Method for synergistically regenerating TiAl3, high-purity silicon and electrolytic aluminum and circulating elements based on thermal-state titanium-containing blast furnace slag and aluminum waste

Abstract

The invention discloses a method for synergistically regenerating TiAl3, high-purity silicon and electrolytic aluminum and circulating elements based on thermal-state titanium-containing blast furnace slag and aluminum waste, and belongs to the technical field of metallurgy and solid waste recycling. According to the method, the titanium-containing blast furnace slag and carried heat are jointly utilized for the first time, the hot titanium-containing blast furnace slag just discharged from a blast furnace is transferred into a molten pool through a chute, collaborative utilization of slag heat is achieved, and reduction energy consumption is reduced; the reducing agent is matched with mixed waste aluminum, and the pain point of the waste aluminum recovery industry is overcome. Reactants in the molten pool can be naturally layered, a light titanium-aluminum alloy phase rich in elements such as titanium and silicon is located on the upper layer, and a residual slag phase after reduction is located on the lower layer. And the upper layer can be separated through a two-stage high-temperature filtering technology, and impurities are removed to obtain the high-purity TiAl3 alloy and high-purity Si. The lower layer can be roasted with NaOH and washed with water to recycle Al2O3, and electrolytic aluminum can be obtained through further electrolysis.

Description

Technical Field

[0001] This invention belongs to the field of metallurgy and solid waste resource utilization technology, specifically relating to a method for the synergistic regeneration of TiAl3, high-purity silicon, electrolytic aluminum, and element recycling based on hot titanium-containing blast furnace slag and aluminum waste. Background Technology

[0002] Titanium resources are mainly low-grade primary ilmenite, which is difficult to beneficiate and has poor practical applicability. After beneficiation, approximately 50% of the Ti in vanadium-titanium magnetite enters the iron concentrate. The Ti in the iron concentrate cannot be reduced during ironmaking and ultimately remains mostly in titanium-containing blast furnace slag. The large-scale accumulation of titanium-containing blast furnace slag by steel companies not only wastes titanium resources but also causes environmental pollution.

[0003] The sources of scrap aluminum are unstable and often mixed with metallic impurities (Fe, Mg, Sr, etc.), non-metallic contaminants (plastics, coatings, oil stains), and alloy cross-contamination (such as aluminum-magnesium alloys mixed with aluminum-silicon alloys). Although physical separation (heavy media separation, parabolic separation) can separate heavy metal impurities, scrap aluminum with an iron content exceeding 1.5% is still difficult to use directly in the production of high-end alloys.

[0004] Existing technologies employ cold-state titanium-containing blast furnace slag mixed with aluminum materials for smelting, and then separate the Ti-Si-Al alloy through directional solidification. This process relies on a slow temperature gradient, causing the high-melting-point Ti-Si phase to crystallize preferentially, while the low-melting-point Al-Si phase becomes enriched at the ends. The overall process suffers from high energy consumption, low separation efficiency, and fails to utilize the slag phase. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the co-regeneration of TiAl3, high-purity silicon, electrolytic aluminum, and element recycling based on hot titanium-containing blast furnace slag and aluminum waste. Based on the "hot slag-aluminum waste co-regeneration" system, the sensible heat of the slag is utilized to reduce smelting energy consumption; separation efficiency is improved and separation energy consumption is reduced by changing the separation process; and resource recycling is achieved through technological restructuring.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions of this invention is to provide a method for the synergistic regeneration of TiAl3, high-purity silicon, and electrolytic aluminum based on hot titanium-containing blast furnace slag and aluminum waste, comprising the following steps:

[0008] Hot titanium-containing blast furnace slag, aluminum waste and additives are added to the molten pool and held at 1673-1973 K for 1.0-5.0 h to obtain a melt with an alloy phase on the upper layer and a slag phase on the lower layer. The slag and the metal are separated to obtain Al-Ti-Si alloy and slag phase A.

[0009] The Al-Ti-Si alloy was filtered at high temperature to obtain TiAl3 alloy and Al-Si alloy with high silicon content;

[0010] The TiAl3 alloy was ground and acid-washed to remove impurities, resulting in a high-purity TiAl3 alloy.

[0011] The high-silicon-content Al-Si alloy is filtered at high temperature (B) to obtain silicon and low-silicon-content Al-Si alloys.

[0012] The silicon is ground and acid-washed to remove impurities, resulting in high-purity silicon.

[0013] The slag phase A was mixed with NaOH and calcined, then washed with water to obtain Al2O3 and slag phase B;

[0014] The Al2O3 is electrolyzed to obtain Al;

[0015] The titanium-containing blast furnace slag contains 20-30 wt% TiO2 and 20-25 wt% SiO2.

[0016] The mass fraction of Al in the aluminum scrap is not less than 85 wt%.

[0017] The mass fraction of CaO in the additive is not less than 80 wt%;

[0018] The mass ratio of titanium-containing blast furnace slag to aluminum waste is (1-2):1; the mass ratio of titanium-containing blast furnace slag to additives is (3-6):1.

[0019] The TiAl3 (titanium aluminum) isolated by this invention is a lightweight material with high specific strength, excellent high-temperature stability and oxidation resistance. It is suitable for manufacturing key components for extreme environments such as aerospace engines and gas turbines, and can also be applied to composite materials, protective coatings and other technical fields.

[0020] The recycling process of this invention can achieve a titanium recovery rate of more than 83%.

[0021] Optionally, the aluminum scrap is cast aluminum alloy or other aluminum scrap that is difficult to recycle.

[0022] Optionally, the additive is calcium oxide, limestone, or solid waste containing calcium oxide.

[0023] Preferably, the high-temperature filter A has a filtration temperature of 1073–1273 K and filters under gravity or pressure conditions.

[0024] Preferably, when removing impurities from the TiAl3 alloy, the grinding particle size is <200μm, the pickling temperature is 298~363K, the pickling time is 0.5~3.0h, and the acid used is a mixture of nitric acid and hydrofluoric acid with a volume ratio of 15:(1~1.5).

[0025] The high-purity TiAl3 alloy after pickling according to this invention has a purity greater than 99%.

[0026] Preferably, the high-temperature filter B has a filtration temperature of 850-900K and filters under gravity or pressure conditions.

[0027] Preferably, during the silicon impurity removal process, the grinding particle size is <200μm, the acid washing temperature is 298-363K, the time is 0.5-3.0h, and the acid used is a mixture of nitric acid and hydrofluoric acid with a volume ratio of 20:(1-2).

[0028] The high-purity silicon obtained after acid washing according to this invention has a purity greater than 99.9%.

[0029] Preferably, the mass ratio of slag phase A to NaOH during the roasting process is 1:(1.2-1.5), the temperature is 1073-1273K, and the time is 0.5-2.0h.

[0030] The second technical solution of this invention provides a method for the synergistic regeneration of TiAl3, high-purity silicon, electrolytic aluminum, and element recycling based on hot titanium-containing blast furnace slag and aluminum waste, comprising the following steps:

[0031] The above-mentioned method for the co-regeneration of TiAl3, high-purity silicon, and electrolytic aluminum based on hot titanium-containing blast furnace slag and aluminum waste is implemented; the resulting low-silicon Al-Si alloy and / or electrolytic aluminum are returned to the molten pool as aluminum waste; the resulting slag phase B is returned to the molten pool as an additive, forming an element cycle.

[0032] The process flow diagram of this invention, which involves the synergistic regeneration of TiAl3 and high-purity silicon from hot titanium-containing blast furnace slag and aluminum waste, and the realization of element recycling, is shown below. Figure 1 .

[0033] A schematic diagram of the "hot slag-waste aluminum co-regeneration" system of this invention is shown below. Figure 2 .

[0034] The beneficial technical effects of the present invention are as follows:

[0035] (1) Innovation on the raw material side: For the first time, titanium-containing blast furnace slag and the heat it carries are used together. The hot titanium-containing blast furnace slag that has just been discharged from the blast furnace is transferred to the molten pool through the chute to realize the synergistic utilization of slag and heat and reduce the energy consumption of reduction; the reducing agent is compatible with mixed waste aluminum, which overcomes the pain points of the waste aluminum recycling industry.

[0036] (2) Intermittent Operation: Aluminum and hot titanium-containing blast furnace slag are added to the molten pool at an aluminum-to-slag ratio of 2-1:1 for reaction. Utilizing the density difference of the products (the density of the titanium-aluminum alloy is less than that of the remaining slag phase), natural stratification is achieved in the molten pool after the reaction. At the end of the reaction, the lightweight titanium-aluminum alloy phase rich in titanium, silicon, and other elements is located in the upper layer, while the reduced residual slag phase is located in the lower layer. At this point, the lower residual slag phase can be discharged through the bottom slag outlet. After the slag phase is discharged, new hot titanium-containing blast furnace slag is added to the furnace. When the aluminum phase is consumed to the point where it can no longer react effectively, the upper titanium-aluminum alloy phase is first discharged through the aluminum outlet of the furnace body, and then the final residual slag phase is discharged through the bottom slag outlet. This "reaction-stratification-slag discharge-slag replenishment" cyclic operation mode can significantly improve equipment utilization and production efficiency, and reduce heat loss and the number of start-ups and shutdowns.

[0037] (3) Separation process: A two-stage high-temperature filtration technology is used to replace directional solidification. The first-stage high-temperature filtration separates the Al-Ti-Si alloy product of aluminothermic reduction of titanium blast furnace slag into TiAl3 alloy and Al-Si alloy. The second-stage high-temperature filtration separates the Al-Si alloy into silicon and Al-Si alloy with lower silicon content. The Al-Si alloy can be recycled as aluminum material, providing a new path for the economical utilization of complex titanium-containing blast furnace slag resources.

[0038] The fundamental difference between high-temperature filtration and directional solidification (CN109402420A) lies in the following: High-temperature filtration achieves solid-liquid physical sieving based on melting point differences under isothermal conditions (e.g., retaining the TiAl3 solid phase at 1273K and sieving out the Al-Si liquid phase), its core being mechanical sieving; directional solidification, on the other hand, relies on the segregation effect induced by temperature gradients, where the high-melting-point Ti-Si phase preferentially crystallizes through layer-by-layer solidification of the melt, while the low-melting-point Al-Si phase is enriched at the ends, essentially a phase transition-driven atomic diffusion process. The advantages of high-temperature filtration are: shorter separation time, increased efficiency, and reduced energy consumption.

[0039] (4) Recycling of waste residue: For the first time, we attempted to separate the product slag phase of aluminothermic reduction of titanium blast furnace slag by a method of mixed roasting followed by water washing to obtain Al2O3 and residue. The Al2O3 is electrolyzed to regenerate aluminum, forming an internal cycle of aluminum resources; the obtained residue can be used as building materials or recycled as an additive, providing a new path for the economic utilization of complex titanium-containing blast furnace slag resources. Attached Figure Description

[0040] Figure 1 This is a process flow diagram of the present invention based on the synergistic regeneration of TiAl3 and high-purity silicon from hot titanium-containing blast furnace slag and aluminum waste, and the realization of element recycling.

[0041] Figure 2 This is a schematic diagram of the "hot slag-waste aluminum co-regeneration" system of the present invention.

[0042] Figure 3 The images shown are macroscopic and SEM images of the Al-Si-Ti alloy samples before and after high-temperature filtration in Example 1 of this invention. In the images, a is a macroscopic image of the Al-Si-Ti alloy before high-temperature filtration, b1 is a macroscopic image of the TiAl3 alloy after high-temperature filtration, b2 and b3 are SEM images of the TiAl3 alloy after high-temperature filtration at different magnifications, c1 is a macroscopic image of the Ai-Si alloy after high-temperature filtration, and c2 and c3 are SEM images of the Ai-Si alloy after high-temperature filtration at different magnifications.

[0043] Figure 4 The images shown are macroscopic images and XRD patterns of the Ai-Si alloy samples before and after secondary high-temperature filtration in Example 1 of this invention. In the images, a is a macroscopic image of the Ai-Si alloy before secondary high-temperature filtration, b1 and b2 are macroscopic images of silicon after secondary high-temperature filtration, b3 is an XRD pattern of silicon after secondary high-temperature filtration, c1 and c2 are macroscopic images of the Ai-Si alloy after secondary high-temperature filtration, and c3 is an XRD pattern of the Ai-Si alloy after secondary high-temperature filtration. Detailed Implementation

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0045] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0046] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0047] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0048] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0049] Example 1

[0050] raw material:

[0051] Titanium-containing blast furnace slag (containing 21.6 wt% TiO2 and 22.9 wt% SiO2);

[0052] Aluminum scrap (cast aluminum alloy, containing 92.6 wt% Al, 7 wt% Si, and 0.4% Mg, accounting for 40% of the total raw material mass);

[0053] Additive (industrial calcium oxide, containing 94 wt% CaO, accounting for 12% of the total mass of raw materials).

[0054] step:

[0055] 1. Reduction smelting: After pre-melting aluminum scrap in an electric arc furnace, a mixture of titanium-containing blast furnace slag and additives is added, and the mixture is smelted at 1823 K for 3 hours to produce a Ti-Si-Al alloy (composition: Ti 24wt%, Si 25wt%, Al 50wt%) and slag (TiO2 < 1.0wt% in the slag). The slag phase is in the lower layer, and the Ti-Si-Al alloy phase is in the upper layer.

[0056] 2. High-temperature filtration: The Ti-Si-Al alloy is transferred to a preheated filtration device and filtered at 1273K and 500G. The retained phase consists of high-melting-point TiAl3 particles (melting point 1613K) and a small amount of Ti-Si compounds; the liquid phase is a high-silicon, low-melting-point Al-Si alloy (melting point 850K).

[0057] Secondary high-temperature filtration: The high-silicon, low-melting-point Al-Si alloy is transferred to a preheated filtration device and filtered at 900K and 500G. The retained phase is high-melting-point Si (melting point 1687K); the liquid phase is low-melting-point Al-Si alloy (melting point 850K).

[0058] 3. Product refining:

[0059] The TiAl3 phase was ball-milled to 200 mesh (74 μm) and then acid-washed with a mixture of nitric acid and hydrofluoric acid in a volume ratio of 15:1 (323 K × 30 min) to obtain high-purity TiAl3 powder (purity > 99.1%, Ti recovery rate 84.2%).

[0060] Si was ball-milled to 200 mesh (74 μm) and then acid-washed with a mixture of nitric acid and hydrofluoric acid in a volume ratio of 20:1 (323 K × 10 min) to obtain high-purity Si powder (purity > 99.9%).

[0061] 4. Slag phase treatment:

[0062] NaOH and slag were mixed at a mass ratio of 1.2:1 and calcined for 2 hours, followed by water leaching to obtain Al2O3 (purity >98%) and residue.

[0063] Al2O3 is further electrolyzed to obtain Al (purity >99.9%).

[0064] The residue can be recycled as an additive, and Al and Al-Si alloys can be recycled as aluminum waste.

[0065] Figure 3 The images shown are macroscopic and SEM images of the Al-Si-Ti alloy samples before and after high-temperature filtration in Example 1 of this invention. In the images, a is a macroscopic image of the Al-Si-Ti alloy before high-temperature filtration, b1 is a macroscopic image of the TiAl3 alloy after high-temperature filtration, b2 and b3 are SEM images of the TiAl3 alloy after high-temperature filtration at different magnifications, c1 is a macroscopic image of the Ai-Si alloy after high-temperature filtration, and c2 and c3 are SEM images of the Ai-Si alloy after high-temperature filtration at different magnifications.

[0066] from Figure 3 As can be seen, after filtration, b2 and b3 are lamellar structures containing a small amount of residual Al-Si phase; after filtration, c2 and c3 have typical Al-Si eutectic structures, composed of needle-like silicon phase (bright color) and aluminum phase (dark color). This indicates that high-temperature filtration successfully achieved the physical separation of the TiAl3 phase and the Al-Si phase.

[0067] Figure 4 The images shown are macroscopic images and XRD patterns of the Ai-Si alloy samples before and after secondary high-temperature filtration in Example 1 of this invention. In the images, a is a macroscopic image of the Ai-Si alloy before secondary high-temperature filtration, b1 is a macroscopic image of silicon after secondary high-temperature filtration, b2 is an XRD pattern of silicon after secondary high-temperature filtration, c1 is a macroscopic image of the Ai-Si alloy after secondary high-temperature filtration, and c2 is an XRD pattern of the Ai-Si alloy after secondary high-temperature filtration.

[0068] from Figure 4 As can be seen, after filtration, b2 is dominated by Si peaks with weaker Al peaks; after filtration, c2 is dominated by Al peaks with weaker Si peaks. This indicates that high-temperature filtration successfully achieved the physical separation of the high-purity Si phase and the Al-Si phase.

[0069] Example 2

[0070] raw material:

[0071] Titanium-containing blast furnace slag (containing 21.6 wt% TiO2 and 22.9 wt% SiO2);

[0072] Aluminum scrap (cast aluminum alloy, containing 92.6 wt% Al, 7 wt% Si, and 0.4% Mg, accounting for 40% of the total raw material mass);

[0073] Additive (the residue obtained from the slag phase treatment in Example 1, CaO 80wt%, accounting for 15% of the total mass of the raw materials).

[0074] 1. Reduction smelting: Aluminum scrap is pre-melted in an electric arc furnace, and mixed titanium-containing blast furnace slag and additives are added. The furnace is smelted at 1873 K for 3 hours to produce a Ti-Si-Al alloy (composition: Ti 14wt%, Si 18wt%, Al 67wt%) and slag (TiO2 < 1.0wt% in the slag). The slag phase is in the lower layer, and the Ti-Si-Al alloy phase is in the upper layer.

[0075] 2. High-temperature filtration: The Ti-Si-Al alloy is transferred to a preheated filtration device and filtered at 1273K and 3MPa. The retained phase consists of high-melting-point TiAl3 particles (melting point 1613K) and a small amount of Ti-Si compounds; the liquid phase is a low-melting-point Al-Si alloy (melting point 850K).

[0076] Secondary high-temperature filtration: The Ai-Si alloy is transferred to a preheated filtration device and filtered at 900K and 3MPa. The retained phase is high-melting-point Si (melting point 1687K); the liquid phase is low-melting-point Al-Si alloy (melting point 850K).

[0077] 3. Product refining:

[0078] The TiAl3 phase was ball-milled to 200 mesh (74 μm) and then acid-washed with a mixture of nitric acid and hydrofluoric acid in a volume ratio of 15:1 (323 K × 30 min) to obtain high-purity TiAl3 powder (purity > 99%, Ti recovery rate 83.1%).

[0079] Si was ball-milled to 200 mesh (74 μm) and then acid-washed with a mixture of nitric acid and hydrofluoric acid in a volume ratio of 20:1 (323 K × 10 min) to obtain high-purity Si powder (purity > 99.9%).

[0080] 4. Slag phase treatment:

[0081] NaOH and slag were mixed at a mass ratio of 1.2:1 and calcined for 2 hours, followed by water leaching to obtain Al2O3 (purity >98%) and residue.

[0082] Al2O3 is further electrolyzed to obtain Al (purity >99.9%).

[0083] The residue can be recycled as an additive, and Al and Al-Si alloys can be recycled as aluminum waste.

[0084] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for the co-regeneration of TiAl3, high-purity silicon, and electrolytic aluminum based on hot titanium-containing blast furnace slag and aluminum waste, characterized in that, Includes the following steps: Hot titanium-containing blast furnace slag, aluminum waste and additives are added to the molten pool and held at 1673-1973 K for 1.0-5.0 h to obtain a melt with an alloy phase on the upper layer and a slag phase on the lower layer. The slag and the metal are separated to obtain Al-Ti-Si alloy and slag phase A. The Al-Ti-Si alloy was filtered at high temperature to obtain TiAl3 alloy and Al-Si alloy with high silicon content; The TiAl3 alloy was ground and acid-washed to remove impurities, resulting in a high-purity TiAl3 alloy. The high-silicon-content Al-Si alloy is filtered at high temperature (B) to obtain silicon and low-silicon-content Al-Si alloys. The silicon is ground and acid-washed to remove impurities, resulting in high-purity silicon. The slag phase A was mixed with NaOH and calcined, then washed with water to obtain Al2O3 and slag phase B; The Al2O3 is electrolyzed to obtain Al; The titanium-containing blast furnace slag contains 20-30 wt% TiO2 and 20-25 wt% SiO2. The mass fraction of Al in the aluminum scrap is not less than 85 wt%. The mass fraction of CaO in the additive is not less than 80 wt%; The mass ratio of titanium-containing blast furnace slag to aluminum waste is (1-2):1; the mass ratio of titanium-containing blast furnace slag to additives is (3-6):

1.

2. The method for co-regenerating TiAl3, high-purity silicon, and electrolytic aluminum based on hot titanium-containing blast furnace slag and aluminum waste according to claim 1, characterized in that, The high-temperature filter A has a filtration temperature of 1073–1273 K and filters under gravity or pressure conditions.

3. The method for co-regenerating TiAl3, high-purity silicon, and electrolytic aluminum based on hot titanium-containing blast furnace slag and aluminum waste according to claim 1, characterized in that, When removing impurities from the TiAl3 alloy, the grinding particle size is <200μm, the pickling temperature is 298~363K, the pickling time is 0.5~3.0h, and the acid used is a mixture of nitric acid and hydrofluoric acid with a volume ratio of 15:(1~1.5).

4. The method for co-regenerating TiAl3, high-purity silicon, and electrolytic aluminum based on hot titanium-containing blast furnace slag and aluminum waste according to claim 1, characterized in that, The high-temperature filter B has a filtration temperature of 850-900K and filters under gravity or pressure conditions.

5. The method for co-regenerating TiAl3, high-purity silicon, and electrolytic aluminum based on hot titanium-containing blast furnace slag and aluminum waste according to claim 1, characterized in that, During the removal of impurities from the silicon, the grinding particle size is <200μm, the acid washing temperature is 298~363K, the time is 0.5~3.0h, and the acid used is a mixture of nitric acid and hydrofluoric acid with a volume ratio of 20:(1~2).

6. The method for co-regenerating TiAl3, high-purity silicon, and electrolytic aluminum based on hot titanium-containing blast furnace slag and aluminum waste according to claim 1, characterized in that, During the roasting process, the mass ratio of slag phase A to NaOH is 1:(1.2-1.5), the temperature is 1073-1273K, and the time is 0.5-2.0h.

7. A method for the synergistic regeneration of TiAl3, high-purity silicon, electrolytic aluminum, and element recycling based on hot titanium-containing blast furnace slag and aluminum waste, characterized in that... Includes the following steps: The method described in any one of claims 1 to 6, based on the co-regeneration of TiAl3, high-purity silicon, and electrolytic aluminum from hot titanium-containing blast furnace slag and aluminum waste, is used to recycle the resulting low-silicon Al-Si alloy and / or electrolytic aluminum as aluminum waste back into the molten pool; the resulting slag phase B is returned to the molten pool as an additive, forming an element cycle.

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