JP3188138B2 - Recovery method of vanadium from petroleum combustion ash - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering vanadium from petroleum-based combustion ash by a wet method.

[0002]

2. Description of the Related Art Conventionally, as a method for recovering vanadium from petroleum-based combustion ash by a wet method, a treatment solution obtained by mixing combustion ash with water, adding an appropriate amount of sulfuric acid to elute vanadium in the ash, or a vanadium compound is used. It is intended for slurry liquid containing. For example, a method in which the pH of a solution is adjusted to 7 to 9, vanadium is precipitated in the form of hydroxide VO (OH) ₂ , and the precipitate is separated and recovered (JP-A-60-19086 and JP-A-60-19086). No. 46930), ammonium metavanadate NH ₄ by addition of ammonia and air oxidation.
A method for producing VO ₃ and separating and recovering this precipitate (JP-A-61-171582 and JP-A-62-2984)
No. 89), and addition of ferrous sulfate and pH adjustment (8 to
9) A method of producing hydroxide VO (OH) ₂ and coprecipitating it with Fe to recover it (JP-A-59-1038)
No. 9) has been proposed. Further, in addition to the above methods, an adsorption method using an ion exchange resin (chelate resin) (Japanese Patent Application Laid-Open No. Sho 50-66494), a method by electrolytic treatment of a vanadium-containing solution (Japanese Patent Application Laid-Open No. 53-56116), and the like have been proposed. At present, however, the only plant operating at the actual plant is the Kashima Kita Joint Thermal Power Plant process.

[0003]

The conventional method is to solve the problem in solution.
Vanadium ion is converted to VO (OH)_TwoOr NH_FourVO_Three
This method has the following problems.
That is, VO (OH) _TwoRecovery as pH adjustment (7
~ 9), but form hydroxide flocs
To separate it into a high-concentration solution of vanadium.
Is unsuitable, and Fe, Mg, etc.
The problem that the purity of vanadium to be recovered is low because it sinks
There is. Also, NH_FourVO_ThreeAs V in the undiluted solution
O_Two ⁺VO _Three ^-Alkali oxidation to NH and NH_FourAnti
Generated by high-temperature heating (70 ° C or higher)
A long reaction time (1 hour or more) is required, and cooling
Energy consumption is extremely large due to separation and recovery
There is a problem.

An object of the present invention is to provide a method capable of recovering vanadium from petroleum-based combustion ash which has solved the above-mentioned problems in the conventional method. That is, vanadium of high purity can be recovered by a reaction at room temperature, and vanadium can be effectively separated even from a high-concentration vanadium solution. Therefore, the same method that requires extremely little water for dissolving and mixing fuel ash is provided. What you want to do.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a petroleum-based combustion ash.
Sulfuric acid and hydrazine are added to the mixture of water and water.
The pH of the mixture to 2-3 and the ORP to 200-4.
00mV to control the dissolution rate of vanadium from the combustion ash.
After solids are separated and removed from the mixture, the solids
Add ammonia water and hydrazine to the separated solution to
PH of the solution is 5-7, ORP is -100-100m
V to control vanadium ions to V_TwoO _FourOr V_TwoO
_Four・ 2H_TwoIt is characterized by being precipitated as O and collected.
This method recovers vanadium from petroleum-based combustion ash.

That is, in the present invention, in order to increase the elution rate of vanadium contained in petroleum-based combustion ash, sulfuric acid is added to lower the pH value of the solution to 2-3, and hydrazine is added as a reducing agent to the solution. Is reduced to 200 to 400 mV. A method of increasing the vanadium elution rate by minimizing the amount of water mixed with the raw material ash (for example, the ratio of the amount of water 2 to the amount of ash 1) is adopted. There is no means for eluting vanadium by mixing with a large amount of water.

Next, the solid solution of the mixture from which vanadium has been eluted is solidified.
Remove the form (unburned carbon and insolubles) by centrifugation, etc.
After removal, add ammonia water to adjust the pH of the solution to 5-7.
Hydrazine as a reducing agent
Further, the ORP of the solution was reduced to -100 to 100 mV.
Vanadium ion_TwoO_FourOr V_TwoO_Four・ 2H
_TwoOxidized to the form of O_TwoO_FourOr V
_TwoO_Four・ 2H_TwoThis is to separate and recover the O precipitate.

[0008]

FIG. 3 shows a phase diagram of vanadium in water (Po
urbaix: pH-ORP diagram). The horizontal axis represents the pH value, and the vertical axis represents the ORP (oxidation-reduction potential). State A is a position when the raw ash is dissolved in water. In the present invention, the state A is transferred to state C via state B, and vanadium is recovered in state C.

In this diagram, V ₂ O ₄ (vanadium tetroxide) is represented by a hatched area (pH = 4.6-5.8, OR).
(P = 0 to 180 mV), the solubility becomes the lowest and a large amount of precipitate is formed. The further away from this range, the greater the solubility of V ₂ O ₄ and V (-4), V (-2),
The outer line of V (0) represents the permutation. Note that V
(-4) is a tetravalent vanadium ion, V (-2) is a divalent vanadium ion, and V (0) is a zero-valent vanadium ion, that is, a vanadium metal.

When a transition operation from state A to state B is performed, V
_The range in which ₂ O ₄ is deposited is avoided, and therefore, the amount of vanadium in the liquid as vanadium ions increases. As described above, in the operation for shifting from state B to state C, V ₂ O ₄ is most stably present as a solid (precipitate) and vanadium is efficiently separated and recovered by utilizing its low solubility. It is thought that it can be done. In addition, V ₂ O ₄ (or V ₂ O
₄ · 2H ₂ O) deposition conditions are slightly shifted as described below.

Referring to FIG. 1, the basic system configuration and processing of the present invention will be described. The combustion ash (raw material ash) is put into the dissolution tank 1 together with the working water (or city water), and the ash and water are mixed and stirred by the stirrer 2. Sulfuric acid is injected into the dissolving tank 1 from the sulfuric acid tank 10 by the pump 9 via the electromagnetic adjustment valve 8, and the injection amount is adjusted by the pH meter 4 and the controller 6 installed in the dissolving tank 1 or a line behind the same. The electromagnetic adjustment valve 8 adjusts the opening in conjunction with the controller 6. The dissolution tank 1 has a pump 11 from a reducing agent tank 12.
Is injected through the electromagnetic adjustment valve 7, and the amount of the injection is adjusted by the ORP meter 3 and the controller 4 installed in the dissolution tank 1 or a line behind the dissolution tank 1. The electromagnetic adjustment valve 7 adjusts the opening in conjunction with the controller 5. The dissolved liquid is sent to the centrifugal separator 14 by the slurry transport pump 13 where the insoluble solids (unburned carbon and insolubles) are separated, and the filtrate from which the insoluble solids are removed is sent to the reaction tank 15.

Ammonia is injected into the reaction tank 15 from the alkaline tank 24 by the pump 23 through the electromagnetic control valve 22, and hydrazine as a reducing agent is simultaneously injected from the hydrazine tank 26 by the pump 25 through the electromagnetic control valve 21. The reaction proceeds with stirring by the stirrer 16. The injection amounts of ammonia and hydrazine are controlled by a pH meter 17, a controller 19, an ORP meter 18, and a controller 20 installed in the reaction tank 15 or in a line behind the controller, respectively.
The signal is transferred to the electromagnetic adjustment valves 21 and 22 connected to the controller to adjust the opening degree. The reaction solution containing V ₂ O ₄ generated by the reaction is sent to a centrifugal separator 28 by a slurry transport pump 27, and a solid content (V ₂ O ₄ cake) is collected there.

[0013]

FIG. 2 shows a basic tester on a beaker scale, for which the principle was confirmed, for the chemical support of the present invention. Further, the test results are shown in Tables 1 and 2 below. FIG. 2A shows an ash dissolution test and an oxidation reaction test device.
(500 cc) 31, a rotating machine 33, and a rotor 32. At the time of dissolving the ash, ash and water were mixed and charged, and sulfuric acid and hydrazine were injected into the ash, and the test was performed. At the time of the oxidation reaction, ammonia and hydrazine were injected into the solution, and the test was performed.

After the test, the solid content is separated by filtration using a filtration test apparatus shown in FIG. 2 (b). Millipore filter (0.
45 μ) 35 was incorporated, and the liquid of the beaker 31 was poured into the funnel 34, and the filtrate 41 was placed in the beaker 37 installed in the vacuum vessel 36.
Collect. The properties of the solids 40 trapped on the Millipore filter 35 were investigated as recovered solids.

Table 1 shows the results of the ash dissolution test. The dissolution conditions were as follows: the mixing ratio of ash to water at room temperature under stirring for 1 hour;
The V elution rate was tested with varying H and ORP. As a result, low pH (pH = 2 to 3) by adding sulfuric acid, and reduction of ORP by adding hydrazine (ORP = 200 to 400 m)
Under the condition V) (test numbers 5 to 8), the dissolution rate of vanadium was 86% or more.

[0016]

[Table 1]

Table 2 shows the results of the oxidation reaction of the vanadium eluate at room temperature for 1 hour. The pH was 5 to 7 and the ORP was -100 to 100 by ammonia injection and hydrazine injection.
Under the condition of 100 mV, the V ₂ O ₄ deposition rate was 90% or more.

[0018]

[Table 2]

[0019]

According to the present invention, the following effects can be obtained. (1) During the elution of vanadium containing ash, sulfuric acid as a pH adjuster and hydrazine as a reducing agent are added.
By controlling the pH to be in the range of 2-3 and the ORP in the range of 200-400 mV, vanadium can be dissolved in the liquid at a high rate. (2) When recovering vanadium from this eluate, ammonia and hydrazine were added, and the pH was 5 to 7,
V ₂ vanadium ions by controlling the range of P = -100~100mV O ₄ or V ₂ O ₄ · 2H ₂
It can be recovered at a high rate as O solids. (3) The method of the present invention can treat raw ash at a high concentration, and equipment and tanks can be compact. Also, since the operation is performed at room temperature, no heat energy is required,
It is a very economical system.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic flow of the present invention.

FIG. 2 shows vanadium dissolution, V _{2 according to} a specific embodiment of the present invention.
FIG. _{4 is} an explanatory diagram of a basic test device for O ₄ generation and separation.

FIG. 3 is a state principle diagram of vanadium in an aqueous solution.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Setsuo Tokunaga 2-1-1 Shinhama, Arai-machi, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Inside the Takasago Research Laboratory (72) Inventor Toru Eito Toichi Wadazaki, Hyogo-ku, Kobe-shi, Hyogo 1-1 1-1 Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Iwao Nakayasu 2-9-19 Aramachi, Aramachi, Takasago City, Hyogo Prefecture Takaishi Engineering Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) C22B 1/00-61/00

Claims (1)

(57) [Claims] 1. A mixture of petroleum-based combustion ash and water is added with sulfuric acid and hydrazine to adjust the pH of the mixture to 2
To 3, and the ORP was controlled to 200 to 400 mV to increase the elution rate of vanadium from the combustion ash to separate and remove solids from the mixed solution. Then, ammonia water and hydrazine were added to the solid separated solution. To bring the pH of the solution to 5-7,
The method for recovering vanadium from petroleum-based combustion ash and recovering by controlling the -100~100mV vanadium ions the ORP precipitated as V ₂ O _4, or _{V 2 O 4 · 2H 2 O} .