JP2022130015A - Tin recovery method - Google Patents
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- JP2022130015A JP2022130015A JP2021028940A JP2021028940A JP2022130015A JP 2022130015 A JP2022130015 A JP 2022130015A JP 2021028940 A JP2021028940 A JP 2021028940A JP 2021028940 A JP2021028940 A JP 2021028940A JP 2022130015 A JP2022130015 A JP 2022130015A
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- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 title claims abstract description 143
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000011084 recovery Methods 0.000 title description 10
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 86
- 238000002386 leaching Methods 0.000 claims abstract description 63
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 38
- 229910052802 copper Inorganic materials 0.000 claims abstract description 38
- 239000010949 copper Substances 0.000 claims abstract description 38
- 239000000243 solution Substances 0.000 claims abstract description 27
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 18
- 230000003647 oxidation Effects 0.000 claims abstract description 15
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 15
- 239000003929 acidic solution Substances 0.000 claims abstract description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 8
- 230000001590 oxidative effect Effects 0.000 claims abstract description 7
- 230000003472 neutralizing effect Effects 0.000 claims abstract description 5
- 239000007788 liquid Substances 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 16
- 239000002244 precipitate Substances 0.000 claims description 16
- 239000002253 acid Substances 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 5
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 239000000758 substrate Substances 0.000 description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 238000000926 separation method Methods 0.000 description 7
- 238000003723 Smelting Methods 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 238000012546 transfer Methods 0.000 description 5
- 238000005363 electrowinning Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 239000011780 sodium chloride Substances 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000000967 suction filtration Methods 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- PIJPYDMVFNTHIP-UHFFFAOYSA-L lead sulfate Chemical compound [PbH4+2].[O-]S([O-])(=O)=O PIJPYDMVFNTHIP-UHFFFAOYSA-L 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- FAKFSJNVVCGEEI-UHFFFAOYSA-J tin(4+);disulfate Chemical compound [Sn+4].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O FAKFSJNVVCGEEI-UHFFFAOYSA-J 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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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
- 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
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- Manufacture And Refinement Of Metals (AREA)
Abstract
Description
本発明は、錫の回収方法に関し、特に、錫の他に銅、鉛の一方または両方を含む錫含有物から錫を効率よく分離して回収する方法に関する。 TECHNICAL FIELD The present invention relates to a method for recovering tin, and more particularly to a method for efficiently separating and recovering tin from a tin-containing material containing tin and/or copper and/or lead.
従来、錫含有物からの錫の回収方法として、鉛製錬工程で発生したドロスから鉛を分離して得た原料を熔融還元した錫含有物（主に錫と銅を含有）をＮａＯＨ溶液中で酸化させながら錫を浸出させ、この錫浸出液から電解採取によって錫を回収する方法が知られている（特許文献１：特許第５１８８７６８号）。しかし、錫含有物に鉛が含まれていると、錫と共に鉛が浸出し、この鉛は錫よりも貴な元素であるため、電解採取の際に錫に優先して析出するので、錫と鉛を分離できない。また、浸出にＮａＯＨを使用するため薬剤コストが高いという問題もあった。 Conventionally, as a method for recovering tin from tin-containing materials, a tin-containing material (mainly containing tin and copper) obtained by melting and reducing a raw material obtained by separating lead from dross generated in a lead smelting process is placed in a NaOH solution. A method is known in which tin is leached while being oxidized with , and tin is recovered from the tin-leached solution by electrowinning (Patent Document 1: Japanese Patent No. 5188768). However, if lead is contained in the tin-containing material, lead will leach out together with the tin. Since this lead is an element more noble than tin, it will precipitate preferentially over tin during electrowinning. Lead cannot be separated. In addition, since NaOH is used for leaching, there is also the problem of high chemical costs.
一方、電解採取前の錫浸出液に銅や鉛が含まれている場合、該浸出液に金属錫粉末を投入して錫よりも貴な元素である銅や鉛を還元し、液中から除去する置換析出（セメンテーション）によって銅や鉛を除去する方法が知られている（特許文献２：特開平１１－２１７６３４号）。しかし、原料中の銅または鉛濃度が高い場合、セメンテーションに用いる金属錫がコスト高になる。 On the other hand, when copper or lead is contained in the tin leaching solution before electrowinning, metal tin powder is added to the leaching solution to reduce copper and lead, which are elements nobler than tin, and remove them from the solution. A method of removing copper and lead by precipitation (cementation) is known (Patent Document 2: JP-A-11-217634). However, when the copper or lead concentration in the raw material is high, the cost of metallic tin used for cementation becomes high.
上記浸出後の錫を電解採取によって回収する方法とは異なり、銅製錬ダストを塩酸や硝酸を用いて浸出し、銅および鉛を優先的に溶出させる一方、錫を浸出残渣に濃縮して回収する方法が知られている（特許文献３：特開２０１９－１５１８６２号、特許文献４：特開２０１９－１５１８６３号）。この方法は浸出後に錫が固体として存在するため、固液分離により容易に錫を回収できる利点を有している一方、錫とともに浸出されない元素が多いので、得られる錫回収物の錫品位が低いという問題があった。 Unlike the above method of recovering tin after leaching by electrowinning, copper smelting dust is leached using hydrochloric acid or nitric acid to preferentially elute copper and lead, while tin is concentrated and recovered in the leaching residue. A method is known (Patent Document 3: JP-A-2019-151862, Patent Document 4: JP-A-2019-151863). Since tin exists as a solid after leaching, this method has the advantage that tin can be easily recovered by solid-liquid separation. There was a problem.
本発明は、従来の錫回収方法における上記問題を解決したものであり、錫と共に銅、鉛のいずれか一方または両方を含む錫含有物から、効率よく錫を回収する方法を提供する。また、上記塩酸浸出や上記硝酸浸出よりも錫品位の高い錫回収物を得ることができる錫の回収方法を提供する。 The present invention solves the above-mentioned problems of conventional tin recovery methods, and provides a method for efficiently recovering tin from tin-containing substances containing either or both of copper and lead together with tin. Further, the present invention provides a tin recovery method capable of obtaining a recovered tin product having a higher tin quality than the above hydrochloric acid leaching or nitric acid leaching.
本発明は、以下の構成によって上記課題を解決した錫の回収方法である。
〔１〕錫と共に銅、鉛のいずれか一方または両方を含む錫含有物から錫を回収する方法であって、硫酸酸性溶液中で該錫含有物から錫を酸化浸出させる硫酸酸化浸出工程と、この浸出後液を中和して錫含有沈澱物を生成させて回収する中和工程を有することを特徴とする錫の回収方法。
〔２〕前記硫酸酸化浸出工程において、硫酸濃度が１００g/L以上～４００g/L以下の酸性溶液を用いる前記[１]に記載する錫の回収方法。
〔３〕前記硫酸酸化浸出工程において、硫酸主体の酸性溶液に塩化物イオンを添加する前記[１]または前記[２]に記載する錫の回収方法。
〔４〕前記中和工程において、液中のｐＨを３.５以上～４.５以下にする前記[１]～前記[３]の何れかに記載する錫の回収方法。
The present invention is a tin recovery method that solves the above problems by the following configuration.
[1] A method for recovering tin from a tin-containing material containing either or both of copper and lead together with tin, comprising a sulfuric acid oxidation leaching step of oxidizing and leaching tin from the tin-containing material in a sulfuric acid acidic solution; A method for recovering tin, comprising a neutralization step of neutralizing the post-leaching solution to generate and recover a tin-containing precipitate.
[2] The method for recovering tin according to [1] above, wherein an acidic solution having a sulfuric acid concentration of 100 g/L or more and 400 g/L or less is used in the sulfuric acid oxidation leaching step.
[3] The method for recovering tin according to the above [1] or [2], wherein chloride ions are added to the acidic solution mainly composed of sulfuric acid in the sulfuric acid oxidation leaching step.
[4] The method for recovering tin according to any one of [1] to [3], wherein the pH of the liquid is adjusted to 3.5 or more and 4.5 or less in the neutralization step.
〔具体的な説明〕
以下、本発明を具体的に説明する。
本発明の方法は、錫と共に銅、鉛のいずれか一方または両方を含む錫含有物から錫を回収する方法であって、硫酸酸性溶液中で該錫含有物から錫を酸化浸出させる硫酸酸化浸出工程と、この浸出後液を中和して錫含有沈澱物を生成させて回収する中和工程からなることを特徴とする錫の回収方法である。
本発明の錫回収方法の処理例を図１に示す。
[Specific explanation]
The present invention will be specifically described below.
The method of the present invention is a method for recovering tin from a tin-containing material containing either or both of copper and lead together with tin, wherein the sulfuric acid oxidative leaching is performed by oxidizing and leaching tin from the tin-containing material in a sulfuric acid acidic solution. and a neutralization step of neutralizing the post-leaching solution to generate and recover a tin-containing precipitate.
FIG. 1 shows a processing example of the tin recovery method of the present invention.
本発明の錫回収方法は、錫と共に銅、鉛のいずれか一方または両方を含む錫含有物から錫を回収する方法である。錫と共に銅、鉛のいずれか一方または両方を含む錫含有物としては、例えば、電子基板の破砕物（破砕基板）、半田屑等のスクラップ、各種スクラップの選別品、および種々の製錬中間品などを用いることができる。 The method for recovering tin of the present invention is a method for recovering tin from a tin-containing material containing either or both of copper and lead together with tin. Tin-containing materials containing either or both of copper and lead together with tin include, for example, crushed electronic substrates (crushed substrates), scraps such as solder chips, sorted scraps, and various smelting intermediates. etc. can be used.
〔硫酸酸化浸出〕
錫含有物（破砕基板等）を硫酸主体の酸性溶液（硫酸酸性溶液と云う）中で酸化浸出（硫酸酸化浸出と云う）して錫を浸出させる。破砕基板等に含まれる錫の大半は酸化されて硫酸錫や硫酸錯イオン等の形態で液中に浸出し、残余の錫は浸出残渣に移行する。
[Sulfuric acid leaching]
Tin-containing materials (crushed substrates, etc.) are subjected to oxidative leaching (referred to as sulfuric acid oxidative leaching) in an acidic solution mainly composed of sulfuric acid (referred to as a sulfuric acid acidic solution) to leach out tin. Most of the tin contained in the crushed substrate or the like is oxidized and leaches into the liquid in the form of tin sulfate, sulfate complex ions, etc., and the remaining tin moves to the leaching residue.
硫酸酸化浸出の硫酸濃度は１００g/L以上～４００g/L以下が好ましい。硫酸濃度が１００g/L未満では錫の浸出率が著しく低下する。一方、硫酸濃度が４００g/Lを超えると、銅の浸出率が上昇するので錫と銅との分離が悪くなり、また錫が硫酸錯イオンを安定に形成するため中和工程で錫が沈澱し難くなる。 The concentration of sulfuric acid in the sulfuric acid leaching is preferably 100 g/L or more and 400 g/L or less. If the sulfuric acid concentration is less than 100 g/L, the tin leaching rate is significantly reduced. On the other hand, when the concentration of sulfuric acid exceeds 400 g/L, the leaching rate of copper increases, resulting in poor separation of tin and copper. In addition, since tin stably forms sulfate complex ions, tin precipitates during the neutralization process. it gets harder.
この硫酸酸化浸出は、酸化剤として空気などを吹き込んで行うとよい。空気に代えて酸素ガスを用いると溶存酸素濃度が高くなり、銅の浸出率が上昇するため、空気などを用いるのが好ましい。 This sulfuric acid oxidation leaching is preferably carried out by blowing in air or the like as an oxidizing agent. If oxygen gas is used instead of air, the concentration of dissolved oxygen increases and the leaching rate of copper increases, so it is preferable to use air or the like.
錫や鉛は銅よりも卑な金属であるため、硫酸酸化浸出では錫および鉛が銅よりも優先的に酸化される。さらに酸化された鉛は液中の硫酸イオンと反応して安定な硫酸鉛を形成して沈殿する。一方、酸化浸出された錫は液中に残るので、銅と鉛の大部分を浸出残渣として分離することができる。この結果、後の中和工程で生成する錫含有沈殿物への銅と鉛の混入を大幅に低減することができる。 Since tin and lead are less noble metals than copper, tin and lead are preferentially oxidized over copper in sulfuric acid leaching. Further, the oxidized lead reacts with sulfate ions in the liquid to form stable lead sulfate and precipitate. On the other hand, since the oxidized and leached tin remains in the liquid, most of the copper and lead can be separated as leaching residues. As a result, it is possible to greatly reduce the contamination of copper and lead in the tin-containing precipitate formed in the subsequent neutralization step.
硫酸酸化浸出において、硫酸溶液に塩化物イオンを添加すると錫の浸出が促されて、錫回収物への錫移行率を上昇させることができる。具体的には、例えば、実施例（No.Ａ２～Ａ５）に示すように、２.５質量％の錫を含む破砕基板（原料）５０ｇを濃度１００g/Lの硫酸１Ｌを用いて浸出するときに、塩化物イオンの添加剤として１ｇ～１０ｇのＮａＣｌ（原料の錫量に対して１～１０倍程度）を添加すると、錫回収物への錫移行率を、ＮａＣｌ無添加に比べて４５％から８３％増大させることができる。上記塩化物イオンの添加剤としては、ＮａＣｌやＫＣｌ等の塩類、これら塩類の水溶液、および塩酸などを用いることができる。 In the sulfuric acid leaching, the addition of chloride ions to the sulfuric acid solution promotes the leaching of tin and can increase the rate of tin transfer to the tin recovery product. Specifically, for example, as shown in Examples (Nos. A2 to A5), when 50 g of a crushed substrate (raw material) containing 2.5% by mass of tin is leached with 1 L of sulfuric acid having a concentration of 100 g/L. When 1 g to 10 g of NaCl (approximately 1 to 10 times the amount of tin in the raw material) is added as an additive for chloride ions, the tin transfer rate to the recovered tin is reduced to 45% compared to the case where NaCl is not added. can be increased by 83% from Salts such as NaCl and KCl, aqueous solutions of these salts, and hydrochloric acid can be used as the chloride ion additive.
〔浸出後液と浸出残渣の分離〕
上記硫酸酸化浸出後の液と浸出残渣を固液分離する。浸出後液には主に錫が含まれており、浸出残渣には銅および鉛の大部分が含まれている。
[Separation of post-leaching liquid and leaching residue]
Solid-liquid separation is performed between the liquid after the sulfuric acid oxidation leaching and the leaching residue. The post-leaching liquor contains mainly tin, and the leaching residue contains mostly copper and lead.
〔中和：錫含有沈澱物生成〕
分離した浸出後液にアルカリ溶液を加えて中和し、主に錫を含む沈殿物（錫含有沈殿物と云う）を生成させる。錫を含む上記浸出後液は強酸性であり、これにＮａＯＨ溶液などのアルカリ溶液を加えて、ｐＨ３.５以上～ｐＨ４.５以下の液性に中和すると、錫含有沈澱物が生成する。図２に示すように、液中の錫濃度はｐＨの上昇に伴い低下し、ｐＨ３.５を超えて中和すると錫のほぼ全量を沈殿させることができる。一方、上記硫酸酸化浸出の工程で銅の一部が浸出していた場合、ｐＨ４.５を超えて中和すると液中の銅が沈澱し、錫含有沈殿物に混入する。したがって、中和工程におけるｐＨは３.５以上～４.５以下に制御することが好ましい。生成した錫含有沈澱物を固液分離して回収し、錫回収物を得る。
[Neutralization: Formation of tin-containing precipitate]
An alkaline solution is added to the separated leaching liquid to neutralize it, thereby forming a precipitate mainly containing tin (referred to as a tin-containing precipitate). The post-leaching solution containing tin is strongly acidic, and when an alkaline solution such as a NaOH solution is added to neutralize the solution to pH 3.5 or more and pH 4.5 or less, a tin-containing precipitate is formed. As shown in FIG. 2, the tin concentration in the liquid decreases as the pH increases, and neutralization above pH 3.5 can precipitate almost all of the tin. On the other hand, if a part of the copper is leached out in the step of leaching by sulfuric acid oxidation, the copper in the solution precipitates when the solution is neutralized at a pH exceeding 4.5, and is mixed with the tin-containing precipitate. Therefore, it is preferable to control the pH in the neutralization step to 3.5 or more and 4.5 or less. The produced tin-containing precipitate is recovered by solid-liquid separation to obtain a recovered tin product.
本発明の錫回収方法によれば、錫と共に銅、鉛のいずれか一方または両方を含む錫含有物について、硫酸酸化浸出を行うことによって、錫を優先的に浸出させ、銅および鉛の大部分を浸出残渣に移行させることができる。このため、錫濃度が高く、かつ、銅濃度および鉛濃度が低い浸出後液を得ることができ、得られた浸出後液を中和することによって、錫品位の高い錫回収物を得ることができる。本発明の錫回収方法によれば、塩酸浸出や硝酸浸出によって得られる錫含有浸出残渣よりも錫品位の高い錫回収物が得られる。 According to the method for recovering tin of the present invention, the tin-containing material containing either or both of copper and lead together with tin is subjected to sulfuric acid oxidation leaching to preferentially leach tin and remove most of copper and lead. can be transferred to the leach residue. Therefore, a post-leaching solution having a high tin concentration and low copper and lead concentrations can be obtained, and by neutralizing the obtained post-leaching solution, a recovered tin product having a high tin quality can be obtained. can. According to the tin recovery method of the present invention, a recovered tin product having a higher tin quality than tin-containing leaching residue obtained by hydrochloric acid leaching or nitric acid leaching can be obtained.
本発明の方法によって得られる錫回収物は錫製錬工程の原料として使用できる。また、この錫回収物は銅濃度が従来の方法に比べ格段に低く、鉛を殆ど含まないので、一般の錫製錬工程で処理することによって経済的に錫地金に仕上げることができる。 The recovered tin product obtained by the method of the present invention can be used as a raw material in the tin smelting process. In addition, since the recovered tin has a much lower copper concentration than that obtained by the conventional method and contains almost no lead, it can be economically finished as a tin metal by processing it in a general tin refining process.
以下、本発明の実施例を示す。濃度の％は質量％である。
〔実施例〕
廃電子基板２kgを二軸破砕機で破砕した後に目開き３.３５mmの篩で分級し、篩下の破砕基板を回収した。この破砕基板５０ｇを６０℃に保持した硫酸濃度５０～５００g/Lの酸性溶液１Ｌに浸漬し、空気を０.５L/minの速度で吹込みながら６時間攪拌して硫酸酸化浸出を行った。一部の試料は硫酸溶液に１ｇ～１０ｇのＮａＣｌを添加して硫酸酸化浸出を行った。その後、吸引濾過装置を用いて固液分離し、浸出後液と浸出残渣を得た。得られた浸出後液に対して４８％ＮａＯＨ溶液を添加し、ｐＨ３.０～ｐＨ５.０に中和した。中和処理後に吸引濾過装置を用いて固液分離し、中和後液と錫回収物を得た。得られた錫回収物は１０５℃の乾燥機で１２時間乾燥させた。
原料の破砕基板に含まれる錫、銅、鉛の含有量を表１に示す。硫酸酸化浸出の処理条件と中和時のｐＨ、および錫回収物の錫、銅、鉛の濃度と移行率を表２に示す。また各実施例および比較例について、浸出残渣と中和後液の錫、銅、鉛の移行率を表３に示す。これらの濃度はＩＣＰ－ＡＥＳによって測定した。移行率は次式[３]によって求めた。
移行率(％)＝[回収物中の金属量]／[原料中の金属量]×100 ・・・[３]
Examples of the present invention are shown below. Concentration % is mass %.
〔Example〕
After crushing 2 kg of waste electronic substrates with a twin-screw crusher, the crushed substrates under the sieve were collected by classifying with a sieve with an opening of 3.35 mm. 50 g of this crushed substrate was immersed in 1 L of an acidic solution with a sulfuric acid concentration of 50 to 500 g/L maintained at 60° C., and stirred for 6 hours while air was blown in at a rate of 0.5 L/min for sulfuric acid oxidation leaching. Some samples were subjected to sulfate oxidation leaching by adding 1 g to 10 g of NaCl to the sulfuric acid solution. Then, solid-liquid separation was performed using a suction filtration device to obtain a liquid after leaching and a leaching residue. A 48% NaOH solution was added to the obtained post-leaching solution to neutralize it to pH 3.0 to pH 5.0. After the neutralization treatment, solid-liquid separation was performed using a suction filtration device to obtain a post-neutralization liquid and a tin recovered product. The obtained tin recovery material was dried in a drier at 105° C. for 12 hours.
Table 1 shows the contents of tin, copper, and lead contained in the raw material crushed substrate. Table 2 shows the processing conditions for sulfuric acid leaching, the pH during neutralization, and the concentrations and transfer rates of tin, copper, and lead in the recovered tin. Table 3 shows the migration rates of tin, copper, and lead in the leaching residue and the neutralized solution for each example and comparative example. These concentrations were measured by ICP-AES. The transfer rate was obtained by the following formula [3].
Migration rate (%) = [amount of metal in recovered material]/[amount of metal in raw material] x 100 ... [3]
表２、表３に示すように、硫酸濃度１００～４００g/Lの範囲において、破砕基板中の錫の約４５～約６２％程度が浸出され、浸出した錫のほぼ全量が錫回収物に移行した（No.Ａ１、Ａ５～Ａ９）。また、塩化物イオンの添加によって錫回収率が約４２％から約８３％増大し、塩化物イオンの添加効果が確認された（No.Ａ２～Ａ４）。一方、硫酸濃度５０g/Lでは錫が約５％しか浸出できず（No.Ｂ１）、また硫酸濃度５００g/Lでは浸出した錫が硫酸錯イオンを安定に形成するので、ｐＨ４まで中和しても錫が全量沈殿せず、全錫の約２０％が中和後液に移行した。さらに硫酸濃度が高いことから銅の浸出率が上昇し、中和後液および錫回収物への銅移行率が上昇した（No.Ｂ２）。銅は錫製錬工程に悪影響を及ぼすため、銅を多く含んだ錫回収物は錫製錬原料として好ましくない。また、ｐＨ３.０までしか中和しない場合、浸出時の硫酸濃度に関わらず錫が全量沈殿しないため、錫の約４．１％が中和後液に移行した（No.Ｂ３）。一方、ｐＨ５.０に中和すると、浸出した銅の大部分が沈殿し、錫回収物の品位が低下した（No.Ｂ４）。
As shown in Tables 2 and 3, about 45 to about 62% of the tin in the crushed substrate is leached in the sulfuric acid concentration range of 100 to 400 g/L, and almost all of the leached tin is transferred to the recovered tin. (No. A1, A5 to A9). Further, the addition of chloride ions increased the tin recovery rate from about 42% to about 83%, confirming the effect of adding chloride ions (Nos. A2 to A4). On the other hand, at a sulfuric acid concentration of 50 g/L, only about 5% of tin can be leached (No. B1), and at a sulfuric acid concentration of 500 g/L, the leached tin stably forms sulfate complex ions, so neutralize to
Claims (4)
4. The method for recovering tin according to any one of claims 1 to 3, wherein the pH of the liquid is adjusted to 3.5 or more and 4.5 or less in the neutralization step.
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