Method for extracting lithium from lepidolite tailings

Abstract

The invention relates to a method for extracting lithium from lepidolite tailings, which is characterized by comprising the following steps: (1) carrying out magnetic separation on the lepidolite tailings to obtain lepidolite rough concentrate; (2) the lepidolite rough concentrate is subjected to ore grinding and screening desliming; (3) the deslimed minerals are subjected to flotation roughing, and flotation rough concentrate and roughing tailings are obtained; (4) carrying out size mixing on the flotation rough concentrate, and then carrying out ultrasonic dispersion stripping; (5) the flotation rough concentrate subjected to ultrasonic treatment is subjected to flotation concentration, and high-grade lepidolite concentrate and concentrated tailings are obtained after concentration; (6) the roughing tailings are subjected to flotation scavenging, and flotation tailings and scavenged concentrate are obtained; and (7) the selected tailings and the scavenged concentrate are returned to be subjected to flotation rough selection. The method has the advantages that the process energy consumption is low, the extraction efficiency is high, flotation tailing products with the Li2O grade as low as 0.05% can be treated, and the mineral treatment cost is low; the Li2O grade of the obtained lepidolite concentrate can reach 2.0%, and the requirement for lithium salt smelting is met.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, and relates to a granite or pegmatite type lepidolite tailings, specifically a method for extracting lithium from lepidolite tailings. Background Technology

[0002] Lepidolite, a layered silicate mineral containing elements such as lithium, potassium, aluminum, and silicon, often occurs in association with minerals such as quartz and feldspar. In China, the grade of lepidolite ore is generally low, ranging from approximately 0.2% to 0.6%, resulting in high beneficiation costs. With the continuous development of lithium resources, high-quality lithium ore resources are becoming increasingly scarce, forcing the mining and beneficiation of lepidolite to gradually shift towards low-grade, complex, and difficult-to-process ores.

[0003] Currently, the purification of lepidolite minerals in China mainly employs flotation, with lithium mineral recovery rates mostly between 50% and 70%. A large amount of difficult-to-process lithium minerals ends up in tailings, causing serious resource waste. Taking Yichun, Jiangxi Province as an example, its lepidolite reserves account for approximately 40% of the national total. However, the lepidolite in this region suffers from severe weathering and complex mineral occurrence, making beneficiation difficult and resulting in a large accumulation of lepidolite tailings. These tailings have a Li₂O grade between 0.05% and 0.15%. Reprocessing and utilizing this portion of the minerals to improve the overall utilization rate of lepidolite would bring considerable economic and social benefits. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that lepidolite tailings still contain a large amount of lithium in the existing purification process of lepidolite minerals, resulting in resource waste, and to provide a method for extracting lithium from lepidolite tailings.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for extracting lithium from lepidolite tailings, characterized by comprising the following steps: (1) The lepidolite tailings are subjected to medium magnetic separation and strong magnetic separation to obtain lepidolite rough concentrate; wherein the magnetic field strength of the medium magnetic separation is 0.2~0.4T and the magnetic field strength of the strong magnetic separation is 0.8~4.5T; (2) Grind and screen the lepidolite concentrate, control the content of -0.1mm in the grinding product to be greater than 60%, and classify and deslim the grinding product (classify and deslim by hydrocyclone or screening, desliming helps to improve flotation efficiency), with a classification particle size of 0.02mm~0.03mm. (3) The deslimed minerals are subjected to flotation roughing. 50~300g / t of modifier and 200~600g / t of collector are added during roughing to obtain flotation rough concentrate and roughing tailings; (4) Adjust the flotation rough concentrate to a concentration of 40-60%, then place the direct contact ultrasonic transducer in the slurry for ultrasonic dispersion and stripping. The output power of a single ultrasonic transducer should not be less than 0.8kW, and the ultrasonic time should be 1min-10min. (5) The ultrasonically treated flotation rough concentrate (slurry) is subjected to flotation cleaning, wherein 0~100g / t of modifier and 0~100g / t of collector are added during cleaning, and the cleaning is carried out 1~2 times. After cleaning, high-grade lithium mica concentrate and cleaned tailings are obtained. (6) The roughing tailings are subjected to flotation and scavenging. During scavenging, 0~100g / t of modifier and 50~300g / t of collector are added to obtain flotation tailings and scavenging concentrate. (7) Return the selected tailings obtained in step (5) and the scavenged concentrate obtained in step (6) to the flotation roughing process.

[0006] Furthermore, the lepidolite tailings are granite or pegmatite-type lepidolite tailings.

[0007] Furthermore, the equipment used for the intermediate magnetic separation is a permanent magnet or vertical ring magnetic separator, and the equipment used for strong magnetic separation is a periodic high gradient magnetic separator or a superconducting magnetic separator.

[0008] Furthermore, the strong magnetic separation is performed 1 to 2 times.

[0009] Furthermore, the modifier is one or two of water glass (Na2SiO3), sodium carbonate (Na2CO3), or sodium metaphosphate.

[0010] Furthermore, the collector is a combination of a sulfonate anionic collector and an amine cationic collector.

[0011] Furthermore, the mass ratio of the sulfonate anionic collector to the amine cationic collector is 1:1 to 5:1.

[0012] Furthermore, the sulfonate anionic collector is any one of sodium dodecyl sulfonate, sodium hexadecyl sulfonate, sodium dodecylbenzene sulfonate, and sodium petroleum sulfonate, and the amine cationic collector is any one of dodecylamine, octadecylamine, and cocoylamine.

[0013] Furthermore, the flotation roughing process consists of two stages.

[0014] Granite or pegmatite-type lepidolite contains a large amount of feldspar and quartz minerals. This invention utilizes the fact that feldspar and quartz are non-magnetic, while lepidolite minerals often have weak magnetism. Magnetic separation can initially enrich lepidolite, producing tailings with a yield of over 90%. The magnetically separated rough concentrate with a yield of less than 10% is then fed into subsequent flotation, significantly improving the processing efficiency of lithium-containing minerals. In the magnetically separated rough concentrate, lepidolite generally has mineral intergrowth or impurity covering. Ultrasonic treatment has a strong effect on separating impurities between mica layers and particles on the mica surface, which can peel off new mica mineral surfaces, reduce the interference of impurities on flotation reagents, improve the selectivity of mica minerals in flotation, reduce the gangue mineral content in the concentrate, and improve the grade of lepidolite concentrate.

[0015] The beneficial effects of this invention are as follows: (1) The lithium extraction process described in this invention has low energy consumption, high extraction efficiency, and can process flotation tailings products with Li2O grade as low as 0.05%, resulting in low mineral processing costs. (2) The present invention reuses solid waste resources and obtains lithium mica concentrate with a Li2O grade of up to 2.0%, which meets the requirements of lithium salt smelting. Attached Figure Description

[0016] Figure 1 This is a simplified process flow diagram of lithium extraction from lepidolite tailings as described in Example 1; Figure 2 This is a simplified process flow diagram of lithium extraction from lepidolite tailings as described in Example 2; Figure 3 A simplified process flow diagram for lithium extraction from lepidolite tailings, as described in the comparative embodiment. Detailed Implementation

[0017] The following is combined Figure 1 The present invention will be further described in detail below: A method for extracting lithium from lepidolite tailings, the specific implementation steps of which are as follows: Example 1

[0018] (1) The pegmatite-type lepidolite tailings (the main minerals are albite, quartz and potassium feldspar, with 62% of the product having a particle size of 0.1~0.3mm and 100% having a particle size of -0.4mm, and the specific composition of the tailings is shown in Table 1 below) were subjected to medium magnetic separation. The magnetic separation equipment was a vertical ring magnetic separator with a magnetic field strength of 0.3T. The products were medium magnetic concentrate I and strong magnetic tailings. The medium magnetic concentrate I was processed by a periodic high gradient magnetic separator with a magnetic field strength of 1.3T. The products were low iron minerals and weakly magnetic lepidolite-bearing minerals. (2) Weakly magnetic lithium-bearing mica minerals were ground with steel balls at a ratio of steel balls to minerals of 10:1 for 3 minutes. After grinding, the content of -0.1mm was 61.21%. The minerals were sieved with a 0.030mm sieve to obtain +0.030mm minerals and -0.030mm fine mud. (3) The +0.030mm mineral is subjected to two-stage flotation roughing. 100g / t modifier (Na2CO3) and 400g / t collector (cocoalumina and sodium dodecyl sulfonate are prepared in a mass ratio of 1:1) are added to roughing 1 to obtain roughing 1 concentrate and roughing 1 tailings. Roughing 2 is then carried out on the roughing 1 tailings. 30g / t modifier (Na2CO3) and 250g / t collector (cocoalumina and sodium dodecyl sulfonate are prepared in a mass ratio of 1:1) are added to roughing 2 to obtain roughing 2 concentrate and roughing 2 tailings. (4) After merging the concentrate from rougher 1 and rougher 2, adjust the slurry concentration to 50%, then place the direct contact ultrasonic transducer in the slurry for ultrasonic dispersion and stripping. The single ultrasonic output power is 1.0kW and the ultrasonic time is 5min. (5) The ultrasonically treated rough concentrate (slurry) is subjected to flotation and cleaning, with 20 g / t modifier (Na2CO3) and 30 g / t modifier ((NaPO3)6) added. After cleaning, high-grade lithium mica concentrate and cleaned tailings are obtained. (6) The tailings from roughing stage 2 are subjected to flotation and scavenging, and 20 g / t modifier (Na2CO3) and 100 g / t collector (cocoalumina and sodium dodecyl sulfonate are prepared in a mass ratio of 1:1) are added to obtain flotation tailings and scavenging concentrate. (7) Return the fine tailings obtained in step (5) and the scavenged concentrate obtained in step (6) to roughing 2.

[0019] In this embodiment, the lithium mica concentrate yield is 1.76%, the Li2O grade is 2.54%, and the recovery rate is 47.85%. The lithium concentrate is used for the smelting of lithium salt products. Magnetic separation yields low-iron minerals with a yield of 85.25%, a Li2O grade of 0.036%, a Fe2O3 content of 0.0036%, a K2O content of 2.56%, and a Na2O content of 4.92%. The low-iron minerals can be appropriately added as raw materials for float glass or high-whiteness ceramics.

[0020]

[0021] Example 2 (1) Granite-type lepidolite tailings (main minerals are potassium feldspar, sodium feldspar, and quartz, with a small amount of altered kaolinite and sericite; the product particle size is 0.1~0.3mm accounting for 73%, and -0.4mm accounting for 100%; the specific composition of the tailings is shown in Table 2 below) are subjected to medium magnetic separation. The magnetic separation equipment is a vertical ring magnetic separator with a magnetic field strength of 0.3T. The products are medium magnetic concentrate I and strong magnetic tailings. The medium magnetic concentrate I is processed by a periodic high gradient magnetic separator with a magnetic field strength of 1.3T. The products are low iron minerals and weakly magnetic lepidolite-bearing minerals. (2) Weakly magnetic lithium-bearing mica minerals were ground with steel balls at a ratio of steel balls to minerals of 10:1 and a grinding time of 2.5 min. The content of -0.1 mm after grinding was 75.42%. The minerals were sieved with a 0.025 mm sieve to obtain +0.025 mm minerals and -0.025 mm fine mud. (3) The +0.025mm mineral is subjected to a first-stage flotation roughing process. 120g / t modifier (Na2CO3) and 350g / t collector (cocoalumina and sodium dodecyl sulfonate are prepared in a mass ratio of 1:1) are added to roughing process 1 to obtain roughing process 1 concentrate and roughing process 1 tailings. (4) Adjust the slurry concentration of the roughing concentrate to 50%, and then place the direct contact ultrasonic transducer in the slurry for ultrasonic dispersion and stripping. The single ultrasonic output power is 1.0kW and the ultrasonic time is 3min. (5) The ultrasonically treated rough concentrate (slurry) is subjected to flotation and cleaning, with 20 g / t modifier (Na2CO3) and 30 g / t modifier ((NaPO3)6) added. After cleaning, high-grade lithium mica concentrate and cleaned tailings are obtained. (6) The tailings from roughing stage 1 are subjected to flotation and scavenging, and 40 g / t modifier (Na2CO3) and 100 g / t collector (cocoalumina and sodium dodecyl sulfonate are prepared in a mass ratio of 1:1) are added to obtain flotation tailings and scavenging concentrate. (7) Return the fine tailings obtained in step (5) and the scavenged concentrate obtained in step (6) to roughing 1.

[0022] In this embodiment, the yield of lepidolite flotation concentrate is 1.15%, the Li2O grade is 2.17%, the recovery rate is 42.57%, and the yield of low-iron minerals obtained by magnetic separation is 84.67%, the Li2O grade is 0.028%, the Fe2O3 content is 0.0064%, the K2O content is 4.22%, and the Na2O content is 3.16%. The low-iron minerals can be appropriately added as raw materials for float glass.

[0023] Comparative Examples

[0024] (1) Granite-type lepidolite tailings (the main minerals are potassium feldspar, sodium feldspar, and quartz, with a small amount of altered kaolinite and sericite; the product particle size is 0.1~0.3mm, accounting for 73%, and -0.4mm particle size accounting for 100%; the specific composition of the tailings is shown in Table 2) were ground with steel balls at a ratio of steel balls to minerals of 10:1 and a grinding time of 2.5 min. After grinding, the content of -0.1mm was 73.28%. The tailings were screened with a 0.025mm sieve to obtain +0.025mm minerals and -0.025mm fine mud. (2) The +0.025mm mineral is subjected to a first-stage flotation roughing process. 60g / t of modifier (Na2CO3) and 300g / t of collector (cocoalumina and sodium dodecyl sulfonate are prepared in a mass ratio of 1:1) are added to roughing process 1 to obtain roughing process 1 concentrate and roughing process 1 tailings. (3) The rougher concentrate 1 is subjected to two-stage flotation cleaning. 20g / t of modifier (Na2CO3) and 30g / t of modifier ((NaPO3)6) are added to cleaning 1, and 10g / t of modifier (Na2CO3) and 10g / t of modifier ((NaPO3)6) are added to cleaning 2. The tailings of cleaning 2 are returned to cleaning 1. After cleaning, high-grade lithium mica concentrate and tailings of cleaning 1 are obtained. (4) The tailings from roughing stage 1 are subjected to flotation and scavenging, and 20 g / t modifier (Na2CO3) and 100 g / t collector (cocoalumina and sodium dodecyl sulfonate are prepared in a mass ratio of 1:1) are added to obtain flotation tailings and scavenging concentrate. (5) Return the tailings obtained in step (3) and the scavenging concentrate obtained in step (4) to roughing process 1.

[0025] In this embodiment, the yield of lepidolite flotation concentrate is 1.35%, the Li₂O grade is 1.86%, the recovery rate is 42.78%, the flotation tailings yield is 94.48%, the Li₂O grade is 0.032%, the Fe₂O₃ content is 0.12%, the K₂O content is 4.15%, and the Na₂O content is 3.80%. In this embodiment, the lepidolite concentrate grade is relatively low, the flotation throughput is large, the reagent cost is high, and the economic benefits are poor.

Claims

1. A method for extracting lithium from lepidolite tailings, characterized in that... Includes the following steps: (1) The lepidolite tailings are subjected to medium magnetic separation and strong magnetic separation to obtain lepidolite rough concentrate; wherein the magnetic field strength of the medium magnetic separation is 0.2~0.4T and the magnetic field strength of the strong magnetic separation is 0.8~4.5T; (2) Grind and screen the lithium mica rough concentrate, control the content of -0.1mm in the grinding product to be greater than 60%, and classify and deslim the grinding product with a particle size of 0.02mm~0.03mm. (3) The deslimed minerals are subjected to flotation roughing. 50~300g / t of modifier and 200~600g / t of collector are added during roughing to obtain flotation rough concentrate and roughing tailings; (4) Adjust the flotation rough concentrate to a concentration of 40-60%, then place the direct contact ultrasonic transducer in the slurry for ultrasonic dispersion and stripping. The output power of a single ultrasonic transducer should not be less than 0.8kW, and the ultrasonic time should be 1min-10min. (5) The ultrasonically treated flotation rough concentrate is subjected to flotation cleaning, wherein 0~100g / t of modifier and 0~100g / t of collector are added during cleaning, and the cleaning is carried out 1~2 times. After cleaning, high-grade lithium mica concentrate and cleaned tailings are obtained. (6) The roughing tailings are subjected to flotation and scavenging. During scavenging, 0~100g / t of modifier and 50~300g / t of collector are added to obtain flotation tailings and scavenging concentrate. (7) Return the selected tailings obtained in step (5) and the scavenged concentrate obtained in step (6) to the flotation roughing process.

2. The method for extracting lithium from lepidolite tailings according to claim 1, characterized in that: The lepidolite tailings are granite or pegmatite-type lepidolite tailings.

3. The method for extracting lithium from lepidolite tailings according to claim 1, characterized in that: The equipment used for medium magnetic separation is a permanent magnet or vertical ring magnetic separator, and the equipment used for strong magnetic separation is a periodic high gradient magnetic separator or a superconducting magnetic separator.

4. The method for extracting lithium from lepidolite tailings according to claim 1, characterized in that: The strong magnetic separation is performed 1 to 2 times.

5. The method for extracting lithium from lepidolite tailings according to claim 1, characterized in that: The modifier is one or two of water glass, sodium carbonate, or sodium metaphosphate.

6. The method for extracting lithium from lepidolite tailings according to claim 1, characterized in that: The collector is a combination of sulfonate anionic collectors and amine cationic collectors.

7. The method for extracting lithium from lepidolite tailings according to claim 6, characterized in that: The mass ratio of the sulfonate anionic collector to the amine cationic collector is 1:1 to 5:

1.

8. A method for extracting lithium from lepidolite tailings according to claim 6 or 7, characterized in that: The sulfonate anionic collector is any one of sodium dodecyl sulfonate, sodium hexadecyl sulfonate, sodium dodecylbenzene sulfonate, and sodium petroleum sulfonate, and the amine cationic collector is any one of dodecylamine, octadecylamine, and cocoylamine.

9. A method for extracting lithium from lepidolite tailings according to any one of claims 1-7, characterized in that: The flotation roughing process consists of two stages.

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