Silica removal agent and application thereof in alkaline vanadium-containing leachate

Abstract

The invention discloses a silicon removal agent and application thereof in alkaline vanadium-containing leachate, and the silicon removal agent is obtained through the following steps: taking aluminum-containing silicon removal slag as a raw material, putting the aluminum-containing silicon removal slag into a NaOH solution, continuously stirring, filtering, collecting solids, drying and grinding to obtain the silicon removal agent, wherein the pH (Potential of Hydrogen) value of the NaOH solution is 8.0 to 10.0; the NaOH solution also contains cationic polyacrylamide, and the concentration of the cationic polyacrylamide is 0.1 to 0.3 mg / ml; the stirring temperature is 80 to 95 DEG C, and the temperature is kept for 60 to 120 minutes. Alkaline vanadium-containing leachate obtained through a sodium salt roasting-water leaching process of vanadium-containing raw materials (vanadium slag and the like) is used as a raw material, aluminum salt (aluminum sulfate, sodium metaaluminate and the like) is used as an impurity removal agent, precipitate sodium aluminosilicate hydrate is added, a sodium aluminosilicate porous material is obtained after treatment, and the sodium aluminosilicate porous material can be used as a silicon removal agent and precipitate floc. And removing silicon impurities in the solution under a weakly alkaline condition.

Description

Technical Field

[0001] This application relates to the field of hydrometallurgical technology of vanadium, specifically to a silicon removal agent and its application in alkaline vanadium-containing leachate. Background Technology

[0002] In recent years, with the rapid development of the new energy revolution and high-end manufacturing, the application of vanadium in high-end fields such as energy storage batteries, special alloys, and pharmaceutical catalysis has been increasing year by year, placing higher demands on the purity of vanadium oxide products. Taking vanadium redox flow batteries as an example, their electrolytes generally require a V₂O₅ purity of over 99.9%, while impurities such as silicon can lead to decreased electrochemical activity and accelerated battery capacity decay. In the pharmaceutical field, when vanadium compounds are used as insulin mimics, trace amounts of silicon may trigger biotoxic reactions. Furthermore, in aerospace applications, silicon impurities in high-purity vanadium-titanium alloys can severely affect the high-temperature creep resistance of the materials. Therefore, deeply removing impurities such as silicon from the source of vanadium-containing leachate to improve the quality of vanadium oxide products is of significant strategic importance for promoting the vanadium industry's ascent to the high-end value chain.

[0003] Currently, the main methods for removing Si(IV) from vanadium-containing leachates include chemical precipitation, solvent extraction, ion exchange, and adsorption. Solvent extraction generally suffers from problems such as easy loss of the organic phase due to volatilization, high extraction agent procurement costs, difficulty in treating oily wastewater, and the potential for excessive organic carbon in vanadium products, making large-scale application difficult. Ion exchange and adsorption methods have inherent drawbacks such as limited adsorption capacity, poor adaptability to high-concentration silicon-containing alkaline systems, frequent and costly resin / adsorbent regeneration, and the inability to achieve continuous industrial production; they are only suitable for deep refining of low-concentration vanadium solutions. Therefore, chemical precipitation, with its simple process flow, large processing capacity, and controllable desilication costs, has become the mainstream industrial technology for desilication of vanadium-containing leachates, with magnesium salt precipitation and aluminum salt precipitation being the most widely used.

[0004] Patent CN101709376B discloses a purification method for alkaline vanadium leaching solution. It uses magnesium nitrate to purify the solution, obtaining a purified clear liquid. Ammonium salts are then used to precipitate vanadium from the purified clear liquid, yielding vanadium products and vanadium-precipitated wastewater, some of which is returned to the leaching step. However, this patent requires the addition of excessive magnesium nitrate to achieve deep silicon removal, directly increasing the cost of raw materials. Furthermore, excessive nitrate ions accumulate continuously in the leaching solution system, corroding production equipment and causing severe exceedances of total nitrogen in the discharged wastewater, significantly increasing the cost of wastewater treatment and environmental control pressure. Magnesium nitrate desiliconization relies on the adsorption and co-precipitation of silicate ions by magnesium hydroxide colloid. While adsorbing silicon, magnesium hydroxide colloid also carries a large number of vanadate ions, resulting in direct vanadium loss and reducing the overall vanadium recovery rate. The continuous enrichment of nitrate ions in the system also affects the crystallization efficiency of the subsequent vanadium precipitation process, easily leading to uneven particle size and decreased purity of the vanadium product.

[0005] Patent CN117004834B discloses a method for preparing a vanadium-containing silicon-removing agent and its application, which involves preparing a Mg-containing agent by electrolyzing Mg sheets in a silicon-free vanadium solution. 2+ The silica removal agent, by adding solid HVO3, Na3VO4, and NaVO3 to adjust the pH value, can react with the silicon-vanadium-containing solution to form Mg. x (SiO3) y The silicon is then removed by heating and precipitation. However, this method requires a dedicated electrolytic reaction device, which places high demands on the corrosion resistance, sealing, and power supply control system of the equipment. The process is lengthy and the operation and management are complex. The equipment investment and energy consumption are much higher than conventional precipitation processes, making it unsuitable for large-scale industrial continuous production. In order to adjust the reaction pH value, various vanadium-containing solid compounds need to be added, which not only increases the cost of raw and auxiliary materials but also introduces new impurity ions, further increasing the difficulty of subsequent vanadium product purification. Moreover, the magnesium silicate precipitate flocs generated by the reaction are loose and have poor settling performance. They easily form stable colloids that are suspended in the solution, making solid-liquid separation difficult. In addition, the flocs have a strong carrying capacity, which will cause a large loss of vanadium and make it difficult to achieve deep removal of silicon.

[0006] Patent CN114477285B discloses a method for removing silicon impurities from vanadium products by introducing a reducing agent to reduce hexavalent chromium to trivalent chromium under acidic conditions, followed by the addition of ammonium salt to precipitate ammonium chromium polyvanadate, leaving silicon impurities in the solution. However, this method is only applicable to acidic vanadium solutions containing chromium and is completely unsuitable for alkaline vanadium-containing leachates obtained by sodium roasting-water leaching processes, exhibiting strong exclusivity in its application scenarios. The core of this method is to achieve vanadium-silicon separation through vanadium precipitation, rather than directly removing silicon impurities. To achieve complete vanadium precipitation, excessive ammonium salts are required, resulting in high reagent costs and significantly exceeding ammonia nitrogen levels in wastewater, placing immense pressure on environmental treatment. The precipitated product is an ammonium chromium polyvanadate complex, not a single vanadium compound, requiring multiple complex dissolution, separation, and purification steps to obtain high-purity vanadium oxide products. This significantly extends the process flow, resulting in extremely low production efficiency. Furthermore, secondary vanadium loss is highly likely during separation, making it difficult to guarantee the overall recovery rate and failing to meet the industrial demand for large-scale production of high-purity vanadium products.

[0007] Patent CN117987643A discloses a desilication method for alkaline vanadium solution, which involves mixing alkaline vanadium solution and aluminate solution to obtain a mixed solution, neutralizing with sulfuric acid, controlling specific reaction conditions, and synthesizing γ-AlOOH in situ to synergistically adsorb silicon, thereby achieving deep desilication. This method requires precise control of multiple parameters, including the neutralization reaction rate, system pH, and reaction temperature, to achieve controllable in-situ synthesis of γ-AlOOH. The process parameter control window is extremely narrow, and the requirements for the level of automation control in the production process are extremely high. In large-scale production, problems such as uneven product phase and fluctuations in adsorption performance are prone to occur, making it impossible to stably achieve deep removal of silicon. The in-situ synthesized γ-AlOOH is a nanoscale flocculent with a large specific surface area. While adsorbing and desiliconizing, it also adsorbs a large number of vanadate ions in the solution, causing significant loss of vanadium. This method requires the addition of a large amount of aluminate as an aluminum source. After the reaction, the excess aluminum ions are prone to forming soluble aluminate residues in the alkaline system, introducing new aluminum impurities. It is impossible to achieve both deep removal of silicon and effective control of aluminum residues, ultimately affecting the purity of the subsequent high-purity vanadium oxide product.

[0008] Patent CN118600241A discloses a method for producing high-quality vanadium liquor from high-chromium vanadium slag. The method involves using an aluminum salt solution for silicon removal followed by filtration. A polymeric flocculant is added to the filtrate to further separate suspended solid particles, followed by clarification to obtain high-quality vanadium liquor. However, this method fails to overcome the core contradiction between aluminum salt dosage and desilication effectiveness. Insufficient aluminum salt dosage results in incomplete silicate precipitation, limiting the desilication depth and failing to meet the stringent purity requirements of high-end applications. Conversely, excessive aluminum salt dosage leads to the formation of soluble aluminates in the alkaline system, introducing new aluminum impurities and reducing vanadium product purity. Furthermore, this method only removes suspended silica flocs through flocculation and sedimentation, failing to effectively remove dissolved polysilicates, resulting in insufficient desilication depth. The added polymeric flocculant leaves residues in the vanadium liquor, which can easily enter the vanadium product during subsequent precipitation, affecting the purity and physicochemical properties of the vanadium oxide product and increasing the difficulty of treating the vanadium mother liquor.

[0009] Therefore, in the aluminum salt desiliconization process, ensuring the deep removal of silicon impurities from the vanadium-containing leachate and preventing the introduction of aluminum has become a technical challenge for the subsequent preparation of high-purity vanadium oxide. Summary of the Invention

[0010] To address the aforementioned shortcomings, this application provides a silicon remover and its application in alkaline vanadium-containing leaching solutions, thereby resolving a series of technical problems in the existing alkaline vanadium-containing leaching process, such as the inability to simultaneously achieve deep removal of silicon impurities and effective control of aluminum residues, insufficient aluminum salt addition resulting in incomplete removal of silicate precipitation and insufficient desilication depth to meet the requirements for high-purity vanadium product preparation, and excessive addition leading to the formation of soluble aluminates by excess aluminum ions and the introduction of new impurities.

[0011] In a first aspect, this application provides a silicon remover, which is obtained through the following steps:

[0012] Using aluminum-containing desiliconizing slag as raw material, it is added to NaOH solution, stirred continuously, filtered and the solid is collected, dried and ground to obtain the desiliconizing agent;

[0013] The NaOH solution has a pH of 8.0 to 10.0; it also contains cationic polyacrylamide at a concentration of 0.1 to 0.3 mg / ml; the stirring temperature is 80 to 95 °C, and the mixture is kept at this temperature for 60 to 120 minutes.

[0014] Preferably, the drying temperature is 100~120°C.

[0015] Preferably, the particle size of the solid after grinding is ≤0.125 μm.

[0016] Preferably, the aluminum-containing desiliconizing slag is obtained through the following steps:

[0017] Using alkaline vanadium-containing leachate as raw material, aluminum salts are added and the precipitate is collected to obtain the aluminum-containing desiliconized slag.

[0018] The aluminum salt is selected from aluminum sulfate or sodium aluminate; the alkaline vanadium-containing leaching solution contains Si element, and the amount of aluminum salt added is calculated according to the molar ratio of Al element to Si element of (0.05~0.1):1.

[0019] Preferably, the alkaline vanadium-containing leachate is derived from the sodium roasting-water leaching process of vanadium-containing raw materials.

[0020] Secondly, this application provides an application of a silicon remover, which is used to remove Si element from vanadium-containing leachate.

[0021] Preferably, the specific steps are as follows:

[0022] Step 1: Add the silicon remover to the alkaline vanadium-containing solution and stir continuously to ensure that the silicon remover is fully dispersed in the solution;

[0023] For each 100 mL of alkaline vanadium-containing solution, add 0.5~1.0 g of silicon remover;

[0024] Step 2: Add aluminum salt to the mixture obtained in Step 1. After the aluminum salt dissolves, adjust the pH of the solution.

[0025] The aluminum salt is selected from aluminum sulfate or sodium aluminate; the alkaline vanadium-containing leaching solution contains Si element, and the amount of aluminum salt added is calculated according to the molar ratio of Al element to Si element of (0.05~0.1):1; the pH value is adjusted to 8.0~10.5;

[0026] Step 3: Heat the mixture obtained in Step 2 to 50~90 °C, stir continuously and react for 15~60 min;

[0027] Step 4: After the product from the reaction in Step 3 has been allowed to stand, it is filtered to obtain purified vanadium solution and aluminum-containing desiliconizing slag. The purified vanadium solution is used to prepare vanadium-containing products, and the aluminum-containing desiliconizing slag is used to prepare the desiliconizing agent.

[0028] Preferably, in step 1, the stirring speed is 350~500 r / min.

[0029] Preferably, in step 2, H2SO4 or NaOH is used to adjust the pH value.

[0030] Preferably, in step 2, the stirring speed is 150~250 r / min.

[0031] Preferably, in step 4, the mixture is left to stand for 4 to 24 hours.

[0032] Compared with the prior art, this application has the following beneficial effects:

[0033] 1. The silicon removal agent preparation process described in this application is short and simple, requiring only leaching with a weakly alkaline solvent, heating and stirring, filtration and drying, and grinding and fractionation. The reaction conditions are mild, requiring no high-temperature and high-pressure environment or complex synthesis equipment. It can be directly integrated with existing hydrometallurgical production line facilities, facilitating large-scale and continuous industrial preparation. Furthermore, the porous sodium aluminum silicate material prepared in this application has a controllable particle size of ≤0.125 μm, possessing both abundant porous structure and numerous surface-active hydroxyl sites. It exhibits dual functions of desilication reactivity and flocculation sedimentation. It can directly remove silicon impurities through complexation and adsorption reactions between surface-active sites and silicate ions in solution, and can also act as floc nuclei to provide heterogeneous nucleation sites for newly generated desilication precipitates, enhancing floc aggregation and sedimentation. This overcomes the limitations of traditional single-function desilication agents. Furthermore, the desiliconizing slag generated after the desiliconizing agent participates in the reaction can be directly returned to the preparation process as raw material for recycling, forming a closed-loop recycling system. During the recycling process, the core function shows no significant attenuation, no secondary solid waste is generated, and the preparation process uses only a weakly alkaline sodium hydroxide solution and trace amounts of cationic polyacrylamide, without introducing toxic or harmful reagents, and without the emission of high-risk byproducts or pollutants, making the production process green and safe. The core raw material of the desiliconizing agent described in this application comes from the aluminum-containing desiliconizing slag generated during the aluminum salt desiliconization process in vanadium hydrometallurgy. It is also compatible with sodium silicon slag solid waste from the Bayer process aluminum extraction industry. This transforms industrial solid waste that would otherwise require stockpiling and disposal into high-value-added desiliconizing functional materials, achieving the reduction, harmlessness, and high-value utilization of industrial solid waste, while significantly reducing the raw material cost of the desiliconizing agent.

[0034] 2. When the silicon removal agent described in this application is applied to the desilication process of alkaline vanadium-containing leaching solution, it can form a synergistic effect with trace aluminum salts, breaking through the efficiency bottleneck of traditional desilication processes. Under optimized process conditions, the silicon removal rate can reach over 99%, reducing the silicon content in the leaching solution to below 0.01 g / L, with a minimum of 0.002 g / L. This completely solves the negative impact of silicon impurities on the performance of subsequent vanadium products, fully meeting the stringent requirements for raw material purity in high-end fields such as vanadium redox flow battery electrolytes, aerospace high-purity vanadium-titanium alloys, and pharmaceutical-grade vanadium compounds. This provides core technological support for the extension of the vanadium industry to the high-end value chain. This application system, through the enhanced desilication effect of the desiliconizing agent, can significantly reduce the amount of aluminum salt added to n(Al) / n(Si) = 0.05~0.10, which is only about 1 / 10 of the amount used in traditional processes in the existing technology. It avoids the problem of soluble aluminate residue caused by excessive aluminum salt from the source. Actual verification shows that the aluminum content in the purified vanadium solution can be lower than 0.001 g / L. It completely solves the core technical problem of traditional aluminum salt desilication: "insufficient addition leads to incomplete desilication, while excessive addition introduces aluminum residue." While achieving deep silicon removal, it completely eliminates the secondary introduction of aluminum impurities, ensuring the stability of the subsequent preparation of high-purity vanadium products. Meanwhile, this system adopts a synergistic desilication mode of "silicon removal agent + trace aluminum salt", avoiding vanadium co-precipitation loss caused by high-dose precipitants in traditional processes. The dense, large-particle flocs formed by the silicon removal agent can also significantly reduce the adsorption and entrainment of vanadium in the precipitation. The vanadium loss rate can be stably controlled within 2%, with a minimum of 1.41%, which is significantly better than the traditional aluminum salt desilication process. This effectively reduces vanadium resource loss and improves the overall vanadium recovery rate and production economic benefits. In addition, the flocculation function of this silicon removal agent can promote the formation of larger and denser flocs in the desilication precipitation, solving the problems of fine particle precipitation suspension, slow sedimentation, and difficult filtration in traditional processes. This significantly improves the solid-liquid separation efficiency. Moreover, the desilication reaction has a wide pH range and a wide temperature range, requiring no strict parameter control. It can be directly connected to existing sodium-based vanadium extraction industrial production lines without the need for additional complex equipment. The process adaptability and operational stability are strong. At the same time, the entire process forms a closed-loop solid waste recycling system with no additional hazardous waste disposal costs. It has both economic and environmental advantages, low difficulty in industrialization, strong replicability, and extremely high industrial promotion value. Detailed Implementation

[0035] This application will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with specific examples. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0036] Unless otherwise specified in the specific circumstances, the numerical ranges listed herein include upper and lower limits, as well as all integers and fractions within that range, but are not limited to the specific values ​​listed when the range is defined.

[0037] I. A silicon remover

[0038] In the desilication stage of alkaline vanadium-containing leaching solution in the sodium-based vanadium extraction process, the existing mainstream aluminum salt chemical precipitation method has a series of core technical problems that cannot be addressed simultaneously. On the one hand, there is a rigid contradiction between the amount of aluminum salt added and the desilication effect. When the amount added is insufficient, the silicate precipitate is not completely removed, which cannot meet the stringent limit requirements for silicon impurities in high-end vanadium products. When the amount added is excessive, it will introduce secondary impurities of soluble aluminate, making it difficult to achieve both deep desilication and no impurity introduction. On the other hand, the addition of high doses of aluminum salt can easily cause vanadium co-precipitation and adsorption entrainment, resulting in a high vanadium loss rate. At the same time, the fine particulate precipitate generated by the desilication reaction has problems such as slow settling speed and low solid-liquid separation efficiency, resulting in poor process operation stability. In addition, the aluminum-containing desilication slag generated by the desilication reaction is mostly disposed of as industrial solid waste, which brings heavy environmental pressure and cannot achieve resource utilization, further increasing the process operating cost.

[0039] To address the aforementioned technical challenges, this application departs from the traditional approach of simply adjusting aluminum salt dosage to optimize desilication. Firstly, from the perspective of high-value recycling of industrial solid waste, it utilizes desilication slag, originally intended for solid waste disposal, as a core raw material, exploring its potential desilication and flocculation functions. Secondly, from the perspective of optimizing the precipitation reaction mechanism, it modifies and activates the desilication slag to impart a rich porous structure and active sites, enabling it to provide heterogeneous nucleation sites for desilication precipitation and reduce reaction supersaturation. Simultaneously, it enhances the complexation and adsorption of silicate ions through surface-active hydroxyl groups, thereby reducing dependence on aluminum salt dosage. Thirdly, from the perspective of vanadium loss control, it optimizes the floc structure to reduce vanadium adsorption, entrainment, and co-precipitation. Furthermore, it constructs a closed-loop recycling system to achieve full reuse of solid waste, ultimately forming a technical path that is both environmentally friendly and economical. Based on the above-mentioned solutions, this application presents a complete technical processing scheme, designing a novel desiliconizing agent. First, using the aluminum-containing desiliconizing slag produced from the desiliconization of aluminum salts in an alkaline vanadium-containing leaching solution as raw material, the agent is activated by heating in a weakly alkaline system containing additives, then filtered, dried, and ultrafine ground to prepare a porous sodium aluminum silicate desiliconizing agent possessing both desiliconization activity and flocculation function. The desiliconizing agent is obtained through the following steps:

[0040] Using aluminum-containing desiliconizing slag as raw material, it is added to NaOH solution, stirred continuously, filtered and the solid is collected, dried and ground to obtain the desiliconizing agent; wherein, the pH value of NaOH solution is 8.0~10.0; the NaOH solution also contains cationic polyacrylamide, the concentration of cationic polyacrylamide is 0.1~0.3 mg / ml; the stirring temperature is 80~95 °C, and the temperature is maintained at this temperature for 60~120 min.

[0041] The silicon-removing agent described in this application has achieved unexpected technical results after practical application: Firstly, it completely solves the core contradiction of traditional aluminum salt desilication, achieving over 99% ultra-deep desilication while reducing the aluminum salt dosage to 1 / 10 of the traditional process. It can even reduce the silicon content in the leachate to below 0.01 g / L, and the aluminum content in the purified solution is below 0.001 g / L. The desiliconizing agent achieves a vanadium loss rate of g / L with no secondary aluminum impurities introduced, achieving the dual goals of ultra-deep desiliconization and high purity. Secondly, while achieving ultra-deep desiliconization, the vanadium loss rate can be stably controlled within 2%, with a minimum of 1.41%, significantly lower than the traditional aluminum salt desiliconization process, breaking the inherent defect that deep desiliconization is inevitably accompanied by high vanadium loss. Thirdly, it realizes the full closed-loop recycling and reuse of desiliconizing slag, with no secondary solid waste generated. This not only completely solves the environmental problem of desiliconizing slag storage but also significantly reduces the raw material and addition costs of desiliconizing agents. At the same time, the core function of the desiliconizing agent does not significantly decrease during the recycling process, achieving simultaneous improvement in environmental and economic benefits. Fourthly, the flocculation function of the desiliconizing agent can promote the precipitation to form dense large-particle flocs, greatly improving the sedimentation and solid-liquid separation efficiency. Meanwhile, the desiliconization reaction can maintain stable and excellent results within a wide pH and temperature range, without the need for stringent process control conditions. It can be directly connected to existing industrial production lines, and its industrial adaptability far exceeds that of traditional processes.

[0042] In some embodiments of this application, the pH value of the NaOH solution is 8.0~10.0. The NaOH solution within a specific pH range is the core activating solvent for aluminum-containing desiliconization slag. The weakly alkaline environment is used to gently etch and loosen the bulk structure of the aluminum-containing desiliconization slag (hydrated sodium aluminosilicate), dissolve amorphous impurities in the slag phase, open up internal closed channels, and simultaneously regulate the number and distribution of hydroxyl sites on the surface of sodium aluminosilicate. Without destroying the main crystal structure, the material is endowed with a rich porous structure and higher desiliconization reactivity, providing sufficient heterogeneous nucleation sites and silicate adsorption sites for subsequent desiliconization reactions. At the same time, the weakly alkaline environment can form a synergistic effect with cationic polyacrylamide, ensuring the dispersion stability and modification effect of the flocculant. If the pH of the NaOH solution is too high (>10.0), it will create a strongly alkaline over-etching environment, dissolving and destroying the main framework structure of sodium aluminum silicate, leading to the collapse of the porous structure and a large loss of active sites. It will also cause the cationic polyacrylamide to hydrolyze and become ineffective, and increase the cost of subsequent washing and neutralization agents. If the pH is too low (<8.0), the weakly alkaline activation ability is insufficient, making it impossible to effectively etch and modify the aluminum-containing desiliconizing slag. It is difficult to open the internal channels and fully expose the active sites, resulting in a desiliconizing agent with high density and poor porosity. This significantly reduces the synergistic desiliconization effect, failing to achieve the core goal of reducing aluminum salt usage and achieving deep desiliconization. Therefore, it can further be 8.0, 9.0, 10.0, etc., as well as all ranges and sub-ranges between the above values. It should be understood that, in the implementation scheme, any of the above ranges can be combined with any other range.

[0043] In some embodiments of this application, the NaOH solution also contains cationic polyacrylamide at a concentration of 0.1-0.3 mg / ml. As a modifier and dispersant, the cationic polyacrylamide can, on the one hand, form adsorption bridges with the negative potential points on the surface of sodium aluminum silicate particles through its cationic groups, inhibiting particle agglomeration and growth during heating and stirring, ensuring that alkaline etching can act uniformly on each particle, and achieving uniformity of modification effect; on the other hand, it can also modify the surface of the desiliconizing agent, giving it stronger flocculation and bridging capabilities, synergistically enhancing floc agglomeration and sedimentation in subsequent desiliconization applications, and improving solid-liquid separation efficiency; simultaneously, trace amounts of the additive can optimize the pore structure of the desiliconizing agent, preventing pore collapse during etching and ensuring the stability of the porous structure. If the concentration of cationic polyacrylamide is too high (>0.3 mg / ml), the excessive additive will form a thick organic coating on the surface of sodium aluminum silicate particles, completely shielding the active hydroxyl sites and porous channel entrances on the particle surface. This leads to a significant loss of the desilication activity of the desiliconizing agent, and also causes excessive system viscosity, severe particle agglomeration, and the introduction of organic impurities in subsequent applications, contaminating the alkaline vanadium-containing leachate. If the concentration is too low (<0.1 mg / ml), it cannot form effective adsorption bridging and dispersion protection, and the particles are prone to severe agglomeration during activation, resulting in uneven modification effects, insufficient exposure of active sites, and failure to effectively optimize the flocculation performance of the desiliconizing agent, making it difficult to solve the problems of fine particle precipitation, suspension, and slow sedimentation in traditional processes. Therefore, it can further be 0.1 mg / ml, 0.2 mg / ml, 0.3 mg / ml, etc., as well as all ranges and sub-ranges between the above values. It should be understood that, in the implementation scheme, any of the above ranges can be combined with any other range.

[0044] In some embodiments of this application, the stirring temperature is 80~95 °C. The heating temperature is the thermodynamic condition for the efficient activation and modification of aluminum-containing desiliconizing slag. It can provide sufficient activation energy for the mild etching reaction of sodium aluminum silicate by NaOH, accelerate the etching reaction rate, promote the opening of internal closed channels and the generation of surface active hydroxyl sites, and significantly shorten the activation and modification cycle. At the same time, the suitable temperature can promote the uniform adsorption and modification of cationic polyacrylamide on the particle surface, ensure the dispersion and flocculation modification effect, maintain a uniform mass transfer environment of the system, avoid insufficient local modification, and ensure the uniform and stable performance of the desiliconizing agent prepared in batches. If the heating temperature is too high (>95 °C), the system will boil violently, and the rapid evaporation of the solution will cause drastic fluctuations in the concentration of NaOH and additives. The modification reaction environment will become uncontrolled, resulting in problems such as local over-etching or insufficient modification. At the same time, it will exacerbate the thermal agglomeration of particles, accelerate the thermal degradation and failure of cationic polyacrylamide, and increase production energy consumption and safety management risks. If the temperature is too low (<80 °C), it cannot provide sufficient activation energy for the etching reaction, the modification reaction rate will be extremely slow, and effective activation cannot be completed within the set time. The active sites of the desiliconizing agent will not be exposed enough, and the adsorption modification efficiency of the additives will decrease significantly. The mass transfer efficiency of the system will deteriorate, and the performance of the desiliconizing agent prepared in batches will fluctuate greatly, making it impossible to guarantee the stability of the subsequent desiliconization application effect. Therefore, the temperature can be further set to 80 °C, 85 °C, 90 °C, 95 °C, etc., as well as all ranges and sub-ranges between the above values. Maintaining this temperature range for 60–120 min ensures the activation and modification reaction proceeds sufficiently, providing ample reaction time for the gentle etching of NaOH and the adsorption modification of cationic polyacrylamide. This ensures the etching reaction is uniform and complete, fully opening the internal closed channels, maximizing the exposure of surface active hydroxyl sites, and simultaneously allowing the additives to be uniformly adsorbed onto the particle surface. This completes the modification and optimization of the flocculation performance of the desiliconizing agent, ensuring that the performance of the desiliconizing agent meets the standards while also considering production efficiency. If the holding time is too long (>120 min), the alkaline etching reaction will be excessive, damaging the main framework structure of sodium aluminum silicate, causing the collapse of the formed porous structure and loss of active sites. It will also exacerbate the hydrolysis and degradation of the additives, significantly prolong the production cycle, increase energy consumption, and drive up industrial production costs. If the holding time is too short (<60 min), the activation and modification reaction cannot proceed fully, the etching effect can only act on the surface of the particles, and it cannot open up the internal pores. The exposure of active sites is severely insufficient, and the desilication activity and flocculation performance of the desiliconizing agent cannot meet the design requirements. Furthermore, incomplete modification reaction will lead to poor consistency in the performance of the desiliconizing agent, resulting in large fluctuations in subsequent desiliconization applications and an inability to stably achieve the goals of deep desiliconization and low vanadium loss. Therefore, it can further be 60 min, 90 min, 120 min, etc., as well as all ranges and sub-ranges between the above values; it should be understood that in the implementation plan, any of the above ranges can be combined with any other range.

[0045] In some embodiments of this application, the particle size of the ground solid is ≤0.125 μm. By controlling the upper limit of the particle size of the desiliconizing agent through ultrafine grinding, the specific surface area of ​​the desiliconizing agent can be maximized, fully exposing the surface active hydroxyl sites and porous channels, significantly increasing the contact area between the desiliconizing agent and the alkaline vanadium-containing leachate, strengthening the adsorption and complexation of silicate ions, and providing more heterogeneous nucleation sites for desiliconization precipitation; the uniform ultrafine particle size can ensure that the desiliconizing agent is rapidly and uniformly dispersed in the leachate, avoiding the problem of uneven action caused by the sedimentation of large particles, and at the same time, it can better exert the role of floc nuclei, promote the agglomeration and growth of desiliconization precipitates, form denser flocs, and significantly improve sedimentation and solid-liquid separation efficiency. If the solid particles after grinding are too large (>0.125 μm), the specific surface area of ​​the desiliconizing agent will decrease significantly, the exposure of active sites will be significantly reduced, the contact area with the leachate will be insufficient, and the synergistic desiliconization effect will be significantly weakened. At the same time, large particles have poor dispersibility in the leachate and are prone to rapid sedimentation, resulting in uneven desiliconization effect and failing to effectively exert the role of flocculent nuclei, making it difficult to solve the problem of fine particle precipitation and suspension. If the solid particles after grinding are too small (reaching the nanoscale, <50 nm), the surface energy of the particles will be too high, and they are prone to severe agglomeration during preparation and storage, thus losing the activity advantage brought by ultrafine particle size. At the same time, excessively fine particles are easy to penetrate the filter and clog the filter cloth, significantly reducing the filtration efficiency. It will also significantly increase the energy consumption and wear of the grinding equipment, increase the preparation cost, and is not conducive to large-scale industrial production.

[0046] In some embodiments of this application, the aluminum-containing desiliconizing slag is obtained through the following steps:

[0047] Using alkaline vanadium-containing leachate as raw material, aluminum salts are added and the precipitate is collected to obtain the aluminum-containing desiliconized slag.

[0048] The aluminum salt is selected from aluminum sulfate or sodium aluminate. The alkaline vanadium-containing leachate contains Si, and the amount of aluminum salt added is calculated according to the molar ratio of Al to Si of (0.05~0.1):1. The alkaline vanadium-containing leachate is derived from the sodium roasting-water leaching process of vanadium-containing raw materials, where c(V) is typically 20~60 g / L and c(Si) is 0.3~3.0 g / L. By precisely controlling the amount of aluminum salt added, the aluminum salt reacts directionally with the silicate ions in the alkaline vanadium-containing leachate to generate hydrated sodium aluminosilicate precipitate. This provides a stable and sufficiently active aluminum-containing desiliconizing slag raw material for the subsequent preparation of the desiliconizing agent, and also achieves the initial removal of silicon impurities in the leachate with a low amount of aluminum salt added, while avoiding aluminum residue and vanadium loss caused by excessive aluminum salt. Precise control of the aluminum-silicon ratio ensures that the generated hydrated sodium aluminosilicate has a suitable crystal form and structure, providing a high-quality raw material basis for subsequent activation and modification, balancing the desiliconization effect and production cost. If too much aluminum salt is added (Al / Si molar ratio > 0.1), excessive aluminum ions will remain in the leachate, introducing secondary aluminum impurities that contaminate the vanadium solution. Simultaneously, excessive aluminum salt will generate a large amount of amorphous aluminum hydroxide flocs, adsorbing and carrying a significant amount of vanadium components, resulting in a substantial increase in vanadium loss. It will also lead to excessively high aluminum hydroxide impurity content in the aluminum-containing desiliconization slag, making the raw material composition unstable and preventing the subsequent preparation of a qualified desiliconizing agent, while significantly increasing reagent procurement costs. If too little aluminum salt is added (Al / Si molar ratio < 0.05), the aluminum ions will not react sufficiently with silicate ions, failing to generate a sufficient amount of hydrated sodium aluminosilicate precipitate. On the one hand, the output of aluminum-containing desiliconization slag will be insufficient, failing to provide enough raw materials for desiliconizing agent preparation, making it difficult to achieve closed-loop preparation of the desiliconizing agent. On the other hand, silicon impurities in the leachate cannot be effectively removed initially, increasing the load on subsequent deep desiliconization processes. Furthermore, the generated hydrated sodium aluminosilicate precipitate has incomplete crystal structure and insufficient activity, preventing the desiliconizing agent prepared from it from achieving its designed performance, and significantly reducing the synergistic desiliconization effect. Therefore, the molar ratio of Al to Si can be 0.05:1, 0.08:1, 0.1:1, etc., as well as all ranges and subranges between the above values; it should be understood that, in the implementation scheme, any of the above ranges can be combined with any other range.

[0049] II. Application of a Silicone Removing Agent

[0050] This application constructs a desilication process based on the aforementioned desilication agent, consisting of "desilication agent pre-slurrying and dispersion + trace aluminum salt synergistic reaction." First, the prepared desilication agent is added to an alkaline vanadium-containing leaching solution and dispersed at high speed. Then, a low dose of aluminum salt is added, and the pH value, reaction temperature, and stirring conditions are controlled to complete the desilication reaction. Finally, the desilication slag generated after the reaction is directly returned to the desilication agent preparation process, forming a closed-loop cycle process of desilication slag-desilication agent-desilication reaction-desilication slag. The aforementioned desilication agent is used to remove Si element from vanadium-containing leaching solution, and the specific steps are as follows:

[0051] Step 1: Add the silicon remover to the alkaline vanadium-containing solution and stir continuously to ensure that the silicon remover is fully dispersed in the solution;

[0052] For each 100 mL of alkaline vanadium-containing solution, add 0.5~1.0 g of silicon remover;

[0053] Step 2: Add aluminum salt to the mixture obtained in Step 1. After the aluminum salt dissolves, adjust the pH of the solution.

[0054] The aluminum salt is selected from aluminum sulfate or sodium aluminate; the alkaline vanadium-containing leaching solution contains Si element, and the amount of aluminum salt added is calculated according to the molar ratio of Al element to Si element of (0.05~0.1):1; the pH value is adjusted to 8.0~10.5;

[0055] Step 3: Heat the mixture obtained in Step 2 to 50~90°C, stir continuously and react for 15~60 min;

[0056] Step 4: After the product from the reaction in Step 3 has been allowed to stand, it is filtered to obtain purified vanadium solution and aluminum-containing desiliconizing slag. The purified vanadium solution is used to prepare vanadium-containing products, and the aluminum-containing desiliconizing slag is used to prepare the desiliconizing agent.

[0057] In some embodiments of this application, in step 1, the stirring speed is 350~500 r / min.

[0058] In some embodiments of this application, in step 2, H2SO4 or NaOH is used to adjust the pH value.

[0059] In some embodiments of this application, in step 1, the stirring speed is 150~250 r / min.

[0060] In some embodiments of this application, in step 4, the plant is left to stand for 4 to 24 hours.

[0061] III. Examples and Comparative Examples

[0062] The alkaline vanadium-containing leachate used in the following examples and comparative examples has the following composition:

[0063] Table 1. Composition of alkaline vanadium-containing leachate (g / L)

[0064]

[0065] 1. Preparation of silicon remover

[0066] Example 1

[0067] Using aluminum-containing desiliconizing slag as raw material, a sodium hydroxide solution with a pH of 9.0 was added, which contained 0.02% cationic polyacrylamide (i.e., 0.02 g per 100 mL of solution); the mixture was stirred and heated at 90°C for 100 min; after filtration, it was dried at 110°C and then ground to a particle size ≤0.125 μm (all particles reaching below 0.125 μm) to obtain a porous desiliconizing agent for later use.

[0068] Example 2

[0069] Using aluminum-containing desiliconizing slag as raw material, a sodium hydroxide solution with a pH of 8.0 was added, which contained 0.01% cationic polyacrylamide (i.e., 0.01 g per 100 mL of solution); the mixture was stirred and heated at 80°C for 60 min; after filtration, it was dried at 100°C and then ground to a particle size ≤0.125 μm (all particles reaching below 0.125 μm) to obtain a porous desiliconizing agent for later use.

[0070] Example 3

[0071] Using aluminum-containing desiliconizing slag as raw material, a sodium hydroxide solution with a pH of 10.0 was added, which contained 0.03% cationic polyacrylamide (i.e., 0.03 g per 100 mL of solution); the mixture was stirred and heated at 95°C for 120 min; after filtration, it was dried at 120°C and then ground to a particle size ≤0.125 μm (all particles reaching below 0.125 μm) to obtain a porous desiliconizing agent for later use.

[0072] 2. Application of silicon remover

[0073] Example 4

[0074] 800 mL of alkaline vanadium solution (pH 10.08) from Table 1 was measured, and 4.0 g of the porous silica remover prepared in Example 1 was added. The mixture was then dispersed by slurry mixing at 400 r / min. 1.01 g of aluminum sulfate with n(Al) / n(Si) = 0.1 was added, and sulfuric acid was added to maintain the pH of the reaction system at approximately 9.0. The mixture was stirred in a 70°C water bath for 30 min at a stirring speed of 200 r / min. After the reaction was complete, the slurry was allowed to settle for 12 h, then filtered and washed to obtain 880 mL of purified vanadium solution. The purified solution contained 0.002 g / L of Si, less than 0.001 g / L of Al, and 30.08 g / L of V. The Si removal rate was 99.79%, and the V loss was 1.41%.

[0075] Example 5

[0076] Measure 2000 mL of the alkaline vanadium solution (pH 10.08) from Table 1, add 20.0 g of the porous silica remover prepared in Example 2, and disperse by slurrying at 500 r / min; add 1.26 g of aluminum sulfate with n(Al) / n(Si) = 0.05, add sulfuric acid to maintain the pH of the reaction system to approximately 8.0, and stir the reaction in a 90°C water bath for 60 min at a stirring speed of 250 r / min; after the reaction is complete, allow the slurry to settle for 24 h, then filter and wash to obtain 2160 mL of purified vanadium solution. The purified solution has a Si content of 0.003 g / L, an Al content of less than 0.001 g / L, and a V content of 30.52 g / L, with a Si removal rate of 99.69% and a V loss of 1.78%.

[0077] Example 6

[0078] Measure 200 mL of the alkaline vanadium solution (pH 10.08) from Table 1, add 1.6 g of the porous silica remover prepared in Example 3, and disperse by slurrying at 350 r / min; add 0.12 g of aluminum sulfate with n(Al) / n(Si) = 0.06, and add sodium hydroxide to maintain the pH of the reaction system at approximately 10.5. Stir the reaction in a 50°C water bath for 15 min at a stirring speed of 150 r / min. After the reaction is complete, allow the slurry to settle for 4 h, then filter and wash to obtain 235 mL of purified vanadium solution. The purified solution has a Si content of 0.002 g / L, an Al content of less than 0.001 g / L, and a V content of 28.15 g / L, with a Si removal rate of 99.78% and a V loss of 1.44%.

[0079] Comparative Example 1

[0080] Measure 500 mL of the alkaline vanadium solution (pH 10.08) from Table 1, add 5.04 g of aluminum sulfate with n(Al) / n(Si) = 0.8, and add sulfuric acid to maintain the pH of the reaction system at approximately 9.0. Stir the reaction in a 70°C water bath for 30 min. After the reaction is complete, filter and wash the slurry to obtain 510 mL of purified vanadium solution. The purified solution contains 0.003 g / L Si, 0.038 g / L Al, and 32.06 g / L V, with a Si removal rate of 99.71% and a V loss of 2.56%.

[0081] Comparative Example 1 used a higher amount of aluminum sulfate and carried out a desilication reaction at a suitable pH value. Silicon was removed in depth, but aluminum impurities were introduced.

[0082] Comparative Example 2

[0083] 500 mL of the alkaline vanadium solution (pH 10.08) from Table 1 was measured, and 3.78 g of aluminum sulfate with n(Al) / n(Si) = 0.6 was added. Sulfuric acid was added to maintain the pH of the reaction system at approximately 9.0. The reaction was stirred in a 70 °C water bath for 30 min. After the reaction was completed, the slurry was filtered and washed to obtain 510 mL of purified vanadium solution. The purified solution contained 0.029 g / L of Si, less than 0.001 g / L of Al, and 32.35 g / L of V. The Si removal rate was 97.21%, and the V loss was 1.68%.

[0084] Comparative Example 2 uses a lower amount of aluminum sulfate and carries out the desilication reaction at a suitable pH value. This does not introduce aluminum impurities, but silicon cannot be removed in depth.

[0085] As can be seen from the examples and comparative examples:

[0086] (1) Comparative Examples 1 and 2 simulated two typical application scenarios of existing conventional aluminum salt desilication processes, respectively, and directly exposed the core contradictions that existing technologies cannot reconcile: Comparative Example 1 used a high dose of aluminum sulfate (n(Al) / n(Si)=0.8) for desilication. Although it achieved a silicon removal rate of 99.71% and reduced the silicon content of the leaching solution to 0.003 g / L, achieving a deep desilication effect, the aluminum residue in the purified solution reached 0.038 g / L, introducing significant secondary aluminum impurities. At the same time, the vanadium loss rate was as high as 2.56%, resulting in serious vanadium resource depletion. Comparative Example 2 reduced the aluminum sulfate dosage to n(Al) / n(Si)=0.6. Although it achieved an aluminum content in the purified solution of less than 0.001 g / L, with no secondary aluminum impurities introduced and the vanadium loss rate reduced to 1.68%, the silicon removal rate was only 97.21%, and the silicon content in the purified solution reached 0.029 g / L. The concentration of g / L cannot meet the requirements for deep removal of silicon impurities in the preparation of high-end vanadium products. The two comparative examples clearly demonstrate that the existing conventional aluminum salt desiliconization process cannot simultaneously achieve the three core objectives of deep silicon removal, no secondary aluminum impurity introduction, and low vanadium loss rate, and there are intractable technical problems.

[0087] (2) Examples 1-3 demonstrated the controllable preparation of porous silicon removers under different process parameters. Examples 4-6 constructed a synergistic desilication system of low-dose aluminum salt + self-made silicon remover based on the above-mentioned self-made silicon remover, showing a significantly better application effect than the prior art: all examples used a much lower amount of aluminum sulfate added than the comparative example, with n(Al) / n(Si) being only 0.05-0.1, which is only 1 / 16 to 1 / 8 of the highest amount used in the comparative example. On this basis, all three examples achieved a silicon removal rate of over 99.69%, and the silicon content in the purified liquid was stably reduced to 0.002-0.003 g / L, achieving and surpassing the deep desilication effect of Comparative Example 1; at the same time, the aluminum content in the purified liquid was all below 0.001 g / L. g / L, achieving the same effect as Comparative Example 2 without the introduction of secondary aluminum impurities; the vanadium loss rate was stably controlled between 1.41% and 1.78%, all below 2%, which is not only significantly lower than the 2.56% of Comparative Example 1, but also better than the low vanadium loss level of Comparative Example 2 under optimal operating conditions; in addition, the three sets of examples maintained stable and excellent desilication effects within a wide parameter range of pH value 8.0~10.5, reaction temperature 50~90 °C, reaction time 15~60 min, and settling time 4~24 h. In particular, Example 6 only required 4 h of settling to achieve ultra-deep desilication, demonstrating excellent floc settling performance and solid-liquid separation efficiency.

[0088] (3) As can be seen, this application has completely solved the core contradiction of the existing aluminum salt desilication process. For the first time, it has simultaneously achieved the three core objectives of ultra-deep silicon removal, no secondary aluminum impurity introduction, and low vanadium loss rate under extremely low aluminum salt dosage. This breaks the inherent understanding of the existing technology that "deep desilication is inevitably accompanied by high aluminum salt dosage, high vanadium loss, or secondary impurity introduction." Secondly, it fully demonstrates that the porous desilication agent prepared by this application using aluminum-containing desilication slag as raw material has extremely strong synergistic desilication activity and flocculation function. It can provide heterogeneous nucleation sites for desilication precipitation, enhance the adsorption and removal of silicate, significantly reduce the amount of aluminum salt added, and promote the rapid sedimentation of flocs, thereby improving the solid-liquid separation efficiency. Furthermore, it verifies that the desilication agent prepared by this application has the following properties: The silicon process exhibits extremely wide adaptability to various operating conditions, maintaining stable and excellent performance under common industrial conditions with different pH levels, temperatures, and reaction durations. It requires no stringent parameter control and can be directly integrated with existing sodium-based vanadium extraction production lines, demonstrating strong industrial applicability. Furthermore, it proves that the process applied for can achieve ultra-deep desiliconization while further reducing vanadium resource loss and significantly improving the comprehensive utilization rate of vanadium resources, resulting in excellent economic benefits. It also verifies the feasibility of the technical route of preparing desiliconizing agents using desiliconization solid waste as raw material, realizing the high-value closed-loop recycling of industrial solid waste. While achieving application effects far exceeding those of existing processes, it solves the environmental problem of desiliconization slag storage, possessing both environmental and economic value.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of this application without departing from the spirit and scope of this technical solution should be covered within the scope of the claims of this application.

Claims

1. A silicon remover, characterized in that, The silicon remover is obtained through the following steps: Using aluminum-containing desiliconizing slag as raw material, it is added to NaOH solution, stirred continuously, filtered and the solid is collected, dried and ground to obtain the desiliconizing agent; The NaOH solution has a pH of 8.0 to 10.0; it also contains cationic polyacrylamide at a concentration of 0.1 to 0.3 mg / ml; the stirring temperature is 80 to 95 °C, and the mixture is kept at this temperature for 60 to 120 minutes.

2. The silicon remover according to claim 1, characterized in that, The drying temperature is 100~120 °C.

3. The silicon remover according to claim 1, characterized in that, The solid particle size after grinding is ≤0.125 μm.

4. The silicon remover according to claim 1, characterized in that, The aluminum-containing desiliconizing slag is obtained through the following steps: Using alkaline vanadium-containing leachate as raw material, aluminum salts are added and the precipitate is collected to obtain the aluminum-containing desiliconized slag. The aluminum salt is selected from aluminum sulfate or sodium aluminate; the alkaline vanadium-containing leaching solution contains Si element, and the amount of aluminum salt added is calculated according to the molar ratio of Al element to Si element of (0.05~0.1):

1.

5. The silicon remover according to claim 4, characterized in that, The alkaline vanadium-containing leachate is derived from the sodium roasting-water leaching process of vanadium-containing raw materials.

6. An application of a silicon remover, characterized in that, The silicon-removing agent according to any one of claims 1 to 5 is used to remove Si element from vanadium-containing leachate.

7. The application according to claim 6, characterized in that, The specific steps are as follows: Step 1: Add the silicon remover to the alkaline vanadium-containing solution and stir continuously to ensure that the silicon remover is fully dispersed in the solution; For each 100 mL of alkaline vanadium-containing solution, add 0.5~1.0 g of silicon remover; Step 2: Add aluminum salt to the mixture obtained in Step 1. After the aluminum salt dissolves, adjust the pH of the solution. The aluminum salt is selected from aluminum sulfate or sodium aluminate; the alkaline vanadium-containing leaching solution contains Si element, and the amount of aluminum salt added is calculated according to the molar ratio of Al element to Si element of (0.05~0.1):1; the pH value is adjusted to 8.0~10.5; Step 3: Heat the mixture obtained in Step 2 to 50~90 °C, stir continuously and react for 15~60 min; Step 4: After the product from the reaction in Step 3 has been allowed to stand, it is filtered to obtain purified vanadium solution and aluminum-containing desiliconizing slag. The purified vanadium solution is used to prepare vanadium-containing products, and the aluminum-containing desiliconizing slag is used to prepare the desiliconizing agent.

8. The application according to claim 7, characterized in that, In step 1, the stirring speed is 350~500 r / min.

9. The application according to claim 7, characterized in that, In step 2, the pH value is adjusted using H2SO4 or NaOH, and the stirring speed is 150~250 r / min.

10. The application according to claim 7, characterized in that, In step 4, let it stand for 4 to 24 hours.