JP4024106B2

JP4024106B2 - Waste liquid treatment method

Info

Publication number: JP4024106B2
Application number: JP2002230206A
Authority: JP
Inventors: 哲米竹; 潤一伊藤; 治幸今泉; 賢史七海; 哲郎菊地
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: 2007-12-19
Anticipated expiration: 2022-08-07
Also published as: JP2004066130A

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】
ＣｕＳＯ₄＋４ＮａＯＨ＋２ＨＣＨＯ→Ｃｕ＋Ｎａ₂ＳＯ４＋２ＮａＣＯＯＨ＋Ｈ₂＋２Ｈ₂Ｏ
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廃液処理方法において、前記濃縮槽内の廃液を前記濾過手段を通さずに直接排出するように当該濾過手段と並列にバイパス管を設け、前記成分１の結晶を、一定時間濾過し当該一定時間経過後取り出し、その後、前記廃液に含まれる前記成分２を主成分とする廃液が飽和溶解度に達する温度に冷却される前に、当該バイパス管に設けられたバイパスバルブを開放して前記濃縮槽内の廃液を排出することによって、前記成分２の析出による前記濾過手段の目詰まりを防止する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蒸発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廃液処理方法において、前記濃縮槽内の廃液を前記濾過手段を通さずに直接排出するように当該濾過手段と並列にバイパス管を設け、前記硫酸ソーダ結晶を、一定時間濾過し当該一定時間経過したら取り出し、その後、前記廃液に含まれる前記ギ酸ソーダが飽和溶解度に達する温度に冷却される前に、当該バイパス管に設けられたバイパスバルブを開放して前記濃縮槽内の廃液を排出することによって、前記ギ酸ソーダの析出による前記濾過手段の目詰まりを防止する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蒸発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前記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廃液処理方法において、前記濃縮槽内の廃液を前記濾過手段を通さずに直接排出するように当該濾過手段と並列にバイパス管を設け、前記硫酸ソーダ結晶を、一定時間濾過し当該一定時間経過したら取り出し、その後、前記廃液に含まれる前記ギ酸ソーダが飽和溶解度に達する温度に冷却される前に、当該バイパス管に設けられたバイパスバルブを開放して前記濃縮槽内の廃液を排出することによって、前記ギ酸ソーダの析出による前記濾過手段の目詰まりを防止する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。
【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５０ｍ² 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
６ＥＤＴＡ晶析槽
８ＥＤＴＡ濾過機
９ＥＤＴＡ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]
BACKGROUND 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]
Conventional printed wiring boards used for electronic devices and the like are manufactured, for example, through the manufacturing steps shown in FIGS.
[0003]
First, in the material preparation step shown in FIG. 4, a printed wiring board a shown in FIG.
[0004]
In the printed wiring a, a copper foil layer c is formed in advance on one side or both sides of the base material b ((b) in FIG. 4 shows both sides). In the process, as shown in FIG. 4B, a through hole d is formed at a place where an electronic component or the like is mounted.
[0005]
Then, after the catalyst e is attached to the inner peripheral surface of the through hole d in the catalyst application step as shown in FIG. 4C, the copper foil layer c is etched in the circuit formation step, and the copper foil layer A circuit f is formed in c.
[0006]
The printed wiring board a on which the circuit f is formed by the circuit forming process is subjected to copper plating in the chemical copper plating process. At this time, copper ions are precipitated as metallic copper by a precipitation reaction, and at the same time, sulfuric acid is added to the plating solution. Soda and sodium oxalate are precipitated 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
Further, as shown in FIG. 4E, the printed wiring board a in which the copper plating g is applied to the inner surface of the through hole d and the circuit f by the chemical copper plating process is performed in the next solder resist process, as shown in FIG. The solder resist h is formed on the front and back surfaces of the base material b as shown in FIG. 5), and the finished printed wiring board a is unloaded from the manufacturing process.
[0008]
On the other hand, the waste liquid generated in the chemical copper plating process is regenerated using an electrodialyzer in order to regenerate it into a reusable state, and copper ions from the waste liquid generated by the chemical copper plating process and the electrodialysis process. As an apparatus for recovering the EDTA component, for example, a “copper recovery apparatus” described in JP-A-6-170117 and an “EDTA recovery apparatus” described in JP-A-6-246157 are known. .
[0009]
[Problems to be solved by the invention]
However, the copper recovery device and the EDTA recovery device disclosed in the above publication can recover copper ions and EDTA components, but sodium sulfate and sodium formate accumulated in the waste liquid are reaction products. Can not be recovered.
[0010]
In particular, when sodium formate is discharged into rivers, etc. as general wastewater without being collected, it is necessary to discharge COD (chemical oxygen demand) below the water quality standard by biochemical treatment, but biochemical treatment Has a large processing facility and a large number of full-time staff to operate the facility.
[0011]
The present invention was made to solve such conventional problems, and waste liquid treatment that can easily and efficiently take out components such as sodium sulfate and sodium formate from waste liquid generated in the manufacturing process of printed wiring boards 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 according to the present invention is a method for treating waste liquid discharged from a production process, comprising: Component 1 having a constant solubility in water even when the temperature is raised; In addition, the waste liquid mainly composed of the component 2 whose solubility in water is high and the solubility in water increases as the temperature rises is heated to a high temperature in a concentration tank to evaporate the water in the waste liquid, thereby performing a concentration treatment. First, after washing the crystals adhering 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 filtration means while dewatering with dewatering air and steam, then cooled before the component 2 contained in the waste liquid reaches the saturation solubility at the heating temperature, and reaches the saturation solubility at the cooling temperature. The crystallized component 2 is In a waste liquid treatment method for removing crystals as liquid by a filtration means while removing the liquid air and steam, a bypass pipe is provided in parallel with the filtration means so that the waste liquid in the concentration tank is directly discharged without passing through the filtration means. , crystals of the component 1, taken out after filtration certain time the fixed time, after that, before the waste liquid mainly containing components 2 contained in the waste liquid is cooled to a temperature reaches the saturation solubility, the The clogging of the filtering means due to the precipitation of the component 2 is prevented by opening a bypass valve provided in the bypass pipe and discharging the waste liquid in the concentration tank.
[0013]
By the above method, the main component 1 and component 2 in the waste liquid discharged from the production process can be easily and efficiently extracted from the waste liquid, and the component 1 and component 2 taken out from the waste liquid can be separated and reused separately. Since it can be used, it is economical, and since the inside of the concentration tank is cleaned before the concentration treatment, heating of the waste liquid is not hindered by crystals adhering to the inner surface. Evaporation can be performed efficiently.
[0014]
In addition, when the crystals are filtered by the filtering means while removing the concentrated liquid, the filtering means and the surrounding piping are heated by the steam to prevent temperature drop due to the draining, so the filtering means and piping are clogged by the crystals. There is no worry about waking up.
[0015]
In order to achieve the above object, a method for treating waste liquid according to the present invention is a method for treating waste liquid discharged from a manufacturing process of a printed wiring board or the like, wherein sodium sulfate has a constant solubility in water even when the temperature is raised. When the waste liquid mainly composed of sodium formate whose solubility in water is higher than that of sodium sulfate and the solubility in water increases as the temperature rises is heated to a high temperature in a concentration tank, After washing the crystals adhering to the inner surface of the concentration tank, by supplying the waste liquid to the concentration tank and evaporating the water in the waste liquid, firstly, crystals that exceed the saturation solubility in sodium sulfate that reach saturation solubility, It is taken out as sodium sulfate crystals by filtration means while dewatering with dewatering air and steam, then cooled before the sodium formate contained in the waste liquid reaches the saturation solubility at the heating temperature, and saturated solubility at the cooling temperature In a waste liquid treatment method in which sodium formate that has reached and crystallized is taken out as sodium formate crystals by filtration means while being drained by degassing air and steam, the waste liquid in the concentration tank is directly discharged without passing through the filtration means. in the bypass pipe is provided in parallel with the filtering means as, the sodium sulfate crystals are filtered fixed time extraction after the lapse the fixed time, after that, the formic acid soda contained in the waste liquid is cooled to a temperature reaching saturation solubility Before opening the bypass valve provided in the bypass pipe and discharging the waste liquid in the concentration tank to prevent clogging of the filtering means due to precipitation of sodium formate. .
[0016]
According to the above method, sodium sulfate and sodium formate, which are 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. Since it can be reused separately, it is economical, and since the inside of the concentration tank is cleaned before the concentration treatment, heating of the waste liquid is not hindered by crystals adhering to the inner surface. Can be efficiently evaporated.
[0017]
In addition, when the crystals are filtered by the filtering means while removing the concentrated liquid, the filtering means and the surrounding piping are heated by the steam to prevent temperature drop due to the draining, so the filtering means and piping are clogged by the crystals. In addition, there is no need for a large-scale biochemical processing apparatus for extracting sodium formate from the waste liquid and a large number of full-time personnel for operating it, so that the waste liquid can be processed at a low cost.
[0018]
In order to achieve the above object, a method for treating waste liquid according to the present invention is a method for treating waste liquid discharged from a manufacturing process of a printed wiring board or the like, wherein sodium sulfate has a constant solubility in water even when the temperature is raised. It is caused by electrodialysis treatment of the waste liquid after recovering the copper ions and EDTA contained in the chemical copper plating waste liquid mainly composed of sodium formate whose solubility in water increases with increasing temperature. When evaporating and concentrating by mixing the waste liquid and heating it to a high temperature in the concentration tank, first wash the crystals adhering to the inner surface of the concentration tank, then supply the waste liquid to the concentration tank and remove the moisture in the waste liquid. By first evaporating the crystal above the saturated solubility in the sodium sulfate that reaches the saturation solubility, it is taken out as sodium sulfate crystals by filtration means while being dehydrated with dewatering air and steam, The sodium formate contained in the waste liquid is cooled before reaching the saturation solubility at the heating temperature, and the formic acid soda that has reached the saturation solubility at the cooling temperature and crystallized is filtered while being removed by the liquid and steam for liquid removal. In the waste liquid treatment method for taking out as sodium formate crystals by the above, a bypass pipe is provided in parallel with the filtration means so that the waste liquid in the concentration tank is directly discharged without passing through the filtration means, and the sodium sulfate crystals are filtered for a certain period of time. and then taken out, its after the lapse the fixed time, before the formic acid soda contained in the waste liquid is cooled to a temperature reaches the saturation solubility, in the inside condensation tank by opening a bypass valve provided in the bypass pipe By discharging the waste liquid, clogging of the filtering means due to precipitation of the sodium formate is prevented.
[0019]
By the above method, sodium sulfate and sodium formate, which are 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 are Since it can be reused separately, it is economical, and since the inside of the concentration tank is cleaned before the concentration treatment, heating of the waste liquid is not hindered by crystals adhering to the inner surface. Evaporation can be performed efficiently.
[0020]
In addition, when the crystals are filtered by the filtering means while removing the concentrated liquid, the filtering means and the surrounding piping are heated by the steam to prevent temperature drop due to the draining, so the filtering means and piping are clogged by the crystals. In addition, the waste liquid discharged by the chemical copper plating process and the waste liquid discharged by the electrodialysis process can be processed at the same time using the same processing equipment, so compared to the case where these waste liquids are processed by separate processing equipment. Therefore, the equipment can be greatly reduced.
[0025]
DETAILED DESCRIPTION OF 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 includes a chemical copper plating waste liquid tank 1 for storing chemical copper plating waste liquid generated in a chemical copper plating treatment process, and a dialysis waste liquid tank 12. The tank 1 is connected to the copper recovery tank 3 via the pump 2, and the dialysis waste liquid tank 12 is connected to the filtrate neutralization tank 10 via the pump 13.
[0027]
The copper recovery tank 3 is connected to a pump 4 that circulates the waste liquid in the tank through the copper recovery filter 5 and sends it to the EDTA crystallization tank 6. A stirrer 6 a 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]
In the copper recovery filter 5, a filter (not shown) to which a catalyst for depositing copper ions is attached is provided.
[0029]
The EDTA filter 8 is provided with a roll-shaped filter medium 8a for filtering the EDTA crystal C solid-liquid separated in the EDTA crystallization tank 6 from the waste liquid and discharging it to the EDTA receiving tank 9. The EDTA filter 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]
The neutralized waste liquid D does not necessarily have to be mixed with the dialysis waste liquid B, and may of course be stored separately in separate tanks.
[0031]
The filtrate neutralization tank 10 is connected to the concentration tank 15 via the pump 14 and the neutralization waste liquid valve 40, and the waste liquid in the concentration tank 15 is connected to the concentrate discharge manual valve 16 that is manually or automatically opened and closed. Then, it is dropped into the crystal filter 17.
[0032]
A water supply pipe 24 provided with a water supply valve 23 in the middle and a steam supply pipe 26 provided with a steam valve 25 in the middle are connected to the concentration tank 15, and supplied from the water supply pipe 24 and the steam supply pipe 26. Crystals adhered and solidified on the inner surface of the concentration tank 15 can be washed with water and steam.
[0033]
Further, below the concentrate discharge manual valve 16 in the conduit 27 provided with the concentrate discharge manual valve 16, an air supply pipe 29 provided with a liquid discharge air valve 28 in the middle and a liquid discharge in the middle. A steam supply pipe 31 provided with a steam valve 30 is connected, and 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 crystals F of sodium sulfate (component 1) and the crystals G of sodium formate (component 2) from the waste liquid. The crystals F and G are recovered in the crystal receiving tank 18, and the waste liquid from which the components 1 and 2 are removed by the crystal filter 17 is recovered in the final concentrated liquid receiving tank 19. A bypass pipe 33 provided with a bypass valve 32 is provided in parallel, and 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 possible to discharge to 19 at once.
[0035]
A pump 20 is connected to the final concentrate receiving tank 19, waste liquid in the tank is circulated through the concentration tank 15 and the circulation path 22, and water in the waste liquid is evaporated through the exhaust port 21. The concentrated waste liquid is further concentrated by being discharged into the atmosphere, and the concentrated waste liquid is stored as a final concentrated liquid H in the final concentrated liquid receiving tank 19.
[0036]
In FIG. 1, 35 is a chemical copper plating tank constituting the chemical copper plating apparatus, 36 is a dialysate receiving tank, 37 is an electrodialyzer, 38 is a dialysate waste liquid receiving tank, and the chemical copper plating tank 35 is a waste liquid. 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 the waste liquid discharged in the manufacturing process of the printed wiring board using the above-configured waste liquid treatment apparatus will be described.
[0038]
The chemical copper plating solution used in the printed wiring board manufacturing process becomes the chemical copper plating waste solution A in which sodium sulfate and sodium formate are accumulated after use. The dialysis waste liquid B generated in the electrodialysis apparatus 37 that regenerates the chemical copper plating waste liquid accumulated in the above is stored in the dialysis waste liquid tank 12.
[0039]
Next, when 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, the chemical copper plating waste liquid A is supplied to the copper recovery tank 3 from 50 ° C. to 70 ° C. required for the plating deposition reaction. After adding the amount of reductant (formalin) and ph adjusting material (caustic soda) necessary for the chemical copper plating precipitation reaction, 2 mol of formalin and 4 mol of caustic soda are added to the copper, and the pump 4 is used to add copper. By circulating the chemical copper plating waste liquid A in the recovery tank 3 to the copper recovery tank 3 again through the copper recovery filter 5, the copper ions in the chemical copper plating waste liquid are deposited as metallic copper in the copper recovery filter 5. 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 recovering the copper ions is sent to the EDTA crystallization tank 6, and in the EDTA crystallization tank 6, the EDTA crystal C is crystallized. Add pH adjuster (sulfuric acid) while cooling to pH 2 or lower.
[0041]
Then, the waste liquid A is sent to the EDTA filter 8, and the EDT crystals C separated into solid and liquid are filtered by the filter medium 8a and collected in the EDTA receiving tank 9, and the waste liquid A liquid that has passed through the filter medium 8a is added to the filtrate neutralization tank. 10 is stored as neutralization waste liquid D, and the dialysis waste liquid B generated by dialysis is also stored in the filtrate neutralization tank 10 as neutralization waste liquid D.
[0042]
The concentration of the neutralized waste liquid D stored in the filtrate neutralization tank 10 is, for example, a waste liquid after copper deposition of 25 μm with respect to a printed circuit board area of 50 m ² , and the neutralized waste liquid D “1” after recovery of the copper ions and EDTA. In the waste liquid mixed at a ratio of dialysis waste liquid “3” to sodium sulfate, sodium sulfate contains about 45 g / L and sodium formate contains about 35 g / L. As shown in FIG. 2, the solubility of sodium sulfate is While it is almost constant at 35 ° C. or higher, sodium formate has the property of increasing with increasing temperature.
[0043]
In the present invention, this property is used to take out sodium sulfate and sodium formate from the waste liquid. In the evaporative concentration process, first, the water supply valve 23 of the water supply pipe 24 is opened and the concentration tank 15 is filled with water. Next, the steam valve 25 is opened while the water supply valve 23 is opened, and water and steam are continuously supplied to the concentrating tank 15 so that the inside of the concentrating tank 15 is steam-cleaned at 100 ° C. for 30 minutes. The crystals that have adhered and solidified on the inner surface of the concentration tank 15 in the previous treatment are washed.
[0044]
As a result, heating of the waste liquid is not hindered by the crystals solidified on 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 water evaporation amount is prevented from decreasing. The heating in the concentration tank 15 may use an electric heater or the like without using steam.
[0045]
When the inside of the concentration tank 15 is steam-cleaned for a certain time, the neutralization waste liquid valve 40 is opened after closing the water supply valve 23, and the neutralization waste liquid D stored in the filtrate neutralization tank 10 is condensed by the pump 14 to the concentration tank 15. 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. with steam and neutralized. The water in the waste liquid D is evaporated.
[0046]
At this time, the supply amount of the neutralized waste liquid D is prevented in order to prevent the crystal filter 17 and the surrounding pipes from being clogged by crystals generated because the sodium formate concentration of the final concentrated liquid H increases rapidly. 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 increases by about 10%. The concentrated liquid surplus due to the increase in the amount of the liquid overflows 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, by heating the concentration tank 15 to 120 ° C., the sodium sulfate contained in the concentrate E first has a saturation solubility of 290 g. / L is reached and crystallization begins.
[0048]
Thereafter, when the concentration tank 15 is further heated to evaporate the water in the concentrated liquid E, sodium formate contained in the concentrated liquid E reaches the saturation solubility at a heating temperature of 120 ° C. of the concentrated tank 15. Since the surrounding piping excluding the overheated part, the crystal filter 17 and the surrounding piping are affected by the outside air temperature, sodium formate is excessively precipitated in the concentrated liquid flowing in the pipe. Clogging occurs, making it difficult to continue processing.
[0049]
In order to prevent this, the water content of the concentrate E is evaporated immediately before reaching the saturated solubility of sodium formate at 1910 g / L at the holding temperature of 100 ° C. in the end processing step, which is the next processing step, for example, to a sodium formate concentration of 1900 g / L. Thus, only sodium sulfate is crystallized (note that the concentration of sodium formate in the neutralized waste liquid D and the final concentrated liquid H, the total capacity of the concentrated tank 15 and the final concentrated liquid receiving tank 19, and the supply to the concentrated tank 15) The concentration of sodium formate is calculated and managed based on the amount of waste liquid and the amount of water evaporated.)
[0050]
Then, the concentrate E in which the sodium sulfate is crystallized is dropped into the crystal filter 17 by opening and closing the concentrate discharge manual valve 16 for a certain time (1 to 2 seconds). The concentrated liquid E is filtered by the crystal filter 17 while the liquid valve 28 is opened for a certain time (10 to 30 seconds) and the liquid is supplied by 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 The final concentrated liquid H is discharged into the final concentrated liquid receiving tank 19 and the filtration process is repeated, so that the sodium sulfate crystals F that cannot be completely dissolved in the concentrated liquid E are repeatedly collected.
[0052]
At this time, steam is supplied into the crystal filter 17 and the pipes so that the crystal filter 17 and the surrounding pipes are not clogged due to the temperature drop due to liquid removal. The filtration operation is performed while maintaining a temperature at which excessive precipitation does not occur (about 100 ° C. or higher).
[0053]
On the other hand, when the evaporative concentration process is completed, the concentrated liquid E in the concentrated tank 15 is discharged to the final concentrated liquid receiving tank 19, and the concentrated liquid E in the concentrated tank 15 immediately after the completion of the evaporated concentrated process is the concentrated liquid E and sodium sulfate. The crystal temperature is lower than the heating temperature of 120 ° C. due to the mixed state of the crystals, and maintained at 100 ° C. so that the sodium formate does not reach the saturation solubility due to the temperature drop, and for a certain time (60 to 90 minutes) 17, the sodium sulfate crystals in the concentrate E are filtered and discharged to the final concentrate receiver 19.
[0054]
Then, after a certain time has elapsed, the bypass valve 32 of the bypass pipe 33 is opened, and the concentrated solution E is immediately poured into the final concentrated solution receiving tank 19 before the concentrated solution E is cooled to a temperature at which it reaches the saturated solubility of sodium formate. Discharge.
[0055]
Next, the final concentrated H containing 1550 g / L sodium formate is cooled and sodium formate is recovered. As shown in the saturated solubility curve of sodium sulfate in FIG. 2, sodium sulfate starts to crystallize at 35 ° C. or lower. Therefore, the concentrated liquid E is cooled to 35 ° C. to 60 ° C., for example, to 50 ° C., but since the saturated solubility of sodium formate at 50 ° C. is 1210 g / L, 340 g / L sodium formate is finally concentrated. It cannot be dissolved in liquid H and crystallizes.
[0056]
After the final concentrated liquid H in which sodium formate is crystallized is circulated to the concentration tank 15 by the pump 20, the concentrated liquid discharge manual valve 16 is opened for a predetermined time (1 to 2 seconds), and the final concentration in the concentration tank 15 is reached. Concentrated liquid H is dropped into the crystal filter 17, and then the dewatering steam valve 30 and the dewatering air valve 28 are opened for a predetermined time (10 to 30 seconds) to supply steam and air into the crystal filter 17. Then, a filtration process is performed while removing the liquid.
[0057]
When the final concentrated liquid H passes through the filter medium 17a of the crystal filter 17, the sodium formate crystal G that cannot be dissolved in the final concentrated liquid H is filtered by the filter medium 17a and collected in the crystal receiving tank 18, and passes through the filter medium 17a. The final concentrated liquid H is discharged again into the final concentrated liquid receiving tank 19, and the filtration process is repeated to recover all the formic acid soda crystals G that cannot be completely dissolved in the final concentrated liquid H. Crystal filtration has a small temperature drop during processing (about 10 ° C.), so clogging due to excessive crystallization does not occur. However, when the temperature is 35 ° C. or less, the crystal filter 17, the piping and the concentration tank 15 are affected by the temperature drop. Since sodium sulfate precipitates excessively to cause clogging and the filtration process may be impossible, the temperature is maintained in the range of 35 ° C. to 60 ° C. during the filtration process.
[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 sulfuric acid is recovered from these waste liquids A and B. Of course, soda and sodium formate are taken out, but the chemical copper plating waste liquid A and the dialysis waste liquid B may not be mixed and the waste liquid may be treated in a separate process.
[0059]
Further, the recovery of sodium formate is performed after the printed wiring board manufacturing process is completed. When the concentration of the concentrate E in the final concentrate receiver 19 reaches a predetermined concentration, the concentrate E is brought to, for example, 50 ° C. Of course, the formate soda may be recovered by cooling.
[0060]
Furthermore, 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, the component 1 has a substantially constant solubility in water even when the temperature is increased. It can be applied to all waste liquid treatments in which component 1 and component 2 are extracted from waste liquid mainly composed of component 2, which has higher solubility in water than component 1 and whose solubility in water increases with increasing temperature. is there.
[0061]
【The invention's effect】
Since the present invention has been described in detail above, the main component 1 and component 2 in the waste liquid discharged from the production process can be easily and efficiently extracted from the waste liquid, and the components extracted from the waste liquid Since 1 and component 2 can be reused separately, it is economical and the inside of the concentration tank is washed before evaporative concentration treatment, so that the waste liquid is heated by crystals adhering to the inner surface. Since it is not hindered, water can be efficiently evaporated, and when the crystals are filtered by the filtering means while removing the concentrated liquid, the filtering means and the surrounding piping are heated by the steam to reduce the temperature due to the liquid removal. In order to prevent this, there is no concern that the crystal filter or the surrounding piping will be clogged by the crystals.
[0062]
In addition, when processing the waste liquid discharged in the printed wiring board manufacturing process, sodium sulfate and sodium formate, which are the main components in the waste liquid, can be easily and efficiently removed from the waste liquid, and the sodium sulfate removed from the waste liquid. And sodium formate is economical because it can be reused separately, and it does not require large-scale biochemical processing equipment to remove sodium formate from the waste liquid and many dedicated personnel to operate it. It is possible to treat waste liquid.
[0063]
Furthermore, the waste liquid discharged by the chemical copper plating process and the waste liquid discharged by the electrodialysis process can be processed at the same time with the same processing equipment. Therefore, compared with the case where these waste liquids are processed with separate processing equipment, In addition to greatly reducing costs, the concentration tank is cleaned by first supplying water into the concentration tank, cleaning with water, then supplying steam, and steam cleaning while heating with steam. By washing the crystals that have adhered and solidified on the inner surface, it is possible to easily and reliably remove even the crystals that have firmly adhered to the inner surface of the concentration tank, and a bypass pipe provided with a bypass valve is provided on the way. If it is provided in parallel with the filtration means, the bypass valve is opened after the concentration process is completed, and the concentrate before the component (sodium formate) in the concentrate reaches the saturation 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. 1 is a configuration diagram of a waste liquid treatment apparatus for carrying out a waste liquid treatment method of the present invention.
FIG. 2 is a diagram showing the solubility in water of sodium sulfate and sodium formate in waste liquid for carrying out the waste liquid treatment method of the present invention.
FIG. 3 is a process diagram showing manufacturing steps of the printed wiring board.
FIG. 4 is an explanatory view showing a manufacturing process of a printed wiring board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Chemical copper plating waste liquid tank 3 Copper collection tank 5 Copper collection filtration machine 6 EDTA crystallization tank 8 EDTA filtration machine 9 EDTA receiving tank 10 Filtrate neutralization tank 12 Dialysis waste liquid tank 15 Concentration tank 16 Concentrate discharge manual valve 17 Crystal filter (Filtering means)
18 Crystal receiving tank 19 Final concentrate receiving tank 21 Exhaust port 24 Water supply 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 production process, wherein the solubility in water is constant even when the temperature is increased, and the solubility in water is higher than that of Component 1, and the solubility in water is increased as the temperature increases. In the concentration process by heating the waste liquid containing component 2 whose solubility is increased as a main component to a high temperature in the concentration tank and evaporating the water in the waste liquid, the crystals attached to the inner surface of the concentration tank are first washed. After that, the waste liquid is supplied to the concentration tank and heated in the concentration tank, so that the crystals having the saturation solubility or higher in the component 1 that first reach the saturation solubility are discharged with the liquid and steam for liquid removal. It is taken out as crystals by a filtering means, and then cooled before the component 2 contained in the waste liquid reaches the saturation solubility at the heating temperature, and the component 2 that has reached the saturation solubility at the cooling temperature and crystallized is removed from the liquid And do not drain with steam. In waste water treatment method for taking out the crystals et filtration means,
Wherein the waste liquid in the concentrating tank bypass pipe provided in parallel with the filtering means so as to discharge directly without passing through the filtering means, the crystals of the component 1, taking out After elapse the predetermined time filtering certain time, after the Before the waste liquid containing the component 2 contained in the waste liquid as a main component is cooled to a temperature at which saturation solubility is reached, the bypass valve provided in the bypass pipe is opened to discharge the waste liquid in the concentration tank. In this way, the clogging of the filtering means due to the precipitation of the component 2 is prevented.

A method for treating waste liquid discharged from a manufacturing process such as a printed wiring board, wherein the solubility in water is constant even when the temperature is increased, and the solubility in water is higher than that in the sodium sulfate, and the temperature When the waste liquid mainly composed of sodium formate, whose solubility in water rises as it rises, is heated to a high temperature in the concentration tank and subjected to evaporation concentration treatment, first the crystals adhering 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, crystals that exceed the saturated solubility in sodium sulfate that reach the saturation solubility are filtered by the filtration means while removing the crystals with the liquid and steam for liquid removal. Then, the sodium formate contained in the waste liquid is cooled before reaching the saturation solubility at the heating temperature, and the sodium formate crystallized after reaching the saturation solubility at the cooling temperature is dehydrated empty. And in waste water treatment method for taking out as formic acid soda crystals deliquor while filtering means by the steam,
Wherein the waste liquid in the concentrating tank bypass pipe provided in parallel with the filtering means so as to discharge directly without passing through the filtering means, the sodium sulfate crystals, extraction After filtering a predetermined time elapses the predetermined time, after them, Before the sodium formate contained in the waste liquid is cooled to a temperature at which saturation solubility is reached, the bypass valve provided in the bypass pipe is opened to discharge the waste liquid in the concentration tank. A waste liquid treatment method characterized by preventing clogging of the filtering means due to precipitation.

A method for treating waste liquid discharged from the manufacturing process of printed wiring boards, etc., in which sodium sulfate has a constant solubility in water even when the temperature is increased, and sodium formate whose solubility in water 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 electrodialysis of the chemical copper plating liquid, and heating to high temperature in the concentration tank When evaporating and concentrating, the crystals attached to the inner surface of the concentration tank are washed first, and then the waste liquid is supplied to the concentration tank to evaporate the water in the waste liquid. Crystals with saturation solubility or higher in the soda are taken out as sodium sulfate crystals by filtration means while being dehydrated with dewatering air and steam, and then the sodium formate contained in the waste liquid is saturated at the heating temperature. Cooled before reaching the Kaido, formic acid soda crystallized reached saturation solubility at the cooling temperature, the wastewater treatment method for taking out as formic acid soda crystals deliquor while filtering means by draining air and steam,
Wherein the waste liquid in the concentrating tank bypass pipe provided in parallel with the filtering means so as to discharge directly without passing through the filtering means, the sodium sulfate crystals, extraction After filtering a predetermined time elapses the predetermined time, after them, Before the sodium formate contained in the waste liquid is cooled to a temperature at which saturation solubility is reached, the bypass valve provided in the bypass pipe is opened to discharge the waste liquid in the concentration tank. A waste liquid treatment method characterized by preventing clogging of the filtering means due to precipitation.