A treatment method for leaching germanium from germanium-doped waste optical fiber

Abstract

The present application relates to the field of resource recycling, in particular to a method for leaching germanium from waste optical fiber in a eutectic system. The eutectic system comprises a hydrogen bond acceptor and a hydrogen bond donor. After crushing, calcining and ball milling of the germanium-doped optical fiber, the eutectic system is used for leaching. The present application uses an environmentally friendly eutectic solvent as a reaction medium, replacing traditional strong acid / alkali and other corrosive leaching agents, to extract germanium from germanium-doped optical fiber. The process and operation are simple, efficient, and the leaching solution can be recycled, providing a new way for green and efficient recovery of germanium from germanium-doped optical fiber.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and in particular to a method for leaching germanium from germanium-doped waste optical fibers. Background Technology

[0002] Germanium, a typical rare and dispersed metal, has an abundance of only 7 × 10⁻⁶ in the Earth's crust. -6 Germanium resources are extremely dispersed, with almost no independently exploitable deposits. Only a few minerals in nature contain more than 1% germanium, highlighting its scarcity. Due to its excellent semiconductor properties, germanium occupies an irreplaceable and crucial position in many cutting-edge high-tech fields such as optical fiber communication, superconducting materials, high-efficiency solar cells, and infrared detection. Because of its significant strategic value, it has been explicitly listed as a strategic reserve resource by many countries. With the rapid development of global high-tech industries, market demand for germanium resources continues to rise. However, primary germanium reserves are limited and mining is difficult. Against this backdrop, the efficient recovery and recycling of germanium from secondary resources such as waste optical fibers and discarded semiconductor devices has become a key research direction and urgent need in the field of rare and dispersed metal resource utilization.

[0003] Optical fiber is the primary application area for germanium resources. The rapid development of my country's communications industry has greatly propelled the vigorous progress and large-scale development of the optical fiber industry. Given the limited reserves and high mining costs of virgin germanium resources, coupled with the increasingly urgent market demand for germanium, research on the efficient recycling and high-value utilization of germanium resources from waste optical fibers is crucial. It can not only alleviate the pressure of germanium resource shortages but also reduce resource waste, possessing significant practical importance and industrial application value.

[0004] Germanium was once a core material for the early development of the semiconductor device industry. With its unique advantages such as high carrier mobility, low bandgap, strong quantum confinement effect, and high light absorption coefficient, it has once again become a mainstream core electronic material. Existing methods for recycling germanium-containing waste materials mainly include pyrometallurgy, strong acid or strong alkali leaching, and chlorination volatilization, but these methods still have many shortcomings. The processes are demanding and energy-intensive: pyrometallurgy typically requires high-temperature processing, resulting in high energy consumption, equipment wear, and high production costs; acid or alkali leaching methods are highly corrosive to equipment, pose certain operational risks, and involve complex wastewater treatment; germanium is often encapsulated in silicon dioxide, forming tetragonal germanium oxide, which is difficult to leach efficiently using traditional methods; high-temperature pyrometallurgy and highly corrosive reagents easily generate waste gas, slag, and wastewater containing metal ions, posing potential environmental pollution.

[0005] Therefore, there is an urgent need to develop a germanium recovery process that is mild, environmentally friendly, safe to operate, and highly efficient to reduce energy consumption and environmental risks while improving recovery rates. This invention uses a eutectic solvent system to replace traditional highly corrosive leaching agents, enabling efficient leaching of germanium from waste optical fibers under mild conditions, while also considering environmental friendliness and industrial applicability. Eutectic solvents, as a novel type of green and environmentally friendly solvent, have significant advantages such as excellent solubility, environmental friendliness, non-volatility, low cost, and high designability. Applying them to the germanium leaching process can effectively improve germanium leaching efficiency, reduce equipment corrosion risks, and minimize environmental pollution. Summary of the Invention

[0006] To address the above technical problems, this invention provides a method for leaching germanium from germanium-doped waste optical fibers. This method is green, efficient, and simple. The germanium content in germanium-doped waste optical fibers is typically 0.05-10% by mass, and the silicon content is 90-99.9% by mass. During the production of optical rods, the germanium compound reacts with the silicon compound, and the germanium is encapsulated by a large amount of silica. Since germanium and silicon are in the same group, their separation has always been a challenge in the industry. Tetragonal germanium oxide is chemically stable, and common industrial acids are almost ineffective in extracting germanium from this waste. Therefore, the key to recovering this high-silicon, germanium-containing material is to break the silica encapsulation and dissolve the tetragonal germanium oxide. This invention uses ball milling and calcination to break the silica encapsulation and remove other impurities, followed by leaching with a eutectic solvent to transform it into soluble germanate.

[0007] The purpose of this invention is to provide a method for leaching germanium from germanium-doped waste optical fibers, comprising the following steps: A germanium-doped waste optical fiber is provided; The germanium-doped waste optical fiber was calcined and then ball-milled to obtain waste optical fiber powder. The obtained waste optical fiber powder is mixed with a eutectic solution and heated to react. The resulting reaction solution is then subjected to solid-liquid separation to obtain a germanium-containing filtrate.

[0008] In some embodiments of the present invention, the length of the germanium-doped waste optical fiber is 1-2 cm. This condition facilitates subsequent calcination and ball milling.

[0009] In some embodiments of the present invention, the calcination temperature is 600~800℃ and the time is 2~6h.

[0010] In some embodiments of the present invention, a zirconia ball milling jar is used for ball milling, and a planetary ball mill is used for ball milling, with a rotation speed of 300~500 r / min and a time of 10 min~3 h.

[0011] In some embodiments of the present invention, the eutectic solvent comprises urea compounds and organic acids; the urea compounds are selected from one or more of urea, methylurea, and ethylurea. The present invention utilizes the ability of urea compounds to form a stable hydrogen bond network structure with organic acids, thereby lowering the melting point of the system and forming a eutectic solvent, while simultaneously improving the system's ability to dissolve germanium oxides in germanium-doped optical fibers, thus promoting the leaching of germanium.

[0012] In some embodiments of the present invention, the organic acid is selected from one or more of lactic acid, malic acid, and citric acid.

[0013] In some embodiments of the present invention, the molar ratio of urea, methylurea, ethylurea and organic acid is (1:1) to (1:3).

[0014] Furthermore, the preparation conditions for the eutectic solvent are as follows: urea and organic acid are mixed at a temperature of 40-80°C until a uniform, transparent liquid is formed.

[0015] In some embodiments of the present invention, the solid-liquid ratio of waste optical fiber powder to eutectic solution is (1:50) to (1:100) g / ml.

[0016] In some embodiments of the present invention, the heating reaction conditions are: oil bath temperature 50~90°C, time 2~6h.

[0017] In some embodiments of the present invention, the germanium-doped waste optical fiber contains 0.05-10% germanium and 90-99.9% silicon by mass. During the production of the optical rod, the germanium compound reacts with the silicon compound, and the germanium is encapsulated by a large amount of silica. Since germanium and silicon are elements in the same group, their separation has always been a challenge in the industry. Tetragonal germanium oxide is chemically stable, and common industrial acids are almost incapable of extracting germanium from this waste. Therefore, the key to recovering this high-silicon germanium-containing material is to break the silica encapsulation and dissolve the tetragonal germanium dioxide. The present invention uses ball milling and calcination to break the silica encapsulation and remove other impurities, followed by leaching with a eutectic solvent to transform it into a soluble germanate.

[0018] The technical solution of the present invention has the following advantages compared with the prior art: The method of this invention utilizes eutectic leaching of germanium, avoiding the high production costs, complex equipment, and environmental pollution associated with traditional acid leaching followed by germanium precipitation, and also avoids the introduction of metal impurity ions. This invention offers advantages such as being environmentally friendly, having a simple process, low reagent consumption, and strong practicality. Attached Figure Description

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is a technical circuit diagram of the present invention for leaching germanium from waste optical fibers using a low-eutectic process.

[0020] Figure 2 This is an XRD analysis diagram of germanium-doped waste optical fiber from Embodiment 1 of the present invention.

[0021] Figure 3 This is a SEM image of the waste optical fiber in Embodiment 1 of the present invention.

[0022] Figure 4 The Fourier transform infrared (FTIR) spectra of the original waste optical fiber and the calcined sample of Example 1 of the present invention are shown. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0024] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0026] Figure 1 This is a process flow diagram of the present invention. In this invention, the concentration of germanium in the filtrate is determined by ICP-OES, and the germanium leaching rate is calculated according to formula (1): η=(C×V) / (m×w)×100% (1) In the formula: η -- Germanium leaching rate (%); C -- Germanium concentration in the filtrate (mg / L); V -- Filtrate volume (L); m -- Mass of waste optical fiber powder (g); w -- Germanium content (mg / g) in waste optical fiber.

[0027] Example 1

[0028] This embodiment provides a method for leaching germanium from germanium-doped waste optical fiber, as detailed below: I. Using germanium-doped waste optical fibers recycled from a certain factory as raw materials, the main chemical components are shown in Table 1. These components were analyzed by XRD (…). Figure 2 ) and SEM ( Figure 3 Analysis revealed that the main component of the waste optical fiber was amorphous. Figure 2 It can be seen that the main component of waste optical fiber is silicon dioxide, and a significant broad dispersion peak appears at about 22°, indicating that the silicon dioxide in the optical fiber mainly exists in an amorphous structure. Figure 3 It can be seen that the optical fiber powder is formed by irregular micron-sized particle agglomeration. The particle surface is relatively rough and has a cauliflower-like morphology. No obvious regular crystal structure was observed, indicating that the sample has typical microscopic characteristics of amorphous silicon dioxide.

[0029] Table 1: Chemical composition of germanium-doped waste optical fibers

[0030] II. A method for recovering and utilizing germanium from the aforementioned germanium-doped waste optical fiber, comprising the following steps: (1) First, weigh 100g of waste optical fiber and cut it into 1-2cm lengths with scissors.

[0031] (2) The waste optical fiber obtained in step (1) was placed in a muffle furnace and calcined at 700℃ for 3 hours. After calcination, the mechanical toughness of the optical fiber decreased, the material became brittle, and it was prone to breakage. The calcined optical fiber was characterized, and the results are shown in […]. Figure 4 As shown in the figure, the original length of the discarded optical fiber is 2800-3000 cm. -1 A distinct absorption peak of organic functional groups was observed nearby; after calcination, this absorption peak significantly weakened or disappeared, indicating that the calcination process effectively removed the organic coating layer on the fiber surface. Meanwhile, at approximately 1080 cm⁻¹... -1 The characteristic absorption peaks of Si-O-Si still exist, indicating that the SiO2 framework structure remains stable after calcination.

[0032] (3) The waste optical fiber obtained in step (2) is ball-milled using a zirconium oxide ball mill jar and a planetary ball mill at a speed of 300 r / min for 10 min to obtain waste optical fiber powder.

[0033] (4) Mix urea and malic acid in a molar ratio of 1:2 and place them in a stoppered Erlenmeyer flask. Use a magnetic stirrer to heat and stir to prepare a eutectic solution at a temperature of 60°C and a speed of 300 r / min until a uniform and transparent liquid is formed.

[0034] (5) The waste optical fiber powder obtained in step (3) is placed into the eutectic solution obtained in step (4) with a solid-liquid ratio of 1:50 (g / ml). After reacting in an oil bath at 70°C for 4 hours, the mixture is filtered to obtain germanium-containing filtrate and filter residue. According to calculations, the leaching rate of germanium in this embodiment reaches 85.66%.

[0035] Example 2

[0036] This embodiment provides a method for leaching germanium from germanium-doped waste optical fiber, as detailed below: I. Using germanium-doped waste optical fibers recycled by a certain factory as raw materials, the main chemical components are shown in Table 2.

[0037] Table 2: Chemical composition of germanium-doped waste optical fibers

[0038] II. A method for recovering and utilizing germanium from the aforementioned germanium-doped waste optical fiber, comprising the following steps: (1) First, weigh 100g of waste optical fiber and cut it into 1-2cm lengths with scissors.

[0039] (2) The waste optical fiber obtained in step (1) is placed in a muffle furnace and roasted at a temperature of 750°C for 3 hours. After roasting, the mechanical toughness of the optical fiber decreases, the material becomes brittle, and it is easy to break.

[0040] (3) The waste optical fiber obtained in step (2) is ball-milled using a zirconium oxide ball mill jar and a planetary ball mill at a speed of 300 r / min for 20 min to obtain waste optical fiber powder.

[0041] (4) Take 60.06 g of urea and 90.08 g of lactic acid and add them to a stoppered triangular flask. That is, urea and lactic acid are mixed in a molar ratio of 1:1. Use a magnetic stirrer to heat and stir to prepare a eutectic solution at a temperature of 60°C and a speed of 300 r / min until a uniform and transparent liquid is formed.

[0042] (5) The waste optical fiber powder obtained in step (3) is placed into the eutectic solution obtained in step (4), with a solid-liquid ratio of 1:50 (g / ml). After reacting for 4 hours in an oil bath at 70℃, the solution is filtered, and the leaching rate of germanium reaches 91.32%.

[0043] Example 3

[0044] This embodiment provides a method for leaching germanium from germanium-doped waste optical fiber, as detailed below: I. Using germanium-doped waste optical fibers recycled by a certain factory as raw materials, the main chemical components are shown in Table 3.

[0045] Table 3: Chemical composition of germanium-doped waste optical fibers

[0046] II. A method for recovering and utilizing germanium from the aforementioned germanium-doped waste optical fiber, comprising the following steps: (1) First, weigh 100g of waste optical fiber and cut it into 1-2cm lengths with scissors.

[0047] (2) The waste optical fiber obtained in step (1) is placed in a muffle furnace and roasted at 800℃ for 3 hours. After roasting, the mechanical toughness of the optical fiber decreases, the material becomes brittle, and it is easy to break.

[0048] (3) The waste optical fiber obtained in step (2) is ball-milled using a zirconium oxide ball mill jar and a planetary ball mill at a speed of 300 r / min for 3 h to obtain waste optical fiber powder.

[0049] (4) Mix ethyl urea and citric acid in a molar ratio of 1:3, add the mixture to a stoppered triangular flask, and heat and stir with a magnetic stirrer to prepare a eutectic solution at a temperature of 60°C and a speed of 300 r / min until a uniform and transparent liquid is formed.

[0050] (5) The waste optical fiber powder obtained in step (3) is placed into the eutectic solution obtained in step (4), with a solid-liquid ratio of 1:50 (g / ml). After reacting for 4 hours in an oil bath at 70℃, the solution is filtered, and the leaching rate of germanium reaches 89.72%.

[0051] Comparative Example 1 This comparative example provides a method for leaching germanium from germanium-doped waste optical fiber, as detailed below: Except for replacing the eutectic solvent in step (4) with sodium tetraborate solution, the other conditions are the same as in Example 1.

[0052] Specifically, sodium tetraborate was dissolved in deionized water to prepare a leachate with a concentration of 0.1 mol / L. The waste optical fiber powder obtained in step (3) was added to the sodium tetraborate solution and mixed at a solid-liquid ratio of 1:50 (g / mL). The mixture was then reacted in an oil bath at 70 ℃ for 4 h.

[0053] After the reaction was completed, the mixture was filtered to obtain the filtrate and the residue. The germanium content in the filtrate was determined by ICP-OES, and the germanium leaching rate was calculated according to formula (1).

[0054] The results showed that the germanium leaching rate was 71.33%.

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for leaching germanium from germanium-doped waste optical fibers, characterized in that, Includes the following steps: A germanium-doped waste optical fiber is provided; The germanium-doped waste optical fiber was calcined and then ball-milled to obtain waste optical fiber powder. The obtained waste optical fiber powder was mixed with a eutectic solution and heated to react. The resulting reaction solution was then subjected to solid-liquid separation to obtain a germanium-containing filtrate. The eutectic solvent includes urea compounds and organic acids; The organic acid is selected from one or more of lactic acid, malic acid, and citric acid; the urea compound is selected from one or more of urea, methylurea, and ethylurea.

2. The processing method according to claim 1, characterized in that, The length of the germanium-doped waste optical fiber is 1~2cm.

3. The processing method according to claim 1, characterized in that, The roasting temperature is 600~800℃ and the time is 2~6h.

4. The processing method according to claim 1, characterized in that, The ball mill uses a zirconia ball mill jar and a planetary ball mill with a rotation speed of 300~500 r / min and a time of 10 min~3 h.

5. The processing method according to claim 1, characterized in that, The molar ratio of urea, methylurea, ethylurea and organic acid is (1:1) to (1:3).

6. The processing method according to claim 1, characterized in that, The solid-liquid ratio of waste optical fiber powder to eutectic solution is (1:50) ~ (1:100) g / ml.

7. The processing method according to claim 1, characterized in that, The conditions for the heating reaction are: oil bath temperature 50~90℃, time 2~6h.

8. The processing method according to any one of claims 1 to 7, characterized in that, The germanium-doped waste optical fiber contains 0.05-10% germanium and 90-99.9% silicon by mass.

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