Method for extracting lithium from lepidolite

Abstract

The invention discloses a method for extracting lithium from lepidolite, which comprises the following steps: uniformly mixing lepidolite, coke powder, carbide slag and sodium cellulose according to a mass ratio of 1: (0.25-0.6): (0.25-0.6): (0.2-0.4), obtaining a spherical material through a pelletizer, carrying out microwave drying treatment on the spherical material to remove moisture, and carrying out reduction calcination at 700-1050 DEG C, water is added into the clinker according to the liquid-solid ratio of 2: 1-5: 1 for ball milling treatment, leaching of lithium is completed while ore grinding is conducted, then solid-liquid separation is conducted through filter pressing to obtain a lithium-containing solution, and the lithium-containing solution is subjected to purification and impurity removal, concentration and lithium precipitation, carbonization and refining, drying and smashing to obtain a battery-grade lithium carbonate product. According to the method, microwave drying and reduction calcination are adopted, so that the materials can be quickly and uniformly heated, the reaction efficiency is improved, the energy consumption is reduced, the resource utilization of the waste residues is realized, and the environmental pollution is reduced.

Description

Technical Field

[0001] The invention relates to the field of extraction technology, 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 growing. As one of the important sources of lithium resources, the research and development of lithium extraction technology of lithium mica is of great significance. Patent CN 115821060 B reports a method for extracting lithium from lithium mica by staged roasting of a composite salt method. The method mixes lithium mica powder with a variety of salts evenly, roasts in stages, and leaches to obtain a lithium solution. Patent CN 117819578 A reports a method for preparing lithium carbonate by agglomeration roasting of lithium mica, wherein lithium mica, sodium sulfate, calcium hydroxide, and water are mixed and then mixed with sulfur, and then roasted, leached, concentrated, impurity-removed, and lithium carbonate is obtained. Patent CN 114752784B reports a process for improving the lithium leaching rate in lithium mica, wherein activators such as oxalic acid and pore-forming agents such as ammonium chloride are added to the lithium mica for ball milling activation, and then defluorinated by pre-sintering and roasting, and finally pressure cooking, separation and purification, and carbonization of lithium precipitation are performed to obtain lithium carbonate.

[0003] The common lithium extraction process from lepidolite has many problems, such as complex process, high energy consumption, fluorine environmental pollution, etc. Therefore, it is very important to develop a new process for lithium extraction from lepidolite that is efficient, environmentally friendly and economical. Summary of the invention

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

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

[0006] Step 1, mixing and pelletizing: mixing 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 obtaining a spherical material by a pelletizing machine;

[0007] 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.

[0008] 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.

[0009] Step 4, separation: solid-liquid separation by filter pressing to obtain a lithium-containing solution;

[0010] Step 5, preparation of lithium carbonate: the lithium-containing solution is purified and impurities removed, concentrated and lithium precipitated, carbonized and refined, and dried and crushed to obtain a battery-grade lithium carbonate product.

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

[0012] Further, in step 3, the water dosage, the ball mill speed is 50-100 rpm, the grinding time is 1-3h, and the filter pressure is 0.5-1.2MPa.

[0013] By adopting the above scheme, the method for extracting lithium from lepidolite disclosed in the present invention has the following advantages:

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

[0015] 2. The present invention realizes efficient lithium extraction from different lepidolite ores by adjusting the mixing and balling ratio and the conditions of microwave drying and reduction calcination, wherein the filter residue can be used as a cement admixture, thereby improving the comprehensive utilization rate of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is an overall flow chart of a method for extracting lithium from lepidolite; DETAILED DESCRIPTION

[0017] The following describes 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, which are exemplary descriptions, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0018] like Figure 1 As shown, a method for extracting lithium from lepidolite according to the present invention comprises the following steps: Example 1

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

[0020] 1. Mixing and pelletizing: Evenly mix lepidolite with coke powder, carbide slag and sodium cellulose acid in the ratio of 1:0.5:0.5:0.3 and make it into spherical materials through a pelletizing machine.

[0021] 2. Microwave drying and reduction calcination: The prepared spherical material is subjected to a microwave drying treatment to remove moisture, and then subjected to a microwave reduction calcination at a temperature of 1050°C to prepare clinker. The microwave power is 50kW and the time is 15 minutes.

[0022] 3. Ball milling and filter pressing: add water to the calcined clinker according to a certain liquid-solid ratio, then perform ball milling, complete lithium leaching while grinding, and then perform solid-liquid separation by filter pressing to obtain lithium-containing solution and filter residue, which can be used as cement admixture. The water liquid-solid ratio is 2:1, the ball mill speed is 100 rpm, the grinding time is 1h, and the filter pressing pressure is 0.5MPa.

[0023] 4. Preparation of lithium carbonate: The lithium-containing solution is purified and impurities removed, concentrated and lithium precipitated, carbonized and refined, dried and crushed to obtain 28.55g of lithium carbonate product with a main lithium carbonate content of 99.75%.

[0024] Embodiment 2:

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

[0026] 1. Mixing and pelletizing: Mix lepidolite with coke powder, carbide slag and sodium cellulose acid in the ratio of 1:0.25:0.6:0.4 and make it into spherical materials through a pelletizing machine.

[0027] 2. Microwave drying and reduction calcination: The prepared spherical material is subjected to a microwave drying process to remove moisture, and then subjected to a microwave reduction calcination process at a temperature of 700°C to prepare clinker. The microwave power is 30kW and the time is 45 minutes.

[0028] 3. Ball milling and filter pressing: Add water to the calcined clinker according to a certain liquid-solid ratio, then perform ball milling, complete lithium leaching while grinding, and then perform solid-liquid separation through filter pressing to obtain lithium-containing solution and filter residue, which can be used as cement admixture. The water liquid-solid ratio is 4:1, the ball mill speed is 50 rpm, the grinding time is 1.5h, and the filter pressing pressure is 1.0MPa.

[0029] 4. Preparation of lithium carbonate: The lithium-containing solution is purified and impurities removed, concentrated and lithium precipitated, carbonized and refined, dried and crushed to obtain 29.30g of lithium carbonate product with a main lithium carbonate content of 99.84%.

[0030] Embodiment 3:

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

[0032] 1. Mixing and pelletizing: Mix lepidolite with coke powder, carbide slag and sodium cellulose acid in the ratio of 1:0.6:0.25:0.2 and make it into spherical materials through a pelletizing machine.

[0033] 2. Microwave drying and reduction calcination: The prepared spheres are subjected to a microwave drying process to remove moisture, and then subjected to a microwave reduction calcination process at a temperature of 950°C to prepare clinker. The microwave power is 40kW and the time is 30 minutes.

[0034] 3. Ball milling and filter pressing: Add water to the calcined clinker according to a certain liquid-solid ratio, then perform ball milling, complete lithium leaching while grinding, and then perform solid-liquid separation through filter pressing to obtain lithium-containing solution and filter residue, which can be used as cement admixture. The water liquid-solid ratio is 5:1, the ball mill speed is 90 rpm, the grinding time is 3h, and the filter pressing pressure is 1.2MPa.

[0035] 4. Preparation of lithium carbonate: After purification and impurity removal, lithium precipitation, carbonization and refining, drying and crushing, the lithium-containing solution was subjected to 57.80 g of lithium carbonate product, with a main lithium carbonate content of 99.74%.

[0036] Through the above multiple implementation plans, 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 using the same lithium ore as Example 1 is that the traditional sulfuric acid method is used to extract lithium;

[0038] Comparative Example 2 and Example 1 use the same lithium ore as Example 1, but the main difference is that traditional limestone is used;

[0039] The lithium leaching rate of the traditional sulfuric acid method for lithium extraction in Comparative Example 1 is 92% to 96%. The amount of lithium carbonate product obtained in Example 3 of the present technical solution is the largest (57.80 g), and the main content reaches 99.74%, showing a higher lithium recovery rate and product purity. Compared with the traditional sulfuric acid method, the present technical solution reduces the amount of slag during the treatment process, reduces the requirements for the corrosion resistance of the equipment, and improves the product purity.

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

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

[0042]

[0043] As shown in Table 1, the traditional sulfuric acid method produces high-purity lithium carbonate, but impurities may be mixed in the process, requiring further purification steps. The limestone method is difficult to extract lithium due to the complex structure of lithium mica components, and the main content of lithium carbonate may be low. In summary, this technical solution achieves high-efficiency, high-recovery and high-product purity lithium extraction through microwave drying and reduction calcination technology.

[0044] The coke powder (C), carbide slag (CaC2) and sodium cellulose acid in the present invention are simple and easy to obtain materials, and are waste utilization; the coke powder and carbide slag absorb heat quickly, and through microwave internal source heating, the temperature rises quickly, the time is short, and the energy consumption is low, and the temperature can be heated to 700-1050°C in a short time.

[0045] During the microwave roasting process, fluorine in lithium mica is removed, and fluorine reacts with carbide slag to generate CaF2, thereby forming CaF2, which reduces fluorine pollution. At the same time, it protects the reducing atmosphere, promotes the reduction reaction of coke powder and defluorinated lithium mica to generate lithium metal. Finally, when adding water to the ball mill, the lithium metal is constantly in contact with the air through the grinding process, and it is very easy to oxidize and enter the aqueous solution, thereby efficiently obtaining a lithium solution with a low impurity content. The filter residue is used as a cement admixture, realizing the resource utilization of waste residue and reducing environmental pollution.

[0046] During the microwave roasting process, fluorine in lithium mica is removed, and fluorine reacts with carbide slag to generate CaF2, thereby forming CaF2, which reduces fluorine pollution. At the same time, it protects the reducing atmosphere, promotes the reduction reaction of coke powder and defluorinated lithium mica to generate lithium metal. Finally, when adding water to the ball mill, the lithium metal is constantly in contact with the air through the grinding process, and it is very easy to oxidize and enter the aqueous solution, thereby efficiently obtaining a lithium solution with a low impurity content. The filter residue is used as a cement admixture, realizing the resource utilization of waste residue and reducing environmental pollution.

[0047] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by 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: mixing 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 obtaining a 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: the lithium-containing solution is purified and impurities removed, concentrated and lithium precipitated, carbonized and refined, and dried and crushed to obtain a battery-grade lithium carbonate product.

2. A method for extracting lithium from lepidolite according to claim 1, characterized in that: In step 2, the microwave power is 30 kW to 50 kW, and the time is 15 to 60 min.

3. The method for extracting lithium from lepidolite according to claim 1, characterized in that: In step 3, the water dosage, the ball mill speed is 50-100 rpm, the grinding time is 1-3h, and the filter pressure is 0.5-1.2MPa.

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