Lithium compound for valuable metal recovery and method for producing same

Abstract

The present invention relates to a lithium compound for valuable metal recovery and a method for recovering the same. The method for recovering a lithium compound for valuable metal recovery comprises: a step for preparing a battery; freezing and forcibly discharging the battery; a step of crushing the battery; and a step of heating the crushed battery product, the heating step being carried out at a temperature in the range of 1100 to 1400 DEG C, the heating step being carried out at a vacuum degree (LogP [standard atmospheric pressure]) in the range of-4 to 0, the lithium compound recovered by the heating step containing impurities, in wt%, the content of the impurities in the crushed battery product being less than or equal to 1% by weight, and the content of the impurities in the crushed battery product being less than or equal to 1% by weight, and the content of the impurities in the crushed battery product being less than or equal to 1% by weight. The impurities may include 1.8 wt% or less and 0 wt% excluding Na, 0.06 wt% or less and 0 wt% excluding K, 0.62 wt% or less and 0 wt% excluding Ca, and 0.47 wt% or less and 0 wt% excluding Mg.

Description

Technical Field

[0001] The present invention relates to waste batteries, and in particular to a lithium compound for recovering valuable metals recovered from waste batteries and a method for producing the same. Background Art

[0002] As the global demand for electric vehicles grows, how to deal with the waste batteries generated by these vehicles has become a social issue. Lithium secondary batteries, which are the main raw materials of the waste batteries, contain organic solvents, explosive substances and heavy metal substances such as Ni, Co, Mn and Fe, but Ni, Co, Mn and Li are valuable metals with great scarcity value. The recycling and reuse process of discarded lithium secondary batteries has become an important research field.

[0003] Specifically, the lithium secondary battery is mainly composed of copper and aluminum used as collectors, oxides containing Li, Ni, Co, and Mn constituting positive electrode materials, and graphite used as negative electrode materials, and includes a separator for isolating the positive electrode material and the negative electrode material and an electrolyte injected into the separator. The solvent (Solvent) constituting the electrolyte and the solvent used as the salt (Salt) are mainly mixed with carbonate organics such as ethylene carbonate (Ethylene Carbonate) and propylene carbonate (Propylene Carbonate), for example, LiPF6 is used.

[0004] In order to utilize the waste batteries, people are increasingly interested in a waste battery recycling process, in which the waste batteries are crushed to produce intermediate materials such as waste battery crushed materials or black powder, and then valuable metals are recovered through subsequent processes.

[0005] Specifically, the main components of waste batteries are composed of expensive valuable metal elements such as Ni, Co, Mn, and Li. The waste batteries refer to batteries that have reached the end of their service life, such as secondary batteries with a service life of 5 to 10 years. From the perspective of environmental protection and cost, the reuse of the main components of waste batteries is crucial. The waste batteries are subjected to conventional crushing, pulverization or specific gravity screening to produce a mixture of positive and negative electrode materials in the form of black powder as an intermediate product. The valuable metals required for the production of batteries are recovered from the black powder produced in this way through wet processes such as leaching, solvent extraction or crystallization. As a result, the supply of raw materials can be smooth and the cost of battery manufacturing can be greatly reduced.

[0006] In order to reuse the waste batteries, they must be physically disassembled, which is a very dangerous job because of safety issues such as battery explosion or electric shock. After physical disassembly, a hole is drilled in the battery and then discharged in salt water. After the battery is fully discharged, it is broken and then subjected to high-temperature heat treatment to remove water and electrolyte.

[0007] When salt water discharge is performed, the salt used contains a large amount of impurities such as Na, K, Mg, Ca, etc., which exist together with the waste battery. As for Cl, it is removed to a certain extent during the high temperature heat treatment process, but the crushed waste battery or the black powder of the processed crushed waste battery contains impurities Na, K, and Mg.

[0008] At this time, the crushed material is a crushed material obtained by crushing the battery, etc., and the black powder is a powder form in which Al, Cu, and a part of the separator are removed by further processing the crushed material and the oxide of Ni-Co-Mn-Li-O and C are mixed. When the crushed material of the waste battery is subjected to high-temperature heat treatment, oxygen is removed from the oxide to generate an alloy of Ni-Co-Mn-Cu and a lithium-containing compound, carbon, and carbon-containing ash (Ash).

[0009] At this time, since the salt water discharge is carried out in the process of wet processing of lithium-containing compounds, the impurities contained, such as Na, K, Mg, etc., act as impurities during the wet processing, wherein Na, K, Mg, and Ca cause process loads when passing through processes such as causticization (NaOH) used in wet recovery of Li, thereby increasing the processing time and cost. In addition, for Cl, the corrosion of the pipeline for processing chloride ions increases, thereby increasing the equipment cost and equipment maintenance cost. Summary of the invention

[0010] Technical issues to be solved

[0011] According to an embodiment of the present invention, the lithium compound for valuable metal recovery increases the operating efficiency of the wet process, reduces equipment maintenance costs, and provides a lithium compound component with a low impurity content.

[0012] A method for producing a lithium compound for valuable metal recovery according to another embodiment of the present invention provides a method for producing a lithium compound having the aforementioned advantages.

[0013] Technical Solution

[0014] According to one embodiment of the present invention, a lithium compound as a lithium compound for recovering valuable metals recovered from waste batteries comprises Li, Al and impurities, wherein, in terms of weight %, the impurities comprise Na: 1.8 wt % or less and excluding 0 wt %, K: 0.06 wt % or less and excluding 0 wt %, Ca: 0.62 wt % or less and excluding 0 wt % and Mg: 0.47 wt % or less and excluding 0 wt %, and the lithium compound may satisfy the following formula 1.

[0015] <Formula 1>

[0016] <al> / ≤1.30

[0017] <al>and< / al> Each represents the molar number of Al and Li.

[0018] In one embodiment, the lithium compound may satisfy Formula 2 below.

[0019] <Formula 2>

[0020] ([Na]+[K]+[Mg]) / [Ca]≤3.6

[0021] [Na], [K], [Mg] and [Ca] each represent the weight % of Na, K, Mg and Ca.

[0022] In one embodiment, the lithium compound may satisfy Formula 3 below.

[0023] <Formula 3>

[0024] <al> ＝0.3702×< / al> +0.0832±0.5

[0025] <al> and< / al> Each represents the mole number (Moles) of Al and Li.

[0026] According to another embodiment of the present invention, a method for recovering lithium compounds for valuable metal recovery comprises: a step of preparing a battery; a step of freezing and forcibly discharging the battery; a step of crushing the battery; and a step of heating the crushed battery fragments, wherein the heating step is carried out at a temperature range of 1100 to 1400° C., and the heating step is carried out at a vacuum degree (LogP [standard atmospheric pressure]) in the range of -4 to 0, and the lithium compound recovered by the heating step contains impurities, which may include, in weight %, Na: 1.8 wt % or less and excluding 0 wt %, K: 0.06 wt % or less and excluding 0 wt %, Ca: 0.62 wt % or less and excluding 0 wt % and Mg: 0.47 wt % or less and excluding 0 wt %.

[0027] In one embodiment, the lithium compound recovered through the heating step may contain 13.0 wt % or more of lithium in terms of weight %.

[0028] In one embodiment, the method for recovering lithium compounds for valuable metal recovery may satisfy the following formula 2.

[0029] <Formula 2>

[0030] ([Na]+[K]+[Mg]) / [Ca]≤3.6

[0031] [Na], [K], [Mg] and [Ca] each represent the weight % of Na, K, Mg and Ca.

[0032] In one embodiment, the step of heating the broken battery fragments can be performed in an environment of at least one of an inert gas, carbon dioxide, carbon monoxide and a hydrocarbon gas. In one embodiment, the step of freezing and forcibly discharging the battery can be performed by cooling to -150 to -60°C.

[0033] In one embodiment, the steps of freezing and forcibly discharging the battery may be performed by cooling to -60 to -20° C. under a vacuum environment condition of less than 1000 Torr.

[0034] In one embodiment, the steps of freezing and forcibly discharging the battery may satisfy the following formula 4.

[0035] <Formula 4>

[0036] Minimum cooling time (Hr) = A × (W0.33)

[0037] A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

[0038] In one embodiment, the steps of freezing and force-discharging the battery may include force-discharging at a discharge rate of less than 0.04 V / min.

[0039] Beneficial Effects

[0040] According to a lithium compound for valuable metal recovery according to an embodiment of the present invention, in a valuable metal recovery method, a lithium compound component with low impurity content such as Na, K, Mg and Ca is provided by controlling temperature and pressure in a heat treatment step, thereby suppressing the problem of load caused by an additional process for impurity removal, increasing the lithium recovery rate in a wet recovery process, and providing economic benefits for valuable metal recovery.

[0041] According to another embodiment of the present invention, a method for producing a lithium compound for valuable metal recovery provides a valuable metal recovery method for producing a lithium compound having the aforementioned advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a graph regarding the minimum cooling time according to an embodiment of the present invention.

[0043] Figure 2 is a graph showing the relationship among battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0044] Figure 3a and Figure 3b is a photograph showing a fire that occurred when a comparative example of the present invention was broken after being frozen (the time is shorter than the minimum cooling time), Figure 3c and Figure 3d This is a photograph of an embodiment according to the present invention in which no fire occurred when the sample was crushed after being frozen (for a period longer than the minimum cooling time).

[0045] Figure 4 is a photograph evaluating the amount of expansion according to the discharge speed of a battery cell according to one embodiment of the present invention.

[0046] Figure 5 FIG. 1 shows the XRD analysis result of the lithium compound generated after high temperature heat treatment according to one embodiment of the present invention.

[0047] Figures 6a to 6d is a graph showing the correlation between temperature and pressure for removing impurities according to one embodiment of the present invention. DETAILED DESCRIPTION

[0048] The words first, second, third, etc. are used to describe various parts, components, regions, layers and / or segments, but these parts, components, regions, layers and / or segments should not be limited by these words. These words are only used to distinguish a certain part, component, region, layer or segment from another part, component, region, layer or segment. Therefore, without departing from the scope of the present invention, the first part, component, region, layer or segment described below can also be described as the second part, component, region, layer or segment.

[0049] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. Unless the context otherwise clearly indicates the opposite, the singular form used herein is also intended to include the plural form. "Including" used in the specification may specifically refer to a certain characteristic, field, integer, step, action, element and / or component, but does not exclude the existence or addition of other characteristics, fields, integers, steps, actions, elements and / or components.

[0050] If a part is described as being on another part, it may be directly on the other part or there may be other parts therebetween. When a part is described as being directly on another part, there may be no other parts therebetween.

[0051] Although not otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. Terms defined in dictionaries should be interpreted as having the same meaning as that disclosed in the relevant technical literature and this article, and should not be interpreted in an idealized or overly formal sense.

[0052] Hereinafter, embodiments of the present invention will be described in detail. However, the following embodiments are given only as examples, and the present invention is not limited to the following embodiments, and the present invention is subject only to the scope of the claims.

[0053] According to an embodiment of the present invention, the lithium compound for valuable metal recovery as the lithium compound for valuable metal recovery recovered from waste batteries comprises Li, Al and impurities, wherein the impurities may comprise Na, K, Ca and Mg.

[0054] In one embodiment, the lithium compound for valuable metal recovery may satisfy the following Formula 1.

[0055] <Formula 1>

[0056] <al> / < / al> ≤1.30

[0057] <al> and< / al> Each represents the molar number of Al and Li.

[0058] The above formula 1 represents the molar ratio of aluminum to lithium. The above formula 1 can satisfy less than 1.30, specifically less than 0.61. By satisfying the above formula 1, lithium is recovered in the form of aluminates such as stable LiAlO2 or Li5AlO4, thereby having the advantage of minimizing the deviation of lithium recovery rate. If the above formula 1 does not satisfy the aforementioned range, lithium is recovered in the form of aluminum oxides such as Al2O3, rather than in the form of aluminates, and there is a problem of increased process cost for removing Al impurities.

[0059] In one embodiment, the lithium compound may satisfy Formula 2 below.

[0060] <Formula 2>

[0061] ([Na]+[K]+[Mg]) / [Ca]≤3.6

[0062] [Na], [K], [Mg] and [Ca] each represent the weight % of Na, K, Mg and Ca.

[0063] The above formula 2 is a relational expression about the content ratio of impurities, which can be used as a standard for measuring the impurity removal concentration. Specifically, in the above formula 2, Na and K are relatively easy to remove impurities, while Mg and Ca are removed only when the temperature becomes higher and the vacuum degree decreases at the same time. Therefore, the above formula 2 can be used to measure whether the impurities (specifically Na and K) are fully removed.

[0064] The above formula 2 may satisfy a range of 3.6 or less, specifically 2.0 to 3.6, and more specifically 2.2 to 3.2. If the above formula 2 exceeds the above range, there is a problem that impurities cannot be properly removed.

[0065] In one embodiment, the lithium compound may satisfy Formula 3 below.

[0066] <Formula 3>

[0067] <al> ＝0.3702×< / al> +0.0832±0.5

[0068] <al> and< / al> Each represents the mole number (Moles) of Al and Li.

[0069] It is confirmed by the above formula 3 that elements with strong oxidizing power at high temperature, such as Li and Al, generate reaction products such as LiAlO2 or Li5AlO4 that are stable at high temperature. As described above, when subjected to high temperature heat treatment, the reaction between the Al cover or Al current collector of the LiB battery and the Li in the positive electrode material occurs stably according to the above relationship, and by satisfying the above formula 3, there is an advantage of being able to improve the lithium recovery rate.

[0070] According to another embodiment of the present invention, a method for recovering lithium compounds for valuable metal recovery includes: preparing a battery; freezing and forcibly discharging the battery; crushing the battery; and heating the crushed battery. By heating the crushed battery, various forms of lithium compounds can be generated or recovered from lithium oxide (Li2O) contained in the positive electrode material.

[0071] The step of preparing the battery is a step of preparing by crushing the material that serves as the base material of the battery crushed product or preparing the crushed material itself. The base material of the battery crushed product may include batteries that have reached the end of their life, waste batteries, and waste materials generated in the manufacturing process of lithium-ion batteries. Specifically, the waste batteries may include positive electrode materials such as scrap, jelly rolls and slurries that constitute waste batteries, defective products generated in the manufacturing process, residues in the manufacturing process, and debris generated. The crushed material itself may be the crushed product itself such as black powder. As described above, the battery crushed product is manufactured by recycling waste batteries, which has environmental and economic advantages.

[0072] In one embodiment, the steps of freezing and forcibly discharging the battery can be implemented by cooling to a temperature in the range of -150 to -60° C. If the upper limit of the temperature range is exceeded, the residual voltage inside the battery will not drop to 0 V, a battery reaction caused by a short circuit may occur, and the electrolyte may not be completely frozen.

[0073] In one embodiment, the steps of freezing and forcibly discharging the battery can be implemented by cooling to -60 to -20°C under vacuum conditions of less than 1000 Torr. The steps of freezing and forcibly discharging the battery are implemented at a temperature sufficient to freeze the electrolyte contained in the battery. Specifically, for example, the steps of freezing and forcibly discharging the battery can be performed at a temperature range of -150 to -20°C. More specifically, the temperature range is -150 to -50°C, and more specifically, it can be a temperature range of -80 to -60°C.

[0074] If the battery is frozen in the temperature range, the residual voltage inside the battery (e.g., about 2V to 3V) drops to nearly 0V, so even if a short circuit occurs where the positive and negative electrodes are in direct contact, a battery reaction does not occur, and the battery temperature does not increase, thereby preventing the generation of electrolyte gas and combustion. In addition, since the electrolyte is in a frozen state or a state where gasification is suppressed, the mobility of lithium ions is very low, and the power-on characteristics based on the migration of lithium ions can be significantly reduced. Since gasification of the electrolyte does not occur, the generation of combustible gases such as ethylene, propylene, and hydrogen can be avoided.

[0075] If the freezing process exceeds the temperature range, for example, cooling to a temperature higher than -60°C, the residual voltage inside the battery will not drop to 0V, a battery reaction caused by a short circuit may occur, and the electrolyte will not be completely frozen, so it is not suitable. In addition, when cooled to -150°C, the electrolyte will be fully frozen and the internal voltage of the battery will also drop to 0V, so there is no need to lower the temperature. As described above, the battery processing method has the following advantages: before crushing a battery such as a lithium secondary battery, a freezing step is included, thereby preventing the risk of fire that may occur in the battery crushing process.

[0076] In one embodiment, the steps of freezing and forcibly discharging the battery can be performed under the condition of supplying an inert gas, carbon dioxide, nitrogen, water or a combination thereof or under a vacuum environment of less than 100 Torr. For example, when the process of freezing the battery is performed by cooling to a temperature range of -60 to -20°C, if it is performed under the aforementioned conditions, the electrolyte can be prevented from reacting with oxygen by suppressing the supply of oxygen, and the explosion caused can be prevented, and the gasification of the electrolyte can be suppressed, thereby avoiding the generation of flammable gases such as ethylene, propylene or hydrogen.

[0077] In one embodiment, the steps of freezing and forcibly discharging the battery may satisfy the following formula 4.

[0078] <Formula 4>

[0079] Minimum cooling time (Hr) = A × (W 0.33 )

[0080] A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

[0081] W in the above formula 4 represents the weight of the battery, for example, the weight of a battery pack, a single battery or a combination thereof. The minimum cooling time represents the time required for cooling the electrolyte in the battery to a target temperature by a cooling temperature (ie, an external cooling temperature) applied to the battery.

[0082] The steps of freezing and forcibly discharging the battery are performed for more than the minimum cooling time, so that the electrolyte inside the battery is cooled, which has the advantage that subsequent processes can be performed stably. In the steps of freezing and forcibly discharging the battery, if the freezing time of the battery is less than the minimum cooling time, the electrolyte will not be cooled, and there is a risk of fire when it is broken.

[0083] In one embodiment, the step of freezing and forcibly discharging the battery may be performed at a discharge rate of less than 0.04 V / min. Specifically, the forced discharge may be performed at a discharge rate of 0.03 V / min. If the discharge rate range is exceeded, the expansion amount of the battery becomes high, and there is a problem of decreased stability.

[0084] The step of crushing the battery may refer to a process of applying an impact or compressive force to the battery to cause a portion of the battery to fall off. In one embodiment, the step of crushing the battery may refer to a process of crushing the battery, a process of cutting the battery, a process of compressing the battery, and a combination thereof. Specifically, the crushing step may include all processes that can destroy the battery to obtain small-sized crushed objects.

[0085] In one embodiment, the step of crushing the battery may include all processes of compressing the frozen and discharged battery or applying external force such as shear force or tensile force to destroy the battery. For example, the step of crushing the battery may be implemented using a crusher.

[0086] In one embodiment, the step of crushing the battery can be performed at least once. Specifically, the crushing step can be performed continuously or discontinuously at least once.

[0087] In one embodiment, the step of crushing the battery can be implemented until the maximum size of the battery crushed object is less than 100 mm. Specifically, it can be implemented until the size of the battery crushed object is less than 50 mm. If the maximum size of the battery crushed object is more than 100 mm, as the battery crushed object is crushed, the heat temperature caused by instability will rise to the average vaporization temperature of the electrolyte (i.e., the temperature range of 120°C), thereby causing stability problems such as fire.

[0088] In the step of heating the crushed battery fragments, the battery fragments are placed in a heating furnace that can be heated to a high temperature, so that the crushed fragments can be heated to a temperature above the melting point. Specifically, the step of heating the crushed fragments can be accompanied by a heat treatment condition for a high-temperature reduction reaction without going through a melting step.

[0089] In one embodiment, the step of heating the crushed battery fragments may be performed at a temperature ranging from 1100 to 1400° C. Specifically, the temperature may be in the range of 1200 to 1400° C.

[0090] In the temperature range, carbon in the battery crushed material is burned to a minimum, so that the reduction reaction can be performed in a state where almost no carbon dioxide is generated. If the temperature range exceeds the upper limit of the range, there is a problem of loss due to lithium gasification. If the temperature range exceeds the lower limit of the range, there is a problem that the sintering and reduction of the alloy elements cannot be performed.

[0091] In one embodiment, the step of heating the crushed battery fragments can be performed under a vacuum degree (LogP [standard atmospheric pressure]) ranging from -4.0 to 0. Specifically, the vacuum degree is -4.0 to -1.0, and more specifically, -3.6 to -1.0. The vacuum degree represents a value obtained by logarithmizing the pressure (Pressure, P) in the heating furnace.

[0092] If the battery crushed material is heated within the range of the vacuum degree satisfying the above range, there is an advantage that the concentration of impurities Na, K, Ca and Mg is reduced. If the vacuum degree exceeds the upper limit of the above range, Na, K, Ca and Mg are not vaporized, so there is a problem that the impurities are not removed. If the vacuum degree exceeds the lower limit of the above range, there is a problem that Li is vaporized, resulting in a decrease in the actual yield of Li.

[0093] In one embodiment, the step of heating the crushed battery fragments can be performed in a gas environment of at least one of an inert gas, carbon dioxide, carbon monoxide, and a hydrocarbon gas. The inert gas can, for example, include at least one of argon and nitrogen. By heating the battery fragments in the gas environment, a compound containing lithium contained in the battery fragments can be generated, thereby enabling effective recovery of lithium.

[0094] In one embodiment, the lithium compound recovered by the heating step may include at least any one of lithium aluminate (LiAlO2), lithium carbonate (LiCO3), lithium fluoride (LiF) and lithium chloride (LiCl). Specifically, the lithium aluminate, the lithium carbonate and the lithium fluoride may be produced by the following reaction formulas 1 to 3.

[0095] [Reaction 1]

[0096] Li2O(s)+AlO3(s)=2LiAlO2(s)

[0097] [Reaction 2]

[0098] Li2O(s)+C(s)+O2(g)=Li2CO3(s)

[0099] [Reaction 3]

[0100] Li2O+2F=2LiF+1 / 2O2(g)

[0101] As shown in the reaction formulas 1 to 3, Li2O in the positive electrode material can generate LiAlO2 through the collector Al or Al cover material, or can generate Li2CO3 through the combination of the negative electrode material carbon and the positive electrode material oxygen or oxygen in the atmosphere, and Li2O can generate LiF by reacting with the fluorine contained in the electrolyte. Due to the active generation of the lithium compound, the content of impurities such as Na, K, Ca, and Mg will be reduced. Specifically, the impurities can be in a state of being dissolved in a small amount in the crystalline phase of the lithium compound.

[0102] In one embodiment, the lithium compound contains impurities, and the impurities may include, in weight %, Na: 1.8 wt % or less and excluding 0 wt %, K: 0.06 wt % or less and excluding 0 wt %, Ca: 0.62 wt % or less and excluding 0 wt %, and Mg: 0.47 wt % or less and excluding 0 wt %.

[0103] The reasons for limiting the content of the impurities are described below.

[0104] Na: 1.8 wt% or less, excluding 0%

[0105] As for sodium (Na), in the subsequent process of recovering valuable metals from the battery crushed material, sodium as part of the same group element reacts in place of lithium in the lithium hydroxide formation process to form sodium hydroxide, thereby reducing lithium recovery or causing a side effect of cost increase in the causticization process. For the lithium compound, the sodium may be contained at 1.8 wt % or less. Specifically, the sodium may be contained at 1.0 wt % or less, and more specifically, may be contained at 0.3 wt % or less.

[0106] If the sodium content is more than the above range, Na, as a Group 1 element like Li, has a problem of reduced yield in the process required for producing lithium carbonate during the crystallization of Li dissolved in the solvent after the leaching process and the solvent extraction process.

[0107] Ca: 0.62 wt% or less, excluding 0%

[0108] Like sodium, calcium (Ca) is an element that reduces the recovery rate of valuable metals in the subsequent process of recovering valuable metals from the battery crushed product. For the lithium compound, the calcium may be contained at 0.62 wt % or less. Specifically, the calcium may be contained at 0.61 wt % or less, and more specifically, may be contained at 0.3 wt % or less.

[0109] If the calcium content is more than the above range, there is a problem of increased yield and process time in the solid-liquid separation process as an impurity purification process after the leaching process. In addition, if the calcium content is too much, when the precursor nickel, cobalt, manganese hydroxide and lithium hydroxide are synthesized to generate the positive electrode material, Li[NiCoMn] 1-x Ca x )]O2, the potassium constitutes the oxide structure of the positive electrode material, hindering the migration of lithium ions, thereby causing the problem of reduced battery capacity.

[0110] Mg: 0.47 wt% or less

[0111] Magnesium (Mg) is an element that makes it difficult to separate the solid phase and the liquid phase during acid leaching in the valuable metal recovery process. For the lithium compound, the magnesium may be contained in an amount of 0.47 wt % or less, specifically 0.46 wt % or less, and more specifically 0.3 wt % or less.

[0112] If the magnesium content exceeds the above range, there is a problem that the recovery process of nickel, cobalt, lithium, etc. is burdened. In addition, if the magnesium content is too high, when the positive electrode material is synthesized with nickel, cobalt, manganese hydroxide and lithium hydroxide in the precursor state, Li[NiCoMn] 1-x Mg x )]O2, due to the formation of the oxide structure of the positive electrode material, the migration of lithium ions is hindered, resulting in the problem of reduced battery capacity.

[0113] K: 0.06 wt% or less

[0114] Potassium (K) is also a homologue of lithium and hinders the formation of lithium into hydroxide. For the lithium compound, the potassium may be contained in an amount of 0.06 wt % or less, specifically 0.05 wt % or less, and more specifically 0.01 wt % or less.

[0115] If the potassium content exceeds the above range, a burden is imposed on the causticizing process, and there is a problem in that the recovery rate of lithium decreases.

[0116] The preferred embodiments and comparative examples of the present invention are described below. However, the following embodiment is only a preferred embodiment of the present invention, and the present invention is not limited to the following embodiment.

[0117] <Experimental example>

[0118] <Battery internal temperature based on minimum freezing time>

[0119] In the absence of freezing, the battery pack used in the embodiment is crushed using the same crusher as in the embodiment. Figure 3a and Figure 3b As shown, a short circuit caused a flame during the crushing process.

[0120] As described above, it can be confirmed through the Examples and Comparative Examples that, since the step of freezing the battery pack including the battery before the battery crushing is included, short circuit and flame will not occur during the battery crushing step, and excellent stability is achieved.

[0121] Figure 1 FIG. 1 shows a battery voltage change based on cooling temperature according to an embodiment of the present invention.

[0122] Reference Figure 1 It was confirmed that when the battery was frozen to -80°C and the battery voltage was measured, the battery pack showed almost the same voltage at a high temperature of about 40°C, room temperature, and -60°C, so the battery characteristics were not lost. Then, if the temperature dropped from -60°C to -70°C, the voltage dropped rapidly, and it was confirmed that the voltage reached 0 at -70°C. As mentioned above, if the battery is frozen to -60 to -150°C, short circuit will not occur.

[0123] Figure 2 is a graph showing the relationship among battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0124] Reference Figure 2 It can be confirmed that according to the battery processing method of one embodiment of the present invention, the minimum cooling time for cooling the battery in the step of freezing the battery can be derived. Specifically, it can be confirmed that the minimum cooling time is related to the battery weight, the external cooling temperature and the target temperature. Specifically, the figure shows the external cooling temperature and the minimum cooling time when the target temperature is set to -70°C and the battery weights are 2.5kg (A), 10kg (B), 20kg (C) and 50kg (D), respectively. When cooling the battery, after a predetermined time, it can be confirmed that the electrolyte of the battery begins to cool and the voltage becomes 0. It can be confirmed that when cooling the battery, a minimum holding time is required to fully cool the inside (specifically the electrolyte).

[0125] Specifically, it can be confirmed that in the heat transfer condition for cooling (heat is taken to the outside), if the specific heat of the battery itself is taken into account, the battery weight and the time required for cooling are required. As described above, in the present invention, in order to cool the battery, the minimum time required for cooling can be confirmed using the external cooling temperature and target temperature for freezing and the battery weight.

[0126] The following Table 1 shows the minimum cooling time based on the battery weight and the external cooling temperature.

[0127]

Table 1

[0128]

[0129]

[0130] From Table 1 above, it can be confirmed that the smaller the battery weight, the shorter the minimum cooling time required for the battery to be cooled. In addition, when cooling is performed with the minimum cooling time derived from the relationship between the battery weight, the external cooling temperature and the target temperature, it can be confirmed that the battery is cooled, specifically, the electrolyte of the battery is cooled. In addition, when the battery is cooled for more than the minimum cooling time, a fire will not occur in the battery crushing process in the subsequent process. Figure 3a and Figure 3b is a photograph showing a fire that occurred when a comparative example of the present invention was broken after being frozen (the time is shorter than the minimum cooling time), Figure 3c and Figure 3d This is a photograph of an embodiment according to the present invention in which no fire occurred when the sample was crushed after being frozen (for a period longer than the minimum cooling time).

[0131] Reference Figure 3a and Figure 3b , the experiment was conducted to investigate the fire state of the broken objects when the freezing time during battery cooling was less than the minimum required cooling time. In the experiment, when the battery weight was 25kg, the external cooling temperature was -95°C, and the target freezing temperature was -70°C, if the value of the following formula 4 was 7 hours, the experiment was conducted for 5 hours, which was less than the value of the above formula 4.

[0132] <Formula 4>

[0133] Minimum cooling time = A × (W 0.33 )

[0134] A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

[0135] Reference Figure 3c and Figure 3d The experiment tested the fire state of the broken objects when the battery was frozen for more than the minimum freezing time required for battery cooling. In the experiment, the battery weight, external cooling temperature and Figure 3a and Figure 3b Similarly, the minimum freezing time is more than 7 hours.

[0136] Table 2 below compares Figure 3a to Figure 3d The fire occurrence status of the embodiment and the comparative example based on the same battery weight, external cooling temperature and minimum freezing time. For the judgment of the fire occurrence status, if a fire is observed after the battery is crushed, it is represented as "O", and if a fire is not observed, it is represented as "X".

[0137]

Table 2

[0138]

[0139] From Table 2 above, it can be confirmed that if the battery cooling time is less than the value of Formula 4 (equivalent to the minimum cooling time), the electrolyte will not be cooled, and a fire will occur after the battery is broken. As mentioned above, if the battery is cooled with the value of Formula 4 as the minimum cooling time, the broken materials can be stably used after the battery is broken, and a fire will not occur.

[0140] <Forced Discharge>

[0141] When discharging is performed to force discharge, the discharge is performed to near 0V, and the discharge rate (V / minute) is less than 5V per minute for each battery pack. Generally, the battery of each battery pack has a voltage of about 500V, but it varies depending on the charging state and the number of times used and the condition of the vehicle. Therefore, the battery cell, which is the smallest unit in the battery, is tested, and the battery cell has a maximum voltage of 4.2V.

[0142] Table 3 below shows the behavior of the amount of expansion of a single cell according to the discharge rate and temperature.

[0143]

Table 3

[0144]

[0145] Figure 4 is an evaluation photograph of the expansion amount according to the discharge speed of the battery cell according to one embodiment of the present invention. Figure 4 It was confirmed that if the battery cell is discharged at a rate of 0.04 V / min or more during forced discharge, the chemical structure in the battery will rapidly decompose and the battery will become extremely unstable, and the amount of expansion will increase due to the gasification of the positive electrode material and electrolyte inside the battery.

[0146] <Comparison of impurity components in battery crushed materials according to discharge method>

[0147] Table 4 below compares the impurity components such as Na, K, Mg and Ca in the battery crushed products produced by crushing the batteries after salt water discharge and the battery crushed products produced after forced discharge and frozen crushing.

[0148]

Table 4

[0149] Classification Na[%] K[％] Mg[%] Ca[%] Remark Salt water discharge 0.830 0.027 0.049 0.034 Comparative Example Forced discharge & frozen crushing 0.054 0.0065 0.0101 0.02 Example

[0150] From the above Table 4, it can be confirmed that when freeze crushing and electrical forced discharge are performed, the contents of impurity components Na, K, Mg and Ca are lower than those of brine discharge.

[0151] <Comparison of the composition and content of lithium compounds generated after high-temperature heat treatment>

[0152] Table 5 below shows the components and contents of the products and lithium compounds generated when the crushed materials of the examples containing impurities in Table 4 above are subjected to high-temperature heat treatment at 1300°C.

[0153]

Table 5

[0154]

[0155] From Table 5 above, it is confirmed that the impurity components Na, K, Mg, and Ca of the frozen crushed material are enriched to about 800%. This is because the weight of the lithium compound generated after high-temperature heat treatment is reduced to 6% relative to the weight of 100g of the crushed material. In addition, for the lithium compound generated by external force, the content of the impurities Na, K, Mg, and Ca can be controlled within 0.3%, 0.1%, 0.3%, and 0.5%, respectively. Figure 5 FIG. 1 shows the XRD analysis result of the lithium compound generated after high temperature heat treatment according to one embodiment of the present invention.

[0156] from Figure 5 It was confirmed that no crystalline phase containing impurities Na, K, Ca, and Mg was observed. Specifically, the impurities were dissolved in a small amount in the majority crystalline phase LiAlO2, Li2CO3, or LiF.

[0157] Specifically, for LiAlO2 compositions, at least one of 20.5 to 21.5°, 29.0 to 29.5°, 31.5 to 32.0°, 32.2 to 33.0°, 60.5 to 61.5°, and 70.0 to 72.0° may be included as XRD peaks. For Li5AlO4 compositions, at least one of 19.5 to 20.2° and 21.6 to 22.2° may be included as XRD peaks. For LiF compositions, at least one of 37.5 to 40.2°, 43.9 to 46.5°, and 64.5 to 66.5° may be included as XRD peaks. For Li2CO3 compositions, at least one of 24.0 to 26.0°, 27.0 to 29.0°, 34.0 to 36.0°, and 37.0 to 39.0° may be included as XRD peaks.

[0158] Table 6 below compares the composition of the alloy and lithium compound after high temperature heat treatment and separation by external force.

[0159]

Table 6

[0160]

[0161] It can be confirmed from Table 6 above that the impurity content in the lithium compound after high-temperature heat treatment after brine discharge is about 2 to 11 times higher than that after freeze crushing. If the brine is subjected to high-temperature heat treatment after discharge, the impurity content is high. In order to recover lithium in the wet process, a process for removing impurities may be added, which may cause a problem of process load. Therefore, after performing ultra-low temperature freeze crushing and forced discharge, by performing high-temperature heat treatment, the impurity components Na, K, Mg and Ca can be controlled to within 0.3%, 0.1%, 0.3%, and 0.5%, respectively.

[0162] <Impurity Control Based on Temperature and Vacuum Degree in High-Temperature Heat Treatment Step>

[0163] Figures 6a to 6d is a graph showing the correlation between temperature and pressure for removing impurities according to one embodiment of the present invention.

[0164] Reference Figures 6a to 6d , Figures 6a to 6d Graph showing the correlation between temperature and pressure for removing impurities Na, K, Ca and Mg, respectively. Specifically, for impurities such as Ca, Mg, Na, K, etc., which are volatile substances, by adjusting the temperature and vacuum degree, the volatilization reaction of Li can be suppressed while being removed. The temperature can be adjusted within the temperature range of 300 to 1400°C, and the vacuum degree logP (standard atmospheric pressure) can be adjusted within the range of -4 to 0.

[0165] When crushed materials or black mass of LiB batteries are placed in a high-temperature heat treatment reactor in a state where the impurities are high in content, Na, K, Ca, and Mg can be removed according to the following reaction formula.

[0166] Specifically, the volatilization conditions of Na, K, Ca, and Mg are shown in the following reaction formulas 1 to 4.

[0167] [Reaction 1]

[0168] Na volatilization conditions: reaction temperature = 94.58 × logP (standard atmospheric pressure) + 801.28

[0169] [Reaction 2]

[0170] K volatilization conditions: reaction temperature = 68.425 × logP (standard atmospheric pressure) + 623.35

[0171] [Reaction 3]

[0172] Ca volatilization conditions: reaction temperature = 119.26 × logP (standard atmospheric pressure) + 1557.9

[0173] [Reaction 4]

[0174] Mg volatilization conditions: reaction temperature = 140.25×logP (standard atmospheric pressure) + 1805.1 The following Table 7 shows the changes in Na, K, Ca, and Mg components after high-temperature heat treatment based on temperature and vacuum degree.

[0175]

Table 7

[0176]

[0177]

[0178]

[0179] From Table 7 above, it is confirmed that when the temperature is as low as 1000°C, even if the vacuum degree is reduced, there is a problem that Ca, Mg, Na, and K are not sufficiently removed. In addition, when the temperature is 1100 to 1400°C, if the vacuum degree is as low as -5, Li will be lost. In addition, when the temperature is 1500°C, which is higher than 1400°C, Li loss occurs at a vacuum degree of -3, and poor operability is shown at high temperatures.

[0180] The preferred embodiments are described in detail above, but the scope of the present invention is not limited to the above embodiments. Various modifications and improvements made by those skilled in the art using the basic concepts defined in the claims also fall within the scope of the present invention. < / al>

Claims

1. A lithium compound comprising Li, Al and impurities as a lithium compound for valuable metal recovery recovered from waste batteries, In terms of weight %, the impurities include Na: 1.8 wt % or less and excluding 0 wt %, K: 0.06 wt % or less and excluding 0 wt %, Ca: 0.62 wt % or less and excluding 0 wt % and Mg: 0.47 wt % or less and excluding 0 wt %, The lithium compound satisfies the following formula 1, <Formula 1> <al> / ≤1.30 < / al> <al>and Each represents the molar number of Al and Li. < / al> 2. The lithium compound according to claim 1, wherein The lithium compound satisfies the following formula 2, <Formula 2> ([Na]+[K]+[Mg]) / [Ca]≤3.6 [Na], [K], [Mg] and [Ca] each represent the weight % of Na, K, Mg and Ca.

3. The lithium compound according to claim 1, wherein The lithium compound satisfies the following formula 3, <Formula 3> <al> ＝0.3702× +0.0832±0.5 < / al> <al>and Each represents the molar number of Al and Li. < / al> 4. A method for recovering a lithium compound for valuable metal recovery, comprising: Steps to prepare the battery; The steps of freezing and forcibly discharging the battery; a step of crushing the battery; and The step of heating the broken battery fragments, The heating step is performed at a temperature ranging from 1100 to 1400° C., The heating step is carried out under a vacuum degree (LogP [standard atmospheric pressure]) in the range of -4 to 0, The lithium compound recovered by the heating step contains impurities, which, in terms of weight %, include Na: 1.8 wt % or less and excluding 0 wt %, K: 0.06 wt % or less and excluding 0 wt %, Ca: 0.62 wt % or less and excluding 0 wt % and Mg: 0.47 wt % or less and excluding 0 wt %.

5. The method for recovering lithium compounds for valuable metal recovery according to claim 4, wherein: The lithium compound recovered through the heating step contains 13.0 wt % or more of lithium in terms of weight %.

6. The method for recovering lithium compounds for valuable metal recovery according to claim 4, wherein: The lithium compound satisfies the following formula 2, <Formula 2> ([Na]+[K]+[Mg]) / [Ca]≤3.6 [Na], [K], [Mg] and [Ca] each represent the weight % of Na, K, Mg and Ca.

7. The method for recovering lithium compounds for valuable metal recovery according to claim 4, wherein: The step of heating the crushed battery fragments is carried out in an environment of at least one of an inert gas, carbon dioxide, carbon monoxide and a hydrocarbon gas.

8. The method for recovering lithium compounds for valuable metal recovery according to claim 4, wherein: The steps of freezing and forcibly discharging the battery are performed by cooling to -150 to -60°C.

9. The method for recovering lithium compounds for valuable metal recovery according to claim 4, wherein: The steps of freezing and forcibly discharging the battery are performed by cooling to -60 to -20°C under a vacuum environment condition of less than 1000 Torr.

10. The method for recovering lithium compounds for valuable metal recovery according to claim 4, wherein: The steps of freezing and forcibly discharging the battery satisfy the following formula 1: <Formula 4> Minimum cooling time (Hr) = A × (W 0.33 ) A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

11. The method for recovering lithium compounds for valuable metal recovery according to claim 4, wherein: The step of freezing and forcibly discharging the battery comprises forcibly discharging the battery at a discharge rate of less than 0.04 V / min.

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