Method for comprehensively utilizing collophanite decomposed by nitric acid method
By decomposing phosphate rock using nitric acid, and combining steps such as cryogenic decalcification, neutralization precipitation, crystal transformation, and selective leaching, the problem of low rare earth element recovery rate in existing technologies has been solved, enabling low-cost preparation of high-purity rare earth oxides and synergistic utilization of multiple elements.
Patent Information
- Application Number
- CN202511154346.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-18
- Publication Date
- 2025-12-05
AI Technical Summary
In existing phosphate concentrate decomposition processes, the sulfuric acid process produces a large amount of phosphogypsum and has a low rare earth element resource recovery rate. While the nitric acid process produces less slag, its rare earth recovery rate is also low. Furthermore, existing enrichment methods are either costly or inefficient, and there is a lack of a low-cost, high-yield integrated utilization process.
After decomposing phosphate rock using nitric acid, rare earth-containing precipitate residue is obtained through freeze decalcification and neutralization precipitation. Alkaline reagents are added for crystal transformation, and selective leaching is performed using a composite leaching agent. Combined with iron and aluminum impurity removal and carbonic acid precipitation, high-purity rare earth oxides are finally obtained by calcination.
This approach enables low-cost and efficient utilization of rare earth elements without affecting existing phosphate chemical production, improves rare earth recovery rates, reduces costs through the utilization of by-products, and promotes the synergistic utilization of multiple elements.
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Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to the technical field of comprehensive recovery of collophanite, for example to a method for comprehensive utilization of collophanite after nitric acid decomposition. BACKGROUND
[0002] Phosphorite is an important strategic non-metallic mineral resource, and the global rare earth-containing phosphorite is mainly distributed in Russia, the United States, China and other countries. Zhijin County in Guizhou Province is a typical phosphorite enrichment area in China, and there are three associated rare earth ore deposits in the county, with a proven resource reserve of 858,900 tons, ranking third in China. The associated rare earth oxides in the phosphorite are mainly in the form of isomorphism in collophanite. At present, the decomposition process of phosphorite is mainly divided into sulfuric acid method and nitric acid method; among them, the sulfuric acid method produces a large amount of phosphogypsum, and only a part of rare earth elements enters the acid solution, and the resource recovery rate is low; while the nitric acid method has small slag yield when decomposing phosphorite, and more than 90% of rare earth elements can enter the acid solution. Therefore, for the decomposition process of phosphorite, the nitric acid method is more commonly used.
[0003] However, the rare earth elements in the acid solution are usually enriched by solvent extraction, resin adsorption or precipitation method; among them, the cost of solvent extraction and resin adsorption is high, and has a great impact on the existing phosphorus chemical production process; while the precipitation method has the advantages of low cost and simple operation, but the rare earth recovery rate is low, the resource utilization rate is not high and the process cost is high.
[0004] In summary, there is still a lack of low-cost and high-yield process methods for industrial application for the comprehensive utilization of phosphorite co-associated rare earth resources. SUMMARY
[0005] The purpose of the present disclosure is to overcome the deficiencies in the prior art, based on the existing process of nitric acid decomposition of collophanite, to provide a method for comprehensive utilization of collophanite after nitric acid decomposition, so as to at least achieve the effect of low-cost and efficient utilization of rare earth elements without affecting the existing phosphorus chemical production process, and obtain high-purity rare earth oxides.
[0006] The purpose of the present disclosure is achieved by the following technical solutions:
[0007] In one aspect, a method for comprehensive utilization of collophanite after decomposition by nitric acid method is provided. The method comprises: subjecting an acidolysis solution obtained by decomposing the collophanite by the nitric acid method to freeze decalcification and neutralization precipitation to obtain a rare earth-containing precipitate; wherein the collophanite is a rare earth-containing phosphate ore; adding an alkaline reagent to the rare earth-containing precipitate to perform crystal type conversion to obtain a rare earth enrichment and a phosphate conversion solution; adding a composite leaching agent to the rare earth enrichment to perform selective leaching to obtain a rare earth-rich solution; adding a pH adjusting agent to the rare earth-rich solution to perform iron and aluminum impurity removal to obtain a rare earth purified solution; adding a carbonate to the rare earth purified solution to perform carbonic acid precipitation to obtain a carbonic acid rare earth precipitate; and calcining the carbonic acid rare earth precipitate to obtain a rare earth oxide.
[0008] It is worth noting that the rare earth elements in the rare earth-containing precipitate obtained after the acidolysis solution is subjected to the freeze decalcification and the neutralization precipitation mainly exist in the form of phosphate, and have not yet formed a structure-stable mineral form, and are mainly amorphous minerals.
[0009] Therefore, in the method provided in the present disclosure, first, the crystal type conversion of the rare earth-containing precipitate by using the alkaline reagent can convert the rare earth elements in the rare earth phosphate into rare earth hydroxide and remain in the slag, so as to realize the crystal type conversion of the rare earth and improve the grade of the rare earth, thereby obtaining the rare earth enrichment; then, the selective leaching of the rare earth enrichment by using the composite leaching agent can realize the selective extraction of the rare earth, thereby obtaining the rare earth-rich solution; finally, the iron and aluminum impurity removal, the carbonic acid precipitation and the calcination of the rare earth-rich solution can prepare the high-purity rare earth oxide with a TREO content greater than 90%.
[0010] It should be understood that the nitric acid method decomposition, the freeze decalcification and the neutralization precipitation involved in the method provided in the present disclosure are all mature processes, and various methods can be used. The person skilled in the art can make adaptive selection according to the actual needs, and the present disclosure does not limit this.
[0011] For example, the nitric acid method decomposition, the freeze decalcification and the neutralization precipitation can be performed according to the method described in the doctoral thesis “Migration and distribution of phosphorite co-associated elements in the nitric acid phosphate fertilizer process” by Yang Ping of Guizhou University; wherein the reaction conditions of the nitric acid method decomposition include: a mass fraction of nitric acid of 55%, an acidolysis ratio of 1.25:1, an acidolysis temperature of 60°C, and an acidolysis time of 120 min; the reaction conditions of the freeze decalcification include: a freeze end point temperature of -2°C, a crystallization time of 120 min, a calcium removal rate of more than 80%, and a rare earth recovery rate of 95%; and the reaction conditions of the neutralization precipitation include: a pH value of 1.8, a neutralization temperature of 60°C, and a neutralization time of 180 min.
[0012] In some embodiments, the alkaline reagent comprises at least one of ammonia, sodium hydroxide and potassium hydroxide.
[0013] In some embodiments described above, by using the ammonia, the sodium hydroxide or the potassium hydroxide as the alkaline reagent for the crystal type conversion, the phosphate ions in the rare earth phosphate can be correspondingly converted into ammonium phosphate, sodium phosphate or potassium phosphate and transferred into the solution, so as to obtain the phosphate conversion solution, thus the recycling of the phosphorus element in the rare earth-containing precipitate can be effectively realized; in addition, the phosphate byproduct (i.e. ammonium phosphate, sodium phosphate or potassium phosphate) recycled from the phosphate conversion solution can be further used as nitrogen fertilizer, phosphorus fertilizer or other multi-element compound fertilizer, which not only can avoid the environmental pollution problem, but also can effectively reduce the cost.
[0014] In some embodiments, the alkaline reagent is the ammonia; the reaction condition of the crystal type conversion comprises: the mass concentration of the alkaline reagent is 5% to 25%, the liquid-solid ratio is 2 to 10:1, the pressure is 0.5 to 2.0 MPa, the temperature is 80 to 150℃, and the time is 0.5 to 2h.
[0015] In some embodiments described above, by using the ammonia as the alkaline reagent for the crystal type conversion, and on the basis of limiting the reaction condition of the crystal type conversion, the conversion of the rare earth phosphate into ammonium phosphate can be effectively realized under the condition of pressure leaching, and the generated ammonium phosphate byproduct contains nitrogen element and phosphorus element, which has good agricultural prospect.
[0016] In some embodiments, the alkaline reagent is the sodium hydroxide or the potassium hydroxide; the reaction condition of the crystal type conversion comprises: the concentration of the alkaline reagent is 50 to 300g / L, the liquid-solid ratio is 2 to 10:1, the pressure is normal pressure, the temperature is 50 to 100℃, and the time is 1 to 4h.
[0017] It is easy to understand that the term "normal pressure" in the above means a standard atmospheric pressure, which is 101.325kPa.
[0018] In some embodiments described above, by using the sodium hydroxide or the potassium hydroxide as the alkaline reagent for the crystal type conversion, the reaction condition of the crystal type conversion does not need to be pressurized, the conversion of the rare earth phosphate into sodium phosphate or potassium phosphate can be effectively realized under the condition of normal pressure and temperature rise, the operation is more simple, and the generated sodium phosphate byproduct or potassium phosphate byproduct also has certain application value.
[0019] In some embodiments, the composite leaching agent comprises an acid and a salt; wherein the acid comprises one of sulfuric acid, hydrochloric acid and nitric acid, and the salt comprises one of ammonium sulfate and magnesium sulfate.
[0020] In some examples, the concentration of the salt is 10-40 g / L.
[0021] In some embodiments, the reaction conditions of the selective leaching include: pH value of 3.2-4.6, liquid-solid ratio of 2-6:1, temperature of room temperature, and time of 0.5-2 h.
[0022] It is easily understood that the term "room temperature" in the above means room temperature, and the value is generally 25℃.
[0023] In some embodiments, the pH regulator includes at least one of ammonium bicarbonate, sodium hydroxide, sodium carbonate, sodium bicarbonate, and basic magnesium carbonate.
[0024] In some embodiments, the pH value of the iron and aluminum removal is 4.8-5.2.
[0025] In some embodiments, the carbonate includes at least one of ammonium bicarbonate, sodium carbonate, sodium bicarbonate, and basic magnesium carbonate.
[0026] In some embodiments, the pH value of the carbonic acid precipitation is 6.8-7.2.
[0027] In some embodiments, the calcination temperature is 800-1000℃, and the calcination time is 4-8 h.
[0028] In some embodiments, in the collophanite, the content of TREO is 0.05%-0.20%, and the content of P2O5 is greater than or equal to 24%.
[0029] The beneficial effects of the present disclosure are:
[0030] 1. The method for comprehensive utilization of collophanite after nitric acid decomposition provided by the present disclosure can convert rare earth elements in rare earth phosphate into rare earth hydroxide and leave them in the slag by using an alkaline reagent for crystal type conversion, so as to improve the grade of rare earth while realizing the crystal type conversion of rare earth, and then through selective leaching, iron and aluminum removal, carbonic acid precipitation, and calcination, high-purity rare earth oxide with a TREO content greater than 90% can be prepared.
[0031] 2. The method for comprehensive utilization of collophanite after nitric acid decomposition provided by the present disclosure can make phosphate ions form soluble phosphate and transfer to the solution by using ammonia, sodium hydroxide, or potassium hydroxide as an alkaline reagent in the process of crystal type conversion, which not only can effectively realize the recycling of phosphorus elements, but also the by-products can be used as nitrogen fertilizer, phosphorus fertilizer, or other multi-element compound fertilizer, so as to avoid the generation of environmental pollution problems and effectively reduce the cost.
[0032] 3. The method for comprehensive utilization of collophanite after decomposition by nitric acid method provided by the present disclosure can not only realize low-cost and efficient utilization of rare earth under the premise of not affecting the existing phosphorus chemical production process, so as to obtain high-purity rare earth oxide, but also can promote the multi-element synergistic utilization of rare earth-containing phosphorus ore, and can help to promote the industrialization process of comprehensive utilization of rare earth-containing phosphorus ore resources. BRIEF DESCRIPTION OF DRAWINGS
[0033] In order to more clearly illustrate the technical solutions in the present disclosure, the drawings needed to be used in some embodiments of the present disclosure will be briefly introduced as follows. Obviously, the drawings in the following description are only the drawings of some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art according to these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams, and are not limited to the actual process of the method involved in the embodiments of the present disclosure.
[0034] Figure 1 Process flow diagram of the method for comprehensive utilization of collophanite after decomposition by nitric acid method according to some embodiments. DETAILED DESCRIPTION
[0035] The technical solutions in some embodiments of the present disclosure will be described clearly and completely as follows. Obviously, the described embodiments are only some of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present disclosure.
[0036] Unless otherwise required by the context, the term “comprising” is interpreted to be open, inclusive, meaning “including, but not limited to” in the entire specification and claims.
[0037] In describing some embodiments, the expression “A and / or B” can be used. It is easily understood that “A and / or B” includes the following three combinations: only A, only B, and the combination of A and B.
[0038] In describing some embodiments, the expressions “at least one of A, B, and C” and “at least one of A, B, or C” can be used, both of which have the same meaning and include the following combinations of A, B, and C: only A, only B, only C, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B, and C.
[0039] Example 1 Preparation of rare earth-containing precipitated slag
[0040] The rare earth-containing precipitate was prepared by using Guizhou Zhongjing phosphate concentrate (P2O5 grade of 31.19%, TREO grade of 0.15%) and referring to the thesis "Migration and distribution of phosphate ore co-associated elements in the process of frozen nitric acid phosphate fertilizer" by Yang Ping of Guizhou University. The acidolysis conditions are as follows: reaction temperature 60°C, mass fraction of HNO3 55%, acidolysis ratio 1.25:1, and acidolysis time 120 min. The freezing crystallization conditions of the acidolysis solution are as follows: freezing end temperature -2°C, and crystallization time 120 min. The calcium removal rate is above 80%, and the rare earth recovery rate is 95%. Subsequently, ammonia neutralization is performed under the following conditions: pH = 1.7, neutralization time 180 min, and neutralization temperature 60°C. The rare earth-containing precipitate is obtained, in which the content of total rare earth TREO is 1.17%.
[0041] Example 2
[0042] A method for comprehensive utilization of collophanite after nitric acid decomposition, the main steps of which are shown in Figure 1 and specifically include:
[0043] S1. Ammonia water is added to the rare earth-containing precipitate in Example 1 for crystal type conversion (conditions: mass concentration of ammonia water 15%, ammonia immersion pressure 1.0 MPa, ammonia immersion liquid-solid ratio 5:1, reaction temperature 120°C, and reaction time 1 h) to obtain a rare earth enrichment and a conversion solution. The content of total rare earth TREO in the rare earth enrichment is 2.94%. The main component of the conversion solution is phosphate, which can be used for recovery of ammonium phosphate and obtainment of a corresponding ammonium phosphate byproduct, which can be used for preparation of a multi-element compound fertilizer.
[0044] S2. The rare earth enrichment is slurried by adding 20 g / L ammonium sulfate according to a liquid-solid ratio L / S = 4:1, and sulfuric acid is added to adjust the pH value of selective leaching (i.e., acid-salt composite leaching) to 4.0. After reaction at room temperature for 1 h, a rare earth-rich solution is obtained by filtration, and the rare earth leaching rate is 90.50%.
[0045] S3. The rare earth-rich solution is adjusted to a pH value of 5.0 by adding ammonium bicarbonate for iron and aluminum removal to obtain a rare earth purification solution.
[0046] S4. The rare earth purification solution is adjusted to a pH value of 7.0 by adding ammonium bicarbonate for carbonic acid precipitation to obtain carbonic acid rare earth.
[0047] S5. The carbonic acid rare earth is calcined at 1000°C for 6 h to obtain a rare earth oxide (i.e., an oxide rare earth product), in which the content of total rare earth TREO is 94.26%.
[0048] Example 3
[0049] A method for comprehensive utilization of collophanite after nitric acid decomposition, the main steps of which are shown in Figure 1As shown, specifically comprising:
[0050] S1. Adding sodium hydroxide to the rare earth-containing precipitate slag in Example 1 for crystal transformation (conditions: the concentration of sodium hydroxide is 200 g / L, the liquid-solid ratio is 4:1, the reaction temperature is 90℃, the reaction time is 2h, and the reaction pressure is normal pressure), to obtain a rare earth concentrate and a conversion solution; wherein the content of the total rare earth amount TREO in the rare earth concentrate is 3.46%; the main component of the conversion solution is phosphate, and the conversion solution can be used for recovering sodium phosphate and obtaining a corresponding sodium phosphate byproduct;
[0051] S2. The rare earth concentrate is slurried according to a liquid-solid ratio L / S = 4:1 with the addition of 10 g / L ammonium sulfate, and the pH value of the selective leaching (i.e., acid-salt composite leaching) is adjusted to 3.2 by adding sulfuric acid, and after 0.5h of reaction at room temperature, a rare earth-rich solution is obtained by filtration, and the rare earth leaching rate is 91.46%;
[0052] S3. The rare earth-rich solution is adjusted to a pH value of 4.8 by adding ammonium bicarbonate for iron and aluminum impurity removal, to obtain a rare earth purification solution;
[0053] S4. The rare earth purification solution is adjusted to a pH value of 7.2 by adding ammonium bicarbonate for carbonic acid precipitation, to obtain a rare earth carbonate;
[0054] S5. The rare earth carbonate is calcined at 1000℃ for 4h to obtain a rare earth oxide (i.e., an oxide rare earth product), wherein the content of the total rare earth amount TREO is 92.27%.
[0055] Example 4
[0056] A method for comprehensive utilization of collophanite after decomposition by nitric acid method, the main steps of which are as shown Figure 1 As shown, specifically comprising:
[0057] S1. Adding potassium hydroxide to the rare earth-containing precipitate slag in Example 1 for crystal transformation (conditions: the concentration of potassium hydroxide is 300 g / L, the liquid-solid ratio is 2:1, the reaction temperature is 100℃, the reaction time is 4h, and the reaction pressure is normal pressure), to obtain a rare earth concentrate and a conversion solution; wherein the content of the total rare earth amount TREO in the rare earth concentrate is 3.75%; the main component of the conversion solution is phosphate, and the conversion solution can be used for recovering potassium phosphate and obtaining a corresponding potassium phosphate byproduct, which can be used for preparing a multi-element compound fertilizer;
[0058] S2. The rare earth concentrate is slurried according to a liquid-solid ratio L / S = 2:1 with the addition of 40 g / L ammonium sulfate, and the pH value of the selective leaching (i.e., acid-salt composite leaching) is adjusted to 4.6 by adding sulfuric acid, and after 2h of reaction at room temperature, a rare earth-rich solution is obtained by filtration, and the rare earth leaching rate is 89.78%;
[0059] S3. The rich rare earth solution is adjusted to pH 5.2 by adding ammonium bicarbonate, and iron and aluminum impurities are removed to obtain a rare earth purification solution;
[0060] S4. The rare earth purification solution is adjusted to pH 6.8 by adding ammonium bicarbonate, and carbonic acid precipitation is performed to obtain a rare earth carbonate;
[0061] S5. The rare earth carbonate is calcined at 1000°C for 8h to obtain a rare earth oxide (i.e., a rare earth oxide product), wherein the content of the total rare earth amount TREO is 96.35%.
[0062] Comparative Example 1
[0063] Comparative Example 1 is compared with Example 2, wherein Comparative Example 1 uses the rare earth-containing precipitate slag in Example 1, and the difference between Comparative Example 1 and Example 2 is that S1 is not included, and the rare earth concentrate in S2 is replaced with the rare earth-containing precipitate slag; other conditions such as the selection and amount of the remaining reagents and the steps and conditions of the process are the same as those in Example 2.
[0064] The results show that the leaching rate of rare earth in S2 of Comparative Example 1 is 1.05%. It can be seen that if the crystal transformation in S1 is not performed, the leaching effect of rare earth is poor, and the selective extraction of rare earth cannot be achieved.
[0065] Comparative Example 2
[0066] Comparative Example 2 is compared with Example 2, wherein Comparative Example 2 uses the rare earth-containing precipitate slag in Example 1, and the difference between Comparative Example 2 and Example 2 is that ammonium sulfate is not added in S2; other conditions such as the selection and amount of the remaining reagents and the steps and conditions of the process are the same as those in Example 2.
[0067] The results show that the leaching rate of rare earth in S2 of Comparative Example 2 is 30.12%, and the content of the total rare earth amount TREO in the rare earth oxide in S5 is 88.17%. It can be seen that if ammonium sulfate is lacking in S2 for synergistic leaching, the leaching rate of rare earth will decrease significantly, and the selective extraction effect is poor, and the content of the rare earth oxide decreases to a certain extent.
[0068] Comparative Example 3
[0069] Comparative Example 3 is compared with Example 4, wherein Comparative Example 3 uses the rare earth-containing precipitate slag in Example 1, and the difference between Comparative Example 3 and Example 4 is that S1 is not included, and the rare earth concentrate in S2 is replaced with the rare earth-containing precipitate slag; other conditions such as the selection and amount of the remaining reagents and the steps and conditions of the process are the same as those in Example 4.
[0070] The results show that the leaching rate of rare earth in S2 of the control example 3 is 0.85%, and it can be seen that if the crystal transformation in S1 is not performed, the leaching effect of rare earth is poor, and the selective extraction of rare earth cannot be realized.
[0071] Control example 4
[0072] The control example 4 is compared with the example 4, wherein the control example 4 uses the rare earth-containing precipitate slag in the example 1, and the difference between the control example 4 and the example 4 is that no ammonium sulfate is added in S2; and other conditions such as the selection and dosage of the remaining reagents and the steps and conditions of the process are the same as those in the example 4.
[0073] The results show that the leaching rate of rare earth in S2 of the control example 4 is 18.78%, and the content of the total amount of rare earth TREO in the rare earth oxide in S5 is 79.66%. It can be seen that if the ammonium sulfate is lacking in S2 for the synergistic leaching, the leaching rate of rare earth will be greatly reduced, the effect of selective extraction is poor, and the content of the rare earth oxide is decreased.
[0074] Therefore, the method for comprehensive utilization of the collophanite after decomposition by the nitric acid method provided by the present disclosure can not only realize the low-cost and efficient utilization of rare earth without affecting the existing phosphorus chemical production process, so as to obtain high-purity rare earth oxide, but also can promote the multi-element synergistic utilization of the rare earth-containing phosphorus ore, and can help to promote the industrialization process of the comprehensive utilization of the rare earth-containing phosphorus ore resources.
[0075] The above only describes the preferred embodiments of the present disclosure, and it should be understood that the present disclosure is not limited to the forms disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified by the above-mentioned teaching or related technical or knowledge within the scope of the concept described herein. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present disclosure shall be within the protection scope of the appended claims of the present disclosure.
Claims
1. A method for the comprehensive utilization of phosphate rock after nitric acid decomposition, characterized in that, include: The acid hydrolysate obtained after the decomposition of the collophane by the nitric acid method is subjected to freeze decalcification and neutralization precipitation to obtain rare earth-containing precipitate residue; wherein, the collophane is a rare earth-containing phosphate ore; An alkaline reagent is added to the rare earth-containing precipitate residue to carry out crystal transformation, thereby obtaining rare earth enrichment and phosphate conversion solution. A composite leaching agent is added to the rare earth enrichment for selective leaching to obtain a rare earth-rich solution. A pH adjuster was added to the rare earth-rich solution to remove iron and aluminum impurities, resulting in a rare earth purified solution. Adding carbonates to the rare earth purification solution to induce carbonic acid precipitation, yielding rare earth carbonate precipitate; and The rare earth carbonate precipitate was calcined to obtain rare earth oxides.
2. The method according to claim 1, characterized in that, The alkaline reagent includes at least one of ammonia, sodium hydroxide, and potassium hydroxide.
3. The method according to claim 2, characterized in that, The alkaline reagent is the ammonia solution; The reaction conditions for the crystal transformation include: the mass concentration of the alkaline reagent is 5% to 25%, the liquid-to-solid ratio is 2 to 10:1, the pressure is 0.5 to 2.0 MPa, the temperature is 80 to 150 °C, and the time is 0.5 to 2 h.
4. The method according to claim 2, characterized in that, The alkaline reagent is either sodium hydroxide or potassium hydroxide; The reaction conditions for the crystal transformation include: the concentration of the alkaline reagent is 50-300 g / L, the liquid-to-solid ratio is 2-10:1, the pressure is atmospheric pressure, the temperature is 50-100℃, and the time is 1-4 h.
5. The method according to claim 1, characterized in that, The composite leaching agent includes acids and salts; The acid includes one of sulfuric acid, hydrochloric acid, and nitric acid, and the salt includes one of ammonium sulfate and magnesium sulfate.
6. The method according to claim 1 or 5, characterized in that, The selective leaching reaction conditions include: pH value of 3.2-4.6, liquid-to-solid ratio of 2-6:1, temperature of room temperature, and time of 0.5-2 hours.
7. The method according to claim 1, characterized in that, The pH adjuster includes at least one of ammonium bicarbonate, sodium hydroxide, sodium carbonate, sodium bicarbonate, and basic magnesium carbonate; and / or, the pH value of the iron and aluminum impurity removal is 4.8 to 5.
2.
8. The method according to claim 1, characterized in that, The carbonate includes at least one of ammonium bicarbonate, sodium carbonate, sodium bicarbonate, and basic magnesium carbonate; and / or the pH of the carbonate precipitate is 6.8 to 7.
2.
9. The method according to claim 1, characterized in that, The calcination temperature is 800–1000℃, and the calcination time is 4–8 hours.
10. The method according to claim 1, characterized in that, In the collophane, the TREO content is 0.05% to 0.20%, and the P2O5 content is greater than or equal to 24%.