A method of preparing a titanium oxide-carbon electrode by a coating method

Abstract

The application discloses a method for preparing a titanium carbon oxide electrode by coating, and the method comprises the following steps: A. crushing and screening titanium carbon oxide, mixing the titanium carbon oxide with a pore-forming agent and a binder to obtain a mixture, and adding water into the mixture to prepare a slurry; B. coating the slurry on a graphite substrate by using a doctor blade; and C. drying and sintering the coated graphite substrate to obtain the titanium carbon oxide electrode. The application provides a method for preparing a titanium carbon oxide electrode by coating, the titanium carbon oxide electrode is prepared by coating and sintering the mixed slurry on a graphite substrate, the peeling problem of the electrode caused by gas scouring in an electrolysis process is avoided, the loose and porous structure formed by sintering makes the electrode have relatively high dissolving performance, the anode dissolving rate is increased from 50% to more than 80%, and the problem of low dissolving rate of the titanium carbon oxide anode in the electrode process is solved.

Description

Technical Field

[0001] This invention relates to the field of rare metal refining technology, and in particular to a method for preparing titanium dioxide electrodes by coating. Background Technology

[0002] Currently, methods for producing metallic titanium include the magnesium reduction method (Kroll process) and the USTB method. The USTB method utilizes the anodic electrolysis of a soluble solid solution of titanium monoxide / titanium carbide to produce pure titanium. It uses a carbonaceous reducing agent and titanium-containing materials as raw materials, which are then pressed into shape and reduced under high temperature and vacuum to obtain a titanium carbide solid solution (TiC). x O y (x≈0.50, y≈0.50), after being crushed, reshaped, and sintered into electrodes, electrolysis is carried out in a chloride molten salt system containing low-valence titanium ions. During electrolysis, titanium in the solid solution enters the molten salt in the form of ions, and the remaining carbon and oxygen overflow the electrolysis system in the form of CO. Theoretically, no residual carbon is produced at the anode, and pure metallic titanium is deposited on the cathode.

[0003] However, in actual electrolysis, the titanium dioxide electrodes prepared by traditional methods exhibit the following issues during dissolution: First, due to the uneven distribution of microstructural elements in the prepared electrodes, amorphous carbon is generated during electrolysis and adheres to the electrode surface, hindering ion diffusion and reducing the electrode's dissolution efficiency and current efficiency. Second, the gas generated on the anode surface during electrolysis erodes the electrode surface, causing the anode material to peel off into fine particles that sink to the bottom of the electrolytic cell, thereby reducing the anode's utilization rate.

[0004] Therefore, there is a need to improve the existing methods for preparing titanium dioxide electrodes. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for preparing titanium dioxide electrodes by coating, wherein the electrodes prepared by this method are not easy to peel off and have high dissolution efficiency.

[0006] To achieve the above objectives, embodiments of the present invention provide a method for preparing a titanium oxide carbon electrode by coating, the method comprising the following steps:

[0007] A. Crush and screen the titanium oxide, mix it with the pore-forming agent and binder to form a mixture, and add water to the mixture to make a slurry;

[0008] B. Apply the slurry to the graphite substrate using a scraper;

[0009] C. The coated graphite substrate is dried and sintered to obtain a titanium dioxide electrode.

[0010] In some embodiments, the particle size of titanium oxide is 45 μm to 2000 μm.

[0011] In some embodiments, the pore-forming agent includes inorganic salts and polyvinyl alcohol.

[0012] In some implementations, the amount of pore-forming agent accounts for 5% to 30% of the total mixture by weight.

[0013] In some implementations, the binder includes starch or bitumen.

[0014] In some implementations, the amount of water added in step A accounts for 40% to 95% of the total amount of slurry.

[0015] In some embodiments, the graphite matrix is ​​a perforated plate-shaped, cylindrical, or barrel-shaped structure.

[0016] In some embodiments, the coating thickness in step B is 15~30mm.

[0017] In some embodiments, step C, the sintering step, includes:

[0018] Heat to 120℃ and maintain constant temperature for 1 hour;

[0019] Heat to 500℃ and maintain constant temperature for 1 hour;

[0020] Maintain a constant temperature of 950℃ for 1-3 hours.

[0021] In some embodiments, titanium oxide is prepared by carbothermal reduction.

[0022] The present invention has at least the following beneficial technical effects:

[0023] This invention provides a method for preparing titanium dioxide electrodes by coating. The titanium dioxide electrode prepared by coating and sintering a mixed slurry on a graphite substrate avoids the problem of electrode peeling caused by gas erosion during electrolysis. The loose and porous structure formed by sintering gives it relatively high solubility, increasing the anode solubility from 50% to over 80%, thus solving the problem of low solubility of titanium dioxide anodes during electrode preparation. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0025] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0026] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] This invention provides a method for preparing titanium oxide carbon electrodes by coating, the method comprising the following steps:

[0028] A. Crush and screen the titanium oxide, mix it with the pore-forming agent and binder to form a mixture, and add water to the mixture to make a slurry;

[0029] B. Apply the slurry to the graphite substrate using a scraper;

[0030] C. The coated graphite substrate is dried and sintered to obtain a titanium dioxide electrode.

[0031] In some embodiments, the titanium dioxide used in step A has a particle size of 45 μm to 2000 μm, preferably 75 μm to 200 μm, and is prepared by carbothermal reduction. The pore-forming agent is an inorganic salt, polyvinyl alcohol, or other substances that are easily decomposed by heat or volatile under vacuum conditions; the amount of the pore-forming agent accounts for 5% to 30% of the total mixture, and in some preferred embodiments, the proportion is 15% to 25%. Further, the binder is a carbon-chain-containing organic compound such as starch or asphalt, and its proportion accounts for 5% to 30% of the total mixture. The amount of water added in step A accounts for 40% to 95% of the total slurry volume; in some preferred embodiments, the amount of water added accounts for 60% to 80% of the total slurry volume.

[0032] In some embodiments, the graphite substrate in step B is a plate-shaped, cylindrical, or barrel-shaped structure with a rough or perforated surface. The coating thickness during scraping is 0-30 mm, and in some preferred embodiments, the coating thickness is 0-20 mm.

[0033] In some embodiments, step C, the sintering step, includes:

[0034] Heat to around 120℃ and maintain constant temperature for 1 hour; heat to around 500℃ and maintain constant temperature for 1 hour; heat to around 950℃ and maintain constant temperature for 1 to 3 hours.

[0035] Compared to traditional titanium oxide electrodes, the method of this invention has advantages such as no anode peeling and high dissolution efficiency. The pore-forming agent provides an ion channel for the electrolysis process by giving the electrode a loose, porous structure. The binder functions to: 1. create pores; and 2. form a carbon skeleton of sufficient strength after decomposition or volatilization, preventing electrode peeling when gases generated during electrolysis wash over the electrode surface.

[0036] The following uses a practical example to further illustrate the content of this invention.

[0037] Example 1

[0038] Take 60g of titanium dioxide (particle size 45um~2000um), 20g of ammonium chloride, and 20g of starch, and mix them in a three-dimensional mixer for 30 minutes. Add 60g of water and stir to form a slurry. Make holes in a 5mm thick graphite plate, and evenly coat both sides of the graphite plate with the slurry using a scraper. Let it stand in the air for a period of time until the slurry stops flowing, and then perform a second coating. Repeat the above operation until the electrode plate thickness reaches 40mm, then stop scraping. After drying at room temperature for 24 hours, dry it in an oven at 105℃ for 12 hours. Heat the above blank under vacuum or a protective atmosphere at a heating rate of 10℃ / min, and hold it at 150℃, 300℃, and 950℃ for 1 hour respectively, then cool it down and remove it from the furnace to obtain a density of 1.0g / cm³. 3 A titanium dioxide carbon electrode was used as the anode. Electrolysis was performed in an equimolar NaCl-KCl molten salt system. After electrolysis, the anode shape remained intact, and the anode solubility reached 90%.

[0039] Example 2

[0040] Take 70g of titanium dioxide (particle size 75um~200um), 10g of sodium chloride, and 20g of asphalt (60% volatile content) and mix them in a three-dimensional mixer for 30 minutes. Add 70g of water and stir to form a slurry. Make holes in a 5mm thick graphite cylinder and evenly coat both sides of the cylinder with the slurry using a scraper. Let it stand in the air for a period of time until the slurry stops flowing, then apply a second coating. Repeat the above operation until the slurry thickness reaches 15mm, then stop scraping. After drying at room temperature for 24 hours, dry it in an oven at 105℃ for 12 hours. Heat the above blank under vacuum or a protective atmosphere at a heating rate of 5℃ / min, and hold it at 120℃, 350℃, and 900℃ for 1 hour each, then cool it down and remove it from the furnace to obtain a density of 0.9g / cm³. 3A titanium dioxide carbon electrode was used as the anode. Electrolysis was performed in an equimolar NaCl-KCl molten salt system. After electrolysis, the anode shape remained intact, and the anode solubility reached 93%.

[0041] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0042] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0043] The embodiment numbers disclosed in the above embodiments of the present invention are merely for description and do not represent the superiority or inferiority of the embodiments.

[0044] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for preparing a titanium oxide carbon electrode by coating, characterized in that, include: A. The titanium oxide is crushed and sieved, and then mixed with a pore-forming agent and a binder to form a mixture. Water is added to the mixture to prepare a slurry. B. Apply the slurry onto the graphite substrate using a scraper; C. The coated graphite substrate is dried and sintered to obtain a titanium dioxide electrode; The sintering step in step C includes: Heat to 120℃ and maintain constant temperature for 1 hour; Heat to 500℃ and maintain constant temperature for 1 hour; Heat to 950℃ and maintain constant temperature for 1-3 hours; The titanium oxide is prepared by carbothermal reduction.

2. The method for preparing a titanium oxide electrode by coating according to claim 1, characterized in that, The particle size of the titanium dioxide is 45 μm to 2000 μm.

3. The method for preparing a titanium oxide electrode by coating according to claim 1, characterized in that, The pore-forming agent includes inorganic salts and polyvinyl alcohol.

4. The method for preparing a titanium oxide electrode by coating according to claim 1, characterized in that, The amount of the pore-forming agent is 5% to 30% of the total amount of the mixture, by weight percentage.

5. The method for preparing a titanium oxide electrode by coating according to claim 1, characterized in that, The binder includes starch and asphalt.

6. The method for preparing a titanium oxide electrode by coating according to claim 1, characterized in that, The amount of water added in step A accounts for 40% to 95% of the total amount of the slurry.

7. The method for preparing a titanium oxide electrode by coating according to claim 1, characterized in that, The graphite matrix is ​​a hollowed-out plate-shaped, cylindrical, or barrel-shaped structure.

8. The method for preparing a titanium oxide electrode by coating according to claim 1, characterized in that, In step B, the coating thickness is 15~30mm.