Method for preparing aluminum-titanium intermediate alloy through fused salt aluminothermic self-reduction

Abstract

The invention discloses a method for preparing an aluminum-titanium intermediate alloy through aluminothermic self-reduction of molten salt, which comprises the following steps: selecting cryolite molten salt for aluminum electrolysis as a reaction medium, taking molten aluminum as a reducing agent and taking TiO2 as a raw material; the method comprises the steps that cryolite molten salt with a certain proportion is firstly put into a reduction device, a certain amount of TiO2 powder is added, stirring is conducted for 10-30 min under the inert atmosphere condition, and TiO2 is sufficiently and rapidly dissolved in the molten salt; molten aluminum is added under the inert atmosphere and the stirring condition, after aluminothermic self-reduction is conducted for 10-60 min, standing is conducted for a certain time to enable an alloy phase and molten salt to be layered, and then a metal phase and molten salt are separated. According to the invention, the environment-friendly TiO2 is adopted as a raw material to directly prepare the aluminum-titanium intermediate alloy, so that the production cost is greatly reduced; the heat generated by aluminum reduction is used for maintaining the reaction, the molten aluminum is prevented from being oxidized in the inert atmosphere, the dissolution speed of TiO2 dissolved in cryolite melt can be increased through reduction in the stirring environment, the dynamic condition of aluminum reduction is also strengthened, and the speed of in-situ generation of the aluminum-titanium intermediate alloy is greatly increased.

Description

Technical Field

[0001] The invention relates to the technical field of alloy preparation, in particular to a method for preparing an aluminum-titanium master alloy by self-reduction of molten salt aluminothermic reduction. Background Art

[0002] Aluminum is an important light metal with excellent properties. It is widely used in construction, machinery, aerospace, electricity and daily life. It is one of the most widely used non-ferrous metal materials. The alloying research of aluminum is relatively mature. The refinement of aluminum grains is an effective method to improve the comprehensive mechanical properties of aluminum and its alloys. Titanium is a common element for grain refinement. At present, titanium is mainly added to the alloy in the form of an intermediate alloy during the melting and matching process of aluminum alloys. The introduction of titanium in the form of an aluminum-titanium intermediate alloy can solve the problems of easy burning of titanium metal, difficult melting at high melting point, and easy segregation due to high density, and can improve the performance of the alloy. At present, the main method for preparing aluminum-titanium intermediate alloys is the metal melting and matching method, that is, pure aluminum and titanium metal are used in a molten state to generate aluminum-titanium intermediate alloys with different titanium contents, which have large burning losses and are easy to segregate. In addition, since the industrial preparation of titanium metal still adopts the magnesium thermal reduction method (also known as the Kroll method), it has the disadvantages of long process flow, high energy consumption, high environmental pollution, and high production cost, which leads to the high price of titanium metal and the high price of aluminum-titanium intermediate alloys. The patent with publication number CN101514418A uses molten aluminum and sponge titanium as main materials. The aluminum content in the molten aluminum is 99.97-99.99%, and the titanium content in the sponge titanium is 99.8-99.9%. Some refining agents and covering agents are added as auxiliary materials. The aluminum-titanium intermediate alloy obtained by smelting meets the requirements of the national standard GB8735-88.

[0003] The preparation of metals and alloys by molten salt electrolysis has the advantages of short process flow, simple and fast, and low cost, and is a new type of green metallurgical technology. In the patent with publication number CN101092715A, titanium dioxide is added to the electrolytic cell 3-5 times a day, and sampling and analysis are carried out after 2-3 hours; when the electrolytic production time is 4-6 months, the process is rotated, and the addition of titanium dioxide is stopped. The titanium content in the electrolytic production of aluminum-titanium alloy in the electrolytic cell is low, not exceeding 1%. The patent with publication number CN1298965A directly uses a mixture of aluminum oxide and titanium oxide as raw materials, and electrolyzes in an electrolytic cell with a cryolite system as an electrolyte to obtain an aluminum-titanium alloy. The titanium content in the aluminum-titanium alloy obtained by electrolysis is 0.1-0.6% of the total weight of the alloy. It can be seen that using industrial aluminum electrolysis equipment, adding TiO2 powder, and directly electrolyzing to prepare aluminum-based alloys is a feasible way to produce low-cost and efficient production, which proves that the preparation of low-titanium aluminum-based alloys is feasible. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction, which solves the problems of high cost, large burnout of metal titanium, easy segregation of titanium element, etc. in preparing aluminum-titanium master alloy by metal melting and matching method; and to solve the influence of molten salt electrolysis process on molten salt electrolysis process, low titanium content and large segregation of alloy components in preparing aluminum-titanium master alloy by molten salt electrolysis method.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for preparing an aluminum-titanium master alloy by aluminothermic self-reduction of molten salts, comprising the following steps: selecting cryolite molten salt for aluminum electrolysis as a reaction medium, using aluminum liquid as a reducing agent, and using TiO2 as a raw material; firstly charging a certain proportion of cryolite molten salt into a reduction device, adding a certain amount of TiO2 powder, and stirring for 10-30 minutes under inert atmosphere conditions to fully and rapidly dissolve TiO2 in the molten salt; adding aluminum liquid under inert atmosphere and stirring conditions, performing aluminothermic self-reduction for 10-60 minutes, standing for a certain period of time to allow the alloy phase and the molten salt to separate into layers, and then separating the metal phase and the molten salt; adjusting the composition of the separated alloy and removing the slag to obtain a commercial aluminum-titanium master alloy; and then feeding the separated Al2O3-rich molten salt into an industrial aluminum electrolytic cell, electrolyzing and recovering the cryolite molten salt and aluminum liquid for recycling.

[0006] Preferably, the cryolite molten salt system is a mixture of sodium fluoroaluminate, aluminum fluoride and calcium fluoride, with a molecular ratio of 2.0-2.4.

[0007] Preferably, the cryolite melt at 930° C.-960° C. can be heated by cryolite molten salt or obtained from an industrial electrolytic cell.

[0008] Preferably, the aluminum liquid can be high-temperature aluminum liquid heated from aluminum ingots or in an electrolytic cell.

[0009] Preferably, the reduction device is provided with a refractory insulation layer, a stainless steel crucible, and a graphite crucible, the molten salt is contained in the graphite crucible, the graphite crucible is placed in the stainless steel crucible, and the stainless steel crucible is placed inside the refractory insulation layer; a graphite rod stirring device or an inert gas stirring device is provided in the reduction device; the reduction device is provided with an inert atmosphere inlet and outlet, an inlet and outlet for cryolite molten salt and aluminum liquid, a feeding port for titanium oxide, a sampling port, and a temperature measuring port.

[0010] Preferably, the titanium oxide is environmentally friendly TiO2.

[0011] Preferably, the inert atmosphere is an argon atmosphere to avoid oxidation of the aluminum liquid.

[0012] Preferably, a stirring device made of a graphite rod or an inert anode material is used for stirring, and inert atmosphere blowing stirring can also be used.

[0013] Preferably, the alloy phase is separated by a siphon method, a bottom opening aluminum discharge method, or a pouring aluminum discharge method, and the molten salt is separated by a siphon method or a pouring method. The separated molten salt is sent to an industrial aluminum electrolysis cell for electrolysis, and Al2O3 produced by aluminum reducing titanium oxide is electrolytically reduced to Al. The cryolite molten salt after electrolysis can be used as a reaction medium for the next batch, and the aluminum liquid after electrolysis can be reduced and used in the next batch, thereby realizing the recycling of cryolite molten salt and aluminum liquid.

[0014] Preferably, the separated alloy is purified, and then the alloy composition is adjusted with aluminum liquid to prepare a qualified commercial aluminum-titanium intermediate alloy.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts environmentally friendly TiO2 as a raw material to directly prepare an aluminum-titanium master alloy, thereby greatly reducing production costs; utilizing the heat generated by aluminum reduction to maintain the progress of the reaction, preventing aluminum liquid from being oxidized under an inert atmosphere, and reducing under a stirring environment can increase the dissolution rate of TiO2 in cryolite melt, thereby strengthening the kinetic conditions of aluminum reduction, and greatly accelerating the rate of in-situ generation of an aluminum-titanium master alloy; the reduced molten salt is fed into an industrial aluminum electrolysis cell for electrolysis, and Al2O3 generated by aluminum reduction of titanium oxide is electrolytically reduced to Al; the cryolite molten salt after electrolysis can be used as a reaction medium for the next batch, and the aluminum liquid after electrolysis is reduced and used in the next batch, thereby realizing the recycling of cryolite molten salt and aluminum liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 This is the SEM morphology of the aluminum-titanium master alloy of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Embodiment 1: See also Figure 1-2A method for preparing an aluminum-titanium master alloy by aluminothermic self-reduction of molten salt, wherein cryolite molten salt (total mass is 150 g) for aluminum electrolysis is selected as a reaction medium, aluminum liquid is used as a reducing agent, and TiO2 is used as a raw material; a certain proportion of cryolite molten salt is first loaded into a reduction device, 5 g of TiO2 powder is added, and the mixture is stirred for 10 minutes under an inert atmosphere to fully and quickly dissolve TiO2 in the molten salt; 30 g of aluminum liquid is added under an inert atmosphere and stirring conditions, and the mixture is subjected to aluminothermic self-reduction for 20 minutes, and then the mixture is allowed to stand for 10 minutes to separate the alloy phase and the molten salt, and then the metal phase and the molten salt are separated; after the separated alloy is adjusted in composition and slag is removed, a commercial aluminum-titanium master alloy is obtained, and the titanium content in the separated alloy is 7.61%, and the aluminum-titanium master alloy with a titanium content of 5% can be obtained after the composition is adjusted; the separated Al2O3-rich molten salt is then fed into an industrial aluminum electrolytic cell, and the cryolite molten salt and aluminum liquid are electrolyzed and recovered for recycling.

[0019] Among them, the cryolite molten salt system is a mixture of sodium fluoroaluminate, aluminum fluoride and calcium fluoride, with a molecular ratio of 2.35.

[0020] Among them, the 950°C cryolite melt can be heated by cryolite molten salt or obtained from an industrial electrolytic cell.

[0021] The aluminum liquid can be aluminum liquid heated from aluminum ingots or high-temperature aluminum liquid in an electrolytic cell.

[0022] The reduction device is provided with a refractory insulation layer, a stainless steel crucible and a graphite crucible. The molten salt is contained in the graphite crucible, the graphite crucible is placed in the stainless steel crucible, and the stainless steel crucible is placed inside the refractory insulation layer. The reduction device is provided with a graphite rod stirring device or an inert gas stirring device. The reduction device is provided with an inert atmosphere inlet and outlet, an inlet and outlet for cryolite molten salt and aluminum liquid, a feeding port for titanium oxide, a sampling port, and a temperature measuring port.

[0023] Among them, the titanium oxide is environmentally friendly TiO2.

[0024] The inert atmosphere is an argon atmosphere, which can avoid oxidation of the aluminum liquid.

[0025] Among them, the stirring device is made of graphite rod or inert anode material, and inert atmosphere blowing stirring can also be used.

[0026] Among them, the alloy phase is separated by a siphon method, a bottom opening aluminum discharge method, and a pouring aluminum discharge method. The molten salt is separated by a siphon method or a pouring method. The separated molten salt is sent to an industrial aluminum electrolysis cell for electrolysis. The Al2O3 produced by the reduction of aluminum to titanium oxide is electrolytically reduced to Al. The cryolite molten salt after electrolysis can be used as a reaction medium for the next batch, and the aluminum liquid after electrolysis can be reduced and used in the next batch, thereby realizing the recycling of cryolite molten salt and aluminum liquid.

[0027] The separated alloy is purified and then the alloy composition is adjusted with aluminum liquid to prepare qualified commercial aluminum-titanium intermediate alloy.

[0028] Embodiment 2: See also Figure 1-2 A method for preparing an aluminum-titanium master alloy by aluminothermic self-reduction of molten salt, wherein cryolite molten salt (total mass of 150 g) for aluminum electrolysis is selected as a reaction medium, aluminum liquid is used as a reducing agent, and TiO2 is used as a raw material; a certain proportion of cryolite molten salt is first loaded into a reduction device, 8 g of TiO2 powder is added, and the mixture is stirred for 10 minutes under an inert atmosphere to fully and quickly dissolve TiO2 in the molten salt; 30 g of aluminum liquid is added under an inert atmosphere and stirring conditions, and the mixture is subjected to aluminothermic self-reduction for 30 minutes, and then the mixture is allowed to stand for 10 minutes to separate the alloy phase and the molten salt, and then the metal phase and the molten salt are separated; after the separated alloy is adjusted in composition and slag is removed, a commercial aluminum-titanium master alloy is obtained, and the titanium content in the separated alloy is 13.64% (SEM morphology as shown in FIG. Figure 2 As shown), the composition can be adjusted to obtain an aluminum-titanium master alloy with a titanium content of 10%; the separated Al2O3-rich molten salt is then sent to an industrial aluminum electrolysis cell to electrolyze and recover cryolite molten salt and aluminum liquid for recycling.

[0029] Among them, the cryolite molten salt system is a mixture of sodium fluoroaluminate, aluminum fluoride and calcium fluoride, with a molecular ratio of 2.35.

[0030] Among them, the 950°C cryolite melt can be heated by cryolite molten salt or obtained from an industrial electrolytic cell.

[0031] The aluminum liquid can be aluminum liquid heated from aluminum ingots or high-temperature aluminum liquid in an electrolytic cell.

[0032] The reduction device is provided with a refractory insulation layer, a stainless steel crucible and a graphite crucible. The molten salt is contained in the graphite crucible, the graphite crucible is placed in the stainless steel crucible, and the stainless steel crucible is placed inside the refractory insulation layer. The reduction device is provided with a graphite rod stirring device or an inert gas stirring device. The reduction device is provided with an inert atmosphere inlet and outlet, an inlet and outlet for cryolite molten salt and aluminum liquid, a feeding port for titanium oxide, a sampling port, and a temperature measuring port.

[0033] Among them, the titanium oxide is environmentally friendly TiO2.

[0034] The inert atmosphere is an argon atmosphere, which can avoid oxidation of the aluminum liquid.

[0035] Among them, the stirring device is made of graphite rod or inert anode material, and inert atmosphere blowing stirring can also be used.

[0036] Among them, the alloy phase is separated by a siphon method, a bottom opening aluminum discharge method, and a pouring aluminum discharge method. The molten salt is separated by a siphon method or a pouring method. The separated molten salt is sent to an industrial aluminum electrolysis cell for electrolysis. The Al2O3 produced by the reduction of aluminum to titanium oxide is electrolytically reduced to Al. The cryolite molten salt after electrolysis can be used as a reaction medium for the next batch, and the aluminum liquid after electrolysis can be reduced and used in the next batch, thereby realizing the recycling of cryolite molten salt and aluminum liquid.

[0037] The separated alloy is purified and then the alloy composition is adjusted with aluminum liquid to prepare qualified commercial aluminum-titanium intermediate alloy.

[0038] Embodiment 3: See also Figure 1-2 A method for preparing an aluminum-titanium master alloy by aluminothermic self-reduction of molten salt, wherein cryolite molten salt (total mass is 150 g) for aluminum electrolysis is selected as a reaction medium, aluminum liquid is used as a reducing agent, and TiO2 is used as a raw material; a certain proportion of cryolite molten salt is first loaded into a reduction device, 12 g of TiO2 powder is added, and the mixture is stirred for 30 minutes under an inert atmosphere to fully and quickly dissolve TiO2 in the molten salt; 30 g of aluminum liquid is added under an inert atmosphere and stirring conditions, and the mixture is subjected to aluminothermic self-reduction for 60 minutes, and then the mixture is allowed to stand for 10 minutes to separate the alloy phase and the molten salt, and then the metal phase and the molten salt are separated; after the separated alloy is adjusted in composition and slag is removed, a commercial aluminum-titanium master alloy is obtained, and the titanium content in the separated alloy is 20.47%, and the aluminum-titanium master alloy with a high titanium content can be obtained after the composition is adjusted; the separated Al2O3-rich molten salt is then fed into an industrial aluminum electrolytic cell, and the cryolite molten salt and aluminum liquid are electrolyzed and recovered for recycling.

[0039] Among them, the cryolite molten salt system is a mixture of sodium fluoroaluminate, aluminum fluoride and calcium fluoride, with a molecular ratio of 2.35.

[0040] Among them, the 950°C cryolite melt can be heated by cryolite molten salt or obtained from an industrial electrolytic cell.

[0041] The aluminum liquid can be aluminum liquid heated from aluminum ingots or high-temperature aluminum liquid in an electrolytic cell.

[0042] The reduction device is provided with a refractory insulation layer, a stainless steel crucible and a graphite crucible. The molten salt is contained in the graphite crucible, the graphite crucible is placed in the stainless steel crucible, and the stainless steel crucible is placed inside the refractory insulation layer. The reduction device is provided with a graphite rod stirring device or an inert gas stirring device. The reduction device is provided with an inert atmosphere inlet and outlet, an inlet and outlet for cryolite molten salt and aluminum liquid, a feeding port for titanium oxide, a sampling port, and a temperature measuring port.

[0043] Among them, the titanium oxide is environmentally friendly TiO2.

[0044] The inert atmosphere is an argon atmosphere, which can avoid oxidation of the aluminum liquid.

[0045] Among them, the stirring device is made of graphite rod or inert anode material, and inert atmosphere blowing stirring can also be used.

[0046] Among them, the alloy phase is separated by a siphon method, a bottom opening aluminum discharge method, and a pouring aluminum discharge method. The molten salt is separated by a siphon method or a pouring method. The separated molten salt is sent to an industrial aluminum electrolysis cell for electrolysis. The Al2O3 produced by the reduction of aluminum to titanium oxide is electrolytically reduced to Al. The cryolite molten salt after electrolysis can be used as a reaction medium for the next batch, and the aluminum liquid after electrolysis can be reduced and used in the next batch, thereby realizing the recycling of cryolite molten salt and aluminum liquid.

[0047] The separated alloy is purified and then the alloy composition is adjusted with aluminum liquid to prepare qualified commercial aluminum-titanium intermediate alloy.

[0048] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an aluminum-titanium master alloy by molten salt aluminothermic self-reduction, characterized in that: Select cryolite molten salt for aluminum electrolysis as the reaction medium, aluminum liquid as the reducing agent, and TiO2 as the raw material; first load a certain proportion of cryolite molten salt into the reduction device, add a certain amount of TiO2 powder, and stir for 10-30 minutes under inert atmosphere conditions to fully and quickly dissolve TiO2 in the molten salt; Aluminum liquid is added under inert atmosphere and stirring conditions, and after thermite self-reduction for 10-60 minutes, the alloy phase and molten salt are allowed to stand for a certain period of time to separate the alloy phase and the molten salt, and then the metal phase and the molten salt are separated; after the separation, the composition of the alloy is adjusted and the slag is removed to obtain a commercial aluminum-titanium intermediate alloy; the separated Al2O3-rich molten salt is then sent to an industrial aluminum electrolytic cell, and the cryolite molten salt and aluminum liquid are electrolyzed and recycled.

2. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: The cryolite molten salt system is a mixture of sodium fluoroaluminate, aluminum fluoride and calcium fluoride with a molecular ratio of 2.0-2.

4.

3. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: The cryolite melt at 930°C-960°C can be heated by cryolite molten salt or obtained from industrial electrolytic cells.

4. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: The aluminum liquid can be the high-temperature aluminum liquid in the aluminum ingot heating or electrolytic cell.

5. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: The reduction device is provided with a refractory insulation layer, a stainless steel crucible and a graphite crucible. The molten salt is contained in the graphite crucible, the graphite crucible is placed in the stainless steel crucible, and the stainless steel crucible is placed inside the refractory insulation layer. The reduction device is provided with a graphite rod stirring device or an inert gas stirring device. The reduction device is provided with an inert atmosphere inlet and outlet, an inlet and outlet for cryolite molten salt and aluminum liquid, a feeding port for titanium oxide, a sampling port and a temperature measuring port.

6. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: Titanium oxide is environmentally friendly TiO2.

7. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: The inert atmosphere is argon atmosphere, which can avoid oxidation of the aluminum liquid.

8. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: The stirring device can be made of a graphite rod or an inert anode material, or an inert atmosphere blowing stirring can be selected.

9. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: The alloy phase is separated by a siphon method, a bottom opening aluminum discharge method, and a pouring aluminum discharge method. The molten salt is separated by a siphon method or a pouring method. The separated molten salt is sent to an industrial aluminum electrolysis cell for electrolysis. Al2O3 produced by aluminum reducing titanium oxide is electrolytically reduced to Al. After electrolysis, the cryolite molten salt can be used as a reaction medium for the next batch, and the aluminum liquid after electrolysis is reduced and used in the next batch, thereby realizing the recycling of cryolite molten salt and aluminum liquid.

10. The method for preparing aluminum-titanium master alloy by molten salt aluminothermic self-reduction according to claim 1, characterized in that: The separated alloy is purified, and then the alloy composition is adjusted with aluminum liquid to prepare qualified commercial aluminum-titanium intermediate alloy.

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