JP2012041569A - Method for recovering valuable metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently recovering valuable metals even when large amounts of waste batteries such as lithium ion batteries are to be treated.SOLUTION: The method for recovering valuable metals includes: a dry process of melting waste batteries and flux to recover slugs and an alloy of valuable metals; and a wet process of separating valuable metals from the alloy of valuable metals. The alloy of valuable metals in the dry process is obtained as a granular material, preferably as a granular material having an average surface area of 1 to 300 mm. Thereby, a dissolution rate in the wet process that is a rate-determining step can be improved, so that the treatment speed of the waste batteries as a whole can be improved.

Description

  The present invention relates to a method for recovering valuable metals contained in a waste battery such as a lithium ion battery.

  Treatment methods that recycle used or defective batteries (hereinafter referred to as waste batteries), such as lithium-ion batteries, and recover valuable metals contained in them are roughly divided into dry methods and wet methods. is there.

  The dry method is performed by roasting or melting the crushed battery, and the elements such as nickel, cobalt, and copper that are to be recovered are recovered as an alloy, and the low-value-added elements such as iron are recovered as slag. Is.

  For example, Patent Document 1 discloses a method capable of recovering about 80% of valuable metals such as nickel and cobalt by using a high-temperature heating furnace, adding flux to a waste battery, and repeatedly treating slag. Yes.

US Pat. No. 7,169,206

  However, since what is obtained by the dry method is an alloy, an additional step is required to finally recover the valuable metal as a single element. It is conceivable to perform a wet process at this time. However, since the wet process requires processing time for unit operations such as dissolution and precipitation as compared with the dry process, the wet process is simply combined with the dry process. The process became the rate-limiting step in production, and there was a problem that the mass rapid processing that is the merit of the dry method could not be fully utilized.

  Further, the specific method for recovering valuable metals from the alloy after the dry process is not disclosed in the above-mentioned Patent Document 1, and finally the valuable metals can be recovered as a single element using the dry method. There is a need for an economic system.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for recovering valuable metals from a waste battery that improves the total processing speed by taking advantage of the dry method. .

  The inventors pay attention to combining a wet process after a dry process capable of mass processing, and further, at this time, by selecting an alloy shape in the dry process, the dissolution rate in the subsequent wet process can be reduced. The present inventors have found a method that can be greatly improved and have completed the present invention. More specifically, the present invention provides the following.

(1) A method for recovering valuable metals from waste batteries,
A dry process of melting the waste battery and flux to recover slag and an alloy of valuable metals;
A wet process for separating the valuable metal from the alloy of the valuable metal,
A valuable metal recovery method characterized in that the valuable metal alloy in the dry process is obtained as a granular material.

(2) The valuable metal recovery method according to (1), wherein the granular material has an average surface area of 1 mm ² to 300 mm ² .

  (3) The valuable metal recovery method according to (1) or (2), wherein the waste battery is a lithium ion battery.

  (4) The valuable metal recovery method according to any one of (1) to (3), wherein a processing amount of the waste battery is 1 t or more per day.

  According to the present invention, by obtaining an alloy of valuable metals in the dry process as a granular material, that is, a shot alloy, the solubility in the wet process is improved, and the processing capacity of the waste battery is fully exploited by the advantages of the dry process. Can be greatly improved.

It is a flowchart which shows the valuable metal collection | recovery method from a waste battery which is an example of this invention. It is a flowchart which shows an example of a wet process.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing an example of a valuable metal recovery method from a waste battery. In the present embodiment, a case where the waste battery is a lithium ion battery will be described, but the present invention is not limited to this.

<Overall process>
As shown in FIG. 1, this valuable metal recovery method includes a waste battery pretreatment process ST10, a dry process S20, and a wet process S30. Thus, the present invention is a total process in which an alloy is obtained in the dry process S20, and then valuable metal elements are separated and recovered in the wet process S30. In addition, the waste battery in the present invention means not only a used battery but also a defective product in the process. Moreover, what is necessary is just to include a waste battery in the process target, and adding other metals, resin, etc. other than a waste battery suitably is not excluded. In that case, it is a waste battery of the present invention including other metals and resins.

<Waste battery pretreatment step ST10>
The waste battery pretreatment step ST10 is performed for the purpose of preventing explosion of the waste battery. That is, since the waste battery is a closed system and has an electrolytic solution or the like inside, if the dry melting process is performed as it is, there is a risk of explosion and it is dangerous. For this reason, it is necessary to perform an opening process for degassing by some method. This is the purpose of performing the waste battery pretreatment step ST10.

  Although the specific method of waste battery pre-processing process ST10 is not specifically limited, For example, what is necessary is just to physically open a hole in a waste battery with a needle-shaped blade edge. In the present invention, since a melting process is performed in the subsequent dry processing, it is not necessary to separate individual members.

<Dry process 20>
In the dry process S20, a melting process ST21 is performed in which the pretreated waste battery obtained in the waste battery pretreatment process ST10 is melted at around 1500 ° C. Melting process ST21 can be performed with a conventionally known electric furnace or the like.

  Here, air, oxygen, or oxygen-enriched air is blown in order to adjust the degree of oxidation and improve the recovery rate of nickel, cobalt, and copper. For example, aluminum foil is used as a positive electrode material for lithium ion batteries. Carbon is used as the negative electrode material. Further, the outer shell of the battery is made of iron or aluminum, and plastic is used for the outer package of the assembled battery. These materials basically act as a reducing agent. For this reason, the total reaction of melting these materials into gas or slag is an oxidation reaction. Therefore, it is necessary to introduce oxygen into the system. This is why air is introduced in the melting step ST21.

In addition, in the melting step ST21, SiO _2, CaO, or the like is added as a flux in order to lower the melting point of the slag separated in the slag separation ST22 described later.

  Through the melting step ST21, an alloy of nickel, cobalt, and copper, which are valuable metals, and slag, which is an oxide such as iron or aluminum, are generated. Since they have different specific gravities, they are recovered respectively by slag separation S22 and alloy separation ST23. At this time, when aluminum that is easily oxidized is contained in the slag, alumina is produced as a slag having a high melting point and a high viscosity. As described above, SiO2 and CaO are added to lower the melting point of the slag in the melting step ST21. Therefore, the viscosity can be reduced by lowering the melting point of the slag. For this reason, the slag separation 22 can be performed efficiently. Note that dust, exhaust gas, and the like in the melting step ST21 are detoxified in a conventionally known exhaust gas treatment ST24.

After the alloy separation ST23, a dephosphorization step ST25 is further performed from the obtained alloy. In a lithium ion battery, an organic solvent such as ethylene carbonate or diethyl carbonate, LiPF ₆ (lithium hexafluorophosphate) or the like is used as an electrolyte as a lithium salt. Although phosphorus in this LiPF ₆ has the property of being relatively easily oxidized, it has a property of relatively high affinity with iron group elements such as iron, cobalt and nickel. Phosphorus in the alloy is difficult to remove in the subsequent wet process of recovering each element as a metal from the alloy obtained by the dry process, and accumulates as impurities in the processing system, so that the operation cannot be continued. For this reason, it is removed in this dephosphorization step ST25.

  Specifically, lime that generates CaO by reaction is added and oxygen-containing gas such as air is blown to oxidize phosphorus in the alloy and absorb it in CaO.

  When the waste battery is a lithium ion battery, the alloy obtained in this way is composed of cobalt, nickel derived from the positive electrode material, lithium derived from the electrolyte, copper derived from the conductive material of the negative electrode, and the like.

<Alloy shot process S26>
Next, the alloy shot forming step ST26 that is a feature of the present invention will be described. In the present invention, when the alloy is cooled and obtained at the end of the dry step S20, it is obtained as a granular material (also called a shot alloy or simply a shot). Thereby, melt | dissolution process ST31 in subsequent wet process S30 can be performed in a short time.

  As will be described later, the present invention combines the dry process and the wet process by making the dry process a pretreatment in a broad sense to obtain an alloy with few impurities and greatly reducing the amount of processing to be put into the wet process. Make it possible. However, since the wet process is basically a complicated process that is not suitable for mass processing, it is necessary to perform the processing time of the wet process, especially the dissolution process ST31 in a short time in order to combine with the dry process. Therefore, in the present invention, the melting time can be shortened by granulating the alloy.

Here, the granules, it is preferable that the average surface area in terms of the surface area is 300 mm ² from 1 mm ^2, it is preferable from 0.4mg Speaking in average weight in the range of 2.2 g. If it is less than the lower limit of this range, it is not preferable because the particles are too fine and difficult to handle, and further, the reaction is too early and it becomes difficult to dissolve at once due to excessive heat generation. If the upper limit is exceeded, the dissolution rate in the subsequent wet process decreases, which is not preferable. As a method of granulating the alloy by shot, a conventionally known method of quenching by inflow of molten metal into flowing water can be used.

<Wet process S30>

  The valuable metal recovery process from the waste battery is meaningless if it is recovered as an alloy as in Patent Document 1, and needs to be recovered as a valuable metal element. In the present invention, waste batteries are treated in advance in a dry process to reduce impurities such as phosphorus that are difficult to remove by a wet process. And the latter wet process can be simplified by setting it as the alloy only of the above valuable metals. At this time, it is also advantageous for the combination with the wet process that the wet processing amount is reduced from about ¼ to about ３ in mass ratio as compared with the amount of the input waste battery.

  As described above, the present invention makes it possible to industrially combine a dry process and a wet process by obtaining an alloy with few impurities by making the dry process a pretreatment in a broad sense and greatly reducing the processing amount. There is a feature in the point.

  A conventionally well-known method can be used for a wet process, and it does not specifically limit. For example, in the case where the waste battery is a lithium ion battery, in the case of an alloy made of cobalt, nickel, copper, and iron, as shown in FIG. The valuable metal element can be recovered through the element separation step ST32 in the procedure of recovery, nickel / cobalt separation, nickel recovery, and cobalt recovery. And in this invention, since the alloy thrown into melt | dissolution process ST31 is a granular shot-ized alloy, rapid acid melt | dissolution is attained. This point will be described in Examples.

<Processing amount>
The method of the present invention is an unprecedented method for recycling waste batteries, which combines a dry process suitable for large-scale treatment and a wet process suitable for small-scale treatment. And a large amount of processing is possible to perform the dry process first. The present invention can be suitably used when it is at least 1 t or more per day, preferably 10 t or more per day.

  The type of waste battery is not particularly limited, but a rare metal such as cobalt or lithium can be recovered, and its use has been expanded to batteries for automobiles. A lithium ion battery that requires a large-scale recovery process is the present invention. It can illustrate preferably as a process target.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

<Example 1>
In an alumina crucible installed in an electric furnace, an alloy obtained by melting a waste lithium battery with a flux at 1450 ° C and oxidizing it by blowing oxygen into the melt is connected to the tip of a syringe with a silicon tube. The sample was sucked into a quartz tube having an inner diameter of about 4 mm and dropped while stirring water in about 20 L of water stretched in a metallic container. The amount of dropped alloy at one time was about 3 g. After repeating this operation several times, water was drained and the alloy which became granular at the bottom of the container was recovered. Alloy has become spherical shot, the particle size was approximately within the range of the total amount 1 to 3 mm (in the range from 3.1 mm ² to 28.3 mm ² in surface area). About 15 g of this shot alloy was put into 200 ml of a 60 wt% sulfuric acid solution and dissolved at about 60 ° C., and the entire amount was dissolved within 1 hour.

<Comparative Example 1>
After melting and oxidizing treatment under the same conditions as in Example 1, after cooling in the furnace as it is, 16.5 g of a button-like alloy obtained by separating from slag was dissolved in the same way as in Example 1. When the treatment was performed, the undissolved alloy remained even after 8 hours or more.

ST10 Waste battery pretreatment process S20 Dry process ST21 Melting process ST22 Slag separation ST23 Alloy separation ST24 Exhaust gas treatment ST25 Dephosphorization process ST26 Alloy shot process S30 Wet process ST31 Dissolution process ST32 Element separation process

Claims (4)

A method for recovering valuable metals from waste batteries,
A dry process of melting the waste battery and flux to recover slag and an alloy of valuable metals;
A wet process for separating the valuable metal from the alloy of the valuable metal,
A valuable metal recovery method characterized in that the valuable metal alloy in the dry process is obtained as a granular material. The valuable metal recovery method according to claim 1, wherein the granular material has an average surface area of 1 mm ² to 300 mm ² .   The valuable metal recovery method according to claim 1, wherein the waste battery is a lithium ion battery.   The valuable metal recovery method according to any one of claims 1 to 3, wherein a processing amount of the waste battery is 1 t or more per day.

Images