A low-valent titanium oxide compound TiO with controllable oxygen content x Preparation method

Abstract

The present invention provides a low-valent titanium oxide compound TiO with controllable oxygen content. x The preparation method comprises the following steps: (1) mixing a calcium-containing titanium source, a reducing agent and a reducing auxiliary agent, and performing a reduction treatment to obtain a reduced material; (2) performing a wet treatment on the reduced material to obtain TiO x The reducing agent includes aluminum powder, the TiO x The value range of x is 0.167≤x≤1. The present invention can accurately control the amount of oxygen removed from titanium dioxide by introducing calcium-containing substances into the titanium source and using aluminum powder as a reducing agent in combination, and the reduced material after reduction treatment can be removed by simple wet treatment to obtain high-purity titanium oxide, which provides a theoretical and practical basis for preparing low-valent titanium oxide with a specific oxygen content.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium oxide preparation, and in particular to a low-valent titanium oxide compound TiO x Preparation method. Background Art

[0002] Titanium oxide can not only provide excellent raw materials for the subsequent preparation of titanium powder, but also has special functions, such as photocatalytic performance, light-absorbing materials, etc. It is generally difficult to prepare low-valent titanium titanium oxide by direct reduction of the most common titanium oxide TiO2, mainly because the oxygen / titanium ratio, that is, the oxygen content in titanium oxide, is poorly controllable.

[0003] The traditional preparation method of titanium oxide is generally to prepare titanium oxide by compounding and sintering TiO2 and Ti powder, which consumes titanium powder and is costly. Some studies have involved the preparation of titanium oxide by reducing TiO2.

[0004] For example, CN107236869B discloses a method for preparing titanium powder by multi-stage deep reduction, which involves preparing low-valent titanium oxide by a self-propagating method, specifically comprising mixing dried TiO2 powder and magnesium powder evenly, adding them to a self-propagating reactor, inducing a self-propagating reaction, and obtaining low-valent titanium oxide Ti dispersed in a MgO matrix. x O intermediate product, the intermediate product is leached with hydrochloric acid as the leaching liquid, and filtered, washed, and vacuum dried to obtain low-valent titanium oxide Ti x O precursor; however, the Ti x The titanium valence state of O is still relatively high, and the reduction cost is high when magnesium is used as a reducing agent.

[0005] CN104120304A discloses a method for preparing titanium-aluminum alloy based on aluminum heat self-propagation-injection deep reduction, which uses titanium oxide and aluminum powder as raw materials, obtains a high-temperature melt through a self-propagation reaction, but the product is a titanium-aluminum alloy, and the titanium and aluminum in the alloy cannot be further separated by a wet method to obtain low-valent titanium oxide.

[0006] Therefore, it is necessary to develop a low-cost method for preparing low-valent titanium from TiO2. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a low-valent titanium oxide compound TiO x The preparation method has a simple process, the oxygen content in the final product can be accurately controlled through the aforementioned operation steps, the product purity is high, and compared with the magnesium thermal self-propagation method, aluminum can be used as a reducing agent, the cost is significantly reduced, and the application prospect is broad.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a low-valent titanium oxide compound TiO with controllable oxygen content. x A preparation method, the preparation method comprising the following steps:

[0010] (1) mixing a calcium-containing titanium source, a reducing agent and a reducing auxiliary agent, and performing a reduction treatment to obtain a reducing material;

[0011] (2) The reduced material is treated by a wet method to obtain TiO x ;

[0012] The reducing agent includes aluminum powder, the TiO x The value range of x is 0.167≤x≤1, for example, it can be 0.167, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.25, 0.30, 0.35, 0.34, 0.38, 0.4, 0.45, 0.5, 0.55, 0.6, 0.7, 0.8, 0.9 or 1.0, etc.

[0013] The present invention creatively discovered that in the presence of calcium-containing substances and reduction auxiliary agents, the byproduct Al2O3 of aluminum reduction of TiO2 can be converted into a calcium-aluminum compound that is easily soluble in dilute acid. On the one hand, the chemical composition of the reduction byproduct phase is changed, especially the formation of substances with more negative Gibbs free energy, and on the premise that no titanium-aluminum alloy phase is generated, the reaction "Al+TiO2→TiO x +Al2O3" original equilibrium state (to ensure that 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 , and through precise control of the titanium / aluminum ratio, TiO x The oxygen content in the slag can be controlled; on the other hand, the controlled generation of this calcium-aluminum compound that is easily soluble in dilute acid can transform the conventional slag-metal stratification physical separation method caused by self-propagating ultra-high temperature reaction into wet separation, which is more thorough and can obtain higher purity TiO x .

[0014] In addition, in terms of reducing agent costs, since aluminum has 3 electrons and magnesium has only 2 electrons, the mass of aluminum powder required to remove the same amount of oxygen is 75% of that of magnesium powder, and the price of metallic aluminum is approximately only half of that of metallic magnesium, so the reducing agent cost can be saved by up to 62.5%.

[0015] The theoretical calculation formula for controlling the oxygen content in the present invention is Al+TiO2→TiO x+Al2O3. Although the present invention adopts the above theoretical calculation formula to basically determine the amount of reducing agent and its corresponding low-valent titanium oxide composition, what is obtained in the actual reduction treatment is a calcium-aluminum compound that is easily soluble in dilute acid.

[0016] Preferably, the calcium-containing titanium source in step (1) is in powder form.

[0017] Preferably, the calcium-containing titanium source in step (1) comprises 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 obtained by mixing calcium oxide and titanium dioxide in a stoichiometric ratio of CaTiO3 and calcium oxide, and the fourth titanium source is a mixture obtained by mixing calcium oxide and titanium dioxide in a stoichiometric ratio exceeding CaTiO3 and calcining.

[0018] The present invention can use a mixture of calcium oxide and titanium dioxide configured in a CaTiO3 stoichiometric ratio and then mix it with calcium oxide as a calcium-containing titanium source, or can use a mixture of calcium oxide and titanium dioxide calcined in an amount exceeding the CaTiO3 stoichiometric ratio as a calcium-containing titanium source.

[0019] The present invention further preferably uses calcined materials, which can further avoid the agglomeration of fine TiO2 in the subsequent mixing process.

[0020] Preferably, the calcination temperature of the second titanium source, the third titanium source or the fourth titanium source in step (1) is independently 1000-1400°C, for example, it can be 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C or 1400°C, etc.

[0021] Preferably, the molar ratio of calcium to reducing agent in the titanium source in step (1) is 0.6 to 2:1, for example, it can be 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.5:1, 1.8:1, 1.9:1 or 2.0:1, etc.

[0022] Preferably, the molar ratio of the reducing agent to titanium in the titanium source is 0.67 to 1.33:1, for example, it can be 0.67:1, 0.68:1, 0.7:1, 0.72:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1 or 1.33:1, etc.

[0023] The present invention further preferably has the ratio of reducing agent, calcium and titanium in the titanium source within the above range, which can ensure that the reduction byproduct is a calcium-aluminum compound that is easily soluble in dilute acid, and ensure that TiO x The acid separation of the reduction by-products can effectively control x in the final titanium oxide within the range of 0.167 to 1.

[0024] Preferably, the reduction auxiliary agent in step (1) comprises any one of anhydrous CaCl2, KCl, NaCl, CaCl2-KCl eutectic salt, CaCl2-NaCl eutectic salt, CaCl2-LiCl eutectic salt, KCl-NaCl eutectic salt, AlCl3-KCl eutectic salt, AlCl3-LiCl 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 and KCl, a combination of CaCl2 and NaCl, a combination of CaCl2 and CaCl2-KCl eutectic salt, a combination of CaCl2-LiCl2 eutectic salt and KCl-NaCl eutectic salt, a combination of AlCl3-KCl eutectic salt and KCl, and a combination of AlCl3-NaCl eutectic salt and KCl.

[0025] The present invention further preferably uses a calcium-containing reduction auxiliary agent, because the calcium-containing molten reduction auxiliary agent has the function of dissolving calcium oxide, thereby promoting the full chemical reaction of aluminum oxide and calcium oxide generated by aluminum reduction of TiO2.

[0026] Preferably, the weight ratio of the reduction auxiliary agent to the titanium in the titanium source in terms of TiO2 is 0.05 to 3:1, for example, it can be 0.05:1, 0.1:1, 0.2:1, 0.5:1, 1.0:1, 1.5:1, 2.0:1, 2.5:1 or 3.0:1, etc.

[0027] Preferably, the temperature of the reduction treatment in step (1) is 700-1400°C, for example, it can be 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C or 1400°C, etc.

[0028] Preferably, the reduction treatment time is 0.25 to 24 h, for example, it can be 0.25 h, 0.5 h, 1 h, 1.2 h, 1.5 h, 2.0 h, 3 h, 4 h, 5 h, 6 h, 10 h, 12 h, 15 h, 18 h, 20 h or 24 h.

[0029] Preferably, the atmosphere of the reduction treatment in step (1) includes a vacuum or protective atmosphere.

[0030] Preferably, the 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 wet treatment in step (2) comprises: slurrying the reducing material with water and / or acid solution to obtain slurry; adjusting the pH of the slurry and performing solid-liquid separation in sequence, washing and drying the obtained solid phase to obtain TiO x .

[0032] Preferably, the pH of the acid solution in step (2) is ≥ 0.5, for example, it can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.5, 2.0, 2.5, 3.0, 3.5 or 4.0, etc.

[0033] Preferably, the liquid-to-solid ratio of the slurry is 1 to 100:1 mL / g, for example, it can be 1:1 mL / g, 2:1 mL / g, 4:1 mL / g, 5:1 mL / g, 10:1 mL / g, 15:1 mL / g, 20:1 mL / g, 25:1 mL / g, 30:1 mL / g, 40:1 mL / g, 50:1 mL / g, 60:1 mL / g, 70:1 mL / g, 80:1 mL / g, 90:1 mL / g or 100:1 mL / g, etc.

[0034] Preferably, the acid used in the pH adjustment comprises hydrochloric acid.

[0035] Preferably, in the pH adjustment, the pH of the slurry is controlled to be ≥ 0.8, for example, it can be 0.8, 0.85, 0.9, 0.95, 1.0, 1.2, 1.5, 1.8, 2.0, 2.2, 2.5 or 3.0.

[0036] Preferably, the pH of the slurry after pH adjustment is 1.5 to 3.0, for example, it may be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.2, 2.3, 2.5, 2.8 or 3.0.

[0037] Preferably, the washing temperature is 0-60°C, for example, it can be 0°C, 1°C, 2°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, etc.

[0038] Preferably, the drying temperature is ≤60°C, for example, it may be 60°C, 55°C, 50°C, 45°C, 40°C, 35°C, 30°C, 28°C or 20°C.

[0039] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0040] (1) mixing a calcium-containing titanium source, a reducing agent and a reducing auxiliary agent, wherein the molar ratio of calcium in the titanium source to the reducing agent is 0.6 to 2:1, the molar ratio of the reducing agent to titanium in the titanium source is 0.67 to 1.33:1, and the weight ratio of the reducing auxiliary agent to titanium in the titanium source in terms of TiO2 is 0.05 to 3:1, and performing a reducing treatment at 700 to 1400° C. for 0.25 to 24 hours in a vacuum or protective atmosphere to obtain a reducing material;

[0041] (2) The reducing material is slurried with water and / or an acid solution with a pH value of ≥0.5, wherein the liquid-to-solid ratio of the slurry is 1 to 100:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted with hydrochloric acid to a pH value of 1.5 to 3.0, and solid-liquid separation is performed, and the obtained solid phase is washed and dried at ≤60°C to obtain TiO x ;

[0042] The reducing agent includes aluminum powder, the TiO x The value range of x is 0.167≤x≤1.

[0043] The present invention has no special 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, such as filtration, centrifugation or sedimentation separation, or a combination of different methods.

[0044] The present invention has no particular limitation on the drying in the above process. Any drying device and method 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 air drying, vacuum drying, oven drying or freeze drying, or a combination of different methods.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects:

[0046] (1) The low-valent titanium oxide compound TiO with controllable oxygen content provided by the present invention x The preparation method uses aluminum as a reducing agent. Compared with magnesium reducing agent, the reducing agent cost is significantly reduced, wherein the reducing agent cost can be saved by up to 62.5%;

[0047] (2) The low-valent titanium oxide compound TiO with controllable oxygen content provided by the present invention x Compared with the self-propagating method, the reduction reaction system temperature is lower, the equipment requirements are reduced, and the controllability of the oxygen content of the final product is significantly improved. Within the preferred range, the mean square error of x repeated 5 times is within the range of 0.0084, and the range is ≤0.03;

[0048] (3) The low-valent titanium oxide compound TiO with controllable oxygen content provided by the present invention xThe preparation method can realize the preparation of titanium oxide through two steps of reduction treatment and wet treatment. The process is simple and controllable, and the application prospect is broad. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The present invention provides a low-valent titanium oxide compound TiO with controllable oxygen content. x Schematic diagram of the preparation method. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0051] The present invention is further described in detail below. However, the following examples are only 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.

[0052] As a specific embodiment of the present invention, a low-valent titanium oxide compound TiO with controllable oxygen content is provided. x The preparation method, the flow chart of which is as follows Figure 1 As shown, the preparation method comprises the following steps:

[0053] (1) mixing a calcium-containing titanium source, a reducing agent and a reducing auxiliary agent, and performing a reduction treatment at 700 to 1400° C. for 0.25 to 24 hours in a vacuum or protective atmosphere to obtain a reducing material;

[0054] The calcium-containing titanium source comprises 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, wherein 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 CaTiO3 and calcium oxide obtained by mixing titanium dioxide and calcium oxide in a stoichiometric ratio of CaTiO3 and calcining, and the fourth calcium source is a mixture of calcium oxide and titanium dioxide mixed in a stoichiometric ratio exceeding CaTiO3 and calcined;

[0055] (2) The reduced material is further subjected to wet treatment, wherein the wet treatment comprises slurrying the reduced material with water and / or acid solution to obtain slurry; the slurry is successively subjected to pH adjustment and solid-liquid separation, and the obtained solid phase is washed and dried to obtain TiO x ;

[0056] The reducing agent includes aluminum powder, the TiO x The value range of x is 0.167≤x≤1.

[0057] Example 1

[0058] This embodiment provides a low-valent titanium oxide compound TiO with controllable oxygen content. xA preparation method, the preparation method comprising the following steps:

[0059] (1) mixing a calcium-containing titanium source (a mixture of titanium dioxide and calcium oxide), aluminum powder and CaCl2-NaCl eutectic salt, and reducing them at 1200° C. for 2 h in an argon atmosphere to obtain a reduced material;

[0060] (2) The reducing material is slurried in water, and the liquid-to-solid ratio of the slurry is 50:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted with hydrochloric acid, and the pH of the slurry is controlled to be ≥ 0.8 during the pH adjustment process, and the pH of the slurry is adjusted to 2.0 and filtered, and the obtained solid phase is washed with water at 25° C. and dried at 55° C. to obtain TiO x ;

[0061] The TiO x The value range of x can be controlled within the range of 0.167≤x≤1 according to the amount of calcium oxide, aluminum powder and reducing auxiliary agent added.

[0062] The specific amounts of calcium oxide, aluminum powder and CaCl2-NaCl eutectic salt added in this embodiment, the corresponding final x values ​​and the experimental conditions are shown in Table 1.

[0063] Table 1

[0064]

[0065] Example 2

[0066] This embodiment provides a low-valent titanium oxide compound TiO with controllable oxygen content. x A preparation method, the preparation method comprising the following steps:

[0067] (1) mixing a calcium-containing titanium source (a mixture of calcium oxide and titanium dioxide calcined at 1300° C. for 3 h), aluminum powder and CaCl2-NaCl eutectic salt, and performing reduction treatment at 700° C. for 24 h under vacuum conditions (absolute vacuum degree 80 kPa) to obtain a reduced material;

[0068] (2) The reducing material is slurried with hydrochloric acid at a pH of 1.2, and the liquid-to-solid ratio of the slurry is 10:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted with hydrochloric acid, and the pH of the slurry is controlled to be ≥ 0.8 during the pH adjustment process, and the slurry is adjusted to a pH of 2.0 and filtered, and the obtained solid phase is washed with water at 25° C. and dried at 60° C. to obtain TiO x ;

[0069] The TiO x The value range of x can be controlled within the range of 0.167≤x≤1 according to the amount of calcium oxide, aluminum powder and reducing auxiliary agent CaCl2-NaCl eutectic salt added.

[0070] The specific amounts of calcium oxide, aluminum powder and CaCl2-NaCl eutectic salt added in this embodiment and the corresponding final values ​​of x are shown in Table 2.

[0071] Table 2

[0072]

[0073] Example 3

[0074] This embodiment provides a low-valent titanium oxide compound TiO with controllable oxygen content. x A preparation method, the preparation method comprising the following steps:

[0075] (1) mixing a calcium-containing titanium source (a mixture of calcium oxide and titanium dioxide mixed in a stoichiometric ratio of CaTiO3, calcined at 1400°C for 3h, and then mixed with calcium oxide), aluminum powder and CaCl2, and reducing them at 1400°C for 0.25h in a hydrogen atmosphere to obtain a reduced material;

[0076] (2) The reducing material is slurried with hydrochloric acid at a pH of 2.0, and the liquid-to-solid ratio of the slurry is 100:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted with hydrochloric acid, and the pH of the slurry is controlled to be ≥ 0.8 during the pH adjustment process, and the pH of the slurry is adjusted to 1.5 and filtered, and the obtained solid phase is washed with water at 25° C. and dried at 25° C. to obtain TiO x ;

[0077] The TiO x The value range of x can be controlled within the range of 0.167≤x≤1 according to the amount of calcium oxide, aluminum powder and reducing auxiliary agent CaCl2 added.

[0078] The specific amounts of calcium oxide, aluminum powder and CaCl2 added in this embodiment and the corresponding final values ​​of x are shown in Table 3.

[0079] Table 3

[0080]

[0081] Example 4

[0082] This embodiment provides a low-valent titanium oxide compound TiO with controllable oxygen content. x A preparation method, the preparation method comprising the following steps:

[0083] (1) mixing a calcium-containing titanium source (a product obtained by mixing calcium oxide and titanium dioxide in a stoichiometric ratio exceeding CaTiO3 and then calcining at 1200°C for 8 hours), aluminum powder and CaCl2-KCl eutectic salt, and performing reduction treatment at 1000°C for 8 hours in a mixed atmosphere of hydrogen and helium (molar ratio of 1:1) to obtain a reduced material;

[0084] (2) The reducing material is slurried with hydrochloric acid at a pH of 1.0, and the liquid-to-solid ratio of the slurry is 5:1 mL / g to obtain a slurry; the slurry is successively pH-adjusted with hydrochloric acid, and the pH of the slurry is controlled to be ≥ 0.8 during the pH adjustment process, and the pH of the slurry is adjusted to 2.5 and filtered, and the obtained solid phase is washed with water at 0°C and dried at 45°C to obtain TiO x ;

[0085] The TiO x The value range of x can be controlled within the range of 0.167≤x≤1 according to the amount of calcium oxide, aluminum powder and reducing auxiliary agent CaCl2-KCl eutectic salt added.

[0086] The specific amounts of calcium oxide, aluminum powder and CaCl2-KCl eutectic salt added in this embodiment and the corresponding final values ​​of x are shown in Table 4.

[0087] Table 4

[0088]

[0089] Example 5

[0090] This embodiment provides a low-valent titanium oxide compound TiO with controllable oxygen content. x A preparation method, which is the same as Example 1 except that the reducing auxiliary agent is replaced by NaCl. The results are shown in Table 5.

[0091] Table 5

[0092]

[0093] Comparative Example 1

[0094] This comparative example provides a titanium oxide compound TiO x A preparation method, in which the conditions are the same as those in Example 1 except that the aluminum powder is replaced by magnesium powder in an equal molar ratio. The results are shown in Table 6.

[0095] Table 6

[0096]

[0097] Comparative Example 2

[0098] This comparative example provides a titanium oxide compound TiO x A preparation method, wherein the preparation method has the same conditions as Example 2 except that the titanium source does not contain calcium, and the results are shown in Table 7.

[0099] Table 7

[0100]

[0101] Comparative Example 3

[0102] This comparative example provides a titanium oxide compound TiO x A preparation method, wherein the preparation method adopts a self-propagating method, and the specific method comprises the following steps: TiO2, reducing agent Al powder, combustion aid KClO4, and CaO additive are fully mixed according to a certain amount and placed in a stainless steel cup (wherein Al / TiO2=1.33) for half an hour, and then the above steel cup is placed in a high-pressure container filled with argon gas, and the self-propagating reaction is excited by the nickel-chromium filament on the surface above the cup, and the reaction is rapid, releasing a large amount of heat to cause the system temperature to rise sharply, melting the reaction product, and then the slag and the metal titanium realize a self-separation process, and finally obtain TiO with x=0.35 x Titanium oxide ingots.

[0103] Taking the methods of Example 1-1, Example 1-4, Example 1-5, Example 1-7, Example 1-8, Example 4-2, Example 5-1 and Comparative Example 3 as examples, the stability of the product components in different methods was explored, that is, each method was repeated 5 times, and the stability of the product components in the method was investigated according to the low-valent titanium oxide TiO x The oxygen content in the product was used to calculate the value of x in the final product. The results are shown in Table 8.

[0104] Table 8

[0105]

[0106] In Tables 1 to 8, “ / ” indicates that the data is not available.

[0107] From Tables 1 to 8, we can see the following points:

[0108] (1) Based on Examples 1 to 4, it can be seen that the low-valent titanium oxide compound TiO with controllable oxygen content provided by the present invention x The preparation method can better control the low-valent titanium oxide TiO x The oxygen content in the solution is in the range of 0.0084 and the range is ≤0.03. x +Al2O3 effectively controls x between 0.167≤x≤1, achieving precise control of the oxygen content in low-valent titanium oxide;

[0109] (2) It can be seen from Example 1-1 and Example 5-1 that in Example 1-1, CaCl2-NaCl eutectic salt is used as a reduction auxiliary agent. Compared with Example 5-1, in which NaCl is used as a reduction auxiliary agent, under the same ratio, the value of x in Example 1-1 is only 0.99, while the value of x in Example 5-1 is as high as 1.19, and the mean square error is as high as 0.0228, the range is as high as 0.06, and the oxygen content control effect is reduced. This shows that the present invention can better promote the reduction by preferably using a calcium-containing reduction auxiliary agent, and improve the reduction effect and the oxygen content control effect;

[0110] (3) Combining Example 1 and Comparative Example 1, it can be seen that in Example 1, by using aluminum reduction, the value of x in Examples 1-5 can be as low as 0.167 at the same amount of reducing agent added, while in Comparative Example 1, by using magnesium reduction, a composite material of MgO and low-valent titanium oxide is generated, and it is difficult to obtain titanium oxide TiO x , which shows that the present invention is more conducive to controlling TiO by optimizing aluminum reduction x Medium x value and easy to separate by wet method;

[0111] (4) It can be seen from Example 1 and Comparative Examples 2 to 3 that in Example 1, aluminum reduction is carried out under the condition of adding calcium oxide. Compared with Comparative Example 2 in which no calcium oxide is added and Comparative Example 3 is reduced by self-propagating method, Example 1 can perform wet separation, thereby achieving precise control of oxygen content, with a mean square error of only 0.0084 and a range of only 0.02. Although Comparative Example 2 adopts a reduction method similar to that of Example 1, wet separation cannot be adopted. In Comparative Example 3, the self-propagating method is subsequently separated by slag metal, and the oxygen content is difficult to control. The mean square error of 5 repetitions is as high as 0.0308, and the range is as high as 0.08. This shows that the present invention converts the byproduct Al2O3 of aluminum reduction of TiO2 into a calcium-aluminum compound that is easily dissolved by wet separation under the action of calcium-containing substances and reduction auxiliary agents, and can obtain low-valent titanium oxide by wet separation, and the oxygen content is more controllable and the cost of reducing agent is significantly reduced.

[0112] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A low-valent titanium oxide compound TiO with controllable oxygen content x The preparation method is characterized in that The preparation method comprises the following steps: (1) mixing a calcium-containing titanium source, a reducing agent, and a calcium-containing molten reduction auxiliary agent, and performing a reduction treatment to obtain a reducing material; The molar ratio of calcium in the titanium source to the reducing agent is 0.6 to 2:1; the molar ratio of the reducing agent to titanium in the titanium source is 0.67 to 1.33:1; (2) The reduced material is treated by a wet method to obtain TiO x ; The reducing agent includes aluminum powder, the TiO x The value range of x is 0.167≤x≤1.

2. The preparation method according to claim 1, characterized in that: 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 obtained by mixing calcium oxide and titanium dioxide in a stoichiometric ratio of CaTiO3 and calcium oxide, and the fourth titanium source is a mixture obtained by mixing calcium oxide and titanium dioxide in a stoichiometric ratio exceeding CaTiO3 and calcining.

3. The preparation method according to claim 2, characterized in that: In step (1), the calcination temperature of the second titanium source, the third titanium source or the fourth titanium source is independently 1000-1400°C.

4. The preparation method according to claim 1, characterized in that: The reduction auxiliary agent in step (1) includes any one of CaCl2-KCl eutectic salt, CaCl2-NaCl eutectic salt or CaCl2-LiCl eutectic salt, or a combination of at least two thereof.

5. The preparation method according to claim 1, characterized in that: The weight ratio of the calcium-containing molten reduction auxiliary agent to the titanium in the titanium source in terms of TiO2 is 0.05 to 3:

1.

6. The preparation method according to claim 1, characterized in that: The temperature of the reduction treatment in step (1) is 700-1400°C.

7. The preparation method according to claim 1, characterized in that: The reduction treatment time is 0.25 to 24 hours.

8. The preparation method according to claim 1, characterized in that: The atmosphere for the reduction treatment in step (1) includes a vacuum or protective atmosphere.

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

10. The preparation method according to claim 1, characterized in that: The wet treatment in step (2) comprises: slurrying the reducing material with water and / or acid solution to obtain slurry; adjusting the pH of the slurry and performing solid-liquid separation in sequence, washing and drying the obtained solid phase to obtain TiO x .

11. The preparation method according to claim 10, characterized in that: The pH of the acid solution in step (2) is ≥ 0.

5.

12. The preparation method according to claim 10, characterized in that: The liquid-to-solid ratio of the slurry is 1 to 100:1 mL / g.

13. The preparation method according to claim 10, characterized in that: The acid used in the pH adjustment includes hydrochloric acid.

14. The preparation method according to claim 10, characterized in that: In the pH adjustment, the pH of the slurry is controlled to be ≥ 0.

8.

15. The preparation method according to claim 10, characterized in that: The pH of the slurry after pH adjustment is 1.5-3.

0.

16. The preparation method according to claim 10, characterized in that: The washing temperature is 0-60°C.

17. The preparation method according to claim 10, characterized in that: The drying temperature is ≤ 60°C.

18. The preparation method according to claim 1, characterized in that: The preparation method comprises the following steps: (1) mixing a calcium-containing titanium source, a reducing agent and a calcium-containing molten reduction auxiliary agent, wherein the molar ratio of calcium in the titanium source to the reducing agent is 0.6 to 2:1, the molar ratio of the reducing agent to titanium in the titanium source is 0.67 to 1.33:1, and the weight ratio of the calcium-containing molten reduction auxiliary agent to titanium in the titanium source in terms of TiO2 is 0.05 to 3:1, and performing a reduction treatment at 700 to 1400° C. in a vacuum or protective atmosphere for 0.25 to 24 hours to obtain a reduced material; (2) The reducing material is slurried with water and / or an acid solution with a pH value of ≥0.5, wherein the liquid-to-solid ratio of the slurry is 1 to 100:1 mL / g, to obtain a slurry; the slurry is successively pH-adjusted with hydrochloric acid to a pH value of 1.5 to 3.0, and solid-liquid separation is performed, and the obtained solid phase is washed and dried at ≤60°C to obtain TiO x ; The reducing agent includes aluminum powder, the TiO x The value range of x is 0.167≤x≤1.

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