Preparation method of ferrotitanium alloy FeTi70 and dielectric separation device

Abstract

The invention belongs to the technical field of preparation of ferrotitanium, and particularly relates to a preparation method of ferrotitanium FeTi70 and a dielectric separation device. According to the preparation method of the ferrotitanium alloy FeTi70 and the dielectric separation device, the raw material proportion, the reaction temperature, the vibration frequency of furnace charge, the oscillation amplitude and the reaction speed are strictly controlled, the consumption of magnesium can be effectively reduced, and meanwhile the conversion efficiency of titanium is improved. The magnesium consumption (Mg / Ti mass ratio) does not exceed 1.29, and the titanium conversion rate can reach 96%. In addition, the method disclosed by the invention is relatively short in production flow, and the production efficiency can be remarkably improved. Aiming at the characteristics of the mixture of the ferrotitanium FeTi70 and the slag MgO2, the invention provides the dielectric separation device special for separating the mixture, and by using the device, the optimal separation effect can be achieved, so that the purity of the finally obtained ferrotitanium FeTi70 is obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium-iron alloy preparation, and in particular relates to a titanium-iron alloy FeTi70 preparation method and a dielectric separation device. Background Art

[0002] Ferrotitanium is an intermediate alloy of titanium and iron, used as a deoxidizer, degasser and carbon-sulfur stabilizer in steel smelting. Ferrotitanium plays a key role in the production of steel. Through the titanium element it contains, it can effectively purify molten steel and improve the quality and performance of steel. For example, titanium deoxidation in the production of killed steel can reduce the segregation of the upper part of the ingot and improve the quality of steel; titanium combines with nitrogen dissolved in molten steel to form stable titanium nitride, eliminating the adverse effects of nitrogen on steel properties; titanium combines with sulfur in molten steel to form titanium sulfide, which can eliminate the production of iron sulfide that causes hot brittleness; titanium combines with carbon to form extremely stable titanium carbide, and the particles of titanium carbide can prevent the growth of steel grains, refine the structure of steel, and improve the strength of steel. In addition, using ferrotitanium as a coating component in welding rods can improve welding quality.

[0003] The production methods of ferrotitanium mainly include the aluminothermic method, the electrosilicon thermal method and the electrocarbon thermal method, as well as the remelting method of scrap titanium metal. These methods use different reducing agents and process conditions to extract titanium and iron from raw materials to produce ferrotitanium alloys. For example, the aluminothermic method is to produce ferrotitanium by reducing ilmenite (FeTiO3) with aluminum. This method is relatively easy and the product has a low carbon content, but high aluminum and silicon. The electrosilicon thermal method and the electrocarbon thermal method use silicon and carbon as reducing agents, respectively, to reduce TiO2 under high temperature conditions to produce ferrotitanium. The scrap titanium metal remelting method uses titanium waste and scrap steel as raw materials, remelting them in an induction furnace to produce ferrotitanium with about 70% Ti.

[0004] According to the different titanium contents, ferrotitanium is mainly divided into three varieties: FeTi30 (containing Ti25.0%-35.0%, Al<8.5%, Si<5.0%), FeTi40 (containing Ti35.0%-45.0%, Al<9.5%, Si<4.0%) and FeTi70 (containing Ti65%-75%, A10.5%~5%, Si<0.5%). The international market has a large demand for high-titanium ferrotitanium with high titanium content, but my country's current ferroalloy factories generally only produce ordinary medium and low ferrotitanium. There is little production experience for high-titanium ferrotitanium with w(Ti)=65%~75%, w(Al)≤4%.

[0005] In the prior art, "Ullmann's Encyclopedia of Industrial Chemistry. Titanium and Titanium Alloys." proposes a method for preparing titanium iron alloy FeTi70 from titanium alloy waste, low carbon or medium carbon steel waste. Titanium alloy waste mainly includes block titanium waste, flaky scraps and shavings. Without using flux, the raw materials are placed in an induction furnace with magnesite as the furnace lining for melting, and an iron oxide film is formed on the surface of the titanium iron metal solution to protect the prepared FeTi70 from oxidation. The disadvantages of this method are: the cost of titanium alloy waste is high, the waste is highly dependent on the titanium alloy market conditions, and the titanium alloy waste contains some elements that have a negative impact on FeTi70, such as Sn, Al, V, Mo, Mn, Cr, Si, Nb, Zr, etc.

[0006] CN102605182B (Mei Zefeng, Zhu Xiangying, Xia Hongliang, Lin Yifei, authorized on January 22, 2014) discloses a method for producing 70# high titanium iron by an off-furnace method. The method uniformly mixes rutile, titanium iron concentrate, reducing agent, sodium chlorate and lime in a certain proportion, puts the mixture into a special closed high temperature and high pressure resistant reactor, spreads an appropriate amount of magnesium chips on the top of the mixture, uses an off-furnace electric ignition to ignite the magnesium chips to start the smelting reaction, and shakes the reactor during the smelting process to promote the full progress of the reaction. After cooling and depressurization, the furnace is opened to take out the reactants, slag and gold are separated and finished to obtain 70# high titanium iron. The method has simple process, low equipment investment, low production cost, high product quality standard, oxygen content less than 2%, meets the requirements of steelmaking process, and has high economic and social benefits. The disadvantage of this method is that there is a high risk of explosion. The charge contains active oxidant NaClO3, which may explode due to mechanical collision between the charges, and the dust suspended in the air is also explosive. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a preparation method of ferrotitanium alloy FeTi70 and a dielectric separation device, and the present invention specifically includes the following contents:

[0008] A method for preparing titanium-iron alloy FeTi70 comprises the following steps:

[0009] (1) Smelting titanium-iron alloy: TiO2, Mg and Fe are charged into a medium frequency smelting furnace according to the mass ratio of (52-57):(31-34):(9-17) for smelting, and the smelting temperature is controlled to be 1085-1300°C, the vibration frequency is 10-200 Hz, and the vibration amplitude is 0.1-10 mm. After the reaction is completed, the mixture is cooled to obtain a mixture of titanium-iron alloy FeTi70 and slag MgO2;

[0010] (2) Dielectric separation: The mixture of the titanium-iron alloy FeTi70 and the slag MgO2 is crushed into 200-270 meshes, and then dielectric separation is performed using a dielectric separation device to obtain the titanium-iron alloy FeTi70 and the slag MgO2.

[0011] Furthermore, the dielectric liquid for dielectric separation is one or more of methanol, carbon tetrachloride, and water.

[0012] Furthermore, the reaction formula of the smelting reaction in step (1) is:

[0013] TiO2+2Mg+(0.37)Fe→(Ti+0.37Fe)+2MgO2.

[0014] Furthermore, the mass ratio of Ti to Fe in the titanium-iron alloy FeTi70 is 7:3.

[0015] A dielectric separation device for separating the mixture of the titanium-iron alloy FeTi70 and the slag MgO2 comprises a box, a first electrode, a second electrode, a third electrode, a fourth electrode, a first receiver, two second receivers, and a dielectric liquid.

[0016] The top of the box is provided with a feed port, and the box contains dielectric liquid;

[0017] The first electrode, the second electrode, the third electrode and the fourth electrode are sequentially arranged in the box and immersed in the dielectric liquid, a titanium-iron alloy FeTi70 channel is formed between the second electrode and the third electrode, and a slag MgO2 channel is formed between the first electrode and the second electrode, and between the third electrode and the fourth electrode;

[0018] The first receiver and the second receiver are both arranged at the bottom of the box body, and the first receiver is located below the titanium-iron alloy FeTi70 channel; the two second receivers are respectively located below the two slag MgO2 channels.

[0019] Preferably, the first electrode, the second electrode, the third electrode and the fourth electrode are all electrode wires, the minimum distance between the second electrode and the third electrode is 10-14 mm, and the distance between the first electrode wire and the fourth electrode wire is 20-30 mm.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a preparation method of titanium-iron alloy FeTi70 and a dielectric separation device. The method strictly controls the raw material ratio, reaction temperature and vibration frequency and oscillation amplitude of the charge, controls the reaction speed, can effectively reduce the consumption of magnesium and improve the conversion efficiency of titanium. Using the method of the present invention, the consumption of magnesium (Mg / Ti mass ratio) does not exceed 1.29, and the conversion rate of titanium can reach 96%. Moreover, the method disclosed in the present invention has a short production process and can significantly improve production efficiency. The present invention provides a dielectric separation device specifically used for separating the above mixture in view of the characteristics of the mixture of titanium-iron alloy FeTi70 and slag MgO2, designs and defines the parameters and structures such as the distance between each electrode, and uses the device to achieve the best separation effect, so that the purity of the final titanium-iron alloy FeTi70 is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the phase diagram of Ti-Fe binary alloy;

[0023] Figure 2 It is a structural schematic diagram of the dielectric separation device disclosed in the present invention;

[0024] Figure 3 The graph is a trend diagram of magnesium consumption with smelting temperature under different raw material weight ratios in the embodiments of the present invention and the comparative examples;

[0025] Figure 4 The graph is a trend chart of the change of titanium conversion rate with smelting temperature under different raw material weight ratios in the embodiments of the present invention and the comparative examples;

[0026] Figure 5 The figure is a trend diagram of the change of titanium conversion rate with oscillation amplitude at different vibration frequencies in the embodiments of the present invention and the comparative example. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments shown below do not limit the invention content described in the claims. In addition, the entire contents of the structures represented by the following embodiments are not limited to those necessary as solutions to the invention described in the claims.

[0028] A method for preparing titanium-iron alloy FeTi70 comprises the following steps:

[0029] (1) Smelting titanium-iron alloy: TiO2, Mg and Fe are charged into a medium frequency smelting furnace according to the mass ratio of (52-57):(31-34):(9-17) for smelting, and the smelting temperature is controlled to be 1085-1300°C, the vibration frequency is 10-200 Hz, and the vibration amplitude is 0.1-10 mm. After the reaction is completed, the mixture is cooled to obtain a mixture of titanium-iron alloy FeTi70 and slag MgO2;

[0030] (2) Dielectric separation: The mixture of the titanium-iron alloy FeTi70 and the slag MgO2 is crushed to 200-270 mesh, and then subjected to dielectric separation. The dielectric liquid for dielectric separation is one or more of methanol, carbon tetrachloride, and water to obtain the titanium-iron alloy FeTi70 and the slag MgO2.

[0031] The present invention is shown in reaction (1), wherein (Ti+0.37Fe) is a titanium-iron alloy with a mass ratio of Ti to Fe of 7:3, namely FeTi70.

[0032] TiO2+2Mg+(0.37)Fe→(Ti+0.37Fe)+2MgO2 (1)

[0033] The numbers preceding the elements in formula (1) represent the molar ratio of each element.

[0034] The method of the present invention comprises the following steps: mixing raw materials titanium dioxide powder, iron powder and magnesium powder according to a mass ratio of TiO2:Mg:Fe=(52-57):(31-34):(9-17) and then charging them into a reaction furnace for smelting. If the weight ratio of TiO2 to Fe is not within a specified range, the titanium content of the product iron-titanium alloy will not be between 65% and 75%, and the melting point of the product iron-titanium alloy will be greater than 1300°C (e.g. Figure 1 ), resulting in an incomplete reaction. The weight of magnesium in the raw material must also be maintained in the range of 31-34%. If the weight of magnesium is <31%, the titanium content extracted from the raw material will be reduced; if the weight of magnesium is >34%, part of the magnesium will not participate in the reaction (1), and it will remain in the slag or pass into the gas phase, resulting in a waste of reducing agent magnesium.

[0035] The present invention also requires strict control of the reaction furnace temperature between 1085-1300°C. If the furnace temperature is lower than 1085°C, the ferro-titanium alloy is present in the form of small metal particles through the reaction (1), and the small metal particles will not melt together, resulting in difficulty in separating the ferro-titanium alloy and the slag. At the same time, the titanium content extracted from the raw material is very low, and the consumption of the reducing agent magnesium is very large; if the furnace temperature is higher than 1300°C, due to the interaction between titanium dioxide and magnesium, a large amount of low-valent titanium oxides (TiO, Ti2O3, etc.) will be formed, which will also result in a very low titanium content extracted from the raw material and a large consumption of the reducing agent magnesium.

[0036] In order to melt the titanium-iron alloy generated by the reaction, the present invention sets the vibration frequency of the furnace charge in the furnace to 10-200 Hz and the oscillation amplitude to 0.1-10 mm. The furnace charge in the furnace is vibrated reasonably to move the product iron-titanium alloy out of the reaction zone of reaction (1), which is conducive to the continuous generation of products and accelerates the reaction speed.

[0037] The present invention uses dielectric separation to separate the ferro-titanium alloy FeTi70 and the slag MgO2. In the temperature range of 1085-1300°C, the ferro-titanium alloy FeTi70 is liquid and the slag MgO2 is solid. During the reaction process, the product and the slag are not completely separated. Therefore, after the reaction furnace is cooled, the present invention crushes the product and separates FeTi70 from MgO2 by dielectric separation. The method is based on the difference in dielectric constants between the ferro-titanium alloy and the slag, and has a good separation effect.

[0038] Reference Figure 2 The present invention also provides a dielectric separation device for separating the mixture of ferrotitanium FeTi70 and slag MgO2 according to the characteristics of the mixture, comprising a box, a first electrode, a second electrode, a third electrode, a fourth electrode, a first receiver, two second receivers, and a dielectric liquid, wherein a feed port is provided on the top of the box, and the box contains dielectric liquid; the first electrode, the second electrode, the third electrode, and the fourth electrode are sequentially arranged in the box and immersed in the dielectric liquid, a ferrotitanium FeTi70 channel is formed between the second electrode and the third electrode, and slag MgO2 channels are respectively formed between the first electrode and the second electrode, and between the third electrode and the fourth electrode; the first electrode, the second electrode, the third electrode, and the fourth electrode are all electrode wires, the minimum distance between the second electrode and the third electrode is 10-14 mm, and the distance between the first electrode wire and the fourth electrode wire is 20-30 mm. The first receiver and the second receiver are both arranged at the bottom of the box, the first receiver is located below the titanium-iron alloy FeTi70 channel; the two second receivers are respectively located below the two slag MgO2 channels. The device can achieve the best separation effect, so that the purity of the titanium-iron alloy FeTi70 obtained can be significantly improved.

[0039] Example 1

[0040] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 55TiO2: 32Mg: 13Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1200°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 100Hz and the oscillation amplitude is 1mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0041] Example 2

[0042] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 55TiO2: 32Mg: 13Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1200°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 10Hz and the oscillation amplitude is 10mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0043] Example 3

[0044] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 55TiO2: 32Mg: 13Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1200°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 200Hz and the oscillation amplitude is 0.1mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0045] Example 4

[0046] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 52TiO2: 31Mg: 17Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1300°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 100Hz and the oscillation amplitude is 1mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0047] Example 5

[0048] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 57TiO2: 34Mg: 9Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1085°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 100Hz and the oscillation amplitude is 1mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0049] Comparative Example 1

[0050] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 55TiO2: 32Mg: 13Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1200°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 5Hz and the oscillation amplitude is 12mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0051] Comparative Example 2

[0052] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 55TiO2: 32Mg: 13Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1200°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 230Hz and the oscillation amplitude is 0.05mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0053] Comparative Example 3

[0054] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 61TiO2: 32Mg: 7Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1050°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 100Hz and the oscillation amplitude is 1mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0055] Comparative Example 4

[0056] A method for preparing titanium-iron alloy FeTi70, according to the weight ratio (%): 48TiO2: 32Mg: 20Fe, raw titanium oxide carbon dioxide powder, iron powder and reducing agent magnesium powder are loaded into a reaction furnace, the furnace temperature is raised to 1350°C, the raw materials are melted, and the reaction generates titanium-iron alloy FeTi70 and slag MgO2. In order to melt the titanium-iron alloy generated by the reaction together, the vibration frequency of the charge in the furnace is 100Hz and the oscillation amplitude is 1mm. After the reaction process is completed, the reaction furnace is cooled, the titanium-iron alloy FeTi70 and slag MgO2 generated by the reaction are crushed, and FeTi70 is separated from MgO2 by dielectric separation.

[0057] As shown in Table 1, Figure 3 The consumption of reducing agent magnesium (the ratio of the mass of consumed magnesium to the mass of converted titanium, i.e., Mg / Ti) in the preparation method of a titanium-iron alloy FeTi70 in Examples 1-5 and Comparative Examples 1-4 at different weight ratios and different temperatures (vibration frequency of 100 Hz, oscillation amplitude of 1 mm) is shown. From Tables 1 and Figure 3It can be seen that when the weight ratio of raw materials is (52-57) TiO2: (31-34) Mg: (9-17) Fe and the reactor temperature is 1085-1300°C (the bold part in Table 1), the consumption of reducing agent magnesium is relatively low. Among them, when the weight ratio of raw materials is 55 TiO2: 32 Mg: 13 Fe and the reactor temperature is 1200°C, the consumption of reducing agent magnesium is 1.07.

[0058] Table 1 Consumption of reducing agent magnesium in preparation of FeTi70 at different weight ratios and temperatures

[0059]

[0060] As shown in Table 2, Figure 4 The results show the conversion rates of titanium in the preparation method of a titanium-iron alloy FeTi70 of Examples 1-5 and Comparative Examples 1-4 at different weight ratios and different temperatures (vibration frequency of 100 Hz and oscillation amplitude of 1 mm). Figure 4 It can be seen that the titanium conversion rate is higher when the raw material weight ratio is (52-57) TiO2: (31-34) Mg: (9-17) Fe and the reactor temperature is 1085-1300℃. Among them, when the raw material weight ratio is 55TiO2: 32Mg: 13Fe and the reactor temperature is 1200℃, the titanium conversion rate is 96%. In addition, Figure 4 As shown in Figure 2, when the raw material weight ratio is 52TiO2:36Mg:12Fe, the titanium conversion rate is higher, second only to the raw material weight ratio of 55TiO2:32Mg:13Fe. Figure 3 As shown, the consumption of reducing agent magnesium is high, so this ratio is not optimal and is not recommended.

[0061] Table 2 Titanium conversion rate at different weight ratios and temperatures in the preparation of FeTi70

[0062]

[0063]

[0064] As shown in Table 3, Figure 5 The results show the conversion rate of titanium in the preparation method of FeTi70 of Example 1-5 and Comparative Example 1-4 at different vibration frequencies and different oscillation amplitudes (the weight ratio of raw materials is 52TiO2:36Mg:12Fe, and the temperature of the reaction furnace is 1200°C). Figure 5 It can be seen that the conversion rate of titanium is higher when the vibration frequency is 10-200 Hz and the oscillation amplitude is 0.1-10 mm (the bold part in Table 3), among which, when the vibration frequency is 100 Hz and the oscillation amplitude is 1 mm, the conversion rate of titanium is 96%.

[0065] Table 3 Titanium conversion rate at different vibration frequencies and oscillation amplitudes in the preparation of FeTi70

[0066]

[0067] In summary, the method of the present invention is used to prepare the ferrotitanium alloy FeTi70, with low magnesium consumption and high titanium conversion rate. The output and quality of the product are better than those of other methods, and has great advantages.

[0068] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing titanium-iron alloy FeTi70, characterized in that: The following steps are involved: (1) Smelting titanium-iron alloy: TiO2, Mg and Fe are charged into a medium frequency smelting furnace according to the mass ratio of (52-57):(31-34):(9-17) for smelting, and the smelting temperature is controlled to be 1085-1300°C, the vibration frequency is 10-200 Hz, and the vibration amplitude is 0.1-10 mm. After the reaction is completed, the mixture is cooled to obtain a mixture of titanium-iron alloy FeTi70 and slag MgO2; (2) Dielectric separation: The mixture of the titanium-iron alloy FeTi70 and the slag MgO2 is crushed into 200-270 meshes, and then dielectric separation is performed using a dielectric separation device to obtain the titanium-iron alloy FeTi70 and the slag MgO2.

2. The method for preparing a titanium-iron alloy FeTi70 according to claim 1, characterized in that: The dielectric liquid for dielectric separation is one or more of methanol, carbon tetrachloride and water.

3. The method for preparing the ferrotitanium alloy FeTi70 according to any one of claims 1 to 2, characterized in that: The reaction formula of the smelting reaction in step (1) is: TiO2+2Mg+(0.37)Fe→(Ti+0.37Fe)+2MgO2.

4. A dielectric separation device for separating a mixture of ferrotitanium alloy FeTi70 and slag MgO2 as claimed in any one of claims 1 to 3, characterized in that: The device comprises a housing, a first electrode, a second electrode, a third electrode, a fourth electrode, a first receiver, two second receivers, and a dielectric fluid. The top of the box is provided with a feed port, and the box contains dielectric liquid; The first electrode, the second electrode, the third electrode and the fourth electrode are sequentially arranged in the box and immersed in the dielectric liquid, a titanium-iron alloy FeTi70 channel is formed between the second electrode and the third electrode, and a slag MgO2 channel is formed between the first electrode and the second electrode, and between the third electrode and the fourth electrode; The first receiver and the second receiver are both arranged at the bottom of the box body, and the first receiver is located below the titanium-iron alloy FeTi70 channel; the two second receivers are respectively located below the two slag MgO2 channels.

5. A dielectric separation device according to claim 4, characterized in that: The first electrode, the second electrode, the third electrode and the fourth electrode are all electrode wires, the minimum distance between the second electrode and the third electrode is 10-14 mm, and the minimum distance between the first electrode wire and the fourth electrode wire is 20-30 mm.

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