JP3780358B2

JP3780358B2 - Treatment method for petroleum combustion ash

Info

Publication number: JP3780358B2
Application number: JP2000363372A
Authority: JP
Inventors: 賢二野崎; 弘隆磯村; 啓一三浦
Original assignee: Taiheiyo Cement Corp
Current assignee: Taiheiyo Cement Corp
Priority date: 2000-11-29
Filing date: 2000-11-29
Publication date: 2006-05-31
Anticipated expiration: 2020-11-29
Also published as: JP2002166241A

Description

【０００１】
【発明の属する技術分野】
本発明は、石油系燃焼灰からバナジウムを効果的に分離回収する処理方法に関する。より詳しくは、石油系燃焼灰の浸出液からレッドケーキの沈澱を経ずに連続溶媒抽出によってバナジウムを効率よく分離回収する方法に関する。
【０００２】
【従来の技術】
火力発電所や各種工業プラントのボイラー等は重油や石油コークス等の石油系燃料を用いるものが多く、現在、多量の燃焼灰が排出されている。これらの大部分は埋め立て処分されているが、この燃焼灰にはバナジウム等の有価金属が含有されており、環境汚染の防止および再資源化の観点から、その有効利用が求められている。
【０００３】
このような重油灰から有価金属を回収する方法が従来知られている。例えば、特開昭６０−４６９３０号には、石油系燃料の燃焼灰スラリーに硫酸を加えて灰中の有価金属を浸出させた後に、液性をアルカリ性に転化して酸化剤を加え、鉄分を沈殿させた後に、液性を再び強酸性として液中のバナジウムを五酸化バナジウムとして沈殿させ、これを分離回収する方法が記載されている。また、特公平４−６１７０９号には、上記方法において鉄分を除去した後の濾液を冷却してバナジウムのアンモニウム化合物を沈殿させて分離し、その濾液に硫酸を添加して硫酸ニッケルアンモニウムを析出させる方法が提案されている。さらに、特公平５−１３７１８号にはバナジウムのアンモニウム化合物を沈殿分離した後に、残渣からアンモニアを分離し、残留するニッケルスラッジと石膏とをおのおの分離する方法が記載されている。
【０００４】
また、重油灰浸出スラリーの溶液にアンモニアを添加してｐＨ２.５〜３に調整すると共に塩素酸ナトリウムを加えて酸性下で液中のバナジウムを酸化し、液温８５℃前後で酸化バナジウムを沈澱(レッドケーキ)させ、固液分離後に、この固形分に温水と炭酸ナトリウムおよび塩素酸ナトリウムを加え、弱酸性(ｐＨ６.５〜７.５)下で再溶解し、これを固液分離して固形分に残留する鉄およびシリカを分離した後にアンモニア水を加えて弱アルカリ(ｐＨ８.５〜９.５)に調整し、液温７５℃前後でバナジン酸アンモニウムを沈澱させ、これを固液分離してバナジウムを回収する方法も知られている。
【０００５】
【発明が解決しようとする課題】
従来の処理方法のように、重油灰スラリーに硫酸を添加して液性をｐＨ３以下に調整し、液温を３０〜８０℃に加温して、灰中に含まれるバナジウムやニッケルなどの有価金属を酸性浸出させる方法では浸出槽などの腐蝕が激しい問題がある。また、硫酸浸出後の酸化処理の際に液性をアルカリ性に転化しており、その後に再び酸性に戻すなど液性の調整が煩雑である。さらに、レッドケーキを沈澱させた後に再溶解と再沈澱を行う方法は鉄分やシリカ分の少ないバナジウム沈殿物を得ることができるが、処理プロセスが複雑であり、液温も高く、反応時間が長いと云う問題がある。
【０００６】
本発明は、従来の処理方法における上記問題を解決したものであり、石油系燃焼灰の浸出スラリー溶液を連続溶媒抽出に適するように希釈し、これを常温下で中性ないし弱アルカリ性に調整し、この液性下でバナジウムを酸化した後に連続溶媒抽出を利用してバナジウムを回収する方法を提供するものであり、バナジウムを比較的に簡単な処理プロセスで効率よく回収でき、常温で処理するので設備の腐食も少なく、経済的に処理することができる方法を提供する。
【０００７】
【課題を解決する手段】
本発明は、（１）石油系燃焼灰の浸出スラリーを固液分離した溶液のバナジウム濃度を３０００ppm以下、およびｐＨを中性ないし弱アルカリ性に調整し、この液性下で液中のバナジウムを酸化し、次いで、この浸出溶液にバナジウム抽出溶媒を導入してバナジウムを抽出し、回収することを特徴とする石油系燃焼灰の処理方法に関する。
【０００８】
本発明の上記処理方法は、（２）石油系燃焼灰の浸出スラリーを固液分離した溶液を希釈してバナジウム濃度を３０００ppm以下に調整すると共に、アンモニアを導入してｐＨ８〜１０に調整し、さらに空気および/または過酸化水素を導入して液中のバナジウムを酸化し、次いで、この浸出溶液にバナジウム抽出溶媒を導入してバナジウムを抽出し、回収する処理方法、（３）ミキサセトラーを用いてバナジウムの溶媒抽出を連続して行う処理方法、（４）石油系燃焼灰を水ないし硫酸で浸出し、その浸出スラリーを固液分離する工程、その濾液のバナジウム濃度を３０００ppm以下とし、ｐＨ８〜１０に調整すると共に空気および/または過酸化水素を導入して液中のバナジウムを酸化する工程、この浸出溶液にバナジウム抽出溶媒を導入してバナジウムを抽出する工程、一方、上記浸出スラリーの固形分にアンモニア水を加えてｐＨ７〜１０に調整し、酸化剤を加えて酸化浸出し、固液分離する工程、この濾液をバナジウム抽出工程に導く工程を有する処理方法、（５）酸化浸出工程で固液分離した濾液をニッケル溶媒抽出工程に導いて処理する工程を有する処理方法を含む。
【０００９】
【発明の実施の形態】
以下、本発明を実施形態に基づいて詳細に説明する。本発明の処理方法の概略を図１に示す。図示する本発明の処理方法の一例は、石油系燃焼灰を水浸出または硫酸浸出し、この浸出スラリーを固液分離する工程、固液分離した溶液のバナジウム濃度を３０００ppm以下に希釈する工程、およびｐＨを中性ないし弱アルカリ性に調整すると共にこの液性下で液中のバナジウムを酸化する工程、この浸出溶液にバナジウム抽出溶媒を導入してバナジウムを抽出し回収する工程を有する。
【００１０】
本発明において石油系燃焼灰とは、タール質燃料、重油、石油コークス、石油ピッチ、アスファルト等の石油系燃料を燃焼した際に生じる塵灰を云う。これらは発電所や各種工業プラントのボイラー等から排出される集塵灰等を処理対象にすることができる。この燃焼灰には多量の硫黄分が含まれているので水を加えてスラリー(水浸出スラリー)にすると硫黄分が溶出して液性はｐＨ１前後の強酸性になる。また硫酸浸出しても同様に強酸性になり、この浸出処理によって燃焼灰に含まれるバナジウムがスラリー中に溶出する。なお、ニッケルやマグネシウムの一部も溶出するが大部分は固形分に残留する。
【００１１】
本発明の溶媒抽出を利用する処理方法は、この浸出スラリーを固液分離した濾液を水で希釈し、あるいは多量の水で浸出することによって、液中のバナジウム濃度が３０００ppm以下となるように調整する。次工程でバナジウムの溶媒抽出を行う場合、高濃度の硫酸アンモニウムが溶存する液中でバナジウム濃度が３０００ppmより高いと抽出溶媒の種類によってはバナジウムの分離が遅くなるので好ましくない。
【００１２】
次に、この溶液にアンモニアを加えて液性を中性ないし弱アルカリ性(ｐＨ８〜１０)に調整する。アンモニアの添加は常温下でよく、加熱する必要はない。この液性下で、さらに酸化剤、例えば、空気や過酸化水素などを導入して液中の４価のバナジウムを５価に酸化する。通常のバナジウム抽出溶媒では４価のバナジウムイオンは抽出されないので、液中のバナジウムを酸化して５価のバナジウムイオンにする。このとき、溶液のｐＨが８より低い(酸性側)と酸化剤の量が多く必要になり、一方ｐＨが１０より高い(アルカリ側)とバナジウムの抽出率が低下するので好ましくない。なお、空気酸化の場合、その導入量は０.０２ｍ³Ｎ/秒以上が適当であり、過酸化水素の場合には２g/l以上が好ましい。
【００１３】
以上のように液性を調整した浸出溶液をバナジウム抽出溶媒と混合して溶液中のバナジウムを抽出する。このバナジウム抽出液は中性ないし弱アルカリ性で作用するもの、例えば、キレート剤(Tricaprylyl Methyl Ammonium Chloride)をケロシンで５vol％に希釈したメチルアンモニウム系キレート液などを用いることができる。抽出処理後、バナジウムを含む抽出溶媒に塩化アンモニウムとアンモニア水の混合液(NH₄Cl:75％、NH₄OH:25％)を水で希釈したものなどを混合して逆抽出を行う。次いで、この逆抽出液にアンモニア水を加えてｐＨ１０前後、液温７５℃前後に調整してメタバナジン酸アンモニウムを沈澱させ、この沈澱を濾過分離して回収する。分離した濾液は逆抽出工程に循環して再利用することができる。回収したメタバナジン酸アンモニウムは乾燥し、あるいは加熱分解してバナジン酸の粉末を得る。
【００１４】
上記バナジウムの抽出処理は、好ましくは、条件を整えて連続抽出を行う。連続抽出装置はミキサセトラー等を用いることができ、抽出装置の種類は限定されない。ミキサセトラーの場合、有機相(Ｏ)と水相(Ａ)の比(Ｏ/Ａ)を、抽出工程では０.２〜５、逆抽出工程では０.５〜２に調整し、セトラーで分離した水相をミキサーに一部戻して濃縮させると良い。
【００１５】
バナジウム抽出溶媒と分離した溶液には硫酸イオンが含まれているので、これにカルシウム化合物を加え、石膏(CaSO₄・2H₂O)を沈澱させて溶液から分離することにより液中の硫酸濃度を低減することができる。また、回収した石膏を再利用することができる。カルシウム化合物としては生石灰(CaO)、消石灰[Ca(OH)₂]、炭酸カルシウム(CaCO₃)などを用いることができる。さらにこの溶液にはアンモニアが多量に含まれているので、石膏を分離した溶液を蒸留塔に導き、アンモニアを蒸留させて回収することができる。
【００１６】
以上の処理方法は、石油系燃焼灰の浸出スラリーを固液分離して得た溶液についてのものであるが、この固液分離によって残留した固形分からもバナジウムやニッケル、マグネシウムを回収することができる。先ず、上記浸出スラリーの固形分にアンモニア水を加えてｐＨ７〜１０の中性ないし弱アルカリ性に調整し、この液性下で酸化処理する。酸化処理は溶液に空気を導入して攪拌する第一段処理と、さらに過酸化水素あるいは硫酸を溶液に加えて酸化する第二段処理とを行うと良い。この中性ないし弱アルカリ性下の酸化浸出によって固形分に含まれるバナジウムおよびニッケルの浸出効果が向上する。
【００１７】
このような中性ないし弱アルカリ性下での酸化浸出後に、この浸出スラリーを固液分離し、この溶液を溶媒抽出工程に導いてバナジウムおよびニッケルを回収する。残渣は最初の浸出工程に戻して再処理すると良い。このバナジウムの溶媒抽出は先の希釈工程で得た溶液のバナジウム溶媒抽出と同様に行えば良い。あるいは、この浸出溶液と先の希釈工程で得た溶液とを混合してバナジウムの溶媒抽出をまとめて行っても良い。
【００１８】
ニッケルを回収するには、バナジウム抽出前あるいは抽出後の溶液をニッケル抽出工程に導き、中性ないし弱アルカリ性で作用するアセトフェノン系キレート液やバーサチック酸などの溶媒を用いてニッケルを抽出し、次いでこれを濃硫酸で洗浄してニッケルを逆抽出し、硫酸ニッケルとして回収することができる。これらバナジウムの抽出とニッケルの抽出は液中の含有量が少ないほうから行えば抽出処理の負担が少なくて済む。
【００１９】
溶媒抽出後の溶液には硫酸イオンとマグネシウムイオンが溶存しているので、これを石膏および水酸化マグネシウムとして回収することができる。石膏の回収は先の希釈工程後の処理と同様にして行っても良いが、この溶液に消石灰スラリーなどを混合して石膏と水酸化マグネシウムを同時に沈澱させ、これを液体サイクロンに導いて分離する方法でも良い。ここで生じる水酸化マグネシウムの沈澱粒子は概ね石膏の沈澱粒子よりも微細であるので、これらの沈澱を含む懸濁液を液体サイクロンに導いて分離することができる。
【００２０】
【実施例】
以下、本発明を実施例によって具体的に示す。なお、％は特に示さない限り重量％である。
【００２１】
〔実施例１〕
燃焼灰（Ｖ:２.０wt％、Ｎｉ:０.４４wt％、Ｍｇ:２.３wt％、Ｓ:２２wt％）１００ｋgに水１００リットルを加え、ｐＨが２.５以上の場合にはさらに硫酸を加えて１０分間浸出し、この浸出スラリーをフィルタープレスで固液分離した。この濾液１１３リットルにアンモニア水(20％濃度)１１kgと水７７５kgを加えて液中のバナジウム濃度を１７００ppm、ｐＨ９.０に調整し、これに空気０.０３m³Ｎ/secを吹き込んで均一に攪拌した。この溶液にバナジウム抽出溶媒を加えてバナジウムを抽出した。バナジウムの抽出溶媒としては、キレート剤（Tricaprylyl Methyl Ammonium Chloride）をケロシンで５vol％に希釈したもの用い、浸出溶液に対して抽出溶媒を１：１の液量で３分間混合した。この抽出溶媒３００mlに逆抽出液（NH₄Cl８％とNH₄OH３％の混合液）３００mlを混合し、溶液のｐＨを１０.７に調整し、３分間混合してバナジウムを逆抽出した。この逆抽出液をバナジウム抽出溶媒と分離した後に再び新しい抽出溶媒と混合して逆抽出を繰り返し、バナジウムを濃縮した。このとき逆抽出液で生じた析出物は沈降させて分離し、その上澄み液(２８５ml)に新しい逆抽出液(１５ml)を補給して混合槽に戻し、抽出溶媒と混合して逆抽出を繰り返した。沈降物は濾過分離して回収し、乾燥してメタバナジン酸アンモニウム粉末３.４kgを得た。
【００２２】
〔実施例２〕
実施例１の水浸出スラリーを固液分離して得た固形分５８kg(含水量34％)にアンモニア水(20％濃度)３.７kgと水２２６kgを加えてｐＨ約８.０に調整し、これに空気０.０３m³Ｎ/secを吹き込んで酸化処理を行った。この浸出スラリーをフィルタープレスで固液分離し、濾液２４０リットルを得た。この濾液のバナジウム濃度は２g/l、ニッケル濃度は１.９g/lであった。この溶液にバーサチック酸を加え、溶液とバーサチック酸の液量を１：１の割合で３分間混合してニッケルを抽出した。次に、このバーサチック酸を溶液から分離し、バーサチック酸３００mlに対して硫酸(濃度20％)３００mlを加えて３分間混合し、ニッケルを硫酸に逆抽出した。バーサチック酸と分離した硫酸は新しくニッケルを抽出したバーサチック酸と再び混合し、逆抽出を繰り返してニッケルを濃縮した。これを４０回繰り返した後に逆抽出液を３０〜８０℃に加熱して水分を蒸発させ、硫酸ニッケル粉末１９kgを得た。一方、ニッケル抽出溶媒と分離した浸出溶液２４０リットルを実施例１と同様のバナジウム抽出工程に導き、メタバナジン酸アンモニウム粉末１.１kｇを得た。
【００２３】
【発明の効果】
本発明の処理方法によれば、石油系燃焼灰の浸出スラリー溶液からバナジウムを比較的に簡単な処理プロセスで効率よく回収できる。また本処理方法は常温で実施するので設備の腐食やエネルギー費用が少なく、経済的である。
【図面の簡単な説明】
【図１】本発明の処理方法の概略を示す工程図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a treatment method for effectively separating and recovering vanadium from petroleum combustion ash. More specifically, the present invention relates to a method for efficiently separating and recovering vanadium from a leachate of petroleum-based combustion ash by continuous solvent extraction without precipitation of red cake.
[0002]
[Prior art]
Many boilers of thermal power plants and various industrial plants use petroleum-based fuels such as heavy oil and petroleum coke, and a large amount of combustion ash is currently discharged. Most of these are disposed of in landfills, but this combustion ash contains valuable metals such as vanadium, and their effective use is required from the viewpoint of prevention of environmental pollution and recycling.
[0003]
A method for recovering valuable metals from such heavy oil ash is conventionally known. For example, in Japanese Patent Laid-Open No. 60-46930, sulfuric acid is added to petroleum fuel combustion ash slurry to leach valuable metals in the ash, the liquid is converted to alkaline, an oxidizing agent is added, and iron content is reduced. A method is described in which, after precipitation, the liquid property is made strongly acidic again to precipitate vanadium in the solution as vanadium pentoxide, and this is separated and recovered. In JP-B-4-61709, the filtrate after removing iron in the above method is cooled to precipitate and precipitate an ammonium compound of vanadium, and sulfuric acid is added to the filtrate to precipitate nickel ammonium sulfate. A method has been proposed. Further, Japanese Patent Publication No. 5-13718 describes a method in which ammonium compound of vanadium is precipitated and separated, then ammonia is separated from the residue, and the remaining nickel sludge and gypsum are separated.
[0004]
In addition, ammonia is added to the heavy oil ash leaching slurry to adjust the pH to 2.5-3, and sodium chlorate is added to oxidize vanadium in the solution under acidity, and precipitate vanadium oxide at a liquid temperature of about 85 ° C. (Red cake) After solid-liquid separation, warm water, sodium carbonate and sodium chlorate were added to this solid, and redissolved under weak acidity (pH 6.5 to 7.5). After separating iron and silica remaining in the solid content, aqueous ammonia is added to adjust to weak alkali (pH 8.5 to 9.5), and ammonium vanadate is precipitated at a liquid temperature of about 75 ° C., and this is solid-liquid separated. A method for recovering vanadium is also known.
[0005]
[Problems to be solved by the invention]
Like conventional processing methods, sulfuric acid is added to heavy oil ash slurry to adjust the liquidity to pH 3 or lower, the liquid temperature is heated to 30 to 80 ° C., and valuables such as vanadium and nickel contained in ash are added. In the method of acid leaching of metal, there is a problem that corrosion of the leaching tank is severe. In addition, the liquidity is converted to alkaline during the oxidation treatment after the sulfuric acid leaching, and then the liquidity adjustment is complicated, such as returning to acidity again. Furthermore, the method of redissolving and reprecipitating after precipitating the red cake can obtain vanadium precipitates with less iron and silica, but the treatment process is complicated, the liquid temperature is high, and the reaction time is long. There is a problem.
[0006]
The present invention solves the above-mentioned problems in the conventional processing method, and dilutes the leaching slurry solution of petroleum combustion ash so as to be suitable for continuous solvent extraction, and adjusts this to neutral or weak alkalinity at room temperature. This method provides a method for recovering vanadium using continuous solvent extraction after oxidation of vanadium under this liquid condition. Vanadium can be efficiently recovered by a relatively simple processing process and processed at room temperature. Provided is a method which can be economically processed with less equipment corrosion.
[0007]
[Means for solving the problems]
In the present invention, (1) the vanadium concentration of the solution obtained by solid-liquid separation of the leaching slurry of petroleum combustion ash is adjusted to 3000 ppm or less, and the pH is adjusted to neutral to weak alkalinity, and vanadium in the liquid is oxidized under this liquidity. Then, the present invention relates to a method for treating petroleum combustion ash, characterized in that vanadium extraction solvent is introduced into the leaching solution to extract and recover vanadium.
[0008]
The above-mentioned treatment method of the present invention is (2) diluting a solution obtained by solid-liquid separation of the leaching slurry of petroleum combustion ash to adjust the vanadium concentration to 3000 ppm or less and introducing ammonia to adjust the pH to 8 to 10, Further, air and / or hydrogen peroxide is introduced to oxidize vanadium in the liquid, and then a vanadium extraction solvent is introduced into this leaching solution to extract and recover vanadium, and (3) a mixer settler is used. (4) A step of leaching petroleum-based combustion ash with water or sulfuric acid and solid-liquid separating the leached slurry, and setting the vanadium concentration of the filtrate to 3000 ppm or less, pH 8 to And the step of oxidizing air and / or hydrogen peroxide to oxidize vanadium in the liquid, and introducing the vanadium extraction solvent into the leaching solution Step of extracting nadium, on the other hand, adding ammonia water to the solid content of the leaching slurry to adjust the pH to 7 to 10, adding oxidant to oxidative leaching and solid-liquid separation, leading this filtrate to the vanadium extraction step And (5) a processing method including a step of introducing the filtrate, which is solid-liquid separated in the oxidative leaching step, to the nickel solvent extraction step and processing.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments. An outline of the treatment method of the present invention is shown in FIG. An example of the treatment method of the present invention shown in the figure is a step of leaching petroleum combustion ash with water or sulfuric acid, and solid-liquid separating the leached slurry, diluting the vanadium concentration of the solid-liquid separated solution to 3000 ppm or less, and It has a step of adjusting pH to neutral to weakly alkaline and oxidizing vanadium in the liquid under this liquid property, and a step of extracting and recovering vanadium by introducing a vanadium extraction solvent into the leaching solution.
[0010]
In the present invention, the petroleum-based combustion ash refers to dust ash generated when burning petroleum-based fuels such as tar fuel, heavy oil, petroleum coke, petroleum pitch, and asphalt. These can treat dust collection ash discharged from boilers of power plants and various industrial plants. Since this combustion ash contains a large amount of sulfur, when water is added to form a slurry (water leaching slurry), the sulfur is eluted and the liquidity becomes strongly acidic around pH 1. Further, even if sulfuric acid leaches, it becomes strongly acidic as well, and vanadium contained in the combustion ash is eluted into the slurry by this leaching treatment. Although some nickel and magnesium are also eluted, most of them remain in the solid content.
[0011]
The treatment method using the solvent extraction of the present invention is adjusted so that the vanadium concentration in the liquid is 3000 ppm or less by diluting the filtrate obtained by solid-liquid separation of the leaching slurry with water or leaching with a large amount of water. To do. When performing solvent extraction of vanadium in the next step, if the vanadium concentration is higher than 3000 ppm in a solution in which high-concentration ammonium sulfate is dissolved, the separation of vanadium becomes slow depending on the type of extraction solvent, which is not preferable.
[0012]
Next, ammonia is added to this solution to adjust the liquidity to neutral to weakly alkaline (pH 8 to 10). Ammonia may be added at room temperature and does not need to be heated. Under this liquid property, an oxidant such as air or hydrogen peroxide is further introduced to oxidize tetravalent vanadium in the liquid to pentavalent. Since tetravalent vanadium ions are not extracted with a normal vanadium extraction solvent, vanadium in the liquid is oxidized to pentavalent vanadium ions. At this time, if the pH of the solution is lower than 8 (acidic side), a large amount of oxidizing agent is required. On the other hand, if the pH is higher than 10 (alkali side), the vanadium extraction rate is lowered, which is not preferable. In the case of air oxidation, the introduction amount is suitably 0.02 m ³ N / second or more, and in the case of hydrogen peroxide, 2 g / l or more is preferable.
[0013]
The leaching solution with adjusted liquidity as described above is mixed with a vanadium extraction solvent to extract vanadium in the solution. The vanadium extract may be neutral or weakly alkaline, for example, a methylammonium chelating solution in which a chelating agent (Tricaprylyl Methyl Ammonium Chloride) is diluted to 5 vol% with kerosene. After the extraction treatment, back extraction is performed by mixing a mixed solution of ammonium chloride and ammonia water (NH ₄ Cl: 75%, NH ₄ OH: 25%) diluted with water into an extraction solvent containing vanadium. Next, aqueous ammonia is added to the back extract to adjust the pH to around 10 and the solution temperature to around 75 ° C. to precipitate ammonium metavanadate, and the precipitate is collected by filtration. The separated filtrate can be circulated and reused in the back extraction step. The recovered ammonium metavanadate is dried or thermally decomposed to obtain vanadic acid powder.
[0014]
The vanadium extraction treatment is preferably carried out by adjusting the conditions. As the continuous extraction device, a mixer setter or the like can be used, and the type of the extraction device is not limited. In the case of a mixer settler, the ratio (O / A) of the organic phase (O) to the aqueous phase (A) is adjusted to 0.2 to 5 in the extraction process and 0.5 to 2 in the back extraction process, and separated by the settler. A part of the water phase returned to the mixer may be concentrated.
[0015]
Since the solution separated from the vanadium extraction solvent contains sulfate ions, a calcium compound is added to the solution, and gypsum (CaSO ₄ · 2H ₂ O) is precipitated and separated from the solution to reduce the sulfuric acid concentration in the solution. Can be reduced. Moreover, the collected gypsum can be reused. As the calcium compound, quick lime (CaO), slaked lime [Ca (OH) ₂ ], calcium carbonate (CaCO ₃ ) and the like can be used. Further, since this solution contains a large amount of ammonia, the solution from which the gypsum is separated can be guided to a distillation tower and recovered by distilling the ammonia.
[0016]
The above processing method is for a solution obtained by solid-liquid separation of a petroleum-based combustion ash leaching slurry. Vanadium, nickel, and magnesium can also be recovered from the solid content remaining by this solid-liquid separation. . First, aqueous ammonia is added to the solid content of the leaching slurry to adjust the pH to neutral or weakly alkaline from 10 to 10, and oxidation treatment is performed under this liquid property. The oxidation treatment may be performed by a first stage treatment in which air is introduced into the solution and stirred, and a second stage treatment in which hydrogen peroxide or sulfuric acid is added to the solution to oxidize. The leaching effect of vanadium and nickel contained in the solid content is improved by the oxidative leaching under neutral or weak alkaline.
[0017]
After the oxidative leaching under such neutral or weak alkalinity, the leaching slurry is subjected to solid-liquid separation, and this solution is led to a solvent extraction step to recover vanadium and nickel. The residue may be returned to the first leaching step and reprocessed. The vanadium solvent extraction may be performed in the same manner as the vanadium solvent extraction of the solution obtained in the previous dilution step. Alternatively, this leaching solution and the solution obtained in the previous dilution step may be mixed and solvent extraction of vanadium may be performed collectively.
[0018]
In order to recover nickel, the solution before or after vanadium extraction is introduced into the nickel extraction process, and nickel is extracted using a solvent such as acetophenone-based chelating solution or versatic acid that acts neutrally or weakly alkaline. Can be washed with concentrated sulfuric acid to back-extract nickel and recovered as nickel sulfate. If extraction of these vanadium and nickel is performed from the one with a lower content in the liquid, the burden of the extraction process can be reduced.
[0019]
Since sulfate ions and magnesium ions are dissolved in the solution after solvent extraction, these can be recovered as gypsum and magnesium hydroxide. Gypsum may be collected in the same manner as the treatment after the previous dilution step, but this solution is mixed with slaked lime slurry to precipitate gypsum and magnesium hydroxide at the same time, and this is led to a liquid cyclone for separation. The method is fine. Since the precipitated particles of magnesium hydroxide produced here are generally finer than the precipitated particles of gypsum, the suspension containing these precipitates can be led to a liquid cyclone and separated.
[0020]
【Example】
Hereinafter, the present invention will be specifically described by way of examples. % Is% by weight unless otherwise specified.
[0021]
[Example 1]
Add 100 liters of water to 100 kg of combustion ash (V: 2.0 wt%, Ni: 0.44 wt%, Mg: 2.3 wt%, S: 22 wt%). If the pH is 2.5 or more, add sulfuric acid. In addition, leaching was performed for 10 minutes, and this leached slurry was subjected to solid-liquid separation with a filter press. 11 kg of ammonia water (20% concentration) and 775 kg of water were added to 113 liters of this filtrate to adjust the vanadium concentration in the liquid to 1700 ppm and pH 9.0, and 0.03 m ³ N / sec of air was blown into this to uniformly stir. did. Vanadium extraction solvent was added to this solution to extract vanadium. As the extraction solvent for vanadium, a chelating agent (Tricaprylyl Methyl Ammonium Chloride) diluted to 5 vol% with kerosene was used, and the extraction solvent was mixed with the leaching solution in a 1: 1 liquid amount for 3 minutes. The extraction solvent back extraction solution 300ml (NH ₄ Cl8% and NH ₄ OH3% of the mixture) were mixed 300 ml, the pH of the solution was adjusted to 10.7, were back extracted vanadium and mixed for 3 minutes. This back extract was separated from the vanadium extraction solvent and then mixed with a new extraction solvent again, and back extraction was repeated to concentrate vanadium. At this time, the precipitate generated in the back extract is allowed to settle and separated, and the supernatant (285 ml) is replenished with a new back extract (15 ml), returned to the mixing tank, and mixed with the extract solvent to repeat back extraction. It was. The precipitate was collected by filtration and dried to obtain 3.4 kg of ammonium metavanadate powder.
[0022]
[Example 2]
To a solid content of 58 kg (water content: 34%) obtained by solid-liquid separation of the water leaching slurry of Example 1, 3.7 kg of ammonia water (20% concentration) and 226 kg of water were added to adjust the pH to about 8.0, An oxidation treatment was performed by blowing 0.03 m ³ N / sec of air into this. This leached slurry was subjected to solid-liquid separation with a filter press to obtain 240 liters of filtrate. The filtrate had a vanadium concentration of 2 g / l and a nickel concentration of 1.9 g / l. Versatic acid was added to this solution, and the solution and versatic acid were mixed at a ratio of 1: 1 for 3 minutes to extract nickel. Next, this versatic acid was separated from the solution, 300 ml of sulfuric acid (concentration 20%) was added to 300 ml of versatic acid, mixed for 3 minutes, and nickel was back-extracted into sulfuric acid. The sulfuric acid separated from the versatic acid was mixed again with the freshly extracted versatic acid, and the back extraction was repeated to concentrate the nickel. After repeating this 40 times, the back extract was heated to 30 to 80 ° C. to evaporate the water, thereby obtaining 19 kg of nickel sulfate powder. On the other hand, 240 liters of the leaching solution separated from the nickel extraction solvent was led to the same vanadium extraction step as in Example 1 to obtain 1.1 kg of ammonium metavanadate powder.
[0023]
【The invention's effect】
According to the treatment method of the present invention, vanadium can be efficiently recovered from a leached slurry solution of petroleum combustion ash by a relatively simple treatment process. In addition, since this treatment method is carried out at room temperature, there is little equipment corrosion and energy costs and it is economical.
[Brief description of the drawings]
FIG. 1 is a process diagram showing an outline of a treatment method of the present invention.

Claims

The vanadium concentration of the solution obtained by solid-liquid separation of the petroleum-based combustion ash leaching slurry is adjusted to 3000 ppm or less, and the pH is adjusted to neutral or weak alkali. A method for treating petroleum-based combustion ash, wherein a vanadium extraction solvent is introduced to extract vanadium and recovered.

A solution obtained by solid-liquid separation of the leaching slurry of petroleum combustion ash is diluted to adjust the vanadium concentration to 3000 ppm or less, and ammonia is adjusted to pH 8-10, and air and / or hydrogen peroxide is further introduced. The treatment method according to claim 1, wherein vanadium in the solution is oxidized, and then a vanadium extraction solvent is introduced into the leaching solution to extract and recover vanadium.

The processing method of Claim 1 or 2 which performs solvent extraction of vanadium continuously using a mixer settler.

A step of leaching petroleum combustion ash with water or sulfuric acid and solid-liquid separation of the leached slurry, adjusting the vanadium concentration of the filtrate to 3000 ppm or less, adjusting the pH to 8-10, and introducing air and / or hydrogen peroxide. The step of oxidizing vanadium in the liquid, the step of introducing vanadium extraction solvent into this leaching solution and extracting vanadium, while adjusting the pH to 7-10 by adding ammonia water to the solid content of the leaching slurry, 4. The processing method according to claim 1, further comprising a step of oxidative leaching and solid-liquid separation, and a step of leading the filtrate to a vanadium extraction step.

The processing method according to claim 4, further comprising a step of guiding the filtrate separated by solid-liquid separation in the oxidative leaching step to a nickel solvent extraction step.