Method for preparing carbide slag from titanium-containing blast furnace slag based on multi-physical field synergistic effect

Abstract

The invention relates to the technical field of smelting, and discloses a method for preparing carbide slag from titanium-containing blast furnace slag based on a multi-physical field synergistic effect, which comprises the following steps: continuously introducing molten titanium-containing blast furnace slag obtained in a blast furnace process into a reactor; in the reactor, generating a high-temperature cavity in a slag layer through the synergistic effect of a plasma torch immersed in the slag and an external rotating magnetic field; carbon-containing gas is injected into the high-temperature cavity, and a laser beam penetrating through the slag layer is synchronously emitted so that the local temperature in the high-temperature cavity can reach the preset temperature; a vapor deposition carbonization reaction of the titanium oxide is completed in the high-temperature cavity to generate titanium carbide; and carrying out gradient cooling and gravity separation on the reacted slag, and recovering a titanium carbide enriched slag layer. The flash selective gas phase carbonization of the titanium oxide is realized by introducing the dual-energy field synergistic effect of the high-frequency pulse plasma torch and the high-energy focused laser beam, and the reaction time is effectively shortened.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and in particular to a method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields. Background Technology

[0002] my country has abundant titanium reserves. Through the traditional blast furnace ironmaking-converter steelmaking process, most of the titanium ends up in the blast furnace slag, which contains 18%–24% TiO2. Many domestic research institutions have conducted research on various titanium extraction technologies from blast furnace slag, such as producing silicon-titanium composite alloys and manufacturing slag microcrystalline glass. However, these methods have limited processing capacity and cannot fundamentally solve the problem of comprehensive utilization of titanium-containing blast furnace slag. Currently, the process route of "high-temperature carbonization-low-temperature chlorination to produce TiCl4" for high-titanium blast furnace slag is the most promising technology for industrialization.

[0003] High-temperature carbonization is a process that uses an electric furnace to smelt high-titanium blast furnace slag. Specifically, TiO2 in the slag is reduced with carbon powder. As smelting progresses, the TiO2 gradually converts to TiC. Near the end of smelting, the TiC content in the slag is approximately 15%, hence the name "carbonized slag." This process has several drawbacks: first, it consumes a lot of electricity and reducing agents, which is detrimental to cost competitiveness; second, the carbonization rate can only reach 90%, resulting in a waste of over 10% of titanium resources; and third, the reaction time is long, lasting 2-3 hours, and current processes are unlikely to operate continuously, leading to low equipment capacity per unit time.

[0004] Therefore, there is a need to improve the existing methods for preparing carbonized slag from titanium-containing blast furnace slag. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields. By introducing the synergistic effect of a high-frequency pulsed plasma torch and a high-energy focused laser beam, the flash selective gas-phase carbonization of titanium oxides is achieved, effectively shortening the reaction time.

[0006] To achieve the above objectives, embodiments of the present invention provide a method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields, comprising the following steps: S1 continuously introduces the molten titanium-containing blast furnace slag obtained from the blast furnace process into the reactor; S2 generates a high-temperature cavity in the slag layer through the synergistic effect of a plasma torch immersed in the molten slag and an external rotating magnetic field inside the reactor. S3 injects carbon-containing gas into the high-temperature cavity and simultaneously emits a laser beam that penetrates the slag layer to make the local temperature inside the high-temperature cavity reach the predetermined temperature. S4 completes the vapor deposition and carbonization reaction of titanium oxide in a high-temperature cavity to generate titanium carbide. S5 performs gradient cooling and gravity separation on the molten slag after the reaction to recover the titanium carbide-enriched slag layer.

[0007] In some embodiments, in S2, the graphite content in the electrodes of the plasma torch is not less than 90% by mass percentage.

[0008] In some embodiments, in S2, the frequency of the rotating magnetic field is 20 Hz to 100 Hz, and the magnetic field strength is 0.3 T to 0.8 T.

[0009] In some embodiments, in S3, the carbon-containing gas is a mixture of supercritical CO2 and CH4 with a critical pressure of not less than 7.4 MPa, which is injected into a high-temperature cavity through a porous element set at the bottom of the reactor to form a cluster of microbubbles with a diameter of 0.1 mm to 1 mm.

[0010] In some embodiments, S3 further includes: adding a sulfur fixative to the reaction system, wherein the sulfur fixative is elemental sulfur or H2S gas, and the amount added is 20% to 25% of the mass of the molten titanium-containing blast furnace slag.

[0011] In some embodiments, in S3, the wavelength of the laser beam is 450 nm to 550 nm.

[0012] In some implementations, the laser operates in pulses, with a single pulse having an energy of no more than 500 J, a pulse width of 1 ms to 10 ms, and an interval of no less than 100 ms between laser pulses.

[0013] In some implementations, in S3, the predetermined temperature is ≥5000°C.

[0014] In some embodiments, the reaction tail gas generated in S4 is purified and reused to provide a protective atmosphere for the slag conveying chute or tundish in S1.

[0015] In some embodiments, in S5, gradient cooling includes: holding the reacted slag at 1100℃~1200℃ for 5min~10min; followed by step cooling, with the upper part using air cooling at a rate of approximately 8℃ / s~10℃ / s, and the lower part using water-cooled copper plates at a rate of approximately 900℃ / s~1000℃ / s.

[0016] The present invention has at least the following beneficial technical effects: (1) By using a high-frequency pulsed plasma torch and a high-energy focused laser beam to excite the two energy fields, the reaction time of 2 to 3 hours required by the traditional carbonization process is compressed to the millisecond level, the reaction rate is increased by more than 1,000 times, and flash carbonization is realized, which provides the possibility for continuous and high-efficiency production. (2) Under the combined effect of ultra-high temperature and selective laser excitation, the carbonization conversion rate of titanium is greatly improved, which significantly reduces the waste of titanium resources and enhances the comprehensive utilization value of high-titanium blast furnace slag. (3) In the final product: the total content of SiC+Al4C3+CaC2 is <3wt%, the content of TiC is >35wt%, ensuring that the priority of titanium carbide is >99% and the impurity carbide rate is <5%; the content of titanium carbide is much higher than the current level of 13wt%~15wt%. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating an embodiment of the method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0020] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0021] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] like Figure 1The present invention illustrates a method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields, comprising: S1 continuously introduces the molten titanium-containing blast furnace slag obtained from the blast furnace process into the reactor; S2 generates a high-temperature cavity in the slag layer through the synergistic effect of a plasma torch immersed in the molten slag and an external rotating magnetic field inside the reactor. S3 injects carbon-containing gas into the high-temperature cavity and simultaneously emits a laser beam that penetrates the slag layer to make the local temperature inside the high-temperature cavity reach the predetermined temperature. S4 completes the vapor deposition and carbonization reaction of titanium oxide in a high-temperature cavity to generate titanium carbide. S5 performs gradient cooling and gravity separation on the molten slag after the reaction to recover the titanium carbide-enriched slag layer.

[0023] In S2, the plasma torch electrode contains 90 wt% graphite, and the consumption rate is in balance with the amount of carbon required for the carbonization reaction.

[0024] In S2, the high-temperature cavity confined by the rotating magnetic field is generated by inducing eddy currents in the molten slag through a three-phase rotating magnetic field generator, which produces a continuous radial centrifugal force, so that the cavity formed by the plasma torch blow-out maintains a stable shape under conditions without physical isolation; the frequency of the rotating magnetic field is 20-100Hz, and the magnetic field strength is 0.3-0.8T. Experiments have shown that this range can balance the viscosity of the molten slag and the centrifugal force, and avoid splashing.

[0025] In S3, the carbon-containing gas is a mixture of supercritical CO2 and CH4 (critical pressure ≥ 7.4 MPa), which is injected through a porous plug at the bottom of the slag layer to form a cluster of microbubbles (0.1-1 mm in diameter).

[0026] S3 also includes: adding a sulfur fixative to the reaction system, adding about 20% to 25% of elemental sulfur or H2S gas by mass of blast furnace slag (determined according to the calcium and magnesium content in the blast furnace slag), and using sulfur to directionally fix calcium and aluminum to form thermodynamically stable sulfides, so that impurity elements preferentially form sulfides rather than carbides.

[0027] In S3, the laser beam wavelength is selected to be 450-550nm, which matches the absorption spectrum of titanium oxide in the molten slag, ensuring highly selective carbonization of titanium and other impurity elements, especially silicon.

[0028] In S3, the laser single pulse energy is ≤500J, the pulse width is 1~10ms, and the pulse interval is ≥100ms (limiting heat accumulation), which further ensures the selective carbonization of titanium, since other impurity elements require a longer carbon diffusion time than titanium.

[0029] It is worth noting that the TiC formation rate constant (kTiC ≈ 10³ s) - ¹) is SiC (kSiC ≈ 10- ¹s - ¹) of 10 4 Multiphysics simulations show that when the 5000℃ high temperature is maintained for only 3-5ms, the TiC formation rate is 98% and the SiC formation rate is 4.2%; when the high temperature is maintained for more than 100ms, the SiC formation rate soars to 41%.

[0030] In S3, the predetermined temperature is ≥5000℃.

[0031] In S4, the reaction tail gas (containing CO / H2) is purified and reused to provide a protective atmosphere for the slag conveying chute or tundish in S1.

[0032] In S5, gradient cooling includes: holding the reacted slag at 1100℃~1200℃ for 5 min~10 min; followed by step cooling, with air cooling in the upper part at a cooling rate of about 8℃ / s~10℃ / s, and water cooling copper plate cooling in the lower part at a cooling rate of about 900℃ / s~1000℃ / s.

[0033] In step S5, during the gradient cooling process, the TiC enriched layer is held at 1100-1200℃ for 5-10 min to promote TiC grain growth. This optimizes grain size while minimizing side reactions.

[0034] In S5, the upper part of the stepped cooling separation chamber is equipped with air-cooled nozzles (cooling rate 8~10℃ / s), and the lower part is equipped with water-cooled copper plates (cooling rate 900~1000℃ / s).

[0035] It should be explained that in S5, gravity separation utilizes the fact that the density of TiC (4.93 g / cm³) is less than that of the slag phase (3.2-3.5 g / cm³) to achieve flotation enrichment.

[0036] This invention abandons the traditional resistance furnace / electric arc furnace heating and introduces the synergistic effect of a dual energy source of "high-frequency pulsed plasma torch" + "high-energy focused laser beam". It adopts the "titanium atom vapor deposition carbonization" mechanism and compresses the traditional hour-level carbonization reaction to the millisecond level (laser pulse action time) through dual energy field coupling, thus achieving "flash carbonization".

[0037] The method of this invention has significant advantages such as extremely high reaction rate (more than 1,000 times higher, second-level vs. hour-level), high titanium conversion rate (approaching 100%), and low energy consumption. This patent aims to provide a new theoretical paradigm and provide direction for the technological upgrading of future carbonization processes.

[0038] The present invention will be further explained below with reference to specific embodiments.

[0039] Example 1 Raw material: Molten titanium-containing blast furnace slag from a certain blast furnace, with a slag temperature of approximately 1450℃.

[0040] Main equipment: continuous feed reactor with refractory lining and bottom porous plug; high-frequency pulsed plasma torch system with electrodes containing 90wt% graphite; three-phase rotating magnetic field generator (frequency adjustable range 10-150Hz, magnetic field strength 0.1-1.0T); high-energy pulsed laser (wavelength 532nm, maximum single pulse energy 600J, pulse width 1-20ms adjustable); supercritical fluid supply system; gradient cooling-gravity separation chamber (equipped with air-cooled nozzle group and water-cooled copper plate).

[0041] S1 Feed: The above-mentioned molten blast furnace slag is continuously introduced into the reactor at a rate of 5 kg / min.

[0042] S2 Constructing the Reaction Cavity: Immerse the plasma torch approximately 200 mm below the slag layer and start it with an input power of 80 kW. Simultaneously start the rotating magnetic field generator, setting the frequency to 60 Hz and the magnetic field strength to 0.5 T. At this time, a pear-shaped high-temperature cavity with a diameter of approximately 50 mm, stably enveloped by rotating molten slag, is formed above the plasma torch nozzle.

[0043] S3 introduces a carbon source and ultrafast excitation: A mixture of CO2 and CH4 preheated to 40°C and pressure 8.0 MPa (supercritical state) is injected into the cavity through a porous plug at the bottom, forming a cluster of microbubbles with an average diameter of approximately 0.5 mm. Simultaneously, a focused laser beam with a wavelength of 532 nm is emitted into this cavity region. The laser parameters are set as follows: single pulse energy 450 J, pulse width 5 ms, and pulse interval 150 ms. Atomized elemental sulfur, accounting for 22% of the blast furnace slag mass, is sprayed into the reaction system. Temperature monitoring shows that the temperature at the center of the cavity instantaneously reaches 5200 ± 200°C during the laser pulse.

[0044] S4 Reaction and Tail Gas Treatment: Under these conditions, TiO2 in the cavity rapidly vaporizes, and titanium vapor reacts with activated carbon produced by CH4 decomposition to undergo a vapor-phase deposition reaction, generating TiC nanoparticles. The resulting reaction tail gas is purified by cyclone dust removal and cooling, and then introduced above the molten slag insulation chute as a protective gas.

[0045] S5 Product Separation: The molten slag after the reaction flows into the gradient cooling separation chamber. First, it is held at 1150℃ for 8 minutes to moderately coarsen the fine TiC particles. Then, stepped cooling is initiated: the upper air-cooling system cools the surface slag at a rate of approximately 10℃ / s; the lower water-cooled copper plate rapidly cools the bottom slag at a rate of approximately 1000℃ / s. Because the density of TiC (4.93 g / cm³) is less than that of the main slag phase (approximately 3.4 g / cm³), the TiC particles float and accumulate in the upper part of the slag. After cooling and solidification, the TiC-enriched layer (upper slag) is separated by physical crushing and sieving.

[0046] Based on multiphysics simulation and reaction kinetics calculations, the carbonization conversion rate of titanium is expected to be >99% under this millisecond-level ultra-high temperature pulse. The final TiC-enriched layer is expected to contain >36 wt% TiC, while the total content of impurity carbides such as SiC, Al4C3, and CaC2 is <2.5 wt%. The core time of a single carbonization reaction (laser pulse duration) is in the millisecond range.

[0047] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0048] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0049] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0050] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for preparing carbonized slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields, characterized in that, include: S1 continuously introduces the molten titanium-containing blast furnace slag obtained from the blast furnace process into the reactor; S2 generates a high-temperature cavity in the slag layer through the synergistic effect of a plasma torch immersed in the molten slag and an external rotating magnetic field within the reactor. S3 injects carbon-containing gas into the high-temperature cavity and simultaneously emits a laser beam that penetrates the slag layer to make the local temperature inside the high-temperature cavity reach a predetermined temperature. S4 completes the vapor deposition and carbonization reaction of titanium oxide in the high-temperature cavity to generate titanium carbide. S5 performs gradient cooling and gravity separation on the molten slag after the reaction to recover the titanium carbide-enriched slag layer.

2. The method for preparing carbonized slag from titanium-bearing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 1, characterized in that, In S2, the graphite content in the electrodes of the plasma torch is not less than 90% by mass percentage.

3. The method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 1, characterized in that, In S2, the frequency of the rotating magnetic field is 20 Hz ~ 100 Hz, and the magnetic field strength is 0.3 T ~ 0.8 T.

4. The method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 1, characterized in that, In S3, the carbon-containing gas is a mixture of supercritical CO2 and CH4 with a critical pressure of not less than 7.4 MPa. It is injected into the high-temperature cavity through a porous element set at the bottom of the reactor to form a group of microbubbles with a diameter of 0.1 mm to 1 mm.

5. The method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 1, characterized in that, S3 further includes: adding a sulfur fixative to the reaction system, wherein the sulfur fixative is elemental sulfur or H2S gas, and the amount added is 20% to 25% of the mass of the molten titanium-containing blast furnace slag.

6. The method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 1, characterized in that, In S3, the wavelength of the laser beam is 450 nm to 550 nm.

7. The method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 6, characterized in that, The laser operates in pulse form, with the energy of a single pulse not exceeding 500 J, the pulse width being 1 ms to 10 ms, and the interval between laser pulses not less than 100 ms.

8. The method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 1, characterized in that, In S3, the predetermined temperature is ≥5000℃.

9. The method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 1, characterized in that, The reaction tail gas generated in S4 is purified and reused to provide a protective atmosphere for the slag conveying chute or tundish in S1.

10. The method for preparing carbide slag from titanium-containing blast furnace slag based on the synergistic effect of multiple physical fields according to claim 1, characterized in that, In S5, the gradient cooling includes: holding the reacted slag at 1100℃~1200℃ for 5 min~10 min; then performing step cooling, with the upper part using air cooling at a rate of about 8℃ / s~10℃ / s, and the lower part using water-cooled copper plate cooling at a rate of about 900℃ / s~1000℃ / s.

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