JPH11124639A - Method for separating and recovering metal from waste and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for separating and recovering high-purity Ni from wastes and the device therefor. SOLUTION: Combustion ash, water and sulfuric acid are added to a dissolution tank 1, mixed and agitated to elute the Ni component and V component, hydrazine is added to the liq. mixture in a reduction tank 2, ammonium sulfate is added to the reduction tank 2 until >=30 wt.% concn. from a feeder 3 while using a detector 4 and controlling with a controller 5, then the liq. mixture is supplied to a centrifugal separator 6, the liq. phase (V-contg. phase) is discharged outside the system, the solid phase (precipitate, Ni-contg. phase) is introduced into a dissolution tank 7 and mixed with water to form the soln., the soln. is supplied to a centrifugal separator 8 and separated into solid and liq., the solid phase is discharged outside the system, the liq. phase (contg. Ni component) is sent to an adsorption tower 9, in which the V ion remaining in a minute amt. is adsorbed and removed, then fed to the cathode-side storage tank of an electrolyzer 10 and electrolyzed, and metallic Ni is deposited on the cathode and recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for separating and recovering metals such as Ni from waste such as petroleum-based combustion ash.

[0002]

2. Description of the Related Art When separating and recovering trace metals such as Ni from waste such as petroleum-based combustion ash, usually, the combustion ash and water are mixed, and sulfuric acid is added to dissolve the Ni component. After that, a wet method of recovering Ni from the mixed liquid by various methods is applied.

As a method for recovering Ni from such a mixed solution, for example, Ni is extracted from the mixed solution by using an extraction solvent or the like.
Method for recovering waste (Resource Processing Technology, Vol. 37, No. 2, (199
0); Pollution, Vol. 25, No. 5, (1990))
As disclosed in, for example, JP-A-66494, a method in which a mixed solution is brought into contact with a polyamine-type chelate resin, and the Ni component is adsorbed on the chelate resin and recovered,
As disclosed in JP-A-42327 and the like, a method in which hydrogen sulfide is added to a mixed solution to precipitate and recover Ni content as nickel sulfide, and as disclosed in JP-A-61-215219 and the like. , Add hydroxide to the mixture and add N
There is a method of precipitating and recovering the i component as nickel hydroxide.

[0004]

In wastes such as petroleum-based combustion ash, trace metals such as V and Ni are contained as oxides (V ₂ O ₅ and NiO) by a high-temperature oxidation reaction. ing. Since such oxides hardly dissolve in water, when the trace metal components are eluted from the combustion ash into water, sulfuric acid is added to a mixture of the combustion ash and water to ionize the trace metal. Dissolved in water (the addition of sulfuric acid decomposes the above oxides into VOSO ₄ and N
It is considered that trace metal content is dissolved in water as it becomes ISO ₄ . ).

When the trace metal is eluted into water in this way, the Ni and V components are simultaneously dissolved in the water. Therefore, it is necessary to selectively recover the Ni and V components from the mixed solution. Becomes difficult. For this reason, the Ni component and the V component are separated and recovered from the mixed liquid by the various methods described above.

However, in the above-mentioned conventional various methods, a large amount of impurities such as V are mixed into the recovered Ni, and the Ni cannot be recovered with high purity.

In view of the above, an object of the present invention is to provide a method and an apparatus for separating and recovering metals such as Ni with high purity from waste such as petroleum-based combustion ash. did.

[0008]

In order to solve the above-mentioned problems, a method for separating and recovering metal from waste according to the present invention is a dissolving step of mixing waste containing Ni and V, water and sulfuric acid. Adjusting the ammonium sulfate in the mixture to a predetermined concentration to precipitate Ni, and separating the precipitated Ni from the mixture.
An i-component separation step, a Ni-component solution-forming step of dissolving the separated Ni component in water to form a solution, and a Ni-recovering step of electrolyzing the solution to precipitate metal Ni are performed.

In the above-mentioned method for separating and recovering metal from waste, an insoluble matter removing step of dissolving the solid phase in water to remove remaining insoluble matter; And a V ion removing step of removing V ions from.

In the above-mentioned method for separating and recovering metal from waste, the predetermined concentration in the step of precipitating Ni may be 30 or less.
It is characterized by being at least wt%.

An apparatus for separating and recovering metal from waste according to the present invention for solving the above-mentioned problems includes Ni and V.
Dissolving means for mixing waste containing water and sulfuric acid,
Ni content precipitation means for adjusting the ammonium sulfate in the mixed solution to a predetermined concentration to precipitate Ni content, Ni content separation means for separating the precipitated Ni content from the mixed solution,
It is characterized by comprising: a Ni component solution-forming means for dissolving the separated Ni component in water to form a solution; and a Ni recovery means for electrolyzing the solution to deposit metal Ni on the electrode.

In the above-mentioned apparatus for separating and recovering metal from waste, insoluble matter removing means for removing insoluble matter remaining in the solution, and removing V ions from the solution from which the insoluble matter has been removed. V ion removing means.

In the above-mentioned apparatus for separating and recovering metal from waste, the predetermined concentration of the Ni content precipitating means may be 30 or less.
It is characterized by being at least wt%.

In the above-mentioned apparatus for separating and recovering metal from waste, the electrode of the Ni recovery means is made of stainless steel, and the electrode has a surface roughness of 5 μm or less.

[Effect] Usually, waste such as petroleum-based combustion ash includes sulfurous acid gas (SO
₂ ) is reacted with ammonia (NH ₃ ) to recover the sulfurous acid gas as ammonium sulfate ((NH ₄ ) ₂ SO ₄ : solid), thereby reducing the concentration of the sulfurous acid gas in the exhaust gas. Contains ammonium sulfate. When such combustion ash is mixed with water and dissolved, the mixed solution becomes a solution of ammonium sulfate to form a solution of N 2
The i and V components become soluble. When the ammonium sulfate in the mixed solution is adjusted to a predetermined concentration, Ni in the mixed solution precipitates as a double salt compound of nickel sulfate and ammonium sulfate [(NH ₄ ) ₂ Ni (SO ₄ ) ₂ ],
Since V in the mixed solution is present in the mixed solution in the form of ions without forming a double salt compound like Ni, by separating the mixed solution into a solid phase and a liquid phase, ,
The Ni component and the V component can be easily separated.

When the Ni component and the V component are separated in this manner, the precipitation amount of the double salt compound greatly varies depending on the concentration of ammonium sulfate in the mixed solution. By appropriate adjustment, the amount of precipitation of the double salt compound can be increased, that is, the efficiency of recovering Ni can be increased. FIG. 3 shows the relationship between the concentration of ammonium sulfate in such a mixed solution and the solubility of the double salt compound.

As can be seen from FIG. 3, the Ni double salt compound is well soluble in water and shows a solubility of 10 wt% or more.
As the concentration of ammonium sulfate increases, the solubility decreases. When the concentration of ammonium sulfate becomes 30 wt% or more, the solubility decreases significantly. Therefore, while suppressing the amount of water when dissolving the combustion ash in water as much as possible (for example, the amount of water is about twice the amount of the combustion ash), ammonium sulfate is added so that the concentration of ammonium sulfate in the mixed solution becomes 30 wt% or more. If added, most of the above-mentioned Ni double salt compound is precipitated, and the recovery efficiency of Ni content can be increased.

After the Ni double salt compound formed and precipitated as described above is taken out of the mixed solution to separate Ni and V components, the precipitate is dissolved in water again to obtain Ni.
The nickel sulfate (NiSO ₄ ) or a double salt compound of nickel sulfate and ammonium sulfate [(NH ₄ ) ₂ Ni (SO ₄ )
_After eluted in water to form a solution as in ₂ ], the solution is electrolyzed to precipitate and recover metallic Ni.

In this electrolysis, if the material of the electrode (cathode) for precipitating and recovering the metal Ni is stainless steel and the surface roughness of the electrode is 5 μm or less, it becomes difficult for the metal Ni to adhere to the electrode surface. In addition, the metal Ni can be easily collected without falling on the surface of the electrode, and can be easily collected.

Prior to electrolysis of the solution, insoluble materials such as carbon and silica mixed in the solution are removed, and then V ions (Ni) slightly remaining in the solution are removed. If the precipitation inhibitory factor) is adsorbed and removed (10 ppm or less) with an ion exchange resin, the recovery rate of metallic Ni can be increased.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and an apparatus for separating and recovering metal from waste according to the present invention will be described with reference to FIGS. FIG. 1 is an overall schematic configuration diagram of the device, and FIG. 2 is a detailed explanatory diagram of an arrow II portion in FIG.

In FIG. 1, 1 is a dissolving tank, 2 is a reducing tank,
3 is a feeder, 4 is a detector, 5 is a controller, 6 is a centrifuge, 7 is a re-dissolving tank, 8 is a centrifuge, 9 is an adsorption tower, and 10 is an electrolyzer.

The melting tank 1 can mix and stir the waste ash, water and sulfuric acid therein. The reduction tank 2 can agitate the mixed solution in the dissolution tank 1 inside. The feeder 3 can supply ammonium sulfate into the reduction tank 2. The detector 4 can measure the concentration of ammonium sulfate in the reduction tank 2. The controller 5 can control the feeder 3 based on a signal from the detector 4 so that the concentration of ammonium sulfate in the reduction tank 2 becomes a predetermined concentration.

The centrifugal separator 6 can separate the precipitate generated in the reduction tank 2 from the mixed solution.
The re-dissolution tank 7 can mix and stir the sediment separated by the centrifuge 6 and water inside. The centrifugal separator 8 can remove impurities such as carbon and silica mixed in the solution dissolved in the re-dissolution tank 7. The adsorption tower 9 is filled with an ion exchange resin, and the solution from which insoluble matter has been removed by the centrifugal separator 8 is fed into the adsorption tower 9, and V ions (Ni (Precipitation inhibitory factor) can be adsorbed and removed. Electrolysis device 1
Reference numeral 0 indicates that the solution flowing through the adsorption tower 9 is fed into the inside to electrolyze the solution, and has a structure as shown in FIG.

In FIG. 2, 11 is an electrolytic cell, 12 is a diaphragm, 13 is a valve, 14a is a cathode, 14b is an anode, 15
a is a cathode side liquid storage tank, 15b is an anode side liquid storage tank, 16a is a cathode side pump, 16b is an anode side pump, and 17 is a DC power supply.

The electrolytic cell 11 is internally partitioned into a cathode-side electrolytic cell 11a and an anode-side electrolytic cell 11b by a diaphragm 12, and a valve 13 is provided at a lower end of the funnel-shaped cathode-side electrolytic cell 11a side. Have been. The cathode 14a is disposed in the cathode-side electrolytic cell 11a of the electrolytic cell 11, is made of stainless steel, and is polished so that the surface roughness is 5 μm or less. The anode 14b is connected to the electrolytic cell 11
Is disposed in the anode-side electrolytic cell 11b.

The cathode-side storage tank 15a is connected to the cathode-side electrolysis tank 11a of the electrolysis tank 11, stores the solution from the adsorption tower 9, and sends out the electrolyzed solution and the generated hydrogen gas to the outside of the system. You can do it. The anode-side storage tank 15b is connected to the anode-side electrolysis tank 11b of the electrolysis tank 11 so that oxygen gas generated by electrolysis can be sent out of the system. The cathode-side pump 16a feeds and circulates the solution in the cathode-side liquid storage tank 15a into the cathode-side electrolytic cell 11a of the electrolytic cell 11.
The anode-side feed pump 16b feeds the solution in the anode-side liquid storage tank 15b into the anode-side electrolytic tank 11b of the electrolytic tank 11 for circulation.

In this embodiment, the dissolving means is constituted by the dissolving tank 1 and the like, and the Ni content precipitating means is constituted by the reducing tank 2, the feeder 3, the detector 4, the controller 5 and the like. 6, etc., constitute a Ni separation means, and the re-dissolving tank 7, etc. constitute a Ni separation solution means,
The centrifugal separator 8 and the like constitute an insoluble matter removing means, the adsorption tower 9 and the like constitute a V ion removing means, and the electrolytic device 10 and the like constitute a Ni collecting means.

Next, a method of recovering Ni from petroleum-based combustion ash using the thus constituted apparatus will be described. The combustion ash is put into the dissolving tank 1, water and sulfuric acid are added in predetermined amounts, and mixed and stirred to dissolve Ni and V in the combustion ash in water. This mixed solution is fed to the reduction tank 2 and hydrazine is added to reduce V. At the same time, the concentration of ammonium sulfate in the mixed solution is detected by the detector 3 and the concentration is determined to be a predetermined value (3
(0 wt% or more) from the feeder 4 while adding ammonium sulfate to the reduction tank 2 while controlling the same with the controller 5.

When the concentration of ammonium sulfate in the mixed solution reaches a predetermined concentration (30 wt% or more), the mixed solution is fed to a centrifugal separator 6 for solid-liquid separation, and the liquid phase (containing V Phase) is discharged out of the system, and a water-containing cake-like solid phase (precipitate: Ni-containing phase) is put into a re-dissolution tank 7, and water is added to dissolve again to form a solution. This solution is fed to the centrifugal separator 8 and subjected to solid-liquid separation again to remove the solid phase (insoluble impurities such as carbon and silica) out of the system. After being supplied to the adsorption tower 9 and adsorbing and removing a slight residual V ion (an inhibitor of Ni precipitation), the V ion is supplied to the cathode-side liquid storage tank 15 a of the electrolysis apparatus 10.

The solution fed to the cathode-side liquid storage tank 15a is
The cathode-side electrolyzer 11a of the electrolyzer 11 is operated by the cathode-side pump 16a.
To the cathode 14a and the anode 14b through the diaphragm 12.
Is electrolyzed between When the solution is electrolyzed in this manner, metallic Ni precipitates on the surface of the cathode 14a, and spontaneously peels off from the surface of the cathode 14a and deposits in the cathode-side electrolytic cell 11a. After the metal Ni has been deposited to some extent, the valve 13 is opened to collect the metal Ni.

Therefore, according to such a method and apparatus for separating and recovering metal, the Ni and V components in the combustion ash can be efficiently and reliably separated from each other. Pure metal Ni can be recovered.

Prior to electrolyzing the solution containing Ni, insoluble impurities such as carbon and silica are removed and V ions (a factor inhibiting Ni deposition) which remain slightly are also removed. As a result, the recovery rate of metallic Ni can be increased.

The material of the cathode 14a of the electrolytic device 10 is stainless steel, and the surface roughness of the cathode 14a is 5 μm.
Therefore, the metal Ni is less likely to adhere to the surface of the cathode 14a, and is spontaneously peeled and dropped without being stacked on the surface of the cathode 14a, and is deposited below.
i can be easily collected, and the cathode 14a
Can be used repeatedly without replacement, thereby improving work efficiency and reducing costs.

[0035]

EXAMPLES In order to confirm the effects of the method and apparatus for separating and recovering metals from waste according to the present invention, the following experiments were conducted.

[Experiment 1: Precipitation rate of Ni content and V content with respect to ammonium sulfate concentration of mixed solution] Based on the method and apparatus of the above-described embodiment (combustion ash throughput: 30 k)
g / h), the precipitation ratio of Ni content and V content with respect to the concentration of ammonium sulfate in the mixture was examined. Table 1 shows the results.

[0037]

[Table 1]

As can be seen from Table 1, as the concentration of ammonium sulfate in the mixture increases, the precipitation rate of the Ni compound increases, and the concentration of ammonium sulfate decreases to 35 wt%.
Then, although 98% of the Ni compound was precipitated, it was clarified that the precipitation rate of the V compound did not change, and the V compound hardly formed a precipitate as compared with the Ni compound. From this, it was confirmed that by adjusting the concentration of ammonium sulfate in the mixture, the Ni component and the V component could be efficiently and reliably separated.

[Experiment 2: Removability of Precipitated Metal Ni] The releasability of precipitated metal Ni in the material and surface roughness of the cathode of the electrolytic device was examined based on the method and apparatus of the above-described embodiment. Table 2 shows the results.

[0040]

[Table 2]

As can be seen from Table 2, when the material is nickel, the releasability deteriorates regardless of the surface roughness. However, when the material was stainless steel, the releasability was slightly poor when the surface roughness was 20 μm, and the releasability was good when the surface roughness was 5 μm. From this, it was confirmed that when the material of the cathode of the electrolytic device was stainless steel and the surface roughness was 5 μm or less, the precipitated metal Ni could be easily recovered.

[Experiment 3: Confirmation of Purity of Recovered Metal Ni] Based on the results of Experiment 2 described above, it was obtained based on the method and apparatus of the above-described embodiment using a cathode made of stainless steel having a surface roughness of 5 μm. Solution (Ni concentration: about 2000p
pm) and the purity of the metallic Ni recovered by electrolysis. Table 3 shows various conditions and results of the electrolysis.

[0043]

[Table 3]

As can be seen from Table 3, the recovered metal N
i had a purity of 95% or more in all cases. From this, it was confirmed that according to the method and the apparatus based on the above-described embodiment, metal Ni can be recovered with high purity.

[0045]

According to the method and apparatus for separating and recovering metal from waste according to the present invention, the mixed solution of waste, water and sulfuric acid is adjusted so that the concentration of ammonium sulfate becomes a predetermined value. Precipitate and fractionate the Ni content, this Ni
The metal Ni was precipitated and recovered by dissolving the metal in water again and electrolyzing it, so that the Ni and V components in the waste were efficiently and reliably separated from the waste in a high yield. High-purity metal Ni can be recovered.

Further, prior to the electrolysis, insolubles remaining in the solution were removed, and V ions (inhibitors of Ni precipitation) remaining slightly in the solution were removed. The recovery rate of metallic Ni can be increased.

Further, since the concentration of the ammonium sulfate in the mixed solution is set to 30% by weight or more, almost all of the Ni content can be precipitated without substantially precipitating the V content, and the recovery efficiency of the Ni content can be improved. Can be.

Further, since the electrode material of the Ni recovery means is made of stainless steel and the surface roughness of the electrode is set to 5 μm or less, metal Ni hardly adheres to the surface of the electrode and is laminated on the electrode surface. The metal Ni can be easily separated and fall down without being deposited, thereby facilitating the recovery of metal Ni, and can be used repeatedly without replacing the electrode, thereby improving work efficiency and reducing cost. Reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an embodiment of an apparatus for separating and recovering metal from waste according to the present invention.

FIG. 2 is a detailed explanatory view of an arrow II part in FIG. 1;

FIG. 3 is a graph showing the relationship between the concentration of ammonium sulfate in a mixed solution and the solubility of the double salt compound.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dissolution tank 2 Reduction tank 3 Feeder 4 Detector 5 Controller 6 Centrifuge 7 Re-dissolution tank 8 Centrifuge 9 Adsorption tower 10 Electrolysis device 11 Electrolysis tank 11a Cathode side electrolysis tank 11b Anode side electrolysis tank 12 Diaphragm 13 Valve 14a Cathode 14b Anode 15a Cathode-side storage tank 15b Anode-side storage tank 16a Cathode-side pump 16b Anode-side pump 17 DC power supply

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Keiko Moriguchi, Inventor 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Inside Kansai Electric Power Co., Inc. (72) Keiichi Yasuda 1-2-2, Hirabayashikita, Suminoe-ku, Osaka, Osaka −65 Kanden Kako Co., Ltd. Osaka Works (72) Inventor Keimichi Yamamori 3-95, Showa-dori, Amagasaki City, Hyogo Prefecture Kanden Kako Co., Ltd. No. Within the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. No. 1 Inside the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. The No. 1 Mitsubishi Heavy Industries, Ltd. Kobe Shipyard & Machinery Works (72) inventor Fujita, Toru, Hyogo Prefecture, Kobe City, Hyogo-ku, Wadasaki-cho, chome No. 1 in the No. 1 Mitsubishi Heavy Industries, Ltd. Kobe Shipyard & Machinery Works

Claims (7)

[Claims] 1. A dissolving step of mixing waste containing Ni and V, water and sulfuric acid, a Ni-part precipitation step of adjusting ammonium sulfate in the mixed solution to a predetermined concentration to precipitate Ni part. A Ni separation step of separating the precipitated Ni from the liquid mixture; a Ni separation solution of dissolving the separated Ni in water to form a solution; and electrolyzing the solution to deposit metallic Ni And recovering Ni from the waste. 2. The method according to claim 1, further comprising performing an insoluble matter removing step of removing insoluble matter remaining in the solution, and a V ion removing step of removing V ions from the solution from which the insoluble matter has been removed. Claim 1
3. The method for separating and recovering metals from wastes described in 1. above. 3. The method for separating and recovering metals from waste according to claim 1, wherein the predetermined concentration in the Ni precipitation step is 30% by weight or more. 4. A dissolving means for mixing waste containing Ni and V, water and sulfuric acid, and a Ni content precipitating means for adjusting ammonium sulfate in the mixed solution to a predetermined concentration to precipitate Ni content. Ni separation means for separating the precipitated Ni from the mixed solution, Ni separation solution for dissolving the separated Ni in water to form a solution, and electrolyzing the solution to form a metal Ni electrode. An apparatus for separating and recovering metal from waste, comprising: means for recovering nickel from the waste. 5. An insoluble matter removing means for removing insoluble matter remaining in the solution, and a V ion removing means for removing V ions from the solution from which the insoluble matter has been removed. The apparatus for separating and recovering metal from waste according to claim 4. 6. The apparatus for separating and recovering metal from waste according to claim 4, wherein the predetermined concentration of the Ni content precipitation means is 30 wt% or more. 7. The waste material according to claim 4, wherein the electrode of the Ni recovery means is made of stainless steel, and the surface roughness of the electrode is 5 μm or less. Metal separation and recovery equipment.