JP2021116436A - Recovery method of silver - Google Patents
Recovery method of silver Download PDFInfo
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- JP2021116436A JP2021116436A JP2020008587A JP2020008587A JP2021116436A JP 2021116436 A JP2021116436 A JP 2021116436A JP 2020008587 A JP2020008587 A JP 2020008587A JP 2020008587 A JP2020008587 A JP 2020008587A JP 2021116436 A JP2021116436 A JP 2021116436A
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- 239000004332 silver Substances 0.000 title claims abstract description 132
- 229910052709 silver Inorganic materials 0.000 title claims abstract description 131
- 238000011084 recovery Methods 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 title claims abstract description 43
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 claims abstract description 113
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 110
- 239000010949 copper Substances 0.000 claims abstract description 72
- 229910052802 copper Inorganic materials 0.000 claims abstract description 66
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 64
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 62
- 229910021607 Silver chloride Inorganic materials 0.000 claims abstract description 35
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims abstract description 35
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 32
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910001431 copper ion Inorganic materials 0.000 claims abstract description 30
- 229910052751 metal Inorganic materials 0.000 claims abstract description 23
- 239000002184 metal Substances 0.000 claims abstract description 23
- 229910052742 iron Inorganic materials 0.000 claims abstract description 20
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 19
- 239000000956 alloy Substances 0.000 claims abstract description 19
- 230000001376 precipitating effect Effects 0.000 claims abstract 4
- 239000000463 material Substances 0.000 claims description 36
- 238000007598 dipping method Methods 0.000 claims description 29
- -1 silver ions Chemical class 0.000 claims description 27
- 239000011248 coating agent Substances 0.000 claims description 17
- 238000000576 coating method Methods 0.000 claims description 17
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 6
- 229910002651 NO3 Inorganic materials 0.000 claims description 4
- 238000007654 immersion Methods 0.000 claims description 4
- 150000002500 ions Chemical class 0.000 claims description 2
- 238000002386 leaching Methods 0.000 claims 1
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 abstract description 4
- 239000000758 substrate Substances 0.000 abstract description 4
- 239000002253 acid Substances 0.000 abstract 1
- 229910000679 solder Inorganic materials 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 93
- 239000002585 base Substances 0.000 description 30
- 238000006243 chemical reaction Methods 0.000 description 22
- 239000007864 aqueous solution Substances 0.000 description 15
- 238000001914 filtration Methods 0.000 description 14
- 239000007787 solid Substances 0.000 description 11
- 239000002699 waste material Substances 0.000 description 8
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 7
- 238000004090 dissolution Methods 0.000 description 7
- 239000012776 electronic material Substances 0.000 description 7
- 238000000926 separation method Methods 0.000 description 7
- 229910000531 Co alloy Inorganic materials 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- KGWWEXORQXHJJQ-UHFFFAOYSA-N [Fe].[Co].[Ni] Chemical compound [Fe].[Co].[Ni] KGWWEXORQXHJJQ-UHFFFAOYSA-N 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 5
- 239000003513 alkali Substances 0.000 description 5
- 229910017604 nitric acid Inorganic materials 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 4
- 230000008929 regeneration Effects 0.000 description 4
- 238000011069 regeneration method Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 229910001316 Ag alloy Inorganic materials 0.000 description 2
- 238000005219 brazing Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 150000001879 copper Chemical class 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 238000004445 quantitative analysis Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 229910017435 S2 In Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 229910002065 alloy metal Inorganic materials 0.000 description 1
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 235000014593 oils and fats Nutrition 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 150000003378 silver Chemical class 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 231100000167 toxic agent Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc 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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- Processing Of Solid Wastes (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
Description
本発明は、銀が溶解している硝酸鉄溶液から銀を回収する方法に関する。 The present invention relates to a method for recovering silver from an iron nitrate solution in which silver is dissolved.
スマートフォン、パーソナルコンピュータ、通信機器などの電子機器には、主として、鉄、ニッケル、及びコバルトからなる鉄−ニッケル−コバルト合金の表面に塗布等により銀ロウを被覆させた電子材料が用いられている。この電子材料は、金属とセラミックやガラスとの接合に適しており、圧電振動子などの気密封入用に利用されている。 Electronic devices such as smartphones, personal computers, and communication devices mainly use electronic materials in which the surface of an iron-nickel-cobalt alloy composed of iron, nickel, and cobalt is coated with silver wax by coating or the like. This electronic material is suitable for joining metal to ceramics or glass, and is used for airtight sealing of piezoelectric vibrators and the like.
上記の電子材料は、気密封入等に使用される際の接合面の形状に合わせて打ち抜き加工等により作製されるため、この作製時に多量の加工屑が発生する。この加工屑には有価金属である銀が含まれており、また、基材としての鉄−ニッケル−コバルト合金も高価なニッケル及びコバルトを含んでいるため、これら銀及び鉄−ニッケル−コバルト合金をそれぞれできるだけ高純度に回収することが望ましい。 Since the above electronic material is produced by punching or the like according to the shape of the joint surface when it is used for airtight sealing or the like, a large amount of processing waste is generated during this production. Since this processing waste contains silver, which is a valuable metal, and the iron-nickel-cobalt alloy as a base material also contains expensive nickel and cobalt, these silver and iron-nickel-cobalt alloys are used. It is desirable to recover each with the highest possible purity.
従来、上記のような鉄系合金基材に銀ロウが被覆された電子材料の加工屑に対して、基材としての鉄系合金のロスをできるだけ抑えながら銀を回収する方法として、シアン化アルカリを用いる方法が知られている。この回収方法は、銀ロウで被覆された鉄系合金基材をシアン化アルカリ水溶液等のシアン系剥離液に浸漬することにより、鉄系合金基材の表面から銀ロウのみを剥離して回収するものである。しかしながら、当該回収方法は、毒物であるシアン化アルカリを使用するため、回収設備には特定の専用作業施設を設けると共に、該回収設備から発生する洗浄液中のシアンをほぼ完全に分解するための排水処理設備が必要になる。このため、回収処理に極めて多くの手間とコストがかかることが問題になっていた。 Conventionally, alkali cyanide has been used as a method for recovering silver while suppressing the loss of the iron-based alloy as the base material as much as possible with respect to the processing waste of the electronic material in which the iron-based alloy base material is coated with silver wax as described above. The method using is known. In this recovery method, only the silver wax is peeled off from the surface of the iron-based alloy base material and recovered by immersing the iron-based alloy base material coated with silver wax in a cyanide-based stripping solution such as an aqueous solution of an alkali cyanide. It is a thing. However, since the recovery method uses alkali cyanide, which is a toxic substance, a specific dedicated work facility is provided in the recovery facility, and wastewater for almost completely decomposing cyanide in the cleaning liquid generated from the recovery facility is provided. Processing equipment is required. For this reason, there has been a problem that the collection process requires an extremely large amount of labor and cost.
そこで、上記のシアン化アルカリを使わない回収方法として、特許文献１には硝酸鉄含有溶液を用いる技術が提案されている。この回収方法は、該硝酸鉄溶液に含まれるＦｅ３＋を酸化剤として用いることにより、銀ロウに含まれる金属銀及び金属銅を溶解するものである。具体的には、この特許文献１の回収方法は、鉄−ニッケル−コバルト合金等の鉄系合金の基材に銀又は銀系合金を被覆した電子材料の加工屑に対して、硝酸鉄含有溶液を添加することで該銀又は銀系合金を溶解させ、これにより該基板から該銀又は銀系合金を剥離する溶解剥離工程と、該銀又は銀系合金が溶解した硝酸鉄含有溶液に塩酸を添加することで塩化銀沈殿物を生成する塩化銀生成工程と、該溶解剥離工程後の硝酸鉄含有溶液に含まれる２価の鉄イオン（Ｆｅ２＋）を３価の鉄イオン（Ｆｅ３＋）に酸化することで該硝酸鉄含有溶液を再生する硝酸鉄再生工程と、該硝酸鉄再生工程で再生した硝酸鉄含有溶液の濃度を、該溶解剥離工程に使用する硝酸鉄含有溶液の濃度に調整する硝酸鉄含有溶液調整工程とを有している。 Therefore, as a recovery method that does not use the above-mentioned alkali cyanide, Patent Document 1 proposes a technique that uses an iron nitrate-containing solution. In this recovery method, metallic silver and metallic copper contained in silver wax are dissolved by using Fe 3+ contained in the iron nitrate solution as an oxidizing agent. Specifically, the recovery method of Patent Document 1 is a solution containing iron nitrate for processing scraps of an electronic material in which a base material of an iron-based alloy such as an iron-nickel-cobalt alloy is coated with silver or a silver-based alloy. The silver or silver-based alloy is dissolved by adding the above, thereby peeling the silver or the silver-based alloy from the substrate. The divalent iron ion (Fe 2+ ) contained in the silver chloride production step of producing a silver chloride precipitate by addition and the iron nitrate-containing solution after the dissolution and peeling step is converted into a trivalent iron ion (Fe 3+ ). The iron nitrate regeneration step of regenerating the iron nitrate-containing solution by oxidation and the concentration of the iron nitrate-containing solution regenerated in the iron nitrate regeneration step are adjusted to the concentration of the iron nitrate-containing solution used in the dissolution and peeling step. It has an iron nitrate-containing solution adjusting step.
そして、上記溶解剥離工程では、上記電子材料の加工屑に添加した後の硝酸鉄含有溶液中のＦｅ３＋濃度がＦｅ２＋濃度の１.５倍当量以上となるように維持し、該溶解剥離工程では上記硝酸鉄再生工程で再生した硝酸鉄含有溶液を使用し、該硝酸鉄含有溶液調整工程では、該溶解剥離工程で溶解した銀合金成分のうち銀を除いたものと当量の硝酸イオンに相当する硝酸を補充することで、該硝酸鉄再生工程で再生した硝酸鉄含有溶液の硝酸イオン濃度を調整している。この回収方法を採用することで、毒物のシアン化アルカリを使用する必要がなくなるうえ、硝酸鉄溶液を複数回繰り返して利用することができるので、安全かつ低コストに銀及び鉄系合金基材を回収することが可能になる。 Then, in the dissolution / peeling step, the Fe 3+ concentration in the iron nitrate-containing solution after being added to the processing waste of the electronic material is maintained so as to be 1.5 times or more the Fe 2+ concentration, and the dissolution / peeling step is performed. Then, the iron nitrate-containing solution regenerated in the iron nitrate regeneration step is used, and in the iron nitrate-containing solution adjusting step, it corresponds to the amount of nitrate ions equivalent to the silver alloy component dissolved in the dissolution peeling step excluding silver. By replenishing the nitrate to be added, the nitrate ion concentration of the iron nitrate-containing solution regenerated in the iron nitrate regeneration step is adjusted. By adopting this recovery method, it is not necessary to use the toxic alkali cyanide, and the iron nitrate solution can be used repeatedly multiple times, so silver and iron alloy base materials can be used safely and at low cost. It will be possible to collect it.
上記特許文献１の回収方法のように、硝酸鉄含有溶液を使用する場合は、被覆材である銀ロウを構成する銀系合金に主として含まれる銅も溶解する。そのため、硝酸鉄含有溶液を繰り返し使用しているうちに硝酸鉄含有溶液中に銅イオンが徐々に蓄積して硝酸鉄含有溶液の粘性が上昇するうえ、硝酸鉄含有溶液中の硝酸イオンの一部がこの銅の溶解に消費される。このように、硝酸鉄含有溶液を繰り返し使用する場合は、該硝酸鉄含有溶液の溶解能力が徐々に低下することが問題になっていた。 When an iron nitrate-containing solution is used as in the recovery method of Patent Document 1, copper mainly contained in the silver-based alloy constituting the silver brazing material as a coating material is also dissolved. Therefore, during repeated use of the iron nitrate-containing solution, copper ions gradually accumulate in the iron nitrate-containing solution to increase the viscosity of the iron nitrate-containing solution, and a part of the nitrate ions in the iron nitrate-containing solution. Is consumed to melt this copper. As described above, when the iron nitrate-containing solution is used repeatedly, there has been a problem that the dissolving ability of the iron nitrate-containing solution gradually decreases.
特許文献１では、かかる硝酸鉄含有溶液の溶解能力の低下の問題を抑えるため、硝酸水溶液を適宜添加して硝酸鉄含有溶液の硝酸イオン濃度を調整している。しかしながら、硝酸イオン濃度を維持するために硝酸水溶液の添加を行うと、上記回収設備の系内の硝酸鉄含有溶液の合計液量が増加するため、該回収設備を構成する各装置がその処理能力を超えて適切に処理できなくなることがあった。この場合は、例えば該系内の硝酸含有溶液を新たに調製した硝酸鉄含有溶液と入れ替えることになるため、コストの点から好ましくなかった。 In Patent Document 1, in order to suppress the problem of a decrease in the dissolving ability of the iron nitrate-containing solution, an aqueous nitric acid solution is appropriately added to adjust the nitrate ion concentration of the iron nitrate-containing solution. However, when an aqueous nitric acid solution is added to maintain the nitrate ion concentration, the total amount of the iron nitrate-containing solution in the system of the recovery equipment increases, so that each device constituting the recovery equipment has a processing capacity thereof. In some cases, it could not be processed properly. In this case, for example, the nitric acid-containing solution in the system is replaced with a newly prepared iron nitrate-containing solution, which is not preferable from the viewpoint of cost.
本発明は上記実情に鑑みてなされたものであり、銀又は銀系合金で被覆された鉄系合金基材に対して、硝酸鉄含有溶液の消費量を抑制しながら、効率よく銀を回収することが可能な方法を提供することを目的としている。 The present invention has been made in view of the above circumstances, and efficiently recovers silver from an iron-based alloy base material coated with silver or a silver-based alloy while suppressing the consumption of an iron nitrate-containing solution. It aims to provide a possible method.
上記目的を達成するため、本発明に係る銀の回収方法は、銀及び銅を含む被覆基材を硝酸鉄溶液で浸漬処理することで銀を回収する方法であって、銀イオン及び銅イオンを含んだ該浸漬処理後の硝酸鉄溶液に塩酸を添加して銀イオンを塩化銀として析出させ、該析出した塩化銀を分離回収する銀回収工程と、該塩化銀が分離された後の硝酸鉄溶液に鉄粉を添加して銅イオンを銅メタルとして析出させ、該析出した銅メタルを分離除去する脱銅工程とを有し、該銅メタルが分離された後の硝酸鉄溶液を該浸漬処理に繰り返し利用することを特徴としている。 In order to achieve the above object, the method for recovering silver according to the present invention is a method for recovering silver by immersing a coating base material containing silver and copper in an iron nitrate solution, and recovers silver ions and copper ions. A silver recovery step in which hydrochloric acid is added to the contained iron nitrate solution after the immersion treatment to precipitate silver ions as silver chloride, and the precipitated silver chloride is separated and recovered, and iron nitrate after the silver chloride is separated. It has a copper removal step of adding iron powder to the solution to precipitate copper ions as copper metal and separating and removing the precipitated copper metal, and the iron nitrate solution after the copper metal is separated is immersed in the solution. It is characterized by being used repeatedly.
本発明によれば、銀又は銀系合金で被覆された鉄系合金基材に対して、硝酸鉄含有溶液の消費量を抑制しながら、効率よく銀を回収することが可能になる。 According to the present invention, it is possible to efficiently recover silver from an iron-based alloy base material coated with silver or a silver-based alloy while suppressing the consumption of an iron nitrate-containing solution.
以下、本発明に係る銀の回収方法の第１の実施形態について図面を参照しながら詳細に説明する。本発明の第１の実施形態の銀の回収方法は、図１に示すように、処理対象となる銀及び銅を含む被覆基材を硝酸鉄溶液に浸漬させて、その基材部は溶解させずにその被覆部だけを溶解させる浸漬処理工程Ｓ１と、該浸漬処理により得た銀イオン及び銅イオンを含有する含Ａｇ＋硝酸鉄溶液に塩酸を添加して銀イオンを塩化銀として析出させた後、該析出した塩化銀を固液分離により回収する銀回収工程Ｓ２と、該銀回収工程Ｓ２で塩化銀が回収された後の脱Ａｇ＋硝酸鉄溶液に鉄粉を添加することによって、該鉄粉と銅イオンとのセメンテーション反応により該鉄粉を鉄イオンとして溶解させると共に、銅イオンを銅メタルとして析出させた後、該析出した銅メタルを含む固形分を固液分離により除去する脱銅工程Ｓ３とを有している。 Hereinafter, the first embodiment of the silver recovery method according to the present invention will be described in detail with reference to the drawings. In the method for recovering silver according to the first embodiment of the present invention, as shown in FIG. 1, a coated base material containing silver and copper to be treated is immersed in an iron nitrate solution to dissolve the base material portion. In the dipping treatment step S1 in which only the coating portion was dissolved without the dipping treatment, hydrochloric acid was added to an Ag + iron nitrate solution containing silver ions and copper ions obtained by the dipping treatment to precipitate silver ions as silver chloride. After that, by adding iron powder to the silver recovery step S2 in which the precipitated silver chloride is recovered by solid-liquid separation and the de-Ag + iron nitrate solution after the silver chloride is recovered in the silver recovery step S2. The iron powder is dissolved as iron ions by a cementation reaction between iron powder and copper ions, and copper ions are precipitated as copper metal, and then the solid content containing the precipitated copper metal is removed by solution separation. It has a copper step S3.
より具体的に説明すると、上記本発明の第１の実施形態の銀の回収方法の処理対象となる銀及び銅を含む被覆基材は、例えば鉄−ニッケル−コバルト合金などの鉄系合金金属からなる基材の片面又は両面に銀及び銅を含む合金を被覆した被覆基材を挙げることができる。この被覆基材は、電子材料の製造段階の打ち抜き加工等の際に発生する加工屑やスペックアウト品が主に対象となるが、被覆材に少なくとも銀を含む被覆基材であればこれらに限定されるものではない。 More specifically, the coating base material containing silver and copper to be treated in the silver recovery method of the first embodiment of the present invention is made from an iron-based alloy metal such as an iron-nickel-cobalt alloy. Examples thereof include a coated base material in which one side or both sides of the base material is coated with an alloy containing silver and copper. This coating base material mainly targets processing scraps and spec-out products generated during punching in the manufacturing stage of electronic materials, but is limited to these as long as the coating material contains at least silver. It is not something that is done.
上記被覆基材はそのまま上記浸漬処理工程Ｓ１で処理してもよいが、より効率よく浸漬処理を行うため、該浸漬処理前に切断、裁断、破砕などにより単位体積当たりの表面積を増やすのが好ましい。また、被覆基材に油脂等の不純物、夾雑物等が付着したり混在したりしている場合は、洗浄、分級などの前処理を行うのが好ましい。 The coating base material may be treated as it is in the dipping treatment step S1, but in order to perform the dipping treatment more efficiently, it is preferable to increase the surface area per unit volume by cutting, cutting, crushing or the like before the dipping treatment. .. Further, when impurities such as oils and fats and impurities are attached or mixed on the coating base material, it is preferable to perform pretreatment such as cleaning and classification.
上記の銀及び銅を含む合金は、例えば銀ロウを挙げることができる。この銀ロウは、ＪＩＳ Ｚ ３２６１ １９９８に規定されているように、銀及び銅を主成分とし、用途に応じて亜鉛、スズ、カドミウム、ニッケル、リチウムなどの元素が更に添加された合金であり、一般的に銅を１５〜４５％含んでいる。次に、上記した本発明の第１の実施形態の銀の回収方法を構成する各工程について説明する。 Examples of the above alloy containing silver and copper include silver brazing. As specified in JIS Z 3261 1998, this silver wax is an alloy containing silver and copper as main components and further added elements such as zinc, tin, cadmium, nickel and lithium depending on the application. It generally contains 15-45% copper. Next, each step constituting the silver recovery method of the first embodiment of the present invention described above will be described.
（１）浸漬処理工程Ｓ１
浸漬処理工程Ｓ１においては、上記被覆基材を硝酸鉄溶液に浸漬させることで、下記反応式１及び２により被覆層に含まれる銀及び銅を酸化剤としての硝酸鉄により酸化し、それぞれ銀イオン及び銅イオンとして硝酸鉄溶液中に溶解させる。
(1) Immersion treatment step S1
In the dipping treatment step S1, by immersing the coating base material in the iron nitrate solution, silver and copper contained in the coating layer are oxidized by iron nitrate as an oxidizing agent by the following reaction formulas 1 and 2, respectively, and silver ions are obtained. And as copper ions, it is dissolved in the iron nitrate solution.
［反応式１］
Ｆｅ(ＮＯ３)３＋Ａｇ→Ｆｅ(ＮＯ３)２＋Ａｇ(ＮＯ３)
［反応式２］
２Ｆｅ(ＮＯ３)３＋Ｃｕ→２Ｆｅ(ＮＯ３)２＋Ｃｕ(ＮＯ３)２
[Reaction formula 1]
Fe (NO 3 ) 3 + Ag → Fe (NO 3 ) 2 + Ag (NO 3 )
[Reaction equation 2]
2Fe (NO 3 ) 3 + Cu → 2Fe (NO 3 ) 2 + Cu (NO 3 ) 2
上記の被覆基材の浸漬処理に使用する硝酸鉄溶液は、硝酸鉄（III）を好ましくは３５〜４０質量％の濃度で含む硝酸鉄水溶液を使用する。また、浸漬処理時の該硝酸鉄溶液の温度は特に限定はないが３０〜３５℃程度であれば反応率を高めることができるので好ましい。上記の浸漬処理後は、上記銀イオン及び銅イオンを含む含Ａｇ＋硝酸鉄溶液を回収すると共に、溶解により被覆材がほぼ除去された基材を取り出す。この取り出した基材は、必要に応じて水洗等により硝酸鉄溶液を除去した後、基材の原材料として再利用される。一方、回収した硝酸鉄溶液は、次工程の銀回収工程Ｓ２で処理される。 As the iron nitrate solution used for the dipping treatment of the coating substrate, an iron nitrate aqueous solution containing iron (III) nitrate at a concentration of preferably 35 to 40% by mass is used. The temperature of the iron nitrate solution during the dipping treatment is not particularly limited, but is preferably about 30 to 35 ° C. because the reaction rate can be increased. After the dipping treatment, the Ag + iron nitrate solution containing the silver ions and the copper ions is recovered, and the base material from which the dressing has been substantially removed by dissolution is taken out. The removed base material is reused as a raw material for the base material after removing the iron nitrate solution by washing with water or the like, if necessary. On the other hand, the recovered iron nitrate solution is processed in the silver recovery step S2 of the next step.
（２）銀回収工程Ｓ２
銀回収工程Ｓ２においては、前工程の浸漬処理工程Ｓ１において回収した含Ａｇ＋硝酸鉄溶液に対して、該溶液に含まれる銀イオンの全量を塩化銀として析出させるために必要な当量の０.９〜１.０倍の塩酸を添加する。これにより、下記反応式３に示す銀イオンと塩化物イオンとの反応が生じて塩化銀が析出する。析出した塩化銀は濾過などの固液分離手段により回収され、該塩化銀が分離された後の脱Ａｇ＋硝酸鉄溶液は、後工程の脱銅工程Ｓ３で処理される。
［反応式３］
Ａｇ(ＮＯ３)＋ＨＣｌ→ＡｇＣｌ↓＋ＨＮＯ３
(2) Silver recovery step S2
In the silver recovery step S2, with respect to the Ag + iron nitrate solution recovered in the dipping treatment step S1 of the previous step, the equivalent amount required to precipitate the total amount of silver ions contained in the solution as silver chloride is 0. Add 9 to 1.0 times as much hydrochloric acid. As a result, the reaction between the silver ion represented by the following
[Reaction equation 3]
Ag (NO 3 ) + HCl → AgCl ↓ + HNO 3
上記の回収した塩化銀は、別途、公知の方法で還元反応等を経ることで金属の銀を生成することができる。上記のように、塩酸の添加量を当量の０.９〜１.０倍にする理由は、この塩酸の添加量が当量の１.０倍を超えると、塩酸が王水化して基材を溶かす可能性が高くなるからである。また、過剰な塩酸を含む硝酸鉄液を再利用のために上記浸漬処理工程Ｓ１に戻すと瞬時に塩化銀が生成されるので、この生成した塩化銀が基材と共に固形分として分離除去されてしまうからである。 The recovered silver chloride can be separately subjected to a reduction reaction or the like by a known method to produce metallic silver. As described above, the reason for increasing the amount of hydrochloric acid added to 0.9 to 1.0 times the equivalent is that when the amount of hydrochloric acid added exceeds 1.0 times the equivalent, the hydrochloric acid becomes aqua regia and the base material is formed. This is because the possibility of melting increases. Further, when the iron nitrate solution containing excess hydrochloric acid is returned to the dipping treatment step S1 for reuse, silver chloride is instantly generated, so that the produced silver chloride is separated and removed as a solid content together with the base material. Because it will end up.
（３）脱銅工程Ｓ３
上記の浸漬処理工程Ｓ１では、銀と共に銅も硝酸鉄溶液に溶解するため、上記の銀回収工程Ｓ２で銀を回収した後の脱Ａｇ＋硝酸鉄溶液をそのまま繰り返して使用した場合は、銅イオンが系内に蓄積していくことになる。その結果、前述したとおり、銀の溶解能力が低下して銀の回収効率が低下する。そこで、脱銅工程Ｓ３においては、鉄粉を添加することで脱Ａｇ＋硝酸鉄溶液に含まれる銅イオンを除去する。
(3) Copper removal step S3
In the dipping treatment step S1, copper is dissolved in the iron nitrate solution together with silver. Therefore, when the de-Ag + iron nitrate solution after silver is recovered in the silver recovery step S2 is repeatedly used as it is, copper ions are formed. Will accumulate in the system. As a result, as described above, the silver dissolving ability is lowered and the silver recovery efficiency is lowered. Therefore, in the copper removal step S3, copper ions contained in the de-Ag + iron nitrate solution are removed by adding iron powder.
具体的には、銅イオンが含まれている脱Ａｇ＋硝酸鉄溶液に所定量の鉄粉を添加することにより、鉄メタルと銅イオンとのセメンテーション反応が生じて該銅イオンが銅メタルとして析出する。すなわち、セメンテーション反応は、水溶液中に存在する酸化還元電位が貴な金属イオンを卑な金属メタルによって還元して析出させる反応であり、上記の場合では、銅は鉄よりもイオン化傾向が低い、すなわち銅は鉄よりも貴な金属であるので、銅イオンを含んだ脱Ａｇ＋硝酸鉄溶液に鉄粉を添加することで鉄メタルを鉄イオンとして溶出させながら銅イオンを銅メタルとして析出することができる。この析出した銅メタルは、未反応の鉄粉と共に含Ｃｕ固形分として濾過などの固液分離手段よって除去することができる。なお、塩化物イオンは、この脱銅工程Ｓ３によっては消費されない。 Specifically, by adding a predetermined amount of iron powder to a de-Ag + iron nitrate solution containing copper ions, a cementation reaction between the iron metal and the copper ions occurs, and the copper ions become copper metal. Precipitate. That is, the cementation reaction is a reaction in which a metal ion having a noble oxidation-reduction potential in an aqueous solution is reduced and precipitated by a base metal metal. In the above case, copper has a lower ionization tendency than iron. That is, since copper is a nobler metal than iron, by adding iron powder to a de-Ag + iron nitrate solution containing copper ions, copper ions are precipitated as copper metal while eluting iron metal as iron ions. Can be done. The precipitated copper metal can be removed together with unreacted iron powder as a Cu-containing solid content by a solid-liquid separation means such as filtration. Chloride ions are not consumed by this copper removal step S3.
上記の含Ｃｕ固形分が除去された処理済硝酸鉄溶液は、上記浸漬処理工程Ｓ１の浸漬処理用溶液として繰り返し使用される。上記の鉄粉の添加量は、脱銅工程Ｓ３で処理する脱Ａｇ＋硝酸鉄溶液に含まれる銅イオンを全て銅メタルにするために必要な当量に余裕率をかけた量とし、この余裕率は１.１〜１.３程度が好ましい。上記添加する鉄粉は、粒径が約２０〜２００μｍ程度の鉄粒子を用いるのが好ましく、例えばパウダーテック株式会社製の鉄粉を好適に用いることができる。 The treated iron nitrate solution from which the Cu-containing solid content has been removed is repeatedly used as the dipping treatment solution in the dipping treatment step S1. The above-mentioned amount of iron powder added is an amount obtained by multiplying the equivalent amount required to convert all the copper ions contained in the de-Ag + iron nitrate solution treated in the copper removal step S3 into copper metal by a margin ratio, and this margin ratio. Is preferably about 1.1 to 1.3. As the iron powder to be added, it is preferable to use iron particles having a particle size of about 20 to 200 μm, and for example, iron powder manufactured by Powdertech Co., Ltd. can be preferably used.
ところで、上記の浸漬処理Ｓ１によって硝酸鉄溶液に溶解する銅の量は、処理対象となる被覆基材を定量分析したり、上記浸漬処理工程Ｓ１や銀回収工程Ｓ２によって得られる硝酸鉄溶液中の銅イオン濃度を定量分析したりすることで知ることができる。そして、この硝酸鉄溶液中の銅イオン濃度が前述した硝酸鉄溶液の溶解能力を低下させる濃度よりも低い場合は、浸漬処理工程Ｓ１によって得られる含Ａｇ＋硝酸鉄溶液の全量を、上記の脱銅工程Ｓ３で処理する必要はない。 By the way, the amount of copper dissolved in the iron nitrate solution by the dipping treatment S1 can be determined by quantitatively analyzing the coating base material to be treated, or in the iron nitrate solution obtained by the dipping treatment step S1 or the silver recovery step S2. It can be known by quantitative analysis of the copper ion concentration. When the copper ion concentration in the iron nitrate solution is lower than the concentration that reduces the dissolving ability of the iron nitrate solution described above, the total amount of Ag + iron nitrate solution obtained in the dipping treatment step S1 is removed. It is not necessary to process in the copper step S3.
そこで、本発明の銀の回収方法の第２の実施形態においては、浸漬処理工程で得た含Ａｇ＋硝酸鉄溶液を２つに分け、それらのうちの一方にのみ上記の脱銅工程で処理を行う。具体的には、図２に示すように、本発明の第２の実施形態の銀の回収方法は、上記の本発明の第１の実施形態の銀の回収方法と同様にして浸漬処理工程Ｓ１１において被覆基材を浸漬処理した後、得られた含Ａｇ＋硝酸鉄溶液を例えば上記の被覆基材の定量分析結果に基づいて２つに分ける。 Therefore, in the second embodiment of the silver recovery method of the present invention, the Ag-containing + iron nitrate solution obtained in the dipping treatment step is divided into two, and only one of them is treated by the above copper removal step. I do. Specifically, as shown in FIG. 2, the silver recovery method of the second embodiment of the present invention is the same as the silver recovery method of the first embodiment of the present invention described above, and the dipping treatment step S11. After the coating base material is immersed in the coating base material, the obtained Ag + iron nitrate solution is divided into two based on, for example, the above-mentioned quantitative analysis result of the coating base material.
そして、この２つに分けた内の一方に対して、浸漬処理工程Ｓ１１で得られた該２つに分ける前の含Ａｇ＋硝酸鉄溶液中の銀イオンの全量を塩化銀として析出させるために必要な当量の塩酸を添加し、該一方の含Ａｇ＋硝酸鉄溶液中の銀イオンを過剰の塩酸と反応させて塩化銀を析出させた後、該析出した塩化銀を固液分離により回収する銀回収工程Ｓ１２と、該銀回収工程Ｓ１２で塩化銀が回収された後の余剰の塩化物イオンを有する含Ｃｌ−脱Ａｇ＋硝酸鉄溶液に鉄粉を添加することによって、該鉄粉と銅イオンとのセメンテーション反応により該鉄粉を鉄イオンに溶解させると共に、銅イオンを銅メタルとして析出させた後、該析出した銅メタルを含む固形分を固液分離により除去する脱銅工程Ｓ１３と、該固形分が除去された含Ｃｌ−脱Ｃｕ２＋硝酸鉄溶液に、上記の２つに分けた含Ａｇ＋硝酸鉄溶液のもう一方を混合することで該もう一方の含Ａｇ＋硝酸鉄溶液に含まれる銀イオンを塩化銀として析出させた後、該析出した塩化銀を固液分離により回収する追加銀回収工程Ｓ１４とを有している。 Then, in order to deposit the total amount of silver ions in the Ag-containing + iron nitrate solution obtained in the dipping treatment step S11 into one of the two parts as silver chloride. A required equivalent amount of copper is added, and silver ions in one of the Ag + iron nitrate solutions are reacted with excess hydrochloric acid to precipitate silver chloride, and then the precipitated silver chloride is recovered by solid-liquid separation. The iron powder and copper are added to the silver recovery step S12 and the Cl- de-Ag + iron nitrate solution having excess chloride ions after the silver chloride is recovered in the silver recovery step S12. A copper removal step S13 in which the iron powder is dissolved in iron ions by a cementation reaction with ions, copper ions are precipitated as copper metal, and then the solid content containing the precipitated copper metal is removed by solution separation. , including Cl solid content has been removed - the de Cu 2+ iron nitrate solution, the other containing Ag + iron nitrate solution by mixing the other containing Ag + iron nitrate solution was divided into two of the It has an additional silver recovery step S14 in which the silver ions contained in the above are precipitated as silver chloride and then the precipitated silver chloride is recovered by solid-liquid separation.
上記の追加銀回収工程Ｓ１４で得られる処理済硝酸鉄溶液は、上記浸漬処理工程Ｓ１１の浸漬処理用溶液として繰り返し使用される。このように、本発明の第２の実施形態の銀の回収方法では、銀回収工程Ｓ１２で得られる硝酸鉄溶液中には、余剰の塩化物イオンが存在するので、鉄粉の溶解を促進することができ、よって、より効率的に銅メタルを析出させることができる。また、脱銅工程Ｓ１３では塩化物イオンが消費されることはないから、該脱銅工程Ｓ１３で得た含Ｃｌ−脱Ｃｕ２＋硝酸鉄溶液を該脱銅工程Ｓ１３を経ていないもう一方の含Ａｇ＋硝酸鉄溶液と混合することにより、該もう一方の含Ａｇ＋硝酸鉄溶液に含まれる銀イオンを塩化銀として析出させることができる。すなわち、本発明の第２の実施形態の銀の回収方法は、被覆基材の浸漬処理に用いた硝酸鉄溶液のうちの一部に対してその当量分の鉄粉を添加するので、鉄粉の消費量を抑制することができるうえ、脱銅設備の規模を小さく抑えることができる。 The treated iron nitrate solution obtained in the additional silver recovery step S14 is repeatedly used as the dipping treatment solution in the dipping treatment step S11. As described above, in the silver recovery method of the second embodiment of the present invention, excess chloride ions are present in the iron nitrate solution obtained in the silver recovery step S12, so that the dissolution of iron powder is promoted. Therefore, the copper metal can be deposited more efficiently. Further, since chloride ions are not consumed in the copper removal step S13, the Cl - de-Cu 2 + iron nitrate solution obtained in the copper removal step S13 is mixed with the other Ag-containing Ag that has not undergone the copper removal step S13. + by mixing with iron nitrate solution, the silver ions contained in the other containing Ag + iron nitrate solution can be precipitated as silver chloride. That is, in the method for recovering silver according to the second embodiment of the present invention, the equivalent amount of iron powder is added to a part of the iron nitrate solution used for the dipping treatment of the coating base material, so that the iron powder is added. In addition to being able to reduce the consumption of copper, the scale of the copper removal equipment can be kept small.
以上説明したように、本発明に係る銀の回収方法の実施形態により、硝酸鉄溶液から容易に銅を除去すると共に銀を回収することができるので、該硝酸鉄溶液を繰り返し使用しているうちに該硝酸鉄溶液中に銅イオンの濃度が増加して溶解能力が低下する問題を抑制することができる。これにより、硝酸イオン濃度の調整のために多量の硝酸を補充する必要がなくなる。次に、本発明の銀の回収方法について実施例を挙げて説明するが、本発明は下記の実施例に何ら限定されるものではない。 As described above, according to the embodiment of the silver recovery method according to the present invention, copper can be easily removed from the iron nitrate solution and silver can be recovered. Therefore, while the iron nitrate solution is used repeatedly. In addition, it is possible to suppress the problem that the concentration of copper ions in the iron nitrate solution increases and the dissolving ability decreases. This eliminates the need to replenish a large amount of nitric acid to adjust the nitrate ion concentration. Next, the method for recovering silver of the present invention will be described with reference to examples, but the present invention is not limited to the following examples.
［実施例］
銀イオン及び銅イオンを含む硝酸鉄水溶液に対して図２の銀回収工程Ｓ１２、脱銅工程Ｓ１３、及び追加銀回収工程Ｓ１４のフローに沿って処理して銀イオンを塩化銀として回収した。具体的には、銅イオン濃度が４２.０ｇ／Ｌ、鉄イオン濃度が５８.０ｇ／Ｌ、銀イオン濃度が１２.０ｇ／Ｌとなるように調製した硝酸鉄水溶液１０００Ｌを１００Ｌと９００Ｌの２つに分け、前者の１００Ｌの硝酸鉄溶液を撹拌機付きの反応槽へ入れた。この反応槽に更に３５％塩酸１０Ｌを添加して、撹拌により混合した。その結果、硝酸鉄溶液中に１回目の析出物の沈降が生じたので、該反応槽内の内容物を全て濾過器に導入して１回目の濾過を行ない、該１回目濾過の固形分を回収した。
[Example]
The silver nitrate aqueous solution containing silver ions and copper ions was treated according to the flow of the silver recovery step S12, the copper removal step S13, and the additional silver recovery step S14 of FIG. 2, and the silver ions were recovered as silver chloride. Specifically, 100 L and 900 L of an iron nitrate aqueous solution prepared so that the copper ion concentration is 42.0 g / L, the iron ion concentration is 58.0 g / L, and the silver ion concentration is 12.0 g / L are 2 The former 100 L iron nitrate solution was placed in a reaction vessel equipped with a stirrer. Further, 10 L of 35% hydrochloric acid was added to this reaction vessel, and the mixture was mixed by stirring. As a result, the first precipitation occurred in the iron nitrate solution, so all the contents in the reaction vessel were introduced into the filter to perform the first filtration, and the solid content of the first filtration was obtained. Recovered.
次に、この１回目濾過により得た濾液を撹拌機付きの反応槽に入れ、更にこの反応槽にパウダーテック株式会社製の鉄粉（汎用タイプＤＥ−５０、２５ｋｇ／袋）を２.８ｋｇ添加して攪拌により混合した。その結果、硝酸鉄溶液中に析出物が生じたので、該反応槽内の内容物を全て濾過機に導入して２回目の濾過を行ない、該２回目濾過の固形分を回収した。この２回目濾過により得た濾液を撹拌機付き反応槽に入れ、更にこの反応槽に前述した２つに分けた後者の９００Ｌの硝酸鉄溶液を入れて攪拌により混合した。その結果、硝酸溶液中に３回目の析出物が生じたので、該反応槽内の内容物を全て濾過機に導入して３回目の濾過を行ない、該３回目濾過の固形分を回収した。 Next, the filtrate obtained by this first filtration is placed in a reaction tank equipped with a stirrer, and 2.8 kg of iron powder (general-purpose type DE-50, 25 kg / bag) manufactured by Powdertech Co., Ltd. is further added to this reaction tank. And mixed by stirring. As a result, a precipitate was formed in the iron nitrate solution, so that all the contents in the reaction vessel were introduced into the filter to perform the second filtration, and the solid content of the second filtration was recovered. The filtrate obtained by this second filtration was placed in a reaction vessel equipped with a stirrer, and the latter 900 L iron nitrate solution divided into the above two was further added to the reaction vessel and mixed by stirring. As a result, a third precipitate was formed in the nitric acid solution, so all the contents in the reaction vessel were introduced into a filter to perform the third filtration, and the solid content of the third filtration was recovered.
［比較例］
上記１回目の濾過前の１００Ｌの硝酸鉄溶液に塩酸を添加することに代えて、上記２回目の濾過により得た濾液に９００Ｌの硝酸鉄溶液を混合した混合液に塩酸を添加したこと以外は、上記実施例と同様にして硝酸鉄水溶液から銀を回収した。この場合、１回目の濾過前の硝酸鉄水溶液には塩酸を添加しなかったため、該１回目の濾過では固形分は全く回収されなかった。
[Comparison example]
Instead of adding hydrochloric acid to the 100 L iron nitrate solution before the first filtration, hydrochloric acid was added to the mixed solution of 900 L of the iron nitrate solution mixed with the filtrate obtained by the second filtration. , Silver was recovered from the iron nitrate aqueous solution in the same manner as in the above example. In this case, since hydrochloric acid was not added to the iron nitrate aqueous solution before the first filtration, no solid content was recovered in the first filtration.
［評価］
上記の実施例及び比較例でそれぞれ回収した固形分を乾燥した後、それら乾燥物の質量の測定、及び誘導結合プラズマ（ＩＣＰ）発光分光分析装置による組成分析を行った。また、脱銅工程Ｓ１３における脱銅率を算出すると共に、銀回収工程Ｓ１２及び追加銀回収工程Ｓ１４の合計の銀回収率を算出した。その結果を下記表１に示す。
[evaluation]
After the solids recovered in the above Examples and Comparative Examples were dried, the masses of the dried products were measured and the composition was analyzed by an inductively coupled plasma (ICP) emission spectroscopic analyzer. In addition, the copper removal rate in the copper removal step S13 was calculated, and the total silver recovery rate of the silver recovery step S12 and the additional silver recovery step S14 was calculated. The results are shown in Table 1 below.
上記表１の結果より、実施例の銀の回収方法は、硝酸鉄溶液中に含まれる銀イオンの大部分を塩化銀として回収することができるうえ、一部の銅イオンを容易に除去できることが分かった。一方、比較例の銀の回収方法は、銀イオンについては実施例とほぼ同程度に回収できるものの、脱銅処理の前に塩酸による銀の回収を行わないことにより、銅イオンをセメンテーション反応でほとんど除去できないことが分かった。 From the results in Table 1 above, the silver recovery method of the example can recover most of the silver ions contained in the iron nitrate solution as silver chloride, and can easily remove some copper ions. Do you get it. On the other hand, in the method of recovering silver in Comparative Example, although silver ions can be recovered to almost the same level as in Examples, copper ions are cemented by a cementation reaction by not recovering silver with hydrochloric acid before the decopper treatment. It turned out that it could hardly be removed.
なお、本実施例で調製した硝酸鉄水溶液は、銀ロウで被覆された鉄−ニッケル−コバルト合金の基材の加工屑に対して、バッチ処理により工業的規模で銀の回収を行う場合に得られる含Ａｇ＋硝酸鉄水溶液の１バッチ分にほぼ相当している。この工業的規模での加工屑からの銀の回収では、上記１バッチあたり銅イオンの濃度が約２ｇ／Ｌ増加することが確認されている。これに対して、上記実施例の銀の回収方法では脱銅工程Ｓ１３において硝酸鉄溶液中の銅の濃度が約２ｇ／Ｌ減少することができる。 The iron nitrate aqueous solution prepared in this example is obtained when silver is recovered on an industrial scale by batch processing on the processing waste of the base material of the iron-nickel-cobalt alloy coated with silver wax. It is almost equivalent to one batch of Ag-containing + iron nitrate aqueous solution. In the recovery of silver from the processing waste on this industrial scale, it has been confirmed that the concentration of copper ions per batch increases by about 2 g / L. On the other hand, in the silver recovery method of the above example, the concentration of copper in the iron nitrate solution can be reduced by about 2 g / L in the copper removal step S13.
すなわち、上記の工業的規模での加工屑からの硝酸鉄水溶液による銀の回収処理のバッチ毎に該銀の回収時に得られる含Ａｇ＋硝酸鉄水溶液の１／１０の量に対して脱銅処理を行うだけで、該硝酸鉄水溶液に銀と共に溶解する銅のほとんどを除去することができる。よって、該硝酸鉄水溶液を繰り返し使用しても、その溶解能力が低下する問題を抑えることができる。このように、加工屑等から硝酸鉄溶液を用いて銀を回収したときの条件に応じて、該硝酸鉄水溶液の一部に対して脱銅処理するだけで該硝酸鉄水溶液を使い続けることができるので、コストを抑えた銀の回収が可能になる。 That is, for each batch of silver recovery treatment with an iron nitrate aqueous solution from the above-mentioned industrial scale processing waste, copper removal treatment is performed with respect to the amount of Ag-containing + 1/10 of the iron nitrate aqueous solution obtained at the time of silver recovery. Most of the copper dissolved together with silver in the iron nitrate aqueous solution can be removed by simply performing. Therefore, even if the iron nitrate aqueous solution is used repeatedly, the problem that its dissolving ability is lowered can be suppressed. In this way, depending on the conditions when silver is recovered from the processing waste or the like using the iron nitrate solution, the iron nitrate aqueous solution can be continued to be used only by decopperizing a part of the iron nitrate aqueous solution. Since it can be done, it is possible to recover silver at a low cost.
Ｓ１、Ｓ１１ 浸漬処理工程
Ｓ２、Ｓ１２ 銀回収工程
Ｓ３、Ｓ１３ 脱銅工程
Ｓ１４ 追加銀回収工程
S1, S11 Immersion process S2, S12 Silver recovery process S3, S13 Copper removal process S14 Additional silver recovery process
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| JP2007182598A (en) * | 2006-01-05 | 2007-07-19 | Keiichi Tachibana | Method for recovering metal copper from industrial waste liquid containing copper chloride |
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