A method for extracting lithium from lepidolite

Abstract

The present invention discloses a method for extracting lithium from lepidolite, which includes uniformly mixing lepidolite, coke powder, carbide slag, and sodium carboxymethyl cellulose in a mass ratio of 1:(0.25 - 0.6):(0.25 - 0.6):(0.2 - 0.4) to obtain spherical materials through a pelletizing machine; subjecting the spherical materials to microwave drying treatment to remove moisture, and performing reduction calcination at a temperature of 700 - 1050 °C to prepare clinker; subjecting the clinker to ball milling treatment by adding water according to a liquid-solid ratio of 2:1 - 5:1, and completing the leaching of lithium while grinding the ore, and then performing solid-liquid separation by pressure filtration to obtain a lithium-containing solution; and obtaining battery-grade lithium carbonate products after purifying and removing impurities, concentrating and precipitating lithium, carbonizing and refining, and drying and pulverizing the lithium-containing solution. The present invention adopts microwave drying and reduction calcination, which can heat the materials quickly and uniformly, improve the reaction efficiency, reduce energy consumption, realize the resource utilization of waste residues, and reduce environmental pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of extraction, and in particular to a method for extracting lithium from lepidolite. Background Art

[0002] With the rapid development of the new energy industry, the demand for lithium is increasing day by day. As an important source of lithium resources, the research and development of the lithium extraction process from lepidolite is of great significance. Patent CN 115821060 B reports a method for extracting lithium from lepidolite by staged roasting with a composite salt method. In this method, lepidolite powder is mixed evenly with multiple salts, roasted in stages, and leached to obtain a lithium solution. Patent CN 117819578 A reports a method for preparing lithium carbonate by pelletizing and roasting lepidolite. Lepidolite, sodium sulfate, calcium hydroxide, and water are mixed and then mixed with sulfur, and then lithium carbonate is obtained through roasting, leaching, concentration, impurity removal, and lithium precipitation. Patent CN 114752784 B reports a process for improving the lithium leaching rate from lepidolite. Activators such as oxalic acid and pore-forming agents such as ammonium chloride are added to lepidolite for ball milling activation, then pre-sintered and roasted to remove fluorine, and finally lithium carbonate is obtained through autoclaving, separation and purification, and carbonization and lithium precipitation.

[0003] At present, there are many problems in the common lithium extraction processes from lepidolite, such as complex processes, high energy consumption, and fluorine environmental pollution. Therefore, it is very important to develop a new, efficient, environmentally friendly, and economical lithium extraction process from lepidolite. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the present invention proposes a method for extracting lithium from lepidolite to solve the technical problems to be solved.

[0005] To achieve the above object, the present invention provides a method for extracting lithium from lepidolite, which specifically includes the following steps:

[0006] Step 1, mixing and pelletizing: Mix lepidolite, coke powder, carbide slag, and sodium carboxymethyl cellulose evenly according to a mass ratio of 1:(0.25 - 0.6):(0.25 - 0.6):(0.2 - 0.4), and obtain spherical materials through a pelletizing machine;

[0007] Step 2, microwave drying and reduction roasting: Perform microwave drying treatment on the spherical materials to remove moisture, and perform reduction roasting at a temperature of 700 - 1050 °C to prepare clinker.

[0008] Step 3, ball milling and pressure filtration: Add water to the clinker according to a liquid-solid ratio of 2:1 - 5:1 for ball milling treatment, and complete the leaching of lithium while grinding the ore.

[0009] Step 4, separation: Perform solid-liquid separation through pressure filtration to obtain a lithium-containing solution;

[0010] Step 5: Preparation of lithium carbonate: The lithium-containing solution is purified to remove impurities, concentrated to precipitate lithium, carbonized and refined, and dried and pulverized to obtain a battery-grade lithium carbonate product.

[0011] Further, in Step 2, the microwave power is 30 kW to 50 kW, and the time is 15 - 60 min.

[0012] Further, in Step 3, the ball milling speed of the water consumption is 50 - 100 revolutions per minute, the abrasive time is 1 - 3 h, and the pressure of pressure filtration is 0.5 - 1.2 MPa.

[0013] Adopting the above solution, a method for extracting lithium from lepidolite disclosed by the present invention has the following advantages:

[0014] 1. The present invention adopts microwave drying and reduction roasting, which can heat the materials quickly and evenly, improve the reaction efficiency, reduce energy consumption, realize the resource utilization of waste residues, and reduce environmental pollution.

[0015] 2. By adjusting the ratio of mixed pelletizing and the conditions of microwave drying and reduction roasting, the present invention realizes the efficient extraction of lithium from different lepidolite ores. The filter residue can be used as a cement admixture, improving the comprehensive utilization rate of resources. Description of the Drawings

[0016] Figure 1 is the overall flow chart of a method for extracting lithium from lepidolite of the present invention; Detailed Embodiments

[0017] The following introduces the embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and these embodiments are described exemplarily. The protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0018] As Figure 1 shown, a method for extracting lithium from lepidolite of the present invention includes the following steps: Example 1

[0019] Take 1 kg of lepidolite ore from a certain place, where the Li₂O content is 1.36%

[0020] 1. Mixed pelletizing: Mix lepidolite, coke powder, carbide slag, and sodium carboxymethyl cellulose evenly in a ratio of 1:0.5:0.5:0.3, and make spherical materials through a pelletizing machine.

[0021] 2. Microwave drying and reduction roasting: Perform a one-stage microwave drying treatment on the formed spherical materials to remove moisture, and then perform a one-stage microwave reduction roasting at a temperature of 1050 °C to prepare clinker. The microwave power is 50 kW, and the time is 15 min.

[0022] 3. Ball milling and pressure filtration: Add water to the calcined clinker according to a certain liquid-solid ratio, then conduct ball milling. During the grinding process, the leaching of lithium is completed. Then, solid-liquid separation is carried out by pressure filtration to obtain a lithium-containing solution and filter residue. The filter residue can be used as a cement admixture. The liquid-solid ratio of water usage is 2:1, the ball milling speed is 100 revolutions per minute, the grinding time is 1 h, and the pressure of pressure filtration is 0.5 MPa.

[0023] 4. Preparation of lithium carbonate: After the lithium-containing solution undergoes purification and impurity removal, concentration and lithium precipitation, carbonization and refining, and drying and pulverization, 28.55 g of lithium carbonate product is obtained, and the main content of lithium carbonate is 99.75%.

[0024] Example 2:

[0025] Take 1 kg of lepidolite ore from a certain place, and the Li2O content is 1.45%.

[0026] 1. Mixing and pelletizing: Mix lepidolite with coke powder, carbide slag, and sodium carboxymethyl cellulose evenly according to the ratio of 1:0.25:0.6:0.4, and make spherical materials through a pelletizing machine.

[0027] 2. Microwave drying and reduction calcination: Conduct a one-stage microwave drying treatment on the formed spherical materials to remove moisture, and then conduct a one-stage microwave reduction calcination at a temperature of 700 °C to prepare clinker. The microwave power is 30 kW and the time is 45 min.

[0028] 3. Ball milling and pressure filtration: Add water to the calcined clinker according to a certain liquid-solid ratio, then conduct ball milling. During the grinding process, the leaching of lithium is completed. Then, solid-liquid separation is carried out by pressure filtration to obtain a lithium-containing solution and filter residue. The filter residue can be used as a cement admixture. The liquid-solid ratio of water usage is 4:1, the ball milling speed is 50 revolutions per minute, the grinding time is 1.5 h, and the pressure of pressure filtration is 1.0 MPa.

[0029] 4. Preparation of lithium carbonate: After the lithium-containing solution undergoes purification and impurity removal, concentration and lithium precipitation, carbonization and refining, and drying and pulverization, 29.30 g of lithium carbonate product is obtained, and the main content of lithium carbonate is 99.84%.

[0030] Example 3:

[0031] Take 1 kg of lepidolite ore from a certain place, and the Li2O content is 2.60%.

[0032] 1. Mixing and pelletizing: Mix lepidolite with coke powder, carbide slag, and sodium carboxymethyl cellulose evenly according to the ratio of 1:0.6:0.25:0.2, and make spherical materials through a pelletizing machine.

[0033] 2. Microwave drying and reduction calcination: The formed spherical objects are subjected to a one-stage microwave drying process to remove moisture, and then a one-stage microwave reduction calcination is carried out at a temperature of 950 °C to prepare the clinker. The microwave power is 40 kW and the time is 30 min.

[0034] 3. Ball milling and pressure filtration: The calcined clinker is added with water according to a certain liquid-solid ratio, and then ball milling is carried out. The leaching of lithium is completed during the grinding, and then solid-liquid separation is carried out by pressure filtration to obtain a lithium-containing solution and filter residue. The filter residue can be used as a cement admixture. The liquid-solid ratio of water consumption is 5:1, the ball milling speed is 90 revolutions per minute, the grinding time is 3 h, and the pressure of pressure filtration is 1.2 MPa.

[0035] 4. Preparation of lithium carbonate: After the lithium-containing solution is purified, concentrated, precipitated, carbonized, refined, dried and pulverized, 57.80 g of lithium carbonate product is obtained, and the main content of lithium carbonate is 99.74%.

[0036] Through the above-mentioned multiple implementation schemes, it can be proved that the process of the present invention has good stability and repeatability, can effectively extract lithium metal from lepidolite, and prepare lithium carbonate products.

[0037] The main difference between Comparative Example 1 and Example 1 in using the same lithium ore as in Example 1 is that the traditional sulfuric acid method is used for lithium extraction;

[0038] The main difference between Comparative Example 2 and Example 1 in using the same lithium ore as in Example 1 is that traditional limestone is used;

[0039] The lithium leaching rate of the traditional sulfuric acid method for lithium extraction in Comparative Example 1: 92% - 96%. The largest amount of lithium carbonate product (57.80 g) is obtained in Example 3 of this technical solution, and the main content reaches 99.74%, showing a high lithium recovery rate and product purity. Compared with the traditional sulfuric acid method, this technical solution reduces the amount of slag during the treatment process, reduces the requirement for the anti-corrosion performance of equipment, and improves the product purity at the same time.

[0040] Compared with the traditional limestone method in Comparative Example 2, this technical solution shows better performance in terms of energy consumption and comprehensive utilization of resources in Example 3, and the reuse of filter residue reduces the generation of waste.

[0041] Table 1 shows the comparison test results of lithium separation schemes in Examples 1 - 3 and Comparative Examples 1 - 2 / %

[0042]

[0043] As shown in Table 1, high-purity lithium carbonate is produced by the traditional sulfuric acid method, but impurities may be mixed in during the process and further purification steps are required. Due to the complex composition and structure of lepidolite, the difficulty of lithium extraction by the limestone method is relatively high, and the main content of lithium carbonate may be relatively low. In summary, through the microwave drying and reduction calcination technologies, the present technical solution realizes high-efficiency, high-recovery-rate, and high-product-purity lithium extraction.

[0044] The coke powder (C), carbide slag (CaC2), and sodium carboxymethyl cellulose in the present invention are simple and easily available materials, which belong to waste utilization. Among them, the coke powder and carbide slag absorb heat quickly. Through microwave internal heating, the temperature rises quickly, the time is short, and the energy consumption is low, and it can be heated to 700 - 1050 °C in a short time.

[0045] During the microwave roasting process, fluorine in lepidolite escapes, and fluorine reacts with carbide slag to form CaF2, thus reducing fluorine pollution. At the same time, it protects the reducing atmosphere and promotes the reduction reaction between coke powder and de-fluorinated lepidolite to generate lithium metal. Finally, during the water milling treatment, through continuous contact with air during the grinding process, lithium metal is extremely easy to oxidize and enter the aqueous solution, so that a lithium solution with low impurity content can be obtained efficiently. The filter residue is used as a cement admixture, realizing the resource utilization of waste residues and reducing environmental pollution.

[0046] During the microwave roasting process, fluorine in lepidolite escapes, and fluorine reacts with carbide slag to form CaF2, thus reducing fluorine pollution. At the same time, it protects the reducing atmosphere and promotes the reduction reaction between coke powder and de-fluorinated lepidolite to generate lithium metal. Finally, during the water milling treatment, through continuous contact with air during the grinding process, lithium metal is extremely easy to oxidize and enter the aqueous solution, so that a lithium solution with low impurity content can be obtained efficiently. The filter residue is used as a cement admixture, realizing the resource utilization of waste residues and reducing environmental pollution.

[0047] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for extracting lithium from lepidolite, characterized in that: The following steps are involved: Step 1, mixing and pelletizing: mix lepidolite with coke powder, carbide slag and sodium cellulose in a mass ratio of 1: (0.25-0.6): (0.25-0.6): (0.2-0.4) and obtain spherical material by a pelletizing machine; Step 2, microwave drying and reduction calcination: subjecting the spherical material to microwave drying to remove moisture, and reduction calcining at a temperature of 700-1050° C. to prepare clinker; Step 3, ball milling and filter pressing: the clinker is ball milled with water at a liquid-solid ratio of 2:1-5:1, and lithium is leached while grinding. Step 4, separation: solid-liquid separation by filter pressing to obtain a lithium-containing solution; Step 5, preparation of lithium carbonate: purifying and removing impurities from the lithium-containing solution, concentrating and precipitating lithium, carbonizing and refining, drying and crushing to obtain a battery-grade lithium carbonate product; The microwave power is 30kW~50kW, and the time is 15-60min; The water dosage, ball mill speed is 50-100 rpm, grinding time is 1-3h, and filter pressure is 0.5-1.2MPa.

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