Resource recycling method for valuable components in waste lithium iron phosphate batteries

Abstract

The invention discloses a resource recycling method for valuable components in waste lithium iron phosphate batteries, and relates to the technical field of new energy and battery technologies. The method comprises the following steps: pretreating the acid leaching solution of the waste lithium iron phosphate black powder leached by sulfuric acid, adjusting the pH value to 1.0-2.2 by using a sodium hydroxide solution, dropwise adding one or more of sodium peroxide, hydrogen peroxide and peracetic acid as an oxidizing agent at a constant speed, and carrying out full oxidation reaction on the oxidizing agent and titanium in the acid leaching solution at a specific stirring speed and temperature for 10-60 minutes. The method comprises the following steps: adding titanium into a reaction kettle, then adjusting the pH value to 2.3-3.2 by using a potassium hydroxide solution, putting the solution into a temperature-controlled reaction device, carrying out heat-preservation reaction for 10-100min at a set temperature and a set stirring rotating speed to fully hydrolyze and precipitate titanium, and finally filtering by using filter paper or a filter membrane to realize separation of titanium from a solution main body, so as to effectively recover valuable components in the waste batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy and battery technology, and in particular to a method for resource recovery of valuable components in waste lithium iron phosphate batteries. Background Art

[0002] With the growing global demand for clean energy, the new energy vehicle industry has developed rapidly. Lithium iron phosphate batteries are increasingly widely used in new energy vehicles and energy storage due to their high safety, long cycle life, good thermal stability and other advantages. However, with the production, sales and use of a large number of lithium iron phosphate batteries, the number of waste batteries generated after retirement is also increasing sharply. How to properly deal with these waste lithium iron phosphate batteries has become an important issue that needs to be solved urgently.

[0003] On the one hand, from a resource perspective, waste lithium iron phosphate batteries contain a variety of valuable components, such as lithium, iron, phosphorus, etc. These elements are raw materials with high economic value and key uses in many industrial fields. For example, lithium is an indispensable key element for the manufacture of high-performance batteries, while iron and phosphorus are also important basic raw materials for the chemical, material and other industries. If these valuable components are not effectively recycled, a large amount of resources will be wasted, which is not in line with the concept of sustainable resource utilization. In addition, as the demand for related raw materials continues to rise, the supply model that relies on primary mineral resources faces many challenges such as increased costs and gradually reduced resource reserves. Therefore, it is extremely necessary to recycle the valuable components in waste batteries.

[0004] On the other hand, from an environmental perspective, if waste lithium iron phosphate batteries are not properly handled, the chemical components they contain may cause serious harm to the ecological environment. The electrolyte and other substances inside the battery may leak, thereby polluting environmental media such as soil and water. The heavy metal components they contain also pose a risk of threatening the ecosystem and human health through enrichment in the food chain. Therefore, scientifically and rationally handling waste lithium iron phosphate batteries to achieve their harmlessness and resource recovery of valuable components is a key measure to reduce the environmental impact of battery waste.

[0005] At present, although there have been some research and technical methods for the recycling of waste lithium iron phosphate batteries, there are still many shortcomings. After the waste lithium iron phosphate batteries are treated with acid leaching, a large amount of iron, phosphorus and lithium ions are often lost during the removal of impurities in the acid leaching solution, especially titanium. This not only reduces the recovery rate of valuable components and affects economic benefits, but may also lead to problems such as imbalance in the raw material ratio when synthesizing related products in the subsequent process. Summary of the invention

[0006] In response to the above technical problems, the present application solves the problem that after the waste lithium iron phosphate batteries are subjected to acid leaching treatment, a large amount of iron, phosphorus and lithium ion losses often occur during the removal of impurities in the acid leaching solution, especially the removal of titanium. This not only reduces the recovery rate of valuable components and affects economic benefits, but may also lead to problems such as imbalance in the raw material ratio when synthesizing related products in the subsequent process.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted in the present application is: a method for recycling valuable components in waste lithium iron phosphate batteries, comprising the following steps:

[0008] Step 1: Pre-treat the waste lithium iron phosphate black powder acid leaching solution after sulfuric acid leaching to ensure that the solution is in a uniform and stable state and there is no obvious impurity precipitation that interferes with subsequent operations;

[0009] Use sodium hydroxide solution and slowly add it into the pickling solution;

[0010] At the same time, the pH value is monitored in real time by a precision pH detection instrument, and after adjusting the pH value to 1.0 to 2.2, a suitable oxidant is selected from one or more of sodium peroxide, hydrogen peroxide, and peracetic acid and added to the acid leaching solution;

[0011] During the addition process, a uniform dripping method is used to ensure that the oxidant is evenly dispersed in the solution. Under a set stirring speed of 0 to 300 rpm, a temperature control device is used to accurately control the reaction temperature to 15 to 70°C, so that the titanium in the acid leaching solution can fully contact with the oxidant and undergo an oxidation reaction under this environment, and the reaction lasts for 10 to 60 minutes;

[0012] Step 2: After the oxidation reaction in step 1 is completed, potassium hydroxide solution is selected and added to the resulting liquid again, and the pH value is adjusted to 2.3-3.2 by means of high-precision pH monitoring means;

[0013] Then, the solution is placed in a reaction device with precise temperature control, the temperature is adjusted to 30-70°C, and the reaction stirring speed is set to 150-300rpm. The solution is kept warm and reacted under this condition for 10-100 minutes to allow the titanium to be fully hydrolyzed and precipitated, and then filtered through filter paper or filter membrane to separate the titanium from the main body of the solution.

[0014] In order to better realize the present invention, further, the specific pH value of the alkali solution added in step 1 to adjust the pH value is 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 or 2.2.

[0015] In order to better realize the present invention, further, the amount of the oxidant added in step 1 is 0.1 g / L, 0.5 g / L, 1 g / L, 2 g / L, 4 g / L, 6 g / L, 8 g / L or 10 g / L.

[0016] In order to better implement the present invention, further, the stirring speed in step 1 is 0 rpm, 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm or 300 rpm.

[0017] In order to better realize the present invention, further, the reaction temperature in step 1 is 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

[0018] In order to better realize the present invention, further, the reaction time in step 1 is 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0019] In order to better realize the present invention, further, the specific pH value of adding alkali solution to adjust the pH value in step 2 is 2.3, 2.5, 2.7, 2.9, 3.0, 3.1 or 3.2.

[0020] In order to better realize the present invention, further, the reaction temperature in step 2 is 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

[0021] In order to better implement the present invention, further, the reaction stirring speed in step 2 is 150 rpm, 200 rpm, 250 rpm or 300 rpm.

[0022] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0023] 1. After the waste lithium iron phosphate batteries are treated with acid leaching in the prior art, a large amount of iron, phosphorus and lithium ions are often lost during the process of removing impurities (especially titanium) from the acid leaching solution, which seriously reduces the overall recovery rate of valuable components.

[0024] The method provided in this application, by accurately controlling the key parameters of each step, such as strictly controlling the pH value to 1.0-2.2 in step 1, oxidizing titanium with a specific oxidant, a suitable stirring speed, a precise reaction temperature and a reasonable reaction time; in step 2, the pH value is finely adjusted to 2.3-3.2 again, and the corresponding reaction temperature and stirring speed are controlled for heat preservation reaction, so that titanium can be fully hydrolyzed and precipitated and effectively separated. This series of precise operations effectively reduces the loss of valuable components such as iron, phosphorus, and lithium in the process of titanium removal, thereby significantly improving the recovery rate of these valuable components, ensuring the full utilization of resources, and meeting the development needs of resource recycling.

[0025] 2. The existing technology will cause the loss of valuable components during the impurity removal process, which directly affects the economic benefits of recycling. In addition, the loss of elements may cause an imbalance in the raw material ratio when synthesizing related products (such as iron phosphate, etc.), requiring additional raw materials to adjust the ratio, further increasing costs.

[0026] The method of the present invention effectively avoids the loss of a large amount of valuable components, ensures that each element can be retained in a relatively reasonable proportion, makes the supply of raw materials stable and the ratio easier to control in the subsequent synthesis of products, reduces the cost expenditure of additional raw material replenishment, and improves the economic benefits of resource recovery of waste lithium iron phosphate batteries as a whole, and enhances the competitiveness of the recovery method in the market.

[0027] 3. The existing technology often introduces other impurity ions during the titanium removal or other impurity removal process, which not only affects the purity and quality of the recovered product, but may also have many adverse effects on subsequent further processing and utilization as well as the entire recovery process.

[0028] The method of the present application achieves the removal of titanium impurities without introducing other additional impurity ions during the resource recovery process of valuable components in the entire waste lithium iron phosphate battery, especially in the key step of titanium removal in the acid leaching solution, through the selection of specific chemical reagents and rigorous process parameter control, thereby ensuring that the recovered valuable components and subsequent products have high purity, which helps to improve the applicability and value of the recovered products in related industrial fields.

[0029] 4. The existing technology may not accurately control the process parameters, resulting in more uncertainties in the recycling process such as impurity removal, affecting the recycling effect and efficiency.

[0030] The present invention specifies in detail the range of key parameters and specific optional values ​​in each step, such as the specific optional values ​​of the amount of oxidant added, stirring speed, reaction temperature, reaction time, etc. in step 1, and the relevant parameters in step 2 are also clearly defined. This makes the entire recovery process highly controllable, and the operator can operate according to precise parameter requirements, ensuring that a relatively stable and ideal effect can be achieved each time the recovery process is implemented, which is conducive to the promotion and large-scale implementation of the recovery method in actual production applications.

[0031] 5. In the prior art, improper treatment of waste lithium iron phosphate batteries will cause serious harm to the environment.

[0032] The resource recovery method of the present application can not only effectively recover the valuable components and avoid waste of resources, but also reduce the potential environmental pollution risks caused by element loss during the recovery process through precise process control, while avoiding the introduction of impurity ions to bring new adverse effects on the environment, thereby achieving an organic combination of harmless treatment of waste batteries and resource recovery, meeting environmental protection requirements, and having positive significance for reducing the environmental impact of battery waste and protecting the ecological environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative labor.

[0034] Figure 1 The present invention is a flow chart of a method for recycling valuable components in waste lithium iron phosphate batteries. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0038] In the description of this application, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the application is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, if the terms "first", "second", etc. appear in the description of this application, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0039] In addition, if the terms "horizontal" or "vertical" appear in the description of this application, it does not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] Embodiment 1:

[0042] Raw material preparation: Collect a certain amount of waste lithium iron phosphate batteries, disassemble them, obtain the black powder part, treat the black powder through conventional sulfuric acid leaching process, and obtain waste lithium iron phosphate black powder acid leaching solution to ensure that the content of each component is within the normal fluctuation range for subsequent valuable component resource recovery experiments.

[0043] Experimental equipment: prepare a high-precision pH detection instrument (with an accuracy of up to ±0.01), a separatory funnel that can add reagents at a uniform speed, a constant temperature water bath with a temperature control accuracy of ±1°C, a reaction vessel equipped with a stirring device and a stirring speed that can be precisely adjusted (with an accuracy of ±5rpm), filter papers and filter membranes of different specifications and other filtering devices to meet the requirements for precise parameter control and operation in each step of the experimental process.

[0044] Step 1:

[0045] First, the acid leaching liquid of the waste lithium iron phosphate black powder after sulfuric acid leaching is pretreated, and the acid leaching liquid is transferred to a clean and dry reaction container, and slowly stirred to make it in a uniform and stable state. At the same time, observe whether there is obvious impurity precipitation in the solution. If there is, it is removed by conventional means such as filtration to ensure that there are no impurities that interfere with subsequent operations.

[0046] Use a sodium hydroxide solution with a concentration of 1 mol / L, slowly add it to the acid leaching solution through a separatory funnel, and turn on a high-precision pH detection instrument to monitor the pH value in real time. When the pH value reaches 1.6, stop adding the sodium hydroxide solution.

[0047] Select hydrogen peroxide as the oxidant from sodium peroxide, hydrogen peroxide, and peracetic acid, and set the addition amount to 0.1 g / L. Pour the hydrogen peroxide solution into a separatory funnel, and use a uniform dripping method (the dripping speed is controlled to be 1 drop / second) to ensure that the oxidant is evenly dispersed in the solution.

[0048] At the same time, the reaction vessel was placed in a constant temperature water bath, and the temperature control equipment was used to accurately control the reaction temperature at 30°C. The stirring speed was set to 300 rpm, so that the titanium in the acid leaching solution could fully contact the oxidant and undergo oxidation reaction under this environment. The reaction lasted for 60 minutes. During the reaction, the solution state was continuously observed to ensure that the reaction proceeded smoothly.

[0049] Step 2:

[0050] After the oxidation reaction in step 1 is completed, a potassium hydroxide solution with a concentration of 0.5 mol / L is selected and slowly added to the obtained liquid through a separatory funnel. With the help of high-precision pH monitoring means, the addition of potassium hydroxide solution is stopped when the pH value is adjusted to 2.7.

[0051] Then, the solution was placed in another reaction device with precise temperature control (temperature control accuracy of ±1°C), the temperature was adjusted to 60°C, and the reaction stirring speed was set to 300rpm. The solution was kept warm and reacted under this condition for 30 minutes. During this period, samples were taken regularly to observe the hydrolysis and precipitation of titanium in the solution until it was determined through visual observation and instrument detection that titanium could be fully hydrolyzed and precipitated.

[0052] Finally, a filter membrane with a pore size of 0.45 μm was selected and placed in the filtration device, and the solution after the above reaction was filtered to separate titanium from the main body of the solution. The filtered solution was collected for subsequent detection and analysis of the recovery of valuable components and related indicators.

[0053] Valuable component recovery rate detection: Professional chemical analysis methods (such as inductively coupled plasma emission spectroscopy, etc.) are used to detect the lithium, iron, and phosphorus content in the filtered solution, and the recovery rate is calculated by comparing with the initial content of the corresponding elements in the raw material acid leaching solution. After testing, the recovery rate of lithium reached 95%, the recovery rate of iron was 93%, and the recovery rate of phosphorus was 92%. Compared with the traditional titanium removal process, the recovery rate of valuable components has been significantly improved, indicating that this method is effective in reducing the loss of valuable components.

[0054] Impurity ion detection: A comprehensive impurity ion analysis was performed on the filtered solution, and no other impurity ions were detected that were obviously introduced by the titanium removal process. This proves that this method can effectively avoid the introduction of additional impurity ions while removing titanium impurities, thereby ensuring the purity of the recovered solution and subsequent products.

[0055] Economic benefit evaluation: Economic benefit analysis is conducted based on the recovery rate of valuable components and the theoretical amount of raw materials required for the subsequent synthesis of related products (such as lithium iron phosphate, etc.). Since this method ensures a high recovery rate of valuable components, there is no need to add a large amount of additional raw materials to adjust the ratio in the subsequent synthesis process. Compared with the existing technology, under the same scale of recycling and treatment, it is expected to reduce the raw material cost by about 20%, significantly improving the overall economic benefits of the recycling of waste lithium iron phosphate batteries.

[0056] Embodiment 2:

[0057] Similar to Example 1, sufficient waste lithium iron phosphate black powder acid leaching solution and corresponding high-precision experimental equipment are prepared to ensure that the equipment is calibrated and can operate normally and accurately, providing a reliable operating basis for this experiment.

[0058] Step 1:

[0059] After pre-treating the acid leaching solution, the pH value was slowly adjusted using a sodium hydroxide solution with a concentration of 0.8 mol / L. With the help of a precision pH detection instrument, when the pH value reached 1.2, the addition of the sodium hydroxide solution was stopped.

[0060] This time, sodium peroxide was selected as the oxidant, and the addition amount was set to 2g / L. After sodium peroxide was prepared into a solution of appropriate concentration, it was added to the acid leaching solution by uniform dripping (dropping speed of 2 drops / second) through a separatory funnel. At the same time, the reaction container was placed in a constant temperature water bath, and the reaction temperature was accurately controlled at 40°C using a temperature control device, and the stirring speed was set to 200rpm, so that titanium and the oxidant were fully in contact and reacted, and the reaction lasted for 40 minutes. During the process, pay close attention to changes in the solution color, state, etc. to ensure that the reaction proceeds normally.

[0061] Step 2:

[0062] After the reaction in step 1 is completed, a potassium hydroxide solution with a concentration of 1 mol / L is added to the solution to adjust the pH value. The adjustment is completed when the pH value reaches 2.5.

[0063] Subsequently, the solution was transferred to a reaction device with precise temperature control, the temperature was adjusted to 50°C, and the reaction stirring speed was set to 250 rpm. Under this condition, the reaction was kept warm for 60 minutes. During this period, microscopic observation and other methods were used to assist in judging the degree of titanium hydrolysis and precipitation to ensure that the titanium was fully hydrolyzed and precipitated.

[0064] Finally, the solution was filtered using a filtration system consisting of multiple layers of filter paper (qualitative filter paper, medium speed), and the filtrate was collected for subsequent analysis and testing.

[0065] In terms of the recovery rate of valuable components: professional element analysis instruments were used to detect the content of lithium, iron and phosphorus in the filtrate, and the recovery rate was calculated by comparing with the original acid leaching solution. The results showed that the recovery rate of lithium reached 93%, the recovery rate of iron reached 90%, and the recovery rate of phosphorus reached 88%, which once again verified the effectiveness of this method in reducing the loss of valuable components in the titanium removal process and can ensure a high level of recovery of valuable components.

[0066] Impurity detection: After comprehensive and detailed impurity ion detection and analysis, no new impurity ions were found to be introduced during the titanium removal process, which ensures the purity of the recovered solution and is conducive to the subsequent processing and utilization of valuable components and the improvement of product quality.

[0067] The controllability of the process is reflected in that during the entire experimental process, the key parameters of each step (such as pH value, amount of oxidant added, reaction temperature, stirring speed, reaction time, etc.) are precisely controlled according to the clear range and specific optional values ​​set by the present invention, so that relatively stable and similar results can be obtained each time the experiment is repeated, which reflects that the recovery process has strong controllability and provides strong support for actual large-scale production applications.

[0068] Embodiment 3:

[0069] Black powder acid leaching solutions prepared from different batches of waste lithium iron phosphate batteries were collected to increase the diversity of experimental samples. At the same time, all experimental equipment was checked and calibrated again to ensure the accuracy and reliability of the experimental data.

[0070] Step 1:

[0071] The new batch of waste lithium iron phosphate black powder acid leaching solution after sulfuric acid leaching is pretreated to ensure that the solution is uniform and free of impurity precipitation interference, and then the pH value is adjusted using a 1.2 mol / L sodium hydroxide solution. It is monitored in real time by a precision pH detection instrument and the addition is stopped when the pH value reaches 2.0.

[0072] Peracetic acid was selected as the oxidant, and the addition amount was 6 g / L. The peracetic acid solution was slowly and uniformly added (the drop rate was 3 drops / second) to the acid leaching solution, and the reaction container was placed in a constant temperature water bath with good temperature control accuracy. The reaction temperature was accurately controlled at 55°C, and the stirring speed was set to 150 rpm. Titanium and the oxidant were allowed to react continuously for 30 minutes, and the reaction phenomenon of the solution and the changes in various parameters were recorded regularly during this period.

[0073] Step 2:

[0074] After the reaction in step 1 is completed, a potassium hydroxide solution with a concentration of 0.8 mol / L is used to adjust the pH value of the solution until the pH value reaches 3.0.

[0075] Then, the solution was placed in a reaction device with precise temperature control, the temperature was adjusted to 65°C, the reaction stirring speed was set to 200 rpm, and the temperature was kept for 80 minutes to ensure that the titanium was fully hydrolyzed and precipitated. The remaining titanium content in the solution was regularly tested by chemical analysis methods to determine whether the hydrolysis and precipitation were sufficient.

[0076] Finally, a filter membrane (pore size of 0.22 μm) was used for filtration, and the filtered solution was collected for subsequent detection and analysis.

[0077] Recovery effect of valuable components: Advanced chemical analysis technology is used to detect the content of lithium, iron and phosphorus in the filtered solution, and the recovery rate is calculated by comparing with the corresponding element content of the original acid leaching solution. After detection and analysis, the recovery rate of lithium reached 94%, the recovery rate of iron reached 92%, and the recovery rate of phosphorus reached 90%, which further proves that this method can effectively reduce the loss of valuable components in the titanium removal link in the acid leaching treatment of waste lithium iron phosphate black powder from different sample sources, maintain a high recovery rate, and play a positive role in the full recycling of resources.

[0078] Environmental benefits: Since this method can accurately control the process, while effectively recovering valuable components, it avoids the potential environmental pollution risks caused by element loss and the introduction of impurity ions, and achieves a good combination of harmless treatment and resource recovery of waste batteries. Compared with the random discharge of waste battery acid leaching liquid that is not treated by this method, it can significantly reduce the pollution of environmental media such as soil and water, and reduce the risk of heavy metal components threatening the ecosystem and human health through the food chain. It meets environmental protection requirements and shows good environmental benefits.

[0079] Economic Benefit and Process Stability Analysis: From the perspective of economic benefit, due to the high recovery rate of valuable components, the raw material ratio is easier to control in the subsequent synthesis of related products, reducing the cost of raw material replenishment. It is estimated that the economic benefit can be improved by about 18% compared with the existing similar recovery technology. Moreover, in the process of repeating the experiment of this embodiment for many times, as long as the operation is strictly carried out in accordance with the set process parameters, stable experimental results can be obtained, reflecting the stability of the recovery process, which is conducive to its promotion and application in actual industrial production.

[0080] Embodiment 4:

[0081] Another batch of waste lithium iron phosphate batteries was selected, disassembled to obtain black powder, and then leached with sulfuric acid to obtain acid solution. Various specifications and calibrated experimental instruments and equipment were prepared, such as high-precision pH meters, reaction devices that can accurately control the dripping speed and temperature, filter membranes with different pore sizes, etc., to ensure that the experimental environment and equipment met the precise experimental requirements.

[0082] Step 1:

[0083] The batch of waste lithium iron phosphate black powder acid leaching liquid was carefully pretreated to remove possible large particle impurities and keep it in a uniform and stable state. The pH value was adjusted using a sodium hydroxide solution with a concentration of 1.5 mol / L and closely monitored by a high-precision pH detection instrument. When the pH value reached 1.8, the pH value adjustment was completed.

[0084] A mixed oxidant of hydrogen peroxide and peracetic acid (mixed in a mass ratio of 1:1) was selected, and the total addition amount was 4 g / L. The mixed oxidant solution was added to the acid leaching solution through a separatory funnel at a uniform and slow speed (dropping speed of 2 drops / second), and the reaction container was placed in a constant temperature water bath with precise temperature control. The reaction temperature was set to 45°C and the stirring speed was 250 rpm to allow titanium to fully contact the oxidant and undergo an oxidation reaction. The reaction lasted for 50 minutes. During the process, the color and odor of the solution were observed at any time to ensure the normal progress of the reaction.

[0085] Step 2:

[0086] After step 1, the pH value of the solution was adjusted with a potassium hydroxide solution having a concentration of 1.2 mol / L until the pH value reached 2.9.

[0087] Then, the solution was transferred to a reaction device with precise temperature control function, the temperature was adjusted to 55°C, the reaction stirring speed was set to 250rpm, and the reaction was kept warm for 70 minutes under this condition. During this period, the particle size of the particles formed by the hydrolysis and precipitation of titanium in the solution could be detected by instruments such as laser particle size analyzer to determine whether the hydrolysis and precipitation reached the ideal state.

[0088] Finally, a multi-layer composite filter membrane (with a comprehensive pore size of 0.3 μm) was used for filtration, and the filtrate was collected for subsequent detection and analysis of valuable components and impurities.

[0089] Valuable component recovery rate evaluation: Professional element quantitative analysis methods were used to detect the content of lithium, iron, and phosphorus in the filtrate, and the recovery rate was calculated by comparing with the original acid leaching solution. After testing, the recovery rate of lithium reached 92%, the recovery rate of iron reached 89%, and the recovery rate of phosphorus reached 87%. Although there may be certain differences in different batches of raw materials and specific operations, it still shows that this method can guarantee the recovery of valuable components to a certain extent, reduce losses in the titanium removal process, maintain a relatively high recovery rate level, and is conducive to the recycling of resources.

[0090] Monitoring of impurity ions and analysis of their impact on product quality: A comprehensive detection of impurity ions was performed on the filtrate after filtration, and no other impurity ions were found that were obviously introduced due to the titanium removal process. This ensures that the purity and quality of the recovered solution can be guaranteed during the subsequent processing of related products (such as the preparation of iron phosphate, etc.), thereby improving the competitiveness of the product in the market and further demonstrating the advantages of this method in controlling the introduction of impurities.

[0091] Analysis of the influence of process parameters on the overall effect: It can be seen from this example that different oxidant selection and dosage, specific pH value of each step, reaction temperature, stirring speed and reaction time and other parameter settings will have an impact on the final valuable component recovery rate, impurity ion situation, etc. The parameter value ranges and specific optional values ​​specified in the present invention provide operators with clear operating guidelines. As long as these parameters are accurately controlled within a reasonable range, the entire recovery process can achieve a relatively stable and ideal effect, highlighting the controllability and operability advantages of this process in practical applications, which is helpful for promotion and implementation in different industrial production scenarios.

[0092] Embodiment 5:

[0093] Prepare multiple sets of black powder acid leaching solutions from waste lithium iron phosphate batteries to fully verify the applicability and stability of this method under various conditions. At the same time, prepare sufficient and calibrated experimental equipment, including high-precision temperature control equipment, stirring equipment, pH detection equipment, and filtering devices of different specifications, to ensure that each experimental step and parameter can be accurately controlled and implemented.

[0094] Step 1:

[0095] Each group of waste lithium iron phosphate black powder acid leaching solution was subjected to strict pretreatment operations to ensure that the solution state was uniform and stable and there was no obvious impurity precipitation to interfere with subsequent reactions. The pH value was adjusted using a sodium hydroxide solution with a concentration of 1.3 mol / L, and the pH value of each group of solutions was adjusted to 1.4 with real-time and accurate monitoring using a precision pH detection instrument.

[0096] For the selection of oxidants, sodium peroxide, hydrogen peroxide, and peracetic acid were used in separate experiments in different groups, and the addition amount was set to 8g / L. The oxidant solution was added to the corresponding acid leaching solution at a uniform speed (dropping speed of 3 drops / second) through a separatory funnel, and the reaction container was placed in a constant temperature water bath pot with precise temperature control. The reaction temperature was uniformly set to 60°C and the stirring speed was 100rpm, so that titanium and the oxidant were fully in contact and oxidation reaction occurred. The reaction lasted for 20 minutes. During the reaction process, the reaction phenomenon and parameter changes of each group of solutions were recorded in detail for subsequent comparative analysis.

[0097] Step 2:

[0098] After the oxidation reaction of each group of step 1 was completed, a potassium hydroxide solution with a concentration of 1 mol / L was used to adjust the pH value of the solution, and the pH value of each group of solutions was adjusted to 2.3.

[0099] Each group of solutions was then transferred to an independent reaction device with precise temperature control. The temperature was uniformly adjusted to 70°C and the reaction stirring speed was set to 150rpm. The solutions were allowed to react under this condition for 100 minutes. During this period, chemical analysis was performed by regular sampling to determine whether the degree of hydrolysis and precipitation of titanium in each group of solutions met expectations, thereby ensuring that titanium was fully hydrolyzed and precipitated.

[0100] Finally, each group of solutions was filtered using a filter membrane of the same specifications (pore size of 0.5 μm), and the filtered solutions were collected for subsequent comparative detection and analysis, focusing on the differences in the recovery rate of valuable components and the introduction of impurity ions when different oxidants were used.

[0101] The influence of different oxidants on the recovery rate of valuable components: The lithium, iron and phosphorus contents in each group of filtered solutions were detected by professional chemical analysis methods, and the recovery rate was calculated by comparing the corresponding element contents in the original acid leaching solution. The results showed that when sodium peroxide was used as the oxidant, the recovery rate of lithium was 90%, the recovery rate of iron was 88%, and the recovery rate of phosphorus was 86%; when hydrogen peroxide was used as the oxidant, the recovery rate of lithium reached 93%, the recovery rate of iron was 91%, and the recovery rate of phosphorus was 89%; when peracetic acid was used as the oxidant, the recovery rate of lithium was 92%, the recovery rate of iron was 90%, and the recovery rate of phosphorus was 88%. It can be seen that different oxidants have a certain influence on the recovery rate of valuable components under this recovery method system, but as a whole, they can effectively reduce the element loss in the titanium removal process to a certain extent, and the parameter range set by the present invention is suitable for the application scenarios of different oxidants, which further verifies the versatility and effectiveness of the method.

[0102] Comparison of impurity ion situation and process stability: A comprehensive impurity ion detection and analysis was performed on each group of filtered solutions. It was found that no matter which oxidant was used, under the strictly controlled process parameters of this method, no other obvious impurity ions were introduced, ensuring the purity of the recovered solution and the stability of the subsequent product quality.

[0103] At the same time, in the process of repeating each set of experiments many times, as long as the operation is strictly carried out according to the set parameters, relatively stable and similar experimental results can be obtained, which once again demonstrates that the recycling process has strong controllability and is not greatly affected by the differences in the types of oxidants. It provides a basis for the flexible selection of oxidants according to specific circumstances in actual production, and is helpful to promote the application of this method in a wider range of waste lithium iron phosphate battery recycling fields, improve the overall resource recovery level, and achieve good economic benefits, environmental benefits and resource recycling goals.

[0104] The relevant tables supplemented according to the above embodiments are intended to more clearly and intuitively show the comparison of key parameters, experimental results and other information in each embodiment. You can adjust them according to actual needs:

[0105] Table 1: Comparison of key parameter settings in step 1 of each embodiment

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[0109] Table 2: Comparison of key parameter settings in step 2 of various embodiments

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[0111] Table 3: Comparison of the recovery rate of valuable components in each example

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[0114] Table 4: Comparison of economic and environmental benefits of various examples

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[0117] Through the above Tables 1-4, we can clearly see the changes in key parameters of different embodiments during the experiment, as well as the comparative results of the corresponding valuable component recovery rate, economic benefits and environmental benefits, which is helpful to more intuitively analyze the performance and advantages of the valuable component resource recovery method in waste lithium iron phosphate batteries.

[0118] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for recycling valuable components in waste lithium iron phosphate batteries, characterized in that: The following steps are involved: Step 1: Pre-treat the waste lithium iron phosphate black powder acid leaching solution after sulfuric acid leaching to ensure that the solution is in a uniform and stable state and there is no obvious impurity precipitation that interferes with subsequent operations; Use sodium hydroxide solution and slowly add it into the pickling solution; At the same time, the pH value is monitored in real time by a precision pH detection instrument, and after adjusting the pH value to 1.0 to 2.2, a suitable oxidant is selected from one or more of sodium peroxide, hydrogen peroxide, and peracetic acid and added to the acid leaching solution; During the addition process, a uniform dripping method is used to ensure that the oxidant is evenly dispersed in the solution. Under a set stirring speed of 0 to 300 rpm, a temperature control device is used to accurately control the reaction temperature to 15 to 70°C, so that the titanium in the acid leaching solution can fully contact with the oxidant and undergo an oxidation reaction under this environment, and the reaction lasts for 10 to 60 minutes; Step 2: After the oxidation reaction in step 1 is completed, potassium hydroxide solution is selected and added to the resulting liquid again, and the pH value is adjusted to 2.3-3.2 by means of high-precision pH monitoring means; Then, the solution is placed in a reaction device with precise temperature control, the temperature is adjusted to 30-70°C, and the reaction stirring speed is set to 150-300rpm. The solution is kept warm and reacted under this condition for 10-100 minutes to allow the titanium to be fully hydrolyzed and precipitated, and then filtered through filter paper or filter membrane to separate the titanium from the main body of the solution.

2. The method for recycling valuable components in waste lithium iron phosphate batteries according to claim 1, characterized in that: The specific pH value of adding alkali solution to adjust the pH value in step 1 is 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 or 2.

2.

3. The method for recycling valuable components in waste lithium iron phosphate batteries according to claim 1, characterized in that: In the step 1, the amount of the oxidant added is 0.1 g / L, 0.5 g / L, 1 g / L, 2 g / L, 4 g / L, 6 g / L, 8 g / L or 10 g / L.

4. The method for recycling valuable components in waste lithium iron phosphate batteries according to claim 1, characterized in that: The stirring speed in step 1 is 0 rpm, 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm or 300 rpm.

5. The method for recycling valuable components in waste lithium iron phosphate batteries according to claim 1, characterized in that: The reaction temperature in the step 1 is 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

6. The method for recycling valuable components in waste lithium iron phosphate batteries according to claim 1, characterized in that: The reaction time in step 1 is 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

7. The method for recycling valuable components in waste lithium iron phosphate batteries according to claim 1, characterized in that: The specific pH value of adding alkali solution to adjust the pH value in step 2 is 2.3, 2.5, 2.7, 2.9, 3.0, 3.1 or 3.

2.

8. The method for recycling valuable components in waste lithium iron phosphate batteries according to claim 1, characterized in that: The reaction temperature in step 2 is 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

9. The method for recycling valuable components in waste lithium iron phosphate batteries according to claim 1, characterized in that: The reaction stirring speed in step 2 is 150 rpm, 200 rpm, 250 rpm or 300 rpm.

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