Normal-temperature and normal-pressure efficient leaching method for low-grade clay type lithium ore

Abstract

The invention discloses a normal-temperature and normal-pressure efficient leaching method for low-grade clay type lithium ore, and belongs to the technical field of lithium extraction. According to the method, H2SO4 and a fluorine-containing auxiliary leaching agent are adopted as leaching agents, a solution containing F <-> is used for damaging Si-O bonds and Al-O bonds of clay minerals, H < + > of H2SO4 can be adsorbed on the surfaces of the minerals in a system, the strength of the Si-O bonds and the strength of the Al-O bonds are reduced, F <-> is promoted to damage an aluminosilicate structure of the clay minerals, insoluble fluoride salt can be converted into soluble sulfate through H2SO4, and therefore the leaching efficiency of the clay minerals is improved. Dissolved products are prevented from precipitating; and then Li < + > adsorbed on the surface of the leaching slag is removed through water washing, normal-temperature and normal-pressure efficient leaching of the low-grade clay type lithium ore is achieved, the step of high-temperature roasting is omitted, and the method has the advantages of being simple in process, high in leaching rate, low in leaching cost and short in leaching time.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium extraction, and in particular relates to a method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure. Background Art

[0002] Lithium metal is known as green energy metal and "white oil" and is widely used in energy storage, chemical industry, medicine, metallurgy, electronics industry and other fields. In recent years, with the rapid development of new energy vehicles, lithium has become an indispensable material in battery production, and its demand has shown exponential growth. At present, world-class carbonate clay lithium resources have been discovered in central Yunnan, my country, with an average Li2O grade of 0.30%. The predicted resource reserves can reach 4.89 million tons, which has attracted the attention of many scholars. After genetic mineralogy research, it was found that the lithium element in the region is mainly present in clay minerals such as montmorillonite and lithium chlorite. These clay minerals have stable crystal structures and it is difficult to directly leach lithium.

[0003] The invention patent with application number 202310036262.2 discloses a method for selectively leaching lithium from clay-type lithium ore. The crushed and ground clay-type lithium ore is roasted at 500-600°C for 1-3 hours, and the roasted ore powder is leached with water and soluble fluoride salt at 80-90°C to obtain a lithium-rich leaching solution with a leaching rate of more than 80%. Although the leaching agent in the invention is a soluble fluoride salt, which is not a strong acid or alkali and has little damage to the equipment, it requires high-temperature roasting, and the leaching process requires heating, which consumes a lot of energy, takes a long time, and pollutes the environment.

[0004] The invention patent with application number 202410299560.5 discloses a method for extracting lithium from clay lithium ore by low-temperature acidification reaction. The clay lithium ore is crushed and ball-milled to 200 mesh, then subjected to 600°C high-temperature lattice crystal transformation, and then crushed again and leached with one or more acids at 70-80°C. Finally, the lithium is purified, and the leaching rate is above 85%. This invention also has the problems of high energy consumption required for high-temperature roasting, high leaching acid consumption, and complex process.

[0005] The invention patent with application number 202210867554.6 discloses a method for selectively extracting lithium from clay-type lithium ore. The clay lithium ore is first ball-milled into a fine-grained material, and then subjected to a lithium ion replacement reaction with an ion exchange solution under an ultrasonic environment, and finally a lithium-rich solution is extracted with a leaching rate of more than 90%. This invention does not require high-temperature roasting, but is only applicable to clay lithium ores where lithium exists between mineral layers or in an adsorbed state. For lithium existing in the mineral structure, it is impossible to cause its structure to collapse and undergo a replacement reaction.

[0006] At present, most scholars extract lithium by roasting clay-type lithium ore to destroy its crystal structure and then leaching it, which has the problems of complex process, high energy consumption and environmental pollution. Therefore, there is an urgent need for a method of directly leaching clay-type lithium ore without roasting to solve the problems of high energy consumption and complex process of traditional lithium extraction process. Summary of the invention

[0007] In order to solve the above technical problems, the present invention proposes a method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure, comprising the following steps:

[0010] The low-grade clay-type lithium ore is ground, and then leached at room temperature and pressure using H2SO4 and a fluorine-containing leaching aid as leaching agents to obtain a leachate; at room temperature and pressure, deionized water is added to the leachate for washing, and then solid-liquid separation is performed to obtain a lithium-rich solution and a filter residue.

[0011] Preferably, the fluorine-containing immersion aid includes one or more of HF, H2SiF6, NaF, and Na2SiF6.

[0012] Preferably, the mass concentration of H2SO4 is 40-60%, and the mass concentration of the fluorine-containing impregnation agent is 20-40%.

[0013] Preferably, the volume ratio of H2SO4 to the fluorine-containing impregnation agent is 2:1.

[0014] Preferably, the solid-liquid ratio of the leaching is 1:(2-4).

[0015] Preferably, the leaching time is 20 to 40 minutes, and the stirring speed during leaching is 1200 r / min.

[0016] Preferably, the solid-liquid ratio of the water washing is 1:(6-10).

[0017] Preferably, the water washing time is 20 to 40 minutes, and the stirring speed during water washing is 1200 r / min.

[0018] Preferably, the Li2O grade of the low-grade clay-type lithium ore is less than 0.25%.

[0019] Preferably, the grinding is to grind the low-grade clay-type lithium ore to a particle size of -200 mesh accounting for more than 98%.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] (1) Compared with the traditional lithium extraction method, the present invention omits the roasting step and does not require heating and pressurization during leaching, which saves energy and simplifies the process.

[0022] (2) The present invention uses H2SO4 and fluorine-containing leaching aids as leaching agents, which enhances the effect of collapsing the clay mineral structure and releasing lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0024] Figure 1 The process flow chart of the high-efficiency leaching method of low-grade clay-type lithium ore at normal temperature and pressure in Examples 1 to 7 of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The embodiment of the present invention provides a method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure, comprising the following steps:

[0028] The low-grade clay-type lithium ore is ground, and then leached at room temperature and pressure using H2SO4 and a fluorine-containing leaching aid as leaching agents to obtain a leachate; at room temperature and pressure, deionized water is added to the leachate for washing, and then solid-liquid separation is performed to obtain a lithium-rich solution and a filter residue.

[0029] The present invention adopts H2SO4 and fluorine-containing leaching agent as leaching agent, and uses F-containing - The solution destroys the Si-O bond and Al-O bond of clay minerals, and the H + In the system, it can be adsorbed on the mineral surface, reducing the strength of Si-O bonds and Al-O bonds, and promoting F - Destroy the aluminum silicate structure of clay minerals, and H2SO4 can convert insoluble fluoride salts into soluble sulfates to prevent the precipitation of dissolved products; combined with water washing to wash away the Li adsorbed on the surface of the leaching residue +, achieving efficient leaching of low-grade clay-type lithium ore at room temperature and pressure, eliminating the high-temperature roasting step, and has the characteristics of simple process, high leaching rate, low leaching cost and short leaching time.

[0030] In a preferred embodiment, the fluorine-containing immersion aid comprises one or more of HF, H2SiF6, NaF, and Na2SiF6, and HF is further preferred. - The aluminum silicate structure of clay minerals can be effectively destroyed, thereby releasing lithium in the mineral crystal structure, which is the key to lithium leaching in the present invention.

[0031] In a preferred embodiment, the mass concentration of H2SO4 is 40-60%, preferably 50%; the mass concentration of the fluorine-containing leaching agent is 20-40%, preferably 30%. The present invention uses H2SO4 and fluorine-containing leaching agents with higher mass concentrations as leaching agents, which have stronger acidity and can significantly improve the leaching rate of lithium; if the concentration of H2SO4 and fluorine-containing leaching agents is too low, the acidity is weak, and they do not have sufficient ability to dissolve clay minerals, which will affect the leaching rate of lithium.

[0032] In a preferred embodiment, the volume ratio of H2SO4 to the fluorine-containing immersion aid is 2:1.

[0033] In a preferred embodiment, the solid-liquid ratio of the leaching is 1:(2-4), preferably 1:(2.5-3.5).

[0034] In a preferred embodiment, the leaching time is 20 to 40 minutes, preferably 30 minutes; the stirring speed during the leaching is 1200 r / min. In the present invention, the leaching time is too short to completely leach lithium, which will affect the leaching rate of lithium.

[0035] In a preferred embodiment, the solid-liquid ratio of the water washing is 1:(6-10), preferably 1:8; the solid in the solid-liquid ratio of the water washing refers to the raw ore, that is, low-grade clay-type lithium ore.

[0036] In a preferred embodiment, the water washing time is 20 to 40 minutes, preferably 30 minutes; and the stirring speed during the water washing is 1200 r / min.

[0037] In a preferred embodiment, the Li2O grade of the low-grade clay-type lithium ore is less than 0.25%.

[0038] In a preferred embodiment, the grinding is to grind the low-grade clay-type lithium ore to a particle size of -200 mesh accounting for more than 98%.

[0039] In the embodiments of the present invention, normal temperature refers to "25±2°C".

[0040] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0041] Example 1

[0042] Clay-type lithium ore comes from the central part of Yunnan, with a Li2O grade of 0.218%. The lithium element is mainly present in the montmorillonite structure. The process flow of the ... Figure 1 , the specific steps are as follows:

[0043] 1) Grinding low-grade clay-type lithium ore to a particle size of -200 meshes accounting for more than 98%, so as to obtain fine-grained leaching materials after sufficient dissociation;

[0044] 2) Under normal temperature and pressure conditions, leaching the fine-grained leached material in step 1) with 50% by mass concentration of H2SO4 and 30% by mass concentration of HF as leaching agents, the volume ratio of H2SO4 to HF is 2:1, leaching for 30 minutes, the leaching solid-liquid ratio is 1:3, and the stirring speed during leaching is 1200 r / min to obtain a leachate;

[0045] 3) Under normal temperature and pressure conditions, deionized water is added to the leaching solution obtained in step 2) for washing for 30 minutes, the solid-liquid ratio of the washing is 1:8, the stirring speed during the washing is 1200r / min, and after the washing is completed, solid-liquid separation is performed to obtain a lithium-rich solution and a filter residue.

[0046] Example 2

[0047] The difference from Example 1 is that HF ​​in step 2) is replaced by H2SiF6, and the remaining steps are the same as Example 1.

[0048] Example 3

[0049] The difference from Example 1 is that HF ​​in step 2) is replaced by NaF, and the remaining steps are the same as Example 1.

[0050] Example 4

[0051] The difference from Example 1 is that HF ​​in step 2) is replaced by Na2SiF6, and the remaining steps are the same as Example 1.

[0052] The Li2O leaching rates of Examples 1 to 4 are shown in Table 1.

[0053] Table 1 Li2O leaching rate of Examples 1 to 4

[0054] project Example 1 Example 2 Example 3 Example 4 <![CDATA[Leaching rate of Li2O / %]]> 91.33 76.53 65.38 63.25

[0055] As shown in Table 1, under the same leaching conditions, the leaching effect of fluorine-containing leaching aids on clay-type lithium ore is ranked as HF>H2SiF6>NaF>Na2SiF6. When H2SO4 and HF are used as leaching agents, the leaching effect of clay-type lithium ore is the best, followed by H2SO4 and H2SiF6. NaF and Na2SiF6 are salts, which have a great influence on the H content of the leaching environment. + The content did not change significantly, and thus could not promote F - It destroys the aluminum silicate structure of clay minerals, so the leaching effect is poor in comparison; H2SiF6 is an acid, which can make the acidity of the leaching environment stronger, so the leaching effect is better than NaF and Na2SiF6; HF is more acidic than H2SiF6, and HF will decompose into H + and F - , and H2SiF6 will decompose into H + 、F - and SiF6 2- , the F released by HF at the same dosage - More than H2SiF6, so the leaching effect of HF is obviously better than that of H2SiF6.

[0056] According to the atomic structure, the radius of F is smaller than that of O and the electronegativity of F is greater than that of O. The Si-F bond and the Al-F bond are more stable than the Si-O bond and the Al-O bond. Therefore, the F-containing - The solution of H2SO4 destroys the Si-O and Al-O bonds of clay minerals. + In the system, it can be adsorbed on the surface of minerals, reduce the strength of Si-O bonds and Al-O bonds, promote F- to destroy the aluminosilicate structure of clay minerals, and H2SO4 can convert insoluble fluoride salts into soluble sulfates to prevent the precipitation of dissolved products.

[0057] Example 5

[0058] The clay-type lithium ore used in this example comes from western Guizhou, with a Li2O grade of 0.229%. The lithium element is mainly present in lithium chlorite. The high-efficiency leaching method for low-grade clay-type lithium ore at room temperature and pressure is the same as in Example 1, and the process flow is shown in Figure 1 .

[0059] Comparative Example 1

[0060] The difference from Example 5 is that the leaching time in step 2) is 15 minutes, and the remaining steps are the same as Example 5.

[0061] Comparative Example 2

[0062] The difference from Example 5 is that in step 2), H2SO4 with a mass concentration of 50% is used as the leaching agent, and the remaining steps are the same as Example 5.

[0063] Comparative Example 3

[0064] The difference from Example 5 is that in step 2), the mass concentration of H2SO4 is 20%, the mass concentration of HF is 7.5%, and the remaining steps are the same as Example 5.

[0065] Comparative Example 4

[0066] The difference from Example 5 is that the water washing process in step 3) is omitted, and the remaining steps are the same as Example 5.

[0067] The Li2O leaching rates of Example 5 and Comparative Examples 1 to 4 are shown in Table 2.

[0068] Table 2 Li2O leaching rate of Example 5 and Comparative Examples 1 to 4

[0069] project Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 <![CDATA[Leaching rate of Li2O / %]]> 92.12 34.20 3.17 17.45 59.98

[0070] It can be seen from Example 5 and Comparative Example 1 that leaching time is an important factor affecting the Li2O leaching rate. The leaching time of Comparative Example 1 is 15 minutes, which is too short to completely leach lithium.

[0071] It can be seen from Example 5 and Comparative Example 2 that when using a single H2SO4 as a leaching agent for clay-type lithium ore, the Li2O leaching rate is only 3.17%, indicating that even though H2SO4 is a strong acid, it still does not have the ability to collapse the lithium chlorite structure and release lithium. The F- of HF can effectively destroy the aluminosilicate structure of clay minerals, thereby releasing lithium in the mineral crystal structure, indicating that F- is the key to leaching lithium in the present invention.

[0072] It can be seen from Example 5 and Comparative Example 3 that the concentration of H2SO4 and HF is also one of the factors affecting the lithium leaching effect. H2SO4 with a mass concentration of 20% and HF with a mass concentration of 7.5% do not have sufficient ability to dissolve clay minerals due to their low concentration and weak acidity.

[0073] It can be seen from Example 5 and Comparative Example 4 that water washing can remove the Li adsorbed on the surface of the leaching residue. + , improve the Li2O leaching rate.

[0074] Example 6

[0075] Clay-type lithium ore comes from the central part of Yunnan, with a Li2O grade of 0.218%. The lithium element is mainly present in the montmorillonite structure. The process flow of the ... Figure 1 , the specific steps are as follows:

[0076] 1) Grinding low-grade clay-type lithium ore to a particle size of -200 meshes accounting for more than 98%, so as to obtain fine-grained leaching materials after sufficient dissociation;

[0077] 2) Under normal temperature and pressure conditions, the fine-grained leached material in step 1) is leached with 40% by mass H2SO4 and 20% by mass HF as leaching agents, the volume ratio of H2SO4 to HF is 2:1, the leaching is carried out for 20 minutes, the leaching solid-liquid ratio is 1:2, and the stirring speed during leaching is 1200 r / min to obtain a leachate;

[0078] 3) Under normal temperature and pressure conditions, deionized water is added to the leaching solution obtained in step 2) for washing for 20 minutes, the solid-liquid ratio of the washing is 1:6, the stirring speed during the washing is 1200r / min, and after the washing is completed, solid-liquid separation is performed to obtain a lithium-rich solution and a filter residue.

[0079] Example 7

[0080] Clay-type lithium ore comes from the central part of Yunnan, with a Li2O grade of 0.218%. The lithium element is mainly present in the montmorillonite structure. The process flow of the ... Figure 1 , the specific steps are as follows:

[0081] 1) Grinding low-grade clay-type lithium ore to a particle size of -200 meshes accounting for more than 98%, so as to obtain fine-grained leaching materials after sufficient dissociation;

[0082] 2) Under normal temperature and pressure conditions, the fine-grained leached material in step 1) is leached with 60% by mass H2SO4 and 40% by mass HF as leaching agents, the volume ratio of H2SO4 to HF is 2:1, the leaching is carried out for 40 minutes, the leaching solid-liquid ratio is 1:4, and the stirring speed during leaching is 1200 r / min to obtain a leachate;

[0083] 3) Under normal temperature and pressure conditions, deionized water is added to the leaching solution obtained in step 2) for washing for 40 minutes, the solid-liquid ratio of the washing is 1:10, the stirring speed during the washing is 1200r / min, and after the washing is completed, solid-liquid separation is performed to obtain a lithium-rich solution and a filter residue.

[0084] The Li2O leaching rates of Examples 6 to 7 are shown in Table 3.

[0085] Table 3 Li2O leaching rate of Examples 6 to 7

[0086] project Example 6 Example 7 <![CDATA[Leaching rate of Li2O / %]]> 66.90 93.36

[0087] In summary, the method for efficiently leaching low-grade clay-type lithium ore at room temperature and pressure described in the present invention omits the high-temperature roasting step, does not require heating and pressurization during leaching, and has the characteristics of simple process, high leaching rate, low leaching cost and short leaching time.

[0088] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure, characterized in that: The following steps are involved: The low-grade clay-type lithium ore is ground, and then leached at room temperature and pressure using H2SO4 and a fluorine-containing leaching aid as leaching agents to obtain a leachate; at room temperature and pressure, deionized water is added to the leachate for washing, and then solid-liquid separation is performed to obtain a lithium-rich solution and a filter residue.

2. The method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure according to claim 1, characterized in that: The fluorine-containing immersion aid includes one or more of HF, H2SiF6, NaF, and Na2SiF6.

3. The method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure according to claim 1, characterized in that: The mass concentration of the H2SO4 is 40-60%, and the mass concentration of the fluorine-containing immersion aid is 20-40%.

4. The method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure according to claim 1 or 3, characterized in that: The volume ratio of H2SO4 to the fluorine-containing immersion aid is 2:

1.

5. The method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure according to claim 1, characterized in that: The solid-liquid ratio of the leaching is 1:(2-4).

6. The method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure according to claim 1, characterized in that: The leaching time is 20 to 40 minutes, and the stirring speed during leaching is 1200 r / min.

7. The method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure according to claim 1, characterized in that: The solid-to-liquid ratio of the water washing is 1:(6-10).

8. The method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure according to claim 1, characterized in that: The water washing time is 20 to 40 minutes, and the stirring speed during the water washing is 1200 r / min.

9. The method for efficiently leaching low-grade clay-type lithium ore at normal temperature and pressure according to claim 1, characterized in that: The Li2O grade of the low-grade clay-type lithium ore is less than 0.25%.

10. The method for high-efficiency leaching of low-grade clay-type lithium ore at normal temperature and pressure according to claim 1, characterized in that: The grinding process is to grind the low-grade clay-type lithium ore to a particle size of -200 meshes accounting for more than 98%.

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