Lithium extraction method for low-grade lithium ore

Abstract

The invention provides a lithium extraction method for low-grade lithium ore. The lithium extraction method comprises the following steps: (1) mixing low-grade lithium ore, sulfate and disulfate, and roasting to obtain a raw material; and (2) the raw material is subjected to water leaching, and a lithium-containing leaching solution is obtained. According to the method, the bisulfate and the sulfate are adopted as the lithium extraction auxiliary materials to be roasted together with the low-grade lithium ore, and no acid or water is needed, so that corrosion of acid mist formed in the roasting stage to equipment is avoided, meanwhile, the lithium-containing leachate can have relatively low acidity, and the cost of the subsequent lithium extraction process is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium extraction and relates to a method for extracting lithium from low-grade lithium ore. Background Art

[0002] Lithium and its compounds are widely used in emerging fields such as medicine, aerospace, and new energy vehicles, and are indispensable raw materials for modern high-tech industries. In recent years, the supply and demand of the lithium resource market has undergone new changes. The main lithium battery products are in short supply, and there is a shortage of lithium resources. The potential reserves of clay-type lithium mines in central Yunnan are 4.89 million tons. The ore layer is thin and easy to develop, which can effectively improve the current shortage of lithium resources and promote the development of new energy industries.

[0003] Since the lithium ion grade in clay-type lithium ore is extremely low, the traditional methods for extracting high-grade lithium ore are not applicable, and researchers have also proposed many strategies. Chinese patent CN114892024A discloses a method for extracting lithium from lithium-containing clay by low-temperature roasting. The invention mixes 98% sulfuric acid with lithium-containing clay and then roasts it. The lithium leaching rate is 89.32%, but the resulting leachate is highly acidic, and subsequent lithium extraction and impurity removal requires a large amount of alkali, and the lithium extraction process is costly.

[0004] Therefore, there is an urgent need to provide a method for extracting lithium ions from lithium ore with extremely low lithium grade, which can reduce the acidity of the leaching solution and reduce the cost of subsequent lithium extraction processes. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for extracting lithium from low-grade lithium ore. The present invention uses hydrogen sulfate and sulfate as auxiliary materials for lithium extraction and roasts them together with low-grade lithium ore without the participation of acid and water, thereby avoiding the corrosion of the equipment by the acid mist formed in the roasting stage, and at the same time, the lithium-containing leaching solution can have lower acidity, thereby reducing the cost of subsequent lithium extraction processes. The process is simple, the lithium leaching rate is high, the roasting temperature is low, the energy consumption is small, and the equipment investment is low.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for extracting lithium from a low-grade lithium ore, the method comprising:

[0008] (1) mixing low-grade lithium ore, sulfate and hydrogen sulfate, and roasting to obtain raw material;

[0009] (2) The raw material is immersed in water to obtain a lithium-containing leaching solution.

[0010] The invention provides a method for extracting lithium from a low-grade lithium ore. Hydrogen sulfate and sulfate are used as auxiliary materials for lithium extraction and roasted together with the low-grade lithium ore. Then, the raw material obtained after roasting is subjected to water leaching, so that lithium ions can be extracted from the low-grade lithium ore. The method has a high lithium leaching rate, and the water leaching method can reduce the dissolution rate of impurity ions. The subsequent impurity removal step is relatively simple, and the equipment investment cost is relatively low, which is conducive to practical application. During the roasting process, the hydrogen sulfate and the sulfate will become a molten state and perform a lithium exchange reaction with the low-grade lithium ore. Since the hydrogen sulfate has a lower melting point, the mixed salt of the hydrogen sulfate and the sulfate can become a molten state at a lower temperature, thereby reducing the roasting cost and low energy consumption. In addition, the invention adopts hydrogen sulfate and sulfate as auxiliary materials for lithium extraction, and does not require the participation of acid and water, thereby avoiding the corrosion of the equipment by the acid mist formed in the roasting stage, and at the same time, the lithium-containing leaching solution can have a lower acidity, thereby reducing the subsequent lithium extraction process cost.

[0011] Preferably, the low-grade lithium ore includes clay-type lithium ore.

[0012] Preferably, the sulfate includes at least one of sodium sulfate, potassium sulfate, calcium sulfate and ammonium sulfate.

[0013] Preferably, the bisulfate salt includes at least one of sodium bisulfate, potassium bisulfate, calcium bisulfate and ammonium bisulfate.

[0014] Preferably, the mass ratio of the bisulfate to the sulfate is (0.05-0.5):(0.1-0.5), wherein the selection range of bisulfate (0.05-0.5) can be, for example, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5, etc., and the selection range of sulfate (0.1-0.5) can be, for example, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably (0.1-0.3):(0.1-0.4).

[0015] In the present invention, if the mass ratio of hydrogen sulfate to sulfate is too small, the lithium leaching rate is reduced; if the mass ratio of hydrogen sulfate to sulfate is too large, the impurity content in the leachate increases, and the subsequent impurity removal cost increases.

[0016] Preferably, the ratio of the total mass of the bisulfate and the sulfate to the mass of the low-grade lithium ore is (0.15-1):1, for example, it can be 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1 or 1:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably (0.2-0.7):1.

[0017] In the present invention, if the ratio of the total mass of hydrogen sulfate and sulfate to the mass of low-grade lithium ore is too small, the lithium leaching rate decreases; if the ratio of the total mass of hydrogen sulfate and sulfate to the mass of low-grade lithium ore is too large, the relative cost increases and the impurity content of the leachate increases.

[0018] Preferably, in step (1), a crushing step is further performed between the mixing and the roasting.

[0019] In the present invention, the low-grade lithium ore, sulfate and hydrogen sulfate can be mixed uniformly through the crushing step.

[0020] Preferably, taking the total mass of the crushed products obtained by the crushing as 100%, the mass proportion of particles with a particle size of -200 mesh in the crushed products is 50%-95%, for example, it can be 50%, 52%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 70%-95%.

[0021] In the present invention, if the mass proportion of particles with a particle size of -200 mesh in the crushed product is too small, the lithium leaching rate will decrease; if the mass proportion of particles with a particle size of -200 mesh in the crushed product is too large, although the lithium leaching rate can be improved to a certain extent, the corresponding impurity content will increase, and the energy consumption will be large, and the cost will be high.

[0022] Preferably, the calcination temperature is 350°C-750°C, for example, it can be 350°C, 380°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C or 750°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 400°C-650°C.

[0023] In the present invention, hydrogen sulfate and sulfate are used as auxiliary materials for lithium extraction, and the melting of salt and the exchange reaction with lithium can be achieved at a relatively low roasting temperature (350°C-750°C). Furthermore, the hydrogen sulfate and sulfate used in the present invention can achieve the exchange reaction with lithium at 650°C or below.

[0024] Preferably, the calcination time is 0.5h-6h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 1h-3h.

[0025] Preferably, the mass ratio of the raw material to the water used for soaking is 1:(0.5-5), for example, it can be 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 1:(0.8-3).

[0026] Preferably, the water immersion temperature is 25°C-95°C, for example, it can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C or 95°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 50°C-90°C.

[0027] Preferably, the immersion time is 0.08h-6h, for example, it can be 0.08h, 0.1h, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 0.08h-1h.

[0028] As a preferred technical solution of the present invention, the lithium extraction method comprises the following steps:

[0029] (I) mixing low-grade lithium ore, sulfate and hydrogen sulfate, crushing the obtained mixture, and then roasting the obtained crushed product at a temperature of 350° C. to 750° C. for 0.5 h to 6 h, and cooling the temperature to ≤100° C. (for example, 100° C., 90° C., 80° C., 60° C. or 50° C.) after the roasting is completed to obtain a raw material;

[0030] Wherein, the low-grade lithium ore is a clay-type lithium ore; the sulfate includes at least one of sodium sulfate, potassium sulfate, calcium sulfate and ammonium sulfate; the bisulfate includes at least one of sodium bisulfate, potassium bisulfate, calcium bisulfate and ammonium bisulfate; the mass ratio of the bisulfate to the sulfate is (0.05-0.5):(0.1-0.5); the ratio of the total mass of the bisulfate and the sulfate to the mass of the low-grade lithium ore is (0.15-1):1; taking the total mass of the crushed product as 100%, the mass proportion of particles with a particle size of -200 mesh in the crushed product is 50%-95%;

[0031] (II) soaking the raw material in water for 0.08 h to 6 h at a temperature of 25° C. to 95° C., and then performing solid-liquid separation to obtain a lithium-containing leachate;

[0032] Wherein, the mass ratio of the raw material to the water used for water immersion is 1:(0.5-5).

[0033] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The invention provides a method for extracting lithium from a low-grade lithium ore. Hydrogen sulfate and sulfate are used as auxiliary materials for lithium extraction and roasted together with the low-grade lithium ore. Then, the raw material obtained after roasting is subjected to water leaching, so that lithium ions can be extracted from the low-grade lithium ore. The method has a high lithium leaching rate, and the water leaching method can reduce the dissolution rate of impurity ions. The subsequent impurity removal step is relatively simple, and the equipment investment cost is relatively low, which is conducive to practical application. During the roasting process, the hydrogen sulfate and the sulfate will become a molten state and perform a lithium exchange reaction with the low-grade lithium ore. Since the hydrogen sulfate has a lower melting point, the mixed salt of the hydrogen sulfate and the sulfate can become a molten state at a lower temperature, thereby reducing the roasting cost and low energy consumption. In addition, the invention adopts hydrogen sulfate and sulfate as auxiliary materials for lithium extraction, and does not require the participation of acid and water, thereby avoiding the corrosion of the equipment by the acid mist formed in the roasting stage, and at the same time, the lithium-containing leaching solution can have a lower acidity, thereby reducing the subsequent lithium extraction process cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of a process for extracting lithium from low-grade lithium ore provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In one embodiment, the present invention provides a method for extracting lithium from low-grade lithium ore, the process is as follows: Figure 1As shown, the low-grade lithium ore is a clay-type lithium ore, and the lithium extraction method specifically includes:

[0038] The clay-type lithium ore, hydrogen sulfate and sulfate are mixed, and then the obtained mixture is mechanically crushed, the mechanically crushed product is high-temperature roasted, and then the high-temperature roasted product is water-leached to obtain lithium-containing leaching solution and leaching residue.

[0039] Example 1

[0040] This embodiment provides a method for extracting lithium from a low-grade lithium ore, and the method specifically comprises:

[0041] (1) mixing ammonium bisulfate, ammonium sulfate and clay-type lithium ore, wherein the mass ratio of ammonium bisulfate to ammonium sulfate is 0.2:0.2, and the ratio of the total mass of ammonium bisulfate and ammonium sulfate to the mass of clay-type lithium ore is 0.4:1, and then crushing the obtained mixture to obtain a crushed product, wherein the total mass of the crushed product is 100%, the mass of particles with a particle size of -200 mesh in the crushed product accounts for 80%;

[0042] (2) roasting the crushed product at 600° C. for 1.5 h, and cooling the temperature to 80° C. to obtain a raw material;

[0043] (3) The raw material is immersed in water at a temperature of 60° C. for 1 hour, wherein the mass ratio of the raw material to the water used for immersion is 1:3, and then filtered to obtain a lithium-containing leaching solution.

[0044] Test: The lithium ion content and impurity ion content in the lithium-containing leachate are detected by inductively coupled plasma spectrometer (ICP), where the impurity ions are calcium, magnesium, iron and aluminum ions.

[0045] According to the test results, it was calculated that the lithium leaching rate of this embodiment was 86.67%, and the impurity ion leaching rate was 0.52%.

[0046] Example 2

[0047] This embodiment provides a method for extracting lithium from a low-grade lithium ore, and the method specifically comprises:

[0048] (1) mixing potassium hydrogen sulfate, ammonium sulfate and clay-type lithium ore, wherein the mass ratio of potassium hydrogen sulfate to ammonium sulfate is 0.1:0.4, and the ratio of the total mass of potassium hydrogen sulfate and ammonium sulfate to the mass of the clay-type lithium ore is 0.5:1, and then crushing the obtained mixture to obtain a crushed product, wherein the total mass of the crushed product is 100%, the mass of particles with a particle size of -200 mesh in the crushed product accounts for 70%;

[0049] (2) roasting the crushed product at 650° C. for 2 h, and cooling the temperature to 80° C. after roasting to obtain a raw material;

[0050] (3) The raw material is immersed in water at a temperature of 90° C. for 0.8 h, wherein the mass ratio of the raw material to the water used for immersion is 1:2, and then filtered to obtain a lithium-containing leaching solution.

[0051] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 85.98%, and the impurity ion leaching rate was 0.44%.

[0052] Example 3

[0053] This embodiment provides a method for extracting lithium from a low-grade lithium ore, and the method specifically comprises:

[0054] (1) mixing calcium hydrogen sulfate, calcium sulfate and clay-type lithium ore, wherein the mass ratio of calcium hydrogen sulfate to calcium sulfate is 0.3:0.1, and the ratio of the total mass of calcium hydrogen sulfate and calcium sulfate to the mass of the clay-type lithium ore is 0.4:1, and then crushing the obtained mixture to obtain a crushed product, wherein the total mass of the crushed product is 100%, the mass of particles with a particle size of -200 mesh in the crushed product accounts for 90%;

[0055] (2) roasting the crushed product at 500° C. for 3 h, and cooling the temperature to 80° C. to obtain a raw material;

[0056] (3) The raw material is immersed in water at a temperature of 40° C. for 1.5 hours, wherein the mass ratio of the raw material to the water used for the immersion is 1:2.5, and then filtered to obtain a lithium-containing leaching solution.

[0057] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 89.09%, and the impurity ion leaching rate was 0.57%.

[0058] It can be seen from Examples 1-3 that the present invention uses bisulfate and sulfate as auxiliary materials for lithium extraction, and roasts low-grade lithium ore (i.e., clay-type lithium ore) at a relatively low temperature, so that lithium ions can be extracted from low-grade lithium ore, with a relatively high lithium leaching rate of more than 85%, and the water leaching method for lithium extraction can reduce the dissolution rate of impurity ions, and the impurity ion leaching rate is less than 0.6%.

[0059] Example 4

[0060] The difference between this embodiment and embodiment 1 is that the mass ratio of ammonium bisulfate to ammonium sulfate is 0.03:0.5.

[0061] The remaining parameters remain the same as those in Example 1.

[0062] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 81.27%, and the impurity ion leaching rate was 0.41%.

[0063] Example 5

[0064] The difference between this embodiment and embodiment 1 is that the mass ratio of ammonium bisulfate to ammonium sulfate is 0.55:0.1.

[0065] The remaining parameters remain the same as those in Example 1.

[0066] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 90.14%, and the impurity ion leaching rate was 0.68%.

[0067] It can be seen from Examples 1 and 4-5 that if the mass ratio of bisulfate to sulfate is too small, the lithium leaching rate decreases; if the mass ratio of bisulfate to sulfate is too large, the impurity content in the leachate increases and the subsequent impurity removal cost increases.

[0068] Example 6

[0069] The difference between this embodiment and embodiment 1 is that the ratio of the total mass of ammonium bisulfate and ammonium sulfate to the mass of clay-type lithium ore is 0.1:1.

[0070] The remaining parameters remain the same as those in Example 1.

[0071] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 69.06%, and the impurity ion leaching rate was 0.32%.

[0072] Example 7

[0073] The difference between this embodiment and embodiment 1 is that the ratio of the total mass of ammonium bisulfate and ammonium sulfate to the mass of clay-type lithium ore is 1.1:1.

[0074] The remaining parameters remain the same as those in Example 1.

[0075] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 92.03%, and the impurity ion leaching rate was 0.87%.

[0076] It can be seen from Examples 1 and 6-7 that if the ratio of the total mass of bisulfate and sulfate to the mass of low-grade lithium ore is too small, the lithium leaching rate decreases; if the ratio of the total mass of bisulfate and sulfate to the mass of low-grade lithium ore is too large, the relative cost increases and the impurity content of the leachate increases.

[0077] Example 8

[0078] The difference between this embodiment and embodiment 1 is that the mass proportion of particles with a particle size of -200 mesh in the crushed product is 45%.

[0079] The remaining parameters remain the same as those in Example 1.

[0080] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 79.08%, and the impurity ion leaching rate was 0.39%.

[0081] Example 9

[0082] The difference between this embodiment and embodiment 1 is that the mass proportion of particles with a particle size of -200 mesh in the crushed product is 98%.

[0083] The remaining parameters remain the same as those in Example 1.

[0084] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 87.52%, and the impurity ion leaching rate was 0.54%.

[0085] It can be seen from Example 1 and Examples 8-9 that if the mass proportion of particles with a particle size of -200 mesh in the crushed product is too small, the lithium leaching rate will decrease; if the mass proportion of particles with a particle size of -200 mesh in the crushed product is too large, although the lithium leaching rate can be improved to a certain extent, the corresponding impurity content will increase, and the energy consumption will be large, and the cost will be high.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 1 is that the mass of ammonium bisulfate is replaced by ammonium sulfate.

[0088] The remaining parameters remain the same as those in Example 1.

[0089] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 81.05%, and the impurity ion leaching rate was 0.46%.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Example 1 is that the mass of ammonium sulfate is replaced by ammonium bisulfate.

[0092] The remaining parameters remain the same as those in Example 1.

[0093] The lithium ion and impurity ion contents in the lithium-containing leachate were detected by the same method as in Example 1, wherein the impurity ions were calcium, magnesium, iron and aluminum ions. According to the test results, the lithium leaching rate of this example was 87.21%, and the impurity ion leaching rate was 0.60%.

[0094] It can be seen from Example 1 and Comparative Examples 1-2 that if a single salt, that is, only ammonium sulfate, is used, the lithium leaching rate will be significantly reduced, while only ammonium bisulfate is used to extract lithium, the impurity leaching rate will increase and the impurity removal cost will increase.

[0095] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for extracting lithium from low-grade lithium ore, characterized in that: The lithium extraction method comprises: (1) mixing low-grade lithium ore, sulfate and hydrogen sulfate, and roasting to obtain raw material; (2) The raw material is immersed in water to obtain a lithium-containing leaching solution.

2. The lithium extraction method according to claim 1, characterized in that: The low-grade lithium ore includes clay-type lithium ore.

3. The lithium extraction method according to claim 1 or 2, characterized in that: The sulfate includes at least one of sodium sulfate, potassium sulfate, calcium sulfate and ammonium sulfate.

4. The lithium extraction method according to any one of claims 1 to 3, characterized in that: The bisulfate salt includes at least one of sodium bisulfate, potassium bisulfate, calcium bisulfate and ammonium bisulfate.

5. The lithium extraction method according to any one of claims 1 to 4, characterized in that: The mass ratio of the bisulfate to the sulfate is (0.05-0.5):(0.1-0.5), preferably (0.1-0.3):(0.1-0.4); Preferably, the ratio of the total mass of the bisulfate and the sulfate to the mass of the low-grade lithium ore is (0.15-1):1, preferably (0.2-0.7):

1.

6. The lithium extraction method according to any one of claims 1 to 5, characterized in that: In step (1), between the mixing and the roasting, a crushing step is also performed; Preferably, taking the total mass of the crushed products obtained by the crushing as 100%, the mass proportion of particles with a particle size of -200 mesh in the crushed products is 50%-95%, preferably 70%-95%.

7. The lithium extraction method according to any one of claims 1 to 6, characterized in that: The calcination temperature is 350°C-750°C, preferably 400°C-650°C; Preferably, the calcination time is 0.5h-6h, preferably 1h-3h.

8. The lithium extraction method according to any one of claims 1 to 7, characterized in that: The mass ratio of the raw material to the water used for water immersion is 1:(0.5-5), preferably 1:(0.8-3).

9. The lithium extraction method according to any one of claims 1 to 8, characterized in that: The water immersion temperature is 25°C-95°C, preferably 50°C-90°C; Preferably, the immersion time is 0.08h-6h, preferably 0.08h-1h.

10. The lithium extraction method according to any one of claims 1 to 9, characterized in that: The lithium extraction method comprises the following steps: (I) mixing low-grade lithium ore, sulfate and hydrogen sulfate, crushing the obtained mixture, and then roasting the obtained crushed product at a temperature of 350° C. to 750° C. for 0.5 h to 6 h, and cooling the temperature to ≤100° C. after the roasting to obtain a raw material; Wherein, the low-grade lithium ore is a clay-type lithium ore; the sulfate includes at least one of sodium sulfate, potassium sulfate, calcium sulfate and ammonium sulfate; the bisulfate includes at least one of sodium bisulfate, potassium bisulfate, calcium bisulfate and ammonium bisulfate; the mass ratio of the bisulfate to the sulfate is (0.05-0.5):(0.1-0.5); the ratio of the total mass of the bisulfate and the sulfate to the mass of the low-grade lithium ore is (0.15-1):1; taking the total mass of the crushed product as 100%, the mass proportion of particles with a particle size of -200 mesh in the crushed product is 50%-95%; (II) soaking the raw material in water for 0.08 h to 6 h at a temperature of 25° C. to 95° C., and then performing solid-liquid separation to obtain a lithium-containing leachate; Wherein, the mass ratio of the raw material to the water used for water immersion is 1:(0.5-5).

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