Method for reducing chlorine in sponge titanium through re-evaporation

Abstract

The invention discloses a method for reducing chlorine of titanium sponge through re-evaporation, and belongs to the technical field of titanium sponge metallurgy. The method comprises the following steps: putting high-chlorine sponge titanium into a heat treatment furnace for pretreatment, then heating to 1010-1050 DEG C, keeping for 2-6 hours, and finally cooling; the pretreatment mode is a mode I or a mode II; the first mode comprises the steps that the high-chlorine sponge titanium is placed in a heat treatment furnace to be heated to 110 DEG C to 350 DEG C for 30 min to 60 min to be preheated, argon is introduced into the heat treatment furnace for atmosphere replacement after the preheating temperature is reached, and vacuumizing is conducted till the vacuum state is achieved after atmosphere replacement; and the second mode comprises the steps that the high-chlorine sponge titanium is placed in the heat treatment furnace, vacuumizing is conducted to the preset vacuum degree, then argon is introduced for atmosphere replacement, then the furnace temperature is increased to 200-250 DEG C within 60 min, heat preservation is conducted, and argon is introduced again for atmosphere replacement. According to the production process for preparing the sponge titanium by the magnesiothermy, after re-steaming, the chlorine content in both a certified product of the sponge titanium and a wall-climbing titanium product is greatly reduced, particularly, the chlorine grade of the certified product of the sponge titanium is reduced to 0 grade, and the average reduction amplitude is about 55%.

Description

Technical Field

[0001] This invention belongs to the field of sponge titanium metallurgical technology, specifically relating to a method for reducing chlorine in sponge titanium by re-evaporation. Background Technology

[0002] The magnesothermic process, as the mainstream technology for industrial production of sponge titanium, has become a core method supporting the development of the titanium industry due to its mature and stable technical route. Its process chain uses titanium tetrachloride (TiCl4) as the starting material, and involves key steps such as reduction, distillation, cooling, and crushing to finally obtain the finished sponge titanium. Each step has a decisive impact on product quality. The reduction process generates sponge-like metallic titanium through the chemical reaction between metallic magnesium and titanium tetrachloride, while the subsequent distillation process is the core step in purifying the sponge titanium, directly affecting the product's purity and performance.

[0003] The design principle of the distillation process stems from the significant differences in the saturated vapor pressures of titanium, magnesium, and magnesium chloride within a specific temperature range. At process temperatures of 980–1020°C, the volatility characteristics of these three substances exhibit marked differentiation: for example, at 1000°C, the saturated vapor pressure of metallic magnesium reaches 0.033 MPa, magnesium chloride is 0.011 MPa, while the saturated vapor pressure of titanium is almost zero. This significant difference in vapor pressure provides a natural condition for impurity separation. When sponge titanium containing magnesium and magnesium chloride is kept at a constant temperature within this range for an extended period, the magnesium and magnesium chloride will evaporate and be removed due to their sufficient volatility. They are then condensed and recovered on the condenser wall, thus achieving preliminary purification of the sponge titanium.

[0004] To further enhance the distillation effect, the entire process must be carried out in a vacuum environment. Vacuum conditions not only lower the evaporation threshold of magnesium and magnesium chloride, accelerating their volatilization rate, but also isolate the sponge titanium from gases such as oxygen and nitrogen in the air, effectively preventing oxidation or nitridation contamination at high temperatures and ensuring product quality. However, limited by existing process parameters and equipment performance, conventional distillation processes cannot completely remove the volatiles from sponge titanium, and residual trace impurities become a potential hazard affecting downstream applications. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this invention proposes a method for reducing chlorine in sponge titanium through re-evaporation.

[0006] This invention provides a method for reducing chlorine in sponge titanium by re-evaporation, comprising the following steps: placing high-chlorine sponge titanium in a heat treatment furnace for pretreatment, then heating it to 1010-1050℃ and holding it for 2-6 hours, and finally cooling it; The pretreatment method is either Method 1 or Method 2; Method 1 is: placing high-chlorinated sponge titanium in a heat treatment furnace and heating it to 110-350°C for 30-60 minutes for preheating. After reaching the preheating temperature, argon gas is introduced into the heat treatment furnace for atmosphere replacement. After atmosphere replacement, the furnace is evacuated to a vacuum state. Method 2 is as follows: Place the high-chlorinated sponge titanium in a heat treatment furnace, first evacuate to the preset vacuum level, then introduce argon gas for atmosphere replacement, then raise the furnace temperature to 200-250℃ for 60 minutes and hold it at that temperature, and then introduce argon gas again for atmosphere replacement.

[0007] The high-chlorinated sponge titanium is a sponge titanium with a Cl element content of 0.06% or more.

[0008] Preferably, the vacuum level in the vacuum state of Method 1 is <10 Pa.

[0009] Preferably, in the second method, the temperature is maintained at 200-250℃ for 2 hours.

[0010] Preferably, if method one is used for pretreatment, the temperature is raised to 1010-1050℃ within 4-4.5 hours; if method two is used for pretreatment, the temperature is raised to 1010-1050℃ within 3-4 hours.

[0011] Preferably, the cooling method is as follows: stop heating, then maintain a vacuum state inside the furnace for cooling, wait until the temperature drops to 100°C, stop evacuating the vacuum and fill the furnace with argon gas, continue cooling to 40°C, and then take out the sample.

[0012] The technical solution of the present invention has the following beneficial effects: After re-steaming, the chlorine content in both the genuine sponge titanium and the wall-climbing titanium products in the production process of preparing sponge titanium by the magnesothermic method has been greatly reduced. In particular, the chlorine grade of the genuine sponge titanium has been reduced to grade 0, with an average reduction of about 55%. Detailed Implementation

[0013] Example 1 A method for reducing chlorine in sponge titanium by re-evaporation includes the following steps: (1) The selected sponge titanium is the crushed genuine product, which is downgraded to grade 2 because its Cl content is 0.098% (grade 2 is determined according to national standard GB / T 2524-2019). Genuine sponge titanium is the part left after removing the top layer of sponge titanium with high impurities, the bottom layer and the edge layer. The elemental content of the genuine sponge titanium in this embodiment is shown in Table 2.

[0014] (2) Place the high-chlorinated sponge titanium in a heat treatment furnace and heat it to 110-350℃ for 30-60 minutes for preheating. After reaching the preheating temperature, introduce argon into the heat treatment furnace for atmosphere replacement. After atmosphere replacement, evacuate to a vacuum degree of less than 10 Pa and hold for 2 hours. Then, while maintaining the vacuum, continue to heat to 1010-1050℃ for 4-4.5 hours and hold for 6 hours. Finally, stop heating and then maintain the vacuum state in the furnace for cooling. When the temperature drops to 100℃, stop evacuating and introduce argon into the furnace. Continue to cool to 40℃ and then take out the sample. The specific parameters of step (2) are shown in Table 1.

[0015] Table 1 According to national standards, the elemental content of the raw material sponge titanium in Example 1 and the final sample are shown in Table 2.

[0016] Table 2 After re-distillation, the chlorine content in the final product decreased significantly, with the chlorine grade dropping to level 0 and 0A, an average reduction of approximately 55%. Other impurity elements in the sponge titanium, such as Fe, Si, Mn, Mg, H, Ni, Cr, Sn, and Al, showed slight changes, but these did not affect the product's level 0 classification. Although the levels of C, O, and N increased slightly, all indicators still met the level 0 requirements. Therefore, this invention controls the O content within the standard range and minimizes the Cl content as much as possible.

[0017] Example 2 A method for reducing chlorine in sponge titanium by re-evaporation includes the following steps: (1) Eight batches of climbing titanium with a 1kg sample from the laboratory were selected. After thorough mixing, they were divided into eight samples using a divider. Six of them were used as experimental samples and the other two were used as test samples. The average chlorine content was 0.089%. Climbing titanium is the part of sponge titanium with high impurity at the top. The elemental content of climbing titanium in this embodiment is shown in Table 4.

[0018] (2) Place the climbing titanium in the heat treatment furnace, first evacuate to the preset vacuum degree ≤10Kpa and keep it for 2 hours, then introduce argon gas for atmosphere replacement, then raise the furnace temperature to 200-250℃ in 60 minutes and keep it for 2 hours, then introduce argon gas again for atmosphere replacement, after the replacement is completed, raise the temperature to 1050℃ in 3-4 hours and keep it for 2-6 hours, finally stop heating, then keep the furnace in a vacuum state for cooling, wait until the temperature drops to 100℃, stop evacuating and introduce argon gas into the furnace, continue cooling to 40℃, and then take out the sample; the specific parameters of step (2) are shown in Table 3.

[0019] Table 3 According to national standards, the elemental content of the raw material, titanium, and the final sample obtained in Example 2 is shown in Table 4.

[0020] Table 4 After re-distillation: Experiments 1-6 involved the re-distillation of wall-climbing titanium. The chlorine content decreased after distillation in all cases. However, the chlorine reduction in the final product of Example 2 was not as significant as in Example 1. Therefore, the chlorine in the genuine sponge titanium was more easily distilled out than that in the wall-climbing titanium. Nevertheless, Examples 1-2 effectively reduced the chlorine content in high-chlorine sponge titanium and controlled the oxygen content to level 0, showing a significant advantage in reducing chlorine in genuine sponge titanium.

[0021] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for reducing chlorine in sponge titanium by redistillation, characterized in that: The process includes the following steps: placing the high-chlorinated sponge titanium in a heat treatment furnace for pretreatment, then heating it to 1010-1050℃ and holding it for 2-6 hours, and finally cooling it. The pretreatment method is either Method 1 or Method 2; Method 1 is: placing high-chlorinated sponge titanium in a heat treatment furnace and heating it to 110-350°C for 30-60 minutes for preheating. After reaching the preheating temperature, argon gas is introduced into the heat treatment furnace for atmosphere replacement. After atmosphere replacement, the furnace is evacuated to a vacuum state. Method 2 is as follows: Place the high-chlorinated sponge titanium in a heat treatment furnace, first evacuate to the preset vacuum level, then introduce argon gas for atmosphere replacement, then raise the furnace temperature to 200-250℃ for 60 minutes and hold it at that temperature, and then introduce argon gas again for atmosphere replacement.

2. The method for reducing chlorine in sponge titanium by redistillation as described in claim 1, characterized in that: In Method 1, the vacuum level under vacuum conditions is <10 Pa.

3. The method for reducing chlorine in sponge titanium by redistillation as described in claim 1, characterized in that: In Method 2, the temperature is maintained at 200-250℃ for 2 hours.

4. The method for reducing chlorine in sponge titanium by redistillation as described in claim 1, characterized in that: If method one is used for pretreatment, the temperature is raised to 1010-1050℃ within 4-4.5 hours; if method two is used for pretreatment, the temperature is raised to 1010-1050℃ within 3-4 hours.

5. The method for reducing chlorine in sponge titanium by redistillation as described in claim 1, characterized in that: The cooling method is as follows: stop heating, then maintain a vacuum state inside the furnace for cooling. When the temperature drops to 100°C, stop evacuating the vacuum and fill the furnace with argon gas. Continue cooling to 40°C and then remove the sample.

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