Method for removing iron and aluminum ions through cooperation of air oxidation and sodium phosphate

Abstract

The invention belongs to the technical field of waste lithium battery recovery, and particularly relates to a method for removing iron and aluminum ions by air oxidation and sodium phosphate, which comprises the following steps: adding sodium phosphate and sodium carbonate into a waste lithium battery positive electrode powder leachate, introducing air, reacting at a constant temperature of 50-80 DEG C, and performing solid-liquid separation after the reaction is finished to obtain filtrate and iron and aluminum filter residues. According to the method, air is introduced in the constant-temperature reaction process and cooperates with phosphate radicals to precipitate iron and aluminum ions, so that the iron and aluminum removal rate reaches 99.9%, meanwhile, the total loss rate of lithium, nickel, cobalt and manganese is smaller than 0.1%, an oxidizing agent is not additionally used, and the cost is lower. Therefore, the iron and aluminum ion removal cost is low, the iron and aluminum removal rate and the valuable metal loss rate are both considered, and the method is suitable for industrial use.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste lithium battery recycling, and particularly relates to a method for removing iron and aluminum ions by air oxidation and sodium phosphate. BACKGROUND

[0002] With the explosive growth of the new energy vehicle industry, ternary lithium batteries (NCM / NCA) become the mainstream technology route due to high energy density, and the positive electrode material of the ternary lithium battery is rich in strategic metals such as nickel (Ni 10-30 g / L), cobalt (Co 5-10 g / L), manganese (Mn 5-10 g / L), and lithium (Li 1-5 g / L). Therefore, the recovery rate of metals in the retired ternary lithium battery directly affects resource security and economy. At present, hydrometallurgy is the mainstream recovery process, and the metals are dissolved by acid leaching (usually a sulfuric acid system). In this process, the battery structure components are dissolved, the aluminum current collector and the shell are dissolved under acidic conditions, Al 3+ , and Fe 3+ / Fe 2+ is dissolved by introducing iron through impurity migration (iron introduced by iron-based tool wear in the battery manufacturing process). The electrolyte LiPF6 enters the leaching solution and coexists with the valuable metals. Among them, Al 3+ easily forms a gel strip hydroxide to wrap valuable metal ions, reducing the extraction separation effect; Fe 3+ / Fe 2+ oxidation and reduction potential fluctuation affects the stability of the electrolysis process; F pollution synergy: when the F concentration in the leaching solution reaches 2-3 g / L, iron and aluminum are easy to form a colloidal compound (such as AlF3 colloid) with fluorine, which increases the difficulty of solid separation and equipment corrosion. Therefore, the residual iron and aluminum will increase the difficulty of extracting valuable metal ions in the subsequent process, and the removal of iron and aluminum from the leaching solution is a key link in the hydrometallurgical recovery of valuable metals.

[0003] The existing conventional precipitation method has poor selectivity and is easy to form valuable metal entrainment; the solvent extraction method has high selectivity but high cost; the modification process of the adsorption and material modification method is relatively complex, and the scale cost advantage is insufficient; the engineering application of the jarosite method is limited. In order to solve some problems existing in the current impurity removal method, a method for removing iron and aluminum from the leaching solution generated in the recovery of valuable metals from waste lithium ion batteries is disclosed in Chinese Patent No. CN107871912A. The method obtains a purified liquid and iron and aluminum filter residue by oxidation, two-stage precipitation, aging, and filtration. However, the above method is relatively complex to operate, and it is difficult to achieve advantages in recovery cost, iron and aluminum removal rate, and valuable metal loss rate. Therefore, it is necessary to develop a low-cost and simple process for removing iron and aluminum ions from the leaching solution, while taking into account high iron and aluminum removal rate and low valuable metal loss rate. SUMMARY

[0004] The present application intends to provide a method for removing iron and aluminum ions by air oxidation and sodium phosphate, so as to solve the problems of high cost of removing iron and aluminum ions, and difficult to balance the removal rate of iron and aluminum and the loss rate of valuable metals in the existing waste lithium battery cathode powder leaching solution.

[0005] In order to achieve the above-mentioned purpose, the present application provides a method for removing iron and aluminum ions by air oxidation and sodium phosphate, comprising the following steps: adding sodium phosphate and sodium carbonate into the waste lithium battery cathode powder leaching solution, and passing air, constant temperature reaction at 50-80 DEG C, solid-liquid separation after reaction, and obtaining filtrate and iron and aluminum filter residue.

[0006] Optionally, the ratio of the number of moles of sodium phosphate to the number of moles of aluminum in the waste lithium battery cathode powder leaching solution or the ratio of the number of moles of sodium phosphate to the total number of moles of aluminum and iron in the waste lithium battery cathode powder leaching solution is 1-1.2:1.

[0007] Optionally, the sodium carbonate is a sodium carbonate solution with a concentration of 0.5-1.5 mol / L, and the sodium carbonate solution stops adding when the pH value of the waste lithium battery cathode powder leaching solution is 3-3.5.

[0008] Optionally, the flow rate of the air is 500-1000 mL / min.

[0009] Optionally, the sodium phosphate and sodium carbonate are added into the waste lithium battery cathode powder leaching solution under stirring, and the stirring speed is 300-600 rpm.

[0010] Optionally, the constant temperature reaction time is 30-90 min.

[0011] Optionally, the iron and aluminum filter residue is obtained after ultrasonic water washing, and the water washing liquid is recovered for preparing the leaching agent of the waste lithium battery cathode powder.

[0012] The working principle and beneficial effects of the scheme are that: in the constant temperature reaction process, air is introduced to cooperate with the precipitation of phosphate ions to remove iron and aluminum ions, and the iron and aluminum filter residues are washed with ultrasonic water, and the washing liquid is recovered to prepare the leaching agent of the positive electrode powder of the waste lithium battery, thereby reducing the loss amount of valuable metals. In this way, the iron and aluminum ion removal rate can break through 99.5%, while the total loss rate of lithium, nickel, cobalt and manganese is strictly controlled within 0.1%, reducing the loss amount of valuable metals in the traditional precipitation and extraction process. In addition, the scheme does not use additional oxidizing agents, and the cost is low. In addition, the scheme has strong adaptability to the leaching liquid of different battery types such as ternary lithium, lithium iron phosphate, lithium cobaltate and lithium manganate, and supports intelligent and large-scale production by accurately controlling the reaction parameters, promotes the development of impurity removal process in the wet recovery industry, provides key technical support for alleviating global resource shortage and ensuring sustainable development of new energy industry, and significantly improves industrial competitiveness. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A process flow chart of a method for removing iron and aluminum ions by air oxidation and sodium phosphate in the embodiments of the present application. DETAILED DESCRIPTION

[0014] The embodiments of the present application are described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure in the specification. The present application can also be implemented or applied by different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0015] The present application provides a method for removing iron and aluminum ions by air oxidation and sodium phosphate, comprising the following steps: adding sodium phosphate solid to the positive electrode powder leaching liquid of the waste lithium battery, stirring at a speed of 300-600 rpm, then slowly adding sodium carbonate solution with a concentration of 0.5-1.5 mol / L, adjusting the pH value of the positive electrode powder leaching liquid of the waste lithium battery to 3-3.5, and introducing air, and reacting at a constant temperature of 50-80℃ for 30-90min. After the reaction is completed, solid-liquid separation is performed to obtain filtrate and iron and aluminum filter residues; the iron and aluminum filter residues are washed with ultrasonic water for 1-5 times, and the washing liquid obtained during the washing is recovered to prepare the leaching agent of the positive electrode powder of the waste lithium battery.

[0016] The ratio of the number of moles of sodium phosphate solid to the total number of moles of iron and aluminum in the positive electrode powder leaching liquid of the waste lithium battery is 0.8-1.2:1; the flow rate of air is 500-1000 mL / min.

[0017] The following specific examples are provided to illustrate the present application in detail. It should also be understood that these examples are only used to illustrate the present application and should not be construed as limiting the scope of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application are within the scope of protection of the present application. The specific process parameters in the following examples are only one example in the appropriate range, i.e. those skilled in the art can make appropriate selection within the range according to the description herein, and are not limited to the specific values in the following examples.

[0018] Example 1

[0019] This example provides a method for removing iron and aluminum ions by air oxidation and sodium phosphate, as shown in the following steps: Figure 1

[0020] Take 3L of waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is analyzed by ICP, and the concentrations of each element are lithium 3.64g / L, nickel 19.70g / L, cobalt 4.22g / L, manganese 3.92g / L, iron 0.38g / L, and aluminum 1.58g / L), according to the molar ratio of Na3PO4:Al (Al in the waste lithium battery positive electrode powder leaching solution) =1:1, add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution in a water bath at 80℃, stir at 350rpm, slowly add Na2CO3 solution with a concentration of 1mol / L, adjust the pH value of the leaching solution to 3.5, and pass air at a flow rate of 500mL / min, constant temperature reaction for 1h, and filter to obtain the filtrate and iron and aluminum filter residue. The filtrate is sent for ICP test analysis; the iron and aluminum filter residue is washed twice by ultrasonic water, and the washing water is sent for ICP test analysis (the remaining washing water is recovered for preparation of the leaching agent for waste lithium battery positive electrode powder). The calculated iron removal rate is 98.3%, the aluminum removal rate is 99.1%, the loss rate of lithium is 0.08%, the loss rate of nickel is 0.03%, the loss rate of cobalt is 0.05%, the loss rate of manganese is 0.07%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.044%.

[0021] Example 2

[0022] This example provides a method for removing iron and aluminum ions by air oxidation and sodium phosphate, including the following steps:

[0023] ​Take 3L waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is the same as that in Example 1), according to the molar ratio Na3PO4:Al (Al in the waste lithium battery positive electrode powder leaching solution) = 1.1:1, water bath 80℃, add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution, stir at 350rpm, slowly add 1mol / L Na2CO3 solution, adjust the pH value of the leaching solution to 3.5, and pass air at a flow rate of 500mL / min, constant temperature reaction for 1h, and filter to obtain filtrate and iron aluminum filter residue. The filtrate is sent for ICP test analysis; the iron aluminum filter residue is washed twice by ultrasonic, and the washing liquid is sent for ICP test analysis (the remaining washing liquid is recovered for preparation of the leaching agent of the waste lithium battery positive electrode powder). It is calculated that the iron removal rate is 99.2%, the aluminum removal rate is 99.2%, the loss rate of lithium is 0.08%, the loss rate of nickel is 0.05%, the loss rate of cobalt is 0.06%, the loss rate of manganese is 0.08%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.059%.

[0024] Example 3

[0025] The embodiment provides a method for removing iron and aluminum ions by air oxidation and sodium phosphate, comprising the following steps:

[0026] Take 3L waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is the same as that in Example 1), according to the molar ratio Na3PO4:Al (Al in the waste lithium battery positive electrode powder leaching solution) = 1.1:1, water bath 80℃, add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution, stir at 350rpm, slowly add 1mol / L Na2CO3 solution, adjust the pH value of the leaching solution to 3.5, and pass air at a flow rate of 500mL / min, constant temperature reaction for 1h, and filter to obtain filtrate and iron aluminum filter residue. The filtrate is sent for ICP test analysis; the iron aluminum filter residue is washed twice by ultrasonic, and the washing liquid is sent for ICP test analysis (the remaining washing liquid is recovered for preparation of the leaching agent of the waste lithium battery positive electrode powder). It is calculated that the iron removal rate is 99.2%, the aluminum removal rate is 99.2%, the loss rate of lithium is 0.08%, the loss rate of nickel is 0.05%, the loss rate of cobalt is 0.06%, the loss rate of manganese is 0.08%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.059%.

[0027] Example 4

[0028] The embodiment provides a method for removing iron and aluminum ions by air oxidation and sodium phosphate, comprising the following steps:

[0029] Take 3L of waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is the same as that in Example 1), add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution in a water bath at 80℃ according to the molar ratio Na3PO4:Al (Al in the waste lithium battery positive electrode powder leaching solution) = 1.2:1, stir at 350 rpm, slowly add Na2CO3 solution with a concentration of 1 mol / L, adjust the pH value of the leaching solution to 3.5, and pass air at a flow rate of 1000 mL / min for 1 h of constant temperature reaction. Filtrate and iron-aluminum filter residue are obtained by suction filtration. The filtrate is sent for ICP test analysis; the iron-aluminum filter residue is washed with water twice, and the washing water is sent for ICP test analysis (the remaining washing water is recycled for preparation of the leaching agent for waste lithium battery positive electrode powder). It is calculated that the iron removal rate is 99.9%, the aluminum removal rate is 99.9%, the loss rate of lithium is 0.10%, the loss rate of nickel is 0.09%, the loss rate of cobalt is 0.11%, the loss rate of manganese is 0.13%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.099%.

[0030] Example 5

[0031] The present embodiment provides a method for removing iron and aluminum ions by air oxidation and sodium phosphate, comprising the following steps:

[0032] Take 3L of waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is analyzed by ICP, and the concentrations of each element are lithium 8.58g / L, nickel 59.34g / L, cobalt 20.01g / L, manganese 21.59g / L, iron 2.14g / L, and aluminum 4.22g / L), add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution in a water bath at 80℃ according to the molar ratio Na3PO4:(Al+Fe) (Al and Fe in the waste lithium battery positive electrode powder leaching solution) = 1.2:1, stir at 350 rpm, slowly add Na2CO3 solution with a concentration of 0.5 mol / L, adjust the pH value of the leaching solution to 3.5, and pass air at a flow rate of 1000 mL / min for 1 h of constant temperature reaction. Filtrate and iron-aluminum filter residue are obtained by suction filtration. The filtrate is sent for ICP test analysis; the iron-aluminum filter residue is washed with water four times, and the washing water is sent for ICP test analysis (the remaining washing water is recycled for preparation of the leaching agent for waste lithium battery positive electrode powder). It is calculated that the iron removal rate is 99.9%, the aluminum removal rate is 99.9%, the loss rate of lithium is 0.22%, the loss rate of nickel is 0.30%, the loss rate of cobalt is 0.13%, the loss rate of manganese is 0.25%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.253%.

[0033] Comparative Example 1

[0034] The present comparative example provides a method for removing iron and aluminum ions from leaching solution, comprising the following steps:

[0035] Take 3L waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is the same as the waste lithium battery positive electrode powder leaching solution in Example 1), according to the molar ratio Na3PO4:Al (Al in the waste lithium battery positive electrode powder leaching solution) = 1.2:1, add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution under water bath at 80℃, stir under the condition of 350 rpm, slowly add Na2CO3 solution with a concentration of 1 mol / L, adjust the pH value of the leaching solution to 3.5, constant temperature reaction for 1h, and filter to obtain the filtrate and iron-aluminum filter residue. The filtrate is sent for ICP test analysis; the iron-aluminum filter residue is washed twice by ultrasonic water, and the washing water is sent for ICP test analysis. It is calculated that the iron removal rate is 86.5%, the aluminum removal rate is 99.9%, the loss rate of lithium is 0.06%, the loss rate of nickel is 0.05%, the loss rate of cobalt is 0.04%, the loss rate of manganese is 0.09%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.055%.

[0036] Comparative Example 2

[0037] This comparative example provides a method for removing iron and aluminum ions from a leaching solution, comprising the following steps:

[0038] Take 3L waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is the same as the waste lithium battery positive electrode powder leaching solution in Example 1), according to the molar ratio Na3PO4:Al (Al in the waste lithium battery positive electrode powder leaching solution) = 0.8:1, add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution under water bath at 80℃, stir under the condition of 350 rpm, slowly add Na2CO3 solution with a concentration of 1 mol / L, adjust the pH value of the leaching solution to 3.5, and pass air at a flow rate of 500 mL / min, constant temperature reaction for 1h, and filter to obtain the filtrate and iron-aluminum filter residue. The filtrate is sent for ICP test analysis; the iron-aluminum filter residue is washed twice by ultrasonic water, and the washing water is sent for ICP test analysis. It is calculated that the iron removal rate is 98.5%, the aluminum removal rate is 94.6%, the loss rate of lithium is 0.08%, the loss rate of nickel is 0.03%, the loss rate of cobalt is 0.08%, the loss rate of manganese is 0.07%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.047%.

[0039] Comparative Example 3

[0040] This comparative example provides a method for removing iron and aluminum ions from a leaching solution, comprising the following steps:

[0041] Take 3 L of waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is the same as that in Example 1), according to the molar ratio Na3PO4:Al (Al in the waste lithium battery positive electrode powder leaching solution) = 1.2:1, add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution under water bath at 80℃, stir under the condition of 350 rpm, slowly add Na2CO3 solution with a concentration of 1 mol / L, adjust the pH value of the leaching solution to 3.5, pass air at a flow rate of 1000 mL / min, and react for 1 h at constant temperature. Filtrate and iron-aluminum filter residue are obtained by suction filtration. The filtrate is sent for ICP test analysis; the iron-aluminum filter residue is washed with water twice, and the water washing liquid is sent for ICP test analysis. It is calculated that the iron removal rate is 99.9%, the aluminum removal rate is 99.9%, the loss rate of lithium is 0.22%, the loss rate of nickel is 0.18%, the loss rate of cobalt is 0.08%, the loss rate of manganese is 0.26%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.181%.

[0042] Comparative Example 4

[0043] The present comparative example provides a method for removing iron and aluminum ions from a leaching solution, comprising the following steps:

[0044] Take 3 L of waste lithium battery positive electrode powder leaching solution (the waste lithium battery positive electrode powder leaching solution is the same as that in Example 5), according to the molar ratio Na3PO4:(Al+Fe) (Al and Fe in the waste lithium battery positive electrode powder leaching solution) = 1.1:1, add sodium phosphate solid to the waste lithium battery positive electrode powder leaching solution under water bath at 80℃, stir under the condition of 350 rpm, slowly add Na2CO3 solution with a concentration of 0.5 mol / L, adjust the pH value of the leaching solution to 3.5, pass air at a flow rate of 1000 mL / min, and react for 1 h at constant temperature. Filtrate and iron-aluminum filter residue are obtained by suction filtration. The filtrate is sent for ICP test analysis; the iron-aluminum filter residue is washed with water twice (the remaining water washing liquid is recovered for preparing the leaching agent for waste lithium battery positive electrode powder), and the water washing liquid is sent for ICP test analysis. It is calculated that the iron removal rate is 99.9%, the aluminum removal rate is 99.9%, the loss rate of lithium is 0.35%, the loss rate of nickel is 0.46%, the loss rate of cobalt is 0.42%, the loss rate of manganese is 0.56%, and the total loss rate of lithium, nickel, cobalt and manganese is 0.464%.

[0045] The above is only an embodiment of the present application, the present application is not limited to this embodiment The field to which the embodiment relates, common knowledge of specific structures and characteristics in the scheme, etc. is not described in detail here The ordinary skilled person in the art knows all the ordinary technical knowledge in the field to which the present application belongs before the filing date or the priority date, can know all the prior art in the field, and has the ability to apply conventional experimental means before that date The ordinary skilled person in the art can perfect and implement the present scheme under the guidance of the present application, in combination with their own ability Some typical known structures or known methods should not be an obstacle to the implementation of the present application by the ordinary skilled person in the art It should be noted that, for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can also be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the present application The scope of protection claimed in the present application should be subject to the content of its claims The specific implementation in the specification can be used to explain the content of the claims

Claims

1. A method for removing iron and aluminum ions by air oxidation in conjunction with sodium phosphate, characterized in that: Includes the following steps: Sodium phosphate and sodium carbonate are added to the leachate of waste lithium battery cathode powder, and air is introduced. The reaction is carried out at a constant temperature of 50-80°C. After the reaction is completed, the solid and liquid are separated to obtain filtrate and iron-aluminum filter residue.

2. The method according to claim 1, characterized in that: The ratio of the number of moles of sodium phosphate to the number of moles of aluminum in the leachate of waste lithium battery cathode powder, or the ratio of the number of moles of sodium phosphate to the total number of moles of aluminum and iron in the leachate of waste lithium battery cathode powder, is 1 to 1.2:

1.

3. The method according to claim 1, characterized in that: The sodium carbonate is a sodium carbonate solution with a concentration of 0.5 to 1.5 mol / L. The addition of sodium carbonate solution is stopped when the pH value of the leachate from the waste lithium battery positive electrode powder is 3 to 3.

5.

4. The method according to claim 1, characterized in that: The air flow rate is 500–1000 mL / min.

5. The method according to claim 1, characterized in that: Sodium phosphate and sodium carbonate were added to the leachate of waste lithium battery cathode powder under stirring conditions, with a stirring speed of 300-600 rpm.

6. The method according to claim 1, characterized in that: The isothermal reaction time is 30–90 min.

7. The method according to claim 1, characterized in that: The iron-aluminum filter residue is ultrasonically washed with water to obtain a washing solution, which is then recycled and used to prepare a leaching agent for waste lithium battery cathode powder.

8. The method according to claim 1, characterized in that: The concentration of the leachate from the waste lithium battery cathode powder is 3.64–8.58 g / L for lithium, 19.70–59.34 g / L for nickel, 4.22–20.01 g / L for cobalt, 3.92–21.59 g / L for manganese, 0.38–2.14 g / L for iron, and 1.58–4.22 g / L for aluminum.

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