JP2002166241A - Method for treating petroleum combustion ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treating method for reclaiming vanadium efficiently from petroleum combustion ash in a simple process. SOLUTION: The petroleum combustion ash is separated into solid and liquid by being leached out with water or sulfic acid, vanadium concentration of the filtrate is set to 3000 ppm or less and adjusted to pH 8-10, the vanadium is oxidized with air and/or hydrogen peroxide, and from which the vanadium is extracted with a solvent. Ammonia water is added to a solid content of the leached slurry to be adjusted to pH 7-10, an oxidizing agent is added therein to be oxidized and leached, and the filtrate in which solid and liquid are separated is treated in a vanadium extracting process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for effectively separating and recovering vanadium from petroleum-based 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 a red cake.

[0002]

2. Description of the Related Art Many boilers of thermal power plants and various industrial plants use petroleum fuels such as heavy oil and petroleum coke, and at present, a large amount of combustion ash is discharged. Most of these are disposed of in landfills, but this combustion ash contains valuable metals such as vanadium, and effective utilization of these metals is required from the viewpoint of preventing environmental pollution and recycling.

[0003] Methods of recovering valuable metals from such heavy oil ash have been conventionally known. For example, JP-A-60-469
In No. 30, after adding sulfuric acid to the combustion ash slurry of petroleum-based fuel and leaching valuable metals in the ash, the liquid was converted to alkaline, an oxidizing agent was added, and iron was precipitated. Is again made strongly acidic, and vanadium in the liquid is precipitated as vanadium pentoxide, which is separated and recovered. Further, Japanese Patent Publication No. 4-61709 discloses that the filtrate after removing iron in the above method is cooled to precipitate and separate an ammonium compound of vanadium, and sulfuric acid is added to the filtrate to precipitate nickel ammonium sulfate. A method has been proposed. Furthermore, Japanese Patent Publication No. 5-13718
The publication describes a method in which ammonium compounds of vanadium are separated by precipitation, ammonia is separated from the residue, and the remaining nickel sludge and gypsum are each separated.

Further, ammonia is added to the solution of the heavy oil ash leaching slurry to adjust the pH to 2.5 to 3, and vanadium in the solution is oxidized under acidic conditions by adding sodium chlorate. After vanadium is precipitated (red cake) and solid-liquid separated, warm water, sodium carbonate and sodium chlorate are added to the solid, and the mixture is weakly acidic (pH
The solution was redissolved under 6.5-7.5) and separated into solid and liquid to separate iron and silica remaining in the solid, and then added with aqueous ammonia to weak alkali (pH 8.5-9.5). It is also known to adjust the temperature, precipitate ammonium vanadate at a liquid temperature of about 75 ° C., and separate the solid into a liquid to recover vanadium.

[0005]

As in the conventional treatment method, sulfuric acid is added to heavy oil ash slurry to adjust the liquid property to pH 3 or less, and the liquid temperature is raised to 30 to 80 ° C. In the method of acidic leaching of valuable metals such as vanadium and nickel contained in water, there is a problem that corrosion of a leaching tank or the like is severe. In addition, during the oxidation treatment after sulfuric acid leaching, the liquid property is converted to alkaline, and thereafter the liquid property is adjusted again, for example, by returning to acidic again. In addition, the method of redissolving and reprecipitating the red cake after precipitation can obtain a vanadium precipitate having a small amount of iron and silica, but the treatment process is complicated, the liquid temperature is high, and the reaction time is long. There is a problem.

The present invention solves the above-mentioned problems in the conventional treatment method, and dilutes a leaching slurry solution of petroleum-based combustion ash so as to be suitable for continuous solvent extraction, and neutralizes the solution at room temperature with neutral to weak alkaline. It is intended to provide a method of recovering vanadium using continuous solvent extraction after oxidizing vanadium under this liquidity, vanadium can be efficiently recovered by a relatively simple treatment process, and at room temperature. The present invention provides a method capable of economically treating because the treatment is less likely to corrode equipment.

[0007]

According to the present invention, there is provided (1) a solution obtained by solid-liquid separation of a leaching slurry of petroleum-based combustion ash, wherein the vanadium concentration is adjusted to 3000 ppm or less, and the pH is adjusted to neutral or weakly alkaline. Oxidizes vanadium in the liquid with
Next, the present invention relates to a method for treating petroleum-based combustion ash, which comprises introducing a vanadium extraction solvent into the leaching solution to extract and recover vanadium.

According to the above-mentioned treatment method of the present invention, (2) a solution obtained by solid-liquid separation of a leaching slurry of petroleum-based combustion ash is diluted to adjust the vanadium concentration to 3000 ppm or less, and ammonia is introduced to adjust the pH to 8 to 10. Adjusting, further oxidizing the vanadium in the liquid by introducing air and / or hydrogen peroxide, and then extracting vanadium by introducing a vanadium extraction solvent to the leaching solution, a processing method of recovering,
(3) a treatment method for continuously extracting the solvent of vanadium using a mixer settler, (4) a step of leaching petroleum-based combustion ash with water or sulfuric acid, and a solid-liquid separation of the leached slurry.
The vanadium concentration of the filtrate was adjusted to 3000 ppm or less, and p
Adjusting the H8 to 10 and introducing air and / or hydrogen peroxide to oxidize vanadium in the liquid; introducing a vanadium extraction solvent to the leaching solution to extract vanadium; A treatment method having a step of adding ammonia water to the solid content to adjust the pH to 7 to 10, adding an oxidizing agent, oxidizing and leaching, and solid-liquid separation, and a step of leading the filtrate to a vanadium extraction step; And a treatment method having a step of treating the filtrate separated by solid-liquid separation in the step of extracting with a nickel solvent.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 shows an outline of the processing method of the present invention. One example of the treatment method of the present invention shown in the drawings is a step of leaching petroleum-based combustion ash with water or sulfuric acid, separating the leached slurry into solid and liquid, and setting the vanadium concentration of the solid-liquid separated solution to 30.
A step of diluting the solution to 00 ppm or less, and a step of adjusting the pH to neutral to weakly alkaline and oxidizing vanadium in the solution under the liquidity, and extracting and recovering vanadium by introducing a vanadium extraction solvent into the leaching solution. Having a process.

In the present invention, the petroleum-based combustion ash refers to dust ash generated when a petroleum-based fuel such as tar fuel, heavy oil, petroleum coke, petroleum pitch, and asphalt is burned. These can treat dust ash discharged from boilers and the like 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 leached slurry), the sulfur is eluted and the liquid property becomes strongly acidic at around pH 1. Also, sulfuric acid leaching becomes strongly acidic, and vanadium contained in the combustion ash is eluted into the slurry by this leaching treatment. Note that a part of nickel or magnesium is also eluted, but most of the nickel or magnesium remains in the solid content.

The processing method using solvent extraction according to the present invention comprises:
The filtrate obtained by solid-liquid separation of the leached slurry is diluted with water or leached with a large amount of water so that the concentration of vanadium in the liquid is adjusted to 3000 ppm or less. When performing vanadium solvent extraction in the next step, the vanadium concentration is set to 300 in a solution in which a high concentration of ammonium sulfate is dissolved.
If it is higher than 0 ppm, the separation of vanadium will be slow depending on the kind of the extraction solvent, which is not preferable.

Next, ammonia is added to the solution to adjust the solution to neutral to weakly alkaline (pH 8 to 10).
The addition of ammonia may be performed at room temperature and does not require heating. Under this liquidity, an oxidizing agent 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 by 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 (acid side), a large amount of the oxidizing agent is required, while if the pH is higher than 10 (alkaline side), the extraction rate of vanadium decreases, which is not preferable. In the case of air oxidation, the introduction amount is suitably 0.02 m ³ N / sec or more, and in the case of hydrogen peroxide, it is preferably 2 g / l or more.

[0013] The leaching solution whose liquid properties have been adjusted as described above is mixed with a vanadium extraction solvent to extract vanadium in the solution. This vanadium extract is neutral or weakly alkaline, for example, a chelating agent (Tricaprylyl Met
hyl Ammonium Chloride) diluted with kerosene to 5 vol% can be used. After the extraction treatment, a mixed solution of ammonium chloride and ammonia water (NH ₄ Cl: 75%, NH ₄ Cl) was added to an extraction solvent containing vanadium.
(OH: 25%) diluted with water and the like are mixed and back-extracted. Next, aqueous ammonia was added to the back extract to adjust the pH.
The solution is adjusted to about 10 and the liquid temperature to about 75 ° C. to precipitate ammonium metavanadate, and the precipitate is separated by filtration and collected. The separated filtrate can be recycled and recycled to the back extraction step. The recovered ammonium metavanadate is dried or thermally decomposed to obtain a vanadic acid powder.

In the above-mentioned vanadium extraction treatment, preferably, continuous extraction is performed under conditions. As the continuous extraction device, a mixer settler or the like can be used, and the type of the extraction device is not limited. In the case of mixer settler, organic phase (O) and aqueous phase
When the ratio (O / A) of (A) is adjusted to 0.2 to 5 in the extraction step and to 0.5 to 2 in the back extraction step, the aqueous phase separated by the settler is partially returned to the mixer and concentrated. good.

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 to separate the solution from the solution. The sulfuric acid concentration can be reduced.
Further, 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. In addition, this solution contains a large amount of ammonia,
The solution from which the gypsum has been separated is guided to a distillation column, and ammonia can be distilled and recovered.

The above treatment method is for a solution obtained by solid-liquid separation of a leaching slurry of petroleum-based combustion ash, and vanadium, nickel and magnesium are also recovered from the solid content remaining by this solid-liquid separation. be able to. First, ammonia water is added to the solid content of the leached slurry to adjust the pH to a neutral to weakly alkaline pH of 7 to 10, and an oxidation treatment is performed under this liquidity. In the oxidation treatment, it is preferable to perform a first stage treatment in which air is introduced into the solution and agitating the solution, and a second stage treatment in which hydrogen peroxide or sulfuric acid is added to the solution to oxidize the solution. Oxidizing leaching under neutral or weak alkaline conditions improves the leaching effect of vanadium and nickel contained in the solid content.

After such oxidative leaching under neutral or weak alkaline conditions, the leached slurry is subjected to solid-liquid separation, and the 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. This 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, the leaching solution and the solution obtained in the previous dilution step may be mixed, and the solvent extraction of vanadium may be performed collectively.

To recover nickel, the solution before or after vanadium extraction is led to a nickel extraction step, and nickel is extracted using a solvent such as an acetophenone-based chelate solution or a versatic acid which acts in a neutral or weak alkaline state. It can then be washed with concentrated sulfuric acid to back-extract nickel and recover as nickel sulfate. If the extraction of vanadium and the extraction of nickel are performed from the side with the smaller content in the liquid, the burden of the extraction process can be reduced.

Since the sulfate ion and the magnesium ion are dissolved in the solution after the solvent extraction, it can be recovered as gypsum and magnesium hydroxide. The gypsum may be collected in the same manner as in the treatment after the previous dilution step.However, this solution is mixed with slaked lime slurry to precipitate gypsum and magnesium hydroxide at the same time, and then led to a liquid cyclone for separation. A method is also acceptable. Since the precipitated particles of magnesium hydroxide formed here are generally finer than the precipitated particles of gypsum, the suspension containing these precipitates can be introduced into a hydrocyclone for separation.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples. The percentages are by weight unless otherwise indicated.

Example 1 Combustion ash (V: 2.0 wt%, N
i: 0.44 wt%, Mg: 2.3 wt%, S: 22 wt%) 10
100 kg of water was added to 0 kg, and when the pH was 2.5 or more, sulfuric acid was further added and leached for 10 minutes, and the leached slurry was solid-liquid separated by a filter press. This filtrate 113
11 kg of aqueous ammonia (20% concentration) and 775 kg of water were added to the liter to adjust the vanadium concentration in the liquid to 1700 ppm and pH 9.0, and air was blown into the liquid to give 0.03 m ³ N / sec, followed by uniform stirring. A vanadium extraction solvent was added to this solution to extract vanadium. As the extraction solvent for vanadium,
Chelating agent (Tricaprylyl Methyl Ammonium Chloride)
Was diluted to 5 vol% with kerosene, and the extraction solvent was mixed with the leaching solution at a 1: 1 volume 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, mixed with a new extraction solvent again, and back-extraction was repeated to concentrate the vanadium. At this time, the precipitate formed in the back extract was settled and separated, and the supernatant (285 ml) was added to the fresh back extract (1).
(5 ml) was added back to the mixing tank, mixed with the extraction solvent, and the back extraction was repeated. The precipitate was collected by filtration and dried to obtain 3.4 kg of ammonium metavanadate powder.

Example 2 3.7 kg of aqueous ammonia (20% concentration) and 226 kg of water were added to 58 kg of solid content (water content 34%) obtained by solid-liquid separation of the water leached slurry of Example 1 to obtain a pH. About 8.
Was adjusted to 0, it was performed Thereto blown by oxidizing the air 0.03m ³ N / sec. This leached slurry was subjected to solid-liquid separation with a filter press to obtain 240 liters of a 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 the solution, and nickel was extracted by mixing the solution and the versatic acid at a 1: 1 ratio for 3 minutes. Next, this versatic acid was separated from the solution, and sulfuric acid (concentration: 20%) was added to 300 ml of versatic acid.
00 ml was added and mixed for 3 minutes, and nickel was back-extracted into sulfuric acid. The sulfuric acid separated from versatic acid was mixed again with versatic acid from which nickel was newly extracted, and nickel was concentrated by repeating back-extraction. After repeating this 40 times, the back extract is heated to 30 to 80 ° C. to evaporate water,
19 kg of nickel sulfate powder was obtained. On the other hand, 240 l of the leach 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]

According to the treatment method of the present invention, vanadium can be efficiently recovered from a leach slurry solution of petroleum-based combustion ash by a relatively simple treatment process. In addition, since the present treatment method is carried out at normal temperature, equipment corrosion and energy costs are small and economical.

[Brief description of the drawings]

FIG. 1 is a process diagram showing an outline of a processing method of the present invention.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Keiichi Miura 2-4-2, Osaku, Sakura City, Chiba Prefecture Pacific Cement Co., Ltd. Central Research Laboratory F-term (reference) 4D004 AA36 AB03 BA05 CA13 CA34 CA35 CA36 CC02 CC03 CC04 CC06 CC11 CC12 DA03 DA10 DA20 4D056 AB03 AC02 AC25 BA03 CA06 CA14 CA27 CA31 CA33 CA39 DA05 DA10

Claims (5)

[Claims] 1. A vanadium concentration of a solution obtained by solid-liquid separation of a leaching slurry of petroleum-based combustion ash is adjusted to 3000 ppm or less, and a pH is adjusted to neutral or weakly alkaline, and vanadium in the liquid is oxidized under the liquidity. Next, a vanadium extraction solvent is introduced into the leaching solution to extract and recover vanadium, and a method for treating petroleum-based combustion ash, comprising: 2. A solution obtained by solid-liquid separation of a leaching slurry of petroleum-based combustion ash is diluted to adjust the vanadium concentration to 3000 ppm or less, and ammonia is introduced to adjust the pH to 8 to 10.
And further introduce air and / or hydrogen peroxide to oxidize vanadium in the liquid, and then introduce vanadium extraction solvent into the leaching solution to extract vanadium,
The processing method according to claim 1, wherein the processing is performed. 3. The treatment method according to claim 1, wherein the solvent extraction of vanadium is continuously performed using a mixer settler. 4. A step of leaching petroleum-based combustion ash with water or sulfuric acid, separating the leached slurry into a solid and a liquid, and setting the vanadium concentration of the filtrate to 3000 ppm or less and the pH of 8 to 10
Adjusting the air and / or introducing hydrogen peroxide to oxidize the vanadium in the liquid, introducing a vanadium extraction solvent to the leaching solution to extract vanadium, while the solid content of the leaching slurry 4. The method according to claim 1, further comprising the steps of adding ammonia water to adjust the pH to 7 to 10, adding an oxidizing agent, oxidizing and leaching, and solid-liquid separation, and introducing the filtrate to a vanadium extraction step. 5. The processing method according to claim 4, further comprising the step of conducting the filtrate which has been subjected to the solid-liquid separation in the oxidative leaching step to a nickel solvent extraction step.