KR20050112487A - High-rate recovery of valuable metals such as cobalt and lithium from waste lithium secondary batteries - Google Patents

Abstract

The present invention relates to a high-purity recovery method of valuable metals such as cobalt and lithium from a waste lithium ion secondary battery. More particularly, aluminum is separated into a liquid phase by using caustic soda and additives in a waste lithium ion secondary battery. Aluminum dissolution process, inorganic acid leaching process to leach the dissolved residue into liquid phase with inorganic acid and redox agent, neutralization added to the dissolved residue to adjust pH to 3.0 ~ 4.5, primary neutralization process for solid-liquid separation of iron and aluminum, strong alkali It is characterized by consisting of a secondary neutralization step of separating copper at pH 4.8 ~ 5.6 by addition, a repulping process to treat the dissolved residue, and a solvent extraction process to separate lithium and cobalt, in particular waste lithium ion secondary In the subsequent process, aluminum is dissolved and separated using caustic soda and additives before the battery is leached with inorganic acids. Minimizes the process load caused by the process, and efficiently separates metals such as iron, aluminum, and copper through two-step neutralization process, minimizes the input of neutralizing agent, and recovers and purity of cobalt through repulping process and solvent extraction process. It is to provide a means to increase.

Description

High-rate recovery of valuable metals such as cobalt and lithium from waste lithium secondary batteries}

The present invention relates to a high-purity recovery method of valuable metals such as cobalt and lithium from a waste lithium ion secondary battery. More particularly, aluminum is separated into a liquid phase by using caustic soda and additives in a waste lithium ion secondary battery. Aluminum dissolution process, inorganic acid leaching process to leach the dissolved residue into liquid phase with inorganic acid and redox agent, neutralization added to the dissolved residue to adjust pH to 3.0 ~ 4.5, primary neutralization process for solid-liquid separation of iron and aluminum, strong alkali It is characterized by consisting of a secondary neutralization step of separating copper at pH 4.8 ~ 5.6 by addition, a repulping process to treat the dissolved residue, and a solvent extraction process to separate lithium and cobalt, in particular waste lithium ion secondary In the subsequent process, aluminum is dissolved and separated using caustic soda and additives before the battery is leached with inorganic acids. Minimizes the process load caused by the process, and efficiently separates metals such as iron, aluminum, and copper through two-step neutralization process, minimizes the input of neutralizing agent, and recovers and purity of cobalt through repulping process and solvent extraction process. It is to provide a means to increase.

Lithium ion battery (LIB) has high operating voltage and excellent charge / discharge cycle and miniaturization, so it is widely used as a power source for communication and information devices such as mobile phones, laptops, digital cameras, camcorders, etc. Globally, demand is rapidly increasing by more than 25% every year, from about 780 million in 2002 to about 970 million in 2003, and the amount of lithium-ion secondary batteries that are discarded is rapidly increasing. Lithium-ion secondary batteries are coated with aluminum oxide with a composite oxide, usually represented by LiCo _(1-X) MnXO ₂ or LiXMO ₂ (M is cobalt Co or nickel Ni), and the carbon material is mainly coated on the copper foil. The coated product is a cathode, in which a microporous polypropylene is placed between an anode and a cathode or outside of an anode or a cathode, bundled together, and covered with an iron sheath. A metal nickel foil is used as a lead. The raw material ratio of the lithium ion secondary battery varies from manufacturer to manufacturer, but typically contains 25% Fe, 17% Co, 7% Al, 7% Cu, 3-5% Li, and 1% Ni. At this time, the cobalt used is heat and abrasion resistance, and particularly has strong resistance to alloys with tungsten, chromium, nickel and the like. Therefore, it is widely used as a raw material for high speed steel, heat resistant alloys, and carbide tool materials. It is also widely used as a magnetic material and as a raw material for catalyst materials. Cobalt is an indispensable metal in industrial society, but its production is ubiquitous, and its supply is constantly unstable due to the political and social situation of the producing country. Although the research on the recovery and reuse of valuable metals such as lithium and cobalt contained in a large amount of waste lithium ion secondary batteries has been widely conducted, there are difficulties in practical use due to environmental problems and economic problems.

Urea technologies for recovering valuable metals from spent lithium ion secondary batteries are classified into screening technology, melting technology, and separation and purification technology. The sorting process is a step of sorting, dismantling, cutting, and crushing waste batteries, and the dissolving process is a step of separating and concentrating metals by dissolving the crushed scrap in an inorganic acid and the like, and separating and recovering valuable metals from other impurities. to be. The sorting process is generally subjected to sorting, dismantling, cutting, pulverization, calcination, and the like, and most of the dissolving processes have been proposed by adding a reducing agent such as hydrogen peroxide to inorganic acids such as sulfuric acid or hydrochloric acid. Separation and purification processes include electrolytic extraction, precipitation and solvent extraction.

Brief description of the elements of the conventional recovery method associated with the recovery method according to the present invention.

In Korean Patent No. 2001-0106562, an electrode material is made into a powder and separated into an electrode material and a metal piece, and the separated electrode material is burned to remove impurities such as carbons or organic binders, and then only LiCoO ₂ , a cathode active material, is selected and a reducing agent is added. LiCoO _{2 is} added to an acid solution such as sulfuric acid or nitric acid, and cobalt and lithium are reduced and leached. A method for separating and recovering cobalt and lithium in the form of metal salts by separating them into a liquid phase is described. However, in the process of calcining the electrode material, not only energy consumption is excessive but also LiCoO ₂ , a positive electrode active material, is difficult to be purely screened. Have

In Korean Patent No. 2000-0055084, a lithium-transition metal oxide, which is a cathode active material, is peeled from a cathode plate of a lithium ion battery, burned at a temperature in the range of 400 ° C to 1,000 ° C, washed with water, and then washed with water. After dissolving in an aqueous acid solution of carboxylic acid, an alkali metal salt or alkaline earth metal salt of carboxylic acid such as oxalic acid or formic acid was added to the resulting solution to form a carboxylic acid-transition metal salt, which was then heated in a reducing atmosphere. A method of obtaining cobalt powder is shown. In addition, Korean Patent No. 2001-0107390 discloses a process of incineration of a waste lithium secondary battery from which lithium halide salts have been removed, followed by pulverization, physical separation and removal of iron and ground debris from the obtained ground product, and removal of iron and ground debris. The pulverized product is placed in an aqueous strong acid solution, and a redox agent is added thereto to dissolve the metal component, the obtained solution is filtered, and the primary filtrate obtained by the filtration is allowed to stand for a certain period of time, followed by the addition of strong alkali to pH 3 to 4.5. The method of neutralizing, the process of filtering the obtained solution, and the method of precipitating cobalt by adding sodium carbonate to the obtained secondary filtrate so that pH of a secondary filtrate becomes 8-10 are shown. However, these methods also have the disadvantage that aluminum is completely dissolved in the inorganic acid during the dissolution process, so that aluminum cannot be completely removed in a subsequent process.

In Korean Patent No. 2003-0004657, LiCoO ₂ powder is dissolved in an aqueous solution in which inorganic acid and hydrogen peroxide are dissolved, followed by addition of oxalic acid to precipitate cobalt in the form of cobalt oxalate, to recover cobalt, and to add lithium carbonate to the filtrate. A method of recovering is provided. However, this method has a disadvantage in that it is not possible to effectively separate valuable metals such as cobalt and lithium in the case of containing aluminum, iron, copper, etc. other impurities other than LiCoO ₂ powder.

In the conventional methods, aluminum and the like are mixed in the sorting and dissolving process, and precipitation and filtration characteristics are decreased in the subsequent process, so that the recovery rate of cobalt and lithium is lowered. It has a long time disadvantage. In addition, it is necessary to use a treatment method suitable for a separate metal when treating the electrode material containing not only the recovery of lithium but also other rare valuable metal components.

Accordingly, the present inventors have improved the process of separating and recovering cobalt and lithium, which are expensive metals, from the waste lithium ion secondary battery, thereby minimizing the generation of waste acid and waste alkali generated during a series of recovery processes and recovering them in a shorter time. In order to improve the recovery rate of valuable metals and to improve the economic efficiency, efforts were made to develop a recovery method.

As a result, aluminum was dissolved and separated using caustic soda and additives before leaching the waste lithium ion secondary battery with inorganic acids, minimizing the process load due to aluminum in the subsequent process, and significantly reducing the input of neutralizer in the two-stage neutralization process. In addition, it was possible to efficiently separate metals such as iron, aluminum, and copper, and also to increase the recovery of cobalt through the repulping process, and to recover high purity cobalt by recovering only pure cobalt from other impurities in the solvent extraction process. there was.

Accordingly, an object of the present invention is to provide a method for recovering valuable metals such as cobalt from a waste lithium ion secondary battery in an environmentally sound and economical manner with high purity.

1 is a process chart showing a process for recovering valuable metals such as cobalt and lithium from waste lithium ion batteries with high efficiency according to a preferred embodiment of the present invention.

Referring to FIG. 1, the present invention is an aluminum dissolving process (S101) for separating aluminum into a liquid phase using caustic soda and additives from waste lithium ion secondary battery scraps, and ii) dissolving the residue with inorganic acids and redox agents. Inorganic acid leaching step (S102), iii) adding neutralizing agent to the dissolved residue, adjusting the pH to 3.0 ~ 4.5, and then solidifying liquid separation to separate iron and aluminum (S103), 강) strong alkali is added Secondary neutralization step (S105) for separating copper and the like from pH 4.8 to 5.6, iii) repulping step (S107) for treating dissolved residues, and iii) solvent extraction step (S106) for separating lithium and cobalt. do. The waste lithium ion secondary battery scrap is a collective term for a slurry containing cobalt generated in a battery production process, a defective battery, and a battery discarded after use.

Referring to the present invention in more detail as follows.

In the aluminum dissolving step (S101), the battery scrap is added with a strong alkali solution to dissolve the aluminum, and the aluminum is separated into an aqueous solution, and lithium cobalt oxide and carbon are precipitated to separate the aluminum. Alkali used when dissolving aluminum is used sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium triphosphate (Na ₃ PO ₄ ), preferably 5-15% sodium hydroxide solution. If the concentration of cobalt hydroxide is too low, the leaching time of aluminum is long, and if the concentration is too high, part of the cobalt is leached.

Scheme 1

2Al + NaOH + H ₂ O → 2NaAlO ₂ + 3H ₂

NaAlO ₂ + H ₂ O → Al (OH) ₃ + NaOH

As an additive that inhibits the precipitation of aluminum and prevents the formation of aluminum hydroxide, sorbitol, gluconic acid, sodium gluconate, glucamines, and the like may be used. Preferably, sodium gluconate (1-5%) is used. Add. At this time, the alkaline waste liquid containing aluminum may be used as a flocculant in the wastewater treatment process.

In the acid dissolving step (S102), the inorganic acid and the redox agent are added to leave the carbon and leave the metal component. The pH is raised to 2 degrees. It is preferable to use sulfuric acid (H ₂ SO ₄ ) and hydrochloric acid (HCl) as the inorganic acid, and as an additive, hydrogen peroxide (H ₂ O ₂ ), perchloric acid (HClO ₄ ) sodium thiosulfate (Na ₂ S ₂ O ₃ ), and the like are used. . The higher the concentration of the inorganic acid is preferable, the higher the pH of the final leachate can reduce the consumption of the neutralizing agent in the subsequent neutralization step, it is preferred to be at least two. After dissolution, the residue is again leached with a mixture of strong acid and hydrogen peroxide to leach out all unreacted cobalt.

In the first neutralization step (S103), the residue and the liquid are not separated, and the pH is adjusted to 3.0 to 4.5 by adding phosphoric acid and caustic soda, followed by leaching iron and aluminum, followed by vacuum filtration (suction filtration) (S104). In order to minimize the amount of phosphoric acid used, it is preferable to add phosphoric acid at a pH of 3.0 to 4.0. More preferably, when the pH reaches 3.5, phosphoric acid is added.

In the second neutralization step (S105), in order to separate the copper and other metal components in the solution, the pH is raised to 5.6, and then filtered through a filter press. Sodium hydroxide and cobalt carbonate are used as neutralizing agents. Cobalt carbonate has an effect of maintaining a constant concentration of cobalt in the solution to be added to the solvent extraction process afterwards, minimizing the amount of neutralizing agent.

The repulping process (S107) is to dissolve the residue by adding a strong acid and an additive, and then stepwise through the first neutralization step (S103) and the second neutralization step (S105) or to use it again as a solution after suction filtration. When dissolving the secondary battery scrap with an inorganic acid, it is desirable to increase the pH as much as possible in order to minimize the input of the neutralizing agent in the subsequent process, and the pH after the final dissolution is preferably 2-3. However, when dissolving in this way, the cobalt contained in the battery scrap is not completely dissolved, and the overall yield is lowered. Therefore, it is essential to reprocess the residue after dissolution, and when reprocessing the residue, it is desirable to increase the acidity as much as possible to completely dissolve cobalt. However, if the residue after-solution dissolved in strong acid is neutralized as it is, there is a problem that the input amount of the neutralizing agent is excessive, it is preferable to reuse it when dissolving.

In the solvent extraction step (S106), the neutralizing solution is mixed with an organic solvent containing PC88A and TBP, and cobalt and lithium are separated into an organic solution and an aqueous solution, respectively, and cobalt is precipitated in the form of cobalt sulfate and lithium is lithium carbonate. do. The cobalt extracted organic solution was reacted with 0.05M sulfuric acid solution, the cobalt was stripped into an aqueous solution, and the aqueous solution was added with Na ₂ CO ₃ to precipitate lithium as Li ₂ CO ₃ .

Finally, in the waste liquid treatment process, aluminum solution is added to the waste liquid after the solvent extraction to raise the pH to 7 and then remove the remaining phosphoric acid after neutralization.

Such a present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

Example 1 Aluminum Melting Process

200 g of the battery scrap (cobalt content 45%) from the battery production process was added sodium gluconate to 1 liter of 5% sodium hydroxide solution, and then aluminum was dissolved while stirring by injecting air. The concentration of sodium gluconate was adjusted to 1, 3, 5%. After the reaction was completed, the residue was washed with 2 liters of water and then leached into 1 M sulfuric acid solution. The concentrations of aluminum in the solution were 1230 mg / L, 245 mg / L and 95 mg / L, respectively.

Example 2: Recovery of Cobalt from Cell Scrap

200 g of the battery scrap (cobalt content 45%) from the battery production process was put in 1 liter of 5% sodium hydroxide solution, and air was injected to dissolve aluminum while stirring. After the reaction was completed, the residue after suction filtration was washed with 2 liters of water and then leached with 1 M sulfuric acid solution to recover 62% of cobalt. The pH of the final solution was 2.1.

Example 3: Recovery of Cobalt from Dissolution Residue

After leaching as in Example 1), the remaining residue was filtered and leached again by adding 5% hydrogen peroxide to 1M sulfuric acid solution, whereby 95% of cobalt was recovered. The pH of the final solution was 2.1.

According to the recovery method according to the present invention as described above it can be recovered a high resource value of cobalt and lithium from the waste lithium ion secondary battery is considered to contribute significantly to the recycling of rare metal resources. In particular, because cobalt is a rare metal with a scarcity of resource, recycling of waste has a significant meaning in resource strategy. Furthermore, the valuable metal recovery method provided by the present invention has high economical efficiency, environmentally soundness, and excellent operability, and thus has a profound effect on the recycling field of waste lithium ion secondary batteries.

1 is a basic process diagram for explaining the present invention.

Claims (2)

(Iii) an alkali dissolving step of dissolving and removing the thin film lithium secondary battery scrap generated in the production process by dissolving aluminum in a reactor containing sodium hydroxide and an additive; (Ii) an acid dissolving step of leaching the filtered residue after dissolution into a sulfuric acid solution to separate cobalt; (Iii) a repulping step of leaching the residue after dissolving the acid into a solution containing an inorganic acid and a redox agent; (Iii) a first neutralization step of neutralizing and filtering the pH to 4.0 under conditions including the residue after the dissolution process; (Iii) a second neutralization step of neutralizing the solution after the first neutralization by filtration at a pH of 5.6 in a neutralization tank; (Iii) a solvent extraction step of producing cobalt sulfate and the like by subjecting the secondary neutralization solution to solvent extraction; Method of recovering valuable metals from a lithium ion secondary battery, characterized in that the progress. Method of using sorbitol, gluconic acid, sodium gluconate, glucamines, etc. as an additive in the alkali dissolving process of claim 1 to about 1-5%.