【発明の詳細な説明】[Detailed description of the invention]
〔産業上の利用分野〕
本発明は、金めつきに用いられているシアン化
金を含むめつき浴溶液を処理して精製することに
より、めつき浴溶液として再利用可能にする方法
に関する。
〔従来の技術〕
シアン化金を含む金めつき浴溶液には、めつき
加工中にめつき対象物等から持込まれる鉄、ニツ
ケル、クロム等の不純物が蓄積されてくる為、め
つき作業に悪影響を及ぼすようになる。これを避
けるためにはめつき浴溶液を定期的に更新する必
要があることから、従来不純物等で汚れためつき
浴溶液は回収業者に引取られ、酸化、還元工程を
繰返してシアン化金より純金に精製した後、再度
シアン化金に加工されめつき原料として再使用さ
れてきた。
このようなシアン化金を含む金めつき浴溶液の
再生処理方法では精製加工時にメタルロスを生
じ、経費、処理日数等に多くを要する問題があ
る。
〔発明が解決しようとする問題点〕
本発明は、この問題を解決し、短時間に簡単に
不純物等で汚れたシアン化金を含むめつき浴溶液
を再利用できるように処理する方法を提供するこ
とにある。
〔問題点を解決するための手段〕
本発明はシアン化金を含む金めつき浴溶液のPH
値を４〜７に調整した後、シアン化金を含むめつ
き浴溶液を加圧しながら逆浸透膜（以下CA膜と
云う）を通過させることによりシアン化金を透過
液中にそのまゝの形で効率良く回収し、めつき原
料として効率よくしかも迅速に再利用可能にする
ことを特徴とする。
水溶液をCA膜を通して通過させた場合、大部
分の溶質が膜面で通過を阻止されるため、CA膜
を透過した溶液は純水に近い性質をもつことが知
られている。
本発明者は原液タンクに貯められたシアン化金
を含むめつき浴溶液のPH値を４〜７に調整した
後、該溶液を25〜40Kg／cm2−Ｇに加圧しながら
CA膜を通過させ、CA膜を通過したシアン化金を
含むめつき浴溶液と、CA膜を透過しない濃縮液
とに分離し、CA膜を透過しない濃縮液は原液タ
ンクに廻流するような循環処理を行なうことによ
り、めつき作業に害をなす不純物である鉄、ニツ
ケル、クロム等を除去した清浄なめつき浴溶液を
CA膜の透過液として補集するシアン化金を含む
溶液の処理方法を見出した。
本発明にあつて原液タンク内の不純物は廻流を
重ねるに従つて濃縮されるため原液の浸透圧は徐
徐に上昇してくるので原液の浸透圧が操作圧と等
しくなつて透過液が出なくなつた時に作業を終了
する。
〔作用〕
本発明でシアン化金を含むめつき浴溶液のPH値
を４〜７と限定した理由は、PH値によるシアン化
金の回収率は殆んど影響を受けないがCA膜の使
用域がPH値４〜７と限定されており、この範囲以
外ではCA膜の充分な作用効果が見出せない為で
ある。
又、CA膜としては通常市販の酢酸セルロース
系の膜とナイロン系の膜とが使用でき、両者は第
２図の操作圧−シアン化金溶質透過率曲線及び第
３図の操作圧−透過液量曲線に示すように、操作
圧に対する透過率及び透過液量が若干相違するだ
けである。
〔実施例〕
実施例 １
金めつき浴槽の次段階にシアン化金を含むめつ
き浴溶液の回収槽を設置している工場の回収槽の
溶液を第１図に示す原液タンク１に移し、撹拌し
ながら高圧ポンプ５で35Kg／cm2に加圧し、酢酸セ
ルロース系逆浸透膜に通液した。
こゝで原液タンク１から送り出されたシアン化
金を含んだめつき浴溶液は濃縮液４と透過液３に
分離され、通液を開始してから45分で該溶液の浸
透圧が操作圧と等しくなつた。そこで透過液の流
出が停止した。濃縮液と透過液の組成分析を行な
つたところ、第１表に示す如く透過液３中の不純
物である鉄、ニツケル、クロムは大幅に減少する
と共に目的とするシアン化金としての金の回収率
は99.5％に達した。
[Industrial Field of Application] The present invention relates to a method of treating and purifying a plating bath solution containing gold cyanide used in gold plating so that it can be reused as a plating bath solution. [Prior art] Impurities such as iron, nickel, and chromium brought in from the objects to be plated during the plating process accumulate in a gold plating bath solution containing gold cyanide, so that impurities such as iron, nickel, and chromium are accumulated during the plating process. It will have a negative impact. In order to avoid this, it is necessary to periodically renew the plating bath solution. Conventionally, the plating bath solution contaminated with impurities is collected by a collection company, and the oxidation and reduction processes are repeated to convert the gold cyanide to pure gold. After refining, it is processed again into gold cyanide and reused as a plating raw material. Such a method for regenerating a gold plating bath solution containing gold cyanide has the problem that metal loss occurs during refining and requires a large amount of expense and processing time. [Problems to be Solved by the Invention] The present invention solves this problem and provides a method for easily processing a plating bath solution containing gold cyanide contaminated with impurities etc. so that it can be reused. It's about doing. [Means for Solving the Problems] The present invention aims to improve the pH of a gold plating bath solution containing gold cyanide.
After adjusting the value to 4 to 7, the plating bath solution containing gold cyanide is passed through a reverse osmosis membrane (hereinafter referred to as CA membrane) while pressurized, so that the gold cyanide is directly contained in the permeate. It is characterized by being able to be efficiently recovered in the form of plating materials and reused efficiently and quickly as a plating raw material. It is known that when an aqueous solution is passed through a CA membrane, most of the solutes are blocked by the membrane surface, so the solution that passes through the CA membrane has properties similar to pure water. The present inventor adjusted the pH value of a plating bath solution containing gold cyanide stored in a stock solution tank to 4 to 7, and then pressurized the solution to 25 to 40 kg/cm 2 -G.
The plating bath solution containing gold cyanide that has passed through the CA membrane is separated into a concentrated solution that does not pass through the CA membrane, and the concentrated solution that does not pass through the CA membrane is routed to the stock solution tank. A clean plating bath solution that removes impurities such as iron, nickel, and chromium, which are harmful to plating work, is produced through circulation processing.
We have found a method for treating a solution containing gold cyanide that is collected as a permeate through a CA membrane. In the present invention, the impurities in the stock solution tank are concentrated as the circulation continues, and the osmotic pressure of the stock solution gradually increases, so that the osmotic pressure of the stock solution becomes equal to the operating pressure, and no permeate is produced. Finish the work when you get tired of it. [Function] The reason why the pH value of the plating bath solution containing gold cyanide is limited to 4 to 7 in the present invention is that the recovery rate of gold cyanide is hardly affected by the pH value, but the use of a CA membrane is This is because the range of pH values is limited to 4 to 7, and sufficient effects of the CA membrane cannot be found outside this range. In addition, commercially available cellulose acetate-based membranes and nylon-based membranes can be used as CA membranes, and both have the operating pressure-gold cyanide solute permeability curve shown in Figure 2 and the operating pressure-permeated liquid curve shown in Figure 3. As shown in the volume curves, there are only slight differences in permeability and permeate volume versus operating pressure. [Example] Example 1 The solution in the recovery tank of a factory where a recovery tank for plating bath solution containing gold cyanide is installed next to the gold plating bath is transferred to the stock solution tank 1 shown in Fig. 1. While stirring, the mixture was pressurized to 35 kg/cm 2 using a high-pressure pump 5 and passed through a cellulose acetate reverse osmosis membrane. Here, the plating bath solution containing gold cyanide sent out from the stock solution tank 1 is separated into a concentrated solution 4 and a permeated solution 3, and the osmotic pressure of the solution reaches the operating pressure within 45 minutes from the start of liquid flow. They became equal. At that point, the outflow of the permeate stopped. A compositional analysis of the concentrate and permeate revealed that as shown in Table 1, the impurities iron, nickel, and chromium in permeate 3 were significantly reduced, and the desired gold cyanide was recovered. The rate reached 99.5%.
【表】
実施例 ２
処理溶液として、無電解金めつき浴の老廃液を
使用し、溶液の加圧度を30Kg／cm2−Ｇとした場合
の結果は第２表に示した如くであり、実施例１と
同様に不純物の除去率が高く目的とするシアン化
金としての金回収率も97.9％となつた。
この処理に要した時間は60分であつた。[Table] Example 2 When waste liquid from an electroless gold plating bath was used as the treatment solution and the degree of pressurization of the solution was 30 kg/cm 2 -G, the results were as shown in Table 2. As in Example 1, the impurity removal rate was high and the gold recovery rate as the target gold cyanide was 97.9%. The time required for this treatment was 60 minutes.
〔発明の効果〕〔Effect of the invention〕
本発明を実施することにより、シアン化金を含
むめつき浴溶液を迅速に且つ高能率で精製処理出
来る。又、この為めつき浴溶液の更新期間の著し
い延長に加え、めつき不良の原因除去にも効果が
及ぶと共に従来行なわれてきた酸化還元処理法に
比べて経済的にも大きな利益が得られる。
By carrying out the present invention, a plating bath solution containing gold cyanide can be purified quickly and with high efficiency. Furthermore, in addition to significantly extending the renewal period of the plating bath solution, it is also effective in eliminating the causes of poor plating, and provides significant economic benefits compared to conventional redox treatment methods. .
【図面の簡単な説明】[Brief explanation of drawings]
第１図は本発明実施の工程概略図を、第２図は
浸透膜材質による操作圧の変化に対する溶質透過
率の変化を、第３図は浸透膜材質による操作圧に
対する透過液量の変化を示した図である。
１……原液タンク、２……逆浸透膜、３……透
過液、４……濃縮液、５……高圧ポンプ。
Figure 1 shows a schematic diagram of the process of implementing the present invention, Figure 2 shows changes in solute permeability due to changes in operating pressure due to the permeable membrane material, and Figure 3 shows changes in permeated liquid amount due to changes in operating pressure due to the permeable membrane material. FIG. 1... Stock solution tank, 2... Reverse osmosis membrane, 3... Permeated liquid, 4... Concentrated liquid, 5... High pressure pump.