A process for recovering germanium tetrachloride and hydrogen chloride from a hydrolysis mother liquor of germanium tetrachloride

Abstract

The application discloses a process method for directly recovering germanium tetrachloride and hydrogen chloride from a germanium tetrachloride hydrolysis mother liquor, and specifically comprises the following steps: adding the hydrolysis mother liquor under the condition of 40 DEG C to prepare a high-concentration calcium chloride solution by adjusting the calcium chloride concentration in the solution. The mixed solution is slowly heated to above 70 DEG C for distillation, and the hydrolysis mother liquor is added in volume fraction to collect the distillate, and germanium tetrachloride, high-concentration hydrochloric acid and medium-low-concentration hydrochloric acid solution can be collected in sequence, so that the germanium and chlorine resources in the hydrolysis mother liquor are recovered. After the distillation is completed, the calcium chloride solution is dehydrated to the initial concentration for recycling, and the hydrolysis mother liquor can be continuously added for distillation and recovery of the germanium and hydrogen chloride in the mother liquor. The application solves the problems of a long production process, high alkali consumption in the neutralization process and a large amount of solid waste generated in the production process of the neutralization and sedimentation germanium process. The germanium and hydrogen chloride are directly recovered from the germanium tetrachloride hydrolysis mother liquor, and the production process method is simple and easy to operate.

Description

Technical Field

[0001] This application belongs to the field of hydrometallurgy, specifically relating to a method for recovering germanium tetrachloride and hydrogen chloride from the mother liquor of germanium tetrachloride hydrolysis. Background Technology

[0002] Germanium, as a key rare metal, possesses excellent semiconductor properties, infrared optical properties, and corrosion resistance, making it an indispensable core raw material in high-tech fields such as optical fiber communication and new energy batteries.

[0003] Currently, the traditional neutralization precipitation method is commonly used in the industrial sector for the recovery of germanium from the mother liquor of germanium tetrachloride hydrolysis. First, a large amount of alkaline regulator is added to the mother liquor to adjust the pH of the waste liquid to weak alkalinity. Then, a special germanium precipitant is added to enrich and precipitate the germanium element. After solid-liquid separation through pressure filtration, centrifugation and other means, crude germanium concentrate and high-chloride brine are obtained. The separated germanium concentrate needs to be dried and dehydrated before being returned to the chlorination distillation section to re-prepare germanium tetrachloride, thus achieving the recycling and purification of germanium. The by-product high-chloride brine needs to be concentrated and desalinated by multi-effect evaporation before being discharged. The crystalline salt produced by evaporation and dehydration has a high impurity content and is difficult to utilize as a resource, so it can only be disposed of as industrial solid waste in accordance with regulations. However, this recycling process has many insurmountable drawbacks: 1. The production process is complex, requiring multiple steps such as neutralization and slurry preparation, precipitation and enrichment, solid-liquid separation, filter cake drying, chlorination distillation, and germanium tetrachloride purification. The high frequency of material transfer not only prolongs the production cycle but also increases intermediate losses of germanium resources, reducing overall recycling efficiency; 2. It consumes large amounts of reagents and has high production costs. The acidity of the hydrolysis mother liquor is as high as 10wt%-15wt%, and the neutralization and pH adjustment process requires large amounts of alkaline reagents such as liquid alkali and lime, resulting in high reagent costs. The high proportion of costs, coupled with the addition of precipitants, further increases production input; 3. The neutralization process generates a massive amount of high-chlorine brine, and the evaporation and desalination process is energy-intensive and requires significant equipment investment, while also producing a large amount of crystalline salt solid waste. The harmless treatment of such wastewater is complex and costly, and it is highly likely to cause secondary pollution; 4. The purity and recovery rate of germanium are limited. The neutralization and precipitation process easily introduces impurity ions, resulting in a low grade of germanium concentrate. Subsequent chlorination and distillation purification have a high load, and the multi-process flow causes germanium entrainment losses, making it difficult to achieve efficient recovery of germanium resources. This seriously restricts the green and sustainable development of the high-purity germanium preparation industry.

[0004] Therefore, developing a process for recovering germanium tetrachloride from germanium tetrachloride hydrolysis mother liquor that is efficient, simplifies the recycling process, reduces energy consumption and waste liquid production, and achieves efficient enrichment and high-purity recovery of germanium resources is of great practical significance and application value for improving the resource utilization rate of the germanium industry and reducing production costs. Summary of the Invention

[0005] To address the problems existing in the background art, this application provides a process for directly recovering germanium tetrachloride and hydrogen chloride from the mother liquor of germanium tetrachloride hydrolysis, the process comprising the following steps: S1: Prepare a calcium chloride solution with a concentration ≥45wt%; add hydrolysis mother liquor to the calcium chloride solution to obtain a mixed solution; The concentration of calcium chloride in the mixed solution is ≥28 wt%; S2: Perform fractional distillation on the above mixed solution; The fractional distillation sequentially yields fraction A, fraction B, fraction C, and residual liquid; The volume of fraction A is 5%-10% of the added mother liquor; the volume of fraction B is 5%-15% of the added mother liquor; and the volume of fraction C is 60%-70% of the added mother liquor. S3: The residual liquid in step S2 is concentrated and regenerated until the calcium chloride concentration is ≥45wt% and the residual liquid pH is ≥4. Distillation is completed. Germanium tetrachloride and hydrogen chloride are recovered from the mother liquor of germanium tetrachloride hydrolysis.

[0006] Furthermore, the hydrochloric acid concentration of fraction A in step S2 is above 33 wt%.

[0007] Furthermore, fraction B in step S2 is a hydrochloric acid solution with a concentration of 25 wt% or higher.

[0008] Furthermore, the fraction C in step S2 is a low to medium concentration (<10%) hydrochloric acid solution.

[0009] Furthermore, after step S3, the process includes: S4: After distillation, the temperature is lowered to 50°C and kept warm. Hydrolysis mother liquor is added to the concentrated residue to prepare the calcium chloride concentration of the solution to be above 30 wt%. The above steps can be repeated to continue distilling and recovering germanium and hydrogen chloride from the mother liquor.

[0010] Furthermore, the preparation of the calcium chloride solution in step S1 is carried out at 40°C.

[0011] Furthermore, the fractional distillation in step S2 is carried out by slowly heating to above 70°C.

[0012] Furthermore, the volume ratio of the hydrolysis mother liquor to the calcium chloride solution in S1 is 1:(1.48-5).

[0013] Beneficial effects Compared with existing processes, this application has the following advantages: (1) High purity germanium recovery, and the product can be directly reused. This application adopts a process of direct distillation of mother liquor with high concentration calcium chloride solution, which does not require complicated pretreatment and can efficiently distill out germanium in the form of germanium tetrachloride. By collecting fraction A and fraction B in steps, high purity germanium tetrachloride product can be obtained. The purity meets the production requirements and can be directly used to prepare high purity germanium dioxide. At the same time, the high concentration hydrochloric acid produced by the by-product can be directly reused in the germanium concentrate chlorination distillation section to realize closed-loop material reuse and save the complicated process of repurifying germanium concentrate and re-preparing hydrochloric acid.

[0014] (2) Eliminating the neutralization process saves costs. The mother liquor of germanium tetrachloride hydrolysis has a low impurity content. The fraction C collected by the process of this application has an extremely low impurity content and can be directly used as an acid absorber in the hydrochloric acid evaporation system. There is no need to add liquid alkali or other alkaline regulators for neutralization treatment throughout the process, which avoids the problem of large alkali consumption caused by the neutralization of high acidity mother liquor in traditional processes, effectively reduces the cost of auxiliary material procurement and addition, and reduces production input.

[0015] (3) No high-chlorine wastewater or solid waste is generated. The process of this application can directly and simultaneously recover germanium and chlorine elements in the mother liquor. No high-chlorine brine is generated throughout the process, and there is no crystallized salt solid waste by-product. This solves the problems of high energy consumption for high-chlorine brine evaporation and desalination, difficulty in disposing of crystallized salt solid waste, and easy secondary pollution in traditional processes, and greatly reduces the cost of harmless disposal of wastewater and waste residue.

[0016] (4) Waste liquid can be recycled. The calcium chloride solution used in the process can be recycled after dehydration and regeneration treatment. No waste liquid or waste residue is generated throughout the process, thus constructing a closed-loop recycling system and achieving a balance between resource utilization and environmental benefits. Attached Figure Description

[0017] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the process flow of this application. Figure 2 The diagram shows the reagents and results of Example 4 of this application. Detailed Implementation

[0019] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0020] This application has developed a process for directly recovering germanium tetrachloride and hydrogen chloride from the mother liquor of germanium tetrachloride hydrolysis through extensive experiments. During the experiment, it was found that by mixing a calcium chloride solution of a certain concentration with the mother liquor of hydrolysis and distilling it, and by controlling the temperature and adjusting the concentration of the calcium chloride solution, germanium can be distilled out in the form of germanium tetrachloride mixed with hydrogen chloride.

[0021] During the experiment, it was found that the mixed distillation of high-concentration calcium chloride solution could break the azeotropic characteristics of the solution system, allowing germanium tetrachloride and high-concentration hydrogen chloride gas to volatilize together. The volatilization rate of germanium tetrachloride was faster than that of hydrogen chloride gas, and less water was carried over in the early stage of distillation. The high-concentration hydrochloric acid and germanium tetrachloride mixture could be collected first. After condensation and absorption, it could be observed that the collected germanium tetrachloride and hydrochloric acid solutions formed obvious stratification, thus achieving the separation of germanium and chlorine in the mother liquor.

[0022] During the experiment, it was also found that after collecting a certain volume of germanium tetrachloride hydrochloric acid mixed solution, the germanium content in the distillation residue was found to be less than 1 ppm, indicating that the method proposed in this application can achieve complete separation of germanium and chlorine. The experiment used a multi-stage collection method to collect the fractions, which separately collected germanium tetrachloride, high-concentration hydrochloric acid, and medium-to-low-concentration hydrochloric acid. After distillation, the calcium chloride solution was dehydrated and regenerated to its initial concentration, and the mother liquor from hydrolysis was added for further distillation to recover germanium and hydrogen chloride. The collected germanium tetrachloride had high purity and was used to prepare high-purity germanium dioxide after rectification and hydrolysis. The high-concentration hydrochloric acid can be used to recover acid in the chlorination distillation process of germanium concentrate, while the medium-to-low-concentration hydrochloric acid has low impurity content and can be directly used as absorbent acid in the hydrochloric acid recovery system. The entire process generates no wastewater or waste residue, is simple to operate, and uses a conventional chlorination distillation reactor, making it a process method easily implemented in large-scale production.

[0023] Unless otherwise specified, all reagents and materials used in the following examples were purchased from the market.

[0024] Example 1 The main components of the hydrolysis mother liquor provided by a germanium factory are as follows: Ge: 1473 mg / L, HCl: 12.1 wt%, and the auxiliary material is industrial-grade anhydrous calcium chloride with a CaCl2 content of 95 wt%.

[0025] This application provides a method for recovering germanium tetrachloride and hydrogen chloride from a mother liquor of germanium tetrachloride hydrolysis, specifically including the following steps: (1) Prepare 2500ml of 45wt% calcium chloride solution (40℃, ρ≈1.44), add 1690ml of hydrolysis mother liquor, and prepare a mixed solution with 30wt% CaCl2 concentration (ρ≈1.29); (2) The mixed solution obtained in step (1) above is heated to above 70°C and then slowly distilled. The volume of fraction A collected is 160 ml. Hydrochloric acid containing GeCl4 can be collected in fraction A. Germanium tetrachloride settles to the bottom of the collection bottle and forms a clear layer with hydrochloric acid. The concentration of hydrochloric acid is 35.7 wt%. (3) After collecting fraction A, the germanium content in the remaining liquid was found to be 1 ppm. The collection bottle B was then switched, and the volume of fraction B was 200 ml. The hydrochloric acid concentration of fraction B was 26.4 wt%. (4) After collecting fraction B, switch to collection bottle C and continue heating. The volume of fraction C collected is 1305 ml. The residual liquid is concentrated and regenerated until the calcium chloride concentration is above 45 wt%. The distillation is completed. The HCl concentration in fraction C is 3.2 wt%, and the pH of the residual liquid is approximately 5. (5) After distillation, cool down to 50°C and keep warm. You can continue to add hydrolysis mother liquor to the concentrated regeneration residue to prepare the calcium chloride concentration of the solution to 30wt%. Repeat the above steps to continue distillation and recover germanium and hydrogen chloride from the mother liquor.

[0026] In this embodiment, the germanium content in the residual liquid is 1 ppm, and a small amount of germanium enters the tail gas. It is absorbed by liquid alkali, and the germanium recovery rate is >99%. The pH of the residual liquid is ≈5, and a small amount of HCl gas enters the tail gas tower. The hydrogen chloride recovery rate is >90%.

[0027] Example 2 (1) Using the 2.5L calcium chloride solution after distillation and concentration in Example 1 as raw material, add 2050ml of the above mother liquor water to prepare a calcium chloride solution with a concentration of 28wt% (ρ≈1.27). (2) The above mixed solution was slowly heated to above 70°C and distilled. The volume of fraction A was 150 ml. Hydrochloric acid containing GeCl4 was collected in fraction A. Germanium tetrachloride settled to the bottom of the collection flask and formed a clear stratification with the hydrochloric acid. The concentration of hydrochloric acid was 33.2 wt%. (3) After collecting fraction A, the germanium content in the remaining liquid was found to be 20 ppm. The collection bottle B was then switched, and the volume of fraction B collected was 150 ml. The hydrochloric acid concentration of fraction B was 25.7 wt%. (4) After collecting fraction B, the germanium content in the residual liquid was 1 ppm. The collection bottle C was switched and the heating was continued. The volume of fraction C collected was 1650 ml. The residual liquid was concentrated and regenerated until the calcium chloride concentration was above 45 wt%. The distillation was completed. The HCl concentration in fraction C was 9.1 wt%, and the pH of the residual liquid was ≈5. (5) After distillation, cool down to 50°C and keep warm. You can continue to add hydrolysis mother liquor to the concentrated regeneration residue to prepare the calcium chloride concentration of the solution to 30wt%. Repeat the above steps to continue distillation and recover germanium and hydrogen chloride from the mother liquor.

[0028] In this embodiment, the germanium content in the residual liquid is 1 ppm, the germanium recovery rate is >99%, the calcium chloride concentration is reduced, the germanium tetrachloride volatilization rate is slow, and germanium residue is found in the residual liquid of collected fraction A; the final pH of the residual liquid is 5, the HCl recovery rate is >90%, and a small amount of hydrogen chloride and germanium enter the tail gas absorption liquid.

[0029] Example 3 (1) Using the 2.5L calcium chloride solution after distillation and concentration in Example 2 as raw material, add 1377ml of the above mother liquor water to prepare a calcium chloride solution with a concentration of 32wt% (ρ≈1.30). (2) The above mixed solution was slowly heated to above 70°C and distilled. The volume of fraction A was 100 ml. Hydrochloric acid containing GeCl4 was collected in fraction A. Germanium tetrachloride settled to the bottom of the collection flask and formed a clear stratification with hydrochloric acid. The concentration of hydrochloric acid was 36.2 wt%. (3) After collecting fraction A, the germanium content in the remaining liquid was found to be less than 1 ppm. The collection bottle B was then switched, and the volume of fraction B was 100 ml. The hydrochloric acid concentration of fraction B was 34.3 wt%. (4) After collecting fraction B, switch to collection bottle C and continue heating. The volume of fraction C collected is 1080 ml. The residual liquid is concentrated and regenerated until the calcium chloride concentration is above 45 wt%. The distillation is completed. The HCl concentration in fraction C is 8.01 wt%, and the pH of the residual liquid is approximately 5. (5) After distillation, cool down to 50°C and keep warm. You can continue to add hydrolysis mother liquor to the concentrated regeneration residue to prepare the calcium chloride concentration of the solution to 30wt%. Repeat the above steps to continue distillation and recover germanium and hydrogen chloride from the mother liquor.

[0030] In this embodiment, after collecting fraction A, the germanium content in the residual liquid is less than 1 ppm, and the germanium recovery rate is >99%; and the hydrochloric acid acidity in fraction B is 34.3 wt%, the final pH of the residual liquid is 5, and the HCl recovery rate is >90%.

[0031] Example 4 Prepare a 45wt% calcium chloride solution for later use; the concentration of the hydrolysis mother liquor is 11wt%, of which the germanium concentration is 1250mg / L, the total germanium metal content is 1.4125g, and the HCl content is 130.515g.

[0032] Following the method in Example 1, 3100 mL of calcium chloride solution and 1130 mL of hydrolysis mother liquor were mixed to prepare a solution for the recovery of germanium tetrachloride and hydrogen chloride.

[0033] The collected fraction A (hydrochloric acid 1) had a concentration of 33.57% and a volume of 220 ml; fraction B (hydrochloric acid 2) had a concentration of 22.12% and a volume of 100 ml; and fraction C (hydrochloric acid 3) had a concentration of 2.14% and a volume of 700 ml.

[0034] Material balance calculations showed that the germanium metal balance rate was 99.11%, as observed in the experimental phenomena. Figure 2 As shown.

[0035] Example 5 The residue (dehydrated calcium chloride solution) after distillation in Example 4 was recycled and concentrated to a concentration of 47 wt%. The concentration of the hydrolysis mother liquor was 11 wt%, containing 1250 mg / L germanium, 1.4375 g of germanium metal, and 132.825 g of HCl.

[0036] 1150 ml of hydrolysis mother liquor (11 wt%) and 2935 ml of calcium chloride solution (47 wt%) were mixed to prepare a mixed solution for the recovery of germanium tetrachloride and hydrogen chloride.

[0037] The collected fraction A (hydrochloric acid 1) had a concentration of 36.10%, a volume of 175 ml, and an HCl content of 66.33375 g; fraction B (hydrochloric acid 2) had a concentration of 23.60%, a volume of 150 ml, and an HCl content of 35.4 g; and fraction C (hydrochloric acid 3) had a concentration of 1.17%, a volume of 600 ml, and an HCl content of 7.02 g.

[0038] According to material balance calculations, the germanium metal balance rate is 98.38%.

[0039] Comparative Example 1 1. The calculation of alkali consumption in the hydrolysis mother liquor of traditional neutralization treatment is as follows: per 1m 3 The neutralization of the hydrolysis mother liquor (10% HCl acidity) requires at least 0.15m. 3 Liquid alkali (50% concentration), for example, a company needs to treat 1000m³ of hydrolysis mother liquor annually. 3 .

[0040] Based on this calculation, the total annual consumption of liquid alkali reaches 150m³. 3 Meanwhile, the solution after neutralization reaction, upon concentration and crystallization, will generate at least 150 tons of sodium chloride crystals (containing a large amount of impurities and solid waste).

[0041] 2. Traditionally, calcium chloride is used to absorb water and then undergo high-temperature desorption to concentrate the hydrogen chloride concentration in the desorption solution in order to recover hydrogen chloride. Currently, there is no precedent for directly distilling calcium chloride solution to recover germanium. This part of the content in this application is for the sake of process completeness. Moreover, this application does not require the use of a desorption tower, and high-concentration hydrochloric acid can be collected directly using an atmospheric pressure reactor.

[0042] This application uses a calcium chloride solution of a certain concentration to directly distill the mother liquor of germanium tetrachloride hydrolysis, while in the comparative example, the hydrochloric acid in the concentrate distillation residue is concentrated to 28%, and the concentrated hydrochloric acid is used as recovered hydrochloric acid for distilling germanium materials.

[0043] 3. In existing technologies, the recovery of germanium using chlorination agents is carried out under concentrated hydrochloric acid distillation conditions, and the hydrochloric acid mass fraction must be above 30% to be effective. Other methods that use magnesium chloride, ferric chloride, or calcium chloride to treat the hydrolysis mother liquor all involve neutralizing with liquid alkali before using the above chlorides as precipitants to leach out germanium, forming a solid germanium-containing material (germanium-containing slag). Germanium tetrachloride can only be collected through chlorination distillation, which is a different process route.

[0044] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A process for directly recovering germanium tetrachloride and hydrogen chloride from the mother liquor of germanium tetrachloride hydrolysis, characterized in that, The process includes the following steps: S1: Prepare a calcium chloride solution with a concentration ≥45wt%; add hydrolysis mother liquor to the calcium chloride solution to obtain a mixed solution; The concentration of calcium chloride in the mixed solution is ≥28 wt%; S2: Perform fractional distillation on the above mixed solution; The fractional distillation sequentially yields fraction A, fraction B, fraction C, and residual liquid; The volume of fraction A is 5%-10% of the added mother liquor; the volume of fraction B is 5%-15% of the added mother liquor; and the volume of fraction C is 60%-70% of the added mother liquor. S3: The residual liquid in step S2 is concentrated and regenerated until the calcium chloride concentration is ≥45wt% and the residual liquid pH is ≥4. Distillation is completed. Germanium tetrachloride and hydrogen chloride are recovered from the mother liquor of germanium tetrachloride hydrolysis.

2. The process method according to claim 1, characterized in that, The hydrochloric acid concentration of fraction A in step S2 is above 33 wt%.

3. The process method according to claim 1, characterized in that, The fraction B in step S2 is a hydrochloric acid solution with a concentration of 25 wt% or higher.

4. The process method according to claim 1, characterized in that, The fraction C in step S2 is a low to medium concentration (<10%) hydrochloric acid solution.

5. The process method according to claim 1, characterized in that, After step S3, the process further includes: S4: After distillation, the temperature is lowered to 50°C and kept warm. Hydrolysis mother liquor is added to the concentrated residue to prepare the calcium chloride concentration of the solution to be above 30wt%. The above steps can be repeated to continue distillation and recover germanium and hydrogen chloride from the mother liquor.

6. The process method according to claim 1, characterized in that, The calcium chloride solution in step S1 is prepared at 40°C.

7. The process method according to claim 1, characterized in that, The fractional distillation in step S2 is carried out by slowly heating to above 70°C.

8. The process method according to claim 1, characterized in that, The volume ratio of the hydrolysis mother liquor to the calcium chloride solution in S1 is 1:(1.48-5).

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