JP2004066130A

JP2004066130A - Waste liquid treatment method

Info

Publication number: JP2004066130A
Application number: JP2002230206A
Authority: JP
Inventors: Satoru Yonetake; 米竹　哲; Junichi Ito; 伊藤　潤一; Haruyuki Imaizumi; 今泉　沿幸; Masashi Nanaumi; 七海　賢史; Tetsuo Kikuchi; 菊地　哲郎
Original assignee: Hitachi Communication Technologies Ltd; Nichiyo Engineering Corp
Current assignee: Hitachi Communication Technologies Ltd; Nichiyo Engineering Corp
Priority date: 2002-08-07
Filing date: 2002-08-07
Publication date: 2004-03-04
Anticipated expiration: 2022-08-07
Also published as: JP4024106B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste liquid treatment method by which a component 1 and a component 2 are efficiently taken out from a waste liquid produced in a manufacturing process of a printed circuit board. <P>SOLUTION: The method is characterized in that, In a evaporation concentration treatment performed in a concentration vessel 15 by heating the waste liquid consisting essentially of the component 1 having fixed solubility to water even when the temperature is increased and the component 2 having solubility in water higher than that of the component 1 and increased with the temperature rising, after the concentration vessel 15 is cleaned at first, a crystal deposited in more than saturated solubility in the component 1 to reach the saturated solubility in the first time by supplying the waste liquid to the concentration vessel 15 and heating in the concentration vessel 15 is taken out as the crystal by a filtration means 17 while dehydrating with dehydrating air and steam, and next, the waste liquid is cooled before the component 2 contained in the waste liquid reaches the saturated solubility and the component 2 reaching the saturated solubility at a cooling temperature and crystallized is taken out as a crystal by the filtration means 17 while dehydrating. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明はプリント配線板等の製造工程で排出される廃液の処理方法に関する。
【０００２】
【従来の技術】
従来電子機器等に使用されるプリント配線板は、例えば図３及び図４に示す製造工程を経て製造されている。
【０００３】
まず図４に示す材料の準備工程で、図４の（イ）に示すプリント配線板ａが準備される。
【０００４】
プリント配線ａは、基材ｂの片面または両面（図４の（イ）は両面のものを示す）に銅箔層ｃが予め形成されており、このプリント配線板ａは次のスルーホール穴明工程で、電子部品等を実装する個所に図４の（ロ）に示すようにスルーホールｄが穿設される。
【０００５】
その後触媒付与工程でスルーホールｄの内周面に、図４の（ハ）に示すように触媒ｅが付着された後、回路形成工程で、銅箔層ｃがエッチング処理されて、銅箔層ｃに回路ｆが形成される。
【０００６】
回路形成工程により回路ｆが形成されたプリント配線板ａは、化学銅メッキ工程で銅メッキ処理が施されるが、このとき析出反応により銅イオンを金属銅として析出すると同時に、メッキ液中に硫酸ソーダとキ酸ソーダが次式により析出され、廃液中蓄積される。
【０００７】
ＣｕＳＯ_４＋４ＮａＯＨ＋２ＨＣＨＯ→Ｃｕ＋Ｎａ_２ＳＯ４＋２ＮａＣＯＯＨ＋Ｈ_２＋２Ｈ_２Ｏ
また化学銅めっき処理により、図４の（ホ）に示すようにスルーホールｄの内面及び回路ｆに銅めっきｇが施されたプリント配線板ａは、次のソルダーレジスト工程で、図４の（へ）に示すように基材ｂの表裏面にソルダレジストｈが形成されて、完成されたプリント配線板ａとして製造工程より搬出される。
【０００８】
一方化学銅めっき工程で発生した廃液は、再度使用可能な状態に再生するため、電気透析装置を用いて再生処理しており、また化学銅めっき処理及び電気透析処理により生じた廃液中より銅イオンや、ＥＤＴＡ成分を回収する装置としては、例えば特開平６−１７０１１７号公報に記載された「銅回収装置」や、特開平６−２４６１５７号公報に記載された「ＥＤＴＡ回収装置」が公知である。
【０００９】
【発明が解決しようとする課題】
しかし前記公報の銅回収装置や、ＥＤＴＡ回収装置では、銅イオンや、ＥＤＴＡ成分に付いては回収することができるが、廃液中に蓄積された硫酸ソーダやギ酸ソーダは、反応生成物であるため、回収することができない。
【００１０】
特にギ酸ソーダを未回収のまま一般排水として河川等へ排出する場合は、生物化学的処理によりＣＯＤ（化学的酸素要求量）を水質基準以下にしてから排出する必要があるが、生物化学的処理は大掛かりな処理設備や、設備を運転するのに多くの専従員を必要とするため、廃液の処理に多大な費用がかかるなどの問題がある。
【００１１】
本発明はかかる従来の問題点を解決するためになされたもので、プリント配線板等の製造工程で発生した廃液より硫酸ソーダやギ酸ソーダなどの成分を、容易かつ効率よく取り出すことができる廃液処理方法を提供することを目的とするものである。
【００１２】
【課題を解決するための手段】
前記目的を達成するため本発明の廃液の処理方法は、製造工程から排出される廃液の処理方法であって、温度を上昇させても水への溶解度が一定である成分１と、成分１よりも水への溶解度が高く、温度上昇に従って水への溶解度が上昇する成分２を主成分とする廃液を濃縮槽内で高温に加熱して、廃液中の水分を蒸発させることにより濃縮処理を行うに当り、まず濃縮槽の内面に付着した結晶を洗浄した後、濃縮槽へ廃液を供給して濃縮槽内で加熱することにより、最初に飽和溶解度に到達する成分１中の飽和溶解度以上の結晶を、脱液用空気及び蒸気により脱液しながら濾過手段により結晶として取り出し、次に廃液に含まれる成分２が加熱温度で飽和溶解度に達する前に冷却して、冷却温度で飽和溶解度に到達し結晶化した成分２を、脱液用空気及び蒸気により脱液しながら濾過手段により結晶として取り出すようにしたものである。
【００１３】
前記方法により、製造工程から排出された廃液中の主成分である成分１と成分２を、廃液中より容易かつ効率よく取出すことができると共に、廃液より取り出した成分１と成分２は別個に再利用することができるため、経済的である上、濃縮処理を行う前に濃縮槽内を洗浄するようにしたことから、内面に付着した結晶により廃液の加熱が妨げられることがないため、水分の蒸発が効率よく行えるようになる。
【００１４】
また濃縮液を脱液しながら濾過手段により結晶を濾過する際、蒸気により濾過手段及びその周辺の配管が加熱されて脱液による温度低下を防止するため、結晶により濾過手段や配管等が目詰まりを起こす心配もない。
【００１５】
前記目的を達成するため本発明の廃液の処理方法は、プリント配線板等の製造工程から排出される廃液の処理方法であって、温度を上昇させても水への溶解度が一定である硫酸ソーダと、硫酸ソーダよりも水への溶解度が高く、温度上昇とともに水への溶解度が上昇するギ酸ソーダを主成分とする廃液を濃縮槽内で高温に加熱して濃縮処理を行うに当り、まず濃縮槽の内面に付着した結晶を洗浄した後、濃縮槽へ廃液を供給して廃液中の水分を蒸発させることにより、まず最初に飽和溶解度に到達する硫酸ソーダ中の飽和溶解度以上の結晶を、脱液用空気及び蒸気により脱液しながら濾過手段により硫酸ソーダ結晶として取り出し、次に廃液に含まれるギ酸ソーダが加熱温度での飽和溶解度に達する前に冷却して、冷却温度で飽和溶解度に到達し結晶化したギ酸ソーダを、脱液用空気及び蒸気により脱液しながら濾過手段によりギ酸ソーダ結晶として取り出すようにしたものである。
【００１６】
前記方法により、プリント配線板の製造工程から排出される廃液中の主成分である硫酸ソーダ及びギ酸ソーダを、廃液中より容易かつ効率よく取り出すことができると共に、廃液より取り出した硫酸ソーダ及びギ酸ソーダは別個に再利用できるため、経済的である上、濃縮処理を行う前に濃縮槽内を洗浄するようにしたことから、内面に付着した結晶により廃液の加熱が妨げられることがないため、水分の蒸発が効率よく行えるようになる。
【００１７】
また濃縮液を脱液しながら濾過手段により結晶を濾過する際、蒸気により濾過手段及びその周辺の配管が加熱されて脱液による温度低下を防止するため、結晶により濾過手段や配管等が目詰まりを起こす心配がない上、廃液よりギ酸ソーダを取り出すのに大掛かりな生物化学的処理装置や、これを運転するための多くの専従員を必要としないので、ローコストで廃液の処理が可能になる。
【００１８】
前記目的を達成するため本発明の廃液の処理方法は、プリント配線板等の製造工程から排出される廃液の処理方法であって、温度を上昇させても水への溶解度が一定である硫酸ソーダと、温度の上昇と共に水への溶解度が上昇するギ酸ソーダを主成分とする化学銅めっき廃液中に含まれる銅イオン及びＥＤＴＡを回収した後の廃液、及び化学銅めっき液の電気透析処理により生じた廃液を混合して濃縮槽内で高温に加熱することにより濃縮処理を行うに当り、まず濃縮槽の内面に付着した結晶を洗浄した後、濃縮槽へ廃液を供給して廃液中の水分を蒸発させることにより、まず最初に飽和溶解度に到達する硫酸ソーダ中の飽和溶解度以上の結晶を、脱液用空気及び蒸気により脱液しながら濾過手段により硫酸ソーダ結晶として取り出し、次に廃液に含まれるギ酸ソーダが加熱温度で飽和溶解度に達する前に冷却して、冷却温度で飽和溶解度に到達し結晶化したギ酸ソーダを、脱液用空気及び蒸気により脱液しながら濾過手段によりギ酸ソーダ結晶として取り出すようにしたものである。
【００１９】
前記方法により、プリント配線板の製造工程から排出される廃液中の主成分である硫酸ソーダ及びギ酸ソーダを廃液中より容易かつ効率よく取り出すことができると共に、廃液より取り出した硫酸ソーダ及びギ酸ソーダは別個に再利用できるため、経済的である上、濃縮処理を行う前に濃縮槽内を洗浄するようにしたことから、内面に付着した結晶により廃液の加熱が妨げられることがないため、水分の蒸発が効率よく行えるようになる。
【００２０】
また濃縮液を脱液しながら濾過手段により結晶を濾過する際、蒸気により濾過手段及びその周辺の配管が加熱されて脱液による温度低下を防止するため、結晶により濾過手段や配管等が目詰まりを起こす心配がない上、化学銅めっき処理により排出される廃液と、電気透析処理により排出される廃液を同一の処理装置で同時に処理できるため、これら廃液を別々の処理装置で処理する場合に比べて、設備の大幅な削減が図れる。
【００２１】
前記目的を達成するため本発明の廃液の処理方法は、濃縮槽内を洗浄するに当り、まず濃縮槽内へ給水して水で洗浄し、その後蒸気を供給して、蒸気で加熱しながら蒸気洗浄することにより、濃縮槽の内面に付着固化した結晶を洗浄するようにしたものである。
【００２２】
前記方法により、濃縮槽の内面に強固に付着した結晶でも、容易かつ確実に除去することができる。
【００２３】
前記目的を達成するため本発明の廃液の処理方法は、途中にバイパスバルブの設けられたバイパス管を濾過手段と並列に設けたものである。
【００２４】
前記方法により、濃縮処理終了後バイパスバルブを開放して、管路内の濃縮液中の成分（ギ酸ソーダ）が飽和溶解温度に達する前の濃縮液を、バイパス管を介して一気に最終濃縮液受け槽に排出することにより、濾過手段やその周辺の配管等が結晶により目詰まりを起こすのを未然に防止することができる。
【００２５】
【発明の実施の形態】
本発明の廃液処理方法を、プリント配線板を製造する製造工程で排出される廃液に実施した実施の形態について、図面を参照して詳述する。
【００２６】
図１は廃液処理装置の構成図を示すもので、化学銅めっき処理工程で発生した化学銅めっき廃液を貯留する化学銅めっき廃液タンク１と、透析廃液タンク１２を備えており、化学銅めっき廃液タンク１はポンプ２を介して銅回収槽３へ、また透析廃液タンク１２はポンプ１３を介して濾液中和槽１０に接続されている。
【００２７】
銅回収槽３には、槽内の廃液を銅回収濾過機５を介して循環させ、またＥＤＴＡ晶析槽６へ送るポンプ４が接続されており、ＥＤＴＡ晶析槽６には、槽内の廃液を攪拌する攪拌機６ａが設けられていると共に、槽内の廃液を循環させ、またＥＤＴＡ濾過機８へ送るポンプ７が接続されている。
【００２８】
なお銅回収濾過機５内には、銅イオンを析出させる触媒を付着させたフィルタ（図示せず）が設けられている。
【００２９】
ＥＤＴＡ濾過機８には、ＥＤＴＡ晶析槽６で固液分離されたＥＤＴＡ結晶Ｃを廃液中より濾過して、ＥＤＴＡ受け槽９へ排出するロール状の濾材８ａが設けられており、ＥＤＴＡ濾過機８によりＥＤＴＡ結晶Ｃが除去された中和廃液Ｄは、濾液中和槽１０へ送られて、透析廃液Ｂと混合される。
【００３０】
なお中和廃液Ｄは、必ずしも透析廃液Ｂと混合する必要はなく、各々別のタンクに単独させて貯留しても勿論よい。
【００３１】
濾液中和槽１０は、ポンプ１４及び中和廃液バルブ４０を介して濃縮槽１５に接続されており、濃縮槽１５内の廃液は、手動または自動で開閉される濃縮液排出手動弁１６を介して結晶濾過機１７に滴下されるようになっている。
【００３２】
濃縮槽１５には、途中に給水バルブ２３が設けられた給水管２４と、途中に蒸気バルブ２５が設けられた蒸気供給管２６が接続されていて、これら給水管２４及び蒸気供給管２６より供給される水と蒸気により濃縮槽１５の内面に付着固化した結晶を洗浄できるようになっている。
【００３３】
また濃縮液排出手動弁１６が設けられた管路２７の濃縮液排出手動弁１６より下側には、途中に脱液用空気バルブ２８の設けられた空気供給管２９と、途中に脱液用蒸気バルブ３０が設けられた蒸気供給管３１が接続されていて、これら空気供給管２９及び蒸気供給管３１より供給される空気と蒸気により結晶濾過機１７の脱液が行えるようになっている。
【００３４】
結晶濾過機１７には、廃液中より硫酸ソーダ（成分１）の結晶Ｆとギ酸ソーダ（成分２）の結晶Ｇを濾過するロール状の濾材１７ａが設けられていて、この濾材１７ａにより濾過された結晶Ｆ，Ｇは、結晶受け槽１８に回収され、結晶濾過機１７により成分１，２が除去された廃液は、最終濃縮液受け槽１９に回収されると共に、結晶濾過機１７には、途中にバイパスバルブ３２が設けられたバイパス管３３が並列に設けられていて、バイパスバルブ３２を開放することにより、濃縮槽１５内の廃液を結晶濾過機１７を通さずに、直接最終濃縮液受け槽１９へ一気に排出できるようにもなっている。
【００３５】
最終濃縮液受け槽１９には、ポンプ２０が接続されていて、槽内の廃液が濃縮槽１５及び循環路２２を介して循環され、かつ廃液中の水分は蒸発されて排気口２１を介して大気へ放出されることによりさらに濃縮されると共に、濃縮された廃液は最終濃縮液Ｈとして最終濃縮液受け槽１９に貯留されるように構成されている。
【００３６】
なお図１中３５は化学銅めっき処理装置を構成する化学銅めっき槽、３６は透析液受け槽、３７は電気透析装置、３８は透析廃液受け槽で、化学銅めっき槽３５で廃液となった化学銅めっき廃液が、化学銅めっき廃液タンク１へ送られ、透析廃液受け槽３８の透析廃液が透析廃液タンク１２へ送られるようになっている。
【００３７】
次に前記構成された廃液処理装置を使用してプリント配線板の製造工程で排出される廃液の処理方法を説明する。
【００３８】
プリント配線板の製造工程でされる化学銅めっき液は、使用後に硫酸ソーダ、ギ酸ソーダが蓄積した化学銅めっき廃液Ａとなるので、化学銅めっき廃液タンク１に貯留し、また硫酸ソーダ、ギ酸ソーダが蓄積した化学銅めっき廃液を再度使用可能な状態へ再生する電気透析装置３７で生じた透析廃液Ｂは、透析廃液タンク１２に貯留する。
【００３９】
次に化学銅めっき廃液Ａを化学銅めっき廃液タンク１からポンプ２により銅回収槽３に供給すると、銅回収槽３では化学銅めっき廃液Ａを、めっき析出反応に必要な５０℃から７０℃までの範囲で加熱した後、還元剤（ホルマリン）とｐｈ調整材（苛性ソーダ）を化学銅めっき析出反応に必要な量（銅１ｍｏｌに対し、ホルマリン２ｍｏｌ、苛性ソーダ４ｍｏｌ）を添加すると共に、ポンプ４により銅回収槽３の化学銅めっき廃液Ａを、銅回収濾過機５を介して再度銅回収槽３へ循環させることにより、化学銅めっき廃液中の銅イオンを、銅回収濾過機５に金属銅として析出させ、銅回収濾過機５により廃液Ａ中の銅イオンを回収する。
【００４０】
次に、銅イオンを回収した後の化学銅めっき廃液Ａを、ＥＤＴＡ晶析槽６に送ると共に、ＥＤＴＡ晶析槽６では、ＥＤＴＡ結晶Ｃを晶析するため、攪拌機６ａにより攪拌及び３０℃以下まで冷却しながらｐＨ調整剤（硫酸）を添加して、ｐＨ２以下に下げる。
【００４１】
そしてその廃液ＡをＥＤＴＡ濾過機８へ送って、固液分離したＥＤＴ結晶Ｃを濾材８ａにより濾過し、ＥＤＴＡ受け槽９に回収すると共に、濾材８ａを通過した廃液Ａ液は、濾液中和槽１０に中和廃液Ｄとして貯留し、また透析処理によって生じた透析廃液Ｂも同様に、中和廃液Ｄとして濾液中和槽１０に貯留する。
【００４２】
なお濾液中和槽１０に貯留された中和廃液Ｄの濃度は、例えばプリント基板面積５０ｍ^２　に対して２５μｍの銅析出後の廃液で、前記銅イオンとＥＤＴＡ回収後の中和廃液Ｄ「１」に対して透析廃液「３」の比率で混合した廃液中には、硫酸ソーダが約４５ｇ／Ｌ、ギ酸ソーダが約３５ｇ／Ｌを含んでおり、図２に示すように硫酸ソーダの溶解度は３５℃以上ではほぼ一定なのに対して、ギ酸ソーダは温度上昇とともに上昇する性質がある。
【００４３】
本発明では、この性質を利用して廃液中より硫酸ソーダとギ酸ソーダを取り出すもので、蒸発濃縮処理に当っては、まず給水管２４の給水バルブ２３を開放して濃縮槽１５内を水で洗浄し、次に給水バルブ２３を開放したまま蒸気バルブ２５を開放して、水と蒸気を連続的に濃縮槽１５へ供給することにより、濃縮槽１５内を１００℃で３０分間蒸気洗浄して、前回の処理で濃縮槽１５の内面に付着固化した結晶を洗浄する。
【００４４】
これによって濃縮槽１５の内面に付着固化した結晶により廃液の加熱が妨げられることがなくなるため、廃液中の水分の蒸発が効率よく行えると同時に、水分蒸発量が低下するのを防止するもので、濃縮槽１５内の加熱は蒸気によらず、電気ヒータなどを使用してもよい。
【００４５】
濃縮槽１５内を一定時間蒸気洗浄したら、給水バルブ２３を閉じた後中和廃液バルブ４０を開放して、濾液中和槽１０に貯留してある中和廃液Ｄを、ポンプ１４により濃縮槽１５に連続的に供給すると共に、最終濃縮液受け槽１９内の最終濃縮液Ｈもポンプ２０により濃縮槽１５へ連続的に供給して、濃縮槽１５内を蒸気により１２０℃まで加熱し、中和廃液Ｄ中の水分を蒸発させる。
【００４６】
またこのとき最終濃縮液Ｈのギ酸ソーダ濃度が急激に上昇するために発生する結晶により、結晶濾過機１７やその周辺の配管が目詰まりを起こすのを防止するため、中和廃液Ｄの供給量より濃縮槽１５内で蒸発する水分量を引いた値から、中和廃液Ｄの供給量が１割程度増加するよう中和廃液Ｄと最終濃縮液Ｈの供給量を調整し、中和廃液Ｄの増量により余剰となった濃縮液は、オーバフロー管２２より最終濃縮液受け槽１９へオーバフローさせる。
【００４７】
図２に示すようにギ酸ソーダよりも、硫酸ソーダが水への溶解度が低いことから、濃縮槽１５を１２０℃に加熱することにより、最初に濃縮液Ｅ中に含まれる硫酸ソーダが飽和溶解度２９０ｇ／Ｌに到達して結晶化が開始される。
【００４８】
その後さらに濃縮槽１５を加熱し濃縮液Ｅ中の水分を蒸発させると、濃縮液Ｅの中に含まれるギ酸ソーダが濃縮槽１５の加熱温度１２０℃における飽和溶解度に到達するが、濃縮槽１５の過熱部分を除く周辺の配管や、結晶濾過機１７やその周辺の配管が外気温の影響を受けて、配管内を流れる濃縮液に過剰にギ酸ソーダが析出するため、結晶濾過機１７や配管に目詰まりが発生して処理の続行が困難になる。
【００４９】
これを防止するため、次の処理工程である終了作業工程の保持温度１００℃でギ酸ソーダの飽和溶解度１９１０ｇ／Ｌに到達する直前、例えばギ酸ソーダ濃度１９００ｇ／Ｌまで濃縮液Ｅの水分を蒸発させて、硫酸ソーダだけが結晶化している状態を形成する（なお中和廃液Ｄと最終濃縮液Ｈのギ酸ソーダ濃度、濃縮槽１５と最終濃縮液受け槽１９の合計容量及び、濃縮槽１５へ供給する廃液量と水分蒸発量によりギ酸ソーダの濃度を算出し管理する）。
【００５０】
そしてこの硫酸ソーダが結晶化している濃縮液Ｅを、濃縮液排出手動弁１６を一定時間（１〜２秒）開閉することにより結晶濾過機１７に滴下すると共に、その後脱液用蒸気バルブ３０及び脱液用エアバルブ２８を一定時間（１０〜３０秒）開いて、結晶濾過機１７へ蒸気と空気を供給することにより脱液しながら、結晶濾過機１７により濃縮液Ｅを濾過する。
【００５１】
濃縮液Ｅを結晶濾過機１７へ通過させることにより、濃縮液Ｅに溶解しきれない硫酸ソーダ結晶Ｆが濾材１７ａにより取り出されて結晶受け槽１８に回収され、濾材１７ａを通過した濃縮液Ｅは、最終濃縮液Ｈとして最終濃縮液受け槽１９へ排出される共に、前記濾過処理を繰り返すことにより、濃縮液Ｅに溶解しきれない硫酸ソーダ結晶Ｆの回収を繰り返し行う。
【００５２】
またこのとき脱液による温度低下の影響で、結晶濾過機１７や、その周辺の配管に結晶詰まりが発生しないように、結晶濾過機１７内と配管内に蒸気を供給して、ギ酸ソーダ結晶が過剰に析出しない温度（約１００℃以上）を維持しながら濾過作業を行う。
【００５３】
一方蒸発濃縮処理が終了したら、濃縮槽１５内の濃縮液Ｅを最終濃縮液受け槽１９へ排出するが、蒸発濃縮処理終了直後の濃縮槽１５内の濃縮液Ｅは、濃縮液Ｅと硫酸ソーダの結晶が混合している状態のため加熱温度１２０℃よりも低く、かつ温度低下によりギ酸ソーダが飽和溶解度に到達しないように１００℃に維持し、かつ一定時間（６０〜９０分）結晶濾過機１７を用いて濃縮液Ｅ中の硫酸ソーダ結晶を濾過しながら最終濃縮液受け槽１９へ排出する。
【００５４】
そして一定時間が経過したら、バイパス配管３３のバイパスバルブ３２を開放して、濃縮液Ｅがギ酸ソーダ飽和溶解度に到達する温度に冷却される前に、濃縮液Ｅを最終濃縮液受け槽１９に一気に排出する。
【００５５】
次に１５５０ｇ／Ｌのギ酸ソーダを含む最終濃縮Ｈを冷却してギ酸ソーダの回収を行うが、図２の硫酸ソーダ飽和溶解度曲線に示すように、硫酸ソーダは３５℃以下で結晶化を開始するので、３５℃から６０℃の範囲内の例えば５０℃まで濃縮液Ｅの冷却を行うが、５０℃でのギ酸ソーダの飽和溶解度は１２１０ｇ／Ｌであるため、３４０ｇ／Ｌのギ酸ソーダが最終濃縮液Ｈに溶解しきれず結晶化する。
【００５６】
このギ酸ソーダが結晶化している最終濃縮液Ｈをポンプ２０により濃縮槽１５へ循環させた後、濃縮液排出手動弁１６を一定時間（１〜２秒）開放して、濃縮槽１５内の最終濃縮液Ｈを結晶濾過機１７に滴下すると共に、その後脱液用蒸気バルブ３０及び脱液用エアバルブ２８を一定時間（１０〜３０秒）開放して、結晶濾過機１７内へ蒸気と空気を供給して、脱液しながら濾過処理を行う。
【００５７】
最終濃縮液Ｈが結晶濾過機１７の濾材１７ａを通過する際、最終濃縮液Ｈに溶解しきれないギ酸ソーダ結晶Ｇが濾材１７ａにより濾過されて結晶受け槽１８に回収され、濾材１７ａを通過した最終濃縮液Ｈは再び最終濃縮液受け槽１９へ排出される共に、前記濾過処理を繰り返すことにより、最終濃縮液Ｈに溶解しきれないギ酸ソーダ結晶Ｇを全て回収するもので、５０℃での結晶濾過は処理時の温度低下が少ない（１０℃程度）ため、過剰結晶化による詰まりは発生しないが、３５℃以下になると、温度低下の影響で結晶濾過機１７や、配管及び濃縮槽１５に硫酸ソーダが過剰結晶析出して目詰まりを起こし、濾過処理が不可能になる虞があるため、濾過処理中は温度を３５℃から６０℃の範囲に維持する。
【００５８】
なお前記実施の形態では、化学銅めっき工程で排出される化学銅めっき液Ａと、電気透析処理で排出される透析廃液Ｂを濾液中和槽１０に回収して、これら廃液Ａ，Ｂより硫酸ソーダとギ酸ソーダを取り出しているが、化学銅メッキ廃液Ａと透析廃液Ｂを混合せず、別工程で廃液処理するようにしても勿論よい。
【００５９】
またギ酸ソーダの回収をプリント配線板の製造工程終了後に行うようにしているが、最終濃縮液受け槽１９内の濃縮液Ｅの濃度が所定濃度になったところで、濃縮液Ｅを例えば５０℃に冷却して、ギ酸ソーダの回収を行うようにしても勿論よい。
【００６０】
さらに前記実施の形態では、プリント配線板の製造工程で排出される廃液より硫酸ソーダとギ酸ソーダを取り出す場合について説明したが、温度を上昇させても水への溶解度がほぼ一定である成分１と、成分１より水への溶解度が高く、、温度の上昇とともに水への溶解度が上昇する成分２とを主成分とする廃液中より、成分１及び成分２を取り出す廃液処理全般に適用できるものである。
【００６１】
【発明の効果】
本発明は以上詳述したようになるから、製造工程から排出された廃液中の主成分である成分１と成分２を、廃液中より容易かつ効率よく取出すことができると共に、廃液より取り出した成分１と成分２は別個に再利用することができるため、経済的である上、蒸発濃縮処理を行う前に濃縮槽内を洗浄するようにしたことから、内面に付着した結晶により廃液の加熱が妨げられることがないため水分の蒸発が効率よく行えると共に、濃縮液を脱液しながら濾過手段により結晶を濾過する際、蒸気により濾過手段及びその周辺の配管が加熱されて脱液による温度低下を防止するため、結晶により結晶濾過機や、その周辺の配管等が目詰まりを起こす心配がない。
【００６２】
またプリント配線板の製造工程で排出される廃液を処理する場合、廃液中の主成分である硫酸ソーダ及びギ酸ソーダを、廃液中より容易かつ効率よく取り出すことができる上、廃液より取り出した硫酸ソーダ及びギ酸ソーダは別個に再利用できるため経済的であると共に、廃液よりギ酸ソーダを取り出すのに大掛かりな生物化学的処理装置や、これを運転するための多くの専従員を必要としないので、ローコストで廃液の処理が可能である。
【００６３】
さらに化学銅めっき処理により排出される廃液と、電気透析処理により排出される廃液を同一の処理装置で同時に処理するこができるため、これら廃液を別々の処理装置で処理する場合に比べて、設備費の大幅な削減が図れる上、濃縮槽内を洗浄するに当たり、まず濃縮槽内へ給水して水で洗浄し、その後蒸気を供給して、蒸気で加熱しながら蒸気洗浄することにより、濃縮槽の内面に付着固化した結晶を洗浄するようにしたことにより、濃縮槽の内面に強固に付着した結晶でも、容易かつ確実に除去することができると共に、途中にバイパスバルブの設けられたバイパス管を濾過手段と並列に設ければ、濃縮処理終了後、バイパスバルブを開放して、管路内の濃縮液中の成分（ギ酸ソーダ）が飽和溶解温度に達する前の濃縮液を、バイパス管を介して一気に最終濃縮液受け槽に排出することができるため、濾過手段やその周辺の配管等が結晶により目詰まりを起こすのを未然に防止することができる。
【図面の簡単な説明】
【図１】
本発明の廃液処理方法を実施する廃液処理装置の構成図である。
【図２】
本発明の廃液処理方法を実施する廃液中の硫酸ソーダとギ酸ソーダの水への溶解度を示す線図である。
【図３】
プリント配線板の製造工程を示す工程図である。
【図４】
プリント配線板の製造過程を示す説明図である。
【符号の説明】
１　化学銅めっき廃液タンク
３　銅回収槽
５　銅回収濾過機
６　ＥＤＴＡ晶析槽
８　ＥＤＴＡ濾過機
９　ＥＤＴＡ受け槽
１０　濾液中和槽
１２　透析廃液タンク
１５　濃縮槽
１６　濃縮液排出手動弁
１７　結晶濾過機（濾過手段）
１８　結晶受け槽
１９　最終濃縮液受け槽
２１　排気口
２４　給水管
２６　蒸気供給管
２９　空気供給管
３１　蒸気供給管
３２　バイパスバルブ
３３　バイパス管[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for treating waste liquid discharged in a manufacturing process of a printed wiring board or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a printed wiring board used for an electronic device or the like is manufactured through manufacturing steps shown in FIGS. 3 and 4, for example.
[0003]
First, in a material preparation step shown in FIG. 4, a printed wiring board a shown in FIG. 4A is prepared.
[0004]
The printed wiring a has a copper foil layer c previously formed on one or both sides of a base material b ((a) of FIG. 4 shows both sides), and the printed wiring board a has the following through-hole holes. In the process, a through hole d is formed at a place where electronic components and the like are mounted as shown in FIG.
[0005]
Then, a catalyst e is attached to the inner peripheral surface of the through hole d in the catalyst application step as shown in FIG. 4C, and then, in the circuit forming step, the copper foil layer c is etched to form a copper foil layer. Circuit f is formed in c.
[0006]
The printed wiring board a on which the circuit f is formed in the circuit forming step is subjected to copper plating in a chemical copper plating step. At this time, copper ions are precipitated as metallic copper by a precipitation reaction, and at the same time, sulfuric acid is contained in the plating solution. Soda and sodium silicate are deposited by the following formula and accumulated in the waste liquid.
[0007]
CuSO ₄ + 4NaOH + 2HCHO → Cu + Na ₂ SO4 + 2NaCOOH + H ₂ + 2H ₂ O
In addition, as shown in FIG. 4E, the printed wiring board a having the copper plating g applied to the inner surface of the through hole d and the circuit f as shown in FIG. As shown in (h), the solder resist h is formed on the front and back surfaces of the base material b, and is carried out from the manufacturing process as a completed printed wiring board a.
[0008]
On the other hand, the waste liquid generated in the chemical copper plating process is regenerated using an electrodialysis device in order to regenerate it into a usable state again, and copper ions are removed from the waste liquid generated by the chemical copper plating process and the electrodialysis process. As a device for recovering the EDTA component, for example, a “copper recovery device” described in JP-A-6-170117 and an “EDTA recovery device” described in JP-A-6-246157 are known. .
[0009]
[Problems to be solved by the invention]
However, in the copper recovery apparatus and the EDTA recovery apparatus of the above publication, copper ions and EDTA components can be recovered, but sodium sulfate and sodium formate accumulated in the waste liquid are reaction products. , Cannot be recovered.
[0010]
In particular, when sodium formate is discharged to rivers and the like as general wastewater without being recovered, it is necessary to reduce COD (chemical oxygen demand) to water quality standards or less by biochemical treatment. However, there is a problem that a large-scale treatment facility and a large number of dedicated personnel are required to operate the facility, so that a large cost is required for treating the waste liquid.
[0011]
The present invention has been made to solve such a conventional problem, and a waste liquid treatment capable of easily and efficiently extracting components such as sodium sulfate and sodium formate from waste liquid generated in a manufacturing process of a printed wiring board and the like. It is intended to provide a method.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a method for treating waste liquid of the present invention is a method for treating waste liquid discharged from a manufacturing process, comprising: a component 1 having a constant solubility in water even when the temperature is increased; Also, the waste liquid mainly composed of the component 2 whose solubility in water increases with increasing temperature as the temperature rises is heated to a high temperature in a concentration tank to evaporate the water in the waste liquid to perform the concentration treatment. First, after washing the crystals attached to the inner surface of the concentration tank, the waste liquid is supplied to the concentration tank and heated in the concentration tank. Is taken out as crystals by means of filtration while dewatering with air and steam for dewatering, and then the component 2 contained in the waste liquid is cooled before reaching the saturation solubility at the heating temperature, and reaches the saturation solubility at the cooling temperature. The crystallized component 2 is While it dewatered by liquid air and vapor in which they were taken out as a crystal by filtration means.
[0013]
According to the above-mentioned method, the components 1 and 2 which are the main components in the waste liquid discharged from the manufacturing process can be easily and efficiently extracted from the waste liquid, and the components 1 and 2 extracted from the waste liquid can be separately recycled. It is economical because it can be used, and since the inside of the concentration tank is washed before performing the concentration treatment, the heating of the waste liquid is not hindered by the crystals attached to the inner surface, so that the water Evaporation can be performed efficiently.
[0014]
Also, when filtering the crystals by the filtering means while removing the concentrated liquid, the crystals heat the filtering means and the surrounding pipes to prevent the temperature from dropping due to the removal of liquid. No worries.
[0015]
In order to achieve the above object, a waste liquid treatment method of the present invention is a method for treating a waste liquid discharged from a manufacturing process of a printed wiring board or the like, and has a constant solubility in water even when the temperature is increased. Sodium formate whose solubility in water is higher than that of sodium sulfate and increases in temperature with increasing temperature After washing the crystals adhering to the inner surface of the tank, the waste liquid is supplied to the concentration tank to evaporate the water in the waste liquid. It is taken out as sodium sulfate crystals by a filtration means while being drained with liquid air and steam, and then cooled before the sodium formate contained in the waste liquid reaches the saturation solubility at the heating temperature, and reaches the saturation solubility at the cooling temperature. Was formic acid soda crystallized, in which they were taken out as formic acid soda crystals by filtration means with dewatered by draining air and steam.
[0016]
By the above method, sodium sulfate and sodium formate, which are the main components in the waste liquid discharged from the manufacturing process of the printed wiring board, can be easily and efficiently taken out from the waste liquid, and the sodium sulfate and sodium formate taken out from the waste liquid Is economical because it can be reused separately, and since the inside of the concentration tank is washed before performing the concentration treatment, the heating of the waste liquid is not hindered by the crystals attached to the inner surface. Can be efficiently evaporated.
[0017]
Also, when filtering the crystals by the filtering means while removing the concentrated liquid, the crystals heat the filtering means and the surrounding pipes to prevent the temperature from dropping due to the removal of liquid. In addition, since large-scale biochemical treatment equipment for removing sodium formate from waste liquid and many dedicated staffs for operating the same are not required, waste liquid can be treated at low cost.
[0018]
In order to achieve the above object, a waste liquid treatment method of the present invention is a method for treating a waste liquid discharged from a manufacturing process of a printed wiring board or the like, and has a constant solubility in water even when the temperature is increased. And the solubility of sodium formate, whose solubility in water increases as the temperature rises, is generated by the electrodialysis treatment of the wastewater after collecting copper ions and EDTA contained in the wastewater of chemical copper plating, and the chemical copper plating solution. In performing the concentration treatment by mixing the waste liquid and heating it to a high temperature in the concentration tank, first, the crystals attached to the inner surface of the concentration tank are washed, and then the waste liquid is supplied to the concentration tank to remove the water in the waste liquid. By evaporating, first, crystals having a saturation solubility or higher in the sodium sulfate reaching the saturation solubility are taken out as sodium sulfate crystals by a filtration means while being dewatered with dewatering air and steam, and then The sodium formate contained in the liquid is cooled before reaching the saturation solubility at the heating temperature, and the crystallized sodium formate that has reached the saturation solubility at the cooling temperature and is crystallized with de-airing air and steam is subjected to formic acid by filtration means. It is designed to be taken out as soda crystal.
[0019]
According to the above method, sodium sulfate and sodium formate, which are the main components in the waste liquid discharged from the manufacturing process of the printed wiring board, can be easily and efficiently removed from the waste liquid, and the sodium sulfate and sodium formate removed from the waste liquid are It is economical because it can be reused separately, and since the inside of the concentration tank is washed before performing the concentration treatment, the heating of the waste liquid is not hindered by the crystals attached to the inner surface. Evaporation can be performed efficiently.
[0020]
Also, when filtering the crystals by the filtering means while removing the concentrated liquid, the crystals heat the filtering means and the surrounding pipes to prevent the temperature from dropping due to the removal of liquid. And the wastewater discharged by the chemical copper plating treatment and the wastewater discharged by the electrodialysis treatment can be processed simultaneously by the same processing equipment. As a result, the equipment can be greatly reduced.
[0021]
In order to achieve the above object, the waste liquid treatment method of the present invention, when cleaning the concentration tank, first supply water into the concentration tank, wash with water, then supply steam, and heat while heating with steam. By washing, crystals solidified on the inner surface of the concentration tank are washed.
[0022]
According to the above method, even a crystal firmly attached to the inner surface of the concentration tank can be easily and reliably removed.
[0023]
In order to achieve the above object, a waste liquid treatment method according to the present invention includes a bypass pipe provided with a bypass valve in the middle thereof in parallel with a filtration unit.
[0024]
According to the above method, after the concentration process is completed, the bypass valve is opened, and the concentrated solution before the component (sodium formate) in the concentrated solution in the pipe reaches the saturation dissolution temperature is received at a stroke via the bypass tube to receive the final concentrated solution. By discharging to the tank, it is possible to prevent clogging of the filtration means and the surrounding piping with crystals.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment in which the waste liquid treatment method of the present invention is applied to waste liquid discharged in a manufacturing process of manufacturing a printed wiring board will be described in detail with reference to the drawings.
[0026]
FIG. 1 shows a configuration diagram of a waste liquid treatment apparatus, which is provided with a chemical copper plating waste liquid tank 1 for storing a chemical copper plating waste liquid generated in a chemical copper plating treatment step, and a dialysis waste liquid tank 12. The tank 1 is connected to a copper recovery tank 3 via a pump 2, and the dialysis waste liquid tank 12 is connected to a filtrate neutralization tank 10 via a pump 13.
[0027]
The copper recovery tank 3 is connected with a pump 4 for circulating waste liquid in the tank via a copper recovery filter 5 and sending the waste liquid to an EDTA crystallization tank 6. A stirrer 6a for stirring the waste liquid is provided, and a pump 7 for circulating the waste liquid in the tank and sending it to the EDTA filter 8 is connected.
[0028]
Note that a filter (not shown) to which a catalyst for precipitating copper ions is attached is provided in the copper recovery and filtration machine 5.
[0029]
The EDTA filter 8 is provided with a roll-shaped filter medium 8a for filtering the EDTA crystals C solid-liquid separated in the EDTA crystallization tank 6 from the waste liquid and discharging the EDTA crystals C to the EDTA receiving tank 9. The neutralized waste liquid D from which the EDTA crystals C have been removed by 8 is sent to the filtrate neutralization tank 10 and mixed with the dialysis waste liquid B.
[0030]
In addition, the neutralization waste liquid D does not necessarily need to be mixed with the dialysis waste liquid B, and may be stored separately in separate tanks.
[0031]
The filtrate neutralization tank 10 is connected to a concentration tank 15 via a pump 14 and a neutralization waste liquid valve 40, and the waste liquid in the concentration tank 15 is passed through a concentrated liquid discharge manual valve 16 which is opened or closed manually or automatically. The liquid is dropped on the crystal filter 17.
[0032]
A water supply pipe 24 provided with a water supply valve 23 in the middle thereof and a steam supply pipe 26 provided with a steam valve 25 in the middle thereof are connected to the concentration tank 15, and supplied from the water supply pipe 24 and the steam supply pipe 26. The crystals solidified and solidified on the inner surface of the concentration tank 15 can be washed by the water and steam.
[0033]
An air supply pipe 29 provided with a dewatering air valve 28 in the middle of the conduit 27 provided with the concentrated liquid discharging manual valve 16 below the concentrated liquid discharging manual valve 16, A steam supply pipe 31 provided with a steam valve 30 is connected so that the crystal filter 17 can be drained by air and steam supplied from the air supply pipe 29 and the steam supply pipe 31.
[0034]
The crystal filter 17 is provided with a roll-shaped filter medium 17a for filtering the crystal F of sodium sulfate (component 1) and the crystal G of sodium formate (component 2) from the waste liquid, and is filtered by the filter medium 17a. The crystals F and G are collected in the crystal receiving tank 18, and the waste liquid from which the components 1 and 2 have been removed by the crystal filtering device 17 is collected in the final concentrated liquid receiving tank 19 and is sent to the crystal filtering device 17 on the way. A bypass pipe 33 provided with a bypass valve 32 is provided in parallel. By opening the bypass valve 32, the waste liquid in the concentration tank 15 is directly passed through the final concentrated liquid receiving tank without passing through the crystal filter 17. It is also possible to discharge to 19 at a stretch.
[0035]
A pump 20 is connected to the final concentrated liquid receiving tank 19, the waste liquid in the tank is circulated through the concentration tank 15 and the circulation path 22, and the water in the waste liquid is evaporated and discharged through the exhaust port 21. It is configured to be further concentrated by being discharged to the atmosphere, and the concentrated waste liquid is stored in the final concentrated liquid receiving tank 19 as the final concentrated liquid H.
[0036]
In FIG. 1, reference numeral 35 denotes a chemical copper plating tank constituting the chemical copper plating apparatus, 36 denotes a dialysate receiving tank, 37 denotes an electrodialyzer, and 38 denotes a dialysis waste liquid receiving tank. The chemical copper plating waste liquid is sent to the chemical copper plating waste liquid tank 1, and the dialysis waste liquid in the dialysis waste liquid receiving tank 38 is sent to the dialysis waste liquid tank 12.
[0037]
Next, a method for treating waste liquid discharged in the manufacturing process of a printed wiring board using the waste liquid treatment apparatus having the above-described configuration will be described.
[0038]
The chemical copper plating solution used in the manufacturing process of the printed wiring board becomes a chemical copper plating waste solution A in which sodium sulfate and sodium formate have accumulated after use. The dialysis waste liquid B generated in the electrodialysis device 37 for regenerating the accumulated chemical copper plating waste liquid into a usable state again is stored in the dialysis waste liquid tank 12.
[0039]
Next, the chemical copper plating waste liquid A is supplied from the chemical copper plating waste liquid tank 1 to the copper recovery tank 3 by the pump 2. In the copper recovery tank 3, the chemical copper plating waste liquid A is cooled from 50 ° C. to 70 ° C. required for the plating deposition reaction. After heating in the range, a reducing agent (formalin) and a ph adjustor (caustic soda) are added in an amount required for a chemical copper plating deposition reaction (2 mol of formalin and 4 mol of caustic soda per mol of copper), and copper is pumped by The chemical copper plating waste liquid A in the recovery tank 3 is circulated again to the copper recovery tank 3 via the copper recovery filter 5 so that copper ions in the chemical copper plating waste liquid are precipitated as metallic copper on the copper recovery filter 5. Then, the copper ions in the waste liquid A are recovered by the copper recovery filter 5.
[0040]
Next, the chemical copper plating waste liquid A after the recovery of the copper ions is sent to the EDTA crystallization tank 6, and the EDTA crystallization tank 6 is stirred by the stirrer 6 a and crystallized at 30 ° C. or lower to crystallize the EDTA crystal C. While cooling the mixture, a pH adjuster (sulfuric acid) is added to lower the pH to 2 or less.
[0041]
Then, the waste liquid A is sent to the EDTA filter 8, and the solid-liquid separated EDT crystal C is filtered by the filter medium 8a, collected in the EDTA receiving tank 9, and the waste liquid A that has passed through the filter medium 8a is filtered into the filtrate neutralization tank. The dialysis waste liquid B generated by the dialysis treatment is also stored in the filtrate neutralization tank 10 as the neutralization waste liquid D.
[0042]
The concentration of the neutralized waste liquid D stored in the filtrate neutralization tank 10 is, for example, 50 m ² 25 μm of copper effluent after precipitation of copper, and about 45 g of sodium sulfate was contained in a waste liquid obtained by mixing the copper ion and the neutralized waste liquid D “1” after EDTA recovery at a ratio of dialysis waste liquid “3”. / L and sodium formate contain about 35 g / L. As shown in FIG. 2, while the solubility of sodium sulfate is almost constant at 35 ° C. or higher, sodium formate has a property of increasing with increasing temperature.
[0043]
In the present invention, sodium sulfate and sodium formate are taken out of the waste liquid by utilizing this property. In the evaporative concentration treatment, first, the water supply valve 23 of the water supply pipe 24 is opened and the inside of the concentration tank 15 is filled with water. After washing, the steam valve 25 is opened while the water supply valve 23 is opened, and water and steam are continuously supplied to the concentration tank 15, whereby the inside of the concentration tank 15 is subjected to steam washing at 100 ° C. for 30 minutes. The crystals solidified on the inner surface of the concentration tank 15 in the previous treatment are washed.
[0044]
This prevents the heating of the waste liquid from being hindered by the solidified crystals adhered to the inner surface of the concentration tank 15, so that the water in the waste liquid can be efficiently evaporated and at the same time, the amount of water evaporation is prevented from decreasing. The heating in the concentration tank 15 does not depend on steam, but an electric heater or the like may be used.
[0045]
After the inside of the concentration tank 15 is steam-cleaned for a certain period of time, the water supply valve 23 is closed, the neutralization waste liquid valve 40 is opened, and the neutralization waste liquid D stored in the filtrate neutralization tank 10 is removed by the pump 14. And the final concentrated liquid H in the final concentrated liquid receiving tank 19 is also continuously supplied to the concentrated tank 15 by the pump 20, and the inside of the concentrated tank 15 is heated to 120 ° C. by steam to neutralize. The water in the waste liquid D is evaporated.
[0046]
At this time, in order to prevent clogging of the crystal filter 17 and the surrounding pipes due to crystals generated due to a rapid increase in the sodium formate concentration of the final concentrated liquid H, the supply amount of the neutralized waste liquid D was reduced. From the value obtained by subtracting the amount of water evaporated in the concentration tank 15, the supply amounts of the neutralization waste liquid D and the final concentrated liquid H are adjusted so that the supply amount of the neutralization waste liquid D is increased by about 10%. The concentrated liquid that has become excessive due to the increase in the amount is caused to overflow from the overflow pipe 22 to the final concentrated liquid receiving tank 19.
[0047]
As shown in FIG. 2, since sodium sulfate has a lower solubility in water than sodium formate, heating the concentration tank 15 to 120 ° C. first causes the sodium sulfate contained in the concentrate E to have a saturation solubility of 290 g. / L, and crystallization is started.
[0048]
Thereafter, when the concentration tank 15 is further heated to evaporate the water in the concentrated solution E, the sodium formate contained in the concentrated solution E reaches the saturated solubility at a heating temperature of 120 ° C. of the concentrated tank 15. The surrounding piping excluding the superheated portion, the crystal filter 17 and the surrounding piping are affected by the outside air temperature, and excessive sodium formate is precipitated in the concentrated liquid flowing in the piping. Clogging occurs, making it difficult to continue processing.
[0049]
In order to prevent this, the water content of the concentrated solution E is evaporated to just before reaching the saturated solubility of sodium formate at 1910 g / L at a holding temperature of 100 ° C. in the next processing step, that is, the final work step, for example, to a sodium formate concentration of 1900 g / L. To form a state in which only sodium sulfate is crystallized (note that the sodium formate concentration of the neutralized waste liquid D and the final concentrated liquid H, the total capacity of the concentration tank 15 and the final concentrated liquid receiving tank 19, and the supply to the concentration tank 15) Calculate and manage the concentration of sodium formate based on the amount of waste liquid and the amount of water evaporation.)
[0050]
The concentrated liquid E in which sodium sulfate is crystallized is dropped on the crystal filter 17 by opening and closing the concentrated liquid discharging manual valve 16 for a predetermined time (1-2 seconds), and then the liquid vapor valve 30 and The concentrated liquid E is filtered by the crystal filter 17 while the liquid is removed by opening the air valve 28 for liquid removal for a predetermined time (10 to 30 seconds) and supplying steam and air to the crystal filter 17.
[0051]
By passing the concentrate E through the crystal filter 17, the sodium sulfate crystals F that cannot be completely dissolved in the concentrate E are taken out by the filter medium 17a and collected in the crystal receiving tank 18, and the concentrate E that has passed through the filter medium 17a is removed. The concentrated liquid H is discharged to the final concentrated liquid receiving tank 19 and the filtration treatment is repeated, whereby the sodium sulfate crystal F that cannot be completely dissolved in the concentrated liquid E is repeatedly collected.
[0052]
At this time, steam is supplied into the crystal filter 17 and the piping so that crystal clogging does not occur in the crystal filter 17 and the surrounding pipes due to the temperature drop due to the liquid removal, and the sodium formate crystal is formed. The filtration operation is performed while maintaining a temperature (about 100 ° C. or higher) at which no excessive precipitation occurs.
[0053]
On the other hand, when the evaporative concentration processing is completed, the concentrated liquid E in the concentration tank 15 is discharged to the final concentrated liquid receiving tank 19, but the concentrated liquid E in the concentrated tank 15 immediately after the completion of the evaporative concentration processing is the concentrated liquid E and sodium sulfate. The heating temperature is lower than 120 ° C. due to the mixed state of the crystals, and the temperature is maintained at 100 ° C. so that the sodium formate does not reach the saturation solubility due to the temperature drop, and the crystal filter is kept for a certain time (60 to 90 minutes). The sodium sulfate crystals in the concentrated solution E are discharged to the final concentrated solution receiving tank 19 while being filtered using 17.
[0054]
After a certain period of time has elapsed, the bypass valve 32 of the bypass pipe 33 is opened, and the concentrated solution E is immediately blown into the final concentrated solution receiving tank 19 before the concentrated solution E is cooled to a temperature at which the sodium formate saturation solubility is reached. Discharge.
[0055]
Next, the final concentrated H containing 1550 g / L sodium formate is cooled to recover sodium formate. As shown in the sodium sulfate saturation solubility curve of FIG. 2, sodium sulfate starts crystallization at 35 ° C. or lower. Therefore, the concentrated solution E is cooled to 35 ° C. to 60 ° C., for example, 50 ° C., but the saturated solubility of sodium formate at 50 ° C. is 1210 g / L, so that 340 g / L sodium formate is finally concentrated. It cannot be completely dissolved in the liquid H and crystallizes.
[0056]
After the final concentrate H in which the sodium formate is crystallized is circulated to the concentration tank 15 by the pump 20, the concentrate discharge manual valve 16 is opened for a certain time (1 to 2 seconds). The concentrated liquid H is dropped into the crystal filter 17, and thereafter, the vapor valve 30 for dewatering and the air valve 28 for dewatering are opened for a predetermined time (10 to 30 seconds) to supply steam and air into the crystal filter 17. Then, a filtration treatment is performed while removing the liquid.
[0057]
When the final concentrate H passes through the filter medium 17a of the crystal filter 17, the sodium formate crystal G that cannot be completely dissolved in the final concentrate H is filtered by the filter medium 17a, collected in the crystal receiving tank 18, and passed through the filter medium 17a. The final concentrated liquid H is discharged again to the final concentrated liquid receiving tank 19, and the filtration treatment is repeated to collect all the sodium formate crystals G that cannot be completely dissolved in the final concentrated liquid H. In the case of crystal filtration, since the temperature drop during the treatment is small (about 10 ° C.), clogging due to excessive crystallization does not occur. However, when the temperature falls to 35 ° C. or less, the crystal filter 17, the piping and the concentration tank 15 are affected by the temperature drop. During the filtration, the temperature is maintained in the range of 35 ° C. to 60 ° C., since sodium sulfate may precipitate excessive crystals and cause clogging, which may make the filtration impossible.
[0058]
In the above embodiment, the chemical copper plating solution A discharged in the chemical copper plating step and the dialysis waste liquid B discharged in the electrodialysis treatment are collected in the filtrate neutralization tank 10, and the sulfuric acid is removed from the waste liquids A and B. Although soda and sodium formate are taken out, the wastewater treatment may be performed in a separate step without mixing the chemical copper plating waste liquid A and the dialysis waste liquid B.
[0059]
Although the recovery of sodium formate is performed after the manufacturing process of the printed wiring board, when the concentration of the concentrated solution E in the final concentrated solution receiving tank 19 reaches a predetermined concentration, the concentrated solution E is cooled to, for example, 50 ° C. Of course, it is also possible to recover the sodium formate by cooling.
[0060]
Further, in the above-described embodiment, the case where sodium sulfate and sodium formate are taken out from the waste liquid discharged in the manufacturing process of the printed wiring board has been described. However, even if the temperature is increased, the component 1 whose solubility in water is almost constant is increased. It can be applied to waste liquid treatment in which component 1 and component 2 are taken out of a waste liquid containing component 2 having higher solubility in water than component 1 and having a higher solubility in water with increasing temperature. is there.
[0061]
【The invention's effect】
Since the present invention has been described in detail above, components 1 and 2, which are the main components in the waste liquid discharged from the manufacturing process, can be easily and efficiently extracted from the waste liquid, and the components extracted from the waste liquid. Since the component 1 and the component 2 can be separately reused, it is economical. In addition, since the inside of the concentration tank is washed before performing the evaporative concentration treatment, the waste liquid is heated by the crystals attached to the inner surface. Since it is not hindered, the evaporation of moisture can be performed efficiently, and when the crystals are filtered by the filtration means while the concentrated liquid is being removed, the filtration means and the piping around the filtration means are heated by the steam to reduce the temperature drop due to the removal. In order to prevent this, there is no fear of clogging of the crystal filter and the piping around it due to the crystals.
[0062]
Further, when treating the waste liquid discharged in the manufacturing process of the printed wiring board, sodium sulfate and formate, which are the main components in the waste liquid, can be easily and efficiently taken out from the waste liquid, and the sodium sulfate taken out from the waste liquid And sodium formate are economical because they can be reused separately, and low cost because large-scale biochemical treatment equipment for removing sodium formate from wastewater and many dedicated personnel for operating the same are not required. Enables waste liquid treatment.
[0063]
Furthermore, the waste liquid discharged by the chemical copper plating treatment and the waste liquid discharged by the electrodialysis treatment can be simultaneously processed by the same processing apparatus. In addition to greatly reducing costs, when cleaning the concentration tank, first supply water into the concentration tank, wash with water, then supply steam, and wash with steam while heating with steam. By washing the solidified crystals adhered to the inner surface of the enrichment tank, even the crystals firmly adhered to the inner surface of the concentration tank can be easily and reliably removed, and a bypass pipe provided with a bypass valve on the way is provided. If provided in parallel with the filtration means, after the concentration process is completed, the bypass valve is opened, and the concentrated solution before the component (sodium formate) in the concentrated solution in the pipeline reaches the saturated dissolution temperature is bypassed. It is possible to discharge once the final concentrate receiving tank through, can be piping of the filtration unit and its surrounding to prevent from clogging by crystallization.
[Brief description of the drawings]
FIG.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a waste liquid treatment apparatus that performs a waste liquid treatment method of the present invention.
FIG. 2
FIG. 3 is a diagram showing the solubility of sodium sulfate and sodium formate in water in the waste liquid for performing the waste liquid treatment method of the present invention.
FIG. 3
FIG. 5 is a process chart showing a manufacturing process of the printed wiring board.
FIG. 4
It is explanatory drawing which shows the manufacturing process of a printed wiring board.
[Explanation of symbols]
1 Chemical copper plating waste liquid tank
3 Copper recovery tank
5 Copper recovery filtration machine
6 EDTA crystallization tank
8 EDTA filter
9 EDTA receiving tank
10 Filtrate neutralization tank
12 Dialysis waste liquid tank
15 Thickening tank
16 Condensate discharge manual valve
17 Crystal filter (filtration means)
18 Crystal receiving tank
19 Final concentrate receiving tank
21 Exhaust port
24 Water pipe
26 Steam supply pipe
29 Air supply pipe
31 Steam supply pipe
32 Bypass valve
33 Bypass pipe

Claims

A method for treating a waste liquid discharged from a manufacturing process, wherein the solubility in water is constant even when the temperature is increased, and the solubility in water is higher than that of the component 1. In conducting the concentration treatment by heating the waste liquid containing the component 2 whose solubility increases as a main component to a high temperature in the concentration tank and evaporating the water in the waste liquid, first, the crystals attached to the inner surface of the concentration tank are washed. After that, the waste liquid is supplied to the concentration tank and heated in the concentration tank, whereby the crystals having the saturation solubility or higher in the component 1 which reaches the saturation solubility first are removed by the liquid and air for liquid removal while removing the liquid. The component 2 contained in the waste liquid is cooled before reaching the saturation solubility at the heating temperature, and then cooled to the saturation solubility at the cooling temperature, and the component 2 crystallized at the cooling temperature is removed by filtration means. And do not drain with steam. Wastewater treatment method characterized by taking out as crystals by al filtration means.

A method for treating a waste liquid discharged from a manufacturing process of a printed wiring board or the like, in which the solubility in water is constant even when the temperature is increased, and the solubility in water is higher than that of the sodium sulfate. When the waste liquid mainly composed of sodium formate, whose solubility in water increases as the temperature rises, is heated to a high temperature in the concentration tank to perform the evaporative concentration treatment, first, the crystals attached to the inner surface of the concentration tank are washed, and then concentrated. By supplying the waste liquid to the tank and evaporating the water in the waste liquid, first, the crystals having a saturation solubility or higher in the sodium sulfate that reaches the saturation solubility are filtered by means of dewatering with air and steam for dewatering. It is taken out as sodium sulfate crystals, and then cooled before the sodium formate contained in the waste liquid reaches the saturation solubility at the heating temperature, and the sodium formate crystallized after reaching the saturation solubility at the cooling temperature is dewatered. Wastewater treatment method characterized by retrieving a formic acid sodium crystals and filtering means with dewatered by steam.

A method for treating waste liquid discharged from the manufacturing process of printed wiring boards and the like, wherein sodium sulfate has a constant solubility in water even when the temperature is increased, and sodium formate has a solubility in water that increases with increasing temperature. Mixing the waste liquid after recovering copper ions and EDTA contained in the chemical copper plating waste liquid containing as a main component, and the waste liquid generated by the electrodialysis treatment of the chemical copper plating liquid, and heating to high temperature in the concentration tank In carrying out the evaporative concentration treatment, the crystals adhered to the inner surface of the concentration tank are first washed, and then the waste liquid is supplied to the concentration tank to evaporate the water in the waste liquid. The crystals having a solubility equal to or higher than the saturation solubility in the soda are taken out as sodium sulfate crystals by a filtration means while being dewatered with dewatering air and steam, and then the sodium formate contained in the waste liquid is saturated at the heating temperature. A waste liquid characterized in that it is cooled before reaching the solubility, and the sodium formate that has reached the saturation solubility at the cooling temperature and crystallized is taken out as sodium formate crystal by a filtration means while being dewatered with air and steam for dewatering. Processing method.

In cleaning the inside of the concentration tank, first, water is supplied into the concentration tank and washed with water, and then steam is supplied, and steam washing is performed while heating with the steam, so that crystals adhered and solidified on the inner surface of the concentration tank are washed. The waste liquid treatment method according to any one of claims 1 to 3, which is washed.

The waste liquid treatment method according to any one of claims 1 to 4, wherein a bypass pipe provided with a bypass valve on the way is provided in parallel with the filtering means.