Germanic acid and preparation method thereof

Abstract

The invention belongs to the field of resource recovery, and discloses a preparation method of germanic acid, which comprises the following steps: step 1, mixing germanium-containing soot and alkali liquor to obtain slurry A, and carrying out solid-liquid separation after the slurry A reacts to obtain germanium-containing leachate and leaching residues; and step 2, continuously introducing CO2 into the germanium-containing leachate to obtain slurry B, and carrying out solid-liquid separation on the slurry B to obtain a precipitation material, namely germanic acid. According to the method, the carbon dioxide and the germanium-containing leachate are reacted, impurity cations are prevented from being introduced, the concentration of germanic acid is increased, the reaction can be carried out under the condition that the pH value is 6-7, the pH value of a reaction system does not need to be adjusted before the reaction, or the pH value range of the reaction system needing to be adjusted is greatly reduced, raw materials are saved, the process is simplified, and popularization and industrialization are facilitated.

Description

Technical Field

[0001] The invention belongs to the field of resource recovery and relates to a method for recovering germanium elements, in particular to germanic acid and a preparation method thereof. Background Art

[0002] Germanium is a typical rare dispersed element, with a content of about 7 parts per million in the earth's crust. It is widely used in semiconductors, aerospace measurement and control, nuclear physics detection, optical fiber communications, infrared optics, biomedicine and other fields. Germanium ash is relatively scarce in the world, and the main raw materials for extracting germanium include germanium concentrate, germanium coal ash and germanium-containing ash.

[0003] In the prior art, commonly used germanium extraction processes include pyrometallurgical processes and hydrometallurgical processes, and the appropriate extraction process is usually selected according to different raw materials. Usually, pyrometallurgical processes are used to extract germanium from coal, and hydrometallurgical processes are used to recover germanium during non-ferrous metal smelting. The pyrometallurgical enrichment process is short and corrosion-free, but the recovery rate is low. The pyrometallurgical process for recovering germanium has a short enrichment process and is corrosion-free, but the recovery rate of germanium is low. The wet process for recovering germanium usually uses acid leaching to extract germanium first, and then enriches germanium through the tannin method or the chlorination distillation method. The wet process for recovering germanium has the advantages of high recovery rate and low energy consumption, but the acid is highly corrosive, has high requirements for equipment and a complex process.

[0004] At present, the enrichment and recovery of germanium is mainly in the form of germanium oxide or germanium sulfide, and complex refining and purification processes are still required. Germanic acid is an important product of germanium and an important basic raw material for the production of germanium chemicals. It has important applications in the fields of optical fiber, optical glass and medicine. The current preparation methods of germanic acid mostly use pure metallic germanium as raw material, and adopt hydrothermal and chemical synthesis methods. The process is long and the cost is high. Summary of the invention

[0005] In view of the defects and shortcomings of the prior art, in a first aspect, the present invention provides a method for preparing germanic acid; in a second aspect, the present invention provides germanic acid prepared by the above preparation method.

[0006] In a first aspect, the present invention provides a method for preparing germanic acid, comprising the following steps:

[0007] Step 1, mixing germanium-containing soot and alkali solution for a certain period of time and then separating the solid and liquid to obtain germanium-containing leaching solution and leaching residue;

[0008] Step 2, continuously introducing CO2 into the germanium-containing leaching solution to obtain slurry B, and solid-liquid separation of slurry B to obtain a precipitated material, namely germanic acid.

[0009] Preferably, in step 1, the reaction of the germanium-containing soot and the alkali solution further includes a sand grinding process, and after the germanium-containing soot and the alkali solution are mixed, the mixture of the germanium-containing soot and the alkali solution is sand ground.

[0010] More preferably, the sand milling speed is 600-2000 rpm; the sand milling time is 1-6 hours; and the sand milling medium is zirconia balls.

[0011] Preferably, in step 1, the liquid-to-solid ratio of the alkali solution and the germanium-containing fly ash used is 1-5:1 L / Kg; and the concentration of the alkali solution is 20-100 g / L.

[0012] Preferably, the concentration of the alkali solution is 20 to 100 g / L; more preferably, the concentration of the alkali solution is 30 to 80 g / L.

[0013] Preferably, the germanium content in the germanium-containing soot is higher than 0.2%.

[0014] Preferably, the alkali solution is any one or both of potassium hydroxide solution and sodium hydroxide solution; more preferably, the alkali solution is sodium hydroxide solution.

[0015] Preferably, in step 2, the flow rate of CO2 is 40 to 120 L / m 3 / min; further preferably, the flow rate of CO2 is 60 to 100 L / m 3 / min.

[0016] Preferably, in step 2, the reaction temperature of the reaction system is 20 to 40° C.; and the reaction time of the reaction system is 1 to 4 hours.

[0017] Preferably, the mass fraction of germanium in the germanium-containing soot is higher than 0.2%.

[0018] In a second aspect, a germanic acid is prepared by the above preparation method.

[0019] Compared with the prior art, the present invention has the following obvious beneficial effects:

[0020] (1) The present invention generates germanic acid precipitate by reacting carbon dioxide with germanium element in the leaching solution. Compared with the prior art, firstly, the use of carbon dioxide to prepare germanic acid can avoid the introduction of impure cations and improve the purity of germanic acid. Secondly, the use of carbon dioxide to prepare germanic acid can be carried out at a pH value of 6 to 7 compared with the use of sulfuric acid or hydrochloric acid to prepare germanium-containing products. There is no need to adjust the pH value of the reaction system before the reaction or the pH value range of the reaction system that needs to be adjusted is greatly reduced, thereby saving raw materials, simplifying the process, and being conducive to promotion and industrialization.

[0021] (2) The present invention utilizes the sand milling refinement effect and the exothermic effect to strengthen the leaching effect of germanium, shorten the leaching time, and improve the leaching rate. At the same time, because most of the impurity metal elements in the ash are amphoteric metal elements, the impurity metals can also be dissolved under strong alkaline conditions. By adding a sand milling process, the germanium element can be leached under weak alkaline conditions, reducing the possibility of other impurity elements being leached, and reducing the content of impurity elements in the leachate. In addition, the leachate is weakly alkaline, and there is no need to adjust the pH value of the reaction system when using carbon dioxide to precipitate germanium. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the XRD test pattern of germanic acid obtained in Example 3;

[0023] Figure 2 This is a SEM image of germanic acid obtained in Example 3;

[0024] Figure 3 This is the XRD pattern of germanic acid prepared in Example 5. DETAILED DESCRIPTION

[0025] The present invention provides the following specific technical solutions.

[0026] In a first aspect, the present invention provides a method for preparing germanic acid, comprising the following steps:

[0027] Step 1, mixing germanium-containing soot and alkali solution for a certain period of time and then separating the solid and liquid to obtain germanium-containing leaching solution and leaching residue;

[0028] Step 2, continuously introducing CO2 into the germanium-containing leaching solution to obtain slurry B, and solid-liquid separation of slurry B to obtain a precipitated material, namely germanic acid.

[0029] In the prior art, when the wet process is used to recover germanium, the acid used is highly corrosive and has high requirements on equipment. After leaching, the pH value of the reaction system needs to be adjusted to a strong acidity, and the recovery process is complicated and costly. The inventor has found through research that clean CO2 gas can be used as a germanium precipitant to react with the germanium-containing leaching solution to form germanic acid precipitate, and the introduction of any cationic impurity ions can be avoided, thereby improving the purity of germanic acid, and the reaction can be carried out under the condition of pH value of 6 to 7. Before the reaction, there is no need to adjust the pH value of the reaction system or the range of the pH value of the reaction system that needs to be adjusted is greatly reduced, thereby saving raw materials, simplifying the process, and greatly reducing the corrosiveness to the equipment, which is conducive to promotion and industrialization.

[0030] In step 1, a plate filter press is used to separate the reactants of germanium ash and alkali solution into liquid and solid. The main reaction of germanium during the leaching process is as follows:

[0031] GeO2+2OH - =GeO3 2- +H2O

[0032] Ge+2OH - +H2O=GeO3 2- +2H2

[0033] In step 2, the main reactions during the germanium precipitation process are as follows:

[0034] GeO3 2- +CO2+H2O=H2GeO3↓+CO3 2-

[0035] Preferably, in step 1, the reaction of the germanium-containing soot and the alkali solution further includes a sand grinding process, and after the germanium-containing soot and the alkali solution are mixed, the mixture of the germanium-containing soot and the alkali solution is sand ground.

[0036] The inventors have found through research that sand milling and alkali leaching have two major promoting effects on the reaction. On the one hand, it can continuously refine the particles, so that the encapsulated germanium and dense germanium particles are dissociated, thereby exposing a new reaction surface, strengthening the leaching of germanium and enhancing the reaction kinetics; on the other hand, the grinding medium generates a large amount of heat under high-speed rotation, so that the reaction is carried out at a higher temperature, improving the reaction kinetics; the combination of the two can increase the leaching rate of germanium and shorten the leaching time. The inherent advantages of sand milling can increase the leaching rate of germanium under low alkali concentration conditions. Under low alkali concentrations, most of the metal impurities Zn, Pb, Fe, and Si will not be leached. The theoretical leaching pH value of most metal impurities must reach 12, or even above 14 before they can be leached by alkali solution. Under low-alkali conditions, germanium is selectively leached while other impurity elements cannot be leached, thereby improving the purity of germanium in the leachate. Combined with the subsequent CO2 gas precipitation of germanium, germanic acid precipitation can be obtained under weak alkaline conditions without adjusting the pH value of the reaction system, simplifying the process and saving costs; it can also avoid the introduction of any cationic impurity ions, further improving the purity of germanic acid.

[0037] More preferably, the sand milling speed is 600-2000 rpm; the sand milling time is 1-6 hours; and the sand milling medium is zirconia balls.

[0038] In practical applications, the sand mill speed can be adjusted according to actual needs. The inventors have found through research that if the sand mill speed is too high, it will lead to greater ball wear and more impurity dissolution; if the sand mill speed is too low, the material will not be refined and activated enough, which may easily lead to a low germanium leaching rate. Therefore, the inventors propose that the preferred range of the sand mill speed is 600-2000rpm; further preferably, the sand mill speed is 800-1500rpm.

[0039] In the sand grinding process, the commonly used sand grinding media are zirconium oxide and alumina balls, but the alumina material is not resistant to alkaline solutions, so zirconium oxide balls are used in the sand grinding process.

[0040] Preferably, in step 1, the liquid-to-solid ratio of the alkali solution and the germanium-containing ash is 1-5:1 L / Kg; more preferably, the liquid-to-solid ratio of the alkali solution and the germanium-containing ash is 2-4:1 L / Kg.

[0041] The inventors have found through research that a too low liquid-solid ratio can easily lead to incomplete germanium leaching, and at the same time cause the slurry A to have high viscosity and be difficult to stir; a too high liquid-solid ratio can easily increase the burden of the filter press, resulting in an increase in the amount of wastewater.

[0042] Preferably, the concentration of the alkali solution is 20-100 g / L.

[0043] In practical applications, if the concentration of the alkali solution is too low, the leaching effect on the germanium element is not ideal. If the concentration of the alkali solution is too high, it is easy to leach other impurity elements in the ash, affecting the purity of the product. In addition, if the concentration of the alkali solution is too high, the viscosity of the slurry will increase, which is not conducive to stirring.

[0044] Preferably, the germanium content in the germanium-containing soot is higher than 0.2%.

[0045] Preferably, the alkali solution is any one or both of potassium hydroxide solution and sodium hydroxide solution; more preferably, the alkali solution is sodium hydroxide solution.

[0046] Preferably, in step 2, the flow rate of CO2 is 40 to 120 L / m 3 / min; further preferably, the flow rate of CO2 is 60 to 100 L / m 3 / min.

[0047] In practical applications, the flow rate of CO2 can be adjusted according to actual needs, but the flow rate of CO2 directly affects the recovery rate of germanium. Too low a flow rate of CO2 may lead to incomplete precipitation of germanium; too high a flow rate of CO2 may cause an increase in costs. Therefore, the inventors propose that the preferred range of the flow rate of CO2 is 40 to 120 L / m 3 / min.

[0048] Preferably, in step 2, the reaction temperature of the reaction system is 20 to 40° C.; and the reaction time of the reaction system is 1 to 4 hours.

[0049] Preferably, the mass fraction of germanium in the germanium-containing soot is higher than 0.2%.

[0050] In a second aspect, a germanic acid is prepared by the above preparation method.

[0051] In order to make the technical problems, technical solutions and technical advantages to be solved by the present invention more clear, they will be described in detail below with reference to specific examples, but the protection scope of the present invention is not limited to the following specific embodiments.

[0052] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0053] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0054] Embodiment 1:

[0055] The germanium fly ash used as raw material is produced by the side-blown furnace in the secondary lead smelting process, and its composition is shown in the following table:

[0056] element Zn Pb Fe Sn Ge Ca Sb As Si Cu content / % 45.52 20.3 19.6 4.83 2.99 2.01 1.25 0.84 0.81 0.62

[0057] The alkali used in the process is analytical grade and the CO2 is high-purity bottled.

[0058] A method for preparing germanic acid comprises the following steps:

[0059] Step 1, take 1 kg of germanium-containing ash in a beaker, pour 2 L of NaOH solution with a concentration of 50 g / L at a liquid-solid ratio of 2:1, stir evenly to obtain slurry A, then add slurry A to a sand mill, start sand milling and alkali leaching, wherein the sand mill speed is 1000 rpm, the sand milling time is 2 h, and after stopping, the solid-liquid separation of the sand milled slurry A is obtained to obtain a leachate and a leach residue.

[0060] The contents of each element in the leachate are: Zn 0.32g / L, Pb 0.28g / L, Fe 0.03g / L, Sn 0.11g / L, Sb 0.07g / L. The calculation results show that the leaching rate of Zn is 0.14%, the leaching rate of Pb is 0.28%, the leaching rate of Fe is 0.03%, the leaching rate of Sn is 0.46%, and the leaching rate of Sb is 1.11%.

[0061] The obtained leached residue was washed with water and then dried. The weight of the leached residue was weighed to be 0.95 kg. The germanium content in the leached residue was 0.31%. It can be seen that the leaching rate of germanium reached 90.15%.

[0062] Step 2: Pour the leaching solution into a round-bottom beaker and introduce CO2 gas at a flow rate of 50 L / m 3 / min, reaction temperature was 30°C, and ventilation was stopped after 2h of reaction to obtain slurry B. Slurry B was separated into solid and liquid, and the precipitated material obtained was germanic acid, which weighed 45.3g. Analysis showed that the germanium content was 58.17%, and the direct yield of germanium in the whole process was 88.13%.

[0063] Embodiment 2:

[0064] The raw materials used are the same as in Example 1.

[0065] A method for preparing germanic acid comprises the following steps:

[0066] Step 1, take 1 kg of germanium-containing ash in a beaker, pour 1 L of NaOH solution with a concentration of 20 g / L at a liquid-solid ratio of 1:1, stir evenly to obtain slurry A, then add slurry A to a sand mill, start sand milling and alkali leaching, wherein the sand mill speed is 600 rpm, the sand milling time is 1 hour, and after stopping, the solid-liquid separation of the sand milled slurry A is obtained to obtain a leachate and a leach residue.

[0067] The contents of each element in the leachate are Zn0.46g / L, Pb0.30g / L, Fe0.05g / L, Sn0.18g / L, and Sb0.09g / L. Calculation shows that the leaching rate of Zn is 0.20%, the leaching rate of Pb is 0.30%, the leaching rate of Fe is 0.05%, the leaching rate of Sn is 0.75%, and the leaching rate of Sb is 0.14%.

[0068] The obtained leached residue was washed with water and then dried. The weight of the leached residue was weighed to be 0.96 kg. The germanium content in the leached residue was 0.44%. It can be seen that the leaching rate of germanium reached 85.87%.

[0069] Step 2: Pour the leaching solution into a round-bottom beaker and introduce CO2 gas at a flow rate of 40 L / m 3 / min, reaction temperature was 20°C, and ventilation was stopped after 1h of reaction to obtain slurry B. Slurry B was separated into solid and liquid, and the precipitated material obtained was germanic acid, which weighed 42.09g. The germanium content was 59.16% and the direct yield of germanium in the whole process was 83.28%.

[0070] Embodiment 3:

[0071] The raw materials used are the same as in Example 1.

[0072] A method for preparing germanic acid comprises the following steps:

[0073] Step 1, take 1 kg of germanium-containing ash in a beaker, pour 5 L of NaOH solution with a concentration of 100 g / L at a liquid-solid ratio of 5:1, stir evenly to obtain slurry A, then add slurry A to a sand mill, start sand milling and alkali leaching, wherein the sand mill speed is 2000 rpm, the sand milling time is 6 hours, and after stopping, the solid-liquid separation of the sand milled slurry A is obtained to obtain a leachate and a leach residue.

[0074] The contents of each element in the leachate are Zn0.14g / L, Pb0.10g / L, Fe0.02g / L, Sn0.14g / L, Sb0.06g / L. Calculation shows that the leaching rate of Zn is 0.06%, the leaching rate of Pb is 0.10%, the leaching rate of Fe is 0.02%, the leaching rate of Sn is 0.58%, and the leaching rate of Sb is 4.8%.

[0075] The obtained leached residue was washed with water and then dried. The weight of the leached residue was weighed to be 0.87 kg. The germanium content in the leached residue was 0.20%. It can be seen that the leaching rate of germanium reached 94.18%.

[0076] Step 2: Pour the leaching solution into a round-bottom beaker and introduce CO2 gas at a flow rate of 120 L / m 3 / min, reaction temperature was 40°C, ventilation was stopped after 4h reaction, and slurry B was obtained. Slurry B was separated into solid and liquid, and the precipitated material obtained was germanic acid, which weighed 47.90g. Analysis showed that the germanium content was 57.88%, and the direct yield of germanium in the whole process was 92.73%.

[0077] Embodiment 4:

[0078] The raw materials used are the same as in Example 1.

[0079] A method for preparing germanic acid comprises the following steps:

[0080] Step 1, take 1 kg of germanium-containing fly ash in a beaker, pour 2 L of NaOH solution with a concentration of 50 g / L at a liquid-to-solid ratio of 2:1, stir evenly to obtain slurry A, stir for 2 hours to separate the solid and liquid, and obtain leachate and leach residue.

[0081] The content of each element in the leachate is Zn0.06g / L, Pb0.09g / L, Fe0.02g / L, Sn0.02g / L, Sb0.04g / L. Calculation shows that the leaching rate of Zn is 0.03%, the leaching rate of Pb is 0.09%, the leaching rate of Fe is 0.02%, the leaching rate of Sn is 0.08%, and the leaching rate of Sb is 8%.

[0082] The obtained leached residue was washed with water and then dried. The weight of the leached residue was weighed to be 0.97 kg. The germanium content in the leached residue was 2.43%. It can be seen that the leaching rate of germanium reached 21.17%.

[0083] Step 2: Pour the leaching solution into a round-bottom beaker and introduce CO2 gas at a flow rate of 50 L / m 3 / min, reaction temperature was 30°C, and ventilation was stopped after 2h of reaction to obtain slurry B. Slurry B was separated into solid and liquid, and the precipitated material obtained was germanic acid, which weighed 9.76g. The germanium content was 59.04% and the direct yield of germanium in the whole process was calculated to be 19.27%.

[0084] Embodiment 5:

[0085] The germanium ash used as raw material is produced by the rotary kiln during the zinc concentrate smelting process. Its composition is shown in the following table:

[0086] element Zn Pb Fe Cl Si Ge As content / % 49.10 14.29 6.18 2.72 1.66 1.41 0.38

[0087] The alkali used in the process is analytical grade and the CO2 is high-purity bottled.

[0088] A method for preparing germanic acid comprises the following steps:

[0089] Step 1, take 1 kg of germanium-containing ash in a beaker, pour 2 L of NaOH solution with a concentration of 50 g / L at a liquid-solid ratio of 2:1, stir evenly to obtain slurry A, then add slurry A to a sand mill, start sand milling and alkali leaching, wherein the sand mill speed is 1000 rpm, the sand milling time is 2 h, and after stopping, the solid-liquid separation of the sand milled slurry A is obtained to obtain a leachate and a leach residue.

[0090] The contents of each element in the leachate are Zn0.41g / L, Pb0.20g / L, Fe0.02g / L, As0.07g / L, and Si0.04g / L. Calculation shows that the leaching rate of Zn is 0.16%, the leaching rate of Pb is 0.27%, the leaching rate of Fe is 0.06%, the leaching rate of As is 3.6%, and the leaching rate of Si is 0.48%.

[0091] The obtained leached residue was washed with water and then dried. The weight of the leached residue was weighed to be 0.97 kg. The germanium content in the leached residue was 0.16%. It can be seen that the leaching rate of germanium reached 89.00%.

[0092] Step 2: Pour the leaching solution into a round-bottom beaker and introduce CO2 gas at a flow rate of 50 L / m 3 / min, reaction temperature was 30°C, and ventilation was stopped after 2h of reaction to obtain slurry B. Slurry B was separated into solid and liquid, and the precipitated material obtained was germanic acid, which weighed 21.19g. Analysis showed that the germanium content was 58.14%, and the direct yield of germanium in the whole process was 87.37%.

[0093] It can be seen from the content of impurity elements in the leachate in Examples 1 to 5 that under low-alkali conditions, the leaching rate of impurity elements is very low and almost negligible, which further proves that the preparation method provided by the present invention can selectively leach germanium elements and obtain high-purity germanic acid products without the need for impurity removal processes.

[0094] By testing the germanium content of the leached residue, it can be calculated that the leaching rate of germanium in the leachate obtained in step 1 in Example 1 is 90.15%, and the leaching rate of germanium obtained in step 1 in Example 4 is 21.17%. Comparison between the two shows that the sand grinding process combined with a low concentration of alkali solution can greatly improve the leaching rate of the germanium element, while the leaching rate of the impurity elements is still maintained at a very low level, further proving the excellent performance of the preparation method provided by the present invention, which does not require impurity removal, has a high purity of the germanic acid product, and has a simple process.

[0095] Figure 1 is the XRD test pattern of germanic acid obtained in Example 3, Figure 1 It can be seen intuitively that the germanic acid prepared in Example 3 has high purity and no other impurity peaks.

[0096] Figure 2 is the SEM image of germanic acid obtained in Example 3, Figure 2 It can be seen that the prepared germanic acid is in a flake-like aggregate state, with relatively consistent particle morphology and particle size, good uniformity, which conforms to the characteristics of gas-liquid precipitation reaction and is a manifestation of easy control and homogenization of the reaction.

[0097] Figure 3 is the XRD pattern of germanic acid obtained in Example 5, Figure 3 It can be seen that germanic acid has high purity and basically no other impurity peaks. Figure 1 and Figure 3 It can be seen that the crystallinity of the germanic acid prepared in Example 5 is poor. Affected by the content of germanium in the raw materials, the concentration of germanium in the leaching solution of step 1 in Example 5 is low, resulting in insufficient germanium in the growth process of the germanic acid particles to allow the germanic acid particles to grow completely, resulting in slightly poor crystallinity and a coarse XRD baseline.

[0098] The embodiments described above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing germanic acid, characterized in that: The steps include: Step 1, mixing germanium-containing soot and alkali solution for a certain period of time and then separating the solid and liquid to obtain germanium-containing leaching solution and leaching residue; Step 2, continuously introducing CO2 into the germanium-containing leaching solution to obtain slurry B, and solid-liquid separation of slurry B to obtain a precipitated material, namely germanic acid.

2. The method for preparing germanic acid according to claim 1, characterized in that: In step 1, the reaction of the germanium-containing soot and the alkali solution also includes a sand grinding process, in which the mixture of the germanium-containing soot and the alkali solution is sand ground after the germanium-containing soot and the alkali solution are mixed.

3. The method for preparing germanic acid according to claim 2, characterized in that: The sand milling speed is 600-2000 rpm; the sand milling time is 1-6 hours; and the sand milling medium is zirconia balls.

4. The method for preparing germanic acid according to claim 1, characterized in that: In step 1, the liquid-solid ratio of the alkali solution and the germanium-containing ash is 1-5:1 L / Kg; the concentration of the alkali solution is 20-100 g / L.

5. The method for preparing germanic acid according to claim 1 or 4, characterized in that: The alkali solution is any one or both of potassium hydroxide solution and sodium hydroxide solution.

6. The method for preparing germanic acid according to claim 1, characterized in that: In step 2, the flow rate of CO2 is 40-120 L / m 3 / min.

7. The method for preparing germanic acid according to claim 1 or 6, characterized in that: In step 2, the reaction temperature of the reaction system is 20 to 40° C.; the reaction time of the reaction system is 1 to 4 hours.

8. The method for preparing germanic acid according to claim 1, characterized in that: The mass fraction of germanium in the germanium-containing soot is higher than 0.2%.

9. A germanic acid, characterized in that The method is prepared according to any one of claims 1 to 8.

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