KR20250145750A - Method for removing impurities including fluorine and obtaining valuable metals from waste batteries - Google Patents

Abstract

The present invention relates to a method for removing impurities including fluorine from medium- to large-sized spent batteries and obtaining valuable metals, comprising: an alkaline water discharge step (S10) in which medium- to large-sized spent battery cells are immersed in a sodium carbonate (Na ₂ CO ₃ ) aqueous solution and discharged; a crushing and fluorine removal step (S20) in which the battery cells that have gone through the alkaline water discharge step (S10) are put into a calcium carbonate (CaCO ₃ ) aqueous solution to crush and remove fluorine compounds through a chemical reaction; a separator removal and classification step (S30) in which the crushed materials that have gone through the crushing and fluorine removal step (S20) are dried with hot air and separated by gravity to obtain a pulverized material from which a separator has been removed; an electrolyte salt removal and heat treatment step (S40) in which the pulverized materials that have gone through the crushing and fluorine removal step (S20) are reacted with concentrated sulfuric acid to remove electrolyte salts and thermally decompose residual organic substances; and a waste material that has gone through the electrolyte salt removal and heat treatment step (S40) is powdered and particle-sized to obtain valuable metals. By including a crushing and classification step (S50) for obtaining black mass, it is characterized by being able to obtain high-quality black mass in a more environmentally friendly manner by removing various impurities in stages and treating environmental pollutants generated in the process during the process of recovering valuable metals for recycling lithium-ion batteries used in electric vehicles or energy storage systems.

Description

Method for removing impurities including fluorine and obtaining valuable metals from medium- to large-sized waste batteries

The present invention relates to a method for removing impurities including fluorine from medium- to large-sized waste batteries and obtaining valuable metals, and more specifically, to a technology for gradually removing other substances contained in lithium-ion batteries in the process of recovering valuable metals such as nickel, cobalt, fluorine, and lithium for recycling lithium-ion batteries used in electric vehicles or energy storage systems, and effectively processing environmental pollutants generated in the process to obtain high-quality black mass in a more environmentally friendly manner.

In general, lithium-ion batteries are secondary batteries that are widely used in various electronic devices due to their high energy density. They generate electricity according to the electrical flow of lithium ions moving through the electrolyte between the positive and negative electrodes.

The battery cell, which is the smallest unit of a secondary battery, is composed of a cathode material, an anode material, an electrolyte, and a separator inside a container. When charging, lithium ions move from the anode through the separator to the cathode, and when discharging, they move from the cathode to the anode.

The cathode materials used in secondary batteries include nickel, manganese, cobalt, and aluminum, while the anode material is graphite, an anode active material. The electrolyte is composed of a lithium salt (e.g., lithium, phosphoric acid, and fluorine) and an organic solvent.

Meanwhile, the recent expansion of the electric vehicle market and the increased use of energy storage systems (ESS) are expected to exponentially increase the generation of medium- to large-sized waste batteries. As mentioned above, secondary batteries contain valuable metals such as lithium, nickel, manganese, and cobalt as active materials. Therefore, various recycling technologies are being developed to recover mineral resources from these batteries.

As an example of a known technology, Korean Patent No. 10-1275849 discloses a pretreatment method for a lithium-ion battery regeneration process, including the steps of treating a spent lithium-ion battery with a sodium chloride (NaCl) aqueous solution having a concentration of 0.5 to 10% to cause corrosion discharge, crushing the lithium-ion battery waste containing an electrolyte, a separator, an electrode composite, and a current collector into pieces of 5 to 15 mm in size, washing the crushed product with water to remove the electrolyte, and then subjecting the crushed product from which the electrolyte has been removed to gravity separation to remove the separator, and treating the crushed product from which the electrolyte and separator have been removed with a sulfuric acid solution having a concentration of 1 to 4 M to separate and recover the electrode composite attached to the current collector in the crushed product.

As another example, Korean Patent No. 10-2191858 discloses a method for recovering raw materials of a waste lithium-ion battery, including a spent lithium-ion battery brine precipitation step of precipitating a spent lithium-ion battery in a predetermined brine tank, a spent lithium-ion battery discharge step of discharging the spent lithium-ion battery by performing the spent lithium-ion battery brine precipitation step for a predetermined process time, a spent lithium-ion battery cutting step of cutting the discharged spent lithium-ion battery into a predetermined size using a cutter, a cut spent lithium-ion battery drying step of inserting the cut spent lithium-ion battery cut into the predetermined size into a dryer and drying it under predetermined drying process conditions, a cut spent lithium-ion battery crushing step of inserting the dried cut spent lithium-ion battery into a crusher and crushing it, and a raw material selection step of selecting raw materials such as cobalt, nickel, manganese, carbon, copper, and aluminum, which are active materials, from the crushed powder by inserting the powder crushed by the crusher into a selector.

Korean Patent No. 10-1275849 (June 17, 2013) Korean Patent No. 10-2191858 (December 16, 2020) Korean Patent No. 10-1220149 (January 11, 2013) Korean Patent No. 10-1149762 (June 1, 2012)

To recover valuable metals like nickel and cobalt from used lithium-ion batteries, the batteries must be crushed and pulverized into powder, then heat-treated to remove organic substances like binders coated on the electrode plates, thereby separating the cathode active material. However, since electrical energy remains in used lithium-ion batteries, crushing and pulverizing them without separate discharge treatment can cause physical contact between the positive and negative electrodes, resulting in a short circuit and the generation of large amounts of internal heat, which can lead to fire or explosion.

Therefore, the conventional technology comprises a discharging step to completely remove the remaining electric energy in a waste battery, a crushing step for the discharged waste battery, a removing step for the separator from the crushed waste battery, a sulfuric acid treatment step for separating the current collector, and a selection step for recovering valuable metals.

Conventional discharge steps generally involve placing the spent battery into a tank containing salt water and connecting the spent battery to a discharge-capable facility with a wire to remove the electrical energy inside the spent battery.

The electrical discharge method has the disadvantage of requiring a large increase in the scale of facilities to process large quantities of medium- to large-sized waste batteries, increasing the economic burden of constructing expensive discharge facilities, and in particular, there is a risk of fire and explosion due to defects in specific cells during the electrical discharge process.

Discharging using brine has the advantage of safety because the spent batteries are immersed in brine, recovered after discharging, and moved to the next step. However, during the process of discharging by immersion in brine, the spent batteries corrode due to the brine, leaching internal organic compounds and fluorine compounds, generating a large amount of wastewater. In addition, the chlorine (Cl-) ions contained in the sodium chloride (NaCl) used in the brine move to the next step and act as hydrochloric acid during the sulfuric acid treatment, causing equipment corrosion. Furthermore, since the water temperature rises during underwater discharge using brine, there is a problem that the possibility of internal fire cannot be ruled out in case of excessive discharge.

In addition, in the conventional technology, a method of crushing spent batteries discharged in salt water using a crusher or grinder is applied, but in this process, chemicals such as electrolytes containing fluorine are leaked to the outside, and during the sulfuric acid treatment process, fluorine gas is also emitted, and harmful substances including fluorine are emitted at each stage, which aggravates environmental pollution.

Accordingly, the present invention has been invented to solve the problems of the prior art as described above.

Alkaline water discharge step (S10) in which medium and large-sized waste battery cells are immersed in a sodium carbonate (Na ₂ CO ₃ ) aqueous solution and discharged;

A crushing and fluorine removal step (S20) in which the battery cell that has gone through the alkaline water discharge step (S10) is crushed by placing it in a calcium carbonate (CaCO ₃ ) aqueous solution and the fluorine compound is removed through a chemical reaction;

A membrane removal and classification step (S30) for obtaining a pulverized material from which the membrane has been removed by hot air drying and gravity separation of the pulverized material that has gone through the above-mentioned crushing and fluorine removal step (S20),

An electrolytic salt removal and heat treatment step (S40) in which the pulverized material that has gone through the above crushing and fluoride removal step (S20) is reacted with concentrated sulfuric acid to remove electrolytic salts and thermally decompose residual organic substances;

By including a crushing and classification step (S50) for pulverizing and selecting the particle size of the waste material that has gone through the above-mentioned electrolyte salt removal and heat treatment step (S40) to obtain black mass containing valuable metals, it is possible to achieve the purpose of removing various impurities in stages and treating environmental pollutants generated in the process in order to recover valuable metals for recycling lithium-ion batteries used in electric vehicles or energy storage systems, thereby obtaining high-quality black mass in a more environmentally friendly manner.

The present invention relates to a technology for gradually removing other substances contained in lithium-ion batteries during the process of recovering valuable metals for recycling medium- to large-sized lithium-ion batteries used in electric vehicles or energy storage systems, and for effectively treating environmental pollutants generated during this process to obtain high-quality black mass.

In particular, the present invention has the advantage of effectively removing hazardous substances including fluorine through a configuration differentiated from the prior art at each stage in order to solve environmental pollution problems caused by organic compounds, fluorine compounds, etc. generated in the process of recycling waste batteries according to the prior art, and at the same time reducing problems such as the possibility of ignition and corrosion of equipment.

In addition, in the case of the black mass with reduced impurities manufactured by the present invention, the content of impurities including fluorine and chlorine is minimized compared to the black mass obtained using conventional recycling technology, thereby enabling high quality, and the harmful substances generated at each stage are recovered and removed through chemical reactions, thereby enabling an eco-friendly recycling process.

Accordingly, the present invention has the effect of satisfying both environmental friendliness and safety and efficiency by being applied to the recycling process of waste batteries in line with the expected expansion in demand for electric vehicles and energy storage systems.

Figure 1 is a process flow diagram of a method for removing impurities including fluorine from medium- to large-sized waste batteries and obtaining valuable metals according to the present invention.
Table 1 of Fig. 2 is an example of the results of calculating the weight of internal components based on the pouch cell.
Table 2 of FIG. 3 is a comparison table of the results of measuring the discharge voltage by the alkaline water discharge step (S10) according to an embodiment of the present invention and the discharge voltage by the water discharge according to the prior art.
Table 3 of FIG. 4 is a comparison table of the results of measuring the fluorine and chlorine contents of a black mass finally obtained according to an embodiment of the present invention and a commercial black mass sample manufactured by a conventional recycling process.

Hereinafter, the configuration and operation of a preferred embodiment of a method for removing impurities including fluorine from medium- to large-sized spent batteries of the present invention and obtaining valuable metals will be described in detail with reference to the attached drawings. In the following description, specific descriptions of parts that can be easily implemented by those skilled in the art may be omitted. In addition, since the following description describes preferred embodiments of the present invention, the present invention is not limited to the following embodiments, and it will be understood that various modifications may be provided within a scope that does not depart from the scope of the present invention.

It is noted that the method for removing impurities including fluorine from medium- to large-sized waste batteries to which the technology of the present invention is applied and obtaining valuable metals relates to a technology for removing various impurities in stages in the process of recovering valuable metals for recycling used lithium-ion batteries and treating environmental pollutants generated in the process to recycle resources in a more environmentally friendly manner.

The method of removing impurities including fluorine from medium-sized and large-sized waste batteries of the present invention and obtaining valuable metals comprises an alkaline water discharge step (S10), a crushing and fluorine removal step (S20), a separator removal and classification step (S30), an electrolyte salt removal and heat treatment step (S40), and a crushing and classification step (S50), and is specifically as follows.

The alkaline water discharge step (S10) is a step in which medium- to large-sized waste battery cells are discharged by immersing them in a sodium carbonate (Na ₂ CO ₃ ) aqueous solution.

In the alkaline water discharge step (S10), a sodium carbonate (Na ₂ CO ₃ ) aqueous solution is prepared by adding 1 to 30 wt%, more preferably 3 to 7 wt%, of sodium carbonate (Na ₂ CO ₃ ) to water based on the total weight.

Sodium carbonate dissolves in the form of ions in aqueous solutions and acts as an electrolyte, and the pH of the liquid is adjusted to be slightly alkaline. The carbon dioxide generated during the underwater discharge process using sodium carbonate (Na ₂ CO ₃ ) aqueous solution creates an inert atmosphere inside the sedimentation tank, thereby reducing the possibility of fire during discharge.

In the alkaline underwater discharge step (S10) according to the present invention, the termination point is set based on the voltage of the spent battery falling below 1 V. The trace amount of electrical energy remaining inside the spent battery can be shredded underwater in the shredding and fluoride removal step (S20) described below, thereby shortening the time required for complete discharge, thereby enabling efficient management according to operating conditions.

The discharged liquid phase used in the alkaline water discharge step (S10) is configured to be reused as a sodium carbonate (Na ₂ CO ₃ ) aqueous solution in the alkaline water discharge step (S10) through a solid-liquid separation step (S11) and a discharge liquid mixing step (S12).

In the solid-liquid separation step (S11), the liquid phase after discharge is transferred to a filtering device, and fine particles and filtration substances are filtered. In the discharge-liquid mixing step (S12), the filtrate liquid phase is transferred to a discharge solution mixing tank to readjust the concentration of the liquid phase. After discharge, the discharge liquid phase is prepared by mixing sodium carbonate (Na ₂ CO ₃ ) and water based on the sodium content and pH in the liquid phase. The sodium content in the liquid phase is managed within the range of 1.5 to 3 wt%, and the pH in the liquid phase is managed within the range of 8 to 9.

The crushing and fluoride removal step (S20) is a step in which the battery cell that has gone through the alkaline water discharge step (S10) is placed in a calcium carbonate (CaCO ₃ ) aqueous solution to crush it and remove fluoride compounds through a chemical reaction.

In the crushing and fluoride removal step (S20), in order to resolve the problem of risk of fire or explosion if electrical energy remains inside the spent battery when crushing is performed in an oxygen-containing atmosphere at room temperature as in the past, an underwater discharge and inert atmosphere are created. However, during underwater crushing, fluorine compounds such as lithium hexafluorophosphate (LiPF6) flow into the underwater crushing tank during the cutting process of the spent battery, causing corrosion of the equipment, and if discharged without separate fluoride removal treatment, serious environmental pollution occurs.

In the crushing and fluorine removal step (S20) according to the present invention, a battery cell discharged to 1 V or less through an alkaline water discharge step (S10) is placed in an underwater crushing tank and cut into a certain size so that the separator can be removed in the subsequent separator removal and classification step (S30), and in particular, the crushing process is configured to remove compounds containing fluorine inside the spent battery.

In the crushing and fluoride removal step (S20), the calcium carbonate (CaCO ₃ ) aqueous solution introduced into the underwater crushing tank is prepared by adding 1 to 30 wt% of calcium carbonate (Na ₂ CO ₃ ) to the total weight into water.

When the battery cells are crushed in an underwater crushing tank by the crushing and fluoride removal step (S20), the fluorine compounds that flow out from the spent batteries are removed in the form of calcium fluoride (CaF ₂ ) by reacting with water and a calcium carbonate (CaCO ₃ ) aqueous solution according to the following reaction formulas 1 and 2.

In the case of lithium hexafluorophosphate (LiPF6), it can undergo an ionization reaction in the form of lithium ions (Li+) and phosphorus hexafluoride (PF6-) or can exist in the form of lithium fluoride (LiF) and phosphorus pentafluoride (PF5). When phosphorus pentafluoride (PF5) reacts with moisture, a substance is generated after the reaction as shown in the following reaction formula 1.

[Reaction Formula 1]

PF ₅ + 4H ₂ O → H ₃ PO ₄ + 5HF

Hydrogen fluoride (HF) is highly corrosive and is fatal to equipment corrosion and is also harmful to humans and the environment. Therefore, in this step, it is crushed in a calcium carbonate (CaCO ₃ ) aqueous solution to induce a reaction as shown in the following reaction formula 2, thereby removing fluorine and obtaining a cut lithium ion battery.

[Reaction Formula 2]

CaCO ₃ + HF → CaF ₂ + CO ₂ + H ₂ O

Calcium carbonate (CaCO ₃ ) generally has low solubility and is not dissolved in powder form before crushing, but is gradually consumed as it reacts with the formation of hydrogen fluoride (HF), so the amount of calcium carbonate input is adjusted within the above-described range depending on the operating conditions and processing volume of the process. The size of the crushed material is cut to suit the conditions within the range of 10 mm × 10 mm to 40 mm × 40 mm, taking into account the specific gravity separation in the subsequent separation membrane removal and classification step (S30).

In the crushing and fluoride removal step (S20), carbon dioxide (CO 2 ) generated by the reaction between the calcium carbonate (CaCO ₃ ) aqueous solution and calcium fluoride (CaF ₂ ) as in the above reaction formula ₂ is configured to be used as an inert gas inside the underwater crushing tank to prevent ignition.

The membrane removal and classification step (S30) is a step of hot-air drying and gravity separation of the crushed material that has gone through the crushing and fluorine removal step (S20) to obtain a crushed material from which the membrane has been removed.

In the separator removal and classification step (S30), the lithium-ion battery waste recovered through the crushing and fluorine removal step (S20) is dehydrated, and the moisture on the surface is removed using a dry hot air stream, and the relatively light separator is removed using the specific gravity difference principle.

In conventional technology, the separation membrane is removed by burning it during a heat treatment process, but there is a problem in that when the separation membrane is burned, scale is generated inside the pipe, which becomes stuck and causes pipe blockage.

Therefore, in the present invention, the separator, which dries faster than the electrode plate and weighs less than the positive and negative electrode plates for the same area, is first removed by separating it by the difference in specific gravity through the separator removal and classification step (S30), and the remainder is separated through the electrolyte salt removal and heat treatment step. Table 1 of Figure 2 below is an example of the results of calculating the weight of the internal components based on the pouch cell.

The gravity separation equipment can be applied in table type, zigzag type, airflow type, etc., and separates the membrane from the positive and negative plates.

Since some of the electrolyte evaporates during the drying process using hot air, the drying facility installs a passage for exhaust. The evaporated electrolyte may contain fluorine compounds even after being incinerated through a cooling capture or combustion facility. The fluorine compounds contained in the electrolyte that evaporates during drying are brought into contact with a reaction tank filled with a calcium hydroxide (Ca(OH) ₂ ) aqueous solution by moving the air current, and the calcium hydroxide (Ca(OH) ₂ ) aqueous solution is bubbled to precipitate fluorine into calcium fluoride salt ( _CaF2 ). Afterwards, it is transferred to an air environment facility such as a scrubber for treatment.

In the membrane removal and classification step (S30), the crushed material from which the membrane has been removed is first pulverized to obtain a pulverized material by uniformly adjusting the particle size to approximately 300 μm to 1 mm or less. The fine particles generated during the pulverization process are recovered through a cyclone connected to a dust collector.

The electrolytic salt removal and heat treatment step (S40) is a step in which the pulverized material that has gone through the crushing and fluorine removal step (S20) is reacted with concentrated sulfuric acid to remove the electrolytic salt and thermally decompose the residual organic substances.

In the electrolytic salt removal and heat treatment step (S40), fluorine is removed through a dehydration reaction and a substitution reaction of sulfuric acid groups using high-concentration sulfuric acid with a concentration of 95 wt% or more to remove the electrolytic salt, and organic substances such as residual PVDF (Polyvinylidene Fluoride) are removed.

In order to recover valuable metals from lithium-ion batteries after use, it is common to remove organic substances such as binders by thermal decomposition at about 500 to 700°C to separate the electrode plates and cathode active materials. However, among the substances that make up the electrolyte, the electrolyte salt (LiPF6) remains even after heat treatment and is included in the final obtained substance, black mass.

When utilizing a wet refining technology to recover valuable metals such as nickel and cobalt in the form of sulfate while containing fluorine compounds such as electrolyte salt (LiPF6) in black mass, the fluorine in the electrolyte salt may combine with the extractant during the solvent extraction process for selective metal recovery or be discharged in the form of wastewater, causing environmental pollution. Therefore, in the electrolyte salt removal and heat treatment step (S40) of the present invention, the material that has been primarily pulverized through the membrane removal and classification step (S30) is mixed with concentrated sulfuric acid to induce a reaction to remove fluorine in the fluorine compound using a substitution reaction along with a dehydration reaction.

In the step of removing and heat treating the electrolyte salt (S40), the solid-liquid ratio of the pulverized material to the concentrated sulfuric acid is in the range of 1:0.5 to 1:3, more preferably 1:1 to 1:2, and the reaction is performed at 60 to 80°C for 30 to 120 minutes to remove the electrolyte salt. If the concentration of sulfuric acid is lower than 90 wt%, it may react with the pulverized material, so concentrated sulfuric acid of 95 wt% or more is used.

In the electrolytic salt removal and heat treatment step (S40), the fluorine gas generated when the pulverized material is reacted with concentrated sulfuric acid is brought into contact with a reaction tank filled with a calcium hydroxide (Ca(OH) ₂ ) aqueous solution by moving the air current, and a calcium fluoride reaction treatment step (S41) is included to remove the fluorine gas by precipitating it as calcium fluoride salt ( _CaF2 ) according to the following reaction formula 3.

[Reaction Formula 3]

F ₂ + Ca(OH) ₂ = CaF ₂ + ^1/2 O ₂ + H ₂ O

In the calcium fluoride reaction treatment step (S41), the calcium hydroxide (Ca(OH) ₂ ) aqueous solution is brought into contact with fluorine gas in a form such as bubbling or nozzle spraying to remove fluorine by precipitating it as calcium fluoride salt ( _CaF2 ), and then transferred to an atmospheric environmental facility such as a scrubber for treatment.

After the electrolyte salt removal reaction, the pulverized material is centrifuged and then thermally decomposed to remove residual organic substances through high-temperature heat treatment at 500 to 550℃. During the high-temperature heat treatment process, gases such as argon (Ar) and nitrogen (N ₂ ) are injected to create an inert atmosphere to sufficiently create an internal atmosphere before the temperature is raised, and the organic substances on the pulverized material are removed by raising the temperature to 500 to 700℃. The lithium contained in the cathode material can react with residual sulfuric acid and be reduced to the form of lithium sulfate.

Fluorine gas generated during the heat treatment process reacts with calcium compounds remaining on the crushed material during underwater crushing using a calcium carbonate (CaCO ₃ ) aqueous solution in the crushing and fluoride removal step (S20) to form calcium fluoride, thereby enabling fluorine removal according to the above reaction formula 3.

The crushing and classification step (S50) is a step of pulverizing and selecting the particle size of the product that has gone through the electrolytic salt removal and heat treatment step (S40) to obtain black mass containing valuable metals.

In the crushing and classification step (S50), the heat-treated material obtained in the electrolytic salt removal and heat treatment step (S40) is crushed and classified to separate it into Al and Cu electrode plates and positive and negative electrode active materials.

Crushing is carried out in a single or multi-stage manner depending on the form of the to-be-fired material. If there is a phenomenon of agglomeration of the to-be-fired material during the high-temperature heat treatment process, it is preferable to first crush the to-be-fired material using a ball mill or rod mill facility and then carry out crushing.

In the crushing and classification step (S50), the powder is crushed to a particle size of approximately 100 to 200 μm, and the plates and positive and negative active materials are separated through particle size screening. The crushing and classification equipment can be an impact crusher, hammer crusher, pin crusher, jet mill, etc. After the crushing and classification step (S50), the final black mass, which is a mixture of positive and negative active materials, is obtained.

Hereinafter, an embodiment of the present invention having the configuration described above will be described and the effects thereof will be examined in detail.

<Example 1. Comparison of discharge voltage according to discharge liquid phase and time>

In the alkaline underwater discharge step (S10) according to the present invention, underwater discharge was performed on a pouch-type lithium-ion battery to compare the discharge effect using a sodium chloride (NaCl) aqueous solution used as a discharge liquid in the prior art and a sodium carbonate (Na ₂ CO ₃ ) aqueous solution of the present invention, and the results are as described in Table 2 of FIG. 3 below.

As can be seen in Table 2, it can be confirmed that the alkaline water discharge step (S10) using the sodium carbonate (Na ₂ CO ₃ ) aqueous solution according to the present invention produces a discharge effect equivalent to that of the conventional method using sodium chloride (NaCl). In particular, when the sodium carbonate (Na ₂ CO ₃ ) of the present invention is used, the problem of chlorine (Cl-) being included in the discharge liquid phase and even in the black mass during the conventional sodium chloride (NaCl) discharge is fundamentally eliminated, and thus, it has the advantage of enabling significantly more efficient process operation compared to the conventional sodium chloride (NaCl) discharge.

<Example 2. Comparison of impurity content in final product>

A method for removing impurities including fluorine from medium- to large-sized spent batteries and obtaining valuable metals according to the present invention is performed to obtain a final black mass, and the content of impurities including chlorine and fluorine in the black mass is confirmed. In addition, the impurity content of commercial black mass produced by a conventionally well-known and commonly used waste battery recycling process (salt water discharge using sodium chloride (NaCl) → crushing/grinding → high-temperature heat treatment → crushing/classification) is confirmed and compared with that of the present invention.

An embodiment of the present invention obtains a final black mass through a process including an alkaline water discharge step (S10) and a crushing and classification step (S50).

1) Alkaline water discharge stage (S10): To discharge electric energy within a pouch-type battery cell, the battery was immersed in a tank filled with a 5 wt% sodium carbonate (Na ₂ CO ₃ ) aqueous solution and alkaline water discharge was performed to below 1 V. The discharge time was 18 hours, and the voltage measured after recovering the immersed battery was confirmed to be 0.83 V.

2) Crushing and fluoride removal step (S20): 100.0 parts by weight of the recovered battery was placed in an underwater crushing tank filled with a 10 wt% calcium carbonate (Na ₂ CO ₃ ) aqueous solution and cut into pieces of 20 mm × 30 mm to obtain 99.6 parts by weight of crushed material.

3) Membrane removal and classification step (S30): The obtained crushed material was dried for 30 minutes with a hot air stream, and the membrane was removed using a gravity separator to obtain 86.5 parts by weight of the crushed material from which the membrane was removed. The separated membrane was approximately 4.1 parts by weight, and the remaining weight loss is expected to be due to the evaporation of the electrolyte during the hot air drying process.

Afterwards, the crushed material from which the separation membrane was removed was first pulverized to a size of 380 μm to obtain 86.1 parts by weight of the pulverized material.

4) Electrolytic salt removal and heat treatment step (S40): In order to remove the electrolytic salt on the pulverized material, 99 wt% concentrated sulfuric acid was added to 86.1 wt% of the pulverized material at a solid-liquid ratio (S:L) of 1:2, heated to 60 to 70°C, stirred, and the reaction was performed for 1 hour.

After the reaction was completed, sulfuric acid and the pulverized material were separated, and heat treatment was performed to thermally decompose the residual organic matter. The heat treatment was performed by supplying nitrogen at a rate of 30 to 40 L/min and maintaining the temperature at 520°C for 3 hours, and 71.4 parts by weight of the product was obtained after the heat treatment.

5) Crushing and Classification Step (S50): In order to separate the electrode plates, positive electrode active material, and negative electrode active material from the obtained precipitate, multi-stage crushing was performed. First, the material was crushed to a size of 300 μm and classified using a 220 μm particle size separator. The separated material was crushed to a size of 140 μm and classified using a 120 μm particle size separator, and finally, a black mass of 58.4 parts by weight was obtained.

6) Results: The content of fluorine (F-) and chlorine (Cl-) in the black mass finally obtained by the present invention and a commercial black mass sample manufactured by a conventional recycling process were measured and compared using a CIC (combustion ion chromatography) analysis device, and the results are as shown in Table 3 of FIG. 4 below. It can be confirmed that the content of fluorine in the black mass obtained by the present invention was significantly reduced compared to the commercial black mass manufactured by a conventional technique, and that chlorine components remain in the conventional commercial black mass, but no chlorine can be detected at all in the black mass of the present invention.

The method of removing impurities including fluorine from medium- to large-sized waste batteries and obtaining valuable metals according to the present invention as described above has the advantage of effectively removing hazardous substances including fluorine through a configuration differentiated from the prior art at each stage in order to solve environmental pollution problems caused by various organic compounds and fluorine compounds generated in the process of recycling medium- to large-sized waste batteries used in electric vehicles or energy storage systems, and at the same time reducing problems such as the possibility of ignition and corrosion of equipment.

In addition, in the case of the black mass with reduced impurities manufactured by the present invention, the content of impurities including fluorine and chlorine is minimized compared to the black mass obtained using conventional recycling technology, thereby enabling high quality, and the harmful substances generated at each stage are recovered and removed through chemical reactions, thereby enabling an eco-friendly recycling process.

Accordingly, the present invention is expected to have great potential for industrial use, as it can be applied to the recycling process of waste batteries in line with the expected expansion in demand for electric vehicles and energy storage systems, thereby ensuring environmental friendliness and safety as well as efficiency.

S10: Alkaline water discharge stage
S11: High-liquid separation stage
S12: Discharge liquid mixing stage
S20: Shredding and Fluoride Removal Stage
S30: Membrane removal and classification stage
S40: Electrolytic salt removal and heat treatment step
S41: Calcium fluoride reaction treatment step
S50: Crushing and Classification Stage

Claims (6)

Alkaline water discharge step (S10) in which medium and large-sized waste battery cells are immersed in a sodium carbonate (Na ₂ CO ₃ ) aqueous solution and discharged;
A crushing and fluorine removal step (S20) in which the battery cell that has gone through the alkaline water discharge step (S10) is crushed by placing it in a calcium carbonate (CaCO ₃ ) aqueous solution and the fluorine compound is removed through a chemical reaction;
A membrane removal and classification step (S30) for obtaining a pulverized material from which the membrane has been removed by hot air drying and gravity separation of the pulverized material that has gone through the above-mentioned crushing and fluorine removal step (S20),
An electrolytic salt removal and heat treatment step (S40) in which the pulverized material that has gone through the above crushing and fluoride removal step (S20) is reacted with concentrated sulfuric acid to remove electrolytic salts and thermally decompose residual organic substances;
A method for removing impurities including fluorine and obtaining valuable metals from medium- to large-sized waste batteries, characterized by including a crushing and classification step (S50) for pulverizing and selecting particle sizes of the waste material that has undergone the above-mentioned electrolyte removal and heat treatment step (S40) to obtain black mass containing valuable metals. In the first paragraph,
In the alkaline water discharge step (S10), the sodium carbonate (Na ₂ CO ₃ ) aqueous solution is prepared by adding 1 to 30 wt% of sodium carbonate (Na ₂ CO ₃ ) to the total weight into water.
_A method for removing impurities including fluorine from medium- to large-sized spent batteries and obtaining valuable metals, characterized in that the liquid phase after discharge is transferred to a filtering device and a solid-liquid separation step ( _S11 ) for filtering out fine particles and filtration substances, and the filtrate phase is transferred to a discharge solution mixing tank and a discharge liquid mixing step (S12) for adjusting the concentration of the liquid phase by mixing sodium carbonate (Na ₂ CO ₃ ) and water, thereby reusing the sodium carbonate (Na 2 CO 3 ) aqueous solution in the alkaline water discharge step (S10). In the first paragraph,
In the above crushing and fluoride removal step (S20), the calcium carbonate (CaCO ₃ ) aqueous solution is prepared by adding 1 to 30 wt% of calcium carbonate (Na ₂ CO ₃ ) to water based on the total weight.
A method for removing impurities including fluorine from medium- to large-sized spent batteries and obtaining valuable metals, characterized in that the fluorine compounds discharged from spent batteries during crushing in an underwater crushing tank are removed in the form of calcium fluoride (CaF ₂ ) by reacting with water and a calcium carbonate (CaCO ₃ ) aqueous solution according to the following reaction formulas 1 and 2.
[Reaction Formula 1]
PF ₅ + 4H ₂ O → H ₃ PO ₄ + 5HF
[Reaction Formula 2]
CaCO ₃ + HF → CaF ₂ + CO ₂ + H ₂ O In the third paragraph,
A method for removing impurities including fluorine and obtaining valuable metals from medium- to large-sized waste batteries, characterized in that carbon dioxide (CO ₂ ) generated by the reaction of the above calcium carbonate (CaCO ₃ ) aqueous solution and calcium fluoride (CaF ₂ ) is configured to be used as an inert gas inside an underwater crushing tank to prevent ignition. In the first paragraph,
In the above electrolyte removal and heat treatment step (S40),
A method for removing impurities including fluorine and obtaining valuable metals from medium- to large-sized spent batteries, characterized in that the reaction is performed in a high-liquid ratio of pulverized material and concentrated sulfuric acid having a sulfuric acid concentration of 95 wt% or more in the range of 1:0.5 to 1:3, and the reaction is performed at 60 to 80°C for 30 to 120 minutes to remove electrolyte salts. In the first paragraph,
In the above electrolyte removal and heat treatment step (S40),
A method for removing impurities including fluorine from medium- to large-sized spent batteries and obtaining valuable metals, characterized by including a calcium fluoride reaction treatment step ( _S41 ) in which fluorine gas generated when the pulverized material is reacted with concentrated sulfuric acid is brought into contact with a reaction tank filled with a calcium hydroxide (Ca(OH ₎₂ ) aqueous solution by moving an air current therethrough and precipitating the fluorine gas as calcium fluoride salt (CaF2) according to the following reaction formula 3.
[Reaction Formula 3]
F ₂ + Ca(OH) ₂ = CaF ₂ + ^1/2 O ₂ + H ₂ O