JP6352669B2 - Lithium-ion battery waste treatment method - Google Patents

Description

  The present invention relates to a method for treating lithium ion battery waste when efficiently separating and recovering valuable materials from lithium ion battery waste. In more detail, among the substances contained in lithium ion battery waste, lithium is efficiently separated and used in the subsequent process, thereby reducing the cost required for the treatment of lithium ion battery waste. It is about the method.

  In recent years, the amount of secondary batteries used in various industrial fields including electronic devices has increased dramatically, reaching the end of the battery's product life and being rejected as a defective product in the manufacturing process. The amount discarded is also increasing.

  Although there are various types of secondary batteries, the current mainstream due to their capacity and electromotive force is the use of lithium metal salts containing manganese, cobalt and nickel as the positive electrode material. Lithium, manganese, cobalt, and nickel are relatively expensive elements, and it is desirable to recover these from discarded batteries and reuse them.

  As a technique for recovering valuable metals from secondary batteries, for example, in Patent Document 1, after various elements are dissolved from secondary battery waste with acid, manganese, cobalt and nickel are sequentially separated and recovered by solvent extraction. A technique for recovering each valuable metal by leaving lithium in the aqueous phase is disclosed.

  In Patent Document 2, secondary battery waste is roasted, crushed and sieved, and then leached with acid to remove impurities cadmium, iron and zinc by solvent extraction, and cobalt is further solvent extracted. Discloses a technique for separating and concentrating and collecting electrolytically, and collecting nickel by electrolytically collecting nickel remaining in the leachate.

JP 2009-193778 A JP 2005-149889 A

  Currently, aluminum is the most difficult-to-treat impurity among the waste lithium ion battery positive electrode materials. Since the positive electrode material of a lithium ion battery is coated on an aluminum foil, a large amount of aluminum is used in the lithium ion secondary battery. If the waste cathode material is roasted, crushed and sieved, some aluminum can be separated and removed, but still a non-negligible amount is mixed.

  The aluminum mixed here can be precipitated and separated by pH adjustment in the aluminum precipitation step after dissolution. However, since aluminum forms a gel-like hydroxide at that time, it is co-precipitated with nickel and cobalt which are valuable materials during precipitation. As a result, the recovery rate of nickel and cobalt separated and recovered thereafter is reduced.

  In order to prevent this, it is conceivable to form a composite salt of lithium and aluminum in the presence of lithium ions when aluminum is precipitated. However, in this case, if relatively expensive lithium is added separately, there is a problem in terms of cost.

  An object of the present invention is to solve such a problem. The object of the present invention is to treat aluminum lithium with nickel or cobalt in an aluminum precipitation process in treating lithium ion battery waste. An object of the present invention is to provide a method for treating lithium ion battery waste that can reduce the cost by effectively obtaining lithium added to prevent coprecipitation.

As a result of earnest research to solve the above problems, the present inventor has paid attention to the fact that lithium is originally contained in the lithium ion battery waste to be treated, and has undergone a pretreatment roasting step and the like. By immersing the lithium ion battery waste in the form of carbonate in an aqueous solution containing calcium, the carbonate ions are fixed as calcium carbonate, thereby promoting the dissolution of lithium in the aqueous solution and We found that it can be separated efficiently.
Then, it was considered that by using such a lithium solution in the subsequent aluminum precipitation step, processing such as recovery of valuable materials from lithium ion battery waste can be performed effectively and at low cost.

Based on such knowledge, the method for treating lithium ion battery waste according to the present invention is a method for treating lithium ion battery waste containing at least lithium, aluminum, nickel, and cobalt, and is in the form of lithium carbonate. the lithium ion battery waste containing lithium Nasu, by immersion in an aqueous solution containing a calcium salt, by dissolving lithium in the aqueous solution, see containing lithium dissolved to obtain a lithium solution, the lithium dissolving step Thereafter, by solid-liquid separation, a solid-liquid separation step of collecting a residue containing aluminum, nickel, and cobalt from the lithium solution, and acid leaching of the residue collected in the solid-liquid separation step The acid leaching step obtained and the acid leaching solution obtained in the acid leaching step remove the residue in the solid-liquid separation step. After having mixed the stomach lithium solution, and further comprising an aluminum precipitation step to precipitate the aluminum contained in the acid leachate.

In the lithium dissolving step, the calcium salt contained in the aqueous solution is preferably calcium hydroxide.
In this case, in the lithium dissolving step, the amount of calcium hydroxide contained in the aqueous solution is 5.5 to 11 times the amount of lithium contained in the lithium ion battery waste. preferable.
In the lithium dissolution step, it is preferable to continue immersion of lithium ion battery waste in the aqueous solution until the concentration of lithium dissolved in the aqueous solution reaches 4 g / L to 36 g / L.

The treatment method described above further includes a nickel / cobalt recovery step of recovering nickel and cobalt from the acid leaching solution from which aluminum has been removed after the aluminum precipitation step,
It is preferable to use what added calcium salt to the aqueous solution after nickel and cobalt were collect | recovered by the said nickel * cobalt collection | recovery process as said aqueous solution containing the said calcium salt in the said lithium melt | dissolution process.

According to the present invention, the following effects can be obtained.
By selectively recovering lithium from lithium-ion battery waste in advance and using it in the aluminum precipitation separation process, the aluminum is low in cost and more efficient than when relatively expensive lithium is added separately. Can be separated and removed. As a result, for example, the cost required for the treatment of lithium ion battery waste such as recovery of nickel and cobalt from the lithium ion battery waste can be reduced.

It is process drawing which shows roughly the processing method of the lithium ion battery waste which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
In a preferred embodiment of the present invention, first, positive electrode material waste of a lithium ion secondary battery as a lithium ion battery or other lithium ion battery waste is sieved to remove some aluminum pieces. Here, the crushed material after sieving of the lithium ion battery waste is immersed in an aqueous solution containing a calcium salt (hereinafter also referred to as “calcium salt-containing solution”) to dissolve lithium, and a lithium solution. Get. Next, the lithium solution is subjected to solid-liquid separation, and a residue containing aluminum, nickel, and cobalt (hereinafter, also referred to as “valuable material-containing residue”) is separated from the lithium solution. Thereafter, the residue containing valuables is leached with an acid such as sulfuric acid to leach aluminum, nickel and cobalt to obtain an acid leaching solution, and the above lithium solution is added to the acid leaching solution, and the lithium concentration is adjusted. For example, after adjusting to 2 to 25 g / L, the pH is adjusted to 3.5 to 5.0, for example. Thereby, it is possible to selectively precipitate and separate aluminum while suppressing coprecipitation with nickel or cobalt. FIG. 1 shows a process diagram.

What is the object of processing in the processing method according to the present invention is, for example, lithium ion battery waste discarded due to product life of the battery, manufacturing failure or other reasons, for example, lithium ion battery positive electrode material waste, lithium ion One obtained by incineration of the battery or one obtained by separating and crushing the positive electrode material with aluminum foil.
Lithium-ion battery waste contains lithium, aluminum, nickel and cobalt in particular in a positive electrode material with an aluminum foil, and may contain, for example, manganese, iron, phosphoric acid, sodium and the like in addition to these. . Among them, it is desirable to collect rare elements such as cobalt and nickel from the discarded lithium ion battery waste.
In the present invention, such lithium ion battery waste is sequentially subjected to necessary treatments in the following steps.

(Roasting process)
The lithium ion battery waste can be roasted as necessary. Thereby, while the unnecessary substance contained in a lithium ion battery is decomposed | disassembled, burned or volatilized, the aluminum foil can be removed to some extent by making the positive electrode material containing many valuables into a state which can be peeled from an aluminum foil.
Moreover, in this roasting process, lithium contained in the lithium ion battery waste is changed into oxides after absorbing carbon dioxide from combustion of organic substances or carbon dioxide in the air after being changed into oxides. It will be. It should be noted that halides such as lithium chloride and lithium fluoride are more effectively dissolved in an aqueous calcium salt solution than lithium carbonate. Therefore, a lower proportion of lithium carbonate is better, but a method for controlling this is not known.

In addition, as a heating furnace which performs roasting, a fixed bed furnace, an electric furnace, a heavy oil furnace, a kiln furnace, a stalker furnace, a fluidized bed furnace, etc. can be used. Can be roasted over time.
In addition, after performing the necessary chemical treatment together with such heat treatment by roasting, and adjusting to an appropriate size by crushing lithium ion battery waste using a uniaxial crusher or a biaxial crusher, The following sieving step can be carried out.

(Sieving process)
In this sieving step, it is preferable to screen the lithium ion battery waste after being crushed as described above, thereby removing a part of the aluminum, so that the aluminum content is, for example, 7 wt% or less. In order to effectively screen, it is desirable to perform the above-described heat treatment and chemical treatment on the lithium ion battery waste in advance.

  Although the present invention can be applied even when sieving is not performed, the amount of reagent used in acid leaching and neutralization in the acid leaching step described later increases. Similarly, when the separation of aluminum is insufficient, the cost increases. Therefore, the aluminum content of the positive electrode material after sieving is preferably 7 wt% or less, and more preferably 1 wt% or less.

(Lithium dissolution process)
The sieve is immersed in a calcium salt-containing solution. As described above, lithium contained in lithium ion battery waste is changed to lithium carbonate by roasting. By immersing this lithium ion battery waste in a calcium salt-containing solution, based on the reaction shown in the following formula (1), the carbonate of lithium carbonate is gradually fixed as calcium carbonate, so that the dissolution of lithium proceeds. A lithium solution is produced.
Li ₂ CO ₃ + Ca ²⁺ → 2Li ⁺ + CaCO ₃ formula (1)

As an aqueous solution used for dissolving lithium, a salt containing a cation that precipitates a poorly soluble carbonate, for example, one containing barium chloride or the like may be used. However, a calcium salt is realistic in terms of toxicity and operability. Of these, calcium hydroxide (slaked lime) is most preferable from the viewpoints of price and reactivity.
As the calcium salt, for example, calcium chloride, calcium oxide, calcium nitrate, calcium sulfate, calcium hypochlorite and the like can be used in addition to the above calcium hydroxide.

  As can be seen from the above formula (1), the amount of calcium in the calcium salt-containing solution can effectively dissolve lithium carbonate contained in the lithium ion battery waste as long as it is 0.5 mol times or more of lithium. it can. On the other hand, if there is too much calcium, there is a risk of gypsum precipitation when sulfuric acid is added in a later step, so the amount of calcium can be up to 2 moles of lithium in lithium ion battery waste. . When this is converted into calcium hydroxide, the amount of calcium hydroxide is preferably 5.5 to 11 times by weight of lithium, more preferably 7 to 8.5 times by weight of lithium.

  Many calcium salts have low solubility in water, but the effect can be obtained by adding them in the form of a slurry without dissolving them completely and using them as a calcium salt-containing solution. However, since the reaction rate cannot be said to be fast, it is desirable to heat and dissolve the calcium salt in advance.

  The end point of lithium dissolution can be determined by the concentration of lithium, and considering the solubility of lithium hydroxide, it is appropriate that the lithium concentration be 36 g / L or less. The lower limit varies depending on the lithium content in the raw material lithium ion battery waste, but is preferably 4 g / L. If the lower limit is less than 4 g / L, it is not considered that the dissolution reaction has progressed, and it is difficult to effectively reduce the cost from the viewpoint of reusing the lithium solution as described later.

When the lithium ion battery waste is immersed in the calcium salt-containing liquid to cause the reaction represented by the above formula (1), the heating temperature is not particularly limited, but in consideration of cost and operability, If the temperature is too high, the solubility of lithium carbonate also decreases, so that the liquid temperature is preferably 45 ° C to 70 ° C. More preferably, the liquid temperature is 45 to 55 ° C.
At this time, the calcium salt-containing liquid in which the lithium ion battery waste is immersed can be stirred as necessary.

  The calcium salt-containing liquid used in this step has a relatively high lithium concentration and can be used in a subsequent aluminum precipitation step. Further, when the aqueous solution contains an alkaline salt such as calcium hydroxide, calcium oxide, calcium hypochlorite, etc., the amount of alkali used for pH adjustment in the aluminum precipitation step can be suppressed. More effective in terms of cost.

  By using the lithium solution separated in this step in the aluminum precipitation step, the cost of the reagent can be reduced. Further, the lithium solution may be input into a lithium purification step to recover lithium.

(Solid-liquid separation process)
As described above, solid solution separation is performed on a lithium solution obtained by immersing lithium ion battery waste in a calcium salt-containing aqueous solution to separate a valuable material-containing residue from the lithium solution. The solid-liquid separation here can be performed by separation using a general filter press, thickener or the like.

(Acid leaching process)
The valuable substance-containing residue recovered in the solid-liquid separation step mainly includes aluminum, nickel, cobalt, and the like. Here, an acid leaching solution is obtained by dissolving the valuable material-containing residue with an acid.
Examples of the acid that can be added in this case include sulfuric acid, hydrochloric acid, nitric acid, and acetic acid. Among them, sulfuric acid is preferable from the viewpoint of non-oxidation property at room temperature and low coordination ability to metals. If it has oxidation ability, it will cause deterioration of the extractant in solvent extraction in the subsequent process. In addition, if the coordination ability is high, the extraction rate may decrease in the solvent extraction step.
Here, in leaching the valuable material-containing residue, the pH can be adjusted to, for example, 1.5 to 3 by adding the acid.

(Aluminum precipitation process)
In the aluminum precipitation step, the acid leaching solution obtained in the acid leaching step is used to precipitate aluminum by adjusting the pH to obtain a high-purity nickel-cobalt solution.
In this aluminum precipitation step, the lithium solution from which the valuable material-containing residue has been recovered in the solid-liquid separation step can be mixed with the acid leaching solution in a predetermined amount, and the pH can be adjusted. Coprecipitation with objects can be prevented.

In this case, the aluminum is Al (OH) ₃ , LiAlO ₂ , LiAl ₂ (OH) ₇ .2H by adjusting the lithium concentration in the lithium dissolution step as described above and adjusting the pH in the subsequent aluminum precipitation step. A mixture precipitate such as ₂ O is formed. When the lithium solution is not mixed, Al (OH) ₃ causes coprecipitation with nickel and cobalt due to the gel-like precipitation, but the pH is adjusted under conditions where lithium is mixed and lithium is mixed. When precipitation is caused, the form of the precipitate is close to a powder rather than a gel, so that the amount of other metal components co-precipitated with aluminum is greatly reduced.

  Here, since a lithium solution is added as a lithium source, it is more advantageous in terms of cost than when a reagent is used. In addition, after this aluminum precipitation step, lithium in the liquid is an alkali metal, so separation of lithium in the liquid from nickel and cobalt can be easily realized by solvent extraction, etc., so there is almost no inconvenience due to addition of lithium. Absent.

  When the lithium solution is added, the lithium concentration in the solution is preferably 2 g / L to 25 g / L, more preferably 2 g / L to 15 g / L, and particularly 2 g / L to 8 g / L. preferable. The pH is preferably 3.5 to 5.0, more preferably 4.0 to 5.0. If the lithium concentration here is too high, the aqueous solution may contain more lithium than necessary, which may affect the solvent extraction process. On the other hand, if the lithium concentration is too low, nickel and cobalt precipitate. There is a possibility that the amount of valuable materials lost due to coprecipitation will increase. Moreover, if the pH is too high, valuables may be lost due to hydroxylation precipitation. On the other hand, if the pH is too low, precipitation separation of aluminum may be incomplete. .

(Nickel / cobalt recovery process)
After the aluminum precipitation step, the aluminum precipitate is removed from the acid leaching solution, and mainly nickel, cobalt, and other valuable materials are recovered using a known method such as a solvent extraction method.
Here, when the lithium solution is mixed with the acid leaching solution in the aluminum precipitation step, lithium remains in the aqueous solution after recovering valuable materials such as nickel and cobalt. If calcium salt is added again to this aqueous solution after recovering valuable materials and this is repeatedly used in the lithium dissolution step, lithium is naturally concentrated, and there is an advantage that the purification of lithium becomes easy. Further, the increase in lithium concentration by repeatedly using such an aqueous solution is advantageous because it works advantageously also during precipitation separation of aluminum.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these.

(Example)
As a raw material, the waste lithium ion secondary battery was incinerated in a roasting process, crushed with a uniaxial crusher, and then used as an incinerator for a waste lithium ion secondary battery screened at <0.5 mm. The ingredients are shown in Table 1. For quantitative analysis of the components, an appropriate amount was collected, decomposed with aqua regia and diluted, and then the concentrations of various elements were quantified by ICP emission spectroscopy (ICP-AES).
500 g of this raw material was weighed and transferred to a 2000 ml beaker. 1 L of a calcium salt-containing solution containing 156 g / L of calcium hydroxide was added, heated to 60 ° C., and stirred for 2 hours. The valuable material-containing residue was separated with 5C filter paper. The filtrate (lithium solution) was stored separately.
A portion of the lithium solution was taken, diluted appropriately with dilute hydrochloric acid, and the concentrations of various elements were quantified by ICP emission spectroscopy (ICP-AES). The components were contained at the concentrations shown in Table 2.

  The separated valuables-containing residue was transferred to a 2000 ml beaker. 1000 ml of pure water was added, pH 2.2 was adjusted with concentrated sulfuric acid, and the mixture was leached with stirring at 60 ° C. for 2 hours. 300 ml of the acid leachate thus obtained was collected. The separated lithium solution was gradually added to the separated acid leachate. The liquid volume was adjusted with water so that it was always 330 ml.

  Assuming that Mn does not coprecipitate with respect to the change in Mn concentration, Mn is approximately 10% in terms of dilution and sampling loss, as can be seen from the results shown in Table 3 at pH 2.2 and pH 4.5. Is lost. If this is applied to cobalt and nickel, and about 10% of cobalt and nickel are lost for the same reason, the original concentrations (31.4 g / l, 1.6 g / l, respectively) are obtained when aluminum disappears. By subtracting 10% from 1), it can be calculated as about 28.3 g / l for cobalt and about 1.44 g / l for nickel. Comparing these calculated values with the measured concentrations of cobalt and nickel at pH 4.5 in Table 3, it can be said that there is almost no loss of cobalt and nickel due to coprecipitation at pH 4.5. Therefore, it can be seen that in the aluminum precipitation step, only the aluminum component of the acid leaching solution is precipitated and separated and removed in the aluminum precipitation step by the lithium solution previously separated without adding any reagent.

(Comparative example)
The same dilute sulfuric acid solution having a cobalt, nickel, aluminum and manganese concentration of pH 2.2 as in the above example was prepared. The metal source was sulfate (made by Wako Pure Chemical Industries, Ltd., special grade). A sodium hydroxide solution adjusted to 1N was gradually added dropwise to observe changes in metal concentration and pH in the solution. The amount was adjusted with water so that it was always 330 ml.
The method for analyzing the metal concentration is in accordance with the example. The results are shown in Table 4.

  It can be seen that the loss of cobalt is large when aluminum is almost precipitated at pH 4.5. For example, if Mn is not co-precipitated, it is 20% lower than the initial concentration due to dilution and sampling loss. When this is applied to cobalt, the decrease due to dilution or sampling loss is 27 g / l, and nickel is 1.4 g / l. Compared with the measured values at pH 4.5 in Table 4, at pH 4.5, It can be seen that more cobalt and nickel are lost.

Claims (5)

A method of treating lithium ion battery waste containing at least lithium, aluminum, nickel and cobalt, comprising:
The lithium ion battery waste containing lithium in the form of lithium carbonate, by immersion in an aqueous solution containing a calcium salt, by dissolving lithium in the aqueous solution, see containing lithium dissolved to obtain a lithium solution ,
After the lithium dissolution step, a solid-liquid separation step of recovering a residue containing aluminum, nickel and cobalt from the lithium solution by solid-liquid separation, and acid leaching of the residue recovered in the solid-liquid separation step The acid leaching step for obtaining an acid leaching solution and the lithium solution obtained by removing the residue in the solid-liquid separation step are mixed with the acid leaching solution obtained in the acid leaching step, and then included in the acid leaching solution. A method for treating lithium ion battery waste , further comprising an aluminum precipitation step of precipitating aluminum . The method for treating lithium ion battery waste according to claim 1, wherein the calcium salt contained in the aqueous solution is calcium hydroxide in the lithium dissolution step. In the lithium dissolution step, the amount of calcium hydroxide contained in the aqueous solution is 5.5 to 11 times the amount of lithium in the form of lithium carbonate contained in the lithium ion battery waste. The method for treating lithium ion battery waste according to claim 2 , wherein: The lithium ion battery waste is continuously immersed in the aqueous solution until the lithium concentration dissolved in the aqueous solution in the lithium dissolving step is 4 g / L to 36 g / L. according to any one of 3, the processing method of the lithium-ion battery waste. A nickel-cobalt recovery step of recovering nickel and cobalt from the acid leachate from which aluminum has been removed after the aluminum precipitation step;
Any of Claims 1-4 which use what added calcium salt to the aqueous solution after nickel and cobalt were collect | recovered by the said nickel cobalt recovery process as the aqueous solution containing the said calcium salt in the said lithium melt | dissolution process . The method for treating lithium ion battery waste according to one item .

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