Lithium adsorbent, preparation method and application thereof, and buried lithium adsorption system

Abstract

The invention belongs to the technical field of lithium smelting, and particularly relates to a lithium adsorbent, a preparation method and application thereof and a buried lithium adsorption system. The preparation method of the lithium adsorbent comprises the steps that spodumene smelting slag and fluoride salt are mixed and roasted, and roasted slag is obtained; mixing the roasting slag with an acid solution, performing acid activation, and performing solid-liquid separation to obtain acid activated slag; and mixing the acid activation slag and alkali liquor for hydrothermal reaction, and washing and drying the obtained precipitate to obtain the lithium adsorbent. The lithium adsorbent is prepared by taking the spodumene smelting slag as the raw material, so that the cost is low; according to the preparation method, fluoride salt mineralization strengthening, acid activation and alkali reconstruction directional modification are sequentially carried out, and the prepared lithium adsorbent is high in adsorption capacity and good in cycling stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium smelting, and particularly relates to a lithium adsorbent, a preparation method and application thereof, and a buried lithium adsorption system. BACKGROUND

[0002] Lithium, as a strategic resource indispensable to modern industry, plays a key role in the fields of new energy vehicles, aerospace, and nuclear industry. With the acceleration of global energy structure transformation, the development and utilization of lithium resources have become the focus of the scientific and industrial communities. Currently, industrial lithium resources mainly come from two major types: pegmatite type lithium ore (spodumene or lepidolite) and salt lake brine. Among them, spodumene has a significant development advantage due to its high lithium grade (Li2O 5~6%), while lepidolite (Li2O 1.5~3%) has poor economic efficiency due to its low grade and high processing cost; although salt lake brine has abundant reserves, its complex chemical composition greatly increases the extraction difficulty.

[0003] In industrial production, spodumene is mainly used to extract lithium by sulfuric acid method: first, α-spodumene is transformed into β-spodumene by calcination at a high temperature of 1000~1200℃, then mixed with sulfuric acid and calcined at a temperature of 250~300℃, and through the replacement reaction of H + -Li + sulfate generates soluble lithium sulfate, and finally, lithium carbonate products are obtained through processes such as water immersion, impurity removal, evaporation concentration, and lithium precipitation. In the process of producing lithium carbonate from spodumene by sulfuric acid method, lithium spodumene smelting slag is produced, and its main component is HAlSi2O6. Currently, such slag is usually stored as solid waste in a tailings pond, not only causing waste of residual lithium resources (lithium mass content in tailings 0.2~0.5%, Li + concentration in tail liquid 0.1~0.5 g / L), but also occupying a large amount of land resources and accompanying potential environmental risks.

[0004] The current industrial application of lithium adsorbent mainly includes three categories: aluminum, manganese, and titanium. The preparation cost of these adsorbents is generally high, and it is difficult to adapt to the special environment of spodumene smelting tailings pond with high salt and multiple impurities, and there are obvious defects: the lithium adsorption capacity of aluminum adsorbent (such as Al2O3) is low (2~7mg / g), and the lithium concentration in the desorption liquid is only about 0.6g / L; manganese and titanium adsorbents face the problems of high dissolution rate (>5%), strong acid regeneration, and poor cycle stability. Therefore, it is urgent to develop a lithium adsorbent with low cost, high adsorption capacity, and good cycle stability. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a lithium adsorbent, a preparation method and application thereof, and a buried lithium adsorption system. The lithium adsorbent preparation method provided by the present application has low cost, and the lithium adsorbent prepared has high adsorption capacity and good cycle stability.

[0006] The application provides a preparation method of a lithium adsorbent, comprising the following steps: roasting the lithium spodumene smelting slag and a fluorinated salt to obtain roasted slag; mixing the roasted slag and acid liquid to perform acid activation, and performing solid-liquid separation to obtain acid-activated slag; mixing the acid-activated slag and alkali liquid to perform hydrothermal reaction, washing and drying the obtained precipitate to obtain the lithium adsorbent.

[0007] Preferably, the fluorinated salt comprises one or more of sodium fluoride, calcium fluoride and potassium fluoride, and the mass of the fluorinated salt is 0.1-2% of the mass of the lithium spodumene smelting slag.

[0008] Preferably, the roasting temperature is 500-800 DEG C, and the holding time is 10-30 min.

[0009] Preferably, the acid liquid is sulfuric acid or hydrochloric acid, and the concentration of the acid liquid is 20-100 g / L.

[0010] Preferably, the acid activation temperature is 60-90 DEG C, and the time is 1-6 h.

[0011] Preferably, the alkali in the alkali liquid is one or more of sodium hydroxide, potassium hydroxide and aluminum hydroxide, and the concentration of the alkali liquid is 40-120 g / L.

[0012] Preferably, the hydrothermal reaction temperature is 80-120 DEG C, and the time is 1-4 h.

[0013] The application further provides the lithium adsorbent obtained by the preparation method.

[0014] The application further provides application of the lithium adsorbent in recycling lithium in wastewater.

[0015] The application further provides a buried lithium adsorption system, which comprises a lithium adsorption module and a protective shell of the lithium adsorption module. The lithium adsorption module comprises a shell and a lithium adsorption column contained in the shell, and the lithium adsorption column is composed of the lithium adsorbent.

[0016] Compared with the prior art, the application has the following beneficial effects: The application provides a preparation method of a lithium adsorbent, comprising the following steps: roasting lithium spodumene smelting slag and a fluorinated salt to obtain roasted slag; mixing the roasted slag and acid liquid to perform acid activation, and performing solid-liquid separation to obtain acid-activated slag; mixing the acid-activated slag and alkali liquid to perform hydrothermal reaction, washing and drying the obtained precipitate to obtain the lithium adsorbent.

[0017] The application provides a method for preparing a lithium adsorbent from spodumene smelting slag as raw material, and the lithium adsorbent is obtained by sequentially performing fluorinated salt mineralization strengthening, acid activation and alkali restructuring directional modification. + The F ions make the residual Li ions in the slag deintercalate, and the active point positions are increased; the acid liquid (such as H2SO4 / HCl) is used for activation to selectively dissolve out the impurities such as Fe and Ca in the slag, the porosity is expanded (the BET is increased by more than 30%), and the H + exchange sites are enhanced; the alkali liquid (such as NaOH / KOH) is used for treatment to perform alkali restructuring, the [AlO4] and [SiO4] skeletons are reconstructed, and the Li + specific bonding sites are formed. The lithium adsorbent prepared from the spodumene smelting slag as raw material has low cost, high adsorption capacity (the Li + adsorption capacity can reach 40 mg / g) and good cycle stability (after 20 cycles, the adsorption capacity is more than 90% of the initial value).

[0018] The application realizes high-value utilization of waste slag (spodumene smelting slag), and the spodumene smelting slag (traditional solid waste) is converted into a high-performance lithium adsorbent for the first time, which replaces the traditional aluminum-based / manganese-based adsorbent, solves the pollution problem of smelting slag storage, and meets the concept of circular economy of "waste treatment by waste".

[0019] The application also provides a buried lithium adsorption system. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only show some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 It is a preparation process flow chart of the lithium adsorbent in the embodiments. Figure 2 It is a structural schematic diagram of the buried lithium adsorption system in the application, wherein 1 is a gate plate, 2 is an automatic opening and closing machine, 3 is a stainless steel protective shell, 4 is a filler (concrete), 5 is a lithium adsorption module shell, and 6 is a lithium adsorption column. DETAILED DESCRIPTION

[0022] The application provides a preparation method of a lithium adsorbent, including the following steps: The spodumene smelting slag is mixed with a fluorinated salt and is calcined to obtain calcined slag; The roasted residue and acid solution are mixed for acid activation, followed by solid-liquid separation to obtain acid-activated residue; The acid-activated residue and alkaline solution are mixed and subjected to a hydrothermal reaction. The resulting precipitate is washed and dried to obtain a lithium adsorbent.

[0023] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0024] This invention involves mixing spodumene smelting slag with fluoride salts and calcining them to obtain calcined slag.

[0025] In this invention, the spodumene smelting slag is preferably obtained by sequentially subjecting spodumene to high-temperature transformation roasting, sulfation roasting, and water leaching; the high-temperature transformation roasting temperature is preferably 1000~1200℃, and the sulfation roasting temperature is preferably 250~300℃. The main component of the spodumene smelting slag is HAlSi2O6, which retains the "memory effect" of lithium ions due to its unique crystal structure, and can be leached by H... + -Li + Ion exchange achieves selective adsorption. The preferred composition of the spodumene smelting slag includes the following components by mass percentage: Li₂O 0~0.8%, SiO₂ 40~70%, Al 3~15%, Fe 0.1~1%, K 0.1~1.5%, Na 0.1~2%, Ca 0.05~0.5%, and Mn 0.05~0.5%; in this embodiment, it specifically includes: Li 0.2%, SiO₂ 58.3%, and Al 7.39%. This invention uses spodumene smelting slag as raw material to prepare lithium adsorbents, resulting in low preparation costs.

[0026] In this invention, the fluoride salt preferably includes one or more of sodium fluoride, calcium fluoride, and potassium fluoride. The mass of the fluoride salt is preferably 0.1-2% of the mass of the spodumene smelting slag, specifically 0.1%, 1%, or 2%. This invention uses fluoride salts to mineralize and strengthen spodumene smelting slag, utilizing F ions to deintercalate and intercalate residual Li ions in the slag, increasing active sites, thereby improving the saturated adsorption capacity and selectivity of the adsorbent, and reducing the dissolution rate.

[0027] In this invention, the roasting temperature is preferably 500~800℃, specifically 500℃, 700℃ or 800℃, and the holding time is preferably 10~30min, specifically 10min, 25min or 30min.

[0028] In this invention, the roasting process preferably includes crushing the slag, which is preferably fine grinding, and the particle size of the crushed material is preferably more than 90% smaller than 325 mesh.

[0029] After obtaining the roasted residue, the present invention mixes the roasted residue with acid solution for acid activation, and then separates the solid and liquid to obtain acid-activated residue.

[0030] In this invention, the acid solution is preferably sulfuric acid or hydrochloric acid, and the concentration of the acid solution is preferably 20~100g / L, specifically 70g / L or 100g / L; the volume ratio of the acid solution to the mass of the roasted slag (liquid-solid ratio) is preferably 3~10mL:1g, specifically 3mL:1g, 6mL:1g or 10mL:1g.

[0031] In this invention, the acid activation temperature is preferably 60~90℃, specifically 60℃, 70℃, or 90℃, and the activation time is preferably 1~6h, specifically 1h, 3h, or 6h; the acid activation is preferably carried out under ultrasound and stirring, and the ultrasonic density is preferably 0.5~1.5w / cm³. 2 Specifically, it can be 0.5w / cm 2 1w / cm 2 Or 1.5w / cm 2 The acid activation selectively dissolves impurities such as Fe and Ca in the roasted slag, increases porosity (BET increases by more than 30%), and enhances H₂O. + Exchange site.

[0032] In this invention, the solid-liquid separation is preferably filtration, and the solid-liquid separation further includes: washing and drying the solid obtained from the solid-liquid separation; the washing is preferably water washing, and the water washing is preferably stopped until the washing water is neutral; the drying is preferably stopped until constant weight.

[0033] After obtaining the acid-activated residue, the present invention mixes the acid-activated residue with an alkaline solution for a hydrothermal reaction, and washes and dries the resulting precipitate to obtain a lithium adsorbent.

[0034] In this invention, the alkali in the alkaline solution is preferably one or more of sodium hydroxide (NaOH), potassium hydroxide (KOH), and aluminum hydroxide; the concentration of the alkaline solution is preferably 40~120g / L, specifically 40g / L, 80g / L, or 120g / L.

[0035] In this invention, the preferred temperature for the hydrothermal reaction is 80~120℃, specifically 80℃, 90℃, or 120℃, and the preferred time is 1~4 hours, specifically 1 hour, 2 hours, or 4 hours. The hydrothermal reaction process preferably employs ultrasonic-enhanced precipitation, and the ultrasonic waves are preferably in a low-frequency intermittent mode, specifically operating for 10 minutes and then stopping for 5 minutes. The preferred ultrasonic wave density is 0.5~1.5 W / cm³. 2 Specifically, it can be 0.5w / cm 2 0.7w / cm 2Or 1.5w / cm 2 During the hydrothermal reaction, alkali reconstruction occurs, forming a porous aluminosilicate structure, which can improve lithium adsorption capacity. This invention reconstructs the [AlO4] and [SiO4] framework through alkali treatment to form Li… + Specific binding sites (Li + Adsorption capacity can reach 40 mg / g.

[0036] In this invention, the washing is preferably stopped when the wash water is neutral; the drying temperature is preferably 60~120℃, specifically 60℃, 100℃ or 120℃; the drying process preferably includes granulation, and the particle size of the granulated particles is preferably 1~5 mm.

[0037] The present invention also provides a lithium adsorbent obtained by the preparation method described in the above technical solution.

[0038] This invention also provides the application of the lithium adsorbent described in the above technical solution in the recovery of lithium from wastewater.

[0039] In this invention, the application of lithium recovered from wastewater preferably includes the following steps: A lithium adsorbent was used to adsorb wastewater and then separated into solid and liquid components to obtain an adsorbent enriched with lithium. The lithium-enriched adsorbent was subjected to acid elution and solid-liquid separation to obtain a lithium-enriched solution and the eluted adsorbent.

[0040] In this invention, the wastewater is preferably effluent (tailing liquid) from a spodumene smelting tailings pond; the composition of the wastewater preferably includes: Li 0~0.5g / L, Si 0~1g / L, Al 0~0.5g / L, Fe 0~0.5g / L, K 0.1~2g / L, Na 0~5g / L, Ca 0~0.6g / L, Mn 0~0.5g / L; in an embodiment of this invention, the composition of the wastewater includes: Li 0.41g / L, K 0.76g / L, Na 3.85g / L; the pH value of the wastewater is preferably 7~9, specifically 8.02.

[0041] In this invention, the adsorption is preferably carried out at room temperature (10~30℃), and the lithium adsorbent prepared by this invention has a saturated adsorption capacity of 25~40 mg / g. Solid-liquid separation after adsorption yields lithium-free water.

[0042] In this invention, the acid leaching is preferably performed by immersion in a sulfuric acid or hydrochloric acid solution; the concentration of the sulfuric acid or hydrochloric acid solution is preferably 0.1~1 mol / L; the acid leaching is preferably carried out at room temperature for 1~3 hours, specifically 1 hour, 2 hours, or 3 hours. The lithium-rich solution contains Li... +The preferred concentration is 5-20 g / L. This invention enables the recovery of residual lithium from spodumene smelting tailings.

[0043] In this invention, after obtaining the desorbed adsorbent, regeneration is preferably further included. The regeneration comprises the following steps: washing and drying the desorbed adsorbent sequentially, followed by calcination; the calcination temperature is preferably 200~300℃, specifically 200℃, 250℃, or 300℃, and the holding time is preferably 0.5~2h, specifically 0.5h, 1h, or 2h. This invention restores the adsorbent's adsorption performance through regeneration.

[0044] This invention constructs an adsorption-desorption-regeneration cycle system for lithium recovery from tailings pond wastewater, featuring a synergistic cycle of low-temperature desorption and thermal activation of the lithium adsorbent. Desorption stage: H₂SO₄ or HCl is used for desorption at room temperature, and Li₂ is desorbed... + Elution rate >95%, adsorbent loss rate <2%; Regeneration stage: High-temperature thermal activation removes organic impurities, restoring the adsorption capacity to over 90% of the initial value (after 20 cycles). The desorbed lithium-rich solution can be directly used for the preparation of electrolytic lithium salts, realizing a closed-loop process.

[0045] The present invention also provides a buried lithium adsorption system, including a lithium adsorption module and a protective shell for the lithium adsorption module; The lithium adsorption module includes a housing and a lithium adsorption column contained within the housing, the lithium adsorption column being composed of the lithium adsorbent described in the above technical solution.

[0046] In this invention, the lithium adsorption column is preferably in the form of a cuboid block structure, and the preferred dimensions of the cuboid block structure are length × width × height = 1m × 15cm × 15cm. This invention prepares the lithium adsorbent into a lithium adsorption column, which facilitates the addition or reduction of the lithium adsorbent as needed, and also facilitates the replacement of the lithium adsorbent and system maintenance.

[0047] In this invention, the bottom of the protective shell is preferably further provided with a filler for supporting the lithium adsorption module; the filler is preferably a stainless steel frame support structure or concrete.

[0048] In this invention, the protective shell is preferably made of stainless steel, and the protective shell is preferably also equipped with a gate and an automatic opening and closing mechanism to adjust the drainage volume; the drainage volume is preferably 0~1000m³. 3 / h, specifically 400~500m 3 / h.

[0049] In this invention, the buried lithium adsorption system is preferably installed in the effluent channel of the spodumene smelting tailings pond; the composition of the wastewater in the effluent channel preferably includes: Li 0~0.5g / L, Si 0~1g / L, Al 0~0.5g / L, Fe 0~0.5g / L, K 0.1~2g / L, Na 0~5g / L, Ca 0~0.6g / L, Mn 0~0.5g / L; in an embodiment of this invention, the composition of the wastewater includes: Li 0.41g / L, K 0.76g / L, Na 3.85g / L; the pH value of the wastewater is preferably 7~9, specifically 8.02.

[0050] This invention is the first of its kind to utilize an in-situ, underground, modular lithium adsorption system for spodumene smelting tailings ponds. The modular lithium adsorption device is buried underground in the tailings pond's effluent channel, integrating an adsorption shell (including a gate) and a detachable lithium adsorption column, achieving lithium recovery from tailings wastewater without the need for electricity. This invention dynamically controls water flow, and combined with the modular lithium adsorption unit, supports water volume adjustment, adsorbent addition / reduction, and backwashing maintenance.

[0051] To further illustrate the present invention, the lithium adsorbent, its preparation method and application, and the underground lithium adsorption system provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0052] Figure 1 This is a flowchart illustrating the preparation process of the lithium adsorbent in the examples.

[0053] Figure 2 This is a schematic diagram of the underground lithium adsorption system in the application example, where 1-gate, 2-automatic gate opener, 3-stainless steel protective shell, 4-filling material (concrete), 5-lithium adsorption module shell, and 6-lithium adsorption column.

[0054] Example 1 The preparation method of lithium adsorbent includes the following steps: (1) Fluoride mineralization enhancement: The slag obtained by high-temperature transformation roasting-sulfation roasting-water leaching of slag (mass percentage: Li 0.2%, SiO2 58.3%, Al 7.39%) was mixed with sodium fluoride (0.1% of the mass of slag) and roasted at 800℃ for 10 min. The roasted slag was then finely ground to make the particle size less than 325 mesh account for more than 90%.

[0055] (2) Ultrasonic acid activation: The finely ground calcined slag is placed in a reactor, and the reaction is carried out at a liquid-to-solid ratio of 3 mL:1 g, a reaction temperature of 60 °C, a sulfuric acid concentration of 100 g / L, and an ultrasonic density of 0.5 W / cm. 2 Under these conditions, the mixture was stirred and activated for 6 hours to remove surface impurities and enhance H2O. +Exchange sites. After activation, the spodumene smelting slag is filtered, washed with water until the wash water is neutral, and then dried to constant weight.

[0056] (3) Alkali reconstruction: The acid-activated spodumene smelting slag was mixed with sodium hydroxide solution (40 g / L) and hydrothermally reacted at 80 °C for 4 h. The precipitation was enhanced by ultrasound in a low-frequency intermittent mode (working for 10 min and stopping for 5 min) with an ultrasound density of 0.5 W / cm³. 2 This forms a porous aluminosilicate structure.

[0057] (4) Drying and shaping: The product is washed until neutral, dried at a low temperature of 60°C and then granulated (1~5 mm particles) to obtain lithium adsorbent.

[0058] Application Example 1 1. Lithium adsorption (enrichment) An underground lithium adsorption system was installed in the effluent channel of the spodumene smelting tailings dam. Figure 2 The adsorption system consists of a protective shell (made of stainless steel) and a lithium adsorption module, and is equipped with a gate and an automatic opening and closing mechanism to adjust the drainage volume; each lithium adsorption column has a rectangular block structure (length × width × height = 1m × 15cm × 15cm), and is composed of lithium adsorbent prepared in Example 1, with a total of 30 columns.

[0059] The tailings pond wastewater composition is Li 0.41 g / L, K 0.76 g / L, Na 3.85 g / L, and pH value 8.02.

[0060] Adsorption conditions: ambient temperature, water flow rate controlled at 400~500 m³ / h 3 / h.

[0061] The saturated adsorption capacity can reach 32.3 mg / g. After saturation, the lithium adsorption column module is replaced and proceeds to the subsequent desorption and regeneration process.

[0062] 2. Analysis and Regeneration Process Acid desorption: The saturated lithium adsorption column was removed from the buried lithium adsorption system, and the adsorption beads were poured into a 0.1 mol / L H2SO4 solution for immersion and desorption. Desorption was carried out at room temperature for 3 h to obtain a lithium-rich solution with a lithium desorption rate of 97%. After desorption, the lithium adsorbent was separated into solid and liquid phases by sieving.

[0063] Adsorbent regeneration: After desorption, the adsorbent was washed with water, dried, and then calcined at 200℃ for 2 h to restore its adsorption performance. The regenerated adsorbent was reused for adsorption and desorption cycles for 20 times, and the adsorption saturation capacity remained above 29 mg / g. The results are shown in Table 1.

[0064] Example 2 The preparation method of lithium adsorbent includes the following steps: (1) Fluoride mineralization enhancement: The slag obtained by high-temperature transformation roasting-sulfation roasting-water leaching of slag (mass percentage: Li 0.2%, SiO2 58.3%, Al 7.39%) was mixed with calcium fluoride (2% of the mass of slag) and roasted at 500℃ for 30 min. The roasted slag was then finely ground to make the particle size less than 325 mesh account for more than 90%.

[0065] (2) Ultrasonic acid activation: The finely ground calcined slag is placed in a reactor, and the reaction is carried out at a liquid-to-solid ratio of 10 mL:1 g, a reaction temperature of 90 °C, a sulfuric acid concentration of 100 g / L, and an ultrasonic density of 1.5 W / cm. 2 Under these conditions, stirring and activation were performed for 1 hour to remove surface impurities and enhance H2O. + Exchange sites. After activation, the spodumene smelting slag is filtered, washed with water until the wash water is neutral, and then dried to constant weight.

[0066] (3) Alkali reconstruction: The acid-activated spodumene smelting slag was mixed with potassium hydroxide solution (120 g / L) and hydrothermally reacted at 120 °C for 1 h. The precipitation was enhanced by ultrasound in a low-frequency intermittent mode (working for 10 min and stopping for 5 min) with an ultrasound density of 0.5 W / cm³. 2 This forms a porous aluminosilicate structure.

[0067] (4) Drying and shaping: The product is washed until neutral, dried at a low temperature of 120°C and then granulated (1~5 mm particles) to obtain lithium adsorbent.

[0068] Application Example 2 1. Lithium adsorption (enrichment) The difference from Application Example 1 is that the lithium adsorption column is composed of the lithium adsorbent prepared in Example 2.

[0069] The saturated adsorption capacity can reach 38.8 mg / g. After saturation, the lithium adsorption column module is replaced and proceeds to the subsequent desorption and regeneration process.

[0070] 2. Analysis and Regeneration Process Acid desorption: The saturated lithium adsorption column was removed from the buried lithium adsorption system, and the adsorption beads were poured into a 1 mol / L HCl solution for desorption. Desorption was carried out at room temperature for 3 h to obtain a lithium-rich solution with a lithium desorption rate of 98%. After desorption, the lithium adsorbent was separated into solid and liquid phases by sieving.

[0071] Adsorbent regeneration: After washing and drying, the adsorbent was calcined at 300℃ for 0.5 h to restore its adsorption performance. The regenerated adsorbent was reused for 20 adsorption and desorption cycles, and its adsorption saturation capacity remained above 35 mg / g. The results are shown in Table 1.

[0072] Example 3 1. A method for preparing lithium adsorbent, comprising the following steps: (1) Fluoride mineralization enhancement: The slag obtained by high-temperature transformation roasting-sulfation roasting-water leaching of slag (mass percentage: Li 0.2%, SiO2 58.3%, Al 7.39%) was mixed with potassium fluoride (1% of the mass of slag) and roasted at 700℃ for 25 min. The roasted slag was then finely ground to make the particle size less than 325 mesh account for more than 90%.

[0073] (2) Ultrasonic acid activation: The finely ground calcined slag is placed in a reactor, and the reaction is carried out at a liquid-to-solid ratio of 6 mL:1 g, a reaction temperature of 70 °C, a sulfuric acid concentration of 70 g / L, and an ultrasonic density of 1 W / cm. 2 Under these conditions, the mixture was stirred and activated for 3 hours to remove surface impurities and enhance H2O. + Exchange sites. After activation, the spodumene smelting slag is filtered, washed with water until the wash water is neutral, and then dried to constant weight.

[0074] (3) Alkali reconstruction: The acid-activated spodumene smelting slag was mixed with potassium hydroxide solution (80 g / L) and hydrothermally reacted at 90 °C for 2 h. Ultrasonic enhancement precipitation was used, with the ultrasonic waves in low-frequency intermittent mode (working for 10 min and stopping for 5 min) and the ultrasonic density being 0.7 W / cm³. 2 This forms a porous aluminosilicate structure.

[0075] (4) Drying and shaping: The product is washed until neutral, dried at 100°C and then granulated (1~5 mm particles) to obtain lithium adsorbent.

[0076] Application Example 3 1. Lithium adsorption (enrichment) The difference from Application Example 1 is that the lithium adsorption column is composed of the lithium adsorbent prepared in Example 3.

[0077] The saturated adsorption capacity can reach 36.5 mg / g. After saturation, the lithium adsorption column module is replaced and proceeds to the subsequent desorption and regeneration process.

[0078] 2. Analysis and Regeneration Process Acid desorption: The saturated lithium adsorption column was removed from the buried lithium adsorption system, and the adsorption beads were poured into a 1 mol / L H2SO4 solution for immersion and desorption. Desorption was carried out at room temperature for 2 hours to obtain a lithium-rich solution with a lithium desorption rate of 97%. After desorption, the lithium adsorbent was separated into solid and liquid phases by sieving.

[0079] Adsorbent regeneration: After washing and drying, the adsorbent was calcined at 250℃ for 1 h to restore its adsorption performance. The regenerated adsorbent was reused for adsorption and desorption cycles for 20 cycles, and the adsorption saturation capacity remained above 32 mg / g. The results are shown in Table 1.

[0080] Comparative Example 1 The adsorbent is a commercially available aluminum membrane adsorbent.

[0081] Comparative Application Example 1 1. Lithium adsorption (enrichment) The difference from Application Example 1 is that the lithium adsorption column is composed of the lithium adsorbent of Comparative Example 1.

[0082] The saturated adsorption capacity is 6.1 mg / g. After saturation, the lithium adsorption column module is replaced and proceeds to the subsequent desorption process.

[0083] 2. Analysis process The saturated lithium adsorption column was removed from the buried lithium adsorption system. The adsorption beads were poured into pure water from the adsorption column for immersion and desorption. Desorption was carried out at room temperature for 2 hours to obtain a lithium-rich solution with a lithium desorption rate of 98%. After desorption, the desorbed lithium adsorbent was separated into solid and liquid phases by sieving to obtain the desorbed adsorbent.

[0084] The adsorbent after desorption was reused for 20 cycles of adsorption and desorption. The results are shown in Table 1.

[0085] Table 1. Adsorption saturation capacity of the adsorbents in the examples and comparative examples after 20 cycles.

[0086] The selectivity and solubility loss of the adsorbents in the examples and comparative examples were tested. Selectivity: the ratio of Li / Na and Li / K concentrations (g / L) in the solution after 20 cycles. Solubility loss: the rate of change of adsorbent mass after 20 cycles. The results are shown in Table 2.

[0087] Table 2. Selectivity and dissolution rate of the adsorbents in the examples and comparative examples after 20 cycles.

[0088] This invention provides a method for preparing lithium adsorbents using spodumene smelting slag as raw material, which overcomes the problems of high cost, high solubility and poor selectivity of existing adsorbents. At the same time, it realizes the high-value-added resource utilization of smelting waste slag, and can promote the development of lithium extraction technology towards a green and sustainable direction.

[0089] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a lithium adsorbent, characterized in that, Includes the following steps: Lithium spodumene smelting slag is mixed with fluoride salts and roasted to obtain roasted slag; The roasted residue and acid solution are mixed for acid activation, followed by solid-liquid separation to obtain acid-activated residue; The acid-activated residue and alkaline solution are mixed and subjected to a hydrothermal reaction. The resulting precipitate is washed and dried to obtain a lithium adsorbent.

2. The preparation method according to claim 1, characterized in that, The fluoride salt includes one or more of sodium fluoride, calcium fluoride, and potassium fluoride, and the mass of the fluoride salt is 0.1 to 2% of the mass of spodumene smelting slag.

3. The preparation method according to claim 1 or 2, characterized in that, The roasting temperature is 500~800℃, and the holding time is 10~30min.

4. The preparation method according to claim 1, characterized in that, The acid solution is sulfuric acid or hydrochloric acid, and the concentration of the acid solution is 20~100g / L.

5. The preparation method according to claim 1 or 4, characterized in that, The acid activation temperature is 60~90℃, and the time is 1~6h.

6. The preparation method according to claim 1, characterized in that, The alkali in the alkaline solution is one or more of sodium hydroxide, potassium hydroxide, and aluminum hydroxide; the concentration of the alkaline solution is 40~120g / L.

7. The preparation method according to claim 1 or 6, characterized in that, The hydrothermal reaction is carried out at a temperature of 80~120℃ for 1~4 hours.

8. The lithium adsorbent obtained by the preparation method according to any one of claims 1 to 7.

9. The application of the lithium adsorbent according to claim 8 in the recovery of lithium from wastewater.

10. A buried lithium adsorption system, characterized in that, Includes a lithium adsorption module and a protective housing for the lithium adsorption module; The lithium adsorption module includes a housing and a lithium adsorption column contained within the housing, the lithium adsorption column being composed of the lithium adsorbent as described in claim 8.

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