JP3834143B2

JP3834143B2 - Method and apparatus for electrolytic purification of gold

Info

Publication number: JP3834143B2
Application number: JP02566398A
Authority: JP
Inventors: 昇宮下
Original assignee: Dowa Holdings Co Ltd; Dowa Mining Co Ltd
Current assignee: Dowa Holdings Co Ltd
Priority date: 1998-02-06
Filing date: 1998-02-06
Publication date: 2006-10-18
Anticipated expiration: 2018-02-06
Also published as: JPH11222693A

Description

【０００１】
【発明の属する技術分野】
本発明は金の電解精製方法及び金の電解精製装置に係り、特に、金の電解精製の際に電解液に接している装置や配管などの設備表面に電解析出によらないで付着する、いわゆるプレーティング（化学大辞典８巻、７３ページ、共立出版参照）の低減を図った金の電解精製方法及びその装置に関する。
【０００２】
【従来の技術】
金の電解精製は、銀電解製錬の際の陽極泥を処理して得た粗金を板に鋳造して陽極とし、電解液は塩化金酸液を用いて陰極板上に純金を得る方法であり、いわゆるウォールウィル法（化学大辞典２巻、９２６ページ、共立出版参照）に基づいた電解条件で行われている。
【０００３】
図２に示す金の電解精製装置により、従来の金の電解精製方法を述べる。電解槽１には塩化金酸液からなる電解液２が入っており、純チタン製の陰極３と濾布５で包んだ粗金からなる陽極４とが電解槽１内に懸垂されている。粗金の陽極４には交直電源６が接続されており、電解液２中に不純物を含む金を溶解させ、陰極３に金を析出させる。
【０００４】
電解槽１の電解液２は、配管１０より一部抜き出されて循環槽（タンク）７に入る。循環槽７内の電解液２は、ヒーター９によって加熱される。ヒー夕ー９は温度計８によって制御され、循環槽７の電解液２は一定の温度に保持される。循環槽７の一定温度の電解液２は、配管１１のポンプ１２で抜き出され、電解槽１に戻される。
【０００５】
また、電解中、プレーティングによって電解液２中の金濃度が減少するので、適宜電解液組成を確認し、新たに塩化金酸液を加える。このようにして、陰極３に電解析出した金は、溶解して鋳型に鋳造され精製金として販売される。
【０００６】
【発明が解決しようとする課題】
ところが、上記従来の金の電解精製方法にあっては、電解槽１、循環槽７、配管１０、１１などの電解液２に接する電解設備表面に、プレーティングによって付着する金の付着量が多かった。付着した金は除去しなければならないが、除去作業の間、通電を停止しなければならず、電解設備の稼働率が低かった。
【０００７】
また、通常、粗金陽極中の不純物は電解液中に蓄積されて製品の純度を下げることになるため、連続的に除去するための浄液工程（浄液設備）が必要である。浄液設備がない場合、微量の不純物が電解析出する金と共析し製品の品質が安定しない。しかし、プレーティング現象に対処できる浄液設備となると、設備額やランニングコストが高くなってしまう。
【０００８】
また、電解液２には塩酸を使用しており、遊離塩酸濃度が１００ｇ／リットルと高く、更に、電解液２の温度が６０℃と高温のため、塩酸ミストが発生する状況にあった。このため、電解設備周辺で塩酸臭があり、腐食や作業環境上の充分な対処が必要であった。
【０００９】
本発明は上記従来技術の問題点を解消すべくなされたものであり、プレーティングを低減することができ、電解精製の稼働率を向上できると共に浄液設備を簡素化でき、また、作業環境を改善することができる金の電解精製方法及びその装置を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記の目的を達成するために、本発明に係る金の電解精製方法は、粗金を陽極として電解液中に金を溶解させ、陰極に高純度の金を析出させる金の電解精製方法であって、前記電解液に酸化剤が添加されているものである。
【００１１】
本発明者は、プレーティング現象に対処するため、種々検討したところ以下のことが判明した。即ち、電解中では原料である粗金の陽極から金が溶解する際、ＡｕＣｌ₄ ^-、ＡｕＣｌ₂ ^-の２種類の形態で電解液に溶出する。このうちＡｕＣｌ₂ ^- は下記の平衡反応式
３ＡｕＣｌ₂ ^-⇔２Ａｕ＋ＡｕＣｌ₄ ^-＋２Ｃｌ^-
の右向きの反応（不均化反応）によりＡｕが析出し、プレーティングが起きるものと推定される。上記化学式によれば、右向きの反応を抑えることにより、プレーティングの防止が可能となる。
【００１２】
そこで、本発明者は、プレーティングを抑制するため、電解液温度を下げ、電解液に種々の薬液を添加し電解を行った。その結果、過酸化水素水等の酸化剤が有効であることが判明した。すなわち、電解液の酸化還元電位は、薬液（酸化剤）を添加しない従来の塩化金酸液では５００ｍＶであり、過酸化水素水等の酸化剤を加えることにより電解液の酸化還元電位があがり、上記化学式のＡｕＣｌ₂ ^-の分解反応が抑制されることがわかった。つまり、電解液に酸化剤を添加することにより、最適な酸化還元電位を選択することで、上記化学式の反応を抑制でき、プレーティングによる電解液接触面への金付着量が大幅に減少する。
【００１３】
上記発明において、酸化剤としては、過酸化水素水、次亜塩素酸塩、次亜塩素酸、塩素ガスから選ばれる１種以上のものが好ましい。これらのうち、１種だけで用いた場合、過酸化水素水が最も効果があったが、１種以上を組み合わせて用いるようにしてもよい。
【００１４】
また、上記発明において、電解液の温度は、２０℃〜５５℃に保持するのが好ましく、より好ましくは、３５℃〜４５℃に保持するのがよい。
【００１５】
電解液の温度を２０℃以上としたのは、２０℃以下では電解効率が低くなってしまい、また、電解液の温度を５５℃以下としたのは、電解効率からいえば高いほうがよいが、過酸化水素水等の酸化剤の自己分解が起こらず、かつ塩酸のミストが多量に発生しないようにするためである。
【００１６】
また、電解液の温度を、電解槽に電解液を循環供給する循環槽側の、温度が調節された電解液の循環供給によって保持するようにすると、複数の電解槽で電解精製を行った場合にも、電解槽ごとの電解液の温度のバラツキを抑えることができる。
【００１７】
また、上記発明において、酸化剤の添加により、電解液の酸化還元電位を１０００ｍＶ〜１４００ｍＶに保持するのが好ましく、より好ましくは、１１００ｍＶ〜１３００ｍＶに保持するのがよい。
【００１８】
電解液の酸化還元電位を１０００ｍＶ以上としたのは、１０００ｍＶ以上では、Ａｕが、Ａｕ⁰よりもＡｕ⁺の状態が安定となり、プレーティングを抑制できるからである。
また、電解液の酸化還元電位を１４００ｍＶ以下としたのは、酸化剤の安定性を保持するためである。（酸化還元電位が８００ｍＶ〜１７００ｍＶであれば、Ｈ₂０₂等は酸化剤としての作用を呈するが、１４００ｍＶを越えると、例えば、Ｈ₂０₂ではＨ₂ガスの発生が起こるなど、酸化剤の安定性が低下する。）
【００１９】
電解液の酸化還元電位を、電解槽に電解液を循環供給する循環槽側の、酸化剤の添加により酸化還元電位が調節された電解液の循環供給によって保持するようにすると、複数の電解槽で電解精製を行った場合にも、電解槽ごとの電解液の酸化還元電位のバラツキを抑えることができる。
【００２０】
また、本発明に係る金の電解精製装置は、粗金を陽極として電解液中に金を溶解させ、陰極に高純度の金を析出させる金の電解精製装置であって、前記電解液の酸化還元電位を所定範囲に保持するために、電解液に添加される酸化剤の供給量を制御する制御手段を備えたものである。
【００２１】
【発明の実施の形態】
以下に、本発明の実施の形態を図面を用いて説明する。図１は本発明の金の電解精製装置の一実施形態を示す概略構成図である。
【００２２】
図１において１は電解槽であり、電解槽１には塩化金酸液に酸化剤を添加した電解液２が入っている。また、電解槽１には純チタン製の陰極３と、濾布５で包んだ粗金からなる陽極４とが懸垂されている。粗金の陽極４には交直電源６が接続されており、電解液２中に不純物を含む金を溶解させ、陰極３に金を析出させるようになっている。
【００２３】
電解槽１には、所定の温度・酸化還元電位に調節された電解液２を電解槽１に循環供給するための循環槽（タンク）７が隣接して設けられている。循環槽７の容量は１５０リットル、材質はポリプロピレンからなる。電解槽１の電解液２は、配管１０より一部抜き出されて循環槽７に入るが、配管１０には、電解液２中に存在する不純物を除去するための浄液設備１７が設けられている。
【００２４】
循環槽７の電解液２の温度が所定範囲に保たれるように、電解液２の温度を温度計８で計測し、その計測値に基づいて制御装置１６がヒーター９の加熱制御を行うようになっている。電解液２の温度は、上限を５５℃、下限を２０℃とする。電解効率からいえば高いほうがよいが、酸化剤としての過酸化水素水の自己分解が起こらない温度でかつ塩酸のミストが多量に発生しない温度とするためである。
【００２５】
また、循環槽７には酸化剤供給系１４から酸化剤として過酸化水素水（Ｈ₂Ｏ₂）が適宜供給され、循環槽７の電解液２の酸化還元電位が所定範囲に保持される。循環槽７には電位計１３が設けられ、その測定信号によって制御装置１６が、酸化剤供給系１４のバルブ１５の開閉ないし開度を制御し、あるいは、酸化剤供給系１４のポンプ（図示せず）を駆動制御する構成となっている。電解液２の電位は、１０００ｍＶから１４００ｍＶの範囲で制御する。好ましくは１１００ｍＶから１３００ｍＶの範囲が良く、通常１２００ｍＶで行う。過酸化水素水としては、工業薬品や試薬品が使用できる。濃度は特に定める必要はないが、濃度は高い方で良く、３５％程度のものを用いる。過酸化水素水は連続的でも間欠的でも添加できるが、連続的に添加する方が良い。
【００２６】
循環槽７の一定温度・一定電位の電解液２は配管１１のポンプ１２で抜き出され、電解槽１に戻される。なお、電解中、プレーティングによって電解液２中の金濃度が減少した場合などには、適宜電解液組成を確認し、新たに塩化金酸液を加える。
【００２７】
このように、電解液２に過酸化水素水を添加して電解液２の電位を上げることにより、プレーティング反応を抑制でき、電解槽１などの電解精製装置の表面に付着する金の量を大幅に減少させることができた。このため、付着した金の除去作業がほとんど不要となり、電解精製装置の稼働率を向上できた。さらに、特にプレーティング対策を施すことなく浄液設備１７を設けることができ、設備コストやランニングコストを削減できると共に、浄液設備１７を稼働させることで、不純物であるパラジウムの含有率を大幅に下げることができ、製品の品質を安定化できた。また、電解液温度を下げたことにより、塩酸ミストの発生量も大幅に減少し、腐食の防止、作業環境の改善がなされた。
【００２８】
【実施例】
次に、本発明の金の精製方法の具体的な実施例を述べる。
【００２９】
（実施例）
図１の電解精製装置を用い、表１に示した電解条件のもとで電解精製を行った。塩化金酸液の組成（ｇ／リットル）は、Ａｕが１００、Ｆ‐ＨＣｌが１００、Ａｇが１０、Ｐｄが２０、Ｐｔが２０であった。電解液温度は循環槽で４０℃となるように、循環槽で加熱した。電解液の循環量は２リットル／分であった。また、循環槽に濃度３５重量％の過酸化水素水を１０ないし１００ｃｃ／分の割合で添加し、循環槽内に装入した電位計により、電解液の電位が１２００ｍＶで一定に保持されるように、過酸化水素水の添加量を調節した。
【００３０】
【表１】

この結果、電解精製装置の電解液接触面に付着する金の量は大幅に減少し、かつ電解精製装置の稼働率も向上した。さらに浄液設備を稼働させることで不純物であるパラジウムの含有率を大幅に下げることができ、製品の品質が安定した。また、電解液温度を４０℃までに下げたことにより、塩酸ミストの発生量も大幅に減少し、作業環境も良好となった。これらの結果を表２に示す。
【００３１】
【表２】

（比較例）図１の電解精製装置を用い、表１に示した電解条件のもとで電解精製を行った。上記実施例と同じ組成の塩化金酸液を用い、塩化金酸液の電解液には酸化剤は添加せず、電解液温度を６０℃に一定に保った。この結果を表２に示す。
【００３２】
【発明の効果】
以上詳述したように、本発明によれば、電解液に酸化剤を添加して電解液の酸化還元電位を上げたため、プレーティングを生じる化学反応が抑制され、プレーティングによる電解液との接触面への金付着量を大幅に減少できる。
【００３３】
このため、付着した金の除去作業がほとんど不要となり、電解精製装置の稼働率を向上でき、生産性を上げることができる。さらに、プレーティング対策を施すことなく浄液設備を設けることができ、設備コストやランニングコストを削減できると共に、浄液設備を稼働させることで、不純物であるパラジウム等の含有率を大幅に低下でき、精製金の品質を安定化できる。また、電解液温度を下げたことにより、塩酸ミストの発生量も大幅に減少でき、腐食の防止、作業環境の改善が図れる。
【図面の簡単な説明】
【図１】本発明に係る金の電解精製装置の一実施形態を示す概略構成図である。
【図２】従来の金の電解精製装置の概略構成図である。
【符号の説明】
１電解槽
２電解液
３陰極
４陽極
７循環タンク
８温度計
９ヒーター
１３電位計
１４酸化剤供給系
１５バルブ
１６制御装置
１７浄液装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gold electrolytic purification method and a gold electrolytic purification apparatus, and in particular, adheres to an equipment surface such as an apparatus or piping in contact with an electrolytic solution at the time of gold electrolytic purification without depending on electrolytic deposition. The present invention relates to a method for electrorefining gold and a device therefor which reduce so-called plating (see Chemical Dictionary, Vol. 8, page 73, Kyoritsu Publishing).
[0002]
[Prior art]
Electrorefining of gold is a method of casting crude gold obtained by treating anode mud during silver electrolytic smelting on a plate as an anode, and obtaining pure gold on the cathode plate using a chloroauric acid solution as the electrolyte It is carried out under electrolytic conditions based on the so-called Wall Will method (see Chemical Dictionary 2, Vol. 926, Kyoritsu Publishing).
[0003]
A conventional gold electrolytic purification method will be described using the gold electrolytic purification apparatus shown in FIG. The electrolytic cell 1 contains an electrolytic solution 2 made of a chloroauric acid solution, and a cathode 3 made of pure titanium and an anode 4 made of coarse gold wrapped with a filter cloth 5 are suspended in the electrolytic cell 1. An AC / DC power supply 6 is connected to the crude gold anode 4, gold containing impurities is dissolved in the electrolyte 2, and gold is deposited on the cathode 3.
[0004]
The electrolytic solution 2 in the electrolytic cell 1 is partially extracted from the pipe 10 and enters a circulation tank (tank) 7. The electrolytic solution 2 in the circulation tank 7 is heated by the heater 9. The heater 9 is controlled by the thermometer 8, and the electrolytic solution 2 in the circulation tank 7 is maintained at a constant temperature. The electrolytic solution 2 having a constant temperature in the circulation tank 7 is extracted by the pump 12 of the pipe 11 and returned to the electrolytic tank 1.
[0005]
Further, since the gold concentration in the electrolytic solution 2 is reduced by plating during electrolysis, the composition of the electrolytic solution is appropriately confirmed, and a chloroauric acid solution is newly added. In this way, the gold electrodeposited on the cathode 3 is melted and cast into a mold and sold as refined gold.
[0006]
[Problems to be solved by the invention]
However, in the conventional gold electrolytic refining method, the amount of gold deposited by plating on the surface of the electrolytic equipment in contact with the electrolytic solution 2, such as the electrolytic cell 1, the circulation tank 7, the

pipes

10 and 11, is large. It was. The attached gold had to be removed, but the current supply had to be stopped during the removal work, and the operating rate of the electrolysis equipment was low.
[0007]
In addition, since impurities in the crude gold anode are usually accumulated in the electrolytic solution to lower the purity of the product, a liquid purification process (liquid purification equipment) for continuous removal is required. In the absence of liquid purification equipment, a small amount of impurities co-deposit with gold that is electrolytically deposited, resulting in unstable product quality. However, if the liquid purification equipment can cope with the plating phenomenon, the equipment amount and running cost are increased.
[0008]
Moreover, hydrochloric acid was used for the electrolytic solution 2, the concentration of free hydrochloric acid was as high as 100 g / liter, and the temperature of the electrolytic solution 2 was as high as 60 ° C., so that hydrochloric acid mist was generated. For this reason, there was a smell of hydrochloric acid around the electrolysis equipment, and it was necessary to take sufficient measures against corrosion and working environment.
[0009]
The present invention has been made to solve the above-mentioned problems of the prior art, can reduce plating, improve the operation rate of electrolytic refining, simplify the liquid purification equipment, and reduce the work environment. It is an object of the present invention to provide a method and an apparatus for electrolytically purifying gold that can be improved.
[0010]
[Means for Solving the Problems]
To achieve the above object, the gold electrolytic purification method according to the present invention is a gold electrolytic purification method in which gold is dissolved in an electrolytic solution using crude gold as an anode, and high-purity gold is deposited on the cathode. Thus, an oxidizing agent is added to the electrolytic solution.
[0011]
The present inventor has made various studies in order to deal with the plating phenomenon, and has found the following. That is, during electrolysis, when gold dissolves from the raw gold anode, which is a raw material, it elutes into the electrolytic solution in two forms of AuCl ₄ ⁻ and AuCl ₂ ⁻ . Among AuCl ₂ ^- is equilibrium reaction formula _{^{_{^{3AuCl 2 - ⇔2Au + AuCl 4 -}}}} + 2Cl -
It is presumed that Au precipitates due to a rightward reaction (disproportionation reaction) and plating occurs. According to the above chemical formula, plating can be prevented by suppressing the reaction directed to the right.
[0012]
Therefore, the present inventor conducted electrolysis by lowering the electrolyte temperature and adding various chemicals to the electrolyte in order to suppress plating. As a result, it was found that an oxidizing agent such as hydrogen peroxide solution is effective. That is, the oxidation-reduction potential of the electrolytic solution is 500 mV in the conventional chloroauric acid solution to which no chemical solution (oxidant) is added. It was found that the decomposition reaction of AuCl ₂ ^{− having} the above chemical formula is suppressed. That is, by adding an oxidizing agent to the electrolytic solution, by selecting an optimal redox potential, the reaction of the above chemical formula can be suppressed, and the amount of gold deposited on the electrolytic solution contact surface by plating is greatly reduced.
[0013]
In the above invention, the oxidizing agent is preferably one or more selected from hydrogen peroxide, hypochlorite, hypochlorous acid, and chlorine gas. Of these, hydrogen peroxide solution was most effective when used alone, but one or more may be used in combination.
[0014]
Moreover, in the said invention, it is preferable to hold | maintain the temperature of electrolyte solution at 20 to 55 degreeC, More preferably, it is good to hold | maintain at 35 to 45 degreeC.
[0015]
The reason why the temperature of the electrolytic solution is 20 ° C. or higher is that the electrolytic efficiency is low at 20 ° C. or lower, and that the temperature of the electrolytic solution is 55 ° C. or lower is better from the viewpoint of electrolytic efficiency, This is to prevent the self-decomposition of an oxidizing agent such as hydrogen peroxide solution and a large amount of hydrochloric acid mist.
[0016]
In addition, when the temperature of the electrolytic solution is maintained by circulating the supply of the electrolytic solution whose temperature is adjusted on the circulating tank side that circulates and supplies the electrolytic solution to the electrolytic cell, the electrolytic purification is performed in a plurality of electrolytic cells. In addition, it is possible to suppress variations in the temperature of the electrolytic solution for each electrolytic cell.
[0017]
Moreover, in the said invention, it is preferable to hold | maintain the oxidation-reduction potential of electrolyte solution at 1000 mV-1400 mV by addition of an oxidizing agent, More preferably, it is good to hold | maintain at 1100 mV-1300 mV.
[0018]
The reason why the oxidation-reduction potential of the electrolytic solution is set to 1000 mV or more is that when 1000 mV or more, Au has a more stable state of Au ⁺ than Au ⁰ and plating can be suppressed.
The reason why the oxidation-reduction potential of the electrolytic solution is set to 1400 mV or less is to maintain the stability of the oxidizing agent. (If the oxidation-reduction potential is 800 mV to 1700 mV, H ₂ 0 ₂ or the like exhibits an action as an oxidizing agent, but if it exceeds 1400 mV, for example, H ₂ 0 ₂ generates H ₂ gas. Stability is reduced.)
[0019]
By maintaining the oxidation-reduction potential of the electrolytic solution by circulating supply of the electrolytic solution whose oxidation-reduction potential is adjusted by the addition of an oxidizing agent on the circulation tank side that circulates and supplies the electrolytic solution to the electrolytic cell, a plurality of electrolytic cells Even when electrolytic purification is carried out in this manner, variation in the oxidation-reduction potential of the electrolytic solution for each electrolytic cell can be suppressed.
[0020]
The gold electrolytic purification apparatus according to the present invention is a gold electrolytic purification apparatus that dissolves gold in an electrolytic solution using crude gold as an anode, and deposits high-purity gold on the cathode, and oxidizes the electrolytic solution. In order to maintain the reduction potential within a predetermined range, a control means for controlling the supply amount of the oxidizing agent added to the electrolytic solution is provided.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of the gold electrolytic purification apparatus of the present invention.
[0022]
In FIG. 1, 1 is an electrolytic cell. The electrolytic cell 1 contains an electrolytic solution 2 in which an oxidizing agent is added to a chloroauric acid solution. Further, a cathode 3 made of pure titanium and an anode 4 made of coarse gold wrapped with a filter cloth 5 are suspended in the electrolytic cell 1. An AC / DC power supply 6 is connected to the crude gold anode 4, and gold containing impurities is dissolved in the electrolyte 2, and gold is deposited on the cathode 3.
[0023]
The electrolytic cell 1 is provided with a circulation tank (tank) 7 for circulating and supplying the electrolytic solution 2 adjusted to a predetermined temperature and oxidation-reduction potential to the electrolytic cell 1. The capacity of the circulation tank 7 is 150 liters, and the material is made of polypropylene. The electrolytic solution 2 in the electrolytic cell 1 is partially extracted from the pipe 10 and enters the circulation tank 7. The pipe 10 is provided with a liquid purification equipment 17 for removing impurities present in the electrolytic solution 2. ing.
[0024]
The temperature of the electrolytic solution 2 is measured by the thermometer 8 so that the temperature of the electrolytic solution 2 in the circulation tank 7 is maintained within a predetermined range, and the control device 16 controls the heating of the heater 9 based on the measured value. It has become. The upper limit of the temperature of the electrolytic solution 2 is 55 ° C., and the lower limit is 20 ° C. The higher the electrolytic efficiency, the better. However, this is because the temperature is such that hydrogen peroxide water does not self-decompose as an oxidizing agent and does not generate a large amount of hydrochloric acid mist.
[0025]
Further, hydrogen peroxide water (H ₂ O ₂ ) is appropriately supplied as an oxidizing agent from the oxidizing agent supply system 14 to the circulation tank 7, and the oxidation-reduction potential of the electrolytic solution 2 in the circulation tank 7 is maintained within a predetermined range. An electrometer 13 is provided in the circulation tank 7, and a control device 16 controls the opening / closing or opening degree of the valve 15 of the oxidant supply system 14 according to the measurement signal, or a pump (not shown) of the oxidant supply system 14. 2). The potential of the electrolytic solution 2 is controlled in the range of 1000 mV to 1400 mV. The range of 1100 mV to 1300 mV is preferable, and the process is usually performed at 1200 mV. As the hydrogen peroxide solution, industrial chemicals and reagent products can be used. The concentration does not need to be set in particular, but the higher concentration may be used, and a concentration of about 35% is used. The hydrogen peroxide solution can be added continuously or intermittently, but it is better to add it continuously.
[0026]
The electrolytic solution 2 having a constant temperature and a constant potential in the circulation tank 7 is extracted by the pump 12 of the pipe 11 and returned to the electrolytic tank 1. In addition, when the gold concentration in the electrolytic solution 2 is reduced by plating during electrolysis, the composition of the electrolytic solution is confirmed as appropriate, and a chloroauric acid solution is newly added.
[0027]
Thus, by adding hydrogen peroxide water to the electrolytic solution 2 and increasing the potential of the electrolytic solution 2, the plating reaction can be suppressed, and the amount of gold attached to the surface of the electrolytic purification apparatus such as the electrolytic cell 1 can be reduced. It was possible to greatly reduce. For this reason, the removal operation | work of the gold | metal | money adhering became unnecessary and it was able to improve the operation rate of the electrolytic purification apparatus. Furthermore, it is possible to provide the liquid purification equipment 17 without taking any special measures against plating, and it is possible to reduce equipment costs and running costs. By operating the liquid purification equipment 17, the content of palladium as an impurity is greatly increased. The quality of the product could be stabilized. In addition, by reducing the electrolyte temperature, the amount of hydrochloric acid mist generated was greatly reduced, preventing corrosion and improving the work environment.
[0028]
【Example】
Next, specific examples of the gold purification method of the present invention will be described.
[0029]
(Example)
Using the electrolytic purification apparatus of FIG. 1, electrolytic purification was performed under the electrolytic conditions shown in Table 1. The composition (g / liter) of the chloroauric acid solution was 100 for Au, 100 for F-HCl, 10 for Ag, 20 for Pd, and 20 for Pt. The electrolyte solution was heated in the circulation tank so that the electrolyte temperature was 40 ° C. in the circulation tank. The circulation rate of the electrolytic solution was 2 liters / minute. In addition, a 35 wt% concentration of hydrogen peroxide water is added to the circulation tank at a rate of 10 to 100 cc / min, and the potential of the electrolyte is kept constant at 1200 mV by an electrometer installed in the circulation tank. The amount of hydrogen peroxide solution added was adjusted.
[0030]
[Table 1]

As a result, the amount of gold adhering to the electrolytic solution contact surface of the electrolytic purification apparatus was greatly reduced, and the operating rate of the electrolytic purification apparatus was improved. Furthermore, by operating the liquid purification equipment, the content of palladium, which is an impurity, can be greatly reduced, and the product quality has been stabilized. Moreover, by reducing the electrolyte temperature to 40 ° C., the amount of hydrochloric acid mist generated was greatly reduced and the working environment was improved. These results are shown in Table 2.
[0031]
[Table 2]

(Comparative example) Using the electrolytic purification apparatus of FIG. 1, electrolytic purification was performed under the electrolytic conditions shown in Table 1. A chloroauric acid solution having the same composition as in the above example was used, and no oxidant was added to the electrolyte solution of the chloroauric acid solution, and the electrolyte temperature was kept constant at 60 ° C. The results are shown in Table 2.
[0032]
【The invention's effect】
As described above in detail, according to the present invention, an oxidizing agent is added to the electrolytic solution to raise the oxidation-reduction potential of the electrolytic solution, so that a chemical reaction that causes plating is suppressed, and contact with the electrolytic solution by plating is achieved. The amount of gold deposited on the surface can be greatly reduced.
[0033]
For this reason, the removal operation | work of the gold | metal | money adhering becomes almost unnecessary, can improve the operation rate of an electrolytic refining apparatus, and can raise productivity. Furthermore, liquid purification equipment can be provided without taking plating measures, and equipment costs and running costs can be reduced. By operating the liquid purification equipment, the content of impurities such as palladium can be greatly reduced. , Can stabilize the quality of refined gold. In addition, by reducing the electrolyte temperature, the amount of hydrochloric acid mist generated can be greatly reduced, preventing corrosion and improving the working environment.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a gold electrolytic purification apparatus according to the present invention.
FIG. 2 is a schematic configuration diagram of a conventional gold electrolytic purification apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrolysis tank 2 Electrolyte 3 Cathode 4 Anode 7 Circulation tank 8 Thermometer 9 Heater 13 Electrometer 14 Oxidant supply system 15 Valve 16 Controller 17 Cleaner

Claims

In an electrolytic bath, in a method for electrolytically purifying gold, in which gold is dissolved in an electrolytic solution using crude gold as an anode, and high-purity gold is deposited on a cathode,
An oxidizing agent is added to the electrolytic solution,
The gold-metal oxide is characterized in that the oxidation-reduction potential of the electrolytic solution is maintained by circulating supply of the electrolytic solution whose oxidation-reduction potential is adjusted by the addition of the oxidizing agent on the circulation tank side that circulates and supplies the electrolytic solution to the electrolytic tank. Electrolytic purification method.

2. The gold electrolysis according to claim 1, wherein the temperature of the electrolytic solution is maintained by circulating and supplying a temperature-controlled electrolytic solution on a circulating tank side that circulates and supplies the electrolytic solution to the electrolytic cell. Purification method.

The gold electrolytic purification method according to claim 1 or 2, wherein a plurality of the electrolytic baths are provided, and the circulating bath circulates and supplies the electrolytic solution to the plurality of electrolytic baths.

4. The gold electrolytic purification according to claim 1, wherein the oxidizing agent is one or more selected from hydrogen peroxide, hypochlorite, hypochlorous acid, and chlorine gas. Method.

The gold electrolytic purification method according to any one of claims 1 to 4, wherein the temperature of the electrolytic solution is maintained at 20 ° C to 55 ° C.

The gold electrolytic purification method according to any one of claims 1 to 5, wherein the temperature of the electrolytic solution is maintained at 35 ° C to 45 ° C.

The gold electrolytic purification method according to any one of claims 1 to 6, wherein the oxidation-reduction potential of the electrolytic solution is maintained at 1000 mV to 1400 mV by the addition of the oxidizing agent.

The gold electrolytic purification method according to any one of claims 1 to 6, wherein the oxidation-reduction potential of the electrolytic solution is maintained at 1100 mV to 1300 mV by the addition of the oxidizing agent.

A gold electrolytic purification apparatus that dissolves gold in an electrolytic solution using crude gold as an anode and deposits high-purity gold on a cathode,
A circulation tank provided with a control means for controlling the supply amount of the oxidant added to the electrolytic solution and the liquid temperature of the electrolytic solution, and an electrolytic tank;
An electrorefining apparatus for gold, which circulates and supplies an electrolytic solution from a circulation tank to an electrolytic tank.