A method for roasting vanadium slag in-situ supported by aluminosilicate framework to extract vanadium

Abstract

The application discloses a method for roasting vanadium slag in-situ supported by aluminosilicate framework to extract vanadium, and belongs to the technical field of comprehensive utilization of smelting waste residue. The method comprises the steps of ingredient mixing, oxidizing roasting and leaching. By mixing vanadium slag with high-aluminum additives and roasting, cordierite, mullite and other high-melting-point aluminosilicate frameworks are generated in-situ, the low-melting-point silicate glass liquid phase is reduced, and the wrapping of the low-melting-point silicate glass liquid phase on the vanadium-containing product and the high-temperature bonding of the material are reduced. Meanwhile, the high-aluminum additives do not convert vanadium oxides into vanadates as the main mechanism for extracting vanadium, which is beneficial to maintaining the acid leaching activity of high-valence vanadium-containing components. In addition, the aluminosilicate framework generated in-situ has high stability under acid leaching conditions, and compared with calcification roasting, the method can reduce the calcium sulfate by-product and the corresponding acid consumption caused by the additional introduction of a calcification agent. The method is beneficial to improving the vanadium leaching performance, and can realize the resource utilization of vanadium slag and industrial solid waste containing aluminum.

Description

Technical Field

[0001] This invention relates to the field of comprehensive utilization technology of smelting waste residue, specifically to a method for vanadium extraction from vanadium slag by in-situ support of aluminosilicate framework through roasting. Background Technology

[0002] Vanadium slag is a type of vanadium-containing smelting slag produced during the smelting of vanadium-titanium magnetite, and it is also an important secondary resource for industrial vanadium extraction. Vanadium in vanadium slag mainly exists as stable mineral phases such as low-priced vanadium-iron spinel. The leaching rate of vanadium is low when directly using wet leaching. Therefore, it is usually necessary to first change the occurrence state of vanadium through oxidative roasting before subsequent leaching extraction.

[0003] Currently, vanadium extraction from vanadium slag typically employs either sodium roasting-water leaching or calcification roasting-acid leaching processes. Sodium roasting promotes the conversion of low-valent vanadium to soluble high-valent vanadium, but it easily generates saline wastewater during subsequent processing. Furthermore, chromium in the vanadium slag may oxidize during roasting and enter the leaching system, increasing the difficulty of subsequent separation and treatment. Calcification roasting usually uses lime or limestone as additives to convert vanadium into calcium vanadate before acid leaching. However, calcium sulfate is formed during acid leaching, potentially creating a coating layer on the surface of the reacting particles, thus affecting the leaching process and increasing the amount of calcium-containing leaching residue. In addition, vanadium slag contains silicon-containing components such as fir olivine, calcium-iron olivine, and silica, which easily form low-melting-point silicate phases or glassy liquid phases during high-temperature roasting. These liquid phases can cause particle adhesion and increase the tendency for adhesion and ring formation in the roasting equipment; they can also coat the oxidized vanadium-containing products, hindering sufficient contact between the leaching agent and the vanadium-containing components.

[0004] How to provide a method for in-situ support of vanadium slag roasting and vanadium extraction using an aluminosilicate framework to solve these problems has become an urgent issue for those skilled in the art. Summary of the Invention

[0005] Based on the above analysis, the purpose of this invention is to provide a method for vanadium extraction from vanadium slag by in-situ support of an aluminosilicate framework during roasting. By introducing a high-alumina additive during the roasting process of vanadium slag, the high-alumina additive reacts with the silicon-containing components in the vanadium slag in a solid-phase reaction to form a high-melting-point aluminosilicate phase, reducing the formation of a low-melting-point silicate glassy liquid phase, and promoting the oxidation and conversion of low-valent vanadium in the vanadium slag, thereby improving the subsequent acid leaching performance of the roasted clinker.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a method for vanadium extraction from vanadium slag by in-situ support of an aluminosilicate framework through roasting, comprising the following steps:

[0008] S1. Batching and mixing: Add 10wt.% to 60wt.% of high-alumina additives to vanadium slag, and dry grind to obtain a mixture;

[0009] The addition of high-alumina additives provides aluminum-containing components to the roasting system to participate in the formation of aluminosilicate phases. As the amount of high-alumina additives increases, the amount of aluminum-containing components available for solid-phase reactions increases accordingly, which is beneficial for the transformation of SiO2 and silicon-containing components such as fir olivine and calcium fir olivine in vanadium slag into high-melting-point aluminosilicate phases such as cordierite and mullite. When the amount added is too low, there are insufficient aluminum-containing components to participate in phase reconstruction, limiting the transformation effect on low-melting-point silicate phases. When the amount added is too high, the proportion of high-alumina components in the roasting system further increases, diluting the vanadium-containing components per unit mass of roasted material. Therefore, the comprehensive determination of the addition amount of high-alumina additives is 10 wt.%–60 wt.%.

[0010] S2. Oxidative roasting: The mixture is heated to 800-1050°C and roasted in an oxygen-containing atmosphere, so that the high-alumina additive reacts with the silicon-containing components in the vanadium slag in a solid-phase reaction, forming an aluminosilicate framework in situ, and oxidizing the low-valent vanadium in the vanadium slag to obtain roasted clinker.

[0011] S3. Leaching: The roasted clinker is wet-milled, and a dilute sulfuric acid solution is added for stirring and leaching. After leaching, solid-liquid separation is performed to obtain vanadium-containing leachate and leaching residue.

[0012] Preferably, the high-alumina additive is at least one selected from cenospheres, waste corundum, alumina, and aluminum hydroxide.

[0013] Preferably, in step S1, the vanadium content in the vanadium slag is ≥10 wt.% based on V2O5; the Al2O3 content in the cenospheres is 30 wt.% to 40 wt.%; the Al2O3 content in the waste corundum is ≥95 wt.%; the Al2O3 content in the alumina is ≥98 wt.%; and the Al(OH)3 content in the aluminum hydroxide is ≥98 wt.%.

[0014] Preferably, in step S2, the aluminosilicate framework includes at least one of cordierite and mullite phases.

[0015] A further improvement is that, in step S2, the calcination temperature is 850–1000°C. As the calcination temperature decreases below 850°C and further decreases, the oxidation rate slows down, the activation degree of high-alumina additives is low, the amount of cordierite, mullite, and other phases generated is low, the amount of aluminosilicate phases formed is reduced, and the inhibition of the formation of low-melting-point silicate glass liquid phase and its encapsulation effect is reduced. At the same time, the oxidation of vanadium-iron spinel is incomplete, and the amount of vanadium oxide generated is low. When the temperature is higher than 1050°C, the material is prone to liquid phase sintering and forming dense blocks, which not only hinders oxygen diffusion but also makes it difficult for the leaching agent to penetrate into the particle interior, resulting in a decrease in vanadium leaching rate and an increase in production energy consumption.

[0016] Preferably, the dry-milled mixture in step S1 and the calcined clinker after wet milling in step S3 both satisfy the requirement that the mass percentage of particles with a particle size of less than 0.074 mm is ≥85%.

[0017] A further improvement is that the dry-milled mixture in step S1 and the wet-milled calcined clinker in step S3 both satisfy the requirement that the mass percentage of particles with a particle size of less than 0.074 mm is ≥90%.

[0018] Meeting the dry grinding particle size standard during the batching stage ensures uniform mixing of vanadium slag and high-alumina additives, increases the solid-phase reaction contact interface, and promotes in-situ formation of the aluminosilicate framework at high temperatures; meeting the wet grinding particle size standard before leaching increases the contact area between the clinker and the leaching agent, ensuring efficient leaching reaction.

[0019] Preferably, in step S2, the calcination time is 0.5 to 3 hours, and the oxygen volume fraction in the oxygen-containing atmosphere is ≥10%.

[0020] The calcination time is used to ensure that the oxidation of vanadium iron spinel and the solid-phase reaction between the high-alumina additive and the silicon-containing components are fully carried out. If the calcination time is too short, the oxidation conversion of vanadium and the degree of formation of aluminosilicate phase are limited. As the calcination time is extended, the above reactions gradually become more complete. When the calcination time is further extended, the promoting effect of extending the time on phase transformation tends to decrease and the calcination energy consumption increases. Therefore, the calcination time is set to 0.5 to 3 hours.

[0021] Preferably, in step S3, the H2SO4 content in the dilute sulfuric acid solution is 5wt.% to 30wt.%, the leaching temperature is 30 to 90°C, the leaching time is 0.5 to 4 hours, and the leaching liquid-to-solid ratio is 2 to 6 L / kg.

[0022] Increasing the leaching temperature helps to accelerate the reaction between the leaching agent and the acid-soluble vanadium-containing components. However, excessively high temperatures can increase the energy consumption of the leaching process and may promote the entry of some impurity components into the leaching solution. Therefore, the leaching temperature is set to 30–90°C.

[0023] The leaching time is used to ensure that the leaching agent is in full contact with the calcined clinker after wet milling. If the leaching time is too short, the vanadium-containing components inside the particles cannot be fully dissolved. After further extending the leaching time, the degree of continued dissolution of vanadium gradually decreases. Therefore, the leaching time is set to 0.5 to 4 hours.

[0024] The leaching liquid-to-solid ratio affects the contact between the leaching agent and the roasted clinker, as well as the effective acid content in the system. When the liquid-to-solid ratio is low, it is not conducive to the full dispersion of the clinker and the full contact between the leaching agent and the particles. When the liquid-to-solid ratio is too high, it increases the amount of liquid to be processed in the subsequent process. Therefore, the leaching liquid-to-solid ratio is set to 2-6 L / kg.

[0025] A further improvement is that, in step S3, the H2SO4 content in the dilute sulfuric acid solution is 15wt.% to 20wt.%, the leaching temperature is 40 to 80℃, the leaching time is 1.5 to 2.5 h, and the leaching liquid-to-solid ratio is 3 to 5 L / kg.

[0026] When the sulfuric acid concentration is below 5 wt.%, the effective acidity of the leaching system is low, the dissolution of vanadium-containing components is limited, the dissolution of vanadium oxides and vanadates is incomplete, and the vanadium recovery rate is low. When the sulfuric acid concentration is above 30 wt.%, the acid consumption cost will increase significantly, and the dissolution of impurities such as iron and titanium will be aggravated, increasing the burden on subsequent vanadium solution purification processes.

[0027] Reaction mechanism and process

[0028] Vanadium in vanadium slag mainly exists in the +3 valence state in the vanadium-iron spinel (FeV2O4) lattice. Under high-temperature oxidizing atmosphere, the vanadium-iron spinel undergoes oxidative decomposition, and the trivalent vanadium is gradually oxidized to the pentavalent state, forming high-valence vanadium-containing components with acid leaching activity. Among them, some of the high-valence vanadium can react with the original calcium and manganese components in the vanadium slag to form acid-soluble vanadates, while the other part exists in the roasted clinker in the form of high-valence vanadium oxides. With the oxidative decomposition of the vanadium-iron spinel, the divalent iron in the lattice is further oxidized to form iron-containing oxides represented by α-Fe2O3, which migrate out of the original lattice. The chromium released simultaneously is dissolved in the α-Fe2O3 lattice and the high-melting-point aluminosilicate framework, which helps to reduce the dissolution of chromium in the subsequent acid leaching process.

[0029] While the aforementioned vanadium-containing minerals undergo oxidation and activation, the silicate minerals in the vanadium slag also undergo corresponding phase reconstruction. The vanadium slag contains low-melting-point silicate minerals such as iron olivine (Fe2SiO4) and calcium iron olivine (CaFeSiO4), as well as SiO2 components. Under conventional roasting conditions, these readily form a low-melting-point silicate glassy liquid phase. This liquid phase easily encapsulates the oxidized vanadium-containing components, thereby reducing their contact with subsequent leaching agents. This system, by introducing high-alumina additives, promotes the oxidation and solid-phase reconstruction of these low-melting-point silicates during oxidative roasting, and transforms them... The oxidation process forms a high-melting-point aluminosilicate phase. In the initial stage of the calcination reaction, the silicon-containing components such as fir olivine, calcium iron olivine, and SiO2 in the system undergo a solid-phase reaction with Al2O3 provided by the high-alumina additive and MgO in the system, forming a high-melting-point aluminosilicate phase represented by cordierite in situ. Among them, the iron component of fir olivine is further transformed into Fe2O3 during the oxidation process, while the silicon-containing components participate in the formation of the cordierite phase. For calcium iron olivine, the silicon-containing components can also participate in the reconstruction of the aluminosilicate phase, and some Ca components can also participate in the solid solution process of the cordierite phase.

[0030] As the roasting reaction continues, with the magnesium component participating more in the reaction, the remaining SiO2 and other silicon-containing components in the system further undergo solid-phase reaction with Al2O3, forming high-melting-point aluminosilicate phases such as mullite in situ. As a result, the original low-melting-point silicon-containing components in the vanadium slag gradually transform into high-melting-point aluminosilicate phases such as cordierite and mullite, forming a supporting aluminosilicate framework in the roasted clinker.

[0031] The above-mentioned main phase transformation processes can be represented by the following idealized reaction equations:

[0032] 5SiO2 +2Al2O3+2MgO→Mg2Al4Si5O 18

[0033] 10Fe2SiO4+4Al2O3+4MgO +5O2→2Mg2Al4Si5O 18 +10Fe2O3

[0034] 3Al₂O₃ + 2SiO₂ → Al₆Si₂O 13

[0035] 2Fe₂SiO₄ + 3Al₂O₃ + O₂ → Al₆Si₂O 13 +2Fe2O3

[0036] It should be noted that the above reaction formula is used to characterize the overall stoichiometric relationship of the phase transformation of the main components during the roasting process. Since multiple components such as Fe, V, Si, Al, Mg, Ca, Mn and Ti coexist in vanadium slag, the actual roasting process is also accompanied by oxidation, solid-phase reaction, element solid solution and intermediate phase transformation between different mineral phases. Therefore, the above reaction formula is not the only limitation on the actual reaction path and intermediate products.

[0037] As the aforementioned phase reconstruction process proceeds, the in-situ formed high-melting-point aluminosilicate phases such as cordierite and mullite are distributed among the calcined clinker and jointly construct the aluminosilicate framework. During this process, some SiO2 and low-melting-point silicate components such as fir olivine and calcium olivine in the system are transformed and fixed in the high-melting-point aluminosilicate phase, thereby reducing the formation of low-melting-point silicate glassy liquid phase during calcination. On the one hand, this can reduce the encapsulation of vanadium-containing components after oxidation by the glassy liquid phase, making it easier for vanadium-containing components to be exposed in the subsequent wet milling process. On the other hand, it can improve the high-temperature stability of the calcined material and reduce the tendency for molten bonding between particles and adhesion of materials to the furnace wall.

[0038] Meanwhile, during the oxidative roasting process, vanadium-iron spinel decomposes, causing the low-valence vanadium originally contained in the stable spinel lattice to gradually transform into high-valence vanadium-containing components with higher acid leaching activity. Therefore, the oxidative roasting process of the present invention improves the acid leaching activity of the vanadium-containing components themselves through the transformation of vanadium valence state, and reduces the encapsulation of the glassy liquid relative to the vanadium-containing components by constructing a high-melting-point aluminosilicate framework. The two work together to improve the subsequent leaching performance of the roasted clinker.

[0039] When the above-mentioned roasted clinker is wet-milled and then selectively leached with dilute sulfuric acid, the wet milling process further increases the specific surface area of ​​the roasted clinker and fully exposes the vanadium-containing components separated by the aluminosilicate phase. The acid-soluble vanadates and high-valence vanadium oxides in the clinker enter the leaching solution after contacting with sulfuric acid, while the high-melting-point aluminosilicate phases such as cordierite and mullite formed in situ during the roasting process have high stability under the leaching conditions of this invention and are mainly retained in the leaching residue, thereby achieving selective separation of vanadium components from the aluminosilicate solid phase.

[0040] Therefore, this invention improves vanadium leaching performance while reducing the adverse effects of low-melting-point silicate solution on the roasting and leaching processes through a synergistic process of "low-valent vanadium oxidation activation—low-melting-point silicate phase reconstruction—high-melting-point aluminosilicate framework formation—vanadium-containing component exposure—selective leaching with dilute sulfuric acid".

[0041] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0042] 1. Compared with traditional calcination and sodium calcination processes, this invention utilizes a high-alumina additive to react with silicon-containing components in vanadium slag at high temperatures, generating in situ high-melting-point aluminosilicate phases such as cordierite and mullite, and forming an aluminosilicate framework. This process consumes some of the SiO2 and low-melting-point silicate components in the vanadium slag, reducing the formation of high-temperature silicate glassy liquid phases and lessening their encapsulation of vanadium-containing products, thereby improving the vanadium leaching rate and reducing the tendency of materials to stick together at high temperatures and form rings in the rotary kiln.

[0043] 2. Compared with the traditional calcination-roasting-acid leaching process, this invention does not add calcium oxide, calcium carbonate or other calcining agents. The high-alumina additive itself does not use the formation of calcium vanadate as a vanadium extraction mechanism. The vanadium in the roasting product mainly exists as a high-valence vanadium-containing component with acid leaching activity. At the same time, high-melting-point aluminosilicate phases such as cordierite and mullite have high stability under the acid leaching conditions of this invention. Therefore, it can reduce the calcium sulfate byproducts generated by the additional introduction of calcining agents and help reduce the sulfuric acid consumption in the acid leaching process.

[0044] 3. This invention can use industrial solid waste such as cenospheres and waste corundum as high-alumina additives, so as to realize the vanadium extraction from vanadium slag and the synergistic utilization of aluminum-containing industrial solid waste. The solid phase formed after roasting and leaching is mainly composed of aluminosilicate phase, which provides favorable conditions for the subsequent resource utilization of solid residues, thus taking into account both vanadium resource recovery and comprehensive utilization of industrial solid waste. Attached Figure Description

[0045] Figure 1 The XRD pattern is shown in Example 1 of this invention.

[0046] Figure 2 The XRD pattern is shown in Example 4 of this invention.

[0047] Figure 3 High-temperature melting deformation diagram of triangular pyramidal aggregates with different cenosphere content;

[0048] Figure 4 The images show the high-temperature melting morphology of mixtures with different alumina content. Detailed Implementation

[0049] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0050] The main chemical composition of the vanadium slag used in this embodiment is shown in Table 1. The content of each component is expressed in the form of oxides.

[0051] Table 1

[0052]

[0053] It should be noted that the proportion of high-alumina additives in this application is the mass percentage of high-alumina additives relative to vanadium slag; particle size is characterized by the mass percentage of particles with a diameter less than 0.074 mm; the leaching liquid-to-solid ratio represents the ratio of the volume of the leaching liquid to the mass of the roasted clinker to be leached; unless otherwise specified, the roasting in each embodiment is carried out in an oxygen-containing atmosphere, and the roasted clinker is cooled, wet-milled, and then subjected to sulfuric acid leaching.

[0054] Example 1

[0055] 20 wt.% cenospheres were added to vanadium slag and dry-milled at 180 rpm for 30 min in a ball mill to obtain a mixture with a particle size of -0.074 mm or more (over 90%). The mixture was then placed in an alumina crucible and placed in a muffle furnace, heated from room temperature to 900°C at a heating rate of 10°C / min, and calcined in air for 2 h. The mixture was then naturally cooled in the furnace to obtain clinker. The cooled clinker was then wet-milled at 180 rpm for 30 min to control the particle size of -0.074 mm particles to be over 90%. Subsequently, 20 wt.% H2SO4 solution was added at a liquid-to-solid ratio of 5 L / kg, and the mixture was stirred and leached at 60°C for 2 h. After leaching, the mixture was filtered to separate the vanadium-containing leachate and leaching tailings.

[0056] Testing showed that the leaching rate of vanadium in this embodiment was 94.13%, and the leaching rate of chromium was 0.05%. Figure 1 As shown, aluminosilicate phases such as cordierite were detected in the obtained roasted clinker, along with iron-containing and vanadium-containing phases. The presence of cordierite phase indicates that, under the condition of cenospheres participating in roasting, the silicon-containing components in the vanadium slag underwent aluminosilicate phase reconstruction.

[0057] Example 2

[0058] 10 wt.% waste corundum was added to vanadium slag and dry-milled at 180 rpm for 30 min in a ball mill to obtain a mixture with a particle size of -0.074 mm or more of 90%. The mixture was then placed in a corundum crucible and placed in a muffle furnace, heated from room temperature to 900°C at a heating rate of 10°C / min, and calcined in air for 2 h. The calcined clinker was then naturally cooled in the furnace. The cooled clinker was then wet-milled at 180 rpm for 30 min to control the particle size of -0.074 mm particles to be more than 90%. Subsequently, 20 wt.% H2SO4 solution was added at a liquid-to-solid ratio of 5 L / kg, and the mixture was stirred and leached at 60°C for 2 h. After leaching, the mixture was filtered and separated to obtain vanadium-containing leachate and leaching tailings.

[0059] Tests showed that the leaching rate of vanadium was 90.21% and the leaching rate of chromium was 0.07%.

[0060] Example 3

[0061] 15 wt.% aluminum hydroxide was added to vanadium slag and dry-milled at 180 rpm for 30 min in a ball mill to obtain a mixture with a particle size of -0.074 mm or more of 90%. The mixture was then placed in an alumina crucible and placed in a muffle furnace, heated from room temperature to 950°C at a heating rate of 10°C / min, and calcined in air for 2 h. The calcined clinker was then naturally cooled in the furnace. The cooled clinker was then wet-milled at 180 rpm for 30 min to control the particle size of -0.074 mm or more of 90%. Subsequently, 20 wt.% H2SO4 solution was added at a liquid-to-solid ratio of 5 L / kg, and the mixture was stirred and leached at 60°C for 2 h. After leaching, the mixture was filtered to separate the vanadium-containing leachate and leaching tailings.

[0062] Tests showed that the leaching rate of vanadium was 89.47% and the leaching rate of chromium was 0.11%.

[0063] Example 4

[0064] 30 wt.% alumina was added to vanadium slag and dry-milled at 180 rpm for 30 min in a ball mill to obtain a mixture with a particle size of -0.074 mm or more of 90%. The mixture was then placed in an alumina crucible and placed in a muffle furnace, heated from room temperature to 1000℃ at a heating rate of 10℃ / min, and calcined in air for 2 h. The calcined clinker was then naturally cooled in the furnace. The cooled clinker was then wet-milled at 180 rpm for 30 min to control the particle size of -0.074 mm or more of 90%. Subsequently, 20 wt.% H2SO4 solution was added at a liquid-to-solid ratio of 5 L / kg, and the mixture was stirred and leached at 60℃ for 2 h. After leaching, the mixture was filtered and separated to obtain vanadium-containing leachate and leaching tailings.

[0065] Testing showed that the leaching rate of vanadium in this embodiment was 88.66%, and the leaching rate of chromium was 0.10%. Figure 2 As shown, aluminosilicate phases such as cordierite and mullite were detected in the obtained roasted clinker, indicating that under the condition of alumina participation in roasting, silicon-containing components in vanadium slag can form different types of high-melting-point aluminosilicate phases.

[0066] Example 5

[0067] To further illustrate the effect of high-alumina additives on the high-temperature melting behavior of vanadium slag roasting system, samples with different amounts of cenospheres and alumina were tested for high-temperature melting, and the morphological changes of the samples at different temperatures were observed.

[0068] like Figure 3 As shown, the three groups of samples with cenosphere content of 0%, 25% and 50% all maintained an intact conical shape at 1100℃; when the temperature was raised to 1303℃, each group of samples showed different degrees of melting deformation, and the degree of deformation of the samples decreased after the cenosphere content was increased; thus, it can be seen that the addition of cenosphere can change the melting deformation behavior of the vanadium slag system under high temperature conditions.

[0069] like Figure 4 As shown, the vanadium slag sample without added alumina completely melted at 1290℃; the sample with 25% alumina content had a complete melting temperature increased to 1396℃; and the sample with 50% alumina content still did not completely melt at 1460℃. These results indicate that as the amount of alumina added increases, the sample's ability to resist high-temperature melting improves.

[0070] Based on the aforementioned XRD phase analysis results, it can be seen that the high-alumina additive participates in the phase reconstruction of the silicon-containing components of vanadium slag, forming high-melting-point aluminosilicate phases such as cordierite and mullite, and... Figure 3 and Figure 4 The high-temperature melting tendency exhibited in the process is reduced accordingly; the addition of high-alumina additives can promote the transformation of low-melting-point silicon-containing components into high-melting-point aluminosilicate phases, reduce the formation of low-melting-point silicate glassy liquid phases, and improve the high-temperature stability of the calcination system. This is beneficial to reduce the adhesion of materials on the kiln wall and the tendency of rotary kiln ring formation, and mitigate the adverse effects of low-melting-point liquid phases on the furnace lining and vanadium-containing components.

[0071] Comparative Example 1

[0072] No high-alumina additives were added to the vanadium slag, and the other conditions were the same as in Example 1.

[0073] The leaching rate of vanadium was 74.94%, and the leaching rate of chromium was 2.96%. This comparative example did not add any high-alumina additive, so the aluminum-containing components that could participate in the reconstruction of the silicon-containing phase were relatively insufficient, and the conversion of the low-melting-point silicon-containing phase was limited. Therefore, it was easy to form more glassy liquid phase and encapsulate the vanadium-containing components. At the same time, the chromium leaching rate of this comparative example was significantly higher than that of Example 1, indicating that the calcined solid phase formed by adding high-alumina additive is beneficial to suppressing the dissolution of chromium in the subsequent acid leaching process.

[0074] Comparative Example 2

[0075] The calcination temperature was set to 750℃, and the other conditions were the same as in Example 1.

[0076] The leaching rate of vanadium was 70.31%, and the leaching rate of chromium was 3.48%. The calcination temperature of this comparative example was low, and the oxidation and decomposition of vanadium-iron spinel was insufficient, so low-valence vanadium could not be effectively converted into soluble high-valence vanadium. At the same time, the high-alumina additive lattice was not fully activated, and the aluminosilicate framework could not be generated in situ, resulting in a decrease in vanadium leaching rate and an increase in chromium leaching rate.

[0077] Comparative Example 3

[0078] The calcination temperature was set to 1100℃, and the other conditions were the same as in Example 1.

[0079] The leaching rate of vanadium was 85.42%, and the leaching rate of chromium was 0.04%. The calcination temperature of this comparative example was too high, resulting in severe sintering of the material. The pore structure of the clinker shrank and became dense, making it difficult for dilute sulfuric acid to penetrate into the particles. As a result, the vanadium product could not come into contact with the leaching agent, leading to a decrease in the vanadium leaching rate.

[0080] Comparative Example 4

[0081] Calcium carbonate was used to replace the high-alumina additive, and 20 wt.% of calcium carbonate was added to the vanadium slag, with the remaining conditions the same as in Example 1.

[0082] The leaching rate of vanadium was 95.62% and the leaching rate of chromium was 0.18%. Compared with Example 1, the vanadium leaching rate of the calcium carbonate system was slightly higher, but the chromium leaching rate was correspondingly higher, and the impurity control effect was poor. At the same time, a large amount of calcium sulfate waste residue was generated, which easily caused equipment scaling and high solid waste disposal costs. In addition, the melting temperature of the calcination roasting system was low, the material had strong adhesion during the roasting process, and the risk of ring formation in the rotary kiln was high. The overall performance was inferior to that of the present invention.

[0083] Table 2 summarizes the calcination and leaching conditions, and the V and Cr leaching rates for each embodiment and comparative example.

[0084] Table 2. Process conditions and leaching rates for each embodiment and comparative example.

[0085]

[0086] Based on the experimental data from the examples and comparative examples, the following conclusions can be drawn:

[0087] As can be seen from Examples 1 to 4, when using cenospheres, waste corundum, aluminum hydroxide, and alumina as high-alumina additives, the vanadium leaching rate is 88.66% to 94.13%, and the chromium leaching rate is 0.05% to 0.11%, which can effectively inhibit chromium from entering the leaching solution while maintaining a high vanadium leaching rate. In the listed examples, Example 1 shows a high vanadium leaching rate and a low chromium leaching rate, with a vanadium leaching rate of 94.13% and a chromium leaching rate of only 0.05%.

[0088] Comparative Example 1, without the addition of high-alumina additives, showed a vanadium leaching rate of only 74.94% and a chromium leaching rate of only 2.96%. This result confirms the core role of the aluminosilicate framework: when the system lacks an aluminum source to construct the framework, low-melting-point silicates form a large amount of glassy liquid phase, severely encapsulating vanadium products. Simultaneously, chromium lacks additional solid solution from the aluminosilicate framework, ultimately resulting in low vanadium extraction efficiency and high impurity dissolution. Comparative Examples 2 and 3 respectively show that when the calcination temperature is too low, the oxidation transformation of vanadium-iron spinel and the formation of the aluminosilicate phase are limited; when the calcination temperature is too high, the degree of sintering of the material increases, which is detrimental to subsequent... Continued leaching; combining the roasting results of Examples 1-4 and the above-mentioned phase transformation law, this application controls the roasting temperature at 800-1050℃, and further controls it at 850-1000℃, which is beneficial to balance the oxidation activation of vanadium, the formation of aluminosilicate phase and the leaching performance of clinker; compared with the traditional calcification roasting process of Comparative Example 4, the optimal vanadium leaching rate of this process is similar, but the chromium impurity control effect is better, and it can avoid the addition of a large amount of calcium-containing solid phase byproducts due to the addition of calcifying agent, which is beneficial to reduce the calcium-containing solid phase byproducts caused by the addition of calcifying agent and reduce the increased burden of subsequent processing.

[0089] In summary, this invention achieves silicon-containing phase reconstruction by introducing high-alumina additives, which maintains high vanadium leaching performance while avoiding the increase of calcium-containing solid phase byproducts due to the addition of calcifying agents. It also realizes the resource utilization of aluminum-containing industrial solid wastes such as cenospheres and waste corundum, and has both economic feasibility and environmental benefits.

[0090] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for vanadium extraction from vanadium slag by in-situ support of an aluminosilicate framework during roasting, characterized in that, Includes the following steps: S1. Batching and mixing: Add 10wt.% to 60wt.% of high-alumina additives to vanadium slag, and dry grind to obtain a mixture; S2. Oxidative roasting: The mixture is heated to 800-1050°C and roasted in an oxygen-containing atmosphere, so that the high-alumina additive reacts with the silicon-containing components in the vanadium slag in a solid-phase reaction, forming an aluminosilicate framework in situ, and oxidizing the low-valent vanadium in the vanadium slag to obtain roasted clinker. S3. Leaching: The roasted clinker is wet-milled, and a dilute sulfuric acid solution is added for stirring and leaching. After leaching, solid-liquid separation is performed to obtain vanadium-containing leachate and leaching residue.

2. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 1, characterized in that, The high-alumina additive is at least one of cenospheres, waste corundum, alumina, and aluminum hydroxide.

3. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 2, characterized in that, In step S1, the vanadium content in the vanadium slag is ≥10 wt.% based on V2O5; the Al2O3 content in the cenospheres is 30 wt.% to 40 wt.%; the Al2O3 content in the waste corundum is ≥95 wt.%; the Al2O3 content in the alumina is ≥98 wt.%; and the Al(OH)3 content in the aluminum hydroxide is ≥98 wt.%.

4. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 1, characterized in that, In step S2, the aluminosilicate framework includes at least one of cordierite phase and mullite phase.

5. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 1, characterized in that, In step S2, the calcination temperature is 850–1000°C.

6. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 1, characterized in that, Both the dry-milled mixture in step S1 and the calcined clinker after wet milling in step S3 meet the requirement that the mass percentage of particles with a particle size of less than 0.074 mm is ≥85%.

7. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 6, characterized in that, Both the dry-milled mixture in step S1 and the calcined clinker after wet milling in step S3 meet the requirement that the mass percentage of particles with a particle size of less than 0.074 mm is ≥90%.

8. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 1, characterized in that, In step S2, the calcination time is 0.5 to 3 hours, and the oxygen volume fraction in the oxygen-containing atmosphere is ≥10%.

9. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 1, characterized in that, In step S3, the H2SO4 content in the dilute sulfuric acid solution is 5wt.% to 30wt.%, the leaching temperature is 30 to 90℃, the leaching time is 0.5 to 4h, and the leaching liquid-to-solid ratio is 2 to 6L / kg.

10. The method for in-situ supported vanadium slag roasting and vanadium extraction using an aluminosilicate framework according to claim 9, characterized in that, In step S3, the H2SO4 content in the dilute sulfuric acid solution is 15wt.% to 20wt.%, the leaching temperature is 40 to 80℃, the leaching time is 1.5 to 2.5 h, and the leaching liquid-to-solid ratio is 3 to 5 L / kg.

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