Method for synergistically extracting vanadium oxychloride, gallium trichloride and iron-titanium alloy from vanadium slag

Abstract

The invention discloses a method for synergistically extracting vanadium oxytrichloride, gallium trichloride and iron-titanium alloy from vanadium slag, and belongs to the field of recycling of complex multi-metal resources. The method comprises the following steps: uniformly mixing the gallium-containing vanadium slag, carbon and chlorinated waste salt according to a certain proportion, and carrying out vacuum melting treatment to obtain a Fe-Ti alloy; then chlorine is introduced for chlorination treatment, and a gaseous product is obtained; the gaseous product is adsorbed by a molecular sieve with a function of selectively adsorbing VOCl3 to obtain VOCl3, and then GaCl3 is obtained through a cold trap. According to the method, efficient collaborative conversion and recovery of multi-metal resources of vanadium, gallium, iron and titanium in the vanadium slag are achieved, and the problems that multi-metal collaborative extraction in existing vanadium slag is difficult, and the separation efficiency is low can be effectively solved.

Description

Technical Field

[0001] The present invention belongs to the field of recycling and utilization of complex multi-metal resources, and relates to a method for the synergistic extraction of vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag, and specifically to a synergistic chlorination separation and ferrotitanium alloying technology of vanadium and gallium in gallium-containing vanadium slag. Background Art

[0002] Vanadium slag is a major byproduct of the vanadium-titanium magnetite smelting process and is rich in vanadium, iron, titanium, and other metal resources. The traditional vanadium extraction process from vanadium slag involves sodium roasting followed by water leaching or calcium roasting followed by acid leaching. This process produces ammonia nitrogen wastewater and low resource utilization. Chlorinated waste salts are the product of high-temperature carbonization and low-temperature chlorination of titanium slag, primarily containing large amounts of FeCl₃, AlCl₃, and NaCl. Currently, the utilization rate of chlorinated waste salts is extremely low, with the primary disposal method being landfill, which significantly pollutes the environment and wastes resources.

[0003] In recent years, the chlorination method has become a research hotspot due to its clean and efficient nature, but existing technologies have significant limitations. First, existing technologies often focus on the extraction of a single metal. For example, CN119143169A discloses a method for extracting high-purity gallium trichloride from gallium-containing waste. However, this method only addresses the preparation of gallium trichloride and does not address the recovery of other metal resources from gallium-containing waste. Second, existing methods attempting to recover multiple metals suffer from difficulties in product separation and lack of high-value utilization. For example, CN119614856A discloses a vanadium slag chlorination technology. While this method considers the recovery of multiple metal resources, its products are a liquid mixture of vanadium tetrachloride and titanium tetrachloride and a solid mixture of manganese chloride and ferric chloride. Further utilization of these products requires additional separation and processing. Third, traditional chlorination methods have problems such as small differences in the chlorination kinetics of vanadium and gallium, making separation difficult; the titanium and iron in the smelting slag are not effectively utilized, resulting in resource waste; and sodium salts are only used as flux, failing to tap their catalytic potential.

[0004] Gallium, a strategic rare metal, is primarily found in bauxite. 90% of gallium is recovered from Bayer liquor as a byproduct of aluminum extraction, achieving multi-metal synergistic recovery. However, gallium in vanadium slag is found in vanadium-ferro-spinel and fayalite. Existing gallium extraction processes from vanadium slag require complex enrichment and purification steps, resulting in lengthy processes and high costs. Simultaneously recovering vanadium and gallium from vanadium slag could significantly increase the value of this resource.

[0005] Therefore, there is an urgent need to develop a green and efficient process that can simultaneously extract vanadium, gallium and other metal resources from vanadium slag. Summary of the Invention

[0006] The technical problem to be solved by the present invention is the difficulty in synergistic extraction of multiple metals in existing vanadium slag and the low separation efficiency.

[0007] To achieve the above application objectives, the technical solutions adopted in this application are as follows: The present invention provides a method for synergistically extracting vanadium trichloride, gallium trichloride and iron-titanium alloy from vanadium slag, specifically comprising: uniformly mixing gallium-vanadium slag, carbon and chlorinated waste salt in a mass ratio of 50-70:15-25:15-25, and performing vacuum smelting treatment at 1250-1350°C to obtain Fe-Ti alloy; then introducing chlorine gas and performing chlorination treatment at 400-500°C to obtain gaseous products; adsorbing the gaseous products on a molecular sieve with a selective VOCl3 adsorption function to obtain VOCl3, and then passing through a cold trap to obtain GaCl3; The gallium-vanadium-containing slag contains Fe2O3 and TiO2, and the mass ratio of Fe2O3 / TiO2 is ≥2.5; The chlorinated waste salt contains NaCl, with a Na content of 9-12 wt.% and a Cl content of 49-52 wt.%.

[0008] In the above method, the gallium-vanadium-containing slag, carbon and chlorinated waste salt are mixed and then pressed into tablets, and the obtained tablets are subjected to subsequent treatment.

[0009] In the above method, during the vacuum melting process, the vacuum degree is dynamically adjusted during the melting process to reduce the vacuum degree from 2000 Pa to 500 Pa, and the vacuum degree adjustment rate is 50~200 Pa / min.

[0010] In the above method, during the vacuum melting treatment, the melting and holding time is 40 to 120 minutes.

[0011] In the above method, during the chlorination treatment, the chlorine partial pressure is 0.3~0.8atm, and the chlorination reaction time is 1~2h.

[0012] In the above method, the particle size of the gallium-vanadium-containing slag is less than 75 μm, and the Ga content in the gallium-vanadium-containing slag is 100-800 g / t.

[0013] In the above method, the chlorinated waste salt contains FeCl3, AlCl3 and Ti, with the Fe content being 8~11wt.%, the Al content being 7~10wt.%, and the Ti content being 4~7wt.%.

[0014] In the above method, the molecular sieve having the function of selectively adsorbing VOCl3 is a 13X molecular sieve modified with gallium nitrate.

[0015] Furthermore, the adsorption capacity of the molecular sieve for VOCl3 is ≥200 mg / g, and the desorption temperature is 180~220℃.

[0016] In the above method, the temperature of the cold trap is -50~50℃.

[0017] The beneficial effects of the present invention are as follows: It provides a synergistic method for the simultaneous extraction and separation of high-purity vanadium trichloride and gallium trichloride under vacuum and high-temperature conditions using carbon-doped vanadium slag and chlorinated waste salt, and the conversion of iron and titanium components into Fe-Ti alloy byproducts. The key to the invention's innovation lies in fully utilizing the sodium chloride in the chlorinated waste salt, enabling it to play a central role in both the smelting and chlorination stages. During the smelting stage, NaCl not only reacts with Fe2O3 in the raw material to form NaFeO2, effectively reducing melt viscosity, but also provides an excellent dispersion environment for the vanadium and gallium nanometallic crystallites (50-100 nm in size) generated by carbothermal reduction, ensuring their uniform distribution. Simultaneously, the iron and titanium components are enriched to form the Fe-Ti alloy.

[0018] In the subsequent chlorination stage, NaCl in the chlorinated waste salt acts as a highly efficient catalyst by reacting with chlorine to form [Cl - ...Na + ...Cl2] activates the intermediate, significantly reducing the activation energy for VOCl3 formation and increasing the selectivity of GaCl3, thereby promoting the targeted production of VOCl3 and GaCl3. The ferric chloride and aluminum chloride associated with the waste salt act as fluxes, ensuring a smooth chlorination reaction. Finally, the gaseous products are fractionally condensed through a molecular sieve adsorption column and a cryogenic cold trap, yielding VOCl3 with a purity exceeding 98% and GaCl3 with a purity of 4N-7N, respectively. The titanium content of the Fe-Ti alloy byproduct can reach 15-30wt%. Compared to existing technologies, this invention achieves highly efficient synergistic conversion and recovery of vanadium, gallium, iron, and titanium multimetallic resources from vanadium slag. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clear, the application is further described in detail below in conjunction with the embodiments. Unless otherwise defined, all scientific and technical terms used herein have the same meanings as understood by ordinary technicians in this field.

[0020] In order to solve the problems of difficulty in the synergistic extraction of multiple metals and low separation efficiency in the prior art, the present invention provides a method for the synergistic extraction of vanadium trichloride, gallium trichloride and ferrotitanium alloy from vanadium slag, specifically: gallium-containing vanadium slag, carbon and chlorinated waste salt are mixed in a mass ratio of 10~14:3~5:3~5, and vacuum smelting treatment is carried out at 1250~1350℃ to obtain Fe-Ti alloy; then chlorine gas is introduced and chlorination treatment is carried out at 400~500℃ to obtain gaseous products; the gaseous products are adsorbed by a molecular sieve with a selective VOCl3 adsorption function to obtain VOCl3, and then passed through a cold trap to obtain GaCl3.

[0021] In the present invention, the gallium-vanadium slag has a particle size of less than 75 μm and comprises Fe2O3, TiO2, and Ga; wherein the mass ratio of Fe2O3 / TiO2 is ≥2.5, and the Ga content is 100-800 g / t. The carbon is carbon powder. The chlorinated waste salt comprises NaCl, FeCl3, AlCl3, and Ti; wherein the Na content is 9-12 wt.%, the Cl content is 49-52 wt.%, the Fe content is 8-11 wt.%, the Al content is 7-10 wt.%, and the Ti content is 4-7 wt.%.

[0022] In one embodiment of the present invention, the mass ratio of the gallium-vanadium-containing slag, carbon, and chlorinated waste salt is (50-70):(15-25):(15-25). This mass ratio ensures the reduction reaction. During the vacuum smelting stage, carbon can increase the metal reduction rate and prevent residual oxides from hindering chlorination. The NaCl in the chlorinated waste salt serves as a chlorination catalyst and crystal form regulator during the smelting and chlorination stages, while FeCl3 and AlCl3 act as fluxes to promote the chlorination reaction. As non-limiting examples, the mass ratio of the gallium-vanadium-containing slag, carbon, and chlorinated waste salt can be 50:15:15, 50:20:20, 50:25:25, 60:15:15, 60:20:20, 60:25:25, 70:15:15, 70:20:20, 70:25:25, or any ratio therebetween.

[0023] In one embodiment of the present invention, the smelting temperature of the vacuum smelting process is 1250-1350°C, and the smelting holding time is 40-120 minutes. The purpose of setting the smelting temperature is to reduce the vanadium-containing compounds and gallium-containing compounds in the vanadium slag to metal elements by carbon. Within this temperature range, oxide residues can be avoided, and the iron and titanium components are enriched in the smelting slag to form an Fe-Ti alloy. As a non-limiting example, the smelting temperature of the vacuum smelting process can be 1250°C, 1260°C, 1270°C, 1280°C, 1290°C, 1300°C, 1310°C, 1320°C, 1330°C, 1340°C, 1350°C, or within a range of any two of the above values; the smelting holding time can be 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, or within a range of any two of the above values.

[0024] In one embodiment of the present invention, the chlorination temperature of the chlorination treatment is 400-500°C. The purpose of setting the chlorination temperature is to control the generation path of vanadium oxychloride and gallium trichloride, ensuring that vanadium oxychloride and gallium trichloride products are smoothly generated during chlorination. As a non-limiting example, the chlorination temperature of the chlorination treatment can be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, or a range consisting of any two of the above values.

[0025] In one embodiment of the present invention, the gallium-vanadium slag, carbon, and chlorinated waste salt can be mixed and then pressed into tablets, which can then be processed. This increases contact between particles and prevents reactants (such as carbon powder) from being dispersed by airflow.

[0026] In one embodiment of the present invention, the vacuum degree can be dynamically adjusted during the smelting process to reduce the vacuum degree from 2000 Pa to 500 Pa. Dynamically adjusting the vacuum degree during the smelting process promotes carbon reduction to reduce vanadium and gallium compounds to nano-scale metal crystallites; at the same time, it prevents splashing, promotes reaction balance, and improves reduction efficiency. Preferably, the vacuum degree adjustment rate is 50~200 Pa / min. As a non-limiting example, the vacuum degree adjustment rate can be 50 Pa / min, 100 Pa / min, 150 Pa / min, 200 Pa / min, or within a range consisting of any two of the above values.

[0027] In one embodiment of the present invention, the partial pressure of chlorine is controlled to be 0.3 to 0.8 atm during chlorination treatment, and the chlorination reaction time is 1 to 2 hours. Chlorine is introduced and the chlorine partial pressure is controlled to provide a sufficient chlorine source for the chlorination reaction and to increase the rate of the chlorination reaction. As a non-limiting example, the chlorine partial pressure can be 0.3 atm, 0.4 atm, 0.5 atm, 0.6 atm, 0.7 atm, 0.8 atm, or within the range of any two of the above values.

[0028] In one embodiment of the present invention, to improve the adsorption efficiency of VOCl3, the molecular sieve capable of selectively adsorbing VOCl3 may be a 13X molecular sieve modified with gallium nitrate. Preferably, the molecular sieve has an adsorption capacity for VOCl3 of ≥200 mg / g and a desorption temperature of 180-220°C.

[0029] In one embodiment of the present invention, the temperature of the cold trap can be -50~50°C. In order to improve the condensation recovery efficiency of GaCl3, multiple cold traps can be set in actual production, for example, by setting at least one cold trap to capture impurities, and then using liquid nitrogen to assist in lowering the temperature of the cold trap to condense and recover GaCl3. As a non-limiting example, at least one cold trap is set to capture impurities, and its temperature can be 10°C, 20°C, 30°C, 40°C, 50°C or within the range of any two of the above values; a cold trap is set to condense and recover GaCl3, and its temperature can be -50°C, -40°C, -30°C, -20°C, -10°C, 0°C or within the range of any two of the above values.

[0030] Specific examples will be listed below to explain the scheme of the present invention. Those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specifications. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0031] 1. Raw material preparation In Example 1, the particle size of the vanadium slag raw material is less than 75 μm, the gallium content is 450 g / t, and the Fe2O3 / TiO2 mass ratio is 3.0.

[0032] In Example 2, the particle size of the vanadium slag raw material is less than 75 μm, the gallium content is 100 g / t, and the Fe2O3 / TiO2 mass ratio is 2.5.

[0033] In Example 3, the particle size of the vanadium slag raw material is less than 75 μm, the gallium content is 350 g / t, and the Fe2O3 / TiO2 mass ratio is 4.0.

[0034] In Example 4, the particle size of the vanadium slag raw material is less than 75 μm, the gallium content is 200 g / t, and the Fe2O3 / TiO2 mass ratio is 3.5.

[0035] The main chemical components of the chlorinated waste salts described in Examples 1 to 4 are: Fe content of 9.65 wt.%, Na content of 10.11 wt.%, Al content of 8.2 wt.%, Ti content of 5.01 wt.%, and Cl content of 50.32 wt.%.

[0036] 2. Synergistic extraction of vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag Example 1: Vanadium slag: carbon powder: chlorinated waste salt (mass ratio = 60:20:20) was pressed into tablets (20 mm diameter, 5 mm thickness). The tablets were placed in a vacuum tube furnace equipped with a dynamic vacuum control system. The vacuum was initially set to 2000 Pa and gradually reduced to 500 Pa (at a rate of 100 Pa / min). The temperature was set to 1300°C and maintained for 60 minutes to produce an Fe-Ti alloy (Ti content 25 wt%). The temperature was then lowered to 450°C and a chlorine partial pressure of 0.8 atm. Chlorine was introduced for 2 hours to produce VOCl3 and GaCl3 gases. The gaseous products were sequentially passed through 13X molecular sieves modified with ammonium nitrate. The sieves adsorbed VOCl3 with an adsorption capacity of 220 mg / g. The desorption temperature of the molecular sieves was 200°C. The gas then passed through two cold traps: the first set at 30°C to capture impurities, and the second set at 0°C to condense and recover GaCl3.

[0037] After analysis and testing, the final product purities of VOCl3 and GaCl3 were 99.2% and 99.99% respectively.

[0038] Example 2: Vanadium slag: carbon powder: chlorinated waste salt (mass ratio = 70:15:15) was pressed into tablets (15 mm diameter, 8 mm thickness). The tablets were placed in a vacuum tube furnace equipped with a dynamic vacuum control system. The vacuum was initially set to 2000 Pa and gradually reduced to 500 Pa (at a rate of 200 Pa / min). The temperature was set to 1250°C and maintained for 40 minutes to produce an Fe-Ti alloy (Ti content 18 wt%). The temperature was then lowered to 500°C and a chlorine partial pressure of 0.5 atm. Chlorine was introduced for 1 hour to produce VOCl3 and GaCl3 gases. The gaseous products were sequentially passed through 13X molecular sieves modified with ammonium nitrate. The sieves adsorbed VOCl3 with an adsorption capacity of 220 mg / g. The desorption temperature of the molecular sieves was 200°C. The gas then passed through two cold traps: the first set at 50°C to capture impurities, and the second set at 0°C to condense and recover GaCl3.

[0039] After analysis and testing, the final product purities of VOCl3 and GaCl3 were 98.8% and 99.99% respectively.

[0040] Example 3: Vanadium slag: carbon powder: chlorinated waste salt (mass ratio = 50:25:25) was pressed into tablets (25 mm diameter, 6 mm thickness). The tablets were placed in a vacuum tube furnace equipped with a dynamic vacuum control system. The initial vacuum was set to 2000 Pa, which was gradually reduced to 500 Pa (at a rate of 50 Pa / min). The temperature was set to 1350°C and maintained for 120 minutes to produce an Fe-Ti alloy (Ti content 30 wt%). The temperature was then lowered to 400°C, and chlorine gas was introduced to a partial pressure of 0.3 atm. Chlorine was then introduced for 1.5 hours to produce VOCl3 and GaCl3 gases. The gaseous products were sequentially passed through 13X molecular sieves modified with ammonium nitrate. The sieves adsorbed VOCl3 with an adsorption capacity of 210 mg / g. The desorption temperature of the molecular sieves was 200°C. The gas then passed through two cold traps: the first set at 50°C to capture impurities, and the second set at -50°C with liquid nitrogen to condense and recover GaCl3.

[0041] After analysis and testing, the final product purities of VOCl3 and GaCl3 were 98.9% and 99.9999% respectively.

[0042] Example 4: Vanadium slag: carbon powder: chlorinated waste salt (mass ratio = 55:22:23) was pressed into tablets (18 mm diameter, 7 mm thickness). The tablets were placed in a vacuum tube furnace equipped with a dynamic vacuum control system. The vacuum was initially set to 2000 Pa, which was gradually reduced to 500 Pa (at a rate of 150 Pa / min). The temperature was set to 1280°C and maintained for 50 minutes to react and produce an Fe-Ti alloy (Ti content 22 wt%). The temperature was then lowered to 480°C, and chlorine gas was introduced at a partial pressure of 0.6 atm. Chlorine was then introduced for 1.2 hours to produce VOCl3 and GaCl3 gases. The gaseous products are sequentially passed through 13X molecular sieve modified with ammonium nitrate. The molecular sieve adsorbs VOCl3 with an adsorption capacity of 205 mg / g and a desorption temperature of 200°C. The gas then passes through three cold traps. The temperature of the first cold trap is set at 50°C, the temperature of the second cold trap is set at 20°C, and the third cold trap is set at -50°C with the assistance of liquid nitrogen to condense and recover GaCl3.

[0043] After analysis and testing, the final product purities of VOCl3 and GaCl3 were 99.1% and 99.99999% respectively.

Claims

1. A method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag, characterized by: Gallium-vanadium slag, carbon and chlorinated waste salt are mixed in a mass ratio of 50-70:15-25:15-25, and then vacuum smelted at 1250-1350°C to obtain Fe-Ti alloy; Then, chlorine gas is introduced and chlorination treatment is carried out at 400-500°C to obtain a gaseous product; the gaseous product is adsorbed by a molecular sieve with a selective adsorption function of VOCl3 to obtain VOCl3, and then passed through a cold trap to obtain GaCl3; The gallium-vanadium-containing slag contains Fe2O3 and TiO2, and the mass ratio of Fe2O3 / TiO2 is ≥2.5; The chlorinated waste salt contains NaCl, with a Na content of 9-12 wt.% and a Cl content of 49-52 wt.%.

2. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 1, characterized in that: The gallium-vanadium-containing slag, carbon and chlorinated waste salt are mixed and then pressed into tablets, and the obtained tablets are subjected to subsequent treatment.

3. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 1, characterized in that: During the vacuum smelting process, the vacuum degree is dynamically adjusted during the smelting process to reduce the vacuum degree from 2000 Pa to 500 Pa, and the adjustment rate of the vacuum degree is 50-200 Pa / min.

4. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 1, characterized in that: During the vacuum melting process, the melting and holding time is 40 to 120 minutes.

5. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 1, characterized in that: During the chlorination treatment, the chlorine partial pressure is 0.3-0.8 atm, and the chlorination reaction time is 1-2 hours.

6. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 1, characterized in that: The particle size of the gallium-vanadium-containing slag is less than 75 μm, and the Ga content in the gallium-vanadium-containing slag is 100-800 g / t.

7. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 1, characterized in that: The chlorinated waste salt contains FeCl3, AlCl3 and Ti, with the Fe content being 8-11 wt.%, the Al content being 7-10 wt.%, and the Ti content being 4-7 wt.%.

8. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 1, characterized in that: The molecular sieve having the function of selectively adsorbing VOCl3 is a 13X molecular sieve modified by gallium nitrate.

9. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 8, characterized in that: The adsorption capacity of the molecular sieve for VOCl3 is ≥200 mg / g, and the desorption temperature is 180-220°C.

10. The method for synergistically extracting vanadium oxychloride, gallium trichloride and ferrotitanium alloy from vanadium slag according to claim 1, characterized in that: The temperature of the cold trap is -50~50℃.