Method for extracting lithium through continuous induction suspension cascade roasting of clay type lithium ore-lepidolite-spodumene

Abstract

The invention provides a clay type lithium ore-lepidolite-spodumene continuous induction suspension cascade roasting lithium extraction method, which comprises the following steps: mixing clay type lithium ore and lepidolite concentrate for pelletizing, then mixing with spodumene concentrate to obtain a clay type lithium ore-lepidolite-spodumene mixed material, and carrying out continuous induction suspension cascade roasting on the clay type lithium ore-lepidolite-spodumene mixed material to obtain the clay type lithium ore-lepidolite-spodumene powder. And carrying out gradient high-temperature roasting, low-temperature acidizing roasting and water leaching to obtain a lithium leaching solution. The leaching rate of lithium in the lithium leachate obtained through the lithium extraction method is larger than or equal to 90%, the problem that existing spodumene roasting crystal transformation temperature is high can be effectively solved, meanwhile, the extraction and utilization rate of lepidolite and clay type lithium ore is increased, integrated extraction and utilization of lithium resources are achieved, and the method is simple in process, low in energy consumption, low in cost, easy to industrialize and suitable for industrial production. Good application prospects are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing, and in particular relates to a method for extracting lithium by continuous induced suspension cascade roasting of clay-type lithium ore-lepidolite-spodumene. Background Art

[0002] Lithium is the most active metallic element known and is currently widely used in lithium-ion battery materials, possessing extremely high strategic value. my country is the world's leading producer and consumer of lithium salts, accounting for approximately 77% of global lithium salt production and 68% of global lithium consumption.

[0003] Currently, my country's available lithium resources come from hard rock, brine, and clay types. Spodumene, a representative hard rock type, has a mature process involving high-temperature crystallization roasting, low-temperature sulfuric acid roasting, and water leaching. However, the crystallization roasting process (α-type spodumene to β-type spodumene) requires temperatures ≥1050°C, a high-temperature process that consumes significant energy. Lepidolite, a hard rock type lithium mineral, is primarily a layered silicate mineral. Lithium is extracted from lepidolite industrially through high-temperature roasting and chemical leaching. Currently, the main method is sulfate roasting, which destroys the lepidolite crystal structure and converts the lithium into soluble sulfate, which is then extracted through acid leaching. Furthermore, the lithium grade in lepidolite is lower than that in spodumene, and the roasting process easily produces fluorine-containing compounds. Clay-type lithium ores, due to their low grade and fine particle size, have historically been considered a difficult-to-use lithium resource. Clay-type lithium deposits are constrained by their complex occurrence and difficult extraction processes. Their individual mining and utilization are economically expensive, and large-scale industrial applications are currently unavailable. Therefore, the extraction and utilization of spodumene, lepidolite, and clay-type lithium deposits each have their own advantages and disadvantages, and the effective extraction and utilization of lithium resources remains a pressing challenge.

[0004] In fact, in order to solve the problem of excessive temperature during the crystallization roasting process of spodumene and effectively realize the enrichment and extraction of lepidolite, patent CN116240373A proposes a method for collaborative lithium extraction from spodumene and mica, which mainly uses lepidolite concentrate and the strongly oxidizing halogen retained in the transformation aid for crystallization roasting, aiming to promote the breaking of Al-O and Si-O bonds in the spodumene structure, thereby achieving the purpose of lowering the crystallization temperature of spodumene; patent CN118639032A also discloses an invention for efficient lithium extraction by low-temperature calcination of spodumene and lepidolite with sulfuric acid. The invention uses spodumene concentrate and lepidolite concentrate as raw materials, and the lepidolite concentrate and spodumene concentrate are subjected to high-temperature roasting, and then the high-temperature roasted material is subjected to low-temperature acidification roasting, and finally a lithium leaching rate ≥95% can be obtained, and the amount of smelting slag produced by this method for one ton of lithium carbonate product is reduced by about 50% compared with the traditional sulfate method. In addition, patents CN118600239A, CN118880063A and CN117684019A took clay-type lithium ores as research objects, and used boiling chlorination method, concentrated sulfuric acid roasting method and roasting-sulfate leaching method respectively. The lithium leaching rates all reached 90%, but the treatment objects and methods were relatively single, and the mining efficiency was low.

[0005] Based on the above-mentioned various lithium resource enrichment and utilization methods, in order to solve the high crystallization roasting temperature of spodumene, effectively utilize lepidolite resources and solve the problem of low value of clay-type lithium ore mined alone, the present invention proposes a method for comprehensive lithium extraction by continuous induced suspension cascade roasting of clay-type lithium ore-lepidolite-spodumene. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for extracting lithium by continuous induced suspension cascade roasting of clay-type lithium ore-lepidolite-spodumene, which can effectively solve the problem of high crystallization temperature of the existing spodumene roasting, while improving the extraction utilization rate of lepidolite and clay-type lithium ore, realizing the integrated extraction and utilization of lithium resources. The process of the present invention is simple, energy-consuming, low-cost, easy to industrialize, and has good application prospects.

[0007] To solve the above technical problems, the present invention adopts a technical solution: a method for extracting lithium by continuous induced suspension cascade roasting of clay-type lithium ore-lepidolite-spodumene, comprising the following steps: S1. crushing, grinding and discarding the clay-type lithium ore to remove impurities to obtain a clay-type lithium ore sample; S2, the clay-type lithium ore sample obtained in S1 is evenly mixed with the lepidolite concentrate, and water is added to form balls to obtain clay-type lithium ore and lepidolite concentrate pellets; the clay-type lithium ore and lepidolite concentrate pellets are then mixed with spodumene concentrate to obtain a clay-type lithium ore-lepidolite-spodumene mixed material; S3, the clay-type lithium ore-lepidolite-spodumene mixed material obtained in S2 is subjected to step-by-step high-temperature roasting, firstly carrying out the first stage clay-type lithium ore-lepidolite induction roasting, and then raising the temperature to carry out the second stage spodumene crystal conversion roasting to obtain a high-temperature roasted material; S4, air cooling the high temperature calcined material obtained in S3 to below 80°C, and performing low temperature acidification calcination to obtain an acidified calcined material; S5. Leaching the acidified roasted material obtained in S4 into water to obtain a lithium leaching solution.

[0008] Preferably, the lithium grade of the clay-type lithium ore is 0.1-0.6%, the lithium grade of the lepidolite concentrate is 1.5-4.0%, and the lithium grade of the spodumene concentrate is 5.5-7.5%.

[0009] Preferably, the proportion of particles with a particle size of -0.074 mm in the clay-type lithium ore sample described in S1 is greater than 70%.

[0010] Preferably, the water-adding pelletizing in S2 obtains clay-type lithium ore and lepidolite concentrate pellets having a water content of 7 to 10%, which are then dried at a low temperature of 60 to 80 ° C, and finally obtain clay-type lithium ore and lepidolite concentrate pellets having a particle size of 5 to 10 mm.

[0011] Preferably, the mass ratio of the clay-type lithium ore:lepidolite concentrate:spodumene concentrate in S2 is (0.5~2):(0.5~2):(1~3).

[0012] Preferably, in S3, the high-temperature roasting temperature of the first stage is 700-800° C., and the roasting time is 5-20 min; the high-temperature roasting temperature of the second stage is 800-975° C., and the roasting time is 20-60 min.

[0013] Preferably, the reagent for the low-temperature acidification and roasting in S4 is concentrated sulfuric acid with a mass concentration of 18.4 mol / L, and the amount of concentrated sulfuric acid used is 1.3 to 1.5 times the theoretical acid consumption when all the lithium elements in the clay-type lithium ore, lepidolite concentrate and spodumene concentrate are converted into lithium sulfate.

[0014] Preferably, the calcination temperature in the low-temperature acidification calcination in S4 is 200-300° C., and the calcination time is 10-60 min.

[0015] Preferably, the leaching temperature in the water leaching process in S5 is 20-50°C, the leaching time is 30-60 min, and the liquid-solid ratio is (3-5):1.

[0016] Preferably, the leaching rate of lithium in the lithium leaching solution is ≥90%.

[0017] Compared with the prior art, the present invention has significant technical effects: 1. The present invention uses a step-by-step roasting method to significantly reduce the crystal transformation temperature of spodumene. The roasting temperature is 75-350°C lower than the crystal transformation temperature of single spodumene roasting (including the first high-temperature roasting stage). In addition, the step-by-step roasting is more flexible and has lower energy consumption than single-stage roasting.

[0018] 2. The present invention effectively utilizes the means of "step-by-step induction" to integrate and utilize different lithium mineral resources such as clay-type lithium ore, lepidolite, and spodumene, effectively expanding the scope of lepidolite extraction and utilization, and effectively improving the economic development value of clay-type lithium ore.

[0019] 3. The process of the present invention is simple, with low energy consumption and cost, small amount of sulfuric acid used, and the water immersion method is easy for industrial production, which has good application prospects.

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention discloses a flow chart of continuous induced suspension cascade roasting of clay-type lithium ore-lepidolite-spodumene to extract lithium. DETAILED DESCRIPTION

[0022] The raw material specifications used in the present invention are as follows: The lithium grade (calculated as Li2O) in clay-type lithium ore is 0.1~0.6%; the lithium grade (calculated as Li2O) in lepidolite concentrate is 1.5~4.0%; and the lithium grade (calculated as Li2O) in spodumene concentrate is 5.5~7.5%.

[0023] The mass concentration of concentrated sulfuric acid is 18.4 mol / L, and the dosage is 1.3 to 1.5 times the theoretical acid consumption when all the lithium elements in clay-type lithium ore, lepidolite concentrate and spodumene concentrate are converted into lithium sulfate (based on the test grade of each lithium ore).

[0024] Example 1 This embodiment describes a method for extracting lithium by continuous induced suspension cascade roasting of a clay-type lithium ore, lepidolite, and spodumene. The clay-type lithium ore is a clay-type lithium ore from southwestern Sichuan Province, and its main chemical composition is: Li2O 0.25%, SiO2 24.62%, Al2O3 53.87%, Fe2O3 1.29%, CaO 0.38%, TiO2 0.22%, MgO 0.18%, and K2O 0.04%. The method comprises the following steps: S1. After crushing, grinding and discarding the clay-type lithium ore to remove impurities, a mineral sample with a particle size of -0.074 mm accounting for 70.98% was obtained; S2, the clay-type lithium ore sample obtained in S1 is evenly mixed with the lepidolite concentrate, water is added to form balls to obtain clay-type lithium ore and lepidolite concentrate pellets with a water content of 8%, and then the pellets are low-temperature dried at 80°C to finally obtain clay-type lithium ore and lepidolite concentrate pellets with a particle size of 5.5 mm; the clay-type lithium ore and lepidolite concentrate pellets are then mixed with spodumene concentrate to obtain a clay-type lithium ore-lepidolite-spodumene mixed material; wherein the mass ratio of the clay-type lithium ore, lepidolite concentrate and spodumene concentrate is 1:1:1; S3, the clay type lithium ore-lepidolite-spodumene mixture material obtained by S2 is carried out step high temperature roasting, and in the first stage high temperature roasting, roasting temperature is 750 DEG C, and roasting time is 10 min, and in the second stage high temperature roasting, roasting temperature is 925 DEG C, and roasting time is 45 min, obtains high temperature roasting material; S4, the high temperature roasting material obtained in S3 is air-cooled to below 80 ° C, and 1.3 times of the theoretical calculated amount (based on the detection grade of each lithium ore) of concentrated sulfuric acid is added to carry out low temperature acidification roasting. The temperature of low temperature acidification roasting is 250 ° C, and the roasting time is 30 min to obtain the acidified roasting material; S5. The acidified roasted material obtained in S4 was subjected to water leaching at a water leaching temperature of 25°C, a leaching time of 40 min, a liquid-to-solid ratio of 4:1, and a final lithium leaching rate of 95.42%.

[0025] Example 2 The raw materials and methods were the same as those in Example 1, except that the calcination temperature in the first stage of step S3 was 700°C and the calcination time was 5 min. The final lithium leaching rate was 90.24%, indicating that the lithium leaching effect obtained under low temperature and short time conditions within the appropriate temperature and time range was general.

[0026] Example 3 The raw materials and methods are the same as those in Example 1, except that in step S3, the first-stage roasting temperature is 800°C, the roasting time is 10 min, and the final lithium leaching rate is 96.03%. The reason for the increased lithium leaching rate is that the higher roasting temperature in the first stage can release fluorine from the clay-type lithium ore faster and in a larger amount; at the same time, the fluorine-containing gas in the clay-type lithium ore can effectively destroy the structure in the lepidolite, inducing it to gradually begin to release a large amount of fluorine-containing gas, thereby reducing the subsequent crystallization roasting temperature of spodumene and improving the overall lithium leaching rate.

[0027] Example 4 The raw materials and methods are the same as those in Example 1, except that in step S3, the second-stage roasting temperature is 975°C, the roasting time is 20 min, and the final lithium leaching rate is 99.14%. The reason for the improved lithium leaching rate is that within the suitable roasting temperature range, the roasting effect of lepidolite-clay type lithium ore pellets and spodumene increases with the increase of roasting temperature.

[0028] Example 5 The raw materials and methods are the same as those in Example 1, except that the calcination temperature in the second stage of step S3 is 800°C and the calcination time is 60 min. The final lithium leaching rate is 90.59%, indicating that the lithium leaching effect is good within the appropriate calcination temperature and calcination time range.

[0029] Example 6 This embodiment describes a method for extracting lithium by continuous induced suspension cascade roasting of a clay-type lithium ore, lepidolite, and spodumene. The clay-type lithium ore is a clay-type lithium ore from a location in Guizhou Province, and its main components are: Li2O 0.31%, SiO2 37.86%, Al2O3 43.58%, Fe2O3 1.49%, CaO 0.95%, TiO2 1.81%, MgO 0.44%, K2O 1.59%, and Na2O 0.33%. The method comprises the following steps: S1. After crushing, grinding and discarding the clay-type lithium ore to remove impurities, a mineral sample with a particle size of -0.074 mm accounting for 77.15% was obtained; S2, the clay-type lithium ore sample obtained in S1 is evenly mixed with the lepidolite concentrate, water is added to form balls to obtain clay-type lithium ore and lepidolite concentrate pellets with a water content of 10%, and then the pellets are low-temperature dried at 80°C to finally obtain clay-type lithium ore and lepidolite concentrate pellets with a particle size of 6.7 mm; the clay-type lithium ore and lepidolite concentrate pellets are then mixed with spodumene concentrate to obtain a clay-type lithium ore-lepidolite-spodumene mixed material; wherein the mass ratio of the clay-type lithium ore, lepidolite concentrate and spodumene concentrate is 2:1:2; S3, the clay type lithium ore-lepidolite-spodumene mixture material obtained by S2 is carried out to step high temperature roasting, and in the first stage high temperature roasting, the roasting temperature is 800 DEG C, and the roasting time is 10 min. In the second stage high temperature roasting, the roasting temperature is 950 DEG C, and the roasting time is 30 min, and the high temperature roasting material is obtained; S4, the high temperature roasting material obtained by S3 is air-cooled to below 80 ° C, and 1.5 times of the theoretical calculated amount (based on the detection grade of each lithium ore) of concentrated sulfuric acid is added to carry out low temperature acidification roasting. The temperature of low temperature acidification roasting is 250 ° C, and the roasting time is 40 min to obtain the acidified roasting material; S5. The acidified roasted material obtained in S4 was water-leached at a temperature of 25°C, a leaching time of 40 min, a liquid-to-solid ratio of 5:1, and a final lithium leaching rate of 97.63%.

[0030] Example 7 This embodiment is a method for extracting lithium by continuous induced suspension cascade roasting of a clay-type lithium ore-lepidolite-spodumene. The clay-type lithium ore is a clay-type lithium ore from a foreign country, and its main components are: Li2O 0.89%, SiO2 53.02%, Al2O3 5.77%, Fe2O3 3.57%, CaO 2.95%, MgO 14.05%, K2O 4.21%, and is a typical low-aluminum, high-magnesium volcanic rock-type clay-type lithium ore. The method comprises the following steps: S1. After crushing, grinding and discarding the clay-type lithium ore to remove impurities, a mineral sample with a particle size of -0.074 mm accounting for 80.96% was obtained; S2, the clay-type lithium ore sample obtained in S1 is evenly mixed with the lepidolite concentrate, water is added to form balls to obtain clay-type lithium ore and lepidolite concentrate pellets with a water content of 9%, and then the pellets are low-temperature dried at 70°C to finally obtain clay-type lithium ore and lepidolite concentrate pellets with a particle size of 6.1 mm; the clay-type lithium ore and lepidolite concentrate pellets are then mixed with spodumene concentrate to obtain a clay-type lithium ore-lepidolite-spodumene mixed material; wherein the mass ratio of the clay-type lithium ore, lepidolite concentrate and spodumene concentrate is 2:1:1; S3, the clay type lithium ore-lepidolite-spodumene mixed material obtained by S2 is carried out step high temperature roasting, and in the first stage high temperature roasting, the roasting temperature is 800 DEG C, and the roasting time is 10 min. In the second stage high temperature roasting, the roasting temperature is 925 DEG C, and the roasting time is 30 min, and the high temperature roasting material is obtained; S4, the high temperature roasting material obtained by S3 is air-cooled to below 80 ° C, and 1.5 times of the theoretical calculated amount (based on the detection grade of each lithium ore) of concentrated sulfuric acid is added to carry out low temperature acidification roasting. The temperature of low temperature acidification roasting is 250 ° C, and the roasting time is 60 min to obtain the acidified roasting material; S5. The acidified roasted material obtained in S4 was water-leached at a water leaching temperature of 25°C, a leaching time of 40 min, a liquid-to-solid ratio of 3.5:1, and a final lithium leaching rate of 95.63%.

[0031] Example 8 The raw materials and method were the same as those in Example 7, except that the temperature of the low-temperature acidification roasting in step S4 was 200°C, the roasting time was 60 min, and the final lithium leaching rate was 91.22%.

[0032] Example 9 The raw materials and method were the same as those in Example 7, except that the temperature of the low-temperature acidification calcination in step S4 was 300°C, the calcination time was 10 min, and the final lithium leaching rate was 90.97%.

[0033] Example 10 This embodiment describes a method for extracting lithium by continuous induced suspension cascade roasting of a clay-type lithium ore, lepidolite, and spodumene. The clay-type lithium ore is a clay-type lithium ore from a location in Yunnan Province, and its main chemical composition is: Li2O 0.28%, SiO2 39.68%, Al2O3 41.53%, Fe2O3 4.32%, CaO 0.36%, MgO 0.31%, and K2O 0.13%. The method comprises the following steps: S1. Clay-type lithium ore is crushed, ground, and discarded to remove impurities, obtaining an ore sample with a particle size of -0.074 mm, accounting for 89.75%; S2, the clay-type lithium ore sample obtained in S1 is evenly mixed with the lepidolite concentrate, water is added to form balls to obtain clay-type lithium ore and lepidolite concentrate pellets with a water content of 7%, and then the pellets are low-temperature dried at 60°C to finally obtain clay-type lithium ore and lepidolite concentrate pellets with a particle size of 5.5 mm; the clay-type lithium ore and lepidolite concentrate pellets are then mixed with spodumene concentrate to obtain a clay-type lithium ore-lepidolite-spodumene mixed material; wherein the mass ratio of the clay-type lithium ore, lepidolite concentrate and spodumene concentrate is 2:2:1; S3, the clay type lithium ore-lepidolite-spodumene mixed material obtained by S2 is carried out step high temperature roasting, and in the first stage high temperature roasting, the roasting temperature is 775 ℃, and the roasting time is 20 min, and in the second stage high temperature roasting, the roasting temperature is 975 ℃, and the roasting time is 60 min, obtains the high temperature roasting material; S4, the high temperature roasting material obtained by S3 is air-cooled to below 80 ° C, 1.5 times of concentrated sulfuric acid is added to the theoretical amount (based on the detection grade of each lithium ore) and low temperature acidification roasting is carried out. The temperature of the low temperature acidification roasting is 300 ° C, and the roasting time is 45 min to obtain the acidified roasting material; S5. The acidified roasted material obtained in S4 was water-leached at a temperature of 25°C, a leaching time of 40 min, a liquid-to-solid ratio of 4:1, and a final lithium leaching rate of 98.79%.

[0034] Example 11 The raw materials and methods were the same as those in Example 10, except that in step S5, the immersion temperature was 35° C., the leaching time was 60 min, the liquid-to-solid ratio was 3.5:1, and the final lithium leaching rate was 95.77%, indicating that the immersion temperature and immersion time had little effect on the leaching of lithium in the present invention.

[0035] Example 12 The raw materials and method were the same as those in Example 10, except that the immersion temperature in step S5 was 20°C, the immersion time was 60 min, the liquid-to-solid ratio was 5:1, and the final lithium leaching rate was 92.63%.

[0036] Example 13 The raw materials and method were the same as those in Example 10, except that the immersion temperature in step S5 was 50°C, the immersion time was 30 min, the liquid-to-solid ratio was 3:1, and the final lithium leaching rate was 94.44%.

[0037] Comparative Example 1 The raw materials and methods were the same as in Example 1, except that the first-stage roasting time in step S3 was 60 min, the second-stage roasting time was 120 min, and the final lithium leaching rate was 78.25%. This indicates that excessive roasting time can cause spodumene, lepidolite, and clay-type lithium ore to melt. Therefore, an appropriate roasting time is also an important condition parameter in the present invention.

[0038] The present invention provides a method for extracting lithium through continuous induced suspension cascade roasting of clay-type lithium ore-lepidolite-spodumene. The lithium leaching rate in the lithium leachate obtained by the method is ≥90%, which can effectively solve the problem of high crystallization temperature of existing spodumene roasting, while improving the extraction utilization rate of lepidolite and clay-type lithium ore, realizing the integrated extraction and utilization of lithium resources. The method is simple in process, low in energy consumption, low in cost, easy to industrialize, and has good application prospects.

[0039] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for extracting lithium by continuous induced suspension cascade roasting of clay-type lithium ore-lepidolite-spodumene, characterized in that: The following steps are involved: S1. crushing, grinding and discarding the clay-type lithium ore to remove impurities to obtain a clay-type lithium ore sample; S2, the clay-type lithium ore sample obtained in S1 is evenly mixed with the lepidolite concentrate, and water is added to form balls to obtain clay-type lithium ore and lepidolite concentrate pellets; the clay-type lithium ore and lepidolite concentrate pellets are then mixed with spodumene concentrate to obtain a clay-type lithium ore-lepidolite-spodumene mixed material; S3, the clay-type lithium ore-lepidolite-spodumene mixed material obtained in S2 is subjected to step-by-step high-temperature roasting, firstly carrying out the first stage clay-type lithium ore-lepidolite induction roasting, and then raising the temperature to carry out the second stage spodumene crystal conversion roasting to obtain a high-temperature roasted material; S4, air cooling the high temperature calcined material obtained in S3 to below 80°C, and performing low temperature acidification calcination to obtain an acidified calcined material; S5. Leaching the acidified roasted material obtained in S4 into water to obtain a lithium leaching solution.

2. The method according to claim 1, characterized in that The lithium grade of the clay-type lithium ore is 0.1-0.6%, the lithium grade of the lepidolite concentrate is 1.5-4.0%, and the lithium grade of the spodumene concentrate is 5.5-7.5%.

3. The method according to claim 1, characterized in that In the clay-type lithium ore sample described in S1, particles with a particle size of -0.074 mm account for more than 70%.

4. The method according to claim 1, wherein The water-adding pelletizing process described in S2 obtains clay-type lithium ore and lepidolite concentrate pellets with a water content of 7-10%, which are then dried at a low temperature of 60-80°C to finally obtain clay-type lithium ore and lepidolite concentrate pellets with a particle size of 5-10 mm.

5. The method according to claim 1, wherein The mass ratio of clay-type lithium ore: lepidolite concentrate: spodumene concentrate described in S2 is (0.5~2): (0.5~2): (1~3).

6. The method according to claim 1, characterized in that In S3, the first stage high-temperature roasting temperature is 700~800°C, and the roasting time is 5~20 min; the second stage high-temperature roasting temperature is 800~975°C, and the roasting time is 20~60 min.

7. The method according to claim 1, characterized in that The reagent for the low-temperature acidification roasting in S4 is concentrated sulfuric acid with a mass concentration of 18.4 mol / L. The amount of concentrated sulfuric acid used is 1.3 to 1.5 times the theoretical acid consumption when all the lithium elements in the clay-type lithium ore, lepidolite concentrate and spodumene concentrate are converted into lithium sulfate.

8. The method according to claim 1, characterized in that In the low-temperature acidification calcination described in S4, the calcination temperature is 200-300° C., and the calcination time is 10-60 min.

9. The method according to claim 1, characterized in that The leaching temperature in the water leaching process described in S5 is 20~50°C, the leaching time is 30~60 min, and the liquid-to-solid ratio is (3~5):

1.

10. The method according to claim 1, characterized in that The leaching rate of lithium in the lithium leaching solution is ≥90%.

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