Method for recovering lithium and lithium compound

Abstract

Disclosed is a method for increasing lithium recovery rate. Provided is a method for recovering lithium, the method according to one aspect comprising the steps of: (S1) preparing a first mixture including a first flux and powder obtained by crushing waste containing Li; (S2) melting the first mixture in an arc furnace under reducing conditions to produce a melt; (S3) separating a first slag and an alloy from the melt; (S4) melting a second mixture including the first slag and a second flux to obtain a second slag and fume; and (S5) separating a lithium solution from the fume.

Description

Method for recovering lithium and lithium compounds

[0001] The present invention (Disclosure) relates to a method for recovering lithium, and more specifically, to a method for recovering lithium and a lithium compound.

[0002] With the advancement of the IT industry and the increasing use of lithium-ion batteries, the volume of waste lithium-ion batteries and scrap generated during the manufacturing process is also increasing. The cathode, which accounts for more than 60% of the cost of lithium-ion batteries, is increasingly made of ternary oxides (nickel, cobalt, manganese), which offer superior battery performance compared to pure materials. These expensive metals are entirely imported, and the technology to recover these discarded metals is a national project.

[0003] The explosive demand for lithium-ion batteries and the shortening life cycles of small digital appliances have led to a sharp increase in lithium-ion battery emissions, leading to growing interest both domestically and internationally in lithium-ion battery processing and recycling. Reusing the waste materials of these batteries when they reach the end of their lifespan not only reduces environmental pollution but also reduces raw material costs during lithium-ion battery production. Accordingly, various research efforts are ongoing to develop methods for recovering lithium.

[0004] According to one aspect of the present invention, a method for recovering lithium is provided that can increase the recovery rate of lithium.

[0005] According to another aspect of the present invention, a method for recovering lithium is provided that can minimize environmental pollution by using a small area and eco-friendly energy.

[0006] According to another aspect of the present invention, a method for recovering lithium is provided, which can shorten the recovery time of lithium.

[0007] According to another aspect of the present invention, a method for recovering lithium is provided, which can obtain an alloy produced as a byproduct during the process of recovering lithium.

[0008] The purposes of the present invention are not limited to those mentioned above, and other unmentioned purposes and advantages of the present invention can be understood through the following description and will be more clearly understood through embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof described in the specification.

[0009] According to a first aspect of the present invention, a method for recovering lithium is provided, comprising: (S1) preparing a first mixture comprising a powder obtained by pulverizing lithium-containing waste and a first flux; (S2) melting the first mixture in an arc furnace under reducing conditions to produce a melt; (S3) separating a first slag and an alloy from the melt; (S4) melting a second mixture comprising the first slag and a second flux to obtain a second slag and fume; and (S5) separating a lithium solution from the fume.

[0010] According to a second aspect of the present invention, in the first aspect, the lithium-containing waste may include at least one selected from the group consisting of waste lithium-ion batteries, waste electrodes, and waste positive electrode active materials.

[0011] According to a third aspect of the present invention, in the first or second aspect, the step (S1) may include a step of calcining the powder.

[0012] According to a fourth aspect of the present invention, in any one of the first to third aspects, the first flux is Al2O 3, CaO, SiO2, and It may include at least one selected from the group consisting of Fe2O3.

[0013] According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the first mixture may further comprise any one additive selected from the group consisting of transition metals, carbonates, and mixtures thereof. In one example, the first flux may further comprise any one additive selected from the group consisting of transition metals, carbonates, and mixtures thereof.

[0014] According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the arc furnace may be any one selected from the group consisting of a DC Electric Arc Furnace (DC-EAF), an AC Electric Arc Furnace (AC-EAF), a plasma arc furnace, and combinations thereof.

[0015] According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the arc furnace may include a direct current electric arc furnace equipped with an electrode rod, the electrode rod may include a carbon electrode, and the reduction condition may be implemented by the carbon electrode.

[0016] According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the step (S2) may include a step performed by a direct current electric arc furnace under an output condition of 50 to 3,000 kW.

[0017] According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the step (S4) may include a step performed in a furnace different from the arc furnace.

[0018] According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the step (S4) may include a step of melting the second mixture at 1400 to 1700°C for 1 to 3 hours.

[0019] According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the second flux may be any one selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, transition metal chlorides, and mixtures thereof.

[0020] According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the fume may include LiCl(g).

[0021] According to a thirteenth aspect of the present invention, in any one of the first to twelfth aspects, the step (S5) includes a step of dissolving the fume in water using a scrubber, and the scrubber may include one or more wet scrubbers.

[0022] According to a fourteenth aspect of the present invention, the method for recovering lithium in any one of the first to thirteenth aspects may further include a step of concentrating the lithium solution (S6).

[0023] According to a fifteenth aspect of the present invention, a lithium compound recovered by a method for recovering lithium according to any one of the first to fourteenth aspects is provided.

[0024] The solutions to the above problems are not exhaustive and may be combined with several embodiments of the present disclosure. The various features of the present invention and their corresponding advantages and effects can be understood in more detail by referring to the detailed description below.

[0025] According to one aspect of the present invention, a method for recovering lithium can be implemented that increases the recovery rate of lithium while minimizing environmental pollution by using a small area and eco-friendly energy.

[0026] According to another aspect of the present invention, a method for recovering lithium can be implemented, which shortens the recovery time of lithium and allows for the reuse of an alloy produced as a byproduct during the recovery process of lithium.

[0027] In addition to the aforementioned effects, specific effects of the present invention are described below along with specific details for implementing the invention. Furthermore, the effects of the present invention are not limited to the effects described above and can be readily achieved using the means and combinations thereof described in the specification.

[0028] Figure 1 illustrates a direct current electric arc furnace used in a method for recovering lithium according to one embodiment of the present invention.

[0029] Figure 2 is a schematic diagram of a wet scrubber used in a lithium recovery method according to one embodiment of the present invention.

[0030] Figure 3 is a flowchart showing a method for recovering lithium according to one embodiment of the present invention.

[0031] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0032] In this specification, expressions such as "first," "second," and "(S1)" and "(S2)" can describe various components, regardless of order and / or importance, and do not limit the components. These expressions may be used to distinguish one component from another. For example, without departing from the scope of the present disclosure, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

[0033] The numerical range indicated by the term "to" in this specification refers to a numerical range that includes the values ​​stated before and after the term as the lower and upper limits, respectively. For example, if "a" and "b" are stated in the specification, it can be understood that "a" and "b" are stated.

[0034] In the present specification, when multiple numerical values ​​are disclosed as the upper and lower limits of any numerical range, the numerical range disclosed in the present specification can be understood as any numerical range that has any one of the multiple lower limit values ​​and any one of the multiple upper limit values ​​as the lower limit value and the upper limit value, respectively. For example, when a or more, or b or more; and c or less or d or less are described, it can be understood that a or more and c or less, a or more and d or less, b or more and c or less, or b or more and d or less are described.

[0035] In the past, in the process of recovering lithium using lithium-containing waste, there was a problem in that the lithium recovery rate was low due to various process factors during the process when the pretreated lithium-containing waste was melted to recover lithium.

[0036] According to one aspect of the present invention, a method for recovering lithium is provided, comprising the steps of (S1) preparing a first mixture containing a powder obtained by pulverizing lithium-containing waste and a first flux, (S2) melting the first mixture in an arc furnace under reducing conditions to produce a melt, (S3) separating a first slag and an alloy from the melt, (S4) melting a second mixture containing the first slag and a second flux to obtain a second slag and fume, and (S5) separating a lithium solution from the fume. According to one aspect of the present invention, by melting the first mixture in the arc furnace, re-melting the first slag from the molten material produced, and separating the lithium solution from the fume produced in the process of melting the first slag, the recovery rate of lithium can be significantly increased, while at the same time minimizing environmental pollution by using a small amount of land and eco-friendly energy.

[0037] Below, the configuration of the present invention is described in more detail.

[0038] 1. Lithium recovery method

[0039] (S1) A step of preparing a first mixture including a powder obtained by crushing lithium-containing waste and a first flux;

[0040] The method for recovering lithium according to the present invention comprises the step of preparing a first mixture containing a powder obtained by crushing lithium-containing waste and a first flux to facilitate the extraction of lithium by crushing lithium-containing waste to increase the surface area (S1).

[0041] In some examples, the lithium-containing waste may include, without limitation, compounds containing lithium in various forms. For example, the lithium-containing waste may include one or more selected from the group consisting of spent lithium-ion batteries, spent electrodes, and spent cathode active materials. Here, the spent electrodes and spent cathode active materials may be electrodes or cathode active materials that are disposed of separately from the spent lithium-ion batteries as separate components.

[0042] In some examples, the waste lithium-ion battery is a lithium-ion battery that has reached the end of its life or is discarded after use, and may be specifically a lithium-containing primary battery, a lithium-containing secondary battery, or a lithium-containing all-solid-state battery. In one example, the waste lithium-ion battery may be scrap or waste of the primary battery, secondary battery, or all-solid-state battery.

[0043] In some examples, the above-mentioned waste cathode active material may be a cathode active material commercially available in the relevant technical field, and may specifically include a lithium transition metal oxide. For example, the lithium transition metal oxide may be Li x1 CoO2(0.5 <x1<1.3), Li x2 NiO2(0.5 <x2<1.3), Li x3 MnO2(0.5 <x3<1.3), Li x4 Mn2O4(0.5 <x4<1.3), Li x5 (Ni a1 Co b1 Mn c1 )O2(0.5 <x5<1.3, 0<a1<1, 0<b1<1, 0<c1<1, a1+b1+c1=1), Li x6 Ni 1-y1 Co y1 O2(0.5 <x6<1.3, 0<y1<1), Li x7 Co 1-y2 Mn y2 O2(0.5 <x7<1.3, 0≤y2<1), Li x8 Ni 1-y3 Mn y3O2(0.5 <x8<1.3, 0≤y3<1), Li x9 (Ni a2 Co b2 Mn c2 )O4(0.5 <x9<1.3, 0<a2<2, 0<b2<2, 0<c2<2, a2+b2+c2=2), Li x10 Mn 2-z1 Ni z1 O4(0.5 <x10<1.3, 0<z1<2), Li x11 Mn 2-z2 Co z2 O4(0.5 <x11<1.3, 0<z2<2), Li x12 CoPO4(0.5 <x12<1.3) 및 Li x13 FePO4(0.5 <x13<1.3)로 이루어진 군에서 선택되는 하나 이상을 포함할 수 있다.

[0044] In this specification, the average particle diameter is the particle diameter at the 50% point of the cumulative distribution of the number of particles according to particle diameter (D 50 ) means the average particle diameter (D 50 ) is a method of dispersing a sample in a dispersion medium according to the laser diffraction method, and then introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to measure the difference in diffraction pattern according to particle size when the particles pass through the laser beam, thereby calculating the cumulative distribution of the number of particles according to particle size.

[0045] In this specification, "powder" may be defined as a pulverized product obtained by pulverizing lithium-containing waste. In one example, the average particle diameter (D) of the powder 50) is not particularly limited, but may be specifically 3 mm or less, 2 mm or less, 1 mm or less, 0.1 mm or less, 0.01 mm or less, and may be specifically 0.001 mm or more and any one of the plurality of upper limits or less. In another example, the particle size of the powder may be adjusted to 100 mesh or less, 90 mesh or less, 80 mesh or less, 70 mesh or less, 60 mesh or less, 50 mesh or less, 40 mesh or less, 30 mesh or less, 20 mesh or less, or 10 mesh or less, and may be specifically 1 mesh or more and any one of the plurality of lower limits or less.

[0046] For example, if the lithium-containing waste is a waste lithium-ion battery or waste cathode active material, the powder may be black mass.

[0047] In some embodiments of the present invention, the step (S1) may include a step of calcining the powder. Specifically, by calcining the powder, substances such as organic binders contained in the powder can be effectively removed, thereby significantly reducing the content of impurities other than those to be recovered. For example, the step of calcining the powder is not particularly limited, but may specifically include a step of calcining at 600 to 900°C for 10 to 14 hours.

[0048] The first flux according to the present invention can lower the melting point of the first mixture and lower the viscosity of the melt in the melting process described below to control fluidity, while at the same time easily inducing a reduction reaction of the precious metal contained in the powder.

[0049] In some embodiments of the present invention, the content of the first flux may be 30 wt% or more and 50 wt% or less based on the total weight of the first mixture. Specifically, the content of the first flux may be 30 wt% or more, 31 wt% or more, 32 wt% or more, 33 wt% or more, 35 wt% or more, 36 wt% or more, 37 wt% or more, 38 wt% or more, 39 wt% or more, or 40 wt% or more; and 41 wt% or less, 42 wt% or less, 43 wt% or less, 44 wt% or less, 45 wt% or less, 46 wt% or less, 47 wt% or less, 48 ​​wt% or less, 49 wt% or less, or 50 wt% or less based on the total weight of the first mixture. For example, the content of the first flux based on the total weight of the first mixture may be 30 to 50 wt%, 31 to 49 wt%, 35 to 48 wt%, 36 to 47 wt%, 37 to 46 wt%, 38 to 45 wt%, 39 to 44 wt%, 40 to 43 wt%, 40 to 42 wt%, or 40 to 41 wt%. According to some embodiments of the present invention, by controlling the content of the first flux within the above numerical range, the viscosity of the melt can be lowered, effectively controlling the fluidity, and at the same time, easily inducing a reduction reaction of the precious metal contained in the powder.

[0050] In some examples, the first flux is not particularly limited, but is specifically Al2O 3, CaO, SiO2, and It may include at least one selected from the group consisting of Fe2O3, and specifically Al2O 3, It may contain CaO and SiO2.

[0051] In some embodiments of the present invention, based on the total weight of the first mixture, the content of Al2O3 may be 1 wt% or more and 13 wt% or less. Specifically, based on the total weight of the first mixture, the content of Al2O3 may be 1 wt% or more, 2 wt% or more, 3 wt% or more, 4 wt% or more, 5 wt% or more, 6 wt% or more, or 7 wt% or more; and 8 wt% or less, 9 wt% or less, 10 wt% or less, 11 wt% or less, 12 wt% or less, or 13 wt% or less. For example, based on the total weight of the first mixture, the content of Al2O3 may be 1 to 13 wt%, 2 to 12 wt%, 3 to 11 wt%, 4 to 10 wt%, 5 to 9 wt%, 6 to 8 wt%, or 7 to 8 wt%.

[0052] In some embodiments of the present invention, based on the total weight of the first mixture, the content of CaO may be 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, 15 wt% or more, 16 wt% or more, or 17 wt% or more; and 18 wt% or less, 19 wt% or less, 20 wt% or less, 21 wt% or less, 22 wt% or less, or 23 wt% or less. For example, based on the total weight of the first mixture, the content of CaO may be 11 to 23 wt%, 12 to 22 wt%, 13 to 21 wt%, 14 to 20 wt%, 15 to 19 wt%, 16 to 18 wt%, or 17 to 18 wt%.

[0053] In some embodiments of the present invention, based on the total weight of the first mixture, the content of SiO2 may be 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, 15 wt% or more, or 16 wt% or more; and 17 wt% or less, 18 wt% or less, 19 wt% or less, 20 wt% or less, 21 wt% or less, or 22 wt% or less. For example, based on the total weight of the first mixture, the content of SiO2 may be 10 to 22 wt%, 11 to 21 wt%, 12 to 20 wt%, 13 to 19 wt%, 14 to 18 wt%, 15 to 17 wt%, or 16 to 17 wt%.

[0054] According to some embodiments of the present invention, by controlling each composition in the first flux within the above numerical range, the viscosity of the melt can be lowered, effectively controlling the fluidity, and at the same time, easily inducing a reduction reaction of the precious metal contained in the powder.

[0055] In some embodiments of the present invention, the first mixture may further include any one additive selected from the group consisting of transition metals, carbonates, and mixtures thereof. Specifically, the additive can further lower the melting point of the first mixture and effectively control the fluidity of the melt in the melting process described below. For example, the transition metal is not particularly limited, but may specifically include Cu, and the carbonate is not particularly limited, but may specifically include any one selected from the group consisting of CaCO3, MgCO3, and mixtures thereof. For example, the content of the additive is not particularly limited, but may specifically be 3.0 wt% or less, 2.0 wt% or less, 1.0 wt% or less, or 0.5 wt% or less, based on the total weight of the first mixture, and specifically may be 0.1 wt% or more and any one of the plurality of upper limits or less.

[0056] (S2) A step of reducing and melting the first mixture in an arc furnace under reducing conditions to produce a melt;

[0057] In this specification, the "reducing condition" refers to a condition for forming a reducing atmosphere during the smelting process of the step (S2), and may be a condition for reducing a precious metal in the powder obtained by pulverizing the lithium-containing waste to produce an alloy to be described later. For example, the reducing condition is not particularly limited and may be formed by separately adding a reducing agent to the arc furnace or the first mixture, or may be implemented through an electrode (e.g., a carbon electrode) provided in the arc furnace without separately adding the reducing agent. In one embodiment, the first mixture may not include a reducing agent.

[0058] In this specification, “Arc furnace” is not particularly limited and may be a furnace that heats the first mixture using an electric spark generated when a high voltage difference is applied to positive and negative terminals.

[0059] In some embodiments of the present invention, the arc furnace may be any one selected from the group consisting of a DC Electric Arc Furnace (DC-EAF), an AC Electric Arc Furnace (AC-EAF), a plasma arc furnace, and combinations thereof, and specifically may be a DC Electric Arc Furnace (DC-EAF). In some embodiments of the present invention, by using any one selected from the group consisting of a DC Electric Arc Furnace (DC-EAF), an AC Electric Arc Furnace (AC-EAF), a plasma arc furnace, and combinations thereof as the arc furnace, a molten material can be stirred by an arc discharge, thereby separating an alloy having a uniform composition. If an induction furnace that uses resistance heat from induced current is used instead of an arc furnace that uses a heat source from arc discharge, it may be difficult to configure the equipment to be large in size and problems such as low composition uniformity within the alloy may occur.

[0060] According to some embodiments of the present invention, when a direct current electric arc furnace is used, a melting process can be effectively induced by using a higher current density and power than other types of arc furnaces, thereby increasing the recovery rate of lithium.

[0061] Meanwhile, a direct current electric arc furnace is specifically described with reference to Fig. 1.

[0062] Figure 1 illustrates a direct current electric arc furnace used in a method for recovering lithium according to one embodiment of the present invention.

[0063] Referring to FIG. 1, a direct current electric arc furnace (100) according to the present invention may include an electrode rod (10), a lower electrode (20), a separating section (30), an exhaust section (40), and a cooling section (50).

[0064] The electrode rod (10) according to the present invention can generate an arc to heat and melt the first mixture. For example, the electrode rod (10) may be formed vertically (e.g., in the height direction) through an opening in the center of a roof of a direct current electric arc furnace (100). In one example, the number of the electrode rods is not particularly limited, but may be specifically 1, 2 or more, or 3 or more.

[0065] The lower electrode (20) according to the present invention can be electrically connected to the electrode rod (10) to provide a path for current to flow. For example, the lower electrode (20) can be placed at the bottom of a direct current electric arc furnace (100), and specifically, can be placed at the bottom of an alloy which is one of the melting results of the first mixture.

[0066] The separation unit (30) according to the present invention can separate the first slag (S) and the alloy (A) generated in the DC electric arc furnace (100). Specifically, the separation unit (30) may include a first separation unit (30a) for separating the alloy (A) and a second separation unit (30b) for separating the first slag (S). For example, the separation unit (30) may be connected to both side walls of the DC electric arc furnace (100), and specifically, the first separation unit (30a) may be connected to one side wall of the DC electric arc furnace (100), and the second separation unit (30b) may be connected to the other side wall opposite to the one side wall.

[0067] The exhaust unit (40) according to the present invention can discharge gas generated in the DC electric arc furnace (100). For example, the exhaust unit (40) can include a hole penetrating a portion of the roof of the DC electric arc furnace.

[0068] The cooling unit (50) according to the present invention can prevent overheating of the direct current electric arc furnace (100) by injecting cooling water or cooling air and induce safe operation at high temperatures.

[0069] For example, the cooling unit (50) may include a first cooling unit (50a) that introduces cooling water into the interior of the DC electric arc furnace (100), and may include a second cooling unit (50b) that introduces cold air into the interior of the DC electric arc furnace (100).

[0070] In some embodiments of the present invention, the arc furnace includes a direct current electric arc furnace (100) equipped with an electrode rod (10), and the electrode rod (10) includes a carbon electrode, and the reduction condition may be implemented by the carbon electrode. According to some embodiments of the present invention, since the electrode rod includes a carbon electrode, the valuable metal can be effectively reduced without adding a separate reducing agent, thereby easily obtaining an alloy to be described later. Accordingly, the cost can be reduced and the process efficiency can be improved, thereby improving the economic feasibility of the process, and at the same time, the recovery rate of lithium can be increased. For example, the carbon electrode may include graphite.

[0071] In some examples, the step (S2) may include a step performed by a direct current electric arc furnace under output conditions of 50 to 3,000 kW. Specifically, by adjusting the output conditions of the step (S2) within the above numerical range, the recovery rate of lithium can be further increased. Specifically, the output conditions of the step (S2) may be appropriately modified depending on the process scale.

[0072] In some examples, the current conditions of the above step (S2) may be appropriately modified depending on the process scale. In one example, the current conditions may be 130 to 150 A.

[0073] (S3) A step of separating the first slag and alloy from the above melt;

[0074] The method for recovering lithium according to the present invention includes a step (S3) of separating the first slag and the alloy from the molten material to separate the first slag containing lithium and the alloy containing the valuable metal.

[0075] Specifically, the above step (S3) may be performed using a tapping process commonly used in the relevant technical field. For example, the separating member (30) or tapping hole commonly used in the relevant technical field may be used as a means to achieve the above step (S3).

[0076] Although FIG. 1 shows two separating parts (30), the technical idea of ​​the present invention is not limited thereto, and the number of separating parts (tapping holes) may be changed to two or more, three or more, or four or more.

[0077] For example, unlike the first slag, the alloy may not contain lithium.

[0078] For example, the composition of the alloy may vary depending on the composition of the lithium-containing waste. In one example, when the lithium-containing waste includes a LiNiCoMn cathode active material, the alloy may include all of Ni, Co, and Mn. In this case, the sum of the total contents of Ni, Co, and Mn based on the total weight of the alloy may be 85 wt% or more, 86 wt% or more, 87 wt% or more, 88 wt% or more, 89 wt% or more, or 90 wt% or more.

[0079] (S4) A step of melting a second mixture including the first slag and the second flux to obtain second slag and fume;

[0080] The method for recovering lithium according to the present invention includes a step (S4) of melting a second mixture containing the first slag and a second flux to obtain second slag and fume, in order to recover lithium from the first slag at a high recovery rate.

[0081] In some embodiments of the present invention, the step (S4) may include a step performed in a furnace different from the arc furnace. According to some embodiments of the present invention, by using a furnace different from the arc furnace, energy efficiency can be improved and the lithium recovery rate can be further increased. Specifically, when the slag separated in the melting step is melted using a furnace different from the arc furnace, the effects of easy furnace replacement and simplified operation can be realized.

[0082] In some examples, various furnaces commercially available in the art may be used as a means for achieving the above step (S4), without particular limitation. Specifically, the furnace may include a holding furnace. For example, the holding furnace may be an electric furnace, a plasma furnace, or a burner-type melting furnace. Specifically, the holding furnace may be any one selected from the group consisting of a direct current electric arc furnace (DC-EAF), an alternating current electric arc furnace (AC-EAF), a plasma arc furnace, and a combination thereof.

[0083] For example, the first slag may be in a molten state or a solidified state (or cooled state) before being fed into the holding furnace.

[0084] In some examples, step (S4) may include melting the second mixture at 1400 to 1700°C for 1 to 3 hours. Specifically, the temperature of step (S4) may be 1500 to 1650°C, or 1600 to 1650°C, and the melting time may be 1 to 2 hours. In some examples, by controlling the melting temperature and melting time within the above numerical ranges, the recovery rate of lithium may be further increased.

[0085] The second flux according to the present invention can lower the melting point of the first slag and control the fluidity of the second mixture, while at the same time acting as a chlorine donor that induces the first slag and the second flux to react and cause LiCl(g) to smoke.

[0086] In some embodiments of the present invention, the second flux may be any one selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, transition metal chlorides, and mixtures thereof, and may be specifically an alkaline earth metal chloride. According to some embodiments of the present invention, when an alkaline earth metal chloride is used as the second flux, the content of lithium fumed as LiCl(g) may be further increased, thereby further increasing the lithium recovery rate.

[0087] For example, the alkali metal chloride may be NaCl or KCl, the alkaline earth metal chloride may be MgCl2 or CaCl2, and the transition metal chloride may be ZnCl2.

[0088] In some embodiments of the present invention, the content of the second flux may be 90 parts by weight or more and 130 parts by weight or less, based on 100 parts by weight of the powder obtained by pulverizing the lithium-containing waste (e.g., calcined black mass). Specifically, the content may be 90 parts by weight or more, 100 parts by weight or more, 110 parts by weight or more, or 115 parts by weight or more, and 120 parts by weight or less, 125 parts by weight or less, or 130 parts by weight or less, based on 100 parts by weight of the powder obtained by pulverizing the lithium-containing waste (e.g., calcined black mass). According to some embodiments of the present invention, by adjusting the content of the second flux within the above numerical range, the fluidity of the second mixture may be adjusted to an appropriate level, thereby further increasing the recovery rate of lithium.

[0089] In some embodiments of the present invention, the content of the second flux may be 70 parts by weight or more and 130 parts by weight or less, based on 100 parts by weight of the first slag. Specifically, the content of the second flux may be 70 parts by weight or more, 80 parts by weight or more, 90 parts by weight or more, 100 parts by weight or more, 110 parts by weight or more, or 115 parts by weight or more, and 120 parts by weight or less or 125 parts by weight or less, based on 100 parts by weight of the first slag. For example, the content of the second flux may be 90 to 130 parts by weight, 100 to 125 parts by weight, 110 to 125 parts by weight, or 115 to 125 parts by weight, based on 100 parts by weight of the first slag. According to some embodiments of the present invention, by controlling the content of the second flux within the above numerical range, the fluidity of the second mixture can be controlled to an appropriate level, thereby further increasing the recovery rate of lithium.

[0090] In this specification, “fume” may include gas (e.g., LiCl(g)) and / or solid particles (e.g., dust) generated during the process of melting the second mixture.

[0091] In some embodiments of the present invention, the fume may include LiCl(g). In some examples, the content of lithium fumed as LiCl(g) may be 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, or 90 wt% or more, based on the total weight of lithium contained in the lithium-containing waste, and specifically any one or more of the plurality of lower limits; and 99 wt% or less or 100 wt% or less.

[0092] In some examples, the content of LiCl(g) contained in the fume may be 90 vol% or more, 91 vol% or more, 92 vol% or more, 93 vol% or more, 94 vol% or more, 95 vol% or more, 96 vol% or more, 97 vol% or more, 98 vol% or more, or 99 vol% or more based on the total volume of the fume, and specifically, any one or more of the plurality of lower limits may be 99.9 vol% or less. For example, the content of LiCl(g) may be analyzed by a gas chromatography method, a combustion ion chromatography (CIC) analysis method, and a combination thereof.

[0093] (S5) Step of separating lithium solution from the above fume

[0094] The method for recovering lithium according to the present invention includes a step of separating a lithium solution from the fume (S5) to extract lithium from the fume.

[0095] In some embodiments of the present invention, the step (S5) may include a step of dissolving the fume in water using a scrubber. For example, the fume may be dissolved in water by a nozzle provided in the scrubber for spraying water, thereby causing a dissolution reaction of LiCl(g) as shown in the following reaction formula 1. For example, the lithium solution may include LiCl(aq).

[0096] [Reaction Formula 1]

[0097] LiCl(g)+H2O(l)->Li + (aq)+Cl - (aq)

[0098] In some embodiments of the present invention, the scrubber may include one or more wet scrubbers. For example, the wet scrubber is not particularly limited, but may include at least one selected from the group consisting of a packed type scrubber, a spray type scrubber, a cyclone scrubber, a venturi scrubber, and an ejector scrubber.

[0099] In some embodiments of the present invention, the scrubber may include two or more interconnected sub-scrubbers. Specifically, using two or more sub-scrubbers can eliminate the need for a dust collector, thereby reducing manufacturing equipment and improving the economic efficiency of the process.

[0100] Hereinafter, a scrubber used in a lithium recovery method according to one embodiment of the present invention will be described with reference to FIG. 2.

[0101] Figure 2 is a schematic diagram of a wet scrubber used in a lithium recovery method according to one embodiment of the present invention.

[0102] Referring to FIG. 2, a wet scrubber (200) according to the present invention may include a first sub-scrubber (200a), a second sub-scrubber (200b), and a connecting portion (200c) connecting the first and second sub-scrubbers (200a, 200b) to each other.

[0103] The first sub-scrubber (200a) according to the present invention may include a first gas inlet (F), a first charge (230a), a first water supply pipe (210a), a first nozzle (210n1), and a first recovery unit (220a).

[0104] The first gas inlet (F) according to the present invention may be an inlet through which the fume is injected. For example, the fume generated during the second melting process may be introduced into the internal space of the first sub-scrubber (200a) through the first gas inlet (F) and transferred to the first charge (230a) described below.

[0105] The first charge (230a) according to the present invention may be a region where a LiCl(aq) and residual gas (R_G) generation reaction occurs by further increasing the contact area between the fume introduced through the first gas inlet (F) and the water sprayed from the first nozzle (210n1) described later. For example, the first charge (230a) may be in the form of a layer or a particle cluster. For example, the first charge (230a) may include at least one selected from the group consisting of ceramic particles, metal materials, and polyolefins. In one example, the metal material may include stainless steel, and the polyolefin may include polypropylene.

[0106] For example, the reaction of the above reaction formula 1 may proceed on the surface of the first charge (230a). As the above reaction formula 1 proceeds on the first charge (230a), LiCl(aq) that is primarily recovered by the first recovery unit (220a) to be described later; and a residual gas (R_G) containing lithium may be generated. At this time, the residual gas (R_G) may be transferred to the second sub-scrubber (200b) through the connection unit (200c) to be described later.

[0107] The first water supply pipe (210a) according to the present invention can supply water to the first nozzle (210n1) described later via a water pump (not shown). For example, the first water supply pipe (210a) can be placed on the first charging material (230a).

[0108] The first nozzle (210n1) according to the present invention can spray water supplied from the first water supply pipe (210a) onto the first charging material (230a). Through this, a reaction can occur on the surface of the first charging material (230a), in which LiCl(g) reacts with water to produce LiCl(aq). For example, the number of the first nozzles (210n1) is not limited to the embodiment illustrated in FIG. 2 and can be modified in various ways.

[0109] The first recovery unit (220a) according to the present invention can primarily recover LiCl(aq) generated from the first charge (230a). For example, the first recovery unit (220a) can be positioned below the first sub-scrubber (200a). The primarily recovered LiCl(aq) can be discharged through the first outlet (L1). For example, the first outlet (L1) can be connected to one side of the first recovery unit (220a).

[0110] The second sub-scrubber (200b) according to the present invention may include a second charging member (230b), a second water supply pipe (210b) for supplying water to a second nozzle (210n2) to be described later, a second nozzle (210n2), and a second recovery unit (220b). The description of the second sub-scrubber overlaps with the description of the first sub-scrubber, and is therefore briefly described or omitted.

[0111] For example, the residual gas (R_G) transferred into the interior of the second sub-scrubber (200b) through the above-mentioned connection portion (200c) can react with water sprayed through the second nozzle (210n2) on the surface of the second charge (230b). Accordingly, the secondarily recovered LiCl(aq) can be recovered through the second recovery portion (220b) and, specifically, can be discharged through the second outlet (L2).

[0112] In some examples, the first charge (230a) may be the same as or different from the second charge (230b).

[0113] In some examples, the wet scrubber (200) may additionally be equipped with equipment for combining the lithium solutions discharged through the first and second outlets (L1, L2).

[0114] In some examples, the recovery solution recovered from the first and second recovery units (220a, 220b) may contain impurities such as fine particles dissolved in water in addition to the lithium solution.

[0115] (S6) Step of concentrating the lithium solution

[0116] The method for recovering lithium according to the present invention may further include a step (S6) of concentrating the lithium solution to recover LiCl containing a high concentration of Li ions. Through this, a high-concentration lithium solution can be obtained.

[0117] In some examples, the concentration of lithium ions in the high-concentration lithium solution may be 10,000 ppm or more, 15,000 ppm or more, 20,000 ppm or more, 25,000 ppm or more, or 30,000 ppm or more. Here, the concentration of lithium ions may be analyzed by an inductively coupled plasma optical emission spectroscopy (ICP-OES) method.

[0118] In some examples, the concentration of chloride ions in the high-concentration lithium solution may be greater than or equal to 170,000 ppm, and specifically greater than or equal to 170,000 ppm and less than or equal to 300,000 ppm. Here, the concentration of chloride ions may be measured according to a combustion ion chromatography (CIC) analysis method.

[0119] For example, a common concentrator commercially available in the relevant technical field may be used as a means for concentrating the lithium solution. Specifically, the concentrator may be a centrifugal vacuum concentrator, a rotary vacuum concentrator, a rotary evaporator, or a centrifugal vacuum concentrator.

[0120] In another embodiment of the present invention, as a method for concentrating the lithium solution, a method of using at least one type of waste heat selected from the group consisting of heat energy generated during the firing process, heat energy generated during the melting process of the arc furnace, heat energy generated during the melting process of the second mixture, heat energy of the first slag, heat energy of the alloy, and heat energy of the second slag may be used. According to another embodiment of the present invention, by using the waste heat, it is possible to reduce carbon dioxide emitted during the process while saving electric energy, thereby lowering the manufacturing cost. For example, in order to use the waste heat, a duct capable of transporting the waste heat may be connected to at least one of each device for achieving steps (S1) to (S4).

[0121] In another embodiment of the present invention, a method of concentrating the lithium solution may be a method of utilizing any one of the electric energy selected from the group consisting of an arc furnace, a holding furnace, and a combination thereof. According to another embodiment of the present invention, by utilizing the electric energy, carbon dioxide emitted during the process can be reduced, while at the same time, electric energy can be saved, thereby lowering the manufacturing cost.

[0122] Figure 3 is a flowchart showing a method for recovering lithium according to one embodiment of the present invention.

[0123] Referring to FIG. 3, a method for recovering lithium according to one embodiment of the present invention may include the steps of (a) preparing black mass by crushing waste lithium-ion batteries; (b) calcining the black mass; (c) mixing the calcined black mass with a first flux to prepare a first mixture; (d) first melting the first mixture in a direct current electric arc furnace under reducing conditions to obtain a melt; (e) tapping the melt to separate the first slag and the alloy; (f) mixing and second melting the first slag with a second flux in a holding furnace; (g) bringing fumes generated in the second melting process into contact with a scrubber to prepare a lithium solution; and (h) concentrating the lithium solution.

[0124] In some embodiments of the present invention, the recovery rate of lithium recovered by the lithium recovery method may be 90% or more, 91% or more, 92% or more, or 93% or more. For example, the lithium recovery rate may be the ratio of the lithium ion content in the concentrated lithium solution to the lithium content in the black mass.

[0125] 2. Lithium compounds

[0126] According to another aspect of the present invention, a lithium compound recovered by a method for recovering lithium according to some embodiments is provided.

[0127] In this specification, the term "lithium compound" may be defined as a compound containing lithium ions, which is a resultant product recovered by a lithium recovery method according to some embodiments or a product using the same. For example, the resultant product recovered by the lithium recovery method may include LiCl(l), and the product may be lithium carbonate (Li2CO3) produced by the reaction of lithium ions with a carbonate or carbon dioxide. In one example, the lithium carbonate may be widely applied in various fields such as electrode materials for lithium ion batteries, electrolyte materials, glass production, and aluminum production.

[0128] In some examples, the purity of the lithium compound may be 90% or greater, 91% or greater, 92% or greater, 93% or greater, 94% or greater, 95% or greater, 96% or greater, 97% or greater, 98% or greater, or 99% or greater, and specifically any one or more of the multiple lower limits may be 99.99% or less.

[0129] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, this is merely an example, and the scope of the present invention is not limited by the following contents.

[0130] As used herein, terms such as "about" or "substantially" mean a reasonable amount of variation from the term that does not significantly alter the final result. These terms may be interpreted to include a variation of at least ±5% or at least ±10%, provided that such variation does not alter the meaning of the term and render it invalid.

[0131] [Manufacturing Example 1: Lithium Recovery Method]

[0132] <Example 1: Method for recovering lithium>

[0133] Steps to prepare black mass by crushing waste lithium-ion batteries:

[0134] Approximately 100 kg of waste lithium-ion batteries were crushed to approximately 100 mesh or less to prepare black mass.

[0135] Steps for calcining the above black mass:

[0136] In an air atmosphere, the black mass was heated from room temperature to about 750°C at a heating rate of about 100°C, and then calcined at about 750°C for 12 hours to remove carbonized substances. The resultant product from which the carbonized substances were removed was sufficiently cooled at room temperature for 240 minutes, thereby producing calcined black mass having the composition shown in Table 1 below. The composition of the calcined black mass was measured using an ICP-OES (Inductively coupled plasma optical emission spectroscopy) device from Perkin Elmer.

[0137] ClassificationNiCoMnLippm295,250128,900102,30064,785

[0138] A step of preparing a first mixture by mixing the above-mentioned calcined black mass and the first flux:

[0139] A first mixture was prepared by mixing about 60 wt% of the calcined black mass, about 7 wt% of Al2O3, about 17 wt% of CaO, and about 16 wt% of SiO2 using a drum mixer for about 1 hour.

[0140] A step of first melting the first mixture in a direct current electric arc furnace under reducing conditions:

[0141] Before the first mixture was introduced, a batch type DC-Electric Arc Furnace (DC-EAF) was preheated to about 1,500°C for about 2 hours. At this time, the output during preheating was about 80 to 100 kW and the input voltage was 130 to 150 V.

[0142] Meanwhile, the direct current electric arc furnace includes an electrode rod equipped with a carbon electrode. Since the carbon electrode reduces the calcined black mass, it is possible to easily produce an alloy, which will be described later, by reducing the valuable metal contained in the calcined black mass without adding a separate reducing agent.

[0143] After the first mixture was introduced through a hopper equipped in the above-described preheated direct current electric arc furnace, primary melting was performed at 1,500°C for 3 hours under an air atmosphere.

[0144] Step of separating the first slag and alloy by tapping the above melt:

[0145] The first molten material was tapped to separate the first slag and the alloy. At this time, the composition of the first slag is as shown in Table 2 below, and the composition of the alloy is as shown in Table 3 below.

[0146] Meanwhile, the compositions described in Tables 2 and 3 below were analyzed using the ICP-OES (Inductively coupled plasma optical emission spectroscopy) method.

[0147] ClassificationNiCoMnLiAlCuSiFeCaMgSUMppm0089,92068,63094,3500124,0000176,6008,180561,680wt%0016.012.216.8022.1031.41.5100

[0148] ClassificationNiCoMnLiAlCuSiFePCaCrSUMppm625,300334,60092,690058361,8003,54927,57011,9407151,9211,160,668wt%53.828.88.000.15.30.32.41.00.10.2100

[0149] Step of mixing and secondary melting the first slag with the second flux in a holding furnace:

[0150] After the first slag was put into a holding furnace different from the DC electric arc furnace, it was secondarily melted at about 1,600°C for 0.5 hours. During the second melting of the first slag, a second flux composed of 100 parts by weight of CaCl2 and 25 parts by weight of SiO2 was put into 100 parts by weight of the first slag to perform a second melting step. As a result, second slag and fume having the compositions shown in Table 4 below were obtained. At this time, the second slag was analyzed by the ICP-OES (Inductively coupled plasma optical emission spectroscopy) method.

[0151] Meanwhile, LiCl (g) contained in the fume was analyzed through a LiCl aqueous solution sample prepared by dissolving the fume in 1 ton of water. Specifically, Li for the sample + It was analyzed to be approximately 1,532 ppm using the ICP-OES (Inductively coupled plasma optical emission spectroscopy) method.

[0152] ClassificationNiCoMnLiAlCuSiFeCaMgSUMppm0031,910083,1300108,4000330,1007,308560,848wt%006%015%019%059%1%100%

[0153] Step of manufacturing a lithium solution by contacting the fume generated in the above secondary melting process with a scrubber:

[0154] The above fume was passed through a two-stage wet scrubber to dissolve Li in water. The fume generated in the second melting process was recovered by suction, and lithium was recovered in the first sub-scrubber. The residual gas that passed through without being captured in the process was recovered by suction in the second sub-scrubber to obtain a lithium solution.

[0155] Step of concentrating the above lithium solution to recover lithium:

[0156] The lithium solution was concentrated and evaporated at 90°C for 5 hours using an evaporator to obtain a high-concentration lithium solution. At this time, the concentration of lithium ions in the high-concentration lithium solution was 20,000 ppm or more based on the ICP-OES (Inductively coupled plasma optical emission spectroscopy) method. In addition, Cl in the high-concentration lithium solution - It was measured to be approximately 172,399 ppm according to the Combustion Ion chromatography (CIC) analysis method.

[0157] [Experimental Example: Measurement of Lithium Recovery Rate and Recovery Time]

[0158] The recovery rate of lithium was calculated according to Equation 1 below.

[0159] [Formula 1]

[0160] Lithium recovery rate (%) = (O L / I L ) x 100

[0161] In the above equation 1, I L is the lithium content in black mass (kg), and O L is the content (kg) of lithium ions in the recovered concentrated lithium solution.

[0162] Example 1 of the first mixture melting method Direct current electric arc Lithium recovery rate (%) 93% Lithium recovery time (unit: hour, time) 24

[0163] Referring to Table 5 above, it was confirmed that when lithium was recovered using the method according to Example 1, the lithium recovery rate was 93% or more, and the lithium recovery time was significantly shortened to 24 hours or less.

[0164] The features described in the above-described embodiment may be combined with other embodiments unless explicitly stated otherwise. Furthermore, while the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art utilizing the basic concepts of the present invention defined in the following claims also fall within the scope of the present invention.

[0165] [Explanation of symbols]

[0166] 100: Direct current electric arc furnace

[0167] 10: Electrode rod

[0168] 20: Lower electrode

[0169] 30: Separation section

[0170] 30a: 1st separation section

[0171] 30b: Second Separation Section

[0172] 40: Exhaust

[0173] 50: Cooling section

[0174] 50a: 1st cooling section

[0175] 50b: Second cooling section

[0176] 200: Wet scrubber

[0177] 200a: 1st sub-scrubber

[0178] F: 1st gas inlet

[0179] 230a: First charge

[0180] 210a: First water supply pipe

[0181] 210n1: Nozzle 1

[0182] 220a: 1st Recovery Unit

[0183] L1: Exit 1

[0184] 200b: Second sub-scrubber

[0185] 230b: Second charge

[0186] 210n2: Second nozzle

[0187] 220b: Second Recovery Unit

[0188] L2: Exit 2

[0189] 200c: Connection

[0190] R_G: Residual gas

Claims

1. (S1) A step of preparing a first mixture including a powder obtained by crushing lithium-containing waste and a first flux; (S2) A step of melting the first mixture in an arc furnace under reducing conditions to produce a melt; (S3) A step of separating the first slag and alloy from the above melt; (S4) a step of melting a second mixture including the first slag and the second flux to obtain second slag and fume; and (S5) A step of separating a lithium solution from the fume; including; Method for recovering lithium.

2. In paragraph 1, The above lithium-containing waste, Comprising at least one selected from the group consisting of waste lithium ion batteries, waste electrodes, and waste positive electrode active materials. Method for recovering lithium.

3. In paragraph 1, The above step (S1) is, Comprising a step of calcining the above powder, Method for recovering lithium.

4. In paragraph 1, The above first flux is, Al2O 3, CaO, SiO2, and Containing at least one selected from the group consisting of Fe2O3, Method for recovering lithium.

5. In paragraph 1, The above first mixture is, Further comprising one additive selected from the group consisting of transition metals, carbonates and mixtures thereof; Method for recovering lithium.

6. In paragraph 1, The above arc furnace is, Any one selected from the group consisting of a DC Electric Arc Furnace (DC-EAF), an AC Electric Arc Furnace (AC-EAF), a Plasma Arc furnace, and combinations thereof. Method for recovering lithium.

7. In paragraph 1, The above arc furnace includes a direct current electric arc furnace equipped with an electrode rod, The above electrode rod includes a carbon electrode, The above reduction conditions are implemented by the carbon electrode. Method for recovering lithium.

8. In paragraph 1, The above step (S2) is, A step performed by a direct current electric arc furnace under output conditions of 50 to 3,000 kW, Method for recovering lithium.

9. In paragraph 1, The above step (S4) is: Comprising a step performed in a furnace different from the above arc furnace, Method for recovering lithium.

10. In paragraph 9, The above step (S4) is: A step of melting the second mixture at 1400 to 1700°C for 1 to 3 hours, Method for recovering lithium.

11. In paragraph 1, The above second flux is, Any one selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, transition metal chlorides and mixtures thereof, Method for recovering lithium.

12. In paragraph 11, The above fume contains LiCl(g). Method for recovering lithium.

13. In paragraph 1, The above step (S5) is: Comprising a step of dissolving the fume in water using a scrubber, The above scrubber comprises one or more wet scrubbers. Method for recovering lithium.

14. In paragraph 1, (S6) further comprising a step of concentrating the lithium solution; Method for recovering lithium.

15. Lithium compound recovered by the lithium recovery method according to Article 1.

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