A method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst

Abstract

This invention discloses a method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst, belonging to the field of metal recovery technology. The method includes the following steps: (1) grinding, sieving, and drying the tailings of the three-way catalyst; (2) ball milling in a plasma ball mill jar; (3) adding the ball-milled activated powder to a mixed acid solution and stirring to leach; (4) adding sodium hydroxide solution and stirring to adjust the pH value to generate a precipitate; (5) adding a high-concentration sodium hydroxide solution and stirring to adjust the pH value to generate a precipitate, filtering, adding magnesium powder, and stirring to carry out a displacement reaction to generate zirconium precipitate. This invention utilizes the synergistic effect of high-energy plasma electrons and mechanical impact force to accelerate the refinement, increase the specific surface area, and activate the activity of the tailings powder of the three-way catalyst. Simultaneously, it induces thermal stress to promote material breakage. This method significantly shortens the leaching time of lanthanum, cerium, and zirconium and significantly improves their recovery rates, achieving recovery rates of up to 99.98%, 99.97%, and 99.98%, respectively.

Description

Technical Field

[0001] This invention relates to the field of metal recycling technology, specifically a method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst. Background Technology

[0002] Lanthanum, cerium, and zirconium, as key strategic rare earth elements and rare metals, are core components of automotive three-way catalytic converter coatings due to their excellent catalytic activity, thermal stability, and oxygen storage capacity. They are widely used to remove CO, HC, and NO from exhaust gases. x The purification and transformation of harmful gases. With the continuous growth of global car ownership and the expiration of catalyst service life, the amount of waste three-way catalysts generated has increased year by year. The lanthanum, cerium and zirconium contained in them have become secondary resources with great recycling value, which not only alleviates the pressure of resource depletion caused by primary mining, but also conforms to the concept of circular economy development.

[0003] Currently, the main technologies for recovering lanthanum, cerium, and zirconium from ternary catalyst tailings are acid leaching, alkaline fusion, extraction, and chlorine volatilization. Acid leaching is the most widely used industrial method. This method typically involves crushing the ternary catalyst tailings and leaching them with hydrochloric acid or sulfuric acid, dissolving the lanthanum, cerium, and zirconium into the solution, and then separating them by adjusting the pH. However, the leaching rate of this method is greatly affected by the form in which the lanthanum, cerium, and zirconium exist in the tailings. If the lanthanum, cerium, and zirconium are dissolved in the carrier lattice or encapsulated by heavy metal impurities, the leaching rate is less than 70%. Alkaline fusion uses high-temperature melting of sodium hydroxide to destroy the carrier structure and release lanthanum, cerium, and zirconium, but the operating temperature needs to exceed 800℃. This method is lengthy, energy-intensive, and generates significant amounts of greenhouse gases and heavy metal pollution. Extraction uses extractants such as P2O4, which can achieve fine separation of rare earth elements. Under optimized conditions (e.g., extractant concentration of 60% and extractant pH of 3), the extraction rate of lanthanum, cerium, and zirconium can reach 95%. However, the extraction and separation process involves high reagent consumption and significant interference from impurities. The chlorine volatilization method involves heating the tailings of a three-way catalyst in a chlorine atmosphere, causing lanthanum, cerium, and zirconium to form volatile chlorides, which are then collected after condensation. Lanthanum recovery rates are approximately 70%, cerium recovery rates approximately 75%, and zirconium recovery rates approximately 60%. This method is energy-intensive, costly, and carries high safety risks. Efficient recovery of lanthanum, cerium, and zirconium is of great significance for alleviating resource shortages and achieving economic and environmental benefits. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, this invention provides a method for recovering lanthanum, cerium, and zirconium from the tailings of three-way catalysts. This method can improve the recovery rate of the target elements and has outstanding advantages of being clean, efficient, and energy-saving.

[0005] To achieve the above objectives, the technical solution of this invention is as follows: A method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst is provided, the innovation of which lies in the following steps: (1) Grind, sieve and dry the tailings of the three-way catalyst; (2) The tailings of the three-way catalyst treated in step (1) are loaded into the plasma ball mill jar, and after vacuuming, high-purity argon gas is introduced to start the plasma excitation and ball milling synchronous operation. (3) Transfer the ball-milled and activated powder into a leaching tank, add mixed acid solution and stir to leach; (4) Slowly add a low concentration of sodium hydroxide solution to the leachate, stir to adjust the pH value to generate a precipitate, filter to remove the precipitate, and obtain a purified lanthanum, cerium and zirconium mixed solution. (5) Add high-concentration sodium hydroxide solution to the purified mixed solution, stir to adjust the pH value to generate a precipitate, filter and add magnesium powder to the filtrate, stir to carry out a displacement reaction, and generate zirconium precipitate.

[0006] Preferably, in step (1), the particle size of the sieved three-way catalyst tailings waste is 50~300 mesh; the drying conditions for the sieved three-way catalyst tailings waste are: drying at 100~120 ℃ for 10~48 h.

[0007] Preferably, in step (2), the plasma ball mill jar is made of zirconium oxide.

[0008] Preferably, in step (2), the pressure of the introduced argon gas is 5~20 kPa.

[0009] Preferably, in step (2), the ball milling conditions are: ball-to-material ratio of 20:1 to 60:1, discharge power of 50 to 150 W, discharge frequency of 5 to 15 kHz, ball milling speed of 400 to 1000 r / min, and ball milling time of 30 to 90 min.

[0010] Preferably, in step (2), the particle size of the three-way catalyst after ball milling is 200~800 nm.

[0011] Preferably, in step (3), the mixed acid solution is formed by mixing H2SO4 and HCl at a volume ratio of 1:3, the concentration of H2SO4 is 15~25%, the concentration of HCl is 30~50%, the liquid-solid ratio of the mixed acid solution and the tailings powder of the three-way catalyst is 3-6 mL:1 g, and the acid leaching stirring time is 30~90 min.

[0012] Preferably, in step (4), the concentration of the added sodium hydroxide solution is 0.5~2.0 mol / L, the dropping rate is 1.0~5.0 mL / min, and the pH of the solution is adjusted to 3-7 by adding a low concentration of sodium hydroxide solution.

[0013] Preferably, in step (5), the concentration of the added sodium hydroxide solution is 4.0~8.0 mol / L, the dropping rate is 0.5~2.0 mL / min, and the pH value of the solution is adjusted to 8-13 by adding high concentration sodium hydroxide solution.

[0014] The reaction process of adding low-concentration sodium hydroxide solution in this invention is as follows: (1) Neutralize excess acid: H + + OH - → H2O (2) Aluminum ion precipitation (the ternary catalyst is mainly composed of aluminum oxide, and aluminum impurities are removed by a low-concentration sodium hydroxide solution): Al³ + + 3OH - → Al(OH)3↓ The reaction process of adding high-concentration sodium hydroxide solution: (1) Lanthanum ion precipitation: La³ + + 3OH - → La(OH)3↓ (2) Cerium ion precipitation: Ce³ + + 3OH - → Ce(OH)3↓ (3) Zirconium forms soluble hydroxyl complexes: Zr 4+ + 8OH - → [Zr(OH)8] 4- (4) Magnesium powder replacing metallic zirconium: Zr 4+ + 2Mg → Zr↓ + 2Mg² + This invention utilizes the synergistic effect of high-energy electrons from plasma and mechanical impact to pretreat tailings waste from three-way catalytic converters. Its mechanism and effects are as follows: 1. Regarding the catalyst tailings waste itself Powder refinement and increased specific surface area: High-energy electrons in the plasma bombard tailings waste particles, generating instantaneous energy deposition, while mechanical ball milling provides continuous impact and shear forces. The synergistic effect of these two processes causes dislocation slip, grain boundary cracking, and grain fragmentation, efficiently refining micron-sized particles to nano-sized particles, significantly increasing the material's specific surface area, and exposing more unreacted fresh crystal faces.

[0015] Activation of active sites: Continuous bombardment by high-energy electrons induces a large number of lattice defects such as vacancies, interstitial atoms, and dislocations within the tailings material, disrupting the stable chemical bonds between elements such as lanthanum, cerium, and zirconium and the support. Simultaneously, active particles in the plasma environment (such as O...) - N + It reacts with the material surface to form new active functional groups, significantly enhancing the chemical activity of the target metal element.

[0016] Thermal stress-induced material breakage: The instantaneous high temperature generated by plasma discharge and the ambient temperature inside the ball mill cavity create a huge temperature difference, generating a strong thermal stress gradient inside the particles. This thermal stress, combined with mechanical impact force, exacerbates the crack propagation and breakage inside the particles, making the originally dense catalyst tailings waste structure loose and porous, greatly improving the mass transfer efficiency of the leachate.

[0017] 2. Its role in subsequent leaching and recovery treatment. Significantly reduced leaching time: After plasma ball milling pretreatment, the catalyst particles are finer, have a larger specific surface area, and more lattice defects. The contact area and reactivity between the leaching solution and the target metal are significantly improved, allowing the leaching process that originally took several hours to be completed in tens of minutes, greatly shortening the process cycle and improving production efficiency.

[0018] Significantly improved metal recovery rate: Traditional grinding methods struggle to completely destroy the stable structure of catalysts, resulting in some lanthanum, cerium, and zirconium being trapped within the support and unable to leach out. The synergistic effect of plasma ball milling effectively breaks down this trapping, increasing the leaching rate of the target metal from 70%–80% using traditional methods to over 99%, significantly improving resource utilization and economic benefits.

[0019] Compared with traditional grinding methods, this method fundamentally changes the physicochemical properties of the tailings waste of three-way catalysts through the synergistic effect of plasma and mechanical force, significantly shortens the leaching time of lanthanum, cerium, and zirconium, and greatly improves the recovery rate of lanthanum, cerium, and zirconium, providing an innovative pretreatment technology for the efficient resource utilization of waste three-way catalysts.

[0020] This invention provides a method for recovering lanthanum, cerium, and zirconium from the tailings of three-way catalysts, which has the following beneficial effects: (1) This invention uses the synergistic effect of high-energy plasma electrons and mechanical impact force to accelerate the finening, increase the specific surface area and activate the activity of the three-way catalyst tailings waste powder. At the same time, it induces thermal stress to promote material crushing. Compared with traditional grinding methods, this method significantly shortens the leaching time of lanthanum, cerium and zirconium and significantly improves the recovery rate of lanthanum, cerium and zirconium. The recovery rates of lanthanum, cerium and zirconium are as high as 99.98%, 99.97% and 99.98% respectively, realizing the efficient recovery of lanthanum, cerium and zirconium in the tailings waste of the three-way catalyst.

[0021] (2) The present invention adopts the synergistic effect of high-energy electrons and mechanical impact force of plasma. Compared with the traditional single mechanical energy ball mill, the synergistic effect of multiple fields significantly improves the ball milling efficiency. The plasma is generated by the ionization of pure gas, without secondary pollution, and can efficiently treat environmental solid waste, which meets the needs of resource recycling and green development.

[0022] (3) The present invention can achieve efficient activation without adding any additives when using plasma ball milling, which simplifies the process and reduces costs.

[0023] (4) The present invention uses the tailings waste of the three-way catalyst, which is one of the raw materials in the lanthanum, cerium and zirconium recovery process. The recovery can transform the waste into "secondary resources", which can effectively supplement the raw materials of industrial production, reduce the dependence on primary minerals, and ensure the safety of the industrial chain and supply chain. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of the present invention.

[0025] Figure 2 This is the XRD pattern of the tailings waste from a three-way catalyst. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the content described.

[0027] The tailings waste of the three-way catalyst of the present invention includes tailings waste after precious metals are captured by any one of lead, copper, copper matte, iron, bismuth, silicon and tin using pyrometallurgical methods.

[0028] The process flow of a method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to the present invention is as follows: Figure 1 As shown.

[0029] Example 1 This embodiment describes a method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst using plasma ball milling technology. The specific steps include: (1) Grind and sieve the tailings of the three-way catalyst to a particle size of 200 mesh, and dry it in a 110 ℃ drying oven for 36 h.

[0030] (2) The pretreated three-way catalyst tailings waste was loaded into a zirconia plasma ball mill jar. After vacuuming, high-purity argon gas with a pressure of 10 kPa was introduced. The plasma excitation and ball milling were started simultaneously. The ball-to-material ratio was 40:1, the plasma discharge power was 150 W, the frequency was 15 kHz, the ball milling speed was 1000 r / min, and the ball milling time was 90 min.

[0031] (3) The ternary catalyst tailings waste powder after plasma ball milling is acid leached. The acid leaching is carried out by soaking in a mixed acid solution composed of 15% H2SO4 and 30% HCl, wherein the volume ratio of H2SO4 to HCl is 1:3, the liquid-solid ratio of the mixed acid solution to the ternary catalyst tailings waste powder is 3 mL:1 g, and the stirring time is 90 min.

[0032] (4) Add sodium hydroxide solution with a concentration of 1.0 mol / L to the leachate at a dropping rate of 2.0 mL / min, stir to adjust the pH value to 5, so that impurities such as aluminum are hydrolyzed to form hydroxide precipitates, filter to remove the precipitates, and obtain a purified lanthanum, cerium and zirconium mixed solution.

[0033] (5) Add sodium hydroxide solution with a concentration of 6.0 mol / L to the purified solution at a dropping rate of 2.0 mL / min, stir and adjust the pH value to 10. Lanthanum and cerium will form La(OH)3 and Ce(OH)3 precipitates respectively. Add magnesium powder to the filtered filtrate (containing zirconium ions), stir and react to form zirconium precipitate.

[0034] Calculations show that the particle size of the ternary catalyst tailings waste after plasma ball milling in this embodiment is 200 nm, and the recovery rates of lanthanum, cerium, and zirconium are 99.98%, 99.97%, and 99.98%, respectively.

[0035] Example 2 The difference between this embodiment and Embodiment 1 is that: In step (1), the sieved fertilizer is placed in a drying oven at 105 ℃ and dried for 24 h.

[0036] In step (2), after evacuation, high-purity argon gas with a pressure of 20 kPa is introduced, the ball milling speed is 800 r / min, and the ball milling time is 30 min.

[0037] In step (5), sodium hydroxide solution with a concentration of 4.0 mol / L is added to the purification solution at a dropping rate of 0.5 mL / min.

[0038] The rest is the same as in Example 1. According to calculations, the particle size of the ternary catalyst tailings waste after plasma ball milling in this example is 600 nm, and the recovery rates of lanthanum, cerium and zirconium are 92.38%, 89.36% and 85.73%, respectively.

[0039] Example 3 The difference between this embodiment and Embodiment 1 is that: In step (1), the tailings waste of the three-way catalyst is ground and sieved to a particle size of 300 mesh, and then dried in a 120 ℃ drying oven for 48 h.

[0040] In step (2), the plasma discharge power is 100 W, the ball milling speed is 800 r / min, and the ball milling time is 60 min.

[0041] In step (3), the liquid-solid ratio of the mixed acid solution to the ternary catalyst tailings waste powder is 6 mL:1 g, and the stirring time is 60 min.

[0042] In step (5), sodium hydroxide solution with a concentration of 8.0 mol / L is added to the purification solution at a dropping rate of 1.0 mL / min.

[0043] The rest is the same as in Example 1. According to calculations, the particle size of the tailings waste of the three-way catalyst after plasma ball milling in this example is 400 nm, and the recovery rates of lanthanum, cerium and zirconium are 96.34%, 95.21% and 93.47%, respectively.

[0044] Example 4 The difference between this embodiment and Embodiment 1 is that: In step (1), the tailings waste of the three-way catalyst is ground and sieved to a particle size of 200 mesh, and then dried in a drying oven at 105 ℃ for 24 h.

[0045] In step (2), the plasma discharge power is 100 W, the ball milling speed is 800 r / min, and the ball milling time is 60 min.

[0046] In step (3), acid leaching is performed using a mixed acid solution consisting of 20% H2SO4 and 40% HCl. The liquid-to-solid ratio of the mixed acid solution to the tailings waste powder of the three-way catalyst is 6 mL:1 g, and the stirring time is 60 min.

[0047] In step (5), sodium hydroxide solution with a concentration of 8.0 mol / L is added to the purification solution at a dropping rate of 2.0 mL / min.

[0048] The rest is the same as in Example 1. According to calculations, the particle size of the ternary catalyst tailings waste after plasma ball milling in this example is 300 nm, and the recovery rates of lanthanum, cerium and zirconium are 96.32%, 95.91% and 96.14%, respectively.

[0049] Example 5 The difference between this embodiment and Embodiment 1 is that: In step (1), the tailings waste of the three-way catalyst is ground and sieved to a particle size of 200 mesh, and then dried in a drying oven at 105 ℃ for 24 h.

[0050] In step (2), the plasma discharge power is 100 W and the ball milling speed is 800 r / min.

[0051] In step (3), acid leaching is performed using a mixed acid solution consisting of 25% H2SO4 and 50% HCl. The liquid-to-solid ratio of the mixed acid solution to the tailings waste powder of the three-way catalyst is 6 mL:1 g, and the stirring time is 60 min.

[0052] In step (4), the concentration of sodium hydroxide solution added to the leachate is 1.0 mol / L, and the dropping rate is 4.0 mL / min. In step (5), the concentration of sodium hydroxide solution added to the purification solution is 5.0 mol / L, and the dropping rate is 1.0 mL / min.

[0053] The rest is the same as in Example 1. According to calculations, the particle size of the tailings waste of the three-way catalyst after plasma ball milling in this example is 500 nm, and the recovery rates of lanthanum, cerium and zirconium are 91.36%, 90.03% and 88.34%, respectively.

[0054] Example 6 The difference between this embodiment and Embodiment 1 is that: In step (1), the tailings waste of the three-way catalyst is ground and sieved to a particle size of 200 mesh, and then dried in a drying oven at 105 ℃ for 24 h.

[0055] In step (2), the plasma discharge power is 100 W, the ball milling speed is 800 r / min, and the ball milling time is 60 min.

[0056] In step (3), the acid leaching is performed using a mixed acid solution consisting of 15% H2SO4 and 30% HCl, with a stirring time of 90 min.

[0057] In step (5), sodium hydroxide solution with a concentration of 8.0 mol / L is added to the purification solution at a dropping rate of 0.5 mL / min.

[0058] The rest is the same as in Example 1. According to calculations, the particle size of the ternary catalyst tailings waste after plasma ball milling in this example is 400 nm, and the recovery rates of lanthanum, cerium and zirconium are 94.17%, 93.02% and 90.63%, respectively.

[0059] Example 7 This embodiment describes a method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst using plasma ball milling technology. The specific steps include: (1) Grind and sieve the tailings of the three-way catalyst to a particle size of 50 mesh, and dry it in a 105 ℃ drying oven for 10 h.

[0060] (2) The pretreated three-way catalyst tailings waste was loaded into a zirconia plasma ball mill jar. After vacuuming, high-purity argon gas with a pressure of 5 kPa was introduced. The plasma excitation and ball milling were started simultaneously. The ball-to-material ratio was 20:1, the plasma discharge power was 150 W, the frequency was 5 kHz, the ball milling speed was 400 r / min, and the ball milling time was 60 min.

[0061] (3) The ternary catalyst tailings waste powder after plasma ball milling is acid leached. The acid leaching is carried out by soaking in a mixed acid solution composed of 15% H2SO4 and 30% HCl, wherein the volume ratio of H2SO4 to HCl is 1:3, the liquid-solid ratio of the mixed acid solution to the ternary catalyst tailings waste powder is 5 mL:1 g, and the stirring time is 60 min.

[0062] (4) Add sodium hydroxide solution with a concentration of 0.5 mol / L to the leachate at a dropping rate of 1.0 mL / min, stir to adjust the pH value to 3, so that impurities such as aluminum are hydrolyzed to form hydroxide precipitates, filter to remove the precipitates, and obtain a purified lanthanum, cerium and zirconium mixed solution.

[0063] (5) Add sodium hydroxide solution with a concentration of 6.0 mol / L to the purified solution at a dropping rate of 0.5 mL / min, stir and adjust the pH value to 8. Lanthanum and cerium will form La(OH)3 and Ce(OH)3 precipitates respectively. Add magnesium powder to the filtered filtrate (containing zirconium ions), stir and react to form zirconium precipitate.

[0064] Calculations show that the particle size of the ternary catalyst tailings waste after plasma ball milling in this embodiment is 400 nm, and the recovery rates of lanthanum, cerium, and zirconium are 95.11%, 93.28%, and 90.97%, respectively.

[0065] Example 8 This embodiment describes a method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst using plasma ball milling technology. The specific steps include: (1) Grind and sieve the tailings of the three-way catalyst to a particle size of 300 mesh, and dry it in a 120 ℃ drying oven for 48 h.

[0066] (2) The pretreated three-way catalyst tailings waste was loaded into a zirconia plasma ball mill jar. After evacuation, high-purity argon gas with a pressure of 20 kPa was introduced. The plasma excitation and ball milling were started simultaneously. The ball-to-material ratio was 60:1, the plasma discharge power was 50 W, the frequency was 10 kHz, the ball milling speed was 600 r / min, and the ball milling time was 30 min.

[0067] (3) The ternary catalyst tailings waste powder after plasma ball milling is acid leached. The acid leaching is carried out by soaking in a mixed acid solution composed of 15% H2SO4 and 30% HCl, wherein the volume ratio of H2SO4 to HCl is 1:3, the liquid-solid ratio of the mixed acid solution to the ternary catalyst tailings waste powder is 3 mL:1 g, and the stirring time is 30 min.

[0068] (4) Add sodium hydroxide solution with a concentration of 2.0 mol / L to the leachate at a dropping rate of 3.0 mL / min, stir to adjust the pH value to 7, so that impurities such as aluminum are hydrolyzed to form hydroxide precipitates, filter to remove the precipitates, and obtain a purified lanthanum, cerium and zirconium mixed solution.

[0069] (5) Add sodium hydroxide solution with a concentration of 4.0 mol / L to the purified solution at a dropping rate of 2.0 mL / min, stir and adjust the pH value to 13. Lanthanum and cerium will form La(OH)3 and Ce(OH)3 precipitates respectively. Add magnesium powder to the filtered filtrate (containing zirconium ions), stir and react to form zirconium precipitate.

[0070] Calculations show that the particle size of the ternary catalyst tailings waste after plasma ball milling in this embodiment is 300 nm, and the recovery rates of lanthanum, cerium, and zirconium are 94.94%, 92.86%, and 92.04%, respectively.

[0071] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: In step (2), the pretreated three-way catalyst tailings waste is loaded into the planetary ball mill jar for ball milling, with a ball-to-material ratio of 10:1, a ball milling speed of 800 r / min, and a ball milling time of 60 min.

[0072] According to calculations, the particle size of the ternary catalyst tailings waste after plasma ball milling in this example is 2 μm, and the recovery rates of lanthanum, cerium, and zirconium are 46.95%, 42.16%, and 38.73%, respectively.

[0073] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: In step (2), the pretreated three-way catalyst tailings waste is loaded into the planetary ball mill jar for ball milling, wherein the ball-to-material ratio is 20:1, the ball milling speed is 1000 r / min, and the ball milling time is 90 min.

[0074] The rest is the same as in Example 1. According to calculations, the particle size of the tailings waste of the three-way catalyst after plasma ball milling in this example is 2 μm, and the recovery rates of lanthanum, cerium and zirconium are 34.39%, 29.67% and 35.96%, respectively.

[0075] Comparing the recovery rates of Example 1 and Comparative Examples 1-2, it can be seen that, compared to planetary ball milling technology, plasma ball milling technology, as a combination of mechanical alloying and cold-field plasma, achieves the coupled utilization of mechanical energy and plasma energy by constructing a plasma field and mechanical collisions within the milling jar. This technology utilizes highly active plasma particles (ions, electrons, free radicals, etc.) to bombard the powder surface, combined with a unique "thermal explosion-melting-quenching" refining mechanism, which can rapidly break the material's crystal structure, generate numerous defects, and activate the surface. Simultaneously, it avoids the contamination problems and inefficiency bottlenecks of traditional ball milling, and can significantly reduce the activation energy and reaction temperature of subsequent reactions. Compared to traditional processes, plasma ball milling can effectively disrupt the bonding morphology of lanthanum, cerium, and zirconium with the alumina support in the tailings of three-way catalysts, solving the problem of lanthanum, cerium, and zirconium solid solutions. This provides highly active raw materials for subsequent leaching and separation processes, significantly improving the recovery rate of target elements. It also has outstanding advantages of being clean, efficient, and energy-saving, providing a new technical path for the efficient recovery of lanthanum, cerium, and zirconium from the tailings of three-way catalysts, which aligns with current environmental policies and industrial upgrading needs.

[0076] Comparative Example 3 The difference between this comparative example and Example 1 is as follows: In step (2), the ball-to-material ratio is 5:1, the plasma discharge power is 40 W, the frequency is 4 kHz, the ball milling speed is 300 r / min, and the ball milling time is 20 min.

[0077] The rest is the same as in Example 1. According to calculations, the particle size of the tailings waste of the three-way catalyst after plasma ball milling in this example is 2 μm, and the recovery rates of lanthanum, cerium and zirconium are 36.98%, 32.16% and 40.55%, respectively.

[0078] Comparing the recovery rates of Example 1 and Comparative Example 3, it can be seen that low ball-to-material ratio, low discharge power, low discharge frequency, low ball milling speed and time all lead to insufficient grinding of the three-way catalyst tailings, directly affecting the ball milling effect of lanthanum, cerium, and zirconium in the three-way catalyst tailings, and thus affecting the recovery rate.

[0079] Comparative Example 4 The difference between this comparative example and Example 1 is as follows: In step (3), acid leaching is performed using a mixed acid solution consisting of 10% H2SO4 and 20% HCl, with a volume ratio of 1:2 between H2SO4 and HCl. The liquid-solid ratio of the mixed acid solution to the tailings waste powder of the three-way catalyst is 2 mL:1 g, and the stirring time is 20 min.

[0080] The rest is the same as in Example 1. According to calculations, the particle size of the ternary catalyst tailings waste after plasma ball milling in this example is 200 nm, and the recovery rates of lanthanum, cerium and zirconium are 40.98%, 32.86% and 48.75%, respectively.

[0081] Comparative Example 5 The difference between this comparative example and Example 1 is as follows: In step (3), the volume ratio of H2SO4 to HCl is 1:6, the liquid-solid ratio of the mixed acid solution to the three-way catalyst tailings waste powder is 2 mL:1 g, and the stirring time is 10 min.

[0082] The rest is the same as in Example 1. According to calculations, the particle size of the ternary catalyst tailings waste after plasma ball milling in this example is 200 nm, and the recovery rates of lanthanum, cerium and zirconium are 49.78%, 36.76% and 49.15%, respectively.

[0083] Comparing the recovery rates of Example 1 and Comparative Examples 4 and 5, it can be seen that excessively low concentrations of acidic solution, excessively low / excessively high volume ratios of acidic solution, low liquid-to-solid ratios of mixed acid solution and ternary catalyst tailings waste powder, and excessively short stirring times are all detrimental to the efficient leaching of lanthanum, cerium, and zirconium from the ternary catalyst tailings waste. This, in turn, affects the recovery efficiency of lanthanum, cerium, and zirconium from the ternary catalyst tailings waste.

[0084] Comparative Example 6 The difference between this comparative example and Example 1 is as follows: In step (4), the sodium hydroxide solution is added to the leachate at a rate of 6.0 mL / min.

[0085] In step (5), sodium hydroxide solution is added to the purification solution at a rate of 3.0 mL / min.

[0086] The rest is the same as in Example 1. According to calculations, the particle size of the tailings waste of the three-way catalyst after plasma ball milling in this example is 200 nm, and the recovery rates of lanthanum, cerium and zirconium are 55.91%, 48.86% and 45.47%, respectively.

[0087] Comparing the recovery rates of Example 1 and Comparative Example 6, it can be seen that in the recovery of lanthanum, cerium, and zirconium, an excessively high dropping rate affects the recovery effect of lanthanum, cerium, and zirconium due to insufficient reaction, resulting in a low recovery rate.

[0088] Comparative Example 7 The difference between this comparative example and Example 1 is as follows: Step (4) Add sodium hydroxide solution and stir to adjust the pH value to 9.

[0089] Step (5) Continue to add sodium hydroxide solution to the purified solution and stir to adjust the pH value to 14.

[0090] Calculations show that the particle size of the ternary catalyst tailings waste after plasma ball milling in this embodiment is 200 nm, and the recovery rates of lanthanum, cerium, and zirconium are 55.38%, 59.87%, and 63.46%, respectively.

[0091] Comparing the recovery rates of Example 1 and Comparative Example 7, it can be seen that when sodium hydroxide solution is added for precipitation and elemental separation, the adjusted pH will cause lanthanum, cerium, zirconium, etc. to precipitate prematurely and then be separated by filtration, resulting in low recovery rates of lanthanum, cerium, and zirconium, which in turn affects the recovery effect of lanthanum, cerium, and zirconium in the tailings of the three-way catalyst.

[0092] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst, characterized in that: Includes the following steps: (1) Grind, sieve and dry the tailings of the three-way catalyst; (2) The tailings of the three-way catalyst treated in step (1) are loaded into the plasma ball mill jar, and after vacuuming, high-purity argon gas is introduced to start the plasma excitation and ball milling synchronous operation. (3) Add the ball-milled and activated powder to the mixed acid solution and stir to leach it; (4) Slowly add a low concentration of sodium hydroxide solution to the leachate, stir to adjust the pH value to generate a precipitate, filter to remove the precipitate, and obtain a purified lanthanum, cerium and zirconium mixed solution. (5) Add high-concentration sodium hydroxide solution to the purified mixed solution, stir to adjust the pH value to generate a precipitate, filter and add magnesium powder to the filtrate, stir to carry out a displacement reaction, and generate zirconium precipitate.

2. The method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to claim 1, characterized in that: In step (1), the particle size of the sieved three-way catalyst tailings waste is 50~300 mesh; the drying conditions for the sieved three-way catalyst tailings waste are: drying at 100~120 ℃ for 10~48 h.

3. The method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to claim 1, characterized in that: In step (2), the plasma ball mill jar is made of zirconium oxide.

4. The method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to claim 1, characterized in that: In step (2), the pressure of the introduced argon gas is 5~20 kPa.

5. The method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to claim 1, characterized in that: In step (2), the ball milling conditions are: ball-to-material ratio of 20:1 to 60:1, discharge power of 50 to 150 W, discharge frequency of 5 to 15 kHz, ball milling speed of 400 to 1000 r / min, and ball milling time of 30 to 90 min.

6. The method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to claim 1, characterized in that: In step (2), the particle size of the three-way catalyst after ball milling is 200~800nm.

7. The method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to claim 1, characterized in that: In step (3), the mixed acid solution is formed by mixing H2SO4 and HCl at a volume ratio of 1:3, with the concentration of H2SO4 being 15-25% and the concentration of HCl being 30-50%. The liquid-solid ratio of the mixed acid solution and the tailings powder of the three-way catalyst is 3-6 mL:1 g, and the acid leaching and stirring time is 30-90 min.

8. The method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to claim 1, characterized in that: In step (4), the concentration of the added sodium hydroxide solution is 0.5~2.0 mol / L, the dropping rate is 1.0~5.0 mL / min, and the pH of the solution is adjusted to 3-7 by adding a low concentration of sodium hydroxide solution.

9. The method for recovering lanthanum, cerium, and zirconium from the tailings of a three-way catalyst according to claim 1, characterized in that: In step (5), the concentration of the added sodium hydroxide solution is 4.0~8.0 mol / L, the dropping rate is 0.5~2.0 mL / min, and the pH of the solution is adjusted to 8-13 by adding high concentration sodium hydroxide solution.

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