Method for removing silicon and aluminum from sulfuric acid leaching solution of rare earth enrichment

Abstract

The invention provides a method for removing silicon and aluminum from a rare earth enriched product sulfuric acid leaching solution, which comprises the following steps: mixing the rare earth enriched product into slurry, mixing with sulfuric acid for leaching, and carrying out solid-liquid separation to obtain an acidic rare earth leaching solution; magnesium oxide slurry is slowly added into the acid rare earth leaching liquid for reaction, and after the reaction is finished, solid-liquid separation is conducted to obtain rare earth impurity removal liquid. According to the method, the silicon and aluminum impurities in the rare earth enriched sulfuric acid leaching solution can be effectively removed, the cost is saved, and the environmental pollution is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth impurity removal and relates to a method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution. Background Art

[0002] Rare earth is a collective name for 17 chemical elements in the IIIth group of the periodic table, including scandium, yttrium and lanthanide elements. Rare earth elements have rich and unique physical and chemical properties such as magnetism, light, and electricity, and can be combined with other materials to form a wide variety of new materials with different properties. They are indispensable or alternative strategic materials for countries around the world to develop high-tech and cutting-edge defense technologies and transform traditional industries.

[0003] Rare earth elements themselves have similar chemical properties and are difficult to separate from each other. There are a large number of impurity ions, such as silicon and aluminum, in the rare earth concentrates obtained under the magnesium salt mining system. When carrying out subsequent processing of rare earth concentrates containing a large number of impurities, more complex processes and equipment are needed to remove impurities or compensate for the adverse effects of impurities. This not only increases the difficulty of processing, but also leads to increased energy consumption, reduced production efficiency, and increased production costs. The presence of impurities may also limit the application of certain advanced rare earth processing technologies. Some high-precision, high-performance rare earth material preparation processes have extremely high requirements for the purity of raw materials. Excessive impurity content will prevent these processes from proceeding normally, thereby limiting the diversity and high-end development of rare earth products.

[0004] In summary, removing impurities from rare earth concentrates can not only improve the recovery rate and utilization rate of rare earth elements, maximize the utilization of rare earth resources, but also save subsequent production costs.

[0005] At present, the impurity removal of rare earth sulfate mainly adopts the method of adjusting pH with ammonia water, which produces ammonia nitrogen wastewater and pollutes the environment. Therefore, it is still necessary to further develop a method for removing impurities from sulfuric acid leaching solution of rare earth enrichment. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution, which can effectively remove silicon and aluminum impurities in rare earth enriched sulfuric acid leaching solution, save costs and reduce environmental pollution.

[0007] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising:

[0009] The rare earth concentrate is slurried and mixed with acid for leaching, and solid-liquid separation is performed to obtain an acidic rare earth leaching solution;

[0010] Slowly add magnesium oxide slurry into the acidic rare earth leaching solution to carry out reaction, and after the reaction is completed, separate the solid and liquid to obtain a rare earth impurity removal solution.

[0011] As a preferred technical solution of the present invention, the pH of the acidic rare earth leaching solution is 1 to 1.5.

[0012] As a preferred technical solution of the present invention, the concentration of rare earth elements in the acidic rare earth leaching solution is 3-6 g / L.

[0013] As a preferred technical solution of the present invention, the concentration of silicon in the acidic rare earth leaching solution is 5-25% of the concentration of the rare earth element.

[0014] As a preferred technical solution of the present invention, the concentration of aluminum in the acidic rare earth leaching solution is 40-70% of the concentration of the rare earth element.

[0015] As a preferred technical solution of the present invention, the purity of magnesium oxide in the magnesium oxide slurry is greater than 95%.

[0016] As a preferred technical solution of the present invention, the total amount of magnesium oxide added in the magnesium oxide slurry is 0.8 to 1.0 times the amount of magnesium oxide required to remove all silicon and aluminum elements in the acidic rare earth leaching solution.

[0017] As a preferred technical solution of the present invention, the acidic rare earth leaching solution is stirred during the addition and reaction of the magnesium oxide slurry.

[0018] As a preferred technical solution of the present invention, the reaction time is 12 to 24 hours.

[0019] As a preferred technical solution of the present invention, the method for removing silicon and aluminum from the rare earth enriched sulfuric acid leaching solution comprises:

[0020] The rare earth concentrate is slurried and mixed with sulfuric acid for leaching, and solid-liquid separation is performed to obtain an acidic rare earth leaching solution with a pH of 1 to 1.5; the concentration of silicon in the acidic rare earth leaching solution is 5 to 25% of the concentration of the rare earth element, and the concentration of aluminum is 40 to 70% of the concentration of the rare earth element;

[0021] Adding magnesium oxide slurry to the acidic rare earth leaching solution to react for 12 to 24 hours, and separating the solid and liquid after the reaction to obtain a rare earth impurity removal solution;

[0022] The total amount of magnesium oxide added in the magnesium oxide slurry is 0.8 to 1.0 times the amount of magnesium oxide required to remove all silicon and aluminum elements in the acidic rare earth leaching solution, and the purity of magnesium oxide in the magnesium oxide slurry is greater than 95%.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] (1) The present invention provides a method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution. The method has a good impurity removal effect. The relative ratio of impurity silicon to rare earth elements (i.e., Si / REE) in the rare earth sulfate solution obtained after impurity removal is less than 0.5%, and the relative ratio of impurity aluminum to rare earth elements (i.e., Al / REE) is less than 2.5%;

[0025] (2) The present invention provides a method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution. The raw materials of the method are cheap and readily available, the process is simple and easy to control, the production cost and the operation difficulty are reduced, and the cations consumed in the magnesium salt leaching can be supplemented;

[0026] (3) The present invention provides a method for removing silicon and aluminum from sulfuric acid leaching solution of rare earth enriched materials. The method does not use ammonia water to adjust the pH value of the solution, does not produce ammonia nitrogen wastewater to pollute the environment, and realizes true ammonia-free recovery of rare earths, which is suitable for industrial production. DETAILED DESCRIPTION

[0027] The technical solution of the present application is further described below through specific implementation methods.

[0028] The specific embodiment of the present invention provides a method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising:

[0029] The rare earth concentrate is slurried and mixed with sulfuric acid for leaching, and the solid-liquid separation is performed to obtain an acidic rare earth leaching solution;

[0030] Slowly add magnesium oxide slurry into the acidic rare earth leaching solution to carry out reaction, and after the reaction is completed, separate the solid and liquid to obtain a rare earth impurity removal solution.

[0031] In the present invention, a magnesium oxide slurry that has been slurried is slowly added to an acidic rare earth leaching solution. During the reaction, the magnesium oxide first reacts with the acid in the acidic rare earth leaching solution to release water molecules. When the pH value continues to increase, the silicon and aluminum ions in the solution will be hydrolyzed to form precipitation. By controlling the pH value range, the rare earth in the solution is not precipitated at this time, and the purpose of separating the rare earth from the impurities of silicon and aluminum can be achieved after solid-liquid separation.

[0032] In a specific embodiment of the present invention, the concentration of sulfuric acid can be selected according to the leaching effect and rate, and the required pH of the acidic rare earth leaching solution, and is not further limited herein.

[0033] In a specific embodiment of the present invention, the magnesium oxide slurry can be prepared by mixing more than 95% of industrial magnesium oxide with pure water.

[0034] In a specific embodiment of the present invention, the pH of the acidic rare earth leaching solution is 1 to 1.5, such as 1, 1.1, 1.2, 1.3, 1.4 or 1.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] In a specific embodiment of the present invention, the concentration of rare earth elements in the acidic rare earth leaching solution is 3 to 6 g / L, such as 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L or 6 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In a specific embodiment of the present invention, the concentration of silicon in the acidic rare earth leaching solution is 5 to 25% of the concentration of the rare earth element, such as 5%, 10%, 15%, 20% or 25%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] In a specific embodiment of the present invention, the concentration of aluminum in the acidic rare earth leaching solution is 40% to 70% of the concentration of the rare earth element, such as 40%, 45%, 50%, 55%, 60%, 65% or 70%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] In the present invention, the impurities silicon and aluminum can be effectively removed by adjusting the pH range, and the problem of impurity precipitation wrapping rare earth or magnesium oxide, which affects the impurity removal effect and causes excessive rare earth loss, can be avoided.

[0039] In a specific embodiment of the present invention, the total amount of magnesium oxide added in the magnesium oxide slurry is 0.8 to 1.0 times the amount of magnesium oxide required to remove all silicon and aluminum elements in the acidic rare earth leachate, such as 0.8 times, 0.82 times, 0.85 times, 0.88 times, 0.9 times, 0.92 times, 0.95 times, 0.98 times or 1.0 times, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] In a specific embodiment of the present invention, the concentration of magnesium oxide in the magnesium oxide slurry can be adjusted according to the mixing conditions with the acidic rare earth leaching solution and the leaching conditions of silicon and aluminum elements, which are not specifically limited here. The concentration of magnesium oxide slurry depends on the amount of magnesium oxide added and the amount of water used for slurry adjustment.

[0041] In a specific embodiment of the present invention, the acidic rare earth leaching solution is stirred during the addition and reaction of the magnesium oxide slurry.

[0042] In a specific embodiment of the present invention, the stirring speed can be adjusted according to the mixing conditions of the magnesium oxide slurry and the acidic rare earth leaching solution, and is not specifically limited herein.

[0043] In a specific embodiment of the present invention, the reaction time is 12 to 24 hours, such as 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] Embodiment 1:

[0046] A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising the following steps:

[0047] (1) taking 0.8n industrial magnesium oxide with a purity of more than 95% and adding pure water and stirring evenly to obtain magnesium oxide slurry after slurrying;

[0048] (2) mixing the rare earth enriched material with a sulfuric acid solution of a certain concentration for reaction, separating and removing the precipitate to obtain a rare earth sulfate leaching solution with a pH of 1 to 1.5, taking 50 ml of the rare earth sulfate leaching solution and adding magnesium oxide slurry at a stirring speed of 500 rpm, wherein the rare earth element content in the system is 6 g / L after the addition of magnesium oxide slurry is completed, and reacting for 24 hours to obtain a precipitate;

[0049] (3) The precipitate is filtered and the precipitate is removed by solid-liquid separation to obtain rare earth sulfate impurity-free liquid.

[0050] Embodiment 2:

[0051] A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising the following steps:

[0052] (1) taking 0.8n industrial magnesium oxide with a purity of more than 95% and adding pure water and stirring evenly to obtain magnesium oxide slurry after slurrying;

[0053] (2) mixing the rare earth enriched material with a sulfuric acid solution of a certain concentration for reaction, separating and removing the precipitate to obtain a rare earth sulfate leaching solution with a pH of 1 to 1.5, taking 50 ml of the rare earth sulfate leaching solution and adding magnesium oxide slurry at a stirring speed of 500 rpm, wherein the rare earth element content in the system is 3 g / L after the addition of magnesium oxide slurry is completed, and reacting for 24 hours to obtain a precipitate;

[0054] (3) The precipitate is filtered and the precipitate is removed by solid-liquid separation to obtain rare earth sulfate impurity-free liquid.

[0055] Embodiment 3:

[0056] A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising the following steps:

[0057] (1) taking 0.8n industrial magnesium oxide with a purity of more than 95% and adding pure water and stirring evenly to obtain magnesium oxide slurry after slurrying;

[0058] (2) mixing the rare earth enriched material with a sulfuric acid solution of a certain concentration for reaction, separating and removing the precipitate to obtain a rare earth sulfate leaching solution with a pH of 1 to 1.5, taking 50 ml of the rare earth sulfate leaching solution and adding the magnesium oxide slurry at a stirring speed of 500 rpm, wherein the rare earth element content in the system is 4 g / L after the magnesium oxide slurry is added, and reacting for 18 hours to obtain a precipitate;

[0059] (3) The precipitate is filtered and the precipitate is removed by solid-liquid separation to obtain rare earth sulfate impurity-free liquid.

[0060] Embodiment 4:

[0061] A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising the following steps:

[0062] (1) taking 0.85n industrial magnesium oxide with a purity of more than 95% and adding pure water and stirring evenly to obtain magnesium oxide slurry after slurrying for use;

[0063] (2) mixing the rare earth enriched material with a sulfuric acid solution of a certain concentration for reaction, separating and removing the precipitate to obtain a rare earth sulfate leaching solution with a pH of 1 to 1.5, taking 50 ml of the rare earth sulfate leaching solution and adding magnesium oxide slurry at a stirring speed of 500 rpm, wherein the rare earth element content in the system is 6 g / L after the addition of magnesium oxide slurry is completed, and reacting for 24 hours to obtain a precipitate;

[0064] (3) The precipitate is filtered and the precipitate is removed by solid-liquid separation to obtain rare earth sulfate impurity-free liquid.

[0065] Embodiment 5:

[0066] A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising the following steps:

[0067] (1) taking 0.85n industrial magnesium oxide with a purity of more than 95% and adding pure water and stirring evenly to obtain magnesium oxide slurry after slurrying for use;

[0068] (2) mixing the rare earth enriched material with a sulfuric acid solution of a certain concentration for reaction, separating and removing the precipitate to obtain a rare earth sulfate leaching solution with a pH of 1 to 1.5, taking 50 ml of the rare earth sulfate leaching solution and adding the magnesium oxide slurry at a stirring speed of 500 rpm, wherein the rare earth element content in the system is 3 g / L after the magnesium oxide slurry is added, and reacting for 12 hours to obtain a precipitate;

[0069] (3) The precipitate is filtered and the precipitate is removed by solid-liquid separation to obtain rare earth sulfate impurity-free liquid.

[0070] Embodiment 6:

[0071] A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising the following steps:

[0072] (1) taking 1n industrial magnesium oxide with a purity of more than 95% and adding pure water and stirring evenly to obtain magnesium oxide slurry after slurrying for use;

[0073] (2) mixing the rare earth enriched material with a sulfuric acid solution of a certain concentration for reaction, separating and removing the precipitate to obtain a rare earth sulfate leaching solution with a pH of 1 to 1.5, taking 50 ml of the rare earth sulfate leaching solution and adding the magnesium oxide slurry at a stirring speed of 500 rpm, wherein the rare earth element content in the system is 6 g / L after the magnesium oxide slurry is added, and reacting for 12 hours to obtain a precipitate;

[0074] (3) The precipitate is filtered and the precipitate is removed by solid-liquid separation to obtain rare earth sulfate impurity-free liquid.

[0075] Embodiment 7:

[0076] A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising the following steps:

[0077] (1) taking 1n industrial magnesium oxide with a purity of more than 95% and adding pure water and stirring evenly to obtain magnesium oxide slurry after slurrying for use;

[0078] (2) mixing the rare earth enriched material with a sulfuric acid solution of a certain concentration for reaction, separating and removing the precipitate to obtain a rare earth sulfate leaching solution with a pH of 1 to 1.5, taking 50 ml of the rare earth sulfate leaching solution and adding the magnesium oxide slurry at a stirring speed of 500 rpm, wherein the rare earth element content in the system is 3 g / L after the magnesium oxide slurry is added, and reacting for 12 hours to obtain a precipitate;

[0079] (3) The precipitate is filtered and the precipitate is removed by solid-liquid separation to obtain rare earth sulfate impurity-free liquid.

[0080] Embodiment 8:

[0081] A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, the method comprising the following steps:

[0082] (1) taking 1n industrial magnesium oxide with a purity of more than 95% and adding pure water and stirring evenly to obtain magnesium oxide slurry after slurrying for use;

[0083] (2) mixing the rare earth enriched material with a sulfuric acid solution of a certain concentration for reaction, separating and removing the precipitate to obtain a rare earth sulfate leaching solution with a pH of 1 to 1.5, taking 50 ml of the rare earth sulfate leaching solution and adding the magnesium oxide slurry at a stirring speed of 500 rpm, wherein the rare earth element content in the system is 5 g / L after the magnesium oxide slurry is added, and reacting for 18 hours to obtain a precipitate;

[0084] (3) The precipitate is filtered and the precipitate is removed by solid-liquid separation to obtain rare earth sulfate impurity-free liquid.

[0085] Comparative Example 1:

[0086] The only difference from Example 1 is that 0.5n industrial magnesium oxide with a purity of more than 95% is taken and pure water is added and stirred evenly to obtain a magnesium oxide slurry after slurrying for use.

[0087] Comparative Example 2:

[0088] The only difference from Example 1 is that 0.75n industrial magnesium oxide with a purity of more than 95% is taken and pure water is added and stirred evenly to obtain a magnesium oxide slurry after slurrying for use.

[0089] Comparative Example 3:

[0090] The only difference from Example 1 is that 1.5n industrial magnesium oxide with a purity of more than 95% is taken and pure water is added and stirred evenly to obtain magnesium oxide slurry after slurrying for use.

[0091] Comparative Example 4:

[0092] The only difference from Example 1 is that the rare earth element content in the system is 1 g / L after the magnesium oxide slurry is added.

[0093] Comparative Example 5:

[0094] The only difference from Example 1 is that the rare earth element content in the system is 12 g / L after the magnesium oxide slurry is added.

[0095] Comparative Example 6:

[0096] The only difference from Example 1 is that the rare earth element content in the system is 9 g / L after the magnesium oxide slurry is added.

[0097] Comparative Example 7:

[0098] The only difference from Example 1 is that the precipitate obtained after reacting for 0.5 h is filtered.

[0099] Comparative Example 8:

[0100] The only difference from Example 1 is that the precipitate obtained after 4 hours of reaction is filtered.

[0101] Experimental example:

[0102] In Examples 1 to 8 and Comparative Examples 1 to 8, step (2) uses rare earth concentrate to prepare a slurry and then dissolve it in sulfuric acid of a certain concentration to obtain a rare earth sulfate leaching solution with a total amount of 12 g / L. The relative ratio of impurity silicon to rare earth elements (i.e., Si / REE) in the rare earth sulfate leaching solution is 20.63%, and the relative ratio of impurity aluminum to rare earth elements (i.e., Al / REE) is 61.04%. During the impurity removal process, the initial concentration of the rare earth sulfate leaching solution is changed by different amounts of water used for MgO slurry preparation. The leaching solution used in each example and comparative example is obtained by diluting the rare earth sulfate leaching solution in this way. n represents the theoretical consumption of magnesium oxide for the removal of silicon and aluminum in the rare earth sulfate leaching solution.

[0103] According to the methods of Examples 1 to 8 and Comparative Examples 1 to 8, the rare earth sulfate leaching solution prepared in this experimental example was subjected to impurity removal treatment to obtain a rare earth sulfate solution. The contents of rare earth, silicon and aluminum in the leaching solution after impurity removal were respectively detected to calculate Si / REE and Al / REE. The specific results are shown in Table 1.

[0104] Table 1

[0105]

[0106] Note: The "rare earth element content of the leaching solution" in the table refers to the content of rare earth elements in the system after the magnesium oxide slurry is added.

[0107] As shown in Table 1, the initial rare earth concentration of the rare earth sulfate leaching solution is 3-6 g / L, the amount of industrial magnesium oxide added is 0.8n-1n, and the reaction time is 12-24h. The relative ratio of impurity silicon to rare earth elements (i.e., Si / REE) in the rare earth sulfate solution obtained after impurity removal is less than 0.5%, and the relative ratio of impurity aluminum to rare earth elements (i.e., Al / REE) is less than 2.5%. When the experimental conditions are changed, such as in Comparative Example 3, when the amount of magnesium oxide added is too high, a large amount of rare earth will be lost, resulting in too high Si / REE.

[0108] The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for removing silicon and aluminum from a rare earth enriched sulfuric acid leaching solution, characterized in that: The method comprises: The rare earth concentrate is slurried and mixed with sulfuric acid for leaching, and solid-liquid separation is performed to obtain an acidic rare earth leaching solution; A magnesium oxide slurry is added to the acidic rare earth leaching solution to carry out a reaction, and after the reaction is completed, solid-liquid separation is performed to obtain a rare earth impurity removal solution.

2. The method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution according to claim 1, characterized in that: The pH of the acidic rare earth leaching solution is 1 to 1.

5.

3. The method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution according to claim 1, characterized in that: The concentration of rare earth elements in the acidic rare earth leaching solution is 3-6 g / L.

4. The method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution according to claim 1, characterized in that: The concentration of silicon in the acidic rare earth leaching solution is 5-25% of the concentration of the rare earth element.

5. The method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution according to claim 1, characterized in that: The concentration of aluminum in the acidic rare earth leaching solution is 40-70% of the concentration of the rare earth element.

6. The method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution according to claim 1, characterized in that: The purity of magnesium oxide in the magnesium oxide slurry is greater than 95%.

7. The method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution according to claim 1, characterized in that: The total amount of magnesium oxide added in the magnesium oxide slurry is 0.8 to 1.0 times the amount of magnesium oxide required to remove all silicon and aluminum elements in the acidic rare earth leaching solution.

8. The method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution according to claim 1, characterized in that: The acidic rare earth leaching solution is stirred during the addition and reaction of the magnesium oxide slurry.

9. The method for removing silicon and aluminum from rare earth enriched sulfuric acid leaching solution according to claim 1, characterized in that: The reaction time is 12 to 24 hours.

10. The method for removing silicon and aluminum from sulfuric acid leaching solution of rare earth enrichment according to any one of claims 1 to 9, characterized in that: The method comprises: The rare earth concentrate is slurried and mixed with sulfuric acid for leaching, and solid-liquid separation is performed to obtain an acidic rare earth leaching solution with a pH of 1 to 1.5; the concentration of silicon in the acidic rare earth leaching solution is 5 to 25% of the concentration of the rare earth element, and the concentration of aluminum is 40 to 70% of the concentration of the rare earth element; Adding magnesium oxide slurry to the acidic rare earth leaching solution to react for 12 to 24 hours, and separating the solid and liquid after the reaction to obtain a rare earth impurity removal solution; The total amount of magnesium oxide added in the magnesium oxide slurry is 0.8 to 1.0 times the amount of magnesium oxide required to remove all silicon and aluminum elements in the acidic rare earth leaching solution, and the purity of magnesium oxide in the magnesium oxide slurry is greater than 95%.

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