Calcium-aluminum-iron ternary impurity removal material, preparation method thereof and impurity removal method of lepidolite leachate

Abstract

According to the calcium-aluminum-iron ternary impurity removal material and the preparation method thereof, the impurity removal method of the lepidolite leaching solution adopts a simple and convenient coprecipitation method, and uniform precipitation of calcium hydroxide, aluminum hydroxide and iron hydroxide is achieved. And then, converting the precipitate into a calcium-aluminum-iron ternary metal oxide with a stable structure through a high-temperature calcination process. The calcination process promotes the interaction and compounding of oxides, and significantly enhances the crystallinity, chemical stability and adsorptive property of the calcium-aluminum-iron ternary impurity removal material. The adsorption capacity of calcium oxide and aluminum oxide to fluorine ions and calcium ions and the adsorption capacity of iron oxide and aluminum oxide to thallium ions are integrated. Through the synergistic effect of the three oxides and the collaborative optimization of chemical adsorption and physical adsorption, the excellent adsorption performance can be shown, and thallium, fluorine and calcium ions in the solution can be removed at the same time. Compared with an independent treatment method, the calcium-aluminum-iron ternary impurity removal material prepared by the method can simplify thallium removal, fluorine removal and calcium removal steps, and the cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of lithium extraction from lepidolite, and in particular to a calcium-aluminum-iron ternary impurity removal material and a preparation method thereof, and an impurity removal method for a lepidolite leachate. Background Art

[0002] In the lithium battery industry, lithium carbonate is a key raw material, and its preparation process involves a variety of methods, including but not limited to limestone roasting, sulfuric acid method and sulfate method. Regardless of the process adopted, a lithium-containing leachate is first prepared, and then the leachate is purified and impurities removed. Lepidolite ore contains associated elements such as thallium (Tl), fluorine (F) and calcium (Ca), which will dissolve in the leachate during the leaching process. Among them, thallium is a highly toxic trace element, and its acute toxicity to the human body is significantly higher than that of elements such as mercury, cadmium, lead and copper. On the other hand, although fluorine is an essential trace element for the human body and is essential for growth and development, excessive intake can lead to poisoning. Therefore, these two types of wastewater must be treated before they can be discharged. According to environmental protection regulations, the emission limit of thallium should comply with the Jiangxi Province "Industrial Wastewater Thallium Pollutant Emission Standard" (DB 36 / 1149-2019), that is, no more than 5μg / L; the emission concentration of fluoride should follow the "Battery Industry Pollutant Emission Standard" (GB 30484-2013), that is, no more than 10mg / L. As for calcium, its content will affect the purity of lithium carbonate products, so its content needs to be reduced to meet the battery grade lithium carbonate standard (YS / T 582-2023), usually not more than 50mg / L.

[0003] In the related art, elements such as thallium, fluorine, and calcium need to be removed separately, such as by ion exchange, adsorption, and precipitation methods, but the processing steps are cumbersome. Summary of the invention

[0004] The present application provides a calcium-aluminum-iron ternary impurity removal material and a preparation method thereof, as well as an impurity removal method for a lithium mica leachate, which are conducive to simplifying the processing steps.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a calcium-aluminum-iron ternary impurity-removing material, the method comprising.

[0006] Dissolving a soluble calcium salt, a soluble aluminum salt, and a soluble iron salt in water according to a preset ratio to obtain a first solution;

[0007] dissolving sodium hydroxide in deionized water to obtain a second solution;

[0008] Using a peristaltic pump, the second solution is added dropwise into the first solution to form a mixed solution, until the pH of the mixed solution reaches 7 to 14, and then heated and stirred to separate and obtain a hydroxide precipitate;

[0009] washing and drying the hydroxide precipitate to obtain a powder;

[0010] The powder material is calcined to obtain the calcium-aluminum-iron ternary impurity-removing material.

[0011] According to the first aspect, in a possible implementation, the soluble calcium salt, the soluble aluminum salt, and the soluble iron salt are dissolved in water at a molar ratio of calcium ion, aluminum ion, and iron ion of (1-5): (1-3): (1-5).

[0012] According to the first aspect, in a possible implementation, the soluble calcium salt is one or more of calcium nitrate, calcium chloride, and calcium sulfate; and / or,

[0013] The soluble aluminum salt is one or more of aluminum chloride, aluminum sulfate, and aluminum nitrate; and / or,

[0014] The soluble iron salt is one or more of ferric chloride, ferric sulfate and ferric nitrate;

[0015] According to the first aspect, in a possible implementation, the molar concentration of sodium hydroxide in the second solution is 1 to 5 mol / L.

[0016] According to the first aspect, in a possible implementation, in the step of using a peristaltic pump to add the second solution dropwise into the first solution to form a mixed solution until the pH of the mixed solution reaches 7 to 14, and heating and stirring to separate and obtain a hydroxide precipitate,

[0017] The heating temperature is 60°C to 90°C, and the reaction time is 4h to 12h.

[0018] According to the first aspect, in a possible implementation, in the step of calcining the powder material to obtain the calcium aluminum iron ternary impurity-removing material, the calcination temperature is 300° C. to 600° C., and the calcination time is 2 h to 4 h.

[0019] In a second aspect, an embodiment of the present application further provides a calcium-aluminum-iron ternary impurity-removing material, wherein the calcium-aluminum-iron ternary impurity-removing material is prepared by the preparation method of the calcium-aluminum-iron ternary impurity-removing material described in the first aspect.

[0020] In a third aspect, the present application also provides a method for removing impurities from a lithium mica leachate, the method comprising:

[0021] The calcium aluminum iron ternary impurity removal material described in the second aspect is added into the lepidolite leachate to remove impurities;

[0022] Calculated by the volume of the leaching solution, the dosage of the calcium-aluminum-iron ternary impurity removal material is 1g / L to 30g / L.

[0023] The present application provides a calcium aluminum iron ternary impurity removal material and a preparation method thereof, and an impurity removal method for a lithium mica leachate. The present application adopts a simple coprecipitation method to achieve uniform precipitation of calcium, aluminum, and iron hydroxides. Subsequently, the precipitate is converted into a calcium aluminum iron ternary metal oxide with stable structure through a high-temperature calcination process. The calcination process promotes the interaction and compounding between the oxides, significantly enhancing the crystallinity, chemical stability, and adsorption properties of the calcium aluminum iron ternary impurity removal material.

[0024] And. The calcium-aluminum-iron ternary impurity removal material prepared in this application combines the adsorption capacity of calcium oxide and aluminum oxide for fluoride ions and calcium ions, and the adsorption capacity of iron oxide and aluminum oxide for thallium ions. Through the synergistic effect of the three oxides and the coordinated optimization of chemical adsorption and physical adsorption, it can show excellent adsorption performance and remove thallium, fluorine and calcium ions in the solution at the same time. Compared with a separate treatment method, the calcium-aluminum-iron ternary impurity removal material prepared in this application can simplify the steps of thallium removal, fluorine removal and calcium removal, and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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.

[0026] Figure 1 The present invention is a schematic flow chart of a method for preparing a calcium aluminum iron ternary impurity removal material in an embodiment. DETAILED DESCRIPTION

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0031] In the first aspect, the present application provides a method for preparing a calcium aluminum iron ternary impurity removal material, such as Figure 1 As shown, in some embodiments, the method for preparing the material for removing impurities from the lepidolite leachate comprises the following steps:

[0032] Step S10, dissolving a soluble calcium salt, a soluble aluminum salt, and a soluble iron salt in water according to a preset ratio to obtain a first solution;

[0033] The soluble calcium salt, the soluble aluminum salt and the soluble iron salt are dissolved in water in a molar ratio of calcium ion, aluminum ion and iron ion of (1-5): (1-3): (1-5).

[0034] The soluble calcium salt is one or more of calcium nitrate, calcium chloride, and calcium sulfate; the soluble aluminum salt is one or more of aluminum chloride, aluminum sulfate, and aluminum nitrate; and the soluble iron salt is one or more of iron chloride, iron sulfate, and iron nitrate.

[0035] When preparing the first solution, it is important to ensure that all salts are completely dissolved and that the first solution is homogeneous. In addition, if a combination of salts is used, any chemical reactions that may occur between them need to be considered to ensure that the resulting solution is stable and in the desired molar ratio.

[0036] Step S20, dissolving sodium hydroxide in deionized water to obtain a second solution;

[0037] Sodium hydroxide (NaOH) is used as an alkali source to subsequently react with ions in the first solution to form hydroxide precipitates. Deionized water is used to dissolve the sodium hydroxide to ensure that the impurity content in the solution is low, thereby improving the purity of the final product.

[0038] Add an appropriate amount of sodium hydroxide solid into deionized water.

[0039] Use appropriate stirring equipment (such as a magnetic stirrer, mechanical stirrer, etc.) to stir to ensure that the sodium hydroxide is completely dissolved. During the dissolution process, the temperature of the solution can be monitored and cooled if necessary to prevent safety issues caused by overheating of the solution or decomposition of the sodium hydroxide.

[0040] According to the experimental or production requirements, adjust the concentration of sodium hydroxide in deionized water to a molar concentration of 1 to 5 mol / L. The concentration should be determined according to the needs of the subsequent reaction to ensure that the reaction can proceed smoothly and achieve the desired effect.

[0041] During the dissolution and concentration adjustment process, it is necessary to ensure that the solution is homogeneous, that is, the sodium hydroxide molecules are evenly distributed in the deionized water. This can be achieved through continuous stirring and appropriate solution circulation.

[0042] Step S30, using a peristaltic pump to add the second solution dropwise into the first solution to form a mixed solution, until the pH of the mixed solution reaches 7 to 14, heating and stirring, and separating to obtain a hydroxide precipitate;

[0043] The second solution (sodium hydroxide solution) is added dropwise to the first solution using a peristaltic pump. The peristaltic pump can accurately control the speed of solution addition to ensure a smooth mixing process. Dropwise addition helps avoid side reactions caused by excessive local concentrations, and is also conducive to observing and controlling changes in the pH value of the mixed solution.

[0044] During the addition of the second solution, the pH value of the mixed solution is continuously monitored. When the pH value of the mixed solution reaches 7 to 14, the addition of the second solution is stopped. This pH range is conducive to the formation of a stable hydroxide precipitate.

[0045] Heat the mixture to 60℃~90℃ and keep stirring. Heating helps to accelerate the reaction process and increase the rate of precipitation; stirring can ensure that the reactants are evenly distributed in the solution, improving the uniformity and efficiency of the reaction. The reaction time is controlled between 4h and 12h to ensure that the reaction is fully carried out and sufficient hydroxide precipitation is generated.

[0046] After the reaction is completed, the hydroxide precipitate is separated from the mixed solution by an appropriate separation method (such as filtration, centrifugation, etc.). The separation process requires careful operation to avoid loss or contamination of the precipitate.

[0047] Step S40, washing and drying the hydroxide precipitate to obtain a powder material;

[0048] The purpose of washing is to remove impurities attached to the surface of the hydroxide precipitate, such as unreacted ions, solvent molecules or other contaminants.

[0049] Deionized water or a suitable solvent, such as ethanol, is usually used for washing. The washing liquid needs to be replaced several times during the washing process, for example, 3 times or more, to ensure that impurities on the surface of the precipitate are fully removed. During washing, the precipitate can be separated from the washing liquid by filtering, centrifuging or decantation.

[0050] The purpose of drying is to remove water or other volatile components in the hydroxide precipitate to obtain a powder material.

[0051] Drying can be done at room temperature or by heating. Heating can accelerate the evaporation of water, but it is necessary to control the temperature to avoid decomposition or structural changes of the precipitate. Common drying equipment includes ovens, vacuum drying ovens, etc. During the drying process, the precipitate needs to be turned or stirred regularly to ensure that it is evenly heated and fully dried.

[0052] For example, the washed hydroxide precipitate can be placed in a suitable drying device, such as an oven or a vacuum drying oven. The drying temperature is set to 70-90°C, which helps to accelerate the evaporation of water while avoiding decomposition or structural changes of the precipitate. The drying time needs to last for 12 hours or longer to ensure that the water in the precipitate is fully removed to obtain a dry powder.

[0053] After drying, the solid material is removed from the drying equipment and subjected to appropriate grinding or pulverization to obtain a powder of uniform particle size. The powder can be graded by sieving or other methods to meet specific application requirements.

[0054] Step S50, calcining the powder material to obtain the calcium aluminum iron ternary impurity removal material.

[0055] The calcination process not only promotes the interaction and recombination between oxides, but also significantly enhances the crystallinity, chemical stability and adsorption properties of the material.

[0056] The calcination temperature is set between 300° C. and 600° C. This temperature range is selected to ensure that the oxides in the powder material can fully interact and recombine, while avoiding excessively high temperatures that may cause material decomposition or other adverse phase changes.

[0057] The calcination time should be controlled between 2 hours and 4 hours. Appropriate calcination time helps to form and stabilize the internal crystal structure of the material, thereby optimizing its performance. The calcination process can refer to the following process:

[0058] Pretreatment: Before calcination, ensure that the powder material is evenly dispersed in the calcination container to avoid local overheating or agglomeration.

[0059] Heating stage: The calcining furnace is heated to the set calcining temperature at an appropriate rate. During the heating process, the temperature changes in the furnace must be closely monitored to ensure the accuracy of temperature control.

[0060] Insulation stage: When the set calcination temperature is reached, the temperature is maintained for a period of time (2 to 4 hours) to promote the interaction and compounding between the oxides. During this stage, the powder material will gradually be transformed into a calcium aluminum iron ternary impurity removal material with higher crystallinity, chemical stability and adsorption performance.

[0061] Cooling stage: After calcination, the furnace temperature needs to be lowered to room temperature at an appropriate rate. During the cooling process, cracks or structural changes caused by rapid cooling of the material should be avoided.

[0062] The present application adopts a simple coprecipitation method to achieve uniform precipitation of calcium, aluminum and iron hydroxides. Subsequently, the precipitate is converted into a calcium-aluminum-iron ternary metal oxide with stable structure through a high-temperature calcination process. The calcination process promotes the interaction and compounding between the oxides, significantly enhancing the crystallinity, chemical stability and adsorption performance of the calcium-aluminum-iron ternary impurity removal material.

[0063] And. The calcium-aluminum-iron ternary impurity removal material prepared in this application combines the adsorption capacity of calcium oxide and aluminum oxide for fluoride ions and calcium ions, and the adsorption capacity of iron oxide and aluminum oxide for thallium ions. Through the synergistic effect of the three oxides and the coordinated optimization of chemical adsorption and physical adsorption, it can show excellent adsorption performance and remove thallium, fluorine and calcium ions in the solution at the same time. Compared with a separate treatment method, the calcium-aluminum-iron ternary impurity removal material prepared in this application can simplify the steps of thallium removal, fluorine removal and calcium removal, and reduce costs.

[0064] In a second aspect, the present application further provides a calcium-aluminum-iron ternary impurity-removing material, which is prepared by the preparation method of the calcium-aluminum-iron ternary impurity-removing material described in the first aspect.

[0065] In a third aspect, the present application also provides a method for removing impurities from a lithium mica leachate, the method comprising:

[0066] The calcium aluminum iron ternary impurity removal material described in the second aspect is added into the lepidolite leachate to remove impurities;

[0067] Calculated by the volume of the leaching solution, the dosage of the calcium-aluminum-iron ternary impurity removal material is 1g / L to 30g / L.

[0068] After adding the impurity removal material, the lithium mica leachate is stirred to promote the full contact and adsorption of the impurity removal material with the impurities in the leachate. The stirring time is recommended to be 4 to 24 hours, and the specific time can be adjusted according to the actual situation to ensure the full progress of the adsorption process.

[0069] After the stirring and adsorption is completed, the impurity-removing material is separated from the lepidolite leachate by filtering, centrifuging or other appropriate solid-liquid separation methods to obtain a purified leachate.

[0070] As required, the purified leachate is further processed, such as pH adjustment, concentration, crystallization, etc., to extract or purify the target product.

[0071] By utilizing the excellent adsorption performance of calcium aluminum iron ternary impurity removal material, various impurities in the lithium mica leachate can be effectively removed and the purity of the leachate can be improved.

[0072] The lepidolite leachate is treated by using the miscellaneous materials of different embodiments. The lepidolite concentrate powder in this embodiment comes from Yichun City, Jiangxi Province, and the components and contents of the lepidolite leachate are as follows:

[0073] Components Lithium / (g / L) Calcium / (mg / L) Fluoride / (mg / L) Thallium / (mg / L) content 6.8296 478.392 80.46 0.573

[0074] In the first embodiment:

[0075] A method for preparing a calcium-aluminum-iron ternary impurity-removing material comprises the following steps:

[0076] S1. Mix and dissolve a soluble calcium salt, a soluble aluminum salt, and a soluble iron salt in water to prepare a solution 1; the molar ratio of the calcium ion, the aluminum ion, and the iron ion is 2:1:2; the soluble calcium salt is one or more of calcium nitrate, calcium chloride, and calcium sulfate; the soluble aluminum salt is one or more of aluminum chloride, aluminum sulfate, and aluminum nitrate; the soluble iron salt is one or more of ferric chloride, ferric sulfate, and ferric nitrate;

[0077] S2, dissolving sodium hydroxide in deionized water to prepare solution 2; adding solution 2 dropwise into solution 1 using a peristaltic pump until the pH of the mixed solution is 10, heating and stirring the reaction for 4 hours to obtain a hydroxide precipitate;

[0078] S3, washing the obtained hydroxide precipitate with deionized water and anhydrous ethanol for more than 3 times, and then drying at 70-90° C. for more than 12 hours to obtain a powder;

[0079] S4. calcining the obtained powder at a temperature of 400° C. for 3 h to obtain calcium-aluminum-iron ternary metal oxide, i.e., calcium-aluminum-iron ternary impurity-removing material.

[0080] Calculated by the volume of the leachate, the dosage of the calcium-aluminum-iron ternary impurity removal material is 20 g / L, the stirring and adsorption time is 6 h, and the supernatant is taken for detection after filtration.

[0081] In the second embodiment:

[0082] The second embodiment is different from the first embodiment in that the molar ratio of calcium ions, aluminum ions and iron ions is 3:1:3, and other conditions remain unchanged.

[0083] In the third embodiment:

[0084] The third embodiment is different from the first embodiment in that no soluble calcium salt is added in step S1, and other conditions remain unchanged.

[0085] In the fourth embodiment:

[0086] The fourth embodiment is different from the first embodiment in that no soluble iron salt is added in step S1, and other conditions remain unchanged.

[0087] In the fifth embodiment:

[0088] The fifth embodiment is different from the first embodiment in that no soluble aluminum salt is added in step S1, and other conditions remain unchanged.

[0089] Table 1: Treatment effects of different embodiments on leachate:

[0090]

[0091]

[0092] As can be seen from Table 1 above, the lithium mica leachate impurity removal material prepared by the present invention shows significant adsorption efficiency for thallium and calcium ions in the lithium mica leachate. However, when the metal ratio changes, the adsorption performance shows a slight downward trend. Iron and aluminum oxides show good adsorption capacity for thallium ions. At the same time, calcium and aluminum oxides can not only effectively remove fluoride ions, but also show excellent adsorption effects on calcium ions. Calcium aluminum iron ternary metal oxides, due to their synergistic effect, show the best comprehensive adsorption performance, and the lithium loss rate is the lowest during the adsorption process.

[0093] 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 a calcium-aluminum-iron ternary impurity-removing material, characterized in that: The method comprises: Dissolving a soluble calcium salt, a soluble aluminum salt, and a soluble iron salt in water according to a preset ratio to obtain a first solution; dissolving sodium hydroxide in deionized water to obtain a second solution; Using a peristaltic pump, the second solution is added dropwise into the first solution to form a mixed solution, until the pH of the mixed solution reaches 7 to 14, and then heated and stirred to separate and obtain a hydroxide precipitate; washing and drying the hydroxide precipitate to obtain a powder; The powder material is calcined to obtain the calcium-aluminum-iron ternary impurity-removing material.

2. The method for preparing the calcium-aluminum-iron ternary impurity-removing material according to claim 1, characterized in that: The soluble calcium salt, the soluble aluminum salt and the soluble iron salt are dissolved in water in a molar ratio of calcium ion, aluminum ion and iron ion of (1-5): (1-3): (1-5).

3. The method for preparing the calcium-aluminum-iron ternary impurity-removing material according to claim 2, characterized in that: The soluble calcium salt is one or more of calcium nitrate, calcium chloride and calcium sulfate; and / or, The soluble aluminum salt is one or more of aluminum chloride, aluminum sulfate, and aluminum nitrate; and / or, The soluble iron salt is one or more of ferric chloride, ferric sulfate and ferric nitrate.

4. The method for preparing the calcium-aluminum-iron ternary impurity-removing material according to claim 1, characterized in that: The molar concentration of sodium hydroxide in the second solution is 1-5 mol / L.

5. The method for preparing the calcium-aluminum-iron ternary impurity-removing material according to claim 1, characterized in that: In the step of using a peristaltic pump to add the second solution dropwise into the first solution to form a mixed solution until the pH of the mixed solution reaches 7 to 14, heating and stirring the mixed solution and separating to obtain a hydroxide precipitate, The heating temperature is 60°C to 90°C, and the reaction time is 4h to 12h.

6. The method for preparing the calcium-aluminum-iron ternary impurity-removing material according to claim 2, characterized in that: In the step of calcining the powder material to obtain the calcium-aluminum-iron ternary impurity-removing material, the calcination temperature is 300° C. to 600° C. and the calcination time is 2 h to 4 h.

7. A calcium aluminum iron ternary impurity removal material, characterized in that: The calcium-aluminum-iron ternary impurity-removing material is prepared by the preparation method of the calcium-aluminum-iron ternary impurity-removing material according to any one of claims 1 to 6.

8. A method for removing impurities from a lepidolite leachate, characterized in that: The method comprises: The calcium aluminum iron ternary impurity removal material according to claim 7 is added to the lepidolite leachate to remove impurities; Calculated by the volume of the leaching solution, the dosage of the calcium-aluminum-iron ternary impurity removal material is 1g / L to 30g / L.

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