A method for preparing titanium metal powder by three-stage reduction of titanium dioxide

Abstract

The present invention provides a method for preparing titanium powder by three-stage reduction of titanium dioxide, the method comprising the following steps: (1) mixing a titanium source containing calcium, a first reducing agent and a first auxiliary agent, and sequentially performing a first reduction and a first wet treatment to obtain TiO x Intermediate powder, the first reducing agent includes aluminum; (2) the TiO x The intermediate powder is subjected to a second reduction with a second reducing agent, and then subjected to a second wet treatment to obtain a titanium oxide solid solution, wherein the second reducing agent includes magnesium; (3) the titanium oxide solid solution is deeply deoxidized with a deoxidizer, and then subjected to a third wet treatment to obtain metallic titanium powder, wherein the deoxidizer includes magnesium and / or calcium. The method significantly reduces the cost of the reducing agent by using aluminum powder as the reducing agent for the first reduction, and by introducing calcium oxide during the reduction process, avoids the high-temperature slag-metal separation method using a conventional thermite self-propagating reaction, resulting in high separation efficiency and high purity of the obtained metallic titanium powder with low oxygen content.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical metallurgy, and in particular to a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. Background Art

[0002] Titanium is a rare metal with a high melting point. It is widely used in aerospace, petrochemical, biomedicine and other fields due to its high specific strength, good high and low temperature performance, strong corrosion resistance and good biological affinity.

[0003] The Kroll process, a method for preparing titanium metal by magnesium-thermal reduction of TiCl₄, has become the world's leading titanium production method since its introduction in 1937. However, its complex process, high energy consumption, high cost, and severe environmental pollution have limited its widespread application. To develop a new process to replace the Kroll process, metallurgical scholars at home and abroad have proposed processes for preparing titanium metal by direct electrolysis / reduction of TiO₂, including the FFC method, the OS method, the EMR method, the PRP method, the SOM method, and the USTB method. However, these processes have always been plagued by difficult-to-overcome technical challenges, such as low electrolysis efficiency and unstable product quality, preventing their industrialization.

[0004] Titanium dioxide magnesium thermal reduction is also used in the preparation of titanium, but the oxygen content in the final product is relatively high, so direct magnesium thermal reduction is also difficult to obtain a product with qualified oxygen content.

[0005] CN101628337A discloses a method for preparing metallic titanium powder by reducing titanium dioxide with magnesium. The method uses titanium dioxide as a raw material, calcium chloride as an additive, and magnesium as a reducing agent. -30 Under the conditions of 1.5 Pa and a temperature of 800-1200°C, magnesium metal volatilizes into magnesium vapor, which reacts with the titanium dioxide placed on the upper layer to produce titanium metal and magnesium oxide. After washing with dilute acid and vacuum drying, titanium powder is obtained. However, calcium chloride does not have a significant effect in this solution, and the cost of magnesium as a reducing agent is high.

[0006] CN107639234A discloses a method for preparing metallic titanium powder by magnesium thermal reduction of TiO2. The method reduces the heat released during the reaction by adding a diluent, thereby promoting the reaction to proceed in the forward direction. However, since magnesium is used as a reducing agent, the reduction cost is relatively high.

[0007] Therefore, the existing process of reducing titanium dioxide to prepare metallic titanium powder needs to further reduce the cost of the reducing agent to improve the economy of the overall process. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. By adopting a three-stage reduction method, aluminum powder is introduced as a reducing agent, and magnesium and / or calcium is subsequently used as a deoxidizing agent, the cost of the reducing agent is significantly reduced, and high-purity metallic titanium powder with a low oxygen content can be produced, which has broad application prospects.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide, the method comprising the following steps:

[0011] (1) Mixing a calcium-containing titanium source, a first reducing agent, and a first auxiliary agent, and sequentially performing a first reduction and a first wet treatment to obtain TiO x Intermediate powder, wherein 0.167 < x ≤ 1, and the first reducing agent includes aluminum;

[0012] (2) the TiO x The intermediate powder is subjected to a second reduction with a second reducing agent, and then subjected to a second wet process to obtain a titanium oxide solid solution, wherein the oxygen content in the titanium oxide solid solution is ≤2wt%, and the second reducing agent includes magnesium;

[0013] (3) The titanium oxide solid solution is deeply deoxidized by a deoxidizer and then subjected to a third wet process to obtain metallic titanium powder, wherein the deoxidizer includes magnesium and / or calcium.

[0014] The cost of aluminum as a reducing agent is lower than that of magnesium. However, since traditional aluminum reduction generally uses the method of self-propagating aluminum heat, an aluminum phase that is difficult to dissolve in acid or water will be generated during the reduction process. Subsequently, a high-temperature slag-metal separation method is required. Wet treatment cannot be used to separate aluminum and titanium. There is a problem of incomplete separation, and the temperature conditions required for separation are harsh, which to a certain extent reduces the cost advantage of the reducing agent.

[0015] The present invention has found that the combination of calcium-containing substances and the first auxiliary agent, based on aluminum as a reducing agent, can control the reduced aluminum phase to a calcium-aluminum compound soluble in dilute acid. On the one hand, the chemical composition of the reduction by-product phase is changed, especially the generation of substances with more negative Gibbs free energy. Under the premise of no titanium-aluminum alloy phase, the reaction "Al+TiO2→TiO x +Al2O3" original equilibrium state (when no titanium-aluminum alloy phase is generated, according to the oxygen potential, the reduction reaction can only obtain TiO), and obtain TiO with lower oxygen content x On the other hand, the controlled generation of this calcium-aluminum compound that is easily soluble in dilute acid can transform the conventional slag-gold stratification physical separation method caused by self-propagating ultra-high temperature reaction into wet separation, which is more thorough, significantly improves the subsequent separation cost and operation safety, and obtains higher purity TiOx Compared with the conventional magnesium reduction method, the cost of the reducing agent required for this part of oxygen removal is significantly reduced, which has very important value in the field of industrial application.

[0016] The present invention uses a three-step reduction method, through an aluminum reduction-magnesium reduction-magnesium / calcium deep deoxidation process, to significantly reduce the oxygen content in the final titanium metal powder, and has application prospects. The value range of x in the present invention is 0.167<x≤1, for example, it can be 0.168, 0.17, 0.172, 0.18, 0.19, 0.20, 0.22, 0.23, 0.25, 0.28, 0.30, 0.35, 0.38, 0.40, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.

[0017] Preferably, the metal titanium powder of the present invention refers to titanium powder with an oxygen content of ≤0.3wt%, for example, it can be 0.3wt%, 0.25wt%, 0.2wt%, 0.15wt%, 0.12wt%, 0.10wt% or 0.08wt%.

[0018] Preferably, the calcium-containing titanium source in step (1) includes any one of a first titanium source, a second titanium source, a third titanium source or a fourth titanium source, or a combination of at least two thereof; the first titanium source is a mixture of titanium dioxide and calcium oxide, the second titanium source is a mixture of calcium oxide and calcined titanium dioxide, the third titanium source is a mixture of a calcined product of calcium oxide and titanium dioxide mixed in a stoichiometric ratio of CaTiO3 and calcium oxide, and the fourth titanium source is a mixture of calcium oxide and titanium dioxide mixed in a stoichiometric ratio exceeding CaTiO3 and calcined.

[0019] Preferably, the calcination temperature of the second titanium source, the third titanium source or the fourth titanium source is independently 1000-1400°C, for example, it can be 1000°C, 1044°C, 1088°C, 1132°C, 1176°C, 1220°C, 1264°C, 1308°C, 1352°C or 1400°C, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0020] Preferably, the molar ratio of calcium to the first reducing agent in the calcium-containing titanium source in step (1) is 0.6 to 2:1, for example, it can be 0.6:1, 0.8:1, 1:1, 1.1:1, 1.3:1, 1.4:1, 1.6:1, 1.7:1, 1.9:1 or 2:1, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0021] Preferably, the molar ratio of the first reducing agent to the titanium in the calcium-containing titanium source is 0.67 to 1.30:1, for example, it can be 0.67:1, 0.74:1, 0.8:1, 0.86:1, 0.92:1, 0.98:1, 1.04:1, 1.1:1, 1.16:1 or 1.30:1, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0022] The present invention further preferably has the molar ratio of calcium, titanium and the first reducing agent in the first reduction within the above range, which can ensure that the first reduction reaches the set oxygen content level while avoiding the formation of dilute acid-insoluble aluminum phase.

[0023] Preferably, in step (1), the first auxiliary agent comprises any one of anhydrous CaCl2, KCl, NaCl, CaCl2-KCl eutectic salt, CaCl2-NaCl eutectic salt, CaCl2-LiCl eutectic salt, KCl-NaCl eutectic salt, LiCl-NaCl eutectic salt, LiCl-KCl eutectic salt, AlCl3-KCl eutectic salt or AlCl3-NaCl eutectic salt, or a combination of at least two thereof, wherein a typical but non-limiting combination is a combination of CaCl2-NaCl eutectic salt and CaCl2-LiCl eutectic salt, a combination of CaCl2-NaCl eutectic salt and CaCl2-LiCl eutectic salt, and a combination of AlCl3-KCl eutectic salt and AlCl3-NaCl eutectic salt.

[0024] The present invention further prefers calcium-containing substances as the first auxiliary agent, which can better control the formation of aluminum phase that is easily soluble in dilute acid and avoid aluminum in TiO x Residue in the intermediate powder, while ensuring TiO x The oxygen content in the intermediate powder reaches the set level.

[0025] Preferably, the weight ratio of the first auxiliary agent to the titanium in the calcium-containing titanium source calculated as TiO2 is 0.05 to 3:1, for example, it can be 0.05:1, 0.30:1, 0.70:1, 1.00:1, 1.30:1, 1.60:1, 2.00:1, 2.30:1, 2.60:1 or 3:1, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0026] Preferably, the first reducing agent is in the form of powder, chips or granules, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of powder and chips, a combination of granules and chips, and a combination of powder and granules.

[0027] Preferably, the temperature of the first reduction in step (1) is 700-1100°C, for example, it can be 700°C, 740°C, 780°C, 830°C, 870°C, 920°C, 960°C, 1000°C, 1050°C or 1100°C, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0028] Preferably, the first reduction time is 0.5 to 24 hours, for example, 0.5 hours, 3 hours, 5 hours, 8 hours, 11 hours, 13 hours, 16 hours, 18 hours, 21 hours or 24 hours, but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0029] Preferably, the first reducing atmosphere comprises a vacuum or protective atmosphere.

[0030] Preferably, the first reducing protective atmosphere comprises any one of argon, hydrogen or helium, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of argon and hydrogen, a combination of helium and hydrogen, and a combination of argon and helium.

[0031] Preferably, the first wet treatment in step (1) comprises: slurrying the product of the first reduction with water and / or acid solution to obtain a slurry; the slurry is successively pH-adjusted and solid-liquid separated, and the obtained solid phase is successively washed and dried to obtain TiOx intermediate powder.

[0032] Preferably, the second wet treatment in step (2) includes: slurrying the second reduced product with water and / or acid solution to obtain a slurry; the slurry is successively pH-adjusted and solid-liquid separated, and the obtained solid phase is successively washed and dried to obtain a titanium oxide solid solution.

[0033] Preferably, the third wet treatment in step (3) comprises: slurrying the deep deoxidation product with water and / or acid solution to obtain a slurry; the slurry is successively pH-adjusted and solid-liquid separated, and the obtained solid phase is successively washed and dried to obtain metallic titanium powder.

[0034] Preferably, the pH of the acid solution in the first wet treatment, the second wet treatment and the third wet treatment is independently ≥0.5, for example, it can be 0.5, 0.6, 0.7, 0.8, 0.9 or 1.0, etc.

[0035] Preferably, the liquid-to-solid ratio of the slurry in the first wet treatment, the second wet treatment and the third wet treatment is independently 1 to 100:1 mL / g, for example, it can be 1:1 mL / g, 12:1 mL / g, 20:1 mL / g, 30:1 mL / g, 45:1 mL / g, 50:1 mL / g, 60:1 mL / g, 70:1 mL / g, 80:1 mL / g or 100:1 mL / g, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0036] Preferably, the acid used for pH adjustment in the first wet treatment, the second wet treatment and the third wet treatment is independently hydrochloric acid.

[0037] Preferably, the pH of the slurry is independently controlled to be ≥ 0.8 during the pH adjustment in the first wet treatment, the second wet treatment and the third wet treatment, for example, it can be 0.8, 0.9, 1.0, 1.1, 1.2, 1.5 or 2.0, etc., but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0038] Preferably, the pH of the slurry after pH adjustment in the first wet treatment, the second wet treatment and the third wet treatment is independently 1.5 to 3.0, for example, it can be 1.5, 1.7, 1.9, 2, 2.2, 2.4, 2.5, 2.7, 2.9 or 3.0, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0039] In the present invention, in order to prevent TiO x (0.167<x≤1) The intermediate powder, titanium oxide solid solution and metallic titanium powder undergo a dissolution reaction with the acid during the pH adjustment process. The slurry in the pH adjustment process is preferably controlled at a pH value above 0.8. The pH adjustment is considered to be completed when the pH value stabilizes between 1.5 and 3.0 and no longer changes.

[0040] Preferably, the washing temperature in the first wet treatment, the second wet treatment and the third wet treatment is independently 0 to 60°C, for example, it can be 0°C, 7°C, 14°C, 20°C, 27°C, 34°C, 40°C, 47°C, 54°C or 60°C, etc., but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0041] Preferably, the washing comprises washing with water.

[0042] Preferably, the drying temperature in the first wet treatment, the second wet treatment, and the third wet treatment is independently ≤60°C, for example, 0°C, 7°C, 14°C, 20°C, 27°C, 34°C, 40°C, 47°C, 54°C, or 60°C, etc., but is not limited to the listed values, and other values not listed in this range are also applicable. The drying method is one of atmospheric pressure or vacuum drying at no more than 60°C, or freeze drying. Controlling the drying temperature in the present invention can effectively prevent excessive oxidation of the titanium powder surface, which is more conducive to controlling the oxygen content level of the final metallic titanium powder.

[0043] Preferably, in step (2), the second reducing agent and TiO x The mass ratio of the intermediate powder is 0.09 to 0.56:1, for example, it can be 0.09:1, 0.15:1, 0.20:1, 0.24:1, 0.28:1, 0.30:1, 0.35:1, 0.40:1, 0.46:1 or 0.56:1, but is not limited to the listed values. Other unlisted values within this range are also applicable.

[0044] Preferably, the second reducing agent is in the form of powder, chips or granules, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of powder and chips, a combination of granules and chips, and a combination of powder and granules.

[0045] Preferably, a second auxiliary agent is added during the second reduction.

[0046] Preferably, the second auxiliary agent comprises any one of anhydrous MgCl2, MgCl2-CaCl2 eutectic salt, MgCl2-NaCl eutectic salt or MgCl2-KCl eutectic salt, or a combination of at least two thereof, wherein typical but non-limiting combinations are a combination of MgCl2 and a MgCl2-CaCl2 eutectic salt, a combination of MgCl2 and a MgCl2-NaCl eutectic salt, a combination of MgCl2 and a MgCl2-KCl eutectic salt, a combination of a MgCl2-KCl eutectic salt and a MgCl2-NaCl eutectic salt, and a combination of a MgCl2-KCl eutectic salt and a MgCl2-CaCl2 eutectic salt.

[0047] Preferably, the second auxiliary agent is x The weight ratio of the intermediate powder is 0.05 to 3:1, for example, it can be 0.05:1, 0.38:1, 0.70:1, 1.05:1, 1.35:1, 1.65:1, 2.00:1, 2.30:1, 2.60:1 or 3:1, but is not limited to the listed values. Other values not listed within the range are also applicable.

[0048] Preferably, the temperature of the second reduction is 650-900°C, for example, it can be 650°C, 670°C, 700°C, 730°C, 760°C, 780°C, 810°C, 840°C, 870°C or 900°C, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0049] Preferably, the second reduction time is 0.25 to 48 hours, for example, 0.25 hours, 5 hours, 10 hours, 16 hours, 20 hours, 26 hours, 32 hours, 35 hours, 42 hours or 48 hours, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0050] Preferably, the second reducing protective atmosphere comprises any one of argon, hydrogen or helium, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of argon and hydrogen, a combination of helium and hydrogen, and a combination of argon and helium.

[0051] Preferably, the shape of the deoxidizer in step (3) includes any one of powder, chips or granules or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of powder and chips, a combination of granules and chips, and a combination of powder and granules.

[0052] Preferably, a third auxiliary agent is added during the deep deoxidation.

[0053] Preferably, when the deoxidizer contains magnesium, the mass ratio of magnesium to titanium oxide solid solution is 0.03 to 0.2:1, for example, it can be 0.03:1, 0.05:1, 0.07:1, 0.09:1, 0.1:1, 0.12:1, 0.14:1, 0.15:1, 0.17:1, 0.19:1 or 0.2:1, etc., but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0054] Preferably, when the deoxidizer contains magnesium, the third auxiliary agent includes any one of anhydrous MgCl2, MgCl2-CaCl2 eutectic salt, MgCl2-NaCl eutectic salt or MgCl2-KCl eutectic salt, or a combination of at least two thereof, wherein typical but non-limiting combinations are a combination of anhydrous MgCl2 and MgCl2-CaCl2 eutectic salt, a combination of MgCl2-KCl eutectic salt and MgCl2-CaCl2 eutectic salt, and a combination of anhydrous MgCl2 and MgCl2-KCl eutectic salt.

[0055] Preferably, when the deoxidizer contains magnesium, the weight ratio of the third auxiliary agent to the titanium oxide solid solution is 0.05 to 3:1, for example, it can be 0.05:1, 0.38:1, 0.70:1, 1.05:1, 1.35:1, 1.65:1, 2.05:1, 2.35:1, 2.65:1 or 3:1, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0056] Preferably, when the deoxidizer contains magnesium, the temperature of the deep deoxidation is 650-900°C, for example, it can be 650°C, 670°C, 700°C, 730°C, 760°C, 780°C, 810°C, 840°C, 870°C or 900°C, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0057] Preferably, when the deoxidizer contains magnesium, the deep deoxidation time is 0.25 to 48 hours, for example, 0.25 hours, 5 hours, 10 hours, 16 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours or 48 hours, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0058] Preferably, when the deoxidizer contains magnesium, the deep deoxidation atmosphere includes a hydrogen-argon mixed atmosphere or a pure hydrogen atmosphere.

[0059] Preferably, the volume fraction of hydrogen in the hydrogen-argon mixed atmosphere is 5 to 100%, for example, it can be 5%, 16%, 27%, 37%, 48%, 58%, 69%, 79%, 90% or 100%, etc., but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0060] Preferably, when the deoxidizer contains calcium, the mass ratio of calcium to titanium oxide solid solution is 0.05 to 0.4:1, for example, it can be 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1 or 0.4:1, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0061] Preferably, when the deoxidizer contains calcium, the third auxiliary agent includes any one of anhydrous CaCl2, CaCl2-MgCl2 eutectic salt, CaCl2-NaCl eutectic salt, CaCl2-KCl eutectic salt or CaCl2-LiCl eutectic salt, or a combination of at least two thereof, wherein typical but non-limiting combinations are a combination of anhydrous CaCl2 and a CaCl2-MgCl2 eutectic salt, a combination of a CaCl2-KCl eutectic salt and a CaCl2-MgCl2 eutectic salt, and a combination of anhydrous CaCl2 and a CaCl2-LiCl eutectic salt.

[0062] Preferably, when the deoxidizer contains calcium, the weight ratio of the third auxiliary agent to the titanium oxide solid solution is 0.05 to 3:1, for example, it can be 0.05:1, 0.35:1, 0.75:1, 1.05:1, 1.35:1, 1.65:1, 2.05:1, 2.35:1, 2.65:1 or 3:1, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0063] Preferably, when the deoxidizer contains calcium, the temperature of the deep deoxidation is 700-1100°C, for example, it can be 700°C, 740°C, 780°C, 830°C, 870°C, 920°C, 960°C, 1010°C, 1050°C or 1100°C, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0064] Preferably, when the deoxidizer contains calcium, the deep deoxidation time is 0.25 to 48 hours, for example, 0.25 hours, 5 hours, 10 hours, 15 hours, 21 hours, 26 hours, 32 hours, 35 hours, 40 hours or 48 hours, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0065] Preferably, when the deoxidizer contains calcium, the deep deoxidation atmosphere includes vacuum or protective atmosphere.

[0066] Preferably, the deep deoxidation protective atmosphere includes any one of argon, hydrogen or helium, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of argon and hydrogen, a combination of helium and hydrogen, and a combination of argon and helium.

[0067] Preferably, the method further comprises: performing heat treatment on the titanium oxide solid solution between the second wet treatment and the deep deoxidation.

[0068] The surface oxygen content of the titanium metal particles decreases as the specific surface area decreases. After the first and second reductions, the titanium oxide solid solution obtained by the present invention still has a certain pore structure. Heat treatment can produce a denser intermediate, which is more conducive to controlling the surface oxygen content, and thus the oxygen content in the final titanium powder.

[0069] Preferably, the temperature of the heat treatment is 750-1100°C, for example, it can be 750°C, 780°C, 820°C, 860°C, 900°C, 940°C, 980°C, 1020°C, 1060°C or 1100°C, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0070] The present invention further preferably controls the heat treatment temperature within the above range. On the one hand, a temperature that is not too high is beneficial for equipment selection, and on the other hand, it can also ensure the densification of the titanium oxide solid solution.

[0071] Preferably, the heat treatment time is 0.167 to 24 hours, for example, it can be 0.167 hours, 2 hours, 5 hours, 8 hours, 10 hours, 13 hours, 16 hours, 18 hours, 21 hours or 24 hours, but is not limited to the listed values. Other values not listed within this range are also applicable.

[0072] Preferably, the heat treatment atmosphere includes vacuum or protective atmosphere.

[0073] Preferably, the protective atmosphere of the heat treatment includes any one of hydrogen, argon or helium, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of hydrogen and argon, a combination of helium and argon, and a combination of hydrogen and helium.

[0074] Preferably, the method further comprises: subjecting the metallic titanium powder obtained by the third wet treatment in step (3) to dehydrogenation treatment.

[0075] Hydrogen regulates the thermodynamic stability of the Ti-O solid solution. Magnesium can efficiently remove oxygen from the Ti-O solid solution with the help of interstitial hydrogen. However, when magnesium is used as a deoxidizer, the deep deoxidation process can result in hydrogen in the titanium powder. Therefore, dehydrogenation is performed when the application of the titanium powder product has limitations on hydrogen content.

[0076] Preferably, the temperature of the dehydrogenation treatment is 500-1000°C, for example, it can be 500°C, 550°C, 610°C, 660°C, 720°C, 770°C, 830°C, 880°C, 940°C or 1000°C, but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0077] Preferably, the atmosphere of the dehydrogenation treatment includes vacuum or protective atmosphere.

[0078] Preferably, the protective atmosphere of the dehydrogenation treatment includes argon and / or helium.

[0079] Preferably, the method comprises the following steps:

[0080] (1) mixing a calcium-containing titanium source, a first reducing agent, and a first auxiliary agent, wherein the molar ratio of calcium in the calcium-containing titanium source to the first reducing agent is 0.6-2:1, the molar ratio of the first reducing agent to titanium in the calcium-containing titanium source is 0.67-1.30:1, and the weight ratio of the first auxiliary agent to titanium in the calcium-containing titanium source as TiO2 is 0.05-3:1, and sequentially subjecting the mixture to a first reduction at 700-1100°C for 0.5-24h in vacuum or protective atmosphere to obtain a first reduced product;

[0081] The product of the first reduction is slurried with water and / or an acid solution with a pH value of ≥0.5, with a liquid-solid ratio of 1 to 100:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥0.8 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 1.5 to 3.0, and solid-liquid separation is performed, and the obtained solid phase is successively washed at 0 to 60°C and dried at ≤60°C to obtain TiO x Intermediate powder, where 0.167<x≤1;

[0082] (2) the TiO x The intermediate powder is subjected to a second reduction agent and a second auxiliary agent in a protective atmosphere at 650-900°C for 0.25-48h. The second reducing agent and TiO x The mass ratio of the intermediate powder is 0.09-0.56:1, the second auxiliary agent and TiO x The weight ratio of the intermediate powder is 0.05 to 3:1, and the second reduced product is obtained;

[0083] The product of the second reduction is slurried with water and / or an acid solution with a pH of ≥0.5, with a liquid-solid ratio of 1 to 100:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥0.8 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 1.5 to 3.0, and solid-liquid separation is performed, and the obtained solid phase is successively washed at 0 to 60° C. and dried at ≤60° C. to obtain a titanium oxide solid solution;

[0084] (3) The titanium oxide solid solution is first heat-treated at 750-1100° C. for 0.167-24 h under vacuum or protective atmosphere, and then deeply deoxidized under the action of a deoxidizer and a third auxiliary agent to obtain a deeply deoxidized product;

[0085] The deep deoxidation product is slurried with water and / or acid solution with a pH value of ≥0.5, with a liquid-solid ratio of 1 to 100:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted, during which the pH value of the slurry is controlled to be ≥0.8, and the pH value of the slurry after pH adjustment is stabilized at 1.5 to 3.0, and solid-liquid separation is performed, and the obtained solid phase is successively washed at 0 to 60°C and dried at ≤60°C to obtain metallic titanium powder.

[0086] The second reduction of the present invention can further reduce the oxygen content of the first reduction product, greatly reducing the temperature conditions of the heat treatment before the third reduction, ensuring that the temperature of the entire process is ≤1100°C (those skilled in the art understand that 1100°C is just the temperature threshold for selecting equipment with higher material requirements), thereby significantly reducing the thermal load of the equipment, thereby reducing the cost of the equipment, and facilitating the implementation of the equipment.

[0087] The present invention has no particular limitation on the solid-liquid separation in the above process. Any device and method for solid-liquid separation known to those skilled in the art can be used, and can also be adjusted according to the actual process. For example, it can be filtration, centrifugation or sedimentation separation, or a combination of different methods.

[0088] The present invention has no particular limitation on the drying process. Any drying device and method known to those skilled in the art can be used. The drying method can also be adjusted according to the actual process. For example, it can be air drying, vacuum drying, oven drying or freeze drying, or a combination of different methods.

[0089] Compared with the prior art, the present invention has at least the following beneficial effects:

[0090] (1) The method for preparing titanium powder by three-stage reduction of titanium dioxide provided by the present invention adopts a process of aluminum reduction-magnesium reduction-magnesium / calcium deep deoxidation. Compared with the full magnesium reduction process of oxygen in titanium dioxide, the cost of the reducing agent required for the oxygen reduced by aluminum can be saved by more than 60%, and the overall reducing agent cost can be reduced by 22,434 yuan / ton of titanium powder, which is only 56% of the original magnesium reduction cost.

[0091] (2) The method for preparing metallic titanium powder by three-stage reduction of titanium dioxide provided by the present invention obtains an alumina-enriched by-product phase that is easily soluble in dilute acid by adding CaO and a first auxiliary agent and controlling an appropriate ratio. The titanium phase in the first reduction product is easily separated from the aluminum phase and the calcium phase, and the reduction temperature is reduced, the equipment requirements are lower, and the operation is safer;

[0092] (3) The method for preparing metallic titanium powder by three-stage reduction of titanium dioxide provided by the present invention further reduces the oxygen content in the metallic titanium powder through the third step of deep deoxidation of calcium and / or magnesium, thereby ensuring that the oxygen content in the prepared titanium powder is low at a relatively low cost, the oxygen content being lower than 0.2 wt%, and under optimal conditions, the oxygen content being less than 0.1 wt%. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Figure 1 It is a schematic flow chart of a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0094] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0095] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0096] As a specific embodiment of the present invention, a method for preparing titanium powder by three-stage reduction of titanium dioxide is provided. The flow chart of the method is as follows: Figure 1 As shown, the specific steps include:

[0097] (1) mixing a calcium-containing titanium source (calcined or uncalcined titanium dioxide and calcium oxide), a first reducing agent, and a first auxiliary agent, performing a first reduction, and obtaining a first reduced product;

[0098] The product of the first reduction is subjected to a first wet treatment, wherein the first wet treatment comprises slurrying the product of the first reduction with water and / or acid solution to obtain a slurry; the slurry is successively pH-adjusted and subjected to solid-liquid separation, and the obtained solid phase is successively washed and dried to obtain TiO x Intermediate powder, where 0.167<x≤1;

[0099] (2) the TiO x The intermediate powder is subjected to a second reduction by a second reducing agent and a second auxiliary agent to obtain a second reduced product;

[0100] The second reduced product is subjected to a second wet treatment, wherein the second wet treatment comprises slurrying the second reduced product with water and / or acid solution to obtain a slurry; the slurry is successively pH-adjusted and subjected to solid-liquid separation, and the obtained solid phase is successively washed and dried to obtain a titanium oxide solid solution;

[0101] (3) The titanium oxide solid solution is first heat-treated under vacuum or protective atmosphere (optional step), and then deeply deoxidized under the action of a deoxidizer and a third auxiliary agent to obtain a deeply deoxidized product;

[0102] The deep deoxidation product is subjected to a third wet treatment, which includes slurrying the deep deoxidation product with water and / or acid solution to obtain a slurry; the slurry is successively pH-adjusted and solid-liquid separated, and the obtained solid phase is successively washed and dried to obtain metallic titanium powder.

[0103] Example 1

[0104] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide, the method comprising the following steps:

[0105] (1) mixing a calcium-containing titanium source (a mixture of calcium oxide and calcined titanium dioxide), aluminum powder, and a CaCl2-KCl eutectic salt, wherein the molar ratio of calcium in the calcium-containing titanium source to the aluminum powder is 1.5:1, the molar ratio of the aluminum powder to the titanium in the calcium-containing titanium source is 1.11:1, and the weight ratio of the CaCl2-KCl eutectic salt to the titanium in the calcium-containing titanium source as TiO2 is 2.0:1, and sequentially subjecting the mixture to a first reduction in a helium atmosphere at 1000°C for 6 hours to obtain a first reduced product;

[0106] The product of the first reduction was slurried with hydrochloric acid solution at a pH of 1.5, with a liquid-to-solid ratio of 50:1 mL / g, to obtain a slurry; the slurry was successively pH-adjusted, and the pH of the slurry was controlled to be ≥ 0.8 during the pH adjustment. The pH of the slurry after pH adjustment was stabilized at 2.0, and filtered. The obtained solid phase was successively washed with water at 42°C and dried at 50°C to obtain TiO x middle powder;

[0107] (2) the TiO x The intermediate powder was reduced for the second time by magnesium powder and MgCl2-KCl eutectic salt in helium atmosphere at 800℃ for 4h. x The mass ratio of the intermediate powder is 0.15:1, MgCl2-KCl eutectic salt and TiO x The weight ratio of the intermediate powder is 2.0:1, and the second reduced product is obtained;

[0108] The product of the second reduction is slurried in water with a liquid-to-solid ratio of 80:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥0.8 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 2.5, and filtered, and the obtained solid phase is successively washed with water at 55° C. and dried at 55° C. to obtain a titanium oxide solid solution;

[0109] (3) The titanium oxide solid solution is first heat-treated at 1000° C. for 4 h under vacuum conditions, and then deep deoxidized at 800° C. for 4 h in a pure hydrogen atmosphere using magnesium powder and MgCl2-KCl eutectic salt, wherein the mass ratio of magnesium powder to titanium oxide solid solution is 0.08:1, and the weight ratio of MgCl2-KCl eutectic salt to titanium oxide solid solution is 2.0:1, to obtain a deep deoxidized product;

[0110] The deep deoxidation product is slurried with hydrochloric acid solution at a pH of 0.5, with a liquid-to-solid ratio of 20:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥ 0.8 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 1.8, and filtered, and the obtained solid phase is successively washed with water at 50° C. and dried at 50° C. to obtain metallic titanium powder;

[0111] The metal titanium powder is subjected to a dehydrogenation treatment at 800° C. in an argon atmosphere to obtain the final metal titanium powder.

[0112] Example 2

[0113] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide, the method comprising the following steps:

[0114] (1) mixing a calcium-containing titanium source (calcium oxide mixed with calcined titanium dioxide), aluminum powder and a CaCl2-NaCl eutectic salt, wherein the molar ratio of calcium in the calcium-containing titanium source to the aluminum powder is 1.5:1, the molar ratio of the aluminum powder to the titanium in the calcium-containing titanium source is 1.22:1, and the weight ratio of the CaCl2-NaCl eutectic salt to the titanium in the calcium-containing titanium source as TiO2 is 2.5:1, and sequentially subjecting the mixture to a first reduction in a helium atmosphere at 900°C for 12 hours to obtain a first reduced product;

[0115] The product of the first reduction was slurried with hydrochloric acid at a pH of 0.5, with a liquid-to-solid ratio of 10:1 mL / g, to obtain a slurry; the slurry was successively pH-adjusted, and the pH of the slurry was controlled to be ≥ 0.8 during the pH adjustment. The pH of the slurry after pH adjustment was stabilized at 2.0, and filtered. The obtained solid phase was successively washed with water at 50°C and dried at 50°C to obtain TiO x middle powder;

[0116] (2) the TiO x The intermediate powder was subjected to a second reduction reaction with magnesium powder and MgCl2-NaCl eutectic salt in a helium atmosphere at 700℃ for 10h. x The mass ratio of the intermediate powder is 0.15:1, MgCl2-NaCl eutectic salt and TiO x The weight ratio of the intermediate powder is 2.0:1, and the second reduced product is obtained;

[0117] The product of the second reduction was slurried with hydrochloric acid at a pH of 1.0 at a liquid-to-solid ratio of 30:1 mL / g to obtain a slurry; the slurry was successively pH-adjusted to control the pH of the slurry to be ≥0.9 during the pH adjustment, and the pH of the slurry after pH adjustment was stabilized at 2.5, and filtered, and the obtained solid phase was successively washed with water at 30° C. and dried at 55° C. to obtain a titanium oxide solid solution;

[0118] (3) The titanium oxide solid solution was first heat treated at 900°C for 18 hours in an argon atmosphere, and then deep deoxidized at 650°C for 48 hours using magnesium powder and anhydrous MgCl2 in a hydrogen-argon mixed atmosphere (the volume fraction of hydrogen was 85%), wherein the mass ratio of magnesium powder to titanium oxide solid solution was 0.05:1, and the weight ratio of anhydrous MgCl2 to titanium oxide solid solution was 0.5:1, to obtain a deep deoxidized product;

[0119] The deep deoxidation product is slurried with hydrochloric acid solution at a pH of 1.5 at a liquid-to-solid ratio of 30:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥0.8 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 3.0, and filtered. The obtained solid phase is successively washed with water at 55° C. and dried at 55° C. to obtain metallic titanium powder;

[0120] The metal titanium powder is subjected to a dehydrogenation treatment at 1000° C. in an argon atmosphere to obtain the final metal titanium powder.

[0121] Example 3

[0122] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide, the method comprising the following steps:

[0123] (1) mixing a calcium-containing titanium source (a mixture of a calcined product obtained by mixing calcium oxide and titanium dioxide in a stoichiometric ratio of calcium titanate and calcium oxide), aluminum powder, and anhydrous CaCl2, wherein the molar ratio of calcium in the calcium-containing titanium source to aluminum powder is 0.6:1, the molar ratio of aluminum powder to titanium in the calcium-containing titanium source is 0.67:1, and the weight ratio of anhydrous CaCl2 to titanium in the calcium-containing titanium source as TiO2 is 1.0:1, and sequentially subjecting the mixture to a first reduction at 1100°C for 4 hours under vacuum conditions to obtain a first reduced product;

[0124] The product of the first reduction was slurried with hydrochloric acid solution at a pH of 0.5, with a liquid-to-solid ratio of 10:1 mL / g, to obtain a slurry; the slurry was successively pH-adjusted, and the pH of the slurry was controlled to be ≥ 0.8 during the pH adjustment. The pH of the slurry after pH adjustment was stabilized at 1.5, and filtered. The obtained solid phase was successively washed with water at 0°C and dried at 45°C to obtain TiO x middle powder;

[0125] (2) the TiO x The intermediate powder was subjected to a second reduction with magnesium powder and MgCl2-CaCl2 eutectic salt in an argon atmosphere at 900℃ for 0.25h. x The mass ratio of the intermediate powder is 0.35:1, MgCl2-CaCl2 eutectic salt and TiO x The weight ratio of the intermediate powder is 1.0:1, and the second reduced product is obtained;

[0126] The product of the second reduction is slurried with hydrochloric acid at a pH of 1.0 at a liquid-to-solid ratio of 15:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥1.0 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 1.5, and filtered, and the obtained solid phase is successively washed with water at 25° C. and dried at 40° C. to obtain a titanium oxide solid solution;

[0127] (3) The titanium oxide solid solution is first heat-treated at 1100° C. for 2 h under vacuum conditions, and then deep deoxidized at 1100° C. for 2 h in an argon atmosphere using calcium powder and anhydrous CaCl2, wherein the mass ratio of calcium powder to titanium oxide solid solution is 0.15:1 and the weight ratio of anhydrous CaCl2 to titanium oxide solid solution is 2.0:1, to obtain a deep deoxidized product;

[0128] The deep deoxidation product is slurried with hydrochloric acid solution with a pH of 1.0 and a liquid-to-solid ratio of 10:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted, and the pH of the slurry is controlled to be ≥0.8 during the pH adjustment. The pH of the slurry after pH adjustment is stabilized at 3.0, and is filtered. The obtained solid phase is successively washed with water at 30°C and dried at 60°C to obtain metallic titanium powder.

[0129] Example 4

[0130] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide, the method comprising the following steps:

[0131] (1) mixing a calcium-containing titanium source (calcium oxide mixed with calcined titanium dioxide), aluminum powder and a CaCl2-KCl eutectic salt, wherein the molar ratio of calcium in the calcium-containing titanium source to aluminum powder is 2.0:1, the molar ratio of aluminum powder to titanium in the calcium-containing titanium source is 1.22:1, and the weight ratio of the CaCl2-KCl eutectic salt to titanium in the calcium-containing titanium source as TiO2 is 1.5:1, and sequentially subjecting the mixture to a first reduction at 700°C for 24 hours in a helium atmosphere to obtain a first reduced product;

[0132] The product of the first reduction was slurried in water with a liquid-solid ratio of 100:1 mL / g to obtain a slurry; the slurry was successively pH-adjusted to control the pH of the slurry to be ≥0.8, the pH of the slurry after pH adjustment was stabilized at 3.0, and filtered, and the obtained solid phase was successively washed with water at 60°C and dried at 60°C to obtain TiO x middle powder;

[0133] (2) the TiO x The intermediate powder was reduced for the second time by magnesium powder and MgCl2-KCl eutectic salt in hydrogen atmosphere at 650℃ for 48h. x The mass ratio of the intermediate powder is 0.2:1, MgCl2-KCl eutectic salt and TiO x The weight ratio of the intermediate powder is 3.0:1, and the second reduced product is obtained;

[0134] The product of the second reduction is slurried with hydrochloric acid at a pH of 2.0 at a liquid-solid ratio of 100:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥1.0 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 3.0, and filtered, and the obtained solid phase is successively washed with water at 15° C. and dried at 60° C. to obtain a titanium oxide solid solution;

[0135] (3) The titanium oxide solid solution is first heat-treated at 800° C. for 24 h in an argon atmosphere, and then deep deoxidized at 900° C. for 16 h in a helium atmosphere using calcium powder and CaCl2-LiCl eutectic salt, wherein the mass ratio of calcium powder to titanium oxide solid solution is 0.03:1, and the weight ratio of CaCl2-LiCl eutectic salt to titanium oxide solid solution is 1.0:1, to obtain a deep deoxidized product;

[0136] The deep deoxidation product is slurried with hydrochloric acid solution with a pH of 1.5 and a liquid-to-solid ratio of 40:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted, and the pH of the slurry is controlled to be ≥1.0 during the pH adjustment. The pH of the slurry after pH adjustment is stabilized at 1.5, and is filtered. The obtained solid phase is successively washed with water at 40°C and dried at 45°C to obtain metallic titanium powder.

[0137] Example 5

[0138] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as that of Example 1 except that the CaCl2-KCl eutectic salt is replaced by AlCl3-KCl eutectic salt in step (1).

[0139] Example 6

[0140] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as that of Example 1, except that in step (1), the weight ratio of CaCl2-KCl eutectic salt to titanium in the calcium-containing titanium source calculated as TiO2 is 3.5:1.

[0141] Example 7

[0142] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as that of Example 1, except that in step (1), the weight ratio of the CaCl2-KCl eutectic salt to the titanium in the calcium-containing titanium source calculated as TiO2 is 0.01:1.

[0143] Example 8

[0144] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as that of Example 1 except that the MgCl2-KCl eutectic salt in step (2) is replaced by the CaCl2-KCl eutectic salt.

[0145] Example 9

[0146] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as that of embodiment 1 except that the pure hydrogen atmosphere for deep deoxidation in step (3) is replaced by a helium atmosphere.

[0147] Example 10

[0148] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as that of Example 1 except that the molar ratio of calcium to aluminum powder in the calcium-containing titanium source in step (1) is 0.4:1.

[0149] Example 11

[0150] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as that of Example 1 except that the molar ratio of calcium to aluminum powder in the calcium-containing titanium source in step (1) is 2.5:1.

[0151] Example 12

[0152] This embodiment provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as that of embodiment 1 except that the titanium oxide solid solution is not heat-treated in step (3).

[0153] Comparative Example 1

[0154] This comparative example provides a method for preparing metallic titanium powder by three-stage reduction of titanium dioxide. The method is the same as Example 1 except that the calcium-containing titanium source in step (1) is replaced by a calcium-free titanium source, that is, calcined titanium dioxide is directly used.

[0155] X-ray diffraction analysis was used to measure TiO x The oxygen content in the intermediate powder and titanium oxide solid solution is measured, and the oxygen content of the final metal titanium powder is measured by ONH analyzer method, and the cost of the reducing agent consumed for each ton of metal titanium powder produced is calculated, among which the market price of magnesium is calculated at 40,000 yuan per ton, aluminum is calculated at 20,000 yuan per ton, and calcium is calculated at 45,000 yuan per ton.

[0156] The test and calculation results of the above embodiments and comparative examples are shown in Table 1.

[0157] Table 1

[0158]

[0159] Table 2

[0160]

[0161] “ / ” in the table indicates that there is no relevant data.

[0162] The following points can be seen from Tables 1 and 2:

[0163] (1) Based on Examples 1 to 4, it can be seen that the method for preparing titanium metal powder by aluminum-magnesium stepwise reduction provided by the present invention can produce titanium metal powder with an oxygen content of ≤0.2%, and the cost of the reducing agent can be reduced by RMB 224,340 per ton of titanium metal powder, which is only 56% of the original magnesium reduction cost.

[0164] (2) From Examples 1 and 6 to 7, it can be seen that the present invention can reduce the waste of the first auxiliary agent and avoid the formation of a weakly acid-insoluble aluminum phase by controlling the weight ratio of the first auxiliary agent to the titanium in the calcium-containing titanium source in terms of TiO2 within a specific range, thereby facilitating the subsequent wet separation.

[0165] (3) From Example 1 and Example 8, it can be seen that the magnesium reduction in Example 1 uses a second auxiliary agent containing magnesium. Compared with Example 8 using CaCl2-KCl eutectic salt as the second auxiliary agent, the oxygen content in the titanium oxide solid solution in Example 1 is 4.99 wt%, while the oxygen content in Example 8 is as high as 5.51 wt%. This shows that the present invention improves the reduction effect by using a second auxiliary agent containing magnesium to perform the magnesium reduction step;

[0166] (4) From Example 1 and Example 9, it can be seen that in Example 9, magnesium is used as a deoxidizer in a hydrogen-free atmosphere, and the oxygen content of the final titanium powder is as high as 2.42 wt%. This shows that the present invention significantly improves the deoxidation effect by preferably using magnesium + hydrogen-containing atmosphere for deep deoxidation, and further reduces the oxygen content in the titanium powder;

[0167] (5) From Example 1, Examples 10-11, and Comparative Example 1, it can be seen that the molar ratio of calcium to aluminum powder in the calcium titanium source in Example 1 is 1.5:1, compared with 0.4:1 and 2.5:1 in Examples 10-11, respectively. In Comparative Example 1, which does not contain calcium, the first reduced product in Example 1 can be wet-processed to obtain TiO with x=0.5. x The intermediate powder, while in Comparative Example 1 and Example 10, due to the formation of weakly acid-insoluble aluminum phase, subsequent wet separation is difficult, and in Example 11, there is excess CaO ineffective consumption. This shows that the present invention can effectively ensure that the reduction by-products are soluble in weak acid by controlling the molar ratio of calcium to aluminum powder within a specific range;

[0168] (5) From Example 1 and Example 12, it can be seen that Example 12 does not have a heat treatment step, and it is difficult to form a dense structure, resulting in the oxygen content in the final metal titanium powder being as high as 1.78wt%. This shows that the present invention preferably further reduces the oxygen content in the metal titanium powder through heat treatment.

[0169] While the present invention is described through the above-described embodiments to illustrate the detailed structural features of the present invention, the present invention is not limited to these detailed structural features, nor does it necessarily rely on these detailed structural features for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific embodiments, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing metallic titanium powder by three-stage reduction of titanium dioxide, characterized in that: The method comprises the following steps: (1) Mixing a calcium-containing titanium source, a first reducing agent, and a first auxiliary agent, and sequentially performing a first reduction and a first wet treatment to obtain TiO x Intermediate powder, wherein 0.167 < x ≤ 1, and the first reducing agent includes aluminum; (2) the TiO x The intermediate powder is subjected to a second reduction with a second reducing agent, and then subjected to a second wet process to obtain a titanium oxide solid solution, wherein the oxygen content in the titanium oxide solid solution is ≤2wt%, and the second reducing agent includes magnesium; (3) The titanium oxide solid solution is deeply deoxidized by a deoxidizer, and then subjected to a third wet treatment to obtain metallic titanium powder, wherein the deoxidizer includes magnesium and / or calcium; The molar ratio of calcium to the first reducing agent in the calcium-containing titanium source in step (1) is 0.6 to 2:1; The weight ratio of the first auxiliary agent to the titanium in the calcium-containing titanium source calculated as TiO2 is 0.05 to 3:

1.

2. The method according to claim 1, characterized in that The molar ratio of the first reducing agent to titanium in the calcium-containing titanium source is 0.67 to 1.30:

1.

3. The method according to claim 1 or 2, characterized in that In step (1), the first auxiliary agent includes any one of anhydrous CaCl2, KCl, NaCl, CaCl2-KCl eutectic salt, CaCl2-NaCl eutectic salt, CaCl2-LiCl eutectic salt, KCl-NaCl eutectic salt, LiCl-NaCl eutectic salt, LiCl-KCl eutectic salt, AlCl3-KCl eutectic salt or AlCl3-NaCl eutectic salt, or a combination of at least two thereof.

4. The method according to claim 1, wherein The first reducing agent may be in a powdery, crumbly or granular form, or in a combination of at least two of the forms.

5. The method according to claim 1, wherein The temperature of the first reduction in step (1) is 700-1100°C.

6. The method according to claim 1, characterized in that The first reduction time is 0.5 to 24 hours.

7. The method according to claim 1, characterized in that The first reducing atmosphere includes vacuum or protective atmosphere.

8. The method according to claim 1, characterized in that The first reducing protective atmosphere includes any one of argon, hydrogen or helium, or a combination of at least two of them.

9. The method according to claim 1, characterized in that The first wet treatment in step (1) includes: slurrying the product of the first reduction with water and / or acid solution to obtain slurry; adjusting the pH of the slurry and performing solid-liquid separation in sequence, and washing and drying the obtained solid phase in sequence to obtain TiO x Middle powder.

10. The method according to claim 9, characterized in that The second wet treatment in step (2) includes: slurrying the second reduced product with water and / or acid solution to obtain a slurry; adjusting the pH of the slurry and performing solid-liquid separation in sequence, and washing and drying the obtained solid phase in sequence to obtain a titanium oxide solid solution.

11. The method according to claim 10, characterized in that The third wet treatment in step (3) includes: slurrying the deep deoxidized product with water and / or acid solution to obtain a slurry; adjusting the pH of the slurry and performing solid-liquid separation in sequence, and washing and drying the obtained solid phase in sequence to obtain metallic titanium powder.

12. The method according to claim 11, characterized in that The pH of the acid solution in the first wet treatment, the second wet treatment and the third wet treatment is independently ≥0.

5.

13. The method according to claim 11, characterized in that The liquid-to-solid ratio of the slurry in the first wet treatment, the second wet treatment, and the third wet treatment is independently 1 to 100:1 mL / g.

14. The method according to claim 11, characterized in that The acid used for pH adjustment in the first wet treatment, the second wet treatment and the third wet treatment is independently hydrochloric acid.

15. The method according to claim 11, characterized in that The pH of the slurry is independently controlled to be ≥ 0.8 during the pH adjustment in the first wet treatment, the second wet treatment and the third wet treatment.

16. The method according to claim 11, characterized in that The pH of the slurry after pH adjustment in the first wet treatment, the second wet treatment, and the third wet treatment is independently 1.5 to 3.

0.

17. The method according to claim 11, characterized in that The washing temperatures in the first wet treatment, the second wet treatment and the third wet treatment are each independently 0 to 60°C.

18. The method according to claim 11, characterized in that The drying temperatures in the first wet treatment, the second wet treatment, and the third wet treatment are each independently ≤ 60°C.

19. The method according to claim 1, wherein In step (2), the second reducing agent and TiO x The mass ratio of the intermediate powder is 0.09 to 0.56:

1.

20. The method according to claim 1, wherein The second reducing agent may be in a powdery, crumbly or granular form, or in a combination of at least two of the forms.

21. The method according to claim 1, wherein A second auxiliary agent is added during the second reduction.

22. The method according to claim 21, characterized in that The second auxiliary agent includes any one of anhydrous MgCl2, MgCl2-CaCl2 eutectic salt, MgCl2-NaCl eutectic salt or MgCl2-KCl eutectic salt, or a combination of at least two thereof.

23. The method according to claim 21, characterized in that The second auxiliary agent and TiO x The weight ratio of the intermediate powder is 0.05 to 3:

1.

24. The method according to claim 1, wherein The temperature of the second reduction is 650-900°C.

25. The method according to claim 1, wherein The second reduction time is 0.25 to 48 hours.

26. The method according to claim 1, wherein The second reducing protective atmosphere includes any one of argon, hydrogen or helium, or a combination of at least two of them.

27. The method according to claim 1, wherein The deoxidizer in step (3) may be in the form of powder, crumbs or granules, or a combination of at least two of the above.

28. The method according to claim 1, wherein A third auxiliary agent is added during the deep deoxidation.

29. The method according to claim 28, characterized in that When the deoxidizer contains magnesium, the mass ratio of magnesium to titanium oxide solid solution is 0.03 to 0.2:

1.

30. The method according to claim 29, wherein When the deoxidizer contains magnesium, the third auxiliary agent includes any one of anhydrous MgCl2, MgCl2-CaCl2 eutectic salt, MgCl2-NaCl eutectic salt or MgCl2-KCl eutectic salt, or a combination of at least two thereof.

31. The method according to claim 30, wherein When the deoxidizer contains magnesium, the weight ratio of the third auxiliary agent to the titanium oxide solid solution is 0.05 to 3:

1.

32. The method according to claim 30, wherein When the deoxidizer contains magnesium, the temperature of the deep deoxidation is 650-900°C.

33. The method according to claim 30, wherein When the deoxidizer contains magnesium, the deep deoxidation time is 0.25 to 48 hours.

34. The method according to claim 30, wherein When the deoxidizer contains magnesium, the deep deoxidation atmosphere includes a hydrogen-argon mixed atmosphere or a pure hydrogen atmosphere.

35. The method according to claim 34, wherein The volume fraction of hydrogen in the hydrogen-argon mixed atmosphere is 5 to 100%.

36. The method according to claim 28, wherein When the deoxidizer contains calcium, the mass ratio of calcium to titanium oxide solid solution is 0.05-0.4:

1.

37. The method according to claim 28, wherein When the deoxidizer contains calcium, the third auxiliary agent includes any one of anhydrous CaCl2, CaCl2-MgCl2 eutectic salt, CaCl2-NaCl eutectic salt, CaCl2-KCl eutectic salt or CaCl2-LiCl eutectic salt, or a combination of at least two thereof.

38. The method according to claim 28, wherein When the deoxidizer contains calcium, the weight ratio of the third auxiliary agent to the titanium oxide solid solution is 0.05 to 3:

1.

39. The method according to claim 28, wherein When the deoxidizer contains calcium, the temperature of the deep deoxidation is 700-1100°C.

40. The method according to claim 28, wherein When the deoxidizer contains calcium, the deep deoxidation time is 0.25 to 48 hours.

41. The method according to claim 28, wherein When the deoxidizer contains calcium, the deep deoxidation atmosphere includes vacuum or protective atmosphere.

42. The method according to claim 41, wherein The deep deoxidation protective atmosphere includes any one of argon, hydrogen or helium, or a combination of at least two of them.

43. The method according to claim 1, wherein The method further includes: performing a heat treatment on the titanium oxide solid solution between the second wet treatment and the deep deoxidation.

44. The method according to claim 43, wherein The temperature of the heat treatment is 750-1100°C.

45. The method according to claim 43, wherein The heat treatment time is 0.167 to 24 hours.

46. The method according to claim 43, wherein The atmosphere of the heat treatment includes vacuum or protective atmosphere.

47. The method according to claim 43, wherein The protective atmosphere for the heat treatment includes any one of hydrogen, argon or helium, or a combination of at least two of them.

48. The method according to claim 1, wherein The method further comprises: subjecting the metallic titanium powder obtained by the third wet treatment in step (3) to dehydrogenation treatment.

49. The method according to claim 48, characterized in that The temperature of the dehydrogenation treatment is 500-1000°C.

50. The method according to claim 48, wherein The atmosphere of the dehydrogenation treatment includes vacuum or protective atmosphere.

51. The method according to claim 48, wherein The protective atmosphere of the dehydrogenation treatment includes argon and / or helium.

52. The method according to claim 1, wherein The method comprises the following steps: (1) mixing a calcium-containing titanium source, a first reducing agent, and a first auxiliary agent, wherein the molar ratio of calcium in the calcium-containing titanium source to the first reducing agent is 0.6-2:1, the molar ratio of the first reducing agent to titanium in the calcium-containing titanium source is 0.67-1.30:1, and the weight ratio of the first auxiliary agent to titanium in the calcium-containing titanium source as TiO2 is 0.05-3:1, and sequentially subjecting the mixture to a first reduction at 700-1100°C for 0.5-24h in vacuum or protective atmosphere to obtain a first reduced product; The product of the first reduction is slurried with water and / or an acid solution with a pH value of ≥0.5, with a liquid-solid ratio of 1 to 100:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥0.8 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 1.5 to 3.0, and solid-liquid separation is performed, and the obtained solid phase is successively washed at 0 to 60°C and dried at ≤60°C to obtain TiO x Intermediate powder, where 0.167<x≤1; (2) the TiO x The intermediate powder is subjected to a second reduction agent and a second auxiliary agent in a protective atmosphere at 650-900°C for 0.25-48h. The second reducing agent and TiO x The mass ratio of the intermediate powder is 0.09-0.56:1, the second auxiliary agent and TiO x The weight ratio of the intermediate powder is 0.05 to 3:1, and the second reduced product is obtained; The product of the second reduction is slurried with water and / or an acid solution with a pH of ≥0.5, with a liquid-solid ratio of 1 to 100:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted, wherein the pH of the slurry is controlled to be ≥0.8 during the pH adjustment, and the pH of the slurry after pH adjustment is stabilized at 1.5 to 3.0, and solid-liquid separation is performed, and the obtained solid phase is successively washed at 0 to 60° C. and dried at ≤60° C. to obtain a titanium oxide solid solution; (3) The titanium oxide solid solution is first heat-treated at 750-1100° C. for 0.167-24 h under vacuum or protective atmosphere, and then deeply deoxidized under the action of a deoxidizer and a third auxiliary agent to obtain a deeply deoxidized product; The deep deoxidation product is slurried with water and / or acid solution with a pH value of ≥0.5, with a liquid-solid ratio of 1 to 100:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted, during which the pH value of the slurry is controlled to be ≥0.8, and the pH value of the slurry after pH adjustment is stabilized at 1.5 to 3.0, and solid-liquid separation is performed, and the obtained solid phase is successively washed at 0 to 60°C and dried at ≤60°C to obtain metallic titanium powder.

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