Method for preparing battery-grade iron phosphate dihydrate from waste acid solution containing iron and manganese

Abstract

The invention provides a method for preparing battery-grade iron phosphate dihydrate from an iron-manganese-containing waste acid solution. The method comprises the following steps: adding hydrogen peroxide into the iron-manganese-containing waste acid solution, and heating for reaction; extracting the iron-manganese-containing waste acid solution after the heating reaction by using an extracting agent and sulfonated kerosene to form two-phase separation so as to obtain an iron-containing organic mixed solution; washing the iron-containing organic mixed liquid with pure water; treating the iron-containing organic impurity liquid with dilute sulfuric acid to remove impurities so as to obtain an iron-containing organic solution; carrying out reverse extraction on the iron-containing organic solution by taking phosphoric acid as a reverse extraction agent, separating two phases, and collecting a water phase to obtain an iron-rich solution; adding ammonia water into the iron-rich solution to adjust the pH value, adding a surfactant, heating to a fixed temperature, carrying out an iron precipitation reaction, and carrying out solid-liquid separation to obtain an iron-containing precipitate; and washing and drying the iron-containing precipitate to obtain the battery-grade iron phosphate dihydrate. According to the method, the iron resource in the waste acid solution containing iron and manganese is converted into the battery-grade iron phosphate dihydrate, so that the reutilization of the resource is realized, and the damage and pollution to the environment are reduced.

Description

Technical Field

[0001] The present application relates to the technical field of resource recycling, and in particular to a method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid liquid. Background Art

[0002] Tantalum and niobium, as a key strategic resource, play an indispensable role in many high-tech fields such as electronics, aviation, physical therapy and chemical industry due to their unique physical and chemical properties. In the industrial production process of tantalum and niobium, hydrometallurgy is a widely used refining technology. However, this refining method is often accompanied by the generation of a large amount of iron-containing waste liquid. The iron element in these waste liquids is enriched as a companion element. If it is directly discharged without proper treatment, it will not only lead to a huge waste of resources, but also may cause serious pollution to the environment. Summary of the invention

[0003] The present application provides a method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid solution, which is beneficial to reducing resource waste and environmental pollution.

[0004] In a first aspect, an embodiment of the present application provides a method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid solution, the method comprising:

[0005] Adding hydrogen peroxide to the iron-manganese-containing waste acid solution and heating for reaction;

[0006] The iron-manganese-containing waste acid liquid after the heating reaction is extracted using an extractant and sulfonated kerosene to form a two-phase separation to obtain an iron-containing organic impurity liquid;

[0007] Using pure water to wash the iron-containing organic liquid;

[0008] Treating the iron-containing organic liquid with dilute sulfuric acid to remove impurities, thereby obtaining an iron-containing organic solution;

[0009] Using phosphoric acid as a stripping agent to strip the iron-containing organic solution, separating the two phases, and collecting the aqueous phase to obtain an iron-rich solution;

[0010] Ammonia water is added to the iron-rich solution to adjust the pH, and a surfactant is added, and the temperature is raised to a fixed temperature to perform an iron precipitation reaction, and solid-liquid separation is performed to obtain an iron-containing precipitate;

[0011] The iron-containing precipitate is washed and dried to obtain battery-grade iron phosphate dihydrate.

[0012] According to the first aspect, in a possible implementation, the molar ratio of the amount of hydrogen peroxide added to the divalent iron ions in the iron-manganese waste acid solution is (0.5-1.2):1, and the oxidation temperature is 40-70°C.

[0013] According to the first aspect, in a possible implementation method, in the step of using an extractant and sulfonated kerosene to extract the iron-manganese-containing waste acid liquid after the heating reaction to form a two-phase separation to obtain an iron-containing organic impurity liquid, the extraction conditions are: extraction pH<1, the concentration of the extractant and the sulfonated kerosene is (10% to 50%): (50% to 90%), the extraction phase ratio O / A is 0.5 to 2.5, the extraction time is 10 to 30 min, and the extraction level is 1 to 4.

[0014] According to the first aspect, in a possible implementation, in the step of washing the iron-containing organic impurities with pure water, the pure water washing conditions are: A / O ratio of 0.2 to 0.6, washing time of 5 to 10 minutes, and washing level of 1 to 2.

[0015] According to the first aspect, in a possible implementation, in the step of treating the iron-containing organic liquid with dilute sulfuric acid to remove impurities to obtain an iron-containing organic solution, the conditions for washing with dilute sulfuric acid are: a dilute sulfuric acid concentration of 0.5 to 2 mol / L, an A / O ratio of 0.5 to 2, a washing time of 10 to 20 minutes, and a washing number of 2 to 4 times.

[0016] According to the first aspect, in a possible implementation method, in the step of stripping the iron-containing organic solution with phosphoric acid as a stripping agent, separating the two phases, and collecting the aqueous phase to obtain an iron-rich solution, the phosphoric acid concentration is 7 to 14 mol / L, the stripping phase ratio A / O is 1 to 3, the stripping time is 10 to 30 min, and the stripping level is 1 to 5.

[0017] According to the first aspect, in a possible implementation manner, the surfactant is one or more of CTAB, SDBS, PVP, PEG, and PVA.

[0018] According to the first aspect, in a possible implementation, in the step of adding ammonia water to the iron-rich solution to adjust the pH, adding a surfactant, heating to a fixed temperature for iron precipitation reaction, and solid-liquid separation to obtain an iron-containing precipitate, the reaction pH is 1 to 4, the amount of the surfactant used is 0.5% to 3% of the mass of iron in the iron-rich solution, the reaction temperature is 70 to 95°C, and the reaction time is 3 to 8 hours.

[0019] According to the first aspect, in a possible implementation, in the step of washing and drying the iron-containing precipitate to obtain battery-grade ferric phosphate dihydrate, the washing liquid is an ethanol-water mixture with an O / A of 1.

[0020] The present application provides a method for preparing battery-grade iron phosphate dihydrate from iron-manganese waste acid liquid. The present invention adopts the iron-manganese waste acid liquid after wet extraction of tantalum and niobium as raw material to prepare battery-grade iron phosphate dihydrate that meets industry standards, thereby realizing resource recycling. In addition, the iron in the waste liquid is extracted by extraction, and pure water and dilute sulfuric acid are used for impurity removal, and the resulting battery-grade iron phosphate dihydrate has a higher purity; using phosphoric acid to strip iron, compared with the prior art using high-concentration sulfuric acid to strip iron, directly provides a phosphorus source for synthesizing battery-grade iron phosphate dihydrate, which not only simplifies the process flow of synthesizing iron phosphate, but also reduces the synthesis cost of iron phosphate. In the process of preparing battery-grade iron phosphate dihydrate, an appropriate amount of surfactant is added. An appropriate amount of surfactant can ensure that the surface of the particles is evenly coated to form a protective film, which helps to maintain the stability and dispersibility of the particles, avoid agglomeration, and make the prepared battery-grade iron phosphate dihydrate particles more regular. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 The present invention is a schematic flow chart of a method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid solution according to an embodiment;

[0023] Figure 2 The present invention is a flowchart of a method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid solution according to an embodiment. DETAILED DESCRIPTION

[0024] The words "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0025] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0027] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0028] The present invention provides a method for preparing battery-grade ferric phosphate dihydrate from waste acid solution containing iron and manganese, such as Figure 1 and Figure 2 As shown, the method comprises the following steps:

[0029] Step S10, adding hydrogen peroxide to the iron-manganese-containing waste acid solution and heating for reaction;

[0030] The iron-manganese-containing waste acid liquid can be the iron-manganese-containing waste acid liquid obtained after tantalum-niobium extraction by wet process.

[0031] An appropriate amount of hydrogen peroxide is added to the waste acid solution at a molar ratio of hydrogen peroxide to divalent iron ions of (0.5-1.2): 1. This ratio is selected to ensure that the divalent iron can be completely oxidized to trivalent iron while avoiding excessive use of hydrogen peroxide.

[0032] The waste acid solution after adding hydrogen peroxide is heated to 40-70°C and maintained in this temperature range for reaction. The purpose of heating is to accelerate the oxidation reaction and improve the reaction efficiency. The reaction time is set to 0.5 hours to ensure that the divalent iron can be fully oxidized to trivalent iron.

[0033] Since the divalent iron ion (Fe 2+ ) usually appears green in solution, while trivalent iron (Fe 3+ ) is yellow or light yellow, so the change in solution color can be used as a visual indicator of the reaction. During the reaction, it can be observed that the color of the solution gradually changes from green to light yellow.

[0034] Among them, the main components of the iron-manganese waste acid solution after wet extraction of tantalum and niobium are shown in Table 1 below

[0035] Table 1: Main components in iron-manganese wastewater

[0036]

[0037] Step S20, using an extractant and sulfonated kerosene to extract the iron-manganese-containing waste acid liquid after the heating reaction to form a two-phase separation to obtain an iron-containing organic impurity liquid;

[0038] When the organic phase formed by mixing the extractant P507 with sulfonated kerosene is used to extract the iron-manganese waste liquid, the organic phase will contain the metal elements that are effectively extracted by P507. Specifically, during the extraction process, iron ions and manganese ions are likely to be extracted into the organic phase in large quantities, and zinc and copper may be extracted into the organic phase, while the content of zinc and copper is originally very low. Therefore, the main impurity extracted into the organic phase is manganese.

[0039] The extractant P507 and sulfonated kerosene are mixed uniformly according to a predetermined concentration ratio (10% to 50%): (50% to 90%) to form an organic phase. The selection of this concentration ratio is intended to optimize the extraction efficiency while controlling the cost.

[0040] The pH of the spent acid solution is adjusted to below 1 using an appropriate acid or base to ensure a high distribution ratio of the iron ions in the extractant.

[0041] The waste acid liquid with adjusted pH value and the organic phase are poured into the extraction equipment according to the predetermined O / A ratio (0.5-2.5). The selection of the ratio is crucial to the extraction efficiency. Too low may lead to incomplete extraction, while too high may increase the difficulty and cost of subsequent treatment.

[0042] During the extraction process, maintain an appropriate stirring speed and time (10 to 30 minutes) to ensure that the two phases are fully contacted and separated. The choice of stirring speed and time needs to be adjusted according to the specific extraction conditions and equipment.

[0043] After the extraction is completed, the organic phase and the aqueous phase are separated by standing or centrifuging. At this time, the organic phase contains the extracted iron ions and other impurities to form an iron-containing organic liquid.

[0044] If you need to further improve the extraction efficiency, you can perform multi-stage extraction. Each stage of extraction is performed according to the above steps, but you need to pay attention to adjusting the ratio between each stage and the extraction time and other conditions. For example, you can perform 4-stage extraction.

[0045] The extraction efficiency of iron ions can be significantly improved by precisely controlling the concentration of the extractant, the pH value of the waste acid, the phase ratio, the extraction time and the number of stages.

[0046] Step S30, washing the iron-containing organic liquid with pure water;

[0047] By washing with pure water, impurities such as potassium, sodium, and fluorine in the iron-containing organic liquid can be efficiently removed to obtain a purer iron-containing organic phase, which facilitates subsequent processing and extraction.

[0048] According to the predetermined volume ratio of pure water to iron-containing organic liquid (A / O ratio is 0.2-0.6), a proper amount of pure water is measured and added into the washing equipment.

[0049] Slowly pour the iron-containing organic liquid into the washing equipment and turn on the stirring device to fully mix the pure water and the iron-containing organic liquid. The stirring speed and time need to be adjusted according to the specifications of the washing equipment and the washing conditions to ensure the washing effect.

[0050] Keep stirring and wash for 5 to 10 minutes. The length of washing time will affect the washing efficiency and washing effect, and the best value needs to be determined based on experiments.

[0051] After washing is completed, the washing liquid is separated from the iron-containing organic phase by standing. At this time, the washing liquid mainly contains the impurities to be removed.

[0052] If the purity of the iron-containing organic phase after the first washing still does not meet the requirements, multi-stage washing can be performed. In multi-stage washing, the A / O ratio, washing time, and washing stages should be adjusted according to the effect of the previous stage washing and the purity of the iron-containing organic phase. Each stage of washing is carried out according to the steps of the first washing, but it is necessary to control the washing conditions between each stage to ensure the washing effect.

[0053] Step S40, treating the iron-containing organic liquid with dilute sulfuric acid to remove impurities to obtain an iron-containing organic solution;

[0054] Dilute sulfuric acid can react with various impurities in the iron-containing organic solution, such as reacting with metal complexes to form soluble sulfates, thereby transferring these impurities from the organic phase to the aqueous phase. Through subsequent separation steps, these impurities can be effectively removed from the iron-containing organic solution, thereby improving the quality and stability of the final product.

[0055] According to the predetermined dilute sulfuric acid concentration (0.5-2 mol / L), measure an appropriate amount of concentrated sulfuric acid and dilute it with pure water to the required concentration. Ensure that the concentration of dilute sulfuric acid is accurate to avoid adverse effects on iron-containing organic impurities.

[0056] According to the predetermined volume ratio of dilute sulfuric acid to iron-containing organic liquid (A / O ratio is 0.5-2), a proper amount of dilute sulfuric acid is measured and added into the treatment equipment.

[0057] Slowly pour the iron-containing organic liquid into the treatment equipment and turn on the stirring device to fully mix the dilute sulfuric acid with the iron-containing organic liquid. The stirring speed and time need to be adjusted according to the specifications of the treatment equipment and the treatment conditions to ensure the treatment effect.

[0058] Keep stirring and treat with dilute sulfuric acid for 10 to 20 minutes. The treatment time will affect the removal efficiency of impurities and the purity of the iron-containing organic solution, and the optimal value needs to be determined based on experiments.

[0059] After the treatment is completed, the treated liquid is separated from the iron-containing organic solution by standing. At this time, the treated liquid mainly contains the removed impurities and the waste acid generated by the reaction.

[0060] If the purity of the iron-containing organic solution after the first treatment still does not meet the requirements, multiple dilute sulfuric acid treatments can be performed, for example, the number of washings can be 2 to 4 times. In multiple treatments, the concentration of dilute sulfuric acid, A / O ratio, treatment time, and number of treatments need to be adjusted according to the effect of the previous treatment and the purity of the iron-containing organic solution. Each treatment is carried out according to the steps of the first treatment, but it is necessary to control the differences in conditions between each treatment to ensure the treatment effect.

[0061] Step S50, stripping the iron-containing organic solution with phosphoric acid as a stripping agent, separating the two phases, and collecting the aqueous phase to obtain an iron-rich solution;

[0062] The phosphoric acid concentration is 7-14 mol / L. Phosphoric acid within this concentration range has good selectivity. Phosphoric acid can selectively react with the iron element in the iron-containing organic solution to form a soluble iron phosphate compound; while it reacts less to other impurities or unnecessary elements, thereby reducing the introduction of impurities. The soluble iron phosphate compound has a high solubility in the aqueous phase, thereby improving the extraction efficiency of the iron element.

[0063] Phosphoric acid also shows good stability within this concentration range and is not prone to decomposition or degradation, ensuring the smooth progress of the stripping process. By optimizing the concentration of phosphoric acid, it is possible to ensure that as much iron as possible is transferred from the organic phase to the aqueous phase.

[0064] According to the predetermined stripping phase ratio A / O (i.e. the volume ratio of phosphoric acid to the iron-containing organic solution, which is 1 to 3), a proper amount of phosphoric acid is measured and added to the stripping equipment.

[0065] Turn on the stirring device to fully mix the phosphoric acid and the iron-containing organic solution. The stirring speed and time need to be adjusted according to the specifications of the stripping equipment and the stripping conditions to ensure the stripping effect.

[0066] Keep stirring and perform stripping for 10 to 30 minutes. The stripping time will affect the extraction efficiency of iron and the purity of the iron-rich solution, and the optimal value needs to be determined based on experiments.

[0067] After stripping is completed, the organic phase and the aqueous phase are separated by standing. At this time, the aqueous phase is rich in iron, while the organic phase contains less iron and other organic matter.

[0068] If the concentration of iron in the aqueous phase after the first stripping still does not meet the requirements, multi-stage stripping can be performed; for example, the number of stripping stages can be 1 to 5. In multi-stage stripping, the phosphoric acid concentration, stripping ratio A / O, stripping time, and stripping stages need to be adjusted according to the effect of the previous stripping and the concentration of iron in the aqueous phase. Each stripping stage is carried out according to the steps of the first stripping, but it is necessary to control the difference in conditions between each stage to ensure the stripping effect.

[0069] Step S60, adding ammonia water to the iron-rich solution to adjust the pH, adding a surfactant, heating to a fixed temperature to perform an iron precipitation reaction, and performing solid-liquid separation to obtain an iron-containing precipitate;

[0070] Ammonia (NH3·H2O) is added to the iron-rich solution to adjust the pH value of the solution to a range of 1 to 4. This pH range is generally favorable for the precipitation of iron, while above this range, iron ions (Fe3+) may form water-insoluble iron hydroxide (Fe(OH)3) precipitates.

[0071] After adjusting the pH value, a surfactant is added to the solution. The surfactant may be one or more of CTAB (cetyltrimethylammonium bromide), SDBS (sodium dodecylbenzene sulfonate), PVP (polyvinyl pyrrolidone), PEG (polyethylene glycol) or PVA (polyvinyl alcohol).

[0072] The amount of surfactant used is 0.5% to 3% of the mass of iron in the iron-rich solution. An appropriate amount of surfactant can ensure that the surface of the particles is evenly coated to form a protective film, which helps to maintain the stability and dispersibility of the particles, avoid agglomeration, and make the prepared battery-grade iron phosphate dihydrate particles more regular.

[0073] The solution is heated to a fixed temperature of 70-95°C. High temperature can promote the rate of chemical reactions, thereby accelerating the precipitation process of iron. At the same time, high temperature may also affect the crystal structure and purity of the precipitate.

[0074] Under the above conditions, the iron precipitation reaction is carried out. The reaction time is usually 3 to 8 hours to ensure that the reaction is fully carried out.

[0075] After the reaction is completed, the iron-containing precipitate is separated from the solution by solid-liquid separation technology (such as filtration, centrifugation, etc.). In this way, the iron-containing precipitate can be obtained, and the other components in the solution can be recovered or processed.

[0076] Step S70: washing and drying the iron-containing precipitate to obtain battery-grade iron phosphate dihydrate.

[0077] First, the iron-containing precipitate is washed to remove impurities and unreacted raw materials attached to the surface of the precipitate to improve the purity and quality of the product.

[0078] The washing liquid is an ethanol-water mixture, wherein the ratio of ethanol (O) to water (A) is 1:1 (i.e., O / A is 1). As a washing liquid, the ethanol-water mixture has good solubility and volatility, and can effectively remove impurities on the surface of the sediment while avoiding the introduction of new pollutants.

[0079] During the washing process, multiple washings can be performed to ensure that impurities on the surface of the precipitate are fully removed. After each washing, the washing liquid can be separated from the precipitate by filtering or centrifuging.

[0080] After washing, the precipitate is dried to remove moisture and volatile substances from the precipitate to obtain a dry ferric phosphate dihydrate product.

[0081] Drying can be done at an appropriate temperature to ensure that moisture and volatile materials are adequately removed while avoiding product decomposition or deterioration.

[0082] The dried product should be adequately cooled and stored to ensure its quality and stability.

[0083] The product after washing and drying should reach the quality standard of battery grade ferric phosphate dihydrate, with high purity and good physical and chemical properties to meet the requirements of battery materials.

[0084] The present invention uses the iron-manganese waste acid liquid after wet extraction of tantalum and niobium as raw material to prepare battery-grade iron phosphate dihydrate that meets industry standards, thereby realizing resource recycling. In addition, the iron in the waste liquid is extracted by extraction, and pure water and dilute sulfuric acid are used for impurity removal, so that the obtained battery-grade iron phosphate dihydrate has higher purity; the use of phosphoric acid to strip iron directly provides a phosphorus source for synthesizing battery-grade iron phosphate dihydrate, compared with the prior art using high-concentration sulfuric acid to strip iron, which not only simplifies the process flow of synthesizing iron phosphate, but also reduces the synthesis cost of iron phosphate. In the process of preparing battery-grade iron phosphate dihydrate, an appropriate amount of surfactant is added. The appropriate amount of surfactant can ensure that the surface of the particles is evenly coated to form a protective film, which helps to maintain the stability and dispersibility of the particles, avoid agglomeration, and make the prepared battery-grade iron phosphate dihydrate particles more regular.

[0085] In a first embodiment:

[0086] This embodiment is a method for preparing battery-grade ferric phosphate dihydrate from iron-manganese waste acid solution after wet extraction of tantalum and niobium, comprising the following steps:

[0087] (1) adding hydrogen peroxide to the iron-manganese waste acid solution after wet extraction of tantalum and niobium as shown in Table 1, wherein the molar ratio of the amount of hydrogen peroxide added to the divalent iron ion is 0.8, heating to 60° C. for reaction for 0.5 h, oxidizing the divalent iron into trivalent iron, and after the reaction, the solution changes from green to light yellow;

[0088] (2) using an extractant of 40% P507 + sulfonated kerosene to extract the iron-manganese waste acid liquid, the extraction phase O / A is 1, the extraction time is 15 min, the extraction level is 3, and the two phases are separated to obtain an iron-containing organic impurity liquid;

[0089] (3) washing the iron-containing organic liquid with pure water twice, wherein the A / O ratio is 0.4 and the washing time is 5 min, so as to wash away the fluoride ions in the organic liquid;

[0090] (4) washing the iron-containing organic liquid three times with dilute sulfuric acid having a concentration of 0.5 mol / L, wherein the A / O ratio is 2 and the washing time is 10 min, to remove manganese in the liquid and obtain an iron-containing organic solvent;

[0091] (5) using 12 mol / L phosphoric acid as a stripping agent to strip the iron-containing organic solution, the stripping ratio A / O is 1, the stripping time is 15 min, the stripping stage is 3, the two phases are separated, and the aqueous phase is collected to obtain an iron-rich solution;

[0092] (6) Using ammonia water to adjust the pH of the iron-rich solution to 2, adding CTAB, the mass of CTAB is 1.5% of the mass of iron in the iron-rich solution, heating to 80° C., and reacting for 5 hours;

[0093] (7) After the iron precipitation reaction is completed, the mixed solution is cooled to room temperature, solid-liquid separation is performed, and the mixture is washed with a 1:1 mixture of ethanol and water, and dried to obtain a battery-grade iron phosphate product.

[0094] In the second embodiment:

[0095] This embodiment is a method for preparing battery-grade ferric phosphate dihydrate from iron-manganese waste acid solution after wet extraction of tantalum and niobium, comprising the following steps:

[0096] (1) adding hydrogen peroxide to the iron-manganese waste acid solution after wet extraction of tantalum and niobium as shown in Table 1, wherein the molar ratio of the amount of hydrogen peroxide added to the divalent iron ion is 0.7, heating to 70° C. for reaction for 0.5 h, oxidizing the divalent iron into trivalent iron, and after the reaction, the solution changes from green to light yellow;

[0097] (2) using an extractant of 30% P507 + sulfonated kerosene to extract the iron-manganese-containing waste acid liquid, the extraction phase O / A is 2, the extraction time is 20 min, the extraction level is 2, and the two phases are separated to obtain an iron-containing organic impurity liquid;

[0098] (3) washing the iron-containing organic liquid twice with pure water, wherein A / O is 0.5 and the washing time is 5 min, so as to wash away the fluoride ions in the organic liquid;

[0099] (4) washing the iron-containing organic liquid twice with dilute sulfuric acid having a concentration of 1 mol / L, wherein the A / O ratio is 1.5 and the washing time is 12 min, to remove manganese in the liquid and obtain an iron-containing organic solvent;

[0100] (5) using 9 mol / L phosphoric acid as a stripping agent to countercurrently strip the iron-containing organic solution, the stripping ratio A / O is 1, the stripping time is 20 min, the stripping stage is 3, the two phases are separated, and the aqueous phase is collected to obtain an iron-rich solution;

[0101] (6) Using ammonia water to adjust the pH of the iron-rich solution to 1.5, adding CTAB, the mass of CTAB is 2% of the mass of iron in the iron-rich solution, heating to 70° C., and reacting for 5 hours;

[0102] (7) After the iron precipitation reaction is completed, the mixed solution is cooled to room temperature, solid-liquid separation is performed, and the mixture is washed with a 1:1 mixture of ethanol and water, and dried to obtain a battery-grade iron phosphate product.

[0103] In the third embodiment:

[0104] This embodiment is a method for preparing battery-grade ferric phosphate dihydrate from iron-manganese waste acid solution after wet extraction of tantalum and niobium, comprising the following steps:

[0105] (1) adding hydrogen peroxide to the waste acid solution rich in iron and manganese after the wet process of tantalum and niobium extraction as shown in Table 1, wherein the molar ratio of the amount of hydrogen peroxide added to the divalent iron ion is 1, heating to 50° C. for reaction for 0.5 h, oxidizing the divalent iron into trivalent iron, and after the reaction, the solution changes from green to light yellow;

[0106] (2) using an extractant P40% 507 + sulfonated kerosene to extract the iron-manganese-containing waste acid liquid, the extraction phase O / A is 3, the extraction time is 25 min, the extraction level is 1, and the two phases are separated to obtain an iron-containing organic impurity liquid;

[0107] (3) washing the iron-containing organic liquid twice with pure water, wherein A / O is 0.3 and the washing time is 8 min, so as to wash away the fluoride ions in the organic liquid;

[0108] (4) washing the iron-containing organic liquid three times with dilute sulfuric acid having a concentration of 1 mol / L, wherein the A / O ratio is 1 and the washing time is 15 min, to remove manganese in the liquid and obtain an iron-containing organic solvent;

[0109] (5) using 10 mol / L phosphoric acid as a stripping agent to countercurrently strip the iron-containing organic solution, the stripping phase A / O is 2, the stripping time is 30 min, the stripping stage is 2, the two phases are separated, and the aqueous phase is collected to obtain an iron-rich solution;

[0110] (6) Using ammonia water to adjust the pH of the iron-rich solution to 2.5, adding CTAB with a mass of 1.8% of the mass of iron in the iron-rich solution, heating to 90° C., and reacting for 5 h;

[0111] (7) After the iron precipitation reaction is completed, the mixed solution is cooled to room temperature, solid-liquid separation is performed, and the mixture is washed with a 1:1 mixture of ethanol and water, and dried to obtain a battery-grade ferric phosphate dihydrate product.

[0112] The test results of the iron phosphate dihydrate prepared in the first embodiment, the second embodiment and the third embodiment are shown in Table 2

[0113] Table 2: Quality test results of ferric phosphate dihydrate

[0114]

[0115] From the test data of each embodiment in Table 2, it is found that the quality of the battery-grade iron phosphate dihydrate prepared by the present invention perfectly meets the various strict requirements of the existing battery-grade iron phosphate dihydrate. Moreover, the production process of preparing battery-grade iron phosphate dihydrate using the iron-manganese waste acid liquid after wet extraction of tantalum and niobium as raw material is not only simple and efficient, but also shows significant advantages in cost control.

[0116] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the method of the present invention, addition of auxiliary steps, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid solution, characterized in that: The method comprises: Adding hydrogen peroxide to the iron-manganese-containing waste acid solution and heating for reaction; The iron-manganese-containing waste acid liquid after the heating reaction is extracted using an extractant and sulfonated kerosene to form a two-phase separation to obtain an iron-containing organic impurity liquid; Using pure water to wash the iron-containing organic liquid; Treating the iron-containing organic liquid with dilute sulfuric acid to remove impurities, thereby obtaining an iron-containing organic solution; Using phosphoric acid as a stripping agent to strip the iron-containing organic solution, separating the two phases, and collecting the aqueous phase to obtain an iron-rich solution; Ammonia water is added to the iron-rich solution to adjust the pH, and a surfactant is added, and the temperature is raised to a fixed temperature to perform an iron precipitation reaction, and solid-liquid separation is performed to obtain an iron-containing precipitate; The iron-containing precipitate is washed and dried to obtain battery-grade iron phosphate dihydrate.

2. The method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid liquid according to claim 1, characterized in that: The molar ratio of the amount of hydrogen peroxide added to the divalent iron ions in the iron-manganese waste acid solution is (0.5-1.2):1, and the oxidation temperature is 40-70°C.

3. The method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid liquid according to claim 1, characterized in that: In the step of using an extractant and sulfonated kerosene to extract the iron-manganese-containing waste acid liquid after the heating reaction to separate the two phases and obtain an iron-containing organic impurity liquid, the extraction conditions are: extraction pH<1, the concentrations of the extractant and the sulfonated kerosene are (10% to 50%): (50% to 90%), the extraction phase ratio O / A is 0.5 to 2.5, the extraction time is 10 to 30 minutes, and the extraction level is 1 to 4.

4. The method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid liquid according to claim 1, characterized in that: In the step of washing the iron-containing organic impurities with pure water, the pure water washing conditions are: A / O ratio of 0.2 to 0.6, washing time of 5 to 10 minutes, and washing level of 1 to 2 levels.

5. The method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid liquid according to claim 1, characterized in that: In the step of treating the iron-containing organic liquid with dilute sulfuric acid to remove impurities and obtain an iron-containing organic solution, the conditions for washing with dilute sulfuric acid are: dilute sulfuric acid concentration of 0.5-2 mol / L, A / O ratio of 0.5-2, washing time of 10-20 minutes, and washing times of 2-4 times.

6. The method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid solution according to claim 1, characterized in that: In the step of using phosphoric acid as a stripping agent to strip the iron-containing organic solution, separating the two phases, and collecting the aqueous phase to obtain an iron-rich solution, the phosphoric acid concentration is 7-14 mol / L, the stripping phase ratio A / O is 1-3, the stripping time is 10-30 min, and the stripping stage is 1-5.

7. The method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid liquid according to claim 1, characterized in that: The surfactant is one or more of CTAB, SDBS, PVP, PEG, and PVA.

8. The method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid solution according to claim 7, characterized in that: In the step of adding ammonia water to the iron-rich solution to adjust the pH, adding a surfactant, heating to a fixed temperature to carry out an iron precipitation reaction, and separating the solid and liquid to obtain an iron-containing precipitate, the reaction pH is 1 to 4, the amount of the surfactant used is 0.5% to 3% of the mass of iron in the iron-rich solution, the reaction temperature is 70 to 95° C., and the reaction time is 3 to 8 hours.

9. The method for preparing battery-grade ferric phosphate dihydrate from iron-manganese-containing waste acid solution according to claim 1, characterized in that: In the step of washing and drying the iron-containing precipitate to obtain battery-grade ferric phosphate dihydrate, the washing liquid is a mixture of ethanol and water, and the O / A is 1.

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