A method for extracting lithium and beryllium from lepidolite concentrate

Abstract

The present invention provides a method for extracting lithium and beryllium from lepidolite concentrate, and relates to the technical field of lithium extraction from concentrate. The method first grinds the lepidolite concentrate with auxiliary materials and then roasts it at high temperature. The roasted clinker is then leached with water, and a leachate and a leach residue are obtained after solid-liquid separation. Finally, a neutralizer is added to the leachate, and the pH of the leachate is adjusted to 8 to precipitate impurities such as iron, aluminum, beryllium, and manganese. The solid-liquid separation is performed to obtain a decontamination liquid and a neutralization residue. The addition of auxiliary materials in the present invention can selectively replace the lithium and beryllium elements in the lepidolite, while the content of other impurity metal elements in the leachate is low, which is convenient for the subsequent decontamination process. After neutralization and decontamination, most of the beryllium in the mineral can be effectively enriched in a small amount of neutralization residue, which can be used for subsequent beryllium extraction.

Description

Technical Field

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

[0002] Lithium is the lightest metal in nature, with a relative atomic mass of 6.941. It has active chemical properties and usually exists in the form of oxides in nature. It is widely used as lithium-ion batteries to provide the required energy for electric vehicles, portable electronic devices, etc.

[0003] Currently, the common lithium mineral resources used for lithium extraction are divided into brine-type lithium ores and pegmatite-type lithium ores. Pegmatite-type lithium ores include lithium-bearing ores such as lepidolite, spodumene, petalite, and ferrolithium mica. Spodumene ore has the highest lithium grade and can be extracted using the sulfuric acid method after high-temperature transformation. Lepidolite, on the other hand, has a relatively low lithium grade. Due to differences in elemental composition and structure between lepidolite and spodumene, sulfuric acid extraction of lithium from lepidolite results in the simultaneous dissolution of large amounts of aluminum and iron, making subsequent impurity removal difficult and resulting in low lithium leaching rates.

[0004] Due to these differences, the main industrial process for extracting lithium from lepidolite is the sulfate process. This process is highly mature, and commonly used sulfate auxiliary materials include sodium sulfate and potassium sulfate. However, the sulfate process alters the mineral structure, converting a large amount of toxic elements in the lithium slag, such as beryllium, thallium, and arsenic, into active forms. This leads to high leaching toxicity, making the lithium slag difficult to dispose of, resulting in wasted resources and increased environmental costs for enterprises.

[0005] The invention can not only effectively extract lithium element from lepidolite mineral, but also selectively extract beryllium element therein and enrich it in a small amount of neutralization slag through a simple neutralization process. Summary of the Invention

[0006] In order to solve the problem of excessive beryllium leaching toxicity in lithium slag disposal in the prior art, the present invention provides a method for extracting lithium and beryllium from lepidolite concentrate. The technical solution is as follows:

[0007] S1. Calcination:

[0008] The lepidolite concentrate is fully mixed with auxiliary materials, and then roasted and transformed at high temperature to transform lithium oxide and beryllium oxide in the lepidolite into lithium sulfate and beryllium sulfate;

[0009] S2, leaching:

[0010] Grinding the clinker after roasting in step S1, leaching with water, and performing solid-liquid separation to obtain leachate and leach residue;

[0011] S3, neutralization and impurity removal:

[0012] A neutralizing agent is added to the leachate obtained in step S2 to adjust the pH of the leachate to 8, and metals such as aluminum, iron, manganese, and beryllium in the leachate are precipitated. After precipitation, solid-liquid separation is performed to obtain a decontamination liquid and a neutralization slag. Lithium, potassium, etc. remain in the decontamination liquid, while beryllium, aluminum, iron, and manganese are enriched in the neutralization slag.

[0013] In step S1, the mass ratio of the auxiliary material to the lepidolite concentrate is 0.5-1, and the particle size of the lepidolite concentrate is 50-80 mesh.

[0014] The auxiliary material in step S1 is at least one of potassium bisulfate and sodium bisulfate.

[0015] In step S1, the calcination temperature is 900° C. to 1000° C., and the calcination time is 30 min to 90 min.

[0016] The heating rate during calcination in step S1 is 5-10°C / min, and the calcination reaction is naturally cooled to room temperature after completion.

[0017] In the step S2, the calcined clinker is ground to a particle size of 60-80 mesh.

[0018] During the leaching in step S2, the liquid-to-solid ratio is 2:1, and the leaching is carried out at room temperature for 1 hour.

[0019] The neutralizing agent in step S3 is one of potassium carbonate, sodium carbonate and ammonium bicarbonate.

[0020] The leached residue obtained in step S2 is washed with water and then filtered, and the process is repeated twice to obtain lithium residue.

[0021] The neutralized residue obtained in step S3 is washed with water and then filtered, and the process is repeated twice to obtain beryllium-containing waste residue.

[0022] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0023] (1) Low environmental pollution: The traditional sulfuric acid method for extracting lithium will react with fluoride ions in mica to produce hydrogen fluoride gas, which not only corrodes equipment but also causes serious pollution to the environment. The present invention does not have these concerns.

[0024] (2) High lithium and beryllium leaching rates: Using the preferred process parameters of the present invention, a lithium leaching rate of >97% and a beryllium leaching rate of >85% can be achieved.

[0025] (3) The experimental process is simple: The experimental process of the present invention is simple and similar to the existing sulfate process, and can be easily applied to industrial production.

[0026] (4) Beryllium can be effectively enriched: By selecting a suitable neutralizing agent, beryllium can be enriched in a small amount of neutralization slag. Depending on the beryllium content in the lepidolite mineral, beryllium can be enriched 20 to 100 times. The beryllium content in the neutralization slag is 0.2% to 4%, which can be used for further extraction of beryllium, making the beryllium in the lepidolite mineral a resource. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 The present invention provides a flow chart of a method for extracting lithium and beryllium from lepidolite concentrate. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0030] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as an "exemplary" in the present invention should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. Furthermore, in the embodiments of the present invention, "and / or" can mean both or either of the two.

[0031] In the embodiments of the present invention, sometimes a subscript such as W1 may be written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are the same.

[0032] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0033] The embodiment of the present invention provides a method for extracting lithium and beryllium from lepidolite concentrate. Figure 1 The process flow chart of extracting lithium and beryllium from lepidolite concentrate shown in FIG. 1 may include the following steps:

[0034] S1. Calcination:

[0035] The lepidolite concentrate is fully mixed with auxiliary materials, and then roasted and transformed at high temperature to transform lithium oxide and beryllium oxide in the lepidolite into lithium sulfate and beryllium sulfate;

[0036] S2, leaching:

[0037] Grinding the clinker after roasting in step S1, leaching with water, and performing solid-liquid separation to obtain leachate and leach residue;

[0038] S3, neutralization and impurity removal:

[0039] A neutralizing agent is added to the leachate obtained in step S2 to adjust the pH of the leachate to 8. After precipitation, solid-liquid separation is performed to obtain a decontaminated liquid and a neutralized residue.

[0040] The following will be described in conjunction with specific embodiments.

[0041] Example 1

[0042] This embodiment provides a method for extracting lithium and beryllium from lepidolite concentrate, comprising the following steps:

[0043] Roasting and Leaching: Lepidolite concentrate was obtained from a mixed mica ore sourced from an enterprise in Yichun City, Jiangxi Province. The composition is shown in Table 1. 20 g of lepidolite concentrate was thoroughly ground and mixed with 14 g of potassium bisulfate. The mixture was then heated to 950°C at a rate of 5°C / min at room temperature for 90 minutes and then naturally cooled to room temperature. The transformed clinker was ground and weighed. Water was added at a liquid-to-solid ratio of 2:1 and leached at room temperature for 1 hour. The resulting leachate, washing solution, and leaching residue were filtered and washed to obtain the following: The leaching rates of the main elements in the lepidolite were: lithium 99.5%, beryllium 98.7%, aluminum 2.9%, iron 4.1%, manganese 97.8%, and no silicon was leached. The composition of the leaching mother liquor is shown in Table 2.

[0044] Table 1 Composition of lepidolite concentrate

[0045]

[0046] Table 2 Composition of leaching liquor

[0047]

[0048] Neutralization and impurity removal: Solid potassium carbonate was gradually added to the leachate while stirring, adjusting the pH to 8. The neutralized residue was filtered to obtain the impurity removal mother liquor. After two washes of the neutralized residue, the lithium recovery rate reached 99.83%, with virtually no lithium loss. The composition of the impurity removal liquor is shown in Table 3. The composition of the neutralized residue is shown in Table 4. As can be seen, beryllium is enriched over 20 times compared to the lepidolite concentrate.

[0049] Table 3 Composition of neutralization and impurity removal liquid

[0050]

[0051] Table 4 Composition of neutralized slag

[0052]

[0053] Example 2

[0054] This embodiment provides a method for extracting lithium and beryllium from lepidolite concentrate, comprising the following steps:

[0055] Roasting and Leaching: Lepidolite concentrate was obtained from a mixed mica ore sourced from an enterprise in Yichun City, Jiangxi Province. The composition is shown in Table 1. 20 g of lepidolite concentrate and 10 g of potassium bisulfate were weighed, thoroughly ground, and mixed. The mixture was then heated to 1000°C at a rate of 10°C / min at room temperature, roasted for 30 minutes, and then naturally cooled to room temperature. The transformed clinker was ground and weighed. Water was added at a liquid-to-solid ratio of 2:1 and leached at room temperature for 1 hour. The resulting leachate, washing solution, and leaching residue were filtered and washed to obtain the following: leachate, washing solution, and leaching residue. The leaching rates of the main elements in the lepidolite were as follows: lithium leaching rate was 99.0%, beryllium leaching rate was 88.4%, aluminum leaching rate was 5.6%, iron leaching rate was 28.9%, manganese leaching rate was 99.5%, and silicon was not leached. The composition of the leaching mother liquor is shown in Table 5.

[0056] Table 5 Leaching liquor composition

[0057]

[0058] Neutralization and impurity removal: Solid potassium carbonate was gradually added to the leachate while stirring, adjusting the pH to 8. The neutralized residue was filtered to obtain the impurity removal mother liquor. After two washes of the neutralized residue, the lithium recovery rate reached 98.98%, with virtually no lithium loss. The composition of the impurity removal liquor is shown in Table 6. The composition of the neutralized residue is shown in Table 7. As can be seen, beryllium is enriched by more than 20 times compared to the lepidolite concentrate.

[0059] Table 6 Composition of neutralization and impurity removal liquid

[0060]

[0061] Table 7 Composition of neutralized slag

[0062]

[0063] Example 3

[0064] This embodiment provides a method for extracting lithium and beryllium from lepidolite concentrate, comprising the following steps:

[0065] Roasting and Leaching: Lepidolite concentrate was obtained from a mixed mica ore sourced from an enterprise in Yichun City, Jiangxi Province. The composition is shown in Table 1. 20 g of lepidolite concentrate and 20 g of sodium bisulfate were weighed, thoroughly ground, and mixed. The mixture was then heated to 900°C at a rate of 10°C / min at room temperature, roasted for 90 minutes, and then naturally cooled to room temperature. The transformed clinker was ground, weighed, and leached at room temperature for 1 hour using water at a liquid-to-solid ratio of 2:1. The resulting leachate, washing solution, and leaching residue were filtered and washed to obtain the following: leachate, washing solution, and leaching residue. The leaching rates of the main elements in the lepidolite were as follows: lithium leaching rate was 99.1%, beryllium leaching rate was 87.6%, aluminum leaching rate was 6.7%, iron leaching rate was 36.1%, manganese leaching rate was 99.03%, and silicon was not leached. The composition of the leaching mother liquor is shown in Table 8.

[0066] Table 8 Leaching mother liquor composition

[0067]

[0068] Neutralization and impurity removal: Solid potassium carbonate was gradually added to the leachate while stirring, adjusting the pH to 8. The neutralized residue was filtered to obtain the impurity removal mother liquor. After two washes of the neutralized residue, the lithium recovery rate reached 99.83%, with virtually no lithium loss. The composition of the impurity removal liquor is shown in Table 9. The composition of the neutralized residue is shown in Table 10. As can be seen, beryllium was enriched by more than 20 times compared to the lepidolite concentrate.

[0069] Table 9 Composition of neutralization and impurity removal liquid

[0070]

[0071] Table 10 Neutralized slag composition

[0072]

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for extracting lithium and beryllium from lepidolite concentrate, characterized in that: The method comprises: S1. Calcination: The lepidolite concentrate is fully mixed with auxiliary materials, and then roasted and transformed at high temperature to transform lithium oxide and beryllium oxide in the lepidolite into lithium sulfate and beryllium sulfate; S2, leaching: Grinding the clinker after roasting in step S1, leaching with water, and performing solid-liquid separation to obtain leachate and leach residue; S3, neutralization and impurity removal: Adding a neutralizing agent to the leachate obtained in step S2 to adjust the pH of the leachate to 8, and after precipitation, performing solid-liquid separation to obtain a decontaminated liquid and a neutralized residue; The auxiliary material in step S1 is at least one of potassium bisulfate and sodium bisulfate.

2. The method for extracting lithium and beryllium from lepidolite concentrate according to claim 1, wherein In step S1, the mass ratio of the auxiliary material to the lepidolite concentrate is 0.5-1, and the particle size of the lepidolite concentrate is 50-80 mesh.

3. The method for extracting lithium and beryllium from lepidolite concentrate according to claim 1, wherein: In step S1, the calcination temperature is 900° C. to 1000° C., and the calcination time is 30 min to 90 min.

4. The method for extracting lithium and beryllium from lepidolite concentrate according to claim 1, wherein The heating rate during calcination in step S1 is 5-10°C / min, and the calcination reaction is naturally cooled to room temperature after completion.

5. The method for extracting lithium and beryllium from lepidolite concentrate according to claim 1, wherein: In the step S2, the calcined clinker is ground to a particle size of 60-80 mesh.

6. The method for extracting lithium and beryllium from lepidolite concentrate according to claim 1, wherein: During the leaching in step S2, the liquid-to-solid ratio is 2:1, and the leaching is carried out at room temperature for 1 hour.

7. The method for extracting lithium and beryllium from lepidolite concentrate according to claim 1, wherein: The neutralizing agent in step S3 is one of potassium carbonate, sodium carbonate and ammonium bicarbonate.

8. The method for extracting lithium and beryllium from lepidolite concentrate according to claim 1, wherein: The leached residue obtained in step S2 is washed with water and then filtered, and the process is repeated twice to obtain lithium residue.

9. The method for extracting lithium and beryllium from lepidolite concentrate according to claim 1, wherein: The neutralized residue obtained in step S3 is washed with water and then filtered, and the process is repeated twice to obtain beryllium-containing waste residue.

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