JP2006167564A - Method for separating metal ion - Google Patents

Method for separating metal ion Download PDF

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JP2006167564A
JP2006167564A JP2004362313A JP2004362313A JP2006167564A JP 2006167564 A JP2006167564 A JP 2006167564A JP 2004362313 A JP2004362313 A JP 2004362313A JP 2004362313 A JP2004362313 A JP 2004362313A JP 2006167564 A JP2006167564 A JP 2006167564A
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magnesium
metal ions
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waste water
concentration
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JP4548655B2 (en
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Fumio Noguchi
文男 野口
Koji Kakimoto
幸司 柿本
Takeshi Tachibana
武史 橘
Katsuzo Kawada
勝三 川田
Naotaka Sakamoto
尚孝 阪本
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Kyushu Institute of Technology NUC
Astec Irie Co Ltd
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Astec Irie Co Ltd
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    • 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
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recycling a magnesium alloy and resultingly effectively using magnesium or the magnesium alloy by establishing a method for removing toxic metals in waste water by using magnesium or the magnesium alloy and for recovering valuable metals. <P>SOLUTION: In the method for separating metal ions, an adsorbent consisting mainly of magnesium or the magnesium alloy is added to waste water containing metal ions, the metal ions are adsorbed on the layer of magnesium hydroxide formed on magnesium surface by the reaction of water with magnesium, and the metal ions are separated from the waste water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、有害な金属イオンあるいは有用な金属イオンを含む排水又は廃水から、これらの金属イオンを分離除去あるいは分離回収する方法に関する。 The present invention relates to a method for separating and removing or separating and recovering metal ions from wastewater or wastewater containing harmful metal ions or useful metal ions.

ゴミ焼却場、めっき工場、精練工場等の排水（以下、特に区別しない限り廃水、地下水、溶出液等金属イオンを含む水性液を意味する）には、人体に有毒な、例えば、水銀、鉛、カドミニウム、銅、砒素、ニッケル、クロム、銀等の重金属が含まれている。また、生物にとって猛毒の元素である砒素は、通常、熱水、熱気鉱床の旧鉱山廃水、温泉水や地熱発電所等の排温水等の地下水や、産業廃棄物、都市ゴミ焼却灰・飛灰、電気炉製鋼ダスト等にも含有されている。そして、これら金属の除去に当たっては、通常、金属イオンを含む排水あるいは金属イオンを溶出した排水から、金属を分離除去する方法が取られている。また、例えば、産業的に有用・有価な、亜鉛、銀、金、ニッケル、クロムの回収にも、通常、これらの金属イオンを溶出した排水から、金属を分離回収する方法が採用されている。 Wastewater from garbage incineration plants, plating factories, smelting factories, etc. (hereinafter, unless otherwise specified, means wastewater, groundwater, aqueous solutions containing metal ions such as eluate) are toxic to humans, such as mercury, lead, Heavy metals such as cadmium, copper, arsenic, nickel, chromium and silver are included. In addition, arsenic, an extremely toxic element for living organisms, is usually groundwater such as hot water, old mine wastewater from hot-air deposits, hot water from hot springs and geothermal power plants, industrial waste, municipal waste incineration ash and fly ash. It is also contained in electric furnace steelmaking dust and the like. In removing these metals, usually, a method of separating and removing metals from waste water containing metal ions or waste water from which metal ions are eluted is taken. For example, for recovering zinc, silver, gold, nickel, and chromium, which are useful and valuable industrially, usually, a method of separating and recovering metal from waste water from which these metal ions are eluted is employed.

これまで、金属イオンの分離方法としては、多くの方法が提案されている。例えば、比較的最近のものとして、特許文献１〜３が挙げられる。しかし、それぞれの方法には、一長一短があった。
特開２００４−２５１６６号公報 特開２００２−１１３４７３号公報 特開２００１−２５２６７５号公報 Until now, many methods have been proposed as a method for separating metal ions. For example, Patent Documents 1 to 3 are relatively recent examples. However, each method has advantages and disadvantages.
JP 2004-25166 A JP 2002-113473 A JP 2001-252675 A

近年、パソコン等のハウジングにマグネシウム合金が使用されるようになったが、マグネシウム合金のリサイクルが課題となっていることから、このことと、本発明者らが知見した、マグネシウムが水溶液中で変化生成するMg(OH)2が、種々の元素を吸着する能力があるという事実を組合わせて、本発明者らは、排水中の有害元素の除去、有価元素の回収という観点から、マグネシウム合金の有効活用について検討してきた。そして、ホウ素を除去する方法については、既に提案している（非特許文献１）。なお、特許文献４には、塩類濃度の高い排水に、マグネシウムイオンとして塩化マグネシウムあるいは硫酸マグネシウムの溶液を添加し、水酸化ナトリウム溶液でｐＨを１０．７〜１１．２に調節して、共沈法によってホウ素及びマグネシウムの不溶解物質を生成させ、これを固液分離してホウ素の除去を行う方法が提案されているが、後述のごとく、マグネシウムの金属を用いる本発明は、この方法とは異なるものである。
資源・素材学会九州支部「講演要旨集」５４−５６頁、平成１６年５月２８日 特開２００１−２２５０８１号公報 In recent years, magnesium alloys have been used in housings for personal computers and the like, but since recycling of magnesium alloys has become an issue, this and the present inventors have discovered that magnesium changes in aqueous solution. Combining the fact that the produced Mg (OH) 2 has the ability to adsorb various elements, the present inventors have developed a magnesium alloy from the viewpoint of removal of harmful elements in wastewater and recovery of valuable elements. We have examined effective utilization. A method for removing boron has already been proposed (Non-Patent Document 1). In Patent Document 4, a solution of magnesium chloride or magnesium sulfate as magnesium ions is added to waste water with a high salt concentration, and the pH is adjusted to 10.7 to 11.2 with a sodium hydroxide solution, thereby coprecipitation. A method has been proposed in which boron and magnesium insoluble substances are generated by a method, and the boron is removed by solid-liquid separation. However, as described later, the present invention using a magnesium metal is different from this method. Is different.
Japan Society of Natural Resources and Materials, Kyushu Branch, “Abstracts”, pages 54-56, May 28, 2004 JP 2001-225081 A

本発明の課題は、マグネシウム又はマグネシウム合金を用いた排水中の有害元素の除去、有価元素の回収の方法を確立することにより、マグネシウム合金のリサイクル、ひいてはマグネシウム又はマグネシウム合金の有効活用の方法を提供することにある。 An object of the present invention is to provide a method for recycling magnesium alloys, and thus effectively using magnesium or magnesium alloys, by establishing a method for removing harmful elements from wastewater using magnesium or magnesium alloys and recovering valuable elements. There is to do.

本発明者らは、マグネシウムは水溶液中で水と反応し、マグネシウムの表面にMg(OH)2が生成するが、この際に種々の元素を吸着する能力があることを知見し、排水中の有害元素の除去、有価元素の回収という観点から、マグネシウム合金の有効活用について検討してきた。即ち、本発明は、金属イオンを含む排水中に、マグネシウム又はマグネシウム合金を主成分とする吸着材を添加し、水とマグネシウムの反応によりマグネシウム表面に生成する水酸化マグネシウムの層に、該金属イオンを吸着させ、該金属イオンを排水から分離することを特徴とする金属イオンの分離方法である。 The inventors of the present invention have found that magnesium reacts with water in an aqueous solution to produce Mg (OH) 2 on the surface of magnesium, and at this time, has the ability to adsorb various elements, From the viewpoints of removing harmful elements and recovering valuable elements, we have studied the effective use of magnesium alloys. That is, the present invention adds an adsorbent containing magnesium or a magnesium alloy as a main component to waste water containing metal ions, and the metal ions are formed on the magnesium hydroxide layer formed on the magnesium surface by the reaction of water and magnesium. Is a method for separating metal ions, wherein the metal ions are separated from waste water.

本発明の方法は、今後多量の発生が予想されるMgスクラップの有効利用に活用できる。また、従来の各種方法に比べ、排水中の有害元素の除去効率又は有価元素の回収効率が高い。そして、吸着される元素の大部分は、Mg基材の表面のMg(OH)2層に固定化されるので、沈殿物の発生が少なく、沈殿濾過等の処理が軽減される。 The method of the present invention can be utilized for effective use of Mg scrap, which is expected to generate a large amount in the future. Moreover, the removal efficiency of harmful elements in waste water or the recovery efficiency of valuable elements is higher than various conventional methods. Since most of the elements to be adsorbed are immobilized on the Mg (OH) 2 layer on the surface of the Mg base, the generation of precipitates is small, and the processing such as precipitation filtration is reduced.

本発明は、金属イオンを含む廃水、地下水、溶出液等の排水中に、マグネシウム又はマグネシウム合金を主成分とする吸着材を添加し、水とマグネシウムの反応によりマグネシウム表面に生成する水酸化マグネシウムの層に、この金属イオンを吸着させ、この金属イオンを排水から分離除去あるいは分離回収する方法である。そして、本発明の対象とする有害あるいは有用・有価な金属イオンとしては、例えば、亜鉛、カドミウム、水銀、砒素、鉛、クロム、アルミニウム、スズ、アンチモン、マンガン、ニッケル、コバルト、金、銀、白金のイオンが挙げられる。中でも、特に、亜鉛族元素、即ち、周期表１２属の亜鉛、カドミウム、水銀のイオンが好適である。また、対象とする金属イオンとしては、両性元素、即ち、亜鉛、鉛、アルミニウム、スズ、アンチモン等のイオンも好適である。 In the present invention, an adsorbent mainly composed of magnesium or a magnesium alloy is added to wastewater containing metal ions, groundwater, eluate, etc., and magnesium hydroxide produced on the surface of magnesium by reaction of water and magnesium. In this method, the metal ions are adsorbed on a layer, and the metal ions are separated and removed from the waste water or separated and recovered. Examples of harmful or useful and valuable metal ions that are the subject of the present invention include, for example, zinc, cadmium, mercury, arsenic, lead, chromium, aluminum, tin, antimony, manganese, nickel, cobalt, gold, silver, and platinum. Ions. Among these, zinc group elements, that is, ions of zinc, cadmium, and mercury belonging to Periodic Table 12 are preferable. Further, as the target metal ion, amphoteric elements, that is, ions of zinc, lead, aluminum, tin, antimony and the like are also suitable.

本発明において用いられる吸着材は、マグネシウム又はマグネシウム合金を主成分とする材料からなる。マグネシウム合金は、マグネシウム成分を８５%以上含有する合金が好ましい。そして、特に、マグネシウムとAl、Ca、Zn、Mnの少なくとも１つとの合金であるものが好ましい。 The adsorbent used in the present invention is made of a material mainly composed of magnesium or a magnesium alloy. The magnesium alloy is preferably an alloy containing 85% or more of a magnesium component. In particular, an alloy of magnesium and at least one of Al, Ca, Zn, and Mn is preferable.

吸着材の形態は特に制限されるものではなく、例えば、マグネシウム又はマグネシウム合金の粉末、リボン、薄片状の形で、排水に混合して金属イオンを吸着させる。あるいは、マグネシウム又はマグネシウム合金を、多孔質のフィルターに加工して使用することもできる。フィルターは、マグネシウム又はマグネシウム合金粉末を用いて、多孔質に焼結したものでも良いし、あるいは、マグネシウム又はマグネシウム合金の繊維、リボン、薄片を無作為に堆積させた、いわゆる不織布の形でも良い。不織布は、必要に応じて焼結しても良い。本発明において、排水中に吸着剤を添加するとは、多孔質のフィルターや不織布形状の吸着剤に、排水を接触させるやり方も含むものである。 The form of the adsorbent is not particularly limited. For example, the adsorbent is mixed with waste water to adsorb metal ions in the form of magnesium or magnesium alloy powder, ribbon, flakes. Alternatively, magnesium or a magnesium alloy can be used by processing it into a porous filter. The filter may be sintered in a porous manner using magnesium or magnesium alloy powder, or may be in the form of a so-called nonwoven fabric in which magnesium, magnesium alloy fibers, ribbons, and flakes are randomly deposited. You may sinter a nonwoven fabric as needed. In the present invention, adding an adsorbent to the waste water includes a method of bringing the waste water into contact with a porous filter or a non-woven fabric adsorbent.

本発明においては、金属イオンを含む排水中に、マグネシウム又はマグネシウム合金を主成分とする吸着材を添加する際に、マグネシウムの濃度を高め、水酸化マグネシウムの生成量を高めるために、マグネシウムの塩類を添加しても良い。対象とする金属イオンの種類によっては、塩類の添加が好ましい場合もある。マグネシウム塩類としては、塩化マグネシウム、硫酸マグネシウム、又はそれらの混合物が好ましい。 In the present invention, when adding an adsorbent containing magnesium or a magnesium alloy as a main component to waste water containing metal ions, magnesium salts are used to increase the concentration of magnesium and increase the amount of magnesium hydroxide produced. May be added. Depending on the type of metal ion of interest, addition of salts may be preferred. As the magnesium salts, magnesium chloride, magnesium sulfate, or a mixture thereof is preferable.

本発明においては、金属イオンの種類と金属イオンを含む排水のpHによって、金属イオンの吸着と分離の状況が変化する。例えば、金属が亜鉛の場合、亜鉛イオンの疑似排水を使用し吸着実験を行った。亜鉛濃度を５０ppmと一定にし、溶液100ml分取し、まずpHを調整後、１〜２mm程度の切削片状の金属マグネシウムを1g添加して１時間撹拌した。このpHを初期pHとし、初期pH＝1〜13まで変化させた。その結果、初期pH＝1〜12までは、亜鉛イオンをほぼ100％回収できることがわかった。マグネシウムの添加方法について検討したところ、pH調整後に加えても、pH調整前に加えても回収率はほぼ100％と変わらなかった。これは、時間が１時間と長いことから、十分吸着されたものと考えられる。しかし、pH調整前にマグネシウムを添加すると、pH調整中にマグネシウムが溶解し反応が始まる。更に、高濃度の廃水を想定して、初期pH＝１と初期pH=６について、亜鉛濃度を100ppm、500ppmと濃度を高くした場合の亜鉛回収率を見ると、各溶液100mlに対し、切削片状の金属マグネシウムを1g添加した場合でも、完全に１００％回収できることがわかった。 In the present invention, the state of adsorption and separation of metal ions varies depending on the type of metal ions and the pH of the waste water containing the metal ions. For example, when the metal is zinc, an adsorption experiment was performed using simulated drainage of zinc ions. The zinc concentration was kept constant at 50 ppm, and 100 ml of the solution was collected. After adjusting the pH, 1 g of metal magnesium in the form of cut pieces of about 1 to 2 mm was added and stirred for 1 hour. This pH was taken as the initial pH, and the initial pH was varied from 1 to 13. As a result, it was found that almost 100% of zinc ions can be recovered up to the initial pH = 1-12. When the addition method of magnesium was examined, the recovery rate was almost the same as 100% whether added after pH adjustment or before pH adjustment. This is considered to be sufficiently adsorbed because the time is as long as 1 hour. However, if magnesium is added before the pH adjustment, the magnesium dissolves during the pH adjustment and the reaction starts. Furthermore, assuming high concentration wastewater, when the zinc recovery rate is increased to 100 ppm and 500 ppm for the initial pH = 1 and the initial pH = 6, the cutting piece is 100 It was found that even when 1 g of metallic magnesium in the form of 1% was added, 100% could be completely recovered.

金属が砒素の場合には、ｐH７以上の中性からアルカリ性の、砒素イオンを含む排水の場合に、有効、且つ、効率良く砒素が吸着除去される。 When the metal is arsenic, the neutral to alkaline drainage containing arsenic ions having a pH of 7 or higher is effectively and efficiently adsorbed and removed.

金属イオンを含む排水に吸着材を添加し処理する際の条件は、特に限定されるものではないが、通常は、１０〜３０℃の常温が適当である。また、処理系を適当に攪拌するのが好ましい。 Conditions for adding the adsorbent to the wastewater containing metal ions for treatment are not particularly limited, but usually a room temperature of 10 to 30 ° C. is appropriate. In addition, it is preferable to appropriately stir the treatment system.

本発明において、マグネシウム基材の表面のMg(OH)2層に吸着された有価金属は、マグネシウムと分離しなければならないが、このためには、金属の種類に応じて、適宜公知の方法を採用すれば良い。例えば、吸着された金属イオンが亜鉛の場合、マグネシウムも亜鉛も水酸化物あるいは酸化物の形態であろうと思われることから、一旦希硫酸で溶解した後、煮沸しながらH2Sガスを吹き込み、亜鉛をZnS沈殿として沈殿分離するか、希硫酸で溶解後、亜鉛精錬所に送り電解採取をする方法を採用できる。Mg(OH)2層に吸着された有害金属が溶出しない場合には、そのまま埋め立て等の廃棄処分にすることもできる。 In the present invention, the valuable metal adsorbed on the Mg (OH) 2 layer on the surface of the magnesium base material must be separated from the magnesium. For this purpose, a known method is appropriately used depending on the type of metal. Adopt it. For example, if the adsorbed metal ion is zinc, it seems that both magnesium and zinc will be in the form of hydroxide or oxide, so after dissolving with dilute sulfuric acid, H 2 S gas is blown in while boiling, It is possible to adopt a method in which zinc is precipitated and separated as ZnS precipitate, or dissolved in dilute sulfuric acid and then sent to a zinc smelter to perform electrowinning. If the toxic metal adsorbed on the Mg (OH) 2 layer does not elute, it can be disposed of as landfill.

［亜鉛の分離回収の例］
マグネシウム（以下Mg）による、疑似排水(Zn濃度：50ppm)中からの亜鉛（以下Zn）の回収率を、初期pHとの関係、及び、Mgの添加とpH調整の時期との関係で検討した。亜鉛濃度を５０ppmと一定にし、溶液100ml分取し、１〜２mm程度の切削片状の金属マグネシウムを1g添加して１時間撹拌した。 [Example of zinc separation and recovery]
The recovery rate of zinc (hereinafter Zn) from simulated wastewater (Zn concentration: 50 ppm) by magnesium (hereinafter Mg) was examined in relation to the initial pH and the relationship between the addition of Mg and the timing of pH adjustment. . The zinc concentration was kept constant at 50 ppm, 100 ml of the solution was taken, 1 g of metal magnesium in the form of a cut piece of about 1 to 2 mm was added and stirred for 1 hour.

図１は、pH調整後Mgを添加した場合の、初期pHの影響を示している。Zn吸着率は、初期pH＝１から１２までほぼ１００％、初期pH＝１３で約３０％、平衡pHは、初期pH＝２から１０までは、平衡pH＝１０と一定値を示していることがわかる。それ以上の初期pHでは、初期pHの増加と共に上昇した。Mgの重量変化は、pH＝２以上でわずかな重量増加を示すのに対し、pH＝１では−０.１ｇと著しい重量減を示した。これは、pHが低い、即ち酸濃度が高いためMgの溶解が促進したものと考えられる。この場合、著しい水素ガスの発生が観察された。 FIG. 1 shows the influence of the initial pH when Mg is added after pH adjustment. The Zn adsorption rate is almost 100% from the initial pH = 1 to 12, approximately 30% at the initial pH = 13, and the equilibrium pH is constant at the equilibrium pH = 10 from the initial pH = 2 to 10. I understand. At higher initial pH, it increased with increasing initial pH. The change in the weight of Mg showed a slight weight increase at pH = 2 or more, whereas it showed a significant weight loss of -0.1 g at pH = 1. This is considered to be because the dissolution of Mg was promoted because the pH was low, that is, the acid concentration was high. In this case, significant hydrogen gas evolution was observed.

図２は、pH調整後Mgを添加した場合の、溶液中のMgの濃度変化を示している。溶液中のMgの濃度変化は、pH＝１で1,500ppmと非常に高い値を示し、Mgが溶解していることがわかる。pH＝２から１０までは、ごくわずかな減少を示した。そして、pH＝１０以上ではMgの濃度変化は０であった。図１および図２を併せ考察すると、平衡pH、Mgの重量変化、溶液中のMgの濃度変化から、反応の様子は３つの範囲に分けられ、Znの吸着機構も３つのグループに分けられることがわかった。pH＝１の領域では、Mgの重量減が著しく、また、水素ガスの発生が激しいことから、水素ガス発生に伴うMg(OH)2の生成が考えられる。さらにpH＝２以上でも平衡pHの上昇から加水分解によるMg(OH)2の生成が考えられる。 FIG. 2 shows the change in the concentration of Mg in the solution when Mg was added after pH adjustment. The change in the concentration of Mg in the solution shows a very high value of 1,500 ppm at pH = 1, indicating that Mg is dissolved. From pH = 2 to 10, there was a slight decrease. And at pH = 10 or more, the change in Mg concentration was zero. Considering Fig. 1 and Fig. 2 together, the reaction state can be divided into three ranges and the adsorption mechanism of Zn can be divided into three groups based on equilibrium pH, change in Mg weight, and change in Mg concentration in solution. I understood. In the pH = 1 region, the weight loss of Mg is significant, and the generation of hydrogen gas is intense, so the production of Mg (OH) 2 accompanying the generation of hydrogen gas is considered. Furthermore, even if pH = 2 or higher, the production of Mg (OH) 2 by hydrolysis is considered from the increase in equilibrium pH.

図３は、Mgを添加した後pH調整した場合の、初期pHの影響を示している。Zn吸着率は、初期pH＝１から１２までほぼ１００％、初期pH＝１３で約８０％で、pH＝１から１２間でほぼ完全にZnを回収できることがわかった。平衡pHは、初期pH＝１で９に、初期pH＝２〜１０で平衡pH＝１０と一定値を示した。それ以上の初期pHでは、初期pHと同じ値を示した。液中のMg濃度は、pH＝１で3,000ppm、pH＝２で250ppm、それ以上で150ppm程度、pH＝１３で0ppmを示した。pH＝１で液中のMg濃度が非常に高いのは、Mgを添加した後pH調整したため、pH調整中にかなりのMgが溶解したものと推察される。 FIG. 3 shows the influence of the initial pH when the pH is adjusted after adding Mg. The Zn adsorption rate was almost 100% from the initial pH = 1 to 12, and about 80% at the initial pH = 13. It was found that Zn could be recovered almost completely between pH = 1 and 12. The equilibrium pH showed a constant value of 9 at the initial pH = 1, and the equilibrium pH = 10 at the initial pH = 2-10. At the initial pH higher than that, the same value as the initial pH was shown. The Mg concentration in the liquid was 3,000 ppm at pH = 1, 250 ppm at pH = 2, about 150 ppm above it, and 0 ppm at pH = 13. The reason why the Mg concentration in the solution is very high at pH = 1 is presumed that a considerable amount of Mg was dissolved during the pH adjustment because the pH was adjusted after adding Mg.

図４は、Mgを添加した後pH調整した場合の、Mgの重量変化を示している。Mgの重量変化は、初期pH＝１で著しい重量減を示した。その後、初期pHの増加と共にわずかな重量増加を示すことがわかる。試験後Mg表面のＸ線回折の結果、Mg表面にはMg(OH)2の生成が確認された。 FIG. 4 shows the change in the weight of Mg when the pH is adjusted after adding Mg. The weight change of Mg showed a significant weight loss at the initial pH = 1. It can then be seen that there is a slight weight increase with increasing initial pH. As a result of X-ray diffraction on the Mg surface after the test, the production of Mg (OH) 2 was confirmed on the Mg surface.

以上の実験から、Mgによる、疑似排水(Zn濃度：50ppm)中からのZnの回収率を、初期pHとの関係で求めると、pH=1から12までは、ほぼ100%回収できるが、pH=13では30%程度となり、Znを完全には回収出来ないことがわかった。Znの吸着率、Mgの溶出挙動、沈殿量などから、MgによるZnの吸着のメカニズムは、次のように、（ａ）pH=1〜2、（ｂ）pH=2〜10、（ｃ）pH=10以上の３つの領域に分けられることがわかった。 From the above experiment, when the recovery rate of Zn from simulated waste water (Zn concentration: 50 ppm) by Mg is calculated in relation to the initial pH, almost 100% can be recovered from pH = 1 to 12, but pH It was about 30% at = 13, indicating that Zn could not be recovered completely. From the adsorption rate of Zn, elution behavior of Mg, precipitation amount, etc., the mechanism of Zn adsorption by Mg is as follows: (a) pH = 1 to 2, (b) pH = 2 to 10, (c) It was found that it was divided into three regions with pH = 10 or more.

（ａ）pH=1〜2では、
Mg+2H+→Mg2++H2↑ ｛Mg→Mg2++2e、2H++2e→H2↑｝ （１）
Mg2++2OH−→Mg(OH)2↓ （２）
このpH領域では(1)式のようにMgが溶解する際にH2ガスの発生を伴う。そこで、Mgの周りではH+イオンが減少し、その代わりにOH-イオンが増加する。そのため(2)式のように加水分解が進行しMg(OH)2
が生成する。ここで生成したMg(OH)2に、Znが吸着されることにより、回収率が高かったものと考えられる。 (A) At pH = 1-2
Mg + 2H + → Mg 2+ + H 2 ↑ {Mg → Mg 2+ + 2e, 2H + + 2e → H 2 ↑} (1)
Mg 2+ + 2OH − → Mg (OH) 2 ↓ (2)
In this pH range, H 2 gas is generated when Mg dissolves as shown in equation (1). Therefore, H + ions decrease around Mg, and OH − ions increase instead. Therefore, hydrolysis proceeds as in formula (2) and Mg (OH) 2
Produces. It is considered that the recovery rate was high due to the adsorption of Zn to the Mg (OH) 2 produced here.

（ｂ）pH=2〜10では、(3)式、又は、(4)、(5)式のようにMg(OH)2のほか、MgOの生成が認められる。Znは(4)式で生成するMg(OH)2に吸着され、回収率がほぼ１００％を示したものと考えられる。
Mg+H2O→MgO↓+H2 （３）
Mg+2H2O→Mg(OH)2↓+H2 （４）
Mg(OH)2→MgO↓+H2O （５） (B) At pH = 2 to 10, formation of MgO is observed in addition to Mg (OH) 2 as in the formula (3) or the formulas (4) and (5). Zn is adsorbed by Mg (OH) 2 produced by the formula (4), and the recovery rate is considered to be almost 100%.
Mg + H 2 O → MgO ↓ + H 2 (3)
Mg + 2H 2 O → Mg (OH) 2 ↓ + H 2 (4)
Mg (OH) 2 → MgO ↓ + H 2 O (5)

（ｃ）pH=10以上では、アルカリ性が強いことから容易に加水分解し(3)〜(5)式のようにMg(OH)
2又はMgOが生成する。Znはここで生成したMg(OH) 2に吸着されるが、Zn吸着率はpH＝２〜１０領域に比べ低い値を示した。これはZnが両性金属であるため高アルカリ性領域で再溶解も進み、若干吸着率が低下したものと考えられる。 (C) At pH = 10 or higher, it is easily hydrolyzed due to its strong alkalinity, and Mg (OH) as shown in formulas (3) to (5)
2 or MgO is produced. Zn was adsorbed by the Mg (OH) 2 produced here, but the Zn adsorption rate was lower than that in the pH = 2-10 region. This is presumably because Zn is an amphoteric metal and remelting progressed in a highly alkaline region, and the adsorption rate slightly decreased.

［砒素の分離回収の例１］
Mgによる、疑似排水(As(３価、５価)濃度：２ppmおよび１０ppm)中からの砒素（以下As）の回収率を、初期pHとの関係、及び、Mgの添加とpH調整の時期との関係で検討した。先ず、例１の本実験では、As(３価)濃度を２ppmと一定にし、溶液100ml分取し、１〜２mm程度の切削片状の金属Mgを1g添加して１時間撹拌した。 [Example 1 of Arsenic Separation and Recovery]
The recovery rate of arsenic (hereinafter referred to as As) from simulated wastewater (As (trivalent, pentavalent) concentration: 2 ppm and 10 ppm) by Mg, the relationship with the initial pH, and the timing of Mg addition and pH adjustment The relationship was examined. First, in this experiment of Example 1, the As (trivalent) concentration was kept constant at 2 ppm, 100 ml of the solution was taken, 1 g of a piece of metal Mg of about 1 to 2 mm was added and stirred for 1 hour.

図５は、pH調整後Mgを添加した場合の、初期pHの影響を示している。As吸着率は、大体９０％前後で、初期pH＝１０以上で若干低下する程度である。平衡pHは、初期pH＝１０まではほぼ１０で一定値を示した。それ以上の初期pHでは、初期pHの増加と共に若干上昇した。Mgの重量変化は、初期pH＝１、２で高い値を示し、初期pHの上昇と共に低下し、pH＝３でほぼ０になった。これらのことから、初期pH＝１〜３まで、３〜１０まで、１０〜１２までと３つの領域でAsの吸着機構が異なることが予想される。 FIG. 5 shows the effect of the initial pH when Mg is added after pH adjustment. The As adsorption rate is about 90%, and is slightly reduced at an initial pH of 10 or more. The equilibrium pH was approximately 10 and showed a constant value until the initial pH = 10. At higher initial pH, it increased slightly with increasing initial pH. The change in the weight of Mg showed a high value at the initial pH = 1, 2 and decreased with an increase in the initial pH, and became almost zero at the pH = 3. From these facts, it is expected that the adsorption mechanism of As is different in three regions, that is, initial pH = 1-3, 3-10, and 10-12.

図６は、pH調整後Mgを添加した場合の、Mg添加量の影響を示している。Asの吸着率は、pH＝１２で影響が大であった。Mgの重量変化は、pH＝１、２で影響が大であった。pH＝６、１２では、Mgの溶出は起こらなかった。 FIG. 6 shows the influence of the amount of Mg added when Mg is added after pH adjustment. The adsorption rate of As was greatly affected at pH = 12. The change in the weight of Mg was greatly affected at pH = 1 and 2. At pH = 6 and 12, no elution of Mg occurred.

図７は、Mgを添加した後pH調整した場合の、初期pHの影響を示している。Asの吸着率は、初期pH＝１で８０％、pH＝２〜１１までほぼ１００％、初期pH＝１２で約２０％と低下した。初期pH＝１〜１０について平衡pHを調べてみると、ほぼ１０で一定値を示した。それ以上の初期pHでは、初期pHと同じ値を示した。液中のMg濃度は、pH＝１で3,000ppm、pH＝２で250ppm、それ以上で150ppm程度、pH＝１３で0ppmを示した。 FIG. 7 shows the influence of the initial pH when the pH is adjusted after adding Mg. The adsorption rate of As decreased to 80% at the initial pH = 1, almost 100% from pH = 2 to 11, and about 20% at the initial pH = 12. When the equilibrium pH was examined for the initial pH = 1 to 10, it showed a constant value of about 10. At the initial pH higher than that, the same value as the initial pH was shown. The Mg concentration in the liquid was 3,000 ppm at pH = 1, 250 ppm at pH = 2, about 150 ppm above it, and 0 ppm at pH = 13.

図８は、Mgを添加した後pH調整した場合の、Mgの重量変化を示している。Mgの重量変化は、初期pH＝１〜２では重量減が生じた。これは酸によるMgの溶解のためと考えられる。そこで、液中のMg濃度を測定すると、pH＝１で2,200ppm、pH＝３で40ppm、それ以上で15ppm程度、pH＝１１、１２で0ppmを示した。 FIG. 8 shows the change in the weight of Mg when the pH is adjusted after adding Mg. Regarding the change in the weight of Mg, weight loss occurred at the initial pH = 1-2. This is thought to be due to dissolution of Mg by acid. Therefore, when the Mg concentration in the liquid was measured, it showed 2,200 ppm at pH = 1, 40 ppm at pH = 3, about 15 ppm above it, and 0 ppm at pH = 11, 12.

全自動微少部分析装置ＥＰＭＡ(Electron Probe Micro Analyzer)によりMg表面に沈積した生成物の元素分析を行った。その結果も含めて以下に考察する。pH＝１の場合、沈殿物および、Mg表面にAsがかなり検出された。即ち、Mg金属表面の層状の析出物中に、Asの存在が確認された。これはpH＝６の場合もほぼ同様であった。しかし、pH＝１２の場合は、Asは極わずか検出され、しかも層状の膜とMg母材の間に存在していた。膜は、pH＝１、６の場合の膜とは異なり、Mgリッチな強硬な膜であった。この膜はMgとアルカリとの反応で、酸化膜MgOが生成したものと考えられる。Asは、造膜過程で膜とMg母材の間に出来るMg(OH)2層に吸着されるため、極わずかしか吸着されなかったものと考えられる。 Elemental analysis of the product deposited on the Mg surface was performed by a fully automated microanalyzer EPMA (Electron Probe Micro Analyzer). The results are discussed below. When pH = 1, considerable amount of As was detected on the precipitate and on the Mg surface. That is, the presence of As was confirmed in the layered precipitate on the Mg metal surface. This was almost the same when pH = 6. However, when pH = 12, As was detected in a very small amount, and was present between the layered film and the Mg base material. The membrane was a strong Mg-rich membrane unlike the membranes at pH = 1,6. This film is considered to be that the oxide film MgO was generated by the reaction between Mg and alkali. As is adsorbed on the Mg (OH) 2 layer formed between the film and the Mg base material during the film formation process, it is considered that As was adsorbed very little.

［砒素の分離回収の例２］
本実験例２では、As(３価)濃度を１０ppmと一定にし、溶液100mlを分取し、初期pH＝１に調整した後、１〜２mm程度の切削片状の金属マグネシウムを1g添加したときの、溶液中のAs濃度、アルシンガス（以下AsH3）発生量、並びにAsH3累積量、及び溶液中のAs濃度の変化を、撹拌時間に対して測定した。結果を図９に示した。 [Example 2 of Arsenic Separation and Recovery]
In this Experimental Example 2, when As (trivalent) concentration is kept constant at 10 ppm, 100 ml of solution is taken and adjusted to an initial pH = 1, and then 1 g of metal magnesium in the form of cut pieces of about 1 to 2 mm is added. The changes in the As concentration in the solution, the amount of arsine gas (hereinafter referred to as AsH 3 ) generated, the cumulative amount of AsH 3 and the As concentration in the solution were measured with respect to the stirring time. The results are shown in FIG.

溶液中のAs濃度は、撹拌時間と共に放物線的に減少していき３０分で０ppmに達した。即ち、完全に吸着回収されたことを示す。しかしながら、初期pH＝１と低い場合は、H2 ガスの発生を伴いながらMgが溶解していく。このH2ガスが、AsH3の発生源となる。そこで、Mg添加直後のAsH3発生量を調べると、撹拌時間と共に発生量は増加し、２分で最高値を示し、以後１４、１５分で発生が止まることがわかった。この発生量の累積値を計算すると、放物線的に増加し１４、１５分で平衡値に達した。 The concentration of As in the solution decreased parabolically with stirring time and reached 0 ppm in 30 minutes. That is, it indicates that the adsorption and recovery have been completed. However, when the initial pH is as low as 1, Mg dissolves with generation of H 2 gas. This H 2 gas becomes a source of AsH 3 . Accordingly, when the amount of AsH 3 generated immediately after the addition of Mg was examined, it was found that the amount generated increased with stirring time, showed a maximum value at 2 minutes, and then stopped at 14 and 15 minutes. When the cumulative value of this generated amount was calculated, it increased parabolically and reached an equilibrium value in 14 and 15 minutes.

このことから、最初に示した溶液中のAs濃度の曲線にはこのAsH3の量も含まれていることがわかる。図１０は、溶液中の総As濃度曲線（―●―印）とAsH3発生量曲線（―▲―印）を、同一図に示したものである。これから分る様に、撹拌時間９分でみると、沈殿に吸着されたAsとAsH3ガスとして放出されたAs量の比は３：１となっている。即ち、撹拌初期の１０分から１５分間に減少するAs量の約１／４程度は、AsH3ガスによる減少といえる。ここで発生したAsH3ガスは、猛毒であるので実操業では注意が必要である。 From this, it can be seen that the amount of AsH 3 is included in the curve of As concentration in the solution shown first. FIG. 10 shows the total As concentration curve in the solution (-● -mark) and the AsH 3 generation amount curve (-▲ --mark) in the same figure. As can be seen, when the stirring time is 9 minutes, the ratio of As adsorbed to the precipitate and the amount of As released as AsH 3 gas is 3: 1. That is, about 1/4 of the amount of As that decreases from 10 minutes to 15 minutes in the initial stage of stirring can be said to be reduced by AsH 3 gas. The AsH 3 gas generated here is extremely toxic, so care must be taken in actual operation.

以上のことから、MgによるAsの吸着機構は以下の様に考えられる。廃水中のAsにはAs(３価)、
As(５価)があり、一般にAs(５価)の方が水酸化物沈殿に吸着され易いといわれているが、本試験ではAs(３価)でも十分に吸着回収されている。 From the above, the mechanism of adsorption of As by Mg is considered as follows. As (trivalent) for As in wastewater,
There is As (pentavalent), and it is generally said that As (pentavalent) is more easily adsorbed to hydroxide precipitates. In this test, astri (trivalent) is sufficiently adsorbed and recovered.

（ａ）pH=1〜2では、
Mg+2H+→Mg2++H2↑ ｛Mg→Mg2++2e 2H++2e→H2｝ （１）
Mg2++2OH−→Mg(OH)2↓ （２）
ここで生成したMg(OH)2に、Asが吸着される。初期pH＝１〜２と低い場合は、Mgが溶解する際、H2ガスの発生を伴う。このH2ガスが、(6)式のようにAsH3の発生源となる。As(３価)は、酸性領域ではHAsO2の形態をとることから(6)式とした。
HAsO2+3H2→H3As↑+2H2O （６） (A) At pH = 1-2
Mg + 2H + → Mg 2+ + H 2 ↑ {Mg → Mg 2+ + 2e 2H + + 2e → H 2 } (1)
Mg 2+ + 2OH − → Mg (OH) 2 ↓ (2)
As is adsorbed on the Mg (OH) 2 produced here. When the initial pH is as low as 1-2, H 2 gas is generated when Mg dissolves. This H 2 gas becomes a source of AsH 3 as shown in equation (6). Since As (trivalent) takes the form of HAsO 2 in the acidic region, Formula (6) was used.
HAsO 2 + 3H 2 → H 3 As ↑ + 2H 2 O （６）

（ｂ）pH=2〜10では、(3)式または、(4)、(5)式のようにMg(OH)2のほか、MgOの生成が認められる。Asは(4)式で生成するMg(OH)2に吸着され、ほぼ１００％の回収率を示したものと考えられる。
Mg+H2O→MgO↓+H2 （３）
Mg+2H2O→Mg(OH)2↓+H2 （４）
Mg(OH)2→MgO↓+H2O （５） (B) At pH = 2 to 10, formation of MgO is observed in addition to Mg (OH) 2 as in the formula (3) or the formulas (4) and (5). As is adsorbed by Mg (OH) 2 produced by the formula (4), and it is considered that the recovery rate is almost 100%.
Mg + H 2 O → MgO ↓ + H 2 (3)
Mg + 2H 2 O → Mg (OH) 2 ↓ + H 2 (4)
Mg (OH) 2 → MgO ↓ + H 2 O (5)

（ｃ）pH=10〜12では、アルカリ性が強いことから容易に加水分解し(3)〜(5)式のようにMg(OH)
2 またはMgOが生成する。しかしながら、As(３価)はこのように高pH領域ではAsO2 -イオンの存在形態を示し、このイオンは吸着され難いものと推察され、吸着率が低かったものと考えられる。 (C) At pH = 10-12, it is easily hydrolyzed due to its strong alkalinity, and Mg (OH) as shown in formulas (3)-(5)
2 or MgO is produced. However, As (trivalent) shows the presence form of AsO 2 − ions in such a high pH region, and it is assumed that these ions are difficult to be adsorbed, and the adsorption rate is considered to be low.

例えば、亜鉛メッキ鋼板は現在大量に生産されており、そのため、メッキ廃液中の亜鉛の回収が、この業界では緊急の課題となっている。本発明の方法によれば、マグネシウム合金をリサイクル可能な吸着材として有効利用することによって、かかる問題を解決できる可能性がある。 For example, galvanized steel sheets are currently produced in large quantities, and therefore, recovery of zinc in plating waste liquid is an urgent issue in this industry. According to the method of the present invention, there is a possibility that such a problem can be solved by effectively utilizing the magnesium alloy as a recyclable adsorbent.

Znの例で、pH調整後Mgを添加した場合の、初期pHの影響を示す図である。In the example of Zn, it is a figure which shows the influence of initial pH at the time of adding Mg after pH adjustment. Znの例で、pH調整後Mgを添加した場合の、溶液中のMgの濃度変化を示す図である。In the example of Zn, it is a figure which shows the density | concentration change of Mg in a solution at the time of adding Mg after pH adjustment. Znの例で、Mgを添加した後pH調整した場合の、初期pHの影響を示す図である。In the example of Zn, it is a figure which shows the influence of initial pH at the time of adjusting pH after adding Mg. Znの例で、Mgを添加した後pH調整した場合の、Mgの重量変化を示す図である。In the example of Zn, it is a figure which shows the weight change of Mg at the time of adjusting pH after adding Mg. Asの例で、pH調整後Mgを添加した場合の、初期pHの影響を示す図である。In the example of As, it is a figure which shows the influence of initial pH at the time of adding Mg after pH adjustment. Asの例で、pH調整後Mgを添加した場合の、Mgの添加量の影響を示す図である。In the example of As, it is a figure which shows the influence of the addition amount of Mg at the time of adding Mg after pH adjustment. Asの例で、Mgを添加した後pH調整した場合の、初期pHの影響を示す図である。In the example of As, it is a figure which shows the influence of initial stage pH at the time of adjusting pH after adding Mg. Asの例で、Mgを添加した後pH調整した場合の、Mgの重量変化を示す図である。In the example of As, it is a figure which shows the weight change of Mg at the time of adjusting pH after adding Mg. 攪拌時間とAsH3の発生量等の関係を示す図である。Is a diagram showing the relationship between generation amount of the stirring time and AsH 3. 溶液中の総As濃度とAsH3発生量との関係を示す図である。FIG. 3 is a diagram showing the relationship between the total As concentration in a solution and the amount of AsH 3 generated.

Claims (7)

金属イオンを含む排水中に、マグネシウム又はマグネシウム合金を主成分とする吸着材を添加し、水とマグネシウムの反応によりマグネシウム表面に生成する水酸化マグネシウムの層に、該金属イオンを吸着させ、該金属イオンを排水から分離することを特徴とする金属イオンの分離方法。 An adsorbent containing magnesium or a magnesium alloy as a main component is added to waste water containing metal ions, and the metal ions are adsorbed on a magnesium hydroxide layer formed on the magnesium surface by the reaction of water and magnesium. A method for separating metal ions, characterized in that ions are separated from waste water. 金属イオンが、亜鉛族元素のイオンである請求項１記載の金属イオンの分離方法。 2. The method for separating metal ions according to claim 1, wherein the metal ions are zinc group element ions. 金属イオンが、両性元素のイオンである請求項１記載の金属イオンの分離方法。 2. The method for separating metal ions according to claim 1, wherein the metal ions are amphoteric element ions. マグネシウム合金が、Al、Ca、Zn、Mnの少なくとも１つとの合金である請求項１〜３記載の金属イオンの分離方法。 The method for separating metal ions according to claim 1, wherein the magnesium alloy is an alloy with at least one of Al, Ca, Zn, and Mn. 吸着材が、マグネシウム又はマグネシウム合金の粉末である請求項１〜４記載の金属イオンの分離方法。 The method for separating metal ions according to claim 1, wherein the adsorbent is a powder of magnesium or a magnesium alloy. 吸着材が、マグネシウム又はマグネシウム合金のリボンである請求項１〜４記載の金属イオンの分離方法。 The method for separating metal ions according to claim 1, wherein the adsorbent is a ribbon of magnesium or a magnesium alloy. 吸着材が、マグネシウム又はマグネシウム合金の多孔体である請求項１〜４記載の金属イオンの分離方法。
The method for separating metal ions according to claim 1, wherein the adsorbent is a porous body of magnesium or a magnesium alloy.
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JP2019063732A (en) * 2017-09-29 2019-04-25 日鉄ケミカル＆マテリアル株式会社 Metal trapping material for recovering valuable metals, method for producing the same and method for recovering valuable metals
JP2021038441A (en) * 2019-09-04 2021-03-11 国立研究開発法人産業技術総合研究所 Heavy metal separating method and metal recovery method

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JPS499056A (en) * 1972-05-15 1974-01-26
JP2005013976A (en) * 2003-06-25 2005-01-20 Takeshi Tachibana Method for removing arsenic

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Publication number Priority date Publication date Assignee Title
JPS499056A (en) * 1972-05-15 1974-01-26
JP2005013976A (en) * 2003-06-25 2005-01-20 Takeshi Tachibana Method for removing arsenic

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019063732A (en) * 2017-09-29 2019-04-25 日鉄ケミカル＆マテリアル株式会社 Metal trapping material for recovering valuable metals, method for producing the same and method for recovering valuable metals
JP2021038441A (en) * 2019-09-04 2021-03-11 国立研究開発法人産業技術総合研究所 Heavy metal separating method and metal recovery method
JP7368802B2 (en) 2019-09-04 2023-10-25 国立研究開発法人産業技術総合研究所 Heavy metal separation method and metal recovery method

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