Comprehensive recovery method for preparing sodium phosphate, aluminum and lithium from phosphorus lithium aluminum ore nitric acid leaching solution

Abstract

The invention provides a comprehensive recovery method for preparing sodium phosphate, aluminum and lithium from a lithium phosphate ore nitric acid leaching solution, and belongs to the technical field of comprehensive recovery of lithium ores, and the comprehensive recovery method comprises the following steps: adding an iron source into the lithium phosphate ore nitric acid leaching solution, dissolving and filtering to obtain an iron-containing leaching solution and insoluble slag; heating and precipitating the obtained iron-containing immersion liquid to obtain crude iron phosphate and an iron phosphate precipitated liquid; performing alkali dissolution on the crude ferric phosphate to obtain ferric hydroxide precipitate and a sodium phosphate solution; crystallizing the sodium phosphate solution to obtain a sodium phosphate product; carrying out chemical precipitation on the iron phosphate precipitation post-liquid to obtain a product aluminum hydroxide and an aluminum hydroxide precipitation post-liquid; and performing chemical impurity removal on the aluminum hydroxide precipitation solution, and adding a sodium carbonate solution to precipitate lithium to obtain the product battery-grade lithium carbonate. According to the method, phosphorus, aluminum and lithium are efficiently separated and extracted, sodium phosphate, aluminum hydroxide and battery-grade lithium carbonate products are obtained, the resource utilization rate of the phosphorus lithium aluminum ore is greatly increased, and the economic value of the phosphorus lithium aluminum ore is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive recovery of lithium ore, and particularly relates to a comprehensive recovery method for preparing sodium phosphate, aluminum and lithium from a nitric acid leaching solution of lithium aluminum phosphate. Background Art

[0002] Sodium phosphate is an important chemical raw material. Through observation and analysis of the sodium phosphate industry market, it is found that sodium phosphate can be widely used in electroplating industry, food industry, medicine and other fields, and has huge development potential.

[0003] Phospholipid-lithium aluminum ore contains large amounts of phosphorus, lithium, and aluminum, but the process of recovering these valuable metals through the nitric acid method has been relatively understudied. Utilizing this process to comprehensively recover the valuable elements present in it would have significant economic value. Summary of the Invention

[0004] The present invention provides a method for separating and extracting valuable elements from nitric acid leachate of lithium-phosphorus aluminum ore, preparing sodium phosphate, and comprehensively recovering aluminum and lithium. The method utilizes principles such as chemical precipitation to efficiently separate and extract phosphorus, aluminum, and lithium from an acidic solution containing phosphorus, aluminum, and lithium, yielding sodium phosphate, aluminum hydroxide, and battery-grade lithium carbonate products. The method utilizes simple processes and equipment, inexpensive raw and auxiliary materials, low energy costs, and high product quality. It is environmentally friendly, low-carbon, and economically viable, maximizing resource utilization.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium aluminum phosphate ore comprises the following steps:

[0007] S1, adding an iron source to the nitric acid leachate of pyroxenite, dissolving it and filtering it to obtain an iron-containing leachate and an insoluble slag;

[0008] S2, heating, precipitating, and filtering the iron-containing leaching solution obtained in step S1 in sequence to obtain crude ferric phosphate and a solution after precipitation of ferric phosphate;

[0009] S3, alkali-dissolving and filtering the crude ferric phosphate obtained in step S2 to obtain a sodium phosphate solution and ferric hydroxide;

[0010] S4, crystallizing the sodium phosphate solution obtained in step S3 to obtain a sodium phosphate product;

[0011] S5. Chemically precipitating the ferric phosphate precipitation solution obtained in step S2 to obtain an aluminum hydroxide product and an aluminum hydroxide precipitation solution;

[0012] S6. The liquid after precipitation of aluminum hydroxide obtained in step S5 is subjected to impurity removal and lithium precipitation in sequence to obtain battery-grade lithium carbonate.

[0013] Preferably, in step S1, the method for preparing the nitric acid leachate of the phosphate lithium aluminum ore is as follows: adding excess nitric acid to the phosphate lithium aluminum ore with a mesh size of less than 200 mesh, reacting for 3 hours under pressure, and then separating the solid and liquid to obtain a nitric acid leachate. The chemical composition of the nitric acid leachate includes: Li: 6.5~8g / L, Na: 0.1~0.3g / L, Fe: 0.3~0.8g / L, Al: 25~30g / L, Mn: 0.05~1g / L, Ca: 0.01~0.05g / L, Mg: 0.1~0.15g / L, Si: 0.01~0.05g / L, P: 25~30g / L, K: 0.2~0.5g / L, H + :3~4mol / L.

[0014] Preferably, in step S1, the iron source is an acid-soluble iron-containing material, selected from at least one of reducing iron powder, iron oxide, and iron hydroxide, such as iron powder, ferric hydroxide, etc. The iron source consumption is determined by the phosphorus-iron molar ratio, and preferably the phosphorus-iron molar ratio is (0.8-1.2): 1. Suitable phosphorus-iron ratio can ensure that a large amount of phosphorus elements in the leachate can be precipitated by forming crude ferric phosphate. After the iron is dissolved, the iron content in the liquid is about 25-40g / L, and the insoluble slag is mainly a small amount of undissolved iron source, wherein the mass content of iron is about 90%. The insoluble slag can return to S1 and continue to be used as an iron source.

[0015] Preferably, in step S2, the reaction temperature is controlled at 60-120°C and the reaction time is controlled at 4-10 hours to obtain crude ferric phosphate. Selecting this reaction temperature facilitates the precipitation of ferric phosphate and the separation of phosphorus from aluminum in the iron-containing leaching solution. After precipitation of the ferric phosphate, the solution primarily contains aluminum ions and lithium ions.

[0016] Preferably, in step S3, the alkali used is a sodium hydroxide solution, the amount of which is determined according to the molar amount of iron in the ferric phosphate to be dissolved, and the molar amount of sodium hydroxide is controlled to be 2 to 4 times the molar amount of iron. Alkali dissolution is mainly the reaction of iron ions with hydroxide to form iron hydroxide precipitate, the amount of alkali is determined according to the iron content, and the liquid-solid mass ratio during the alkali dissolution is controlled to be 5:1 to 15:1, the alkali dissolution temperature is room temperature to 80 ° C, the dissolution time is 1 to 1.5 hours, and the iron hydroxide obtained by the dissolution reaction is returned to step S1 for use.

[0017] Preferably, in step S4, the crystalline sodium phosphate is first evaporated and concentrated, and then naturally cooled and crystallized, and the crystallization endpoint is when the temperature drops to room temperature. The sodium content in the evaporation and concentration crystallization endpoint liquid is 120-250 g / L, and the crystallization mother liquor is returned to step S3 for alkali preparation.

[0018] Preferably, in step S5, the solution after precipitation of ferric phosphate is adjusted to pH 7 by adding sodium hydroxide at room temperature and reacted for 1 to 1.5 hours to prepare aluminum hydroxide. The main reaction in this step is that the aluminum ions in the solution after precipitation of ferric phosphate react with sodium hydroxide to form aluminum hydroxide precipitate.

[0019] Preferably, in step S6, sodium hydroxide is added to the solution after precipitation of aluminum hydroxide to adjust the pH to 12, and then filtered to remove trace impurities such as calcium and magnesium. Then, a 30% by mass sodium carbonate solution is added to the filtrate to obtain battery-grade lithium carbonate. The mother liquor of lithium precipitation can be returned to S3 for alkali preparation.

[0020] The above technical solution provided by the present invention brings at least the following beneficial effects:

[0021] The method of the present invention uses nitric acid leachate of lithium aluminum phosphate as raw material, adds compounds such as an iron source to the acidic solution, selectively precipitates by controlling the pH value and reaction temperature of the reaction system, separates aluminum, phosphorus, lithium and other metal impurities, and efficiently separates and extracts phosphorus, aluminum and lithium in the solution to obtain sodium phosphate, aluminum hydroxide and battery-grade lithium carbonate products. The purpose of preparing sodium phosphate and comprehensive recycling of valuable elements from nitric acid leachate containing phosphorus, aluminum and lithium is achieved, breaking the process barriers. In addition, the iron source introduced in the process can be recycled, and sodium hydroxide is the main raw material of the product sodium phosphate. In addition, no other impurity elements are introduced, which has the advantage of being green and environmentally friendly.

[0022] In step S1 of the present invention, the iron source is dissolved in the system by the nitric acid remaining in the leachate;

[0023] In steps S2 to S4, the phosphorus in the solution is precipitated in the form of ferric phosphate by controlling the temperature and time, and the crude ferric phosphate is then dissolved by alkali, and finally the product sodium phosphate is obtained by crystallization.

[0024] Step S5, recovering aluminum in the solution after precipitation of ferric phosphate by chemical precipitation to obtain aluminum hydroxide product.

[0025] Step S6, recovering lithium in the solution after precipitation of aluminum hydroxide by carbonization to obtain lithium carbonate product.

[0026] In the above process, the efficient recovery of phosphorus, lithium and aluminum not only produces sodium phosphate, aluminum hydroxide and lithium carbonate products, but also reduces the difficulty of the subsequent sodium phosphate preparation process. The multiple steps of the entire process work together to greatly improve the recovery rate of each valuable metal. The overall process is simple and easy to operate, easy to scale and green and environmentally friendly, low cost, easy to achieve industrial production, high return on investment, and maximum economic benefits. It achieves the goals of energy conservation and emission reduction and the long-term goal of sustainable development. Phosphorus resource utilization produces sodium phosphate, reduces resource waste, increases economic benefits, reduces the cost of treating phosphorus in wastewater, and reduces environmental pollution. After the precipitation of iron phosphate, the liquid can be chemically precipitated to obtain aluminum hydroxide, and after the precipitation of aluminum hydroxide, the liquid can be carbonized to produce battery-grade lithium carbonate products. From then on, the efficient comprehensive recovery of phosphorus, aluminum and lithium in the nitric acid leaching solution of lithium-phosphate aluminum ore is achieved.

[0027] The present invention achieves efficient separation and recovery of phosphorus, aluminum, and lithium through simple processes and equipment, reducing environmental pollution and improving economic benefits. The materials used are easy to purchase and inexpensive; the process is short, the operation is simple and easy to control, the cost is low, the raw materials are widely available, energy consumption is low, and it is environmentally friendly, making it easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 The present invention provides a flow chart of a comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium aluminum phosphate ore. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0031] The analysis results of the components of the nitric acid leachate used in the following examples and comparative examples are shown in Table 1. The hydrogen ion concentration in the nitric acid leachate of phosphate lithium aluminum ore is 3-4 mol / L, and the battery-grade lithium carbonate standard is shown in Table 2.

[0032] Table 1 Analysis results of components of nitric acid leaching solution of lithium aluminum phosphate

[0033]

[0034] Table 2 Battery-grade lithium carbonate standards (wt%) (YS / T582-2013)

[0035] (Except lithium carbonate, the content of other impurities is less than or equal to the standard shown)

[0036] Example 1

[0037] like Figure 1 As shown, a comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leaching solution of lithium aluminum phosphate ore specifically comprises the following steps:

[0038] S1: adding iron powder to the nitric acid leachate of phosphate-lithium aluminum ore at a phosphorus-iron molar ratio of 0.9:1, and filtering to obtain the iron-containing leachate and insoluble slag.

[0039] S2: The temperature of the iron-containing leaching solution obtained in step S1 is controlled at 90° C. and kept warm for 6 hours, and crude ferric phosphate and the precipitated ferric phosphate solution are obtained by filtration.

[0040] S3: The crude iron phosphate obtained in step S2 is treated according to the molar ratio of Fe 3+ :OH - =1:3 for alkali dissolution, control the alkali dissolution temperature at 60°C, the liquid-to-solid ratio at 10:1, stir the reaction at room temperature for 1 h, and the stirring speed is 100 rpm. Filter to obtain sodium phosphate solution and insoluble matter.

[0041] S4: Evaporate and crystallize the sodium phosphate solution obtained in step S3 until the sodium content in the mother liquor is 150 g / L, then cool to room temperature and filter to obtain the product sodium phosphate.

[0042] S5: The ferric phosphate precipitation solution obtained in step S2 is adjusted to pH 7 by adding sodium hydroxide at room temperature, reacted for 1 hour, and then filtered to obtain aluminum hydroxide and the aluminum hydroxide precipitation solution.

[0043] S6: adding sodium hydroxide to the solution after aluminum hydroxide precipitation in step S5 to adjust the system pH to 12 to remove residual calcium and magnesium ions, and adding a 30% by mass sodium carbonate solution to the filtered solution to precipitate lithium to obtain battery-grade lithium carbonate.

[0044] The aluminum recovery rate obtained in this embodiment is 85.1%, the phosphorus recovery rate is 93.2%, and the lithium recovery rate is 97.6%.

[0045] Product quality: Sodium phosphate purity: 97.55%, aluminum hydroxide purity: 94.1%, lithium carbonate purity: 99.74%. The specific content of the lithium carbonate product of the present invention is shown in Table 3.

[0046] Table 3 Content of lithium carbonate product of the present invention (wt%)

[0047]

[0048] Note: The main content and impurity content of the battery-grade lithium carbonate obtained in Examples 2 to 5 all meet the standards.

[0049] Example 2

[0050] A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from a nitric acid leaching solution of lithium aluminum phosphate ore is implemented using the method of Example 1, except that:

[0051] In step S1, the iron source is ferric hydroxide, and the amount used is based on a phosphorus to iron molar ratio of 0.9:1;

[0052] In step S2, the temperature of the iron-containing immersion liquid is controlled at 110° C. and kept warm for 6 hours, and the crude ferric phosphate and the precipitated ferric phosphate liquid are obtained by filtration.

[0053] In step S3, crude ferric phosphate is prepared according to the molar ratio of Fe 3+ :OH - =1:3 for alkali dissolution, control the alkali dissolution temperature at 80℃, and the liquid-to-solid ratio at 12:1.

[0054] The aluminum recovery rate obtained in this embodiment is 80.4%, the phosphorus recovery rate is 96.3%, and the lithium recovery rate is 97.4%.

[0055] Product quality: Sodium phosphate purity: 96.25%, aluminum hydroxide purity: 95.3%, lithium carbonate purity: 99.8%.

[0056] Example 3

[0057] A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from a nitric acid leaching solution of lithium aluminum phosphate ore is implemented using the method of Example 1, except that:

[0058] In step S1, the iron source is iron powder, and the amount used is based on a phosphorus to iron molar ratio of 1:1;

[0059] In step S2, the temperature of the iron-containing immersion liquid is controlled at 60° C. and kept warm for 6 hours, and the crude ferric phosphate and the precipitated ferric phosphate liquid are obtained by filtration.

[0060] In step S3, crude ferric phosphate is prepared according to the molar ratio of Fe 3+ :OH - =1:2 for alkali dissolution, control the alkali dissolution temperature at 60℃, and the liquid-to-solid ratio at 5:1.

[0061] The aluminum recovery rate obtained in this embodiment is 87.9%, the phosphorus recovery rate is 90.7%, and the lithium recovery rate is 98.1%.

[0062] Product quality: Sodium phosphate purity: 97.45%, aluminum hydroxide purity: 92.5%, lithium carbonate purity: 99.6%.

[0063] Example 4

[0064] A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from a nitric acid leaching solution of lithium aluminum phosphate ore is implemented using the method of Example 1, except that:

[0065] In step S1, the iron source is iron powder, and the amount used is based on a phosphorus to iron molar ratio of 1.2:1;

[0066] In step S2, the temperature of the iron-containing immersion liquid is controlled at 90° C. and kept warm for 4 hours, and the crude ferric phosphate and the precipitated ferric phosphate liquid are obtained by filtration.

[0067] In step S3, crude ferric phosphate is prepared according to the molar ratio of Fe 3+ :OH - =1:4 for alkaline dissolution.

[0068] The aluminum recovery rate obtained in this embodiment is 88.7%, the phosphorus recovery rate is 89.1%, and the lithium recovery rate is 97.1%.

[0069] Product quality: Sodium phosphate purity: 97.85%, aluminum hydroxide purity: 92.6%, lithium carbonate purity: 99.9%.

[0070] Example 5

[0071] A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from a nitric acid leaching solution of lithium aluminum phosphate ore is implemented using the method of Example 1, except that:

[0072] In step S2, the temperature of the iron-containing immersion liquid is controlled at 120° C. and kept warm for 10 hours, and the crude ferric phosphate and the precipitated ferric phosphate liquid are obtained by filtration.

[0073] In step S3, crude ferric phosphate is prepared according to the molar ratio of Fe 3+ :OH - =1:4 for alkali dissolution, control the alkali dissolution temperature at 60℃, and the liquid-to-solid ratio at 15:1.

[0074] The aluminum recovery rate obtained in this embodiment is 80.7%, the phosphorus recovery rate is 95.1%, and the lithium recovery rate is 98.1%.

[0075] Product quality: Sodium phosphate purity: 97.15%, aluminum hydroxide purity: 94.6%, lithium carbonate purity: 99.8%.

[0076] Comparative Example 1

[0077] A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from a nitric acid leaching solution of lithium aluminum phosphate ore is implemented using the method of Example 1, except that:

[0078] In step S1, the iron source is an iron source, and the amount used is based on a phosphorus to iron molar ratio of 1.5:1;

[0079] In step S3, crude ferric phosphate is prepared according to the molar ratio of Fe3+ :OH - =1:5 for alkali dissolution, and control the solid ratio of the alkali solution to be 20:1.

[0080] The aluminum recovery rate obtained in this embodiment is 82.4%, the phosphorus recovery rate is 50.7%, and the lithium recovery rate is 79.4%.

[0081] Product quality: Sodium phosphate purity: 96.25%, aluminum hydroxide purity: 57.1%, lithium carbonate purity: 99.73%.

[0082] The phosphorus-iron molar ratio in this comparative example is higher than that in Example 1. The iron content in the solution is too low, and a large amount of phosphorus cannot be precipitated as crude ferric phosphate, resulting in a low phosphorus recovery rate. Furthermore, a large amount of phosphorus remains in the solution after ferric phosphate precipitation, causing aluminum to form insoluble matter with the residual phosphorus during aluminum precipitation, and carrying away a large amount of lithium, resulting in reduced aluminum hydroxide purity and a reduced lithium recovery rate.

[0083] Comparative Example 2

[0084] A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from a nitric acid leaching solution of lithium aluminum phosphate ore is implemented using the method of Example 1, except that:

[0085] In step S2, the temperature of the iron-containing immersion liquid is controlled at 30° C. and kept warm for 6 hours, and the crude ferric phosphate and the precipitated ferric phosphate liquid are obtained by filtration.

[0086] In step S4, the sodium phosphate solution is evaporated and crystallized until the sodium content in the mother liquor is 300 g / L, and then cooled to room temperature and filtered to obtain the product sodium phosphate.

[0087] In step S5, the pH of the ferric phosphate precipitation solution obtained in step S2 is adjusted to 6 by adding sodium hydroxide at room temperature, and the solution is filtered after reacting for 1 hour to obtain aluminum hydroxide and the aluminum hydroxide precipitation solution.

[0088] The aluminum recovery rate obtained in this embodiment is 64.4%, the phosphorus recovery rate is 45.6%, and the lithium recovery rate is 96.4%.

[0089] Product quality: Sodium phosphate purity: 70.89%, aluminum hydroxide purity: 67.4%, lithium carbonate purity: 78.4%.

[0090] The iron dissolution temperature in this comparative example was lower than that in Example 1, resulting in a large amount of phosphorus not being precipitated as ferric phosphate, reducing the phosphorus recovery rate. Furthermore, the sodium content at the evaporation crystallization endpoint was higher than that in Example 1, resulting in a reduction in the purity of the sodium phosphate. The adjusted pH of the solution after ferric phosphate precipitation was lower than that in Example 1, resulting in incomplete aluminum precipitation, reducing the aluminum recovery rate and the purity of lithium carbonate. Furthermore, the excessively high phosphorus and iron contents reduced the purity of the aluminum hydroxide product.

[0091] Comparative Example 3

[0092] A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from a nitric acid leaching solution of lithium aluminum phosphate ore is implemented using the method of Example 1, except that:

[0093] In step S2, the iron-containing leaching liquid is used to precipitate crude ferric phosphate and the temperature is kept for 1 hour, and the crude ferric phosphate and the precipitated ferric phosphate liquid are obtained by filtration.

[0094] In step S3, crude ferric phosphate is prepared according to the molar ratio of Fe 3+ :OH - =1:3 for alkali dissolution, the liquid-to-solid ratio is 4:1.

[0095] The aluminum recovery rate obtained in this embodiment is 67.4%, the phosphorus recovery rate is 39.6%, and the lithium recovery rate is 50.4%.

[0096] Product quality: Sodium phosphate purity: 96.88%, aluminum hydroxide purity: 59.4%, lithium carbonate purity: 93.4%.

[0097] The crude ferric phosphate precipitation time in this comparative example was shorter than that in Example 1, resulting in incomplete precipitation of the crude ferric phosphate. Large amounts of phosphorus and iron were present in the solution after precipitation, reducing the phosphorus recovery rate and the purity of the aluminum hydroxide product. Furthermore, the solids ratio of the crude ferric phosphate alkaline solution was lower than that in Example 1, making it difficult to completely dissolve the crude ferric phosphate, reducing the phosphorus recovery rate. A large amount of lithium was removed by the ferric hydroxide and aluminum-phosphorus compounds during aluminum precipitation, affecting the lithium recovery rate.

[0098] It can be seen from the above embodiments and comparative examples that the embodiment scheme of the present invention can more efficiently separate phosphorus, aluminum and lithium, and obtain better yields of phosphorus, aluminum and lithium, while the comparative examples outside the scope of the present invention cannot achieve the significantly improved effect of the present invention.

[0099] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium-aluminum phosphate ore, characterized in that: The following steps are involved: S1, adding an iron source to the nitric acid leaching solution of lithium aluminum phosphate, dissolving and filtering to obtain an iron-containing leaching solution and an insoluble slag; S2, heating, precipitating and filtering the iron-containing leaching solution obtained in step S1 in sequence to obtain crude iron phosphate and a solution after precipitation of iron phosphate; S3, subjecting the crude ferric phosphate obtained in step S2 to alkaline dissolution and filtration to obtain a sodium phosphate solution and ferric hydroxide; S4, crystallizing the sodium phosphate solution obtained in step S3 to obtain a sodium phosphate product; S5, chemically precipitating the ferric phosphate precipitation liquid obtained in step S2 to obtain an aluminum hydroxide product and an aluminum hydroxide precipitation liquid; S6. The liquid after precipitation of aluminum hydroxide obtained in step S5 is subjected to impurity removal and lithium precipitation in sequence to obtain battery-grade lithium carbonate.

2. The comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium aluminum phosphate according to claim 1, characterized in that: In step S1, the chemical composition of the nitric acid leaching solution includes: Li: 6.5~8g / L, Na: 0.1~0.3g / L, Fe: 0.3~0.8g / L, Al: 25~30g / L, Mn: 0.05~1g / L, Ca: 0.01~0.05g / L, Mg: 0.1~0.15g / L, Si: 0.01~0.05g / L, P: 25~30g / L, K: 0.2~0.5g / L, H + : 3~4mol / L.

3. The comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium aluminum phosphate according to claim 1, characterized in that: In step S1, the iron source is an acid-soluble iron-containing substance, selected from at least one of reducing iron powder, iron oxide, and iron hydroxide; the amount of the iron source is determined according to the phosphorus-iron molar ratio of (0.8~1.2):

1.

4. The comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium aluminum phosphate according to claim 1, characterized in that: In step S2, the reaction temperature is controlled at 60-120° C., and the reaction time is controlled at 4-10 h to obtain crude iron phosphate.

5. The comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium aluminum phosphate according to claim 1, characterized in that: In step S3, the alkali used is a sodium hydroxide solution, and its amount is determined according to the molar amount of iron in the ferric phosphate to be dissolved, and the molar amount of sodium hydroxide is 2 to 4 times the molar amount of iron.

6. The comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium-aluminum phosphate according to claim 5, characterized in that: In step S3, the liquid-to-solid mass ratio in the alkali dissolution process is 5:1-15:1, the alkali dissolution temperature is room temperature-80°C, the dissolution time is 1-1.5h, and the iron hydroxide obtained by the dissolution reaction is returned to step S1 for use.

7. The comprehensive recovery method for preparing sodium phosphate and aluminum and lithium from nitric acid leachate of lithium aluminum phosphate according to claim 1, characterized in that: In step S4, the crystalline sodium phosphate is first concentrated by evaporation and then naturally cooled for crystallization, and the end point of the crystallization is when the temperature drops to room temperature.

8. The method for preparing sodium phosphate and comprehensive recovery of aluminum and lithium from nitric acid leachate of lithium aluminum phosphate according to claim 7, characterized in that: In step S4, the sodium content in the evaporation concentration crystallization end point liquid is 120-250 g / L, and the crystallization mother liquor is returned to step S3 for alkali preparation.

9. The method for preparing sodium phosphate and comprehensive recovery of aluminum and lithium from nitric acid leachate of lithium aluminum phosphate according to claim 1, characterized in that: In step S5, the solution after precipitation of iron phosphate is adjusted to pH 7 by adding sodium hydroxide at room temperature, and reacted for 1 to 1.5 hours to prepare aluminum hydroxide.

10. The method for preparing sodium phosphate and comprehensive recovery of aluminum and lithium from nitric acid leachate of lithium aluminum phosphate according to claim 1, characterized in that: In step S6, sodium hydroxide is added to the liquid after aluminum hydroxide precipitation to adjust the pH to 12, and then filtered to remove trace impurities, and then a 30% by mass sodium carbonate solution is added to the filtrate to obtain battery-grade lithium carbonate, and the lithium precipitation mother liquor is returned to S3 for alkali preparation.

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