Method for preparing tellurium and cadmium by electrolyzing cadmium telluride through solid anode

Abstract

The invention discloses a method for preparing tellurium and cadmium by electrolyzing cadmium telluride through a solid anode, and belongs to the technical field of electrochemical metallurgy. Comprising the following steps: S1, determining an electrochemical deposition voltage: determining the deposition voltage of a solid raw material containing cadmium telluride through an electrochemical test by taking a eutectic solvent as an electrolyte; s2, a cadmium telluride electrode is prepared, specifically, a material loading cavity with an opening is formed in the inert electrode, and a solid-state raw material containing cadmium telluride is loaded into the material loading cavity to serve as an anode; s3, electrochemical deposition: taking the eutectic solvent in the step S1 as a deposition solution, taking the cadmium telluride electrode in the step S2 as an anode, matching with a cathode, ensuring that the raw materials in the material loading cavity are immersed in the deposition solution, and applying the electrolytic voltage determined in the step S1 to perform electrochemical deposition; and after deposition is finished, metal tellurium is deposited in the material loading cavity of the anode, and elemental cadmium is deposited on the surface of the cathode. The method can realize low-temperature one-step direct separation of cadmium telluride.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical metallurgy technology, and more specifically, relates to a method for preparing tellurium and cadmium by solid-state anodic electrolysis of cadmium telluride. Background Technology

[0002] Tellurium (Te) is an extremely rare dispersed metal, present in very low amounts in the Earth's crust and rarely found as an independent mineral; it is primarily found as an associated element in the smelting of metals such as copper and lead. Tellurium plays an irreplaceable role in photovoltaics, electronics, and alloys. High-purity tellurium is a crucial raw material for preparing novel semiconductor materials, thermoelectric materials, and alloy additives, possessing extremely high added value. Therefore, tellurium recycling is a vital means of ensuring supply.

[0003] Cadmium (Cd) also lacks independent deposits, primarily occurring as a byproduct of zinc deposits, and its reserves are relatively limited. Recycling cadmium allows for its solidification and safe resource utilization, avoiding the high costs of treating it as toxic waste. Cadmium and its compounds are highly toxic heavy metals. If discarded cadmium telluride components are carelessly discarded or improperly handled, cadmium can seep into soil and groundwater, accumulate through the food chain, and ultimately severely harm ecosystems and human health (such as damaging kidneys and bones). High-purity cadmium can be used to manufacture nuclear control cadmium rods, high-performance batteries, and optoelectronic materials. Therefore, the safe recycling and solidification of cadmium is an essential environmental responsibility.

[0004] CdTe thin-film batteries are highly efficient, low-cost, and pollution-free, making them not only the most commercially successful thin-film battery but also a major future direction for solar cell technology. Driven by my country's "dual-carbon" strategy, the rapid growth of the CdTe thin-film solar cell market will continue to drive up the demand for cadmium telluride (CdTe) resources. It is predicted that by 2040, global demand for cadmium and telluride will increase sevenfold, leading to a shortage of 1300 tons of cadmium and 1400 tons of tellurium. However, the tellurium and cadmium used in the manufacture of CdTe thin-film batteries are almost entirely derived from byproducts of Cu and Zn. Approximately 90% of tellurium is produced from anode mud in the copper electrolytic refining process, with the remainder mainly recovered from byproducts of lead, gold, and zinc smelting. Compared to copper, tellurium has a lower economic value, and increasing tellurium extraction independently, without considering copper production constraints, is not economically feasible. In addition to copper anode mud, it is urgent to expand diversified supply channels for tellurium resources to address the imminent shortage crisis. It is projected that by 2040, 10% to 50% of the tellurium required for CdTe photovoltaic production will come from retired modules. Therefore, recovering the rare element tellurium and the heavy metal cadmium from discarded CdTe modules can both alleviate the supply crisis of strategic resources and reduce environmental risks.

[0005] Currently, the recovery of cadmium telluride (Cd) mainly employs two technical routes: hydrometallurgy and pyrometallurgy. Hydrometallurgical recovery utilizes a strong acid oxidation system, leveraging the synergistic effect of protons and oxidants to oxidize and break the Cd-Te bonds, allowing tellurium and cadmium to leach into the liquid phase in ionic form. Subsequent recovery is achieved through precipitation, ion exchange, and electrodeposition. Hydrometallurgical recovery faces the triple challenges of high cost, severe environmental pollution, and incomplete separation of tellurium and cadmium. Future technological advancements need to focus on short processes and low-toxicity reagents to meet the green and circular demands of the photovoltaic industry. Pyrometallurgical recovery utilizes high-temperature fields to achieve efficient dissociation of Cd-Te bonds, phase reconstruction, and enhanced separation. Recovery can be achieved through chlorination volatilization, oxidative roasting, and sulfidation-vacuum distillation. While pyrometallurgical recovery has a short process and no wastewater discharge, it suffers from high energy consumption, low recovery rates, and severe secondary pollution.

[0006] Whether using wet or pyrometallurgical processes, the core principle is to treat the separation and extraction of tellurium and cadmium as two or more independent chemical processes in series. This multi-step separation not only increases process complexity and cost but also exacerbates energy consumption and environmental burden. There are existing technologies that describe one-step separation of tellurium and cadmium.

[0007] A search revealed a Chinese patent application (No. 202210710706.1, published on November 15, 2022) disclosing a method for simultaneously extracting metal and tellurium from solid-state semiconductor telluride via molten salt electrolysis. This patent uses semiconductor telluride as a raw material, melting and casting it into a rod-shaped electrode under vacuum conditions. This electrode is then used as the cathode in a chloride molten salt electrolysis process, yielding a metal at the cathode and simultaneously obtaining elemental tellurium at the anode. The semiconductor telluride is selected from, but is not limited to, bismuth telluride, zinc telluride, cadmium telluride, lead telluride, tin telluride, indium telluride, and gallium telluride. However, this electrolysis requires temperatures exceeding 500°C, resulting in high time and energy consumption. Furthermore, due to the very strong chemical bonds in solid-state CdTe, directly extracting Cd from its crystal lattice is challenging. 2+ Restored to Cd 0 Overcoming a huge energy barrier is necessary. On the one hand, very high voltages are required, resulting in extremely low energy efficiency and making it uneconomical. On the other hand, the reaction can only occur in limited regions where ions can easily migrate (such as surfaces, grain boundaries, dislocations, etc.), making it impossible to achieve uniform and complete electrolysis of materials.

[0008] In summary, there is an urgent need to develop a method for preparing tellurium and cadmium by solid-state anodic electrolysis of cadmium telluride. Summary of the Invention

[0009] 1. The problem to be solved The purpose of this invention is to provide a method for preparing tellurium and cadmium by solid-state anode electrolysis of cadmium telluride, aiming to solve the key bottleneck problems of existing CdTe recovery technology, such as complex process, high cost, heavy pollution, and low separation efficiency, and to achieve direct one-step separation of cadmium telluride at low temperature.

[0010] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: According to the purpose of this invention, a method for preparing tellurium and cadmium by solid-state anodic electrolysis of cadmium telluride is provided, comprising the following steps: S1. Determine the electrochemical deposition voltage: Using a eutectic solvent as the electrolyte, determine the deposition voltage of the solid raw material containing cadmium telluride through electrochemical testing. S2. Preparation of cadmium telluride electrode: An open material loading chamber is opened inside the inert electrode, and solid raw material containing cadmium telluride is loaded into the material loading chamber as the anode; S3. Electrochemical deposition: Using the eutectic solvent of step S1 as the deposition solution, the cadmium telluride electrode of step S2 as the anode, and a cathode, the raw material in the loading chamber is immersed in the deposition solution. The electrolysis voltage determined in step S1 is applied to perform electrochemical deposition. After deposition, metallic tellurium is deposited in the loading chamber of the anode, and elemental cadmium is deposited on the surface of the cathode.

[0011] When employing the above technical solution, on the one hand, the deposition solution of this invention uses a eutectic solvent (DES). Compared with traditional aqueous solutions, DES has a wider electrochemical window and can withstand higher anodic potentials while avoiding solvent decomposition. Furthermore, it possesses higher electrical conductivity and thermal stability. By adjusting the composition and electrolysis conditions, Te and Cd can be selectively dissolved for easy separation and recovery. At lower temperature conditions, this invention provides a more ideal and significantly advantageous technical approach for the direct one-step separation of cadmium telluride into metallic tellurium and elemental cadmium. This direct separation mode fundamentally simplifies the process, reduces energy consumption, minimizes pollution, and improves resource recovery efficiency.

[0012] On the other hand, this invention uses an inert electrode as a carrier to fill a solid raw material containing cadmium telluride, eliminating the step of melting and casting the solid raw material into a rod-shaped electrode, saving energy and cost. It allows for direct anodic electrolysis of solid powder. Furthermore, the powdered cadmium telluride solid raw material serves as the anode, and during the deposition process, the anodic reaction preferentially originates from the oxidation of Te. 2- Initially, this process directly disrupts the stable lattice of CdTe, causing the bound Cd to... 2+ The surface CdTe is exposed. After the surface CdTe is oxidized and dissolved, the underlying fresh CdTe surface is exposed, allowing the deposited solution to continue to penetrate and react. This process is a surface-to-inside corrosion, rather than relying on solid-state ion diffusion (e.g., directly using CdTe electrode rods). Therefore, the anodic reaction of this invention can continue until the solid raw material in the loading chamber is completely dissolved.

[0013] As one possible implementation, in step S1, the eutectic solvent contains chloride ions, wherein the molar concentration of chloride ions is 2 mol / L to 5 mol / L.

[0014] As one possible implementation, in step S1, the eutectic solvent includes a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is choline chloride, and the hydrogen bond acceptors are ethylene glycol, urea, and glycerol.

[0015] As one possible implementation, in step S1, the molar ratio of hydrogen bond acceptor to hydrogen bond donor in the eutectic solvent is 1:2 to 1:5.

[0016] As one possible implementation, in step S1, the hydrogen bond acceptor of the eutectic solvent is choline chloride and the hydrogen bond donor is ethylene glycol. Preferably, the molar ratio of choline chloride to ethylene glycol is 1:2.

[0017] As one possible implementation, the solid raw material containing cadmium telluride is CdTe or CdTe intermediate product recovered from waste CdTe components.

[0018] As one possible implementation, the method for recovering the CdTe intermediate product from the waste CdTe component is as follows: the waste CdTe component is disassembled and leached to obtain a mud cake, and the mud cake is subjected to H2 thermal reduction to obtain the CdTe intermediate product, which is used as a solid raw material containing cadmium telluride.

[0019] As one possible implementation, in step S1, a three-electrode system is used for electrochemical testing. The working electrode is a glassy carbon electrode with a solid raw material layer containing cadmium telluride coated on its surface, the counter electrode is graphite, and the reference electrode is Ag / AgCl.

[0020] As one possible implementation, the working electrode is prepared by grinding a solid raw material containing cadmium telluride into CdTe powder, dispersing it in a dispersion to form a CdTe suspension, uniformly coating it on the surface of a glassy carbon electrode, and drying it to obtain a glassy carbon electrode with the solid raw material containing cadmium telluride coated on its surface.

[0021] As one possible implementation, in the preparation method of the working electrode, the mixing ratio of the solid raw material containing cadmium telluride to the dispersion is 1 mg: 100 μL.

[0022] As one possible implementation, in the method for preparing the working electrode, the dispersion is a mixture of ethanol and Nafion 117 solution, with a volume ratio of ethanol to Nafion 117 solution of 19:1.

[0023] As one possible implementation, in the preparation method of the working electrode, the concentration of Nafion 117 solution is 5 wt%.

[0024] As one possible approach, in the preparation method of the working electrode, the glassy carbon electrode is first polished for surface treatment before being coated with CdTe suspension.

[0025] As one possible implementation, in step S2, the inert electrode is a graphite rod.

[0026] As one possible implementation, in step S3, the cathode may include, but is not limited to, titanium sheets, copper sheets, nickel sheets, stainless steel, etc.

[0027] As one possible implementation, in step S3, constant voltage electrolysis is used, with an electrolysis voltage of 0.5~2.5V, preferably 0.5~1.5V.

[0028] As one possible implementation, in step S3, the electrochemical deposition temperature is 50~90℃ and the time is 12~48h.

[0029] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The method of the present invention realizes one-step separation and recovery of cadmium telluride in a eutectic solvent, without the need for strong acid and strong base reagents, and the wastewater and waste gas emissions are zero. (2) The method of the present invention separates and recovers through electrochemical electrolysis. While obtaining elemental cadmium at the cathode, metallic tellurium is enriched in the anode loading chamber. It has the advantages of low cost, simple process, environmental friendliness, economy and one-step separation, which is in line with the concept of green and sustainable development. Attached Figure Description

[0030] Figure 1 The images show the SEM and XRD patterns of the CdTe material in Example 1. Figure 2 This is a cyclic voltammetry curve of the electrochemical behavior test in Example 1; Figure 3 The images show the SEM and XRD patterns of metallic tellurium in the anode carrier cavity after electrochemical deposition in Example 1. Figure 4 The images show the SEM and XRD patterns of elemental cadmium in the cathode after electrochemical deposition in Example 1. Figure 5 This is a schematic diagram of the electrochemical deposition process in Example 1; Figure 6 The images show the UV spectra of the deposition solution before and after electrochemical deposition in Example 1. Figure 7 The images show ESI-MS results of the deposition solution before and after electrochemical deposition in Example 1. Figure 8 The images show the XRD patterns of the cathode (right) and anode loading chambers (left) after 24 hours of electrochemical deposition in Example 2. Figure 9Characterization diagrams of the products in the cathode (right) and anode loading chambers (left) after 48 hours of electrochemical deposition in Example 2; Figure 10 The images show the SEM and EDS images of the metallic tellurium in the anode carrier cavity after electrochemical deposition in Example 3. Figure 11 The images show the SEM and EDS images of elemental cadmium in the cathode after electrochemical deposition in Example 3. Figure 12 The images show the SEM and EDS images of metallic tellurium in the anode loading chamber after 24 hours of electrochemical deposition in Example 4. Figure 13 The images show the SEM and EDS images of metallic tellurium in the anode loading chamber after electrochemical deposition for 26 hours of continued electrolysis in Example 4. Figure 14 This is a flowchart of the process for handling discarded CdTe components in Example 5.

[0031] Figure 15 Characterization diagrams of the products at the anode (top) and cathode (bottom) after 18 hours of electrochemical deposition in the comparative example. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0033] Example 1 This embodiment of a method for preparing tellurium and cadmium by solid-state anodic electrolysis of cadmium telluride includes the following steps: S1. Determine the electrodeposition voltage S11. Preparation of eutectic solvent: At 80°C, choline chloride and ethylene glycol are stirred and mixed evenly in a molar ratio of 1:2 to obtain a colorless and transparent eutectic liquid.

[0034] S12. Preparation of the working electrode: S121. Grind the bulk CdTe material (purity 99.99%, purchased from Sichuan High Purity Materials Technology Co., Ltd.) in an agate mortar for 30 min to ensure that the powder particles are fully refined and obtain CdTe powder. Figure 1 The images are SEM and XRD patterns of CdTe material, respectively. S122. Weigh 10 mg of CdTe powder from step S121 into a glass vial, add 950 μL of ethanol and 50 μL of Nafion 117 solution (5wt%), and sonicate for 1 h to form a homogeneous CdTe suspension. S123. Using a pipette, take 5 μL of the CdTe suspension from step S122 and uniformly coat it onto the surface of a pre-polished glassy carbon electrode (GCE, Φ3 mm, polished with 0.05 μm α-Al2O3 slurry). After drying in a vacuum oven, a glassy carbon electrode with a CdTe layer on the surface is obtained, which is the working electrode.

[0035] S13, Cyclic Voltammetry Curve Test: Using the glassy carbon electrode with a CdTe layer prepared in step S12 as the working electrode, graphite as the counter electrode, and Ag / AgCl as the reference electrode, and the eutectic solvent prepared in step S11 as the electrolyte, cyclic voltammetry was performed. The test range was -1.6V to 1V to -1.6V, and the scan rate was 50mV / s.

[0036] like Figure 2 As shown, the cyclic voltammetry of CdTe coating exhibits an oxidation peak A1A2A3 and a reduction peak C1, where the oxidation peak A1 corresponds to Cd. 0 →Cd 2+ A2 corresponds to Te 2- →Te 0 A3 corresponds to Te 0 →Te 2+ The reduction peak C1 corresponds to Cd 2+ →Cd.

[0037] S14. Tank pressure measurement: Based on the cyclic voltammetry curve test results obtained in step S13, the eutectic solvent obtained in step S11 is subjected to constant potential electrolysis through a three-electrode system at a temperature of 80℃. The electrode obtained in step S12 is used as the working electrode, Ag / AgCl is used as the reference electrode, and the titanium sheet is used as the counter electrode. The constant potential electrolysis potential is set between the oxidation peaks A2 and A3 in the cyclic voltammetry curve test obtained in step S13. After the current stabilizes, the cell voltage between the working electrode and the counter electrode is measured to be 1.5V using a multimeter. The obtained cell voltage value is the voltage value required for constant voltage electrodeposition.

[0038] S2. Preparation of cadmium telluride electrode: Take a graphite rod with a diameter of 1 cm and a height of 4 cm. Drill a cylindrical material-carrying cavity with a diameter of 0.8 cm and a depth of 0.6 cm along the axis at a distance of 0.5 cm from the bottom. Take 30 mg of ground cadmium telluride powder (purity 99.99%, purchased from Sichuan High Purity Materials Technology Co., Ltd.) and fill it into the material-carrying cavity to obtain a cadmium telluride electrode.

[0039] S3, Electrochemical Deposition: S31. First, cool the eutectic solvent obtained in step S11 at room temperature (as the temperature decreases, the viscosity of the eutectic solvent increases). S32. Take a small amount of the eutectic solvent cooled in step S31 and drop it into the loading chamber of the cadmium telluride electrode prepared in step 2. This allows the cadmium telluride powder in the loading chamber to come into contact with the cooled eutectic solvent itself for pre-wetting, preventing the powder from dispersing in the deposition solution. Let it stand for 30 min to allow the eutectic solvent to fully wet the surface and pores of the cadmium telluride powder, using this as the anode. A titanium sheet is used as the cathode, and the cooled eutectic solvent from S31 is used as the deposition solution. The deposition voltage is 1.5V, the temperature is 80℃, and the time is 24 h. After deposition, the obtained cathode product and the product in the loading chamber are characterized by XRD and SEM, respectively. Figure 3 , 4 The phase characterization results show that CdTe can be completely decomposed in this system, metallic tellurium is deposited in the anode loading chamber, and elemental cadmium is deposited on the cathode surface.

[0040] From the eutectic solvent system of Example 1, the basic principle of the reaction can be seen as follows: Figure 5 As shown, in a eutectic solvent, the anodic electrolysis of CdTe solid is essentially a process of oxidation-dissolution-complexation synergy. Tellurium remains in the graphite loading cavity in elemental form, while cadmium enters the solution in ionic form.

[0041] Ultraviolet spectroscopy analysis was performed on the deposition solution before and after electrochemical deposition, such as... Figure 6 As shown, compared with the blank deposition solution (black curve), the electrolyzed deposition solution (red curve) exhibits a new absorption peak at 204 nm in its UV spectrum, indicating that Cd2O3 has a higher absorption rate during electrochemical deposition. 2+ It reacts with the eutectic solvent component to form a new metal complex.

[0042] To study Cd more clearly 2+ The form in which it exists in the electrolyte, and the ESI-MS analysis of the deposition solution before and after electrochemical deposition, as shown in the following figures. Figure 7 As shown: The results indicate that Cd 2+ In eutectic solvents, it is [CdCl3]. - It exists in form. Under the influence of an electric field, Cd 2+ The electrode is moved to the cathode for reduction deposition. After electrochemical deposition is complete, the electrode is removed to obtain metallic tellurium and elemental cadmium.

[0043] Therefore, the anode and cathode reactions of CdTe in ChCl-EG DES can be described as follows: Anodic reaction: CdTe(s) → Te(s) + Cd 2+ + 2e - ; Cathode reaction: [CdCl3] - + 2e - → Cd(s) + 3Cl - .

[0044] Example 2 The method in Example 2 is basically the same as that in Example 1, except that: ① The eutectic solvent is choline chloride and urea in a molar ratio of 1:2.5. At this time, the tank pressure value measured in step S14 is 2.2V. ② In step S3, the cathode is a copper sheet and the deposition voltage is 2.2V.

[0045] Electrodeposition was performed for 24 hours, and the resulting anode and cathode products were characterized by XRD. Figure 8 As shown in the figure. The results indicate that the electrolytic products obtained by constant voltage electrolysis are elemental cadmium on the cathode copper sheet, while the products in the anode loading chamber are mostly CdTe raw materials and a small amount of metallic Te, indicating that the deposition time is insufficient.

[0046] Therefore, electrodeposition was continued for another 24 hours, and the anodic and cathodic products were characterized, such as... Figure 9 As shown, the anode's loading chamber mainly contains metallic Te (atomic ratio 91.4%) and a small amount of incompletely decomposed CdTe, while the cathode copper sheet still contains elemental Cd.

[0047] Example 3 The method in Example 3 is basically the same as that in Example 1, except that: ① The eutectic solvent is choline chloride and glycerol in a molar ratio of 1:3. At this time, the tank pressure value measured in step S14 is 1.8V. ② In step S3, the deposition voltage is 1.8V and the time is 30 h.

[0048] The cathode and anolyte products obtained by constant voltage electrolysis were characterized by SEM and EDS, such as... Figure 10 , 11 As shown in the figure. The results indicate that CdTe can be completely decomposed into metallic tellurium and elemental cadmium under these process conditions.

[0049] Example 4 The method in Example 4 is basically the same as that in Example 1, except that the eutectic solvent is prepared by choline chloride and ethylene glycol in a molar ratio of 1:5, and the other conditions remain unchanged.

[0050] like Figure 12 As shown, after 24 hours of electrochemical deposition, the Te to Cd ratio in the anode's loading chamber was 8:2. After another 2 hours of electrolysis, as... Figure 13 As shown, CdTe decomposes completely.

[0051] Example 5 The method in Example 5 is basically the same as that in Example 1, except that the bulk CdTe material (99.99% purity, purchased from Sichuan High Purity Materials Technology Co., Ltd.) in step 1 is replaced with CdTe intermediate products recycled from waste CdTe modules. The recycling method is described in "Economic recycling of CdTe photovoltaic modules": "Bohland J, Anisimov I, Dapkus T. Economic recycling of CdTe photovoltaic modules[C] / / Conference Record of the Twenty Sixth IEEE Photovoltaic Specialists Conference-1997. IEEE, 1997: 355-358." The recycling process is as follows: Figure 14 As shown in the CdTe component, the waste CdTe component undergoes pretreatment steps such as dismantling, stripping of encapsulation material, crushing, and physical sorting, followed by leaching to obtain a sludge cake. Finally, the sludge cake is subjected to H2 thermal reduction to obtain a material enriched with cadmium telluride. The relevant reaction formulas for the leaching reaction are: (1) CdTe(s)+3H2SO4+3H2O2= CdSO4(aq)+Te(SO4)2(aq)+6H2O (2) CdS(s)+H2SO4+H2O2= CdSO4(aq)+S(s)+2H2O The relevant reaction formulas for neutralization and precipitation are: (3) CdSO4(aq)+Na2CO3(s) = CdCO3(s)+Na2SO4(aq) (4)Te(SO4)2(aq)+2Na2CO3(s) = TeO2(s)+2Na2SO4(aq)+CO2(g) The relevant reaction equation for the thermal reduction of H2 is: (5)TeO2+3H2+CdCO3= Te+Cd+3H2O+CO2 (6)Te+Cd = CdTe (N2500℃) In this embodiment, the electrolysis voltage is determined to be 1.7V, the electrolysis time is 18h, and the electrolysis temperature is 90℃.

[0052] like Figure 15As shown, after 18 hours of electrochemical deposition, elemental Te was found in the anode loading chamber, and the purity of Te was determined to be 99.3% by chemical analysis. The cathode product contained not only metallic cadmium but also a small amount of tellurium (5%). This was because the high electrolysis potential caused further oxidation of the elemental Te in the anode chamber, and the resulting positively charged ions co-deposited with cadmium ions at the cathode, making the cathode product impure.

[0053] Comparative Example The method for the comparative example is basically the same as that for Example 1, except that in step S32, a pre-wetted cadmium telluride electrode is used as the cathode, and graphite is used as the anode. The comparative example cathode electrolysis of cadmium telluride failed to react normally.

[0054] This is because the chemical bonds in solid CdTe are very strong, making it difficult to directly bond Cd within its crystal lattice. 2+ Restored to Cd 0 Overcoming a significant energy barrier is necessary. This requires applying extremely high voltages (far exceeding its thermodynamic decomposition voltage of approximately 0.5V at room temperature; increasing temperature can lower the theoretical decomposition voltage). Therefore, in the comparative example of cathode electrolysis of cadmium telluride, most of the electrical energy is consumed in overcoming the lattice energy rather than for efficient material conversion, resulting in extremely low energy efficiency and uneconomical operation. Furthermore, the reaction only occurs in limited regions where ions can easily migrate (such as surfaces, grain boundaries, and dislocations), making uniform and complete electrolysis of the material impossible. Even assuming a localized reduction reaction (such as CdTe + 2e⁻) occurs... - → Cd +Te 2- The formation of Cd as a product and the retention of new solid-phase products inside the cathode hinder the decomposition of CdTe. In other words, once metallic Cd is locally formed at the cathode, the Cd layer adheres tightly to the CdTe surface. This metallic Cd layer impedes the continued conduction of electrons to the internal CdTe and also prevents the electrolyte from contacting the unreacted CdTe, causing the reaction to stop rapidly.

[0055] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for the production of tellurium and cadmium from a solid anode cadmium telluride electrolysis, characterized by: The method comprises the following steps: S1, determining an electrochemical deposition voltage: using a eutectic solvent as an electrolyte, and determining a deposition voltage of a solid-state raw material containing cadmium telluride through electrochemical testing; S2, preparing a cadmium telluride electrode: opening a material loading cavity in an inert electrode, and loading the solid-state raw material containing cadmium telluride into the material loading cavity as an anode; S3, electrochemical deposition: using the eutectic solvent in step S1 as a deposition solution, using the cadmium telluride electrode in step S2 as an anode, and matching a cathode, to ensure that the raw material in the material loading cavity is immersed in the deposition solution, and then applying the electrolysis voltage determined in step S1 to perform electrochemical deposition; After the deposition is completed, the material loading cavity of the anode is filled with deposited tellurium, and the surface of the cathode is filled with deposited elemental cadmium.

2. A process for the production of tellurium and cadmium from a solid anode cadmium telluride electrolyte as claimed in claim 1, wherein: In step S1, the eutectic solvent contains chloride ions, and the molar concentration of the chloride ions is 2 mol / L to 5 mol / L.

3. A process for the production of tellurium and cadmium from a solid anode cadmium telluride electrolyte as claimed in claim 2, wherein: In step S1, the eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is choline chloride, and the hydrogen bond donor is ethylene glycol, urea, and glycerol.

4. A process for the production of tellurium and cadmium from a solid anode cadmium telluride electrolyte as claimed in claim 3, wherein: In step S1, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor of the eutectic solvent is 1:2 to 1:

5.

5. A process for the production of tellurium and cadmium from a solid anode cadmium telluride electrolyte as claimed in claim 4, wherein: In step S1, the hydrogen bond acceptor of the eutectic solvent is choline chloride, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor, preferably choline chloride and ethylene glycol, is 1:

2.

6. The method of claim 1, wherein the solid anode electrolyte cadmium telluride produces tellurium and cadmium. The solid-state raw material containing cadmium telluride is CdTe or a CdTe intermediate product recovered from a waste CdTe component.

7. A process for the production of tellurium and cadmium from a solid anode cadmium telluride electrolyte as claimed in claim 1, wherein: In step S1, the electrochemical testing is performed using a three-electrode system, the working electrode is a glassy carbon electrode coated with the solid-state raw material containing cadmium telluride, the counter electrode is graphite, and the reference electrode is Ag / AgCl.

8. The method according to any one of claims 1 to 7, wherein the method is a method for producing tellurium and cadmium from a solid anode cadmium telluride, characterized by: In step S2, the inert electrode is a graphite rod; and in step S3, the cathode includes but is not limited to a titanium sheet, a copper sheet, a nickel sheet, and stainless steel.

9. A process for the production of tellurium and cadmium from a solid anode cadmium telluride electrolyte as claimed in claim 8, wherein: In step S3, constant voltage electrolysis is used, and the electrolysis voltage is 0.5 V to 2.5 V, preferably 0.5 V to 1.5 V.

10. A process for the production of tellurium and cadmium from a solid anode cadmium telluride electrolyte as claimed in claim 8, wherein: In step S3, the temperature of the electrochemical deposition is 50°C to 90°C, and the time is 12 h to 48 h.

Images