WO2020203937A1

WO2020203937A1 - Method for recovering valuable metals

Info

Publication number: WO2020203937A1
Application number: PCT/JP2020/014401
Authority: WO
Inventors: 昌麟王; 健太郎浦田; 卓對馬
Original assignee: 株式会社神戸製鋼所
Priority date: 2019-04-03
Filing date: 2020-03-27
Publication date: 2020-10-08
Also published as: CN113302005A; CN113302005B

Abstract

The purpose of the present invention is to inexpensively and efficiently recover valuable metals such as Co or Ni from a recovery product containing Al₂O₃, CoO_X, or NiO_X.　In a method for recovering valuable metals according to the present invention, used secondary batteries are subjected to heating, pulverizing, sieving, and magnetic separation to obtain a recovery product containing valuable metals, and a mixture of the obtained recovery product and a reducing agent is heated to reduce valuable metals in the mixture into a molten metal state, thereby separating the mixture into metals and oxides. When separating and recovering the metals from the oxides after cooling, the heating temperature of the mixture is set to 1400°C or higher. When the reducing agent is mixed with the recovery product, the reducing agent is mixed with the recovery product such that 0<O/R≤0.97 is satisfied (where, O [mol/kg] is the amount of oxygen chemically bonded with valuable metals in the mixture, and R [mol/kg] is the amount of the reducing agent contained in the mixture), and such that x and y, which are the ratios of the concentrations [wt%] of Al₂O₃, SiO₂, and CaO contained in the mixture, satisfy the desired relationship.

Description

How to recover valuable metals

The present invention relates to a technique for recovering a valuable metal such as Co or Ni from an oxide containing Al ₂ O ₃ or CoO _X or NiO _X.

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

Here, rare metals (valuable metals) such as Co and Ni are used for secondary batteries such as LIB and Ni-MH. For example, cobalt and nickel, which are indispensable for the production of LIB (lithium-ion rechargeable battery), have problems such as ubiquitous resources worldwide, and the risk of resource depletion has been pointed out. In addition, with regard to cobalt, unfair labor conditions at mines have been reported, and mining alone may not be sufficient to meet the demand.

From these points of view, the recycling technology of rare metals such as cobalt and nickel is drawing attention. However, at present, wet solvent extraction is the main focus, and mass processing technology has not yet been established due to cost issues. Therefore, there is a demand for a technique for recovering valuable metals inexpensively and efficiently from LIBs that use cobalt or nickel. The high-temperature refining technology used in the iron-making process (hereinafter referred to as "pyrometallurgy") can be processed at a relatively low cost, and in order to meet the challenges of social recycling, and in various industries such as automobiles and electrical equipment. It is considered that there is an urgent need to establish technology in terms of its availability in the field.

For example, Patent Document 1 describes a method for recovering valuable metals from metal oxides containing alkali metals, which efficiently recovers valuable metals from metal oxides containing alkali metals generated in the process of manufacturing a secondary battery. There is. In the method for recovering valuable metals in Patent Document 1 described above, a reducing agent and a slag-forming agent are added to a metal oxide containing an alkali metal generated in the manufacturing process of a secondary battery, and the valuable metal is reduced and settled. Is to be collected.

Further, Patent Document 2 describes a method for easily recovering valuable metals from a used lithium secondary battery in good yield. The method for recovering valuable metals in 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 crushed product, and a step of sieving the crushed product. The step of obtaining a primary valuable metal concentrate under a sieve, and the process of mixing the primary valuable metal concentrate with a calcium compound and then melting the metal to remove the slag produced thereby to make the metal a secondary valuable metal. It consists of a process of collecting as a concentrate.

Further, Patent Document 3 describes a method capable of improving the recovery rate of valuable metals such as cobalt and reducing the recovery cost when a waste battery such as a lithium ion battery is dry-treated. The method for recovering the valuable metal of Patent Document 3 described above is a pre-oxidation step ST20 in which a waste battery containing aluminum and iron is roasted to perform a pre-oxidation treatment, and a melted product obtained by melting the waste battery after the pre-oxidation step ST20. The first slag separation step ST22 for separating and recovering the first slag containing aluminum oxide from the melt, and the first alloy which is the melt after the first slag separation step. Iron is passed through a second slag separation step ST23, which performs an oxidation treatment, and a second slag separation step ST24, which separates and recovers a second slag containing iron from the first alloy after the second oxidation step ST23. In the method of obtaining a second alloy having excellent separation performance between and cobalt and a low iron content, the second slag is reused as a flux added to promote the second and subsequent melting steps ST21b. ing.

Further, Patent Document 4 describes a recycling method for recovering a metal from a lithium ion battery. The recycling method of Patent Document 4 described above is a method of recovering cobalt from a lithium ion battery containing aluminum and carbon, and includes a step of preparing a bath furnace provided with a means for injecting O ₂ and a slag forming agent. A step of preparing a metallurgical charge material containing CaO and a lithium ion battery as a metal, and supplying oxygen and the metallurgical charge material to the furnace, whereby at least a part of the cobalt is reduced, and a metal. The method includes a step of collecting the slag in the phase and a step of separating the slag from the metal phase by boiling water, and the method is expressed in terms of mass% of the metallurgical charge raw material: 153 mass% -3.5 ( Al% + 0.6C%) Self-generated conditions by supplying a fraction of a lithium-ion battery equal to or greater than [Al% and C% represent the mass% of aluminum and carbon in the battery]. It is characterized by being operated with.

Further, Patent Document 5 describes a separation step 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 valuable metal from the positive electrode material or the separated negative electrode material separated by the separation step. A valuable metal recovery system for recovering valuable metals from a waste secondary battery is described, including a step of recovering the precious metals. The valuable metal recovery system of Patent Document 5 described above includes a separation step of physically separating a waste secondary battery and separating it into a separated negative electrode material and a separated positive electrode material, and a positive electrode material or separation separated by the separation step. It includes a step of recovering valuable metal from the negative electrode material.

Further, Patent Document 6 describes a method for reducing the sulfur content generated in the step of recovering the valuable metal contained in the waste battery. The method of Patent Document 6 described above is a method of recovering the valuable metal from a waste battery or process waste containing at least one valuable metal of cobalt or nickel, and (1) pre-roasting treatment, crushing treatment and sieving. A primary concentration step of obtaining a primary concentrate of the valuable metal through a division treatment, (2) a secondary concentration step of dissolving the primary concentrate with sulfuric acid and obtaining the solution as a secondary concentrate. (3) A tertiary concentration step of adding an aqueous solution of an alkali metal to the secondary concentrate and performing a hydroxylation treatment, followed by an oxidation roasting treatment and a water washing treatment to reduce sulfurization to obtain a tertiary concentrate of the valuable metal. And (4) a quaternary concentration step of melting the tertiary concentrate and recovering the valuable metal.

Japanese Unexamined Patent Publication No. 2000-226619 Japanese Patent Application Laid-Open No. 10-158751 Japanese Unexamined Patent Publication No. 2012-224877 Special Table 2013-5006048 International Publication No. 2000-025382 Japanese Unexamined Patent Publication No. 2016-037661

The technique of Patent Document 1 described above is a technique of recovering a valuable metal as an alloy from a raw material of an oxide containing Li, Mn, Co, Ni, and Fe generated in the manufacturing process of a secondary battery. The raw material does not contain Al in the first place, and cannot be applied when the alloy is recovered from an oxide containing Al. That is, when Al (Al ₂ O ₃ ) is contained in the raw material, the raw material has a high melting point, so that it cannot be melted and it may be difficult to recover the valuable metal as an alloy. ..

Further, in the technique of Patent Document 2, the amount of CaO / Al ₂ O ₃ is described, but since the amount of CaO added is large and the amount of CaO relative to Al ₂ O ₃ is large, the productivity is low and the cost is reduced. Possibly, does not include alloy recovery in the case of high Al ₂ O ₃ content. In addition, there is no description of an appropriate reducing agent ratio.

Further, the technique of Patent Document 3 does not describe the reducing agent ratio required to obtain granular metallic iron.

Further, in the technique of Patent Document 4, as in the case of Patent Document 2, an appropriate reducing agent ratio is not written, and the amount of SiO ₂ and CaO added is large, and SiO ₂ / Al ₂ O ₃ and CaO / The value of Al ₂ O ₃ is high. Therefore, the productivity is low and the cost may be reduced, and the alloy recovery when a large amount of Al ₂ O ₃ is contained is not included.

Further, the technique of Patent Document 5 does not contain Al ₂ O _{3 in} the raw material, and cannot be applied when the alloy is recovered from the oxide containing Al.

Further, the technique of Patent Document 6 is a method of reducing the residue obtained by removing Cu and C from under the sieve after incineration, crushing and sieving with C (coke) or Al, but 100% coke is used as a reducing agent. When used, C / A (CaO / Al ₂ O ₃ ) and S / A (SiO ₂ / Al ₂ O ₃ ) had values of about 2.7, and the amount of flux was too large, and Al was used as the reducing agent. Even in this case, C + A (SiO ₂ + CaO) = 1.72, and the flux amount is too large in this case as well. Therefore, even with the technique of Patent Document 6, the productivity is low and the cost may be reduced.

That is, the techniques of Patent Documents 1 to 6 described above are for recovering valuable metals by reducing the recovered material of the secondary battery while melting it, and adding flux to melt the recovered product. It has become. However, when the recovered product is slag containing Al ₂ O ₃ , even when flux is added for melting, if the amount of flux added is too large, Co and Ni to be recovered in the mixture The amount is reduced and the productivity is directly deteriorated. Therefore, although it is possible to recover the alloys of Co and Ni, there is a concern that the productivity will be deteriorated, the cost will be reduced, and the advantage of relatively low cost, which is a characteristic of pyrometallurgy, will be erased.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for recovering valuable metals such as Co and Ni from a recovered product containing Al ₂ O ₃ at low cost and efficiently. And.

In order to solve the above problems, the method for recovering valuable metals of the present invention takes the following technical measures.
That is, in the method for recovering valuable metals of the present invention, a recovered product containing valuable metals is obtained by subjecting a used secondary battery to treatments of heating, crushing, sieving, and magnetic separation, and the obtained recovered product is obtained. By mixing the product with a reducing agent and heating it, the valuable metal in the mixture is metallized by reduction and melted to separate the metal and oxide from the mixture, and after cooling, the metal is sorted from the oxide. In the method for recovering the valuable metal to be recovered, the heating temperature of the mixture is set to 1400 ° C. or higher, and when the reducing agent is mixed with the recovered product, the amount of oxygen compounded with the valuable metal in the mixture is O [mol. / Kg], where the reducing agent content of the reducing agent contained in the mixture is R [mol / kg], 0 <O / R ≦ 0.97 is established, and the reducing agent is contained in the mixture. A reducing agent is mixed with the recovered material so that the ratios x and y of the concentrations [wt%] of Al ₂ O ₃ , SiO ₂ , and CaO satisfy the following formulas (1) to (4), and the valuable metal. It is characterized by collecting.

Further, another method for recovering the valuable metal of the present invention was obtained by subjecting a used secondary battery to a treatment of heating, crushing, sieving, and magnetic separation to obtain a recovered product containing the valuable metal. By mixing the recovered product with a reducing agent and heating it, the valuable metal in the mixture is metallized by reduction and melted to separate the metal and oxide from the mixture, and after cooling, the metal is separated from the oxide. In the method for recovering valuable metals to be sorted and recovered, when a reducing agent is mixed with the recovered product, the amount of oxygen compounded with the valuable metal in the mixed product is O [mol / kg], which is contained in the mixed product. When the reducing agent content of the reducing agent is R [mol / kg], 0 <O / R ≦ 0.97 is established, and the SiO ₂ of SiO ₂ with respect to Al ₂ O ₃ contained in the mixture is satisfied. A reducing agent is mixed with the recovered product so that the ratio x of the concentration [wt%] and the ratio y of the concentration [wt%] of CaO to Al ₂ O ₃ satisfy the following formulas (1) to (4). Further, when heating the recovered product mixed with the reducing agent, when the heating temperature for heating the mixture is T [° C.] and the time for heating the mixture is t [min], the following formula ( It is characterized in that the recovered product is heated so that 5) is established.

In any of the above recovery methods, it is preferable to use at least one kind of carbonaceous reducing agent, metal Al, or metal Si as the reducing agent.

Preferably, as the reducing agent, one having a particle size of 75 μm or less and having an integrated volume adjusted to 65% or more is used.

According to the method for recovering valuable metals of the present invention, valuable metals such as Co and Ni can be recovered inexpensively and efficiently from the recovered product containing Al ₂ O ₃ .

It is a figure which showed how the recovery result of a valuable metal fluctuates when the value of O / R and the heating temperature of a mixture are different from each other. It is a figure which showed how the recovery result of a valuable metal fluctuates when the value of S / A and the value of C / A are different from each other. It is a figure which showed the relationship between the parameter obtained from the heating temperature and the heating time, and the yield.

Hereinafter, embodiments of the method for recovering valuable metals according to the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the method for recovering valuable metals in the present embodiment is to recover valuable metals from the recovered material of a used secondary battery in the state of a single metal or an alloy by utilizing a reduction reaction. ..
Specifically, the recovery method of the present embodiment targets a recovery product containing a valuable metal obtained by subjecting a used secondary battery to a treatment of heating, crushing, sieving, and magnetic separation. Then, by mixing the recovered product to be recovered with a reducing agent and heating it, the valuable metal in the mixture is metallized by reduction and melted to separate the metal and the oxide from the mixture, and the metal after cooling. Is selected from oxides and recovered.

Further, in the recovery method of the present embodiment, when the reducing agent is mixed with the recovered product, the amount of oxygen compounded with the valuable metal in the mixture is O [mol / kg], and the reducing agent of the reducing agent contained in the mixture is used. When the content is R [mol / kg], 0 <O / R ≦ 0.97 is established, and the concentrations of Al ₂ O ₃ , SiO ₂ , and Ca O contained in the mixture [wt%]. A reducing agent is mixed with the recovered product so that the ratios x and y of the above satisfy the above formulas (1) to (4).
When (i) the heating temperature of the mixture is 1400 ° C. or higher, or (ii) the heating temperature for heating the mixture is T [° C.] and the time for heating the mixture is t [min], the above formula (5) ) Is established, and the valuable metal is recovered by heating the mixture.
In the case of (ii) above, the heating temperature T is preferably 1400 ° C. or higher.

Next, the recovered product and the reducing agent used in the recovery method of the present embodiment, and the contents of each step performed using these will be described in detail.
The recovered product, which is the target of the recovery method described above, is obtained by heating, crushing, sieving, or the like a used secondary battery containing a valuable metal such as nickel and cobalt. That is, in the secondary battery, lithium cobalt oxide, lithium nickel oxide, or the like may be used as the positive electrode material, and valuable metals such as Li, Mn, Co, and Ni are contained. Further, since a metal such as copper may be used for the secondary battery, the used secondary battery is appropriately heated, crushed, sieved, etc., and Li, Mn, Co, Ni, etc. To prepare a recovered product in which the valuable metal of the above is easily recovered.

Specifically, the recovered material is first heated to burn a combustible material such as a synthetic resin contained in a secondary battery as a separator or the like. In this way, excess synthetic resin and the like are burnt down, and metals such as Li, Mn, Co, Ni, Fe, and Cu remain in the state of oxides or metals, so that valuable metals can be easily recovered.
Since oxides or metals such as Li, Mn, Co, Ni, Fe, and Cu may be in large lumps, the particle size is appropriately crushed or sorted so as to easily react with the reducing agent described later. It also needs to be adjusted. Further, in the case of metals that are magnetized to magnets such as Co, Ni, and Fe, the non-magnetized metals can be removed as oxides and dust of metals that are not valuable metals by performing appropriate magnetic selection. It is also possible to improve the recovery efficiency of valuable metals.

The reducing agent is mixed with the recovered product for the purpose of removing oxygen bound to valuable metals in the oxide by oxidizing itself. The reducing agent is formed in the form of particles (powder) having a small diameter, and is uniformly mixed with the recovered product formed in the form of particles (powder) having a small diameter, and then heated to a desired temperature. As a result, a reduction reaction is caused. When the reduction reaction occurs, the oxide of the valuable metal contained in the recovered product reacts with the reducing agent, and the oxide of the valuable metal is reduced to a single metal or alloy.

Various reducing agents can be used as the reducing agent of the present invention, and for example, coal such as bituminous coal and carbon-based reducing agent (carbon material reducing agent) such as charcoal and bamboo charcoal can be preferably used. .. Since the reaction product of the reduction reaction of the carbon-based reducing agent is carbon dioxide or carbon monoxide, the reaction product can be easily removed from the recovered product, and the valuable metal can be easily recovered as a single metal or alloy. This is to become.

When carbon is used as the reducing agent described above, there is a suitable range in the mixing ratio of the reducing agent with respect to the recovered product. That is, when the amount of oxygen compounded with the valuable metal in the mixture is O [mol / kg] and the content of the reducing agent is R [mol / kg], the amount of oxygen O [mol / kg] is the content of the reducing agent. It is preferable that the ratio (O / R) divided by R [mol / kg] satisfies the relationship of 0 <O / R ≦ 0.97.

When the above-mentioned ratio (O / R) is too high, the amount of the reducing agent is small with respect to the amount of oxygen combined with the valuable metal to be reduced, so that the reduction is insufficient and the oxygen combined with the valuable metal can be sufficiently reduced. It disappears. Therefore, all the valuable metals such as nickel and cobalt cannot be metallized, and the recovery efficiency of the valuable metals is lowered.
If the ratio (O / R) is too low, valuable metals such as nickel and cobalt are sufficiently metallized, but the reducing agent is excessive with respect to the amount of oxygen, so that the reducing agent remains even after the reaction. It ends up. Since the reducing agent remaining in this way hinders the aggregation of the metal for recovery purposes, the particles of the valuable metal after reduction become fine particles, which significantly reduces the efficiency of magnetic separation described later, and the recovery efficiency of the valuable metal (recovery yield). ) Is reduced.

Therefore, the ratio (O / R) described above is preferably 0 <O / R ≦ 0.97, preferably 0.46 ≦ O / R ≦ 0.97, and more preferably 0.53 ≦. It is preferable that O / R ≦ 0.97.
In the method for recovering valuable metals of the present invention, it is necessary to mix the above-mentioned reducing agent with the recovered product and heat and reduce the mixture to bring the reduced mixture into a molten state. By performing such melting, it becomes easy to separate the elemental metal or the valuable metal of the alloy from the oxide.

In order to melt the above-mentioned mixture, it is preferable to first maintain the heating temperature at 1400 ° C. or higher. If the heating temperature is maintained at 1400 ° C. or higher, the elemental metal or the valuable metal of the alloy produced by the reduction reaction can be sufficiently melted, and the valuable metal melted after cooling can be agglomerated and separated from the oxide. It will be easy.
The composition of the recovered product is also important in order to bring the above-mentioned reduced mixture into a molten state.

Specifically, the above-mentioned recovered product contains oxides such as Al ₂ O ₃ , SiO ₂ , and CaO, and if Al ₂ O ₃ is present among them, the mixture may be melted. It will be difficult.
Therefore, in the method for recovering valuable metals of the present invention, the Al ₂ O ₃ concentration [wt%], the SiO ₂ concentration [wt%], and the Ca O concentration [wt%] in the mixture are the following formulas (1) to (4). ), The composition of the recovered product or mixture is adjusted.

In the above-mentioned formulas (1) to (4), the amount of Al ₂ O ₃ that suppresses melting is contained in the recovered product composed of SiO ₂ and CaO, and the amount of SiO _2- Al in the mixture is determined. ₂ O ₃ and between _CaO-Al 2 _{O 3} concentration ratio between the x, have the meanings indicated in y, those derived from experiments. The grounds for the formulas (1) to (4) will be described later using an experimental example.

Even if the above formulas (1) to (4) do not hold, if there are recovered products with different compositions such as Al ₂ O ₃ , SiO ₂ , and CaO, the recovered products have different compositions. By switching to, or by using a mixture of partially different compositions, the equations (1) to (4) can be satisfied.
Further, when the composition of such _{_{_{Al 2 O 3, SiO 2,}}} CaO as recovered material can not provide a different optionally comprises oxide such as _{_{_{Al 2 O 3, SiO 2,}}} CaO , or these fluxes By adding an appropriate amount of the above to the recovered product, the formulas (1) to (4) can be satisfied.

According to the method for recovering valuable metals of the present embodiment described above, valuable metals such as Co and Ni can be recovered inexpensively and efficiently from the recovered product containing Al ₂ O ₃ .
In this way, by setting the heating temperature to 1400 ° C. or higher and melting the mixture, recovery of valuable metals after cooling becomes cheaper and more efficient than before, but if there is a method for further increasing the recovery rate, that is, the yield. , More preferred.

This is because the grain size of the magnetic or non-magnetic material is important when the magnetic material and the non-magnetic material are surely separated by magnetic selection. For example, when the mixture is reduced in a state where the amount of the reducing agent such as graphite is too large (the state where the O / R is very small) with respect to the amount of oxygen in the oxide such as cobalt, the cobalt and the like are reduced and metallized. However, since the amount of the reducing agent is originally larger than the amount of oxygen, the reducing agent not used in the reaction remains in the recovered product. If graphite or the like, which is a reducing agent, is present in the recovered product, the aggregation of metals is inhibited, so that the residual reducing agent inhibits the aggregation of metals. As a result, when it has been melted for a short time, the recovered product is recovered in a state of containing extremely fine metal having a particle size of several tens of μm or less.

However, such a metal having a particle size of several tens of μm or less, to be exact, a particle size of 1 mm or less is difficult to separate at the time of magnetic separation and cannot be recovered with good magnetic selection efficiency, so that the metal can be recovered. The rate drops significantly.
Therefore, in the method for recovering valuable metals of the present invention, the agglomeration of the metal is further promoted, and the metal is recovered after growing into particles having a particle size of more than 1 mm. Specifically, the higher the heating temperature and the longer the heating time, the more the metal aggregates. Therefore, in the present invention, when the heating temperature is T [° C.] and the heating time is t [min], the valuable metal is further increased by heating so that the relationship of the above formula (5) is established. It was made possible to collect by yield.

Next, the effects of the method for recovering valuable metals of the present invention will be described in detail with reference to Examples and Comparative Examples.
In Examples and Comparative Examples, a waste battery of a lithium ion battery (LIB) is incinerated, crushed, and sieved, and the material separated under the sieve is used as a recovered product to recover valuable metals and a recovery rate. Is calculated. More specifically, Examples and Comparative Examples were carried out according to Experiments 1 to 3 below.

[Experiment 1]
In the examples and comparative examples of Experiment 1, powdered coal was used as the reducing agent to be mixed with the recovered product. As this powdered coal, bituminous coal is crushed by a ball mill to have a particle size of 75 μm or less by a laser diffraction / scattering method, but the integrated volume is adjusted to 65% or more. For this mixture, a graphite crucible (inner diameter 40 mmφ) was heated at a high frequency, and the mixture (agglomerate) was heated by radiant heating from the crucible. In addition, an R thermocouple was installed in the crucible, and the temperature inside the crucible was monitored by the R thermocouple. Incidentally, the crucible is held in an inert atmosphere filled with an inert gas or N ₂ gas, such as Ar, with consideration to not spray directly atmospheric gas into the mixture in the crucible.

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

That is, in order to calculate the above-mentioned recovery rate, it is first necessary to obtain the "total weight of the recovered valuable metals".
That is, the reaction product obtained from the heated mixture is pulverized and then subjected to magnetic separation. The reaction products selected on the magnetized side in this magnetic selection are sieved with a mesh size of 1 mm, and the weight of the reaction products remaining on the sieve is weighed to obtain the above-mentioned “total recovered valuable metals”. "Weight" can be calculated. In this embodiment, recovery was performed by magnetic separation, but the recovery method is not limited to magnetic selection, and other general recovery techniques can be adopted.

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

In this way, analysis was performed by ICP, quantitative analysis of Co, Ni, Mn, Cu, and Fe contained in the raw material of the mixture was performed, and Co, Ni, Mn, Cu, which were originally contained in the mixture. And Fe concentration (weight) is determined. The weights of Co, Ni, Mn, Cu, and Fe contained in the mixture thus obtained from the beginning are divided by the weight of the mixture weighed by the electronic balance, and the Co, Ni, in the mixture is divided. The weight concentration (weight ratio) of Mn, Cu, and Fe is calculated.

Finally, the calculated weight concentrations of Co, Ni, Mn, Cu, and Fe in the mixture are multiplied by the weight of the mixture charged into the pit, and the Co, Ni, Mn, Cu, contained in the mixture in the pit are multiplied. And Fe were calculated, and the sum of the calculated weights was calculated as the "total weight of recovered valuable metals".
The "total weight of Co, Ni, Mn, Cu, and Fe contained in the mixture from the beginning" obtained in this way minus the above-mentioned "total weight of the recovered valuable metal". The percentage is the recovery rate (yield).

Regarding Experiments 1 and 2 below, the condition that the recovery rate (yield) is larger than 0% is accepted, the condition that 0% <yield <80% is indicated by "Δ", and the condition that the yield is ≥80% Is indicated by "○". Further, the condition that no metal of 1 mm or more could be obtained was rejected and indicated by "x". In Experiment 3 below, if the recovery rate (yield) is less than 80%, it is rejected, and the condition that 0% <yield <80% is indicated by "x", and the condition that the yield ≥ 80% It is indicated by "○" as a pass.

Table 1 shows the experimental results related to Experiment 1.

Looking at the column of "O / R" in Table 1 described above, the amount of oxygen compounded with the valuable metal in the mixture is O [mol / kg], and the reducing agent content of the reducing agent contained in the mixture is R. When [mol / kg] is set and the O / R value is 0.14 to 0.97, the recovery rate is evaluated as “○” or “Δ”, and the O / R value is larger than 1.03. In that case, it can be seen that the evaluation of the recovery rate is “x”.
Looking at the "Temperature" column in Table 1, when the heating temperature is 1400 ° C, the evaluation of the recovery rate is "○" or "Δ", and when the heating temperature is 1300 ° C, 1350 ° C, or 1375 ° C. It can be seen that the evaluation of the recovery rate is "x".

The results of "O / R" and "Temperature" in Table 1 are shown on the graph as "○" and "△" with the "O / R" value on the horizontal axis and the "Temperature" value on the vertical axis. , And the results of "x" can be plotted as FIG.
That is, as shown in FIG. 1, the evaluation of the recovery rate is “◯” or “Δ” when the heating temperature is 1400 ° C. or higher and the value of “O / R” is 0.14 to 0. It can be understood that it is limited to the case of 97.

From the results of Table 1 and FIG. 1, by setting the above-mentioned O / R to 0.14 to 0.97, more preferably the O / R to 0.56 to 0.97, valuable metals can be recovered with a good yield. It is judged that it will be possible to do so.

[Experiment 2]
In Experiment 2, 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 were obtained. ] Was divided by the Al ₂ O ₃ concentration [wt%] in the mixture, and the effect of the ratio y (= C / A) on the yield was investigated.

Table 2 shows the experimental results related to Experiment 2.

In the examples, the concentration of Al ₂ O ₃ in the mixture is 16.0 wt% to 17.3 wt%, the concentration of SiO ₂ is 2.0 wt% to 6.3 wt%, and the concentration of Ca O is 0.5 wt% to 2 It is about the composition of .6 wt%. When the concentration of this example is shown using the above-mentioned ratio x and ratio y, the ratio x (= S) obtained by dividing the SiO ₂ concentration [wt%] in the mixture by the Al ₂ O ₃ concentration [wt%] in the mixture. / a) becomes 0.118 to 0.390, and the concentration of _Al 2 _{O 3} in the mixture of CaO concentration [wt%] in the mixture ratio divided by [wt%] y (= C / a) is 0 The result is .031 to 0.163.

Further, in the comparative example, the concentration of Al ₂ O ₃ in the mixture is 16.7 wt% to 17.7 wt%, the concentration of SiO ₂ is 0.6 wt% to 3.4 wt%, and the concentration of Ca O is 0.5 wt%. It is about a composition of about 3.7 wt%. When the concentration of this comparative example is shown using the ratio x and the ratio y as in the examples, the ratio x (= S / A) is 0.036 to 0.201, and the ratio y (= C / A). ) Is the result of 0.031 to 0.155.
Further, as in Table 1, in order to make it easier to understand the relationship between "S / A" and "C / A" in Table 2 and the recovery rate, the horizontal axis is the value of "S / A" and the vertical axis is "C". Taking the value of "/ A" and plotting the results of "○", "Δ", and "×" on the graph, the result is as shown in FIG.

As shown in FIG. 2, the evaluation of the recovery rate is ◯ or Δ in the gray shaded portion in the figure. This shaded portion is composed of four boundary lines (I) to (IV). When these four boundary lines are expressed by mathematical formulas, the following relationships (1) to (4) can be obtained.

From the above, if x (= S / A) and y (= C / A) satisfy the relationship between the formulas (1) to (4), the evaluation of the recovery rate is "○" or It becomes “Δ”, and valuable metals such as Co and Ni can be recovered inexpensively and efficiently from the recovered material containing Al ₂ O ₃ .

As described above, S / A (SiO ₂ / Al ₂ O ₃ ) and C / A (CaO / Al ₂ O ₃ ) are defined for the following reasons. That is, the used secondary batteries, Co to become a metal is reduced, in addition to Ni, _Al 2 _O 3 as a component to become slag as _oxide, MnO X, Li, are included F, etc., recovered material Has a complex composition. Here, in order to obtain valuable metals such as Co and Ni for recovery from the recovered material, it is necessary to put both the metal and the oxide in a molten state.

Therefore, in the method for recovering valuable resources of the present invention, by controlling S / A and C / A within the above range, slag meltability is ensured and the valuable metal can be recovered inexpensively and efficiently.
That is, the relationship between the equations (1) and (3) is set so that the metal / slag can be separated well. Further, if too much flux is added, the productivity is lowered and the cost is reduced. Therefore, in order to maintain the productivity and the economic efficiency, (C + S) / A ≦ 0.6 as shown in the equation (4). The upper limit of the addition amount was set.

[Experiment 3]
When the above-mentioned heating temperature, equations (1) to (4) and the like are satisfied, valuable metals such as Co and Ni can be separated as metals and oxides. However, the method for recovering valuable metals of the present invention aims to recover valuable metals as lumps of metal. In other words, even if a fine precious metal with a particle size that is too small to form a metal lump, for example, a fine valuable metal with a mesh size of 1 mm and under a sieve, was obtained, the valuable metal could be recovered as a metal lump. It doesn't mean that. It is difficult to recover such fine metal particles even by using magnetic separation, and it is not possible to recover such fine metal particles with good magnetic selection efficiency, which greatly reduces the metal recovery rate.

Therefore, in the method for recovering valuable metals of the present invention, we also propose a method in which fine metal particles are more agglomerated, grown to particles having a particle size of more than 1 mm, and then recovered as metal. This is because good magnetic separation efficiency can be maintained if the particles are recovered as particles having a particle size of more than 1 mm. 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], the valuable metal is increased by heating so that the relationship of the formula (5) is established. It is possible to collect by yield. The applicant confirms that the relational expression of the equation (5) is empirically derived and satisfies the actual data.

The relationship of the above-mentioned formula (5) (relationship between the heating temperature T [° C.] and the heating time t [min]) is derived from the result of Experiment 3.

That is, as shown in Table 3, Experiment No. 1 to No. For the seven samples of 7, the heating temperature T [° C.] was changed in the range of 1373 ° C. to 1548 ° C., and the heating time t [min] was changed in the range of 1.2 min to 23.0 min. Measure the yield when recovering valuable metals.

The above-mentioned experiment No. 1 to No. When the parameters (temperature / time parameters) corresponding to the left side of the equation (6), that is, the parameters of "T + 5 × t" are calculated for the sample of No. 7, the experimental No. 7 which is a comparative example is calculated. 1 to No. No. 4 is 1395.9 to 1488.3, and the experimental No. 4 is an example. 5 to No. 7 is 1491.5 to 1574.1. The comparative examples having parameters of 1395.9 to 1488.3 were all evaluated as "x", and the examples having parameters of 1491.5 to 1574.1 were all evaluated as "○".

In addition, as in Tables 1 and 2, in order to make it easier to understand the relationship between the "temperature / time parameters" and "yield" in Table 3, the horizontal axis is the value of the "temperature / time parameter" and the vertical axis is the value. Taking the value of "yield" and plotting the results of "○" and "×" on the graph, the result is as shown in FIG.
As shown in FIG. 3, the "yield" indicates a linear change (linear change) with respect to the "temperature / time parameter". Here, the experimental No. 1 with a parameter of 1488.3. Experiment No. 4 has a parameter of 1491.5, while 4 has a yield of 79.7%. 5 gives 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.

It should be noted that the embodiments disclosed this time are exemplary in all respects and are not restrictive. In particular, in the embodiments disclosed this time, matters not explicitly disclosed, such as operating conditions, operating conditions, various parameters, dimensions, weights, volumes of components, etc., deviate from the scope normally implemented by those skilled in the art. A value that can be easily assumed by a person skilled in the art is adopted.

Claims

A recovered material containing a valuable metal is obtained by subjecting a used secondary battery to processing of heating, crushing, sieving, and magnetic separation, and the obtained recovered product is mixed with a reducing agent and heated. In a method for recovering a valuable metal, which separates a metal and an oxide from the mixture by metallizing the valuable metal in the mixture by reduction and melting the metal, and selecting and recovering the metal from the oxide after cooling.
The heating temperature of the mixture is set to 1400 ° C. or higher.
When mixing the reducing agent with the recovered product,
When the amount of oxygen compounded with the valuable metal in the mixture is O [mol / kg] and the content of the reducing agent contained in the mixture is R [mol / kg], 0 <O / R. Make sure that ≤0.97 holds,
And,
A reducing agent is added to the recovered product so that the ratios x and y of the concentrations [wt%] of Al 2 O 3 , SiO 2 , and CaO contained in the mixture satisfy the following formulas (1) to (4). A method for recovering valuable metals, which comprises mixing and recovering valuable metals.
A recovered material containing a valuable metal is obtained by subjecting a used secondary battery to processing of heating, crushing, sieving, and magnetic separation, and the obtained recovered product is mixed with a reducing agent and heated. In a method for recovering a valuable metal, which separates a metal and an oxide from the mixture by metallizing the valuable metal in the mixture by reduction and melting the metal, and selecting and recovering the metal from the oxide after cooling.
When mixing the reducing agent with the recovered product,
When the amount of oxygen compounded with the valuable metal in the mixture is O [mol / kg] and the content of the reducing agent contained in the mixture is R [mol / kg], 0 <O / R. Make sure that ≤0.97 holds,
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 the following equations (1) to (4). A reducing agent is mixed with the recovered product so as to satisfy the above conditions.
Further, when heating the recovered product mixed with the reducing agent, when the heating temperature for heating the mixture is T [° C.] and the time for heating the mixture is t [min], the following formula (5) ) Is satisfied, the method for recovering valuable metals, which comprises heating the recovered material.
The method for recovering a valuable metal according to claim 1 or 2, wherein at least one of a carbonaceous reducing agent, metal Al, and metal Si is used as the reducing agent.
The recovery of the valuable metal according to any one of claims 1, 2 or 3, wherein a reducing agent having a particle size of 75 μm or less and an integrated volume adjusted to 65% or more is used. Method.