Method for extracting lithium in preparation for the recycling of lithium-ion batteries

Abstract

The invention relates to a method for obtaining lithium in preparation for the recycling of lithium-ion batteries (22), comprising: carrying out a comminution process, wherein at least one lithium-ion battery (22) is mechanically comminuted into fragments (26) in the presence of a protective fluid (24) in contact with the lithium-ion battery (22); following the comminution process, passing the protective fluid (24) through a sorbent (20), wherein lithium ions contained in the protective fluid (24) are bound by the sorbent (20) and a lithium-ion-enriched sorbent (20) is obtained; and passing a desorption fluid (32) through the lithium-ion-enriched sorbent (20), wherein lithium ions are desorbed from the sorbent (20) by the desorption fluid (32) and a lithium-ion-enriched desorption fluid (32) is obtained.

Description

The present invention relates to a method for recovering lithium in the preparation for recycling lithium ion batteries.Due to its merits such as high electric energy density, high working electric voltage, long cycle life, lack of memory effect, etc., the rechargeable lithium-ion battery has become widely used in electric appliances such as laptops, mobile phones and electric cars. The demand for lithium is increasing greatly due to, among other things, the disassemblance of electromobility.In view of the increasing spread of lithium ion batteries, the amount of old batteries present also increases. In order to permanently cover the demand for lithium, the utilization or recycling of old batteries is of great importance. In order to prepare lithium-ion batteries for recycling, the lithium-ion batteries are typically first mechanically comminuted into portions in a comminution process. If the lithium-ion batteries are charged or partially charged, there is a risk of fire during the mechanical comminution. The comminution therefore often takes place in the presence of a protective fluid which performs a fire protection function. The mechanical comminution into the parts exposes the lithium-containing interior of the lithium-ion batteries. The lithium contained in the sections can then be obtained within the framework of the actual recycling by a pyrometallurgical treatment and / or by a hydrometallurgical treatment of the sections.The invention is concerned with the object of increasing the efficiency with regard to the recovery of lithium from lithium-ion batteries.The above object is achieved according to the invention by a method having the features of claim 1. The dependent claims and the description indicate advantageous variants and embodiments.According to the invention, a method for recovering lithium in the preparation for recycling lithium ion batteries is therefore provided.The method according to the invention comprises: carrying out a comminution process, wherein at least one lithium-ion battery is mechanically comminuted into portions in the presence of a protective fluid in contact with the lithium-ion battery.Thus, at least one lithium-ion battery is brought into contact with a protective fluid and then mechanically comminuted. The comminution process can be configured in various variants. For example, in the course of the comminution process, cutting comminution and / or impact comminution of the at least one lithium-ion battery takes place. Preferably, the at least one lithium-ion battery is mechanically comminuted into the parts by a shredder or shredder. The comminution process takes place in the presence of the protective fluid which is in contact with the at least one lithium-ion battery. Preferably, water or an aqueous solution is used as the protective fluid. Water or aqueous solutions are particularly suitable as protective fluid because they reliably avoid temperature peaks and degrade the electrical charge on contact with electrically charged lithium-ion batteries or electrically charged sections of lithium-ion batteries. However, the presence of the protective fluid also leads to a part of the substances of the at least one lithium-ion battery being discharged into the protective fluid. Materials released include lithium ions and other materials such as phosphorus, nickel, cobalt, manganese, alcohols (methanol, ethanol), fluoride, sulfate, organic carbonates or inorganic carbonates. The protective fluid is thus enriched with lithium ions. The other substances are summarized below under the term "foreign substances".The method of the invention further comprises: subsequent to the comminution operation, passing the protective fluid through a sorbent, wherein lithium ions contained in the protective fluid are bound through the sorbent and a lithium ion enriched sorbent is obtained, and passing a desorption fluid through the lithium ion enriched sorbent, wherein lithium ions are desorbed from the sorbent by the desorption fluid and a lithium ion enriched desorption fluid is obtained.In known methods, the protective fluid and thus the lithium ions contained in the protective fluid were discarded after the comminution process. By the procedure according to the invention, i.e. the passage of the protective fluid through the sorbent and the extraction of lithium ions from the protective fluid connected therewith, in contrast, the efficiency with regard to the recovery of lithium from lithium-ion batteries can be increased overall. Surprisingly, it has been found that the foreign substances contained in the protective fluid at most slightly impair the recovery of lithium by the sorbent. In particular, the expected damage to the chemically and mechanically unstable sorbent by the foreign substances has been surprisingly low.Preferably, the at least one lithium-ion battery is mechanically comminuted in a bath of protective fluid during the comminution process. This particularly effectively reduces the risk of fire caused by the protective fluid. Because the lithium ions released into the protective fluid are recovered by the sorbent, a large volume of protective fluid can be used without adversely affecting the efficiency of recovering lithium from the at least one lithium ion battery. Alternatively, the at least one lithium-ion battery can also be only wetted with the protective fluid and then mechanically comminuted.The final lithium ion-enriched desorption fluid may be processed in further steps to final yield a battery grade lithium compound.The method can be used for different types of lithium ion batteries, i.e. for different cell chemistry types. For example, the at least one lithium ion battery is a nickel-manganese-cobalt rechargeable battery or a lithium iron phosphate rechargeable battery.In some preferred embodiments, it is contemplated that the sorbent is an alumina-based sorbent. Aluminum oxide-based sorbents are particularly stable chemically and mechanically, so that damage by the foreign substances takes place at most to an extremely small extent. Alumina-based sorbents bind lithium ions by adsorption. During an adsorption process, the adsorbed material accumulates at an interface of the sorbent and / or is incorporated into a layered structure of the sorbent. Particularly preferably, the aluminum oxide-based sorbent is an aluminum layered double hydroxide (LDH) having the chemical empirical formula Li x Al 2( OH) 6 Cl x ·n H 2 O, for example. LiCl·Al 2( OH) 6 ·n H 2 O. If the sorbent is an aluminum oxide-based sorbent, then the desorption fluid used is preferably low-salt water.In some preferred embodiments, it is provided that the sorbent is a manganese oxide-based sorbent. Manganese oxide-based sorbents are distinguished by their high selectivity with respect to the binding of lithium ions, so that fine purification can be realized by manganese oxide-based sorbents. Manganese oxide-based sorbents bind lithium ions by exchanging bound hydrogen ions for lithium ions. Manganese oxide-based sorbents therefore act as cation exchangers when lithium ions are bound. The manganese oxide-based sorbent is particularly preferably a sorbent having the chemical empirical formula H x Mn y O z, for example. H 1.6 Mn 1.6 O 4. If the sorbent is a manganese oxide-based sorbent, then an acidic desorption fluid is preferably used as desorption fluid. Particularly preferably, the acidic desorption fluid comprises hydrochloric acid, sulfuric acid and / or acetic acid.In some preferred embodiments, it is provided that the sorbent is a titanium oxide-based sorbent. Titanium oxide-based sorbents are also distinguished by their high selectivity with respect to the binding of lithium ions. Titanium oxide-based sorbents also bind lithium ions by exchanging bound hydrogen ions for lithium ions. Particularly preferably, the titanium oxide-based sorbent is a sorbent having the chemical empirical formula H x Ti y O z, for example. H 2 TiO 3. Preferably, an acidic desorption fluid is also used when using a titanium oxide-based sorbent. Particularly preferably, the acidic desorption fluid comprises hydrochloric acid, sulfuric acid and / or acetic acid.It is also possible to use a mixture of the aforementioned sorbents as sorbent, for example a mixture of a titanium oxide-based sorbent and a manganese oxide-based sorbent.In some preferred embodiments, it is provided that the portions of the at least one lithium ion battery and the protective fluid are separated from one another before the protective fluid is passed through the sorbent. This prevents the sorbent from coming into contact with the sections of the at least one lithium-ion battery. Particularly preferably, the sections and the protective fluid are separated from one another by filtration. However, the portions and the protective fluid can also be separated from one another, for example, by decantation.In some preferred embodiments, it is provided that the protective fluid is passed through the sorbent without chemical pretreatment following the comminution process. Thus, no chemical pretreatment of the protective fluid takes place between the completion of the comminution process and the subsequent introduction of the protective fluid into the sorbent. A chemical pretreatment means influencing a property of the protective fluid by adding one or more chemicals. Examples of such chemical pretreatment are precipitation of a component of the protective fluid by addition of a suitable precipitant or changing the pH of the protective fluid by addition of an acid or a base. By omitting a chemical pretreatment, a particularly time-efficient execution of the method can be realized.In some preferred embodiments, it is provided that a temperature of the protective fluid exceeds a threshold temperature of 40° C. when introducing the protective fluid into the sorbent. It has been found that at such a temperature of the protective fluid, lithium ions are particularly effectively bound by the sorbent. Preferably, the temperature of the protective fluid exceeds a threshold temperature of 50°C, preferably a threshold temperature of 70°C, more preferably a threshold temperature of 80°C, upon introduction of the protective fluid into the sorbent.In some preferred embodiments, it is provided that the comminution process is carried out in such a way that the protective fluid is heated by the comminution process to a temperature exceeding the threshold temperature. The heating of the protective fluid during the comminution process is essentially effected by the discharge of charged or partially charged lithium-ion batteries or sections of lithium-ion batteries. A desired temperature of the protective fluid can be adjusted, for example, by changing the ratio of protective fluid to lithium-ion batteries or by changing the average state of charge of the lithium-ion batteries to be ground. The heating of the protective fluid by the comminution process has the advantage that energy-intensive, separate heating of the protective fluid can be dispensed with. Instead, the thermal energy released in any case is used to heat the protective fluid.In some preferred embodiments, it is provided that lithium contained in the sections is obtained by a pyrometallurgical treatment and / or by a hydrometallurgical treatment of the sections. The parts of the at least one lithium ion battery produced in the comminution process are therefore further processed in the context of a pyrometallurgical treatment and / or a hydrometallurgical treatment. This processing of the parts forms the actual recycling of the at least one lithium-ion battery.The invention is described in more detail below with reference to the figures, wherein identical or functionally identical elements are optionally provided with reference symbols only once. The description is given by way of example and is not intended to be limiting. They show FIG. 1 is a schematic illustration of a plant for preparing the recycling of lithium-ion batteries; and FIG. 2 shows a method for recovering lithium in the preparation for recycling lithium-ion batteries.FIG. 1 shows a schematic illustration of a plant 10 for preparing the recycling of lithium-ion batteries 22.The plant 10 comprises a comminution device 12 which is designed to reduce objects such as, for example. To break down lithium ion batteries 22 into sections 26 mechanically. For this purpose, the comminution device 12 comprises, in the present schematic illustration, a container 14 and a comminution unit 16 arranged in the container 14.The plant 10 also includes a lithium sorption device 28. the lithium sorption device 28 includes a container 18 containing a sorbent 20. Sorbent 20 is configured to bind lithium ions. Preferably, sorbent 20 is an alumina-based sorbent, a manganese oxide-based sorbent, or a titanium oxide-based sorbent. Sorbent 20 is present as a solid. The container 18 is designed as a column in the exemplary embodiment shown in FIG. 1.In the following, with additional reference to FIG. 2, an advantageous method for recovering lithium in the preparation for recycling of lithium-ion batteries 22 is explained in more detail. FIG. 2 shows the method using a flow chart. The method is carried out by means of the plant 10 shown in FIG. 1.In a first step 101, a plurality of lithium-ion batteries 22 and a protective fluid 24 are provided and introduced into the container 14 of the comminution device 12. The lithium-ion batteries 22 are then in contact with the protective fluid 24. In the present case, water is used as the protective fluid 24.In a second step 103, a comminution process is carried out, wherein the lithium-ion batteries 22 are mechanically comminuted into portions 26 in the presence of the protective fluid 24. The comminution process is carried out by the comminution unit 16, not shown in FIG. 2. The lithium-ion batteries 22 are prepared for recycling by the mechanical comminution. The representation of the portions 26 is purely schematic with regard to their shape and size in FIG. 2. If the lithium-ion batteries 22 are charged or partially charged, there is a risk of fire during the mechanical comminution. The comminution is therefore carried out in the presence of the protective fluid 24, which performs a fire protection function.Because the protective fluid 24 is in contact with the lithium-ion batteries 22 during the mechanical comminution, a portion of the substances contained in the lithium-ion batteries 22 is absorbed by the protective fluid 24. In particular, lithium ions contained in the lithium-ion batteries 22 or the sections 26 are partially washed out by the protective fluid 24.If the lithium-ion batteries 22 are not fully discharged, but are partially or fully charged, then a discharge of the lithium-ion batteries 22 or of the portions 26 is achieved by the protective fluid 24 during the comminution process. The discharge generates thermal energy which is absorbed by the protective fluid 24.Preferably, the comminution process is carried out in such a way that the protective fluid 24 heats up to a temperature of more than 80° C. A desired temperature of the protection fluid 24 may be achieved, for example, by selecting an appropriate ratio of the number of lithium ion batteries 22 to the volume of the protection fluid 24, or by using lithium ion batteries 22 having an appropriate average residual charge.In a third step 105, the sections 26 and the protective fluid 24 are separated from one another. Preferably, the portions 26 and the protection fluid 24 are separated from each other by filtration. A separation can be achieved, for example, by a separate filtration unit or by a filter which is integrated into a fluid outlet of the container 14. Alternatively, the sections 26 and the protective fluid 24 can also be separated from one another by decantation.In a fourth step 107, the protective fluid 24 is passed through the sorbent 20. Passing a fluid through a sorbent involves introducing the fluid into the sorbent and then discharging the fluid from the sorbent. As the protective fluid 24 passes through the sorbent 20, lithium ions contained in the protective fluid 24 are bound by the sorbent 20. A sorbent 20 enriched with lithium ions is thus obtained. Depending on the sorbent, the bonding of the lithium ions is based on an adsorption process or an ion exchange. Preferably, the protective fluid 24 has a temperature of greater than 80° C. when introduced into the sorbent 20. Such a high temperature results in effective binding of the lithium ions by the sorbent 20.In an optional fifth step 109, the sorbent 20 is rinsed. For this purpose, a flushing fluid 30 is passed through the sorbent 20 enriched with lithium ions. By passing the flushing fluid 30 through the sorbent 20, residues of the protective fluid 24 together with the non-bound foreign substances are displaced from the sorbent 20. Preferably, inert gas, in particular nitrogen, or water is used as flushing fluid 30.In a sixth step 111, a desorption fluid 32 is passed through the sorbent 20 enriched with lithium ions. The bound lithium ions are desorbed by the desorption fluid 32, so that a regenerated sorbent 20 and a desorption fluid 32 enriched with lithium ions are obtained. Depending on the sorbent 20, a different desorption fluid 32 is used. If the sorbent 20 is an aluminum oxide-based sorbent, then the desorption fluid 32 used is preferably low-salt water. However, if the sorbent 20 is a manganese oxide-based sorbent or a titanium oxide-based sorbent, then an acidic desorption fluid 32 is preferably used as desorption fluid 32.In subsequent steps, not shown, the desorption fluid 32 enriched with lithium ions is further purified, so that finally a lithium compound of battery quality is obtained.In a seventh step 113, lithium contained in the sections 26 is obtained by a pyrometallurgical treatment and / or by a hydrometallurgical treatment of the sections 26. This process constitutes the actual recycling of the lithium-ion batteries 22.

Claims

A method for recovering lithium in the preparation for recycling lithium ion batteries (22), comprising: a. carrying out a comminution process, wherein at least one lithium ion battery (22) is mechanically comminuted into portions (26) in the presence of a protective fluid (24) in contact with the lithium ion battery (22), in particular water or an aqueous solution, b. following the comminution process, passing the protective fluid (24) through a sorbent (20), wherein lithium ions contained in the protective fluid (24) are bound by the sorbent (20) and a lithium ion-enriched sorbent (20) is obtained, and c. passing a desorption fluid (32) through the lithium ion-enriched sorbent (20), wherein lithium ions are desorbed from the sorbent (20) by the desorption fluid (32), and a desorption fluid (32) enriched with lithium ions is obtained.The method of claim 1, characterized in that the sorbent (20) is an alumina-based sorbent.The method according to claim 1, characterized in that the sorbent (20) is a manganese oxide-based sorbent.Method according to claim 1, characterized in that the sorbent (20) is a titanium oxide-based sorbent.Method according to one of the preceding claims, characterized in that the sections (26) and the protective fluid (24) are separated from one another, in particular by filtration, before the protective fluid (24) is passed through the sorbent (20).Method according to one of the preceding claims, characterized in that the protective fluid (24) is passed through the sorbent (20) without chemical pretreatment following the comminution process.Method according to one of the preceding claims, characterized in that a temperature of the protective fluid (24) when introducing the protective fluid (24) into the sorbent (20) exceeds a threshold temperature of 40°C, preferably a threshold temperature of 50°C, preferably a threshold temperature of 70°C, particularly preferably a threshold temperature of 80°C.Method according to claim 7, characterised in that the comminution process is carried out in such a way that the protective fluid (24) is heated by the comminution process to a temperature exceeding the threshold temperature.Method according to one of the preceding claims, characterized in that, before the desorption fluid (32) is passed through, a flushing fluid (30), in particular inert gas or water, is passed through the sorbent (20) enriched with lithium ions.Method according to one of the preceding claims, characterized in that lithium contained in the sections (26) is obtained by a pyrometallurgical treatment and / or by a hydrometallurgical treatment of the sections (26).

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