Method for recovering valuable metals from electrode waste

Abstract

The present invention discloses a method for recovering valuable metals from electrode waste containing nickel, cobalt, tungsten, oxygen, and lithium. The method comprises the following steps: mixing the electrode waste with a reducing agent, subjecting the waste to hot grinding or calcining in a flowing atmosphere to obtain a mixture; leaching the resulting mixture in water, separating it to obtain a lithium-containing solution and a primary filter residue; and alkali leaching the resulting primary filter residue, separating it to obtain a tungsten-containing solution and a secondary filter residue. This method solves the problem of existing technologies that prevent the effective recovery of valuable metals from tungsten-containing waste lithium-ion battery materials.

Description

Technical Field

[0001] The invention relates to the technical field of electrode waste recycling, in particular to a method for recycling valuable metals from electrode waste. Background Art

[0002] Lithium-ion batteries have many excellent properties and are widely used in mobile devices such as mobile phones and laptops. However, in order to further improve the conductivity and stability of lithium-ion batteries, high-valent metal ions are used to modify them. Lithium-ion batteries modified with lithium tungstate and tungsten oxide have significantly improved their reversible capacity, rate capability, and stability. According to preliminary statistics, the production of lithium-ion batteries increased from 1 billion in 2010 to 15.7 billion in 2019. With the scrapping and storage of a large number of lithium-ion batteries, not only will the valuable metals in them be wasted, but they will also occupy a large amount of land resources and cause long-term environmental pollution under natural conditions.

[0003] Currently, the main approaches to recycling used lithium-ion batteries are as follows: first, using reductive acid leaching, where the leachate undergoes extraction and stripping to produce a corresponding salt solution, which is then flash-evaporated to produce crystalline salts such as sulfates and chlorides; second, using an extraction-stripping process to remove impurities from the leachate, where the solution is diluted to a certain concentration before preparing a corresponding precipitate; and third, using electrodeposition to produce metal elements after extraction-stripping. While these methods can address the storage issues of used lithium-ion batteries to a certain extent, they involve complex processes and high production costs, making it difficult to achieve high-value recycling of used lithium-ion batteries. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a method for recovering valuable metals from electrode waste, thereby resolving the problem that the prior art methods cannot effectively recover valuable metals from tungsten-containing waste lithium-ion battery waste.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for recovering valuable metals from electrode waste, the method comprising the following steps:

[0007] The electrode waste is mixed with a reducing agent, and subjected to hot grinding or calcination treatment under atmospheric conditions to obtain a mixture; the mixture is soaked in water, separated, and a lithium-containing solution and a primary filter residue are obtained; and

[0008] The primary filter residue is subjected to alkaline leaching and separation to obtain a tungsten-containing solution and a secondary filter residue.

[0009] The present invention does not limit the type of electrode waste. For example, it can be electrode waste containing nickel, cobalt, tungsten, oxygen and lithium, such as at least one of nickel-cobalt-lithium tungstate ternary waste, tungsten-doped nickel-cobalt-lithium manganese state ternary waste, and lithium tungstate-coated nickel-cobalt-lithium manganese state.

[0010] Preferably, the reducing agent includes at least one of a reducing gas, carbon and a reducing metal salt.

[0011] Preferably, the reducing gas is at least one of hydrogen, carbon monoxide and methane.

[0012] Preferably, the carbon is at least one of activated carbon and coke.

[0013] Preferably, the cation elements in the reducing metal salt include at least one of nickel, cobalt and manganese, and the anion elements include S 2- , at least one of oxalate and nitrite.

[0014] Preferably, the reducing metal salt is a manganese salt.

[0015] Preferably, the manganese salt is at least one of manganese sulfide, manganese oxalate and manganese nitrite.

[0016] Preferably, the molar ratio of the electrode waste to the reducing agent is 2 to 8:1.

[0017] Preferably, the atmospheric condition is a flowing atmospheric condition.

[0018] Preferably, the gas of the flowing atmosphere is at least one of an inert gas, nitrogen, hydrogen, air and a nitrogen-oxygen mixed gas, and the volume percentage of oxygen in the nitrogen-oxygen mixed gas is less than 5%.

[0019] Preferably, the rotation speed of the hot grinding treatment is 200 rpm to 1000 rpm, and the temperature is 30° C. to 100° C.

[0020] Preferably, the calcination treatment is performed at a temperature of 200° C. to 600° C. and for a time of 10 min to 60 min.

[0021] Preferably, the liquid-to-solid ratio of the water immersion process is 3 to 10:1 L / kg, and the temperature is 20°C to 50°C.

[0022] Preferably, the leaching agent used in the alkaline leaching includes at least one of sodium carbonate, sodium bicarbonate and sodium hydroxide.

[0023] Preferably, the method further comprises the step of performing reduction acid leaching on the secondary filter residue.

[0024] Preferably, the leaching agent used in the reduction acid leaching includes an acid and a reducing component, the acid includes at least one of sulfuric acid, hydrochloric acid and phosphoric acid, and the reducing component includes at least one of hydrogen peroxide, sodium metabisulfite, sodium sulfite, oxalic acid and oxalate.

[0025] Preferably, the acid concentration is 1.5 mol / L to 2 mol / L.

[0026] Preferably, the mass content of the reducing component is 8% to 15%.

[0027] Preferably, the method further comprises the step of adjusting the pH of the tungsten-containing solution to 1-3 and blowing in oxygen or air to prepare tungstic acid precipitate.

[0028] As a further preferred technical solution of the method of the present invention, the method comprises the following steps:

[0029] The nickel-cobalt lithium tungstate waste material and a reducing manganese salt are mixed in a molar ratio of 2 to 8:1, and subjected to hot grinding or calcination treatment under flowing atmosphere conditions to obtain a mixture; the nickel-cobalt lithium tungstate waste material is: lithium nickel-cobalt tungstate obtained by modifying lithium nickel-cobalt oxide with tungsten oxide and lithium tungstate, and / or lithium nickel-cobalt tungstate waste prepared by sintering nickel-cobalt tungstate hydroxide with lithium hydroxide;

[0030] The mixed material is immersed in water, and solid-liquid separation is performed to obtain a lithium-containing solution and a nickel-cobalt-manganese-tungsten filter residue; the nickel-cobalt-manganese-tungsten filter residue is heated and alkali-leached to obtain a tungstate solution, and filtered to obtain a nickel-cobalt-manganese filter residue and a tungstate solution;

[0031] subjecting the filter residue containing nickel, cobalt and manganese to reducing acid leaching to obtain a nickel, cobalt and manganese mixed solution; and

[0032] The pH of the tungstate solution is adjusted to 1-3, and oxygen or air is introduced to obtain tungstic acid precipitation.

[0033] Advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the embodiments of the present invention. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Without departing from the principles of the embodiments of the present invention, several improvements and modifications can be made, and these improvements and modifications are also considered to be within the scope of protection of the embodiments of the present invention.

[0036] The embodiments of the present invention provide a method for recovering valuable metals from electrode waste containing nickel, cobalt, tungsten, oxygen and lithium, which is used to solve the problem that the methods in the prior art cannot effectively recover valuable metals from tungsten-containing waste lithium-ion battery waste.

[0037] An embodiment of the present invention provides a method for recovering valuable metals from electrode waste containing nickel, cobalt, tungsten, oxygen, and lithium, the method comprising the following steps:

[0038] The electrode waste is mixed with a reducing agent, and subjected to thermal grinding or calcination treatment under atmospheric conditions to obtain a mixed material;

[0039] The obtained mixture is immersed in water and separated to obtain a lithium-containing solution and a primary filter residue, and

[0040] The primary filter residue is subjected to alkaline leaching and separation to obtain a tungsten-containing solution and a secondary filter residue.

[0041] The method provided in an embodiment of the present invention is to mix the electrode waste with a reducing agent, and perform a hot grinding or calcination treatment under atmospheric conditions, so that the metal bond between tungsten and lithium is broken, and the bond between part of tungsten and oxygen is broken. If the electrode waste also contains elements such as nickel and cobalt commonly found in the electrode waste, the metal bond between elements such as nickel and cobalt and lithium can be broken, as well as the bond between part of nickel, cobalt and oxygen can be broken. In the obtained mixture, each element except lithium exists in the form of oxides, simple substances or hydroxides, while the lithium element exists in the form of lithium oxide. After the mixture is soaked in water, lithium is transferred into the solution, and separation is performed to obtain a lithium-containing solution and a primary filter residue. The primary filter residue contains tungsten. If the electrode waste contains metal elements such as nickel and cobalt, these elements will remain in the primary filter residue.

[0042] The method of the embodiment of the present invention utilizes a reducing agent and performs hot grinding or calcination treatment under atmospheric conditions to separate tungsten and lithium. If there are other metal elements commonly found in electrode waste (such as nickel, cobalt, etc.), tungsten, lithium, and other elements can be separated to obtain tungsten products, lithium products, and other metal element products.

[0043] In the embodiment of the present invention, hot grinding is preferably used to achieve the bond breaking effect. The reason is that hot grinding can effectively act on the material in all directions and effectively reduce the particle size, which is beneficial to the contact between the reducing agent and the waste material, and is beneficial to improving the subsequent element separation effect.

[0044] In the embodiment of the present invention, the steps of mixing the electrode waste with the reducing agent and hot grinding or calcining under flowing atmosphere conditions can be performed in two steps or in one step. For example, hot grinding or calcining can be performed under the flow of hydrogen, which is also a one-step process.

[0045] In an embodiment of the present invention, the electrode waste containing nickel, cobalt, tungsten, oxygen and lithium includes at least one of: nickel-cobalt-lithium tungstate ternary waste, tungsten-doped nickel-cobalt-lithium manganese oxide ternary waste, and lithium tungstate-coated nickel-cobalt-lithium manganese oxide.

[0046] In an embodiment of the present invention, the reducing agent comprises at least one of a reducing gas, carbon, and a reducing metal salt. The reducing gas is at least one of hydrogen, carbon monoxide, and methane, and the carbon is at least one of activated carbon and coke. A reducing metal salt is preferably used as the reducing agent.

[0047] In the embodiment of the present invention, the cation element in the reducing metal salt includes at least one of nickel, cobalt and manganese, and the anion includes S 2- , at least one of oxalate and nitrite.

[0048] When a reducing metal salt is used as a reducing agent, after water immersion, the cations in the metal salt are transferred to the primary filter residue. Preferably, the main metal elements in the electrode waste are nickel, cobalt, tungsten, and lithium, or the main metal elements in the electrode waste are nickel, cobalt, aluminum, tungsten, and lithium. The metal elements in the electrode waste are generally present in the form of lithium nickelate, lithium cobaltate, lithium aluminate, lithium nickel cobalt manganate, or lithium nickel cobalt aluminumate. Such electrode waste is treated according to the method of the present invention, and the resulting filter residue is converted into a filtrate that can be directly used for the preparation of electrode materials, with good application prospects. It should be noted that the cations are generally not selected from inactive component doping elements (such as iron, copper, etc.) because these elements can act as impurities. For example, the presence of iron can easily cause the prepared battery material to self-discharge, resulting in a short circuit.

[0049] Taking the metal elements in electrode waste as nickel, cobalt, aluminum, tungsten and lithium as an example, for this type of electrode waste, if a reducing manganese salt is used as a reducing agent, after the filter residue is converted into filtrate, if it is directly used to prepare electrode materials without impurities removal, it will be the quaternary material NCMA.

[0050] In an embodiment of the present invention, the reducing metal salt is preferably a manganese salt, and more preferably at least one of manganese sulfide, manganese oxalate, and manganese nitrite. Taking the treatment of nickel-cobalt-lithium tungstate ternary waste with a reducing manganese salt as an example, lithium, tungsten, and a mixed nickel-cobalt-manganese element are extracted from the waste using a reducing manganese salt. The lithium and tungsten are then further processed to achieve recovery. The nickel-cobalt-manganese element in the filter residue can be used to prepare a ternary precursor, for example, by reducing acid leaching with sulfuric acid to obtain a mixed nickel-cobalt-manganese sulfate, which can achieve the purpose of preparing a ternary precursor at low cost, or can be used to prepare other compounds.

[0051] In an embodiment of the present invention, the molar ratio of the electrode waste to the reducing agent is 2 to 8:1, for example, 2:1, 3:1, 4:1, 5:1, 6:1, 6.5:1, 7:1 or 8:1.

[0052] In the embodiment of the present invention, the atmosphere condition is a flowing atmosphere condition; the flowing atmosphere can carry away the product, reduce the concentration of the product, and promote the reaction to proceed in the direction of low concentration.

[0053] In an embodiment of the present invention, the gas of the atmosphere is at least one of an inert gas, nitrogen, hydrogen, air and a nitrogen-oxygen mixture, and the volume percentage of oxygen in the nitrogen-oxygen mixture is less than 5%.

[0054] In an embodiment of the present invention, the rotation speed of the hot grinding treatment is 200 rpm to 1000 rpm, for example, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 750 rpm, 850 rpm or 950 rpm; the temperature is 30°C to 100°C, for example, 30°C, 45°C, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C.

[0055] In an embodiment of the present invention, the calcination temperature is 200°C to 600°C, such as 200°C, 300°C, 400°C, 500°C, 550°C or 600°C, and the calcination time is 10 min to 60 min, such as 10 min, 20 min, 30 min, 45 min, 50 min or 60 min.

[0056] In an embodiment of the present invention, the liquid-to-solid ratio of the water immersion process is 3 L / kg to 10:1 L / kg, for example, 3:1 L / kg, 4.5:1 L / kg, 5:1 L / kg, 7:1 L / kg, 8:1 L / kg or 10:1 L / kg; the temperature is 20°C to 50°C, for example, 20°C, 25°C, 30°C, 40°C or 50°C.

[0057] In an embodiment of the present invention, the leaching agent used in the alkaline leaching includes at least one of sodium carbonate, sodium bicarbonate and sodium hydroxide.

[0058] In a preferred embodiment of the present invention, the method further comprises the step of subjecting the secondary filter residue to a reduction acid leaching step. Electrode waste containing nickel, cobalt, tungsten, oxygen, and lithium generally also contains nickel and may also contain active elements such as cobalt or manganese. These elements are present in the secondary filter residue. For example, the secondary filter residue containing nickel, cobalt, and manganese is used for illustration. Because some of the nickel, cobalt, and manganese elements are in a high-valent state and difficult to leach, a reduction acid leaching method is used to obtain a nickel-cobalt-manganese mixed solution.

[0059] In an embodiment of the present invention, the impregnation system used in the reduction acid leaching includes an acid and a reducing component, the acid includes at least one of sulfuric acid, hydrochloric acid and phosphoric acid, and the reducing component includes at least one of hydrogen peroxide, sodium metabisulfite, sodium sulfite, oxalic acid and oxalate.

[0060] In an embodiment of the present invention, the acid concentration is 1.5 mol / L to 2 mol / L, for example, 1.5 mol / L, 1.7 mol / L, 1.8 mol / L or 2 mol / L.

[0061] In an embodiment of the present invention, the mass content of the reducing component is 8% to 15%, for example, 8%, 9%, 10%, 11%, 12%, 12.5%, 13%, 14% or 15%.

[0062] In another preferred embodiment of the present invention, the method further comprises the steps of adjusting the pH of the tungsten-containing solution to a range of 1-3 (e.g., pH 1, 1.5, 2, or 3), and bubbling oxygen or air to produce a tungstic acid precipitate. Tungsten-containing solutions (e.g., sodium tungstate solutions) readily form tungstic acid precipitates when the pH is below 3. Bubbling oxygen or air simultaneously promotes the oxidation of low-valent tungsten salts to high-valent tungstate salts, further facilitating the formation of tungstic acid precipitates when the pH is below 3.

[0063] The waste nickel-cobalt-lithium tungstate powder used in Examples 1-7 of the present invention is: lithium nickel-cobalt-tungstate obtained by modifying lithium nickel-cobalt-oxide with tungsten oxide or lithium tungstate, and a mixture of one or both of the waste nickel-cobalt-tungstate prepared by sintering nickel-cobalt-tungsten hydroxide and lithium hydroxide. For the mixture of the two, the mixing ratio of the two is arbitrary.

[0064] Example 1:

[0065] (1) Waste nickel-cobalt-lithium tungstate powder and manganese sulfide are mixed in a molar ratio of 6:1 to obtain a mixture, and then the mixture is placed in a sintering furnace and sintered by nitrogen, calcined at 500°C for 2h, and cooled with the furnace.

[0066] (2) After cooling, the waste is immersed in water at a liquid-to-solid ratio of 3:1 and a water immersion temperature of 20° C., and filtered to obtain a lithium-containing solution and a nickel-cobalt-manganese-tungsten filter residue.

[0067] (3) The nickel-cobalt-manganese-tungsten filter residue is leached with a 12 mol / L sodium hydroxide solution at 80°C to obtain a tungsten salt solution and nickel-cobalt-manganese slag.

[0068] Oxygen was introduced into the tungsten salt solution at 100 ml / min, and sulfuric acid was used to adjust the solution to 1-3 until no yellow precipitate was produced during the reaction, and then the oxygen was introduced.

[0069] The nickel-cobalt-manganese slag and the filter residue in step (2) are subjected to reduction acid leaching using a system of sulfuric acid and hydrogen peroxide at a liquid-to-solid ratio of 10:1, wherein the concentration of sulfuric acid in the system of sulfuric acid and hydrogen peroxide is 2.0 mol / L and the mass content of H2O2 is 8%, to obtain a mixed sulfate of nickel-cobalt-manganese. The mixed salt solution can be used to prepare a ternary precursor, sulfate and other compounds.

[0070] Example 2:

[0071] (1) Waste nickel-cobalt-lithium tungstate powder and manganese sulfide are mixed in a molar ratio of 3:1 to obtain a mixture, which is then placed in a sintering furnace and sintered in air, calcined at 600°C for 2 hours, and cooled in the furnace.

[0072] (2) After cooling, the waste is immersed in water at a liquid-to-solid ratio of 5:1 and a water immersion temperature of 50°C, and filtered to obtain a lithium-containing solution and a nickel-cobalt-manganese-tungsten filter residue.

[0073] (3) The nickel-cobalt-manganese-tungsten filter residue is leached with a 0.5 mol / L sodium carbonate solution at 100°C to obtain a tungsten salt solution and nickel-cobalt-manganese slag.

[0074] Oxygen was introduced into the tungsten salt solution at 100 ml / min, and sulfuric acid was used to adjust the solution to 1-3 until no yellow precipitate was produced during the reaction, and then the oxygen was introduced.

[0075] The nickel-cobalt-manganese slag and the filter residue in step (2) are subjected to reduction acid leaching using a system of sulfuric acid and sodium metabisulfite at a liquid-to-solid ratio of 10:1. In the sulfuric acid and sodium metabisulfite system, the concentration of sulfuric acid is 1.5 mol / L and the mass content of sodium metabisulfite is 15%, thereby obtaining a mixed sulfate of nickel-cobalt-manganese. The mixed salt solution can be used to prepare a ternary precursor, sulfates and other compounds.

[0076] Example 3:

[0077] (1) Weigh waste nickel-cobalt-lithium tungstate powder and manganese oxalate in a molar ratio of 2:1, then put the mixture into a grinder, introduce air into the grinder, grind at 800 rpm, calcine at 90 ° C for 2 h, and cool in the furnace.

[0078] (2) After cooling, the waste is immersed in water at a liquid-to-solid ratio of 6:1 and a water immersion temperature of 35°C, and filtered to obtain a lithium-containing solution and a nickel-cobalt-manganese-tungsten filter residue.

[0079] (3) The nickel-cobalt-manganese-tungsten filter residue is leached with a 0.5 mol / L sodium carbonate solution at 100°C to obtain a tungsten salt solution and nickel-cobalt-manganese slag.

[0080] Air was introduced into the tungsten salt solution at a rate of 200 ml / min, and nitric acid was used to adjust the solution to 1-3 until no yellow precipitate was produced during the reaction. Then, the air was introduced.

[0081] The nickel-cobalt-manganese slag and the filter residue in step (2) are subjected to reduction acid leaching using a system of sulfuric acid and sodium sulfite at a liquid-to-solid ratio of 10:1. In the sulfuric acid and sodium metabisulfite system, the concentration of sulfuric acid is 1.5 mol / L and the mass content of sodium metabisulfite is 15%, thereby obtaining a mixed sulfate of nickel-cobalt-manganese. The mixed salt solution can be used to prepare a ternary precursor, sulfates and other compounds.

[0082] Example 4:

[0083] Except that the calcination temperature in step (1) was adjusted to 300° C., other methods and conditions were the same as those in Example 1.

[0084] Example 5:

[0085] Except that the calcination atmosphere in step (1) was adjusted to nitrogen, other methods and conditions were the same as those in Example 2.

[0086] Example 6:

[0087] (1) Waste nickel cobalt lithium tungstate powder was calcined at a hydrogen flow rate of 1000 ml / min at a temperature of 400°C for 1.5 h and then cooled in the furnace.

[0088] (2) After cooling, the waste is immersed in water at a liquid-to-solid ratio of 8:1 and a water immersion temperature of 25° C., and filtered to obtain a lithium-containing solution and a nickel-cobalt-tungsten filter residue.

[0089] (3) The nickel-cobalt-tungsten filter residue is leached with sodium carbonate at 90°C to obtain a tungsten salt solution and nickel-cobalt slag.

[0090] Air was introduced into the tungsten salt solution at a rate of 160 ml / min, and nitric acid was used to adjust the solution to 2 until no yellow precipitate was produced during the reaction. Then, the air was introduced.

[0091] The nickel-cobalt slag and the filter residue in step (2) are subjected to reduction acid leaching using a system of sulfuric acid and sodium sulfite at a liquid-to-solid ratio of 10:1, wherein the concentration of sulfuric acid in the system of sulfuric acid and sodium sulfite is 1.5 mol / L and the mass content of sodium sulfite is 15%, to obtain a mixed sulfate of nickel and cobalt. The mixed salt solution can be used to prepare a ternary precursor, sulfate and other compounds.

[0092] Example 7:

[0093] (1) Waste nickel-cobalt-lithium tungstate powder and activated carbon were mixed in a molar ratio of 2:1 to obtain a mixture, and the mixture was hot ground at a speed of 500 rpm, a temperature of 85°C, a time of 3 hours, and cooled.

[0094] (2) After cooling, the waste is immersed in water at a liquid-to-solid ratio of 10:1 and a water immersion temperature of 30° C., and filtered to obtain a lithium-containing solution and a nickel-cobalt-tungsten filter residue.

[0095] (3) The nickel-cobalt-tungsten filter residue is leached with sodium carbonate at 110°C to obtain a tungsten salt solution and nickel-cobalt slag.

[0096] Air was introduced into the tungsten salt solution at a rate of 210 ml / min, and nitric acid was used to adjust the solution to 2.5. The air was then introduced until no yellow precipitate was produced during the reaction.

[0097] The nickel-cobalt slag and the filter residue in step (2) are subjected to reduction acid leaching using a system of sulfuric acid and sodium sulfite at a liquid-to-solid ratio of 10:1, wherein the concentration of sulfuric acid in the system of sulfuric acid and sodium sulfite is 1.5 mol / L and the mass content of sodium sulfite is 15%, to obtain a mixed sulfate of nickel and cobalt. The mixed salt solution can be used to prepare a ternary precursor, sulfate and other compounds.

[0098] Example 8:

[0099] (1) The waste powder prepared by doping lithium tungstate and lithium nickel cobalt manganese oxide in a molar ratio of 8:92 was mixed with manganese oxalate in a molar ratio of 1.5:1 to obtain a mixture, and the mixture was hot ground at a speed of 950 rpm, a temperature of 90° C., a time of 3 h, and cooled.

[0100] (2) After cooling, the waste is immersed in water at a liquid-to-solid ratio of 10:1 and a water immersion temperature of 30° C., and filtered to obtain a lithium-containing solution and a nickel-cobalt-manganese-tungsten filter residue.

[0101] (3) The nickel-cobalt-manganese-tungsten filter residue is leached with a 12 mol / L sodium hydroxide solution at 110°C to obtain a tungsten salt solution and nickel-cobalt-manganese slag.

[0102] Air was introduced into the tungsten salt solution at a rate of 210 ml / min, and sulfuric acid was used to adjust the solution to 2.5. The air was then introduced until no yellow precipitate was produced during the reaction.

[0103] Nickel-cobalt-manganese slag is subjected to reduction acid leaching using a system of sulfuric acid and hydrogen peroxide at a liquid-to-solid ratio of 8:1. In the system of sulfuric acid and hydrogen peroxide, the concentration of sulfuric acid is 2.0 mol / L and the mass content of H2O2 is 8%. A mixed sulfate of nickel, cobalt and manganese is obtained. The mixed salt solution can be used to prepare ternary precursors, sulfates and other compounds.

[0104] Example 9:

[0105] (1) Waste powder prepared by doping lithium nickel cobalt manganese oxide and tungsten oxide in a molar ratio of 90:10 was mixed with manganese nitrite in a molar ratio of 6:1 to obtain a mixture, and the mixture was hot ground at a speed of 900 rpm, a temperature of 95° C., a time of 3 hours, and cooled.

[0106] (2) After cooling, the waste is immersed in water at a liquid-to-solid ratio of 10:1 and a water immersion temperature of 30° C., and filtered to obtain a lithium-containing solution and a nickel-cobalt-manganese-tungsten filter residue.

[0107] (3) The nickel-cobalt-manganese-tungsten filter residue is leached with a 12 mol / L sodium hydroxide solution at 110°C to obtain a tungsten salt solution and nickel-cobalt-manganese slag.

[0108] Air was introduced into the tungsten salt solution at a rate of 210 ml / min, and sulfuric acid was used to adjust the solution to 2.5. The air was then introduced until no yellow precipitate was produced during the reaction.

[0109] Nickel-cobalt-manganese slag is subjected to reduction acid leaching using a system of sulfuric acid and hydrogen peroxide at a liquid-to-solid ratio of 7:1. In the system of sulfuric acid and hydrogen peroxide, the concentration of sulfuric acid is 2.0 mol / L and the mass content of H2O2 is 8%. A mixed sulfate of nickel, cobalt and manganese is obtained. The mixed salt solution can be used to prepare ternary precursors, sulfates and other compounds.

[0110] Example 10:

[0111] Except that manganese sulfide was replaced by manganese oxalate, other preparation methods and conditions were the same as those in Example 1.

[0112] Comparative Example 1:

[0113] Except that manganese sulfide was not added, other methods and conditions were the same as those in Example 1.

[0114] Comparative Example 2:

[0115] Except that the air atmosphere in Example 2 was replaced by an oxygen atmosphere, other methods and conditions were the same as those in Example 1.

[0116] Table 1

[0117]

[0118]

[0119] Note: The Li leaching rate is the leaching rate during water leaching, excluding the subsequent acid leaching rate. The W leaching rate is the leaching rate during alkaline leaching, and the Ni and Co leaching rates are the leaching rates during the reducing acid leaching process.

[0120] As can be seen from the table above, the leaching rates of Ni and Co are primarily affected by acid concentration and the type and dosage of the three reducing agents: hydrogen peroxide, sodium metabisulfite, and sodium sulfite. This is followed by the degree of reaction between waste nickel-cobalt lithium tungstate and additives such as manganese sulfide, manganese nitrite, hydrogen, and activated carbon. The leaching rate of tungsten is primarily influenced by factors such as temperature, leaching agent concentration, and degree of reduction.

[0121] The main reason why the lithium leaching rate in Example 1 is higher than that in Example 10 is that the amounts of waste nickel cobalt lithium tungstate and manganese sulfide reach the corresponding molar ratio, the valence of sulfur element increases from -2 to +6 when manganese sulfide exerts its reducing effect, and the amount of reducing agent is sufficient; while the valence of carbon element increases from +3 to +4 when manganese oxalate exerts its reducing effect. According to the molar ratio in Example 1, the amount of reducing agent is insufficient, and manganese oxalate is easily decomposed.

[0122] However, in Comparative Example 1, due to the lack of reducing agent, it is difficult to reduce the nickel cobalt tungstate lithium, so it is difficult to leach lithium during the water leaching process.

[0123] In Comparative Example 2, oxygen was used, causing some of the sulfur in the manganese sulfide to be oxidized to form sulfur dioxide or manganese sulfate, while some of the sulfur remained unreacted with the lithium nickel cobalt tungstate. This resulted in insufficient reaction of the lithium nickel cobalt tungstate and a relatively low element leaching rate.

[0124] The applicant states that the present invention is intended to illustrate the detailed methods of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed methods, that is, it does not mean that the present invention must rely on the above-described detailed methods in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A method for recovering valuable metals from electrode waste, characterized in that: The method comprises the following steps: The electrode waste is mixed with a reducing agent, and subjected to hot grinding or calcination treatment under atmospheric conditions to obtain a mixture; the mixture is soaked in water, separated, and a lithium-containing solution and a primary filter residue are obtained; and alkali leaching the primary filter residue and separating the tungsten-containing solution and the secondary filter residue; The electrode waste is electrode waste containing nickel, cobalt, tungsten, oxygen and lithium; The reducing agent includes a reducing metal salt; The cation elements in the reducing metal salt include at least one of nickel, cobalt and manganese, and the anion elements include S 2- , at least one of oxalate and nitrite.

2. The method according to claim 1, characterized in that The electrode waste includes at least one of nickel cobalt lithium tungstate waste, tungsten-doped nickel cobalt lithium manganese oxide waste and lithium tungstate-coated nickel cobalt lithium manganese oxide waste.

3. The method according to claim 1, characterized in that The reducing agent further includes reducing gas and / or carbon.

4. The method according to claim 3, characterized in that The reducing gas is at least one of hydrogen, carbon monoxide and methane.

5. The method according to claim 3, characterized in that The carbon is at least one of activated carbon and coke.

6. The method according to claim 1, characterized in that The reducing metal salt is a manganese salt.

7. The method according to claim 6, characterized in that The manganese salt is at least one of manganese sulfide, manganese oxalate and manganese nitrite.

8. The method according to claim 1, characterized in that The molar ratio of the electrode waste to the reducing agent is 2 to 8:

1.

9. The method according to claim 1, characterized in that The atmospheric condition is a flowing atmospheric condition.

10. The method according to claim 9, characterized in that The gas of the flowing atmosphere is at least one of an inert gas, nitrogen, hydrogen, air and a nitrogen-oxygen mixed gas, and the volume percentage of oxygen in the nitrogen-oxygen mixed gas is less than 5%.

11. The method according to claim 1, wherein The rotation speed of the hot grinding treatment is 200 rpm to 1000 rpm, and the temperature is 30° C. to 100° C.

12. The method according to claim 1, characterized in that The calcination treatment is performed at a temperature of 200° C. to 600° C. and for a time of 10 to 60 minutes.

13. The method according to claim 1, wherein The liquid-to-solid ratio of the water immersion process is 3 to 10:1 L / kg, and the temperature is 20° C. to 50° C.

14. The method according to claim 1, wherein The leaching agent used in the alkaline leaching includes at least one of sodium carbonate, sodium bicarbonate and sodium hydroxide.

15. The method according to claim 1, wherein The method further comprises the step of performing reduction acid leaching on the secondary filter residue.

16. The method according to claim 15, characterized in that The leaching agent used in the reduction acid leaching includes an acid and a reducing component, the acid includes at least one of sulfuric acid, hydrochloric acid and phosphoric acid, and the reducing component includes at least one of hydrogen peroxide, sodium metabisulfite, sodium sulfite, oxalic acid and oxalate.

17. The method according to claim 16, characterized in that The acid concentration is 1.5 mol / L to 2 mol / L.

18. The method according to claim 16, characterized in that The mass content of the reducing component is 8% to 15%.

19. The method according to claim 1, wherein The method further comprises the steps of adjusting the pH of the tungsten-containing solution to 1-3 and blowing in oxygen or air to prepare tungstic acid precipitate.

20. The method according to claim 1, wherein The method comprises the following steps: The nickel-cobalt lithium tungstate waste material and a reducing manganese salt are mixed in a molar ratio of 2 to 8:1, and subjected to hot grinding or calcination treatment under flowing atmosphere conditions to obtain a mixture; the nickel-cobalt lithium tungstate waste material is a mixture of one or both of the following: tungsten oxide or lithium tungstate modified nickel cobalt oxide, and nickel cobalt tungstate waste material prepared by sintering nickel cobalt tungstate hydroxide and lithium hydroxide; Soaking the mixture in water and performing solid-liquid separation to obtain a lithium-containing solution and a nickel-cobalt-manganese-tungsten filter residue; heating the nickel-cobalt-manganese-tungsten filter residue and leaching it with alkali to obtain a tungstate solution, and filtering to obtain a filter residue containing nickel, cobalt and manganese and a tungstate solution; subjecting the filter residue containing nickel, cobalt and manganese to reducing acid leaching to obtain a nickel, cobalt and manganese mixed solution; and The pH of the tungstate solution is adjusted to 1-3, and oxygen or air is introduced to obtain tungstic acid precipitation.

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