Vacuum re-evaporation treatment method for high-chlorine-content titanium sponge

Abstract

The present application relates to the field of titanium sponge production, and particularly relates to a vacuum re-evaporation treatment method of high-chlorine-content titanium sponge. The vacuum re-evaporation treatment method comprises the following key steps: a low-temperature dehydration and degassing stage: placing moisture-absorbed high-chlorine-content titanium sponge material in a vacuum distillation furnace; starting a vacuum system to make and maintain a high vacuum state in the furnace; slowly and controllably increasing the furnace temperature to 100-200 DEG C; under the low-temperature and high-vacuum condition, continuously processing for 10-20 hours; gently removing moisture (H2O) and air adsorbed on the surface and pores of the titanium sponge; a high-temperature deep dechlorination stage: after confirming that the low-temperature dehydration and degassing stage is completed, gradually increasing the furnace temperature to 950-1050 DEG C; maintaining a high vacuum state, and performing distillation processing for 50-80 hours under the high temperature.

Description

Technical Field

[0001] This invention relates to the field of sponge titanium production, and more particularly to a vacuum re-evaporation treatment method for high-chlorine-content sponge titanium. Background Technology

[0002] Titanium sponge is a key raw material in aerospace, high-end chemicals, and medical devices. Its purity and microstructure directly determine the mechanical properties, corrosion resistance, and processing stability of downstream finished products. Therefore, quality control during product storage and pretreatment is particularly critical. Titanium sponge products, which already have a high chlorine content, are at significantly higher risk of moisture absorption during long-term storage in warehouses due to factors such as fluctuating ambient temperature and humidity and gradually decreasing packaging seal. This is because residual chlorine alters the electron distribution on the titanium surface, increasing surface energy and making it easier for water molecules in the air to adhere to the product surface through physical adsorption. Simultaneously, thanks to the porous structure (pore diameters mostly in the micrometer to submicrometer range) formed by the manufacturing process of titanium sponge, water gradually penetrates into the internal pores, ultimately forming a dual adsorption state of "surface water film + pore-retained water."

[0003] More importantly, the moisture adsorption process is accompanied by the simultaneous retention of air: the porous structure of sponge titanium acts like a "miniature gas tank." While water molecules fill the pores, oxygen, nitrogen, and other components in the air are trapped inside, forming a tight contact with the titanium surface. If such moisture-absorbing materials are directly subjected to high-temperature processing (such as vacuum arc furnace melting, electron beam cold bed melting, etc., where the process temperature is usually above 1600℃), the residual air, especially oxygen, will break through the original passivation film on the titanium surface under high temperature conditions, undergoing a violent oxidation reaction with titanium atoms to generate oxides such as TiO2 and Ti2O3. These oxides not only exist in the final product as inclusions, disrupting the uniformity of the titanium material and causing a significant deterioration in its mechanical properties such as strength and elongation, but also form low-melting-point eutectics with other impurity elements during the melting process, causing defects such as surface crusting and internal shrinkage cavities in the ingot, and in severe cases, even leading to the scrapping of the entire batch of products.

[0004] Furthermore, if the high chlorine content is not effectively controlled, it will react with titanium at high temperatures to form volatile chlorides such as TiCl4. These substances not only corrode the refractory materials of the smelting equipment but may also re-condense inside the product during cooling, forming a hidden corrosion source and affecting the long-term stability of the product. Therefore, for sponge titanium products with high chlorine content and a tendency to absorb moisture, there is an urgent need to develop a safe, efficient, and industrially viable pretreatment method. Summary of the Invention

[0005] Purpose of the invention: To provide a more effective vacuum re-evaporation treatment method for high-chlorine-content sponge titanium, the specific purpose of which is described in the detailed implementation section for several substantial technical effects.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The vacuum re-evaporation treatment method for high-chlorine-content sponge titanium is characterized by, The vacuum re-evaporation process includes the following key steps: Low-temperature dehydration and degassing stage: The moisture-absorbing high-chlorine sponge titanium material is placed in a vacuum distillation furnace; the vacuum system is started to bring the furnace into a high vacuum state and maintain it; the furnace temperature is slowly and controllably raised to 100℃-200℃; under these low-temperature and high-vacuum conditions, the process is continued for 10 to 20 hours; the moisture (H2O) and air adsorbed on the surface and in the pores of the sponge titanium are gently removed. High-temperature deep dechlorination stage: After confirming that the low-temperature dehydration and degassing stage is completed, gradually increase the furnace temperature to 950℃-1050℃; maintain a high vacuum state and carry out distillation treatment for 50 to 80 hours at this high temperature.

[0007] A further technical solution of the present invention is that the relatively low temperature of 100℃-200℃ can effectively prevent significant oxidation of titanium, while the high vacuum promotes the evaporation and extraction of moisture and gas.

[0008] A further technical solution of the present invention is that: the high temperature of 950℃-1050℃ significantly increases the volatilization rate and vapor pressure of residual chlorides (mainly MgCl2 and other chloride salts); the high vacuum environment accelerates the migration of these volatile chloride components from the pores and interior of the sponge titanium to the condensation zone and condenses and precipitates, thereby achieving deep removal of the residual and difficult-to-remove Cl⁻ ions after primary distillation.

[0009] The present invention, which adopts the above technical solution, has the following beneficial effects compared with the prior art: high safety: by removing moisture and air at low temperature first, the risk of violent oxidation reaction between titanium and oxygen during subsequent high-temperature treatment is completely avoided.

[0010] High dechlorination efficiency: The high-temperature stage is specifically designed to target the pores and internal chlorides that are difficult to remove after primary distillation, significantly reducing the chloride content of the final sponge titanium product.

[0011] Resource reuse: Effectively dispose of stockpiled high-chlorinated sponge titanium and reduce resource waste.

[0012] Process controllable: The temperature is clearly controlled in stages, making it easy to operate. Attached Figure Description

[0013] To further illustrate the present invention, the following description is provided in conjunction with the accompanying drawings: Figure 1 The flowchart is for the invention. Detailed Implementation

[0014] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0015] Example 1: A vacuum re-evaporation treatment method for high-chlorine-content sponge titanium, characterized in that, The vacuum re-evaporation process includes the following key steps: Low-temperature dehydration and degassing stage: The moisture-absorbing high-chlorine sponge titanium material is placed in a vacuum distillation furnace; the vacuum system is started to bring the furnace into a high vacuum state and maintain it; the furnace temperature is slowly and controllably raised to 100℃-200℃; under these low-temperature and high-vacuum conditions, the process is continued for 10 to 20 hours; the moisture (H2O) and air adsorbed on the surface and in the pores of the sponge titanium are gently removed. High-temperature deep dechlorination stage: After confirming the completion of the low-temperature dehydration and degassing stage, the furnace temperature is gradually increased to 950℃-1050℃; a high vacuum state is maintained, and distillation is carried out continuously at this high temperature for 50 to 80 hours. The substantive technical effects and implementation process of this technical solution, i.e., its basic functions, are as follows: This invention provides a vacuum re-evaporation treatment method for moisture-absorbing high-chlorine sponge titanium. Its core lies in adopting a staged temperature gradient vacuum distillation process to achieve safe dehydration and degassing first, followed by efficient and deep dechlorination.

[0016] The processing method includes the following key steps: Low-temperature dehydration and degassing stage: The moisture-absorbing high-chlorine sponge titanium material is placed in a vacuum distillation furnace.

[0017] Start the vacuum system to achieve and maintain a high vacuum state inside the furnace.

[0018] The furnace temperature is slowly and controllably raised to 100℃-200℃.

[0019] Under these low temperature and high vacuum conditions, the process continues for 10 to 20 hours.

[0020] Mechanism of action: The main purpose of this stage is to gently remove moisture (H2O) and air (mainly O2, N2, etc.) adsorbed on the surface and pores of the sponge titanium. Low temperature can effectively prevent significant oxidation of titanium, while high vacuum promotes the evaporation and removal of moisture and gas.

[0021] High-temperature deep dechlorination stage: After confirming that the low-temperature dehydration and degassing stage is completed, the furnace temperature will be gradually increased to 950℃-1050℃.

[0022] Maintaining a high vacuum, distillation is carried out at this high temperature for 50 to 80 hours.

[0023] Mechanism of action: High temperature significantly increases the volatilization rate and vapor pressure of residual chlorides (mainly MgCl2 and other chloride salts). The high vacuum environment accelerates the migration and condensation of these volatile chloride components from the pores and interior of the sponge titanium to the condensation zone, thereby achieving deep removal of the difficult-to-remove Cl⁻ ions remaining after primary distillation.

[0024] The method described in this invention has the following significant advantages: 1. High safety: By employing a stepped heating strategy, free moisture and pore air in the material are thoroughly removed first in the low-temperature range of 200-300℃, isolating the titanium-oxygen contact conditions from the source. This pretreatment mechanism effectively avoids the safety hazard of a violent exothermic reaction between metallic titanium and residual oxygen during subsequent high-temperature treatment (>1000℃), significantly reducing process risks such as combustion and explosion.

[0025] 2. High dechlorination efficiency: During the critical high-temperature stage of 850-950℃, the thermal energy is specifically applied to the stubborn chlorides remaining after primary distillation. By extending the holding time and optimizing the mass transfer path, this method can efficiently decompose the MgCl2·nH2O complex enriched in grain boundary gaps and closed pores of the sponge, reducing the chloride ion residue in the final sponge titanium product to below 200ppm, significantly better than the 500-800ppm level of traditional processes.

[0026] 3. Significant Resource Recycling Value: This process can remove chlorine impurities from long-accumulated waste-grade sponge titanium with high chlorine content (>0.1wt%) to meet standards, enabling the recycling of defective materials. This not only alleviates storage pressure but also reduces the consumption of primary ore resources by approximately 1.2 tons per ton of recycled sponge titanium, aligning with the concept of clean production.

[0027] 4. High process controllability: The process clearly defines three temperature windows: dehydration (200-300℃), medium-temperature degassing (400-600℃), and high-temperature deep dechlorination (850-950℃). Quantitative parameters are set for the holding time and heating rate of each stage. Combined with an online chlorine concentration monitoring system, operators can adjust the process curve in real time to ensure stable and reliable production.

[0028] Defect 1: High-chlorine sponge titanium is prone to moisture absorption after storage, forming a dual adsorption structure of "surface water film + pore water retention", with the pores encapsulating air components such as O2 and N2; Compared to the shortcomings of existing technologies: high-chlorinated sponge titanium has residual chlorine that increases the surface energy of the material. Combined with its micron-submicron porous structure, it easily adsorbs moisture and traps air. Moisture and oxygen are sealed in the internal pores of the sponge titanium and cannot be removed in advance. This patent innovatively and non-obviously incorporates a low-temperature high-vacuum dehydration and degassing pre-process as the first treatment unit, setting a low-temperature range of 100℃-200℃ and a high-vacuum environment for 10-20 hours.

[0029] Implement the logic for resolving defects in the matching process: The high vacuum environment significantly reduces the saturated vapor pressure of water, causing water trapped in pores and water film on the surface to vaporize rapidly. This water is then continuously extracted by the vacuum system without being bound by porous capillaries, completely eliminating the dual adsorption water structure. Simultaneously remove the O2 and N2 mixture of air trapped in the pores and remove oxidizing gases from inside the material; The low temperature of 100℃~200℃ is far below the critical temperature for the violent oxidation reaction of titanium, so titanium will not oxidize with oxygen throughout the process, solving the underlying problem of existing technologies that do not have pre-treatment for water and gas removal and that water, gas and oxygen are permanently retained in the pores.

[0030] Defect 2: Moisture-absorbing high-chlorine sponge titanium directly enters the smelting process above 1600℃. The high temperature of oxygen in the pores causes the titanium to be violently oxidized, generating TiO2 and Ti2O3 inclusions, which deteriorates the mechanical properties and causes shrinkage cavities, crusting, or even scrapping of the entire batch. Compared to the shortcomings of existing technologies, where moisture and oxygen inside the material are not removed in advance, oxygen breaks through the titanium passivation film during direct high-temperature smelting, resulting in strong oxidation reactions, oxide inclusions, and metallurgical defects in the ingot, this patent innovatively and non-obviously separates the two-stage vacuum re-evaporation gradient temperature control process into oxidation risk source removal and impurity removal steps. First, oxygen and water are thoroughly removed at low temperature, and then the temperature is raised to high temperature for dechlorination.

[0031] Implement the logic for resolving defects in the matching process: The pre-low temperature dehydration and degassing stage has completely removed all free water and encapsulated oxygen from the pores, and the material has no oxidizing medium before entering the 950℃~1050℃ high temperature dechlorination stage. The high-temperature stage is maintained under high vacuum without external air supply, and there are no reactant conditions for titanium oxidation reaction, thus eliminating the formation of TiO2 and Ti2O3 oxide inclusions from the source. After eliminating oxide inclusions, low-melting-point impurity eutectics are no longer generated during the smelting stage, thus avoiding metallurgical defects such as surface crusting, internal shrinkage cavities, decreased strength and elongation, and batch scrapping of ingots.

[0032] Defect 3: High residual chlorine generates TiCl4 volatile chloride at high melting temperatures, which corrodes the molten refractory materials. After cooling, chloride salts condense inside the product, forming a hidden corrosion source and reducing the long-term stability of titanium materials. Compared to the shortcomings of existing technologies, such as the lack of a dedicated deep dechlorination process in the pretreatment stage, the presence of residual chloride salts such as MgCl2 in the pores and grain boundaries of sponge titanium, and the formation of TiCl4 at high temperatures during smelting that corrodes the equipment and leaves residual chloride impurities, this patent innovatively and non-obviously incorporates a deep dechlorination process using a 950℃~1050℃ high-temperature long-time vacuum distillation as an independent secondary treatment unit, coupled with a continuous high vacuum environment to achieve directional separation of chloride salts.

[0033] Implement the logic for resolving defects in the matching process: High temperatures of 950℃~1050℃ significantly increase the vapor pressure and volatilization rate of residual chloride salts such as MgCl2, allowing solid chloride salts that are difficult to remove and are enriched in micron / submicron pores and grain boundaries to be converted into gaseous state. High vacuum drives gaseous chloride to continuously migrate and condense into the furnace condensation zone, permanently separating Cl⁻ ions from the interior of the sponge titanium matrix, thus achieving deep dechlorination. After treatment by this process, the chloride content of sponge titanium is significantly reduced, and a large amount of TiCl4 will not be generated in subsequent smelting processes. This avoids corrosion and loss of refractory materials in the smelting furnace and eliminates the internal hidden corrosion source formed by secondary condensation of chloride salts after cooling, thus ensuring the long-term corrosion resistance and service stability of titanium materials.

[0034] Defect 4: The existing process lacks a suitable, safe and efficient pretreatment solution for high-chlorine moisture-absorbing sponge titanium that is suitable for industrial use. As a result, the stockpiled high-chlorine sponge titanium cannot be reused, leading to a waste of raw materials. Compared to the shortcomings of existing technologies, such as the lack of a phased and controllable vacuum pretreatment process, high-chlorine moisture-absorbing sponge titanium can only be directly scrapped, resulting in low resource utilization. Furthermore, direct high-temperature treatment poses multiple safety and quality risks, including oxidation and equipment corrosion. This patent innovatively and non-obviously applies a standardized, quantitatively controllable two-stage vacuum re-evaporation process to the regeneration treatment of stockpiled high-chlorine moisture-absorbing sponge titanium.

[0035] Implement the logic for resolving defects in the matching process: The temperature range, holding time, and vacuum conditions for both processes are all quantified (low temperature 100-200℃ / 10-20h; high temperature 950-1050℃ / 50-80h), the process parameters are clear, and industrial mass production is easy to operate and easy to control stably. The pre-process low temperature eliminates the risk of oxidation, and the post-process high temperature stably removes chlorine impurities. This process can purify scrap-grade high-chlorine sponge titanium to qualified raw material standards, realize the resource reuse of stockpiled materials, reduce the consumption of primary titanium ore, and reduce raw material waste.

[0036] Innovatively, each of the above effects exists independently, yet a single structure can be used to combine the results.

[0037] It should be noted that the multiple solutions provided in this patent include their own basic solutions, which are independent of each other and do not restrict each other. However, they can also be combined with each other without conflict to achieve multiple effects.

[0038] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims.

Claims

1. A vacuum re-evaporation treatment method for high-chlorine-content sponge titanium, characterized in that, The vacuum re-evaporation process includes the following key steps: Low-temperature dehydration and degassing stage: The moisture-absorbing high-chlorine sponge titanium material is placed in a vacuum distillation furnace; the vacuum system is started to bring the furnace into a high vacuum state and maintain it; the furnace temperature is slowly and controllably raised to 100℃-200℃; under these low-temperature and high-vacuum conditions, the process is continued for 10 to 20 hours; the moisture (H2O) and air adsorbed on the surface and in the pores of the sponge titanium are gently removed. High-temperature deep dechlorination stage: After confirming that the low-temperature dehydration and degassing stage is completed, gradually increase the furnace temperature to 950℃-1050℃; maintain a high vacuum state and carry out distillation treatment for 50 to 80 hours at this high temperature.

2. The vacuum re-evaporation treatment method for high-chlorine-content sponge titanium as described in claim 1, characterized in that, The relatively low temperature of 100℃-200℃ is used to effectively prevent significant oxidation of titanium, while the high vacuum promotes the evaporation and removal of moisture and gas.

3. The vacuum re-evaporation treatment method for high-chlorine-content sponge titanium as described in claim 1, characterized in that... The high temperature of 950℃-1050℃ significantly increases the volatilization rate and vapor pressure of residual chlorides (mainly MgCl2 and other chloride salts); the high vacuum environment accelerates the migration of these volatile chloride components from the pores and interior of the sponge titanium to the condensation zone and condenses and precipitates, thereby achieving deep removal of the difficult-to-remove Cl⁻ ions remaining after primary distillation.

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