JP6597349B2 - Blast furnace wastewater treatment method - Google Patents

Blast furnace wastewater treatment method Download PDF

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JP6597349B2
JP6597349B2 JP2016018242A JP2016018242A JP6597349B2 JP 6597349 B2 JP6597349 B2 JP 6597349B2 JP 2016018242 A JP2016018242 A JP 2016018242A JP 2016018242 A JP2016018242 A JP 2016018242A JP 6597349 B2 JP6597349 B2 JP 6597349B2
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智大 石森
実 渡辺
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Kurita Water Industries Ltd
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本発明は、高炉集塵水などの高炉排水の処理方法及び処理装置に関するものであり、詳しくは、高炉排水中の遊離シアンのみならず、鉄シアノ錯体等の各種のシアノ錯体をも効率的に凝集沈澱処理することができる高炉排水の処理方法に関する。   The present invention relates to a method and an apparatus for treating blast furnace wastewater such as blast furnace dust collection water, and more specifically, not only free cyanide in blast furnace wastewater but also various cyano complexes such as iron cyano complexes are efficiently treated. The present invention relates to a method for treating blast furnace waste water that can be subjected to coagulation sedimentation treatment.

銑鉄製造に用いられる高炉から排出されるガス(高炉ガス)は、多量の粉塵と炉内での反応により生じた各種反応ガスを含むことから、湿式集塵器を通して除塵した後、有用なガスをガスホルダーに回収して再利用する方式が一般に採用されている。   The gas discharged from the blast furnace used for pig iron production (blast furnace gas) contains a large amount of dust and various reaction gases generated by the reaction in the furnace. A method of collecting and reusing in a gas holder is generally adopted.

湿式集塵器で除塵に用いられた水、すなわち高炉集塵水には、鉄鉱石、コークス及び石灰石などの製銑原料に由来する微粉(ダスト)やカルシウム、鉄、亜鉛及びマグネシウムなどの塩類が溶解・懸濁している。   The water used for dust removal in wet dust collectors, that is, blast furnace dust collection water, contains fine powder (dust) derived from ironmaking raw materials such as iron ore, coke and limestone, and salts such as calcium, iron, zinc and magnesium. Dissolved and suspended.

高炉集塵水に含まれる溶解・懸濁物のうち、水に溶解しないダストについては、凝集剤添加により凝集処理され、シックナーなどの沈殿槽で沈殿除去されることが多い。また、水に溶解している塩類については、高炉集塵水のpHをアルカリ性に調整して水酸化物として析出させ、ダストと共に凝集沈殿処理されることがある。通常、このような凝集沈殿処理水は、その一部又は全部がガス洗浄水として湿式集塵器に循環されるが、高炉集塵水中には、休風時および炉内温度が大きく変化する際等に、ガス中にシアンが発生してこれが水中に取り込まれ、シアン含有水となる。   Of the dissolved / suspended material contained in the blast furnace dust collection water, the dust that does not dissolve in water is often agglomerated by adding a flocculant and is removed by precipitation in a precipitation tank such as a thickener. Moreover, about the salt which melt | dissolves in water, pH of blast furnace dust collection water may be adjusted to alkalinity, and it may precipitate as a hydroxide, and may be coagulated and settled with dust. Usually, a part or all of such coagulated sediment-treated water is circulated to the wet dust collector as gas cleaning water. For example, cyan is generated in the gas and is taken into the water to become cyan-containing water.

高炉排水や、化学工場、メッキ工場、コークス製造工場、金属表面処理工場等から排出されるシアン含有廃水の処理方法としては、アルカリ塩素法や全シアン処理法が行われている。   As a method for treating cyanogen-containing wastewater discharged from blast furnace effluent, chemical factories, plating factories, coke factories, metal surface treatment factories, etc., an alkali chlorine method or a total cyanide treatment method is performed.

アルカリ塩素法では、シアンにアルカリ及び遊離塩素を反応させることにより酸化分解する。この方法は、遊離シアン主体の廃水の処理には有効であるが、鉄シアノ錯体のような難分解性のシアノ錯体については処理することができない。また、2段階に分けてpHと酸化還元電位を設定値に調整する必要があり、水質管理、薬注管理が煩雑である。   In the alkali chlorine method, cyanide is oxidized and decomposed by reacting alkali with free chlorine. This method is effective for the treatment of waste water mainly composed of free cyanide, but cannot treat a hardly decomposable cyano complex such as an iron cyano complex. Moreover, it is necessary to adjust pH and oxidation-reduction potential to set values in two stages, and water quality management and chemical injection management are complicated.

全シアン法(還元銅塩法)では、還元剤の存在下に銅塩を添加して、各種シアン化合物との難溶性塩を析出させて沈殿分離する(特許文献1)。特許文献1には、沈澱分離工程に先立って高分子凝集剤を添加することが記載されている(第3頁右上欄)。実際の全シアン法では、高分子凝集剤の他に無機凝集剤として鉄系凝集剤を添加することが行われている。   In the all-cyan method (reduced copper salt method), a copper salt is added in the presence of a reducing agent to precipitate a hardly soluble salt with various cyan compounds and precipitate and separate (Patent Document 1). Patent Document 1 describes that a polymer flocculant is added prior to the precipitation separation step (upper right column on page 3). In an actual all-cyan method, an iron-based flocculant is added as an inorganic flocculant in addition to a polymer flocculant.

特開昭63−39693号公報JP 63-39693 A

本発明は、全シアン法において、無機凝集剤として鉄系凝集剤を用いた場合よりも効率的に沈澱分離処理を行うことができる高炉排水の処理方法を提供することを課題とする。   It is an object of the present invention to provide a blast furnace wastewater treatment method capable of performing a precipitation separation process more efficiently than in the case of using an iron-based flocculant as an inorganic flocculant in the all cyan method.

本発明者らは、上記課題を解決すべく鋭意検討を重ねた結果、高炉排水を全シアン法により処理する方法において、無機凝集剤としてアルミ系凝集剤を添加することにより、鉄系凝集剤を用いた場合よりも効果的にシアンを除去できることを見出した。   As a result of intensive investigations to solve the above problems, the present inventors have added an iron-based flocculant by adding an aluminum-based flocculant as an inorganic flocculant in a method of treating blast furnace wastewater by the all-cyan method. It has been found that cyan can be removed more effectively than when it is used.

本発明はこのような知見に基いて達成されたものであり、以下を要旨とする。   The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] シアンを含有する高炉排水に銅化合物及び還元剤を添加して、シアンの難溶性塩を生成させる難溶性塩生成工程と、該難溶性塩生成工程からの液に凝集剤を添加してシアンの難溶性塩を凝集させて分離する凝集分離工程とを有する高炉排水の処理方法において、該凝集剤としてアルミ系凝集剤を添加することを特徴とする高炉排水の処理方法。 [1] Adding a copper compound and a reducing agent to blast furnace effluent containing cyan to produce a hardly soluble salt of cyan, and adding a flocculant to the liquid from the hardly soluble salt producing step A blast furnace wastewater treatment method comprising aggregating and separating a flocculating and separating step of aggregating a hardly soluble salt of cyanide, wherein an aluminum-based flocculant is added as the flocculant.

[2] [1]において、前記アルミ系凝集剤がPAC及び/又は硫酸バンドであることを特徴とする高炉排水の処理方法。 [2] A method for treating blast furnace waste water according to [1], wherein the aluminum-based flocculant is PAC and / or a sulfuric acid band.

[3] [1]又は[2]において、前記銅塩及び還元剤を添加する反応槽内の液のORPが80mV以下であることを特徴とする高炉排水の処理方法。 [3] A method for treating blast furnace waste water according to [1] or [2], wherein the ORP of the liquid in the reaction vessel to which the copper salt and the reducing agent are added is 80 mV or less.

[4] [1]ないし[3]のいずれかにおいて、前記凝集剤を添加する凝集反応槽内の液のpHが7.0〜9.0であることを特徴とする高炉排水の処理方法。 [4] The method for treating blast furnace waste water according to any one of [1] to [3], wherein the pH of the liquid in the aggregation reaction tank to which the flocculant is added is 7.0 to 9.0.

高炉排水を全シアン処理法により処理する方法において、その凝集処理工程で、鉄系凝集剤ではなくアルミ系凝集剤を添加することにより、凝集処理効果が向上する。この理由としては次のことが考えられる。   In the method of treating blast furnace wastewater by the all-cyan treatment method, the coagulation treatment effect is improved by adding an aluminum coagulant instead of the iron coagulant in the coagulation treatment step. The reason is considered as follows.

高炉排水には、シアンと錯体を形成する有機酸が混在することが多い。有機酸としてはグルコン酸、クエン酸、酒石酸、マロン酸などである。これらが存在すると凝集効果が悪化して、シアン除去率が悪化する。   Blast furnace wastewater often contains organic acids that form complexes with cyanide. Organic acids include gluconic acid, citric acid, tartaric acid, malonic acid and the like. If these are present, the aggregation effect is deteriorated and the cyan removal rate is deteriorated.

銅塩および還元剤と無機凝集剤として塩化第二鉄を併用する場合、有機酸が存在するとCuCNおよび水酸化第二鉄の沈殿物の形成が阻害され凝集効果が悪化する。無機凝集剤としてアルミ系凝集剤を使用すると、錯体が形成されにくくなり、CuCNの沈殿が良好に行われる。   In the case where ferric chloride is used in combination as a copper salt and a reducing agent and an inorganic flocculant, the presence of an organic acid inhibits the formation of a precipitate of CuCN and ferric hydroxide, thereby deteriorating the agglomeration effect. When an aluminum-based flocculant is used as the inorganic flocculant, it is difficult to form a complex and CuCN is favorably precipitated.

また、ORPおよびpHを適正に管理することで安定した効果的な運転管理が可能となる。   In addition, stable and effective operation management can be performed by appropriately managing the ORP and pH.

本発明のシアン含有水の処理方法を示す系統図である。It is a systematic diagram which shows the processing method of the cyan containing water of this invention.

以下に本発明の実施の形態を詳細に説明する。   Hereinafter, embodiments of the present invention will be described in detail.

[処理対象排水]
本発明で処理対象とする高炉排水としては、前述の高炉集塵水が挙げられる。
[Treatment wastewater]
Examples of the blast furnace wastewater to be treated in the present invention include the above-mentioned blast furnace dust collection water.

高炉集塵水は、製鉄所の高炉ガスの湿式集塵器においてガス洗浄に用いられた高炉ガス洗浄排水である。通常、この高炉集塵水は、凝集沈殿処理された後、その一部又は全部がガス洗浄水として湿式集塵器に循環される。高炉集塵水中には、休風時および炉内温度が大きく変化する際等に、ガス中にシアンが発生し、集塵水中に取り込まれるため、遊離シアン、Fe、Zn等の金属のシアノ錯体が、全シアン濃度として、0.1〜100mg/L程度含有されている。   Blast furnace dust collection water is blast furnace gas cleaning wastewater used for gas cleaning in a blast furnace gas wet dust collector at an ironworks. Usually, after this blast furnace dust collection water is coagulated and precipitated, a part or all of it is circulated as a gas cleaning water to a wet dust collector. In the blast furnace dust collection water, cyanide is generated in the gas when the wind is resting or when the temperature in the furnace changes greatly, and is taken into the dust collection water. Therefore, metal cyanogen complexes such as free cyanide, Fe, Zn, etc. However, the total cyan density is about 0.1 to 100 mg / L.

[難溶性塩の生成工程]
本発明では、上記シアン含有水にまず2価の銅塩及び還元剤を添加して難溶性塩を生成させる。銅塩としては、水溶性の硫酸銅(II)、塩化銅(II)、硝酸銅(II)などの2価の銅塩が利用可能である。
[Producing process of sparingly soluble salt]
In the present invention, a divalent copper salt and a reducing agent are first added to the cyan-containing water to form a hardly soluble salt. As the copper salt, divalent copper salts such as water-soluble copper (II) sulfate, copper (II) chloride, and copper (II) nitrate can be used.

還元剤は2価の銅イオンを1価に還元できる還元剤であり、例えば亜硫酸塩、重亜硫酸塩、鉄塩(II)、ヒドラジンなどいずれでもよいが、汚泥発生量の低減及び入手の容易性の点から亜硫酸塩、重亜硫酸塩が推奨される。これらの塩としてはナトリウム塩が好適である。   The reducing agent is a reducing agent capable of reducing divalent copper ions to monovalent, and may be any of sulfites, bisulfites, iron salts (II), hydrazine, etc., but the amount of sludge generated is reduced and the availability is easy. From this point, sulfite and bisulfite are recommended. As these salts, sodium salts are preferred.

一般に硫酸銅などの2価の銅塩に亜硫酸塩、重亜硫酸塩、硫酸鉄(II)、ヒドラジンなどの各種還元剤を添加してpH2〜11としても、見かけ上1価の銅イオンの生成は見られないが、シアン含有水に2価の銅塩と還元剤を添加すると、1価の銅のシアン化合物が難溶性塩となって沈殿する。   Generally, even when various reducing agents such as sulfite, bisulfite, iron (II) sulfate, hydrazine are added to divalent copper salts such as copper sulfate to adjust the pH to 2 to 11, apparently monovalent copper ions are produced. Although not seen, when a divalent copper salt and a reducing agent are added to cyanide-containing water, a monovalent copper cyanide compound precipitates as a hardly soluble salt.

上記の反応は下式に示す3種類に代表される。   The above reaction is represented by the following three types.

Cu+CN→CuCN …(1)
4Cu+Zn(CN) 2−→4CuCN+Zn2+ …(2)
Cu+Ag(CN) →CuAg(CN) …(3)
このうち(1)式は遊離シアンの反応、(2)式は前記易分解性のシアン錯塩の反応、(3)式は難分解性のシアン錯塩の反応である。
Cu + + CN → CuCN (1)
4Cu + + Zn (CN) 4 2− → 4CuCN + Zn 2+ (2)
Cu + + Ag (CN) 2 → CuAg (CN) 2 (3)
Among these, the formula (1) is a reaction of free cyan, the formula (2) is a reaction of the above easily decomposable cyan complex, and the formula (3) is a reaction of a hardly decomposable cyan complex.

反応系に添加する2価の銅塩の量は、好ましくは廃水中のシアンとの反応当量以上であり、原則的には上記(1)〜(3)式における反応当量でよいが、廃水中のシアン濃度の変動に対処するため、ならびに反応促進のためには廃水中のシアン濃度の2〜5倍量が特に好ましい。   The amount of the divalent copper salt added to the reaction system is preferably not less than the reaction equivalent with cyanide in the wastewater, and in principle, the reaction equivalent in the above formulas (1) to (3) may be used. 2 to 5 times the cyan concentration in the waste water is particularly preferable for coping with fluctuations in the cyan concentration and for promoting the reaction.

還元剤の量は2価の銅イオンを1価に還元するための理論量及び溶存酸素等によって消費される量の合計量又はそれ以上である。銅塩及び還元剤がすでに廃水中に存在する場合は不足分を添加すればよい。銅塩及び還元剤を添加する場合は同時に添加するのが好ましいが、前後に別けて別々に添加してもよい。   The amount of the reducing agent is the total amount of the theoretical amount for reducing divalent copper ions to monovalent and the amount consumed by dissolved oxygen or the like, or more. If the copper salt and reducing agent are already present in the wastewater, the deficiency may be added. When adding a copper salt and a reducing agent, it is preferable to add them simultaneously, but they may be added separately before and after.

シアン含有水に銅塩及び還元剤を添加して第1銅シアン化合物を生成させるためのpH(銅塩及び還元剤を添加する反応槽のpH)は好ましくは2〜9.5特に好ましくは7〜9.5である。また、銅塩及び還元剤を添加する反応槽のORPは好ましくは80mV以下、例えば50〜80mVである。   The pH for adding a copper salt and a reducing agent to cyanide-containing water to form a cuprous cyanide compound (pH of the reaction vessel in which the copper salt and the reducing agent are added) is preferably 2 to 9.5, particularly preferably 7 ~ 9.5. Moreover, ORP of the reaction tank to which the copper salt and the reducing agent are added is preferably 80 mV or less, for example, 50 to 80 mV.

[凝集及び固液分離工程]
本発明においては、このようにシアン含有水に銅塩及び還元剤を添加して難溶性塩を生成させた後、凝集剤を添加し、凝集処理する。
[Agglomeration and solid-liquid separation process]
In the present invention, after adding a copper salt and a reducing agent to cyan-containing water to form a hardly soluble salt, a flocculant is added and agglomeration treatment is performed.

本発明では、この凝集処理を行うために、無機凝集剤としてアルミ系凝集剤を添加する。アルミ系凝集剤としては、ポリ塩化アルミ(PAC)、硫酸バンドなどが好適であり、特にPACが好適である。   In the present invention, an aluminum flocculant is added as an inorganic flocculant in order to perform this flocculant treatment. As the aluminum flocculant, polyaluminum chloride (PAC), sulfuric acid band and the like are preferable, and PAC is particularly preferable.

アルミ系凝集剤の添加濃度は20〜2000mg/L特に100〜500mg/L程度が好ましい。また、アルミ系凝集剤と共に、又はアルミ系凝集剤添加後に有機高分子凝集剤を添加することが好ましい。有機高分子凝集剤としては、アニオン系高分子凝集剤が好ましく、その添加量は0.2〜10mg/L特に0.5〜2mg/L程度が好ましい。   The addition concentration of the aluminum-based flocculant is preferably about 20 to 2000 mg / L, particularly about 100 to 500 mg / L. Further, it is preferable to add the organic polymer flocculant together with the aluminum flocculant or after the addition of the aluminum flocculant. As the organic polymer flocculant, an anionic polymer flocculant is preferable, and the addition amount is preferably about 0.2 to 10 mg / L, particularly about 0.5 to 2 mg / L.

凝集剤が添加される凝集反応槽内の液のpHは7.0〜9.0特に7.0〜8.5程度が好ましく、必要に応じ硫酸、苛性ソーダなどによりpH調整を行うことが好ましい。   The pH of the liquid in the coagulation reaction tank to which the coagulant is added is preferably about 7.0 to 9.0, particularly about 7.0 to 8.5, and it is preferable to adjust the pH with sulfuric acid, caustic soda, or the like as necessary.

なお、過剰に添加された銅を除去するために、凝集処理時に重金属捕集剤を添加してもよい。重金属捕集剤としてはジチオカルバミン酸系キレート剤などが挙げられる。   In order to remove excess copper, a heavy metal scavenger may be added during the agglomeration treatment. Examples of heavy metal scavengers include dithiocarbamic acid chelating agents.

凝集処理後の固液分離としては、沈澱分離、浮上分離、濾過の1又は2以上が挙げられる。濾過としては、砂濾過、多層濾過(アンスラサイト・砂二層濾過など)、膜濾過などを用いることができる。   Examples of the solid-liquid separation after the agglomeration treatment include one or more of precipitation separation, floating separation, and filtration. As filtration, sand filtration, multilayer filtration (anthracite / sand double-layer filtration, etc.), membrane filtration, etc. can be used.

図1は、上記の一連の工程を行う排水処理装置の一例を示すものである。高炉排水は、反応槽1に導入され、還元剤及び銅塩が添加され、撹拌機1aによって撹拌混合された後、凝集反応槽2に導入され、アルミ系凝集剤が添加され、撹拌機2aによって撹拌された後、移流管3を介して凝集沈澱槽4に導入され、凝集沈澱処理される。なお、凝集反応槽2内又は移流管3にて高分子凝集剤が添加される。   FIG. 1 shows an example of a wastewater treatment apparatus that performs the above-described series of steps. The blast furnace wastewater is introduced into the reaction tank 1, the reducing agent and the copper salt are added, and after stirring and mixing by the stirrer 1a, it is introduced into the agglomeration reaction tank 2, and the aluminum-based flocculant is added, and the stirrer 2a. After being stirred, it is introduced into the coagulation sedimentation tank 4 through the advection tube 3 and coagulation sedimentation treatment is performed. A polymer flocculant is added in the agglomeration reaction tank 2 or in the advection tube 3.

凝集沈澱槽4の上澄水は、砂濾過、多層濾過(アンスラサイト・砂二層濾過など)、膜濾過などの濾過器5で濾過され、処理水として取り出される。   The supernatant water of the coagulation sedimentation tank 4 is filtered by a filter 5 such as sand filtration, multilayer filtration (anthracite / sand bilayer filtration, etc.), membrane filtration, etc., and taken out as treated water.

なお、反応槽1にORP計を設け、ORPを測定することが好ましい。また、凝集反応槽2にpH計を設置し、検出されるpHが所定範囲となるようにpH調整を行うことが好ましい。   In addition, it is preferable to provide an ORP meter in the reaction tank 1 and measure the ORP. Moreover, it is preferable to install a pH meter in the aggregation reaction tank 2 and adjust the pH so that the detected pH falls within a predetermined range.

以下、本発明の実施例及び比較例について説明する。   Examples of the present invention and comparative examples will be described below.

以下の実施例及び比較例で処理対象とした被処理水は、製鉄所の高炉集塵水(pH8.5、濁度50度、シアン:1.8mg/L、T−Cu:0.3mg/L以下、ORP120mV)である。実施例で添加した還元剤は重亜硫酸ナトリウム、銅化合物は硫酸銅である。無機凝集剤は実施例ではPAC又は硫酸バンド(AlをAlとして10重量%含有)、比較例では塩化第二鉄又はポリ硫酸第二鉄、有機高分子凝集剤はアニオン系高分子凝集剤(栗田工業株式会社製クリファームPA923)、重金属捕集剤はジチオカルバミン酸塩系化合物(栗田工業株式会社製ウェルクリンK)、pH調整剤は水酸化ナトリウム又は硫酸である。 The water to be treated in the following Examples and Comparative Examples was blast furnace dust collection water (pH 8.5, turbidity 50 degrees, cyan: 1.8 mg / L, T-Cu: 0.3 mg / L or less, ORP120 mV). The reducing agent added in the examples is sodium bisulfite, and the copper compound is copper sulfate. In the examples, the inorganic flocculant is PAC or sulfuric acid band (containing 10% by weight of Al as Al 2 O 3 ), in the comparative example, ferric chloride or polyferric sulfate, and the organic polymer flocculant is anionic polymer flocculant. The agent (Kurita Industry Co., Ltd. Kuri Farm PA923), the heavy metal scavenger is a dithiocarbamate-based compound (Kurita Industry Co., Ltd. Wellclin K), and the pH adjuster is sodium hydroxide or sulfuric acid.

[実施例1〜7、比較例1〜7]
図1の装置(ただし濾過器5は省略)において、被処理水を反応槽1に導入し、銅化合物と還元剤を添加し、攪拌機1aで攪拌混合して反応させた。反応液を凝集槽2へ移送し、無機凝集剤及び重金属捕集剤を添加し、攪拌機2aで攪拌して凝集反応を行った。凝集槽2の凝集反応液を凝集沈殿槽4へ移送する過程で、有機高分子凝集剤を添加し、フロックを凝集沈殿槽4で分離した。処理水水質等を表1に示す。
[Examples 1-7, Comparative Examples 1-7]
In the apparatus of FIG. 1 (the filter 5 is omitted), water to be treated was introduced into the reaction tank 1, a copper compound and a reducing agent were added, and the mixture was stirred and mixed with a stirrer 1a to be reacted. The reaction liquid was transferred to the agglomeration tank 2, an inorganic flocculant and a heavy metal scavenger were added, and the agglomeration reaction was carried out by stirring with the stirrer 2a. In the process of transferring the aggregation reaction liquid in the aggregation tank 2 to the aggregation precipitation tank 4, an organic polymer flocculant was added, and the floc was separated in the aggregation precipitation tank 4. Table 1 shows the quality of treated water.

Figure 0006597349
Figure 0006597349

Figure 0006597349
Figure 0006597349

Figure 0006597349
Figure 0006597349

[考察]
表1に示す実施例1,2は、無機凝集剤としてPACを添加し、実施例3は硫酸バンドを添加したものである。比較例1,2は、塩化第二鉄、比較例3はポリ硫酸第二鉄を添加したものである。
[Discussion]
In Examples 1 and 2 shown in Table 1, PAC was added as an inorganic flocculant, and in Example 3, a sulfuric acid band was added. In Comparative Examples 1 and 2, ferric chloride is added, and in Comparative Example 3 polyferric sulfate is added.

表1の通り、無機凝集剤としては、アルミ系凝集剤が好適であり、PACが硫酸バンドよりやや好適である。塩化第二鉄及びポリ硫酸第二鉄はシアン除去効果が劣る。   As shown in Table 1, an aluminum flocculant is suitable as the inorganic flocculant, and PAC is slightly more suitable than the sulfuric acid band. Ferric chloride and polyferric sulfate are inferior in cyan removal effect.

表2は、被処理水のpHを硫酸又は苛性ソーダの添加によって変えたこと以外は実施例1と同様とした実験結果を示している。表2の通り、被処理水のpHは7.0〜8.5が好適である。pHが低くなるとCN除去効果はよいが、硫酸使用量が多くなり処理水のCuもやや高くなる。pHが高いと、シアン除去効果が低下する。   Table 2 shows experimental results similar to those in Example 1 except that the pH of the water to be treated was changed by adding sulfuric acid or caustic soda. As shown in Table 2, the pH of the water to be treated is preferably 7.0 to 8.5. When the pH is lowered, the CN removal effect is good, but the amount of sulfuric acid used is increased and the treated water Cu is also slightly increased. When the pH is high, the effect of removing cyan decreases.

表3は、実施例1において、NaHSOの添加量を変えた(又は無添加とした)実験結果を示している。表3の通り、NaHSOの添加量が200mg/L以上であり、その添加後のORPが80mV以下である場合、シアン除去効果が安定して良好となる。 Table 3 shows experimental results in Example 1 in which the amount of NaHSO 3 added was changed (or was not added). As shown in Table 3, when the addition amount of NaHSO 3 is 200 mg / L or more and the ORP after the addition is 80 mV or less, the cyan removal effect is stable and good.

1 反応槽
2 凝集反応槽
4 凝集沈澱槽
5 濾過器
DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Coagulation reaction tank 4 Coagulation precipitation tank 5 Filter

Claims (2)

シアンを含有する高炉排水に銅化合物及び還元剤を添加して、シアンの難溶性塩を生成させる難溶性塩生成工程と、
該難溶性塩生成工程からの液に凝集剤を添加してシアンの難溶性塩を凝集させて分離する凝集分離工程とを有する高炉排水の処理方法において、
銅塩及び還元剤を添加する反応槽の液のORPが50〜80mVで、pHが7.0〜9.0であり、
該凝集剤としてアルミ系凝集剤を添加することを特徴とする高炉排水の処理方法。
Adding a copper compound and a reducing agent to blast furnace wastewater containing cyanide to produce a hardly soluble salt of cyan,
In a method for treating blast furnace wastewater, comprising a flocculant separating step of adding a flocculant to the liquid from the hardly soluble salt producing step to agglomerate and separate the hardly soluble salt of cyanide,
ORP of the liquid in the reaction vessel for addition of the copper salt and a reducing agent in 50~80MV, pH is 7.0 to 9.0,
A method of treating blast furnace waste water, comprising adding an aluminum-based flocculant as the flocculant.
請求項1において、前記アルミ系凝集剤がPAC及び/又は硫酸バンドであることを特徴とする高炉排水の処理方法。   The blast furnace wastewater treatment method according to claim 1, wherein the aluminum-based flocculant is PAC and / or a sulfuric acid band.
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