A method for recycling lithium from waste batteries

Abstract

The present invention discloses a method for recycling lithium from waste batteries, comprising the following steps: step S1: immersing electrode material slurry in an alkaline aldehyde solution, reacting for a period of time, and washing with water to obtain a valuable metal hydroxide precipitate and a lithium-containing solution by solid-liquid separation; step S2: adding sodium carbonate to the lithium-containing solution, and performing solid-liquid separation to obtain industrial-grade lithium carbonate; step S3: dissolving the valuable metal hydroxide precipitate with a sulfuric acid solution, and performing solid-liquid separation to obtain a solution containing nickel, cobalt, and manganese ions. Compared with the prior art that uses an acid leaching method, the present invention uses an alkaline leaching method, which has a good leaching effect and can produce a variety of valuable by-products. In particular, metallic copper will not dissolve under moderately alkaline conditions, and the copper element can be recovered, thereby increasing the value of direct valuable by-products.

Description

Technical Field

[0001] The invention relates to the technical field of waste battery material recycling, and in particular to a method for recycling lithium from waste batteries. Background Art

[0002] With the strong support of national policies, the production and sales of new energy vehicles in my country have increased sharply. With the rapid development of new energy, a large number of scrapped / retired power lithium-ion batteries have attracted widespread attention. When the capacity of the power battery of a new energy vehicle decays to less than 80%, the power battery cannot meet the power requirements of the electric vehicle and needs to be scrapped / retired. These scrapped / retired power batteries will inevitably become one of the main urban solid wastes in my country in the future. The nickel, cobalt, manganese, lithium and other metal elements in waste power batteries have very important economic value. Recycling them will definitely bring considerable economic benefits. At present, many companies are also conducting research in this area. There are currently two main methods for recycling waste batteries, one is repair and the other is hydrometallurgical recycling. Among them, the latter is the method currently used more in China. Technicians in this field have conducted a lot of research, for example:

[0003] Invention patent CN105742744B discloses a method for extracting lithium from a lithium-containing waste liquid generated in the recycling process of waste lithium-ion batteries. The patent uses Na2CO3 as a precipitant, adds Na2CO3 to the lithium-containing waste liquid to precipitate lithium; later mixed with MnCO3 for roasting treatment, and finally the lithium is recovered in the form of spinel lithium manganese oxide. This method has a high lithium recovery rate, is clean and environmentally friendly, and has a wide variety of products. However, the patent does not involve the recovery of other elements, and there may even be other impurity elements.

[0004] Invention patent CN110835117A discloses a method for selectively extracting lithium from waste ternary positive electrode materials. The patent obtains a lithium-rich solution by mixing waste ternary positive electrode material powder with acid and roasting it, then mixing it with an auxiliary agent and roasting it, and finally leaching it in water. This method reduces the cost of lithium extraction, simplifies the process, and solves the problem of high acid and alkali consumption in lithium recovery. However, the patent involves multi-step roasting, high energy consumption, more mixed acid in the early stage, high cost, and is not conducive to practical application.

[0005] Invention patent CN112079369A discloses a method for preferentially extracting lithium and synergistically recovering manganese from waste lithium-ion batteries. The patent grinds the positive active material and carbonaceous material of the waste battery finely, adds a chlorinating agent and roasts to obtain roasted sand, then adds water to the roasted sand and filters it, and adds H2SO4 to the filtrate to obtain CaSO4 and filtrate, further adds NaOH to the filtrate to obtain Mn(OH)2 and filtrate, and finally adds Na2CO3 to the filtrate to obtain battery-grade Li2CO3. The patent advances the transformation of Li2CO3 to the roasting stage, which can solve the problem of incomplete transformation of Li2CO3 during the water immersion process, reduce lithium loss, and recover part of Mn. However, in this process, sulfuric acid is used to precipitate Ca in the early stage, and alkali is used to precipitate Mn in the later stage. Therefore, a large amount of alkali and acid must be consumed in the early stage to complete the neutralization reaction, and an excessive amount of alkali is required to complete the precipitation of Mn, which is bound to increase the consumption of alkali and increase the cost. At the same time, the patent only involves the synergistic recovery of Mn, and does not involve the recovery of other elements, such as Co, Ni, etc.

[0006] Invention patent CN112522513A discloses a method for selectively extracting lithium from retired lithium batteries. The patent grinds the waste positive electrode active material and activator and then puts them into a tubular furnace for activation. Later, lithium is extracted by leaching to obtain a Li-enriched solution, and then carbonates and / or phosphates are added to the enriched solution to obtain lithium carbonate and / or lithium phosphate. The patent uses an activator to increase the reaction activity of lithium, with a high extraction rate and a simple process. However, the recovery of other elements is not involved, resulting in the mixing of other metal elements, which in turn leads to impure lithium carbonate and / or lithium phosphate.

[0007] Invention patent CN112374511A discloses a method for recycling waste ternary lithium batteries to prepare lithium carbonate and ternary precursors. The patent uses graphite and binder from waste ternary batteries as reducing agents, destroys the structure of ternary materials through self-reduction phase transformation; uses carbonation water leaching to convert lithium carbonate into lithium bicarbonate that is easy to be leached in water, and preferentially extracts lithium; the material after lithium extraction is directly leached with sulfuric acid to obtain nickel-cobalt-manganese solution. The patent has a high recovery rate for valuable metals lithium, nickel, cobalt, and manganese, a short process, good product quality, and is economical and environmentally friendly. However, its recovery process is relatively complicated. At the same time, since lithium bicarbonate is easily soluble in water, the recovery rate of Li in the form of lithium bicarbonate is bound to be not too high. Summary of the invention

[0008] In view of the above-mentioned defects of the prior art, the present invention provides a method for recovering lithium from waste batteries.

[0009] The present invention provides a method for recycling lithium from waste batteries, comprising the following steps:

[0010] Step S1: immersing the electrode material slurry in an alkaline aldehyde solution, reacting for a period of time, and then washing the solid and liquid to obtain a copper element, a valuable metal hydroxide precipitate and a lithium-containing solution;

[0011] Step S2: adding sodium carbonate to the lithium-containing solution to separate the solid and liquid to obtain industrial-grade lithium carbonate;

[0012] Step S3: drying the copper element and the valuable metal hydroxide precipitate, and then sieving them to separate the copper element and the valuable metal hydroxide precipitate, dissolving the valuable metal hydroxide precipitate with a sulfuric acid solution, and performing solid-liquid separation to obtain a solution containing nickel, cobalt and manganese ions.

[0013] Preferably, the method further comprises step S0: slowly adding waste electrode powder into a certain amount of pure water until fully mixed to obtain the electrode material slurry.

[0014] Furthermore, the waste electrode powder is positive and negative electrode powder of one or more of waste ternary batteries, waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries, and waste nickel-hydrogen batteries.

[0015] Furthermore, the liquid-to-solid ratio of pure water to waste electrode powder is 2 to 10:1.

[0016] Preferably, in step S1, the aldehyde in the alkaline aldehyde solution is formaldehyde and / or acetaldehyde.

[0017] Preferably, in step S1, the concentration of aldehyde in the alkaline aldehyde solution is 2-15%.

[0018] Preferably, in step S1, the concentration of alkali in the alkaline aldehyde solution is 2-20%.

[0019] Preferably, in step S1, the base used in preparing the alkaline aldehyde solution is lithium hydroxide and / or sodium hydroxide.

[0020] Preferably, in step S1, the solid-liquid separation adopts plate and frame filtration and negative pressure filtration.

[0021] Furthermore, in step S1, the solid-liquid separation is performed by plate and frame filter pressing.

[0022] Preferably, in step S1, the copper element and the valuable metal hydroxide precipitate obtained after solid-liquid separation are washed multiple times, and the wastewater generated by the first washing is used for the preparation of the electrode material slurry; the wastewater generated by the washing after the first washing is used for the previous washing; and pure water is used for the last washing.

[0023] Furthermore, the number of times of washing with water is 3 to 5 times.

[0024] Furthermore, the washing time is 5 to 20 minutes.

[0025] Preferably, step S1 is a closed operation.

[0026] Preferably, in step S3, the concentration of the sulfuric acid solution is 1-6 mol / L.

[0027] The present invention adopts the above technical solution, and has the following technical effects compared with the prior art:

[0028] (1) Compared with the prior art which uses acid leaching, the present invention uses alkaline leaching, which has a good leaching effect and can produce a variety of valuable by-products. In particular, metallic copper will not dissolve under moderately alkaline conditions, and the copper element can be recovered, thereby increasing the value of direct valuable by-products.

[0029] (2) Aldehydes exhibit strong reducing properties under alkaline conditions. The present invention uses an alkaline solution of aldehydes to reduce high-valent metals in the battery core powder, such as changing +3-valent Co to +2-valent and +4-valent Mn to +2-valent, thereby disintegrating the crystal structure of the powder and releasing lithium ions and valuable metal ions. The recovery of valuable metal ions is more thorough and the effect is better.

[0030] (3) The present invention adopts circulating countercurrent water washing to maximize the water utilization efficiency and reduce the water usage. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flow chart of a method for recovering lithium from waste batteries. DETAILED DESCRIPTION

[0032] Most of the existing retired lithium battery recycling technologies add reducing substances such as hydrogen peroxide and sulfite to an acidic system to extract valuable metals, leach them under acidic conditions, and dissolve a large amount of impurity metals. Many chemical species are required, the process is complicated, and multiple steps of impurity removal are required in the later stage.

[0033] In view of the above-mentioned defects of the prior art, the present invention provides a leaching method in an alkaline environment, which has good leaching effect and can produce a variety of valuable by-products. In particular, metallic copper will not dissolve under moderately alkaline conditions, and the copper element can be recovered, thereby increasing the value of direct valuable by-products and greatly reducing the cost of recycling waste batteries.

[0034] Based on the fact that formaldehyde and acetaldehyde show strong reducing properties under alkaline conditions, the alkaline solution of aldehyde is used to reduce the high-valent metals in the battery core powder, such as +3-valent Co becomes +2-valent, and +4-valent Mn becomes +2-valent, so that the crystal structure of the powder is disintegrated, lithium ions and valuable metal ions are released, and the valuable metal ions are recovered. The present invention provides a method for recovering lithium from waste batteries, comprising the following steps:

[0035] Step S0: adding a certain amount of pure water or the waste water generated by the first water washing in step S1 into the reactor, turning on the stirring and self-circulating device of the reactor, and slowly adding a certain amount of waste electrode powder to prevent the generation of a large amount of dust and avoid a large amount of powder floating on the liquid surface due to uneven stirring. After the addition is completed, continue stirring for 10 to 20 minutes to fully mix the materials to obtain electrode material slurry;

[0036] Step S1: immersing the electrode material slurry in an alkaline aldehyde solution, reacting for 30 to 120 minutes, separating the solid and the liquid, and washing with water for multiple times to obtain a copper element, a valuable metal hydroxide precipitate and a lithium-containing solution;

[0037] Step S2: adding sodium carbonate to the lithium-containing solution to separate the solid and liquid to obtain industrial-grade lithium carbonate;

[0038] Step S3: drying the copper element and the valuable metal hydroxide precipitate, and then sieving to separate the copper element and the valuable metal hydroxide precipitate, the material on the sieve is the copper element, dissolving the valuable metal hydroxide precipitate with sulfuric acid solution, and performing solid-liquid separation to obtain a solution containing nickel, cobalt and manganese ions.

[0039] In a specific embodiment, the waste electrode powder is positive and negative electrode powder of one or more of waste ternary batteries, waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries, and waste nickel-hydrogen batteries.

[0040] In a preferred embodiment, the liquid-to-solid ratio of pure water or waste water generated by the first water washing in step S1 to the waste electrode powder is 2 to 10:1.

[0041] In a specific embodiment, in step S1, the alkaline aldehyde solution includes formaldehyde and / or acetaldehyde; the concentration of aldehyde in the alkaline aldehyde solution is 2-15%; the concentration of alkali in the alkaline aldehyde solution is 2-20%; the alkali used in the preparation of the alkaline aldehyde solution is lithium hydroxide and / or sodium hydroxide.

[0042] In a preferred embodiment, in step S1, the solid-liquid separation adopts plate and frame filter pressing and negative pressure filtration; further preferably, the solid-liquid separation adopts plate and frame filter pressing.

[0043] In a preferred embodiment, in step S1, the number of water washings is 3 to 5 times; the water washing time is 5 to 20 minutes. The wastewater generated by the first water washing is used for the preparation of electrode material slurry, and the wastewater generated by the water washing after the first water washing is used for the previous water washing. The last water washing uses pure water, the number of water washings is 3 to 5 times, and the water washing time is controlled at 5 to 20 minutes. The present invention adopts circulating countercurrent water washing to maximize the use efficiency of water and reduce the amount of water used.

[0044] In a preferred embodiment, step S1 is a closed operation to prevent aldehyde substances from volatilizing and polluting the environment.

[0045] In a specific embodiment, in step S3, the concentration of the sulfuric acid solution is 1-6 mol / L.

[0046] In the present invention, the recovery rate of lithium is 90-99%, the recovery rate of nickel, cobalt and manganese is 90-98%, and the recovery rate of copper is 90-98%.

[0047] The present invention is described in detail and specifically by specific examples below to provide a better understanding of the present invention, but the following examples do not limit the scope of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for recycling lithium from waste batteries, such as Figure 1 The following steps are included:

[0050] Step S0: adding a certain amount of pure water or the wastewater generated by the first water washing in step S1 into the reactor, turning on the stirring and self-circulating device of the reactor, and slowly adding a certain amount of ternary positive electrode material powder, wherein the liquid-to-solid ratio of water to the ternary positive electrode material powder is 3:1, and continuing to stir for 10 to 20 minutes after the addition is completed to fully mix the materials to obtain electrode material slurry;

[0051] Step S1: immersing the electrode material slurry in an alkaline formaldehyde solution, wherein the concentration of formaldehyde is controlled at 12%, and the concentration of sodium hydroxide is controlled at 15%. After reacting for 60 minutes, solid-liquid separation and water washing are performed 5 times to obtain copper element, valuable metal hydroxide precipitate and lithium-containing solution, and the water washing time is controlled at 15 minutes;

[0052] Step S2: adding sodium carbonate to the lithium-containing solution to precipitate lithium, and performing solid-liquid separation to obtain industrial-grade lithium carbonate (battery-grade lithium carbonate);

[0053] Step S3: drying the copper element and the valuable metal hydroxide precipitate, and then sieving them to separate the copper element and the valuable metal hydroxide precipitate. The material on the sieve is the copper element. The valuable metal hydroxide precipitate is dissolved in a sulfuric acid solution with a concentration of 2 mol / L. The solid-liquid separation is performed to obtain a solution containing nickel, cobalt and manganese ions. The slag is carbon powder.

[0054] In this embodiment, the recovery rate of lithium is 98%, the recovery rate of nickel, cobalt and manganese is 98%, and the recovery rate of copper is 98%.

[0055] Example 2

[0056] This embodiment provides a method for recycling lithium from waste batteries, such as Figure 1 The following steps are included:

[0057] Step S0: adding a certain amount of pure water or the wastewater generated by the first water washing in step S1 into the reactor, turning on the stirring and self-circulating device of the reactor, and slowly adding a certain amount of ternary positive electrode material powder, wherein the liquid-to-solid ratio of water to the ternary positive electrode material powder is 4:1, and continuing to stir for 10 to 20 minutes after the addition is completed to fully mix the materials to obtain electrode material slurry;

[0058] Step S1: immersing the electrode material slurry in an alkaline acetaldehyde solution, wherein the concentration of acetaldehyde is controlled at 8%, and the concentration of sodium hydroxide is controlled at 20%. After reacting for 30 minutes, solid-liquid separation and water washing are performed 4 times to obtain copper element, valuable metal hydroxide precipitate and lithium-containing solution, and the water washing time is controlled at 20 minutes;

[0059] Step S2: adding sodium carbonate to the lithium-containing solution to precipitate lithium, and performing solid-liquid separation to obtain industrial-grade lithium carbonate (battery-grade lithium carbonate);

[0060] Step S3: drying the copper element and the valuable metal hydroxide precipitate, and then sieving them to separate the copper element and the valuable metal hydroxide precipitate. The material on the sieve is the copper element. The valuable metal hydroxide precipitate is dissolved in a sulfuric acid solution with a concentration of 2 mol / L. The solid-liquid separation is performed to obtain a solution containing nickel, cobalt and manganese ions. The slag is carbon powder.

[0061] In this embodiment, the recovery rate of lithium is 99%, the recovery rate of nickel, cobalt and manganese is 98%, and the recovery rate of copper is 98%.

[0062] Comparative Example 1

[0063] This comparative example provides a method for recovering lithium from waste batteries, comprising the following steps:

[0064] Step S0: adding a certain amount of pure water or the waste water generated by the first water washing in step S1 into the reactor, turning on the stirring and self-circulating device of the reactor, and slowly adding a certain amount of ternary positive electrode material powder, wherein the liquid-to-solid ratio of water to the ternary positive electrode material powder is 12:1, and continuing to stir for 10 to 20 minutes after the addition is completed to fully mix the materials to obtain electrode material slurry;

[0065] Step S1: immersing the electrode material slurry in an alkaline formaldehyde solution, wherein the concentration of formaldehyde is controlled at 12%, and the concentration of sodium hydroxide is controlled at 15%. After reacting for 60 minutes, solid-liquid separation and water washing are performed 5 times to obtain copper element, valuable metal hydroxide precipitate and lithium-containing solution, and the water washing time is controlled at 15 minutes;

[0066] Step S2: adding sodium carbonate to the lithium-containing solution to precipitate lithium, and performing solid-liquid separation to obtain industrial-grade lithium carbonate (battery-grade lithium carbonate);

[0067] Step S3: drying the copper element and the valuable metal hydroxide precipitate, and then sieving them to separate the copper element and the valuable metal hydroxide precipitate. The material on the sieve is the copper element. The valuable metal hydroxide precipitate is dissolved in a sulfuric acid solution with a concentration of 2 mol / L. The solid-liquid separation is performed to obtain a solution containing nickel, cobalt and manganese ions. The slag is carbon powder.

[0068] In this embodiment, the recovery rate of lithium is 92%, the recovery rate of nickel, cobalt and manganese is 98%, and the recovery rate of copper is 95%.

[0069] Comparative Example 2

[0070] This comparative example provides a method for recycling lithium from waste batteries, such as Figure 1 The following steps are included:

[0071] Step S0: adding a certain amount of pure water or the wastewater generated by the first water washing in step S1 into the reactor, turning on the stirring and self-circulating device of the reactor, and slowly adding a certain amount of ternary positive electrode material powder, wherein the liquid-solid ratio of water to the ternary positive electrode material powder is 1:1, and continuing to stir for 10 to 20 minutes after the addition is completed to fully mix the materials to obtain electrode material slurry;

[0072] Step S1: immersing the electrode material slurry in an alkaline formaldehyde solution, wherein the concentration of formaldehyde is controlled at 12%, and the concentration of sodium hydroxide is controlled at 15%. After reacting for 60 minutes, solid-liquid separation and water washing are performed 5 times to obtain copper element, valuable metal hydroxide precipitate and lithium-containing solution, and the water washing time is controlled at 15 minutes;

[0073] Step S2: adding sodium carbonate to the lithium-containing solution to precipitate lithium, and performing solid-liquid separation to obtain industrial-grade lithium carbonate (battery-grade lithium carbonate);

[0074] Step S3: drying the copper element and the valuable metal hydroxide precipitate, and then sieving them to separate the copper element and the valuable metal hydroxide precipitate. The material on the sieve is the copper element. The valuable metal hydroxide precipitate is dissolved in a sulfuric acid solution with a concentration of 2 mol / L. The solid-liquid separation is performed to obtain a solution containing nickel, cobalt and manganese ions. The slag is carbon powder.

[0075] In this embodiment, the recovery rate of lithium is 87%, the recovery rate of nickel, cobalt and manganese is 89%, and the recovery rate of copper is 90%.

[0076] Comparative Example 3

[0077] This embodiment provides a method for recycling lithium from waste batteries, comprising the following steps:

[0078] Step S0: adding a certain amount of pure water or the wastewater generated by the first water washing in step S1 into the reactor, turning on the stirring and self-circulating device of the reactor, and slowly adding a certain amount of ternary positive electrode material powder, wherein the liquid-to-solid ratio of water to the ternary positive electrode material powder is 3:1, and continuing to stir for 10 to 20 minutes after the addition is completed to fully mix the materials to obtain electrode material slurry;

[0079] Step S1: immersing the electrode material slurry in an alkaline formaldehyde solution, wherein the concentration of formaldehyde is controlled at 18%, and the concentration of sodium hydroxide is controlled at 15%. After reacting for 60 minutes, solid-liquid separation and water washing are performed 5 times to obtain copper element, valuable metal hydroxide precipitate and lithium-containing solution, and the water washing time is controlled at 15 minutes;

[0080] Step S2: adding sodium carbonate to the lithium-containing solution to precipitate lithium, and performing solid-liquid separation to obtain industrial-grade lithium carbonate (battery-grade lithium carbonate);

[0081] Step S3: drying the copper element and the valuable metal hydroxide precipitate, and then sieving them to separate the copper element and the valuable metal hydroxide precipitate. The material on the sieve is the copper element. The valuable metal hydroxide precipitate is dissolved in a sulfuric acid solution with a concentration of 2 mol / L. The solid-liquid separation is performed to obtain a solution containing nickel, cobalt and manganese ions. The slag is carbon powder.

[0082] In this embodiment, the recovery rate of lithium is 88%, the recovery rate of nickel, cobalt and manganese is 98%, and the recovery rate of copper is 92%.

[0083] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A method for recovering lithium from waste batteries, characterized in that: The following steps are involved: Step S1: immersing the electrode material slurry in an alkaline aldehyde solution, reacting for a period of time, and then washing the solid and liquid to obtain a copper element, a valuable metal hydroxide precipitate and a lithium-containing solution; Step S2: adding sodium carbonate to the lithium-containing solution to separate the solid and liquid to obtain industrial-grade lithium carbonate; Step S3: drying the copper element and the valuable metal hydroxide precipitate, then sieving them to separate the copper element and the valuable metal hydroxide precipitate, dissolving the valuable metal hydroxide precipitate with a sulfuric acid solution, and performing solid-liquid separation to obtain a solution containing nickel, cobalt, and manganese ions; The method further comprises step S0: slowly adding waste electrode powder into a certain amount of pure water until the mixture is fully mixed to obtain the electrode material slurry; Wherein, in step S1, the copper element and the valuable metal hydroxide precipitate obtained after solid-liquid separation are washed multiple times, and the waste water generated by the first washing is used for the preparation of the electrode material slurry; the waste water generated by the washing after the first washing is used for the previous washing; and the last washing is washed with pure water; Wherein, in step S1, the aldehyde in the alkaline aldehyde solution is formaldehyde and / or acetaldehyde.

2. The method for recovering lithium from waste batteries according to claim 1, characterized in that: The waste electrode powder is one or more of the positive and negative electrode powders of waste ternary batteries, waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries, and waste nickel-hydrogen batteries.

3. The method for recovering lithium from waste batteries according to claim 1, characterized in that: The liquid-to-solid ratio of pure water and waste electrode powder is 2~10:

1.

4. The method for recovering lithium from waste batteries according to claim 1, characterized in that: In step S1, the concentration of aldehyde in the alkaline aldehyde solution is 2-15%.

5. The method for recovering lithium from waste batteries according to claim 1, characterized in that: In step S1, the concentration of alkali in the alkaline aldehyde solution is 2-20%.

6. The method for recovering lithium from waste batteries according to claim 1, characterized in that: In step S1, the base used in preparing the alkaline aldehyde solution is lithium hydroxide and / or sodium hydroxide.

7. The method for recovering lithium from waste batteries according to claim 1, characterized in that: In step S1, the solid-liquid separation adopts plate and frame filter pressing and negative pressure filtration.

8. The method for recovering lithium from waste batteries according to claim 1, characterized in that: Step S1 is a closed operation.

9. The method for recovering lithium from waste batteries according to claim 1, characterized in that: In step S3, the concentration of the sulfuric acid solution is 1-6 mol / L.

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