Methods for recovering germanium

Abstract

This technology provides a method for recovering germanium from germanium-containing scrap with a high recovery rate. [Solution] A method for recovering germanium from a germanium-containing raw material, comprising the steps of: adding the germanium-containing raw material to hydrochloric acid; adding hydrogen peroxide dropwise to the hydrochloric acid containing the germanium-containing raw material to prepare a dissolution; heating the dissolution to generate germanium tetrachloride vapor; and collecting the germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution.

Description

Technical Field

[0001] The present invention relates to a method for recovering germanium.

Background Art

[0002] High-purity germanium is widely used as a raw material for electronic device products. In processes such as the production of these electronic device products and raw materials, scraps containing germanium are generated.

[0003] If high-purity germanium can be recovered from these germanium-containing scraps and reused as a raw material, it is extremely preferable from the perspective of efficient resource utilization.

[0004] Patent Document 1 discloses a method for recovering germanium from a substance containing germanium and phosphorus. It is disclosed that the germanium recovery rate of the technique disclosed in Patent Document 1 was 97.3% (in Examples).

[0005] Patent Document 2 discloses a method for recovering germanium tetrachloride. It is disclosed that the recovery rates of germanium tetrachloride in the technique disclosed in Patent Document 2 were 82% (Example 1) and 75% (Example 2), which cannot be said to be a very high recovery rate.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problem to be Solved by the Invention

[0007] As described above, the recovery rates of germanium tetrachloride in the technology disclosed in Patent Document 2 were 82% (Example 1) and 75% (Example 2), which are not particularly high. On the other hand, the recovery rate of germanium in the technology disclosed in Patent Document 1 was 97.3% (Example), which is higher than that of Patent Document 2.

[0008] If high-purity germanium, with minimal contamination from other metallic elements, can be recovered from germanium-containing scrap and reused as a raw material, it would be extremely desirable from the standpoint of efficient resource utilization.

[0009] Therefore, an object of the present invention is to provide a technology for recovering germanium from germanium-containing scrap with a high recovery rate. [Means for solving the problem]

[0010] The inventors of this invention, through diligent research and development, discovered that germanium can be recovered from germanium-containing scrap with a high recovery rate in the form of germanium tetrachloride by the method described below, and thus arrived at the present invention.

[0011] Therefore, the present invention includes (1) the following: (1) A method for recovering germanium from a germanium-containing raw material, The process of adding germanium-containing raw materials to hydrochloric acid, A process to prepare a dissolving solution by adding hydrogen peroxide dropwise to hydrochloric acid into which a germanium-containing raw material has been added. A process of heating the dissolution to generate germanium tetrachloride vapor, A process of collecting germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution. Methods that include... [Effects of the Invention]

[0012] According to the present invention, high-purity germanium with reduced contamination by other metal elements can be recovered in the form of germanium tetrachloride from germanium-containing scrap at a high recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] [Figure 1] Figure 1 is an explanatory diagram showing an outline of the apparatus used for germanium recovery according to the present invention. DETAILED DESCRIPTION OF EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0014] The present invention is described in detail below with reference to specific embodiments. The present invention is not limited to the specific embodiments disclosed below.

[0015] [Method for recovering germanium from germanium-containing raw material] The method according to the present invention is a method for recovering germanium from a germanium-containing raw material, comprising: a step of charging the germanium-containing raw material into hydrochloric acid, a step of dropwise adding hydrogen peroxide solution into the hydrochloric acid charged with the germanium-containing raw material to prepare a dissolution liquid, a step of heating the dissolution liquid to generate germanium tetrachloride vapor, and a step of collecting the germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution.

[0016] [Germanium-containing raw material] In the present invention, germanium is recovered from a germanium-containing raw material. Examples of the germanium-containing raw material may include offcuts, powders, scraps and the like generated in the process of manufacturing products such as germanium-containing targets.

[0017] In a preferred embodiment, the germanium-containing raw material is a raw material containing metallic germanium.

[0018] In a preferred embodiment, the germanium-containing raw material may contain, in addition to germanium, elements such as antimony, tellurium, carbon, aluminum, magnesium, silicon, iron, sulfur, and the like.

[0019] In a preferred embodiment, the germanium-containing raw material can have a germanium content of, for example, 1 wt% or more, 5 wt% or more, 10 wt% or more, 15 wt% or more, or 95 wt% or less, 80 wt% or less.

[0020] [Step of charging germanium-containing raw material into hydrochloric acid] In the present invention, the step of charging the germanium-containing raw material into hydrochloric acid is performed. The charging can be carried out by known means. The charging is sufficient as long as the charged state is achieved as a result, and includes an operation of slow immersion. The charging is sufficient as long as the charged state is achieved as a result, and hydrochloric acid can also be poured after the germanium-containing raw material is placed in a container.

[0021] In a preferred embodiment, the hydrochloric acid into which the germanium-containing raw material is charged can be used at a concentration in the range of, for example, 6 to 36 wt%, preferably 10 to 30 wt%, preferably 15 to 25 wt%, preferably 17 to 19 wt%, or 5 to 20 wt%, preferably 10 to 20 wt%, or 15 to 30 wt%, preferably 15 to 20 wt%.

[0022] In a preferred embodiment, the step of charging is performed while maintaining the hydrochloric acid, into which the germanium-containing raw material is charged, at a temperature in the range of, for example, 20 to 40°C, preferably 20 to 30°C, preferably 20 to 25°C.

[0023] In a preferred embodiment, for the hydrochloric acid into which the germanium-containing raw material is charged, the number of moles of hydrochloric acid can be set to, for example, a range of 1 to 6, preferably a range of 2 to 5, preferably a range of 3 to 4, preferably a range of 3.5 to 3.7, relative to the number of moles of the contained metal amount.

[0024] [Step to prepare the solution by adding hydrogen peroxide dropwise] In this invention, a step is performed to prepare a solution by dropping hydrogen peroxide solution into hydrochloric acid containing a germanium-containing raw material. The dropping can be carried out by known means.

[0025] Since the temperature of the liquid that will be used as the dissolving solution rises when hydrogen peroxide solution is added dropwise, it is preferable to adjust the rate of addition so that the temperature of the liquid that will be used as the dissolving solution is maintained in the range of, for example, 47°C or lower, preferably 40°C or lower, or 30-40°C, preferably 20-30°C.

[0026] In a preferred embodiment, the hydrogen peroxide solution added dropwise may be hydrogen peroxide solution with a concentration of, for example, 1 to 10 wt%, preferably 3 to 7 wt%, or 5 to 6 wt%.

[0027] In a preferred embodiment, the number of moles of hydrogen peroxide added dropwise can be, for example, in the range of 1 to 3, preferably 1.5 to 2.5, or in the range of 1.7 to 2.2, preferably 1.8 to 2.1, relative to the number of moles of the contained metal.

[0028] In this invention, hydrogen peroxide is added dropwise to hydrochloric acid containing the germanium-containing raw material. Hydrogen peroxide is not added to the hydrochloric acid containing the germanium-containing raw material prior to its addition. By providing a separate step for adjusting the solution by dropwise adding hydrogen peroxide to the hydrochloric acid containing the germanium-containing raw material, this invention achieves precise temperature control within the aforementioned temperature range.

[0029] In a preferred embodiment, the prepared solution may have a germanium concentration in the range of, for example, 1-40 g / L, 1-30 g / L, 1-20 g / L, 1-10 g / L, 1-5 g / L, preferably 1.5-4.5 g / L, or 2-4 g / L, preferably 2.5-3.5 g / L. A solution with such a germanium concentration can be heated in a later step to suitably generate germanium tetrachloride vapor.

[0030] [Process of heating the dissolved solution to generate germanium tetrachloride vapor] In the present invention, a step is performed in which a solution prepared by adding hydrogen peroxide dropwise is heated to generate germanium tetrachloride vapor.

[0031] In a preferred embodiment, the step of heating the solution to generate germanium tetrachloride vapor is performed by raising the temperature of the solution to, for example, a range of 83 to 105°C, preferably a range of 85 to 105°C, preferably a range of 90 to 105°C, preferably a range of 95 to 105°C, preferably a range of 99 to 105°C, over a period of 5 to 10 minutes, preferably a range of 6 to 10 minutes, preferably a range of 7 to 10 minutes, and maintaining the aforementioned temperature range.

[0032] [Steps to prepare an aqueous germanium tetrachloride solution by collecting germanium tetrachloride vapor with water] In the present invention, a step is performed to collect germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution.

[0033] In a preferred embodiment, the step of collecting germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution is carried out by collection with water in a collection container. Preferably, pure water is used as the water.

[0034] In a preferred embodiment, the water placed in the collection container may be pure water pre-installed in a volume ratio of, for example, 20-80%, preferably 30-70%, and preferably 40-60%, when the evaporation rate of germanium tetrachloride-containing vapor in the dissolution section is set to 100%. The amount of water can be appropriately selected within a range that does not reach the saturation dissolution amount of germanium tetrachloride, and within a range that the resulting germanium tetrachloride concentration does not become so dilute that it is difficult to handle in subsequent steps.

[0035] [Temperature of the flow path from the container to the collection container] In a preferred embodiment, germanium tetrachloride vapor is guided through a closed channel from a space in a container holding a heated solution into water in a collection container and collected. In this way, the germanium tetrachloride vapor comes into contact with the inner walls of the container and the channel in the channel from the container to the collection container. In a preferred embodiment, in the channel from the container to the collection container, the inner walls or surfaces of the container and the channel in contact with the germanium tetrachloride vapor are maintained at, for example, 83°C or higher, preferably 85°C or higher, or at, for example, in the range of 83 to 105°C, preferably 85 to 105°C.

[0036] In a preferred embodiment, the temperature in the flow path can be maintained using known means. Such means include, for example, covering with insulating material, heating with a heater, and heating with superheated steam. These means can be appropriately adopted by those skilled in the art depending on the degree to which the temperature in the flow path needs to be maintained. The necessity of adopting these means can be appropriately determined by those skilled in the art based on the heat capacity of the flow path, the flow velocity of the germanium tetrachloride vapor, etc.

[0037] [Germanium recovery] According to the present invention, by performing the temperature control described above, germanium can be recovered from germanium-containing raw materials in high yield.

[0038] In a preferred embodiment, the yield of germanium recovery according to the present invention can be, for example, 95% or more, preferably 96% or more, 97% or more, 98% or more, 99% or more, and particularly preferably 100%. This recovery rate can be determined by means described later in the examples.

[0039] The germanium recovery according to the present invention is carried out in the form of an aqueous germanium tetrachloride solution. If desired, germanium can be obtained in the form of metallic germanium by performing a neutralization step and a reduction step on this aqueous germanium tetrachloride solution.

[0040] [Preferred embodiments of the present invention] In preferred embodiments, the present invention includes (1) and the following: (1) A method for recovering germanium from a germanium-containing raw material, The process of adding germanium-containing raw materials to hydrochloric acid, A process to prepare a dissolving solution by adding hydrogen peroxide dropwise to hydrochloric acid into which a germanium-containing raw material has been added. A process of heating the dissolution to generate germanium tetrachloride vapor, A process of collecting germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution. Methods that include... (2) The process of adding germanium-containing raw materials to hydrochloric acid is This process involves adding germanium-containing raw materials to hydrochloric acid at 20-30°C. The process of preparing a dissolving solution involves adding hydrogen peroxide dropwise to hydrochloric acid containing germanium-containing raw materials. The method according to (1), wherein hydrogen peroxide is added dropwise so that the temperature of the dissolving solution is maintained at 47°C or below. (3) In the process of adding germanium-containing raw materials to hydrochloric acid, The number of moles of hydrochloric acid is in the range of 1 to 6 relative to the number of moles of the contained metal. In the process of preparing a dissolving solution by adding hydrogen peroxide dropwise to hydrochloric acid containing germanium-containing raw materials, The method according to (1), wherein the number of moles of hydrogen peroxide added dropwise is in the range of 2 to 3 relative to the number of moles of the contained metal. (4) The method according to (1), wherein the germanium-containing raw material is scrap containing metallic germanium. (5) The process involves heating the solution to generate germanium tetrachloride vapor. The method according to (1), wherein the dissolution is heated to a range of 83 to 110°C within 5 to 10 minutes and the temperature is maintained at 83 to 110°C. (6) The process involves heating the solution to generate germanium tetrachloride vapor. This is done by heating the dissolving solution in the container. The process of collecting germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution is carried out by collection using water in a collection container. The method according to (1), wherein the inner surface of the container in contact with germanium tetrachloride vapor is maintained at 83°C or higher in the flow path from the container to the collection container. (7) A method for producing an aqueous germanium tetrachloride solution by a method comprising the steps of any of the methods described in (1) to (6).

[0041] In a preferred embodiment, the present invention also includes a method for recovering germanium, comprising the above steps; further, a method for producing an aqueous germanium tetrachloride solution, comprising the above steps; and further, a method for producing metallic germanium, comprising the above steps. According to the present invention, by employing the above steps, germanium can be recovered from germanium-containing scrap with a high recovery rate. Therefore, the germanium recovery method employing the above steps, the method for producing an aqueous germanium tetrachloride solution, and the method for producing metallic germanium are all recovery methods or production methods with excellent recovery rates. [Examples]

[0042] The present invention will be described in detail below with reference to examples. The present invention is not limited to the examples illustrated below.

[0043] [Recovery device] Figure 1 shows an explanatory diagram illustrating the overview of the apparatus used for germanium recovery according to the present invention.

[0044] The recovery device 1 shown in Figure 1 comprises a container 3 and a collection container 5. The container 3 and collection container 5 of the recovery device 1 are connected by a connecting pipe 7. Container 3 is a container to which the connecting pipe 7 is connected, and further connected to a supply pipe 91 for blowing air 11. Collection container 5 is a container to which the connecting pipe 7 is connected, and further connected to an exhaust pipe 95 for exhausting 17.

[0045] First, the scrap containing metallic germanium is added to the hydrochloric acid in container 3, and hydrogen peroxide is added dropwise while stirring with a stirring bar (not shown). The hydrogen peroxide is added dropwise through a supply tube (not shown). As the temperature of the solution rises with the addition of hydrogen peroxide, the addition is done slowly to maintain the temperature of the solution within a predetermined range. The added scrap is dissolved using this procedure.

[0046] Next, container 3 is heated in order to heat the dissolved scrap solution 35 inside container 3.

[0047] Thus, the dissolution of the scrap and the subsequent heating of the dissolution solution can be carried out using the same container, but it is also possible to transfer the solution to a different container for heating. When focusing on the dissolution process, container 3 can be called the dissolution container, and when focusing on the heating process, container 3 can be called the heating container. In other words, the dissolution container and the heating container can be the same container, or different containers can be used.

[0048] The germanium tetrachloride vapor generated by heating container 3 evaporates into the space 37 inside container 3, and is then pressurized by the air blown in 11 from supply pipe 91 to become a germanium tetrachloride vapor stream 15, which flows into connecting pipe 7.

[0049] The collection container 5 contains pure water 51, and the tip 73 of the connecting pipe 7 is positioned below the liquid surface of the pure water 51. The germanium tetrachloride vapor stream 15 that flows into the connecting pipe 7 is guided into the pure water 51 inside the collection container 5, where the germanium tetrachloride vapor dissolves into the pure water 51 and is collected as a germanium tetrachloride aqueous solution. The pressure generated in the space 53 due to the inflow of the germanium tetrachloride vapor stream 15 is regulated by exhaust gas 17 from the exhaust pipe 95 connected to the collection container 5.

[0050] In a preferred embodiment, during the heating described above, the solvent 35 in the container 3 is heated to maintain a desired temperature. Such a desired temperature is, for example, in the range of 83 to 105°C.

[0051] In a preferred embodiment, the heating described above is performed such that the container is heated from the lower end 31 to the upper end 33 to maintain a desired temperature. This desired temperature is, for example, 83°C or higher.

[0052] In a preferred embodiment, during the heating described above, the inlet 71 of the connecting tube 7 connected to the container 3 is heated to maintain a desired temperature. Such a desired temperature is, for example, 83°C or higher.

[0053] In a preferred embodiment, during the heating described above, the connecting pipe 7 is heated so that the entire conduit from the container 3 to the collection container 5 is maintained at a desired temperature. Such a desired temperature is, for example, 83°C or higher.

[0054] [Example 1: Example 1, Comparative Example 1] Recovery of germanium from scrap [Example 1] [Raw materials] The raw material used was scrap generated during the manufacturing process of GST-type sputtering targets. This scrap contains germanium.

[0055] [Dissolution] 15 g of scrap was added to a container containing 300 mL of 21 wt% hydrochloric acid, and 45 mL of 30 wt% hydrogen peroxide solution was added dropwise while stirring. These operations were carried out at atmospheric pressure and 25°C. The number of moles of hydrochloric acid corresponds to 3.6 moles for every 1 mole of metal contained in the scrap. The number of moles of hydrogen peroxide corresponds to 2 moles for every 1 mole of metal contained in the scrap. Stirring was performed using a stirring bar at 300 rpm.

[0056] Since adding hydrogen peroxide solution drops generates heat, the addition was carried out over approximately one hour while maintaining a temperature of 44-47°C or lower during the process.

[0057] After the dropwise addition of hydrogen peroxide was complete, stirring was continued for approximately 4 hours until the mixture cooled naturally to room temperature. In this way, a scrap solution was obtained. The stirring was performed using a stirring bar at 300 rpm.

[0058] [distillation] After the dropwise addition was complete, the mixture was stirred for approximately 4 hours, and the scrap solution, which had cooled to room temperature by natural cooling, was then heated.

[0059] The scrap dissolution solution was heated to a temperature of 99-105°C within approximately 10 minutes.

[0060] The heated solution was sealed in a dissolution container, and by blowing air at a rate of 2 L / min near the liquid surface of the solution in the dissolution container, the germanium tetrachloride vapor generated from the solution was guided to a collection container via a connecting pipe.

[0061] The collection container was filled with pure water, and the germanium tetrachloride vapor was introduced into the pure water, cooled, and dissolved in the water. The germanium tetrachloride vapor was collected while the pure water in the collection container was stirred with a stirring bar.

[0062] Subsequently, heating was terminated when the amount of the dissolved solution was reduced to 50 mL or less through distillation. In this way, an aqueous germanium tetrachloride solution was obtained.

[0063] The details of these conditions are summarized in Table 1.

[0064] [Table 1]

[0065] In Table 1, heating time refers to the time the temperature was maintained after reaching 99-105°C. The connecting pipe inlet temperature is the temperature of the inner wall at the portion 71 where the connecting pipe 7 is connected to the container 3 in Figure 1.

[0066] The Ge concentration in the collected liquid obtained after distillation was measured by ICP-OES and found to be 5.1 g / L.

[0067] The Ge yield was calculated using the following formula: Ge yield = (Collection liquid volume L × Collection liquid Ge concentration g / L) / (Amount of scrap material added g × Ge weight ratio wt%) × 100

[0068] [Comparative Example 1] [Dissolution] A scrap dissolving solution for Comparative Example 1 was obtained in the same manner as in Example 1.

[0069] [distillation] The scrap dissolution solution for Comparative Example 1 was heated. The heat was increased so that the scrap dissolution solution reached 94-97°C within approximately 10 minutes.

[0070] Except for the temperature reached by this heating, distillation was carried out in the same manner as in Example 1 to obtain an aqueous germanium tetrachloride solution in a collection container.

[0071] The Ge concentration in the collected liquid obtained after distillation was measured in the same manner as in Example 1, and the Ge concentration in the collected liquid was found to be 4.8 g / L.

[0072] [Results for Example 1 and Comparative Example 1] In the distillation experiment of Example 1, the volume of the collected liquid after distillation increased compared to the volume at the start of distillation, and the volume of the dissolved liquid decreased. The germanium tetrachloride concentration in the obtained dissolved portion was as described above, confirming that the distillation of germanium tetrachloride was proceeding as intended. Furthermore, during the distillation experiment of Example 1, no white deposits were observed on the inner walls of any path from the container used to heat the solution to the connecting tube connected to the container.

[0073] On the other hand, during the distillation of the experiment in Comparative Example 1, a white substance was observed adhering to the inner wall of the container used to heat the solution and to the inner wall of the connecting tube connected to the container. Although analysis was not performed due to the difficulty of recovery in the apparatus structure, the inventors believe that it was probably a portion of the germanium tetrachloride vapor that was cooled by the inner wall of the container, adhered to it, and then hydrolyzed by water vapor to become germanium oxide.

[0074] [Potential contribution to the SDGs] One embodiment of the present invention provides a technology for recovering high-purity germanium from scrap, which could lead to a reduction in the loss of metal raw materials, a limited resource. For this reason, one embodiment of the present invention could contribute to Goal 12 of the United Nations-led Sustainable Development Goals (SDGs), "Ensure sustainable consumption and production patterns." [Industrial applicability]

[0075] This invention provides a technology for recovering germanium from germanium-containing scrap with a high recovery rate. This invention is industrially useful.

Claims

1. A method for recovering germanium from a germanium-containing raw material, The process of adding germanium-containing raw materials to hydrochloric acid, A process to prepare a dissolving solution by adding hydrogen peroxide dropwise to hydrochloric acid into which a germanium-containing raw material has been added. A process of heating the dissolution to generate germanium tetrachloride vapor, A process of collecting germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution. Methods that include...

2. The process of adding germanium-containing raw materials to hydrochloric acid is This process involves adding germanium-containing raw materials to hydrochloric acid at 20-30°C. The process of preparing a dissolving solution involves adding hydrogen peroxide dropwise to hydrochloric acid containing germanium-containing raw materials. The method according to claim 1, wherein hydrogen peroxide solution is added dropwise so that the temperature of the dissolving solution is maintained at 47°C or below.

3. In the process of adding germanium-containing raw materials to hydrochloric acid, The number of moles of hydrochloric acid is in the range of 1 to 6 relative to the number of moles of the contained metal. In the process of preparing a dissolving solution by adding hydrogen peroxide dropwise to hydrochloric acid containing germanium-containing raw materials, The method according to claim 1, wherein the number of moles of hydrogen peroxide added dropwise is in the range of 2 to 3 relative to the number of moles of the contained metal.

4. The method according to claim 1, wherein the germanium-containing raw material is scrap containing metallic germanium.

5. The process involves heating the solution to generate germanium tetrachloride vapor. The method according to claim 1, wherein the dissolving solution is heated to a range of 83 to 110°C within 5 to 10 minutes and the temperature is maintained at 83 to 110°C.

6. The process involves heating the solution to generate germanium tetrachloride vapor. This is done by heating the dissolving solution in the container. The process of collecting germanium tetrachloride vapor with water to prepare an aqueous germanium tetrachloride solution is carried out by collection using water in a collection container. The method according to claim 1, wherein the flow path from the container to the collection container is maintained at 83°C or higher on the inner surface of the container in contact with germanium tetrachloride vapor.

7. A method for producing an aqueous germanium tetrachloride solution by a method comprising the steps of any one of claims 1 to 6.

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