Method for producing chloride-based electrolyte for electrolytic refining

Abstract

The present invention relates to a method for producing a chloride-based electrolyte for electrolytic refining, the method comprising the steps of: a) preparing a molten salt comprising a melt of an eutectic mixture and copper chloride (CuClx), wherein x is an integer of 1 or 2; and b) producing a metal chloride by reacting the molten salt with a metal (M) source.

Description

Method for manufacturing chloride-based electrolyte for electrolytic refining

[0001] Research related to this patent was conducted with the support of the Korea Institute of Industrial Technology Planning and Evaluation (Research Project Name: Material and Component Technology Development Project, Project Name: Development of High-Purity Smelting Technology for Ti Metal Materialization without Emission of Toxic Fluorine Gas, Project Identification Number: 1415186061) under the auspices of the Ministry of Trade, Industry and Energy.

[0002] The present invention relates to a method for producing a chloride-based electrolyte for electrolytic refining.

[0003] Titanium (Ti) has high specific strength and its mechanical properties do not change even at high temperatures of 400 to 500°C, so its use is increasing in industries that require lightweight metals, such as automotive and aerospace.

[0004] Currently, the most commonly used method for refining titanium (Ti) is the Kroll method, which involves reducing a titanium tetrachloride (TiCl4) precursor with sodium (Na), magnesium (Mg), etc. to obtain titanium (Ti). In this process, electrolysis and electrolytic processes are performed to improve the purity of titanium (Ti). However, the titanium tetrachloride (TiCl4) precursor has a relatively low melting point and boiling point, which reduces the efficiency of refining through the electrolytic and electrolytic processes.

[0005] To improve the above problems, technology is being studied to replace the titanium tetrachloride (TiCl4) precursor with low-chloride titanium, such as titanium chloride (TiCl2), which has a relatively high melting point and boiling point. However, even this leads to problems such as increased process complexity, emission of environmental pollutants during the process stage, and decreased final yield.

[0006] The purpose of the present invention is to provide a method for producing a chloride-based electrolyte for electrolytic refining.

[0007] The present invention comprises a) a eutectic mixture and copper chloride (CuCl) x) a step of preparing a molten salt containing a molten substance of a metal (M), wherein x is an integer of 1 or 2; and b) a step of reacting the molten salt with a metal (M) source to produce a metal chloride.

[0008] The above metal chloride can satisfy the following chemical formula 1.

[0009] (Chemical formula 1) MCl x

[0010] (In the above chemical formula 1, M is any one of Ti, Zr, Hf, V, Nb, and Ta, and x is an integer from 1 to 5)

[0011] The above metal (M) source may include titanium (Ti) powder.

[0012] The average particle diameter of the above titanium powder may be 0.5 to 3.0 mm.

[0013] The above metal chloride may include titanium chloride (TiCl2).

[0014] The above copper chloride may include CuCl.

[0015] The above eutectic mixture may include two or more mixtures selected from the group consisting of NaCl, CaCl2, MgCl2, BaCl2, KCl, and LiCl.

[0016] The molar ratio of the copper chloride in the molten salt may be 1.0 to 26.0 mol% of the eutectic mixture.

[0017] In the above step b), the production of metal chloride is carried out by adding copper chloride (CuCl x ) and the solid-liquid reaction of the metal (M) source.

[0018] The above solid-liquid reaction can be carried out with stirring.

[0019] In step b), the solid-liquid reaction can be performed at a temperature 100 to 150°C higher than the eutectic point of the eutectic mixture.

[0020] In the above solid-liquid reaction, metallic copper (Cu) is produced, and a step of separating the metallic copper from the eutectic mixture and the metal chloride may be further included.

[0021] The above eutectic composition includes NaCl and CaCl2, the copper chloride includes CuCl, the metal (M) source includes titanium (Ti) powder, and the reaction temperature of the molten salt and the titanium (Ti) powder can be 570 to 730°C.

[0022] The amount of the titanium (Ti) powder used in the above reaction may be 1.05 to 1.15 times the stoichiometric ratio (ratio=1.00). Here, the stoichiometric ratio (ratio=1.00) is 0.5 moles of titanium (Ti) per mole of chlorine (Cl) in copper chloride (CuCl).

[0023] The above chloride-based electrolyte for electrolytic refining can be used for the production of titanium (Ti) produced through electrolytic refining using the above titanium chloride (TiCl2).

[0024] According to the present invention, a method for producing a chloride-based electrolyte for electrolytic refining is provided.

[0025] Figure 1 is a diagram illustrating a method for manufacturing a chloride-based electrolyte for electrolytic refining according to one embodiment of the present invention.

[0026] Figure 2 is a flowchart showing a method for manufacturing a chloride-based electrolyte for electrolytic refining according to one embodiment of the present invention.

[0027] Figure 3 shows the change in concentration of titanium chloride (TiCl2) according to the change in reaction temperature.

[0028] Figure 4 shows the change in concentration of unreacted titanium (Ti) according to the change in reaction temperature.

[0029] Figure 5 shows the content of copper (Cu) in the electrolyte according to changes in reaction temperature.

[0030] Figure 6 shows the change in concentration of titanium chloride (TiCl2) according to the change in the addition ratio of titanium (Ti) powder.

[0031] Figure 7 shows the change in concentration of unreacted titanium (Ti) according to the change in the addition ratio of titanium (Ti) powder.

[0032] Figure 8 shows the content of copper (Cu) in the electrolyte according to the change in the addition ratio of titanium (Ti) powder.

[0033] The present invention will be described in more detail with reference to the drawings below.

[0034] The attached drawings are merely examples intended to more specifically illustrate the technical concepts of the present invention, and therefore, the scope of the present invention is not limited to the attached drawings. Furthermore, the attached drawings may exaggerate the size and spacing of components to illustrate the relationships between components.

[0035] The present invention relates to a method for producing a chloride-based electrolyte for electrolytic refining, comprising: a eutectic mixture and copper chloride (CuCl x ) is prepared, and a method for producing a chloride-based electrolyte for electrorefining is provided, which produces a metal chloride through a solid-liquid reaction between the molten salt and a metal (M) source.

[0036] In the following description, the eutectic mixture (or eutectic composition) is NaCl-CaCl2, which is copper chloride (CuCl x ) is mainly explained by exemplifying CuCl, the metal (M) source is titanium (Ti) powder, and the chloride metal is titanium chloride (TiCl2), but is not limited thereto.

[0037] A eutectic mixture is formed at the eutectic point, the lowest melting point in a system where two or more elements are uniformly mixed. It is a compound with a melting point lower than the intrinsic melting point of the elements in the system. Therefore, the composition ratio for forming a eutectic mixture can be determined or selected using phase diagrams, etc., depending on the components.

[0038] The eutectic mixture may be a molten mixture of two or more metal chlorides selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, and Ba.

[0039] The eutectic mixture may be a mixture of two or more selected from the group consisting of NaCl, CaCl2, MgCl2, BaCl2, KCl, and LiCl, but is not limited thereto. Specifically, the eutectic mixture may be any one of a binary system of NaCl and CaCl2 mixed together, NaCl-CaCl2, a binary system of CaCl2 and KCl mixed together, CaCl2-KCl, a binary system of LiCl and KCl mixed together, LiCl-KCl, and a ternary system of LiCl-KCl-NaCl, a binary system of LiCl, KCl, and NaCl mixed together, LiCl-KCl-CaCl2.

[0040] Copper chloride (CuCl) x ) may use CuCl, but is not limited thereto. In other embodiments, CuCl2 may be used or a mixture of CuCl and CuCl2 may be used.

[0041] Titanium (Ti) can be used as the metal for synthesizing metal (M) chloride, and in other embodiments, any one of Zr, Hf, V, Nb, and Ta can be used.

[0042] Titanium (Ti) powder is used as a metal (M) source for TiCl2 synthesis, but is not limited thereto.

[0043] When titanium (Ti) powder is used as a metal (M) source, the average particle size may be 0.5 to 3.0 mm. If the titanium (Ti) powder is less than 0.5 mm, the time and cost required to reduce the particle size of the titanium (Ti) powder increase, and the synthesis process may become complicated, which may reduce productivity. Conversely, if the particle size exceeds 3.0 mm, it is difficult to uniformly mix the molten salt and titanium powder, and the yield of titanium chloride (TiCl2), the final product, may decrease during the reaction. Specifically, the titanium (Ti) powder may have an average particle size of 0.5 to 3.0 mm, 1.0 to 2.5 mm, and 1.5 to 2.0 mm.

[0044] The metal chloride may be, but is not limited to, titanium chloride (TiCl2). In another embodiment, the metal chloride is ZrCl. x , HfCl x , VCl x , NbCl x and TaCl x where x is an integer from 1 to 5. In another embodiment, the metal chloride may be a complex compound such as NaTiCl3 and Na2TiCl4, since titanium (Ti) tends to form complex compounds in eutectic mixtures.

[0045] Hereinafter, a method for manufacturing a chloride-based electrolyte for electrolytic refining according to one embodiment of the present invention will be described.

[0046] FIG. 1 is a schematic diagram illustrating a method for manufacturing a chloride-based electrolyte for electrolytic refining according to an embodiment of the present invention, and FIG. 2 is a flowchart illustrating a method for manufacturing a chloride-based electrolyte for electrolytic refining according to an embodiment of the present invention.

[0047] Referring to Figure 1, in step a), first, a molten salt containing a eutectic mixture and a molten copper chloride is prepared. Specifically, the molten salt can be prepared by adding copper chloride to the eutectic mixture and melting the copper chloride.

[0048] Specifically, the eutectic mixture and copper chloride are introduced into a reaction vessel filled with Ar gas, mixed, and then reacted through heat treatment. Here, the Ar gas filled in the reaction vessel may have an oxygen (O2) content of 100 ppm or less and a water (H2O) content of 1 ppm or less.

[0049] Although not limited thereto, the molar ratio of copper chloride in the molten salt may be 1.0 to 26.0 mol% and 5.0 to 10.0 mol% of the eutectic mixture.

[0050] Heat treatment for melting the eutectic mixture and copper chloride within the reaction vessel can be performed at a temperature of 550°C to 750°C for 2 h to 20 h.

[0051] The reaction vessel may be made of a material that can maintain a predetermined shape even after heat treatment. Furthermore, the reaction vessel may be made of a metal capable of rapidly transferring the reaction heat emitted from the molten salt produced, but is not limited thereto.

[0052] Next, in step b), a molten salt and a metal (M) source are reacted to produce a metal chloride. (S200)

[0053] Specifically, a metal (M) source is added to the molten salt, and stirring is performed to allow the molten salt (specifically, copper chloride) and the metal (M) source to react better. Here, step b) is to add copper chloride (CuCl) to the molten salt. x ) and a metal (M) source through a solid-liquid reaction. Here, the molten salt may be a mixture of copper chloride (CuCl) and a eutectic mixture (NaCl-CaCl2), such as NaCl-CaCl2-CuCl.

[0054] In step b), titanium chloride (TiCl2) is generated through a reaction between copper chloride (CuCl) and titanium (Ti) powder in a molten salt. Here, the reaction temperature for the reaction between copper chloride (CuCl) and titanium (Ti) powder may be 570 to 730°C, 600 to 700°C, and 630 to 670°C.

[0055] The reaction time may be from 30 minutes to 10 hours, from 1 hour to 5 hours, or from 1.5 hours to 2.5 hours. In other embodiments, stirring may be performed during the reaction, or stirring may be performed intermittently.

[0056] b) The amount of titanium (Ti) powder added to the molten salt in step may be 1.05 to 1.15 times, 1.05 to 1.12 times, and 1.06 to 1.12 times the stoichiometric ratio. Here, the stoichiometric ratio is based on 1.00 when there is 0.5 mole of titanium (Ti) per mole of chlorine (Cl) in copper chloride (CuCl).

[0057] Afterwards, in step c), the metallic copper (Cu) produced through the solid-liquid reaction is separated from the eutectic mixture and the metal chloride. (S300)

[0058] After the solid-liquid reaction, when the molten salt is allowed to stand for a certain period of time, the copper with a high specific gravity precipitates at the bottom, and the eutectic mixture (NaCl-CaCl2) and the metal chloride (specifically, titanium chloride) with a relatively low specific gravity are located at the top. Here, the eutectic mixture and the metal chloride located at the top become the chloride-based electrolyte for electrorefining. Titanium (Ti) metal can be obtained by electrorefining the chloride-based electrolyte for electrorefining.

[0059] The copper below may contain unreacted titanium (Ti).

[0060] This difference in specific gravity can be used to separate metallic copper from the eutectic mixture and the metal chloride. In another embodiment, copper can be separated from the eutectic mixture (NaCl-CaCl2) and the metal chloride using a molten salt separator or mesh. Here, the separated metallic copper can be recycled as flakes and powder.

[0061] Hereinafter, the method for producing metal chloride according to the present invention will be described in more detail through specific experimental examples. However, the following experimental examples are merely references for explaining the present invention in detail and are not intended to limit the present invention, which may be implemented in various forms.

[0062] Additionally, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this description is solely for the purpose of effectively describing specific embodiments and is not intended to limit the invention. Furthermore, unless specifically stated in the specification, units for additives represent weight percent.

[0063] [Example 1]

[0064] In a reaction vessel filled with Ar gas, 67.38 g of CaCl2 powder, 32.62 g of NaCl powder and CuCl A molten salt was prepared by heating 18.71 g of powder at 650°C for 1 hour.

[0065] Next, 4.52 g of titanium (Ti) powder with an average particle size of 2 mm was added to the molten salt in the reaction vessel and reacted at a temperature of 650°C. Here, titanium chloride (TiCl2) was manufactured through a process of repeating 2.5 minutes of stirring and 20 or 30 minutes of reaction four times.

[0066] Afterwards, copper (Cu) in a metallic state was separated from the chloride-based electrolyte {eutectic mixture (NaCl-CaCl2) and titanium chloride (TiCl2)} for electrolytic refining in the reaction vessel.

[0067] Example 1: Since the number of moles of titanium (Ti) is 0.5 times the number of moles of chlorine (Cl) in copper chloride (CuCl), the stoichiometric ratio is 1.00.

[0068] [Example 2]

[0069] The same procedure as Example 1 was followed, except that the reaction temperature for producing titanium chloride (TiCl2) was changed to 600°C.

[0070] [Example 3]

[0071] The same procedure as Example 1 was followed except that the reaction temperature for producing titanium chloride (TiCl2) was changed to 700°C.

[0072] [Example 4]

[0073] Stoichiometrically, the same procedure as Example 1 was followed, except that 1.1 times more titanium (Ti) powder was added.

[0074] [Comparative Example 1]

[0075] The same procedure as Example 1 was followed, except that the reaction temperature for producing titanium chloride (TiCl2) was changed to 550°C.

[0076] [Comparative Example 2]

[0077] The same procedure as Example 1 was followed except that the reaction temperature for producing titanium chloride (TiCl2) was changed to 750°C.

[0078] [Comparative Example 3]

[0079] Stoichiometrically, the same procedure as Example 1 was followed, except that 0.75 times the amount of titanium (Ti) powder was added.

[0080] [Comparative Example 4]

[0081] Stoichiometrically, the same procedure as Example 1 was followed, except that 1.2 times the amount of titanium (Ti) powder was added.

[0082] [Comparative Example 5]

[0083] Stoichiometrically, the same procedure as Example 1 was followed, except that 1.3 times more titanium (Ti) powder was added.

[0084] Temperature (℃)Stoichiometric ratioTi powder (g)Example 16501.004.52Example 26001.004.52Example 37001.004.52Example 46501.104.97Comparative Example 15501.004.52Comparative Example 27501.004.52Comparative Example 36500.753.39Comparative Example 46501.205.42Comparative Example 56501.305.87

[0085] [Characteristic Analysis]

[0086] 1) EDS analysis

[0087] To determine the concentration of unreacted titanium (Ti) in copper, the concentration value (weight %) in copper was measured using EDS (Energy Dispersive X-ray Spectroscopy).

[0088] 2) ICP analysis

[0089] The content of copper (Cu) in the electrolyte was measured using ICP (Inductively Coupled Plasma Analysis).

[0090] 3) Hydrogen evolution and titrimetric analysis

[0091] To determine the TiCl2 concentration in the electrolyte, the TiCl2 concentration was measured in terms of the amount of H2 in the electrolyte using hydrogen evolution and titrimetric analysis.

[0092] [Experimental Results]

[0093] Figure 3 shows the change in concentration of titanium chloride (TiCl2) according to the change in reaction temperature, and Figure 4 shows the change in concentration of unreacted titanium (Ti) according to the change in reaction temperature.

[0094] It is shown in Fig. 5, and the content of copper (Cu) in the electrolyte according to the change in reaction temperature is shown.

[0095] Referring to FIGS. 3 to 5, it can be seen that when the reaction temperature is too high, as in Comparative Example 2, the concentration of titanium chloride (TiCl2) decreases and the concentration of unreacted titanium (Ti) in copper increases. In addition, when the reaction temperature is too low, as in Comparative Example 1, the concentration of copper (Cu) in the electrolyte increases.

[0096] Looking at the concentration of titanium chloride (TiCl2) and the concentration of unreacted titanium (Ti) according to temperature, it can be seen that the examples are superior to the comparative examples, and looking at the concentration of copper in the electrolyte, it can be seen that among the examples, Example 1 (reaction temperature 650°C) is superior.

[0097] Figure 6 shows the change in concentration of titanium chloride (TiCl2) according to the change in the addition ratio of titanium (Ti) powder, Figure 7 shows the change in concentration of unreacted titanium (Ti) according to the change in the addition ratio of titanium (Ti) powder, and Figure 8 shows the content of copper (Cu) in the electrolyte according to the change in the addition ratio of titanium (Ti) powder.

[0098] Referring to FIGS. 6 to 8, it can be confirmed that as the addition ratio of titanium (Ti) powder increases at the same reaction temperature (650°C), the concentration of titanium chloride (TiCl2) increases.

[0099] In addition, it can be confirmed that when the addition ratio of titanium (Ti) powder is low, as in Comparative Example 3, the concentration of unreacted titanium (Ti) increases and the content of copper (Cu) in the electrolyte increases.

[0100] That is, it was confirmed that the appropriate ratio of titanium (Ti) powder added for the highest yield of titanium chloride (TiCl2) is the stoichiometric ratio of 1.0 or 1.1, and in particular, when the ratio of titanium (Ti) powder added is 1.1, it can be seen that titanium chloride (TiCl2) of a certain level or higher (yield of 95% or higher) can be obtained with the least amount of unreacted titanium (Ti) in copper.

[0101] Above, one embodiment of the present invention has been described, but a person having ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this is also included within the scope of the rights of the present invention.

Claims

1. a) Eutectic mixture and copper chloride (CuCl) x ) a step of preparing a molten salt containing a melt, wherein x is an integer of 1 or 2; and b) A method for producing a chloride-based electrolyte for electrolytic refining, comprising the step of producing a metal chloride by reacting the molten salt and a metal (M) source.

2. In paragraph 1, The above chloride metal is a method for producing a chloride-based electrolyte for electrolytic refining that satisfies the following chemical formula 1. (Chemical formula 1) MCl x (In the above chemical formula 1, M is any one of Ti, Zr, Hf, V, Nb, and Ta, and x is an integer from 1 to 5) 3. In paragraph 2, The above metal (M) source is a method for producing a chloride-based electrolyte for electrolytic refining containing titanium (Ti) powder.

4. In paragraph 3, A method for producing a chloride-based electrolyte for electrolytic refining, wherein the average particle size of the titanium powder is 0.5 to 3.0 mm.

5. In paragraph 2, The above chloride metal is a method for producing a chloride-based electrolyte for electrolytic refining containing titanium chloride (TiCl2).

6. In paragraph 1, The above copper chloride is a method for producing a chloride-based electrolyte for electrolytic refining containing CuCl.

7. In paragraph 1, A method for producing a chloride-based electrolyte for electrolytic refining, wherein the eutectic mixture comprises two or more mixtures selected from the group consisting of NaCl, CaCl2, MgCl2, BaCl2, KCl and LiCl.

8. In paragraph 1, A method for producing a chloride-based electrolyte for electrolytic refining, wherein the molar ratio of the copper chloride in the molten salt is 1.0 to 26.0 mol% of the eutectic mixture.

9. In paragraph 1, In step b), the production of metal chloride is The above copper chloride (CuCl x ) and a method for producing a chloride-based electrolyte for electrorefining performed through a solid-liquid reaction of the above metal (M) source.

10. In paragraph 9, A method for producing a chloride-based electrolyte for electrorefining, wherein the above solid-liquid reaction is performed with stirring.

11. In paragraph 10, A method for producing a chloride-based electrolyte for electrorefining, wherein the solid-liquid reaction in step b) is performed at a temperature 100 to 150°C higher than the eutectic point of the eutectic mixture.

12. In paragraph 11, In the above solid-liquid reaction, metallic copper (Cu) is produced. A method for producing a chloride-based electrolyte for electrolytic refining, further comprising a step of separating the copper in the metallic state from the eutectic mixture and the chloride metal.

13. In paragraph 12, The above eutectic composition includes NaCl and CaCl2, the copper chloride includes CuCl, and the metal (M) source includes titanium (Ti) powder. A method for producing a chloride-based electrolyte for electrolytic refining, wherein the reaction temperature of the molten salt and the titanium (Ti) powder is 570 to 730°C.

14. In paragraph 13, The amount of titanium (Ti) powder used in the above reaction is, A method for producing a chloride-based electrolyte for electrolytic refining having a stoichiometric ratio (ratio=1.00) of 1.05 to 1.15 times, wherein the stoichiometric ratio (ratio=1.00) is 0.5 moles of titanium (Ti) per mole of chlorine (Cl) in copper chloride (CuCl).

15. In paragraph 14, The above chloride-based electrolyte for electrolytic refining is A method for producing a chloride-based electrolyte for electrolytic refining used for producing titanium (Ti) through electrolytic refining using the above titanium chloride (TiCl2).

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