JP5434935B2 - Valuable metal recovery method - Google Patents

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.

  In the dry method, crushed waste batteries are melted, and valuable metals, such as cobalt, nickel, and copper, and other metals with low added value, such as iron and aluminum, are recovered. Separation and collection are performed using the difference in oxygen affinity between the two. That is, an element with low added value such as iron is oxidized as much as possible to obtain slag, and valuable materials such as cobalt are recovered as an alloy while suppressing oxidation as much as possible.

  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

  Since iron and cobalt have similar oxygen affinity, the oxidation reaction of both elements occurs competitively. For this reason, it is theoretically impossible to oxidize 100% of iron and recover all of it to the slag side, and to recover all of it to the alloy side without oxidizing 100% of cobalt. For this reason, in practice, the recovery rate of cobalt as a metal is improved by adjusting the oxidation degree so that the oxidation degree of iron is less than 100% and a certain ratio is distributed to the alloy side. That is, the cobalt recovery rate is improved by allowing a certain amount of iron to be present in the alloy by adjusting the oxidation degree. Since iron in the alloy is an unnecessary metal that is separated and removed in a later wet process, the amount of iron in the alloy is preferably as small as possible.

  As another element affecting the competitive oxidation reaction of iron and cobalt, there is aluminum contained in a large amount as a positive electrode conductive material of a lithium ion battery. Aluminum has an oxygen affinity much higher than that of iron or cobalt, and easily becomes aluminum oxide. Therefore, when aluminum coexists, aluminum consumes oxygen preferentially during oxidation, resulting in insufficient iron oxidation, resulting in a decrease in iron distribution to slag and an increase in the amount of iron in the alloy. There is.

  Another problem is that if the content of aluminum oxide in the slag is relatively high, the melting temperature becomes high and the viscosity of the slag becomes high, and the alloy is physically dragged to the slag side during slag separation and recovery. As a result, there is also a problem that the recovery rate as an alloy is lowered.

  Due to these causes, particularly in the presence of aluminum, the amount of iron in the alloy necessary for obtaining a predetermined cobalt recovery rate is further increased as compared with the two elements of iron and cobalt. In the treatment of waste batteries, it has been difficult to achieve both a high distribution ratio of iron into the slag and a high distribution ratio of cobalt into the alloy.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a valuable metal recovery method capable of stably and significantly increasing the recovery rate in recovering valuable metals from waste batteries by a dry method. It is to provide.

  The inventors of the present invention divided the slag separation into two steps and separated it into two stages, separated the first slag mainly composed of aluminum oxide in the first first slag separation step, and then the second slag separation step. By separating the second slag mainly composed of iron oxidized in step 2, it is possible to form a second slag having good separability from the alloy at a low melting temperature in the second slag separation step. It has been found that the separation performance can be dramatically improved, and the present invention has been completed. More specifically, the present invention provides the following.

(1) A method for recovering valuable metals from waste batteries containing aluminum and iron,
A melting step of melting the waste battery to obtain a melt,
A first oxidation step that is performed on the melt during the melting step or the waste battery before the melting step, and the aluminum is treated with an oxidizable degree;
Separating a first slag containing aluminum oxide from the melt to obtain a first alloy containing iron;
A second oxidation step for treating the first alloy or the melt thereof with an oxidation degree capable of oxidizing the iron;
A valuable metal recovery method comprising: a second slag separation step of separating a second slag containing iron oxide from the melt after the second oxidation step and recovering a second alloy containing cobalt.

  (2) The valuable metal recovery method according to (1), wherein a mass ratio of iron in the first alloy in the total iron in the waste battery is 30% or more and 100% or less.

(3) The mass ratio of cobalt in the second alloy in the total cobalt in the waste battery is 75% or more,
The valuable metal recovery method according to (1) or (2), wherein a mass ratio of iron in the second alloy in the total iron in the waste battery is 7% or more and 30% or less.

  (4) Any of (1) to (3), wherein the first oxidation step is performed on the waste battery before the melting step, and the waste battery is roasted to perform a preliminary oxidation treatment. The valuable metal recovery method described.

  (5) The valuable metal recovery method according to (4), wherein the preliminary oxidation step is performed at 600 ° C. or higher and 1250 ° C. or lower.

  (6) The valuable metal recovery method according to any one of (1) to (5), wherein the second slag separation step is performed at 1350 ° C. or higher and 1550 ° C. or lower.

  (7) The valuable metal recovery method according to any one of (1) to (6), wherein the waste battery is a lithium ion battery.

  According to the present invention, in a method for recovering valuable metals such as cobalt from a waste battery containing aluminum and iron, a preliminary oxidation step for performing an oxidation treatment prior to the dry step is provided, and in the dry step, mainly from the melt. A first slag separation step for separating aluminum oxide and a second slag separation step for separating and removing iron mainly from the first alloy from which aluminum oxide was separated and removed in the first slag separation step were provided. Thus, through the two-stage slag separation step, separation performance between valuable metals such as cobalt and slag such as iron can be remarkably enhanced, and valuable metals can be recovered stably at a high recovery rate. It becomes possible.

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 cross-sectional schematic diagram which shows the use condition of the kiln used for the oxidation process in the preliminary oxidation process of this invention. It is a graph which shows the distribution rate to the metallic iron and metallic cobalt in an alloy in an Example and a comparative example.

  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, the valuable metal recovery method includes a waste battery pretreatment process ST10, a preliminary oxidation process ST20, a dry process S20, and a wet process S30. Thus, the valuable metal recovery method in the present embodiment is a total process in which an alloy is obtained in the dry process S20, and then the valuable metal element is 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 sealed system and has an electrolyte solution or the like inside, if the dry melting process is performed as it is, there is a risk of explosion, which 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, separation of individual members or the like is not necessary.

<Pre-oxidation process ST20 (first oxidation process)>

  This pre-oxidation step ST20 is a preferable step of the first oxidation step in the present invention, and in the present invention, “the melt is performed on the melt during the melting step, and the aluminum is treated with an oxidizable degree of oxidation. This corresponds to the “first oxidation step”.

  In the preliminary oxidation step ST20, the preliminary oxidation treatment is performed by supplying oxygen while roasting the pretreated waste battery obtained in the waste battery pretreatment step ST10 at a temperature of 600 ° C to 1250 ° C. In the conventional valuable metal recovery method, the oxidation treatment is performed in the melting step in the dry process. However, in the valuable metal recovery method of the present invention, as the first oxidation step, the preliminary oxidation step ST20 before the melting step ST21. By implementing the pre-oxidation treatment in the process, it is possible to implement in a more preferable embodiment.

  This pre-oxidation treatment is performed before the melting step ST21, and is performed in the preliminary oxidation furnace by providing a pre-oxidation furnace separately from the melting furnace performing the melting step ST21. A kiln can be used as the preliminary oxidation furnace. As an example, a rotary kiln that has been conventionally used for cement production and the like can be suitably used. Therefore, the details of the present invention will be described below using the rotary kiln as a representative example of the kiln, but the kiln in the present invention is not limited thereto. Absent. For example, it includes all types of kilns such as a tunnel kiln (Heath Furnace) that can be oxidized inside by supplying oxygen while roasting waste batteries in the preliminary oxidation step ST20.

  In the present embodiment, the preliminary oxidation step ST20 is performed by using the kiln 1 shown in FIG. 2 as a preliminary oxidation furnace. As shown in FIG. 2, the kiln main body 10 is a cylindrical rotary kiln made of carbon steel having a thickness of 15 to 30 mm. The interior is lined with refractory bricks. A drive gear 11 is provided outside the kiln body 10 to transmit the rotational force to the kiln body. Further, a burner pipe 12 for blowing hot air for heating the inside is provided in the kiln main body. The kiln main body 10 provided with these is installed so as to have an inclination of 3 to 4% with respect to the horizontal plane in use.

  In the preliminary oxidation step ST20 using the kiln 1, first, the temperature inside the kiln main body 10 is heated to 600 to 1250 ° C. with hot air blown from the burner pipe 12. Next, while the kiln main body 10 is rotated in the R direction by the drive gear 11, the waste battery is carried in from the carry-in port 13 in the A direction. The waste battery moves in the kiln body 10 toward the discharge port 14 while being stirred and roasted along the inclination of the kiln body 10. At this time, if the temperature in the kiln main body 10 is less than 600 ° C., the oxidation of aluminum and carbon does not proceed sufficiently. If the temperature is in the range of 600 ° C. to 1250 ° C., the oxidation of aluminum and carbon proceeds sufficiently, while the oxidation of iron remains at a relatively low degree of oxidation. Therefore, in the subsequent first slag separation step Only aluminum oxide can be suitably slag separated. Further, when the temperature exceeds 1250 ° C., a part of iron or the like mainly used for the outer shell of the waste battery adheres to the inner wall of the kiln main body 10 and hinders smooth operation. Alternatively, it may lead to deterioration of the kiln itself, which is not preferable.

  As described above, in order to adjust the oxidation degree of the waste battery moving through the kiln main body 10 while being roasted at a temperature of 600 to 1250 ° C., an appropriate amount of oxidizing agent (for example, air) is added to the kiln main body 10. Introduce. For example, aluminum foil is used as a positive electrode material for lithium ion batteries. Carbon is used as the negative electrode material. Furthermore, 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 for converting these materials into gas or slag is an oxidation reaction. Therefore, it is necessary to introduce oxygen into the kiln body 10. This is why air is introduced in the pre-oxidation step ST20.

  Although the oxidizing agent is not particularly limited, a gas containing oxygen such as air, pure oxygen, and oxygen-enriched gas is preferably used from the viewpoint of easy handling. These are directly fed into the kiln body 10 in the preliminary oxidation step ST20. The amount of oxidant introduced here is approximately 1.2 times the chemical equivalent required for the oxidation of each substance to be oxidized.

  The waste battery oxidized through the above process is discharged from the discharge port 14 in the B direction. The exhaust gas generated during the oxidation process is discharged in the C direction.

  Since the preliminary oxidation step ST20 in the present invention is an oxidation treatment at a lower temperature than the case where the oxidation treatment is performed in the melting step ST21, the reaction rate is relatively slow, and the cylindrical kiln body 10 This is a method of oxidizing a waste battery moving in the kiln main body 10 by directly introducing a predetermined amount of oxygen into the space, so that the oxidation can be controlled by adjusting the oxygen amount, oxidation time, temperature, etc. Easy. Therefore, it is possible to adjust the degree of oxidation more strictly while suppressing variations in oxidation.

  The adjustment of the degree of oxidation in the preliminary oxidation step ST20 is performed as follows. The main elements constituting the material of the waste battery are generally oxidized in the order of aluminum> lithium> carbon> manganese> phosphorous> iron> cobalt> nickel> copper due to the difference in affinity with oxygen. That is, aluminum is most easily oxidized and copper is most hardly oxidized. In the preliminary oxidation step ST20, first, oxidation is promoted until the entire amount of aluminum is oxidized. At this time, the oxidation may be further promoted until a part of iron is oxidized, but it is necessary to stop the oxidation degree so that cobalt is not oxidized and recovered to the slag side. This is the meaning of “treating aluminum with an oxidizable degree of oxidation” in the present invention. As described above, in the preliminary oxidation step ST20, such a strict degree of oxidation can be adjusted by adjusting the amount of oxygen, the oxidation time, and the temperature. By adjusting the degree of oxidation in this way, almost the entire amount of aluminum oxide can be separated as the first slag in the first slag separation step ST22.

  In addition, the 1st oxidation process in this invention is not limited to the above-mentioned preliminary oxidation process by roasting. Like 2nd oxidation process ST23 mentioned later, a lance is inserted in the melt in the melting process ST21 and air Alternatively, bubbling may be performed by blowing an oxidizing agent such as the above. This corresponds to the “first oxidation step performed on the waste battery before the melting step and treating the aluminum with an oxidizable degree” in the present invention.

<Melting step ST21>
In the dry step S20, a melting step ST21 is first performed in which the waste battery subjected to the preliminary oxidation process in the preliminary oxidation step ST20 is melted at a temperature of 1450 ° C. or higher, preferably 1650 ° C. or lower to obtain a molten waste battery. Melting process ST21 can be performed with a conventionally known electric furnace or the like. The melt produced by the melting step ST21 includes a first slag containing an oxide such as aluminum, a valuable metal such as nickel, cobalt, copper, and a first alloy containing iron that is not a valuable metal. included. When the preliminary oxidation step ST20 is performed, the oxidation treatment is not performed here.

In the melting step ST21, SiO ₂ (silicon dioxide), CaO (lime), or the like is added as a flux to the melt of the waste battery. The ratio of SiO ₂ / CaO here is preferably between 0.5 and 1.5, more preferably between 0.8 and 1.1. Thereby, the melting temperature of the 1st slag isolate | separated by 1st slag isolation | separation process ST22 mentioned later can be lowered | hung. The addition of the flux does not necessarily have to be performed in the melting step ST21, and the same effect can be obtained even if it is performed in the preliminary oxidation step ST20 preceding the melting step ST21. Note that the dust, exhaust gas, and the like in the melting step ST21 are detoxified in a conventionally known exhaust gas treatment.

<First slag separation step ST22>
In the first slag separation step ST22, the first slag and the first alloy are separated and recovered using the specific gravity difference. The high-melting aluminum oxide having a high melting temperature mainly contained in the first slag is discharged out of the furnace here. As will be described later, the first alloy is subsequently subjected to steps such as a second oxidation step ST23 and a second slag separation step ST24 in the furnace.

Empirically, it is known that slag containing a large amount of aluminum oxide (Al ₂ O ₃ ) has a high melting temperature and becomes a highly viscous slag. In order to efficiently separate and recover such slag, it is necessary to raise the temperature to near the melting temperature and sufficiently reduce the viscosity of the slag. However, increasing the melting temperature increases the energy cost and melts the refractory. It is not preferable because the operating cost is greatly increased due to an increase in loss speed. In particular, when the temperature exceeds 1650 ° C., it becomes difficult to operate using a normal electric furnace, and it is necessary to use a plasma treatment or the like as described in Patent Document 1, and the durability of the refractory is also reduced. Thermocouple damage for in-furnace temperature measurement also occurs. It is preferable that the melting temperature of slag is 1450 degreeC or more and 1650 degrees C or less also from a viewpoint of performing melting process ST21 with a conventionally well-known electric furnace, and a melting temperature of the alloy to produce | generate. In the valuable metal recovery method of the present invention, the first slag contains a large amount of aluminum oxide, but since a predetermined ratio of flux is added in the melting step ST21, the melting temperature of the first slag decreases. And sufficiently low viscosity. For this reason, even if it performs melting process ST21 at the said temperature, isolation | separation with a 1st slag and a 1st alloy can be performed without a problem.

  With respect to aluminum and iron, the respective distribution ratios in the first alloy and in the first slag are obtained by removing aluminum as aluminum oxide in the first slag separation step ST22 to the slag side. The distribution rate of aluminum is extremely low. Specifically, the mass ratio of the waste battery to the total amount of aluminum is 0% by mass or more and 0.1% by mass or less, and aluminum close to the total amount is distributed to the first slag. Thus, the present invention is excellent in that the separation performance of iron and cobalt can be greatly improved in the subsequent second slag separation step. At this time, the iron content (distribution rate) in the first alloy is high, and is preferably 30% or more and 100% or less in terms of mass ratio to the total amount of iron in the waste battery. If the iron distribution rate is less than 30%, iron is excessively distributed to the slag side, and cobalt is also partially distributed to the first slag, which is not preferable.

<Second oxidation step ST23>
Subsequently, in the second oxidation step ST23, oxidation treatment is performed on the first alloy. This oxidation treatment can be performed by oxygen bubbling in which a straw-shaped cylinder called a lance made of iron-based material is inserted into the melt and oxygen is blown. In addition, the melt here may be the melt of the first alloy obtained in the first slag separation step ST22 itself, or may be a melt that is once cooled and then melted again. By this second oxidation step ST23, a second slag that is an oxide such as iron and a second alloy containing nickel, cobalt, and copper as valuable metals are generated.

Here, SiO ₂ (silicon dioxide), CaO (lime), and the like are added as fluxes as in the melting step ST21, but the ratio of SiO ₂ / CaO here is not particularly limited. For example, a large amount of silicon dioxide having a relatively low cost can be blended, and the blending ratio can be set between 2 and 6. The difference from the melting step ST21 is that, as described above, the first alloy does not contain or contains aluminum oxide, which is the main cause of increasing the viscosity of the slag at a high melting temperature. This is because the amount is extremely small.

<Second Slag Separation Step ST24>
In the second slag separation step ST24, the second slag and the second alloy are separated and recovered from the oxidized first alloy using the specific gravity difference. The second slag is discharged out of the furnace, and the second alloy is subsequently subjected to a dephosphorization step ST25 and an alloy shot step ST26.

  Here, the melting temperature of the oxidized first alloy is about 1350 ° C. In the present invention, in the first slag separation step ST22, the aluminum oxide that raises the melting temperature of the slag and increases the viscosity is separated and removed. It is possible to help improve the fluidization of the slag and lower the melting temperature of the second slag to about 1250 ° C., which is lower than the melting temperature of the first alloy. As a result, the recovery rate of valuable metals can be improved by improving the physical separation performance from the second alloy due to the decrease in viscosity. For this reason, the temperature of the melt in the second slag separation step ST24 is sufficient to be about 1350 ° C to 1550 ° C.

  In the first slag separation step ST22, aluminum was removed to the slag side as aluminum oxide. As a result, with respect to aluminum and iron, the respective distribution ratios in the second alloy and the first and second slags are even if the distribution ratio of iron in the second alloy is low. Can be high. That is, in the present invention, the separation performance of iron and cobalt in the second alloy is remarkably improved. This is an excellent effect of the present invention.

  Specifically, the distribution ratio (mass ratio) of iron in the second alloy with respect to the total iron mass in the waste battery is the same as the total cobalt in the waste battery if the iron mass ratio is 7% or more. The distribution ratio (mass ratio) of cobalt in the second alloy with respect to the mass is 75% or more. This means that even if the iron distribution rate is as low as 7%, the cobalt recovery rate can be 75% or more, compared to the case where aluminum oxide coexists in the slag separation stage as in the prior art. This is an epoch-making method in which the recovery rate of cobalt can be improved even if the distribution rate of iron in the alloy is greatly reduced. This point will be described in detail in the embodiments described later.

<Dephosphorization step ST25>
Subsequent to the second slag separation step ST24, a phosphorus removal step ST25 is performed on the second alloy to remove phosphorus from the second alloy. In lithium ion batteries, ethylene carbonate, diethyl carbonate, or the like is used as an organic solvent, and LiPF ₆ (lithium hexafluorophosphate) or the like is used as an electrolyte as an electrolyte. 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 dry processing, and if it accumulates in the processing system as an impurity, the operation cannot be continued. This can be prevented by removing phosphorus in advance in the dephosphorization step ST25.

  Specifically, by adding lime or the like that generates CaO by reaction and blowing in an oxygen-containing gas such as air, phosphorus in the alloy can be oxidized and absorbed into CaO. When the waste battery is a lithium ion battery, the alloy that has undergone the dephosphorization step ST25 is composed of cobalt, nickel, electrolyte-derived lithium, negative electrode material conductive copper, and the like derived from the positive electrode material.

<Alloy shot process ST26>
At the end of the dry process S20, an alloy shot forming process ST26 is performed. In this step, when the alloy that has undergone the dephosphorization step ST25 is cooled, a granular material (also called a shot alloy or simply a shot) is used.

  As will be described later, by combining the dry process S20 and the wet process S30 by obtaining an alloy with few impurities by making the dry process S20 a pretreatment in a broad sense and significantly reducing the amount of processing to be put into the wet process S30. Is possible. However, since the wet process S30 is basically a complicated process that is not suitable for mass processing, in order to combine with the dry process S20, it is necessary to perform the processing time of the wet process S30, in particular, the dissolution process ST31 in a short time. In the alloy shot forming step ST26, 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. By treating the waste battery in advance in a dry process, an alloy of only valuable metals as described above can be used to simplify the subsequent wet process. 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.

  Thus, it is industrially possible to combine the dry process S20 and the wet process S30 by obtaining an alloy with few impurities by making the dry process S20 a pretreatment in a broad sense and greatly reducing the processing amount.

  The wet process S30 can use a conventionally known method and is not particularly limited. For example, in the case of an alloy composed of cobalt, nickel, copper, and iron when the waste battery is a lithium ion battery, after acid dissolution (dissolution step ST31), iron removal, copper separation recovery, nickel / cobalt separation, Valuable metal elements can be recovered through the element separation step ST32 in the procedures of nickel recovery and cobalt recovery.

  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 automobile batteries, etc., and 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 and a comparative example demonstrate this invention further more concretely, this invention is not limited to a following example.

  First, examples will be described. In the embodiment, as shown in FIG. 1, a preliminary oxidation process is provided prior to the melting process to perform a preliminary oxidation process (first oxidation process), and then a melting process is provided to perform the melting process. 1 slag separation, oxidation treatment, and second slag separation were performed.

  In the preliminary oxidation step, about 23 g of a waste lithium ion battery (hereinafter referred to as “sample”) is kept in an alumina crucible at a temperature of 900 ° C. to 1250 ° C. for 30 minutes by heating in a nitrogen atmosphere. Oxygen was blown through the alumina tube to accelerate the oxidation until the total amount of aluminum was oxidized, and a preliminary oxidation treatment was performed.

Subsequently, in the melting step, 7.2 g of a mixed flux having a SiO ₂ / CaO ratio of 1 is added to the sample in the alumina crucible oxidized by the preliminary oxidation treatment, and then the sample is heated from 1450 ° C. by raising the temperature in a nitrogen atmosphere. It was melted at a temperature in the range of 1500 ° C. and held for 1 hour.

  After the holding, the first slag separation step was performed by separating and collecting the first slag and the first alloy from the melted sample using the specific gravity difference.

Subsequently, after adding 7.2 g of a mixed flux having a SiO ₂ / CaO ratio of 4, an oxidation treatment was performed on the first alloy after the first slag separation step (second oxidation step). This oxidation treatment was performed by inserting a straw-shaped cylinder called an lance made of alumina material into the melt, and performing oxygen bubbling by blowing 10 L of oxygen, and maintaining the temperature at 1450 ° C. for 1 hour.

  The alloy that had undergone the oxidation treatment was cooled in the furnace, and after cooling, the slag and the alloy were separated and recovered to perform second slag separation. The distribution ratio of metallic iron and metallic cobalt was analyzed by the ICP method for the second alloy that had undergone the second slag separation.

  Next, a comparative example will be described. In the comparative example, the preliminary oxidation treatment was not performed as a difference from the example. The melting process was first performed without going through the preliminary oxidation process, followed by oxidation treatment and slag separation.

In the melting process, in an alumina crucible installed in an electric furnace in a nitrogen atmosphere, about 23 g of waste lithium ion battery is within a range of 1450 ° C. to 1500 ° C. with a mixed flux of 7.3 g of SiO ₂ / CaO ratio of 1. For 30 minutes. After holding, the sample was oxidized by blowing 20 L of oxygen through an alumina tube. After oxidation, it was held for 30 minutes and then cooled in the furnace. After cooling, slag and alloy were separated and recovered, and analyzed by the ICP method.

  Table 1 and FIG. 3 show the distribution ratios of metallic iron and metallic cobalt in the alloy (in the second alloy in the example) in the results of Examples and Comparative Examples. Here, the distribution ratio is the mass ratio of the amount of metal element present in the alloy (in the second alloy in the embodiment) to the total mass of the specific metal element in the used waste battery, and is determined by the above ICP method. It is measured. In addition, the continuous line and wavy line in FIG. 3 show the theoretical value about the distribution rate of each metal in each of Examples and Comparative Examples.

  As can be seen from Table 1 and FIG. 3, in the examples, the distribution ratio of iron in the alloy, that is, the mass ratio of metallic iron in the alloy to the total iron amount in terms of iron element was set to 7% or more. In this case, when the recovery rate of metallic cobalt is 75% or more and the mass ratio of metallic iron is 18% or more, the recovery rate of metallic cobalt can be 90% or more. This is an ideal recovery rate that is close to the theoretical limit that can be obtained theoretically, especially when the mass ratio of metallic iron is in the range of 40% or less. It can be understood that the performance is remarkably improved.

ST10 Waste battery pretreatment process ST20 Pre-oxidation process S20 Dry process ST21 Melting process ST22 First slag separation process ST23 Second oxidation process ST24 Second slag separation process ST25 Dephosphorization process ST26 Alloy shot process S30 Wet process ST31 Melting process ST32 Element Separation Process 1 Kiln 10 Kiln Main Body 11 Drive Gear 12 Burner Pipe 13 Carry In 14 Outlet

Claims (7)

A method for recovering valuable metals from waste batteries containing aluminum and iron,
A melting step of melting the waste battery to obtain a melt,
A first oxidation step that is performed on the melt during the melting step or the waste battery before the melting step, and the aluminum is treated with an oxidizable degree;
Separating a first slag containing aluminum oxide from the melt to obtain a first alloy containing iron;
A second oxidation step for treating the first alloy or the melt thereof with an oxidation degree capable of oxidizing the iron;
A valuable metal recovery method comprising: a second slag separation step of separating a second slag containing iron oxide from the melt after the second oxidation step and recovering a second alloy containing cobalt.   2. The valuable metal recovery method according to claim 1, wherein a mass ratio of iron in the first alloy in the total iron in the waste battery is 30% or more and 100% or less. The total mass of cobalt in the second battery is 75% or more by mass of cobalt in the second alloy,
The valuable metal recovery method according to claim 1 or 2, wherein a mass ratio of iron in the second alloy is 7% or more and 30% or less in all iron in the waste battery.   4. The valuable metal recovery according to claim 1, wherein the first oxidation step is a pre-oxidation step in which the waste battery before the melting step is performed and the waste battery is roasted to perform a pre-oxidation treatment. 5. Method.   The valuable metal recovery method according to claim 4, wherein the preliminary oxidation step is performed at 600 ° C. or higher and 1250 ° C. or lower.   The valuable metal recovery method according to claim 1, wherein the second slag separation step is performed at 1350 ° C. or higher and 1550 ° C. or lower.   The valuable metal recovery method according to claim 1, wherein the waste battery is a lithium ion battery.

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