A method for extracting germanium from germanium-containing lignite while producing coke and tar by microwave pyrolysis

Abstract

This invention provides a method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, belonging to the field of lignite resource utilization technology. The method includes the following steps: S1, adding water to the germanium-containing lignite to form pellets, then drying to complete sample preparation; S2, mixing the sample with an alkaline flux-reduction composite agent, placing it in a microwave roasting furnace under a reducing atmosphere for roasting, and simultaneously collecting tar to obtain coke and germanium-containing volatile products; S3, weighing the sample before and after roasting, and calculating the germanium volatilization efficiency and the yields of coke and tar after digestion and germanium content detection; S4, extracting germanium from the volatile products; S5, sieving the coke to remove impurities and recovering the tar for later use. This invention solves the problem of germanium being difficult to volatilize due to being encapsulated by gangue in traditional processes by introducing an alkaline flux-reduction composite agent and combining it with microwave pyrolysis technology. The composite agent lowers the melting point of the gangue, and the elemental carbon powder enhances the reducing atmosphere, synergistically promoting the conversion to O, thus achieving efficient recovery of the rare dispersed metal germanium.

Description

Technical Field

[0001] This invention relates to the field of lignite resource utilization technology, and more specifically, to a method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar. Background Technology

[0002] Germanium, due to its excellent physicochemical properties, has wide applications in many fields such as infrared optics, fiber optic communication, aerospace, military equipment, medical and health care, chemical catalysis, new energy, and semiconductors. In the semiconductor industry, germanium, as a key basic material, holds a particularly prominent strategic position. In recent years, with the rapid development of global high-tech and new energy industries, the demand for germanium resources has continued to grow, and its market value and strategic significance have been constantly rising. Developed economies such as the United States, the European Union, and Japan have successively implemented strict controls through critical mineral legislation to consolidate their competitive advantage in cutting-edge technology fields. Against this backdrop, the strategic importance of germanium resources is further highlighted.

[0003] Germanium is a typical rare and dispersed metal that does not possess the conditions to form independent deposits in nature. Its resources mainly exist as associated minerals in lead-zinc ore and lignite. Among these two sources, lignite occupies a crucial position, contributing more than 50% of the global germanium supply and serving as one of the core carriers for the development and utilization of germanium resources.

[0004] Currently, the mainstream technology for extracting germanium from germanium-containing lignite in the industry is the combustion volatilization-chlorination distillation process. This process adopts a parallel mode of energy utilization and germanium extraction. While generating heat energy from lignite combustion for power generation, the high-temperature environment during combustion is used to convert germanium-containing substances in the coal into dust. Subsequent collection processes then achieve preliminary enrichment of germanium. However, this process has significant technical shortcomings. Not only is the germanium recovery efficiency low, but the utilization rate of heat energy generated from lignite combustion is also unsatisfactory. The combination of these two inefficiencies prevents the full realization of the comprehensive utilization value of germanium-containing lignite, resulting in low overall utilization efficiency. How to invent a method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar to solve these problems has become an urgent issue for those skilled in the art. Summary of the Invention

[0005] To overcome the above shortcomings, this invention provides a method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar. This method aims to address the problem that the recovery efficiency of germanium is low and the utilization rate of thermal energy generated by lignite combustion is also unsatisfactory. The superposition of these two inefficiencies results in the failure to fully realize the comprehensive utilization value of germanium-containing lignite resources and the overall low utilization efficiency.

[0006] This invention is implemented as follows:

[0007] This invention provides a method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, comprising the following steps:

[0008] S1. Add appropriate amount of water to germanium-containing lignite to form pellets, and place the obtained sample in an oven to dry, thus completing sample preparation;

[0009] S2. Take the alkaline flux-reduction composite agent and mix it with the dried sample in S1. Then place the mixed sample in a microwave roasting furnace under a reducing atmosphere for roasting. During the roasting process, collect the tar through a condensation device. After roasting, obtain coke and volatile products.

[0010] S3. Weigh the samples before and after calcination, grind the samples finely, and then use... - The sample was digested with a mixed acid, and after the germanium content was detected, the germanium volatilization efficiency, coke yield and tar yield were calculated.

[0011] S4. Collect the volatile products and extract germanium using appropriate processes.

[0012] S5. Screen the coke products to remove impurities and recover the tar products for later use.

[0013] Preferably, the processing method of the germanium-containing lignite in S1 is to crush and grind it to 100% less than 74μm, and the germanium content is detected by ICP-MS to be 100ppm. The weight of the germanium-containing lignite is 20g each time, the oven temperature is 105℃, and the drying time is 24h.

[0014] Preferably, the alkaline flux-reduction composite agent in S2 is of analytical grade. It is prepared by mixing with elemental toner at a mass ratio of 2:1, with the elemental toner having a particle size ≤5μm and a purity ≥99.5%.

[0015] Preferably, the amount of alkaline flux-reduction composite agent added in S2 is 5%-8% of the mass of germanium-containing lignite sample, and the mixing treatment is to mix the composite agent with the dried sample and let it stand for 10 minutes.

[0016] Preferably, the reducing atmosphere in S2 is atmosphere, The gas introduction rate is 0.5-1 L / min, and the thickness of the mixed sample in the microwave roasting furnace is 1-3 cm.

[0017] Preferably, in step S2, the heating rate of microwave calcination is 10-15℃ / min, the calcination temperature is 500-800℃, the calcination time is 0.5-2h, and the microwave power is 500-1000w.

[0018] Preferably, the acid solution in S3 is an analytical grade solution mixed at a volume ratio of 6:1. - The mixed acid was diluted with deionized water during the digestion process.

[0019] Preferably, the process for extracting germanium in S4 is as follows: the volatile product is passed into a condenser with a cooling temperature of -10~0℃, the germanium oxide solid is collected and then reduced with hydrogen to obtain metallic germanium.

[0020] Preferably, in step S5, a 100-mesh standard sieve is used for screening and impurity removal. The material on the sieve is coke product, and the material under the sieve is impurities.

[0021] Preferably, the germanium volatilization efficiency, coke yield, and tar yield in S3 are all calculated based on the changes in sample mass, germanium content, and condensate device mass before and after roasting.

[0022] The beneficial effects of this invention are:

[0023] 1. The core innovation of this patented technology lies in the first-time proposal and realization of a three-field synergistic germanium extraction mechanism involving alkali melting field, reduction field, and microwave electromagnetic heating field. This mechanism overcomes the limitations of existing technologies that rely on a single heating field or a single reaction field. The constructed alkali melting field, the reduction field constructed by elemental carbon powder, and the electromagnetic heating field constructed by microwave form a mutually reinforcing and interdependent linkage, rather than a simple superposition of independent effects. Their synergistic effect directly promotes a qualitative leap in germanium volatilization efficiency, while ensuring stable coke yield and tar yield, thus achieving dual optimization of germanium extraction efficiency and product quality.

[0024] 2. The microwave pyrolysis in this invention has the characteristics of rapid internal heating and uniform temperature distribution, which greatly reduces energy consumption compared with traditional resistance furnace roasting. At the same time, the process does not require the use of harmful chlorinating agents, avoiding the environmental pollution caused by chloride emissions in traditional processes. Furthermore, the digestion process uses analytical grade reagents and deionized water, and the subsequent products have no harmful residues, which meets the development requirements of green metallurgy.

[0025] 3. This invention breaks through the limitations of single germanium extraction. While extracting germanium, it simultaneously produces high-quality coke and tar. Compared with the traditional process that only uses lignite for power generation and germanium extraction, this method fully taps the energy and material value of lignite and achieves the dual goal of "germanium extraction + coke / tar upgrading".

[0026] 4. The process flow of this invention is clear, and the core steps only include sample preparation, compound agent mixing, microwave roasting, product detection and processing. The operation is convenient and controllable. The raw materials used are widely available and inexpensive. The experimental equipment is conventional metallurgical equipment such as microwave roasting furnace and ICP-MS detector, without the need for special customization. At the same time, the process parameter range is clear, which is conducive to industrial scale-up production and provides a feasible path for the large-scale and efficient utilization of germanium-containing lignite resources. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a process flow diagram of a method for extracting germanium from germanium-containing lignite using microwave pyrolysis and simultaneously preparing coke and tar, provided by an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] I. Preparations before implementation

[0031] (a) Raw material specifications

[0032] The germanium-containing lignite used in the experiment was crushed and ground to a particle size of less than 74 μm. ICP-MS analysis confirmed a germanium content of 100 ppm. Industrial analysis results showed: fixed carbon 42.3%, volatile matter 38.7%, ash 17.2%, and moisture 1.8%. The alkaline flux-reduction composite agent was analytical grade... It was prepared by uniformly mixing (purity ≥99.8%) and elemental carbon powder (particle size ≤5μm, purity ≥99.5%) at a mass ratio of 2:1; the experiment used Gas purity ≥ 99.99%, - All samples were of analytical grade, and the solvent used for dilution and digestion was deionized water (conductivity ≤10μS / cm).

[0033] (II) Experimental Equipment

[0034] Microwave roasting oven (power adjustment range 0-1500w, temperature control accuracy ±5℃, furnace volume 5L); ICP-MS analyzer (detection limit ≤0.01ppm, relative standard deviation ≤2%); electronic balance (accuracy 0.0001g); forced-air drying oven (temperature control range 50-200℃, temperature control accuracy ±1℃); condensation recovery device (cooling temperature adjustable range -20~20℃); 100-mesh standard sieve; ball mill (speed adjustable 0-500r / min).

[0035] (III) Detection and Calculation Methods

[0036] Germanium content detection: Samples before and after calcination were ground to below 200 mesh and mixed at a volume ratio of 6:1. - The mixed acid was microwave digested, and the digest was diluted with deionized water to a fixed volume. The germanium content was then detected by ICP-MS.

[0037] Germanium volatilization efficiency: Based on the sample mass and germanium content before and after calcination, the formula for calculating germanium volatilization efficiency is as follows:

[0038]

[0039] in, For evaporation efficiency% and The values ​​are the sample mass (g) before and after pyrolysis, respectively. and The germanium content (wt.) of the samples before and after calcination is shown below.

[0040] The formula for calculating coke yield is:

[0041]

[0042] in, Coke yield % (coke is weighed after being sieved through a 100-mesh sieve to remove impurities).

[0043] The formula for calculating tar yield is:

[0044]

[0045] in, Tar yield; and The values ​​are the weights (g) of condensate before and after pyrolysis (the cooling temperature of the condensation device is controlled at -10~0℃).

[0046] II. Implementation Examples

[0047] Example 1

[0048] Sample preparation: Weigh 20g of pretreated germanium-containing lignite, add an appropriate amount of deionized water and stir evenly to form briquettes. Place the briquettes in a 105℃ forced-air drying oven and dry for 24h. Cool to room temperature for later use.

[0049] Composite agent mixing: Weigh 1.0g of alkaline flux-reduction composite agent at 5% of the mass of germanium-containing lignite, mix it thoroughly with the dried coal briquettes, and let it stand for 10 minutes to allow the composite agent to be evenly adsorbed on the surface of the coal briquettes.

[0050] Microwave calcination: Place the mixed sample into a microwave calcination oven, control the thickness of the spread to 1 cm, and introduce... A reducing atmosphere was created by introducing gas (at a rate of 0.5 L / min), and the temperature was increased to 500°C at a rate of 10°C / min. The microwave power was maintained at 500 W, and the calcination was carried out for 0.5 h. During the calcination process, the tar was collected by a condenser (cooling temperature -10°C).

[0051] Product processing and testing: After roasting, the product was cooled to room temperature, the coke was weighed and sieved to remove impurities, and the tar collected by the condenser was tested. Samples before and after roasting were digested and analyzed by ICP-MS.

[0052] Test results: The germanium content in the roasted slag was 87.35 ppm, the germanium volatilization efficiency was 45.71%, the coke yield was 62.15%, and the tar yield was 18.11%.

[0053] Example 2

[0054] Sample preparation: Same as in Example 1;

[0055] Composite agent mixing: Weigh 1.2g of alkaline flux-reduction composite agent at 6% of the mass of germanium-containing lignite, and perform mixing and standing operations as in Example 1;

[0056] Microwave roasting: 1.5cm thick layer of batter. The feed rate was 0.6 L / min, the heating rate was 12℃ / min, the calcination temperature was 600℃, the microwave power was 500 W, and the calcination time was 1 h; the cooling temperature of the condenser was -5℃.

[0057] Product processing and testing: Same as in Example 1.

[0058] Test results: The germanium content in the roasted slag was 67.87 ppm, the germanium volatilization efficiency was 58.38%, the coke yield was 61.32%, and the tar yield was 18.77%.

[0059] Example 3

[0060] Sample preparation: Same as in Example 1;

[0061] Composite agent mixing: Weigh 1.4g of alkaline flux-reduction composite agent at 7% of the mass of germanium-containing lignite, and perform mixing and standing operations as in Example 1;

[0062] Microwave baking: 2cm thick layer of batter. The feed rate was 0.8 L / min, the heating rate was 13℃ / min, the calcination temperature was 700℃, the microwave power was 800 W, and the calcination time was 1 h; the cooling temperature of the condenser was -3℃.

[0063] Product processing and testing: Same as in Example 1.

[0064] Test results: The germanium content in the roasted slag was 50.03 ppm, the germanium volatilization efficiency was 69.39%, the coke yield was 61.18%, and the tar yield was 19.04%.

[0065] Example 4

[0066] Sample preparation: Same as in Example 1;

[0067] Composite agent mixing: Weigh 1.6g of alkaline flux-reduction composite agent at 8% of the mass of germanium-containing lignite, and perform mixing and standing operations as in Example 1;

[0068] Microwave roasting: 2.5cm thick layer of batter. The feed rate was 0.9 L / min, the heating rate was 14 °C / min, the calcination temperature was 700 °C, the microwave power was 1000 W, and the calcination time was 2 h; the cooling temperature of the condenser was 0 °C.

[0069] Product processing and testing: Same as in Example 1.

[0070] Test results: The germanium content in the roasted slag was 34.68 ppm, the germanium volatilization efficiency was 78.83%, the coke yield was 61.05%, and the tar yield was 19.12%.

[0071] Example 5

[0072] Sample preparation: Same as in Example 1;

[0073] Composite agent mixing: Weigh 1.4g of alkaline flux-reduction composite agent at 7% of the mass of germanium-containing lignite, and perform mixing and standing operations as in Example 1;

[0074] Microwave baking: 2cm thick layer of batter. The feed rate was 0.8 L / min, the heating rate was 15℃ / min, the calcination temperature was 800℃, the microwave power was 800 W, and the calcination time was 2 h; the cooling temperature of the condenser was -2℃.

[0075] Product processing and testing: Same as in Example 1.

[0076] Test results: The germanium content in the roasted slag was 26.76 ppm, the germanium volatilization efficiency was 83.65%, the coke yield was 61.11%, and the tar yield was 19.31%.

[0077] Example 6

[0078] Sample preparation: Same as in Example 1;

[0079] Composite agent mixing: Weigh 1.6g of alkaline flux-reduction composite agent at 8% of the mass of germanium-containing lignite, and perform mixing and standing operations as in Example 1;

[0080] Microwave baking: 3cm thick layer of batter. The feed rate was 1.0 L / min, the heating rate was 15℃ / min, the calcination temperature was 800℃, the microwave power was 1000w, and the calcination time was 2h; the cooling temperature of the condenser was 0℃.

[0081] Product processing and testing: Same as in Example 1.

[0082] Test results: The germanium content in the roasted slag was 12.97 ppm, the germanium volatilization efficiency was 92.18%, the coke yield was 60.28%, and the tar yield was 19.85%.

[0083] Example 7

[0084] Sample preparation: Same as in Example 1;

[0085] Composite agent mixing: Weigh 1.6g of alkaline flux-reduction composite agent at 8% of the mass of germanium-containing lignite, and perform mixing and standing operations as in Example 1;

[0086] Microwave baking: 3cm thick layer of batter. The feed rate was 1.0 L / min, the heating rate was 15℃ / min, the calcination temperature was 800℃, the microwave power was 1000w, and the calcination time was 1h; the cooling temperature of the condenser was -1℃.

[0087] Product processing and testing: Same as in Example 1.

[0088] Test results: The germanium content in the roasted slag was 23.21 ppm, the germanium volatilization efficiency was 85.87%, the coke yield was 60.89%, and the tar yield was 19.55%.

[0089] Example 8

[0090] Sample preparation: Same as in Example 1;

[0091] Composite agent mixing: Weigh 1.6g of alkaline flux-reduction composite agent at 8% of the mass of germanium-containing lignite, and perform mixing and standing operations as in Example 1;

[0092] Microwave baking: 3cm thick layer of batter. The feed rate was 1.0 L / min, the heating rate was 15℃ / min, the calcination temperature was 800℃, the microwave power was 1000 W, and the calcination time was 0.5 h; the cooling temperature of the condenser was -2℃.

[0093] Product processing and testing: Same as in Example 1.

[0094] Test results: The germanium content in the roasted slag was 28.32 ppm, the germanium volatilization efficiency was 82.91%, the coke yield was 60.34%, and the tar yield was 19.39%.

[0095] Summary and Analysis Table of Microwave Pyrolysis Experimental Data for Germanium-Containing Lignite:

[0096] 1. The effect of the amount of compound agent added:

[0097] As the amount of composite agent added increased from 5% to 8%, the germanium volatilization efficiency gradually increased (45.71% → 92.18%). Breaking through lignite , The physical barrier of gangue and the enhanced reducing atmosphere of elemental carbon powder work synergistically to promote... Easily volatile When the O conversion rate reaches 8%, the synergistic effect approaches saturation.

[0098] 2. The effect of roasting temperature and time:

[0099] As the temperature increased from 500℃ to 800℃, the germanium volatilization efficiency nearly doubled (45.71% → 92.18%), due to the significant increase in volatilization efficiency at higher temperatures. O saturated vapor pressure accelerates the conversion and volatilization of germanium-containing substances; at the same temperature, extending the calcination time (0.5h→2h) can improve the volatilization efficiency (e.g., Example 8→Example 6, 82.91%→92.18%), ensuring that the germanium-containing substances react fully.

[0100] 3. The influence of microwave power:

[0101] Increasing the power from 500W to 1000W significantly improved the germanium volatilization efficiency (e.g., from Example 2 to Example 6, 58.38% to 92.18%). The high power enhanced the uniformity of internal heating of the sample by the microwave field, reduced the local temperature gradient, and prevented germanium from being encapsulated by the incompletely pyrolyzed coal matrix.

[0102] 4. Product yield stability:

[0103] In all embodiments, the coke yield remained stable at 60.28%-62.15%, while the tar yield increased from 18.11% to 19.85% with the optimization of process parameters. This indicates that the synergistic effect of the composite agent and microwave roasting not only improved the germanium recovery efficiency but also did not disrupt the pyrolysis law of lignite organic matter. Furthermore, the tar formation environment was optimized due to the fluxing effect.

[0104] III. Comparative Example

[0105] Comparative Example 1 (No compounding agent + conventional roasting)

[0106] Sample preparation: Same as in Example 1 (without adding alkaline flux-reduction composite agent);

[0107] Calcination process: Place the dried coal briquettes into a conventional electric resistance furnace, with a layer thickness of 3cm, and then introduce gas. Gas (rate 1.0 L / min), heating rate 10 °C / min, heated to 800 °C, calcined for 2 h; condensation device and collection operation are the same as in Example 1;

[0108] Product processing and testing: Same as in Example 1.

[0109] Test results: The germanium content in the roasted slag was 57.13 ppm, the germanium volatilization efficiency was 64.73%, the coke yield was 61.74%, and the tar yield was 18.84%.

[0110] Comparative Example 2 (No composite agent + high-temperature conventional calcination)

[0111] Sample preparation: Same as in Example 1 (without adding alkaline flux-reduction composite agent);

[0112] Firing procedure: Conventional electric resistance furnace firing, material layer thickness 3cm. The flow rate was 1.0 L / min, the heating rate was 10 °C / min, the temperature was raised to 1100 °C, and the calcination was carried out for 2 hours; the condensation device and collection operation were the same as in Example 1;

[0113] Product processing and testing: Same as in Example 1.

[0114] Test results: The germanium content in the roasted slag was 23.73 ppm, the germanium volatilization efficiency was 85.44%, the coke yield was 61.34%, and the tar yield was 18.94%.

[0115] Comparative Example 3 (No composite agent + microwave roasting)

[0116] Sample preparation: Same as in Example 1 (without adding alkaline flux-reduction composite agent);

[0117] Calcination procedure: The microwave calcination parameters were the same as in Example 6 (temperature 800℃, power 1000w, time 2h). (rate 1.0 L / min)

[0118] Product processing and testing: Same as in Example 1.

[0119] Test results: The germanium content in the roasted slag was 38.42 ppm, the germanium volatilization efficiency was 75.36%, the coke yield was 60.87%, and the tar yield was 19.02%.

[0120] Summary table of comparative data:

[0121] 1. Differences in efficiency between roasting methods:

[0122] At the same temperature (800℃) and time (2h), the germanium volatilization efficiency of microwave roasting (Comparative Example 3) (75.36%) was significantly higher than that of conventional resistance furnace roasting (Comparative Example 1, 64.73%), demonstrating the advantages of microwave "rapid internal heating and uniform temperature", which can reduce the problem of "external overheating and internal unreaction" in conventional roasting.

[0123] 2. Limitations of conventional high-temperature roasting:

[0124] Comparative Example 2 requires a temperature increase to 1100℃ (300℃ higher than Comparative Example 1) to achieve a germanium volatilization efficiency of 85.44%, which is close to the level of some examples. However, the high temperature leads to a surge in energy consumption (about 40% higher than microwave roasting at 800℃) and may cause excessive pyrolysis of coke, resulting in a decline in product quality.

[0125] 3. Efficiency bottleneck without compounding agents:

[0126] Comparative Example 3 (microwave roasting without composite agent) and Example 6 (microwave roasting with 8% composite agent) differed only in parameters from the addition of composite agent, but the germanium volatilization efficiency differed by 16.82 percentage points (75.36%→92.18%), proving that gangue blockage is the core bottleneck of the process without composite agent, and the introduction of composite agent can effectively overcome this limitation.

[0127] IV. Results Analysis and Explanation

[0128] (I) Comparative Analysis

[0129] Select "800℃, 2h, 1.0L / min" Using "3cm material thickness" as the benchmark parameter, compare key indicators:

[0130] Comparison and analysis table of examples and comparative examples:

[0131] The germanium volatilization efficiency of Example 6 (92.18%) is 7.9 percentage points higher than the highest value of the comparative example (Comparative Example 2, 85.44%), and it does not require high temperature, thus avoiding energy waste. Moreover, the relative energy consumption of Example 6 (1.0) is significantly lower than that of conventional roasting (Comparative Example 1:1.5, Comparative Example 2:1.8). Even compared with microwave roasting without composite agent (Comparative Example 3:1.1), the "energy consumption per unit of germanium recovery" is reduced by about 10% due to the efficiency improvement. It can be seen that the example, through the combination of "microwave roasting + alkaline fluxing - reducing composite agent", breaks through the dual contradiction of "low efficiency" and "high energy consumption" of traditional processes. Its synergistic mechanism (physical fluxing + chemical reduction + microwave enhancement) provides a new path for the efficient utilization of germanium-containing lignite, which has significant technical innovation and application value.

[0132] (II) Influence of process parameters

[0133] Temperature and Time: As the calcination temperature increased from 500℃ to 800℃ and the calcination time was extended from 0.5h to 2h, the germanium volatilization efficiency significantly improved (Examples 1-6). This is because the extended residence time at higher temperatures is beneficial. Towards volatile O conversion, and The saturated vapor pressure of O increases with increasing temperature, which promotes the volatilization of germanium;

[0134] Microwave power: When the microwave power is increased from 500W to 1000W, the germanium volatilization efficiency is significantly improved (Examples 3-4, 6). This is because the increase in microwave power can enhance the internal heating uniformity, reduce the local temperature gradient, and prevent germanium from being trapped by gangue and unable to volatilize.

[0135] Composite agent addition amount: As the composite agent addition amount increased from 5% to 8%, the germanium volatilization efficiency gradually improved (Examples 1-4, 6). The fluxing effect removes the gangue barrier, and the elemental carbon powder enhances the reducing atmosphere. The two work together to promote the transformation and volatilization of germanium.

[0136] (III) Advantage Verification

[0137] 1. Compared with traditional processes: Comparative Example 1 (conventional calcination) has a germanium volatilization efficiency of only 64.73%, which is far lower than the 92.18% of Example 6; Comparative Example 2 requires raising the temperature to 1100℃ to achieve a volatilization efficiency of 85.44%, while the present invention can achieve a higher recovery rate at 800℃, reducing energy consumption by about 30%;

[0138] 2. Comparison with microwave process without composite agent: Comparative Example 3 (without composite agent) has a germanium volatilization efficiency of 75.36%, while Example 6 (with 8% composite agent) has an improvement of 16.82 percentage points, proving that the synergistic effect of alkaline flux-reduction composite agent is the key to improving germanium recovery efficiency. This technical solution is not a conventional choice in the field.

[0139] 3. Product Quality Assurance: In all embodiments, the coke yield remained stable at 60%-62%, and the tar yield at 18%-20%, showing no significant decrease compared to the comparative example. Furthermore, the fixed carbon content of the coke increased to over 65%, and the proportion of light components (benzene, toluene, etc.) in the tar increased by 30%, achieving the dual goals of "germanium extraction + product quality improvement." As a flux, it can reduce the content of lignite in lignite. , Reduce the melting point of gangue (from above 1500℃ to below 800℃) to decrease the impact of gangue on... The physical barrier to the volatilization of germanium solves the problem of "germanium being trapped in the gangue and difficult to volatilize" in traditional microwave pyrolysis. The supplementary reducing atmosphere intensity of elemental carbon powder promotes volatilization. Towards O conversion, while inhibiting O re-oxidation, synergistically with the reducing atmosphere of microwave pyrolysis.

[0140] (iv) Precautions

[0141] 1. The mixing of the composite agent must be uniform; otherwise, it will lead to local differences in fluxing-reduction effect, affecting the stability of germanium volatilization efficiency.

[0142] 2. During the roasting process The feed rate needs to be stable to prevent air from entering the furnace and causing problems. O is oxidized into non-volatile substances. ;

[0143] 3. The temperature of the condensation device needs to be controlled between -10 and 0℃. Too high a temperature will cause tar to evaporate and be lost, while too low a temperature may cause pipe blockage.

[0144] 4. For digestion - Mixed acids must be prepared and used immediately to avoid concentration changes affecting the sample digestion effect, which could lead to errors in germanium content detection.

[0145] It should be noted that the specific model and specifications need to be selected and determined based on the actual specifications of the device. The specific selection and calculation method adopts the existing technology in this field, so it will not be described in detail here.

[0146] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, characterized in that, Includes the following steps: S1. Add appropriate amount of water to germanium-containing lignite to form pellets, and dry the obtained sample in an oven to complete sample preparation; S2. Take the alkaline flux-reduction composite agent and mix it with the dried sample in S1. Then place the mixed sample in a microwave roasting furnace under a reducing atmosphere for roasting. During the roasting process, collect the tar through a condensation device. After roasting, obtain coke and volatile products. S3. Weigh the samples before and after calcination, grind the samples finely, and then use... - The sample was digested with a mixed acid, and after the germanium content was detected, the germanium volatilization efficiency, coke yield and tar yield were calculated. S4. Collect the volatile products and extract germanium using appropriate processes. S5. Screen the coke products to remove impurities and recover the tar products for later use.

2. The method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, is characterized in that... The processing method for germanium-containing lignite in S1 is to crush and grind it to 100% less than 74μm, and the germanium content is detected by ICP-MS to be 100ppm. Each time, the weight of the germanium-containing lignite is 20g, the oven temperature is 105℃, and the drying time is 24h.

3. The method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, is characterized in that... The alkaline fluxing-reducing composite agent in S2 is of analytical grade. It is prepared by mixing with elemental toner at a mass ratio of 2:1, with the elemental toner having a particle size ≤5μm and a purity ≥99.5%.

4. The method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, is characterized in that... The amount of alkaline flux-reduction composite agent added in S2 is 5%-8% of the mass of germanium-containing lignite sample, and the mixing treatment is to mix the composite agent with the dried sample and let it stand for 10 minutes.

5. The method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, is characterized in that... The reducing atmosphere in S2 is atmosphere, The gas introduction rate is 0.5-1 L / min, and the thickness of the mixed sample in the microwave roasting furnace is 1-3 cm.

6. The method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, is characterized in that... The heating rate of microwave calcination in S2 is 10-15℃ / min, the calcination temperature is 500-800℃, the calcination time is 0.5-2h, and the microwave power is 500-1000w.

7. The method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, is characterized in that... The acid solution in S3 is an analytical grade mixture at a volume ratio of 6:

1. - The mixed acid was diluted with deionized water during the digestion process.

8. A method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, characterized in that, The process for extracting germanium in S4 is as follows: the volatile product is passed into a condenser with a cooling temperature of -10~0℃, and the germanium oxide solid is collected and then reduced with hydrogen to obtain metallic germanium.

9. A method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, characterized in that... The sieving and impurity removal process in S5 uses a 100-mesh standard sieve. The material on the sieve is coke product, and the material under the sieve is impurities.

10. A method for extracting germanium from germanium-containing lignite using microwave pyrolysis while simultaneously preparing coke and tar, as described in claim 1, characterized in that, The germanium volatilization efficiency, coke yield, and tar yield in S3 are all calculated based on the changes in sample mass, germanium content, and condensate device mass before and after roasting.

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