JP2016164310A - Method of recovering transition metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that recovers high-purity group 5 and/or group 6 transition metal at a low cost.SOLUTION: A method of recovering transition metal comprises a step of electrolyzing a raw material mixture comprising at least one of V, Nb, Ta, Cr and Mo components, using an electrolyte comprising alcohol amine.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for recovering a transition metal, and more particularly to a method for recovering a Group 5 and / or Group 6 transition metal.

  As a metal recovery method, usually, a process of pulverizing a scrap containing the metal and then dissolving with alkali is used. However, in the recovery of Group 5 and Group 6 transition metals, Group 5 and Group 6 transition metals are very hard and highly resistant to chemicals. It is difficult to. Therefore, it is a regular method to dissolve and recover the Group 5 and Group 6 transition metals by oxidizing them with a strong treatment such as an alkali molten salt.

  On the other hand, for example, since molybdenum (Group 6 transition metal) used targets and mill ends are originally of high purity, the use of molten salt treatment or pulverization, which is a general treatment as described above, reduces the purity. It will be drastically reduced. Therefore, in order to purify the metal, the treatment process tends to be complicated, such as requiring multistage purification or ion exchange treatment.

  As a technique for dissolving the metal, there is electrolysis. For example, in Patent Document 1, as an electrolytic processing liquid composition intended to carry out either an electrolytic etching process or an electrolytic oxide film removal process, Basically, among (1) water-soluble electrolyte, (2) polarization improver, and (3) corrosion inhibitor (inhibitor), the water-soluble electrolyte of (1) is used as a basis, and (2) to (3) By using any one or a combination of two or more of the above, it is possible to perform electrolysis while suppressing the growth of a viscous liquid formed of a metal ion electrolyzed and an electrolyte component in the vicinity of the anode surface and a viscous liquid layer. An electrolytic etching treatment method is disclosed. (1) As a water-soluble electrolyte, one or more selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid or their ammonium, potassium, sodium salt, potassium hydroxide, (2) Polarization As an improver, one or more selected from aminocarboxylic acids and salts thereof, ethanolamines, carboxylic acids or salts thereof, and (3) dehydrated cyclized ethanol derivatives as corrosion inhibitors (inhibitors) It is disclosed that one or two or more selected from amine compounds containing nitrogen, nitrogen-containing heterocyclized bases, and thiourea derivatives are used. And according to this, it describes that the electrolytic solution composition which performs these electrolytic processing very effectively can be provided when implementing the electrolytic processing including electrolytic etching and electrolytic oxide film removal.

  Patent Document 2 discloses that 0.1% by weight or more of phosphoric acid, citric acid, tartaric acid, oxalic acid, malic acid, acetic acid, gluconic acid, glycolic acid, succinic acid, etc. 0.1% by weight or more of triethanolamine, diethanolamine and monoethanolamine in one or more aqueous solutions of the group consisting of and sulfuric acid, and each salt group of these acids such as sodium, potassium and ammonium An electrolytic solution used in an electrolytic polishing method for stainless steel, characterized in that one or more of them are blended is disclosed. And according to this, in the electrolytic polishing method for the stainless steel surface, it can be used in alternating current, direct current and AC / DC superposition, and electrolysis that improves corrosion resistance performance not only in austenitic stainless steel but also in martensitic and ferritic stainless steel. It is described that a liquid can be provided.

Patent Document 3 discloses a method for electrolytic polishing a surface of a metal selected from iron, tungsten, light metals, and alloys of these metals using an electrolytic solution, and the electrolytic solution includes methanesulfonic acid and A general formula C _n H _2n (OH) ₂ , an aliphatic diol represented by n = 2 to 6 and a general formula C _m H _2m-1 OH, m = 5 to 8 and a group consisting of alicyclic alcohols represented by An electropolishing method comprising at least one selected alcohol compound is disclosed. And according to this, it is described that it is possible to provide a substantially harmless method for work safety and environmental protection suitable for electropolishing the surfaces of iron, tungsten, light metals and their alloys. Has been.

  Furthermore, Patent Document 4 discloses an electrolytic elution method for eluting platinum by electrolyzing platinum in an electrolytic solution as an anode, wherein the electrolytic solution is a hydrochloric acid solution of 8 to 11.5 N, and electrolytic conditions As a method, a method of eluting the platinum electrode by applying a current having a liquid temperature of 60 to 80 ° C. and a current density of 60 to 100 A / dm 2 is disclosed. According to this, it is described that a method of efficiently dissolving platinum that is chemically stable and not dissolved by an electrolytic method can be provided.

JP-A-8-49100 JP 2007-277682 A JP 2008-121118 A JP 2011-131282 A

  As described above, a technique for dissolving various metals by an electrolytic method is known. However, there is still room for improvement in a technique for recovering a transition metal with high purity at a low cost. In order to recover Group 5 and Group 6 transition metals with high purity, for example, it is conceivable to use ammonium nitrate (ammonium nitrate), which is an inorganic solution, as an electrolytic solution. To adjust the pH of the electrolyte. However, ammonium nitrate itself has high explosiveness at high concentrations, so it is necessary to control the concentration during electrolysis. Furthermore, since ammonia also has a concentration change due to volatilization in the electrolysis temperature range, concentration management or the like is indispensable, and a running cost is required for recovery equipment, control equipment, and the like. Further, in the recovery of transition metals from originally high-purity materials such as used targets and mill ends, an impurity-free treatment method is required.

  Then, this invention makes it a subject to provide the method of collect | recovering high purity group 5 and / or group 6 transition metals at low cost.

In order to solve the above-mentioned problems, the present inventor has eagerly studied an electrolytic solution capable of high-purity electrolysis of Group 5 and Group 6 transition metals, and as a result, has found an electrolytic solution using alcohol amine. Alcoholamine does not contain impurities such as Na, K, Fe and S, has a relatively high boiling point, and an aqueous solution containing several percent is safe. Furthermore, since the voltage resistance is high and stable, and the pH dependency is low, it is easy to control during electrolysis, and replenishment by volatilization such as ammonia is not necessary, so that the running cost can be suppressed as a result.
In the inventions related to the electrolytic solutions of Patent Documents 2, 3, and 4, amine is used for the electrolytic solution. However, in Patent Document 2, the electrolyte contains an acid and sulfuric acid that act non-oxidatively on stainless steel such as phosphoric acid, citric acid, tartaric acid, oxalic acid, malic acid, acetic acid, gluconic acid, glycolic acid, and succinic acid. As well as one or two or more aqueous solutions of each of the groups of these salts, such as sodium, potassium, ammonium, etc. of these acids, which are different in configuration from the present invention. Further, Patent Document 3 contains methanesulfonic acid as an essential component, which is disadvantageous in that the structure is different from that of the present invention, and methanesulfonic acid is strongly acidic and very expensive. Moreover, in patent document 4, hydrochloric acid which is a strong acid is contained in electrolyte solution, and a structure differs from this invention.

  In one aspect, the present invention completed on the basis of the above knowledge is electrolyzed using an electrolytic solution containing an alcohol amine for a raw material mixture containing at least one of V, Nb, Ta, Cr and Mo components. It is the recovery method of the transition metal including the process of performing.

  In one embodiment of the method for recovering a transition metal according to the present invention, the alcohol amine is monoethanolamine and / or triethanolamine.

  In another embodiment of the method for recovering a transition metal according to the present invention, the concentration of alcoholamine in the electrolytic solution is 1 to 40 mass%.

  In still another embodiment of the method for recovering a transition metal according to the present invention, electrolysis is performed by adjusting the temperature of the electrolytic solution to 50 ° C. or higher.

  In still another embodiment of the method for recovering a transition metal according to the present invention, the electrolyte solution has a pH of 9 or more.

In still another embodiment of the method for recovering a transition metal according to the present invention, the set voltage in the electrolysis is 30 V or less, and the set current density is 500 A / dm ² or less.

According to the present invention, it is possible to provide a method for recovering high-purity Group 5 and / or Group 6 transition metals at low cost by electrolysis using an electrolytic solution containing an alcohol amine. it can.
More specifically:
(1) By removing impurities such as Na, K, Fe and S in the treatment reaction system, it is possible to recover the Group 5 and / or Group 6 transition metals with high purity without lowering the purity. it can.
(2) From recycled materials, etc., the purity of the Group 5 and / or Group 6 transition metal can be 4N or higher.
(3) Since the electrolytic solution has a high withstand voltage and is stable and has a low pH dependency, it is easy to control during electrolysis and does not require replenishment by volatilization such as ammonia. it can.

It is a schematic diagram of an example of the electrolytic cell shown by embodiment of this invention. The electrolytic solution temperature and the group 5 and / or group 6 transition metal when the group 5 and / or group 6 transition metal scrap is electrolyzed using the electrolytic solution according to the present invention and the conventional electrolytic solution It is a figure which shows the relationship with a dissolution rate. It is a figure which shows the relationship between the constant voltage in electrolysis, and current efficiency.

  Hereinafter, an embodiment of the transition metal recovery method according to the present invention will be described in detail.

  First, a raw material mixture containing at least one of V, Nb, Ta, Cr, and Mo components that are Group 5 and / or Group 6 transition metal components to be treated is prepared. Examples of the raw material mixture include so-called recycled materials obtained by pulverizing V, Nb, Ta, Cr, and Mo scraps. The typical quality of the raw material mixture containing at least one of V, Nb, Ta, Cr and Mo components to be treated in the present invention is as follows: Fe is 0.005 mass%, Ni is 0.003 mass%, Cu exists in each concentration of 0.002 mass%, and the purity of V, Nb, Ta, Cr, and Mo is 99.99 to 99.999 mass%.

Next, an anode, a cathode, and an electrolytic cell including an electrolytic solution are prepared, and the raw material mixture containing at least one of V, Nb, Ta, Cr, and Mo components is electrolyzed using the electrolytic cell.
Although an electrolytic cell is not specifically limited, For example, the structure shown in FIG. 1 may be sufficient. In FIG. 1, a titanium basket is used as an anode, and a raw material mixture containing at least one of V, Nb, Ta, Cr and Mo components is provided in the titanium basket. Titanium baskets are preferred in that they are stable under high voltage, high current and high temperature electrolytic treatment conditions as in the present invention.

  The electrolytic solution contains alcohol amine. Examples of the alcohol amine include triethanolamine, diethanolamine, monoethanolamine, aminopropanol, and methylethanolamine. In particular, monoethanolamine and triethanolamine are preferable in that they are inexpensive.

  The concentration of alcohol amine in the electrolytic solution is preferably 1 to 40 mass%. If the concentration of alcoholamine in the electrolytic solution is less than 1 mass%, the conductivity becomes too low and electrolysis becomes unstable. If the concentration of alcoholamine in the electrolytic solution exceeds 40 mass%, the solubility in water may be exceeded depending on the type of the electrolytic solution, and the concentration becomes higher than necessary, which is disadvantageous in terms of cost. The concentration of alcoholamine in the electrolytic solution is more preferably 2 to 10 mass%.

  The temperature of the electrolytic solution at the time of electrolysis may be room temperature, but higher temperature is better, and it is particularly preferable to adjust to 50 ° C. or higher. This is because the conductivity of the electrolytic solution increases at higher temperatures. Here, FIG. 2 shows the electrolyte temperature and the V, Nb, Ta, Cr when the scraps of V, Nb, Ta, Cr, Mo are electrolyzed using the electrolytic solution according to the present invention and the conventional electrolytic solution. And the relationship with the dissolution rate of Mo. In the figure, the graph of the result of electrolysis in the electrolytic cell using the electrolytic solution according to the present invention is described as the present PAT bath, and the graph of the result of electrolysis in the electrolytic cell with the conventional electrolytic solution is shown as the conventional bath. It is described. In this PAT bath, a 10% aqueous solution of monoethanolamine is used as an electrolytic solution, and electrolysis is performed at a constant voltage of 10V. On the other hand, in a conventional bath, ammonium nitrate and ammonia are used as an electrolytic solution, and electrolysis is performed at a constant voltage of 10V. Further, the dissolution rates of V, Nb, Ta, Cr, and Mo are plotted as relative values when the value of the electrolytic solution at 25 ° C. is 1.0. As shown in this figure, it is difficult to raise the temperature of the conventional bath to a temperature higher than that since the ammonia volatilization becomes intense when the temperature of the electrolytic solution is 45 ° C. or higher. On the other hand, since this PAT bath is composed of a high boiling point solvent, it can be electrolyzed without any problem up to the water evaporation temperature range or lower, and as a result, the dissolution rate increases at 50 ° C. or higher, and the productivity increases.

  The pH of the electrolytic solution is adjusted so that the electrolytic solution is weakly alkaline, and is preferably 9 or more, more preferably 10 or more. If the pH is less than 9, the generated ions related to V, Nb, Ta, Cr, and Mo cannot be dissolved, form a compound, precipitate, and as a result, the electrolytic dissolution may be hindered. .

Alcoholamines used in the electrolyte have high withstand voltage and current withstand density, and it is preferable for the productivity that the set voltage and set current density in electrolysis are higher. Therefore, it is preferable that the set voltage is 30 V or less and the set current density is 500 A / dm ² or less because it is practical. For reference, FIG. 3 shows the relationship between constant voltage and current efficiency in electrolysis. As shown in FIG. 3, when the voltage / current density is low, the processing amount (production amount) per time is small.

  V, Nb, Ta, Cr, and Mo are dissolved in the electrolytic solution by electrolysis, and then neutralized with hydrochloric acid, nitric acid, and the like, and V, Nb, Ta, Cr, and Mo are taken out as hydroxides. In this case, the quality of V, Nb, Ta, Cr, and Mo is already very high at 4N or higher in the state of hydroxide.

  Next, the obtained hydroxides of V, Nb, Ta, Cr, and Mo are concentrated to form a metalate compound, which is heated and reduced as necessary to obtain a high-purity metal oxide or single metal. to recover.

The method for recovering a transition metal according to the present invention includes electrolysis using an electrolytic solution containing an alcoholamine as described above, and thus high-purity Group 5 and / or Group 6 transition metal at low cost. Can be recovered. In particular:
(1) By removing impurities such as Na, K, Fe and S in the treatment reaction system, it is possible to recover the Group 5 and / or Group 6 transition metals with high purity without lowering the purity. it can.
(2) From recycled materials, etc., the purity of the Group 5 and / or Group 6 transition metal can be 4N or higher.
(3) Since the electrolytic solution has a high withstand voltage and is stable and has a low pH dependency, it is easy to control during electrolysis and does not require replenishment by volatilization such as ammonia. it can.
Here, the withstand voltage and stability of the electrolyte solution of alcohol amine is high and stable for an unclear reason. Probably, the dissolved group 5 and / or group 6 transition metal coordinates with alcohol amine, This is thought to be due to stabilization.

  Examples of the present invention will be described below, but the examples are for illustrative purposes and are not intended to limit the invention.

Example 1
As the anode of the electrolytic cell, 5.0 kg of a target piece of molybdenum (100% purity) was used.
A titanium plate was used as the cathode of the electrolytic cell.
As an electrolytic solution for the electrolytic bath, pure water was added to monoethanolamine to prepare 20 L of a 11.0 pH electrolytic solution having a monoethanolamine concentration of 5 mass%.
Using these, the set voltage was 10 V, the current density was 5 A / dm ² , the temperature was adjusted to 60 ° C. at a constant current of 100 A, and electrolysis was performed for 10 hours.
As a result, high purity molybdenum of 4N or higher was recovered. The amount of molybdenum dissolved was 0.6 kg, and the current efficiency was almost 100%.

(Example 2)
As the anode of the electrolytic cell, a small piece of MoSi ₂ alloy scrap, 3.0 kg, was used.
A titanium plate was used as the cathode of the electrolytic cell.
As an electrolytic solution for the electrolytic cell, 10 L of an electrolytic solution having a pH of 11.0 and a monoethanolamine concentration of 10 mass% was prepared by adding pure water to monoethanolamine.
Using these, the set voltage was 10 V, the current density was 50 A / dm ² , the temperature was adjusted to 60 ° C. at a constant current of 500 A, and electrolysis was performed for 2 hours.
As a result, the purity of molybdenum excluding silicon was 4N or higher, and high purity molybdenum could be recovered. The molybdenum dissolution amount was 0.59 kg, and the current efficiency was almost 100%.

  Examples 1 and 2 show that, with respect to molybdenum and molybdenum alloys, the method for recovering transition metals according to the present invention can recover high-purity Group 5 and / or Group 6 transition metals at low cost. It was done. Here, molybdenum is a Group 6 transition metal, and Group V and Group 6 transition metals V, Nb, Ta, Cr, and Mo react with each other in the same manner with respect to alcohol amine. Based on (1) and (2), it can be seen that the method for recovering a transition metal according to the present invention is similarly effective even if the transition metal to be recovered is V, Nb, Ta, or Cr.

(Comparative Example 1)
As an anode for the electrolytic cell, a tungsten basket with 5 kg of irregular shaped end material made of tungsten recycled material was used.
A titanium plate was used as the cathode of the electrolytic cell.
As an electrolytic solution for the electrolytic bath, pure water was added to ammonium nitrate and aqueous ammonia, and 10 L of an electrolytic solution with a pH of 10.6 having an ammonium nitrate concentration of 10 mass% and an ammonia concentration of 5 mass% was prepared.
Using these, the set voltage was 5 V, the current density was 5 A / dm ² , the temperature was adjusted to 70 ° C. at a constant current of 50 A, and electrolysis was performed for 10 hours.
As a result, the tungsten dissolution amount was 0.5 kg, and the current efficiency was almost 90%, which was lower than that of the example. In addition, since the ammonia component volatilizes during electrolysis, it is necessary to replenish the electrolyte solution with ammonia water as needed, which is very time-consuming and requires a large amount of ammonia supply. It was disadvantageous in terms of costs and costs.

Claims (6)

  A method for recovering a transition metal comprising a step of subjecting a raw material mixture containing at least one of V, Nb, Ta, Cr and Mo components to electrolysis using an electrolytic solution containing an alcohol amine.   The method for recovering a transition metal according to claim 1, wherein the alcohol amine is monoethanolamine and / or triethanolamine.   The method for recovering a transition metal according to claim 1 or 2, wherein the concentration of the alcohol amine in the electrolytic solution is 1 to 40 mass%.   The method for recovering a transition metal according to claim 1, wherein electrolysis is performed by adjusting the temperature of the electrolytic solution to 50 ° C. or higher.   The transition metal recovery method according to claim 1, wherein the electrolyte solution has a pH of 9 or more. The method for recovering a transition metal according to claim 1, wherein a set voltage in the electrolysis is 30 V or less and a set current density is 500 A / dm ² or less.