CN117003211A - Preparation method of battery-grade ferric phosphate - Google Patents
Preparation method of battery-grade ferric phosphate Download PDFInfo
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- CN117003211A CN117003211A CN202310842776.7A CN202310842776A CN117003211A CN 117003211 A CN117003211 A CN 117003211A CN 202310842776 A CN202310842776 A CN 202310842776A CN 117003211 A CN117003211 A CN 117003211A
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- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
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- C01B25/375—Phosphates of heavy metals of iron
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- C01P2004/52—Particles with a specific particle size distribution highly monodisperse size distribution
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Abstract
The invention provides a preparation method of battery-grade ferric phosphate, which belongs to the technical field of battery material recycling, and comprises the following steps: removing carbon from iron phosphate carbon slag serving as a raw material to obtain slurry liquid; reducing the slurry to obtain a ferrous solution; respectively removing heavy metals and aluminum from the ferrous solution to obtain a purified solution; and (3) carrying out oxidation aging reaction on the purifying liquid to obtain the battery grade ferric phosphate. The preparation method provided by the invention is simple, has high utilization rate, is more suitable for preparing large-batch battery-level ferric phosphate in the production process, solves the problem that the iron phosphate carbon residue obtained after the lithium extraction of the traditional waste lithium iron phosphate battery cannot be recovered, not only avoids the waste of ferric phosphate resources, but also achieves the purpose of environmental protection, avoids environmental pollution, and the recovered ferric phosphate is a battery-level raw material and can be put into the production process of the power battery again.
Description
Technical Field
The invention belongs to the technical field of battery material recycling, and particularly relates to a preparation method of battery-grade ferric phosphate and a preparation method thereof.
Background
The power battery is a power source for providing power for tools, and is a storage battery for providing power for electric automobiles, electric trains, electric bicycles and golf carts. Which is mainly distinguished from a starting battery for starting an engine of an automobile. At present, the new energy power battery is mainly a lithium iron phosphate battery.
With the wide use of new energy automobiles, a large amount of waste batteries will be generated. Aiming at the treatment of the waste batteries, on one hand, the improper treatment can cause huge pollution to the ecological environment, and on the other hand, the treatment of the waste batteries can also cause waste of a large amount of resources.
The waste lithium iron phosphate battery is rich in lithium, iron and lithium resources. The existing recycling enterprises only extract lithium in the waste lithium iron phosphate batteries when the waste lithium iron phosphate batteries are treated, the rest is the ferric phosphate carbon slag, and the ferric phosphate carbon slag has higher content of impurities due to the ferric phosphate carbon slag, and the conventional treatment mode comprises the following steps: stacked at will, but can cause environmental pollution, or sold to cement plants at low cost. The comprehensive utilization rate of the treatment modes is low, and the economic value is not high.
In a word, the existing waste lithium iron phosphate battery generates a large amount of iron phosphate carbon residues after extracting lithium, the iron phosphate carbon residues contain high content of impurities, the impurities cannot be directly recycled as a raw material of the power battery, and the existing method for preparing battery-grade iron phosphate from the iron phosphate carbon residues in the waste lithium iron phosphate battery after extracting lithium is not applicable to production, so that the waste of resources is caused, and the environment is not protected.
Disclosure of Invention
In order to solve the problems, the invention provides a preparation method of battery-grade ferric phosphate, which is applied to ferric phosphate carbon residue after lithium extraction, and comprises the following steps:
taking ferric phosphate carbon slag as a raw material, and removing carbon to obtain slurry liquid;
reducing the slurry to obtain a ferrous solution;
respectively removing heavy metals and aluminum from the ferrous solution to obtain a purifying solution;
and (3) carrying out oxidation aging reaction on the purifying liquid to obtain the battery-grade ferric phosphate.
Preferably, the method for preparing slurry liquid by taking iron phosphate carbon residue as a raw material and removing carbon comprises the following steps:
mixing the iron phosphate carbon slag serving as a raw material with water to prepare mixed slurry;
adding sulfuric acid into the mixed slurry to react to obtain a first mixture; wherein the liquid-solid ratio in the first mixture is (4-6): 1; the reaction temperature is 60-80 ℃; the reaction time is 1 hour to 2 hours;
and carrying out solid-liquid separation on the first mixture to respectively obtain slurry liquid and solid graphite.
Preferably, the molar concentration of the sulfuric acid is 0.2mol/L to 0.4mol/L.
Preferably, the reducing the slurry to obtain a ferrous solution includes:
and adding phosphoric acid and iron powder into the slurry, and carrying out reduction reaction to obtain the ferrous solution.
Preferably, the slurry includes Fe 2 (SO 4 ) 3 ；
Wherein, after the phosphoric acid and the iron powder are added into the slurry, fe in the slurry 2 (SO 4 ) 3 The mole ratio of phosphoric acid to iron powder is (1-1.5): (0.8-1.0): (1-1.2).
Preferably, the ferrous solution is subjected to calcium, magnesium, nickel and cobalt removal and aluminum removal respectively to obtain a purifying solution
Preferably, the aluminum removal resin used in the aluminum removal step is a T-62MP resin.
Preferably, the oxidizing aging reaction is performed on the purifying solution to obtain battery-grade ferric phosphate, which comprises the following steps:
preparing the purified liquid into a stock solution by using phosphoric acid and water;
adding hydrogen peroxide into the stock solution to perform oxidation aging reaction to obtain aged slurry liquid;
performing solid-liquid separation on the aged slurry liquid, and filtering to obtain filtrate and the battery-grade ferric phosphate;
preferably, the filtrate is added back to the ferrous solution of the step of reducing the slurry to obtain a ferrous solution.
Preferably, the preparing the purified liquid into a stock liquid by using phosphoric acid and water comprises:
detecting the iron and phosphorus content of the purifying liquid;
supplementing phosphoric acid according to the detection result until the mole ratio of the phosphorus to the iron in the solution is (1.2-1.3): 1;
adding pure water to enable the mass concentration of iron ions in the solution to reach 58g/L-80g/L, and obtaining the stock solution.
Preferably, the adding hydrogen peroxide into the stock solution for oxidation aging reaction to obtain an aged slurry liquid comprises:
dropwise adding 31% hydrogen peroxide with 1.2-1.5 times of excess into the stock solution at the reaction starting temperature of 50-60 ℃;
and after the dripping is finished, the temperature is increased to 80-90 ℃ to react, and after the reaction is finished, the heat is preserved for 2-6 hours, so that the aged slurry liquid is obtained.
Preferably, in the step of obtaining the battery grade ferric phosphate after filtering by performing solid-liquid separation on the aged slurry liquid, the method further comprises the following steps:
adding pure water into the filtered solid ferric phosphate according to the condition of the liquid-solid ratio (2-3): 1 for washing;
performing solid-liquid sedimentation separation to obtain purified solid ferric phosphate;
and sequentially drying and sintering the purified solid ferric phosphate to obtain the battery-grade ferric phosphate.
Preferably, after the solid-liquid sedimentation separation is performed to obtain the purified solid ferric phosphate, the method further comprises:
and (3) returning the washing water obtained after the solid-liquid separation to the stock solution in the step of preparing the purified solution into the stock solution by using phosphoric acid and water.
The invention provides a preparation method of battery-grade ferric phosphate and a preparation method thereof, which are applied to ferric phosphate carbon residue after lithium extraction and comprise the following steps: taking ferric phosphate carbon slag as a raw material, and removing carbon to obtain slurry liquid; reducing the slurry to obtain a ferrous solution; respectively removing calcium, magnesium, nickel and cobalt and aluminum from the ferrous solution to obtain a purifying solution; and (3) carrying out oxidation aging reaction on the purifying liquid to obtain the battery-grade ferric phosphate.
According to the preparation method provided by the invention, the iron phosphate carbon slag obtained after lithium extraction of the waste lithium iron phosphate battery is subjected to carbon removal to obtain slurry liquid, the slurry liquid is reduced into ferrous solution through reduction reaction, the impurities of calcium, magnesium, nickel and cobalt and aluminum are removed respectively, and the battery grade iron phosphate which can be recycled as the raw material of the power battery is obtained through aging reaction.
Drawings
FIG. 1 is a comparative schematic diagram of the results of elemental analysis and detection of iron phosphate obtained in the examples average and comparative examples;
FIG. 2 is a graph showing the particle size distribution of the iron phosphate of example 1;
FIG. 3 is a graph showing the result of particle size distribution of iron phosphate of example 2;
FIG. 4 is a graph showing the result of particle size distribution of iron phosphate of example 3;
FIG. 5 is a graph showing the particle size distribution of the iron phosphate of example 4;
FIG. 6 is a graph showing the result of the particle size distribution of the iron phosphate of example 5;
FIG. 7 is a morphology chart (SEM) of the recovered iron phosphate of example 1;
FIG. 8 is a morphology chart (SEM) of the recovered iron phosphate of example 2;
FIG. 9 is a morphology chart (SEM) of the recovered iron phosphate of example 3;
FIG. 10 is a morphology chart (SEM) of the recovered iron phosphate of example 4;
FIG. 11 is a morphology (SEM) of the recovered iron phosphate of example 5.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Unless defined otherwise hereinafter, all technical and scientific terms used in the detailed description of the invention are intended to be identical to what is commonly understood by one of ordinary skill in the art. While the following terms are believed to be well understood by those skilled in the art, the following definitions are set forth to better explain the present invention.
As used herein, the terms "comprising," "including," "having," "containing," or "involving" are inclusive or open-ended and do not exclude additional unrecited elements or method steps. The term "consisting of …" is considered to be a preferred embodiment of the term "comprising". If a certain group is defined below to contain at least a certain number of embodiments, this should also be understood to disclose a group that preferably consists of only these embodiments.
The indefinite or definite article "a" or "an" when used in reference to a singular noun includes a plural of that noun.
The term "about" in the present invention means a range of accuracy that one skilled in the art can understand while still guaranteeing the technical effect of the features in question. The term generally means a deviation of + -10%, preferably + -5%, from the indicated value.
Furthermore, the terms first, second, third, (a), (b), (c), and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.
Unless defined otherwise or clearly indicated by context, all technical and scientific terms in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
The technical solution of the present invention is further described in detail below with reference to specific embodiments, but the present invention is not limited thereto, and any modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.
The invention provides a preparation method of battery-grade ferric phosphate, which is applied to ferric phosphate carbon residue after lithium extraction and comprises the following steps:
step S100, taking ferric phosphate carbon slag as a raw material, and removing carbon to obtain slurry liquid;
step S200, reducing the slurry to obtain a ferrous solution;
step S300, respectively removing heavy metals and aluminum from the ferrous solution to obtain a purified solution;
and step S400, performing oxidation aging reaction on the purifying liquid to obtain the battery-grade ferric phosphate.
The method provided by the invention is specially aimed at the waste lithium iron phosphate power battery after extracting lithium, and the obtained lithium iron phosphate carbon residue is obtained after extracting lithium.
As described above, in the iron phosphate carbon slag, a large amount of impurity components including, but not limited to, carbon, calcium, magnesium, nickel, cobalt, aluminum, and the like are contained.
The above carbon removal methods include, but are not limited to, reduction of carbon with a strong acid.
The slurry mainly contains Fe 2 (SO 4 ) 3 Ferrous is obtained through reduction reaction, ferrous ions can be dissolved into a solvent in an oxidation mode, impurities which do not react are removed, the purposes of removing calcium, magnesium, nickel and cobalt and aluminum are achieved, and pure battery-grade ferric phosphate can be obtained after the ferrous is subjected to oxidation aging reaction.
In a word, the invention obtains the iron phosphate carbon slag after extracting lithium from the waste lithium iron phosphate battery, obtains slurry liquid after removing carbon, reduces the slurry liquid into ferrous solution through reduction reaction, respectively removes impurities of calcium, magnesium, nickel and cobalt and aluminum, and obtains the battery-grade iron phosphate which can be recycled as the raw material of the power battery through aging reaction.
Further, in the step S100, iron phosphate carbon slag is used as a raw material, and slurry liquid is obtained after carbon removal, including:
step S110, mixing the iron phosphate carbon slag serving as a raw material with water to prepare mixed slurry;
and mixing water serving as a solvent and the recycled lithium-extracted iron phosphate carbon residues serving as raw materials to obtain slurry liquid.
Step S120, adding sulfuric acid into the mixed slurry to react, and obtaining a first mixture; wherein the liquid-solid ratio in the first mixture is (4-6): 1; the reaction temperature is 60-80 ℃; the reaction time is 1 hour to 2 hours. For example, the liquid to solid ratio may be 4:1, 4.5:1, 5:1, 5.5:1, 6:1, and so forth; for another example, the reaction time may be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, etc.;
the molar concentration of the sulfuric acid is 0.2mol/L to 0.4mol/L. For example, it may be 0.20mol/L, 0.22mol/L, 0.24mol/L, 0.26mol/L, 0.28mol/L, 0.30mol/L, 0.32mol/L, 0.34mol/L, 0.36mol/L, 0.38mol/L, 0.40mol/L, etc.
The main component of the iron phosphate carbon slag can comprise iron phosphate (FePO) 4 ) Graphite and other impurities. Iron phosphate carbon slag is a by-product of the lithium extraction process, with iron phosphate and graphite being valuable raw materials in the battery manufacturing process. The iron phosphate carbon slag is provided withAfter slurry liquid is formed, fePO in the ferric phosphate carbon slag 4 The purpose of adding sulfuric acid into water is to dissolve ferric phosphate in the ferric phosphate carbon residue so as to facilitate subsequent solid-liquid separation. Sulfuric acid is a strong acid that can react with iron phosphate to form iron sulfate and hydrogen phosphate ions.
This reaction can be expressed as: 2FePO 4 +3H 2 SO 4 →Fe 2 (SO 4 ) 3 +2H 3 PO 4 ；
In addition, in the iron phosphate carbon, other impurity components are included, and by adding sulfuric acid, the following reactions may be included in addition to the above reactions:
(1)Ni+H 2 SO 4 →NiSO 4 +H 2 ↑；
(2)Co+H 2 SO 4 →CoSO 4 +H 2 ↑；
and step S130, carrying out solid-liquid separation on the first mixture to obtain slurry liquid and solid graphite respectively.
The solid-liquid separation is carried out, wherein the solid is solid graphite, and the liquid is slurry liquid.
In the step, the carbon simple substance in the mixture, namely graphite, can be separated by extraction and screening, so that the impurity in the mixture can be separated, and the graphite can be used as a negative electrode graphite raw material in the process of preparing the power battery, thereby realizing cyclic utilization and further improving the utilization rate.
Further, in the step S200, the slurry is reduced to obtain a ferrous solution, which includes:
and step S210, adding phosphoric acid and iron powder into the slurry liquid, and carrying out reduction reaction to obtain the ferrous solution.
Further, the slurry liquid comprises Fe 2 (SO 4 ) 3 ；
Wherein, after the phosphoric acid and the iron powder are added into the slurry, fe in the slurry 2 (SO 4 ) 3 The mole ratio of phosphoric acid to iron powder is (1-1.5): (0.8-1.0): (1-1.2). For example, upon deployment, the mixedThe amounts of the substances corresponding to the individual components in the slurry liquid may be selected as follows, depending on the proportions in the whole:
(1)Fe 2 (SO 4 ) 3 may be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, etc.;
(2) Phosphoric acid may be 0.80, 0.85, 0.90, 0.95, 1.0, etc.;
(3) The iron powder may be 1.0, 1.1, 1.2, etc.
Above, fe in the slurry 2 (SO 4 ) 3 After a certain amount of elemental iron and phosphoric acid are added, the following reactions respectively occur:
(1)2H 3 PO 4 (lean) +fe=fe (H) 2 PO 4 ) 2 +H 2 ↑；
(2)Fe+CuSO 4 →FeSO 4 +Cu↓；
(3)Fe+Fe 2 (SO 4 ) 3 →3FeSO 4 ；
3 reactions, fe 2 (SO 4 ) 3 Reacts with the iron simple substance to reduce ferric iron ions in the iron simple substance into ferrous iron ions, namely FeSO 4 The method comprises the steps of carrying out a first treatment on the surface of the And Fe simple substance and H 3 PO 4 Fe (H) containing ferrous iron can be obtained by the reaction 2 PO 4 ) 2 The method comprises the steps of carrying out a first treatment on the surface of the At the same time, cuSO in the slurry liquid 4 FeSO of ferrous iron is also obtained by the reaction of elementary iron 4 And copper simple substance precipitation, and the copper simple substance can be removed through solid-liquid separation. Phosphoric acid and iron simple substance in the solution generate Fe (H) with ferrous ions in the reaction 2 PO 4 ) 2 . Therefore, the components contained in the ferrous solution at this time are: feSO 4 And Fe (H) 2 PO 4 ) 2 Thereby further impurity removal process can be performed.
Further, in the step S300, the ferrous solution is subjected to calcium, magnesium, nickel and cobalt removal and aluminum removal respectively to obtain a purified solution,
step S340, removing aluminum from the ferrous solution filtered to remove heavy metal impurities by using aluminum removal resin to obtain the purified liquid;
further, the regulator is one or more of ammonia water, sodium hydroxide and sodium carbonate;
further, the aluminum removing resin adopted in the aluminum removing step is T-62MP resin.
The T-62MP resin has the characteristic of its macropores, allowing rapid reactant diffusion into its interior. The large surface area of the T-62MP resin enables a large number of catalyst sites to participate in the catalytic reaction. This will help the catalytic reaction run faster and better. The T-62MP resin is suitable for organic chemical reaction with hydrogen ion as catalyst to replace H 2 SO 4 Or mineral acids such as HCl, and removing aluminum ions under acidic conditions.
The purpose of this step S330 is to separate the ferrous solution and the filter residue in the reaction solution for subsequent treatment by sedimentation solid-liquid separation. The purpose of this step, in turn, is to make the ferrous solution purer for subsequent reactions by removing aluminum and removing aluminum ions from the filtrate with resin T-62MP, step S340.
Further, in the step S400, oxidation aging reaction is performed on the purifying solution, so as to obtain battery-level ferric phosphate, which includes:
step S410, preparing the purified liquid into a stock solution by using phosphoric acid and water;
step S420, adding hydrogen peroxide into the stock solution to perform oxidation aging reaction to obtain aged slurry liquid;
step S430, carrying out solid-liquid separation on the aged slurry liquid, and filtering to obtain filtrate and the battery grade ferric phosphate;
further, the filtrate returns to the step S200 and is added to the ferrous solution in the step of reducing the slurry to obtain a ferrous solution.
Further, in the step S410, the preparing the purified liquid into a stock solution by using phosphoric acid and water includes:
step S411, detecting the iron and phosphorus content of the purifying liquid;
step S412, supplementing phosphoric acid according to the detection result until the mole ratio of the phosphorus to the iron in the solution is (1.2-1.3): 1; for example, it may be 1.20:1, 1.22:1, 1.24:1, 1.26:1, 1.28:1, 1.30:1, etc.
And S413, adding pure water to enable the mass concentration of iron ions in the solution to reach 58g/L-80g/L, and obtaining the stock solution. For example, 58g/L, 60g/L, 65g/L, 70g/L, 75g/L, 80g/L, etc.
The raw material solution is a purifying solution, wherein the main component is purified ferrous solution, and the main component is Fe 2+ Ions, and may also contain Fe (H) 2 PO 4 ) 2 And the like.
On the basis of the composition of this ferrous solution, the purpose of analyzing the elemental content and supplementing phosphoric acid is to control the molar ratio of phosphorus to iron and the iron ion mass concentration in the solution to obtain a ferrous stock solution suitable for battery manufacturing.
In particular, the purpose of the phosphoric acid supplementation is to adjust the molar ratio of phosphorus to iron in the solution to a ratio suitable for battery manufacture. In ferrous solutions, the molar ratio of phosphorus to iron may be undesirable, thus requiring analysis of elemental content and replenishment of phosphoric acid.
And pure water is added to control the mass concentration of the iron ions in the solution, so that the quality of the ferrous stock solution is more stable and reliable. Meanwhile, the quality of the finally prepared battery grade ferric phosphate can be ensured to be more stable and reliable.
And for the subsequent aging effect, the concentration of ferric phosphate in the reaction solution can be more stable by supplementing phosphoric acid, so that the aging reaction effect is more consistent and reliable. Meanwhile, the molar ratio of phosphorus to iron and the mass concentration of iron ions in the solution are controlled, so that the aging reaction is purer and more efficient, and the yield and the efficiency of the reaction are improved.
This has the advantage that a ferrous stock solution suitable for battery manufacture can be obtained, thereby ensuring a more stable and reliable quality and performance of the final manufactured battery. Meanwhile, by controlling the mole ratio of phosphorus to iron and the mass concentration of iron ions, the reaction is purer and more efficient, so that the yield and the efficiency of the reaction are improved.
Further, in step S420, the step of adding hydrogen peroxide into the stock solution to perform an oxidation aging reaction to obtain an aged slurry liquid includes:
step S421, dropwise adding 31% hydrogen peroxide with 1.2-1.5 times of excess into the stock solution at the reaction starting temperature of 50-60 ℃; wherein the initial reaction temperature can be 50deg.C, 52deg.C, 55deg.C, 28deg.C, 58deg.C, 60deg.C; the excess of hydrogen peroxide added may be a multiple of 1.2, 1.3, 1.4, 1.5, etc.
Step S422, raising the temperature to 80-90 ℃ after the dripping is finished, and reacting, and preserving the heat for 2-6 hours after the reaction is finished, thus obtaining the aged slurry liquid. Wherein the temperature rise can be 80 ℃, 82 ℃, 84 ℃, 86 ℃, 88 ℃, 90 ℃, etc.; the incubation time may be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, etc.
After the stock solution is prepared, adding hydrogen peroxide to perform an aging reaction, wherein the reaction formula can be as follows:
2FeSO 4 +2H 3 PO 4 +H 2 O 2 →2FePO 4 +2H 2 SO 4 +2H 2 O；
the amount of hydrogen peroxide added is determined according to the actual situation.
The aging reaction is a process of mixing reactants under a certain condition and then standing for a period of time to enable substances in a reaction system to generate a series of chemical changes, thereby obtaining a purer and efficient product. During this process, the reactants are gradually converted to products, with some by-products and intermediates being produced. These byproducts and intermediates may have an effect on the reaction and thus require some handling and control.
The aging reaction usually takes a certain time to complete, and this time depends on the specific conditions of the reaction system, including factors such as the kind and concentration of the reactants, the reaction temperature, the reaction time, and the like. During the reaction, certain control and adjustment are needed to ensure the efficiency and yield of the reaction.
The effect of the aging reaction can be evaluated by detecting the concentration of iron phosphate in the reaction solution. After the reaction is completed, the precipitate may be separated by centrifugation or the like, and washed and dried. The final product is ferric phosphate, which can be used for preparing batteries and other applications.
The aging reaction has the advantages that the reaction is purer and more efficient, so that the yield and the efficiency of the reaction are improved. Meanwhile, the hydrogen peroxide is added to promote the reaction, so that the reaction time is shortened, and the reaction efficiency is improved. The final iron phosphate product has stable quality and is suitable for battery and other applications.
And adding 31% hydrogen peroxide into the stock solution to perform oxidation aging reaction. Obtaining an aged slurry liquid, wherein the excess of hydrogen peroxide is 1.2-1.5 times. (the theoretical addition amount of hydrogen peroxide is according to the addition amount of iron and phosphorus in the stock solution), the initial reaction temperature of the stock solution is controlled to be 50-60 ℃, hydrogen peroxide is dripped, the temperature is raised to 80-90 ℃ after dripping is finished, the reaction is carried out, and after the color of the slurry becomes white and slightly pink, the temperature is kept for 2-6 hours.
Further, in the step S430, the step of performing solid-liquid separation on the aged slurry liquid and filtering to obtain the battery-level ferric phosphate further includes, after filtering:
step S431, adding the filtered solid ferric phosphate into pure water for washing according to the condition of the liquid-solid ratio (2-3): 1; for example, the liquid to solid ratio may be 2.0:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3.0:1.
Step S432, performing solid-liquid sedimentation separation to obtain purified solid ferric phosphate;
and step S433, drying and sintering the purified solid ferric phosphate in sequence to obtain the battery grade ferric phosphate.
The purpose of step S430 is to purify the iron phosphate for subsequent treatment by washing with pure water. And the purified iron phosphate is dried and sintered to prepare battery grade iron phosphate for battery manufacturing.
In summary, the purpose of the above-described preparation process is to convert the lithiated iron phosphate carbon residue into battery grade iron phosphate, and through a series of reactions and treatments, make the iron phosphate purer and suitable for use in battery manufacturing. The advantage of this process is that the iron phosphate can be efficiently converted to battery grade iron phosphate and, through a series of reactions and treatments, the iron phosphate is made purer and suitable for use in battery manufacturing.
Further, in the step S432, after solid-liquid sedimentation separation is performed to obtain purified solid ferric phosphate, the method further includes:
and step S434, the washing water obtained after the solid-liquid separation is added back to the step S410, and the purified liquid is prepared into the stock solution in the stock solution step by using phosphoric acid and water.
The washing water, i.e., the washing water obtained by solid-liquid separation, may be returned to the ferrous iron stock solution for recycling, or may be returned to step S410, added to the stock solution, recycled, and subjected to the extraction process again.
The invention is further illustrated by the following specific examples, but it should be understood that these examples are for the purpose of illustration only and are not to be construed as limiting the invention in any way.
The preparation method of the battery grade ferric phosphate adopted in the example comprises the following steps:
step 1, taking ferric phosphate carbon slag as a raw material, and removing carbon to obtain slurry liquid;
(1) Mixing the iron phosphate carbon slag serving as a raw material with water to prepare mixed slurry;
(2) Adding sulfuric acid into the mixed slurry to react to obtain a first mixture; wherein the liquid-solid ratio in the first mixture is (4-6): 1; the reaction temperature is 60-80 ℃; the reaction time is 1 hour to 2 hours; wherein the molar concentration of sulfuric acid is 0.2mol/L-0.4mol/L.
(3) And carrying out solid-liquid separation on the first mixture to respectively obtain slurry liquid and solid graphite.
Step 2, adding phosphoric acid and reduced iron powder into the slurry liquid, and carrying out a reduction reaction to obtain a ferrous solution; wherein Fe is 2 (SO 4 ) 3 The mole ratio of phosphoric acid to reduced iron powder is (1-1.5)0.8-1.0):(1-1.2)。
Step 3, respectively removing calcium, magnesium, nickel and cobalt and aluminum from the ferrous solution to obtain a purified solution;
(1) Removing aluminum from the ferrous solution with calcium, magnesium, nickel and cobalt impurities filtered by using aluminum removing resin (T-62 MP) to obtain the purifying liquid;
and step 4, performing oxidation aging reaction on the purifying liquid to obtain the battery-grade ferric phosphate.
(1) Preparing the purified liquid into a stock solution by using phosphoric acid and water;
detecting the iron and phosphorus content of the purifying liquid;
supplementing phosphoric acid according to the detection result until the mole ratio of the phosphorus to the iron in the solution is (1.2-1.3): 1;
adding pure water to enable the mass concentration of iron ions in the solution to reach 58g/L-80g/L, and obtaining the stock solution.
(2) Adding hydrogen peroxide into the stock solution to perform oxidation aging reaction to obtain aged slurry liquid;
dropwise adding 31% hydrogen peroxide with 1.2-1.5 times of excess into the stock solution at the reaction starting temperature of 50-60 ℃;
and after the dripping is finished, the temperature is increased to 80-90 ℃ for reaction, and after the color of the slurry is changed into white and slightly pink, the temperature is kept for 2-6 hours after the reaction is finished, so that the aged slurry liquid is obtained.
(3) Carrying out solid-liquid separation and filtration on the aged slurry liquid;
(4) Adding pure water into the filtered solid ferric phosphate according to the condition of the liquid-solid ratio (2-3): 1 for washing (3 times); the washing water obtained after the solid-liquid separation is returned to the stock solution in the step of preparing the purified solution into the stock solution by utilizing phosphoric acid and water;
(5) Performing solid-liquid sedimentation separation to obtain purified solid ferric phosphate;
(6) And sequentially drying and sintering the purified solid ferric phosphate to obtain the battery-grade ferric phosphate.
Preparation parameters in Table 1, examples 1-5 and comparative examples 1-2
Example 1
Using the preparation method of the above example, battery grade iron phosphate was prepared based on the parameters in table 1.
Example 2
Using the preparation method of the above example, battery grade iron phosphate was prepared based on the parameters in table 1.
Example 3
Using the preparation method of the above example, battery grade iron phosphate was prepared based on the parameters in table 1.
Example 4
Using the preparation method of the above example, battery grade iron phosphate was prepared based on the parameters in table 1.
Example 5
Using the preparation method of the above example, battery grade iron phosphate was prepared based on the parameters in table 1.
Comparative example 1 (aluminum removal with NaF)
The comparative example differs from the method used in example 1 only in that the "aluminum removal resin (T-62 MP), which is replaced with NaF, of step 3- (3) was used to remove aluminum from the ferrous solution from which calcium, magnesium, nickel and cobalt impurities were removed.
The specific aluminum removal step comprises the following steps: dropwise adding NaF (adding amount is 30% of excess amount according to the reaction metering ratio of fluoride ions and aluminum ions) into the ferrous solution with calcium, magnesium, nickel and cobalt impurities filtered out, heating at 60 ℃ for 40-60min, and filtering and separating to obtain the purified solution after the reaction is completed.
Other steps and experimental parameters were the same as in example 1.
Comparative example 2 (aluminum removal by D113)
The comparative example differs from the method used in example 1 only in that the "aluminum removal resin (T-62 MP), which is replaced with D113," of step 3- (3) was used to remove aluminum from the ferrous solution from which heavy metal impurities were removed, to obtain the purified solution.
The specific aluminum removal step comprises the following steps: removing aluminum ions from the ferrous solution with heavy metal impurities removed by using D113 acrylic acid weak acid type macroporous cation exchange resin to obtain ferrous sulfate solution with aluminum ions removed; the ferrous solution is added into the resin chromatographic column according to a certain flow, and the purifying liquid is obtained after the aluminum ions are removed and filtered and separated.
Other steps and experimental parameters were the same as in example 1.
Comparative example 3 (different acid addition reaction temperature)
This comparative example 3 differs from the method employed in example 1 only in that the "temperature range of the acid addition reaction" of step 1- (2) is 60 ℃ -80 ℃, "in which the reaction temperature is adjusted to 50 ℃.
The specific aluminum removal step comprises the following steps: after adding sulfuric acid to the mixed slurry for reaction, a first mixture is obtained, the mixture is placed in a 1000ml beaker, and the beaker is placed in a constant-temperature water bath kettle, and the temperature is set to be 50 ℃.
Other steps and experimental parameters were the same as in example 1.
Experimental results:
1. elemental analysis:
table 2, table of the results of analysis and detection of iron phosphate element obtained in examples and comparative examples
Remarks: in table 2, national standard is international standard, real 1 is short for example 1, real 2 is short for example 2, real 3 is short for example 3, real 4 is short for example 4, real 5 is short for example 5, AVG is corresponding average value of each item of data of examples 1-5; the abbreviation of comparative example 1 is given for pair 1, comparative example 2 is given for pair 2, and comparative example 3 is given for pair 3.
As can be seen from the data in the elemental analysis results table in table 2 above, the elemental content of each impurity in the iron phosphate recovered in the batteries of comparative examples 1 to 3 was numerically lower than the elemental content of the corresponding impurity in the iron phosphate recovered in examples 1 to 5;
referring to fig. 6, the test data of each of examples 1 to 5 were averaged, and the elemental contents of each kind of impurity showed a significant difference compared to comparative examples 1 to 3.
The ferric phosphate product recovered by the method provided by the invention has obvious good quality, and can be completely used for preparing lithium iron phosphate batteries.
2. Particle size analysis:
refer to the particle size analysis charts of fig. 2-6.
As can be seen from the particle size analysis charts of fig. 2 to 6, the particle size distribution of the iron phosphate prepared by the method provided by the invention belongs to a normal distribution.
3. Product SEM analysis:
as can be seen from fig. 7 to 11, the iron phosphate recovered in the example of the present invention has uniform size, regular morphology, no agglomeration and aggregation, and is suitable for use as lithium iron phosphate batteries.
In a word, the preparation method provided by the invention obtains the iron phosphate carbon slag after extracting lithium from the waste lithium iron phosphate battery, obtains slurry liquid after decarbonizing, reduces the slurry liquid into ferrous solution through reduction reaction, respectively removes impurities of calcium, magnesium, nickel, cobalt and aluminum, and obtains the battery grade iron phosphate which can be recycled as a raw material of the power battery through aging reaction. The preparation method is simple, has high utilization rate, is more suitable for preparing a large amount of battery-grade ferric phosphate in the production process, solves the problem that the iron phosphate carbon residue obtained after the lithium extraction of the traditional waste lithium iron phosphate battery cannot be recovered, not only avoids the waste of the ferric phosphate resource, but also achieves the purpose of environmental protection, avoids environmental pollution, and the recovered ferric phosphate is a battery-grade raw material and can be put into the production process of the power battery again.
While the preferred embodiments and examples of the present invention have been described, it should be noted that those skilled in the art may make various modifications and improvements without departing from the inventive concept, including but not limited to, adjustments of proportions, procedures, and amounts, which fall within the scope of the present invention. While the preferred embodiments and examples of the present invention have been described, it should be noted that those skilled in the art may make various modifications and improvements without departing from the inventive concept, including but not limited to, adjustments of proportions, procedures, and amounts, which fall within the scope of the present invention.
Claims (10)
1. The preparation method of the battery-grade ferric phosphate is applied to the lithium-extracted ferric phosphate carbon residue and is characterized by comprising the following steps:
taking ferric phosphate carbon slag as a raw material, and removing carbon to obtain slurry liquid;
reducing the slurry to obtain a ferrous solution;
respectively removing heavy metals and aluminum from the ferrous solution to obtain a purifying solution;
and (3) carrying out oxidation aging reaction on the purifying liquid to obtain the battery-grade ferric phosphate.
2. The method for preparing battery grade ferric phosphate according to claim 1, wherein the method for preparing slurry liquid by taking ferric phosphate carbon slag as raw material and removing carbon comprises the following steps:
mixing the iron phosphate carbon slag serving as a raw material with water to prepare mixed slurry;
adding sulfuric acid into the mixed slurry to react to obtain a first mixture; wherein the liquid-solid ratio in the first mixture is (4-6): 1; the reaction temperature is 60-80 ℃; the reaction time is 1 hour to 2 hours;
carrying out solid-liquid separation on the first mixture to respectively obtain slurry liquid and solid graphite;
preferably, the molar concentration of the sulfuric acid is 0.2mol/L to 0.4mol/L.
3. The method of claim 1, wherein the reducing the slurry to obtain a ferrous solution comprises:
and adding phosphoric acid and iron powder into the slurry, and carrying out reduction reaction to obtain the ferrous solution.
4. The method for producing battery grade iron phosphate according to claim 3,
the slurry liquid comprises Fe 2 (SO 4 ) 3 ；
Wherein, after the phosphoric acid and the iron powder are added into the slurry, fe in the slurry 2 (SO 4 ) 3 The mole ratio of phosphoric acid to iron powder is (1-1.5): (0.8-1.0): (1-1.2).
5. The method for preparing battery-grade ferric phosphate according to claim 1, wherein the ferrous solution is subjected to calcium, magnesium, nickel and cobalt removal and aluminum removal respectively to obtain a purified solution,
preferably, the aluminum removal resin used in the aluminum removal step is a T-62MP resin.
6. The method for preparing battery-grade ferric phosphate according to claim 1, wherein the oxidizing aging reaction is performed on the purified solution to obtain the battery-grade ferric phosphate, comprising:
preparing the purified liquid into a stock solution by using phosphoric acid and water;
adding hydrogen peroxide into the stock solution to perform oxidation aging reaction to obtain aged slurry liquid;
performing solid-liquid separation on the aged slurry liquid, and filtering to obtain filtrate and the battery-grade ferric phosphate;
preferably, the filtrate is added back to the ferrous solution of the step of reducing the slurry to obtain a ferrous solution.
7. The method of producing battery grade ferric phosphate according to claim 6, wherein said preparing the purified solution into a stock solution using phosphoric acid and water comprises:
detecting the iron and phosphorus content of the purifying liquid;
supplementing phosphoric acid according to the detection result until the mole ratio of the phosphorus to the iron in the solution is (1.2-1.3): 1;
adding pure water to enable the mass concentration of iron ions in the solution to reach 58g/L-80g/L, and obtaining the stock solution.
8. The method for preparing battery-grade ferric phosphate according to claim 6, wherein the adding hydrogen peroxide into the stock solution for oxidation aging reaction to obtain an aging slurry liquid comprises:
dropwise adding 31% hydrogen peroxide with 1.2-1.5 times of excess into the stock solution at the reaction starting temperature of 50-60 ℃;
and after the dripping is finished, the temperature is increased to 80-90 ℃ to react, and after the reaction is finished, the heat is preserved for 2-6 hours, so that the aged slurry liquid is obtained.
9. The method for preparing battery grade ferric phosphate according to claim 6, wherein in the step of obtaining the battery grade ferric phosphate after filtering by solid-liquid separation of the aged slurry liquid, the method further comprises, after filtering:
adding pure water into the filtered solid ferric phosphate according to the condition of the liquid-solid ratio (2-3): 1 for washing;
performing solid-liquid sedimentation separation to obtain purified solid ferric phosphate;
and sequentially drying and sintering the purified solid ferric phosphate to obtain the battery-grade ferric phosphate.
10. The method for preparing battery-grade ferric phosphate according to claim 9, wherein after the solid-liquid sedimentation separation is performed to obtain purified solid ferric phosphate, the method further comprises:
and (3) returning the washing water obtained after the solid-liquid separation to the stock solution in the step of preparing the purified solution into the stock solution by using phosphoric acid and water.
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