A method for extracting lithium carbonate from low-grade tantalum-niobium ore

Abstract

A method for extracting lithium carbonate from low-grade tantalum-niobium ore and its application are disclosed, comprising: S1 Impurity separation: taking low-grade tantalum-niobium ore and crushing it to a particle size of 70-80 μm, separating magnetic minerals from the ore using magnetic separation to obtain primary minerals; S2 Chemical leaching extraction of alkali metals: adding a leaching agent to the primary minerals obtained in S1 to separate lithium-containing solution and solid residue; S3 Separation of alkali metal precipitates: adding sodium carbonate solution to the lithium-containing solution in S2 for neutralization to separate alkali metal precipitates from the lithium-containing solution; S4 Lithium ion recovery: selectively adsorbing lithium ions from the lithium-containing solution after alkali metal precipitate separation in S3 using an ion exchange resin, and desorbing lithium ions from the ion exchange resin by introducing a desorption solution to obtain a high-purity lithium ion solution. This method can not only extract a high-purity lithium ion solution from low-grade tantalum-niobium ore, but also effectively separate valuable metals from low-grade tantalum-niobium ore, achieving efficient utilization of low-grade tantalum-niobium ore.

Description

Technical Field

[0001] This invention relates to the field of lithium carbonate preparation technology, and in particular to a method for preparing lithium carbonate from low-grade tantalum-niobium ore and its application. Background Technology

[0002] With the rapid development of lithium battery technology, the demand for high-purity lithium carbonate continues to grow. However, traditional lithium resource mining often faces problems such as resource waste and environmental pollution. Tantalum-niobium mine waste resources contain abundant alkali metal elements, including lithium, but due to their extremely low grade, traditional extraction processes are costly, inefficient, and have a serious impact on the environment. For example, the separation of magnetic minerals is directly carried away by high magnetic field strength, which may reduce the lithium recovery efficiency by carrying away some lithium-bearing minerals, while also consuming a lot of energy. Lithium ions are treated by directly adding leaching agents without selectively adjusting leaching conditions, resulting in low leaching efficiency. Therefore, developing an environmentally friendly and efficient battery-grade lithium carbonate preparation process is particularly important. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned technical defects and provide a method for preparing lithium carbonate from low-grade tantalum-niobium ore and its application.

[0004] In a first aspect, this application provides a method for preparing lithium carbonate from low-grade tantalum-niobium ore, comprising:

[0005] S1 impurity separation:

[0006] Low-grade tantalum-niobium ore is collected and crushed to a particle size of 70-80 μm. Magnetic minerals are then separated from the low-grade tantalum-niobium ore using magnetic separation to obtain primary minerals. The magnetic field strength is 0.7-0.9 T, and the flow rate of the tantalum-niobium ore is 1-2 m / s. By adjusting the flow rate and magnetic field strength, the effective separation of valuable metals such as tantalum and niobium can be achieved while reducing energy consumption.

[0007] S2 chemical leaching extraction of alkali metals:

[0008] Add a leaching agent to the primary minerals obtained from S1, control the leaching temperature at 75-85℃, the stirring rate at 280-320 r / min, and the leaching time at 110-130 min; separate the lithium-containing solution and solid residue; select a suitable leaching agent and control the concentration, temperature and leaching time of the leaching agent to improve the leaching efficiency.

[0009] S3 separates alkali metal precipitates:

[0010] At room temperature, sodium carbonate solution was added to the lithium-containing S2 solution for neutralization, and alkali metal precipitates in the lithium-containing solution were separated.

[0011] S4 lithium-ion recovery:

[0012] Lithium ions are selectively adsorbed from the lithium-containing solution after the separation of alkali metal precipitates in S3 using an ion exchange resin. The ion exchange resin is a D72 strong acid cation exchange resin, and the resin bed flow rate is controlled at 1 BV / h at room temperature. The adsorption efficiency of lithium is improved by selecting a specific type of resin.

[0013] Lithium ions are desorbed from the ion exchange resin by introducing a desorption solution to obtain a high-purity lithium ion solution.

[0014] In one embodiment, the solid residue from step S2 is ground to a particle size of 100-150 mesh, and a sulfuric acid solution with a concentration of 1.5-2.5 mol / L is added to carry out a leaching reaction. After the reaction is completed, solid-liquid separation is performed to obtain a lithium sulfate solution. The concentration of the sulfuric acid solution is controlled to ensure efficient lithium ion leaching, while also taking into account cost and safety considerations.

[0015] In one embodiment, aluminum hydroxide sol is added to a lithium sulfate solution for purification, wherein the mass ratio of aluminum hydroxide sol to lithium sulfate solution is (1-2):10, to obtain a purified lithium sulfate solution.

[0016] In one embodiment, the weight ratio of the added sulfuric acid solution to the S2 solid residue is 3:1, and the leaching reaction temperature is controlled at 80-120°C; by controlling the leaching reaction temperature, the lithium leaching rate is improved.

[0017] In one embodiment, the purified lithium sulfate solution is evaporated and concentrated under normal pressure to obtain a high-purity lithium sulfate solution.

[0018] The evaporation and concentration temperature is 100-120℃, and the concentration ratio is 5-10 times.

[0019] In one embodiment, in step S2, which separates alkali metal precipitates, the leaching agent is dilute sulfuric acid or hydrochloric acid with a concentration of 0.5 mol / L, and the mass ratio of the leaching agent to the primary mineral is (2.5-3.5):1.

[0020] In one embodiment, in step S3, when separating alkali metal precipitates, the concentration of the sodium carbonate solution is 0.7-0.9 mol / L.

[0021] In one embodiment, during step S3, when separating the alkali metal precipitate, sodium carbonate solution is added to adjust the pH of the lithium-containing solution to 6-7; by adjusting the pH, the lithium recovery rate is improved.

[0022] In one embodiment, in step S4 lithium ion recovery, the desorption solution is a hydrochloric acid solution with a concentration of 1.8-2.2 mol / L, and the temperature of the desorption solution is controlled at 55-65°C; by controlling the concentration and temperature of the desorption solution, the lithium recovery efficiency is improved.

[0023] Secondly, this application also provides the application of the above-mentioned method for extracting lithium carbonate from low-grade tantalum-niobium ore in the preparation of high-purity lithium carbonate.

[0024] The present invention has the following beneficial effects

[0025] The present invention provides a method for preparing lithium carbonate from low-grade tantalum-niobium ore. This method mainly uses waste resources from extremely low-grade tantalum-niobium mines, and achieves comprehensive recovery of alkali metals through key technologies for overall clean recycling and a one-step preparation of lithium sulfate solution. This technology effectively improves the utilization efficiency of waste resources, reduces environmental pollution, and achieves efficient preparation of battery-grade lithium carbonate.

[0026] The proposed method for separating impurities, chemically leaching alkali metals, separating alkali metal precipitates, and recovering lithium ions from low-grade tantalum-niobium ore can improve the extraction purity of lithium carbonate, increase the extraction rate, and reduce production energy consumption and waste generation. By performing multiple purification processes on low-grade tantalum-niobium ore, not only can high-purity lithium ion solutions be extracted, but valuable metals such as tantalum and niobium in the ore can also be effectively separated, achieving efficient utilization of low-grade tantalum-niobium ore and avoiding resource waste and environmental pollution caused by the abundant alkali metal elements in tantalum-niobium ore. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments and examples. It should be understood that these embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the invention. The purpose of providing these embodiments and examples is to make the disclosure of the present invention more thorough and complete. It should also be understood that the present invention can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present invention, and the equivalent forms obtained also fall within the protection scope of this application. Furthermore, numerous specific details are set forth in the following description to provide a fuller understanding of the present invention. It should be understood that the present invention can be implemented without one or more of these details.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for descriptive purposes only and is not intended to be limiting of the invention.

[0029] the term

[0030] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0031] In this document, terms such as "preferred," "better," "more suitable," and "ideal" are merely descriptions of more effective implementation methods or embodiments and should be understood not to limit the scope of protection of this invention. If multiple "preferred" terms appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "preferred" term shall be independent.

[0032] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features. It should be understood that when the chemical composition of a substance is described in a limiting manner, the substance may contain impurities present in normal amounts, including but not limited to impurities inevitably introduced due to the preparation process.

[0033] In this invention, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0034] Unless otherwise specified, the test methods used in the examples and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. The raw materials used in the examples and comparative examples of this invention are as follows:

[0035] Low-grade tantalum-niobium ore: tailings from tantalum-niobium mines, containing an average of 0.15% lithium oxide by mass.

[0036] Examples 1-3: Preparation method of high-purity lithium carbonate:

[0037] S1 impurity separation:

[0038] Low-grade tantalum-niobium ore is taken and crushed to a particle size of 70-80μm. Magnetic minerals are separated from the low-grade tantalum-niobium ore by magnetic separation. Primary minerals are obtained after separation. The magnetic field strength is 0.7-0.9T and the tantalum-niobium ore flow rate is 1-2m / s.

[0039] S2 chemical leaching extraction of alkali metals:

[0040] A leaching agent is added to the primary mineral obtained in S1, and the leaching temperature is controlled at 75-85℃, the stirring rate at 280-320 r / min, and the leaching time at 110-130 min; the lithium-containing solution and solid residue are separated; the leaching agent is dilute sulfuric acid with a concentration of 0.5 mol / L, and the mass ratio of the leaching agent to the primary mineral is (2.5-3.5):1;

[0041] The solid residue from step S2 is ground to a particle size of 100 mesh, and a 2 mol / L sulfuric acid solution is added to carry out a leaching reaction. After the reaction is completed, solid-liquid separation is performed to obtain a lithium sulfate solution. The weight ratio of the added sulfuric acid solution to the solid residue from S2 is 3:1, and the leaching reaction temperature is controlled at 100°C.

[0042] Aluminum hydroxide sol is added to a lithium sulfate solution for purification, wherein the mass ratio of aluminum hydroxide sol to lithium sulfate solution is (1-2):10; a purified lithium sulfate solution is obtained; the purified lithium sulfate solution is evaporated and concentrated under normal pressure to obtain a high-purity lithium sulfate solution; the evaporation and concentration temperature is 100-120℃, and the concentration factor is 5-10 times.

[0043] S3 separates alkali metal precipitates:

[0044] At room temperature, sodium carbonate solution is added to the lithium-containing solution S2 for neutralization to separate alkali metal precipitates from the lithium-containing solution; the concentration of the sodium carbonate solution is 0.7-0.9 mol / L; the pH value of the lithium-containing solution is adjusted to 6-7 by adding sodium carbonate solution;

[0045] S4 lithium-ion recovery:

[0046] Lithium ions are selectively adsorbed from the lithium-containing solution after the separation of alkali metal precipitates in S3 using an ion exchange resin. The ion exchange resin is a D72 strong acid cation exchange resin, and the resin bed flow rate is controlled at 1 BV / h under normal temperature conditions.

[0047] Lithium ions are desorbed from the ion exchange resin by introducing a desorption solution to obtain a high-purity lithium ion solution; the desorption solution is a hydrochloric acid solution with a concentration of 1.8-2.2 mol / L, and the temperature of the desorption solution is controlled at 55-65℃.

[0048] Preparation methods of high-purity lithium carbonate in Comparative Examples 1-6:

[0049] S1 impurity separation:

[0050] Low-grade tantalum-niobium ore is collected and crushed. Magnetic minerals are separated from the low-grade tantalum-niobium ore using magnetic separation. Primary minerals are obtained after separation, and the magnetic field strength and the flow rate of tantalum-niobium ore are controlled.

[0051] S2 chemical leaching extraction of alkali metals:

[0052] A leaching agent is added to the primary minerals obtained in S1, and the leaching temperature, stirring rate, and leaching time are controlled; a lithium-containing solution and solid residue are separated; the leaching agent is dilute sulfuric acid;

[0053] The solid residue from step S2 is ground to a particle size of 100 mesh, and a 2 mol / L sulfuric acid solution is added to carry out a leaching reaction. After the reaction is completed, solid-liquid separation is performed to obtain a lithium sulfate solution. The weight ratio of the added sulfuric acid solution to the solid residue from S2 is 3:1, and the leaching reaction temperature is controlled at 100°C.

[0054] Aluminum hydroxide sol is added to a lithium sulfate solution for purification, and the mass ratio of the aluminum hydroxide sol to the lithium sulfate solution is controlled; a purified lithium sulfate solution is obtained; under normal pressure, the purified lithium sulfate solution is evaporated and concentrated to obtain a high-purity lithium sulfate solution; the temperature and concentration factor of the evaporation and concentration are controlled;

[0055] S3 separates alkali metal precipitates:

[0056] At room temperature, sodium carbonate solution is added to the lithium-containing solution S2 for neutralization to separate alkali metal precipitates from the lithium-containing solution; the concentration of the sodium carbonate solution is controlled; the pH value of the lithium-containing solution is controlled by adding sodium carbonate solution.

[0057] S4 lithium-ion recovery:

[0058] Lithium ions are selectively adsorbed from the lithium-containing solution after the separation of alkali metal precipitates in S3 using an ion exchange resin. The ion exchange resin is a D72 strong acid cation exchange resin, and the resin bed flow rate is controlled at 1 BV / h under normal temperature conditions.

[0059] Lithium ions are desorbed from the ion exchange resin by introducing a desorption solution to obtain a high-purity lithium ion solution; the desorption solution is a hydrochloric acid solution, and the concentration and temperature of the desorption solution are controlled.

[0060] The differences between the preparation methods of the examples and the comparative examples are shown in the table below.

[0061]

[0062] In each of Examples 1-3 and Comparative Examples 1-6, the high-purity lithium sulfate solution prepared in step S2 and the high-purity lithium chloride solution prepared in step S4 were continuously added with 0.2-0.5 mol / L sodium carbonate solution and stirred until no precipitate was formed in the solution. The precipitate in the solution was separated and washed to obtain high-purity lithium carbonate. The lithium carbonate obtained in each example or comparative example was tested using the following various test methods:

[0063] 1. Lithium carbonate purity detection method: ICP-OES method is used to determine impurity components;

[0064] 2. Yield detection method: Calculate the lithium carbonate yield of the examples and comparative examples, that is, the ratio of the amount of lithium carbonate produced to the amount of raw materials consumed;

[0065] 3. Waste discharge: Testing standards: Wastewater and exhaust gas emissions are assessed in accordance with GB8978-1996 "Integrated Wastewater Discharge Standard" and GB16297-1996 "Integrated Emission Standard for Air Pollutants".

[0066]

[0067] The above embodiments demonstrate that the present application's method for separating impurities, chemically leaching alkali metals, separating alkali metal precipitates, and recovering lithium ions from low-grade tantalum-niobium ore can improve the extraction purity of lithium carbonate, increase the extraction rate, and reduce production energy consumption and waste generation. It not only extracts valuable metals such as tantalum and niobium but also efficiently recovers alkali metal lithium, achieving high-value utilization of waste resources.

Claims

1. A method for extracting lithium carbonate from low-grade tantalum-niobium ore, characterized in that, include: S1 impurity separation: Low-grade tantalum-niobium ore is collected and crushed to a particle size of 70-80 μm. Magnetic minerals are separated from the low-grade tantalum-niobium ore using magnetic separation. Primary minerals are obtained after separation. The magnetic field strength is 0.7-0.9 T, and the flow velocity of the tantalum-niobium ore is 1-2 m / s. The low-grade tantalum-niobium ore is tailings from a tantalum-niobium mine and contains an average of 0.15% lithium oxide by mass. S2 chemical leaching extraction of alkali metals: A leaching agent is added to the primary mineral obtained in S1, and the leaching temperature is controlled at 75-85℃, the stirring rate at 280-320 r / min, and the leaching time at 110-130 min; the lithium-containing solution and solid residue are separated; the leaching agent is dilute sulfuric acid or hydrochloric acid with a concentration of 0.5 mol / L, and the mass ratio of the leaching agent to the primary mineral is (2.5-3.5):1; S3 separates alkali metal precipitates: At room temperature, sodium carbonate solution is added to the lithium-containing solution S2 for neutralization, the pH value of the lithium-containing solution is adjusted to 6-7, and the alkali metal precipitate in the lithium-containing solution is separated. S4 lithium-ion recovery: Lithium ions were selectively adsorbed from the lithium-containing solution after the alkali metal precipitate was separated from S3 using an ion exchange resin. The ion exchange resin was a D72 strong acid cation exchange resin, and the resin bed flow rate was controlled at 1 BV / h at room temperature. Lithium ions are desorbed from the ion exchange resin by introducing a desorption solution to obtain a high-purity lithium ion solution.

2. The method for extracting lithium carbonate from low-grade tantalum-niobium ore according to claim 1, characterized in that, The solid residue from step S2 is ground to a particle size of 100-150 mesh, and a sulfuric acid solution with a concentration of 1.5-2.5 mol / L is added to carry out a leaching reaction. After the reaction is completed, solid-liquid separation is performed to obtain a lithium sulfate solution.

3. The method for extracting lithium carbonate from low-grade tantalum-niobium ore according to claim 2, characterized in that, Aluminum hydroxide sol was added to the lithium sulfate solution for purification, wherein the mass ratio of aluminum hydroxide sol to lithium sulfate solution was (1-2):10, to obtain a purified lithium sulfate solution.

4. The method for extracting lithium carbonate from low-grade tantalum-niobium ore according to claim 2, characterized in that, The ratio of the amount of sulfuric acid solution added to the weight of S2 solid residue is 3:1, and the leaching reaction temperature is controlled at 80-120℃.

5. The method for extracting lithium carbonate from low-grade tantalum-niobium ore according to claim 3, characterized in that, Under normal pressure, the purified lithium sulfate solution was evaporated and concentrated to obtain a high-purity lithium sulfate solution. The evaporation and concentration temperature is 100-120℃, and the concentration ratio is 5-10 times.

6. The method for extracting lithium carbonate from low-grade tantalum-niobium ore according to claim 1, characterized in that, In step S3, during the separation of alkali metal precipitates, the concentration of the sodium carbonate solution is 0.7-0.9 mol / L.

7. The method for extracting lithium carbonate from low-grade tantalum-niobium ore according to claim 1, characterized in that, In step S4, lithium ion recovery, the desorption solution is a hydrochloric acid solution with a concentration of 1.8-2.2 mol / L, and the temperature of the desorption solution is controlled at 55-65℃.

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