Method for lithium extraction from lithium ore

Abstract

The application belongs to the field of lithium ore lithium extraction, and specifically discloses a lithium ore lithium extraction method, which comprises the following steps: crushing lithium ore to obtain lithium ore powder, wherein the D50 particle size of the lithium ore powder is less than or equal to 20 microns; performing transformation roasting on the lithium ore powder to obtain a transformation roasting product; performing acidizing roasting on the transformation roasting product to obtain an acidizing roasting product; and performing leaching on the acidizing roasting product to obtain a lithium-containing leaching solution and a leaching residue. The above method can efficiently extract lithium from lithium ore of different grades, and the lithium extraction rate is more than 95%.

Description

Technical Field

[0001] This application relates to the field of lithium extraction from lithium ore, specifically to methods for lithium extraction from lithium ore. Background Technology

[0002] Lithium is a widely used metallic material and a crucial strategic resource. With the continuous expansion of the new energy industry, the demand for lithium batteries is constantly rising, leading to explosive growth in global lithium consumption. This has resulted in the rapid development of lithium ore resources. However, in recent years, the lithium extraction rate has varied significantly due to the different types and grades of lithium ores. Therefore, achieving efficient lithium extraction from various types and grades is currently one of the major challenges.

[0003] Application content

[0004] This application aims to at least partially solve one of the technical problems in the related art. Therefore, one objective of this application is to provide a method for lithium extraction from lithium ore, which is applicable to different types and grades of lithium ore, and achieves a lithium extraction efficiency of over 95%.

[0005] The first aspect of this application proposes a method for extracting lithium from lithium ore, comprising: crushing lithium ore to obtain lithium ore powder, wherein the D50 particle size of the lithium ore powder is ≤20 micrometers; performing transformation roasting on the lithium ore powder to obtain transformation roasting product; performing acid roasting on the transformation roasting product to obtain acid roasting product; and leaching the acid roasting product to obtain lithium-containing leachate and leaching residue.

[0006] This method involves crushing lithium ore to control the particle size of lithium ore powder. Almost all the lithium ore inside the powder particles can be transformed into an active structure, thereby improving the crystallization rate during transformation roasting. During acid roasting, almost all the lithium ore with the active structure can participate in the reaction. Furthermore, the aforementioned particle size range can increase the contact area between the lithium ore powder and acid, reducing the amount of acid used, thus achieving the goal of efficient lithium extraction, unaffected by the type and grade of lithium ore.

[0007] In addition, the lithium extraction method from lithium ore according to the above embodiments of this application may also have the following additional technical features:

[0008] In some embodiments of this application, the specific surface area of ​​the lithium ore powder is 5m². 2 / g~15m 2 / g. The above specific surface area is beneficial to improving the crystallization rate of lithium ore powder during the transformation roasting process, as well as the contact area with acid during acid roasting, thereby effectively improving the lithium extraction rate.

[0009] In some embodiments of this application, the D10 particle size of the lithium ore powder is ≤10μm; the D90 particle size of the lithium ore powder is ≤40μm. These particle size ranges are beneficial for further improving the lithium extraction rate.

[0010] In some embodiments of this application, the lithium ore grade is [0.2%, 3%], and the lithium ore powder satisfies the following conditions: D50 particle size ≤ 10 μm, D10 particle size ≤ 5 μm, and D90 particle size ≤ 40 μm; or the lithium ore grade is [3%, 6%], and the lithium ore powder satisfies the following conditions: D50 particle size ≤ 20 μm, D10 particle size ≤ 5 μm, and D90 particle size ≤ 40 μm. Setting appropriate particle size ranges for lithium ores of different grades can improve efficiency and reduce costs while ensuring lithium extraction rate.

[0011] In some embodiments of this application, the crushing includes sequential coarse grinding and fine grinding. This allows for the rapid acquisition of lithium ore powder with a suitable particle size range.

[0012] In some embodiments of this application, the coarse grinding is performed using at least one of a jaw crusher, a crusher, and a double-roll mill, and / or the fine grinding is performed using at least one of a vibratory mill and a planetary ball mill. Thus, coarse grinding is more efficient and less costly, while fine grinding allows for easier control of the lithium ore powder particle size.

[0013] In some embodiments of this application, after the fine grinding, the crushing includes sieving the product from the fine grinding using a 200-2000 mesh sieve. This further removes larger lithium ore particles, resulting in lithium ore powder that meets the particle size requirements.

[0014] In some embodiments of this application, the transformation roasting meets the following conditions: the transformation roasting temperature is 900℃~1200℃; and / or the transformation roasting holding time is 0.5h~1h. The above temperature and time ranges are beneficial for improving the transformation of lithium ore powder into an active structure and increasing the crystal transformation rate.

[0015] In some embodiments of this application, the acidification roasting includes: ball milling the acid and the transformation roasting product, and then roasting the resulting mixture. Ball milling allows for more thorough mixing of the acid and the transformation roasting product, resulting in a more complete reaction during the roasting process.

[0016] In some embodiments of this application, the acidification roasting meets the following conditions: the acid used in the acidification roasting includes sulfuric acid; and / or, the actual amount of acid used is 1.5 to 2.5 times its theoretical amount; and / or, the acidification roasting temperature is 250°C to 270°C; and / or, the holding time for the acidification roasting is 1 to 1.5 hours; and / or, the ball milling time is 15 to 30 minutes. These acidification roasting conditions facilitate a full reaction between the roasting product and the acid, thereby improving the lithium extraction rate.

[0017] In some embodiments of this application, the leaching meets the following conditions: the leaching is performed using water; and / or the leaching temperature is room temperature; and / or the solid-liquid ratio is 1:2 to 3; and / or the leaching time is 2 to 3 hours. Under these leaching conditions, lithium can be leached more fully, resulting in a higher lithium extraction rate.

[0018] In some embodiments of this application, the following steps are further included: before the acidification roasting, the acidified roasting product is subjected to a first vibration grinding treatment; and / or, before the leaching, the acidified roasting product is subjected to a second vibration grinding treatment. This can further improve the lithium extraction rate.

[0019] In some embodiments of this application, the lithium ore meets the following conditions: the lithium ore includes petalite; and / or, the lithium oxide grade in the lithium ore is 0.2% to 6%. The lithium extraction method of this application is well applicable to petalite of different grades, and can achieve a high lithium extraction rate in all cases. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a lithium extraction process from lithium ore according to an embodiment of this application. Detailed Implementation

[0021] The embodiments of this application are described in detail below. The embodiments described below are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0022] This application is based on the inventor's following discoveries and understandings:

[0023] With the increasing demand for lithium batteries, the development of lithium mineral resources has accelerated, and numerous methods for lithium extraction from lithium ore have emerged. Currently, methods for lithium extraction from lithium ore include sulfuric acid roasting, sulfate roasting, and chlorination roasting, among others. Different methods yield varying lithium extraction rates and can lead to other degradations. The final lithium extraction rates of current lithium ore extraction methods are inconsistent, with generally low recovery rates. Furthermore, the extraction rate is affected by the grade of the lithium ore, with lower grades yielding even lower extraction rates. Therefore, the inventors sought to develop a lithium extraction method that is applicable to different grades and types of lithium ore and achieves a high lithium extraction rate.

[0024] Through further exploration, the inventors proposed a method for lithium extraction from lithium ore. This method controls the particle size of lithium ore powder through crushing, enabling the entire lithium ore powder particle to be activated. This allows lithium to more easily dissociate from its original crystal structure, transforming into lithium compounds that are more soluble in water or acid, thus improving the crystallization rate during the transformation roasting process. Simultaneously, controlling the particle size range of the lithium ore powder increases the contact area between the lithium ore powder and acid during the acid roasting step, resulting in a more complete reaction and requiring less acid. This lithium extraction method is applicable to different types and grades of lithium ore, and achieves a higher lithium extraction rate.

[0025] In the first aspect of this application, a method for extracting lithium from lithium ore is proposed, referring to... Figure 1 The method includes the following steps:

[0026] S10: The lithium ore is crushed to obtain lithium ore powder, wherein the D50 particle size of the lithium ore powder is ≤20 micrometers.

[0027] In this step, by controlling the D50 particle size of the lithium ore powder to ≤20 micrometers through crushing, the lithium ore powder can fully absorb heat energy during the subsequent transformation roasting. The stable structure of the lithium ore powder can be broken without excessively high temperatures, and almost all of it can be transformed into an active structure, which improves the crystallization rate of the lithium ore powder. In addition, the contact area with acid during acid roasting is larger, the reaction is more complete, the lithium conversion rate is higher, and lithium is easier to leach, thus improving the lithium extraction rate.

[0028] For example, the D50 particle size of lithium ore powder can specifically be 1 micrometer, 2 micrometer, 3 micrometer, 4 micrometer, 5 micrometer, 6 micrometer, 7 micrometer, 8 micrometer, 9 micrometer, 10 micrometer, 11 micrometer, 12 micrometer, 13 micrometer, 14 micrometer, 15 micrometer, 16 micrometer, 17 micrometer, 18 micrometer, 19 micrometer, 20 micrometer, etc. Within the above range, the crystal transformation rate of lithium ore powder can be further improved, the reaction with acid can be promoted, and thus the lithium extraction rate can be further improved.

[0029] In some embodiments of this application, the D10 particle size of the lithium ore powder is ≤10μm, specifically, it can be 10μm, 9μm, 8μm, 7μm, 6μm, 5μm, 4μm, 3μm, 2μm, 1μm, etc. In some embodiments of this application, the D90 particle size of the lithium ore powder is ≤40μm, specifically, it can be 40μm, 35μm, 30μm, 25μm, 20μm, 15μm, 10μm, etc. Within the above particle size range, the lithium ore powder has a suitable particle size distribution, which can further improve the crystal transformation rate of the lithium ore powder, promote the reaction with acid, and thus further improve the lithium extraction rate.

[0030] In this article, D50 particle size refers to the particle size corresponding to a cumulative particle size distribution percentage of 50% for lithium ore powder. That is, particles smaller than this D50 value account for 50% of the total particle count, and particles larger than this D50 value also account for 50%. D10 particle size refers to the particle size corresponding to a cumulative particle size distribution percentage of 10% for lithium ore powder. Particles smaller than this D10 value account for 10% of the total particle count, and particles larger than this D10 value account for 90%. D90 particle size refers to the particle size corresponding to a cumulative particle size distribution percentage of 90% for lithium ore powder. Particles smaller than this D90 value account for 90% of the total particle count, and particles larger than this D90 value account for 10%.

[0031] D10, D50, and D90 particle sizes can be measured using a laser particle size analyzer.

[0032] It is understandable that the higher the grade of lithium ore, the easier it is to extract lithium and the easier it is to increase the lithium extraction rate. Conversely, the lower the grade of lithium ore, the more difficult it is to extract lithium and the less likely it is to obtain a high lithium extraction rate. In the lithium extraction method of this application, different particle size ranges are controlled for lithium ores of different grades, so that a high lithium extraction rate can be achieved regardless of whether it is a high-grade or low-grade lithium ore.

[0033] According to an embodiment of this application, the grade of the lithium ore is [0.2%, 3%], specifically, it can be 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 2.9%, 2.95%, etc.; the lithium ore powder satisfies the following: D50 particle size ≤ 10μm (specifically, 10μm, 9μm, 8μm, 7μm, 6μm, 5μm, 4μm, 3μm, 2μm, 1μm, etc.); D10 particle size ≤ 5μm (specifically, 5μm, 4μm, 3μm, 2μm, 1μm, etc.); D90 particle size ≤ 40μm (specifically, 40μm, 35μm, 30μm, 25μm, 20μm, 15μm, 10μm, 5μm, etc.).

[0034] According to an embodiment of this application, the lithium ore has a grade of [3%, 6%], and the lithium ore powder satisfies the following conditions: D50 particle size ≤ 20μm (specifically, 20μm, 18μm, 16μm, 14μm, 12μm, 10μm, 9μm, 8μm, 7μm, 6μm, 5μm, 4μm, 3μm, 2μm, 1μm, etc.); D10 particle size ≤ 5μm (specifically, 5μm, 4μm, 3μm, 2μm, 1μm, etc.); D90 particle size ≤ 40μm (specifically, 40μm, 35μm, 30μm, 25μm, 20μm, 15μm, 10μm, 5μm, etc.).

[0035] Specifically, by setting appropriate particle size ranges for lithium ores of different grades, the grade range of lithium ores can be broadened. Whether it is high-grade or low-grade lithium ore, a high lithium extraction rate can be achieved, while the efficiency is high and the cost is low.

[0036] In this article, the grade of lithium ore refers to the mass percentage of lithium oxide in the lithium ore. The range [0.2%, 3%) above represents the range of 0.2% to 3%, including the 0.2% endpoint but excluding the 3% endpoint. Other similar descriptions are the same and will not be repeated here.

[0037] According to an embodiment of this application, the specific surface area of ​​the lithium ore powder is 5m². 2 / g~15m 2 / g, specifically 5m 2 / g, 5.5m 2 / g、6m 2 / g, 6.5m 2 / g、7m 2 / g, 7.5m 2 / g、8m 2 / g, 8.5m 2 / g、9m 2 / g, 9.5m 2 / g, 10m 2 / g, 10.5m 2 / g、11m 2 / g, 11.5m 2 / g、12m 2 / g, 12.5m 2 / g、13m 2 / g, 13.5m 2 / g、14m 2 / g, 14.5m 2 / g, 15m 2 / g etc. Within the above range, lithium ore powder has a larger contact area with acid during subsequent acid roasting, resulting in a more complete reaction with acid and more thorough lithium dissociation, thus achieving a higher lithium extraction rate while saving acid usage and reducing costs.

[0038] In this article, specific surface area refers to the surface area per unit mass of lithium ore powder. The specific surface area of ​​lithium ore powder can be measured using the BET method.

[0039] According to the embodiments of this application, as long as the lithium ore can be crushed to a suitable particle size range, there are no particular restrictions on the specific crushing method, and it can be flexibly selected according to actual needs.

[0040] In some embodiments, the crushing includes sequential coarse grinding and fine grinding. Specifically, coarse grinding primarily aims to initially liberate most of the valuable minerals in the ore from the gangue, breaking large ore pieces into smaller particles. For example, the coarse grinding can employ jaw crushers, crushers, and double-roll mills. Fine grinding primarily aims to further refine the coarsely ground particles, making them smaller and more uniform. For example, the fine grinding can employ vibratory mills, planetary ball mills, etc. Thus, lithium ore powder meeting particle size requirements can be obtained efficiently and at a lower cost.

[0041] In some embodiments, to better control the particle size of lithium ore powder, after fine grinding, the product can be sieved using a 200-2000 mesh sieve (specifically, 200 mesh, 400 mesh, 600 mesh, 800 mesh, 1000 mesh, 1200 mesh, 1400 mesh, 1600 mesh, 1800 mesh, 2000 mesh, etc.), and the undersize material is used as lithium ore powder in subsequent steps. Sieving further removes lithium ore particles larger than the target particle size, resulting in lithium ore powder that meets the particle size requirements.

[0042] In some embodiments of this application, the specific type and grade of lithium ore that can be used in this step are not particularly limited. By controlling the particle size of the lithium ore powder through pre-crushing treatment, lithium can be more easily separated from the lithium ore.

[0043] In some embodiments, the lithium ore comprises petalite. Specifically, petalite has the chemical formula LiAlSi4O 10Furthermore, petalite is mostly found along the (100) crystal plane and parallel to the (010) crystal direction, exhibiting a semi-euhedral, coarse, flat, or columnar crystal structure. The crystals are generally transparent to translucent, colorless, white, or gray monoclinic, with a three-dimensional framework composed of TO4 (T = Li, Al, Si) apical oxygen atoms. The cations are perfectly arranged at the crystal sites, making it a layered silicate. This structure is relatively stable, making lithium extraction more difficult than from other lithium ores and requiring higher energy consumption. The lithium extraction method of this application, by controlling the particle size of the lithium ore powder through crushing, allows the stable petalite to undergo crystal structure changes at a lower transformation roasting temperature, transforming it into a more active crystal structure. This allows the lithium in the lithium ore to react more fully with the acid in the subsequent acid roasting step, thereby achieving a higher lithium extraction rate. This overcomes the problems of high difficulty in extracting lithium from petalite, low lithium extraction rate, and high requirements for lithium ore grade.

[0044] In some embodiments, the lithium oxide grade in the lithium ore is 0.2% to 6%, specifically, it can be 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, etc. For lithium ores within the above-mentioned grade range, the lithium extraction method of this application can achieve a high lithium extraction rate, overcoming the problem in related technologies that require high lithium ore grade to improve the lithium extraction rate.

[0045] As an example, petalite includes, but is not limited to, concentrates, tailings, and raw ore in mineral processing.

[0046] S20: The lithium ore powder is subjected to transformation roasting to obtain the transformation roasting product.

[0047] In this step, the crystal structure of lithium ore powder changes from dense to loose, and lithium changes from an insoluble form to a soluble form, which is beneficial for the dissociation and leaching of lithium in subsequent steps.

[0048] In some embodiments of this application, the transformation roasting temperature is 900℃ to 1200℃, specifically 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, etc. Within this temperature range, the transformation of the lithium ore crystal structure is more conducive, and the transformation rate is higher. The transformed crystal structure is more conducive to lithium dissociation and leaching. Furthermore, by controlling the particle size range of the lithium ore powder, the transformation roasting temperature can be appropriately reduced, achieving the transformation of the lithium ore crystal structure without excessively high temperatures, thereby reducing energy consumption and saving costs.

[0049] In some embodiments of this application, the holding time for the transformation roasting is 0.5h to 1h, specifically, it can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, etc. Within the above time range, almost all lithium ore powder can complete the crystal structure transformation. The crystal structure of some lithium ore powder will not fail to transform due to an excessively short holding time, nor will it result in a waste of time and energy due to an excessively long holding time.

[0050] In some embodiments of this application, the transformed roasted product may also undergo a first vibration grinding process. This allows for the dissociation of lithium ore powder that has agglomerated during roasting, yielding a product with a suitable particle size range.

[0051] As an example, the time for the first vibration grinding treatment can be 15 min to 30 min (specifically, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, etc.).

[0052] It is understandable that when the method includes a first vibration grinding process, the product obtained after the first vibration grinding process is subjected to subsequent acid roasting.

[0053] S30: The transformed roasting product is subjected to acid roasting to obtain an acid roasting product.

[0054] In this step, lithium in the lithium ore can react with acid to form soluble lithium salts, which facilitates leaching in subsequent steps.

[0055] In some embodiments of this application, the acidification roasting may include: ball milling the acid and the transformation roasting product, and then roasting the resulting mixture. Ball milling allows for more thorough mixing of the acid and the transformation roasting product, resulting in a more complete reaction during the roasting process.

[0056] In some embodiments of this application, the ball milling time can be 15-30 minutes, specifically 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, etc. Within the above time range, the acid and the transformation roasting product can be fully mixed.

[0057] As an example, the obtained transformation roasted product and acid can be added to a planetary ball mill and mixed for 15 min to 30 min.

[0058] In some embodiments of this application, the acid used in acid roasting includes sulfuric acid. Specifically, sulfuric acid can react with lithium in lithium ore to form soluble lithium sulfate, allowing lithium to be effectively leached from the lithium ore.

[0059] In some embodiments, the sulfuric acid can be sulfuric acid with a mass concentration of 93% to 98%, specifically, the mass concentration of the sulfuric acid can be 93%, 94%, 95%, 96%, 97%, 98%, etc. This allows for a more complete reaction with lithium in the lithium ore, which is beneficial for improving the lithium extraction rate.

[0060] In some embodiments of this application, the amount of acid added is 1.5 to 2.5 times its theoretical amount, specifically 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, and 2.5 times. This promotes a more complete reaction of lithium and increases the lithium extraction rate.

[0061] In this article, the theoretical amount of acid used refers to the amount of acid calculated based on the lithium content in the lithium ore and the reaction equation between lithium and acid. Taking lithium in the lithium ore as lithium oxide and sulfuric acid as the acid used as an example, the reaction equation between lithium oxide and sulfuric acid is as follows: Li₂O + H₂SO₄ → Li₂SO₄ + H₂O. The lithium oxide content in the lithium ore is measured, and then the theoretical amount of sulfuric acid can be calculated based on the above chemical reaction equation. For example, if the lithium oxide content in the lithium ore is measured to be 1 mole, then the theoretical amount of sulfuric acid used is 1 mole. In actual operation, the actual amount of sulfuric acid used is 1.5 moles to 2.5 moles.

[0062] In some embodiments of this application, the acid roasting temperature is 250℃~270℃, specifically, it can be 250℃, 255℃, 260℃, 265℃, 270℃, etc. Within the above temperature range, lithium in lithium ore can react with acid at a higher rate and more fully to generate soluble lithium salts, thereby obtaining a higher lithium extraction rate.

[0063] In some embodiments of this application, the holding time for acid roasting is 1 hour to 1.5 hours, specifically 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, etc. Within the above time range, the reaction between lithium and acid in the lithium ore can be basically guaranteed to proceed fully without wasting too much time.

[0064] In some embodiments of this application, the acid-calcined product can also be subjected to a second vibration grinding process. This allows for the dissociation of agglomerates generated during acid-calcination, yielding a product with a suitable particle size range.

[0065] As an example, the second vibration grinding treatment time can be 15 min to 30 min (specifically 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, etc.).

[0066] It is understandable that when the method includes a second vibration grinding treatment, the product obtained after the second vibration grinding treatment will be subsequently leached.

[0067] S40: The acidified roasting product is leached to obtain a lithium-containing leachate and leaching residue.

[0068] In this step, soluble lithium salts in the acidified roasting product can be leached into a solution to obtain a lithium-containing leachate, which separates lithium from the acidified roasting product.

[0069] In some embodiments of this application, water can be used to leach the acidified roasted products. This reduces equipment requirements, is environmentally friendly, non-toxic, and does not introduce impurities. Furthermore, the leachate can be reused multiple times to leach the acidified roasted products, thereby increasing the lithium concentration.

[0070] It should be noted that the above-mentioned multiple reuse of the leaching solution refers to the use of the lithium-containing leaching solution obtained earlier to leach the acidified roasted product obtained later. The resulting lithium-containing leaching solution has a higher lithium concentration, is easier to process later, and does not affect the lithium extraction rate.

[0071] In some embodiments of this application, the leaching temperature can be room temperature. Here, room temperature refers to 20°C to 35°C. This provides mild conditions while achieving a relatively high lithium extraction rate.

[0072] In some embodiments of this application, the leaching time is 2 to 3 hours, specifically 2 hours, 2.2 hours, 2.5 hours, 2.7 hours, 3 hours, etc. Within the above time range, it can be basically guaranteed that lithium can be fully leached into the solution, which can ensure a high lithium extraction rate without wasting too much time.

[0073] In some embodiments of this application, the solid-liquid ratio of the leaching is 1:2 to 3, specifically 1:2, 1:2.5, 1:3, etc. This ratio range allows lithium to dissolve fully in the solution, resulting in a high lithium extraction rate. Simultaneously, the lithium concentration in the resulting lithium-containing leachate is high, which is beneficial for subsequent processing and application.

[0074] It is understandable that after leaching, lithium-containing leachate and leaching residue can be obtained through solid-liquid separation. There are no particular restrictions on the solid-liquid separation method; for example, it can be pressure filtration, vacuum filtration, belt filtration, etc. The main component of the lithium-containing leachate is lithium salt. The specific type of lithium salt is related to the type of acid used in the acid roasting process. For example, if the acid used in the acid roasting process is sulfuric acid, then the lithium salt in the lithium-containing leachate will be lithium sulfate.

[0075] The lithium-containing leachate obtained according to the method of this application can be used to synthesize battery-grade lithium carbonate after adjusting the pH value, removing calcium with sodium carbonate, and performing deep impurity removal.

[0076] The method described in this application can effectively extract lithium, and the lithium extraction rate can still reach more than 95% even at lower grades, which largely solves the problem of low lithium extraction efficiency at low grades.

[0077] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0078] Example 1

[0079] Crushing: The lithium oxide content of 4.0% of petalite was first crushed in two steps: coarse grinding using a roller mill and fine grinding using a vibratory mill to obtain petalite powder. The petalite powder was then sieved using a 1200-mesh sieve (12.5 micrometers aperture) to obtain the undersize powder. The particle size and specific surface area of ​​the petalite powder are shown in Table 1.

[0080] Transformation roasting: The crushed lithium feldspar powder is placed in a rotary kiln, and the material temperature in the high-temperature section is controlled at 1000℃ and held for 1 hour.

[0081] Acidification roasting: The product obtained from transformation roasting is ground using a vibratory mill for 20 minutes; the finely ground roasted material is metered and added to a planetary ball mill, and sulfuric acid with a mass concentration of 98% is added at twice the theoretical amount for ball milling and mixing for 20 minutes; the mixture obtained from ball milling is transferred to an acidification kiln, and the temperature is controlled at 250℃ for 1 hour.

[0082] Leaching: The product obtained by acid roasting is subjected to vibration grinding for 20 minutes. After grinding, the product is added to the slurry tank and water is added at a solid-liquid ratio of 1:2 for slurry leaching for 2 hours. After leaching, solid-liquid separation is performed to obtain lithium sulfate leaching solution and leaching residue. The leaching residue can be washed in two stages, with the amount of water used for washing being twice that of the leaching residue, and the washing time being 20 minutes. The lithium sulfate leaching solution can be used for further purification and other processes. All leaching operations are carried out at room temperature.

[0083] Examples 2-30

[0084] Similar to Example 1, the main differences are in lithium oxide grade, particle size of crushed lithite, temperature and time of transformation roasting, concentration and amount of sulfuric acid during acid roasting, leaching time, etc., as detailed in Table 1.

[0085] Comparative Examples 1-2

[0086] Same as Example 1, the main differences are shown in Table 1.

[0087] Relevant parameter tests:

[0088] 1. Determination of lithium oxide grade in lithium ore:

[0089] 2. Determination of lithium ore powder particle size: The particle size was measured using a laser particle size analyzer (NKT5100-H, Shandong Niket Analytical Instrument Co., Ltd.). The lithium ore powder was dispersed in alcohol, ultrasonically treated at 50W for 15 minutes, and then the particle size was tested.

[0090] 3. Determination of specific surface area of ​​lithium ore powder: The BET method was used for testing.

[0091] 4. Determination of lithium extraction rate: The lithium oxide grade in lithium ore and the lithium content in lithium-containing leachate are detected by ICP. The lithium extraction rate is calculated according to the conversion rate = (lithium in lithium-containing leachate) / (lithium in lithium ore) × 100%.

[0092] Table 1

[0093]

[0094]

[0095] The data above shows that pre-crushing the lithium ore and controlling its D50 particle size to be no greater than 20 micrometers significantly improves the lithium extraction rate. Specifically, for spodumene, particle size control improves the lithium extraction rate to a certain extent. Furthermore, for petrified feldspar, which is difficult to extract lithium from, the lithium extraction rate is significantly improved. Even for low-grade petrified feldspar, the lithium extraction rate can still be no less than 95%, while for high-grade petrified feldspar, the lithium extraction rate can be no less than 98%. This demonstrates that the lithium extraction method of this application can effectively improve the lithium extraction rate, especially for low-grade petrified feldspar, which is difficult to extract lithium from, where the improvement is significant.

[0096] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0097] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0098] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for extracting lithium from lithium ore, characterized in that, include: The lithium ore is crushed to obtain lithium ore powder, wherein the D50 particle size of the lithium ore powder is ≤20 micrometers; The lithium ore powder was subjected to transformation roasting to obtain the transformation roasting product; The transformed roasting product is subjected to acid roasting to obtain an acid roasting product; The acidified roasting product is leached to obtain a lithium-containing leachate and a leaching residue.

2. The lithium extraction method from lithium ore according to claim 1, characterized in that, The specific surface area of ​​the lithium ore powder is 5m². 2 / g~15m 2 / g.

3. The lithium extraction method from lithium ore according to claim 1, characterized in that, The lithium ore powder has a D10 particle size ≤ 10 μm; the lithium ore powder has a D90 particle size ≤ 40 μm.

4. The lithium extraction method from lithium ore according to claim 1, characterized in that, The lithium ore has a grade of [0.2%, 3%), and the lithium ore powder meets the following requirements: D50 particle size ≤ 10 μm, D10 particle size ≤ 5 μm, and D90 particle size ≤ 40 μm. or The lithium ore has a grade of [3%, 6%], and the lithium ore powder meets the following requirements: D50 particle size ≤ 20 μm, D10 particle size ≤ 5 μm, and D90 particle size ≤ 40 μm.

5. The lithium extraction method from lithium ore according to claim 1, characterized in that, The crushing process includes coarse grinding and fine grinding performed sequentially.

6. The lithium extraction method from lithium ore according to claim 5, characterized in that, The coarse grinding is carried out using at least one of a jaw crusher, a crusher, and a double-roll mill; and / or... The fine grinding is performed using at least one of a vibratory mill prototype and a planetary ball mill.

7. The lithium extraction method from lithium ore according to claim 5, characterized in that, After the fine grinding, the crushing includes: screening the product of the fine grinding using a 200-2000 mesh sieve.

8. The lithium extraction method from lithium ore according to claim 1, characterized in that, The transformation roasting satisfies at least one of the following conditions: The transformation roasting temperature is 900℃~1200℃; The heat preservation time for the transformation roasting is 0.5h to 1h.

9. The lithium extraction method from lithium ore according to claim 1, characterized in that, The acidification roasting includes: ball milling the acid and the transformation roasting product, and then roasting the resulting mixture.

10. The lithium extraction method from lithium ore according to claim 9, characterized in that, The acid roasting satisfies at least one of the following conditions: The acid used in the acidification roasting includes sulfuric acid; The actual amount of acid used is 1.5 to 2.5 times its theoretical amount; The acidification roasting temperature is 250℃~270℃; The holding time for the acidification roasting is 1 hour to 1.5 hours; The ball milling process takes 15-30 minutes.

11. The method for extracting lithium from lithium ore according to claim 1, characterized in that, The leaching satisfies at least one of the following conditions: The leaching is carried out using water; The leaching temperature is room temperature; The solid-liquid ratio of the leaching is 1:2 to 3; The leaching time is 2 to 3 hours.

12. The lithium extraction method from lithium ore according to claim 1, characterized in that, It also includes at least one of the following steps: Prior to the acidification roasting, the process further includes: subjecting the transformation roasting product to a first vibration grinding treatment; Prior to the leaching, the process further includes subjecting the acidified roasted product to a second vibration grinding treatment.

13. The method for extracting lithium from lithium ore according to claim 1, characterized in that, The lithium ore satisfies at least one of the following conditions: The lithium ore includes petalite; The lithium oxide content in the lithium ore is 0.2% to 6%.

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