A method for comprehensively extracting lithium, aluminum and phosphorus resources from beraunite

Abstract

The application discloses a method for comprehensively extracting lithium, aluminum and phosphorus resources from amblygonite. The method comprises the following steps: uniformly mixing the amblygonite with an aluminum sulfate additive, and then roasting to obtain a roasting product; using water or dilute acid to leach the roasting product to obtain a lithium solution and an aluminum-phosphorus residue; using a carbonate to precipitate lithium carbonate after impurity removal of the lithium solution to obtain a lithium carbonate product; using a strong acid to dissolve the aluminum-phosphorus residue, and then removing insoluble substances through solid-liquid separation to obtain an aluminum-phosphorus solution; and performing alkali neutralization and hydrothermal precipitation on the aluminum-phosphorus solution to obtain an aluminum phosphate product. The method can efficiently extract lithium, aluminum and phosphorus resources from the amblygonite, the extraction rate of the lithium resource reaches more than 98%, the utilization rate of the aluminum and phosphorus resources reaches more than 96%, the economic benefits of the amblygonite resource development and utilization are significantly improved, the method is simple in process, green and environmentally friendly, and easy to realize industrial production.

Description

Technical Field

[0001] This invention relates to a method for processing lithium phosphate aluminum ore, specifically a method for comprehensively extracting lithium, aluminum and phosphorus resources from lithium phosphate aluminum ore, belonging to the field of lithium extraction technology from ores. Background Technology

[0002] Lithium is a strategically important metal, hailed as the "white oil" of the 21st century, and is widely used in metallurgy, energy, pharmaceuticals, ceramics, electronics, and other industries. In recent years, with the rapid development of new energy vehicles and chemical energy storage, the demand for lithium in the new energy industry has exploded. Lithium resources mainly include lithium-bearing ores, salt lake brines, and seawater. Lithium-bearing ores include spodumene, lepidolite, and phosphogypsum. Efficient and economical lithium extraction from these resources is crucial for promoting the sustainable development of the new energy industry.

[0003] Lithium aluminum phosphate (LiAlPO4(F,OH)) is a lithium and aluminum fluorophosphate, often containing elements such as Na, K, Rb, Cs, Si, and Ca. The theoretical mass fraction of its mineral Li2O is 10.1%, but in actual minerals, due to the substitution effect of Na and K, the mass fraction of Li2O is 8.0%–9.5%, making it one of the minerals with a relatively high lithium content and extremely high lithium extraction value. Currently, the main methods for extracting lithium from lithium aluminum phosphate include the sulfuric acid method and the alkali dissolution method. The sulfuric acid method is the earliest developed process for lithium extraction from lithium aluminum phosphate, with advantages such as simple process, inexpensive auxiliary materials, and high yield, but it suffers from problems such as becoming a thin paste after adding acid. Besides the sulfuric acid method, researchers have also developed a calcium salt roasting method to extract lithium from lithium phosphate. For example, Chinese patent CN113981244A discloses a method for extracting lithium from lithium phosphate raw materials. This method involves roasting a mixture of calcium carbonate, sodium sulfate, and calcium sulfate with crushed and screened lithium phosphate at high temperature. After leaching, the lithium content in the leaching residue can be reduced to 0.19 wt%, achieving a high lithium recovery rate. However, this patented technology fails to fully recover aluminum and phosphorus from the lithium phosphate, both of which are economically valuable resources in lithium phosphate.

[0004] Therefore, developing an efficient, low-cost, and short-process integrated method for extracting lithium, aluminum, and phosphorus from lithium phosphate aluminum ore is of great significance for the development and utilization of valuable resources in lithium phosphate aluminum ore. Summary of the Invention

[0005] In view of the technical problems existing in the prior art, such as the difficulty in extracting lithium resources from lithium phosphate ore and the difficulty in comprehensively utilizing valuable resources, the purpose of this invention is to provide a method for comprehensively extracting lithium, aluminum and phosphorus resources from lithium phosphate ore. This method has the characteristics of short process and high efficiency in lithium extraction, and can realize the comprehensive and efficient extraction of lithium, aluminum and phosphorus from ore, truly realizing the comprehensive utilization of lithium phosphate ore.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a method for the comprehensive extraction of lithium, aluminum, and phosphorus resources from lithium phosphate rock, the method comprising the following steps:

[0007] 1) After uniformly mixing lithium aluminum phosphate with aluminum sulfate additives, the mixture is calcined to obtain the calcined product.

[0008] 2) The roasted product is leached with water or dilute acid to obtain lithium solution and aluminum-phosphorus filter residue;

[0009] 3) After removing impurities from the lithium solution, lithium carbonate is precipitated using carbonate to obtain the lithium carbonate product;

[0010] 4) The aluminum phosphorus filter residue is dissolved in a strong acid, and the insoluble matter is removed by solid-liquid separation to obtain an aluminum phosphorus solution; the aluminum phosphorus solution is neutralized by alkali and subjected to hydrothermal precipitation to obtain aluminum phosphate product.

[0011] The key to the method for comprehensively extracting lithium, aluminum, and phosphorus resources from lithium phosphate aluminate provided by this invention lies in the use of aluminum sulfate additives to achieve mineral reconstruction of lithium phosphate aluminate at high temperatures. The sulfate ions in the aluminum sulfate additives convert lithium in lithium phosphate aluminate into water-soluble lithium sulfate, while aluminum ions convert phosphate ions into water-insoluble phosphates for effective fixation. This allows for the separation of lithium from phosphorus and aluminum through water leaching or dilute acid leaching. Simultaneously, aluminum ions can convert fluorine in lithium phosphate aluminate into aluminum fluoride. Aluminum fluoride is easily decomposed into hydrogen fluoride and aluminum oxide by water vapor carried in the air or generated during mineral roasting at high temperatures. This allows for the absorption and recovery of hydrogen fluoride from the roasting atmosphere, achieving the separation of fluorine from aluminum and phosphorus. The final aluminum-phosphorus filter residue after lithium and fluorine separation mainly contains aluminum phosphate and silicon dioxide. The soluble nature of aluminum phosphate in high-concentration strong acids further facilitates the separation of aluminum phosphate from silicon dioxide, while aluminum and phosphorus are recovered as aluminum phosphate products. In summary, this method utilizes aluminum sulfate additives to achieve mineral reconstruction of lithium phosphate aluminum ore, thereby separating and comprehensively recovering lithium, fluorine, phosphorus, and aluminum from the lithium phosphate aluminum ore.

[0012] As a preferred embodiment, the aluminum sulfate additive comprises at least one of aluminum sulfate, potassium aluminum sulfate, and sodium aluminum sulfate. The preferred aluminum sulfate additive does not decompose or volatilize at high temperatures, meeting the requirements for high-temperature roasting of lithium phosphate aluminum ore. In particular, the use of aluminum sulfate additives avoids the introduction of a large number of new impurity ions during roasting, and aluminum ions can be fully recovered. The aluminum sulfate additive may also contain other sulfates, such as potassium sulfate and sodium sulfate. The total mass of sodium sulfate and potassium sulfate, etc., does not exceed 1-50% of the mass of the aluminum sulfate additive.

[0013] As a preferred embodiment, the amount of aluminum sulfate additive relative to lithium phosphate aluminum ore is measured to be 1 to 3 times the theoretical molar amount of lithium ions in the lithium phosphate aluminum ore that can be replaced by the cations in the aluminum sulfate additive. In order to completely convert the lithium in the lithium phosphate aluminum ore, the amount of aluminum sulfate additive must be at least the theoretical amount of lithium that can be replaced in the lithium phosphate aluminum ore. According to the characteristics of cation replacement, one aluminum ion can theoretically replace three lithium ions, while one potassium ion or sodium ion can theoretically replace one lithium ion.

[0014] As a preferred embodiment, the calcination conditions are: calcination in air at a temperature of 450–700°C for 0.5–12 hours. The use of aluminum sulfate additives can lower the remodeling temperature of lithium aluminum phosphate. To ensure sufficient reaction between the lithium aluminum phosphate and the aluminum sulfate additives, the calcination temperature cannot be too low, nor can the calcination time be too short. Furthermore, if the calcination temperature is too high, the aluminum sulfate will decompose into sulfur trioxide and aluminum oxide, which is also undesirable.

[0015] As a preferred embodiment, the hydrogen fluoride gas generated during the roasting process is absorbed by an alkaline solution. The concentration of the alkaline solution is generally 2–5 mol / L. Preferred alkaline solutions include common industrial alkalis such as sodium hydroxide and ammonia.

[0016] As a preferred embodiment, the leaching conditions are as follows: using water or a dilute acid with a concentration not exceeding 1 mol / L as the leaching agent, the leaching liquid-to-solid ratio is 5 mL:1 g to 20 mL:1 g, the leaching time is 0.5 h to 6 h, and the leaching temperature is 20 to 80 °C. The concentration of the dilute acid is further preferably 0.1 to 1 mol / L. The dilute acid can be at least one of conventional hydrochloric acid, sulfuric acid, and nitric acid. Appropriately increasing the temperature or extending the leaching time during the leaching process is beneficial for promoting lithium ion leaching and increasing the lithium ion leaching rate, while appropriately increasing the leaching temperature can shorten the leaching time. Compared to water, using dilute acid can accelerate the leaching process. Simultaneously, controlling the leaching liquid-to-solid ratio is advantageous for obtaining a higher lithium concentration leaching solution. If the liquid-to-solid ratio is too high, it is difficult to obtain a high-concentration leaching solution; if the liquid-to-solid ratio is too low, the lithium leaching rate will decrease. Therefore, it is necessary to control an appropriate liquid-to-solid ratio.

[0017] As a preferred embodiment, the conditions for precipitating lithium carbonate are as follows: using a water-soluble carbonate as a precipitant, precipitation is carried out at a temperature of 70–95°C for 1–3 hours. The water-soluble carbonate can be ammonium carbonate, sodium carbonate, etc., and under these preferred conditions, efficient precipitation of lithium carbonate can be achieved.

[0018] As a preferred embodiment, the strong acid is nitric acid and / or hydrochloric acid, and the concentration of the strong acid is 4–16 mol / L. The dissolution time of the aluminum-phosphorus filter residue with the strong acid is 1–6 hours. The main components of the aluminum-phosphorus residue after lithium leaching are aluminum phosphate and silicon dioxide, etc. To recover aluminum and phosphorus resources, it is necessary to achieve effective separation of aluminum phosphate and silicon dioxide. Given that aluminum phosphate is soluble in most concentrated inorganic acids, while silicon dioxide is basically insoluble in inorganic acids except hydrofluoric acid, concentrated acids such as nitric acid and hydrochloric acid are used to achieve the separation of aluminum phosphate from other poorly soluble components.

[0019] As a preferred embodiment, the alkali neutralization controls the pH of the aluminum phosphate solution to be between 4.5 and 6. Sodium hydroxide solution is used to adjust the pH during the alkali neutralization process. The concentration of the sodium hydroxide solution is 0.5–5 mol / L. Controlling the pH of the aluminum phosphate solution within the range of 4.5–6 is primarily to achieve the precipitation and separation of aluminum phosphate, while also preventing the formation of aluminum hydroxide.

[0020] As a preferred embodiment, the hydrothermal reaction is carried out at a temperature of 140–180°C for 6–36 hours. Under these preferred hydrothermal reaction conditions, the high temperature and pressure of the hydrothermal reaction yields aluminum phosphate with a better crystalline form. Conventional heating only produces amorphous colloidal aluminum phosphate hydrate.

[0021] As a preferred embodiment, the lithium ion concentration in the lithium solution is greater than 15 g / L. A lithium-rich solution with a concentration greater than 15 g / L can be used for subsequent deep impurity removal and carbonate precipitation of lithium carbonate. If the lithium ion concentration in the lithium solution is less than 15 g / L, it can be evaporated and concentrated until the lithium concentration is greater than 15 g / L, or it can be returned to the leaching cycle for leaching until the lithium concentration is greater than 15 g / L.

[0022] As a preferred embodiment, the particle size of the lithium aluminum phosphate is 100–300 mesh. To increase the active surface area of ​​the calcination reaction, the lithium aluminum phosphate can be crushed and sieved.

[0023] As a preferred embodiment, the lithium aluminum phosphate and aluminum sulfate additives are mixed by high-energy ball milling or mechanical stirring.

[0024] As a preferred embodiment, the lithium solution is purified by hydrolysis, mainly by alkaline precipitation. By adjusting the pH range of the lithium solution to 6-10, the impurity metal ions in the lithium solution are hydrolyzed and precipitated. The alkali used is at least one of sodium hydroxide and / or ammonia water.

[0025] Compared with existing lithium extraction technologies from lithium phosphate bauxite, the beneficial technical effects of the present invention are as follows:

[0026] (1) This invention targets the mineral composition characteristics of lithium aluminum phosphate and uses additives such as aluminum sulfate and potassium aluminum sulfate to carry out a roasting reaction with lithium aluminum phosphate to reconstruct the minerals of lithium aluminum phosphate. This can completely convert the lithium in lithium aluminum phosphate into soluble lithium salts, and can achieve short-process and deep extraction of lithium, with a lithium extraction rate of over 98%.

[0027] (2) This invention uses additives such as aluminum sulfate and potassium aluminum sulfate, in which aluminum ions and sulfate ions are fully utilized, and the Al in them is also fully utilized. 3+ It can be recycled in the future, and can achieve efficient separation of lithium from aluminum and phosphorus without introducing other impurity ions. It is also conducive to the comprehensive extraction of aluminum and phosphorus resources in the future, and the extraction rate of aluminum and phosphorus can reach more than 96%.

[0028] (3) The lithium leaching solution of the present invention can be recycled, which can effectively increase the lithium concentration in the lithium leaching solution, reduce the energy consumption for concentrating lithium solution, and reduce the production cost of lithium carbonate.

[0029] (4) This invention recovers phosphorus and aluminum from lithium aluminum phosphate in the form of aluminum phosphate product with higher added value, thereby improving economic benefits;

[0030] (5) The entire process of the present invention does not produce toxic or harmful pollutants. The main component of the final filter residue is silicon dioxide. The entire process of comprehensive utilization of phosphorus, lithium and aluminum ore is simple and environmentally friendly. Attached Figure Description

[0031] Figure 1 A flowchart illustrating the principle of comprehensive extraction of lithium, aluminum, and phosphorus resources from phosphate-lithium-aluminate ore.

[0032] Figure 2 The image shows the XRD pattern of filter residue C obtained after leaching the roasted product A in Example 5.

[0033] Figure 3 The graph shows a comparison of the extraction rates of lithium, aluminum, and phosphorus for Examples 1, 2, 3, 4, 5, Comparative Examples 1, 2, and 3. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] The raw materials used in the embodiments of this invention are all phosphate-lithium aluminum ore from a mining area in Africa, and their main components are shown in Table 1:

[0036] Table 1. Main components of lithium phosphate aluminum ore

[0037]

[0038] Example 1

[0039] This embodiment provides a method for the comprehensive extraction of lithium, aluminum, and phosphorus resources from lithium phosphate rock. The principle process flow diagram is shown below. Figure 1 As shown, the specific steps include the following:

[0040] S1. The lithium aluminum phosphate rock was crushed and sieved through a 200-mesh sieve. Then, 50g of lithium aluminum phosphate rock powder was mixed evenly with 19.5g of aluminum sulfate (the amount of aluminum sulfate additive was 1.0 times the theoretical amount of lithium in the ore that its cations could replace, i.e., the Li / Al molar ratio was 3:1). The mixture was then roasted at 700℃ for 2 hours to obtain 67.8g of roasted product A. The roasting flue gas was absorbed by 300mL of 2mol / L sodium hydroxide solution, and the fluoride ion concentration in the absorbent was 5.49g / L.

[0041] S2. The roasted product A was leached with 340 mL of deionized water (liquid-solid ratio of 5:1) at 20 °C for 6 h. After solid-liquid separation, lithium-containing filtrate B and filter residue C with a lithium concentration of 5.78 g / L were obtained. It can be calculated that the lithium leaching rate of lithium aluminum phosphate after roasting with aluminum sulfate additive reached 98.73%.

[0042] S3. Evaporate and concentrate the lithium-containing filtrate B to 108 mL to obtain a lithium-rich solution D with a lithium concentration of 18.21 g / L; adjust the pH of the lithium-rich solution D to 10 using sodium hydroxide solution for deep impurity removal; then use sodium carbonate solution to precipitate lithium from the lithium-rich solution D at 95 °C for 2 h, and obtain 8.32 g of lithium carbonate product after filtration and washing.

[0043] S4. Dissolve the filter residue C obtained in step S2 with 12 mol / L concentrated hydrochloric acid for 3 hours. After solid-liquid separation, obtain a product containing Al. 3+ PO4 3- Filtrate E and filter residue F;

[0044] S5. The pH of filtrate E was adjusted to 4.5 using 5 mol / L sodium hydroxide solution, and then a hydrothermal reaction was carried out at 180℃. After 6 hours of reaction, solid and liquid were separated, and the precipitate was dried to obtain 40.61 g of aluminum phosphate. The comprehensive extraction rates of aluminum and phosphorus in the lithium aluminum phosphate reached 96.68% and 97.59%, respectively.

[0045] Example 2

[0046] This embodiment provides a method for the comprehensive extraction of lithium, aluminum, and phosphorus resources from lithium phosphate rock, including the following steps:

[0047] S1. The lithium aluminum phosphate rock was crushed and sieved through a 100-mesh sieve. 75g of lithium aluminum phosphate rock powder was then mixed evenly with 33.2g of potassium aluminum sulfate additive (the amount of potassium aluminum sulfate additive is 1.0 times the theoretical amount of lithium in the ore that can be replaced by its cations, i.e., the Li / Al / K molar ratio is 4:1:1). The mixture was then roasted at 450℃ for 12h to obtain 105.6g of roasted product A. The roasting flue gas was absorbed by 400mL of 3mol / L sodium hydroxide solution, and the fluoride ion concentration in the absorbent was 6.18g / L.

[0048] S2. The roasted product A was leached with 1056 mL of 0.2 mol / L nitric acid (liquid-solid ratio of 10:1) at 80 °C for 0.5 h. After solid-liquid separation, lithium-containing filtrate B and filter residue C with a lithium concentration of 2.78 g / L were obtained. The lithium extraction rate reached 98.34%.

[0049] S3. Evaporate and concentrate the lithium-containing filtrate B to 155 mL to obtain a lithium-rich solution D with a lithium concentration of 19.01 g / L; adjust the pH of the lithium-rich solution D to 9 with ammonia water for deep impurity removal; then use sodium carbonate solution to precipitate lithium from the lithium-rich solution D at 90 °C for 1.5 h, and obtain 13.31 g of lithium carbonate product after filtration and washing.

[0050] S4. Dissolve the filter residue C obtained in step S2 with 16 mol / L concentrated nitric acid for 1 hour. After solid-liquid separation, obtain a product containing Al. 3+ PO4 3- Filtrate E and filter residue F;

[0051] S5. The pH of filtrate E was adjusted to 6 using 4 mol / L sulfuric acid solution, and then a hydrothermal reaction was carried out at 140℃. After 36 h of reaction, solid and liquid were separated, and the precipitate was dried to obtain 61.84 g of aluminum phosphate. The comprehensive extraction rates of aluminum and phosphorus in the lithium aluminum phosphate reached 98.68% and 98.59%, respectively.

[0052] Example 3

[0053] This embodiment provides a method for the comprehensive extraction of lithium, aluminum, and phosphorus resources from lithium phosphate rock, including the following steps:

[0054] S1. The lithium aluminum phosphate rock was crushed and sieved through a 300-mesh sieve. Then, 75g of lithium aluminum phosphate rock powder was mixed evenly with 14.64g of aluminum sulfate and 18.24g of sodium sulfate (the amount of aluminum sulfate and sodium sulfate additives was 1.0 times the theoretical amount of lithium in the ore that could be replaced by its cations, i.e., the Li / Al / Na molar ratio was 6:1:3). Then, it was roasted at 500℃ for 8 hours to obtain 105.42g of roasted product A. The roasting flue gas was absorbed by 300mL of 3mol / L potassium hydroxide solution, and the fluoride ion concentration in the absorbent was 8.19g / L.

[0055] S2. The roasted product A was leached with 2108 mL of 0.1 mol / L hydrochloric acid (liquid-solid ratio of 20:1) at 60 °C for 1 h. After solid-liquid separation, lithium-containing filtrate B and filter residue C with a lithium concentration of 1.40 g / L were obtained. The lithium extraction rate reached 98.87%.

[0056] S3. Evaporate and concentrate the lithium-containing filtrate B to 145 mL to obtain a lithium-rich solution D with a lithium concentration of 20.39 g / L; adjust the pH of the lithium-rich solution D to 6 with ammonia water for deep impurity removal; then use sodium carbonate solution to precipitate lithium from the lithium-rich solution D at 70 °C for 3 h, and obtain 12.51 g of lithium carbonate product after filtration and washing.

[0057] S4. Dissolve the filter residue C obtained in step S2 with 4 mol / L hydrochloric acid for 6 hours. After solid-liquid separation, obtain a product containing Al. 3+ PO4 3- Filtrate E and filter residue F;

[0058] S5. The pH of filtrate E was adjusted to 5.5 using 0.5 mol / L sodium hydroxide solution, and then a hydrothermal reaction was carried out at 160℃. After 24 h of reaction, solid and liquid were separated, and the precipitate was dried to obtain 60.95 g of aluminum phosphate. The comprehensive extraction rates of aluminum and phosphorus in lithium aluminum phosphate reached 97.21% and 97.33%, respectively.

[0059] Example 4

[0060] This embodiment provides a method for the comprehensive extraction of lithium, aluminum, and phosphorus resources from lithium phosphate rock, including the following steps:

[0061] S1. The lithium aluminum phosphate rock was crushed and sieved through a 200-mesh sieve. Then, 50g of lithium aluminum phosphate rock powder was mixed evenly with 29.28g of aluminum sulfate and 44.69g of potassium sulfate (the amount of aluminum sulfate and potassium sulfate used is 3.0 times the theoretical amount of lithium in the ore that can be replaced by its cations, i.e., the Li / Al / Na molar ratio is 2:1:3). Then, it was roasted at 550℃ for 4h to obtain 122.35g of roasted product A. The roasting flue gas was absorbed by 300mL of 2mol / L potassium hydroxide solution, and the fluoride ion concentration in the absorbent was 5.39g / L.

[0062] S2. The roasted product A was leached with 1835 mL of deionized water (liquid-solid ratio of 15:1) at 50 °C for 0.5 h. After solid-liquid separation, lithium-containing filtrate B and filter residue C with a lithium concentration of 1.07 g / L were obtained. The lithium extraction rate reached 98.66%.

[0063] S3. The lithium-containing filtrate B is recycled to step 2 to leach out the new roasted product A until a lithium-rich solution D with a lithium concentration of 18.99 g / L is obtained. The pH of the lithium-rich solution D is adjusted to 8 with ammonia water for deep impurity removal. Then, lithium is precipitated from the lithium-rich solution D with sodium carbonate solution at 95°C for 3 hours. After filtration and washing, 25.51 g of lithium carbonate product is obtained.

[0064] S4. Dissolve the filter residue C obtained in step S2 with 8 mol / L nitric acid for 5 hours. After solid-liquid separation, obtain a product containing Al. 3+ PO4 3- Filtrate E and filter residue F;

[0065] S5. The pH of filtrate E was adjusted to 5.0 using 3 mol / L sodium hydroxide solution, and then a hydrothermal reaction was carried out at 150℃. After 30 h of reaction, solid and liquid were separated, and the precipitate was dried to obtain 40.32 g of aluminum phosphate. The comprehensive extraction rates of aluminum and phosphorus in lithium aluminum phosphate reached 96.21% and 96.57%, respectively.

[0066] Example 5

[0067] This embodiment provides a method for the comprehensive extraction of lithium, aluminum, and phosphorus resources from lithium phosphate rock, including the following steps:

[0068] S1. The lithium aluminum phosphate rock was crushed and sieved through a 200-mesh sieve. 75g of lithium aluminum phosphate rock powder was then mixed evenly with 85.53g of aluminum sulfate octadecylhydrate additive (the amount of aluminum sulfate additive was 1.5 times the theoretical amount of lithium in the ore that its cations could replace, i.e., the Li / Al molar ratio was 3:2). The mixture was then roasted at 700℃ for 0.5h to obtain 116.4g of roasted product A. The roasting flue gas was absorbed by 500mL of 3mol / L sodium hydroxide solution, and the fluoride ion concentration in the absorbent was 4.89g / L.

[0069] S2. The calcined product A was leached with 1164 mL of 0.5 mol / L sulfuric acid (liquid-solid ratio 10:1) at 50 °C for 1 h. After solid-liquid separation, a lithium-containing filtrate B with a lithium concentration of 2.55 g / L and filter residue C were obtained. The lithium extraction rate reached 99.42%. The XRD pattern of filter residue C is shown below. Figure 2 As shown, from Figure 2 It is known that after roasting and leaching, the filter residue obtained from lithium phosphate aluminum ore mainly consists of aluminum phosphate and silicon dioxide, from which aluminum and phosphorus resources can be further extracted.

[0070] S3. Evaporate and concentrate the lithium-containing filtrate B to a volume of 163 mL to obtain a lithium-rich solution D with a lithium concentration of 18.16 g / L; adjust the pH of the lithium-rich solution D to 8 with sodium hydroxide for deep impurity removal; then use sodium carbonate solution to precipitate lithium from the lithium-rich solution D at 95 °C for 3 h, and obtain 13.31 g of lithium carbonate product after filtration and washing.

[0071] S4. Dissolve the filter residue C obtained in step S2 with 10 mol / L hydrochloric acid for 4 hours. After solid-liquid separation, obtain a product containing Al. 3+ PO4 3- Filtrate E and filter residue F;

[0072] S5. The pH of filtrate E was adjusted to 5.5 using 2 mol / L sodium hydroxide solution, and then a hydrothermal reaction was carried out at 165℃. After 3 hours of reaction, solid and liquid were separated, and the precipitate was dried to obtain 60.32 g of aluminum phosphate. The comprehensive extraction rates of aluminum and phosphorus in lithium aluminum phosphate reached 96.24% and 96.53%, respectively.

[0073] Comparative Example 1

[0074] This comparative example describes the roasting reaction of lithium aluminum phosphate without the aid of additives. First, the lithium aluminum phosphate was crushed and sieved through a 200-mesh sieve. Then, 75g of the lithium aluminum phosphate powder was roasted at 700℃ for 12 hours to obtain 74.8g of roasted product A. Simultaneously, the roasting flue gas was absorbed using 400mL of 3mol / L sodium hydroxide solution, resulting in a fluoride ion concentration of only 0.13g / L in the absorbent. Next, roasted product A was leached with 748mL of deionized water (liquid-to-solid ratio 10:1) at 40℃ for 2 hours. After solid-liquid separation, only a lithium concentration of 0.11g / L was obtained. The lithium extraction rate was only 4.42% in the lithium-containing filtrate B and filter residue C obtained in step S2. Finally, the filter residue C obtained in step S2 was dissolved in 12 mol / L concentrated hydrochloric acid for 6 hours. After solid-liquid separation, filtrate E and filter residue F were obtained. The pH of filtrate E was adjusted to 5.5 with 5 mol / L sodium hydroxide solution, and a hydrothermal reaction was carried out at 160℃. After 24 hours of reaction, solid-liquid separation was performed. After drying the precipitate, only 1.86 g of aluminum phosphate was obtained. The comprehensive extraction rates of aluminum and phosphorus in lithium aluminum phosphate were only 3.14% and 3.28%, respectively.

[0075] Comparative Example 2

[0076] This comparative example describes the low-temperature roasting reaction of lithium aluminum phosphate (LAP) with the aid of additives. First, LAP was crushed and sieved through a 200-mesh sieve. Then, 75g of LAP powder was mixed evenly with 85.53g of aluminum sulfate octahydrate (the amount of aluminum sulfate added was 1.5 times the theoretical amount of lithium that its cations could replace in the ore, i.e., a Li / Al molar ratio of 3:2). The mixture was then roasted at 350℃ for 12 hours to obtain 159.5g of roasted product A. Simultaneously, the roasting flue gas was absorbed using 400mL of 3mol / L sodium hydroxide solution, with a fluoride ion concentration of only 0.011g / L in the absorbent. Next, the roasted product A was rinsed with 1595mL of deionized water (liquid...). The lithium was leached at a solid-liquid ratio of 10:1 and a temperature of 40℃ for 2 hours. After solid-liquid separation, only lithium-containing filtrate B and filter residue C with a lithium concentration of 0.03 g / L were obtained, with a lithium extraction rate of only 1.61%. Finally, the filter residue C obtained in step S2 was dissolved in 12 mol / L concentrated hydrochloric acid for 2 hours. After solid-liquid separation, filtrate E and filter residue F were obtained. The pH of filtrate E was adjusted to 5.5 with 5 mol / L sodium hydroxide solution, and a hydrothermal reaction was carried out at 160℃. After 24 hours of reaction, solid-liquid separation was performed. After drying the precipitate, only 1.01 g of aluminum phosphate was obtained. The comprehensive extraction rates of aluminum and phosphorus in lithium aluminum phosphate were only 1.54% and 1.38%, respectively.

[0077] Comparative Example 3

[0078] This comparative example describes the roasting reaction of lithium aluminum phosphate (LAP) with a small amount of additive. First, LAP was crushed and sieved through a 200-mesh sieve. Then, 75g of LAP powder was mixed evenly with 14.26g of aluminum sulfate octahydrate (the amount of aluminum sulfate added was 0.25 times the theoretical amount of lithium that its cations could replace in the ore, i.e., a Li / Al molar ratio of 12:1). The mixture was then roasted at 700℃ for 12 hours to obtain 82.32g of roasted product A. Simultaneously, the roasting flue gas was absorbed using 500mL of 2mol / L sodium hydroxide solution, with a fluoride ion concentration of only 1.22g / L in the absorbent. Next, roasted product A was rinsed with 823mL of deionized water (liquid-to-solid ratio...). The lithium was extracted at a ratio of 10:1 and a temperature of 40℃ for 2 hours. After solid-liquid separation, lithium-containing filtrate B and filter residue C with a lithium concentration of only 0.88 g / L were obtained, and the lithium extraction rate was only 24.52%. Finally, the filter residue C obtained in step S2 was dissolved in 12 mol / L concentrated hydrochloric acid for 2 hours. After solid-liquid separation, filtrate E and filter residue F were obtained. The pH of filtrate E was adjusted to 5.5 with 5 mol / L sodium hydroxide solution, and a hydrothermal reaction was carried out at 160℃. After 24 hours of reaction, solid-liquid separation was performed. After drying the precipitate, only 14.78 g of aluminum phosphate was obtained. The comprehensive extraction rates of aluminum and phosphorus in lithium aluminum phosphate were only 23.59% and 24.11%, respectively.

[0079] The comparison chart of lithium, aluminum, and phosphorus extraction rates for Examples 1, 2, 3, 4, 5, and Comparative Examples 1, 2, and 3 is shown below. Figure 3 As shown, from Figure 3 It is evident that the method provided by this invention can efficiently and comprehensively extract lithium, phosphorus, and aluminum resources from lithium phosphate aluminum ore, with lithium resource extraction rates exceeding 98% and aluminum and phosphorus resource extraction rates exceeding 96%. Furthermore, the comparative results show that without additives and during low-temperature calcination, the extraction rates of lithium, aluminum, and phosphorus are extremely low; the recovery rates of lithium, aluminum, and phosphorus resources are also low when the amount of additives used is small. This indicates that the excellent effect achieved by the method provided by this invention is the result of the combined effect of various factors.

[0080] 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 variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for the comprehensive extraction of lithium, aluminum, and phosphorus resources from phosphate rock, characterized in that: Includes the following steps: 1) After uniformly mixing lithium aluminum phosphate with aluminum sulfate additives, the mixture is calcined to obtain the calcined product; The aluminum sulfate additives include at least one of aluminum sulfate, potassium aluminum sulfate, and sodium aluminum sulfate; The amount of aluminum sulfate additive relative to lithium phosphate aluminum is measured as 1 to 3 times the theoretical molar amount of lithium ions in lithium phosphate aluminum that can be replaced by the cations in the aluminum sulfate additive. 2) The roasted product is leached with water or dilute acid to obtain lithium solution and aluminum-phosphorus filter residue; 3) After removing impurities from the lithium solution, lithium carbonate is precipitated using carbonate to obtain the lithium carbonate product; 4) The aluminum-phosphorus filter residue is dissolved in a strong acid, and then the insoluble matter is removed by solid-liquid separation to obtain an aluminum-phosphorus solution; The aluminum phosphate solution is neutralized by alkali and subjected to a hydrothermal reaction to obtain aluminum phosphate product.

2. The method for comprehensively extracting lithium, aluminum, and phosphorus resources from phosphate rock according to claim 1, characterized in that: The calcination conditions are: calcination at 450~700℃ for 0.5~12 h.

3. The method for comprehensively extracting lithium, aluminum, and phosphorus resources from phosphate rock according to claim 2, characterized in that: The hydrogen fluoride gas generated during the roasting process is absorbed by an alkaline solution.

4. A method for comprehensively extracting lithium, aluminum, and phosphorus resources from phosphate rock according to claim 1, characterized in that: The leaching conditions are as follows: water or dilute acid with a concentration not exceeding 1 mol / L is used as the leaching agent, the leaching liquid-to-solid ratio is 5 mL:1 g to 20 mL:1 g, the leaching time is 0.5 h to 6 h, and the leaching temperature is 20 to 80 °C.

5. A method for comprehensively extracting lithium, aluminum, and phosphorus resources from phosphate rock according to claim 1, characterized in that: The conditions for precipitating lithium carbonate are as follows: using water-soluble carbonate as a precipitant, precipitation is carried out at a temperature of 70~95 ℃ for 1~3 h.

6. A method for comprehensively extracting lithium, aluminum, and phosphorus resources from phosphate rock according to claim 1, characterized in that: The strong acid is nitric acid and / or hydrochloric acid, and the concentration of the strong acid is 4 to 16 mol / L.

7. The method for comprehensively extracting lithium, aluminum, and phosphorus resources from phosphate rock according to claim 1, characterized in that: The alkali neutralization is used to control the pH of the aluminum phosphorus solution to be between 4.5 and 6.

8. A method for comprehensively extracting lithium, aluminum, and phosphorus resources from phosphate rock according to claim 1, characterized in that: The hydrothermal reaction conditions are: at a temperature of 140~180℃, the reaction time is 6~36 h.

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