JP2016180125A - Recovery method of valuable metal from waste nickel hydrogen battery and recovery device of valuable metal from waste nickel hydrogen battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recovery method and a recovery device of valuable metal from waste nickel hydrogen battery establishing a process of bypass of nickel refining process and reducing the number of times of filtration treatment, achieving simplification of whole process, reducing cost and further enhancing safety or recovery efficiency.SOLUTION: In a demanganization process S13, an oxidant is added to a mixed slurry obtained in a rare earth crystallization process S12 to set oxidation reduction potential of the mixed slurry at 800 mV (Ag/AgCl electrode basis) or more and further pH of the slurry at 1.5 to 2.5 to obtain a mixture solution containing nickel sulfate and cobalt sulfate from which manganese is removed, and the mixture solution is recovered as valuable metal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and apparatus for separating and recovering valuable metals such as nickel, cobalt, and rare earth elements from used nickel-metal hydride batteries and waste nickel-metal hydride batteries such as defective products produced during production.

  One of the causes of air pollution and global warming in recent years is automobile exhaust gas. In order to reduce pollution caused by exhaust gas, production of hybrid vehicles and electric vehicles equipped with secondary batteries such as nickel metal hydride batteries Demand is increasing at an accelerating rate. Any of the nickel metal hydride batteries installed in these vehicles are expected to be discarded, and valuable metals are recovered from used nickel metal hydride batteries (hereinafter also referred to as “waste nickel metal hydride batteries”) as resources. Technological development for recycling is also underway.

  As a method of recovering valuable metals such as nickel and cobalt from waste nickel metal hydride batteries, a dry processing method is known in which nickel is reduced and recovered as ferronickel alloyed with part of iron. Although the dry processing method can be processed efficiently at low cost, it is insufficient from the viewpoint of high purity nickel and recovery of cobalt and rare earth elements, and valuable metals contained in waste nickel metal hydride batteries. Cannot be recycled for battery materials. In view of this, a wet processing method that corrects problems in the dry processing method and recovers the valuable metal from the leachate obtained by dissolving the valuable metal has been proposed (see, for example, Patent Documents 1 and 2).

  In the method described in Patent Document 1, (1) the positive electrode active material and the negative electrode active material are subjected to a cleaning treatment using an acidic aqueous solution, and the electrolyte component adhering to the positive electrode active material and the negative electrode active material is removed. A washing step for obtaining a residue after washing and a solution after washing, and (2) mixing the residue after washing and the leachate obtained in the leaching step to subject the leachate to a reduction treatment, and keep the iron in the leachate divalent. A reduction step for obtaining a reduction solution and reduction residue containing nickel, cobalt, rare earth elements and other coexisting metal elements, and (3) adding a sulfuric acid aqueous solution to the reduction residue and subjecting to a leaching treatment while oxidizing. A leaching step for obtaining a leaching solution and a leaching residue containing nickel and a rare earth element, and (4) mixing an alkaline sulfate or alkali hydroxide with the reducing solution, subjecting it to a rare earth element double chloride treatment, The precipitate and nickel and A rare earth recovery step for obtaining a filtrate containing balt; and (5) an oxidation containing nickel and cobalt by subjecting the filtrate obtained in the rare earth recovery step to an oxidative neutralization treatment by adding an oxidizing agent and a neutralizing agent. An oxidation neutralization step for obtaining a neutralized solution and an oxidized neutralized starch containing iron and aluminum; and (6) subjecting the oxidized neutralized solution to a solvent extraction treatment using a phosphoric acid-based extractant, It is comprised from the solvent extraction process of obtaining the back extract liquid containing cobalt, manganese, zinc, and yttrium, and the extraction residual liquid containing nickel.

  In Patent Document 1, nickel, cobalt, rare earth elements, and other coexistence are obtained from a positive electrode active material and a negative electrode active material obtained by disassembling a used nickel metal hydride battery through the steps (1) to (6). In particular, nickel and rare earth elements having a high content can be recovered in a form that can be reused as battery materials.

  However, since the method described in Patent Document 1 has a large number of steps and is complicated, it requires a large processing cost, and is not a commercially viable process. In addition, impurities such as iron and aluminum separated by neutralization are small. For this reason, the slurry concentration after the oxidation neutralization is low, the effect of reducing the impurity concentration by coprecipitation cannot be expected, the particle size of the oxidation neutralized starch is fine, and the filtration takes time. There is a problem of being bad.

  On the other hand, the method described in Patent Document 2 includes (1) a leaching step in which a positive / negative electrode active material-containing material is mixed and dissolved in a sulfuric acid solution, and then separated into a leachate and a residue, and (2) A rare earth crystallization step of adding a sulfate of an alkali metal to obtain a mixed precipitation of a rare earth element sulfate and a rare earth element liquid; and (3) adding a sulfiding agent to the derare earth element liquid, nickel and cobalt It consists of a sulfide raw material recovery step that separates the sulfide raw material and the residual liquid. In patent document 2, nickel, cobalt, and a rare earth element can be isolate | separated and collect | recovered from the positive / negative electrode active material which comprises a nickel hydride battery by passing through the process of said (1)-(3).

  However, since the method described in Patent Document 2 precipitates a large amount of nickel, not a very small amount of impurities, the amount of the sulfiding agent used is enormous, which causes a cost increase. In addition, since the sulfide precipitation method is used, it is necessary to increase the number of steps of the entire recovery process because it is necessary to increase the two-step sulfiding step and the equipment used for separating zinc and the like.

JP 2010-174366 A JP 2012-025992 A

  Therefore, the present invention has been proposed in view of the above-mentioned problems of the prior art, and from a waste nickel metal hydride battery that further improves safety and recovery efficiency while simplifying and reducing the cost of the entire process. An object of the present invention is to provide a valuable metal recovery method and recovery device.

  In order to achieve the above-mentioned object, the inventors of the present invention, in particular, did not separate the mixed slurry of the sulfate double salt mixed precipitate obtained in the rare earth crystallization step and the derare earth element liquid containing manganese without performing solid-liquid separation. It is sent to the demanganese step, and an oxidant is added to the slurry to separate manganese in the derare earth element liquid as a precipitate containing manganese, and the mixture of this precipitate and sulfate mixed salt mixed precipitate is collectively At the same time, we focused on solid-liquid separation and repeated research.

  As a result, the present inventors, in the demanganese process, by simultaneously solid-liquid separation of the manganese-containing precipitate and the sulfate double salt mixed precipitate, nickel sulfate that can be used as a raw material for battery materials and It has been found that a mixed aqueous solution containing cobalt sulfate can be efficiently produced at low cost, and the present invention has been completed.

  That is, the method for recovering valuable metals from waste nickel metal hydride batteries according to the present invention for achieving the above object is the waste nickel for separating and recovering nickel, cobalt and rare earth elements from valuable metal-containing materials obtained from waste nickel metal hydride batteries. A method of recovering valuable metals from a hydrogen battery, wherein the valuable metal-containing material obtained from the waste nickel metal hydride battery is mixed and dissolved in a sulfuric acid solution, and then separated into a leachate and a leach residue, A rare earth crystallization step of adding an alkali metal sulfate to the leachate obtained in the leaching step to obtain a mixed slurry of a rare earth element sulfate double salt mixed precipitate and a derare earth element solution containing manganese; and An oxidant is added to the mixed slurry obtained in the rare earth crystallization step, and the redox potential of the mixed slurry is set to 800 mV (Ag / AgCl electrode standard) or more. Thereby removing manganese in the mixed slurry as a precipitate and obtaining a mixed aqueous solution containing nickel sulfate and cobalt sulfate from which the precipitate containing manganese and the mixture of the sulfate double salt mixed precipitate have been removed; It is characterized by having.

  Moreover, the recovery device of valuable metals from waste nickel metal hydride batteries according to the present invention for achieving the above object is waste nickel for separating and recovering nickel, cobalt and rare earth elements from valuable metal-containing materials obtained from waste nickel metal hydride batteries. A device for recovering valuable metals from a hydrogen battery, the reaction tank storing leachate obtained by separating the valuable metal-containing material obtained from the waste nickel metal hydride battery after being mixed and dissolved in a sulfuric acid solution, and A supply unit for supplying alkali metal sulfate and oxidant to the reaction tank, a control unit for controlling at least the supply sequence and supply amount of the alkali metal sulfate and oxidant supplied from the supply unit, and the leachate The mixed slurry of the rare earth element sulfate double salt mixed precipitate obtained by adding the alkali metal sulfate to the above and the derare earth element liquid containing manganese is further added to the previous slurry. It contains nickel sulfate and cobalt sulfate by solid-liquid separation from a slurry comprising a manganese-containing precipitate obtained by adding an oxidizing agent and a mixture of the sulfate double salt mixed precipitate and an aqueous solution containing nickel sulfate and cobalt sulfate. A recovery unit for recovering the mixed aqueous solution, and the control unit controls the supply order so as to add the oxidizing agent to the mixed slurry after adding the alkali metal sulfate to the leachate, and The supply amount of the oxidizing agent is controlled so that the oxidation-reduction potential of the mixed slurry is 800 mV (Ag / AgCl electrode standard) or more.

  According to the present invention, a sulfate-containing double salt mixed precipitate is generated, a precipitate containing manganese is generated and co-precipitated, and these precipitates are collectively filtered, thereby simplifying the entire process and reducing the cost. And safety and recovery efficiency of valuable metals can be improved.

It is process drawing which shows the outline of the recovery process of valuable metals in the recovery method of valuable metals from the waste nickel metal hydride battery which concerns on one embodiment of this invention. It is the schematic which shows the outline of the collection | recovery apparatus of the valuable metal from the waste nickel metal hydride battery which concerns on one embodiment of this invention. It is process drawing which shows the outline of the collection process of the valuable metal in the recovery method of the valuable metal from the conventional waste nickel metal hydride battery.

  A specific embodiment to which the present invention is applied (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings in the following order. Note that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention.

1. 1. Recovery method of valuable metals from waste nickel metal hydride batteries 1-1. Leaching process 1-2. Rare earth crystallization process 1-3. Demanganese process 1-4. 1. Battery material manufacturing process 2. Equipment for recovering valuable metals from waste nickel metal hydride batteries 2-1. Reaction tank 2-2. Supply unit 2-3. Heating unit 2-4. Collection unit 2-5. Control unit 2-6. 2. Procedure for using valuable metal recovery equipment Summary

[1. Method for recovering valuable metals from waste nickel metal hydride batteries]
As shown in FIG. 1, the method for recovering valuable metals from waste nickel metal hydride batteries according to the present embodiment (sometimes simply referred to as “valuable metal recovery method”) leaches the valuable metal-containing material. A leaching step S11 for obtaining a leachate containing a valuable metal and a leach residue, a rare earth crystallization treatment for the leachate obtained in the leaching step S11, and a rare earth element sulfate containing manganese mixed precipitate and a rare earth element solution containing manganese Rare earth crystallization step S12 for obtaining a mixed slurry, oxidation treatment on the mixed slurry obtained in rare earth crystallization step S12, and a mixture of a precipitate containing manganese and a double sulfate mixed precipitate and a valuable metal mixed solution (nickel sulfate · And a demanganese step S13 for obtaining a cobalt mixed solution.

  In the valuable metal recovery method, the valuable metal mixed solution is obtained in the demanganese step S13 using the mixed slurry obtained in the rare earth crystallization step S12, whereby the valuable metal can be recovered from the waste nickel metal hydride battery. . In addition, by supplying the valuable metal mixed solution obtained in the demanganese step S13 to the battery material manufacturing process S14, a battery material is produced from the valuable metal mixed solution, and various batteries are manufactured using the obtained battery material. be able to.

<1-1. Leaching process>
In the leaching step S11, as shown in FIG. 1, a valuable metal-containing material obtained by pre-treating a waste nickel metal hydride battery and a sulfuric acid solution are mixed, heated and dissolved to obtain a leachate containing valuable metals. And leaching residue.

Of the valuable metals contained in the valuable metal-containing material, for example, lanthanum, which is one of nickel and rare earth elements, is dissolved according to the following formulas 1 and 2.
Ni + H ₂ SO ₄ → NiSO ₄ + H ₂ (Formula 1)
2La + 3H ₂ SO ₄ → La ₂ (SO ₄ ) ₃ + 3H ₂ (Formula 2)

  The pH of the leachate is not particularly limited, but is preferably maintained at 0 or more and 5 or less, more preferably 0 or more and 1 or less. When the pH of the leachate is less than 0, the neutralizing agent used in the subsequent process increases. On the other hand, when the pH of the leaching solution exceeds 5, the leaching rate of valuable metals such as nickel and cobalt decreases.

  In the leaching step S11, in order to obtain a practical and satisfactory reaction rate, leaching is preferably performed while maintaining a liquid temperature of 80 ° C. or higher under a strong acid. In the leaching step S11, for example, leaching processing can be performed using sulfuric acid having a concentration of 64%.

  Further, in the leaching step S11, the valuable metal-containing material and the sulfuric acid solution are mixed, heated and dissolved, and then a valuable metal-containing material can be further added to neutralize the excess sulfuric acid. Next, the slurry made of the obtained leachate and leach residue is allowed to cool, and then solid-liquid separation is performed to obtain the leachate. Although it does not specifically limit as a slurry density | concentration, It is preferable to adjust to 50 g / L or more and 300 g / L or less.

  As described above, in the leaching step S11, a leaching solution in which valuable metals such as nickel, cobalt, and rare earth elements are leached into the sulfuric acid solution can be obtained.

  In general, a nickel-metal hydride battery, which is a type of secondary battery, has a functional member such as a positive electrode, a negative electrode, an electrode terminal, and an electrolyte, a separator provided between an electrode substrate, a positive electrode and a negative electrode, and a case for housing them. And other structural members.

  Various materials are contained in the functional member and the structural member constituting the nickel metal hydride battery. For example, the positive electrode contains a positive electrode active material, and the positive electrode active material is made of nickel hydroxide containing a trace amount of added elements. Further, the negative electrode contains a negative electrode active material, and the negative electrode active material is composed of a hydrogen storage alloy containing nickel, cobalt, a rare earth element (Misch metal), or the like.

  The positive substrate is made of a nickel plate, a foamed nickel plate, or the like, and the negative substrate is made of a nickel-plated iron plate or the like. Furthermore, the separator is made of a synthetic resin or the like, the electrolyte is made of a potassium hydroxide aqueous solution or the like, the electrode terminal material is made of copper, an iron-based metal, or the like, and the case is made of a synthetic resin, steel, or the like.

  The valuable metal-containing material used in the leaching step S11 is obtained by subjecting a waste nickel metal hydride battery to a predetermined pretreatment, and in addition to nickel and cobalt, which are valuable metals, lanthanum and cerium are included. It contains rare earth elements such as yttrium, and impurities such as manganese, iron, and aluminum. However, the type and content of impurities in the valuable metal-containing material are not particularly limited, and vary depending on the member of the waste nickel metal hydride battery used as a raw material, the processing method, and the like. In the valuable metal recovery method, the valuable metal in the content can be efficiently recovered at low cost and high purity regardless of the type and content of impurities in the valuable metal content.

<1-2. Rare earth crystallization process>
Next, in the rare earth crystallization step S12, as shown in FIG. 1, an alkali metal sulfate is added to the leachate obtained in the leaching step S11, and the sulfate double salt mixed precipitate in which the rare earth element is combined with the alkali metal Then, a mixed slurry is obtained which is a mixture of a rare earth element liquid containing manganese, which is a mixed aqueous solution of nickel sulfate and cobalt sulfate from which the rare earth element has been separated.

In the rare earth crystallization step S12, for example, lanthanum, which is one of the rare earth elements in the leachate, generates a lanthanum and sodium double salt (sulfate double salt mixed precipitate) according to the following formula 3.
La ₂ (SO ₄ ) ₃ + Na ₂ SO ₄ → 2LaNa (SO ₄ ) ₂ (Formula 3)

  In the rare earth crystallization step S12, it is more preferable to use an alkali sulfate (alkali metal sulfate) such as sodium sulfate or potassium sulfate.

  Although it does not specifically limit as pH at the time of reaction, It is preferable to maintain at 1-5, and it is more preferable to maintain at 1-3. That is, in the rare earth crystallization step S12, when the pH during the reaction is 1 or more and 5 or less, the rare earth element can be separated as a precipitate. In addition, pH adjustment at the time of reaction in rare earth crystallization process S12 is performed using pH adjusters, such as a mineral acid and alkaline aqueous solution, as needed.

  However, when the pH during the reaction exceeds 3, since metal elements such as nickel, cobalt, iron, and aluminum may precipitate together with the sulfate double salt mixed precipitation, the pH is maintained in the range of 1 to 3, It is more preferable that these metal elements remain in the rare-earth element liquid.

  In the rare earth crystallization step S12, the liquid temperature is not particularly limited, but is preferably 50 ° C. or higher and 70 ° C. or lower. When the liquid temperature is less than 50 ° C., a practical and satisfactory reaction rate cannot be obtained. On the other hand, the upper limit of the liquid temperature is not particularly limited, but is preferably 70 ° C. or lower in consideration of the amount of water evaporation and energy efficiency.

  In the rare earth crystallization step S12, valuable metals and impurities are sent to the next demanganese step S13 in a slurry state without performing the solid-liquid separation operation after the rare earth crystallization. The amount of manganese-containing precipitate obtained in the demanganese step S13 is a small amount of about 2 g / L, and the particles are fine. Therefore, the solid-liquid separation operation after rare-earth crystallization is performed to remove only the manganese-containing precipitate. In the case of filtration alone, the filterability deteriorates, and further, the precipitate may escape into the filtrate (nickel sulfate / cobalt mixed solution) during the filtration operation.

  In order to solve such a problem, in the next demanganese step S13, a relatively large amount of a sulfate double salt mixed precipitate having good filterability and a precipitate containing manganese are simultaneously solid-liquid separated. To do. As a result, in the next demanganese step S13, the filterability of the precipitate containing manganese can be improved, the filtration time can be shortened, the removal rate of manganese can be improved by the coprecipitation effect, and the filtration step can be integrated. The cost due to can be reduced, and the efficiency of the entire process can be improved.

  That is, in the rare earth crystallization step S12 and the demanganese step S13, the mixed form of sulfate double salt is not separated into solid and liquid, but a precipitate containing manganese, iron, etc. produced in the demanganese step S13 is added. Thus, the process efficiency is improved by solid-liquid separation. Furthermore, in the same reactor, the demanganese operation can be performed following the rare earth crystallization operation.

<1-3. Demanganese process>
Next, in the demanganese step S13, as shown in FIG. 1, an oxidizing agent is added to the mixed slurry obtained in the rare earth crystallization step S12 to perform oxidation treatment, and a sulfate-containing double salt mixed precipitate and a manganese-containing precipitate are added. And a valuable metal mixed solution (nickel sulfate / cobalt mixed solution) are obtained, and the valuable metal is recovered as the valuable metal mixed solution.

As conditions for the demanganese reaction in the demanganese step S13, the oxidation-reduction potential of the derare earth element liquid is 800 mV (Ag / AgCl electrode standard) or more and the pH is 1.5 to 2.5. When the pH of the rare earth element solution is lower than 1.5, manganese, iron and the like are not easily precipitated, and the amount of the neutralizing agent used in the subsequent battery material manufacturing process S14 increases. On the other hand, when the pH of the rare earth element solution exceeds 2.5, nickel, cobalt, or the like may be precipitated. Theoretically, when the redox potential of the rare earth element liquid is increased to 1000 mV (Ag / AgCl electrode standard), nickel hydroxide (III) (Ni (OH) ₃ ) is generated at pH 3. The pH of the rare earth element solution is adjusted using a pH adjuster such as a mineral acid or an alkaline aqueous solution as necessary, as in the rare earth crystallization step S12.

  In the demanganese step S13, hydrogen peroxide, lithium nickelate powder, sodium persulfate, or the like can be used as an oxidizing agent. Moreover, mineral acids, such as a sulfuric acid and hydrochloric acid, and alkalis, such as sodium hydroxide, sodium carbonate, calcium hydroxide, a calcium carbonate, can be used as a pH adjuster. In these, it is preferable to use sodium hydroxide or sodium carbonate which does not have a fear of mixing of calcium.

For example, when lithium nickelate powder, which is a raw material for lithium ion battery materials, is used as the oxidant, the oxidation-reduction potential is increased by adding this oxidant to the mixed slurry. Part of the dissolved manganese and iron produces a precipitate.
Mn ²⁺ + 2LiNiO ₂ + 3H ₂ SO ₄
→ MnO ₂ + Li ₂ SO ₄ + 2NiSO ₄ + 2H ₂ O + 2H ⁺ (Formula 4)
Fe ³⁺ + 3NaOH → Fe (OH) ₃ + 3Na ⁺ (Formula 5)

As described above, in the demanganese step S13, the demanganese reaction is performed under the condition that the redox potential of the derare earth element solution is 800 mV (Ag / AgCl electrode standard) or more and the pH is 1.5 to 2.5. . As a result, manganese is precipitated as manganese oxide (IV) (MnO ₂ ), iron is precipitated as iron hydroxide (III) (Fe (OH) ₃ ), and nickel and cobalt are in the form of ions (Ni ²⁺ , Co ²⁺ ). Since it exists in the liquid, it is filtered, and the resulting mixed aqueous solution of nickel sulfate and cobalt sulfate (nickel sulfate / cobalt mixed solution) is used as a raw material for battery material production in the battery material production process S14 described later. be able to.

<1-4. Battery Material Manufacturing Process>
In the battery material manufacturing process S14, as shown in FIG. 1, the mixed aqueous solution of nickel sulfate and cobalt sulfate (nickel sulfate / cobalt mixed solution) obtained in the demanganese step S13 is used as a raw material. The sulfuric acid content in the mixed aqueous solution of nickel sulfate and cobalt sulfate is finally discharged from the waste liquid treatment process in the form of sodium sulfate.

  If this sodium sulfate is a predetermined concentration or more, it can be used as a sodium salt used in the rare earth crystallization step S12, and the chemical cost required for the treatment can be reduced.

[2. Equipment for recovering valuable metals from waste nickel metal hydride batteries]
Next, based on FIG. 2, a recovery device for valuable metals from the waste nickel metal hydride battery according to the present embodiment (which may be simply referred to as “recovery device 1”) that can be used in the above-described recovery method. .). As shown in FIG. 2, the recovery device 1 includes a reaction tank 10, a supply unit 20, a heating unit 30, a recovery unit 40, and a control unit 50. Since the recovery device 1 includes such components, the filtration process, which has been performed in two stages using an individual reaction tank in the conventional method, can be performed collectively in the reaction tank 10, so that the entire process Can be simplified and the cost can be reduced, and safety during operation of the apparatus and recovery efficiency of valuable metals can be improved.

<2-1. Reaction tank>
The reaction tank 10 stores the leachate obtained by separating the valuable metal-containing material obtained from the waste nickel metal hydride battery after mixing it with the sulfuric acid solution and dissolving it. The material of the reaction vessel 10 can store the leachate obtained by the leaching reaction in the leaching step S11 shown in FIG. 1, and in the rare earth crystallization reaction in the rare earth crystallization step S12 and the demanganese reaction in the demanganese step S13. If it does not deteriorate with the various chemical | medical agents to be used and the product obtained by various reaction, there will be no restriction | limiting in particular, According to the objective, it can select suitably. The reaction tank 10 is not particularly limited in size (capacity), shape, structure, etc. as long as it is a container capable of performing rare earth crystallization reaction and demanganese reaction in the tank, and is appropriately selected according to the purpose. can do.

  In the reaction vessel 10, the reactions performed in the rare earth crystallization step S12 and the demanganese step S13 shown in FIG. 1, that is, the rare earth crystallization reaction and the demanganese reaction are performed. Since the specific reaction and the drug to be used are as described in the above-described collection method, description thereof is omitted here.

<2-2. Supply Department>
The supply unit 20 supplies alkali sulfate (alkali metal sulfate), an oxidizing agent, and a pH adjuster to the leachate in the reaction vessel 10. The supply unit 20 includes a storage tank (not shown) for storing the leachate, the alkali metal sulfate, the oxidizing agent, and the pH adjuster, and a liquid supply such as a pump for supplying these to the reaction tank 10 respectively. -It is comprised from the addition means (not shown) and piping (not shown). In the supply unit 20, the leachate, the alkali metal sulfate, the oxidizing agent, and the pH adjuster are supplied from the storage tank to the reaction tank 10 via the pipes by the liquid feeding / addition unit.

  The control unit 50 controls the supply order and supply amount of the leachate, alkali metal sulfate, oxidizing agent, and pH adjuster in the supply unit 20. The supply unit 20 supplies the leachate into the reaction tank 10 by the control unit 50 and then sequentially supplies the alkali metal sulfate and the oxidizing agent. Further, the supply unit 20 adjusts the supply amount of the pH adjusting agent by the control unit 50 so that the pH of the leaching solution is 1 or more and 5 or less, preferably 1 or more and 3 or less in the rare earth crystallization reaction. Further, the control unit 50 causes the supply unit 20 to reduce the oxidation-reduction potential of the leachate to 800 mV (Ag / AgCl electrode standard) or more and to set the pH to 1.5 to 2.5 in the demanganese reaction. And the supply amount of the pH adjusting agent is adjusted.

  The leachate is obtained by the reaction performed in the leaching step S11 shown in FIG. 1, that is, the leaching reaction. The leachate is obtained by performing the reaction in the storage tank or reaction tank of the supply unit 20. Alternatively, the leachate obtained in another tank may be sent to the reaction tank.

<2-3. Heating unit>
The heating unit 30 heats the leachate in the reaction vessel 10. The heating unit 30 is not particularly limited as long as the leachate in the reaction vessel 10 can be heated, and can be appropriately selected according to the purpose. As the heating unit 30, for example, a method of flowing a heat medium such as steam through a heat exchange serpentine tube, a method of inserting an electrothermal heater into the tank, or the like can be applied.

  Control of the heating temperature and time of the leachate is performed by the control unit 50. The heating temperature and time can be appropriately selected in consideration of the fact that a practical and satisfactory reaction rate can be obtained, the amount of water evaporation and the energy efficiency.

<2-4. Collection Department>
The recovery unit 40 recovers valuable metals from the leachate in the reaction vessel 10. The recovery unit 40 is not particularly limited as long as the product (slurry) obtained by the demanganese reaction can be solid-liquid separated into a sulfate double salt mixed precipitate and a mixture of precipitates containing manganese and a valuable metal mixed solution. Can be appropriately selected according to the purpose. As the collection unit 40, for example, a filter plate stretched on a filter plate with an uneven hole made of metal or resin is closely attached in series, and the slurry is depressurized by press-fitting the slurry from the hole of the filter plate with a pump. A filter press or the like for separating the solid content can be applied.

  Conditions such as a liquid passing pressure and a liquid passing time when a filter press is used as the recovery unit 40 are not particularly limited as long as the product obtained by the demanganese reaction can be solid-liquid separated. You can choose. The control unit 50 controls operation conditions in the recovery unit 40, for example, conditions such as a liquid passing pressure and a liquid passing time.

<2-5. Control unit>
The control unit 50 controls the operation of each component of the collection device 1. Specifically, the control unit 50 controls the operations of the supply unit 20, the heating unit 30, and the recovery unit 40, and controls at least the supply order and supply amount of alkali metal sulfate and oxidant supplied from the supply unit 20. To do. As shown in FIG. 2, the recovery device 1 may be configured to control the operations of the supply unit 20, the heating unit 30, and the recovery unit 40 by a single control unit 50, and may be configured according to the purpose. One control unit may be provided for each component to control the operation.

  The recovery device 1 includes elements other than the above-described components as necessary, for example, a stirring unit and a stirring blade that stirs the leachate, a stirring unit that includes a motor that drives the stirring shaft and the stirring blade, and the like. You may prepare.

<2-6. Procedure for using valuable metal recovery equipment>
A use procedure for recovering valuable metals using the recovery apparatus 1 will be described. First, the supply unit 20 supplies a predetermined amount of leachate from a storage tank (not shown) for the leachate to the reaction tank 10 via a pipe (not shown) using a liquid delivery means (not shown) such as a pump. To do. The leachate is prepared in advance by supplying a predetermined amount of valuable metal-containing material and sulfuric acid solution into the storage tank.

  Next, the supply unit 20 supplies a predetermined amount of alkali metal sulfate from a storage tank for alkali metal sulfate (not shown) using a liquid feeding / adding means (not shown) such as a pump (not shown). Is fed into the reaction vessel 10. The result is a mixture of a sulfate double salt mixed precipitate in which a rare earth element is combined with an alkali metal by a rare earth crystallization reaction, and a rare earth element liquid that is a mixed aqueous solution of nickel sulfate and cobalt sulfate containing manganese from which the rare earth has been separated. A mixed slurry is produced.

  Next, the supply unit 20 supplies a predetermined amount of oxidant into the reaction tank 10 from an oxidant storage tank (not shown) using an adding means (not shown) such as a pump. As a result, manganese contained in the mixed aqueous solution of nickel sulfate and cobalt sulfate is precipitated by the demanganese reaction, and a precipitate containing manganese is formed.

  Next, the recovery unit 40 is operated by the control unit 50 to separate a mixture of the sulfate double salt mixed precipitate and the precipitate containing manganese from the mixed slurry, and recover valuable metals such as nickel and cobalt as a valuable metal mixed solution. . The recovered valuable metal mixed solution becomes a battery material by being subjected to the battery material manufacturing process S14 shown in FIG. 1, and various batteries can be manufactured using the obtained battery material.

<3. Summary>
As a conventional method, the method described in Patent Document 2 will be described as an example. As shown in FIG. 3, in the sulfide raw material recovery step S23, a nickel / cobalt sulfide raw material is manufactured by sulfidation, and nickel / cobalt is produced. The sulfide raw material is processed in the nickel smelting process S24. That is, in this method, the sulfide raw material recovery step S23 for selectively separating the nickel and cobalt to be recovered is indispensable. Therefore, in the sulfide raw material recovery step S23, a large amount of nickel is precipitated instead of a very small amount of impurities, so that the amount of the sulfiding agent used is enormous, which causes a cost increase.

  That is, in the method described in Patent Document 2, a large amount of a sulfurizing agent having a relatively high unit price is used, which occupies most of the cost of the drug and becomes a factor that increases the cost. In addition, since the use of a sulfiding agent is expected to generate hydrogen sulfide gas during the process, it is essential to install an exhaust gas treatment facility such as a detoxification tower, which increases equipment costs and operating costs.

  Further, the sulfide raw material recovery step S23 is for removing impurities, but this is not universal, and some impurities such as zinc are more likely to generate sulfide precipitates than nickel. In other words, since it cannot be completely separated, a two-stage sulfidation operation is required to separate nickel and cobalt from zinc and the like. That is, in the method described in Patent Document 2, first, a sulfide is added to the rare earth element liquid to generate a sulfide precipitate containing zinc and the like, and then the sulfide precipitate and the filtrate are separated into solid and liquid. Then, a sulfiding agent is added again to the obtained filtrate to obtain a sulfide precipitate of nickel and cobalt. In the case of using such a sulfide precipitation method, when separating zinc or the like, it is necessary to increase the two-stage sulfidation process and the equipment used for them, and the entire process for recovering valuable metals from waste nickel metal hydride batteries. The number of processes is large and complicated.

  In addition, since the nickel / cobalt sulfide raw material can be used as a raw material for the nickel refining process S24, the method described in Patent Document 2 recycles valuable metals contained in used nickel-metal hydride batteries for batteries. The purpose of recovering as a high purity metal that can be achieved is achieved. However, in this method, the nickel / cobalt sulfide raw material obtained in the sulfide raw material recovery step S23 is processed in the nickel refining process S24 to become high-purity nickel sulfate (battery material raw material), and the battery material manufacturing process S25. And commercialized into battery materials such as nickel hydroxide and lithium nickelate. Therefore, from the viewpoint of the manufacturing cost of the raw material for battery materials, the processing cost in the nickel smelting process S24 is added to the wet processing cost, so it is difficult to reduce the processing cost.

  In contrast, in the valuable metal recovery method and the valuable metal recovery apparatus according to the present embodiment, as described above, the valuable metal-containing material obtained by pretreating the waste nickel metal hydride battery is mixed with the sulfuric acid solution. After obtaining the leachate by dissolution, the rare earth elements, which are useful elements, are separated from the leachate containing nickel, cobalt, rare earth elements, and manganese using alkali metal sulfates as precipitates (sulfate double salt mixed precipitation). A mixed slurry containing the precipitate is obtained. Next, without using a sulfiding agent, an oxidizing agent is added to the mixed slurry, and manganese is separated from nickel and cobalt as a precipitate (manganese precipitate), and a sulfate double salt mixed precipitate and a mixture of manganese precipitates are separated. The mixed solution of nickel and cobalt separated by filtration is supplied to the battery material manufacturing process.

  That is, in the valuable metal recovery method and the valuable metal recovery apparatus according to the present embodiment, a process for bypassing the nickel smelting process is established, and a sulfate-containing mixed salt precipitate is generated, and then a precipitate containing manganese is generated. By co-precipitating and filtering these precipitates at once, the entire process can be simplified and the cost can be reduced, and safety and recovery efficiency of valuable metals can be improved.

  The valuable metal recovery method and valuable metal recovery apparatus according to the present embodiment are a mixture of a sulfate double salt mixed precipitate and a manganese precipitate in the rare earth crystallization step S12 and the demanganese step S13, or the rare earth crystallization reaction and the demanganese reaction. Can selectively separate rare earth elements, manganese, iron, etc., and selectively recover nickel and cobalt as a mixed aqueous solution (nickel sulfate / cobalt mixed solution) containing nickel sulfate and cobalt sulfate Can do. Thereby, unlike the conventional method, valuable metals can be recovered without going through the sulfidation step. Therefore, the processing cost can be reduced in the entire valuable metal recovery process.

  Further, in the valuable metal recovery method and the valuable metal recovery apparatus according to the present embodiment, since the battery material can be produced without going through the nickel smelting process, the entire battery material manufacturing process including the valuable metal recovery process described above is possible. Can cut the processing cost in half.

  Furthermore, in the valuable metal recovery method and the valuable metal recovery apparatus according to the present embodiment, a mixed aqueous solution containing nickel sulfate and cobalt sulfate obtained by the demanganese step S13 or the demanganese reaction is used as a raw material for battery materials. it can. Thereby, it is possible to establish a process for recovering valuable metals contained in the waste nickel metal hydride battery as recyclable metal for the battery. This process is economically effective and very useful.

  Further, in the valuable metal recovery method and the valuable metal recovery apparatus according to the present embodiment, it is possible to recover nickel and cobalt, which are valuable metals, without using a sulfiding agent, thereby reducing the drug cost associated with the use of the sulfiding agent. Can do. Furthermore, by not using a sulfiding agent, it is possible to eliminate equipment costs and operating costs in an exhaust gas treatment facility associated with the generation of hydrogen sulfide gas. Thereby, in the valuable metal recovery method and the valuable metal recovery device, the risk of hydrogen sulfide gas generation is eliminated, so that an effect on the safety environment can be expected.

  The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

Example 1
In Example 1, a valuable metal-containing material obtained by pretreating a waste nickel metal hydride battery was used as a raw material. There are two types of raw materials, a metal piece that is difficult to leach and a powder that is easy to leach. In Example 1, these were treated and subjected to a leach treatment in the leach step described later. Moreover, in Example 1, in order to implement | achieve efficient leaching, the leaching of the raw material used as a process target was performed in two steps.

<Leaching process>
In the leaching step, 25 kg of metal flake raw material was put into the column tank, and 120 L of 59% sulfuric acid was supplied stepwise while circulating 300 L of water to obtain a leachate having a first stage acid concentration.

  Next, in the leaching step, 65 kg of the powdery raw material was put into a leaching tank equipped with a stirrer, 150 L of water was supplied, and 350 L of the first stage leachate was supplied stepwise while stirring. The powdery raw material was leached with excess sulfuric acid contained in the first stage leaching solution, and after leaching residue was filtered with a filter press, a leaching solution having a pH of 1.0 and a nickel concentration of 110 g / L was finally obtained.

<Rare earth crystallization process>
In the rare earth crystallization step, a 180 g / L sodium sulfate solution 140 L was put in a tank equipped with a stirrer in advance. Next, in the rare earth crystallization step, 140 L of the leachate obtained in the leaching step was charged into this tank, and stirring was continued for 3 hours while maintaining 60 ° C. As a result, 300 L of a mixed slurry of the rare earth sulfate double salt, nickel sulfate, and cobalt sulfate formed by precipitation was obtained. The nickel concentration in the liquid at this time was 42 g / L.

<Demanganese process>
In the demanganese process, among the mixed slurry obtained in the rare earth crystallization process, the mixed aqueous solution of nickel sulfate and cobalt sulfate has a nickel concentration of 41 g / L, a cobalt concentration of 6.3 g / L, and a manganese concentration of 1.7 g. / L and an iron concentration of 0.83 g / L were used as starting materials.

  In the demanganese process, 2.1 kg of lithium nickelate powder as an oxidizing agent was added to 300 L of the mixed slurry solution obtained in the rare earth crystallization process. At the time of the demanganese reaction, sulfuric acid was consumed with the dissolution of the oxidizing agent, so that sulfuric acid was supplied with stirring so as to maintain the pH of 2. The 59% sulfuric acid required for this was 1.6 L. In the demanganese process, when the oxidizing agent was dissolved, the supply of sulfuric acid was stopped and the pH was stabilized at 2, it was judged that the oxidation of manganese and iron was completed. The final redox potential was 1000 mV (Ag / AgCl electrode standard).

  In the demanganese process, the obtained mixed slurry was filtered with a filter press, and finally, pH 2.0, nickel concentration 42 g / L, cobalt concentration 6.5 g / L, manganese concentration 0.26 g / L and iron concentration 0. A mixed aqueous solution of 19 g / L of nickel sulfate and cobalt sulfate was obtained. The time required for filtration at this time was about 3 minutes.

  In addition, the heavy metal component analysis in the liquid obtained at each process was performed using ICP (Inductively Coupled Plasma) emission photometric analysis.

  In Example 1, about 80% of both iron and manganese could be separated.

(Comparative Example 1)
In Comparative Example 1, it was obtained by solid-liquid separation in a rare earth element crystallization step and a mixed rare earth element solution and sulfuric acid double salt mixed precipitation, and in the demanganese step, an oxidant was added to the obtained derare earth element solution. A mixed aqueous solution of nickel sulfate and cobalt sulfate was obtained in the same manner as in Example 1 except that the slurry was separated into solid and liquid. In addition, the heavy metal component analysis in the liquid obtained at each process was performed using the ICP emission photometric analysis method similarly to Example 1.

  That is, in Comparative Example 1, the sulfate double salt mixed precipitate obtained in the rare earth crystallization step was filtered alone, and the time required for the filtration was about 3 minutes. Thereafter, 2.1 kg of lithium nickelate powder was added as an oxidizing agent to 280 L of the filtrate. Since sulfuric acid was consumed with the dissolution of the oxidizing agent, sulfuric acid was supplied with stirring so as to maintain pH2. The 59% sulfuric acid required for this was 1.6 L. When the oxidizing agent was dissolved, the supply of sulfuric acid was stopped and the pH was stabilized at 2, it was judged that the oxidation of manganese and iron was completed. The final redox potential was 1000 mV (Ag / AgCl electrode standard).

  In Comparative Example 1, the obtained mixed slurry was filtered with a filter press, and finally pH 2.0, nickel concentration 42 g / L, cobalt concentration 6.3 g / L, manganese concentration 0.31 g / L and iron concentration 0. A mixed aqueous solution of 22 g / L of nickel sulfate and cobalt sulfate was obtained. The time required for filtration at this time was about 7 minutes.

  In Comparative Example 1, as compared with Example 1, the filtration work increased once, and the filtration time took longer. Furthermore, in Comparative Example 1, the manganese concentration and iron concentration of the obtained mixed aqueous solution of nickel sulfate and cobalt sulfate are slightly high, and the coprecipitation effect was not obtained and the filterability deteriorated, It is presumed that the flow pressure of the filter press increased and a small amount of demanganese precipitate leaked into the filtrate.

  1 recovery device, 10 reaction tank, 20 supply unit, 30 heating unit, 40 recovery unit, 50 control unit

Claims (5)

A method for recovering valuable metals from waste nickel metal hydride batteries, which separates and recovers nickel, cobalt and rare earth elements from valuable metal-containing materials obtained from waste nickel metal hydride batteries,
A leaching step of separating the valuable metal-containing material obtained from the waste nickel metal hydride battery into a leaching solution and a leaching residue after being dissolved in a sulfuric acid solution;
A rare earth crystallization step of adding an alkali metal sulfate to the leachate obtained in the leaching step to obtain a mixed slurry of a rare earth element sulfate double salt mixed precipitate and a manganese-containing derare earth element solution;
By adding an oxidizing agent to the mixed slurry obtained in the rare earth crystallization step, the mixed slurry is made to have an oxidation-reduction potential of 800 mV (Ag / AgCl electrode standard) or more, thereby precipitating manganese in the mixed slurry. And a demanganese process for obtaining a mixed aqueous solution containing nickel sulfate and cobalt sulfate from which the precipitate containing manganese and the mixture of the sulfate double salt mixed precipitate are removed. For recovering valuable metals from sewage.   The method for recovering valuable metals from a waste nickel metal hydride battery according to claim 1, wherein, in the demanganese step, the pH of the mixed slurry is set to 1.5 to 2.5.   The method for recovering valuable metals from waste nickel metal hydride batteries according to claim 1 or 2, wherein the alkali metal sulfate is sodium sulfate and / or potassium sulfate. An apparatus for recovering valuable metals from waste nickel metal hydride batteries that separates and recovers nickel, cobalt and rare earth elements from valuable metal-containing materials obtained from waste nickel metal hydride batteries,
A reaction vessel for storing a leachate obtained by mixing and dissolving a valuable metal-containing material obtained from the waste nickel metal hydride battery in a sulfuric acid solution; and
A supply unit for supplying an alkali metal sulfate and an oxidizing agent to the reaction vessel;
A control unit for controlling the supply sequence and supply amount of at least the alkali metal sulfate and the oxidant supplied from the supply unit;
Manganese obtained by further adding the oxidizing agent to a mixed slurry of a rare earth element sulfate double salt mixed precipitate obtained by adding the alkali metal sulfate to the leachate and a derare earth element liquid containing manganese. And a recovery section for recovering a mixed aqueous solution containing nickel sulfate and cobalt sulfate by solid-liquid separation from a slurry comprising a precipitate containing the mixed sulfate and a mixture of the double sulfate mixed precipitate and an aqueous solution containing nickel sulfate and cobalt sulfate. And
The control unit controls the supply order to add the oxidant to the mixed slurry after adding the alkali metal sulfate to the leachate,
In addition, the apparatus for recovering valuable metals from a waste nickel metal hydride battery is characterized in that the supply amount of the oxidizing agent is controlled so that the oxidation-reduction potential of the mixed slurry is 800 mV (Ag / AgCl electrode standard) or more.   The waste according to claim 4, wherein the controller controls the supply amount of the pH adjusting agent so that the pH of the mixed slurry is 1.5 to 2.5 when the oxidizing agent is added. Equipment for recovering valuable metals from nickel metal hydride batteries.