イオン
濃度が１０−４ｍｏｌ／ｌ以下になった液を第１工程の
飛灰の抽出に、第４工程により鉛の回収を終えた後の、
鉛イオン濃度が１０−５ｍｏｌ／ｌ以下になった液を第
３工程の残渣の抽出にそれぞれ循環再使用して、新たな
飛灰に対し、第１〜第４工程を行った。その場合、２回
目溶出液、２回目電解後液も１回目と同様に溶出および
電解ができた。このような操作を繰り返し行ったとこ
ろ、５回目以降では、溶出液中のカドミウム濃度が高く
なり、カドミウムの電解が可能となったので、銅の電解
時に−０．４２Ｖ（ｖｓ．標準水素電位）になった時点
で陰極を面積５０ｃｍ２ のアルミニウム板に変更して
−１．０３Ｖ（ｖｓ．標準水素電位）になるまで２．５
Ａの電流で電解を行った。各溶出操作時の収率は９０％
以上、電解操作時の効率は６０％以上であり、飛灰から
効率的に重金属を回収できることが明らかになった。(Fifth Step) After the completion of the recovery of copper, cadmium and zinc in the second step, the liquid containing these metal ions at a concentration of 10 −4 mol / l or less is used as a fly ash in the first step. After extraction of lead in the fourth step,
The liquids having a lead ion concentration of 10 −5 mol / l or less were circulated and reused for extraction of the residue in the third step, and the first to fourth steps were performed on the new fly ash. In that case, the second eluate and the second post-electrolysis solution could be eluted and electrolyzed in the same manner as the first. When such an operation was repeated, the cadmium concentration in the eluate increased after the fifth time, and the electrolysis of cadmium became possible. Therefore, during the electrolysis of copper, -0.42 V (vs. standard hydrogen potential) was obtained. At that point, the cathode was changed to an aluminum plate having an area of 50 cm 2 and 2.5 was applied until it became −1.03 V (vs. standard hydrogen potential).
Electrolysis was performed at the current of A. 90% yield in each elution operation
As described above, the efficiency during the electrolysis operation was 60% or more, and it was revealed that heavy metals can be efficiently recovered from fly ash.
【００２５】[0025]
【表１】 [Table 1]
【００２６】[0026]
【発明の効果】本発明の方法によれば、飛灰から銅、カ
ドミウム、亜鉛、鉛等の重金属を効率的に回収すること
ができる。According to the method of the present invention, heavy metals such as copper, cadmium, zinc and lead can be efficiently recovered from fly ash.
【図１】実施例による飛灰からの重金属回収方法を示す
フローシートである。FIG. 1 is a flow sheet showing a method for recovering heavy metals from fly ash according to an embodiment.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｃ２５Ｃ 1/16 Ｂ０９Ｂ 3/00 ３０４Ｇ ＺＡＢ 1/18 Ｃ０２Ｆ 1/46 １０１Ｂ // Ｃ２２Ｂ 3/04 Ｃ２２Ｂ 3/00 Ａ 15/00 15/08 17/00 17/04 19/00 19/22 (72)発明者 近藤 雅芳 大阪市住之江区南港北１丁目７番89号 日 立造船株式会社内 (72)発明者 辰己 浩史 大阪市住之江区南港北１丁目７番89号 日 立造船株式会社内 Ｆターム(参考） 4D004 AA37 AB03 BA05 CA34 CA35 CA44 CC12 4D056 AB03 AB04 AB07 AB08 AC21 AC22 BA12 BA13 CA17 CA26 CA33 DA10 4D061 EA05 EB04 EB27 EB28 EB30 EB31 EB38 GB22 4K001 AA06 AA09 AA20 AA30 BA24 DB03 DB21 DB24 4K058 AA21 BA21 BA24 BA25 CA04 EC04 ED04 FC07 FC14 FC22─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI theme code (reference) C25C 1/16 B09B 3/00 304G ZAB 1/18 C02F 1/46 101B // C22B 3/04 C22B 3 / 00 A 15/00 15/08 17/00 17/04 19/00 19/22 (72) Inventor Masayoshi Kondo 1-789 South Kohoku, Minami Kohoku, Suminoe-ku, Osaka City (72) Inventor Hiroshi Tatsumi 1-89, Minami Kohoku, Suminoe-ku, Osaka City F-term (reference) within Nitto Shipbuilding Co., Ltd. EB28 EB30 EB31 EB38 GB22 4K001 AA06 AA09 AA20 AA30 BA24 DB03 DB21 DB24 4K058 AA21 BA21 BA24 BA25 CA04 EC04 ED04 FC07 FC14 FC22
Claims (4)
理して同液に銅、カドミウムおよび亜鉛を溶出させ、生
じた飛灰含有スラリーの固液分離により得られた分離液
中で陽極と陰極の間で電気分解を行い、陰極電位を徐々
にまたは段階的に負の方向に変化させることにより、陰
極に銅、カドミウムおよび亜鉛を分別して電解析出さ
せ、その後、上記固液分離で残った残渣をチオ硫酸ソー
ダ塩水溶液で抽出処理して同液に鉛を溶出させ、生じた
残渣含有スラリーの固液分離により得られた分離液中で
陽極と陰極の間に直流電力をかけて、液中の鉛を硫化鉛
として沈殿させることを特徴とする飛灰からの重金属の
電気化学的回収方法。1. A fly ash is subjected to extraction treatment with a sulfuric acid aqueous solution having a pH of 4 or less to elute copper, cadmium and zinc in the same solution, and an anode is used in a separation liquid obtained by solid-liquid separation of the resulting fly ash-containing slurry. By performing electrolysis between the cathodes and gradually or gradually changing the cathode potential in the negative direction, copper, cadmium and zinc are separated and electrolytically deposited on the cathodes, and then the solid-liquid separation is performed. The residue was extracted with an aqueous solution of sodium thiosulfate to elute lead in the same solution, and DC power was applied between the anode and the cathode in the separated liquid obtained by solid-liquid separation of the resulting residue-containing slurry, A method for electrochemically recovering heavy metals from fly ash, which comprises precipitating lead in liquid as lead sulfide.
ムおよび亜鉛の回収を終えた後の液を飛灰の抽出に、鉛
の回収を終えた後の液を残渣の抽出にそれぞれ循環再使
用して、新たな飛灰に対し請求項１記載の方法を繰り返
すことを特徴とする飛灰からの重金属の電気化学的回収
方法。2. The liquid after recovery of copper, cadmium and zinc by the method according to claim 1 is recycled for extraction of fly ash, and the liquid after recovery of lead is recycled for extraction of residues, respectively. A method for electrochemically recovering heavy metals from fly ash, which comprises repeating the method according to claim 1 for new fly ash.
陽極にチタンあるいは白金めっきしたチタンからなる電
極を、陰極に、銅の電解析出時には銅電極を、カドミウ
ムの電解析出時にはアルミニウム電極を、亜鉛の電解析
出時にはチタン電極を順番に取り替えて用い、上記直流
電力をかけて鉛を硫化鉛として沈殿させる際には陰極と
してチタン、ステンレス鋼または炭素鋼からなる電極を
用いることを特徴とする飛灰からの重金属の電気化学的
回収方法。3. The invention according to claim 1 or 2,
The anode is made of titanium or platinum-plated titanium, the cathode is used as a copper electrode for electrolytic deposition of copper, the aluminum electrode is used for electrolytic deposition of cadmium, and the titanium electrode is used for electrolytic deposition of zinc. An electrochemical recovery method of heavy metals from fly ash, characterized in that an electrode made of titanium, stainless steel or carbon steel is used as a cathode when the lead is precipitated as lead sulfide by applying the DC power.
硝酸水溶液で抽出処理して同液に銅、鉛、カドミウム、
亜鉛およびカルシウムを溶出させ、生じた飛灰含有スラ
リーの固液分離により得られた抽出液にアルカリをｐＨ
７〜９まで添加し、銅、鉛、カドミウムおよび亜鉛を水
酸化物として沈殿させ、得られた沈殿物をｐＨ４以下の
硫酸水溶液で抽出処理して同液に銅、カドミウムおよび
亜鉛を溶出させ、生じた飛灰含有スラリーの固液分離に
より得られた分離液中で陽極と陰極の間で電気分解を行
い、陰極電位を徐々にまたは段階的に負の方向に変化さ
せることにより、陰極に銅、カドミウムおよび亜鉛を分
別して電解析出させ、その後、上記固液分離で残った残
渣をチオ硫酸ソーダ水溶液で抽出処理して同液に鉛を溶
出させ、生じた残渣含有スラリーの固液分離により得ら
れた分離液中で陽極と陰極の間に直流電力をかけて、液
中の鉛を硫化鉛として沈殿させることを特徴とする飛灰
からの重金属の電気化学的回収方法。4. Fly ash is extracted with a hydrochloric acid aqueous solution or a nitric acid aqueous solution having a pH of 4 or less, and copper, lead, cadmium,
Zinc and calcium were eluted, and the pH of alkali was added to the extract obtained by solid-liquid separation of the resulting fly ash-containing slurry.
7 to 9 are added to precipitate copper, lead, cadmium and zinc as hydroxides, and the resulting precipitate is extracted with a sulfuric acid aqueous solution having a pH of 4 or less to elute copper, cadmium and zinc in the same solution, Electrolysis is performed between the anode and the cathode in the separation liquid obtained by solid-liquid separation of the resulting fly ash-containing slurry, and the cathode potential is gradually or stepwise changed to the negative direction, whereby the copper , Cadmium and zinc are separated and electrolytically deposited, and then the residue remaining in the solid-liquid separation is subjected to extraction treatment with an aqueous sodium thiosulfate solution to elute lead, and solid-liquid separation of the resulting residue-containing slurry is performed. A method for electrochemically recovering heavy metals from fly ash, characterized in that direct current power is applied between an anode and a cathode in the obtained separated liquid to precipitate lead in the liquid as lead sulfide.
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| US8226813B2 (en) | 2006-08-29 | 2012-07-24 | Koganei Corporation | Method of purifying water and apparatus therefor |
| US8905242B2 (en) | 2012-05-25 | 2014-12-09 | John VanDeMierden | Ash processing and metals recovery systems and methods |
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2001
- 2001-07-19 JP JP2001219262A patent/JP3951041B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPWO2008018317A1 (en) * | 2006-08-08 | 2009-12-24 | 株式会社コガネイ | Water purification method and apparatus |
| JP4686605B2 (en) * | 2006-08-08 | 2011-05-25 | 株式会社コガネイ | Water purification method and apparatus |
| US8226813B2 (en) | 2006-08-29 | 2012-07-24 | Koganei Corporation | Method of purifying water and apparatus therefor |
| US8905242B2 (en) | 2012-05-25 | 2014-12-09 | John VanDeMierden | Ash processing and metals recovery systems and methods |
| US9573139B2 (en) | 2012-05-25 | 2017-02-21 | Pure Recovery Group, L.P. | Incineration byproduct processing systems and methods |
| CN113578916A (en) * | 2021-06-23 | 2021-11-02 | 常熟理工学院 | Method for realizing resource utilization of phosphogypsum by utilizing waste incineration fly ash |
| CN113578916B (en) * | 2021-06-23 | 2022-05-10 | 常熟理工学院 | Method for realizing resource utilization of phosphogypsum by utilizing waste incineration fly ash |
| CN115287466A (en) * | 2022-08-09 | 2022-11-04 | 云南奥宇环保科技有限公司 | Method for recovering cadmium by solvent extraction |
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