Preparation method of low-silicon and low-iron vanadium pentoxide flake

Abstract

The present application relates to a kind of low-silicon low-iron flaky vanadium pentoxide preparation method, comprising: (1) after the pretreated vanadium-containing raw material is mixed with sodium salt, sodium calcination treatment is carried out, and calcined clinker is obtained;(2) the calcined clinker is treated with water leaching vanadium, and vanadium-containing crude liquid is obtained;(3) adding impurity-removing agent to the vanadium-containing crude liquid, and deep impurity-removing treatment is carried out, and purified vanadium liquid is obtained;The impurity-removing agent includes aluminum sulfate solution;The addition amount of the impurity-removing agent is 1.5-6% of the volume of the vanadium-containing crude liquid;(4) the purified vanadium liquid is sequentially treated with reduction and vanadium precipitation and calcination, and the low-silicon low-iron flaky vanadium pentoxide is obtained.The preparation method of the present application has the advantages of high impurity-removing efficiency, no impurity residue, strong process compatibility, controllable cost, and the vanadium recovery rate is ≥90%.

Description

Technical Field

[0001] This invention relates to the field of vanadium pentoxide production technology, and in particular to a method for preparing low-silicon, low-iron flake vanadium pentoxide. Background Technology

[0002] Vanadium pentoxide (V₂O₅) is a key basic raw material in fields such as iron and steel smelting, chemical catalysis, and new energy battery materials. Among them, flake-shaped vanadium pentoxide is particularly valuable due to its large specific surface area (≥1.2m²). 2 With its advantages such as high density, good fluidity (angle of repose ≤32°), and fast dissolution rate, it has become a core raw material for the production of high-end vanadium-aluminum alloys and precision catalysts, and its market demand has grown at an average annual rate of 8% to 10%.

[0003] Currently, the mainstream industrial process for producing flake vanadium pentoxide is the sodium roasting method. The technical principle is to react vanadium ore with sodium salts (sodium carbonate, sodium chloride, etc.) at high temperature to convert insoluble vanadium minerals into soluble sodium vanadate (NaVO3). Then, through water leaching, purification, vanadium precipitation, and calcination, flake products are prepared. The core process is as follows: vanadium ore crushing and screening → sodium batching → high-temperature roasting (850~950℃) → water leaching for vanadium extraction → vanadium liquor purification → ammonium salt precipitation of vanadium → calcination for flake production (550~650℃).

[0004] However, vanadium ore raw materials commonly contain associated siliceous minerals such as quartz (SiO2) and feldspar (KAlSi3O8) (typically 5%–12%), as well as iron-bearing minerals such as pyrite (FeS2) and hematite (Fe2O3) (typically 3%–8%). During sodium roasting, the siliceous minerals react with sodium salts to form soluble sodium silicate (Na2SiO3), while the iron-bearing minerals are oxidized to Fe. 3+ The oxides partially dissolve in the leaching solution, resulting in silicon and iron impurity concentrations in the vanadium solution reaching 0.5~1.2 g / L and 0.3~0.6 g / L, respectively. The presence of these impurities causes two major problems: first, it reduces product purity, affecting the compositional uniformity and catalytic activity of subsequent alloy smelting; second, it disrupts the lamellar crystal morphology, leading to product agglomeration and reduced fluidity, failing to meet the process requirements of high-end applications.

[0005] To address the aforementioned issues, the impurity removal technologies developed in the industry can be mainly categorized into three types:

[0006] 1) Calcium salt precipitation method: In the existing sodium roasting process for producing flake vanadium pentoxide, silicon (in the form of SiO3) is associated with vanadium ore. 2- Form), iron (in Fe) 3+(Form) Impurities enter the vanadium solution in large quantities after roasting and leaching. Traditional impurity removal methods (such as calcium salt precipitation and fluorosilicic acid complex precipitation) have significant drawbacks: calcium salts can only target desiliconization, the iron removal rate is less than 20%, and calcium vanadate precipitate is easily generated, which reduces the vanadium recovery rate by 3% to 5%. Excessive calcium salts can easily generate calcium vanadate precipitate, resulting in vanadium loss.

[0007] For example, CN120987362A discloses a method for preparing high-purity vanadium pentoxide, comprising: adding an impurity-removing agent to a vanadium phosphorus-containing solution for impurity removal, followed by solid-liquid separation to obtain a filtrate; subjecting the obtained filtrate to sequential pH adjustment, pH adjustment, ammonium salt precipitation of vanadium, dehydration, calcination to remove ammonia, and melting to obtain high-purity vanadium pentoxide; wherein the impurity-removing agent comprises: calcium salt and flocculant; the endpoint pH value of the first pH adjustment is 4.5-5.5; the endpoint pH value of the second pH adjustment is... 1.8-2.2; This method has a single target for impurity removal, effectively removing only silicon impurities (removal rate 65%~70%), and iron removal rate is only 10%~15%, with the final product still having an iron content ≥0.08%; High vanadium loss rate: Excess calcium salts easily form calcium vanadate precipitate, resulting in a vanadium recovery rate of only 85%~88%; Limited product purity: Silicon content remains at 0.10%~0.15%, which cannot meet the needs of high-end applications; Unresolved problem of impurity removal agent loss: The impurity removal agent addition stage is not optimized, and simultaneous deep removal of silicon and iron cannot be achieved.

[0008] 2) Complexation precipitation method: Add complexing agents such as fluorosilicic acid and fluoroboric acid to form complex precipitation with silicon and iron. Although fluorosilicic acid can remove some of the silicon and iron at the same time, the cost is 3 to 4 times that of aluminum sulfate, and the residual fluoride ions will corrode the equipment and contaminate the subsequent products.

[0009] 3) Aluminum salt impurity removal method: Some processes have attempted to remove impurities by adding aluminum salts such as aluminum sulfate and polyaluminum chloride during the sodium preparation or roasting stage. However, due to the high temperature environment, the aluminum salt decomposition loss rate reaches 25%~45%, and the impurity removal efficiency drops significantly. In addition, aluminum salt and sodium salt undergo side reactions, affecting the conversion of vanadium minerals to soluble sodium vanadate, resulting in vanadium conversion efficiency fluctuations of more than 5%, and thus failing to achieve industrial application.

[0010] Existing processes struggle to simultaneously achieve the three objectives of "deep removal of ferrosilicon," "no introduction of new impurities," and "stable and compatible processes." The resulting products typically have a silicon content ≥0.1% and an iron content ≥0.1%, failing to meet the demands for low-impurity vanadium flakes in high-end vanadium alloys and precision catalysts. Therefore, developing a method for preparing low-silicon, low-iron flake vanadium pentoxide that is "highly efficient in impurity removal, leaves no impurity residue, has strong process compatibility, and is cost-controllable" has become a pressing technical challenge for the industry. Summary of the Invention

[0011] To address the aforementioned technical problems, this invention provides a method for preparing low-silicon, low-iron flake vanadium pentoxide. This invention fundamentally avoids the high-temperature decomposition and loss of the impurity removal agent by adding it only during the impurity removal stage of the vanadium-containing crude liquor after water leaching, ensuring the purity of Al. 3+ It fully participates in the impurity removal reaction; without changing the core equipment (rotary kiln, leaching tank, melting furnace) and key parameters (roasting temperature, leaching liquid-solid ratio, calcination temperature) of the existing sodium roasting process, only a simple aluminum sulfate addition device needs to be added, reducing the difficulty and cost of industrialization transformation.

[0012] To achieve this objective, the present invention adopts the following technical solution:

[0013] In a first aspect, the present invention provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide, the method comprising:

[0014] (1) After mixing the pretreated vanadium-containing raw material with sodium salt, sodium roasting treatment is carried out to obtain roasted clinker;

[0015] (2) The roasted clinker is subjected to water leaching for vanadium extraction to obtain vanadium-containing crude liquid;

[0016] (3) Add a vanadium-containing crude liquid to perform deep impurity removal treatment to obtain purified vanadium liquid; the vanadium-containing crude liquid contains aluminum sulfate solution; the amount of vanadium-containing crude liquid added is 1.5-6% of the volume of the vanadium-containing crude liquid.

[0017] (4) The purified vanadium liquid is subjected to reduction precipitation and calcination treatment in sequence to obtain the low-silicon and low-iron flake vanadium pentoxide.

[0018] The preparation method of this invention involves adding aluminum sulfate solution only during the purification stage of the vanadium-containing crude liquor after water leaching extraction, utilizing the Al dissociation of aluminum sulfate in aqueous solution. 3+ SiO3 in vanadium solution 2- A chemical reaction occurs, forming a sparingly soluble aluminosilicate precipitate (Al2(SiO3)3・6H2O); simultaneously, Al 3+ Under specific pH conditions, hydrolysis produces aluminum hydroxide (Al(OH)3) colloid. This colloid has extremely strong adsorption properties and can adsorb Fe from vanadium solution. 3+ It adsorbs and forms Fe(OH)3・Al(OH)3 coprecipitate, and achieves simultaneous deep removal of silicon and iron impurities through precision filtration.

[0019] The key reaction equations are as follows:

[0020] 1) Dissociation reaction of aluminum sulfate: Al2(SO4)3 = 2Al 3+ +3SO4 2− ;

[0021] 2) Silicon ion precipitation reaction: 2Al 3+ +3SiO3 2− +6H₂O=Al₂(SiO₃)₃⋅6H₂O↓ (Solubility product Ksp=3.2×10⁻⁶) -34 (It is almost insoluble in water at room temperature).

[0022] 3) Co-precipitation of aluminum ion hydrolysis and iron ion adsorption: The degree of hydrolysis of colloids is the highest at pH=8~9; the adsorption activity of colloids is the strongest; the co-precipitation removal rate of colloids reaches more than 80%.

[0023] The amount of the impurity remover added is 1.5-6% of the volume of the vanadium-containing crude liquid, such as 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] As a preferred technical solution of the present invention, the pretreatment in step (1) includes crushing and grinding the vanadium-containing raw material to obtain vanadium ore powder.

[0025] Preferably, the particle size of the vanadium ore powder is ≤120 mesh.

[0026] This invention uses a jaw crusher to crush the vanadium ore to a particle size of ≤120 mesh, and then uses a vibrating screen to remove impurities that exceed the particle size limit, thereby obtaining uniform vanadium ore powder. This particle size can ensure that the vanadium minerals and sodium salts are in full contact during subsequent roasting, thereby improving the conversion efficiency by 3% to 5%.

[0027] As a preferred technical solution of the present invention, the sodium salt in step (1) includes sodium carbonate and sodium chloride; the mass ratio of sodium carbonate to sodium chloride is 1:(1-1.1), such as 1:1, 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.1, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0028] Preferably, the amount of sodium salt added is 10-15% of the mass of the pretreated vanadium-containing raw material, such as 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0029] Preferably, the mixing method in step (1) includes stirring; the stirring time is 15-20 min, such as 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0030] As a preferred technical solution of the present invention, the calcination temperature of the sodium calcination treatment in step (1) is 880-920℃, such as 880℃, 885℃, 890℃, 895℃, 900℃, 905℃, 910℃, 915℃, 920℃, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0031] In this invention, by controlling the roasting temperature of the sodium roasting process, vanadium minerals (such as V2O3 and FeV2O4) can be fully converted into soluble sodium vanadate. If the roasting temperature is below 880°C, the vanadium conversion will be incomplete, and if the roasting temperature is above 920°C, the material will easily clump together.

[0032] Preferably, the sodium calcination treatment time is 2.5-3 hours, such as 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, 3 hours, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0033] Preferably, the sodium roasting treatment is carried out in an oxidizing atmosphere; the oxygen content in the oxidizing atmosphere is ≥8%, such as 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, etc., but not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0034] No impurity removal agent is added during the sodium roasting process described in this invention to avoid pre-reaction with sodium salt.

[0035] As a preferred technical solution of the present invention, in the water leaching vanadium extraction process in step (2), the liquid-solid ratio of water to roasted clinker is 4:1 to 6:1, for example 4:1, 4.3:1, 4.5:1, 4.8:1, 5:1, 5.2:1, 5.5:1, 5.8:1, 6:1, etc., but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0036] In this invention, by controlling the liquid-solid ratio of water to roasted clinker in the vanadium extraction process, vanadium can be fully leached out. If the liquid-solid ratio is too low, the vanadium leaching rate will be insufficient; if the liquid-solid ratio is too high, the vanadium solution concentration will be too low, affecting subsequent vanadium precipitation.

[0037] Preferably, the temperature of the water used for the vanadium extraction process is 85-95℃, such as 85℃, 87℃, 89℃, 91℃, 93℃, 95℃, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0038] Preferably, the vanadium extraction treatment is carried out under stirring conditions; the stirring speed is 60-80 r / min, such as 60 r / min, 65 r / min, 70 r / min, 75 r / min, 80 r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0039] Preferably, the vanadium extraction time is 1.5-2 hours, such as 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2 hours, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0040] Preferably, the concentration of V2O5 in the vanadium-containing crude liquid is controlled to be 20-25 g / L, such as 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L, 25 g / L, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0041] As a preferred technical solution of the present invention, the deep impurity removal process in step (3) is carried out under stirring conditions; the stirring speed is 40-50 r / min, such as 40 r / min, 42 r / min, 44 r / min, 46 r / min, 48 r / min, 50 r / min, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0042] Preferably, the concentration of the aluminum sulfate solution is 20-30%, such as 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0043] In this invention, the vanadium recovery rate can be improved by controlling the concentration of aluminum sulfate solution to 20-30%. If the concentration is too low, the volume of addition will be large, affecting production efficiency. If the concentration is too high, it will easily lead to violent local reactions and the formation of colloidal agglomerates.

[0044] Preferably, the amount of the impurity remover added is 2-4% of the volume of the vanadium-containing crude liquid, such as 2%, 2.3%, 2.5%, 2.7%, 3%, 3.3%, 3.5%, 3.8%, 4%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0045] In this invention, when the amount of the impurity remover added is 2% to 4% of the volume of the crude vanadium-containing liquid, the removal rates of silicon and iron reach 93% and 85% or more, respectively, and the vanadium recovery rate is ≥90%. If the amount of the impurity remover added is <1.5%, the impurity removal is incomplete. If it is >6%, the aluminum hydroxide colloid will excessively adsorb vanadium ions, causing the vanadium recovery rate to drop to below 88%.

[0046] Preferably, the deep impurity removal treatment uses an alkaline solution or an acid solution to control the pH to 8-9, such as 8, 8.2, 8.4, 8.6, 8.8, 9, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable, and 8.5 is more preferably used.

[0047] In this invention, when the pH value of the deep impurity removal treatment is 8.5, Al 3+ The aluminum hydroxide colloid generated by hydrolysis has the largest absolute zeta potential (≥30mV) and the strongest adsorption capacity. When pH < 8, hydrolysis is incomplete and the amount of colloid is insufficient. When pH > 9, the colloid is prone to agglomeration and sedimentation, and the adsorption efficiency decreases.

[0048] Preferably, the alkaline solution comprises a sodium hydroxide solution; the mass fraction of the sodium hydroxide solution is 10-15%, such as 10%, 11%, 12%, 13%, 14%, 15%, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0049] Preferably, the acid solution includes a sulfuric acid solution; the mass fraction of the sulfuric acid solution is 5-10%, such as 5%, 6%, 7%, 8%, 9%, 10%, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0050] Preferably, the temperature of the deep cleaning process is 60-70℃, such as 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0051] The preferred temperature for deep purification treatment in this invention is 60-70℃, which balances the reaction rate and precipitation stability. When the temperature for deep purification treatment is 60-70℃, the reaction rate between silicon ions and aluminum ions is increased by 2-3 times compared to room temperature, and the precipitated particles are larger (particle size ≥ 5μm), facilitating subsequent filtration. When the temperature is >70℃, the colloidal stability decreases; when the temperature is <60℃, the reaction time needs to be extended to more than 120 minutes, affecting production efficiency.

[0052] Preferably, the deep cleaning process takes 40-80 minutes, such as 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0053] As a preferred technical solution of the present invention, the impurity removal agent in step (3) further includes any one of potassium aluminum sulfate solution, polyaluminum chloride solution or ammonium aluminum sulfate solution.

[0054] Preferably, the concentration of the potassium aluminum sulfate solution is 25-35%, such as 25%, 27%, 29%, 31%, 33%, 35%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0055] Preferably, the amount of potassium aluminum sulfate solution added is 5-7% of the volume of the vanadium-containing crude liquid, such as 5%, 5.5%, 6%, 6.5%, 7%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0056] In this invention, potassium aluminum sulfate dissociates into Al in aqueous solution. 3+ The impurity removal principle is the same as that of aluminum sulfate; its advantages are stronger chemical stability, milder reaction in vanadium solution, less prone to colloidal agglomeration, and suitable for treating high silicon vanadium solution with SiO2 content >8%; its disadvantages are that the raw material cost is 10%~15% higher than that of aluminum sulfate, and the potassium ion residue is <0.01%, which does not affect the product performance.

[0057] Preferably, the concentration of the polyaluminum chloride solution is 10-20%, such as 10%, 12%, 14%, 16%, 18%, 20%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0058] Preferably, the amount of polyaluminum chloride solution added is 2.5-7.5% of the volume of the vanadium-containing crude liquid, such as 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0059] In this invention, polyaluminum chloride releases Al after hydrolysis. 3+It also generates polynuclear aluminum hydroxy complexes, which have a stronger adsorption capacity than aluminum sulfate, and the iron removal rate can reach 88%~90%, making it suitable for high-end products with extremely high iron content requirements (Fe≤0.02%). However, an additional washing step is required after vanadium precipitation to ensure that the residual chloride ion content is <0.005%. The advantage is that the iron removal effect is better, but the disadvantage is that an additional washing process is required, and the raw material cost is 5%~10% higher than that of aluminum sulfate.

[0060] Preferably, the concentration of the aluminum ammonium sulfate solution is 20-30%, such as 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0061] Preferably, the amount of aluminum ammonium sulfate solution added is 2-6% of the volume of the vanadium-containing crude liquid, such as 2%, 3%, 4%, 5%, 6%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0062] In this invention, ammonium aluminum sulfate dissociates to release Al 3+ Achieving impurity removal while releasing NH4 + It can assist in the subsequent vanadium precipitation reaction and reduce the amount of ammonium sulfate added by 10% to 15%. The advantage is that the vanadium precipitation efficiency is improved, but the disadvantage is that the raw material price is 20% to 25% higher than that of aluminum sulfate. It is suitable for small-batch, high-precision product production.

[0063] As a preferred technical solution of the present invention, the vanadium precipitation agent in the reduction vanadium precipitation treatment in step (4) includes ammonium sulfate; the molar ratio of ammonium sulfate to vanadium ions is 1.2:1 to 1.5:1, for example 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1, 1.5:1, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0064] Preferably, the reduction precipitation of vanadium is performed by adjusting the pH of the acid solution to 2.0-2.5, such as 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, etc., but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0065] Preferably, the acid solution includes a dilute sulfuric acid solution.

[0066] Preferably, the stirring reaction time for the reduction vanadium precipitation treatment is 30-50 min, such as 30 min, 35 min, 40 min, 45 min, 50 min, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0067] As a preferred technical solution of the present invention, after the vanadium reduction treatment in step (4) generates a precipitate, it is allowed to stand for 10-15 minutes; then the solid and liquid are separated and washed with deionized water 2-3 times.

[0068] The vanadium reduction precipitation process of the present invention involves mixing and reacting purified vanadium solution with ammonium sulfate as a vanadium precipitant to generate a pale yellow ammonium polyvanadate precipitate; after standing for a period of time, the solid and liquid are separated, and the precipitate is washed with deionized water to remove the sulfate ions adsorbed on the surface.

[0069] The settling time is 10-15 minutes, such as 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0070] The number of washes is 2-3 times, such as 2 times, 3 times, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range also apply.

[0071] As a preferred technical solution of the present invention, the calcination temperature in step (4) is 580-620℃, such as 580℃, 585℃, 590℃, 595℃, 600℃, 605℃, 610℃, 615℃, 620℃, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0072] Preferably, the calcination time is 2.5-3 hours, such as 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, 3 hours, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0073] In this invention, the ammonium polyvanadate precipitate obtained by reduction vanadium precipitation is calcined to decompose the ammonium polyvanadate into vanadium pentoxide. During the calcination process, vanadium pentoxide forms a liquid and is then used to generate flake vanadium pentoxide through a disc casting machine. After cooling to room temperature, the finished product is obtained with a thickness of 0.1~0.3mm, which meets the industry requirements for flake vanadium pentoxide.

[0074] The chemical reaction equation that occurs during the calcination process is: 2NH4VO3→V2O5+2NH3↑+H2O↑.

[0075] Preferably, the thickness of the low-silicon, low-iron flake vanadium pentoxide is 0.1-0.3 mm, such as 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0076] Compared with the prior art, the present invention has at least the following beneficial effects:

[0077] (1) This invention adds aluminum sulfate as a vanadium-containing impurity remover only during the purification stage of the crude vanadium-containing liquor after water leaching extraction, without adding any aluminum-containing vanadium ... 3+ Fully participate in the impurity removal reaction;

[0078] (2) This invention optimizes the concentration and amount of aluminum sulfate solution added during the deep purification process, as well as the temperature, pH, and time of the deep purification reaction. Through the precipitation reaction of aluminum ions and silicon ions and the adsorption and co-precipitation of iron ions by aluminum hydroxide colloid, the simultaneous removal of silicon and iron impurities from vanadium solution is achieved. The vanadium pentoxide product obtained by this invention has a silicon content ≤0.1%, an iron content ≤0.1%, a thickness of 0.1~0.3 mm, and a vanadium recovery rate ≥90%.

[0079] (3) The preparation method of the present invention does not change the core equipment (rotary kiln, leaching tank, melting furnace) and key parameters (roasting temperature, leaching liquid-solid ratio, calcination temperature) of the existing sodium roasting process. It only requires the addition of a simple aluminum sulfate addition device, which reduces the difficulty and cost of industrialization. Detailed Implementation

[0080] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0081] Example 1

[0082] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide, the preparation method comprising:

[0083] (1) After crushing and grinding the vanadium-containing raw material, vanadium ore powder is obtained; the particle size of the vanadium ore powder is ≤120 mesh; the vanadium ore powder is mixed with sodium carbonate and sodium chloride in a mass ratio of 1:1 for 15 min, and then subjected to sodium roasting treatment at 880℃ for 3 h to obtain roasted clinker;

[0084] The total amount of sodium carbonate and sodium chloride added is 10% of the mass of the vanadium ore powder; the sodium roasting treatment is carried out under an oxidizing atmosphere; the oxygen content in the oxidizing atmosphere is 8%;

[0085] (2) Water at 85°C and the roasted clinker are mixed and stirred at 60 r / min at a liquid-solid ratio of 4:1, and vanadium is extracted by water leaching for 2 h to obtain vanadium-containing crude liquid; and the V2O5 concentration in the vanadium-containing crude liquid is controlled to be 20 g / L.

[0086] (3) Add a 20% aluminum sulfate solution to the crude vanadium solution, and perform deep impurity removal treatment at 60°C for 80 minutes under stirring at 40 r / min to obtain purified vanadium solution;

[0087] The amount of aluminum sulfate solution added is 4% of the volume of the vanadium-containing crude liquid; the deep impurity removal treatment uses a 10% sodium hydroxide solution to control the pH at 8.5.

[0088] (4) The purified vanadium solution is mixed with ammonium sulfate and subjected to reduction precipitation treatment with stirring for 30 min; after the vanadium precipitation treatment generates precipitate, it is allowed to stand for 15 min; then the solid and liquid are separated and washed twice with deionized water;

[0089] The resulting precipitate was then calcined at 580°C for 3 hours to obtain the low-silicon, low-iron flake vanadium pentoxide with a thickness of 0.1-0.3 mm.

[0090] The molar ratio of ammonium sulfate to vanadium ions is 1.2:1; the reduction precipitation of vanadium is performed by adjusting the pH to 2.0 with dilute sulfuric acid solution.

[0091] Example 2

[0092] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide, the preparation method comprising:

[0093] (1) After crushing and grinding the vanadium-containing raw material, vanadium ore powder is obtained; the particle size of the vanadium ore powder is ≤120 mesh; the vanadium ore powder is mixed with sodium carbonate and sodium chloride in a mass ratio of 1:1.05 for 17 min, and then subjected to sodium roasting treatment at 900℃ for 2.7 h to obtain roasted clinker;

[0094] The total amount of sodium carbonate and sodium chloride added is 13% of the mass of the vanadium ore powder; the sodium roasting treatment is carried out under an oxidizing atmosphere; the oxygen content in the oxidizing atmosphere is 10%;

[0095] (2) Water at 90°C and the roasted clinker are mixed and stirred at 70 r / min at a liquid-solid ratio of 5:1, and vanadium is extracted by water leaching for 1.7 h to obtain vanadium-containing crude liquor; and the V2O5 concentration in the vanadium-containing crude liquor is controlled to be 23 g / L.

[0096] (3) Add a 25% potassium aluminum sulfate solution to the crude vanadium solution, and perform deep impurity removal treatment at 65°C for 60 min under stirring at 45 r / min to obtain purified vanadium solution;

[0097] The amount of potassium aluminum sulfate solution added is 5% of the volume of the vanadium-containing crude liquid; the deep impurity removal treatment uses a 5% sulfuric acid solution to control the pH at 8;

[0098] (4) The purified vanadium solution is mixed with ammonium sulfate and subjected to reduction precipitation treatment with stirring for 40 min; after the vanadium precipitation treatment generates precipitate, it is allowed to stand for 13 min; then the solid and liquid are separated and washed 3 times with deionized water;

[0099] The resulting precipitate was then calcined at 600℃ for 2.7 h to obtain the low-silicon, low-iron flake vanadium pentoxide with a thickness of 0.1-0.3 mm.

[0100] The molar ratio of ammonium sulfate to vanadium ions is 1.3:1; the reduction precipitation of vanadium is performed by adjusting the pH to 2.3 with dilute sulfuric acid solution.

[0101] Example 3

[0102] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide, the preparation method comprising:

[0103] (1) After crushing and grinding the vanadium-containing raw material, vanadium ore powder is obtained; the particle size of the vanadium ore powder is ≤120 mesh; the vanadium ore powder is mixed with sodium carbonate and sodium chloride in a mass ratio of 1:1.1 for 15 min, and then subjected to sodium roasting treatment at 920℃ for 2.5 h to obtain roasted clinker;

[0104] The total amount of sodium carbonate and sodium chloride added is 15% of the mass of the vanadium ore powder; the sodium roasting treatment is carried out under an oxidizing atmosphere; the oxygen content in the oxidizing atmosphere is 12%.

[0105] (2) Water at 95°C and the roasted clinker are mixed and stirred at 80 r / min at a liquid-solid ratio of 6:1, and vanadium is extracted by water leaching for 1.5 h to obtain vanadium-containing crude liquid; and the V2O5 concentration in the vanadium-containing crude liquid is controlled to be 25 g / L.

[0106] (3) Add a 10% polyaluminum chloride solution to the vanadium-containing crude liquid, and perform deep impurity removal treatment at 70°C for 40 minutes under stirring at 50 r / min to obtain purified vanadium liquid;

[0107] The amount of polyaluminum chloride solution added is 7.5% of the volume of the vanadium-containing crude liquid; the deep impurity removal treatment uses a 10% sulfuric acid solution to control the pH at 8;

[0108] (4) The purified vanadium solution is mixed with ammonium sulfate and subjected to reduction precipitation treatment with stirring for 50 min; after the vanadium precipitation treatment generates precipitate, it is allowed to stand for 10 min; then the solid and liquid are separated and washed 3 times with deionized water;

[0109] The resulting precipitate was then calcined at 620°C for 2.5 hours to obtain the low-silicon, low-iron flake vanadium pentoxide with a thickness of 0.1-0.3 mm.

[0110] The molar ratio of ammonium sulfate to vanadium ions is 1.5:1; the reduction precipitation of vanadium is performed by adjusting the pH to 2.5 with dilute sulfuric acid solution.

[0111] Example 4

[0112] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide, the preparation method comprising:

[0113] (1) After crushing and grinding the vanadium-containing raw material, vanadium ore powder is obtained; the particle size of the vanadium ore powder is ≤120 mesh; the vanadium ore powder is mixed with sodium carbonate and sodium chloride in a mass ratio of 1:1 for 15 min, and then subjected to sodium roasting treatment at 910℃ for 2.6 h to obtain roasted clinker;

[0114] The total amount of sodium carbonate and sodium chloride added is 11% of the mass of the vanadium ore powder; the sodium roasting treatment is carried out under an oxidizing atmosphere; the oxygen content in the oxidizing atmosphere is 14%.

[0115] (2) Water at 92°C and the roasted clinker are mixed and stirred at 75 r / min at a liquid-solid ratio of 5.5:1 and subjected to water leaching for vanadium extraction for 1.6 h to obtain vanadium-containing crude liquid; and the V2O5 concentration in the vanadium-containing crude liquid is controlled to be 21 g / L.

[0116] (3) Add a 30% aluminum ammonium sulfate solution to the crude vanadium solution, and perform deep impurity removal treatment at 66°C for 50 min under stirring at 48 r / min to obtain purified vanadium solution;

[0117] The amount of aluminum ammonium sulfate solution added is 2% of the volume of the vanadium-containing crude liquid; the deep impurity removal treatment uses an 8% sulfuric acid solution to control the pH at 8.2.

[0118] (4) The purified vanadium solution is mixed with ammonium sulfate and subjected to reduction precipitation treatment with stirring for 35 min; after the vanadium precipitation treatment generates precipitate, it is allowed to stand for 12 min; then the solid and liquid are separated and washed twice with deionized water;

[0119] The resulting precipitate was then calcined at 610℃ for 2.6 hours to obtain the low-silicon, low-iron flake vanadium pentoxide with a thickness of 0.1-0.3 mm.

[0120] The molar ratio of ammonium sulfate to vanadium ions is 1.4:1; the reduction precipitation of vanadium is performed by adjusting the pH to 2.1 with dilute sulfuric acid solution.

[0121] Example 5

[0122] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Embodiment 1 is that the concentration of the aluminum sulfate solution in step (3) is 15%, while the others are the same as in Embodiment 1.

[0123] Example 6

[0124] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Embodiment 1 is that the concentration of the aluminum sulfate solution in step (3) is 35%, while the others are the same as in Embodiment 1.

[0125] Example 7

[0126] This embodiment provides a method for preparing low-silicon, low-iron flake vanadium pentoxide. The difference from Embodiment 1 is that the amount of aluminum sulfate solution added in step (3) is 1.8% of the volume of the vanadium-containing crude liquid. All other aspects are the same as in Embodiment 1.

[0127] Example 8

[0128] This embodiment provides a method for preparing low-silicon, low-iron flake vanadium pentoxide. The difference from Embodiment 1 is that the amount of aluminum sulfate solution added in step (3) is 4.2% of the volume of the vanadium-containing crude liquid. All other aspects are the same as in Embodiment 1.

[0129] Example 9

[0130] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Embodiment 1 is that the temperature of the deep impurity removal treatment in step (3) is 55°C, while the rest is the same as in Embodiment 1.

[0131] Example 10

[0132] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Embodiment 1 is that the temperature of the deep impurity removal treatment in step (3) is 75°C, while the rest is the same as in Embodiment 1.

[0133] Example 11

[0134] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Embodiment 1 is that the pH of the deep impurity removal treatment in step (3) is 7.5, while the rest is the same as in Embodiment 1.

[0135] Example 12

[0136] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Example 1 is that the pH of the deep impurity removal treatment in step (3) is 9.5, while the rest is the same as in Example 1.

[0137] Example 13

[0138] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Embodiment 1 is that the deep impurity removal process in step (3) takes 35 minutes, while the rest is the same as in Embodiment 1.

[0139] Example 14

[0140] This embodiment provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Embodiment 1 is that the deep impurity removal process in step (3) takes 85 minutes, while the rest is the same as in Embodiment 1.

[0141] Comparative Example 1

[0142] This comparative example provides a method for preparing low-silicon, low-iron flake vanadium pentoxide. The difference from Example 1 is that the amount of aluminum sulfate solution added in step (3) is 1.2% of the volume of the vanadium-containing crude liquid. All other aspects are the same as in Example 1.

[0143] Comparative Example 2

[0144] This comparative example provides a method for preparing low-silicon, low-iron flake vanadium pentoxide. The difference from Example 1 is that the amount of aluminum sulfate solution added in step (3) is 6.3% of the volume of the vanadium-containing crude liquid. All other aspects are the same as in Example 1.

[0145] Comparative Example 3

[0146] This comparative example provides a method for preparing low-silicon, low-iron sheet-like vanadium pentoxide. The difference from Example 1 is that the aluminum sulfate solution in step (3) is replaced with calcium chloride solution in equal mass. All other aspects are the same as in Example 1.

[0147] Comparative Example 4

[0148] This comparative example provides a method for preparing low-silicon, low-iron flake vanadium pentoxide. The difference from Example 1 is that aluminum sulfate solution is added in the sodium roasting treatment described in step (1), while the rest is the same as in Example 1.

[0149] Comparative Example 5

[0150] This comparative example provides a method for preparing low-silicon, low-iron flake vanadium pentoxide. The difference from Example 1 is that aluminum sulfate solution is added in the water leaching vanadium extraction process described in step (2). All other aspects are the same as in Example 1.

[0151] Performance testing

[0152] The silicon content, iron content, and vanadium recovery rate of the vanadium pentoxide products prepared in Examples 1-14 and Comparative Examples 1-5 were tested, and the specific results are shown in Table 1.

[0153] Table 1

[0154]

[0155] The test results show that:

[0156] (1) As can be seen from Examples 1 to 4, the present invention adds aluminum sulfate as a vanadium-containing crude liquor purification agent only in the purification stage after water leaching for vanadium extraction, and does not add any aluminum-containing vanadium ... 3+ The vanadium pentoxide product obtained by fully participating in the impurity removal reaction has a silicon content of ≤0.1%, an iron content of ≤0.1%, and a vanadium recovery rate of ≥90%.

[0157] (2) By comparing Example 1 with Examples 5-14, it can be seen that by optimizing the concentration and amount of aluminum sulfate solution and the temperature, pH and time of the deep impurity removal reaction, the present invention can further improve the vanadium recovery rate and reduce the silicon and iron content of the product.

[0158] (3) By comparing Example 1 with Comparative Examples 1-2, it can be seen that the aluminum sulfate solution in Comparative Examples 1-2 is not within the preferred range of this application, which leads to a decrease in vanadium recovery rate and an increase in silicon and iron content of vanadium pentoxide product.

[0159] (4) By comparing Example 1 with Comparative Examples 3-5, it can be seen that replacing aluminum sulfate with calcium chloride in Comparative Example 3 can only effectively remove silicon impurities, but cannot remove iron impurities at the same time, which ultimately leads to an increase in the iron content of vanadium pentoxide products and a decrease in vanadium recovery rate.

[0160] In Comparative Examples 4 and 5, aluminum sulfate was not added only during the purification of the crude vanadium-containing liquor after water leaching for vanadium extraction. Instead, aluminum sulfate was added during the sodium roasting and water leaching for vanadium extraction stages. Due to the high temperature during the sodium roasting stage, aluminum salts were severely decomposed and lost, resulting in unstable impurity removal and a decrease in vanadium recovery rate, as well as an increase in silicon and iron content in the vanadium pentoxide product.

[0161] In summary, this invention provides a method for preparing low-silicon, low-iron flake vanadium pentoxide. By adding aluminum sulfate as a purifying agent only during the purification stage of the vanadium-containing crude liquor after water leaching, and omitting any aluminum-containing purifying agents in all other stages such as sodium preparation and calcination, the high-temperature decomposition and loss of purifying agents are fundamentally avoided, ensuring the purity of Al. 3+It fully participates in the impurity removal reaction; by optimizing the concentration and amount of aluminum sulfate solution in the deep impurity removal process, as well as the temperature, pH, and time of the deep impurity removal reaction, the silicon and iron impurities in the vanadium solution are simultaneously removed through the precipitation reaction of aluminum ions and silicon ions and the adsorption and co-precipitation of iron ions by aluminum hydroxide colloid; the obtained vanadium pentoxide product has a silicon content ≤0.1%, an iron content ≤0.1%, a thickness of 0.1~0.3mm, and a vanadium recovery rate ≥90%.

[0162] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing low-silicon, low-iron flake vanadium pentoxide, characterized in that, The preparation method includes: (1) After mixing the pretreated vanadium-containing raw material with sodium salt, sodium roasting treatment is carried out to obtain roasted clinker; (2) The roasted clinker is subjected to water leaching for vanadium extraction to obtain vanadium-containing crude liquid; (3) Add a vanadium-containing crude liquid to perform deep impurity removal treatment to obtain purified vanadium liquid; the vanadium-containing crude liquid contains aluminum sulfate solution; the amount of vanadium-containing crude liquid added is 1.5-6% of the volume of the vanadium-containing crude liquid. (4) The purified vanadium liquid is subjected to reduction precipitation and calcination treatment in sequence to obtain the low-silicon and low-iron flake vanadium pentoxide.

2. The preparation method according to claim 1, characterized in that, The pretreatment in step (1) includes crushing and grinding the vanadium-containing raw material to obtain vanadium ore powder; Preferably, the particle size of the vanadium ore powder is ≤120 mesh.

3. The preparation method according to claim 1 or 2, characterized in that, The sodium salt in step (1) includes sodium carbonate and sodium chloride; the mass ratio of sodium carbonate to sodium chloride is 1:(1-1.1); Preferably, the amount of sodium salt added is 10-15% of the mass of the pretreated vanadium-containing raw material; Preferably, the mixing method in step (1) includes stirring; the stirring time is 15-20 min.

4. The preparation method according to any one of claims 1-3, characterized in that, The calcination temperature for the sodium-based calcination treatment in step (1) is 880-920℃; Preferably, the sodium calcination treatment time is 2.5-3 hours; Preferably, the sodium roasting treatment is carried out in an oxidizing atmosphere; the oxygen content in the oxidizing atmosphere is ≥8%.

5. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the liquid-solid ratio of water to calcined clinker in the vanadium extraction process is 4:1 to 6:

1. Preferably, the temperature of the water used in the vanadium extraction process is 85-95°C; Preferably, the vanadium extraction treatment is carried out under stirring conditions; the stirring speed is 60-80 r / min. Preferably, the vanadium extraction treatment by water leaching takes 1.5-2 hours; Preferably, the concentration of V2O5 in the vanadium-containing crude liquid is controlled to be 20-25 g / L.

6. The preparation method according to any one of claims 1-5, characterized in that, The deep impurity removal process described in step (3) is carried out under stirring conditions; the stirring speed is 40-50 r / min; Preferably, the concentration of the aluminum sulfate solution is 20-30%; Preferably, the amount of the impurity remover added is 2-4% of the volume of the vanadium-containing crude liquid; Preferably, the deep impurity removal treatment uses an alkaline solution or an acidic solution to control the pH to 8-9; Preferably, the alkaline solution comprises a sodium hydroxide solution; the mass fraction of the sodium hydroxide solution is 10-15%; the acid solution comprises a sulfuric acid solution; the mass fraction of the sulfuric acid solution is 5-10%. Preferably, the temperature of the deep impurity removal treatment is 60-70℃ and the time is 40-80 min.

7. The preparation method according to any one of claims 1-6, characterized in that, The impurity removal agent in step (3) also includes any one of potassium aluminum sulfate solution, polyaluminum chloride solution, or ammonium aluminum sulfate solution; Preferably, the concentration of the potassium aluminum sulfate solution is 25-35%, and the amount added is 5-7% of the volume of the vanadium-containing crude liquid; Preferably, the concentration of the polyaluminum chloride solution is 10-20%, and the amount added is 2.5-7.5% of the volume of the vanadium-containing crude liquid. Preferably, the concentration of the aluminum ammonium sulfate solution is 20-30%, and the amount added is 2-6% of the volume of the vanadium-containing crude liquid.

8. The preparation method according to any one of claims 1-7, characterized in that, The vanadium precipitating agent in step (4) of the reduction vanadium precipitation treatment includes ammonium sulfate; the molar ratio of ammonium sulfate to vanadium ions is 1.2:1 to 1.5:1; Preferably, the vanadium reduction precipitation treatment uses an acid solution to adjust the pH to 2.0-2.5; the acid solution includes a dilute sulfuric acid solution; Preferably, the stirring reaction time for the reduction vanadium precipitation treatment is 30-50 minutes.

9. The preparation method according to any one of claims 1-8, characterized in that, After the vanadium reduction treatment in step (4) generates a precipitate, let it stand for 10-15 minutes; then separate the solid and liquid, and wash with deionized water 2-3 times.

10. The preparation method according to any one of claims 1-9, characterized in that, The calcination temperature in step (4) is 580-620℃; Preferably, the calcination treatment time is 2.5-3 hours; Preferably, the thickness of the low-silicon, low-iron sheet vanadium pentoxide is 0.1-0.3 mm.

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