TWI863507B - Method for recovering valuable metals in lithium-ion batteries - Google Patents

Abstract

The present invention provides a method and equipment for recovering valuable metals in lithium-ion batteries. The method for recovering valuable metals in lithium-ion batteries sequentially comprises a material detection step, an alkaline leaching step, an acid leaching step, a metal replacement step, an iron removal step, a nickel and manganese recovery step, a cobalt recovery step, and a lithium recovery step. The equipment for recovering valuable metals in lithium-ion batteries comprises: an alkaline leaching device, an acid leaching device, a copper removal device, an iron removal device, a nickel and manganese recovery device, a cobalt recovery device, and a lithium recovery device. The method and equipment for recovering valuable metals in lithium-ion batteries of the present invention can remove impurity metals such as aluminum, copper and iron from the carbon ink powder of the positive electrode material in the discarded lithium-ion batteries, and recover valuable metals such as nickel, manganese, cobalt and lithium.

Description

Methods for recovering valuable metals in lithium-ion batteries

The present invention relates to a method and apparatus for recovering valuable metals in lithium-ion batteries, and in particular to a method and apparatus for removing impurity metals such as aluminum, copper and iron from discarded lithium-ion batteries and recovering valuable metals such as nickel, manganese, cobalt and lithium from lithium-ion batteries.

After lithium-ion batteries were successfully introduced into the market, they are widely used in various 3C products, energy storage equipment and even electric vehicles around the world due to their relatively light weight, small size and long life. However, lithium-ion batteries contain valuable metals such as lithium, cobalt, nickel and manganese. If they are discarded arbitrarily after use, it is easy to cause heavy metal pollution to the environment and even change the environment ecology. As environmental awareness has risen and environmental protection issues have also received universal attention, the industry or academia has also developed resource recycling technology. Currently known methods for recycling valuable metals are as follows.

Taiwan invention patent I286850 (hereinafter referred to as document 1) discloses that the positive electrode part where lithium and cobalt are located is soaked in hydrochloric acid for two hours, and then the pH value of the soaking solution is adjusted to 8 with sodium hydroxide. Then, the gel containing cobalt, aluminum and nickel can be separated by filtration. Finally, a saturated sodium carbonate solution is added to the soaking solution to obtain lithium carbonate powder. The gel containing cobalt, aluminum and nickel obtained by filtration is first washed with sulfuric acid and the pH value is adjusted to 2. After the metals are dissolved, ammonia water is added to adjust the pH value to 8 to filter out the gelatin containing aluminum ions. Finally, the pH value of the filtered pickling solution is adjusted to 4.3 with sulfuric acid and poured into the electrolytic cell for electrolytic recovery. The electrolyte temperature is maintained at 55°C using a constant temperature water bath. After a fixed current is passed, cobalt and nickel metals will be deposited on the cathode stainless steel sheet. After drying, cobalt and nickel metals can be recovered to achieve the purpose of waste resource recycling. In other words, Document 1 uses electrolysis to obtain cobalt and nickel.

Taiwan Invention Patent No. 501294 (hereinafter referred to as Document 2) discloses that the used waste lithium-ion batteries are roasted in a high-temperature furnace to decompose and remove the organic electrolytes, and then crushed and screened. The screened materials can be treated with magnetic separation and eddy current separation to separate the broken iron shells, copper foils and aluminum foils; while the screened materials are treated with sulfuric acid and peroxide. The solution is etched with a mixture of hydrogen and filtered, and the solution obtained by the etching is then precipitated by adjusting the acid-base value. During the process, metallic copper and metallic cobalt are electrolyzed respectively by electrolysis. After the electrolysis, the solution rich in lithium ions is added with carbonate to form lithium carbonate precipitation, thereby effectively recovering lithium. In other words, Reference 2 also uses electrolysis to obtain cobalt.

Taiwan Invention Patent No. 511306 (hereinafter referred to as Document 3) discloses that waste lithium-ion batteries are roasted in a high-temperature furnace to decompose and remove organic electrolytes, and then crushed and screened. The screened materials are then treated with magnetic separation and eddy current separation to separate the broken iron shell, copper foil and aluminum foil, etc.; while the screened materials are directly dissolved and filtered, and by controlling the pH value and electrolytic conditions, metallic copper and cobalt are electrolyzed by diaphragm electrolysis. The acid generated on the cathode side during the electrolysis process can be recovered through diffusion dialysis treatment and recycled to the dissolution step for use, forming a closed process. After the electrolysis, the solution rich in lithium ions can be added with carbonate to form high-purity lithium carbonate to recover lithium after adjusting the pH value to precipitate metal impurities. In other words, Reference 3 also uses electrolysis to obtain cobalt.

Taiwan Invention Patent No. I392745 (hereinafter referred to as Document 4) is limited to slurry composed of ternary lithium metal salt and solvents such as carbon, N-methyl-2-pyrrolidone, polyvinyl alcohol, etc., which is the slag produced in the manufacturing step of lithium secondary batteries. The metal composition in the slurry is generally 10~12 mass% Co, 10~12 mass% Ni, 10~12 mass% Mn, 4~5 mass% Li, that is, in addition to limiting Co, Ni, and Mn to equal amounts, there is no treatment method for impurities such as aluminum, copper, and iron. Document 4 discloses that a lithium battery residue containing a ternary lithium metal salt (containing approximately equal amounts of cobalt, nickel and manganese) is stirred and leached with a hydrochloric acid solution having a concentration of 250 g/l or more, or stirred and leached with a sulfuric acid solution having a concentration of 200 g/l or more while being heated to 65-80°C, or stirred and leached with a mixture of a sulfuric acid solution having a concentration of 200 g/l or more and a 20 g/l or more sulfuric acid solution. After being stirred and leached with the above hydrogen peroxide solution, the leaching solution is subjected to solvent extraction with a special extractant, such as DE2HPA extractant for manganese and PC-88A extractant for cobalt and nickel, to extract more than 98% of the three metals manganese, cobalt and nickel to generate a solution containing each metal, and then the valuable metals such as manganese, cobalt, nickel and lithium are recovered from these solutions and the residual liquid containing lithium after extraction. In other words, although document 4 does not use the electrolysis method of documents 1 to 3, it cannot handle the problem of handling impurity metals such as aluminum, copper, and iron that must be faced in the lithium battery recycling process, and solvent extraction must be performed with a special extractant.

From the above-mentioned references 1 to 4, it can be found that references 1 to 3 all use electrolysis, which consumes a lot of electricity and leads to high costs, while reference 4 uses a special extractant for solvent extraction, which will cause environmental problems, and reference 4 cannot handle the treatment of impurity metals such as aluminum, copper, and iron.

In view of the above-mentioned known problems, the inventor of the present invention has thought about and designed a method and device for recovering valuable metals from carbon ink powder of the positive electrode material of discarded lithium-ion batteries, in order to improve the deficiencies of the known technology and further promote its implementation and utilization in the industry.

Based on the above purpose, the present invention provides a method for recovering valuable metals in lithium ion batteries, which sequentially comprises a material detection step, an alkaline leaching step, an acid leaching step, a metal replacement step, an iron removal step, a nickel and manganese recovery step, a cobalt recovery step, and a lithium recovery step.

The material testing step is to analyze the metal content of carbon ink powder, one of the positive electrode materials from the discarded lithium-ion battery, to obtain the content values of lithium, nickel, cobalt, manganese, aluminum, copper and iron. The carbon ink powder also contains carbon.

The alkaline leaching step is to mix an alkaline aqueous solution with the carbon ink powder, so that the lithium, nickel, cobalt, manganese, copper, iron and carbon in the carbon ink powder are precipitated into a first filter residue, wherein the aluminum is dissolved in the alkaline aqueous solution to form a first aqueous solution, and the first aqueous solution is removed to retain the first filter residue.

The acid leaching step is to mix an acidic aqueous solution with the first filter slag, so that the lithium, nickel, cobalt, manganese, copper and iron in the first filter slag are dissolved in the acidic aqueous solution to form a second aqueous solution, and the carbon in the first filter slag is precipitated to form a second filter slag. The second filter slag is removed and the second aqueous solution is retained.

The metal replacement step is to mix the second aqueous solution with an additional iron-containing substance, and the equivalent number of iron in the additional iron-containing substance is greater than the equivalent number of copper in the second aqueous solution or the equivalent number of copper in the carbon ink powder, so that the copper in the copper sulfate in the second aqueous solution is replaced by iron to become iron sulfate and copper metal is precipitated, so that the second aqueous solution is converted into a third aqueous solution, and the precipitated copper metal is precipitated into a third filter residue, and the third filter residue is removed and the third aqueous solution is retained.

The iron removal step is to adjust the pH value of the third aqueous solution to between 4 and 5 with a first alkaline substance, so that the iron of the iron sulfate in the third aqueous solution forms a first alkaline compound with the first alkaline substance and precipitates the first alkaline compound to turn the third aqueous solution into a fourth aqueous solution. The precipitated first alkaline compound is an iron compound and precipitates into a fourth filter residue. The fourth filter residue is removed and the fourth aqueous solution is retained. The nickel and manganese recovery step is to remove the fourth The aqueous solution is adjusted with a second alkaline substance to a pH value between 6 and 8 and a carbonate is added, so that the nickel in the nickel sulfate and the manganese in the manganese sulfate in the fourth aqueous solution react with the carbonate to form nickel carbonate and manganese carbonate, and the nickel carbonate and the manganese carbonate are precipitated to convert the fourth aqueous solution into a fifth aqueous solution. The precipitated nickel carbonate and the manganese carbonate are precipitated into a fifth filter residue, and the fifth filter residue is separated and the fifth aqueous solution is retained; The step of recovering cobalt is to treat the fifth aqueous solution with a third After the alkaline substance is adjusted to a pH value between 11 and 13, the cobalt in the cobalt sulfate in the fifth aqueous solution forms a third alkaline compound with the third alkaline substance and the third alkaline compound is precipitated to convert the fifth aqueous solution into a sixth aqueous solution. The precipitated third alkaline compound is a cobalt compound and precipitates into a sixth filter residue. The sixth filter residue is separated and the sixth aqueous solution is retained; the lithium recovery step is to mix the sixth aqueous solution with phosphate, and the phosphate in the phosphate is The equivalent number of ions is greater than the equivalent number of lithium in the sixth aqueous solution or the equivalent number of lithium in the carbon ink powder. The phosphate undergoes a double decomposition reaction with the lithium sulfate in the sixth aqueous solution, so that the lithium in the lithium sulfate in the sixth aqueous solution is exchanged for the metal in the phosphate due to the double decomposition reaction to become a water-soluble sulfate and lithium phosphate is precipitated to convert the sixth aqueous solution into a seventh aqueous solution. The precipitated lithium phosphate is precipitated into a seventh filter residue. The seventh aqueous solution is removed and the seventh filter residue is retained.

The present invention also provides a valuable metal recovery device for lithium-ion batteries, which is used to implement the aforementioned valuable metal recovery method for lithium-ion batteries. The valuable metal recovery device for lithium-ion batteries includes: an alkaline leaching device, an acid leaching device, a copper removal device, an iron removal device, a nickel-manganese recovery device, a cobalt recovery device, and a lithium recovery device.

Thus, the present invention first removes impurity metals such as aluminum, copper, iron and carbon from carbon ink powder, and then achieves the purpose of separating and recovering valuable metals lithium, nickel, cobalt and manganese by collecting nickel carbonate and manganese carbonate, cobalt hydroxide or cobalt oxide, and lithium phosphate. Therefore, the purpose of accurately separating valuable metals from carbon ink powder of lithium ion battery can be achieved, and no electrolysis or special extractant is used in the separation process.

P: Pipeline system

S00: Material testing steps

S10: Alkaline immersion step

S20: Acid leaching step

S30: Metal replacement step

S40: Iron removal step

S50: Nickel and manganese recovery step

S60: Cobalt recovery step

S70: Lithium recovery step

100: Equipment for recovering valuable metals in lithium-ion batteries

1: Alkaline leaching device

11: Alkaline leaching tank

12: First stirring device

13: First filter device

14: Aluminum salt tank

2: Acid leaching device

21: Acid leaching tank

22: Second stirring device

23: Second filter device

3: Copper removal device

31: Copper removal tank

32: The third stirring device

33: The third filter device

4:Iron removal device

41:Iron removal tank

42: The fourth stirring device

43: The fourth filter device

5: Nickel and manganese recovery device

51: Nickel and manganese recovery tank

52: Fifth stirring device

53: Fifth filter device

6: Cobalt recovery device

61: Cobalt recovery tank

62: Sixth stirring device

63: Sixth filter device

7: Lithium recovery device

71: Lithium recovery tank

72: Seventh stirring device

73: Seventh filter device

Figure 1 is a flow chart of the method for recovering valuable metals in the lithium-ion battery of the present invention.

Figure 2 is a schematic diagram of the valuable metal recovery equipment in the lithium-ion battery of the present invention.

In order to facilitate understanding of the technical features, content and advantages of the present invention and the effects that can be achieved, the present invention is described in detail with the accompanying drawings as follows. The drawings used therein are only for illustration and auxiliary description purposes, and may not be the actual proportions and precise configurations after the implementation of the present invention. Therefore, the proportions and configurations of the attached drawings should not be interpreted to limit the scope of rights of the present invention in actual implementation.

Please refer to Figure 1. The method for recovering valuable metals in lithium-ion batteries of the present invention sequentially includes a material detection step S00, an alkaline leaching step S10, an acid leaching step S20, a metal replacement step S30, an iron removal step S40, a nickel and manganese recovery step S50, a cobalt recovery step S60, and a lithium recovery step S70. Among them, the material testing step S00, alkaline leaching step S10, acid leaching step S20, metal replacement step S30 and iron removal step S40 are collectively referred to as the impurity metal removal step, and the nickel and manganese recovery step S50, cobalt recovery step S60 and lithium recovery step S70 are collectively referred to as the valuable metal separation step.

Material testing step S00: The carbon ink powder of the positive electrode material taken from the discarded lithium ion battery is analyzed for metal content in the carbon ink powder to obtain the content values of lithium, nickel, cobalt, manganese, aluminum, copper and iron therein. The carbon ink powder also contains carbon. The lithium ion battery disassembly process can refer to the aforementioned references 1 to 4, so it is not repeated here. The present invention is to separate the impurity metal and the valuable metal from the carbon ink powder of the positive electrode material in the discarded lithium ion battery in sequence. In the present invention, the material testing step refers to the atomic absorption spectroscopy (AAS) analysis performed after obtaining the carbon ink powder. For example, in one embodiment, the contents (weight percentage) of lithium, nickel, cobalt and manganese in the carbon ink powder are measured to be 2.92%, 4.04%, 15.97% and 5.12%, respectively; the rest include aluminum, copper, iron, lead, zinc, chromium, calcium, sodium and magnesium, and the contents are 30320ppm, 15710ppm, 23940ppm, 436ppm, 3504ppm, 804ppm, 622ppm, 2641ppm and 496ppm, respectively. Therefore, in the present invention, valuable metals refer to lithium, nickel, cobalt and manganese; impurity metals refer to aluminum, copper and iron; other metals such as lead, zinc, chromium, calcium, sodium and magnesium are ignored due to their small contents. In other words, the material testing step refers to the metal content analysis of the carbon ink powder after obtaining the carbon ink powder to obtain the content values of lithium, nickel, cobalt, manganese, aluminum, copper and iron. Of course, the carbon ink powder also contains carbon.

Alkaline leaching step S10: or also called aluminum removal step, after mixing an alkaline aqueous solution (e.g., sodium hydroxide aqueous solution) with carbon ink powder, stirring at a first predetermined temperature for a first predetermined time, so that lithium, nickel, cobalt, manganese, copper, iron and carbon in the carbon ink powder are precipitated into a first slag, aluminum is dissolved in the alkaline aqueous solution to form a first aqueous solution, and the first aqueous solution is removed to retain the first slag. In the present invention, the alkaline leaching step refers to using an alkaline substance to adjust the pH value of the solution to greater than 12; preferably, the pH value is 13. The alkaline substance includes sodium hydroxide and ammonia water, preferably sodium hydroxide, and more preferably, a sodium hydroxide aqueous solution with a concentration of 5%, 10%, 15%, 20%, 25%, 30% by weight. The conditions of the alkaline leaching step, including the alkaline substance used, pH value, heating temperature, heating time, solid-liquid ratio, can be adjusted according to the content of the carbon ink powder and/or each metal therein, and are not subject to theoretical constraints. The equation for the alkaline leaching step may be Al ₂ O ₃ +2NaOH→2NaAlO ₂ +H ₂ O. For example, the carbon black powder mainly contains lithium, nickel, cobalt, manganese, aluminum, copper, iron and carbon, and the remaining substances are negligible. Basically, for the purpose of complete reaction, the equivalent number of alkali (e.g., the molar number of hydroxide ions) in the alkaline aqueous solution is greater than the equivalent number of aluminum. In one embodiment, the alkaline leaching step is to use a sodium hydroxide aqueous solution with a weight of 10 times that of the carbon ink powder and a concentration of 10% and mix it with the carbon ink powder, and then stir it at a predetermined temperature for a predetermined time, then Al ₂ O ₃ in the carbon ink powder will form NaAlO ₂ and dissolve in the sodium hydroxide aqueous solution to form a first aqueous solution, and the rest containing lithium, nickel, cobalt, manganese, copper, iron and carbon will not dissolve in the sodium hydroxide aqueous solution and precipitate as a first slag. In other words, the alkaline leaching step causes the aluminum in the carbon ink powder to form an aluminum salt and dissolve in water, while lithium, nickel, cobalt, manganese, copper, iron and carbon form metal-containing carbon powder and precipitate as the first slag. Furthermore, the first aqueous solution is removed and the first slag is retained.

Acid leaching step S20: or carbon removal step, after mixing an acidic aqueous solution (e.g., sulfuric acid aqueous solution) with the first filter slag, stirring at a second predetermined temperature for a second predetermined time, the lithium, nickel, cobalt, manganese, copper and iron in the first filter slag are dissolved in the acidic aqueous solution to form a second aqueous solution, and the carbon in the first filter slag is precipitated to form a second filter slag, and the second filter slag is removed to retain the second aqueous solution. In the present invention, the acid leaching step refers to using an acidic substance to adjust the pH value of the solution to less than 4, preferably, the pH value is 0.5. The acidic substance includes sulfuric acid, nitric acid or hydrochloric acid, preferably sulfuric acid, and more preferably 5%, 10%, 15%, 20%, 25%, 30% sulfuric acid. The conditions of the acid leaching step, including the acidic substance used, pH value, heating temperature, heating time, solid-liquid ratio, can be adjusted according to the content of the carbon ink powder and/or each metal therein, and are not subject to theoretical constraints. The equation of the acid leaching step can be Co/Ni/Mn/Li/Fe/Cu/C+H ₂ SO ₄ →CoSO ₄ /NiSO ₄ /MnSO ₄ /Li ₂ SO ₄ /Fe ₂ (SO ₄ ) ₃ /CuSO ₄ +C. For example, the first slag produced by the aforementioned alkaline leaching step contains lithium, nickel, cobalt, manganese, copper, iron and carbon. Basically, for the purpose of complete reaction, the equivalent number of sulfate ions in the acidic aqueous solution is greater than the sum of the equivalent numbers of lithium, nickel, cobalt, manganese, copper and iron. In one embodiment, the acid leaching step is to use a sulfuric acid aqueous solution with a weight of 10 times that of the carbon ink powder and a concentration of 20% and mix it with the first filter residue, and then stir it at a second predetermined temperature for a second predetermined time. In particular, in order to facilitate measurement and avoid measurement errors caused by water in the first filter residue, the acid leaching step is to use a sulfuric acid aqueous solution with a weight of 10 times that of the carbon ink powder and a concentration of 20%, instead of using a sulfuric acid aqueous solution with a weight of 10 times that of the first filter residue and a concentration of 20%. From the above equation of the alkaline leaching step, it can be known that the lithium, nickel, cobalt, manganese, copper and iron originally in the first filter residue form lithium sulfate, nickel sulfate, cobalt sulfate, manganese sulfate, copper sulfate and iron sulfate respectively and dissolve in the acidic aqueous solution to form the second aqueous solution, while the carbon originally in the first filter residue does not react with sulfuric acid to form sulfate, and thus precipitates into the second filter residue that does not contain lithium, nickel, cobalt, manganese, copper and iron, or is called carbon residue or graphite residue. In addition, the second filter residue is removed and the second aqueous solution is retained.

The aforementioned solid-liquid ratio refers to the weight ratio of the solid to the liquid. The solid-liquid ratio can be 5, 10, 15, 20, which means that the weight of the liquid is 5 times, 10 times, 15 times, and 20 times the weight of the solid respectively; the aforementioned and the following heating temperature or the predetermined temperature can be room temperature 25°C (unheated), 60°C, 70°C, 80°C or 90°C; the aforementioned and the following heating time or the predetermined time can be 2 hours, 4 hours, 6 hours, 8 hours or 10 hours.

Regarding the aforementioned metal replacement step, in the present invention, the metal replacement step refers to adding an excess of other metals so that the excess of other metals replaces the metal to be obtained or removed. The excess ratio means that the equivalent number of other metals is 1.05 times, 1.1 times, 1.15 times, 1.2 times, 1.25 times or 1.3 times the equivalent number of metals to be obtained or removed. The condition for the metal replacement reaction is the activity sequence of the metal. The equation of the metal replacement step in the present invention can be _3CuSO4 +2Fe→ _Fe2 ( _SO4 ) ₃ +3Cu.

Metal replacement step S30: or copper removal step, is to mix the second aqueous solution with an additional iron-containing substance (e.g., iron powder) and stir at a third predetermined temperature for a third predetermined time. The equivalent of iron in the additional iron-containing substance (iron powder) is greater than the equivalent of copper in the second aqueous solution or the equivalent of copper in the carbon black powder, so that the copper in the copper sulfate in the second aqueous solution is replaced by iron to become iron sulfate and copper metal is precipitated, so that the second aqueous solution is converted into a third aqueous solution, and the precipitated copper metal is precipitated as a third slag, and the third slag is removed to retain the third aqueous solution. In the present invention, the metal replacement step refers to making the pH value of the second aqueous solution less than 4 (e.g., adding acidic sulfuric acid) and mixing the second aqueous solution with an additional iron-containing substance (e.g., iron powder). The metal replacement step may be formulated as 3CuSO ₄ +2Fe→Fe ₂ (SO ₄ ) ₃ +3Cu. In one embodiment, the metal replacement step is to mix the second aqueous solution with iron powder, wherein the equivalent of iron in the iron powder is 1.2 times the equivalent of copper in the second aqueous solution or the equivalent of copper in the carbon black powder. From the above formula of the metal replacement step, it can be seen that under the condition of a pH value less than 4, the copper in the copper sulfate in the second aqueous solution is replaced by iron to become iron sulfate and copper metal is precipitated to become the third aqueous solution, and the precipitated copper metal is precipitated as the third slag. Then, the third slag is removed and the third aqueous solution is retained. Therefore, the third aqueous solution contains lithium sulfate, nickel sulfate, cobalt sulfate, manganese sulfate and iron sulfate, and the copper of the copper sulfate originally in the second aqueous solution is precipitated as the third slag.

The above-mentioned iron removal step, nickel and manganese recovery step, and cobalt recovery step refer to the precipitation of metals in different pH environments after adjusting the pH value in the present invention. The present invention includes the iron removal step, nickel and _manganese recovery step, and _cobalt recovery step. The equations for the iron removal step, _nickel and manganese recovery step, and _cobalt recovery step can be _Fe2 ( _SO4 ) _{3 +} 6NaOH→2Fe( _OH ) ₃ + _3Na2SO4 , NiSO4+ _Na2CO3 →NiCO3+Na2SO4, _MnSO4 + _Na2CO3 → _MnCO3 + _{Na2SO4 ,} and CoSO4 ₊ NaOH→Co(OH) ₂ + _{Na2SO4 , respectively .}

Iron removal step S40: The third aqueous solution is adjusted to a pH value between 4 and 5 (preferably, a pH value of 4.5) with a first alkaline substance (e.g., sodium hydroxide) and then stirred at a fourth predetermined temperature for a fourth predetermined time, so that the iron of the iron sulfate in the third aqueous solution forms a first alkaline compound (e.g., iron hydroxide) with the first alkaline substance and precipitates the first alkaline compound (e.g., iron hydroxide) to convert the third aqueous solution into a fourth aqueous solution. The precipitated first alkaline compound is an iron compound (e.g., iron hydroxide) and precipitates into a fourth filter residue. The fourth filter residue is removed to retain the fourth aqueous solution. The formula for the iron removal step can be Fe ₂ (SO ₄ ) ₃ +6NaOH→2Fe(OH) ₃ +3Na ₂ SO ₄ . It can be seen from the equation of the above-mentioned iron removal step that under the condition that the pH value is between 4 and 5, in one embodiment, the first alkaline substance is sodium hydroxide, and the iron of the iron sulfate originally in the third aqueous solution forms iron hydroxide with hydroxide ions and precipitates iron hydroxide precipitate (fourth filter residue), so that the third aqueous solution is converted into a fourth aqueous solution, and the fourth filter residue is removed and the fourth aqueous solution is retained. Therefore, the fourth aqueous solution contains lithium sulfate, nickel sulfate, cobalt sulfate and manganese sulfate, and the iron of the iron sulfate originally in the third aqueous solution is precipitated as iron hydroxide precipitate (fourth filter residue).

The nickel and manganese recovery step S50 is to adjust the fourth aqueous solution to a pH value between 6 and 8 (preferably, a pH value of 7) with a second alkaline substance (e.g., sodium hydroxide), add carbonate (e.g., sodium carbonate), and stir the solution at a fifth predetermined temperature for a fifth predetermined time, so that nickel in nickel sulfate and manganese in manganese sulfate in the fourth aqueous solution react with carbonate to form nickel carbonate and manganese carbonate, and nickel carbonate and manganese carbonate are precipitated to convert the fourth aqueous solution into a fifth aqueous solution. The precipitated nickel carbonate and manganese carbonate are precipitated to form a fifth filter residue, and the fifth filter residue is separated and the fifth aqueous solution is retained. The equations for the step of recovering nickel and manganese can be NiSO ₄ +Na ₂ CO ₃ →NiCO ₃ +Na ₂ SO ₄ , MnSO ₄ +Na ₂ CO ₃ →MnCO ₃ +Na ₂ SO ₄ . From the above equations for the step of recovering nickel and manganese, it can be seen that under the condition of a pH value between 6 and 8, in one embodiment, the carbonate is sodium carbonate, the nickel of the nickel sulfate and the manganese of the manganese sulfate originally in the fourth aqueous solution react with the carbonate to form nickel carbonate and manganese carbonate, and nickel carbonate and manganese carbonate are precipitated to convert the fourth aqueous solution into a fifth aqueous solution, and the precipitated nickel carbonate and manganese carbonate are precipitated as a fifth sludge, the fifth sludge is separated and the fifth aqueous solution is retained, so that the fifth aqueous solution contains lithium sulfate and cobalt sulfate.

The cobalt recovery step S60 is to adjust the fifth aqueous solution to a pH value between 11 and 13 (preferably, a pH value of 12) with an alkaline substance (such as sodium hydroxide), and then stir it at a sixth predetermined temperature for a sixth predetermined time, so that the cobalt in the cobalt sulfate in the fifth aqueous solution forms an alkaline compound (such as cobalt hydroxide) with the alkaline substance and precipitates the alkaline compound (such as cobalt hydroxide), so that the fifth aqueous solution is converted into a sixth aqueous solution, and the precipitated alkaline compound is a cobalt compound (such as cobalt hydroxide) and precipitates into a sixth filter residue, and the sixth filter residue is separated and the sixth aqueous solution is retained. The equation for the cobalt recovery step can be CoSO ₄₊ NaOH→Co(OH) ₂ +Na ₂ SO ₄ . It can be known from the above equation of the cobalt recovery step that under the condition of pH value between 11 and 13, in one embodiment, the alkaline substance is sodium hydroxide, the cobalt of the cobalt sulfate originally in the fifth aqueous solution forms cobalt hydroxide with hydroxide ions and precipitates cobalt hydroxide precipitate (sixth filter residue), and the fifth aqueous solution is converted into the sixth aqueous solution, the sixth filter residue is separated and the sixth aqueous solution is retained, so the sixth aqueous solution contains lithium sulfate, and the cobalt of the cobalt sulfate originally in the fifth aqueous solution is precipitated as cobalt hydroxide precipitate (sixth filter residue). Of course, the cobalt hydroxide precipitate (sixth filter residue) can also be heated and dried to be converted into cobalt oxide.

The lithium recovery step S70 is to mix the sixth aqueous solution with phosphate (e.g. sodium phosphate) and stir the mixture at a seventh predetermined temperature for a seventh predetermined time. The equivalent number of phosphate ions in the phosphate (e.g. sodium phosphate) is greater than the equivalent number of lithium in the sixth aqueous solution or the equivalent number of lithium in the carbon ink powder. The phosphate and the lithium sulfate in the sixth aqueous solution undergo a double decomposition reaction, so that the lithium in the lithium sulfate in the sixth aqueous solution is exchanged for the metal (e.g. sodium) in the phosphate (e.g. sodium phosphate) due to the double decomposition reaction to become a water-soluble sulfate (e.g. sodium sulfate), and lithium phosphate is precipitated to convert the sixth aqueous solution into a seventh aqueous solution. The precipitated lithium phosphate is precipitated as a seventh filter residue. The seventh aqueous solution is removed and the seventh filter residue is retained. In the present invention, the lithium recovery step refers to mixing the sixth aqueous solution with phosphate (e.g., sodium phosphate). The equation for the lithium recovery step may be 3Li ₂ SO ₄ +2Na ₃ PO ₄ →2Li ₃ PO ₄ +3Na ₂ SO ₄ . In one embodiment, the lithium recovery step is mixing the sixth aqueous solution with sodium phosphate, wherein the equivalent number of phosphate ions in the sodium phosphate is 1.2 times the equivalent number of lithium in the sixth aqueous solution or the equivalent number of lithium in the carbon ink powder. From the above equation for the lithium recovery step, it can be seen that the lithium in the lithium sulfate in the original sixth aqueous solution is exchanged for the sodium in the sodium phosphate to become water-soluble sodium sulfate and lithium phosphate is precipitated to convert the sixth aqueous solution into the seventh aqueous solution. The precipitated lithium phosphate is precipitated to form the seventh filter residue. The seventh aqueous solution is removed and the seventh filter residue is retained.

Therefore, the present invention first removes impurity metals such as aluminum, copper, iron and carbon from the carbon black powder, and then achieves the purpose of separating and recovering valuable metals lithium, nickel, cobalt and manganese by collecting nickel carbonate and manganese carbonate from the fifth filter slag, cobalt hydroxide or cobalt oxide from the sixth filter slag, and lithium phosphate from the seventh filter slag.

The present invention also provides a valuable metal recovery device for lithium-ion batteries, which is used to implement the aforementioned valuable metal recovery method for lithium-ion batteries.

Please refer to Figure 2, the recovery equipment 100 for valuable metals in lithium-ion batteries, which includes: alkaline leaching device 1, acid leaching device 2, copper removal device 3, iron removal device 4, nickel and manganese recovery device 5, cobalt recovery device 6 and lithium recovery device 7.

The alkali leaching device 1 comprises an alkali leaching tank 11, a first stirring device 12 disposed in the alkali leaching tank 11, a first filtering device 13 connected to the bottom of the alkali leaching tank 11 via a pipeline system P, and an aluminum salt tank 14 connected to the first filtering device 13 via the pipeline system P. The alkali leaching device 1 is used to implement the alkali leaching step S10. After a sodium hydroxide aqueous solution with a weight of 10 times that of the carbon ink powder and a concentration of 10% is mixed with the carbon ink powder in the alkali leaching tank 11, it is stirred by a first stirring device 12 at a first predetermined temperature of 80° C. for a first predetermined time of 4 hours to form a first aqueous solution and a first filter residue. After the reaction is completed, the pipeline system P at the bottom of the alkali leaching tank 11 is opened to transport the first aqueous solution and the first filter residue in the alkali leaching tank 11 to the first filtering device 13. The first filtering device 13 separates the first aqueous solution and the first filter residue, and stores the first aqueous solution in the aluminum salt tank 14. Among them, the carbon ink powder is weighed to be 1000Kg (kilograms), and according to the atomic absorption spectroscopic analysis results in the aforementioned material testing step S00, the carbon ink powder is converted to obtain 29.2Kg of lithium, 40.4Kg of nickel, 159.7Kg of cobalt and 51.2Kg of manganese.

The acid leaching device 2 includes an acid leaching tank 21 connected to the first filtering device 13 by a pipeline system P to receive the first filtered residue, a second stirring device 22 disposed in the acid leaching tank 21, and a second filtering device 23 connected to the bottom of the acid leaching tank 21 by the pipeline system P. The acid leaching device 2 is used to implement the acid leaching step S20. After a sulfuric acid aqueous solution with a weight of 10 times that of the carbon black powder and a concentration of 20% is mixed with the first filter residue in the acid leaching tank 21, it is stirred by the second stirring device 22 at a second predetermined temperature of 80°C for a second predetermined time of 8 hours to form a second aqueous solution and a second filter residue. After the reaction is completed, the pipeline system P at the bottom of the acid leaching tank 21 is opened to transport the second aqueous solution and the second filter residue in the acid leaching tank 21 to the second filtering device 23, and the second filtering device 23 separates the second aqueous solution and the second filter residue.

The copper removal device 3 includes a copper removal tank 31 connected to the second filtering device 23 by a pipeline system P to receive the second aqueous solution, a third stirring device 32 disposed in the copper removal tank 31, and a third filtering device 33 connected to the bottom of the copper removal tank 31 by the pipeline system P. The copper removal device 3 is used to implement the metal replacement step S30. In the copper removal tank 31, the pH value of the second aqueous solution is made less than 4 and mixed with iron powder, wherein the equivalent number of iron in the iron powder is 1.2 times the equivalent number of copper in the second aqueous solution or the equivalent number of copper in the carbon black powder. The third predetermined temperature is stirred at room temperature by the third stirring device 32 for a third predetermined time of 4 hours to form a third aqueous solution and a third filter residue. After the reaction is completed, the pipeline system P at the bottom of the copper removal tank 31 is opened to transport the third aqueous solution and the third filter residue in the copper removal tank 31 to the third filter device 33, and the third filter device 33 separates the third aqueous solution and the third filter residue.

The iron removal device 4 includes an iron removal tank 41 connected to the third filtering device 33 by a pipeline system P to receive the third aqueous solution, a fourth stirring device 42 disposed in the iron removal tank 41, and a fourth filtering device 43 connected to the bottom of the iron removal tank 41 by the pipeline system P. The iron removal device 4 is used to implement the iron removal step S40. Sodium hydroxide is used in the iron removal tank 41 to make the pH value of the third aqueous solution 4.5. The fourth predetermined temperature is room temperature and the fourth predetermined time is 4 hours. The fourth stirring device 42 is used to stir to form a fourth aqueous solution and a fourth filter residue. After the reaction is completed, the pipeline system P at the bottom of the iron removal tank 41 is opened to transport the fourth aqueous solution and the fourth filter residue in the iron removal tank 41 to the fourth filter device 43. The fourth filter device 43 separates the fourth aqueous solution and the fourth filter residue.

The nickel-manganese recovery device 5 includes a nickel-manganese recovery tank 51 connected to the fourth filtering device 43 by a pipeline system P to receive the fourth aqueous solution, a fifth stirring device 52 disposed in the nickel-manganese recovery tank 51, and a fifth filtering device 53 connected to the bottom of the nickel-manganese recovery tank 51 by the pipeline system P. The nickel-manganese recovery device 5 is used to implement the nickel and manganese recovery step S50. In the nickel-manganese recovery tank 51, sodium hydroxide is used to make the pH value of the fourth aqueous solution 7, and the fifth predetermined temperature is 80°C, and the fifth predetermined time is 4 hours. The fifth aqueous solution and the fifth filter residue are formed. After the reaction is completed, the pipeline system P at the bottom of the nickel-manganese recovery tank 51 is opened to transport the fifth aqueous solution and the fifth filter residue in the nickel-manganese recovery tank 51 to the fifth filter device 53, and the fifth filter device 53 separates the fifth aqueous solution and the fifth filter residue. The fifth filter residue is nickel carbonate and manganese carbonate. The weight of the filter residue is 180.3Kg. After atomic absorption spectrometry analysis, the nickel is 38.58Kg and the manganese is 48.9Kg. Divided by the nickel and manganese content of the carbon ink powder (nickel is 40.4Kg and manganese is 51.2Kg), the recovery rate of nickel and manganese is 96%.

The cobalt recovery device 6 includes a cobalt recovery tank 61 connected to the fifth filtering device 53 by a pipeline system P to receive the fifth aqueous solution, a sixth stirring device 62 disposed in the cobalt recovery tank 61, and a sixth filtering device 63 connected to the bottom of the cobalt recovery tank 61 by the pipeline system P. The cobalt recovery device 6 is used to implement the cobalt recovery step S60. Sodium hydroxide is used in the cobalt recovery tank 61 to make the pH value of the fifth aqueous solution 12. The sixth predetermined temperature is 80° C. and the sixth predetermined time is 8 hours. The sixth stirring device 62 is used to stir to form a sixth aqueous solution and a sixth filter residue. After the reaction is completed, the pipeline system P at the bottom of the cobalt recovery tank 61 is opened to transport the sixth aqueous solution and the sixth filter residue in the cobalt recovery tank 61 to the sixth filter device 63. The sixth filter device 63 separates the sixth aqueous solution and the sixth filter residue. The sixth filter residue is cobalt hydroxide, and the weight of the filter residue is 240.55Kg. The cobalt content calculated by atomic absorption spectrometry is 152.5Kg. Divided by the cobalt content of carbon ink powder 159.7Kg, the cobalt recovery rate is 95%

The lithium recovery device 7 includes a lithium recovery tank 71 connected to the sixth filter device 63 by a pipeline system P to receive the sixth aqueous solution, a seventh stirring device 72 disposed in the lithium recovery tank 71, and a seventh filter device 73 connected to the bottom of the lithium recovery tank 71 by the pipeline system P. The lithium recovery device 7 is used to implement the lithium recovery step S70. After the sixth aqueous solution is mixed with sodium phosphate in the lithium recovery tank 71, the equivalent number of phosphate ions in the sodium phosphate is 1.2 times the equivalent number of lithium in the sixth aqueous solution or the equivalent number of lithium in the carbon ink powder. The seventh predetermined temperature is 70°C and the seventh predetermined time is 4 hours to form the seventh aqueous solution and the seventh filter residue. After the reaction is completed, the pipeline system P at the bottom of the lithium recovery tank 71 is opened to transport the seventh aqueous solution and the seventh filter residue in the lithium recovery tank 71 to the seventh filter device 73. The seventh filter device 73 separates the seventh aqueous solution and the seventh filter residue. The seventh filter residue is lithium phosphate, and its weight is 155.1Kg. The lithium content is calculated by atomic absorption spectrometry to be 27.9Kg. Divided by the lithium content of carbon ink powder (29.2Kg), the lithium recovery rate is 96%

It is particularly noted that the first filter device 13, the second filter device 23, the third filter device 33, the fourth filter device 43, the fifth filter device 53, the sixth filter device 63 and the seventh filter device 73 of the present invention can be plate-frame filter presses, also known as plate presses. The first stirring device 12, the second stirring device 22, the third stirring device 32, the fourth stirring device 42, the fifth stirring device 52, the sixth stirring device 62 and the seventh stirring device 72 can be blade stirrers.

The method and equipment for recovering valuable metals in lithium-ion batteries of the present invention can effectively separate valuable metals without using electrolytic reaction and special extracting agent. Furthermore, the present invention first removes impure metals such as aluminum, copper, iron and carbon in carbon black powder, and then achieves the purpose of separating and recovering valuable metals such as lithium, nickel, cobalt and manganese by collecting nickel carbonate and manganese carbonate from the fifth filter slag, cobalt hydroxide or cobalt oxide from the sixth filter slag, and lithium phosphate from the seventh filter slag. In addition, the present invention first removes impure metals such as aluminum, copper, iron and carbon in carbon black powder, so the recovery rate of valuable metals recovered subsequently can be as high as 95% or more.

The above-mentioned embodiments are only for illustrating the technical ideas and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. They cannot be used to limit the patent scope of the present invention. In other words, any equivalent changes or modifications made according to the spirit disclosed by the present invention should still be covered by the patent scope of the present invention.

S00: Material testing steps

S10: Alkaline immersion step

S20: Acid leaching step

S30: Metal replacement step

S40: Iron removal step

S50: Nickel and manganese recovery step

S60: Cobalt recovery step

S70: Lithium recovery step

Claims (6)

A method for recovering valuable metals in lithium-ion batteries comprises: a material detection step (S00), in which a carbon ink powder, which is a positive electrode material of a discarded lithium-ion battery, is analyzed for metal content in the carbon ink powder to obtain the content values of lithium, nickel, cobalt, manganese, aluminum, copper and iron therein, wherein the carbon ink powder also contains carbon; an alkaline leaching step (S10), in which an alkaline aqueous solution is mixed with the carbon ink powder to make the carbon ink powder The lithium, nickel, cobalt, manganese, copper, iron and carbon in the powder are precipitated into a first slag, wherein the aluminum is dissolved in the alkaline aqueous solution to form a first aqueous solution, and the first aqueous solution is removed to retain the first slag; an acid leaching step (S20) is to mix an acid aqueous solution with the first slag, so that the lithium, nickel, cobalt, manganese, copper and iron in the first slag are dissolved in the acid aqueous solution to form a second aqueous solution, and the carbon in the first slag is precipitated into a second slag. , removing the second slag and retaining the second aqueous solution; a metal replacement step (S30), wherein the second aqueous solution is mixed with an additional iron-containing substance, wherein the equivalent amount of iron in the additional iron-containing substance is greater than the equivalent amount of copper in the second aqueous solution or the equivalent amount of copper in the carbon ink powder, so that the copper in the copper sulfate in the second aqueous solution is replaced by iron to become iron sulfate and copper metal is precipitated, so that the second aqueous solution is converted into a third aqueous solution, and the precipitated The copper metal is precipitated into a third filter residue, and the third filter residue is removed to retain the third aqueous solution; an iron removal step (S40) is to adjust the third aqueous solution to a pH value between 4 and 5 with a first alkaline substance, so that the iron of the iron sulfate in the third aqueous solution and the first alkaline substance form a first alkaline compound and precipitate the first alkaline compound to convert the third aqueous solution into a fourth aqueous solution, and the precipitated first alkaline compound The compound is an iron compound and precipitates into a fourth filter residue, the fourth filter residue is removed and the fourth aqueous solution is retained; a nickel and manganese recovery step (S50): the fourth aqueous solution is adjusted to a pH value between 6 and 8 by using a second alkaline substance, a carbonate is added, the nickel of the nickel sulfate and the manganese of the manganese sulfate in the fourth aqueous solution react with the carbonate to form a nickel carbonate and a manganese carbonate, and the nickel carbonate and the manganese carbonate are precipitated to convert the fourth aqueous solution into The fifth aqueous solution is formed by mixing the nickel carbonate and the manganese carbonate and precipitating them into a fifth filter residue. The fifth filter residue is separated and the fifth aqueous solution is retained. A cobalt recovery step (S60) is to adjust the fifth aqueous solution to a pH value between 11 and 13 by using a third alkaline substance, so that the cobalt in the cobalt sulfate in the fifth aqueous solution reacts with the third alkaline substance to form a third alkaline compound and precipitate the third alkaline compound to recover the fifth aqueous solution. The aqueous solution is converted into a sixth aqueous solution, the precipitated third alkaline compound is a cobalt compound and precipitates into a sixth filter residue, the sixth filter residue is separated and the sixth aqueous solution is retained; and a lithium recovery step (S70) is to mix the sixth aqueous solution with a phosphate, the equivalent number of phosphate ions in the phosphate is greater than the equivalent number of lithium in the sixth aqueous solution or the equivalent number of lithium in the carbon ink powder, so that the lithium sulfate in the sixth aqueous solution is reduced to The metal in the phosphate is exchanged to become a water-soluble sulfate and lithium phosphate is precipitated to convert the sixth aqueous solution into a seventh aqueous solution. The precipitated lithium phosphate is precipitated into a seventh filter residue. The seventh aqueous solution is removed and the seventh filter residue is retained; wherein the alkaline aqueous solution is a sodium hydroxide aqueous solution, the acidic aqueous solution is a sulfuric acid aqueous solution, and the first alkaline substance, the second alkaline substance and the third alkaline substance are sodium hydroxide. A method for recovering valuable metals in lithium-ion batteries as described in claim 1, wherein the added iron-containing substance is iron powder. A method for recovering valuable metals in lithium-ion batteries as described in claim 2, wherein the carbonate is sodium carbonate. A method for recovering valuable metals in lithium-ion batteries as described in claim 3, wherein the phosphate is sodium phosphate. The method for recovering valuable metals in lithium ion batteries as described in claim 4, wherein in the metal replacement step (S30), the second aqueous solution is mixed with iron powder, and the equivalent amount of iron in the iron powder is 1.2 times the equivalent amount of copper in the second aqueous solution or the equivalent amount of copper in the carbon ink powder. The method for recovering valuable metals in lithium-ion batteries as described in claim 5, wherein in the lithium recovery step (S70), the sixth aqueous solution is mixed with the sodium phosphate, wherein the equivalent number of phosphate ions in the sodium phosphate is 1.2 times the equivalent number of lithium in the sixth aqueous solution or the equivalent number of lithium in the carbon ink powder.

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