Method for selectively extracting rubidium from lithium ore tailings by short process

Abstract

The application discloses a method for selectively extracting rubidium from lithium mine tailings in a short process, and relates to the field of comprehensive utilization of mineral waste. The method comprises the following steps: grinding lithium mine tailings into powder; adding an additive to the lithium mine tailings powder and fully stirring and mixing; roasting the mixture to obtain calcined clinker; directly water-immersing the calcined clinker; obtaining a rubidium enrichment liquid and leaching residue from the leaching liquid through solid-liquid separation; mixing the rubidium extraction composite material with the rubidium enrichment liquid to realize selective adsorption of rubidium; and recycling the composite material. The application realizes efficient and selective recovery of rubidium in lithium mine tailings, not only shortens the water immersion time, reduces the water immersion temperature and the rubidium extraction roasting reaction temperature, but also significantly improves the separation efficiency of impurities in the lithium mine tailings and the selective recovery efficiency of the rubidium element, thereby realizing efficient and selective recovery of rubidium in the lithium mine tailings.

Description

Technical Field

[0001] This invention relates to the field of comprehensive utilization of mineral waste, specifically a method for selectively extracting rubidium from lithium tailings using a short process. Background Technology

[0002] Lithium extraction processes from lepidolite generally include acid methods, alkali methods, salt methods, and pressure cooking methods. During the production of these lithium salts, a large amount of lithium ore tailings is generated as industrial waste. It is estimated that 1 ton of lithium carbonate yields 8 to 10 tons of lithium ore tailings.

[0003] Research on the comprehensive utilization of lithium mine tailings mainly focuses on their direct application in building materials such as concrete, cement mortar, and cement, as well as the preparation of ceramics, building ceramsite, and molecular sieves. The technology is relatively outdated, costing approximately 200 yuan to process one ton of lithium mine tailings, which is quite high and makes it difficult to achieve effective reprocessing of lithium mine tailings in actual factory production. However, in addition to extracting the valuable metal lithium, lithium ore can also extract the high-value metal rubidium, thus realizing the resource utilization of solid waste.

[0004] Rubidium is a soft, reactive, and rare metal with unique optoelectronic properties. It is also one of the most valuable rare alkali metals, widely used in traditional fields such as atomic clocks, photovoltaic cells, specialty glasses, biochemistry, and medicine. In particular, with the rapid development of rubidium in emerging applications such as magnetohydrodynamic power generation, thermionic power generation, and ion propulsion engines, the demand for rubidium has been increasing significantly year by year.

[0005] Previous methods for extracting rubidium from lepidolite typically involve the following steps: crushing the raw ore, adding additives to the crushed ore and roasting it at high temperature, then directly leaching the roasted product in water at a certain rotation speed, thoroughly washing the leached ore and liquid with deionized water to achieve solid-liquid separation, and finally extracting rubidium as rubidium salt from the washing solution. However, each step is carried out in a strong chemical environment, resulting in high energy consumption. Furthermore, the washing solution contains a large number of other metallic impurities besides rubidium, making it difficult to achieve targeted extraction and utilization of rubidium resources. For example, the method provided in CN114107674A requires microwave heating to 1000–1600°C for roasting, while the method in CN115725856A uses ion exchange to extract rubidium, which, although not requiring high-temperature roasting, still requires a leaching time of 24 hours. Although the CN113337734A method can extract rubidium at a lower temperature, other metal elements are still mixed in the rubidium enrichment solution, and effective separation cannot be achieved. Summary of the Invention

[0006] To address the shortcomings of existing rubidium extraction methods, such as requiring reactions in a strong chemical environment, high energy consumption, and numerous impurities, this invention provides a short-process selective rubidium extraction method from lithium mine tailings. This method uses a mixture of calcium chloride and oxalic acid as additives, releasing metal elements from the tailings through a combination of chlorination roasting and leaching. Combined with a self-made rubidium extraction composite material, this method selectively extracts rubidium from the rubidium enrichment solution, separating other impurity elements and improving the purity of rubidium-containing substances. This provides a new approach for the targeted recovery and utilization of rubidium resources in lithium mine tailings.

[0007] The present invention adopts the following technical solution:

[0008] A method for selectively extracting rubidium from lithium mine tailings using a short process includes the following steps:

[0009] S1. Grind the lithium tailings to obtain lithium tailings powder;

[0010] S2. The lithium tailings powder obtained in step S1 is thoroughly mixed with the composite additive to obtain raw material. The composite additive is a mixture of calcium chloride and oxalic acid.

[0011] S3. Roast the raw materials obtained in step S2 to obtain roasted material;

[0012] S4. After cooling the roasted slag obtained in step S3 to room temperature, water leaching is performed. The leachate is separated into rubidium-enriched solution (leachate) and leachate residue through solid-liquid separation.

[0013] S5. Select the rubidium extraction composite material and mix it with the rubidium enrichment solution obtained in step S4 to obtain a mixture. The rubidium extraction composite material is a metal-organic framework (MOF) material.

[0014] S6. The mixture obtained in S5 is subjected to solid-liquid separation to obtain rubidium-enriched material; the rubidium-enriched material is placed in KCl solution and heated for desorption treatment. After solid-liquid separation, rubidium-enriched pure solution and regenerated rubidium-extracted composite material are obtained.

[0015] Furthermore, in step S1, the proportion of lithium tailings powder with a particle size of 0 to 100 μm exceeds 98%, and more preferably, the proportion of powder with a particle size of 0 to 75 μm exceeds 90%.

[0016] Furthermore, in step S2, the mass ratio of calcium chloride to oxalic acid is 0.3-0.6:0.5, preferably 0.4-0.5:0.5.

[0017] Furthermore, in step S3, the calcination temperature is 600–900℃, and the calcination time is 0.5–3h.

[0018] Furthermore, in step S4, the water immersion temperature is 25–90°C, and the time is 2–120 min.

[0019] Furthermore, in step S4, the calcining material is in powder form and does not require further grinding. The mass ratio of the calcining material to water is 1:2 to 10.

[0020] Furthermore, in step S5, the stirring speed is 100–950 r / min, the mixing temperature is 20–80℃, and the mixing time is 2 min–2 h.

[0021] Further, in step S5, metal-organic framework materials (MOFs) are prepared using conventional methods of the prior art, with the selection of at least one of potassium ferrocyanide trihydrate, cobalt nitrate hexahydrate, p-phenylcarboxylic acid, DMF, acetic acid, and zirconium oxychloride octahydrate as raw materials as needed.

[0022] Furthermore, in step S5, the mass ratio of the rubidium-containing composite material to the rubidium enrichment solution is 0.8 to 1.2:1, preferably 0.9 to 1.1:1.

[0023] Furthermore, in step S6, the concentration of the KCl solution is 0.5–2 mol / L, and the desorption temperature is 40–70 °C, preferably 50–60 °C.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention enables the rapid release of rubidium at relatively low temperatures and allows for the selective extraction of rubidium from rubidium-enriched solutions using composite materials, further enhancing the targeted and selective resource utilization of rubidium. Furthermore, by precisely controlling particle size distribution, additive ratios, calcination conditions, leaching parameters, stirring speed and temperature, and desorption conditions, this invention optimizes the rubidium extraction process, thereby improving extraction efficiency and selectivity. This method not only reduces energy consumption and environmental pollution but also lowers rubidium extraction costs, improving economic benefits. By using MOF materials, this invention also achieves highly efficient adsorption and desorption of rubidium, further enhancing the controllability and flexibility of the extraction process. In addition, the method of this invention has advantages such as simple operation, low equipment requirements, and ease of industrial scale-up, showing promising prospects for industrial applications. Attached Figure Description

[0026] Figure 1 This is a flowchart of the process flow of the present invention.

[0027] Figure 2 These are SEM and EDS images of the original lithium ore tailings and roasted samples from Example 2 of the present invention, where (a) is the original lithium ore tailings, (b) is the roasted sample, and (c) is the leaching residue. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this does not limit the scope of protection of the present invention.

[0029] In the following examples, unless otherwise specified, the raw materials and instruments used are commercially available, the equipment used is conventional equipment, and the data obtained are the average values ​​of more than three repeated experiments.

[0030] The preparation methods for the four rubidium-containing composite materials are as follows:

[0031] (1) KCoFC@UIO-66: Prepared from potassium ferrocyanide trihydrate, cobalt nitrate hexahydrate, p-phenylcarboxylic acid, DMF, acetic acid, and zirconium oxychloride octahydrate. Specifically, 10 mL of 0.5 mol / L potassium ferrocyanide trihydrate was added to 24 mL of 0.3 mol / L cobalt nitrate hexahydrate and stirred for 1 h at room temperature. The mixture was washed with deionized water and centrifuged three times to remove excess cobalt nitrate. The product after centrifugation was dried at 115 °C for 24 h. The dried particles were then ground and passed through a 100-mesh sieve to obtain potassium cobalt hexacyanate ferrate. 15 mol of p-phenylcarboxylic acid was added to a beaker containing a mixture of 120 mol of potassium cobalt hexacyanoferrate, 30 mL of N,N'-dimethylformamide (DMF), and 18 mL of acetic acid. The mixture was stirred thoroughly at room temperature for 30 min. Then, 5 mol of chromium oxychloride octahydrate was added to the beaker, and the mixture was stirred for 2 h. The mixture was then placed in a 100 mL autoclave and heated at 150 °C for 24 h. The mixture was then transferred to 50 mL centrifuge tubes and centrifuged at 8000 rpm for 10 min. The mixture was washed three times each with anhydrous ethanol and DMF to remove excess ions, ensuring the surface of the material was free of impurity ions. The bottom dark green solid phase was separated to obtain the final product, which was then vacuum dried at 65 °C for 8 h until the quality stabilized, yielding the final metal-organic framework material KCoFC@UIO-66.

[0032] (2) Potassium cobalt hexacyanoferrate (KCoFC): Prepared using potassium ferrocyanide trihydrate and cobalt nitrate hexahydrate as raw materials. Specifically, 10 mL of 0.5 mol / L potassium ferrocyanide trihydrate was added to 24 mL of 0.3 mol / L cobalt nitrate hexahydrate and stirred for 1 h at room temperature. The mixture was then washed with deionized water and centrifuged three times to remove excess cobalt nitrate. The centrifuged product was dried at 115 °C for 24 h. The dried particles were then ground and passed through a 100-mesh sieve to obtain potassium cobalt hexacyanoferrate (KCoFC).

[0033] (3) UIO-66 material: It was prepared using terephthalic acid, DMF, acetic acid, and zirconium oxychloride octahydrate as raw materials. Specifically, 0.5000 g of zirconium oxychloride octahydrate was added to 15 mL of DMF and sonicated for 15 min. Then, 0.2575 g of terephthalic acid and 9.3 mL of acetic acid were added and sonicated for 30 min. The mixture was then placed in a 100 mL high-pressure reactor and heated at 150 °C for 24 h. The mixture was then placed in a 50 mL centrifuge tube and centrifuged at 8000 rpm for 10 min. After centrifugation, the mixture was washed three times each with anhydrous ethanol and DMF to remove excess ions and ensure that there were no impurity ions on the surface of the material. Finally, the material was vacuum dried at 65 °C for 24 h until the quality stabilized to obtain UIO-66 material.

[0034] (4) Ammonium phosphotungstenate-sodium alginate material: Prepared using calcium chloride, sodium alginate, and ammonium phosphotungstenate as raw materials. Specifically, a 0.5 mol / L calcium chloride solution and a 1.5% sodium alginate sol were first prepared. According to the material ratio m(NaALG):m(AWP) = 1:2, ammonium phosphotungstenate was gradually added to the sodium alginate sol to ensure thorough mixing. The mixed sol was then drawn up using a medical syringe and slowly added dropwise to the previously prepared 0.5 mol / L calcium chloride solution. After the addition was complete, the mixture was allowed to stand at room temperature for 24 hours. After sedimentation, the composite adsorbent was separated by vacuum filtration and washed repeatedly with deionized water to ensure the removal of residual calcium chloride on the surface. After filtration, the mixture was placed in an electric heating drying oven preheated to 105°C and dried to constant weight. The ammonium phosphotungstenate-sodium alginate material was finally obtained.

[0035] Example 1

[0036] A method for selective rubidium extraction from lithium tailings using a short process, the process flow is as follows: Figure 1 As shown, it includes the following steps:

[0037] S1. Take 10g of lithium ore tailings, dry and crush it to obtain lithium ore tailings powder with a particle size range of 0-100μm and more than 98% content. The main chemical components (mass percentage) of the lithium ore tailings used in this embodiment are shown in Table 1.

[0038] Table 1. Main chemical components of lithium tailings

[0039] oxides <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[K2O]]> CaO <![CDATA[Fe2O3]]> MgO <![CDATA[Na2O]]> <![CDATA[Rb2O]]> other Percentage / % 62.7 20.7 5.06 4.25 3.61 1.59 1.26 0.227 0.603

[0040] S2. Take 5g of calcium chloride, 3g of oxalic acid and 10g of raw lithium tailings sample, mix them thoroughly and evenly to prepare a mixed sample.

[0041] S3. Heat the above mixed sample to 700°C and calcine for 2 hours to obtain the calcined material.

[0042] S4. The calcined material is in powder form and does not require further grinding. It is directly leached. Water leaching is carried out at a leaching temperature of 25°C and a leaching time of 30 minutes. The liquid-solid mass ratio of water to calcined material is 4:1. The leachate is treated by solid-liquid separation to obtain rubidium-enriched solution and leaching residue.

[0043] S5. The prepared rubidium-enriched composite material KCoFC@UIO-66 and the rubidium enrichment solution were mixed at a mass ratio of 1:1 at 25°C and a stirring speed of 250 r / min for 2 hours to form a mixture.

[0044] S6. Perform solid-liquid separation on the mixture to separate the rubidium-enriched material.

[0045] S7. Place the rubidium-enriched material in a 1 mol / L KCl solution and heat it to 50°C for desorption treatment for 30 min. Obtain the rubidium-enriched pure solution and the regenerated rubidium-extracted composite material through solid-liquid separation.

[0046] Experimental results show that, under the above conditions, after all the lithium tailings were leached, the concentration of rubidium in the rubidium enrichment solution reached 142.91 mg / L, and the extraction rate of rubidium reached 89.94%.

[0047] The concentration of rubidium ions and the content of major interfering metal elements in the rubidium enrichment solution were accurately measured using atomic absorption spectrophotometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). The process parameters and leaching rates of the raw materials are shown in Table 2, and the basic data of the leachate are shown in Table 3.

[0048] Examples 2 to 22 demonstrate short-process, short-time selective rubidium extraction methods from lithium tailings with different process parameters. The difference from Example 1 lies in the altered process parameters of the original lithium tailings chlorination roasting process; the remaining steps are identical to Example 1 and will not be repeated here. The selective adsorption of the composite material will be discussed in detail in Examples 23 to 26.

[0049] The parameters corresponding to Examples 1 to 22 and the leaching rates obtained by testing and calculation are shown in Table 2.

[0050] Table 2. Process parameters and leaching rates for Examples 1-22

[0051]

[0052] As shown in Table 2, during the chlorination roasting extraction of rubidium, the roasting time and temperature, leaching time, leaching temperature, and solid-liquid ratio, among other process parameters, all significantly affect the rubidium leaching rate. This invention, through precise control and optimization of these process parameters, enables efficient rubidium extraction at lower temperatures within a shorter time, achieving a maximum leaching rate of 91.80%. This effectively overcomes the technical shortcomings of traditional leaching methods, such as long leaching time, high energy consumption, and low leaching rate.

[0053] Examples 23 to 26 further provide a short-process, short-time selective rubidium extraction method from lithium tailings using different adsorbents. Compared to Example 1, these examples employ four different adsorbents for selective rubidium adsorption in the leachate treatment after chlorination roasting of the original lithium tailings. The remaining steps are the same as in Example 1 and will not be repeated here. Table 3 shows the adsorbents and the remaining amounts of different metals in the leachate for each example. Furthermore, the regeneration experimental results of the KCoFC@UIO-66 adsorbent material in Example 1 are recorded in detail in Table 4.

[0054] Table 3. Data on leachate under optimal conditions and data after adsorption of different materials.

[0055] Example Rb / ppm Na / ppm Mg / ppb Ca / ppm K / ppm Zn / ppb Original leachate 142.91 175.8 228.7 540.5 903.9 530.7 23 KCoFC@UIO-66 1.012 172.3 223.4 540.3 960.1 528.3 24 KCoFC 98.71 138.9 219.9 515.8 934.9 469.1 25 UIO-66 130.836 78.19 212.6 539.8 909.8 317.8 26 Ammonium phosphotungstate-sodium alginate 127.899 73.47 224.6 538.3 911.8 335.3

[0056] Table 4 shows the regeneration status of the KCoFC@UIO-66 adsorbent material.

[0057] Rb / ppm Rb adsorption capacity (mg / g) Repeat 1 1.012 141.898 Repeat 2 2.197 140.713 Repeat 3 5.693 137.217 Repeat 4 8.1622 134.747 Repeat 5 16.909 126.001

[0058] As shown in Tables 3 and 4, the composite adsorbent material prepared in this invention exhibits a significant selective adsorption capacity for rubidium in the leachate. After five adsorption-desorption cycles, the selective adsorption capacity of the composite material for rubidium remains at 88.8% of the initial adsorption capacity, demonstrating its ability to rapidly, efficiently, and selectively adsorb rubidium from the leachate. The method of this invention avoids the problems of long processing time, complex operation, and low regeneration efficiency commonly found in traditional rubidium adsorption technologies.

[0059] In summary, the short-process selective rubidium extraction method from lithium tailings provided by this invention employs an integrated process of chlorination roasting, short-time low-temperature water leaching, and selective rubidium adsorption using composite materials. First, the ground lithium tailings are uniformly mixed with calcium chloride and oxalic acid to prepare a roasting material. This material is then roasted at a predetermined temperature and maintained at that temperature. After the reaction, it is naturally cooled to room temperature, directly yielding the leaching material. Next, the leaching material is mixed with water in a predetermined ratio and leached with stirring at a set temperature. The leaching is then filtered to obtain a rubidium-rich solution (leaching liquid) and leaching residue. Finally, at room temperature, a composite adsorption material is added to the rubidium-rich solution in a fixed ratio to achieve selective adsorption of rubidium. Through this process, this invention can efficiently extract rubidium from lithium tailings. The entire process is simple to operate, has low energy consumption, short time, high leaching rate, and good selectivity, effectively overcoming the technical difficulties of traditional rubidium adsorption technologies, such as long processing time, complex operation, and low regeneration efficiency. It has significant practical application value.

Claims

1. A method for selectively extracting rubidium from lithium ore tailings using a short-process method, characterized in that, Includes the following steps: S1. Grind the lithium tailings to obtain lithium tailings powder; S2. The lithium tailings powder obtained in step S1 is thoroughly mixed with the composite additive to obtain raw material. The composite additive is a mixture of calcium chloride and oxalic acid. S3. Roast the raw materials obtained in step S2 to obtain roasted material; S4. After cooling the calcined material obtained in step S3 to room temperature, it is subjected to water leaching. The leachate is separated into rubidium-enriched solution and leaching residue through solid-liquid separation. S5. Select the rubidium extraction composite material and mix it with the rubidium enrichment solution obtained in step S4 to obtain a mixture. The rubidium extraction composite material is KCoFC@UIO-66, KCoFC, UIO-66 or ammonium phosphotungstate-sodium alginate. S6. The mixture obtained in S5 is subjected to solid-liquid separation to obtain rubidium-enriched material; the rubidium-enriched material is placed in KCl solution and heated for desorption treatment. After solid-liquid separation, rubidium-enriched pure solution and regenerated rubidium-extracted composite material are obtained.

2. The method for selectively extracting rubidium from lithium tailings using a short-process method according to claim 1, characterized in that, In step S1, the lithium tailings powder has a particle size of 0~100 μm and the proportion of powder exceeds 98%.

3. The method for selectively extracting rubidium from lithium tailings using a short-process method according to claim 1, characterized in that, In step S2, the mass ratio of calcium chloride to oxalic acid is 0.3~0.6:0.

5.

4. The method for selectively extracting rubidium from lithium tailings using a short-process method according to claim 1, characterized in that, In step S3, the calcination temperature is 600~900℃ and the calcination time is 0.5~3 h.

5. The method for selectively extracting rubidium from lithium tailings using a short-process method according to claim 1, characterized in that, In step S4, the water immersion temperature is 25~90℃ and the time is 2~120 min.

6. The method for selectively extracting rubidium from lithium tailings using a short-process method according to claim 1, characterized in that, In step S4, the calcining material is in powder form and does not require further grinding. The mass ratio of the calcining material to water is 1:2~10.

7. The method for selectively extracting rubidium from lithium tailings using a short-process method according to claim 1, characterized in that, In step S5, The stirring speed is 100~950 r / min, the mixing temperature is 20~80℃, and the mixing time is 2min~2h.

8. The method for selectively extracting rubidium from lithium tailings using a short-process method according to claim 1, characterized in that, In step S5, the mass ratio of the rubidium composite material to the rubidium enrichment solution is 0.8~1.2:

1.

9. The method for selectively extracting rubidium from lithium tailings using a short-process method according to claim 1, characterized in that, In step S6, the concentration of the KCl solution is 0.5~2 mol / L, and the desorption temperature is 40~70℃.

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