A method for separating and purifying germanium from a complex silicon-based germanium-containing material
Patent Information
- Application Number
- CN202611006705.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-07
- Publication Date
- 2026-08-28
AI Technical Summary
[0005]本发明的目的在于提供一种从复杂硅基含锗物料中分离提纯锗的方法，用于解决现有技术中浸出率低、硅干扰大、萃取选择性差及环境污染重等的问题
[0023] 1. This invention introduces low-temperature plasma activation technology to expose internal germanium atoms without significantly damaging the integrity of the silicon framework. Experimental data shows that this method increases the leaching rate of germanium from the traditional 45% to over 96.8%, while strictly controlling the silicon dissolution rate to around 15%, reducing the difficulty of subsequent silicon separation and reducing acid and energy consumption.
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Figure CN122648741A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of non-ferrous metal metallurgy and resource recycling technology, and in particular relates to a method for separating and purifying germanium from complex silicon-based germanium-containing materials. Background Technology
[0002] With the rapid development of the semiconductor and photovoltaic industries, the production of germanium-containing silicon-based waste has increased dramatically. Germanium, as an important strategic rare metal, is widely used in infrared optics, fiber optic communication, solar cells, and the nuclear industry. However, current methods for recycling and processing these complex silicon-based germanium-containing materials still have the following shortcomings:
[0003] Traditional processes often employ high-temperature strong acid or chlorination volatilization methods. Due to the dense lattice of silicon-based materials, conventional acids have difficulty penetrating, resulting in germanium leaching rates typically below 60%. To forcibly increase the leaching rate, acid consumption and temperature often need to be significantly increased, which not only wastes energy but also causes a large amount of silicon to dissolve into the solution, leading to extremely high subsequent silicon removal costs. Existing solvent extraction processes mainly rely on organophosphorus extractants such as tributyl phosphate or P507. These traditional extractants have poor selectivity for germanium and are prone to co-extracting impurities such as iron, aluminum, and arsenic during the extraction process. They also have weak silicon inhibition capabilities. Especially when the silicon content in the solution is high, emulsification is very likely to occur, leading to difficulties in phase separation, severe organic phase entrainment, and ultimately affecting product purity.
[0004] To address this issue, we provide a method for separating and purifying germanium from complex silicon-based germanium-containing materials. Summary of the Invention
[0005] The purpose of this invention is to provide a method for separating and purifying germanium from complex silicon-based germanium-containing materials, in order to solve the problems of low leaching rate, large silicon interference, poor extraction selectivity and heavy environmental pollution in the prior art.
[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:
[0007] This invention discloses a method for separating and purifying germanium from complex silicon-based germanium-containing materials, comprising the following steps:
[0008] S1) After mechanically ball milling the complex silicon-based germanium-containing material, it is placed in a low-temperature plasma reactor, and a trace amount of oxygen is introduced under an inert gas atmosphere to control the reaction temperature at 300-500℃.
[0009] S2) The activated material is put into a mixed acidic solution containing ammonium bifluoride and hydrogen peroxide, and the pH value is controlled at 1.5-2.5 and the temperature is 40-60℃.
[0010] S3) An organic phase composed of functionalized imidazole ionic liquid and n-dodecane is used as the extractant. The volume ratio of aqueous phase to organic phase is adjusted to 1:1.5. A tertiary amine is added as a co-extractant. Extraction is carried out in a multi-stage countercurrent extraction tank.
[0011] S4) The supported organic phase was back-extracted using a dilute hydrochloric acid solution with a stepwise concentration gradient to obtain a germanium-rich solution, and sodium sulfide solution was added dropwise to it.
[0012] S5) Add modified polyethylene glycol to the purified germanium-rich solution, adjust the pH value of the solution and slowly cool it to below 5°C, filter and dry to obtain a solid product.
[0013] The present invention is further configured such that the power density of the low-temperature plasma in step S1) is 10-30 W / cm², the processing time is 10-30 minutes, and the partial pressure of oxygen is controlled at 0.5-2.0 kPa.
[0014] The present invention is further configured such that the molar ratio of ammonium bifluoride to hydrogen peroxide in the mixed acidic solution in step S2) is 1:(0.5-1.2), and ultrasonic assistance is introduced with a frequency of 20-40kHz.
[0015] The present invention is further configured such that the functionalized imidazole ionic liquid in step S3) is 1-butyl-3-methylimidazolium hexafluorophosphate or a derivative thereof.
[0016] The present invention is further configured such that the tertiary amine in step S3) is trioctylamine or triethylamine, and its concentration in the organic phase is 0.5-2.0 mol / L.
[0017] The present invention is further configured such that the stepwise concentration gradient elution in step S4) specifically uses 0.5 mol / L HCl in the first stage, 1.5 mol / L HCl in the second stage, and 3.0 mol / L HCl in the third stage.
[0018] The present invention is further configured such that, when adding sodium sulfide solution in step S4), the molar ratio of sulfur ions to heavy metal ions is controlled to be 1.1:1, the reaction temperature is 15-25℃, and the mixture is allowed to stand for 2 hours.
[0019] The present invention is further configured such that the modified polyethylene glycol in step S5) is a network polymer obtained by crosslinking modification with epichlorohydrin, with a molecular weight of 2000-5000 Da, and the amount added is 0.01%-0.05% of the germanium-containing solution.
[0020] The present invention is further configured such that, in step S5), the process of adjusting the pH value of the solution is continuously purged with a nitrogen protective atmosphere.
[0021] The present invention is further configured such that, after the filtrate generated in step S4) is neutralized by lime milk and subjected to flocculation and precipitation treatment, calcium fluoride byproduct is recovered, and the filtrate is recycled back to step S2 after being treated by a reverse osmosis membrane system.
[0022] The present invention has the following beneficial effects:
[0023] 1. This invention introduces low-temperature plasma activation technology to expose internal germanium atoms without significantly damaging the integrity of the silicon framework. Experimental data shows that this method increases the leaching rate of germanium from the traditional 45% to over 96.8%, while strictly controlling the silicon dissolution rate to around 15%, reducing the difficulty of subsequent silicon separation and reducing acid and energy consumption.
[0024] 2. This invention employs a synergistic extraction system combining functionalized imidazole ionic liquids with tertiary amines. The functionalized imidazole ionic liquids form stable complexes with germanium ions, while the tertiary amines further enhance the extraction capability through anion exchange mechanisms. This effectively repels impurity ions such as silicon, iron, and aluminum, and the interfacial tension is moderate, resulting in a total germanium extraction rate of over 99.5%.
[0025] 3. This invention employs a step-concentration gradient back-extraction strategy, which not only improves back-extraction and achieves graded removal of impurities, but also introduces sodium sulfide for deep purification. Under controlled molar ratio conditions, the removal rates of harmful heavy metals such as copper, lead, and arsenic all exceed 99.9%, while the germanium loss rate is extremely low. Attached Figure Description
[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.
[0027] Figure 1 This is a schematic diagram of the method flow of the present invention.
[0028] Figure 2 This is a schematic diagram of the equipment process of the present invention. Detailed Implementation
[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0030] Example
[0031] Please see Figure 1 and Figure 2 This invention provides a method for separating and purifying germanium from complex silicon-based germanium-containing materials, comprising the following steps:
[0032] Step S1: Low-temperature plasma activation
[0033] Complex silicon-based germanium-containing materials crushed to a particle size of <100μm are ground in a high-energy ball mill for 3 hours. The materials are then fed evenly into a low-temperature plasma reactor, such as the LP-2000 model, via a screw feeder. Argon gas is introduced into the low-temperature plasma reactor as a carrier gas, and the oxygen partial pressure is precisely controlled at 0.8kPa using a mass flow controller. The plasma generator is turned on, with the power density set at 20W / cm², the processing time at 20 minutes, and the reaction temperature controlled at 400℃.
[0034] The activation effects of different processing methods, specifically the control group, this embodiment, and the comparative example, are compared as follows (refer to Table 1):
[0035] experimental group Oxygen partial pressure (kPa) Power density (W / cm²) Processing time (min) Germanium leaching rate (%) Silicon solubility (%) process control group 0 0 120 45.2 12.5 Traditional acid leaching Example 0.8 20 20 96.8 15.3 This process Comparative Example 5 20 20 88.4 45.6 Excess oxygen causes silicon to dissolve.
[0036] Table 1
[0037] As shown in Table 1, after low-temperature plasma activation treatment, the germanium leaching rate increased significantly from 45.2% in the control group to 96.8%, an increase of more than 50 percentage points, and the processing time was shortened to 1 / 6 of the original, improving production efficiency. Meanwhile, the silicon dissolution rate in this example was only 15.3%, far lower than the 45.6% in Comparative Example 1. This indicates that the combination of trace oxygen at 0.8 kPa and a specific power density of 20 W / cm² is effective: an appropriate amount of active oxygen species can effectively disrupt the silicon lattice to release germanium, while excessive oxygen will lead to over-oxidation and dissolution of the silicon matrix, increasing the burden on subsequent separation.
[0038] Step S2: Ultrasonic-assisted acid leaching
[0039] The activated material is fed into a leaching tank with a heating jacket via a pneumatic pump. A mixed acidic solution is prepared, with the molar ratio of ammonium bifluoride to hydrogen peroxide controlled at 1:0.8. The solution pH is adjusted to 2.0 using an automatic acid addition system, and the temperature is maintained at 50°C. An ultrasonic transducer array installed at the bottom of the leaching tank is activated at a frequency of 30 kHz to assist the leaching process for 30 minutes.
[0040] The leaching effects at different temperatures are shown in Table 2:
[0041] Run batch Temperature (°C) pH value Ultrasonic frequency (kHz) Germanium leaching rate (%) Silicon solubility (%) Clarity of leachate Batch 01 50 2.0 30 96.8 15.3 Ultra HD Batch 02 40 2.0 30 92.1 14.8 Slightly turbid Batch 03 60 2.0 30 97.2 16.5 Ultra HD
[0042] Table 2
[0043] Table 2 shows that the leaching rate of germanium remains above 92% within the temperature range of 40℃ to 60℃, indicating that the process has a certain degree of tolerance to temperature.
[0044] However, 50°C is the optimal point for overall benefits: its leaching rate is slightly lower than that of 60°C, but its silicon dissolution rate is lower than that of 60°C, and the clarity of the leachate is better than that of 40°C.
[0045] This demonstrates that ultrasonic cavitation most effectively enhances mass transfer at 50°C, promoting reaction kinetics while preventing excessive silicon dissolution due to high temperatures. Furthermore, the clarity index indicates that ultrasound effectively prevents colloid formation, which is beneficial for subsequent solid-liquid separation.
[0046] Step S3: Multistage countercurrent extraction
[0047] 1-Butyl-3-methylimidazolium hexafluorophosphate was dissolved in n-dodecane, and trioctylamine was added as a co-extractant at a concentration of 1.0 mol / L. The leachate and extractant were mixed at a volume ratio of aqueous phase to organic phase of 1:1.5 and then introduced into a three-stage countercurrent extraction tank. Each stage was equipped with an independent stirrer and a clarification chamber to ensure sufficient contact and stratification.
[0048] The extraction effects at different stages are shown in Table 3:
[0049] series Aqueous phase pH Ge concentration in the organic phase (g / L) Ge concentration in the raffinate (mg / L) Single-stage extraction rate (%) Cumulative extraction rate (%) Level 1 2.0 12.5 45.0 78.5 78.5 Level 2 2.0 28.4 8.2 95.6 96.8 Level 3 2.0 32.1 1.5 98.9 99.5
[0050] Table 3
[0051] Table 3 illustrates the typical characteristics of countercurrent extraction: the first-stage extraction rate reached 78.5%, indicating that the functionalized ionic liquid has a very strong affinity for germanium; with increasing stages, after the third stage extraction, the germanium content in the raffinate decreased to 1.5 mg / L, and the cumulative extraction rate reached 99.5%. This data shows that the three-stage countercurrent extraction is reasonable and sufficient to almost completely transfer germanium from the aqueous phase to the organic phase. Simultaneously, the germanium concentration in the organic phase increased from 12.5 g / L to 32.1 g / L, a concentration factor of approximately 2.5 times, improving the efficiency of subsequent back-extraction.
[0052] Step S4: Stepwise back-extraction and purification
[0053] Back-extraction: The loaded organic phase is sequentially pumped into a three-stage back-extraction tank; the first stage uses 0.5 mol / L HCl, the second stage uses 1.5 mol / L HCl, and the third stage uses 3.0 mol / L HCl for countercurrent back-extraction; the third-stage back-extraction solution is collected as a germanium-rich solution.
[0054] Purification: Pump the rich solution into the purification reactor, and add sodium sulfide solution dropwise here using a metering pump. Control the molar ratio of sulfur ions to heavy metal ions such as Cu, Pb, and As to be 1.1:1. The reaction temperature is 20℃, and the mixture is magnetically stirred and allowed to stand for 2 hours for aging.
[0055] Solid-liquid separation: After the reaction is completed, the slurry enters the plate and frame filter press, the heavy metal sulfide filter cake is sent to hazardous waste treatment, and the filtrate enters the next process.
[0056] The purification effect is shown in Table 4:
[0057] heavy metal ions Concentration before purification (mg / L) Concentration after purification (mg / L) Removal rate (%) Remark Cu 120.5 <0.1 99.92 CuS precipitate is formed Pb 85.3 <0.05 99.94 PbS precipitate is formed As 45.2 <0.02 99.96 As2S3 precipitate is formed Ge 32.1 31.8 99.06 Minimal loss
[0058] Table 4
[0059] Table 4 data demonstrates the deep purification capability of this process: the removal rates of key harmful impurities such as copper, lead, and arsenic all exceed 99.9%, meeting the precursor requirements for electronic-grade materials. Notably, under highly efficient impurity removal conditions, the germanium loss rate is only 0.94%, indicating precise control of sodium sulfide addition and the absence of germanium co-precipitation. Stepwise back-extraction transfers germanium from the organic phase to the aqueous phase at a high concentration (32.1 g / L), laying the foundation for subsequent high-purity precipitation.
[0060] Step S5: Precipitation and crystallization of modified polyethylene glycol
[0061] A network-modified polyethylene glycol (PEG) with a molecular weight of 3000 Da, cross-linked with epichlorohydrin, was added to the germanium-rich solution in the purification tank at a concentration of 0.03% of the total solution volume. Under nitrogen protection, the pH was slowly adjusted to slightly alkaline neutral using an automatic alkali addition system. A low-temperature cooling circulation system was then activated to cool the solution to below 5°C at a rate of 1°C / min, allowing it to stand for crystallization for 12 hours. Finally, the solution was filtered and washed using a vacuum filter, and then dried in a vacuum drying oven to obtain a white solid germanium compound.
[0062] The finished product specifications are shown in Table 5:
[0063] Testing items Test results Standard Specifications (Electronic Grade) Detection methods Ge purity (%) 99.995 ≥99.99 ICP-MS Si content (ppm) 15 ≤50 XRF Fe content (ppm) 2 ≤10 AAS Moisture(%)0.02 0.02 ≤0.05 Karl Fischer Crystal morphology Regular flakes - SEM observation
[0064] Table 5
[0065] Table 5 shows that all indicators of the final product exceed the standard requirements for electronic-grade germanium. In particular, the Si content is only 15 ppm, thanks to the effective suppression and separation of silicon in the preceding steps. The crystal morphology exhibits a regular lamellar structure, attributed to the directional growth-inducing effect of modified polyethylene glycol and the low-temperature, slow crystallization process. The nitrogen protective atmosphere effectively prevents the oxidation of the germanium compounds. Overall, this step successfully converts high-purity germanium-rich solution into a high-value-added electronic-grade solid product with extremely low moisture content, which is beneficial for subsequent processing.
[0066] The filtrate produced in step S4 is neutralized in a neutralization reaction tank by adding lime slurry to generate calcium fluoride precipitate. The by-product is recovered by pressure filtration, and the supernatant is treated in a reverse osmosis membrane system. The permeate is recycled back to step S2 to prepare leachate, thus achieving zero discharge of water resources and recycling of reagents.
[0067] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
Claims
1. A method for separating and purifying germanium from complex silicon-based germanium-containing materials, characterized in that, Includes the following steps: S1) After mechanically ball milling the complex silicon-based germanium-containing material, it is placed in a low-temperature plasma reactor, and a trace amount of oxygen is introduced under an inert gas atmosphere to control the reaction temperature at 300-500℃. S2) The activated material is put into a mixed acidic solution containing ammonium bifluoride and hydrogen peroxide, and the pH value is controlled at 1.5-2.5 and the temperature is 40-60℃. S3) An organic phase composed of functionalized imidazole ionic liquid and n-dodecane is used as the extractant. The volume ratio of aqueous phase to organic phase is adjusted to 1:1.
5. A tertiary amine is added as a co-extractant. Extraction is carried out in a multi-stage countercurrent extraction tank. S4) The supported organic phase was back-extracted using a dilute hydrochloric acid solution with a stepwise concentration gradient to obtain a germanium-rich solution, and sodium sulfide solution was added dropwise to it. S5) Add modified polyethylene glycol to the purified germanium-rich solution, adjust the pH value of the solution and slowly cool it to below 5°C, filter and dry to obtain a solid product.
2. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, The power density of the low-temperature plasma in step S1) is 10-30 W / cm², the processing time is 10-30 minutes, and the partial pressure of oxygen is controlled at 0.5-2.0 kPa.
3. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, In step S2), the molar ratio of ammonium bifluoride to hydrogen peroxide in the mixed acidic solution is 1:(0.5-1.2), and ultrasonic assistance is introduced at a frequency of 20-40kHz.
4. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, The functionalized imidazole ionic liquid mentioned in step S3) is 1-butyl-3-methylimidazolium hexafluorophosphate or its derivative.
5. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, The tertiary amine mentioned in step S3) is trioctylamine or triethylamine, and its concentration in the organic phase is 0.5-2.0 mol / L.
6. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, The stepwise concentration gradient elution described in step S4) is as follows: the first stage uses 0.5 mol / L HCl, the second stage uses 1.5 mol / L HCl, and the third stage uses 3.0 mol / L HCl.
7. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, When adding sodium sulfide solution in step S4), the molar ratio of sulfur ions to heavy metal ions is controlled at 1.1:1, the reaction temperature is 15-25℃, and the mixture is allowed to stand for 2 hours.
8. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, The modified polyethylene glycol mentioned in step S5) is a network polymer obtained by crosslinking modification with epichlorohydrin, with a molecular weight of 2000-5000 Da and an addition amount of 0.01%-0.05% of the germanium-containing solution.
9. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, In step S5), the process of adjusting the pH value of the solution is carried out by continuously introducing nitrogen gas to maintain a protective atmosphere.
10. The method for separating and purifying germanium from complex silicon-based germanium-containing materials according to claim 1, characterized in that, The filtrate generated in step S4) is neutralized with lime milk and subjected to flocculation and sedimentation treatment to recover calcium fluoride byproducts. The filtrate is then recycled back to step S2 after being treated by a reverse osmosis membrane system.