Method for selectively extracting gallium from vanadium extraction converter sludge through microwave enhancement

Abstract

The invention discloses a method for microwave-enhanced selective extraction of gallium from vanadium extraction converter sludge, and belongs to the technical field of metallurgical waste treatment. In order to realize low-energy-consumption and high-selectivity extraction of trace gallium in vanadium converter sludge, the invention provides a microwave-enhanced selective gallium extraction method, which comprises the following steps: pretreating vanadium converter sludge, and then mixing the pretreated vanadium converter sludge with a wave-absorbing tempering agent; and carrying out microwave irradiation treatment in a single-frequency microwave or power change microwave or multi-frequency microwave synergistic manner, and leaching to obtain the gallium-containing leachate. According to the method, on the basis of selective bulk phase heating characteristics of microwaves, different mineral phases are induced to generate intergranular fracture and microcracks due to mismatching of thermal expansion coefficients, so that efficient and selective extraction of gallium is realized under mild conditions, and particularly, the recovery rate is further improved through the synergistic effect of power change microwaves and multi-frequency microwaves.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical waste treatment technology, specifically relating to a microwave-enhanced selective gallium extraction method from vanadium extraction converter sludge. It utilizes the selective bulk phase heating characteristics of microwaves to extract metallic gallium from vanadium extraction converter sludge through high power, power regulation, and multi-frequency synergy. Background Technology

[0002] Vanadium-titanium magnetite sludge is a solid waste generated during the wet dust removal process after vanadium extraction in a converter. Besides containing large amounts of iron, vanadium, and chromium, it typically contains dispersed gallium. Gallium in the sludge is mainly found in ferrate (such as gallium ferrite) and aluminosilicate lattices, or it substitutes for some iron / aluminum in isomorphous forms. The gallium particles are finely embedded and tightly bound by gangue minerals, making extraction extremely difficult.

[0003] Existing technologies for recovering gallium from gallium-containing solid waste mainly include acid leaching, alkaline high-pressure leaching, or a combined high-temperature roasting-leaching process. For example, CN202310923930.3 uses oxalic acid leaching to recover gallium, CN202510816552.8 uses titanium dioxide waste acid leaching to recover gallium, and CN202511541246.4 uses high-temperature roasting to recover gallium. However, these existing technologies have significant shortcomings: although conventional acid leaching can dissolve gallium, it has poor selectivity, and a large amount of iron, silicon, and other matrix components dissolve simultaneously, resulting in high reagent consumption and difficulties in subsequent separation; traditional roasting relies on external heat sources for conduction heating, which has low heating efficiency and easily leads to sintering on the material surface, hindering the reaction; in addition, existing methods mostly focus on the recovery of the main metal vanadium, lacking targeted design for the extraction of associated gallium, and failing to effectively destroy the stable gallium-bearing phases.

[0004] Therefore, it is of great significance to develop a method that is low in energy consumption, highly selective, and capable of directionally destroying gallium-containing phase lattices. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for selectively extracting metallic gallium from vanadium converter sludge using microwave-enhanced leaching. This method is based on the selective bulk heating characteristics of microwaves. Through the synergistic effect of high-power microwaves, power-varying microwaves, and multi-frequency microwaves, intergranular fracture is induced in different mineral phases due to the mismatch in their thermal expansion coefficients, thereby achieving efficient and selective extraction of gallium under mild conditions.

[0006] To achieve the above objectives, the present invention provides a method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge, comprising the following steps:

[0007] A. Pretreatment: Drying and crushing pretreatment of vanadium extraction converter sludge;

[0008] B. Conditioning: The pretreated sludge is mixed with a microwave absorbing conditioner; in step B, the microwave absorbing conditioner is a carbonaceous material and a sodium / potassium / ammonium salt, wherein the sodium / potassium / ammonium salt is selected from at least one of halides, carbonates, bicarbonates, phosphates, dihydrogen phosphates, monohydrogen phosphates, sulfates, and citrates.

[0009] C. Microwave irradiation treatment: The conditioned material is irradiated with a single-frequency microwave; or, the conditioned material is irradiated with a power-varying microwave; or, the conditioned material is irradiated with a multi-frequency microwave in combination, so that the gallium-containing phase will produce intergranular fracture and microcracks due to the mismatch of the thermal expansion coefficients of different mineral phases.

[0010] The single-frequency microwave method is as follows: power 1.0~3.5kW / kg, frequency 1850~3000MHz;

[0011] The method of power variation microwave is as follows: adopting a gradient mode of low power preheating - high power pulse - medium power maintenance, wherein the low power preheating is 0.5~1kW / kg, the high power pulse is 2~5kW / kg, the medium power maintenance is 1~2kW / kg, the microwave irradiation treatment time for each power is not less than 1 minute, and the frequency is 1850~3000MHz.

[0012] The multi-frequency microwave coordination method is as follows: at least two different frequencies of microwaves are applied simultaneously or in a time-division manner. The frequency range of the different frequencies of microwaves is 600~3600MHz, the frequency interval between adjacent frequencies of microwaves is not less than 1000MHz, the power of each microwave is 1.0~1.5kW / kg, and the microwave irradiation treatment time of each microwave is not less than 5 minutes.

[0013] D. The material treated with microwave irradiation is placed in an alkaline leaching agent for leaching reaction to obtain gallium-containing leaching solution.

[0014] In the above-mentioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, step A of the vanadium-extraction converter sludge contains 0.015~0.050 wt% Ga.

[0015] In the above-mentioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, step A of the vanadium-extraction converter sludge contains 40-65 wt% TFe and 0.5-3.0 wt% V2O5.

[0016] In the microwave-enhanced selective gallium extraction method for vanadium converter sludge, step A involves drying at 80-105°C, crushing the material, passing it through a 100-300 mesh sieve, and collecting the material passing through the sieve.

[0017] In the aforementioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, in step B, the sodium / potassium / ammonium halide is selected from at least one of sodium chloride, potassium chloride, and ammonium chloride; the sodium / potassium / ammonium carbonate is selected from at least one of sodium carbonate, potassium carbonate, and ammonium carbonate; the sodium / potassium / ammonium bicarbonate is selected from at least one of sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate; the sodium / potassium / ammonium phosphate is selected from at least one of sodium phosphate, potassium phosphate, and ammonium phosphate; the sodium / potassium / ammonium dihydrogen phosphate is selected from at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate; the sodium / potassium / ammonium monohydrogen phosphate is selected from at least one of sodium monohydrogen phosphate, potassium monohydrogen phosphate, and ammonium monohydrogen phosphate; the sodium / potassium / ammonium sulfate is selected from at least one of sodium sulfate, potassium sulfate, and ammonium sulfate; and the sodium / potassium / ammonium citrate is selected from at least one of sodium citrate, potassium citrate, and ammonium citrate.

[0018] In the above-mentioned method for selective gallium extraction from vanadium converter sludge using microwave enhancement, in step B, the amount of microwave absorbing conditioning agent added is 3-16% of the sludge mass.

[0019] Preferably, in the above-mentioned microwave-enhanced selective gallium extraction method from vanadium converter sludge, in step B, the amount of carbonaceous material added is 1-10% of the sludge mass, and the amount of sodium / potassium / ammonium salt added is 2-6% of the sludge mass.

[0020] In the above-mentioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, step C, in the single-frequency microwave mode, involves a microwave irradiation treatment time of 5 to 90 minutes.

[0021] In the above-mentioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, in step C, the microwave irradiation treatment time for low-power preheating is 2-10 minutes, the microwave irradiation treatment time for high-power pulse is 1-5 minutes, the microwave irradiation treatment time for medium-power maintenance is 5-20 minutes, and the total treatment time is 8-35 minutes.

[0022] In the above-mentioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, step C, the multi-frequency microwave synergy method, employs two different microwave frequencies: 2000~3000MHz and 800~1000MHz.

[0023] Preferably, in the above-mentioned method for selective gallium extraction from vanadium converter sludge using microwave enhancement, in step C, the multi-frequency microwave synergy involves first irradiating the sample with microwaves at 800-1000MHz and 1.0-1.5kW / kg for 5-15 minutes, followed by simultaneously irradiating the sample with microwaves at 2000-3000MHz and 800-1000MHz, with the power at 2000-3000MHz and 800-1000MHz being 1.0-1.5kW / kg, and the total power being 2-3kW / kg, for a total synergistic microwave irradiation treatment of 5-20 minutes.

[0024] In the above-mentioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, in step C, the microwave irradiation treatment is carried out in an inert atmosphere or a weakly reducing atmosphere, and the total input energy in the microwave irradiation treatment is controlled at 0.3~5 kWh / kg sludge (total input energy = (rated power of microwave generator × treatment time) / initial sludge mass).

[0025] In the above-mentioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, in step D, the alkaline leaching agent is an aqueous solution of NaOH or Na2CO3 with a concentration of 50~300g / L.

[0026] In the above-mentioned method for selective gallium extraction from vanadium-extraction converter sludge using microwave enhancement, in step D, the liquid-to-solid ratio of the alkaline leaching agent and the microwave-irradiated material is 3-8 L: 1 kg.

[0027] In the microwave-enhanced selective gallium extraction method from vanadium converter sludge, the leaching reaction conditions in step D are: temperature 50~150℃, time 0.5~4 hours, and pressure at atmospheric pressure or slightly positive pressure.

[0028] In the microwave-enhanced selective gallium extraction method from vanadium converter sludge described above, in step D, the gallium-containing leachate obtained is electrolytically recovered to obtain metallic gallium.

[0029] The beneficial effects of this invention are:

[0030] Highly efficient dissociation: Through microwave-induced intergranular fracture, highly efficient dissociation of gallium-bearing phases is achieved, significantly increasing the reaction contact area and gallium leaching rate (up to 80%, 85%, or 90% or more), while minimizing damage to the main mineral phase.

[0031] High selectivity: Intergranular fracture mainly occurs at mineral grain boundaries rather than inside the mineral crystals. Therefore, in subsequent leaching, gangue components such as iron and silicon dissolve less, achieving highly selective separation of gallium.

[0032] Energy-efficient and high-performance: The characteristics of microwave bulk heating and selective heating avoid the overall heating and heat loss in the traditional roasting process. The power variation microwave and multi-frequency microwave synergy further improve energy utilization efficiency.

[0033] Environmentally friendly: The reaction conditions are mild (low temperature and normal pressure leaching), avoiding high concentrations of acids and alkalis and high temperature and high pressure operations, thus reducing reagent consumption and safety risks. Detailed Implementation

[0034] Specifically, a method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge includes the following steps:

[0035] A. Pretreatment: Drying and crushing pretreatment of vanadium extraction converter sludge;

[0036] B. Conditioning: The pretreated sludge is mixed with a microwave absorbing conditioner; in step B, the microwave absorbing conditioner is a carbonaceous material and a sodium / potassium / ammonium salt, wherein the sodium / potassium / ammonium salt is selected from at least one of halides, carbonates, bicarbonates, phosphates, dihydrogen phosphates, monohydrogen phosphates, sulfates, and citrates.

[0037] C. Microwave irradiation treatment: The conditioned material is irradiated with a single-frequency microwave; or, the conditioned material is irradiated with a power-varying microwave; or, the conditioned material is irradiated with a multi-frequency microwave in combination, so that the gallium-containing phase will produce intergranular fracture and microcracks due to the mismatch of the thermal expansion coefficients of different mineral phases.

[0038] The single-frequency microwave method is as follows: power 1.0~3.5kW / kg, frequency 1850~3000MHz;

[0039] The method of power variation microwave is as follows: adopting a gradient mode of low power preheating - high power pulse - medium power maintenance, wherein the low power preheating is 0.5~1kW / kg, the high power pulse is 2~5kW / kg, the medium power maintenance is 1~2kW / kg, the microwave irradiation treatment time for each power is not less than 1 minute, and the frequency is 1850~3000MHz.

[0040] The multi-frequency microwave coordination method is as follows: at least two different frequencies of microwaves are applied simultaneously or in a time-division manner. The frequency range of the different frequencies of microwaves is 600~3600MHz, the frequency interval between adjacent frequencies of microwaves is not less than 1000MHz, the power of each microwave is 1.0~1.5kW / kg, and the microwave irradiation treatment time of each microwave is not less than 5 minutes.

[0041] D. The material treated with microwave irradiation is placed in an alkaline leaching agent for leaching reaction to obtain gallium-containing leaching solution.

[0042] In this invention, the vanadium-extraction converter sludge is a solid waste generated during the wet dust removal process after vanadium-titanium magnetite is smelted in a converter. It contains trace amounts of gallium, generally 0.015~0.050wt%; in addition, it generally contains 40~65wt% TFe and 0.5~3.0wt% V2O5.

[0043] In step A of this invention, the drying temperature is 80~105℃, and after crushing, the material is passed through a 100~300 mesh sieve and the material passing through the sieve is collected.

[0044] This invention targets vanadium-extraction converter sludge, employing a specific combination and ratio of carbonaceous materials and sodium / potassium / ammonium salts, in conjunction with a microwave-based weak reduction process, to achieve efficient separation of iron, vanadium, and gallium. During the microwave heating treatment of vanadium-extraction converter sludge, the amount of carbonaceous materials (such as activated carbon and graphite) used as a reducing agent and microwave absorbing medium must be precisely controlled: insufficient dosage leads to an inadequate reducing atmosphere, preventing effective destruction of the iron-vanadium solid solution and significantly reducing the leaching rates of vanadium and gallium; excessive dosage creates a strong reducing atmosphere, causing iron to be over-reduced to metallic iron (Fe) or forming an iron-vanadium alloy, which not only increases the difficulty of subsequent magnetic separation but may also lead to localized overheating, increased energy consumption, or even equipment damage due to excessive carbon accumulation absorbing microwave energy. The main function of adding sodium / potassium / ammonium salts is to selectively separate and enrich iron, vanadium, and gallium by breaking down the iron-vanadium solid solution, converting vanadium into soluble vanadates and releasing gallium, while improving the dielectric properties of the material to enhance microwave absorption, lowering the activation energy of the reaction, and controlling the phase of the product. The amount of salt used is also crucial: if the amount is too small, the iron-vanadium solid solution will not be broken down sufficiently, the amount of vanadate generated will be insufficient, and the extraction rate of vanadium and gallium will be difficult to improve; if the amount is too large, excessive alkali metal salts will generate a large amount of low-melting-point glass phase with gangue such as silicon and aluminum, resulting in severe sintering and agglomeration of the material, hindering the diffusion of reducing gas, deteriorating the uniformity of microwave heating, and increasing the consumption of reagents and the burden of wastewater treatment in subsequent leaching processes.

[0045] In step B of this invention, the sodium / potassium / ammonium halide is selected from at least one of sodium chloride, potassium chloride, and ammonium chloride; the sodium / potassium / ammonium carbonate is selected from at least one of sodium carbonate, potassium carbonate, and ammonium carbonate; the sodium / potassium / ammonium bicarbonate is selected from at least one of sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate; the sodium / potassium / ammonium phosphate is selected from at least one of sodium phosphate, potassium phosphate, and ammonium phosphate; the sodium / potassium / ammonium dihydrogen phosphate is selected from at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate; the sodium / potassium / ammonium monohydrogen phosphate is selected from at least one of sodium monohydrogen phosphate, potassium monohydrogen phosphate, and ammonium monohydrogen phosphate; the sodium / potassium / ammonium sulfate is selected from at least one of sodium sulfate, potassium sulfate, and ammonium sulfate; and the sodium / potassium / ammonium citrate is selected from at least one of sodium citrate, potassium citrate, and ammonium citrate.

[0046] In step B of this invention, the amount of microwave absorbing conditioner added is 3-16% of the sludge mass. In step B of this invention, the amount of carbonaceous material added is 1-10% of the sludge mass, and the amount of sodium / potassium / ammonium salt added is 2-6% of the sludge mass.

[0047] In step C of this invention, the microwave irradiation treatment time is 5 to 90 minutes in the single-frequency microwave method.

[0048] In step C of this invention, the microwave irradiation treatment time for low-power preheating is 2-10 minutes, the microwave irradiation treatment time for high-power pulse is 1-5 minutes, the microwave irradiation treatment time for medium-power maintenance is 5-20 minutes, and the total treatment time is 8-35 minutes.

[0049] In step C of this invention, the multi-frequency microwave irradiation method employs two different microwave frequencies: 2000-3000MHz and 800-1000MHz. More specifically, in step C, the multi-frequency microwave irradiation method involves first irradiating the sample with 800-1000MHz microwaves at 1.0-1.5kW / kg for 5-15 minutes, followed by simultaneously activating both 2000-3000MHz and 800-1000MHz microwaves. The power for 2000-3000MHz is 1.0-1.5kW / kg, and the power for 800-1000MHz is also 1.0-1.5kW / kg, for a total power of 2-3kW / kg, for a total irradiation treatment of 5-20 minutes.

[0050] Iron in vanadium-extraction converter sludge mainly exists as Fe2O3 (hematite, weakly magnetic), while vanadium and gallium are dissolved in iron oxide lattices or exist as complex oxides. This invention, through precise control of redox reactions, artificially alters the occurrence state and phase composition of iron, vanadium, and gallium in solid waste, transforming the original "chemically bound, difficult-to-separate" symbiotic relationship into a "physically mixed, easily separable" state. Therefore, the microwave irradiation treatment of this invention needs to avoid the influence of oxygen and other contaminants. In step C of this invention, the microwave irradiation treatment is carried out under an inert atmosphere or a weakly reducing atmosphere, and the total input energy in the microwave irradiation treatment is controlled at 0.3~5 kWh / kg sludge. The inert atmosphere is a common inert gas atmosphere in the art, and the weakly reducing atmosphere is also a common weakly reducing gas atmosphere in the art, such as a mixed gas with the following volume ratios (5~15% CO, balance N2; 3~10% H2, balance N2; 5~15% CO, 2~5% CO2, balance N2), etc.

[0051] In step D of this invention, the alkaline leaching agent is an aqueous solution of NaOH or Na2CO3 with a concentration of 50~300g / L.

[0052] In step D of this invention, the liquid-to-solid ratio of the alkaline leaching agent and the microwave-treated material is 3-8 L: 1 kg.

[0053] In step D of this invention, the leaching reaction conditions are: temperature 50~150℃, time 0.5~4 hours, and pressure at atmospheric pressure or slightly positive pressure.

[0054] In this invention, after obtaining the gallium-containing leachate in step D, metallic gallium can be obtained through a conventional electrolytic recovery process. In this invention, microwave irradiation treatment can be carried out in a microwave reactor, which can be a multi-source microwave reactor equipped with multiple independently controlled magnetrons and / or multi-frequency microwave generators, and optionally includes artificial electromagnetic metasurfaces or waveguide distributors for achieving zoned heating.

[0055] The present invention will be further described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described herein.

[0056] Example 1: Single-frequency microwave constant power processing

[0057] Take sludge from a vanadium extraction converter in a steel plant (main components: TFe 45wt%, V2O5 3wt%, Ga 0.025wt%), dry it at 105℃, and grind it to pass through a 100-mesh sieve.

[0058] Conditioning: Add 5g of activated carbon and 3g of sodium chloride to 100g of sludge and mix well.

[0059] Microwave irradiation treatment: The mixture was placed in a microwave reactor and treated for 15 minutes at a constant power of 2kW and a frequency of 2450MHz under nitrogen protection. The total input energy was 5kWh / kg sludge. The treated material was noticeably looser.

[0060] Leaching: Add the microwave-treated material to a 100 g / L Na2CO3 aqueous solution at a liquid-to-solid ratio of 5:1 and a temperature of 90°C, and leach for 2 hours with stirring.

[0061] Results: The leaching rate of gallium reached 82%, while the leaching rate of iron was less than 4%.

[0062] Example 2: Microwave Processing with Power Variation

[0063] The raw materials are the same as in Example 1.

[0064] Conditioning: Same as in Example 1.

[0065] Microwave irradiation treatment: The mixture was placed in a multi-source microwave reactor and a gradient power mode was adopted: first, it was preheated at a low power of 0.8 kW / kg for 5 minutes; then, it was pulsed at a high power of 3.5 kW / kg for 3 minutes; finally, it was reduced to 1.2 kW / kg and maintained for 7 minutes, with the frequency fixed at 2450 MHz. The total input energy was 0.38 kWh / kg sludge, and nitrogen protection was applied throughout the process.

[0066] Leaching: Same as in Example 1.

[0067] Results: The gallium leaching rate reached 89%, while the iron leaching rate was less than 3.5%. Compared with the constant power mode in Example 1, the gallium leaching rate increased by 7 percentage points, indicating that high-power pulses can enhance the intergranular fracture effect.

[0068] Example 3: Multi-frequency microwave collaborative processing

[0069] The raw materials are the same as in Example 1.

[0070] Conditioning: Same as in Example 1.

[0071] Microwave irradiation treatment: The mixture was placed in a dual-frequency microwave reactor and irradiated with 2450MHz and 915MHz dual frequencies. The treatment procedure was as follows: first, irradiation was carried out at 915MHz and 1.5kW / kg for 8 minutes, followed by simultaneous irradiation of 2450MHz and 915MHz, with a total power of 2.5 kW / kg (of which 2450MHz contributed 1.5kW / kg and 915MHz contributed 1.0kW / kg) for 10 minutes. The total input energy was 0.62kWh / kg of sludge, and nitrogen protection was provided throughout the process.

[0072] Leaching: Same as in Example 1.

[0073] Results: The leaching rate of gallium reached 93%, while the leaching rate of iron was less than 3%. Compared with Examples 1 and 2, the dual-frequency synergistic treatment further improved the leaching rate, indicating that multi-frequency microwaves achieved more uniform and thorough selective heating of the material interior.

[0074] Comparative Example 1: No microwave pretreatment

[0075] Using the same raw materials as in Example 1, without adding conditioning agents or undergoing microwave irradiation treatment, leaching was carried out directly under the same conditions (100 g / L Na2CO3, 90 °C, 2 h).

[0076] Result: The gallium leaching rate was only 22%.

[0077] Comparative Example 2: Firing in a conventional muffle oven

[0078] Using the same raw materials as in Example 1, the samples were conventionally calcined in a muffle furnace at 800°C for 2 hours (without adding any conditioning agent), and then leached with Na2CO3 of the same concentration.

[0079] Results: The gallium leaching rate was 65%, but the energy consumption was more than 5 times that of Example 1, and the material showed obvious sintering, making the leaching residue difficult to filter.

[0080] Comparative Example 3: Constant Low Power Processing

[0081] The raw materials and conditioning were the same as in Example 1.

[0082] Microwave irradiation treatment: A constant low power density of 0.5 kW / kg, a frequency of 2450 MHz, and a treatment time of 30 minutes under nitrogen protection were used, with a total input energy of 0.25 kWh / kg sludge.

[0083] Leaching: Same as in Example 1.

[0084] Results: The gallium leaching rate was 58%. This indicates that long-term processing at low power density cannot effectively generate sufficient thermal stress to induce intergranular fracture; energy is mainly consumed in the overall gentle temperature rise, resulting in limited dissociation effect.

Claims

1. A method for selectively extracting gallium from vanadium-extraction converter sludge using microwave enhancement, characterized in that: Includes the following steps: A. Pretreatment: Drying and crushing pretreatment of vanadium extraction converter sludge; B. Conditioning: The pretreated sludge is mixed with a microwave absorbing conditioner; in step B, the microwave absorbing conditioner is a carbonaceous material and a sodium / potassium / ammonium salt, wherein the sodium / potassium / ammonium salt is selected from at least one of halides, carbonates, bicarbonates, phosphates, dihydrogen phosphates, monohydrogen phosphates, sulfates, and citrates. C. Microwave irradiation treatment: The conditioned material is irradiated with a single-frequency microwave; or, the conditioned material is irradiated with a power-varying microwave; or, the conditioned material is irradiated with a multi-frequency microwave in combination, so that the gallium-containing phase will produce intergranular fracture and microcracks due to the mismatch of the thermal expansion coefficients of different mineral phases. The single-frequency microwave method is as follows: power 1.0~3.5kW / kg, frequency 1850~3000MHz; The method of power variation microwave is as follows: adopting a gradient mode of low power preheating - high power pulse - medium power maintenance, wherein the low power preheating is 0.5~1kW / kg, the high power pulse is 2~5kW / kg, the medium power maintenance is 1~2kW / kg, the microwave irradiation treatment time for each power is not less than 1 minute, and the frequency is 1850~3000MHz. The multi-frequency microwave coordination method is as follows: at least two different frequencies of microwaves are applied simultaneously or in a time-division manner. The frequency range of the different frequencies of microwaves is 600~3600MHz, the frequency interval between adjacent frequencies of microwaves is not less than 1000MHz, the power of each microwave is 1.0~1.5kW / kg, and the microwave irradiation treatment time of each microwave is not less than 5 minutes. D. The material treated with microwave irradiation is placed in an alkaline leaching agent for leaching reaction to obtain gallium-containing leaching solution.

2. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to claim 1, characterized in that: In step A, the vanadium extraction converter sludge contains 0.015~0.050wt% Ga; the vanadium extraction converter sludge contains 40~65wt% TFe and 0.5~3.0wt% V2O5.

3. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to claim 1, characterized in that: In step A, the drying temperature is 80~105℃, and after crushing, the material is passed through a 100~300 mesh sieve and the material passing through the sieve is collected.

4. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to claim 1, characterized in that: In step B, the sodium / potassium / ammonium halide is selected from at least one of sodium chloride, potassium chloride, and ammonium chloride; the sodium / potassium / ammonium carbonate is selected from at least one of sodium carbonate, potassium carbonate, and ammonium carbonate; the sodium / potassium / ammonium bicarbonate is selected from at least one of sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate; the sodium / potassium / ammonium phosphate is selected from at least one of sodium phosphate, potassium phosphate, and ammonium phosphate; the sodium / potassium / ammonium dihydrogen phosphate is selected from at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate; the sodium / potassium / ammonium monohydrogen phosphate is selected from at least one of sodium monohydrogen phosphate, potassium monohydrogen phosphate, and ammonium monohydrogen phosphate; the sodium / potassium / ammonium sulfate is selected from at least one of sodium sulfate, potassium sulfate, and ammonium sulfate; and the sodium / potassium / ammonium citrate is selected from at least one of sodium citrate, potassium citrate, and ammonium citrate.

5. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to claim 1, characterized in that: In step B, the amount of microwave absorbing conditioner added is 3-16% of the sludge mass; preferably, the amount of carbonaceous material added is 1-10% of the sludge mass, and the amount of sodium / potassium / ammonium salt added is 2-6% of the sludge mass.

6. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to claim 1, characterized in that: In step C, the microwave irradiation treatment time is 5 to 90 minutes in the single-frequency microwave method.

7. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to claim 1, characterized in that: In step C, the microwave irradiation treatment with varying power is carried out for 2 to 10 minutes for low-power preheating, 1 to 5 minutes for high-power pulsed microwave irradiation, and 5 to 20 minutes for medium-power sustained microwave irradiation, with a total treatment time of 8 to 35 minutes.

8. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to claim 1, characterized in that: In step C, the multi-frequency microwave synergy method uses two different microwave frequencies: 2000~3000MHz and 800~1000MHz. Preferably, the patient is first irradiated with 800~1000MHz microwave at 1.0~1.5kW / kg for 5~15 minutes, and then simultaneously irradiated with 2000~3000MHz and 800~1000MHz microwaves at 1.0~1.5kW / kg and 800~1000MHz microwaves at 1.0~1.5kW / kg, for a total power of 2~3kW / kg, for a synergistic microwave irradiation treatment of 5~20 minutes.

9. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to claim 1, characterized in that: In step C, the microwave irradiation treatment is carried out in an inert atmosphere or a weakly reducing atmosphere, and the total input energy in the microwave irradiation treatment is controlled at 0.3~5 kWh / kg sludge.

10. The method for microwave-enhanced selective gallium extraction from vanadium-extraction converter sludge according to any one of claims 1 to 9, characterized in that: In step D, at least one of the following must be satisfied: The alkaline leaching agent is an aqueous solution of NaOH or Na2CO3 with a concentration of 50~300g / L; The liquid-to-solid ratio of the alkaline leaching agent and the microwave-treated material is 3-8 L: 1 kg. The leaching reaction conditions are: temperature 50~150℃, time 0.5~4 hours, and pressure at atmospheric pressure or slightly positive pressure.