Resourceful treatment method for high-silicon vanadium-chromium reducing slag

Abstract

The invention relates to the technical field of chemical engineering, in particular to a resourceful treatment method of high-silicon vanadium-chromium reducing slag, which comprises the following steps: stirring and mixing the high-silicon vanadium-chromium reducing slag and calcium salt, and calcining to obtain clinker; washing the clinker with water to remove soluble substances in the clinker, and then filtering and washing to obtain a first filter cake; mixing the first filter cake with sulfuric acid to react, so that chromium and vanadium in the first filter cake are respectively and directionally converted into soluble Cr2 (SO4) 3 and VOSO4, and then carrying out water leaching and filtering treatment to obtain second filtrate, so that the chromium and the vanadium enter a liquid phase, and the recovery of the chromium and the vanadium is realized. By means of the scheme, chromium and vanadium resource recycling can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical industry, in particular to a resource treatment method of high-silicon vanadium-chromium reduction slag. BACKGROUND

[0002] In the process of producing chromium hydroxide with silicon, a large amount of waste slag containing chromium and vanadium will be produced. The waste slag contains a high content of Cr2O3 and a certain amount of V2O5. Chromium and vanadium are important valuable metals in the industrial field. If such waste slag is directly stored or simply disposed, not only the valuable metal resources will be wasted, but also the surrounding soil, water and other ecological environment may be at risk due to the potential migration of harmful substances in the waste slag. Therefore, efficient recovery of chromium and vanadium in the waste slag has important resource utilization value and environmental protection significance.

[0003] At present, the treatment technology for such chromium and vanadium-containing waste slag has problems such as low extraction efficiency, complex process flow, high energy consumption or easy secondary pollution, which is difficult to meet the comprehensive needs of industrial production in resource recovery rate, treatment cost and environmental protection requirements. SUMMARY

[0004] The purpose of the present application is to provide a resource treatment method of high-silicon vanadium-chromium reduction slag, which can realize the resource recovery of chromium and vanadium.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: A resource treatment method of high-silicon vanadium-chromium reduction slag, comprising: stirring and mixing the high-silicon vanadium-chromium reduction slag with calcium salt, calcining to obtain clinker; water washing the clinker to remove soluble substances in the clinker, and then filtering and washing to obtain a first filter cake; mixing the first filter cake with sulfuric acid to make chromium and vanadium in the first filter cake respectively directional conversion into soluble Cr2(SO4)3 and VOSO4, and then treating by water immersion or filtration to obtain a second filtrate, so that chromium and vanadium enter the liquid phase to realize the recovery of chromium and vanadium.

[0006] The scheme uses the reaction of calcium and silicon in the slag to convert silicon into silicate which is difficult to dissolve in water by mixing and calcining high-silicon vanadium-chromium reduction slag with calcium salt, and then removes silicon from the system by water immersion, effectively avoiding the wrapping of silicon in the subsequent extraction process or the invalid reaction of silicon with reagents, and clearing the matrix interference for the subsequent directional conversion of chromium and vanadium. Then, the first filter cake obtained by water immersion and filtration after calcination is mixed with sulfuric acid to accurately convert chromium and vanadium into soluble sulfates, and then the target metals enter the liquid phase by water immersion and filtration, realizing the efficient capture of chromium and vanadium from the high-silicon complex matrix.

[0007] And, the pretreatment link of calcination and water washing to remove soluble substances avoids the consumption of sulfuric acid by these soluble impurities in the subsequent reaction with sulfuric acid, so that sulfuric acid can more concentratedly react with chromium and vanadium in the filter cake, reduces the invalid loss of sulfuric acid, and improves the utilization efficiency of the key reagent; meanwhile, after the pretreatment, the impurities in the system are reduced, the impurity removal reagent and operation steps required in the subsequent chromium and vanadium purification process are also simplified accordingly, and the overall process material cost and operation cost are indirectly reduced.

[0008] The method is aimed at high-silicon vanadium-chromium reduction slag, an industrial solid waste, and converts chromium and vanadium therein into recyclable liquid products through a systematic process, so that the solid waste originally requiring stockpiling disposal is converted into a resource with economic value; the environmental risks of metals such as chromium and vanadium in the original slag to soil and water caused by leaching and penetration are avoided, and the requirements of circular economy and environmental protection are met.

[0009] Further, the mixing reaction of the first filter cake with sulfuric acid and then the filtration treatment to obtain the second filtrate specifically include: determining the theoretical sulfuric acid dosage, i.e. the sulfuric acid dosage required for the complete reaction of the vanadium and chromium contents and the alkali content not washed off in the first filter cake; adjusting the moisture content of the first filter cake so that the sulfuric acid concentration is 55% to 70% after adding sulfuric acid; adding 1.3 to 1.8 times the theoretical sulfuric acid dosage of sulfuric acid with a concentration of 98% to the first filter cake, and stirring to obtain a mixture; calcining the mixture at a temperature of 150°C to 200°C for 40 minutes to 80 minutes; after the calcination is completed, adding deionized water to the calcined material at a solid-liquid ratio of 1:4 to 7, and stirring and leaching in a water bath at a temperature of 70°C to 100°C for 45 minutes to 75 minutes, and then filtering and washing to realize solid-liquid separation, to obtain the second filtrate and the second filter cake.

[0010] This scheme designs an excess coefficient of 1.3 to 1.8 times the theoretical amount of sulfuric acid, which not only provides sufficient amount for the reaction of chromium, vanadium and sulfuric acid, and ensures that the insoluble chromium and vanadium oxides can be fully converted into soluble sulfates, but also reduces the invalid loss of sulfuric acid by controlling the excess multiple, avoiding the excessive acidity of the liquid phase during subsequent water immersion, and achieving a balance between complete conversion and controllable cost. In addition, the design of adjusting the moisture content of the filter cake to control the sulfuric acid concentration to 55% to 70% further ensures that the sulfuric acid concentration is in the optimal interval of reaction activity, which not only avoids slow reaction rate and incomplete conversion caused by too low concentration, but also prevents local intense reaction caused by too high concentration, such as the generation of insoluble by-products and the destruction of filter cake dispersibility, to provide a stable reaction environment for chromium and vanadium directional conversion.

[0011] The roasting temperature of the mixture is controlled at 150℃~200℃ and the time is set at 40min~80min. From the perspective of reaction efficiency, 150℃~200℃ is the efficient temperature range for the sulfation reaction of chromium and vanadium oxides with sulfuric acid. This temperature range is sufficient to break the mineral crystal structure, promote the interfacial reaction between sulfuric acid and chromium and vanadium, and accelerate the formation of soluble sulfates. From the perspective of product stability, this temperature range is lower than the decomposition temperature of sulfates, which can avoid the high temperature causing the already formed soluble sulfates to decompose back into insoluble oxides. From the perspective of energy consumption and time balance, the roasting time of 40min~80min is matched with the temperature, which can ensure the full conversion of chromium and vanadium in the filter cake, while avoiding the energy waste and production cycle extension caused by over-roasting, thus balancing the conversion effect and production efficiency.

[0012] In the post-calcination water leaching process, the leaching effect of chromium and vanadium was further optimized by using a combination of parameters including a solid-liquid ratio of 1:4~7, a water bath at 70℃~100℃, and stirring for 45min~75min. The solid-liquid ratio design of 1:4~7 (g / mL) means adding 4~7mL of deionized water per 1g of calcined clinker. This design ensures that the aqueous phase can fully dissolve the soluble sulfates generated during calcination, avoiding the retention of the target metal in the solid phase due to insufficient water, while also avoiding excessive water leading to too low a concentration of chromium and vanadium in the liquid phase, which would increase the energy consumption and cost of subsequent purification and concentration.

[0013] A water bath temperature of 70℃~100℃ can significantly increase the solubility of sulfates in water, while accelerating the dissolution rate and reducing leaching time; stirring can break the concentration gradient at the solid-liquid interface, allowing dissolved chromium and vanadium to quickly enter the liquid phase and avoiding local saturation that hinders further leaching.

[0014] The leaching time of 45 min to 75 min ensures that the soluble sulfates are fully dissolved. Combined with subsequent filtration and washing, chromium and vanadium can be transferred to the second filtrate to the greatest extent, while reducing the entrainment loss of the target metal in the residue. This provides a high-concentration, low-impurity liquid-phase raw material for the subsequent purification and recovery of chromium and vanadium.

[0015] Further, the process of mixing the first filter cake with sulfuric acid and then leaching it in water to obtain the second filtrate specifically includes: determining the theoretical amount of sulfuric acid required, i.e., the amount of sulfuric acid needed to completely react with the vanadium and chromium content and the unwashed alkali content in the first filter cake; adding sulfuric acid with a concentration of 30% to 50% at 1.2 to 1.5 times the theoretical amount of sulfuric acid to the first filter cake and stirring to mix; leaching under stirring and reflux at a temperature of 130℃ to 180℃ for 2 to 4 hours, followed by filtration and washing to achieve solid-liquid separation, obtaining the second filtrate and the second filter cake.

[0016] This solution utilizes 30%–50% low-concentration sulfuric acid, which, compared to 98% concentrated sulfuric acid, not only reduces procurement and storage costs but also avoids equipment damage caused by the strong corrosiveness of high-concentration sulfuric acid. It also reduces the risk of acid mist volatilization during operation, balancing economic efficiency and safety. Furthermore, unlike the process of mixing concentrated sulfuric acid, roasting, and then leaching, this implementation method directly employs an integrated design of sulfuric acid mixing reaction followed by stirring and leaching at a temperature of 130℃–180℃. Its core advantage lies in process compression. It eliminates the need for a separate roasting unit and dedicated roasting furnace equipment, reducing fixed asset investment and equipment maintenance costs. Simultaneously, the leaching process is completed directly in the liquid phase system, eliminating the need for a dry roasting and water wetting process, shortening the production cycle, facilitating continuous production, and adapting to the needs of large-scale industrial operations.

[0017] The leaching temperature of 130℃~180℃ works synergistically with the stirring operation. This temperature range is sufficient to provide the energy required for the reaction, breaking the crystal structure of chromium and vanadium oxides in the first filter cake and promoting their reaction with sulfuric acid to form soluble sulfates. Stirring can enhance solid-liquid contact, avoid reaction dead zones caused by insufficient local acid concentration, and ensure that chromium and vanadium are uniformly converted and dissolved in the liquid phase. High-efficiency conversion can be achieved without relying on high-temperature solid-phase reactions such as calcination.

[0018] A leaching time of 2-4 hours provides ample time for conversion and dissolution: compared to short-time roasting, a longer leaching time allows low-concentration sulfuric acid to fully penetrate the filter cake and react completely with chromium and vanadium encapsulated in fine particles, reducing the loss of target metals due to incomplete reaction and retention in the residue. Subsequent filtration and washing operations further enrich chromium and vanadium in the liquid phase in the second filtrate, laying the foundation for a high-concentration, low-impurity raw material for subsequent purification.

[0019] Furthermore, the method also includes: neutralizing the second filtrate with alkali, filtering to obtain a chromium hydroxide filter cake, a solution containing vanadium ions and sodium sulfate; drying, calcining, and leaching the chromium hydroxide filter cake, then filtering and washing to obtain a third filtrate and a third filter cake, drying the third filter cake to obtain chromium oxide green; adjusting the pH value of the third filtrate and the solution containing vanadium ions and sodium sulfate to a preset range, filtering to obtain a hydrated vanadium oxide filter cake, and calcining and purifying to obtain vanadium pentoxide.

[0020] In the second filtrate, chromium and vanadium coexist in ionic form. If they are not separated and directly purified, the two metals will interfere with each other, making it difficult to achieve the required purity in the final product. This preferred embodiment utilizes the key step of alkali neutralization, taking advantage of the different precipitation characteristics of different metal ions at a specific pH. The addition of alkali adjusts the pH of the liquid phase to a range where chromium preferentially precipitates while vanadium remains dissolved, thus allowing chromium to precipitate more readily. 3+ Directed conversion into chromium hydroxide solid filter cake, while V 5+ V 4+It remains stably present in the solution, specifically the solution containing vanadium ions and sodium sulfate. This selective precipitation separation design completely breaks the mixed state of chromium and vanadium in the liquid phase, avoiding the problem of chromium residue affecting vanadium purity or vanadium residue contaminating chromium products during subsequent purification. It provides single-component raw materials for the subsequent separate preparation of high-purity chromium oxide green and vanadium pentoxide, which is a core prerequisite for ensuring product quality.

[0021] Directional preparation of chromium oxide green: Chromium hydroxide filter cake can be converted into chromium oxide through drying and calcination. Subsequent leaching, filtration, and washing can remove trace impurities such as sodium and vanadium adsorbed on the surface of the filter cake. This series of operations can improve the purity of chromium oxide to industrial application standards. Chromium oxide green is a key raw material in ceramics, coatings, metallurgy, and other fields, and has a higher market value compared to crude chromium salts.

[0022] Purification and preparation of vanadium pentoxide: A solution containing vanadium ions is reacted with the third filtrate after leaching with chromium hydroxide (which may contain trace amounts of unprecipitated Cr). 3+ The vanadium ions are combined and their pH is adjusted to induce the directional conversion of vanadium ions into hydrated vanadium oxide precipitate. This precipitate is then removed by calcination to remove water of crystallization and residual impurities, ultimately yielding vanadium pentoxide (V₂O₅). Vanadium pentoxide is a core product of the vanadium industry, widely used in steel desulfurization, catalysts, battery materials, and other fields, realizing the high-value utilization of vanadium resources.

[0023] Furthermore, the second filtrate obtained is neutralized with alkali, and filtered to obtain chromium hydroxide filter cake, a solution containing vanadium ions and sodium sulfate. Specifically, the pH value of the second filtrate is adjusted to 6.5-7.0 with 50% sodium hydroxide in a water bath at 60℃-80℃, and then kept warm and stirred for 30-60 minutes. Finally, the filtrate is filtered to obtain chromium hydroxide filter cake, a solution containing vanadium ions and sodium sulfate.

[0024] Within the pH range of 6.5 to 7.0, the chromium ions (Cr) in the second filtrate... 3+ Will react with OH — The directional reaction generates chromium hydroxide precipitate, minimizing the residue of chromium ions in the liquid phase and avoiding chromium loss. Simultaneously, vanadium ions in the second filtrate remain stably dissolved in a neutral to slightly acidic environment of 6.5–7.0, and will not precipitate along with the chromium hydroxide, completely avoiding cross-interference issues such as vanadium being encapsulated in the chromium filter cake or chromium residue contaminating the vanadium-containing solution.

[0025] Compared to low-concentration alkali (such as 20%~30% NaOH), 50% high-concentration sodium hydroxide can significantly reduce the amount of reagent required to adjust pH, avoid excessive dilution of the filtrate due to the addition of a large amount of low-concentration alkali, shorten the pH adjustment operation time, and avoid increasing the energy consumption of evaporation and concentration due to excessive water volume during subsequent purification of vanadium-containing solutions, thus balancing process efficiency and cost control.

[0026] A water bath temperature of 60℃~80℃ can significantly accelerate the Cr 3+ With OH — The reaction rate is increased, promoting the rapid formation of chromium hydroxide precipitate. More importantly, moderate heating can regulate the precipitate morphology of chromium hydroxide, causing the precipitate to form larger, more loosely structured flocculent particles, rather than fine particles. This optimized precipitate morphology can significantly improve subsequent filtration efficiency while reducing the content of adsorbed impurity ions in the filter cake, thus reducing the burden on subsequent chromium hydroxide purification.

[0027] The 30-60 minute incubation with stirring is a crucial detail in this step, its core function being to optimize the quality of the precipitate. During aging, the already formed fine chromium hydroxide particles gradually aggregate into larger particles through the Ostwald ripening effect. Simultaneously, trace amounts of vanadium ions and sodium sulfate adsorbed on the particle surface are desorbed back into the liquid phase, effectively reducing the residual vanadium in the chromium hydroxide filter cake and minimizing chromium loss during the filtering of fine particles, further improving chromium recovery. Incubation with stirring maintains a stable system temperature, preventing repeated dissolution and reprecipitation of the precipitate due to temperature drops during aging, and preventing the large particles from redispersing into smaller particles, ensuring the precipitate remains in an optimal state of easy filtering and low impurities.

[0028] Furthermore, the drying, calcination, and leaching of the chromium hydroxide filter cake specifically includes: drying the chromium hydroxide filter cake at a temperature of 100℃~110℃ for 6h~10h, and then calcining it at a temperature of 800℃~1200℃ for 2h~4h; after calcination, adding the calcined clinker to deionized water at a solid-liquid ratio of 1:4~7, and stirring and leaching it in a water bath at a temperature of 70℃~100℃ for 45min~75min.

[0029] The drying temperature of 100℃~110℃ efficiently evaporates free water and some adsorbed water in the filter cake, while avoiding surface hardening or particle sintering caused by high temperatures, thus maintaining the internal porous structure and facilitating gas escape and full reaction during subsequent calcination. A drying time of 6h~10h ensures that the moisture content of the filter cake is reduced to an extremely low level, preventing material splashing or temperature fluctuations caused by rapid moisture evaporation during calcination. It also reduces the formation of low-melting-point eutectic compounds between moisture and impurities at high temperatures, thus reducing the difficulty of subsequent leaching and impurity removal.

[0030] If the calcination temperature is too low, decomposition will be incomplete, leaving residual chromium hydroxide or intermediate oxides, affecting product purity and color. If the calcination temperature is too high, it may lead to excessive sintering of particles and a decrease in specific surface area, affecting the leaching efficiency of impurities during subsequent leaching. Within this temperature range of 800℃ to 1200℃, not only can the complete conversion of chromium hydroxide into the stable α-Cr2O3 crystal form be ensured, but trace organic matter and adsorbed water can also be removed through high-temperature sintering, significantly improving product purity. A holding time of 2h to 4h ensures uniform internal temperature and complete reaction of the material, while promoting grain growth and forming dense chromium oxide particles with high physicochemical stability.

[0031] Furthermore, adjusting the pH of the third filtrate and the solution containing vanadium ions and sodium sulfate to a preset range specifically includes: mixing the third filtrate and the solution containing vanadium ions and sodium sulfate and heating to 80℃~90℃, adding a 50% sodium hydroxide solution dropwise under stirring, adjusting the pH of the solution to 9.0~10.0, and continuing to keep it warm and stir for 30min~60min.

[0032] At a pH of 9.0–10.0, vanadium ions in the mixed solution will react with OH-. — The directed reaction produces hydrated vanadium oxide. If the pH value is too low, vanadium ions are difficult to precipitate sufficiently, leading to vanadium loss. If the pH value is too high, water-soluble vanadates, such as NaVO3, may be formed, causing vanadium to redissolve. Simultaneously, this pH range has no precipitation effect on trace impurities remaining in the solution, such as small amounts of unseparated Cr. 3+ The impurities have been removed in previous steps; the main impurity is Na. + SO4 2— , making Na + SO4 2— It will remain stably in the liquid phase and will not precipitate along with hydrated vanadium oxide, thus completely avoiding the problem of impurities co-precipitating and contaminating the vanadium filter cake.

[0033] Furthermore, the preparation of the clinker specifically includes: determining the silicon content in the high-silicon vanadium-chromium reducing slag, adding calcium salt according to a Ca to Si molar ratio of 2 to 3, and stirring to mix evenly; after stirring, calcining at a temperature of 400℃ to 600℃ for 2 to 3 hours to obtain the clinker.

[0034] In high-silicon vanadium-chromium reduction slag, silicon is mainly in the form of SiO2. The reaction product of calcium salts (calcium oxide or calcium hydroxide) and SiO2 is insoluble calcium silicate, such as Ca2SiO4 and Ca3SiO5, with a Ca:Si molar ratio of approximately 2-3. Adding calcium salts in this ratio ensures that the SiO2 in the slag is fully reacted, avoiding silicon residue due to insufficient calcium. Residual SiO2 can coat chromium and vanadium during subsequent acid leaching or react with sulfuric acid to form insoluble silicic acid, severely reducing the chromium and vanadium recovery rate.

[0035] The calcination temperature of 400℃ to 600℃ provides energy for the interfacial reaction between calcium salts and silicon, promoting the rapid formation of calcium silicate. If the temperature is too low, the reaction rate is extremely slow, and the silicon conversion is incomplete. If the temperature is too high, although it can accelerate the silicon reaction, it will cause the chromium and vanadium oxides (Cr2O3, V2O5) in the slag to sinter prematurely or form insoluble complex oxides with other components (such as excess calcium salt), such as CaCrO4 and Ca3(VO4)2, which will increase the difficulty of subsequent acid leaching to extract chromium and vanadium. Furthermore, 400℃ to 600℃ is within the medium-temperature calcination range. Compared with high-temperature calcination, such as above 800℃, the required heating energy consumption is lower, and the requirements for the temperature-resistant materials of the calcination equipment are also lower, which significantly reduces the energy cost and fixed asset investment of the process.

[0036] A calcination time of 2-3 hours allows the reaction between calcium salts and SiO2 to penetrate from the surface into the interior of the slag, avoiding the problem of localized residues where the outer silicon layer has reacted while the inner silicon layer has not come into contact with the calcium salt due to insufficient time, thus further improving the silicon reaction rate. Excessively prolonged calcination time can easily lead to over-sintering and agglomeration of the generated calcium silicate particles, making it difficult for soluble calcium silicate to dissolve quickly during subsequent water leaching, increasing leaching time and operational difficulty. A time of 2-3 hours allows the clinker to maintain a loose structure, creating favorable conditions for solid-liquid contact during subsequent water leaching for silicon removal, thereby improving the leaching efficiency of soluble substances.

[0037] Furthermore, the process of immersing the clinker in water specifically includes: mixing the clinker and deionized water at a solid-liquid ratio of 1:4 to 7, and stirring and immersing for 45 to 75 minutes in a water bath at a temperature of 70°C to 100°C.

[0038] Under leaching conditions, chromium and vanadium in the clinker mainly exist in the form of oxides and are basically insoluble in water. Therefore, most of the chromium and vanadium will remain in the solid phase (first filter cake), providing high-grade raw materials for the subsequent acid leaching process to centrally recover chromium and vanadium.

[0039] The present invention has the following unexpected beneficial effects: This invention utilizes the mixed calcination of high-silicon vanadium-chromium reducing slag and calcium salts. The reaction between calcium and silicon in the slag converts silicon into water-soluble silicates. Subsequent water leaching removes the silicon from the system, eliminating matrix interference for the subsequent targeted conversion of chromium and vanadium. The first filter cake obtained after calcination is then reacted with sulfuric acid to precisely convert chromium and vanadium into soluble sulfates. Water leaching or filtration allows the target metals to enter the liquid phase, achieving highly efficient capture of chromium and vanadium from a complex high-silicon matrix. Attached Figure Description

[0040] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0041] Figure 1 This document illustrates a flowchart of one embodiment of the resource utilization treatment method for high-silicon vanadium-chromium reducing slag described in this application.

[0042] Figure 2 A schematic flowchart of another embodiment of the resource utilization treatment method for high-silicon vanadium-chromium reducing slag described in this application is shown. Detailed Implementation

[0043] Analysis revealed that the high-silicon vanadium-chromium reduction slag purchased from Panzhihua Iron and Steel Group contained 32-35% Cr2O3 and approximately 5% V2O5. This application proposes a sulfation roasting process to achieve efficient extraction of chromium and vanadium. The chromium and vanadium in the slag are converted into soluble sulfates (Cr2(SO4)3 and VOSO4), and then subjected to water leaching to allow the target metals to enter the liquid phase, thereby achieving the recovery of chromium and vanadium.

[0044] The instruments, equipment and reagents involved in the embodiments of this application include a constant temperature water bath, an oven, chromium hydroxide silicate slag, concentrated sulfuric acid, a circulating water vacuum pump, a 300ml beaker, deionized water and tap water.

[0045] Example 1, see Figure 1 As shown, this application provides a method for the resource utilization of high-silicon vanadium-chromium reduction slag, which includes: High-silicon vanadium-chromium reducing slag was mixed with calcium salt and calcined to obtain clinker. Specifically, the silicon content in the high-silicon vanadium-chromium reducing slag was determined, and calcium salt was added according to a Ca to Si molar ratio of 2-3, and the mixture was stirred until homogeneous. After stirring, the mixture was calcined at 500℃ for 3 hours to obtain clinker.

[0046] The clinker is washed with water to remove soluble substances, and then filtered and washed to obtain the first filter cake. Specifically, after the clinker conversion is completed, water is added to slurry and wash three times to remove most of the alkali salts. After the filter cake is filtered and dried, solidified silica slag, i.e., the first filter cake, is obtained.

[0047] The first filter cake is mixed with sulfuric acid to react, causing chromium and vanadium in the first filter cake to be directionally converted into soluble Cr2(SO4)3 and VOSO4, respectively. The resulting filtrate is then subjected to water leaching and filtration to obtain a second filtrate, allowing chromium and vanadium to enter the liquid phase and achieving chromium and vanadium recovery. Specifically, the vanadium and chromium content and the content of unwashed alkali in the first filter cake are first analyzed, and the theoretical amount of sulfuric acid required is calculated based on the analysis results. Next, 20g of the first filter cake is weighed and placed in a 300mL beaker, and the amount of sulfuric acid added is 1.4 times the theoretical amount. That is, 25.5g of water is added to the beaker and mixed evenly with the first filter cake. Then, 32.4g of 98% concentrated sulfuric acid is slowly added and stirred evenly until the material becomes a paste, with a final sulfuric acid concentration of 56%.

[0048] Then, the well-mixed material was placed in an oven at 150℃ and roasted for 80 minutes. After roasting, the material turned green, indicating that the chromium had been converted into chromium sulfate, and some of the water in the material had evaporated, leaving a paste-like consistency.

[0049] Finally, the calcined material was leached with deionized water at a liquid-to-solid ratio of 1:5, i.e., 5 mL of deionized water was added for every 1 g of material. The pH was measured and found to be <1. The leaching was carried out under stirring in a water bath at 80°C for 60 min. The second filtrate after leaching was green, indicating that chromium had entered the liquid phase.

[0050] After leaching, a vacuum pump is used for solid-liquid separation to obtain a second filtrate and a second filter cake.

[0051] Example 2 differs from Example 1 in that the amount of sulfuric acid added in this example is 1.3 times the theoretical amount. Specifically, 20g of the first filter cake is weighed and placed in a 300 mL beaker, then 23.7g of water is added to the beaker and mixed evenly with the first filter cake. Then, 30.1g of 98% concentrated sulfuric acid is slowly added. All other parameters are the same as in Example 1.

[0052] Example 3 differs from Example 1 in that the amount of sulfuric acid added in this example is 1.5 times the theoretical amount. Specifically, 20g of the first filter cake is weighed and placed in a 300 mL beaker, then 27.3g of water is added to the beaker and mixed evenly with the first filter cake. Then, 34.7g of concentrated sulfuric acid with a concentration of 98% is slowly added. All other parameters are the same as in Example 1.

[0053] Example 4 differs from Example 1 in that the amount of sulfuric acid added is 1.8 times the theoretical amount. Specifically, 20g of the first filter cake is weighed and placed in a 300mL beaker, then 33.0g of water is added and mixed thoroughly. Next, 41.6g of 98% concentrated sulfuric acid is slowly added and stirred until homogeneous. The resulting material is then placed in an oven at 200℃ and roasted for 60 minutes. All other parameters are the same as in Example 1.

[0054] Example 5 differs from Example 1 in that the amount of sulfuric acid added is 1.6 times the theoretical amount, and chromium and vanadium extraction is performed using first filter cakes prepared from different batches of raw materials. Specifically, 20g of the first filter cake is weighed and placed in a 300mL beaker, then 29.0g of water is added and mixed evenly with the first filter cake. Then, 37.0g of 98% concentrated sulfuric acid is slowly added and stirred evenly to obtain the material. The material is then placed in an oven at 200℃ and calcined for 60 minutes. All other parameters are the same as in Example 1.

[0055] Example 6 differs from Example 5 in that the final sulfuric acid concentration in the material is 70%. Specifically, 20g of the first filter cake is weighed and placed in a 300mL beaker. 15.8g of water is added to the beaker and mixed thoroughly with the first filter cake. Then, 37.0g of 98% concentrated sulfuric acid is slowly added and stirred until a paste-like consistency is achieved. The final sulfuric acid concentration in the material is 70%. All other parameters are the same as in Example 5.

[0056] Example 7 differs from Example 6 in that the amount of sulfuric acid added in this example is 1.6 times the theoretical amount. Specifically, 20g of the first filter cake is weighed and placed in a 300mL beaker, then 15.8g of water is added and mixed thoroughly. Then, 37g of 98% concentrated sulfuric acid is slowly added and stirred until a paste-like consistency is achieved, with a final sulfuric acid concentration of 70%. The thoroughly mixed material is then placed in an oven at 150℃ and baked for 40 minutes. The rest of the process is the same as in Example 6.

[0057] Example 8 differs from Example 6 in that the calcination time is 60 minutes, while the other parameters are the same as in Example 6.

[0058] Example 9 differs from Example 6 in that the roasting time is 80 minutes, while the other parameters are the same as in Example 6.

[0059] Example 10 differs from Example 6 in that the amount of the first filter cake added is 50g. Specifically, 50g of the first filter cake is weighed and placed in a 300mL beaker, and 40.0g of water is added to the beaker. The mixture is then thoroughly mixed with the first filter cake, and 92.0g of 98% concentrated sulfuric acid is slowly added and stirred until homogeneous. The resulting material is then placed in an oven at 150℃ and calcined for 80 minutes. All other parameters are the same as in Example 10.

[0060] Comparative Example 1 differs from Example 1 in that the amount of sulfuric acid added in this comparative example is 1.2 times the theoretical amount of sulfuric acid. Specifically, 20g of the first filter cake is weighed and placed in a 300 mL beaker, then 21.8g of water is added to the beaker and mixed evenly with the first filter cake. Then, 27.8g of concentrated sulfuric acid with a concentration of 98% is slowly added. All other parameters are the same as in Example 1.

[0061] Comparative Example 2 differs from Example 5 in that the amount of sulfuric acid added in this comparative example is 1.6 times the theoretical amount of sulfuric acid. Specifically, 20g of the first filter cake is weighed and placed in a 300 mL beaker, then 55.3g of water is added to the beaker and mixed evenly with the first filter cake. Then, 37g of concentrated sulfuric acid with a concentration of 98% is slowly added and stirred evenly until the material becomes a paste. The final concentration of sulfuric acid in the material is 40%. The remaining parameters are the same as in Example 5.

[0062] The second filtrate stock solution and the second filtrate washing solution obtained in Examples 1 to 10, Comparative Example 1 and Comparative Example 2 were respectively adjusted to a fixed volume, and the mass of the second filter cake was weighed. The results are shown in Table 1.

[0063] Table 1 Results of the determination of the volume of the second filtrate and the mass of the second filter cake Total chromium and ICP were determined for Examples 1 to 11, Comparative Example 1 and Comparative Example 2, respectively, and the results are shown in Tables 2 and 3.

[0064] Table 2. Results of total chromium and ICP determination in the second filtrate. Table 3. Results of total chromium and ICP determination in the second filter cake. The ICP analysis results of the second filtrate and second filter cake from Examples 1 to 3 and Comparative Example 1 in Tables 2 and 3 show that, for the same batch of first filter cake, the content of chromium and vanadium in the first filter cake gradually decreases with the increase of sulfuric acid addition. When the amount of sulfuric acid added is greater than or equal to 1.3 times the theoretical amount of sulfuric acid, that is, when the content of chromium in the second filter cake obtained from Examples 1 to 3 is less than 1.9% and the content of vanadium is less than 0.3%, almost all of the chromium and vanadium have been extracted.

[0065] The ICP analysis results of the second filtrate and second filter cake from Examples 5, 6, and Comparative Example 2 in Tables 2 and 3 show that the final sulfuric acid concentration in the material affects the extraction rates of chromium and vanadium when the sulfuric acid addition is 1.6 times the theoretical amount. If the concentration is too low, it indicates that too much water has been added, requiring a longer reaction time or a higher reaction temperature to achieve the desired extraction effect. If the concentration is too high, it will cause the sulfuric acid and slag phase to agglomerate and mix unevenly, leading to incomplete reaction and affecting the extraction rates of chromium and vanadium. When the sulfuric acid concentration is between 56% and 70%, the material can be mixed evenly, and the extraction rates of chromium and vanadium both reach over 95%.

[0066] The ICP analysis results of the second filtrate and second filter cake from Examples 7 to 9 in Tables 2 and 3 show that, under the condition of a calcination temperature of 150°C, the content of chromium and vanadium in the second filter cake gradually decreases with increasing calcination time. The extraction rates of chromium and vanadium reach their maximum values ​​of 97% and 99%, respectively, at a calcination temperature of 150°C and a calcination time of 80 min.

[0067] The extraction rates of chromium and vanadium were calculated based on the chromium and vanadium content in the second filter cake. The results are shown in Table 4 below. Table 4 Extraction rates of chromium and vanadium Comparing the extraction rate results of Examples 1 to 3 with Comparative Example 2, the extraction rates of chromium and vanadium in Comparative Example 1 were lower than those in Examples 1 to 3. Comparing the extraction rate results of Examples 4, 6, and Comparative Example 2, the extraction rates of chromium and vanadium in Comparative Example 1 were lower than those in Examples 4 and 6.

[0068] Example 11, see Figure 2 As shown, this application provides a method for the resource utilization of high-silicon vanadium-chromium reduction slag, which further includes: neutralizing the second filtrate obtained in Example 1 with an alkali, that is, adjusting the pH value of the second filtrate obtained in Example 1 to 6.9 with 50% sodium hydroxide at a water bath temperature of 80°C, continuing to keep it warm and stir for 45 minutes, and then filtering to obtain a solution containing vanadium-chromium hydroxide filter cake and sodium sulfate.

[0069] The vanadium-containing chromium hydroxide filter cake was calcined and leached. Specifically, the chromium hydroxide filter cake was calcined at 950℃ for 3.5 hours. After calcination, the calcined clinker was added to deionized water at a solid-liquid ratio of 1:4, and leached under stirring in a water bath at 70℃~100℃ for 60 minutes. The mixture was then filtered and washed to obtain a third filtrate and a third filter cake. The third filter cake was dried to obtain chromium oxide green. The pH of the third filtrate and the solution containing vanadium ions and sodium sulfate were adjusted to the preset range. Specifically, the third filtrate and the solution containing vanadium ions and sodium sulfate were mixed and heated to 85°C. A 50% sodium hydroxide solution was added dropwise under stirring to adjust the pH of the solution to 9.5. The mixture was then kept warm and stirred for 45 minutes. The resulting hydrated vanadium oxide filter cake was obtained by filtration and then calcined and purified to obtain vanadium pentoxide.

[0070] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A method for the resource-based treatment of high-silicon vanadium-chromium reducing slag, characterized in that, include: The high-silicon vanadium-chromium reducing slag was mixed with calcium salt and calcined to obtain clinker; The clinker is washed with water to remove soluble substances, and then filtered and washed to obtain the first filter cake. The first filter cake is mixed with sulfuric acid to react, so that the chromium and vanadium in the first filter cake are directionally converted into soluble Cr2(SO4)3 and VOSO4, respectively. Then, the second filtrate is obtained by water leaching and filtration, so that the chromium and vanadium enter the liquid phase and the chromium and vanadium are recovered.

2. The method for resource-based treatment of high-silicon vanadium-chromium reducing slag according to claim 1, characterized in that: The first filter cake is mixed with sulfuric acid and reacted, and then filtered to obtain the second filtrate, which specifically includes: Determine the theoretical amount of sulfuric acid required, which is the amount of sulfuric acid needed to completely react with the vanadium and chromium content and the unwashed alkali content in the first filter cake. Adjust the moisture content of the first filter cake so that the sulfuric acid concentration is 55%~70% after adding sulfuric acid; Add 1.3 to 1.8 times the theoretical amount of sulfuric acid to the first filter cake, and stir to obtain a mixture. The mixture is calcined at a temperature of 150℃~200℃ for 40min~80min; After roasting, the roasted clinker is added to deionized water at a solid-liquid ratio of 1:4~7, and stirred and leached for 45min~75min under a water bath at a temperature of 70℃~100℃. Then, the solid and liquid are separated by filtration and washing to obtain the second filtrate and the second filter cake.

3. The method for resource-based treatment of high-silicon vanadium-chromium reducing slag according to claim 1, characterized in that: The first filter cake is mixed with sulfuric acid and reacted, and then the second filtrate is obtained by water leaching. Specifically, the process includes: Determine the theoretical amount of sulfuric acid required, which is the amount of sulfuric acid needed to completely react with the vanadium and chromium content and the unwashed alkali content in the first filter cake. Add 1.2 to 1.5 times the theoretical amount of sulfuric acid (30% to 50%) to the first filter cake and stir to mix. The mixture is stirred and refluxed at a temperature of 130℃~180℃ for 2h~4h, then filtered and washed to achieve solid-liquid separation, yielding a second filtrate and residue.

4. The method for resource-based treatment of high-silicon vanadium-chromium reducing slag according to claim 1, characterized in that, It also includes: neutralizing the second filtrate with alkali, and filtering to obtain chromium hydroxide filter cake, a solution containing vanadium ions and sodium sulfate; The chromium hydroxide filter cake is dried, calcined, and leached, then filtered and washed to obtain a third filtrate and a third filter cake. The third filter cake is then dried to obtain chromium oxide green. The pH of the third filtrate and the solution containing vanadium ions and sodium sulfate were adjusted to the preset range, and the hydrated vanadium oxide filter cake was obtained by filtration. Vanadium pentoxide was obtained by calcination and purification.

5. The method for resource-based treatment of high-silicon vanadium-chromium reducing slag according to claim 4, characterized in that: The second filtrate obtained by neutralizing it with alkali and filtering it yields a chromium hydroxide filter cake, a solution containing vanadium ions and sodium sulfate, specifically including: The pH of the second filtrate was adjusted to 6.5-7.0 with 50% sodium hydroxide in a water bath at 60-80°C. The solution was then kept warm and stirred for 30-60 minutes. Finally, the solution was filtered to obtain chromium hydroxide filter cake and a solution containing vanadium ions and sodium sulfate.

6. The method for resource-based treatment of high-silicon vanadium-chromium reducing slag according to claim 4, characterized in that: The process of drying, calcining, and leaching chromium hydroxide filter cake specifically includes: The chromium hydroxide filter cake was dried at 100℃~110℃ for 6h~10h, and then calcined at 800℃~1200℃ for 2h~4h. After calcination, the calcined clinker is added to deionized water at a solid-liquid ratio of 1:4~7, and stirred and leached for 45min~75min under a water bath at a temperature of 70℃~100℃.

7. The method for resource-based treatment of high-silicon vanadium-chromium reducing slag according to claim 4, characterized in that: Adjusting the pH of the third filtrate and the solution containing vanadium ions and sodium sulfate to the preset range specifically includes: Mix the third filtrate with a solution containing vanadium ions and sodium sulfate and heat to 80℃~90℃. Add a 50% sodium hydroxide solution dropwise while stirring to adjust the pH of the solution to 9.0~10.

0. Continue to heat and stir for 30min~60min.

8. The method for resource-based treatment of high-silicon vanadium-chromium reducing slag according to claim 1, characterized in that, The preparation of the clinker specifically includes: To determine the silicon content in the high-silicon vanadium-chromium reduction slag, calcium salts were added according to a Ca to Si molar ratio of 2 to 3, and the mixture was stirred until homogeneous. After stirring, calcine at 400℃~600℃ for 2h~3h to obtain clinker.

9. The method for resource-based treatment of high-silicon vanadium-chromium reducing slag according to claim 1, characterized in that, The process of immersing clinker in water specifically includes: mixing clinker and deionized water at a solid-liquid ratio of 1:4~7, and stirring and immersing in a water bath at a temperature of 70℃~100℃ for 45min~75min.

Images