JP7399586B2 - Method of recovering valuable elements - Google Patents

Description

The present invention relates to a valuable element recovery technique for recovering valuable elements such as Co and Ni from oxides containing _{Al2O3 , CoOx} , and _NiOx .

In recent years, as environmental regulations have become stricter, renewable energy is expected to increase in the future, and as electrification advances to improve vehicle fuel efficiency, secondary batteries are expected to become even more important. There is. For example, the mainstream secondary batteries currently in use are lithium ion batteries (LIB) and nickel metal hydride batteries (Ni-MH), and demand for these secondary batteries is expected to increase in the future.

Here, secondary batteries such as LIB and Ni-MH include rare metals (valuable metals) such as Co and Ni, and valuable elements such as oxides of Li (hereinafter, we will refer to valuable metals and valuable metal oxides, etc.). (together referred to as valuable elements) are used. For example, with regard to cobalt and nickel, which are essential for the production of LIBs (lithium-ion rechargeable batteries), there are problems such as the ubiquity of these resources around the world, and the risk of resource depletion has been pointed out. Furthermore, with regard to cobalt, there have been rumors of unfair labor conditions in mines, and there is a possibility that mining alone will not be able to fully meet the demand.

From these viewpoints, recycling technology for rare metals such as cobalt and nickel is attracting attention. However, currently, wet solvent extraction is the main method, and large-scale processing technology has not been established due to cost issues. Therefore, there is a need for a technology that can inexpensively and efficiently recover valuable metals from LIBs that use cobalt and nickel. High-temperature refining technology (hereinafter referred to as pyrometallurgical refining technology) used in the steelmaking process is relatively inexpensive, and is used in various industries such as automobiles and electrical equipment to meet social recycling issues. It is considered that there is an urgent need to establish the technology so that it can be used in various fields.

For example, Patent Document 1 describes a method of recovering valuable metals from metal oxides containing alkali metals, which efficiently recovers valuable metals from metal oxides containing alkali metals generated during the manufacturing process of secondary batteries. There is. The method for recovering valuable metals described in Patent Document 1 described above involves adding a reducing agent and a slag-forming agent to metal oxides containing alkali metals generated during the manufacturing process of secondary batteries, melting them, and reducing and precipitating valuable metals. is to be collected.

Further, Patent Document 2 describes a method for easily recovering valuable metals with good yield from used lithium secondary batteries. The valuable metal recovery method of Patent Document 2 described above includes a step of roasting a used lithium secondary battery to obtain a roasted product, a step of crushing the roasted product to obtain a pulverized product, and a step of sieving the pulverized product. obtaining a primary valuable metal concentrate as a sieve, and mixing the primary valuable metal concentrate with a calcium compound and then melting and removing the resulting slag to convert the metal into secondary valuable metals. The process consists of recovering it as a concentrate.

Further, Patent Document 3 describes a method that can improve the recovery rate of valuable metals such as cobalt and reduce the recovery cost when dry-processing waste batteries such as lithium ion batteries. The valuable metal recovery method of Patent Document 3 described above includes a preliminary oxidation step ST20 in which a waste battery containing aluminum and iron is roasted and subjected to preliminary oxidation treatment, and a molten product is obtained by melting the waste battery after the preliminary oxidation step ST20. A first slag separation step ST22 of separating and recovering a first slag containing aluminum oxide from the melt, and a first alloy that is the melt after the first slag separation step. Through a second oxidation step ST23 in which oxidation treatment is performed and a second slag separation step ST24 in which a second slag containing iron is separated and recovered from the first alloy after the second oxidation step ST23, iron is removed. In the method for obtaining a second alloy with excellent separation performance of cobalt and cobalt and a low iron content, the second slag is reused as a flux added to accelerate the second and subsequent melting steps ST21b. ing.

Further, Patent Document 4 describes a recycling method for recovering metal from a lithium ion battery. The above-mentioned recycling method of Patent Document 4 is a method of recovering cobalt from a lithium ion battery containing aluminum and carbon, and includes the steps of preparing a bath furnace equipped with a means for injecting O ₂ and a slag forming agent. providing a metallurgical charge comprising CaO and a lithium ion battery, and feeding the metallurgical charge to the furnace with oxygen injection, whereby at least a portion of the cobalt is reduced and the metallurgical charge is reduced; and separating the slag from the metal phase by tapping, the method comprising the steps of collecting the slag in a phase and separating the slag from the metal phase by tapping, the method comprising the steps of: collecting the slag in a metal phase; +0.6C%) [Al% and C% represent the weight percent of aluminum and carbon in the battery] It is characterized by the fact that Patent Document 5 also describes a separation process in which waste secondary batteries are physically separated into separated negative electrode materials and separated positive electrode materials, and valuable metals are extracted from the positive electrode material or separated negative electrode material separated in the separation process. A valuable metal recovery system for recovering valuable metals from waste secondary batteries is described. The valuable metal recovery system of Patent Document 5 described above includes a separation process in which a waste secondary battery is physically separated and separated into a separated negative electrode material and a separated positive electrode material, and a positive electrode material or separated cathode material separated in the separation process. The method includes a step of recovering valuable metals from the negative electrode material.

Further, Patent Document 6 describes a method for reducing the sulfur content generated during the process of recovering valuable metals contained in waste batteries. The method of Patent Document 6 mentioned above is a method for recovering valuable metals from waste batteries or process waste containing at least one valuable metal of cobalt or nickel, and includes (1) preliminary roasting treatment, pulverization treatment, and sieving. (2) a secondary concentration step in which the primary concentrate is dissolved in sulfuric acid and the dissolved solution is obtained as a secondary concentrate; (3) a tertiary concentration step in which an aqueous solution of an alkali metal is added to the secondary concentrate, the hydroxide treatment is performed, and the sulfur reduction treatment is performed by oxidation roasting treatment and water washing treatment to obtain a tertiary concentrate of the valuable metal; and (4) a fourth concentration step of melting the third concentration and recovering the valuable metal.

Japanese Patent Application Publication No. 2000-226619 Japanese Patent Application Publication No. 10-158751 Japanese Patent Application Publication No. 2012-224877 Special table 2013-506048 publication International Publication No. 2000-025382 JP2016-037661A

The technology of Patent Document 1 mentioned above is a technology for recovering valuable metals as an alloy from oxide raw materials containing Li, Mn, Co, Ni, and Fe generated in the manufacturing process of secondary batteries. The raw material does not contain Al in the first place, so it cannot be applied when recovering an alloy from an oxide containing Al. In other words, if the raw material contains Al (Al ₂ O ₃ ), the raw material has a high melting point and cannot be melted, making it difficult to recover valuable metals as an alloy. .

In addition, although the technology of Patent Document 2 describes the amount of CaO/Al ₂ O ₃ , the amount of CaO added is large, and the amount of CaO relative to Al ₂ O ₃ is large, resulting in low productivity and pressure on costs. This does not include alloy recovery when Al ₂ O ₃ is included. Furthermore, there is no description of an appropriate reducing agent ratio.
Further, the technique of Patent Document 3 does not describe the reducing agent ratio necessary for obtaining granular metallic iron.

In addition, as in the case of Patent Document 2, the technique of Patent Document 4 does not include an appropriate reducing agent ratio, and the amount of SiO ₂ and CaO added is large, resulting in SiO ₂ /Al ₂ O ₃ and CaO/ The value of Al ₂ O ₃ is high. Therefore, productivity may be low and costs may be reduced, and alloy recovery when a large amount of Al ₂ O ₃ is contained is not included.
Moreover, the technique of Patent Document 5 does not contain Al ₂ O ₃ in the raw material and cannot be applied to the case where alloy is recovered from an oxide containing Al.

Furthermore, the technology of Patent Document 6 is a method of reducing the residue after removing Cu and C from the bottom of the sieve after incineration, crushing, and sieving with C (coke) or Al, but 100% coke is used as the reducing agent. If Al is used, C/A (CaO/Al ₂ O ₃ ) and S/A (SiO ₂ /Al ₂ O ₃ ) will be around 2.7, resulting in too much flux, and even if Al is used as a reducing agent, , C+A(SiO ₂ +CaO)=1.72, and the amount of flux is too large in this case as well. Therefore, even with the technique of Patent Document 6, productivity is low and there is a possibility that costs may be reduced.

In other words, the techniques disclosed in Patent Documents 1 to 6 described above recover valuable metals by melting and reducing recovered materials from secondary batteries, and flux is added to melt the recovered materials. It has become. However, if the recovered material is slag containing Al ₂ O ₃ , even if flux is added for melting, if too much flux is added, the Co and Ni to be recovered in the mixture will be The quantity decreases, directly deteriorating productivity. For this reason, although it is possible to recover Co and Ni alloys, there is a concern that productivity will deteriorate, which will put pressure on costs and eliminate the advantage of pyrometallurgy, which is relatively low cost.

The present invention has been made in view of the above-mentioned problems, and is a method for recovering valuable elements such as Co, Ni, and even Li oxides from recovered materials containing Al ₂ O ₃ at low cost and in high yield. The purpose is to provide a method for recovering elements.

In order to solve the above problems, the method for recovering valuable elements of the present invention takes the following technical measures.
That is, the method for recovering valuable elements of the present invention includes a mixing step of mixing recovered material from a secondary battery, a reducing agent, and a flux, a reducing step of heating and reducing the mixture, and a cooling of the reduced mixture. In the method for recovering valuable elements, the mixing step is performed by adding O [mol/kg] of oxygen combined with the valuable elements contained in the mixture to When the content of the reducing agent contained is R [mol/kg], the following formula (1) is established, and the concentration of SiO ₂ with respect to Al ₂ O ₃ contained in the mixture [wt%] ], and the ratio y of CaO concentration [wt%] to Al ₂ O ₃ satisfies the following formulas (2) to (5), and the reduction step is performed at a temperature of T [℃]. (However, T≧1400° C.) When the time for heating the mixture is t [min], the heating is performed so that the following formula (6) is satisfied.

O/R≦0.97...(1)
x≧0.118 ...(2)
y≧-0.12×x+0.0755 (if 0.118≦x≦0.375)...(3)
y≧0.031 (when x>0.375) ... (4)
y≦-x+0.6...(5)
T+5×t≧1490...(6)
However, x = SiO ₂ concentration in the mixture [wt%] ÷ Al ₂ O ₃ concentration in the mixture [wt%]
y = CaO concentration in the mixture [wt%] ÷ Al ₂ O ₃ concentration in the mixture [wt%]
Preferably, the reducing agent is at least one of a carbonaceous reducing agent, metal Al, and metal Si.

Preferably, the reducing agent used is one in which the cumulative volume of particle sizes of 75 μm or less is adjusted to 65% or more.

According to the method for recovering valuable elements of the present invention, valuable elements such as oxides of Co, Ni, and even Li can be recovered at low cost and in high yield from recovered materials containing Al ₂ O ₃ .

FIG. 2 is a diagram showing how the recovery results of valuable elements vary when the O/R value and the heating temperature of the mixture are different. FIG. 7 is a diagram showing how the recovery results of valuable elements vary when the S/A value and the C/A value are different. FIG. 2 is a diagram showing the relationship between parameters obtained from heating temperature and heating time and yield.

EMBODIMENT OF THE INVENTION Hereinafter, embodiments of the method for recovering valuable elements according to the present invention will be described in detail based on the drawings.
As shown in FIG. 1, the method for recovering valuable elements of this embodiment utilizes a reduction reaction to recover valuable metals in the form of single metals or alloys from recovered materials of used secondary batteries. . Furthermore, the method for recovering valuable elements of this embodiment utilizes the above-described reduction reaction to recover oxides such as Li as valuable metal oxides. In other words, the recovery method of the present invention targets not only single metals and alloys, but also metal oxides, and collects valuable elements including metal oxides.

Specifically, the recovery method of this embodiment targets recovered materials containing valuable elements obtained by subjecting secondary batteries to, for example, heating, crushing, sieving, and magnetic separation. Then, by performing a mixing step of mixing the recovered material from the secondary battery, a reducing agent, and a flux, and a reduction step of heating and reducing the mixture, the metal and oxide are separated from the mixture, After cooling, metals are separated from oxides and recovered.

In addition, in the recovery method of this embodiment, when mixing the reducing agent with the recovered material, the amount of oxygen combined with the valuable element (valuable metal) in the mixture is O [mol/kg], and the amount of oxygen contained in the mixture is When the reducing agent content of the reducing agent is R [mol/kg], formula (1) should be satisfied, and the ratio of the concentration [wt%] of SiO ₂ to Al ₂ O ₃ contained in the mixture should be Valuable elements are recovered by mixing a reducing agent with the recovered material so that the ratio y of the concentration [wt%] of CaO to Al ₂ O ₃ satisfies the following formulas (2) to (5). When heating the recovered material mixed with a reducing agent, if the heating temperature for heating the mixture is T [°C] and the time for heating the mixture is t [min], the following formula (6) holds true. It is characterized by heating the collected material so as to

Next, the recovered material and reducing agent used in the recovery method of this embodiment, as well as the contents of each process performed using these, will be explained in detail.
The recovered material that is the subject of the above-mentioned recovery method is obtained by, for example, heating, crushing, sieving, etc. a secondary battery containing valuable elements such as nickel and cobalt, and even Li oxide. be. That is, lithium cobalt oxide, lithium nickel oxide, etc. are sometimes used as positive electrode materials in secondary batteries, and these materials contain valuable elements such as Li, Mn, Co, and Ni. In addition, since some secondary batteries use metals such as copper, the secondary batteries are heated, crushed, sieved, etc. as appropriate to remove valuable materials such as Li, Mn, Co, and Ni. Create a recovered material in which the elements can be easily recovered.

To give a specific example, the collected material is first heated to burn the combustible material such as synthetic resin contained in the secondary battery as a separator or the like. In this way, unnecessary synthetic resins and the like are burned away and metals such as Li, Mn, Co, Ni, Fe, and Cu remain in the oxide or metal state, making it easier to recover valuable elements.
Note that oxides or metals such as Li, Mn, Co, Ni, Fe, and Cu may be in large chunks, so crush or sort them as appropriate to reduce the particle size so that they can easily react with the reducing agent described below. It is preferable to adjust. In addition, in the case of metals that are magnetically attracted to a magnet, such as Co, Ni, and Fe, by performing appropriate magnetic separation, metals that are not magnetically attracted can be removed as metal oxides and dust that are not valuable metals. , it is also possible to improve the recovery efficiency of valuable elements.

The reducing agent is mixed into the recovered material for the purpose of removing oxygen bonded to valuable metals such as Co and Ni among the valuable elements in the oxide by being oxidized. The reducing agent is formed into small-diameter particles (powder), and is homogeneously mixed with the recovered material, which is also formed into small-diameter particles (powder), and then heated to a desired temperature. This causes a reduction reaction to occur. When the reduction reaction occurs, the oxide of the valuable metal contained in the recovered material reacts with the reducing agent, and the oxide of the valuable metal is reduced to a single metal or an alloy.

Various reducing agents can be used as the reducing agent of the present invention, and for example, carbon-based reducing agents such as coal such as bituminous coal and lignite, charcoal, and bamboo charcoal can be suitably used. Since the reaction products of carbon-based reducing agents are carbon dioxide and carbon monoxide, the reaction products can be easily removed from the recovered material, making it easy to recover valuable elements as single metals or alloys. This is to become.

When carbon is used as the above-mentioned reducing agent, there is a suitable range for the mixing ratio of the reducing agent to the recovered material. In other words, if the amount of oxygen combined with valuable elements in the mixture is O [mol/kg] and the reducing agent content is R [mol/kg], then the following equation (1) is satisfied. preferable.
In other words, the relationship in equation (1) defines the following relationship for the ratio (O/R) obtained by dividing the oxygen amount O [mol/kg] by the reducing agent content R [mol/kg]. It has become.

0＜O/R≦0.97...(1)
If the above ratio (O/R) is too high, the amount of reducing agent combined with the valuable metal to be reduced is small, resulting in insufficient reduction and the oxygen combined with the valuable metal cannot be sufficiently reduced. It disappears. Therefore, all valuable metals such as nickel and cobalt cannot be metallized, and the recovery efficiency of valuable elements (valuable metals) decreases.

In addition, if the ratio (O/R) is too low, valuable metals such as nickel and cobalt will be sufficiently metallized, but the reducing agent will remain in excess of the amount of oxygen, so the reducing agent will remain after the reaction. Put it away. Since the remaining reducing agent prevents the agglomeration of the metal to be recovered, the particles of the valuable metal after reduction become fine, which significantly reduces the efficiency of magnetic separation, which will be described later, and prevents the recovery of valuable elements (valuable metals). This will reduce efficiency (recovery yield).

Therefore, the ratio (O/R) mentioned above is preferably 0<O/R≦0.97, preferably 0.46≦O/R≦0.97, more preferably 0.53≦O/R≦0.97. It's good.
In the method for recovering valuable elements of the present invention, the above-mentioned reducing agent is mixed with the recovered material, the mixture is heated and reduced, and the reduced mixture is brought into a molten state. By performing such melting, valuable metals among valuable elements can be easily separated from oxides in the form of single metals or alloys. In order to bring the above-mentioned reduced mixture into a molten state, the composition of the recovered material shown below is important.

Specifically, the above-mentioned recovered material contains oxides such as Al ₂ O ₃ , SiO ₂ , CaO, etc. Among these, the presence of Al ₂ O ₃ makes it difficult to bring the mixture into a molten state. It becomes difficult.
Therefore, in the method for recovering valuable elements of the present invention, the ratio x of the concentration [wt%] of SiO ₂ to Al ₂ O ₃ in the mixture and the ratio y of the concentration [wt%] of CaO to Al ₂ O ₃ in the mixture are as follows. The composition of the recovered material or mixture is adjusted so as to satisfy formulas (2) to (5).

x≧0.118 ...(2)
y≧-0.12×x+0.0755 (if 0.118≦x≦0.375)...(3)
y≧0.031 (when x>0.375) ... (4)
y≦-x+0.6...(5)
However, x = SiO ₂ concentration in the mixture [wt%] ÷ Al ₂ O ₃ concentration in the mixture [wt%]
y = CaO concentration in the mixture [wt%] ÷ Al ₂ O ₃ concentration in the mixture [wt%]
Equations (2) to (5) above express how much Al ₂ O ₃ that suppresses melting is contained in the recovered material composed of SiO ₂ and CaO, etc., based on the amount of SiO ₂ - Al in the mixture. It is expressed as the concentration ratio x,y between ₂ O ₃ and CaO- Al ₂ O ₃ , and is derived from experiments. Note that the basis of equations (2) to (5) will be explained later using experimental examples.

Even if the above formulas (2) to (5) do not hold true, if the recovered material has a different composition such as Al ₂ O ₃ , SiO ₂ , CaO, etc., the recovered material should be treated as a material with a different composition. It is possible to satisfy formulas (2) to (5) by switching to the formula or by partially mixing and using materials having different compositions.
In addition, if it is not possible to prepare recovered materials with different compositions such as Al ₂ O ₃ , SiO ₂ , CaO, etc., oxides such as Al ₂ O ₃ , SiO ₂ , CaO, or fluxes containing these may be used as needed. It is also possible to satisfy formulas (2) to (5) by adding appropriate amounts of the following to the recovered material.

According to the method for recovering valuable elements of the present embodiment described above, valuable metals (valuable elements) such as Co and Ni can be recovered at low cost and efficiently from recovered materials containing Al ₂ O ₃ .
When a reducing agent is mixed with the above-mentioned recovered material so that the relationship of formula (1) is satisfied, and the composition of the mixture is adjusted so that the relationships of formulas (2) to (5) are satisfied, the mixture can be heated. It becomes possible to make it into a molten state. However, even if the mixture can be brought into a molten state, whether or not the recovery rate, or yield, will be good when it is collected by magnetic separation after cooling is another matter.

This is because, when magnetic separation is used to reliably separate magnetic substances and non-magnetized substances, the particle size of the magnetic substances and non-magnetized substances becomes important. For example, if a mixture is reduced in a state where the amount of reducing agent such as graphite is too large for the amount of oxygen in an oxide such as cobalt (O/R is very small), cobalt etc. will be reduced and metalized. However, since the amount of reducing agent is originally in excess of the amount of oxygen, reducing agent that is not used in the reaction remains in the recovered material. If a reducing agent such as graphite is present in the recovered material, the aggregation of metals will be inhibited, so the remaining reducing agent will inhibit the aggregation of metals. As a result, in cases where a short period of time has passed since the melting, the recovered material contains extremely fine metals with particle sizes of several tens of micrometers or less.

However, metals with a particle size of several tens of μm or less, more precisely 1 mm or less, are difficult to separate during magnetic separation, and cannot be recovered with good magnetic separation efficiency, making metal recovery difficult. rate will drop significantly.
Therefore, in the method for recovering valuable elements of the present invention, the aggregation of the metal is further advanced, and the metal is recovered after the metal has grown to a particle size exceeding 1 mm. Specifically, the higher the heating temperature and the longer the heating time, the more the metal aggregation progresses. Therefore, in the present invention, when heating temperature is T [°C] and heating time is t [min], valuable metals (valued elements) are heated so that the relationship of formula (6) is established. It is possible to recover it with a high yield.

Further, by satisfying the relationships of formulas (1) to (6) described above, valuable metals among valuable elements can be efficiently recovered as simple metals or alloys. On the other hand, the mixture after removing valuable metals such as Co and Ni contains a high concentration of valuable oxides such as Li. Therefore, valuable elements such as Li oxide can also be recovered by using the reduced mixture as it is or by subjecting it to appropriate chemical treatment.

Next, the effects of the method for recovering valuable elements of the present invention will be explained in detail using Examples and Comparative Examples.
In Examples and Comparative Examples, waste lithium-ion batteries (LIB) are incinerated, crushed, and sieved, and the material separated under the sieve is used as recovered material to recover valuable elements, and the recovery rate is This is the result of the calculation. More specifically, Examples and Comparative Examples were conducted according to Experiments 1 to 3 below.
"Experiment 1"
In the example and comparative example of Experiment 1, powdered coal was used as the reducing agent mixed with the recovered material. The powdered coal used is bituminous coal that has been pulverized in a ball mill to have a particle size of 75 μm or less as determined by laser diffraction/scattering, but whose integrated volume is adjusted to 65% or more. For this mixture, a graphite crucible (inner diameter 40 mmφ) was heated with high frequency, and the mixture (agglomerate) was heated by radiation heating from the crucible. Further, an R thermocouple was installed inside the crucible, and the temperature inside the crucible was monitored with the R thermocouple. Note that the inside of the crucible was maintained in an inert atmosphere filled with an inert gas such as Ar or N ₂ gas, and care was taken not to blow atmospheric gas directly onto the mixture in the crucible.

In addition, the mixture shall be heated to one of the predetermined heating temperatures (1300°C, 1350°C, 1375°C, 1400°C), and the temperature will be raised at a rate of about 100°C/min to reach the specified heating temperature. After reaching the temperature, the inside of the crucible was kept in a heated state for 6 minutes at the predetermined heating temperature.
For the above-mentioned Examples and Comparative Examples, the recovery yield (recovery rate) was calculated for valuable metals of 1 mm or more obtained from the heated mixture. Specifically, this recovery rate is calculated by dividing the ``total weight of recovered valuable metals'' by ``the total weight of Co, Ni, Mn, Cu, and Fe contained in the mixture from the beginning.'' It is a ratio, and the calculated ratio is expressed as a percentage.

In other words, in order to calculate the recovery rate mentioned above, it is first necessary to determine the "total weight of recovered valuable metals."
That is, the reaction product obtained from the heated mixture is pulverized and then subjected to magnetic separation. The reaction products sorted to the magnetically attracted side in this magnetic separation are sieved with an opening of 1 mm, and the weight of the reaction products remaining on the sieve is weighed to determine the total amount of valuable metals recovered. You can find the weight. In this example, the collection was performed by magnetic separation, but the collection method is not limited to magnetic separation, and other general collection techniques can be employed.

On the other hand, when determining the "total weight of Co, Ni, Mn, Cu, and Fe contained in the mixture from the beginning," in principle, all raw materials of the mixture are analyzed before heating. That is, when the mixture is composed of a recovered material and a reducing agent, each of the recovered material and the reducing agent is analyzed by ICP (inductively coupled plasma emission spectrometry). In addition, if the mixture contains flux in addition to the recovered material and reducing agent, or if multiple types of recovered materials are used in combination, ICP analysis is also performed on the flux, or ICP analysis is performed on all recovered materials. to do things.

In this way, ICP analysis was performed to quantitatively analyze Co, Ni, Mn, Cu, and Fe contained in the raw materials of the mixture. and find the concentration (weight) of Fe. The weight of Co, Ni, Mn, Cu, and Fe originally contained in the mixture determined in this way is divided by the weight of the mixture weighed with an electronic balance. Calculate the weight concentration (weight ratio) of Mn, Cu, and Fe.

Finally, the calculated weight concentration of Co, Ni, Mn, Cu, and Fe in the mixture is multiplied by the weight of the mixture put into the crucible, and the amount of Co, Ni, Mn, Cu contained in the mixture in the crucible is determined by The weights of Fe and Fe were calculated, and the sum of the calculated weights was determined as the "total weight of valuable metals recovered."
After dividing the above-mentioned "total weight of valuable metals recovered" by the "total weight of Co, Ni, Mn, Cu, and Fe originally contained in the mixture" obtained in this way, The percentage is the recovery rate (yield).

In addition, for experiments 1 and 2 below, a case where the recovery rate (yield) is greater than 0% is considered a pass, and conditions where 0%<yield<80% are indicated with a "△", and conditions where the yield is ≥80%. is indicated by "○". In addition, conditions in which no metal of 1 mm or more was obtained were judged as failures and marked with an "x". In addition, for Experiment 3 below, a case where the recovery rate (yield) is less than 80% is considered a failure, a condition where 0%<yield<80% is indicated with an "×", and a condition where yield is ≥80% is indicated as a failure. It was indicated with "○" as passing the test.

The experimental results for Experiment 1 are shown in Table 1.

Looking at the "O/R" column in Table 1 mentioned above, the amount of oxygen combined with valuable metals in the mixture is O [mol/kg], and the reducing agent content of the reducing agent contained in the mixture is R. [mol/kg], if the O/R value is 0.14 to 0.97, the recovery rate will be evaluated as “○” or “△”, and if the O/R value is greater than 1.03, the recovery rate will be evaluated. It can be seen that is "x".
Also, looking at the "Temperature" column in Table 1, when the heating temperature is 1400°C, the recovery rate will be evaluated as "○" or "△", and when the heating temperature is 1300°C, 1350°C, or 1375°C, the recovery rate will be evaluated as "○" or "△". It can be seen that the evaluation of the recovery rate is "x".

In addition, the results of "O/R" and "temperature" in Table 1 are plotted as "○" and "△" on the graph by taking the "O/R" value on the horizontal axis and the "temperature" value on the vertical axis. ”, and “×” can be plotted as shown in FIG. 1.
In other words, as shown in Figure 1, the evaluation of recovery rate is "○" or "△" when the heating temperature is 1400℃ or higher and the "O/R" value is 0.14 to 0.97. I understand that it is limited to.

From the results shown in Table 1 and Figure 1, it is determined that it is possible to recover valuable metals with a good yield by setting the above-mentioned O/R to 0.14 to 0.97, more preferably 0.56 to 0.97. Ru.
"Experiment 2"
Experiment 2 was conducted using the ratio x (=S/A) obtained by dividing the SiO ₂ concentration [wt%] in the mixture by the Al ₂ O ₃ concentration [wt%] in the mixture, and the CaO concentration [wt%] in the mixture. ] divided by the Al ₂ O ₃ concentration [wt%] in the mixture, y (=C/A), on the yield was investigated.

The experimental results for Experiment 2 are shown in Table 2.

Examples are compositions in which the concentration of Al ₂ O ₃ in the mixture is 16.0wt% to 17.3wt%, the concentration of SiO ₂ is 2.0wt% to 6.3wt%, and the concentration of CaO is 0.5wt% to 2.6wt%. It is about. When the concentration in this example is expressed using the ratio _x and the ratio _y mentioned above, the ratio _x (=S /A) becomes 0.118 to 0.390, and the ratio y (=C/A) obtained by dividing the CaO concentration [wt%] in the mixture by the Al ₂ O ₃ concentration [wt%] in the mixture becomes 0.031 to 0.163. result.

In addition, in the comparative example, the concentration of Al ₂ O ₃ in the mixture was 16.7wt% to 17.7wt%, the concentration of SiO ₂ was 0.6wt% to 3.4wt%, and the concentration of CaO was 0.5wt% to 3.7wt%. This is about the composition. When the concentration of this comparative example is expressed using the ratio x and the ratio y as in the example, the ratio x (=S/A) is 0.036 to 0.201, and the ratio y (=C/A) is 0.031 to 0.201. The result is 0.155.
Furthermore, in order to make it easier to understand the relationship between "S/A" and "C/A" in Table 2 and the recovery rate, as in Table 1, the value of "S/A" is plotted on the horizontal axis, and the "C/A" value is plotted on the vertical axis. /A'' and plot the results of ``○'', ``△'', and ``x'' on the graph, the result will be as shown in Figure 2.

As shown in FIG. 2, the areas where the recovery rate is evaluated as ◯ or △ are shaded in gray in the figure. This shaded area is composed of four boundary lines (I) to (IV). When these four boundary lines are expressed numerically, the following relationships (2) to (5) can be obtained.
x≧0.118 ...(2)
y≧-0.12×x+0.0755 (if 0.118≦x≦0.375)...(3)
y≧0.031 (when x>0.375) ... (4)
y≦-x+0.6...(5)
From the above, if x (=S/A) and y (=C/A) satisfy the relationships of formulas (2) to (5), the recovery rate will be evaluated as "○" or The result is "△", and it becomes possible to recover valuable metals such as Co and Ni from recovered materials containing Al ₂ O ₃ at low cost and efficiently.

The reason why S/A (SiO ₂ /Al ₂ O ₃ ) and C/A (CaO/Al ₂ O ₃ ) are defined as described above is as follows. In other words, in addition to Co and Ni, which become metals when reduced, used secondary batteries contain Al ₂ O ₃ , _MnO has a complex composition. Here, in order to obtain valuable metals such as Co and Ni to be recovered from the recovered material, it is necessary to bring both the metal and the oxide into a molten state.

Therefore, in the method for recovering valuable elements of the present invention, by controlling S/A and C/A within the above-mentioned ranges, slag meltability is ensured, and valuable metals can be recovered at low cost and efficiently.
In other words, the relationships expressed by equations (2) to (4) are set so that metal/slag can be separated well. Also, if too much flux is added, productivity will decrease and cost will be reduced, so in order to maintain productivity and economic efficiency, (C+S)/A≦0.6 as shown in equation (5). We have set an upper limit on the amount added.
"Experiment 3"
When the above-mentioned heating temperature and formulas (1) to (5) are satisfied, valuable metals such as Co and Ni can be separated as metals and oxides. However, the method for recovering valuable elements of the present invention is aimed at recovering valuable metals in the form of metal lumps. In other words, even if the particle size is too small to be a metal lump, for example, if a valuable metal is obtained that is so fine as to fall under a sieve with a 1mm opening, the valuable metal can be recovered as a metal lump. It doesn't matter. Such fine metal particles are difficult to recover even by magnetic separation, and cannot be recovered with good magnetic separation efficiency, resulting in a significant reduction in metal recovery rate.

Therefore, in the method for recovering valuable elements of the present invention, fine metal particles are further agglomerated and grown to particles with a particle size exceeding 1 mm, and then recovered as metal. This is because good magnetic separation efficiency can be maintained if the particles are collected as particles with a particle size exceeding 1 mm. Note that the higher the heating temperature and the longer the heating time, the more the metal can be aggregated.

Specifically, in the present invention, when the heating temperature is T [°C] and the heating time is t [min], valuable elements are heated so that the relationship of formula (6) holds. It is assumed that the yield is recoverable. This relational expression (6) has been derived empirically, and the applicant has confirmed that it satisfies actual data.
T+5×t≧1490...(6)
The relationship in equation (6) described above (the relationship between heating temperature T [° C.] and heating time t [min]) is derived from the results of Experiment 3.

That is, as shown in Table 3, for the seven samples of experiments No. 1 to No. 7, the heating temperature T [°C] was varied in the range of 1373 °C to 1548 °C, and the heating time t [min] was 1.2 The yield is measured when valuable metals are recovered from the recovered material by varying the time from min to 23.0 min.

For the samples of experiments No. 1 to No. 7 mentioned above, when calculating the parameters corresponding to the left side of equation (6) (temperature and time parameters), that is, the parameter "T + 5 × t", it is found that it is a comparative example Experiments No. 1 to No. 4 are 1395.9 to 1488.3, and Experiments No. 5 to No. 7, which are examples, are 1491.5 to 1574.1. All comparative examples with parameters of 1395.9 to 1488.3 were evaluated as "x", and all examples with parameters of 1491.5 to 1574.1 were evaluated as "○".

Also, in order to make it easier to understand the relationship between "temperature/time parameters" and "yield" in Table 3, as in Tables 1 and 2, the horizontal axis is the value of "temperature/time parameter" and the vertical axis is " If the values of "Yield" are taken and the results of "○" and "x" are plotted on a graph, the results as shown in FIG. 3 are obtained.
As shown in FIG. 3, the "yield" shows a linear change (linear change) with respect to the "temperature/time parameters". Here, experiment No. 4 with a parameter of 1488.3 has a yield of 79.7%, whereas experiment No. 5 with a parameter of 1491.5 has a yield of 85.5%. From this, it is considered that by setting the parameter to 1490 or more, preferably 1520 or more, it is possible to obtain a "yield" of 80% or more, preferably 90% or more.

Furthermore, in the examples (Experiments No. 5 to No. 7) with excellent recovery rates of valuable metals, the mixture after removing valuable metals such as Co and Ni contained high concentrations of valuable oxides such as Li. I'm here. Therefore, the applicant has confirmed that valuable elements such as Li oxide can be efficiently recovered by using the reduced mixture as it is or by subjecting it to appropriate chemical treatment.
It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. In particular, in the embodiments disclosed herein, matters that are not explicitly disclosed, such as operating conditions, operating conditions, various parameters, dimensions, weights, and volumes of components, are beyond the scope of those skilled in the art. Rather, values that can be easily assumed by a person skilled in the art are used.

Claims (3)

A mixing process in which the recovered material from the secondary battery, a reducing agent, and a flux are mixed together, a reduction process in which the mixture is heated and reduced, and a sorting process in which the reduced mixture is cooled and metals are separated from oxides. In the method for recovering valuable elements having
In the mixing step, if the amount of oxygen combined with the valuable element contained in the mixture is O [mol/kg] and the content of the reducing agent contained in the mixture is R [mol/kg], the following So that equation (1) holds true,
and,
The ratio x of the concentration [wt%] of SiO ₂ to Al ₂ O ₃ contained in the mixture and the ratio y of the concentration [wt%] of CaO to Al ₂ O ₃ are determined by the following equations (2) to (5). ),
The reduction step is performed so that the following formula (6) holds true, where the temperature is T [°C] (T≧1400°C) and the time for heating the mixture is t [min]. A method for recovering valuable elements.
O/R≦0.97...(1)
x≧0.118 ...(2)
y≧-0.12×x+0.0755 (if 0.118≦x≦0.375)...(3)
y≧0.031 (when x>0.375) ... (4)
y≦-x+0.6...(5)
T+5×t≧1490...(6)
However, x = SiO ₂ concentration in the mixture [wt%] ÷ Al ₂ O ₃ concentration in the mixture [wt%]
y = CaO concentration in the mixture [wt%] ÷ Al ₂ O ₃ concentration in the mixture [wt%] The method for recovering valuable elements according to claim 1, wherein at least one of a carbonaceous reducing agent, metal Al, or metal Si is used as the reducing agent. The method for recovering valuable elements according to claim 1 or 2, characterized in that the reducing agent is one in which the cumulative volume of particle sizes of 75 μm or less is adjusted to 65% or more.