Method for green and efficient extraction of lithium from sedimentary clay lithium ore

Abstract

The invention relates to a method for green and efficient extraction of lithium from sedimentary clay lithium ore, belongs to the technical field of lithium extraction, and solves the problem that in the prior art, it cannot be guaranteed that high-efficiency extraction of lithium cannot be guaranteed, and meanwhile harm to the environment in the extraction process cannot be reduced. The method comprises the steps that sedimentary clay lithium ore is crushed, ground and sieved, and millimeter-level lithium ore powder is obtained; mixing the millimeter-scale lithium ore powder with a carboxylic acid-based green solvent system, and heating to strengthen leaching to obtain a lithium-containing solid-liquid mixture; the carboxylic acid-based green solvent system is a carboxylic acid solution or a deep eutectic solvent formed by carboxylic acid and choline chloride; and carrying out solid-liquid separation on the lithium-containing solid-liquid mixture to obtain a lithium-rich leachate and mixed slag. According to the method, acid reagents with extremely high corrosivity such as strong acid are not adopted, high-temperature pretreatment is not needed, the requirement for equipment is not harsh, side reactions are reduced, and efficient leaching of lithium in the sedimentary clay lithium ore is achieved under the relatively mild condition.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium extraction, and in particular to a method for green and efficient extraction of lithium from sedimentary clay lithium ore. Background Art

[0002] Lithium (Li) resources have superior performance and high energy density, making them an indispensable element in energy transition. Natural lithium resources are primarily divided into three types: brine, hard rock, and sedimentary clay. Brine and hard rock types have mature development technologies and are currently the primary sources of lithium compound development worldwide. Sedimentary clay lithium ore is a new type of sedimentary lithium ore and has yet to be developed and applied on a large scale. Given the limited reserves of existing lithium resources, the development of clay-type lithium resources has become an important research direction.

[0003] Sedimentary clay lithium deposits are primarily formed through the natural deposition of clay minerals with high lithium content, such as montmorillonite. Although clay-type lithium deposits have a low lithium grade, they hold significant reserves and are highly valuable for development.

[0004] Compared with the extraction of lithium from traditional high-grade lithium ores such as lepidolite and spodumene, the technical requirements for lithium extraction from clay-type lithium ores are more stringent. The existing extraction processes for clay lithium ores include direct leaching, acid leaching, roasting leaching, additive roasting ion exchange leaching, etc.

[0005] The lithium in clay lithium ore coexists with clay minerals in the form of adsorption and lattice structure. It is difficult to achieve effective dissolution of lithium by direct water leaching; direct leaching with sulfuric acid or hydrochloric acid can achieve a lithium leaching rate of 70-80%, but there are technical problems such as severe equipment corrosion and difficulty in treating acidic wastewater. At the same time, the simultaneous leaching of aluminum and magnesium impurities increases the difficulty of subsequent separation and purification; high-temperature roasting can thermally activate and release lithium, but the process has high energy consumption and causes environmental pollution problems; adding additives such as ammonium sulfate and calcium chloride to lower the roasting temperature can achieve 90.9% lithium leaching, but the tail gas contains NH3 and SO2 that need to be treated, and has high requirements for equipment.

[0006] Therefore, in response to the many problems arising from existing processes, it is particularly urgent to develop a green and environmentally friendly technology with a high lithium leaching rate, while ensuring efficient lithium extraction and reducing the harm to the environment during the extraction process. Summary of the Invention

[0007] In view of the above analysis, the embodiments of the present invention aim to provide a green and efficient method for extracting lithium from sedimentary clay lithium ore, so as to solve the problem that the existing lithium extraction methods cannot ensure efficient extraction of lithium while reducing the harm to the environment during the extraction process.

[0008] The present invention provides a green and efficient method for extracting lithium from sedimentary clay lithium ore, the method comprising:

[0009] Step (1), crushing, grinding, and sieving sedimentary clay lithium ore to obtain millimeter-sized lithium ore powder;

[0010] Step (2), mixing the millimeter-sized lithium ore powder with a carboxylic acid-based green solvent system and heating to enhance leaching to obtain a lithium-containing solid-liquid mixture; the carboxylic acid-based green solvent system is a carboxylic acid solution or a deep eutectic solvent (DES) formed by carboxylic acid and choline chloride;

[0011] Step (3) is to separate the lithium-containing solid-liquid mixture into solid and liquid to obtain a lithium-rich leachate and mixed slag.

[0012] Preferably, the carboxylic acid is at least one of acetic acid, oxalic acid and citric acid.

[0013] Preferably, in the carboxylic acid-based green solvent system, the mass concentration of carboxylic acid in the carboxylic acid solution is 6-40%, and the total mass concentration of carboxylic acid and choline chloride in the deep eutectic solvent formed by the carboxylic acid and choline chloride is 55-70%.

[0014] Preferably, in the deep eutectic solvent formed by the carboxylic acid and choline chloride, the molar ratio of choline chloride to carboxylic acid is 1:1.

[0015] Preferably, in step (1), the sieving is through a 60-mesh sieve.

[0016] Preferably, in step (1), the particle size of the millimeter-sized lithium ore powder is less than 0.2 mm.

[0017] Preferably, in step (2), the mass ratio of the millimeter-sized lithium ore powder to the carboxylic acid-based green solvent system is 1:1 to 15.

[0018] Preferably, in step (2), the conditions for the heating-enhanced leaching include: a heating temperature of 30 to 70° C., a heating time of 1 to 5 hours, and a stirring speed of 400 to 600 rpm.

[0019] Preferably, when the carboxylic acid is oxalic acid, the method further comprises: treating the mixed slag to recover the oxalic acid, and using the recovered oxalic acid in a carboxylic acid-based green solvent system.

[0020] Preferably, the processing of the mixed slag to recover oxalic acid comprises: mixing the mixed slag with sulfuric acid, precipitating, and solid-liquid separation, cooling the solution obtained by solid-liquid separation, crystallizing it, and washing it to obtain oxalic acid crystals.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] 1. The method of the present invention does not use highly corrosive acid reagents such as strong acids, does not require high-temperature pretreatment, is not demanding on equipment, and reduces the occurrence of side reactions, thereby achieving efficient leaching of lithium from sedimentary clay lithium ore under relatively mild conditions.

[0023] 2. The method of the present invention adopts a low leaching temperature, reduces energy consumption and process implementation costs, achieves maximum lithium leaching in one go, and is highly environmentally friendly.

[0024] 3. The carboxylic acid-based green solvent system of the present invention is easy to obtain, has a simple type of leaching agent, and a simple operation process, which is conducive to promotion to industrial application level.

[0025] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0027] Figure 1 The present invention is a flow chart of a method for green and efficient extraction of lithium from sedimentary clay lithium ore.

[0028] Figure 2 The present invention is a flowchart of a method for green and efficient extraction of lithium and recovery of oxalic acid from sedimentary clay lithium ore using an oxalic acid system according to one embodiment of the present invention. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0030] The present invention provides a green and efficient method for extracting lithium from sedimentary clay lithium ore. Figure 1 As shown, the method includes:

[0031] Step (1), crushing, grinding, and sieving sedimentary clay lithium ore to obtain millimeter-sized lithium ore powder;

[0032] Step (2), mixing the millimeter-sized lithium ore powder with a carboxylic acid-based green solvent system and heating to enhance leaching to obtain a lithium-containing solid-liquid mixture; the carboxylic acid-based green solvent system is a carboxylic acid solution or a deep eutectic solvent (DES) formed by carboxylic acid and choline chloride;

[0033] Step (3) is to separate the lithium-containing solid-liquid mixture into solid and liquid to obtain a lithium-rich leachate and mixed slag.

[0034] Compared with existing technologies, the method of the present invention does not use highly corrosive acid reagents such as strong acids, does not require high-temperature pretreatment, is less demanding on equipment, and reduces the occurrence of side reactions, achieving efficient lithium leaching from sedimentary clay lithium ores under relatively mild conditions. The carboxylic acid-based green solvent system of the present invention is readily available, uses a simple leaching agent type, and has a simple operation process, facilitating its expansion to industrial-scale applications.

[0035] It should be noted that the lithium grade in the sedimentary clay lithium ore is below 0.013%.

[0036] Illustratively, in the carboxylic acid-based green solvent system, the carboxylic acid is at least one of acetic acid, oxalic acid, and citric acid. That is, the carboxylic acid-based green solvent is at least one of acetic acid solution, oxalic acid solution, citric acid solution, choline chloride / acetic acid type deep eutectic solvent, choline chloride / oxalic acid type deep eutectic solvent, and choline chloride / citric acid type deep eutectic solvent.

[0037] Illustratively, in the carboxylic acid-based green solvent system, the mass concentration of carboxylic acid in the carboxylic acid solution is 6% to 40%, for example, 6%, 10%, 15%, 20%, 25%, 30%, 40%, and the rest is water.

[0038] Specifically, when the carboxylic acid-based green solvent system is acetic acid, the mass concentration of acetic acid is 6-40%, for example, 6%, 10%, 15%, 20%, 25%, 30%, 40%, and the rest is water; when the carboxylic acid-based green solvent system is oxalic acid, the mass concentration of oxalic acid is 6-20%, for example, 6%, 10%, 15%, 20%, and the rest is water; when the carboxylic acid-based green system is citric acid, the mass concentration of the citric acid solution is 6-40%, for example, 6%, 10%, 15%, 20%, 25%, 30%, 40%, and the rest is water. At the above concentrations, carboxylic acid releases H + Achieve effective leaching of lithium from clay lithium ore.

[0039] Illustratively, the total mass concentration of carboxylic acid and choline chloride in the deep eutectic solvent formed by the carboxylic acid and choline chloride is 55-70%, for example, 55%, 60%, 65%, or 70%, and the remainder is water.

[0040] In the carboxylic acid / choline chloride type deep eutectic solvent system, due to the addition of choline chloride, the two components in the system are firmly associated by hydrogen bonds. Compared with the carboxylic acid solution, the mass concentration of the deep eutectic solvent system increases accordingly. It is worth noting that the carboxylic acid / choline chloride type deep eutectic solvent can achieve effective lithium leaching by dissolving metal oxides in lithium ore.

[0041] For example, in the deep eutectic solvent formed by the carboxylic acid and choline chloride, the molar ratio of choline chloride to carboxylic acid is 1: 1. The deep eutectic solvent (DES) formed by choline chloride and carboxylic acid has a good leaching effect on lithium in clay-type lithium ore.

[0042] In order to improve the leaching rate of lithium, illustratively, in step (1), the screening is through a 60-mesh sieve.

[0043] Illustratively, in step (1), the particle size of the millimeter-sized lithium ore powder is less than 0.2 mm.

[0044] Illustratively, in step (2), the mass ratio of the millimeter-sized lithium ore powder to the carboxylic acid-based green solvent system is 1:1 to 15, for example, 1:1, 1:5, 1:10, or 1:15.

[0045] Illustratively, in step (2), the conditions for heating-enhanced leaching include: a heating temperature of 30 to 70°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C; a heating time of 1 to 5h, for example, 1h, 2h, 3h, 4h, 5h; and a stirring speed of 400 to 600rpm, for example, 400rpm, 450rpm, 500rpm, 550rpm, 600rpm.

[0046] For example, in step (3), when the carboxylic acid-based green solvent system is acetic acid solution, the lithium-rich leachate is an acetic acid-type lithium-rich leachate, and the mixed slag is undissolved slag; when the carboxylic acid-based green solvent system is oxalic acid solution, the lithium-rich leachate is an oxalic acid-type lithium-rich leachate, and the mixed slag is undissolved slag and calcium oxalate; when the carboxylic acid-based green solvent system is citric acid solution, the lithium-rich leachate is a citric acid-type lithium-rich leachate, and the mixed slag is undissolved slag; when the carboxylic acid-based green solvent system is choline chloride / acetic acid type deep eutectic solvent, the lithium-rich leachate is a choline chloride / acetic acid type lithium-rich leachate, and the mixed slag is undissolved slag; when the carboxylic acid-based green solvent system is a choline chloride / oxalic acid type deep eutectic solvent, the lithium-rich leachate is a choline chloride / oxalic acid type lithium-rich leachate, and the mixed slag is undissolved slag and calcium oxalate; when the carboxylic acid-based green solvent system is a choline chloride / citric acid type deep eutectic solvent, the lithium-rich leachate is a choline chloride / citric acid type lithium-rich leachate, and the mixed slag is undissolved slag.

[0047] Illustratively, when the carboxylic acid is oxalic acid, the method further comprises: treating the mixed slag to recover the oxalic acid, and using the recovered oxalic acid in a carboxylic acid-based green solvent system.

[0048] Illustratively, the processing of the mixed slag to recover oxalic acid includes: mixing the mixed slag with sulfuric acid, precipitating, and separating the solid and liquid, cooling the separated solution, crystallizing it, and washing it to obtain oxalic acid crystals.

[0049] Specifically, the processing of the mixed slag to recover oxalic acid includes: adding sulfuric acid to the mixed slag containing undissolved slag and calcium oxalate for precipitation reaction, the amount of sulfuric acid is 2 to 2.5 times the theoretical molar amount of calcium oxalate, and the initial mass concentration of sulfuric acid is 30 to 40%, the precipitation conversion temperature is 30 to 40°C, the stirring speed is 500 to 700 r / min, and the time is 1 hour to 2 hours. After the precipitation conversion is completed, the precipitate and the solution are separated while hot, and the separated solution is naturally cooled and crystallized for 3 to 4 hours to obtain crystals, and the crystals are washed with saturated oxalic acid solution and ethanol in turn to obtain oxalic acid crystals.

[0050] The following is a detailed description of the green and efficient method for extracting lithium from sedimentary clay lithium ore.

[0051] The sedimentary clay lithium ore in the following examples and comparative examples comes from the Barunmahai Basin in Qinghai Province, and has a Li2O grade of 0.013%.

[0052] Example 1

[0053] This embodiment provides a method for green and efficient extraction of lithium from sedimentary lithium ore, the method comprising:

[0054] Step (1) crushes and grinds the sedimentary clay lithium ore, and passes it through a 60-mesh sieve to obtain millimeter-grade lithium ore powder with a particle size of less than 0.2 mm.

[0055] Step (2), mixing the millimeter-sized lithium ore powder with a carboxylic acid-based green solvent system and heating to enhance leaching to obtain a lithium-containing solid-liquid mixture; the carboxylic acid-based green solvent system is an acetic acid aqueous solution, the mass concentration of acetic acid in the carboxylic acid-based green solvent system is 10%, the mass ratio of the millimeter-sized lithium ore powder to the acetic acid solution is 1:10, and the conditions for heating to enhance leaching include: a heating temperature of 60°C, a heating time of 2h, and a stirring speed of 500rpm to obtain an acetic acid-type lithium-containing solid-liquid mixture.

[0056] In step (3), the acetic acid type lithium-containing solid-liquid mixture is subjected to solid-liquid separation to obtain an acetic acid type lithium-rich leachate and mixed slag. The lithium-rich leachate is subjected to ion quantitative analysis, and the results obtained are shown in Table 1.

[0057] Example 2

[0058] This embodiment provides a green and efficient method for extracting lithium from sedimentary lithium ore. Figure 2 As shown, the method includes:

[0059] Step (1) crushes and grinds the sedimentary clay lithium ore, and passes it through a 60-mesh sieve to obtain millimeter-grade lithium ore powder with a particle size of less than 0.2 mm.

[0060] Step (2), mixing the millimeter-sized lithium ore powder with a carboxylic acid-based green solvent system and heating to enhance leaching to obtain a lithium-containing solid-liquid mixture; the carboxylic acid-based green solvent system is an oxalic acid aqueous solution, the mass concentration of oxalic acid in the carboxylic acid-based green solvent system is 10%, the mass ratio of the millimeter-sized lithium ore powder to the oxalic acid solution is 1:5, and the conditions for heating to enhance leaching include: a heating temperature of 60°C, a heating time of 2h, and a stirring speed of 500rpm to obtain an oxalic acid-type lithium-containing solid-liquid mixture.

[0061] In step (3), the oxalate-type lithium-containing solid-liquid mixture is subjected to solid-liquid separation to obtain an oxalate-type lithium-rich leachate, undissolved slag, and calcium oxalate. The lithium-rich leachate is subjected to ion quantitative analysis, and the results are shown in Table 1.

[0062] Step (4): adding sulfuric acid to the mixed slag containing undissolved slag and calcium oxalate to recover oxalic acid, wherein the amount of sulfuric acid is 2.5 times the theoretical molar amount of calcium oxalate, and the initial mass concentration is 30%, the precipitation conversion temperature is 35°C, the stirring speed is 500r / min, and the time is 1.5h. After the precipitation conversion is completed, the precipitate and the solution are separated while hot, and the separated solution is naturally cooled and crystallized for 4h. The crystals are washed with saturated oxalic acid solution and ethanol in sequence to obtain oxalic acid crystals. The oxalic acid crystals are used in a carboxylic acid-based green solvent system, and the acid-based green solvent system can continue to be used for the recovery of lithium in sedimentary clay lithium ore.

[0063] Example 3

[0064] This embodiment provides a method for green and efficient extraction of lithium from sedimentary lithium ore, the method comprising:

[0065] Step (1) crushes and grinds the sedimentary clay lithium ore, and passes it through a 60-mesh sieve to obtain millimeter-grade lithium ore powder with a particle size of less than 0.2 mm.

[0066] Step (2), mixing the millimeter-sized lithium ore powder with a carboxylic acid-based green solvent system and heating to enhance leaching to obtain a lithium-containing solid-liquid mixture; the carboxylic acid-based green solvent system is a citric acid aqueous solution, the mass concentration of citric acid is 10% citric acid, the mass ratio of the millimeter-sized lithium ore powder to the citric acid is 1:10, and the conditions for heating to enhance leaching include: a heating temperature of 60°C, a heating time of 2h, and a stirring speed of 500rpm to obtain a citric acid-type lithium-containing solid-liquid mixture.

[0067] In step (3), the citric acid type lithium-containing solid-liquid mixture is subjected to solid-liquid separation to obtain a citric acid type lithium-rich leachate and undissolved slag. The lithium-rich leachate is subjected to ion quantitative analysis, and the results obtained are shown in Table 1.

[0068] Example 4

[0069] This embodiment provides a method for green and efficient extraction of lithium from sedimentary lithium ore, the method comprising:

[0070] Step (1) crushes and grinds the sedimentary clay lithium ore, and passes it through a 60-mesh sieve to obtain millimeter-grade lithium ore powder with a particle size of less than 0.2 mm.

[0071] Step (2), mixing the millimeter-sized lithium ore powder with a carboxylic acid-based green solvent system and heating to enhance leaching to obtain a lithium-containing solid-liquid mixture; the carboxylic acid-based green solvent system is a choline chloride / citric acid low eutectic solvent, wherein the total mass concentration of choline chloride and citric acid is 55%, the rest is water, and the molar ratio of choline chloride to citric acid is 1:1; the mass ratio of the millimeter-sized lithium ore powder to the choline chloride / citric acid low eutectic solvent is 1:5, and the conditions for heating to enhance leaching include: a heating temperature of 60°C, a heating time of 2h, and a stirring speed of 500rpm, to obtain a choline chloride / citric acid low eutectic solvent (DES) type solid-liquid mixture.

[0072] Step 3: Separate the DES-type solid-liquid mixture to obtain a DES-type lithium-rich leachate and undissolved slag. The lithium-rich leachate was subjected to ion quantitative analysis, and the results are shown in Table 1.

[0073] Comparative Example 1

[0074] This comparative example provides a method for extracting lithium from a sedimentary lithium ore similar to Example 1, with the only difference being that, in step (2), leaching is performed at room temperature (25° C.) without heat-enhanced leaching. The results are shown in Table 1.

[0075] Comparative Example 2

[0076] This comparative example provides a method for extracting lithium from a sedimentary lithium ore similar to Example 1, except that pure water is used for leaching in step (2). The results are shown in Table 1.

[0077] Table 1

[0078] project Lithium leaching rate / % Example 1 49.56 Example 2 82.06 Example 3 73.34 Example 4 63.84 Comparative Example 1 26.30 Comparative Example 2 21.87

[0079] As can be seen from Table 1, the method of the present invention achieves efficient leaching of lithium from sedimentary clay lithium ore.

[0080] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A green and efficient method for extracting lithium from sedimentary clay lithium ore, characterized in that: The method comprises: Step (1), crushing, grinding, and sieving sedimentary clay lithium ore to obtain millimeter-sized lithium ore powder; Step (2), mixing the millimeter-sized lithium ore powder with a carboxylic acid-based green solvent system and heating to enhance leaching to obtain a lithium-containing solid-liquid mixture; the carboxylic acid-based green solvent system is a carboxylic acid solution or a low eutectic solvent formed by carboxylic acid and choline chloride; Step (3) is to separate the lithium-containing solid-liquid mixture into solid and liquid to obtain a lithium-rich leachate and mixed slag.

2. The method according to claim 1, characterized in that The carboxylic acid is at least one of acetic acid, oxalic acid and citric acid.

3. The method according to claim 1, characterized in that The mass concentration of the carboxylic acid in the carboxylic acid solution is 6-40%, and the total mass concentration of the carboxylic acid and choline chloride in the deep eutectic solvent formed by the carboxylic acid and choline chloride is 55-70%.

4. The method according to claim 1, wherein In the deep eutectic solvent formed by the carboxylic acid and choline chloride, the molar ratio of choline chloride to carboxylic acid is 1:

1.

5. The method according to claim 1, wherein In step (1), the sieving is through a 60-mesh sieve.

6. The method according to claim 1, characterized in that In step (1), the particle size of the millimeter-sized lithium ore powder is less than 0.2 mm.

7. The method according to claim 1, characterized in that In step (2), the mass ratio of the millimeter-sized lithium ore powder to the carboxylic acid-based green solvent system is 1:1 to 15.

8. The method according to claim 1, characterized in that In step (2), the conditions for the heating-enhanced leaching include: a heating temperature of 30 to 70° C., a heating time of 1 to 5 hours, and a stirring speed of 400 to 600 rpm.

9. The method according to claim 1, characterized in that When the carboxylic acid is oxalic acid, the method further comprises: treating the mixed slag to recover the oxalic acid, and using the recovered oxalic acid in a carboxylic acid-based green solvent system.

10. The method according to claim 9, characterized in that The process of treating the mixed slag to recover oxalic acid comprises: mixing the mixed slag with sulfuric acid, precipitating, and solid-liquid separation; cooling the solution obtained by solid-liquid separation, crystallizing the solution, and washing the solution to obtain oxalic acid crystals.

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