JP6750454B2 - Method for removing impurities from bismuth electrolyte - Google Patents
Method for removing impurities from bismuth electrolyte Download PDFInfo
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- JP6750454B2 JP6750454B2 JP2016211497A JP2016211497A JP6750454B2 JP 6750454 B2 JP6750454 B2 JP 6750454B2 JP 2016211497 A JP2016211497 A JP 2016211497A JP 2016211497 A JP2016211497 A JP 2016211497A JP 6750454 B2 JP6750454 B2 JP 6750454B2
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- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 title claims description 101
- 229910052797 bismuth Inorganic materials 0.000 title claims description 92
- 238000000034 method Methods 0.000 title claims description 62
- 239000012535 impurity Substances 0.000 title claims description 30
- 239000003792 electrolyte Substances 0.000 title claims 3
- 229910052709 silver Inorganic materials 0.000 claims description 63
- 239000004332 silver Substances 0.000 claims description 63
- 239000008151 electrolyte solution Substances 0.000 claims description 53
- 229910052751 metal Inorganic materials 0.000 claims description 39
- 239000002184 metal Substances 0.000 claims description 39
- 238000003756 stirring Methods 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 10
- 239000003929 acidic solution Substances 0.000 claims description 6
- GTKRFUAGOKINCA-UHFFFAOYSA-M chlorosilver;silver Chemical compound [Ag].[Ag]Cl GTKRFUAGOKINCA-UHFFFAOYSA-M 0.000 claims description 6
- 239000010953 base metal Substances 0.000 claims description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 59
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 38
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 37
- 229910052802 copper Inorganic materials 0.000 description 37
- 239000010949 copper Substances 0.000 description 37
- 239000000243 solution Substances 0.000 description 30
- 238000005868 electrolysis reaction Methods 0.000 description 21
- 238000002386 leaching Methods 0.000 description 21
- 239000002253 acid Substances 0.000 description 15
- 239000003513 alkali Substances 0.000 description 15
- 238000007670 refining Methods 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 10
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 9
- 229910052711 selenium Inorganic materials 0.000 description 9
- 239000011669 selenium Substances 0.000 description 9
- 229910052714 tellurium Inorganic materials 0.000 description 9
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 9
- 238000000638 solvent extraction Methods 0.000 description 8
- 229910000510 noble metal Inorganic materials 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 6
- 229910000416 bismuth oxide Inorganic materials 0.000 description 6
- TYIXMATWDRGMPF-UHFFFAOYSA-N dibismuth;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Bi+3].[Bi+3] TYIXMATWDRGMPF-UHFFFAOYSA-N 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 5
- 229910052737 gold Inorganic materials 0.000 description 5
- 239000010931 gold Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- 239000007858 starting material Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 238000003723 Smelting Methods 0.000 description 4
- 229910000380 bismuth sulfate Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- BEQZMQXCOWIHRY-UHFFFAOYSA-H dibismuth;trisulfate Chemical compound [Bi+3].[Bi+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O BEQZMQXCOWIHRY-UHFFFAOYSA-H 0.000 description 4
- 238000006386 neutralization reaction Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 239000010970 precious metal Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 238000005363 electrowinning Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000033116 oxidation-reduction process Effects 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 239000012255 powdered metal Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- -1 silver halide Chemical class 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 229910052787 antimony Inorganic materials 0.000 description 2
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000013067 intermediate product Substances 0.000 description 2
- 239000011133 lead Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- STCOOQWBFONSKY-UHFFFAOYSA-N tributyl phosphate Chemical compound CCCCOP(=O)(OCCCC)OCCCC STCOOQWBFONSKY-UHFFFAOYSA-N 0.000 description 2
- KZVBBTZJMSWGTK-UHFFFAOYSA-N 1-[2-(2-butoxyethoxy)ethoxy]butane Chemical compound CCCCOCCOCCOCCCC KZVBBTZJMSWGTK-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- MBIDWOISWGGCJD-UHFFFAOYSA-N [O].[Bi].[Bi] Chemical compound [O].[Bi].[Bi] MBIDWOISWGGCJD-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 229910001451 bismuth ion Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- 229910000856 hastalloy Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000012074 organic phase Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- YPNVIBVEFVRZPJ-UHFFFAOYSA-L silver sulfate Chemical compound [Ag+].[Ag+].[O-]S([O-])(=O)=O YPNVIBVEFVRZPJ-UHFFFAOYSA-L 0.000 description 1
- 229910000367 silver sulfate Inorganic materials 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Manufacture And Refinement Of Metals (AREA)
- Electrolytic Production Of Metals (AREA)
Description
本発明は、ビスマス電解液からの不純物を除去方法に関する。さらに詳しくは、銅電解精製工程で発生する銅電解スライムから有価金属であるビスマスを回収する精製工程の中間生成物であるビスマス電解液から不純物を除去する方法に関する。 The present invention relates to a method for removing impurities from a bismuth electrolytic solution. More specifically, it relates to a method for removing impurities from a bismuth electrolytic solution which is an intermediate product of a refining step of recovering bismuth which is a valuable metal from copper electrolysis slime generated in a copper electrorefining step.
銅を含有する鉱石から銅を回収する方法として、銅を含有する鉱石を選鉱工程に付して銅を濃縮した銅精鉱を得、次にこの銅精鉱を炉に投入して高温で熔融する乾式製錬に付して粗銅を得、次にこの粗銅をアノードとして硫酸酸性溶液に浸漬し、同時に面対して浸漬したステンレスや銅の板を用いたカソードとの間に電流を流し、アノードから溶解した銅を選択的にカソード上に電析させる電解精製に付すことを経て、高純度な電気銅を得る方法が一般的に用いられてきた。 As a method of recovering copper from an ore containing copper, the ore containing copper is subjected to a beneficiation process to obtain a copper concentrate enriched with copper, and then the copper concentrate is put into a furnace and melted at a high temperature. Crude copper is obtained by subjecting it to dry smelting, and then this crude copper is immersed as an anode in a sulfuric acid acidic solution, and at the same time, a current is passed between the cathode and a stainless steel or copper plate that is immersed face-to-face A method for obtaining electrolytic copper having a high purity through electrolytic refining in which the dissolved copper is selectively electrodeposited on the cathode has been generally used.
上記の銅を含有する鉱石には、目的とする銅のほかに金銀などの貴金属やビスマスやヒ素やアンチモンやセレンや鉛や鉄やテルルなどの有価物でもあり不純物でもある多種多様な成分が含有されることが多い。これらの成分は、上記の乾式製錬でスラグとして分離されたり、電解精製では銅電解スライムとして貴金属とともに電解槽の底に沈積されたりするなどして銅と分離される。
上記の銅電解スライムは、前述するように多種多様な成分が含有されているため、このスライムを精製して目的とする有価物を回収する処理が必要となる。
In addition to the desired copper, the above-mentioned copper-containing ores contain precious metals such as gold and silver, bismuth, arsenic, antimony, selenium, lead, iron, tellurium, and other valuable substances and impurities. It is often done. These components are separated from copper by being separated as slag in the above-mentioned dry smelting or being deposited as copper electrolytic slime together with a precious metal on the bottom of the electrolytic cell in electrolytic refining.
Since the above-mentioned copper electrolytic slime contains a wide variety of components as described above, it is necessary to purify the slime to recover the intended valuables.
スライムを精製する方法としてはいくつかの方法が知られているが、その中の一つの方法として、銅電解スライムに硫酸を添加して銅電解スライムに混在する銅を溶解して除去する脱銅工程を行い、次に脱銅して得た脱銅スライムを炉に入れて高温に加熱し、セレン、アンチモンを揮発して分離し、次に酸化して鉛を酸化物として分離し、その後に貴金属とビスマスを分離する方法がある。 There are several known methods for refining slime, but one of them is to remove copper by adding sulfuric acid to copper electrolytic slime to dissolve and remove copper mixed in copper electrolytic slime. Then, the decoppered slime obtained by decopperizing is placed in a furnace and heated to a high temperature to volatilize and separate selenium and antimony, and then oxidize to separate lead as an oxide, and then There is a method of separating precious metal and bismuth.
上記の方法は、大量の物量を取り扱うのには適した方法であるが、一方で大掛かりな設備が必要で、処理に要するエネルギーコストも大きく、また貴金属を回収できるのが工程の後半になるので仕掛り金利がかさむなどの課題があった。 The above method is suitable for handling a large amount of material, but on the other hand, it requires large-scale equipment, the energy cost required for processing is large, and the precious metal can be recovered in the latter half of the process. There were issues such as the in-process interest rate increasing.
そこで近年では、湿式方法を中心とした新しい処理プロセスが広く実用化されてきた。これら湿式処理プロセスは、セレン分離に湿式還元法を採用するか、焙焼法を採用するかにより、以下の二つの方法に大別される。 Therefore, in recent years, new treatment processes centering on the wet method have been widely put into practical use. These wet treatment processes are roughly classified into the following two methods depending on whether a wet reduction method or a roasting method is used for selenium separation.
第一の方法は、非特許文献１や特許文献１あるいは特許文献２に示される方法である。
これらの方法では、銅電解スライムに硫酸と酸素を加えて高温高圧下でテルルの一部と銅を浸出する。次に浸出して得た残渣に塩酸及び過酸化水素あるいは塩素を加えて金、白金族元素、セレン、テルルを浸出する。
The first method is the method shown in Non-Patent Document 1, Patent Document 1 or Patent Document 2.
In these methods, sulfuric acid and oxygen are added to copper electrolytic slime to leach a part of tellurium and copper under high temperature and high pressure. Next, hydrochloric acid and hydrogen peroxide or chlorine are added to the residue obtained by leaching, and gold, platinum group element, selenium and tellurium are leached.
つぎに、この浸出液に有機抽出剤であるビス（２−ブトキシエチル）エーテル（以後ＤＢＣと表記する）を混合して金を抽出剤中に抽出し、その抽残液を二酸化硫黄で還元してセレン、テルル、白金族元素を回収する。セレン、テルル、白金族元素の混合物はメタル状態のまま蒸留することにより、セレンとテルル及び白金族元素とに分離される。塩素浸出残渣は、アンモニア水にて処理することにより銀を浸出し、この浸出液から銀が粉末として回収される。 Next, bis(2-butoxyethyl)ether (hereinafter referred to as DBC) that is an organic extractant is mixed with this leachate to extract gold into the extractant, and the raffinate is reduced with sulfur dioxide. Selenium, tellurium and platinum group elements are recovered. A mixture of selenium, tellurium, and a platinum group element is distilled in a metal state to be separated into selenium, tellurium, and a platinum group element. The chlorine leaching residue is leached out of silver by treating it with ammonia water, and silver is recovered as a powder from the leached solution.
第二の方法は、非特許文献２に示す方法である。すわなち、銅電解スライムを硫酸による加圧浸出に付して、脱銅、脱テルルを行なう工程までは上記第一の方法と同じであるが、その後残渣を硫酸と混合し、焙焼してセレンを揮発分離すると同時に、残渣中の銀を硫酸銀に変換する。そして硫酸焙焼残渣は、まず、硝酸カルシウム水溶液を用いて銀を浸出し、この浸出液を電解することにより銀メタルを回収する。 The second method is the method shown in Non-Patent Document 2. That is, the steps are the same as those in the first method described above up to the steps of performing copper electrolytic slime pressure leaching with sulfuric acid to perform copper removal and tellurium removal, but then the residue is mixed with sulfuric acid and roasted. The selenium is volatilized and separated, and at the same time, the silver in the residue is converted into silver sulfate. Then, in the sulfuric acid roasting residue, first, silver is leached using an aqueous solution of calcium nitrate, and the leachate is electrolyzed to recover silver metal.
銀を浸出した残渣は、塩酸及び塩素にて金、白金族、セレン、及び残留しているテルルを浸出する。この浸出液にＤＢＣを混合して金を抽出するが、この原理は第一の方法と同じである。更に、この抽残液をヒドラジン還元することにより、白金族元素とテルルとを金属粉として回収する。 The silver leaching residue leaches gold, platinum group, selenium, and residual tellurium with hydrochloric acid and chlorine. DBC is mixed with this leachate to extract gold, and the principle is the same as in the first method. Further, the platinum group element and tellurium are recovered as metal powder by reducing the extraction residue solution with hydrazine.
なお、上記の第二の方法における硫酸焙焼残渣から銀を回収する法としては、上記第一の方法と同様に、アンモニアを使用する方法、亜硫酸ナトリウムを使用する方法も提案されている。 As the method for recovering silver from the sulfuric acid roasting residue in the above-mentioned second method, a method using ammonia and a method using sodium sulfite are also proposed, as in the above-mentioned first method.
しかるに、上記２つの方法では、いくつかの有価物並びに不純物の分離方法として、例えばビスマスに関しては、湿式工程で回収することは示されていない。ビスマスは従来から行われてきた乾式工程を用いて熔融し、スラグから回収する方法が一般的である。しかし乾式工程を実現するためには炉を設けるための投資や使用するエネルギーなどの投資や費用が大きくなる等の問題があり好ましくなかった。 However, in the above two methods, as a method for separating some valuables and impurities, for example, bismuth is not shown to be recovered in a wet process. Bismuth is generally melted using a conventionally used dry process and recovered from slag. However, in order to realize the dry process, there are problems such as an increase in investment for setting up a furnace, investment in energy used, and the like, which is not preferable.
上記の問題を解決するために銅と貴金属とビスマスと不純物とを含有する鉱物を製錬して得た粗銅を電解精製に付して銅を回収し、次に電解精製を行うことで生成した電解スライムから湿式法により貴金属を回収する工程において、貴金属を回収後に生成した酸性溶液を以下の各工程に付して金属ビスマスを得る方法が提案されている。 Crude copper obtained by smelting a mineral containing copper, noble metal, bismuth and impurities in order to solve the above problem was subjected to electrolytic refining to recover copper, and then produced by electrolytic refining. In the step of recovering noble metal from electrolytic slime by a wet method, a method has been proposed in which an acidic solution produced after recovering the noble metal is subjected to the following steps to obtain metal bismuth.
１）前記酸性溶液にアルカリを添加してｐＨを２．０以上３．０以下の範囲に調整し、次いで固液分離して中和濾液と中和澱物を得る中和処理工程
２）前記中和澱物にアルカリを添加してアルカリ浸出液とアルカリ浸出残渣に分離するアルカリ浸出工程
３）前記アルカリ浸出残渣に硫酸を添加して硫酸浸出液と硫酸浸出残渣とに分離する硫酸浸出工程
４）前記硫酸浸出液を冷却し、硫酸ビスマスの結晶を得る冷却工程
５）前記硫酸ビスマスの結晶にアルカリを加え、酸化ビスマスを得るビスマス酸化工程
６）前記酸化ビスマスに酸溶液を添加して溶解し、得た溶解液を電解採取して金属ビスマスを得る電解工程
1) An alkali is added to the acidic solution to adjust the pH to a range of 2.0 or more and 3.0 or less, and then solid-liquid separation is performed to obtain a neutralized filtrate and a neutralized precipitate. Alkali leaching step 3) in which alkali is added to the neutralized precipitate to separate it into an alkali leaching solution and an alkali leaching residue 3) Sulfuric acid leaching step 4) in which sulfuric acid is added to the alkali leaching residue to separate it into a sulfuric acid leaching solution and a sulfuric acid leaching residue Cooling step of cooling the sulfuric acid leachate to obtain crystals of bismuth sulfate 5) adding alkali to the crystals of bismuth sulfate and obtaining bismuth oxide bismuth oxidation step 6) adding an acid solution to the bismuth oxide and dissolving it Electrolysis process to obtain metal bismuth by electrowinning the solution
上記の方法を用いた場合、電解工程の原料になる酸化ビスマス中に銀が濃縮されることから、単純に酸化物を溶解して得た電解液中には銀が不純物として多く含まれる。
金属ビスマスを得るための電解液としては、例えばケイフッ酸濃度が３００〜３５０ｇ／Ｌ、ビスマス濃度が５０〜１００ｇ／Ｌの水溶液が用いられるが、銀はビスマスより貴な金属であることから、微量でも電解液中に存在した場合、銀がビスマスよりも優先的に析出し、高品位な金属ビスマス、例えば４Ｎグレードの金属ビスマスを得ることができない。電解始液のビスマス濃度が５０ｇ／Ｌ、電解終液のビスマス濃度が３０ｇ／Ｌになるように電解した場合では銀のみを不純物として考えた場合でも、計算上は２ｍｇ／Ｌ未満（全量析出するとした場合）にしなければならない。
When the above method is used, since silver is concentrated in bismuth oxide which is a raw material for the electrolysis step, the electrolytic solution obtained by simply dissolving the oxide contains a large amount of silver as an impurity.
As the electrolytic solution for obtaining the metal bismuth, for example, an aqueous solution having a hydrosilicofluoric acid concentration of 300 to 350 g/L and a bismuth concentration of 50 to 100 g/L is used. However, when it is present in the electrolytic solution, silver is preferentially deposited over bismuth, and high-quality metal bismuth, for example, 4N grade metal bismuth cannot be obtained. When electrolysis was carried out so that the bismuth concentration in the electrolysis starter solution was 50 g/L and the bismuth concentration in the electrolysis end solution was 30 g/L, even if only silver was considered as an impurity, the calculated amount was less than 2 mg/L (if the total amount is deposited, If you do)
銀を除去する方法としてはハロゲン化銀による沈殿除去が知られているが、微量ではあるが、溶解度があるため、完全な除去はできない。例えば特許文献３では塩化銀では７５ｍｇ／Ｌ程度の溶解度をもつため、リン酸系の抽出剤であるＴＢＰ（トリブチルフォスフェート）を用いた溶媒抽出によって１００ｍｇ／Ｌ程度の希薄溶液からの銀の回収を試みている。しかしこの目的においても前記に理由によって沈殿法が適用できないことは同様である。 Precipitation removal using silver halide is known as a method of removing silver, but it is not possible to completely remove it due to its solubility even though the amount is very small. For example, in Patent Document 3, since silver chloride has a solubility of about 75 mg/L, silver extraction from a dilute solution of about 100 mg/L is performed by solvent extraction using TBP (tributyl phosphate) which is a phosphoric acid-based extractant. Are trying. However, the precipitation method cannot be applied to this purpose due to the above reasons.
特許文献３に示す溶媒抽出法であるが、この方法を本目的のために適用しようとした場合、別途溶媒抽出工程が必要になる。 Although the solvent extraction method shown in Patent Document 3 is applied for this purpose, a separate solvent extraction step is required.
さらに、溶媒抽出操作を行った場合、水相中には微細な有機相の液滴が微量残るエントレイメントと呼ばれる状態が生じるため、このエントレイメントを除去するために例えば活性炭吸着装置などが必要になる。特に、酸化銅鉱石を対象とした硫酸で銅を浸出し溶媒抽出（ＳＸ）と電解採取（ＥＷ）を組み合わせたＳＸ−ＥＷプロセスでは、このエントレイメントが原因でカソード表面を暗褐色に変化させる「オーガニックバーン」と呼ばれる現象が知られており、カソードの品質が悪化する原因になることが知られている。 Furthermore, when a solvent extraction operation is carried out, a state called entrainment in which a small amount of fine organic phase droplets remain in the aqueous phase occurs, so in order to remove this entrainment, for example, an activated carbon adsorption device or the like is used. You will need it. In particular, in the SX-EW process in which copper is leached with sulfuric acid for copper oxide ore and solvent extraction (SX) and electrowinning (EW) are combined, the cathode surface turns dark brown due to this entrainment. A phenomenon called "organic burn" is known and is known to cause deterioration of the quality of the cathode.
溶媒抽出工程やエントレイメントの除去装置などにかかるコストがかかることや、品質悪化の恐れがあることから、本目的のために溶媒抽出法を適用することは難しい。以上の経緯からより簡便で効率的なビスマス電解液からの銀の除去方法が求められてきた。 It is difficult to apply the solvent extraction method for this purpose because of the high cost of the solvent extraction step and the entrainment removal device and the risk of quality deterioration. From the above background, a simpler and more efficient method for removing silver from a bismuth electrolytic solution has been demanded.
本発明は、上記事情に鑑み、銀を不純物として多く含む電解液から銀を除去して高品位な金属ビスマスを得る方法を提供することを目的とする。 In view of the above circumstances, it is an object of the present invention to provide a method for removing silver from an electrolytic solution containing a large amount of silver as an impurity to obtain high-quality metal bismuth.
第１発明のビスマス電解液の不純物除去方法は、ビスマスと銀を含有するケイフッ酸性溶液からなるビスマス電解液に、銀より電位的に卑な金属を添加し、還元雰囲気下で混合撹拌することを特徴とする。
第２発明のビスマス電解液の不純物除去方法は、第１発明において、前記卑な金属が、ビスマス金属であることを特徴とする。
第３発明のビスマス電解液の不純物除去方法は、第１、または第２発明において、前記還元雰囲気が、銀塩化銀電極を参照電極とする値で、５１８ｍＶ以下の酸化還元電位に制御したものであることを特徴とする。
第４発明のビスマス電解液の不純物除去方法は、第３発明において、前記還元雰囲気が、銀塩化銀電極を参照電極とする値で、４００ｍＶ以上の酸化還元電位に制御したものであることを特徴とする。
The method for removing impurities from a bismuth electrolyte solution according to the first aspect of the present invention comprises adding a metal, which is a base potential less than silver, to a bismuth electrolyte solution containing a bismuth acid solution containing bismuth and silver, and mixing and stirring the mixture in a reducing atmosphere. Characterize.
A method for removing impurities from a bismuth electrolyte solution according to a second aspect of the invention is characterized in that, in the first aspect, the base metal is bismuth metal.
A method for removing impurities from a bismuth electrolyte solution according to a third aspect of the present invention is the method according to the first or second aspect, wherein the reducing atmosphere is controlled to a redox potential of 518 mV or less with a value using a silver-silver chloride electrode as a reference electrode. It is characterized by being.
A method for removing impurities from a bismuth electrolyte solution according to a fourth aspect of the present invention is characterized in that, in the third aspect, the reducing atmosphere is controlled to a redox potential of 400 mV or more with a value using a silver-silver chloride electrode as a reference electrode. And
第１発明によれば、不純物である銀よりも卑な金属を添加すると、添加した金属と電解液中に溶解している銀イオンとの酸化還元を利用したセメンテーション反応により、不純物である銀をメタルに還元析出させて電解液中から除去することができる。このため、純度の高い金属ビスマスを得ることができる。
第２発明によれば、酸化還元電位が５１８ｍＶの上限値以下であると銀を析出をさせ電解液から除去することができる。
第３発明によれば、添加する金属の比表面積を小さくする等の手間とコストをかけずに銀を析出させ電解液から除去することができる。
According to the first aspect of the present invention, when a metal that is less noble than silver that is an impurity is added, a cementation reaction utilizing redox between the added metal and silver ions dissolved in the electrolytic solution causes a silver that is an impurity. Can be reduced and precipitated on the metal to be removed from the electrolytic solution. Therefore, highly pure metal bismuth can be obtained.
According to the second invention, when the oxidation-reduction potential is not more than the upper limit value of 518 mV, silver can be precipitated and removed from the electrolytic solution.
According to the third invention, silver can be deposited and removed from the electrolytic solution without labor and cost such as reducing the specific surface area of the added metal.
まず、本発明の不純物除去方法が適用される代表的な前工程として湿式法を用いたビスマス精製方法を説明する。
上記ビスマス精製方法は、銅と貴金属とビスマスと不純物とを含有する鉱物を製錬して得た粗銅を電解精製に付して銅を回収し、次に電解精製を行うことで生成した電解スライムから湿式法により貴金属を回収する工程であって、貴金属の回収後に生成した酸性溶液を以下の工程に付すことを特徴とする。
First, a bismuth refining method using a wet method will be described as a typical preceding step to which the impurity removing method of the present invention is applied.
The above-mentioned bismuth refining method, electrolytic copper is subjected to electrolytic refining of crude copper obtained by smelting a mineral containing copper, a noble metal, bismuth and impurities to recover copper, and then electrolytic slime produced by performing electrolytic refining. Is a step of recovering the noble metal by a wet method, wherein the acidic solution produced after the recovery of the noble metal is subjected to the following steps.
図３はビスマス精製の各工程を示しており、図４は図３に示す各工程で得られる生成物の説明図である。下記符号１）〜６）は図中のものと一致している。
１）中和処理工程
貴金属の回収後に生成した前記酸性溶液にアルカリを添加してｐＨを２．０以上３．０以下の範囲に調整し、次いで固液分離して中和濾液と中和澱物を得る。
２）アルカリ浸出工程
前記中和処理工程で得た中和澱物にアルカリを添加してアルカリ浸出液とアルカリ浸出残渣に分離する。
３）硫酸浸出工程
前記アルカリ浸出工程で得たアルカリ浸出残渣に硫酸を添加して硫酸浸出液と硫酸浸出残渣とに分離する。
４）冷却工程
前記硫酸浸出工程で得た硫酸浸出液を冷却し、硫酸ビスマスの結晶を得る。
５）ビスマス酸化工程
前記冷却工程で得た硫酸ビスマスの結晶にアルカリを加え、酸化ビスマスを得る。
６）電解工程
前記ビスマス酸化工程で得た酸化ビスマスに酸溶液を添加して溶解し、得た溶解液を電解採取して金属ビスマスを得る。
FIG. 3 shows each step of bismuth purification, and FIG. 4 is an explanatory view of the product obtained in each step shown in FIG. The following symbols 1) to 6) correspond to those in the figure.
1) Neutralization treatment step An alkali is added to the acidic solution produced after the recovery of the noble metal to adjust the pH to a range of 2.0 or more and 3.0 or less, and then solid-liquid separation is performed to perform neutralization filtrate and neutralization precipitate Get things.
2) Alkali leaching step Alkali is added to the neutralized precipitate obtained in the neutralization treatment step to separate into an alkali leaching solution and an alkali leaching residue.
3) Sulfuric acid leaching step Sulfuric acid is added to the alkali leaching residue obtained in the alkali leaching step to separate into a sulfuric acid leaching solution and a sulfuric acid leaching residue.
4) Cooling step The sulfuric acid leaching solution obtained in the sulfuric acid leaching step is cooled to obtain bismuth sulfate crystals.
5) Bismuth oxidation step Alkali is added to the crystals of bismuth sulfate obtained in the cooling step to obtain bismuth oxide.
6) Electrolysis step An acid solution is added to the bismuth oxide obtained in the bismuth oxidation step and dissolved, and the obtained solution is electrowinned to obtain metal bismuth.
本発明は上記電解工程６）で得た電解液を処理対象とする。以下詳細に説明する。 The present invention treats the electrolytic solution obtained in the above electrolysis step 6) as a treatment target. The details will be described below.
（本発明に係る処理対象液）
上記電解工程６）では、前記ビスマス酸化工程５）で得た酸化ビスマスに酸溶液を添加して溶解する。このように酸溶液を加えると、ビスマスがイオンとして溶解する。そして、得た溶解液を電解採取すると、つまり溶解液に電極を入れて通電するとビスマスイオンが電子を受けてカソード上に単体の金属ビスマスとして電析する。
この工程における電解に用いる酸溶液は、ビスマスと共に銀などの不純物を含んでいる。これが、本発明の処理対象液である。
(Liquid to be treated according to the present invention)
In the electrolysis step 6), an acid solution is added and dissolved in the bismuth oxide obtained in the bismuth oxidation step 5). When the acid solution is added in this way, bismuth dissolves as ions. When the obtained solution is electrowinned, that is, when an electrode is placed in the solution and electricity is applied, bismuth ions receive electrons and are electrodeposited as a single metal bismuth on the cathode.
The acid solution used for electrolysis in this step contains impurities such as silver together with bismuth. This is the liquid to be treated of the present invention.
電解に用いる酸溶液には、ビスマスの溶解度が十分に高く電解に好都合なビスマス濃度が確保でき、しかも共存する銀などの不純物との分離性が高いことからケイフッ酸溶液が好ましい。ケイフッ酸を含有する溶液を用いた電解浴とすることで、ケイフッ化ビスマスの形で存在する電解液中から不純物たる銀を充分に分離した金属ビスマスを得ることができる。 The acid solution used for electrolysis is preferably a silicofluoric acid solution because the solubility of bismuth is sufficiently high, the bismuth concentration convenient for electrolysis can be ensured, and the coexistence with impurities such as silver is high. By using an electrolytic bath that uses a solution containing silicofluoric acid, it is possible to obtain metal bismuth in which silver, which is an impurity, is sufficiently separated from the electrolytic solution that is present in the form of bismuth silicofluoride.
（添加金属）
電解液に添加する金属は不純物として回収したい銀よりも卑な金属である。銀よりも卑な金属としては、ビスマスよりも電気化学的に卑な金属かビスマスそのものを用いることができる。銀よりも卑であっても、ビスマスより貴な金属はビスマスよりも優先的に析出して品位を低下するため、用いることはできない。ビスマス金属をセメンテーション反応に用いた場合は、電析させるビスマス金属の品位に影響を及ぼさないため、ビスマス金属を添加するのが好ましい。
(Additional metal)
The metal added to the electrolytic solution is a metal that is baser than silver that is desired to be recovered as an impurity. As a metal that is baser than silver, a metal that is electrochemically baser than bismuth or bismuth itself can be used. A metal that is more noble than bismuth, even if it is less noble than silver, preferentially deposits more than bismuth and degrades its quality, so it cannot be used. When bismuth metal is used for the cementation reaction, it does not affect the quality of the bismuth metal to be electrodeposited, so it is preferable to add bismuth metal.
電解始液にビスマス金属を添加し、浸漬させて電解始液に含有された銀イオンをビスマス金属上に析出させるセメンテーション反応に付し、さらにその液を電解に付すとビスマス金属中の銀品位を低減することができる。 When bismuth metal is added to the electrolysis starter solution and immersed, it is subjected to a cementation reaction to deposit the silver ions contained in the electrolysis starter solution on the bismuth metal, and when the solution is subjected to electrolysis, the silver grade in the bismuth metal Can be reduced.
添加する金属の形状は特に制限はないが、セメンテーションの反応性を上げるためには板やインゴット状のものよりも、比表面積が大きい粒状や粉末状のものが好ましい。 The shape of the metal to be added is not particularly limited, but in order to increase the reactivity of cementation, a granular or powdery one having a large specific surface area is preferable to a plate or ingot-shaped one.
（還元雰囲気）
セメンテーション反応を用いて不純物である銀を除去するには、還元雰囲気にすることが必要である。この目的のためにも添加する金属の形状は比表面積の大きい粒状や粉末状のものが好ましい。還元剤を別途添加する方法も考えられるが、工程が複雑になり、コストの増加を招く恐れがあることから、本発明ではセメンテーション反応において添加する金属によって還元雰囲気にしている。
(Reducing atmosphere)
In order to remove the impurity silver by using the cementation reaction, it is necessary to use a reducing atmosphere. Also for this purpose, the shape of the added metal is preferably granular or powdery having a large specific surface area. Although a method of separately adding a reducing agent is also conceivable, the process is complicated and there is a risk of increasing the cost. Therefore, in the present invention, the reducing atmosphere is set by the metal added in the cementation reaction.
還元雰囲気を定量的に把握するには、酸化還元電位（ＯＲＰ）の値を市販のＯＲＰメーターを用いて確認する方法が最も簡単である。ここでいうＯＲＰ値は、混合撹拌後、平衡に達したときの値（ＯＲＰメーター指示値）である。 The easiest way to quantitatively grasp the reducing atmosphere is to check the value of the redox potential (ORP) using a commercially available ORP meter. The ORP value here is a value when the equilibrium is reached after mixing and stirring (ORP meter indicated value).
ＯＲＰ値と銀の除去効率は相関があるので、図２に示すように、銀塩化銀電極を参照電極とする値で５１８ｍＶ以下の電位に低減するように、ビスマス金属等の銀よりも卑な金属を添加すればよい。ＯＲＰ値がこの上限値を超えると、銀が析出できなくなり好ましくない。 Since there is a correlation between the ORP value and the removal efficiency of silver, as shown in FIG. 2, it is lower than silver such as bismuth metal so as to reduce the potential to 518 mV or less at the value using the silver-silver chloride electrode as a reference electrode. A metal may be added. If the ORP value exceeds this upper limit, silver cannot be deposited, which is not preferable.
また、銀塩化銀電極を参照電極とする値で４００ｍＶより下廻っても、セメンテーション反応を生じさせることができるが、その場合は、添加する金属の比表面積をより小さくしたり（微粉化したり）、余剰に添加する必要がある。このように、手間のコストを考慮しなければ、１０ｍＶの還元雰囲気まで利用可能である。 Further, the cementation reaction can occur even when the value using the silver-silver chloride electrode as the reference electrode is lower than 400 mV, but in that case, the specific surface area of the added metal can be made smaller (pulverized). , It is necessary to add in excess. As described above, even if a labor cost is not considered, a reducing atmosphere of 10 mV can be used.
ただし、手間とコストを省き現実的・工業的に採用可能な範囲を求めるなら、酸化還元電位を、４００〜５１８ｍＶとの間とすると手間とコストをかけず、銀を電解液から十分に除去することが可能になるので、好ましい。 However, in order to save labor and cost and to find a practically industrially applicable range, setting the oxidation-reduction potential between 400 and 518 mV eliminates labor and cost, and removes silver from the electrolytic solution sufficiently. It is possible because it is possible.
図２は、本発明において採用できる酸化還元電位を示しており、符号Ｄ１で示す範囲が下限値１０ｍＶから上限値５１８ｍＶまでの使用可能範囲である。そして、符号Ｄ２で示す４００ｍＶから５１８ｍＶの範囲が好適範囲である。 FIG. 2 shows the oxidation-reduction potential that can be adopted in the present invention, and the range indicated by the symbol D1 is the usable range from the lower limit value 10 mV to the upper limit value 518 mV. Then, the range of 400 mV to 518 mV indicated by reference sign D2 is a preferable range.
反応温度は特に制限なく、常温で行うことが可能である。反応時は撹拌混合する必要があるが、強撹拌では空気を巻き込み、酸化雰囲気になるため、空気を巻き込まない程度に撹拌することが好ましい。 The reaction temperature is not particularly limited, and it can be carried out at room temperature. It is necessary to stir and mix at the time of reaction, but since strong stirring entrains air and creates an oxidizing atmosphere, it is preferable to stir to such an extent that air is not entrained.
（金属ビスマスの電解）
金属ビスマスを得るには電解を行う。その電解条件としては、以下を例示できる。すなわち、ケイフッ酸濃度が３００〜３５０ｇ／ｌの溶液を用いて酸化ビスマスを溶解し、ビスマス濃度が８０〜１００ｇ／ｌの電解始液を得、この電解始液をカソードにハステロイ、アノードにカーボンを用いた電解槽に供給し、液温を４０〜５０℃、好ましくは５０℃以下、に維持しつつ、８０〜１２０Ａ／ｍ２のカソード電流密度で通電することで、カソード上に金属ビスマスを電析させることができる。
電流密度が２００Ａ／ｍ２を超えると電着表面の状態が荒れて粒上析出物が生じやすく電解液が巻き込まれるなど好ましくない。
(Electrolysis of metal bismuth)
Electrolysis is performed to obtain metal bismuth. Examples of the electrolysis conditions are as follows. That is, bismuth oxide is dissolved using a solution having a hydrofluoric acid concentration of 300 to 350 g/l to obtain an electrolytic starter solution having a bismuth concentration of 80 to 100 g/l. This electrolytic starter solution has Hastelloy as a cathode and carbon as an anode. The metal bismuth is supplied onto the cathode by supplying electricity to the used electrolytic cell and energizing at a cathode current density of 80 to 120 A/m 2 while maintaining the liquid temperature at 40 to 50° C., preferably 50° C. or less. Can be deposited.
If the current density exceeds 200 A/m 2 , the condition of the electrodeposited surface becomes rough and precipitates on the grains are apt to be generated, and the electrolytic solution is entrained, which is not preferable.
電解の終了は、例えば電解液中のビスマス濃度が２０〜３０g／ｌ程度まで低下した時点とすれば、析出するビスマスの表面状態の悪化を抑止でき、電解液の巻き込みなどの影響のない表面平滑な金属ビスマスを得ることができて好ましい。
また、電解終了後はカソードを引き上げて電着したビスマスを剥ぎ取り、水で洗浄し、ついで炉の中に入れて不活性雰囲気下でビスマスの融点（２７１℃）を若干上回る３００℃くらいの温度で熔解することで、不純物や酸化物を取り除き、インゴット等の形状の金属ビスマスを得ることができる。
At the end of electrolysis, for example, when the bismuth concentration in the electrolytic solution is reduced to about 20 to 30 g/l, the deterioration of the surface state of the precipitated bismuth can be suppressed, and the surface smoothness without the influence of the entrainment of the electrolytic solution can be suppressed. It is preferable because a good metal bismuth can be obtained.
After completion of electrolysis, the cathode is pulled up to remove the electrodeposited bismuth, washed with water, and then placed in a furnace, and the temperature is about 300°C which is slightly higher than the melting point (271°C) of bismuth in an inert atmosphere. By melting with, impurities and oxides can be removed, and metal bismuth in the shape of an ingot or the like can be obtained.
以下に実施例と比較例を示す。
＜実施例１＞
ケイフッ酸濃度が３３６ｇ／Ｌ、ビスマス濃度が５０ｇ／Ｌ、銀濃度が０．０９ｇ／Ｌ、ＯＲＰが６１１ｍＶのビスマス電解液に粉末状の銀より電位的に卑な金属である金属ビスマスを１．０ｇ添加し、１時間程度混合撹拌した。混合撹拌後の電解液のＯＲＰは７４ｍＶ、電解液中の銀濃度は０．１ｍｇ／Ｌ未満だった。つまり、９９．９％以上の銀を析出させて除去することができた。
Examples and comparative examples are shown below.
<Example 1>
1. A bismuth electrolyte solution having a silicic hydrofluoric acid concentration of 336 g/L, a bismuth concentration of 50 g/L, a silver concentration of 0.09 g/L, and an ORP of 611 mV was provided with 1. 0 g was added and mixed and stirred for about 1 hour. The ORP of the electrolytic solution after mixing and stirring was 74 mV, and the silver concentration in the electrolytic solution was less than 0.1 mg/L. That is, 99.9% or more of silver could be deposited and removed.
＜実施例２＞
ケイフッ酸濃度が３３６ｇ／Ｌ、ビスマス濃度が５０ｇ／Ｌ、銀濃度が０．０９ｇ／Ｌ、ＯＲＰが６１１ｍＶのビスマス電解液に、粉末状の金属ビスマスを０．７５ｇ添加し、１時間程度混合撹拌した。混合撹拌後の電解液のＯＲＰは２７１ｍＶ、電解液中の銀濃度は０．１ｍｇ／Ｌ未満であった。つまり、９９．９％以上の銀を析出させて除去することができた。
<Example 2>
0.75 g of powdered metal bismuth was added to a bismuth electrolyte solution having a hydrofluoric acid concentration of 336 g/L, a bismuth concentration of 50 g/L, a silver concentration of 0.09 g/L, and an ORP of 611 mV, and mixed and stirred for about 1 hour. did. The ORP of the electrolytic solution after mixing and stirring was 271 mV, and the silver concentration in the electrolytic solution was less than 0.1 mg/L. That is, 99.9% or more of silver could be deposited and removed.
＜実施例３＞
ケイフッ酸濃度が３３６ｇ／Ｌ、ビスマス濃度が５０ｇ／Ｌ、銀濃度が０．０９ｇ／Ｌ、ＯＲＰが６１１ｍＶのビスマス電解液に粉末状の金属ビスマスを０．２５ｇ添加し、１時間程度混合撹拌した。混合撹拌後の電解液のＯＲＰは４２０ｍＶ、電解液中の銀濃度は０．１ｍｇ／Ｌ未満であった。つまり、９９．９％以上の銀を析出させて除去することができた。
<Example 3>
0.25 g of powdered metal bismuth was added to a bismuth electrolyte solution having a silicofluoric acid concentration of 336 g/L, a bismuth concentration of 50 g/L, a silver concentration of 0.09 g/L, and an ORP of 611 mV, and mixed and stirred for about 1 hour. .. The ORP of the electrolytic solution after mixing and stirring was 420 mV, and the silver concentration in the electrolytic solution was less than 0.1 mg/L. That is, 99.9% or more of silver could be deposited and removed.
＜実施例４＞
ケイフッ酸濃度が３３６ｇ／Ｌ、ビスマス濃度が５０ｇ／Ｌ、銀濃度が０．０９ｇ／Ｌ、ＯＲＰが６１１ｍＶのビスマス電解液に粉末状の金属ビスマスを０．１ｇ添加し、１時間程度混合撹拌した。混合撹拌後の電解液のＯＲＰは４５３ｍＶ、電解液中の銀濃度は０．１ｍｇ／Ｌ未満であった。つまり、９９．９％以上の銀を析出させて除去することができた。
<Example 4>
0.1 g of powdered metal bismuth was added to a bismuth electrolyte solution having a silicofluoric acid concentration of 336 g/L, a bismuth concentration of 50 g/L, a silver concentration of 0.09 g/L, and an ORP of 611 mV, and mixed and stirred for about 1 hour. .. The ORP of the electrolytic solution after mixing and stirring was 453 mV, and the silver concentration in the electrolytic solution was less than 0.1 mg/L. That is, 99.9% or more of silver could be deposited and removed.
＜実施例５＞
ケイフッ酸濃度が３３６ｇ／Ｌ、ビスマス濃度が５０ｇ／Ｌ、銀濃度が０．０９ｇ／Ｌ、ＯＲＰが６１１ｍＶのビスマス電解液に粒状のビスマスショットを１０ｇ添加し、１時間程度混合撹拌した。混合撹拌後の電解液のＯＲＰは５１８ｍＶ、電解液中の銀濃度は１．２ｍｇ／Ｌだった。つまり、９８．７％以上の銀を析出させて除去することができた。
<Example 5>
10 g of granular bismuth shot was added to a bismuth electrolyte solution having a silicofluoric acid concentration of 336 g/L, a bismuth concentration of 50 g/L, a silver concentration of 0.09 g/L, and an ORP of 611 mV, and mixed and stirred for about 1 hour. The ORP of the electrolytic solution after mixing and stirring was 518 mV, and the silver concentration in the electrolytic solution was 1.2 mg/L. That is, 98.7% or more of silver could be deposited and removed.
＜比較例１＞
ケイフッ酸濃度が３３６ｇ／Ｌ、ビスマス濃度が５０ｇ／Ｌ、銀濃度が０．０９ｇ／Ｌ、ＯＲＰが６１１ｍＶのビスマス電解液に粒状のビスマスショットを５ｇ添加し、１時間程度混合撹拌した。混合撹拌後の電解液のＯＲＰは５３０ｍＶまでしか低下せず、電解液中の銀濃度は２．８ｍｇ／Ｌと残留した。酸化雰囲気のため銀が十分に析出できなくなったことを意味する。
<Comparative Example 1>
5 g of granular bismuth shot was added to a bismuth electrolyte solution having a silicofluoric acid concentration of 336 g/L, a bismuth concentration of 50 g/L, a silver concentration of 0.09 g/L, and an ORP of 611 mV, and mixed and stirred for about 1 hour. The ORP of the electrolytic solution after mixing and stirring dropped only to 530 mV, and the silver concentration in the electrolytic solution remained at 2.8 mg/L. This means that silver could not be sufficiently deposited due to the oxidizing atmosphere.
＜比較例２＞
ケイフッ酸濃度が３３６ｇ／Ｌ、ビスマス濃度が５０ｇ／Ｌ、銀濃度が０．０９ｇ／Ｌ、ＯＲＰが６１１ｍＶのビスマス電解液に粒状のビスマスショットを２．５ｇ添加し、１時間程度混合撹拌した。混合撹拌後の電解液のＯＲＰは５４０ｍＶまでしか低減せず、電解液中の銀濃度は１３ｍｇ／Ｌも残留した。酸化雰囲気のため銀が十分に析出できなくなったことを意味する。
<Comparative example 2>
2.5 g of granular bismuth shot was added to a bismuth electrolyte solution having a silicofluoric acid concentration of 336 g/L, a bismuth concentration of 50 g/L, a silver concentration of 0.09 g/L, and an ORP of 611 mV, and mixed and stirred for about 1 hour. The ORP of the electrolytic solution after mixing and stirring was reduced only to 540 mV, and the silver concentration in the electrolytic solution remained as high as 13 mg/L. This means that silver could not be sufficiently deposited due to the oxidizing atmosphere.
上記実施例１〜５および比較例１，２のデータを表１に示す。また、表１のデータを図２に示す。
上記のように、セメンテーション反応時の電解液のＯＲＰを４００〜５１８ｍＶの範囲あるいはそれ以下の酸化還元電位に制御すればビスマス電解液中の銀濃度を２ｍｇ／ｌ以下に抑制できる。 As described above, the silver concentration in the bismuth electrolytic solution can be suppressed to 2 mg/l or less by controlling the ORP of the electrolytic solution during the cementation reaction to a redox potential in the range of 400 to 518 mV or lower.
電解終液中のビスマス濃度を３０ｇ／Ｌとして金属ビスマスを電解採取した場合、本発明を用いなければ、得られる金属ビスマスの品位は９９％（２Ｎ）グレードにとどまるが、本発明を用いることで金属ビスマスの品位は９９．９９％（４Ｎ）のグレードが得られる。 When metal bismuth is electrowinned with the bismuth concentration in the electrolysis final solution being 30 g/L, the quality of the obtained metal bismuth is 99% (2N) grade unless the present invention is used. The grade of metal bismuth is 99.99% (4N).
本発明は、銅電解精製工程で発生する銅電解スライムから有価金属であるビスマスを回収する精製工程の中間生成物であるビスマス電解液から不純物を除去するのに好適であるが、これに限られず、銀を不純物として多く含む電解液から銀を除去する目的であれば、あらゆる分野から発生した電解液に対し本発明を適用することができる。 The present invention is suitable for removing impurities from the bismuth electrolytic solution, which is an intermediate product of the refining step of recovering bismuth, which is a valuable metal, from the copper electrolytic slime generated in the copper electrorefining step, but is not limited thereto. For the purpose of removing silver from an electrolytic solution containing a large amount of silver as an impurity, the present invention can be applied to electrolytic solutions generated from all fields.
Ｄ１ 使用可能な酸化還元電位
Ｄ２ 好適な酸化還元電位
D1 Available redox potential D2 Suitable redox potential
Claims (4)
還元雰囲気下で混合撹拌する
ことを特徴とするビスマス電解液の不純物除去方法。 To a bismuth electrolytic solution consisting of a fluorinated acidic solution containing bismuth and silver, a metal that is more base than silver is added,
A method for removing impurities from a bismuth electrolyte, which comprises mixing and stirring in a reducing atmosphere.
ことを特徴とする請求項１記載のビスマス電解液の不純物除去方法。 The method for removing impurities from a bismuth electrolyte according to claim 1, wherein the base metal is bismuth metal.
ことを特徴とする請求項１または２記載のビスマス電解液の不純物除去方法。 The method for removing impurities from a bismuth electrolyte solution according to claim 1 or 2, wherein the reducing atmosphere is controlled to a redox potential of 518 mV or less with a value using a silver-silver chloride electrode as a reference electrode.
ことを特徴とする請求項３記載のビスマス電解液の不純物除去方法。 4. The method for removing impurities from a bismuth electrolyte solution according to claim 3, wherein the reducing atmosphere has a value using a silver-silver chloride electrode as a reference electrode and is controlled to a redox potential of 10 mV or higher.
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