JPH0149778B2 - - Google Patents
Info
- Publication number
- JPH0149778B2 JPH0149778B2 JP14001885A JP14001885A JPH0149778B2 JP H0149778 B2 JPH0149778 B2 JP H0149778B2 JP 14001885 A JP14001885 A JP 14001885A JP 14001885 A JP14001885 A JP 14001885A JP H0149778 B2 JPH0149778 B2 JP H0149778B2
- Authority
- JP
- Japan
- Prior art keywords
- silver
- agcn
- cyanide
- waste liquid
- ozone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- LFAGQMCIGQNPJG-UHFFFAOYSA-N silver cyanide Chemical compound [Ag+].N#[C-] LFAGQMCIGQNPJG-UHFFFAOYSA-N 0.000 claims description 65
- 239000007788 liquid Substances 0.000 claims description 43
- 239000002699 waste material Substances 0.000 claims description 37
- 229910052709 silver Inorganic materials 0.000 claims description 36
- 238000007747 plating Methods 0.000 claims description 34
- 239000004332 silver Substances 0.000 claims description 34
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 claims description 33
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 32
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 20
- 229940098221 silver cyanide Drugs 0.000 claims description 18
- 239000002244 precipitate Substances 0.000 claims description 12
- 239000002253 acid Substances 0.000 claims description 11
- 239000003513 alkali Substances 0.000 claims description 10
- 238000001914 filtration Methods 0.000 claims description 6
- 238000011084 recovery Methods 0.000 description 18
- 239000010949 copper Substances 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 10
- 238000000354 decomposition reaction Methods 0.000 description 9
- 239000000243 solution Substances 0.000 description 9
- 230000007423 decrease Effects 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- DOBRDRYODQBAMW-UHFFFAOYSA-N copper(i) cyanide Chemical compound [Cu+].N#[C-] DOBRDRYODQBAMW-UHFFFAOYSA-N 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 150000003378 silver Chemical class 0.000 description 2
- 235000011121 sodium hydroxide Nutrition 0.000 description 2
- 101710134784 Agnoprotein Proteins 0.000 description 1
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 235000011118 potassium hydroxide Nutrition 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 238000005406 washing Methods 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
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は使用済の銀めつき廃液からの銀の回収
方法に関し、さらに詳しくは、シアン化銀
（AgCN）を用いる銀めつき廃液からの銀の回収
方法に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for recovering silver from a used silver plating waste solution, and more specifically, to a method for recovering silver from a used silver plating waste solution using silver cyanide (AgCN). Concerning silver recovery methods.
［従来の技術］
一般に、電気めつき法によつて銀めつきが行わ
れた後の使用済の銀めつき廃液は、主成分が
AgCNであり、不純物として被めつき材から溶出
したシアン化銅（CuCN）がシアン化アルカリ光
沢剤等も含むが、大量の銀を含んでいる。このた
め、この銀めつき廃液からの銀の回収が図られて
おり、従来から、使用済の銀めつき廃液に直流電
圧を印加し、陰極側に銀を析出させて回収する電
解法が広く行われている。ところが、この方法で
は比較的高い純度の銀を回収できるものの、金属
銀として回収されるため、これを再びAgCNとし
て電解浴に再利用するには、まず硝酸に溶解して
濃縮した後、AgNO3として結晶せしめ、さらに
この飽和水溶液にシアン化アルカリの濃厚液を加
えて生じた沈澱を熱アンモニア液から再結晶する
必要がある。またこのような方法による銀の回収
は一般のめつき工場においては不可能であり、使
用済めつき廃液を精錬業者に委託精錬または売却
しているのが実情である。[Prior art] Generally, the main component of the used silver plating waste liquid after silver plating is carried out by the electroplating method.
It is AgCN, and copper cyanide (CuCN) eluted from the plating material as an impurity also contains alkali cyanide brighteners, etc., but it also contains a large amount of silver. For this reason, efforts have been made to recover silver from this silver plating waste liquid, and conventionally, an electrolytic method has been widely used in which a DC voltage is applied to the used silver plating waste liquid to deposit silver on the cathode side and recover it. It's being done. However, although silver of relatively high purity can be recovered with this method, it is recovered as metallic silver, so in order to reuse it in the electrolytic bath as AgCN, it must first be dissolved in nitric acid and concentrated, and then AgNO 3 It is necessary to add a concentrated alkali cyanide solution to this saturated aqueous solution and recrystallize the resulting precipitate from hot ammonia solution. Furthermore, recovery of silver using this method is not possible in general plating factories, and the reality is that used plating waste liquid is contracted out to refining companies or sold.
そこで、使用済の銀めつき廃液からAgCNのま
まで銀を回収する方法として、銀めつき廃液に酸
を加えることにより液中のシアン化アルカリをガ
ス化し、Ag（CN）2 -の錯イオンの形で溶解してい
るAgを、AgCNとして沈澱させて回収すること
が堤案されている。 Therefore, as a method for recovering silver from used silver plating waste liquid in the form of AgCN, by adding acid to the silver plating waste liquid, the alkali cyanide in the liquid is gasified, and Ag(CN) 2 - complex ions are recovered. It has been proposed to collect dissolved Ag in the form of AgCN by precipitating it.
［発明が解決しようとする問題点］
ところが、この銀めつき廃液に酸を加え、
AgCNとして沈澱させて回収する方法は、簡便で
はあるものの、共存している他のシアン化合物、
特にCuCNが不溶化して沈澱物中に混入するた
め、銀の純分が低く、このままの形で再利用する
ことは難しい。[Problems to be solved by the invention] However, when acid was added to this silver plating waste liquid,
Although the method of precipitating and recovering AgCN is simple,
In particular, since CuCN becomes insolubilized and mixed into the precipitate, the pure silver content is low, making it difficult to reuse it as is.
［問題点を解決するための手段］
この発明は、かかる現状に艦み種々検討を行つ
た結果なされたもので、使用済のシアン化銀めつ
き廃液に酸またはアルカリを加えてPHを９以上に
調整し、次いで、この廃液にオゾンを作用させる
ことによつて、廃液中の遊離シアンを完全に分解
し、生成した沈澱を濾過分離して、AgCNとして
回収するか、あるいは廃液にオゾンを作用させて
行う廃液中の遊離シアンの分解を、完全には行わ
ず、生成した沈澱を濾過分離して、AgCNとして
回収するとともに、さらにAgCNを分離除去した
分離液に酸またはアルカリを加えてPHを７以下に
調整し、生成した沈澱を濾過分離して、AgCNと
して回収することによつて、高純度のAgCNを
100％近い回収率で回収できるようにしたもので
ある。[Means for Solving the Problems] This invention was made as a result of various studies in view of the current situation. Then, by applying ozone to this waste liquid, free cyanide in the waste liquid is completely decomposed, and the generated precipitate is separated by filtration and recovered as AgCN, or by applying ozone to the waste liquid. The free cyanide in the waste liquid is not completely decomposed, but the precipitate formed is separated by filtration and recovered as AgCN, and the pH is adjusted by adding acid or alkali to the separated liquid from which AgCN has been separated and removed. 7 or less, filter and separate the generated precipitate, and collect it as AgCN to obtain highly pure AgCN.
This allows the collection rate to be close to 100%.
この発明において、使用済のシアン化銀めつき
廃液は、酸またはアルカリを加えてPHを９以上に
調整した後、オゾンを吹き込んで反応させるのが
好ましく、銀めつき廃液のPHを９以上に調整して
オゾンと反応させると、下記の反応式
2CN-＋5O3→2CO2＋N2＋11／2O2
に示すように、オゾンが遊離のシアン化アルカリ
に対してほぼ化学当量的に反応して、CN-はCO2
とN2に分解される。そして、この反応をさらに
進めると、Ag（CN）2 -として溶けていた錯イオン
のCNが酸化をうけてAgCNの沈澱を生成する。
また、Cu（CN）-2として錯イオンを形成していた
Cuは、オゾンによる酸化をうけてCu（CN）4 -2ま
たはCu（CN）2の錯体を形成し、液中に溶解した
状態でとどまる。従つて、このようにして得られ
た反応液を濾別し、水洗、乾燥すればAgCNの回
収と精製が同時に行われ、銀がAgCNの状態で回
収される。 In this invention, it is preferable to adjust the pH of the used silver cyanide plating waste liquid to 9 or higher by adding acid or alkali, and then blow ozone into it to cause a reaction. When adjusted and reacted with ozone, as shown in the following reaction formula 2CN - +5O 3 →2CO 2 +N 2 +11/2O 2 , ozone reacts with free alkali cyanide almost chemically equivalently, CN - CO2
and N2 . When this reaction proceeds further, the complex ion CN dissolved as Ag(CN) 2 - is oxidized to form a precipitate of AgCN.
In addition, complex ions were formed as Cu(CN) -2 .
When Cu is oxidized by ozone, it forms a complex of Cu(CN) 4 -2 or Cu(CN) 2 and remains dissolved in the liquid. Therefore, by filtering the reaction solution obtained in this way, washing with water, and drying, recovery and purification of AgCN are performed simultaneously, and silver is recovered in the form of AgCN.
このように、シアン化銀めつき廃液のPHを９以
上に調整してオゾンを吹き込み、オゾンによる遊
離シアンの分解を行うと、シアンの分解が進むに
つれてPHが低下し、遊離シアンが完全に分解され
て終点に近づくとほぼ一定の値を示すようにな
る。しかして、たとえば、反応開始時のPHを12〜
12.5とし、PHが低下してほぼ一定の値９〜9.5を
示すようになるまでシアン化銀めつき廃液にオゾ
ンを吹き込み、遊離シアンの分解反応を行えば、
シアン化銀めつき廃液中の遊離シアンが完全に分
解されてAgCNとして沈澱し、100％近い回収率
で銀がAgCNの状態で回収される。またPHを９以
上に調整しているため、共存しているCuCNは前
記したように液中に溶解した状態にとどまり、不
溶化して沈澱物中に混入することもないため
AgCNが高純度で回収される。 In this way, when the pH of the silver cyanide plating waste liquid is adjusted to 9 or higher and ozone is blown in to decompose free cyanide with ozone, the pH decreases as the cyanide decomposition progresses, and the free cyanide is completely decomposed. As it approaches the end point, it shows an almost constant value. For example, if the pH at the start of the reaction is 12~
12.5, and ozone is blown into the silver cyanide plating waste solution until the pH decreases to a nearly constant value of 9 to 9.5 to perform a decomposition reaction of free cyanide.
Free cyanide in the silver cyanide plating waste liquid is completely decomposed and precipitated as AgCN, and silver is recovered in the form of AgCN with a recovery rate of nearly 100%. In addition, since the pH is adjusted to 9 or higher, the coexisting CuCN remains dissolved in the liquid as described above, and does not become insolubilized and mixed into the precipitate.
AgCN is recovered with high purity.
このように、オゾンを吹き込んで反応させる際
の使用済シアン化銀めつき廃液のPHは、オゾンに
よる遊離シアンの分解反応を良好に行わせるため
酸またはアルカリを加えて９〜14のアルカリ性に
するのが好ましく、遊離シアンの分解速度をより
速めるため、種々の条件を考慮するとPHを12〜13
に調整するのがより好ましい。このようなPHの調
整のため加えられる酸としては、硫酸、硝酸など
が使用され、またアルカリとしては、苛性ソー
ダ、苛性カリなどが使用される。 In this way, when reacting by blowing ozone, the pH of the used silver cyanide plating waste liquid is made alkaline to 9 to 14 by adding acid or alkali so that the decomposition reaction of free cyanide by ozone can be carried out well. is preferable, and in order to further accelerate the decomposition rate of free cyanide, the pH should be adjusted to 12 to 13, considering various conditions.
It is more preferable to adjust to As acids added to adjust the pH, sulfuric acid, nitric acid, etc. are used, and as alkalis, caustic soda, caustic potash, etc. are used.
以上のように、所定のPH値に調整されたシアン
化銀めつき廃液にオゾンを吹き込み、オゾンによ
る遊離シアンの分解を完全に行う場合は、高純度
のAgCNが100％近い回収率で回収されるが、反
面PHが低下してほぼ一定の値を示すようになるま
でシアン化銀めつき廃液にオゾンを吹き込まなけ
ればならないため、遊離シアンを完全に分解させ
るまでに長時間を要し、ランニングコスト上から
は不利となる。 As described above, if ozone is blown into the silver cyanide plating waste liquid adjusted to a predetermined pH value and free cyanide is completely decomposed by ozone, highly pure AgCN can be recovered with a recovery rate of nearly 100%. However, on the other hand, it is necessary to blow ozone into the silver cyanide plating waste solution until the pH decreases to a nearly constant value, so it takes a long time to completely decompose free cyanide, and running This is disadvantageous from a cost standpoint.
このため、この発明の銀めつき廃液からの銀の
回収方法は、必ずしも、オゾンによる遊離シアン
の分解を完全に行わずに、たとえば、遊離シアン
を80〜90％分解させるまでは、オゾンによる遊離
シアンの分解を行つて、生成されたAgCNを回収
し、さらに濾別された分離液に残留する銀は、こ
の分離液に酸を加えてPH値を弱酸性に再調整し、
AgCNとして沈澱させて回収してもよい。この方
法による場合は、オゾンによる遊離シアンの分解
を完全に行わないため、濾別された分離液に銀が
残留するが、残留する銀は、この分離液のPH値を
弱酸性に再調整し、AgCNとして沈澱させて回収
しているため、オゾンによる遊離シアンの分解を
完全に行う場合と同様に、100％近い回収率で
AgCNが回収される。また、PHが低下してほぼ一
定の値を示すようになるまでシアン化銀めつき廃
液にオゾンを吹き込む必要がないため、この
AgCNの回収が100％近い回収率で、短時間に行
え、ランニングコスト上極めて有利で効率のよい
AgCNの回収が行える。このように分離液に酸を
加え、PH値を弱酸性に再調整してAgCNとして沈
澱させ、回収する際のPH域は２〜５の範囲内にす
るのが好ましい。 Therefore, in the method of recovering silver from silver plating waste liquid of this invention, it is not necessary to completely decompose free cyanide with ozone. Cyanide is decomposed and the AgCN produced is recovered, and the silver remaining in the separated liquid is filtered by adding acid to the separated liquid to readjust the pH value to weak acidity.
It may be precipitated and recovered as AgCN. In this method, free cyanide is not completely decomposed by ozone, so silver remains in the filtered separated liquid, but the remaining silver is removed by readjusting the pH value of this separated liquid to a weakly acidic one. Since it is recovered by precipitation as AgCN, the recovery rate is close to 100%, which is the same as when free cyanide is completely decomposed by ozone.
AgCN is recovered. In addition, there is no need to blow ozone into the silver cyanide plating waste solution until the pH decreases and shows an almost constant value.
Recovery of AgCN is close to 100%, can be done in a short time, and is extremely advantageous and efficient in terms of running costs.
AgCN can be recovered. In this way, it is preferable to add an acid to the separated liquid, readjust the pH value to weakly acidic, precipitate it as AgCN, and keep the pH range within the range of 2 to 5 during recovery.
［実施例］ 以下、この発明の実施例について説明する。[Example] Examples of the present invention will be described below.
実施例
供試廃液は、電気めつき法でシアン化銀めつき
を行つた後の廃液で、Ag、Cu、CNを下記の組
成割合で含む使用済シアン化銀めつき廃液を使用
した。Example The sample waste liquid was a waste liquid after silver cyanide plating was performed using an electroplating method, and was a used silver cyanide plating waste liquid containing Ag, Cu, and CN in the composition ratios shown below.
Ag 22.2ｇ／
Cu 2.3ｇ／
全Cu 15.3ｇ／
この使用済シアン化銀めつき廃液に、苛性ソー
ダを加えて反応開始PHを12.5に調整した。次い
で、このPHが12.5の使用済シアン化銀めつき廃液
中に、この廃液１に対しオゾンをO3として１
ｇ／ｈの割合で吹き込んで反応させ、遊離のシア
ンを分解した。 Ag 22.2g/Cu 2.3g/Total Cu 15.3g/ Caustic soda was added to this spent silver cyanide plating waste solution to adjust the reaction initiation pH to 12.5. Next, add 1 part of ozone to the used silver cyanide plating waste liquid with a pH of 12.5 as O 3 to 1 part of this waste liquid.
The reaction was carried out by blowing at a rate of g/h to decompose free cyanide.
第１図は、このようにして遊離のシアンを分解
したときの反応時間に対するPH値の変化をグラフ
で示したものである。この第１図のグラフから明
らかなように、遊離シアンの分解と共にPHが低下
するが、反応が進行するにつれてその変化が少な
くなりほぼ一定値を示すようになる。 FIG. 1 is a graph showing the change in pH value with respect to reaction time when free cyanide is decomposed in this manner. As is clear from the graph in FIG. 1, the pH decreases as free cyanide decomposes, but as the reaction progresses, the change decreases and becomes almost constant.
また第２図は、このような遊離シアンの分解反
応が、第１図のグラフにおいてＡポイントで示す
ように、完全に近い時点でのサンプルを分取し、
段階的にPHを調整して生成した固形分を濾別、水
洗、乾燥し、AgCNとしての回収率及び固形分中
のAgCNの純分の割合を示したものであり、さら
に第３図は、このような遊離シアンの分解反応
が、第１図のグラフにおいてＢポイントで示すよ
うに、80〜90％終了した時点でのサンプルを分取
し、段階的にPHを調整して生成した固形分を濾
別、水洗、乾燥し、AgCNとしての回収率及び固
形分中のAgCNの純分の割合を示したものであ
る。これら第２図および第３図から明らかなよう
に、分解反応が充分に行われたとみられる段階で
は回収率はさほどPH値の影響をうけない（第２
図）が、分解反応が不充分な段階ではアルカリ性
に傾くに従つて回収率が極端に低下（第３図）す
る。またAgCNの純分については、弱アルカリ性
の方が高い数値が得られ、分解反応の進行度の影
響をあまり受けない。 In addition, FIG. 2 shows that a sample is taken at a point when the decomposition reaction of free cyanide is almost complete, as shown by point A in the graph of FIG.
The solid content produced by adjusting the pH in stages is filtered, washed with water, and dried, and the recovery rate as AgCN and the pure content of AgCN in the solid content are shown. As shown by point B in the graph of Figure 1, a sample is collected when 80 to 90% of the decomposition reaction of free cyanide has been completed, and the pH is adjusted stepwise to obtain the solid content. was filtered, washed with water, and dried, and the recovery rate as AgCN and the percentage of pure AgCN in the solid content are shown. As is clear from these Figures 2 and 3, the recovery rate is not significantly affected by the PH value at the stage where the decomposition reaction is considered to have taken place sufficiently (the 2nd
(Fig. 3), but at a stage where the decomposition reaction is insufficient, the recovery rate decreases extremely as the alkalinity increases (Fig. 3). Regarding the purity of AgCN, a higher value can be obtained in the case of weak alkalinity, and it is not affected much by the degree of progress of the decomposition reaction.
次ぎに、実施例において、シアンの分解を完全
に近い第１図のグラフのＡポイントまで行い、生
成した沈澱を濾別、水洗、乾燥して得られた固形
分の成分分析を行つたところ、次の結果を得た。 Next, in the example, cyanide was decomposed to almost complete point A in the graph of FIG. I got the following results.
Ag 78.8％
Cu 0.06％
CN 19.0％
その他（水分等） 2.2％
また、実施例において、第１図のグラフのＢポ
イントにおける反応液をPH9.5に調整し、生成し
た沈澱を濾別、水洗、乾燥して得られた固形分の
成分分析を行つたところ、次の結果を得、
Ag 78.6％
Cu 0.07％
CN 18.7％
その他（水分等） 2.6％
次いで、さらに分離液をPH３に調整し残余の
AgCNを沈澱せしめ上澄液についてAg及びCuに
ついて分析したところ次の結果を得た。 Ag 78.8% Cu 0.06% CN 19.0% Others (moisture, etc.) 2.2% In addition, in the example, the reaction solution at point B in the graph of Fig. 1 was adjusted to pH 9.5, and the generated precipitate was separated by filtration, washed with water, When we analyzed the components of the solid matter obtained by drying, we obtained the following results: Ag 78.6% Cu 0.07% CN 18.7% Others (moisture etc.) 2.6% Next, the separated liquid was further adjusted to pH 3 and the remaining
When AgCN was precipitated and the supernatant was analyzed for Ag and Cu, the following results were obtained.
Ag 0.07ｇ／
Cu 2.2ｇ／
［発明の効果］
以上の分析結果から明らかなように、いずれに
おいてもシアン化銀めつき廃液主成分のAgCNと
不純分であるCuCNの分離が効率よく行われてお
り、このことから本発明の方法による使用済シア
ン化銀めつき廃液からのAgCNの回収方法は、回
収率、純度とも極めて良好であることがわかる。
また、第１図のＡポイントにおけるようにシアン
化合物を完全に分解した場合は、AgCNの回収率
がさほどPH値の影響を受けず、AgCNの純分も高
くて100％近い回収率で銀がAgCNとして回収で
きることがわかる。さらに第１図のＢポイントに
おけるように遊離シアンの分解を100％行わずに、
ある程度の反応が進んだ時点で中性〜弱アルカリ
性にPHを調整して、生成したAgCNを濾別し、さ
らに分離された濾液を弱酸性に調整し、残余の
AgCNを沈澱回収する場合も純分の高いAgCNを
回収することができ、さらにこの方法によれば、
遊離シアンを完全に分解する場合に比べて、遊離
シアンの分解に要する時間が50〜70％でよく、ラ
ンニングコスト上極めて有利であることがわか
る。また、この発明の回収方法は、AgCNの状態
で再利用できるという特徴があり、実際本発明法
によつて回収せられたAgCNを用いて銀めつきを
施したところ、新しく建浴しためつき浴との比較
において何等遜色のない製品が得られ、従来の回
収方法では得られない効率のよいAgCNの回収が
行えることがわかつた。 Ag 0.07g/Cu 2.2g/ [Effects of the invention] As is clear from the above analysis results, in all cases, AgCN, the main component of the silver cyanide plating waste liquid, and CuCN, the impurity, were efficiently separated. This shows that the method of recovering AgCN from spent silver cyanide plating waste liquid according to the method of the present invention is extremely good in terms of both recovery rate and purity.
In addition, when the cyanide is completely decomposed as at point A in Figure 1, the recovery rate of AgCN is not affected by the pH value so much, and the purity of AgCN is high, so that silver can be recovered with a recovery rate of nearly 100%. It can be seen that it can be recovered as AgCN. Furthermore, without decomposing 100% of free cyanide as at point B in Figure 1,
Once the reaction has progressed to a certain extent, adjust the pH to neutral to slightly alkaline, filter out the AgCN produced, and adjust the separated filtrate to slightly acidic to remove the remaining
When collecting AgCN by precipitation, it is possible to collect highly pure AgCN, and furthermore, according to this method,
It can be seen that the time required to decompose free cyanide is only 50 to 70% compared to the case where free cyanide is completely decomposed, which is extremely advantageous in terms of running costs. In addition, the recovery method of this invention has the feature that it can be reused in the AgCN state, and in fact, when silver plating was performed using the AgCN recovered by the method of the present invention, it was found that the silver plating of newly built baths did not change. It was found that AgCN could be recovered efficiently, which is not possible with conventional recovery methods, and a product was obtained that was comparable to that of the bath.
第１図はシアン化銀メツキ廃液中の遊離シアン
を分解したときの反応時間とPH値との関係図、第
２図および第３図は同遊離シアンを分解し、生成
した固形分を濾別したときのPH値と、AgCNとし
ての回収率および純分との関係図である。
Figure 1 shows the relationship between reaction time and PH value when free cyanide in the silver cyanide plating waste liquid is decomposed, and Figures 2 and 3 show the relationship between the reaction time and PH value when the free cyanide is decomposed and the solid content produced is filtered out. FIG. 3 is a relationship diagram between the PH value and the recovery rate and purity as AgCN.
Claims (1)
ルカリを加えてPHを９以上に調整した後、この廃
液にオゾンを作用させて液中の遊離シアンを分解
し、生成した沈澱を濾過分離して、AgCNとして
回収することを特徴とする銀めつき廃液からの銀
の回収方法。 ２ 使用済のシアン化銀めつき廃液に酸またはア
ルカリを加えてPHを９以上に調整した後、この廃
液にオゾンを作用させて液中の遊離シアンを分解
し、生成した沈澱を濾過分離して、AgCNとして
回収するとともに、AgCNを分離除去した分離液
にさらに酸またはアルカリを加えてPHを７以下に
調整し、生成した沈澱を濾過分離して、AgCNと
して回収することを特徴とする銀めつき廃液から
の銀の回収方法。[Claims] 1. After adjusting the pH to 9 or higher by adding acid or alkali to the used silver cyanide plating waste liquid, ozone is applied to this waste liquid to decompose the free cyanide in the liquid and generate A method for recovering silver from a silver plating waste solution, which comprises separating the precipitate by filtration and recovering it as AgCN. 2 Add acid or alkali to the used silver cyanide plating waste liquid to adjust the pH to 9 or higher, then apply ozone to this waste liquid to decompose free cyanide in the liquid, and filter and separate the formed precipitate. The silver is recovered as AgCN, and the separated liquid from which AgCN is separated and removed is further added with an acid or alkali to adjust the pH to 7 or less, and the generated precipitate is separated by filtration and recovered as AgCN. Method for recovering silver from plating waste liquid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60140018A JPS621829A (en) | 1985-06-26 | 1985-06-26 | Recovering method for silver from silvering waste liquor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60140018A JPS621829A (en) | 1985-06-26 | 1985-06-26 | Recovering method for silver from silvering waste liquor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS621829A JPS621829A (en) | 1987-01-07 |
| JPH0149778B2 true JPH0149778B2 (en) | 1989-10-26 |
Family
ID=15259021
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60140018A Granted JPS621829A (en) | 1985-06-26 | 1985-06-26 | Recovering method for silver from silvering waste liquor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS621829A (en) |
-
1985
- 1985-06-26 JP JP60140018A patent/JPS621829A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS621829A (en) | 1987-01-07 |
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