A method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy

Abstract

The present invention discloses a method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy, which mainly involves using fluotitanate to smelt spongy TiAl, TiAl3, Ti3Al alloy or a mixture thereof through aluminothermic reduction, and evaporating the fluotitanate and other incompletely reacted low-boiling impurities therein at high temperature. By means of molten salt electrolysis, using the spongy TiAl, TiAl3, Ti3Al alloy or a mixture thereof prepared by aluminothermic reaction as the anode material and the molten salt of cryolite and chloride system as the electrolyte, the Al in the anode is electrolytically separated, high-purity metallic Al is obtained at the cathode, and high-purity spongy titanium is obtained at the anode. The present invention makes full use of the method of preparing metallic spongy titanium at high temperature through molten salt electrolysis to prepare high-purity metallic spongy titanium and high-purity metallic aluminum as a by-product. Compared with the traditional Kroll method for preparing Ti, this method is energy-saving and environmentally friendly, has a simple process, and no harmful substances are emitted.

Description

Technical Field

[0001] The invention belongs to the field of metal smelting and extraction, and specifically relates to a smelting and purification method for preparing high-purity Ti and Ti alloys, and particularly relates to a method for preparing metallic titanium by electrolytically separating aluminum-titanium alloys. Background Art

[0002] As a strategic resource, titanium has excellent physical and chemical properties. Its density is 43% lower than that of steel, and it has high specific strength, high melting point, high temperature corrosion resistance and is non-toxic. It has been widely used in aerospace, military and chemical industries. As a "space metal", titanium alloys are used as engine materials, structural materials and various pipe joint materials for aircraft and rockets. Titanium has the characteristics of light weight, high strength, high hardness and corrosion resistance. my country's titanium resource reserves are the largest in the world. Mainly vanadium-titanium magnetite is deposited in the Panxi area of ​​Sichuan, distributed in Taihe, Baima, Hongge, Panzhihua and other mining areas. Among them, Baima, Hongge and Panzhihua iron mines are located in Panzhihua City, and Taihe Iron Mine is located in Xichang City. Among them, the vanadium-titanium magnetite resources have a reserve of about 9 billion tons (the potential evaluation of mineral resources predicts 19 billion tons of iron ore resources), of which the titanium resources (in terms of TiO2) have a reserve of nearly 600 million tons, accounting for about 87% of the national reserves. However, the price of titanium has greatly limited its use. Although titanium is abundant in the earth's crust (0.44%, ranking 8th among all metal elements, second only to magnesium's 2.0%), its price cannot be reduced due to the cumbersome current metallurgical process.

[0003] At present, the method for preparing titanium metal generally adopted in industry is magnesium thermal reduction process (Kroll method), and the sponge titanium produced can be purified by electron beam melting. The process of producing titanium metal by Kroll method is first to prepare titanium tetrachloride (TiCl4) by adding carbon to chlorinate titanium dioxide, and then obtain sponge titanium by thermal reduction with magnesium metal, and magnesium metal is obtained by electrolysis of magnesium chloride, and the chlorine obtained by electrolysis is used for the preparation of titanium chloride. The whole production process includes three main parts: magnesium chloride electrolysis, titanium oxide chlorination and magnesium thermal reduction. The steps are cumbersome and energy consumption is large, and the core magnesium thermal reduction step is intermittent operation, and the production efficiency is very low. Due to these reasons, the price of titanium metal is expensive, and its price is much higher than that of steel, and the unit weight price is more than 3 times that of aluminum metal. In addition, the chlorination process produces a serious corrosive environment, which is extremely harmful to production equipment and the environment. It is a major problem currently faced by Kroll method, and the storage and transportation of titanium tetrachloride are also very difficult.

[0004] At present, there are several representative titanium production processes in the molten salt electrolysis process, such as the FFC method, the OS method and the USTB method. The above three methods mainly use TiO2 as the anode material for electrolysis. During the electrolysis process, the oxygen element in the material is difficult to remove, and it is difficult to produce more than 99.9% of metallic titanium, and the current efficiency is not high. Although the preparation of metallic titanium by molten salt electrolysis has obvious cost and technical advantages, large-scale industrial production is still not possible at present, and many problems still need to be solved if large-scale industrial production is to be achieved. Both the FFC method and the OS method require a long time of electrolysis to reduce the dissolved oxygen content in metallic titanium, and the current efficiency is only about 15%. It can be seen that reducing the oxygen content of metallic titanium, shortening the time for preparing metallic titanium electrolysis, and improving the current efficiency are the key to the industrialization of electrolytic titanium production. Summary of the invention

[0005] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is: how to provide a method for preparing metallic titanium with high deoxidation rate, short preparation time and high current efficiency.

[0006] In order to solve the above technical problems, the present invention adopts the following technical scheme: a method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy, wherein metallic aluminum powder is used as a reducing agent, and fluorotitanate is subjected to aluminothermic reduction at 750-850°C in an inert atmosphere in a corundum crucible with a lid for 2-3 hours; after the reaction is sufficient, the lid of the corundum crucible is lifted, and the temperature is raised to 1050-1250°C for evaporation to remove unreacted fluorotitanate, fluoroaluminate generated by the reaction, and other low-boiling impurities that have not reacted completely; after evaporation, a low-purity sponge-like aluminum-titanium alloy mixture is obtained in the corundum crucible; the sponge-like aluminum-titanium alloy mixture is used as an anode, and electrolysis is carried out in a molten salt electrolyte to obtain high-purity metallic sponge titanium at the anode.

[0007] As an improvement, the fluorotitanate is sodium fluorotitanate or potassium fluorotitanate.

[0008] As an improvement, the sponge-like aluminum-titanium alloy mixture is sponge-like TiAl, TiAl3, Ti3Al or a mixture thereof.

[0009] As an improvement, in the electrolysis process, a mixture of BaCl2, Na3AlF6, AlF3 and NaCl is used as the electrolyte, sponge-like TiAl, TiAl3, Ti3Al alloy or a mixture thereof is used as the anode material for electrolysis, and graphite is used as the cathode material.

[0010] As an improvement, the electrolyte is a mixture of 60wt% BaCl2, 22wt% Na3AlF6, 14wt% AlF3 and 4wt% NaCl.

[0011] As an improvement, the electrolysis temperature of the electrolysis process is 1000-1100°C.

[0012] As an improvement, the amount of the metal aluminum powder added is 2 to 4 wt% more than the amount required to generate Ti.

[0013] Compared with the prior art, the present invention has at least the following advantages:

[0014] 1. The present invention proposes to use TiAl, TiAl3, Ti3Al alloy or a mixture thereof prepared by aluminothermic reduction method through molten salt electrolysis as anode material, and use 60wt% BaCl2, 22wt% Na3AlF6, 15wt% AlF3, 4wt% NaCl as electrolyte, and obtain high-purity aluminum at the cathode and high-purity metal sponge titanium at the anode after electrolysis. Compared with the traditional Kroll process for preparing sponge titanium, the present invention significantly reduces energy consumption, is energy-saving and environmentally friendly, has a simple process, and has high added value of the byproduct high-purity aluminum.

[0015] 2. The present invention combines aluminothermic reduction with molten salt electrolysis. The aluminothermic reduction process can produce porous sponge-like TiAl, TiAl3, Ti3Al or a mixture thereof. Under electrolysis conditions, Al in the anode is dissolved and precipitated at the cathode, thereby achieving the purpose of refining metallic titanium. The electrolysis process in the present invention greatly reduces energy consumption, and the current efficiency in the process is also very high. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Flow chart of the method of the present invention.

[0017] Figure 2 This is an experimental device for electrolytic production of titanium according to the present invention.

[0018] In the figure, 1- steel rod, 2- graphite crucible, 3- aluminum-titanium alloy, 4- corundum tube, 5- molten salt, 6- pure aluminum. DETAILED DESCRIPTION

[0019] The present invention is described in further detail below.

[0020] A method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy aims to prepare TiAl, TiAl3, Ti3Al alloy or other mixtures by aluminothermic reduction of fluorotitanate (mainly sodium fluorotitanate or potassium fluorotitanate), and evaporate the fluorotitanate and other low-boiling impurities that have not reacted completely at high temperature. Then, 60wt% BaCl2, 22wt% Na3AlF6, 15wt% AlF3 and 4wt% NaCl are used as electrolytes, and spongy TiAl, TiAl3, Ti3Al alloy or their mixtures prepared by aluminothermic reaction are used as anode materials for electrolysis. After electrolysis, high-purity aluminum is obtained at the cathode, and high-purity metallic titanium is obtained at the anode. The present invention makes full use of high-temperature aluminothermic reduction to prepare aluminum-titanium alloy, and then prepares high-purity metallic Ti and high-purity metallic Al as a byproduct by molten salt electrolysis. Compared with the traditional Kroll method for preparing Ti, this method is energy-saving and environmentally friendly, has a simple process, and does not emit harmful substances.

[0021] See also Figure 1 and Figure 2 A method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy, wherein metallic aluminum powder is used as a reducing agent, and fluorotitanate is subjected to aluminothermic reduction at 750-850°C in an inert atmosphere for 2-3 hours in a corundum crucible with a lid; in specific implementation, the aluminothermic reduction temperature can be selected from 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C or 850°C; and the reaction time can be selected from 2.0h, 2.2h, 2.5h, 2.8h or 3.0h.

[0022] After the reaction is sufficient, the lid of the corundum crucible is lifted, and the temperature is raised to 1050-1250°C for evaporation to remove unreacted fluorotitanate, fluoroaluminate generated by the reaction, and other low-boiling impurities that have not reacted completely; the purpose of the temperature of 1050-1250°C is to evaporate other low-boiling point substances except Ti and Al after the reaction, including unreacted reactant fluorotitanate, fluoride and fluorotitanate generated by the reaction. In specific implementation, the evaporation temperature can be selected from 1050°C, 1080°C, 1100°C, 1130°C, 1150°C, 1180°C, 1200°C or 1250°C.

[0023] After evaporation, a low-purity sponge-like aluminum-titanium alloy mixture is obtained in a corundum crucible; the sponge-like aluminum-titanium alloy mixture is used as an anode, and electrolysis is performed in an inert atmosphere environment to obtain high-purity metal sponge titanium at the anode.

[0024] In a specific implementation, the fluorotitanate is sodium fluorotitanate or potassium fluorotitanate.

[0025] The aluminum-titanium alloy mixture is TiAl, TiAl3, Ti3Al alloy or a mixture thereof.

[0026] In the electrolysis process, BaCl2, Na3AlF6, AlF3 and NaCl are used as electrolytes, sponge-like TiAl, TiAl3, Ti3Al alloy or a mixture thereof are used as anode materials for electrolysis, and graphite is used as cathode material. The sponge titanium and sponge-like TiAl, Ti3Al, TiAl3 alloy or a mixture thereof are electrolyzed by using a molten salt electrolysis method to use sponge-like TiAl, TiAl3, Ti3Al alloy or a mixture thereof as anode materials, graphite as cathode materials, and applying a DC voltage to oxidize Al on the anode into Al 3+ Entering the molten electrolyte, at the cathode Al 3+ The ions obtain electrons to form single Al and precipitate to form relatively high purity metallic Al, and the remaining part of the anode is relatively high purity metallic titanium.

[0027] The amount of the metal aluminum powder added is 2-4wt% more than the amount required to generate Ti. Specifically, the amount of the metal aluminum powder added is 2.0wt%, 2.2wt%, 2.5wt%, 2.8wt%, 3wt%, 3.2wt%, 3.5wt%, 3.8wt% or 4.0wt% more than the amount required to generate Ti.

[0028] like Figure 1 As shown, the anode is made of low-purity sponge-like TiAl, TiAl3, Ti3Al alloy or a mixture thereof by aluminothermic reduction, and high-purity metal sponge titanium is obtained after electrolysis; graphite is used as cathode material, and a mixture of BaCl2, Na3AlF6, AlF3 and NaCl is used as electrolyte, and the electrolysis temperature is 1000-1100°C. In specific implementation, the electrolysis temperature can be selected from 1000°C, 1010°C, 1020°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C, 1090°C or 1100°C. The electrolyte is a mixture of 60wt% BaCl2, 22wt% Na3AlF6, 14wt% AlF3 and 4wt% NaCl.

[0029] The specific reaction equation involved is:

[0030] 3Na2TiF6+4Al+6NaF=3Ti+4Na3AlF6

[0031] 3Na2TiF6+7Al+6NaF=3AlTi+4Na3AlF6

[0032] 3Na2TiF6+13Al+6NaF=3AlTi3+4Na3AlF6

[0033] 3K2TiF6+4Al+6KF=3Ti+4K3AlF6

[0034] 3K2TiF6+7Al+6KF=3AlTi+4K3AlF6

[0035] 3K2TiF6+13Al+6KF=3AlTi3+4K3AlF

[0036] Al+7AlCl4 - =4Al2Cl7 - +3e -

[0037] 4Al2Cl7 - +3e - =Al+7AlCl4 -

[0038] In the present invention, various aluminum-titanium alloys that appear in the aluminothermic reduction process can be electrolytically separated, not limited to one type of aluminum-titanium alloy. The various aluminum-titanium alloys are mostly sponge-shaped, which provides a larger available space for the second step of the electrolysis process, increases the reaction efficiency, shortens the reaction time, and the by-products after crystallization can continue to be used for industrial aluminum electrolysis. During the electrolysis process, high-purity aluminum can be obtained at the cathode, and high-purity sponge titanium can also be obtained at the anode, which reduces energy consumption, saves energy and protects the environment, has a simple process, and does not emit harmful substances.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy, characterized in that: Aluminum powder is used as a reducing agent to carry out aluminothermic reduction of fluorotitanate in a corundum crucible with a lid at 750-850°C in an inert atmosphere for 2-3 hours; After the reaction is sufficient, the lid of the corundum crucible is lifted, and the temperature is raised to 1050-1250°C for evaporation to remove the unreacted fluorotitanate, the fluoroaluminate generated by the reaction, and other low-boiling impurities that have not reacted completely; After evaporation, a low-purity sponge-like aluminum-titanium alloy mixture is obtained in a corundum crucible; The sponge-like aluminum-titanium alloy mixture is used as an anode to carry out electrolysis in a molten salt electrolyte, and a high-purity metal sponge titanium is obtained at the anode; The sponge-like aluminum-titanium alloy mixture is sponge-like TiAl, TiAl3, Ti3Al or a mixture thereof; In the electrolysis process, a mixture of BaCl2, Na3AlF6, AlF3 and NaCl is used as electrolyte, sponge-like TiAl, TiAl3, Ti3Al alloy or a mixture thereof is used as an anode material for electrolysis, and graphite is used as a cathode material.

2. The method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy as claimed in claim 1, characterized in that: The fluorotitanate is sodium fluorotitanate or potassium fluorotitanate.

3. The method for preparing titanium metal by electrolytic separation of aluminum-titanium alloy as claimed in claim 1, characterized in that: The electrolyte is a mixture of 60 wt% BaCl2, 22 wt% Na3AlF6, 14 wt% AlF3 and 4 wt% NaCl.

4. The method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy as claimed in claim 1, characterized in that: The electrolysis temperature of the electrolysis process is 1000-1100°C.

5. The method for preparing metallic titanium by electrolytic separation of aluminum-titanium alloy as claimed in claim 4, characterized in that: The amount of the metal aluminum powder added is 2-4 wt% more than the amount required to obtain the metal sponge titanium.

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