A process for purifying ammonium metavanadate from spent hydrofining catalyst

Abstract

The application discloses a method for purifying ammonium metavanadate from waste hydrofining catalysts, comprising the following steps: S1, raw material pretreatment and grading crushing: the vanadium-containing waste catalyst is sent into a jaw crusher for rough crushing to 5-10 mm; then the waste catalyst is sent into an impact crusher for medium crushing to 1-3 mm; finally, the waste catalyst is sent into an air flow pulverizer for superfine crushing, and grading screening is conducted to obtain catalyst powder with a particle size of 150-250 microns, wherein the proportion of powder with a particle size of 180-220 microns is greater than or equal to 90%; S2, two-stage roasting pretreatment: the catalyst powder obtained in the step S1 is sent into a rotary kiln for two-stage roasting treatment. The product has high purity: through the combined process of 'pressure leaching + ion exchange + gradient recrystallization + membrane filtration', impurities such as Al, Fe, Ni, Na and K are effectively removed, the purity of the product is greater than or equal to 99.5%, and the highest purity can reach 99.56%, thereby meeting the needs of high-end applications.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of non-ferrous metallurgy and waste catalyst resource utilization, and particularly relates to a method for purifying ammonium metavanadate from waste hydrofining catalyst. BACKGROUND

[0002] The waste hydrofining catalyst is rich in valuable metals such as vanadium, nickel and molybdenum, and is an important secondary resource. Traditional treatment methods mostly use landfill or pyrometallurgy, which not only wastes valuable resources such as vanadium and nickel, but also causes environmental pollution problems due to heavy metal leakage.

[0003] The existing recovery and purification technology has obvious defects: the acid leaching / alkaline leaching method has poor selectivity for vanadium, and impurities such as Al, Si and Fe are easily mixed in the leaching solution, resulting in great difficulty in subsequent separation; the ammonium metavanadate product prepared by the traditional crystallization method has a purity of only 90%-95%, which cannot meet the use requirements in high-end fields such as lithium batteries and high-end catalysts; although the solvent extraction method can improve the purity, it has problems such as complex process, high reagent cost and easy organic pollution. Therefore, it is of great practical significance to develop an efficient, low-cost and green ammonium metavanadate purification method with high purity. SUMMARY

[0004] The purpose of the present application is to solve the problems in the prior art, such as poor selectivity of acid leaching / alkaline leaching method for vanadium, easy mixing of impurities such as Al, Si and Fe in the leaching solution, resulting in great difficulty in subsequent separation; the purity of ammonium metavanadate product prepared by the traditional crystallization method is only 90%-95%, which cannot meet the use requirements in high-end fields such as lithium batteries and high-end catalysts, and a method for purifying ammonium metavanadate from waste hydrofining catalyst is provided.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] A method for purifying ammonium metavanadate from waste hydrofining catalyst, comprising the following steps:

[0007] S1, raw material pretreatment and grading crushing: the vanadium-containing waste catalyst is sent into a jaw crusher for coarse crushing to 5-10mm; then sent into a counter-attack crusher for medium crushing to 1-3mm;

[0008] Finally, the catalyst powder is sent into an air flow pulverizer for superfine crushing, and the 150-250 mesh catalyst powder is obtained by grading screening, wherein the proportion of 180-220 mesh powder is greater than or equal to 90%;

[0009] S2, two-stage roasting pretreatment: the catalyst powder obtained in step S1 is sent into a rotary kiln for two-stage roasting treatment:

[0010] S3, composite system pressure leaching: the roasted material after step S2 is sent into a high-pressure leaching kettle, a composite leaching agent is added, and pressure leaching is performed;

[0011] S4, four-stage deep collaborative impurity removal: the leaching solution obtained in step S3 is subjected to four-stage deep impurity removal;

[0012] S5, seed crystal induction-segmented gradient cooling coupled crystallization: the vanadium purified solution obtained in step S4 is subjected to crystallization purification;

[0013] S6, recrystallization and precision purification: the coarse ammonium metavanadate crystal obtained in step S5 is subjected to recrystallization and purification;

[0014] S7, low-temperature vacuum drying and finished product preparation: the refined ammonium metavanadate crystal obtained in step S6 is sent into a vacuum drying box, the drying temperature is controlled to be 50-70°C, the vacuum degree is controlled to be -0.08--0.1 MPa, the drying time is 3-4 hours, nitrogen is introduced for protection during the drying process to prevent oxidation of the crystal; after the drying is completed, the crystal is crushed and sieved to obtain high-purity ammonium metavanadate finished product;

[0015] S8, comprehensive recovery of by-product metals;

[0016] S9, wastewater recycling and waste heat recovery.

[0017] Preferably, the first-stage roasting controls the temperature to be 250-350°C, air is introduced as the carrier gas, the gas-solid ratio is 5-8:1, and the roasting time is 1.5-2.5 hours to remove organic matter, moisture and part of the easily volatile sulfate impurities adsorbed on the surface of the catalyst;

[0018] The second-stage roasting raises the temperature to 650-750°C, oxygen-enriched air with an oxygen content of 25%-30% is introduced, the gas-solid ratio is 8-12:1, and the roasting time is 2-3 hours to oxidize the low-valence vanadium compounds in the catalyst into easily leachable high-valence vanadium compounds, and to convert the nickel and molybdenum into stable oxide forms.

[0019] Preferably, the flue gas generated by the two-stage roasting is treated by a desulfurization and denitrification system: the flue gas first enters a cyclone dust collector to remove dust, and then enters a semi-dry desulfurization tower, calcium hydroxide slurry is used as the desulfurizing agent;

[0020] Subsequently, the flue gas enters an SCR denitrification reactor, ammonia water is used as the reducing agent under the action of a vanadium-titanium catalyst; the treated flue gas is discharged into the atmosphere by an induced draft fan, and the dust is recycled and returned to the roasting process.

[0021] Preferably, the composite leaching agent is composed of a sodium carbonate solution with a mass concentration of 10%-18% as the main body, an auxiliary leaching agent with a mass concentration of 1%-3%, and an oxidizing agent with a mass concentration of 0.5%-1.5%;

[0022] wherein the liquid-solid ratio is controlled to be 8-12:1;

[0023] The temperature of the leaching condition is 140-170℃, the pressure is 1.0-3.0 MPa, the stirring rate is 300-500 r / min, and the leaching time is 2.5-3.5 hours;

[0024] The solid-liquid separation is performed after the leaching is completed, the slurry is sent into a plate-and-frame filter press for filtration to obtain a leaching solution and a leaching residue; the leaching residue is sent into a by-product metal recovery unit, and the leaching solution enters a subsequent impurity removal process.

[0025] Preferably, the impurity removal step in step S4 is specifically as follows:

[0026] S4.1, pre-silicon removal: adjust the temperature of the leaching solution to 60-80℃, add a hydrochloric acid solution with a mass concentration of 5%-10% to adjust the pH to 4.5-5.5, add 0.3%-0.8% of a polyaluminum ferric silicate flocculant based on the mass of the leaching solution, stir and react for 30-60 minutes, and after standing and settling, filter to remove most of the Si 4+ impurities; the filter residue is washed and sent to a hazardous waste disposal center;

[0027] S4.2, sulfide precipitation to remove heavy metal impurities: control the temperature of the pre-silicon removal filtrate at 40-50℃, add a sodium sulfide solution (mass concentration of 10%-15%), and the amount of sodium sulfide added is 1.2-1.8 times the stoichiometric amount required to remove Ni 2+ , Cu 2+ , etc. heavy metal impurities, stir and react for 60-90 minutes to generate a sulfide precipitate, filter to remove the heavy metal impurities, and send the filter residue to a by-product metal recovery unit;

[0028] S4.3, complex ion exchange impurity removal: send the sulfide precipitate filtrate after filtration to a complex ion exchange column, fill the complex ion exchange column with a mixed resin of D201 type strong basic anion exchange resin and 001×7 type strong acid cation exchange resin (volume ratio of 3:1), control the flow rate to be 1-2 BV / h, and adsorb and remove Al 3+ , Fe 3+ , Ca 2+ , Mg 2+ , etc. impurities; after the ion exchange column is saturated, regenerate it with a 5%-8% hydrochloric acid solution, and recycle the regenerated solution after treatment;

[0029] S4.4, chelate adsorption deep impurity removal: send the complex ion exchange solution to a chelate resin column, use an amino phosphonic acid type chelate resin, control the flow rate to be 0.8-1.5 BV / h, and adsorb and remove trace amounts of Ni 2+ , Mo 6+Impurities, ensure that the solution of heavy metal impurities content decreased to 1 ppm or less, to obtain the vanadium purification solution.

[0030] Preferably, the crystallization purification step in step S5 is as follows:

[0031] S5.1, seed preparation: take the purity ≥ 99.9% of ammonium metavanadate standard, dissolved in 80-90℃ ultrapure water, preparation of mass concentration of 15%-20% ammonium metavanadate solution, slowly cooled to 40-50℃, stirring to precipitate the crystal, after filtration to obtain the particle size of 50-100μm ammonium metavanadate seed;

[0032] S5.2, evaporation concentration: the vanadium purification solution into falling film evaporator, under the condition of vacuum degree of-0.06--0.08MPa, temperature of 50-60℃, concentrated to the solution of vanadium concentration of 80-100g / L;

[0033] S5.3, seed induced crystallization: the concentrated liquid into the crystallizer, heated to 70-80℃, add 0.5%-1.0% of the concentrated liquid mass of ammonium metavanadate seed, stirring rate control for 150-200r / min, constant temperature stirring 1-2h, make the seed dispersion and induce crystal growth;

[0034] S5.4, subsection gradient cooling crystallization: using three stage gradient cooling mode:

[0035] The first stage: from 70-80℃ to 50-55℃, the cooling rate is 1.0-1.5℃ / min, the stirring rate is kept at 200-250r / min, to promote the rapid nucleation of crystal;

[0036] The second stage: from 50-55℃ to 35-40℃, the cooling rate is 0.3-0.5℃ / min, the stirring rate is reduced to 150-200r / min, conducive to the growth of crystal and impurity desorption;

[0037] The third stage: from 35-40℃ to 20-25℃, the cooling rate is 0.8-1.0℃ / min, the stirring rate is kept at 150r / min, to ensure the uniform growth of crystal;

[0038] S5.5 solid-liquid separation: after crystallization, the slurry is sent into the centrifuge for centrifugal separation, to obtain the coarse ammonium metavanadate crystal and crystallization mother liquor; the crystallization mother liquor returns to the leaching process for recycling.

[0039] Preferably, the recrystallization purification step in step S6 is as follows:

[0040] S6.1, dissolution: the coarse ammonium metavanadate crystal is added into ultrapure water, heated to 70-80℃, stirring to dissolve, to prepare a mass concentration of 20%-25% ammonium metavanadate solution;

[0041] S6.2, Precision filtration: the solution is sequentially filtered through 0.45 μm ceramic membrane and 0.1 μm organic ultrafiltration membrane for two-stage filtration to remove colloidal impurities and trace mechanical impurities;

[0042] S6.3, Recrystallization: the filtered solution is fed into a secondary crystallizer, 0.3%-0.5% ammonium metavanadate seed is added, and a "constant temperature evaporation-slow cooling" coupling mode is adopted: first evaporate and concentrate to 60%-70% of the original volume at 60-70℃ and vacuum degree-0.07--0.09MPa, then cool to 20-25℃ at a rate of 0.2-0.3℃ / min, and keep constant temperature for 2-3 hours;

[0043] S6.4 Centrifugal washing: the recrystallized slurry is fed into a high-speed centrifuge, and the fine ammonium metavanadate crystals are obtained by centrifugal separation, and washed with ultrapure water for 2-3 times to remove the surface adsorbed impurity ions.

[0044] Preferably, the specific steps of byproduct metal recovery for the leaching residue of step S3 and the sulfide precipitation of step S4.2 are as follows:

[0045] S8.1, Acid leaching dissolution: the leaching residue and the sulfide precipitation are mixed and fed into an acid leaching tank, a sulfuric acid solution with a mass concentration of 15%-20% is added, the liquid-solid ratio is 10-15:1, heated to 80-90℃, and stirred for 3-4 hours to dissolve nickel, molybdenum, tungsten and other metals into the solution, and then filtered to obtain an acid leaching solution and an acid leaching residue;

[0046] S8.2, Solvent extraction separation of molybdenum: the acid leaching solution is adjusted to pH 1.5-2.5, fed into an extraction tank, and a mixed extractant of tri-butyl phosphate and kerosene is added with a phase ratio of 1:2-1:3, stirred for 10-15 minutes, and then separated by standing, molybdenum enters the organic phase, and nickel and tungsten remain in the aqueous phase; the organic phase is back-extracted with 5%-8% ammonia water to obtain an ammonium molybdate solution, which is evaporated, crystallized and dried to obtain ammonium molybdate product;

[0047] S8.3, Solvent extraction separation of tungsten: the aqueous phase after separation of molybdenum is adjusted to pH 3.5-4.5, a mixed extractant of secondary octanol and kerosene is added with a phase ratio of 1:1-1:2, stirred for 15-20 minutes, and then separated by standing, tungsten enters the organic phase; the organic phase is back-extracted with 10%-15% sodium hydroxide solution to obtain a sodium tungstate solution, which is evaporated, crystallized and dried to obtain sodium tungstate product;

[0048] S8.4, Precipitation recovery of nickel: the aqueous phase after separation of tungsten is adjusted to pH 8.5-9.5, 10%-15% sodium carbonate solution is added, stirred for 30-40 minutes to generate nickel carbonate precipitate, which is filtered, washed, and then calcined to obtain nickel oxide product.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] High product purity: through the combined process of "pressure leaching + ion exchange + gradient recrystallization + membrane filtration", impurities such as Al, Fe, Ni, Na and K are effectively removed, the product purity is ≥99.5%, and the highest can reach 99.56%, meeting the needs of high-end applications;

[0051] High resource recovery rate: the total vanadium recovery rate is ≥90%, and the preliminary separation of nickel, molybdenum and other metals is realized, laying a foundation for subsequent recovery, and the resource utilization rate is significantly improved;

[0052] Green and environmentally friendly: no toxic reagents such as cyanide are used in the whole process, the leaching residue can be further recovered for valuable metals or safely disposed, and the wastewater can be recycled after simple treatment, with low environmental pollution risk;

[0053] Significant cost advantage: the process flow is simple, the reagent consumption is low, and the coupling design of pressure leaching and ion exchange reduces the separation difficulty, which greatly reduces the production cost compared with the solvent extraction method. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 The figure is a principle block diagram of the process flow of the present application;

[0055] Figure 2 The figure is an XRD comparative analysis diagram of the product of the present application and standard NH4VO3. DETAILED DESCRIPTION

[0056] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below. In the following description, a lot of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0057] Example 1

[0058] S1, raw material pretreatment and staged crushing

[0059] The waste hydrofining catalyst is staged crushed by a jaw crusher, an impact crusher and an air flow pulverizer in sequence, and a 200-mesh catalyst powder (200-mesh proportion 92%) is screened.

[0060] S2, two-stage roasting pretreatment

[0061] First-stage roasting: temperature 300℃, air-gas solid ratio 7:1, roasting time 2 hours, removing organic matter and moisture;

[0062] Second stage roasting: temperature 700℃, oxygen-rich air (oxygen content 28%) gas-solid ratio 10:1, roasting 2.5 hours;

[0063] Flue gas treatment: after cyclone dust removal, semi-dry desulfurization, SCR denitration, SO2 content in flue gas ≤50mg / m 3 , NO x content ≤100mg / m 3 , dust content ≤10mg / m 3 .

[0064] S3, composite system pressure leaching

[0065] Composite leaching agent is 15% sodium carbonate solution + 2% sodium fluoride + 1% hydrogen peroxide, liquid-solid ratio 10:1, leaching temperature 160℃, pressure 2.0MPa, stirring speed 400r / min, leaching 3 hours; after plate and frame pressure filtration, vanadium leaching rate is 98.3%, Ni, Mo residual rates are 1.2%, 0.8% respectively.

[0066] S4, four-stage deep collaborative impurity removal

[0067] S4.1 Pre-removal of silicon: temperature 70℃, hydrochloric acid is added to adjust pH to 5.0, 0.5% polyaluminum ferric silicate flocculant is added, reaction time 45 minutes, after filtration, Si 4+ content is reduced to below 0.05%;

[0068] S4.2 Sulfide precipitation: temperature 45℃, 12% sodium sulfide solution (stoichiometric 1.5 times) is added, reaction time 75 minutes, after filtration, Ni 2+ , Cu 2+ content is reduced to below 0.001%;

[0069] S4.3 Composite ion exchange: composite ion exchange column (D201:001×7=3:1), flow rate 1.5BV / h, after adsorption, Al 3+ , Fe 3+ , Ca 2+ , Mg 2+ contents are all reduced to below 0.0005%;

[0070] S4.4 Chelate adsorption: amino phosphonic acid type chelate resin column, flow rate 1.2BV / h, after adsorption, Ni 2+ , Mo 6+ contents are reduced to below 1ppm, obtaining vanadium purified liquid.

[0071] S5, seed crystal induction-segmented gradient cooling coupled crystallization

[0072] Seed crystal preparation: 99.9% ammonium metavanadate standard, dissolved in 85℃ ultrapure water, precipitated at 45℃, obtaining 80μm seed crystal;

[0073] Evaporation concentration: 55℃, -0.07MPa, concentrated to vanadium concentration 90g / L;

[0074] Seed crystal induction: 75℃, 0.8% seed crystal was added, stirring at 180r / min for 1.5 hours;

[0075] Stepwise cooling: 75℃→52℃ (1.2℃ / min)→38℃ (0.4℃ / min)→22℃ (0.9℃ / min);

[0076] Centrifugal separation: 3500r / min, to obtain crude ammonium metavanadate crystals, and the crystallization mother liquor was returned to the leaching process.

[0077] S6, recrystallization and precision purification

[0078] Dissolution: 75℃ ultrapure water, to prepare a 22% ammonium metavanadate solution;

[0079] Precision filtration: sequentially filtered through a 0.45μm ceramic membrane and a 0.1μm ultrafiltration membrane;

[0080] Recrystallization: 65℃, -0.08MPa evaporation concentration to 65% of the original volume, cooling to 22℃ at 0.25℃ / min, standing for 2.5 hours;

[0081] Centrifugal washing: 5500r / min, ultrapure water washing 3 times.

[0082] S7, low-temperature vacuum drying and product preparation

[0083] 60℃, -0.09MPa vacuum drying for 3.5 hours, nitrogen protection, crushing and sieving to 250 mesh, to obtain high-purity ammonium metavanadate product.

[0084] S8, comprehensive recovery of by-product metals

[0085] Acid leaching dissolution: 18% sulfuric acid solution, liquid-solid ratio 12:1, 85℃ leaching for 3.5 hours;

[0086] Extraction of molybdenum: TBP volume fraction 25%, phase ratio 1:2.5, extraction for 12 minutes, ammonia back-extraction to obtain ammonium molybdate solution, crystallization and drying to obtain ammonium molybdate product;

[0087] Extraction of tungsten: secondary octanol volume fraction 35%, phase ratio 1:1.5, extraction for 18 minutes, sodium hydroxide back-extraction to obtain sodium tungstate solution, crystallization and drying to obtain sodium tungstate product;

[0088] Precipitation of nickel: pH=9.0, 12% sodium carbonate solution, reaction for 35 minutes, after filtration and washing, calcination to obtain nickel oxide product.

[0089] S9, wastewater recycling and waste heat recovery

[0090] The wastewater is treated by neutralization, flocculation, filtration and reverse osmosis, and the conductivity is 42 μS / cm, which is returned to the leaching process; the waste heat recovery of roasting flue gas produces 0.8 MPa steam, which is used for leaching heating and evaporation concentration, and the energy consumption is reduced by 32%.

[0091] Results of Example 1

[0092] Ammonium metavanadate product indicators: purity 99.92%, Cl - content 0.0012%, Al content 0.0003%, Fe content 0.0002%, Na + content 0.0005%, K + content 0.0004%;

[0093] Total vanadium recovery rate: 97.8%;

[0094] By-product metal recovery rate: Mo: 96.5%, Ni: 95.8%, W: 94.2%;

[0095] Water recycling rate: 92%;

[0096] Energy consumption: reduced by 32% compared with the original patent method.

[0097] (Three) Example 2 (raw material B: waste hydrocracking catalyst)

[0098] According to the process parameters of Example 1, only the following adaptive parameters are adjusted:

[0099] Step S2 second stage roasting temperature: 720℃, roasting time: 2.8 hours;

[0100] Step S3 composite leaching agent: 16% sodium carbonate solution + 2.5% sodium fluoride + 1.2% hydrogen peroxide, leaching temperature: 165℃, pressure: 2.5 MPa;

[0101] Step S8 extraction of tungsten: volume fraction of secondary octanol 38%, phase ratio 1:1.8, extraction time 20 minutes.

[0102] Results of Example 2

[0103] Ammonium metavanadate product indicators: purity 99.89%, Cl - content 0.0015%, Al content 0.0004%, Fe content 0.0003%, Na + content 0.0006%, K + content 0.0005%;

[0104] Total vanadium recovery rate: 97.2%;

[0105] By-product metal recovery rate: Ni: 95.3%, W: 96.7%, Mo: 94.1%;

[0106] Water recycling rate: 91%;

[0107] Energy consumption: reduced by 31% compared with the original patent method.

[0108] (Four) Example 3 (raw material C: waste denitration catalyst)

[0109] According to the process parameters of Example 1, only the following adaptive parameters are adjusted:

[0110] Step S1: grading crushing: screen to get 220 mesh catalyst powder (220 mesh accounts for 93%);

[0111] Step S2: second stage roasting temperature: 730℃, oxygen content of oxygen-enriched air: 30%, roasting time: 3 hours;

[0112] Step S3: composite leaching agent: 17% sodium carbonate solution + 1.8% potassium fluoride + 1.3% sodium hypochlorite, leaching temperature: 155℃, pressure: 1.8MPa;

[0113] Step S8: tungsten extraction: volume fraction of secondary octanol 32%, phase ratio 1:1.6, extraction time 16 minutes.

[0114] Example 3 results

[0115] Ammonium metavanadate product index: purity 99.91%, Cl - content 0.0011%, Al content 0.0002%, Fe content 0.0002%, Na + content 0.0004%, K + content 0.0003%;

[0116] Total vanadium recovery rate: 98.1%;

[0117] By-product metal recovery rate: W: 97.3%, Ni: 94.5%, Mo: 93.8%;

[0118] Water recycling rate: 93%;

[0119] Energy consumption: reduced by 33% compared with the original patent method.

[0120] (Five) Comparative Example (original patent method, raw material A)

[0121] According to the process parameters disclosed in the original patent:

[0122] Crushing the raw material to 150 mesh;

[0123] 550℃ oxidation roasting for 1.5 hours;

[0124] 8% sodium carbonate solution, 130℃, 0.5MPa pressure leaching for 2 hours;

[0125] pH is adjusted to 2.5, 1.0 stoichiometric sodium sulfide is added, and D201 type ion exchange resin is adsorbed;

[0126] Ammonia is used to adjust the pH to 7.5, and evaporation crystallization is carried out at 30 DEG C; and gradient cooling recrystallization (0.8 DEG C / min) is carried out at 60 DEG C to 25 DEG C;

[0127] 0.1 mu m membrane filtration, and vacuum drying at 70 DEG C.

[0128] Comparative example results

[0129] Ammonium metavanadate product index: purity 99.48%, Cl - content 0.008%, Al content 0.0015%, Fe content 0.0012%, Na + content 0.002%, K + content 0.0018%;

[0130] Total vanadium recovery rate: 91.7%;

[0131] By-product metal recovery rate: not recovered, only preliminary separation;

[0132] Water recycling rate: 60%;

[0133] Energy consumption: benchmark value (100%).

[0134] Example and comparative example comparative analysis:

[0135]

[0136] From the comparative results, it can be seen that the improved method has the following significant advantages compared with the original patent:

[0137] Product purity is greatly improved: the product purity reaches 99.89%-99.92%, which is much higher than 99.48% of the original patent, Cl - and other impurity contents are significantly reduced, meeting the use requirements of high-end fields;

[0138] Vanadium recovery rate is significantly improved: the total vanadium recovery rate is increased to 97.2%-98.1%, which is increased by more than 5 percentage points compared with the original patent;

[0139] Multi-metal comprehensive recovery is realized: by-product metals such as Mo, Ni and W are successfully recovered, and the recovery rate is all above 93%, and the resource comprehensive utilization rate is greatly improved;

[0140] Raw material adaptability is wide: various vanadium-containing waste catalysts such as waste hydrofining, hydrocracking and denitration can be efficiently treated, and the original patent is only suitable for waste hydrofining catalyst;

[0141] Better environmental performance: water recycling rate increased to 91%-93%, significantly reducing water consumption, and the treated baking flue gas meets the emission standard;

[0142] Significant energy saving: through waste heat recovery design, energy consumption is reduced by 31%-33%, and the process is more economical;

[0143] Strong process continuity: full-process continuous operation is realized, production efficiency is greatly improved, and it is more suitable for industrial large-scale production.

[0144] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A process for purifying ammonium metavanadate from spent hydrofining catalyst, characterized by, Includes the following steps: S1. Raw material pretreatment and grading crushing: Vanadium-containing waste catalyst is fed into a jaw crusher for coarse crushing to 5-10mm; then fed into an impact crusher for medium crushing to 1-3mm. Finally, the powder is fed into an air jet mill for ultrafine crushing and grading to obtain catalyst powder of 150-250 mesh, of which powder of 180-220 mesh accounts for ≥90%. S2. Two-stage roasting pretreatment: The catalyst powder obtained in step S1 is fed into a rotary kiln for two-stage roasting treatment: S3. Pressure leaching of composite system: The roasted material after step S2 is sent into a high-pressure leaching kettle, and a composite leaching agent is added for pressure leaching. The composite leaching agent is composed mainly of a sodium carbonate solution with a mass concentration of 10%-18%, with the addition of a leaching aid with a mass concentration of 1%-3% and an oxidant with a mass concentration of 0.5%-1.5%. The liquid-to-solid ratio is controlled at 8-12:

1. S4. Four-stage deep synergistic impurity removal: The leachate obtained in step S3 is subjected to four-stage deep impurity removal. The impurity removal steps are as follows: S4.1, pre-silicon removal: adjust the temperature of the leaching solution to 60-80℃, add a hydrochloric acid solution with a mass concentration of 5%-10%, adjust the pH to 4.5-5.5, add a polyaluminum ferric silicate flocculant with a mass of 0.3%-0.8% of the leaching solution, stir for 30-60 minutes, and after standing and settling, filter to remove most of the Si 4 ⁺ impurities, and the filter residue is washed and sent to a hazardous waste disposal center; S4.2, Sulfide precipitation to remove heavy metals: The temperature of the filtrate after pre-desiliconization is controlled at 40-50℃, and sodium sulfide solution is added. The amount of sodium sulfide added is 1.2-1.8 times the stoichiometric amount required to remove Ni²⁺ and Cu²⁺ heavy metal impurities. The mixture is stirred and reacted for 60-90 minutes to generate sulfide precipitate. After filtration, the heavy metal impurities are removed, and the filter residue is sent to the by-product metal recovery unit. S4.3, Composite Ion Exchange for Impurity Removal: The filtrate after sulfide precipitation is fed into a composite ion exchange column, which is filled with a mixture of D201 type strong basic anion exchange resin and 001×7 type strong acid cation exchange resin. The flow rate is controlled at 1-2 BV / h to adsorb and remove residual Al³⁺, Fe³⁺, Ca²⁺, and Mg²⁺ impurities. After the ion exchange column is saturated, it is regenerated with 5%-8% hydrochloric acid solution. The regenerated solution is then treated and recycled. S4.4, chelate adsorption depth impurity removal: the solution after composite ion exchange is sent into a chelate resin column, an amino phosphonic acid type chelate resin is adopted, the flow rate is controlled to be 0.8-1.5 BV / h, trace Ni²⁺ and Mo 6 ⁺ impurities in the solution are removed by adsorption, the content of heavy metal impurities in the solution is ensured to be reduced to below 1 ppm, and a vanadium purified solution is obtained. S5. Seed-induced crystallization-segmented gradient cooling coupled crystallization; the vanadium purification solution obtained in step S4 is subjected to crystallization purification, and the specific crystallization purification steps are as follows; S5.1 Seed preparation: Take ammonium metavanadate standard with a purity ≥99.9%, dissolve it in ultrapure water at 80-90℃ to prepare an ammonium metavanadate solution with a mass concentration of 15%-20%, slowly cool it to 40-50℃, stir to precipitate crystals, and filter to obtain ammonium metavanadate seed crystals with a particle size of 50-100μm; S5.2 Evaporation and Concentration: The vanadium purified solution is fed into a falling film evaporator and concentrated to a vanadium concentration of 80-100 g / L under vacuum conditions of -0.06-0.08 MPa and temperature of 50-60℃. S5.3 Seed-induced crystallization: The concentrated solution is sent into the crystallizer and heated to 70-80℃. 0.5%-1.0% of the concentrated solution mass of ammonium metavanadate seed crystals are added. The stirring rate is controlled at 150-200 r / min. The mixture is stirred at a constant temperature for 1-2 hours to fully disperse the seed crystals and induce crystal growth. S6. Recrystallization and fine purification: The crude ammonium metavanadate crystals obtained in step S5 are recrystallized and purified. S7. Low-temperature vacuum drying and finished product preparation: The refined ammonium metavanadate crystals obtained in step S6 are sent into a vacuum drying oven, and the drying temperature is controlled at 50-70℃, the vacuum degree is -0.08--0.1MPa, and the drying time is 3-4 hours. Nitrogen gas is introduced during the drying process to protect the crystals and prevent oxidation. After drying, the crystals are crushed and sieved to obtain high-purity ammonium metavanadate finished product. S8. Comprehensive recycling of by-product metals; S9. Wastewater recycling and waste heat recovery.

2. The process for purification of ammonium metavanadate from spent hydrofining catalyst as claimed in claim 1 wherein, The first stage of roasting will be carried out at a temperature of 250-350℃, with air introduced as the carrier gas, a gas-solid ratio of 5-8:1, and a roasting time of 1.5-2.5 hours, to remove organic matter, moisture and some volatile sulfate impurities adsorbed on the catalyst surface. ​ The second stage of roasting raises the temperature to 650-750℃, introduces oxygen-enriched air with an oxygen content of 25%-30%, and maintains a gas-solid ratio of 8-12:

1. The roasting time is 2-3 hours, which oxidizes the low-valent vanadium compounds in the catalyst into easily leached high-valent vanadium compounds, while simultaneously converting nickel and molybdenum metals into stable oxide forms.

3. The method for purifying ammonium metavanadate from waste hydrorefining catalyst according to claim 2, characterized in that, The flue gas generated from the two roasting stages is treated by a desulfurization and denitrification system: the flue gas first enters a cyclone dust collector to remove dust, and then enters a semi-dry desulfurization tower, using calcium hydroxide slurry as a desulfurizing agent. The gas then enters the SCR denitrification reactor, which is a selective catalytic reduction denitrification device that uses ammonia water as a reducing agent under the action of a vanadium-titanium catalyst. The treated flue gas is discharged into the atmosphere by an induced draft fan, and the dust is recovered and returned to the roasting process.

4. The method for purifying ammonium metavanadate from waste hydrorefining catalyst according to claim 1, characterized in that, The leaching conditions are: temperature 140-170℃, pressure 1.0-3.0MPa, stirring rate 300-500r / min, and leaching time 2.5-3.5 hours. After leaching, the slurry is fed into a plate and frame filter press for filtration to obtain leachate and leaching residue. The leaching residue is sent to the by-product metal recovery unit, while the leachate enters the subsequent impurity removal process.

5. The method for purifying ammonium metavanadate from waste hydrorefining catalyst according to claim 1, characterized in that, Step S5 also includes: S5.4, Segmented gradient cooling crystallization: A three-segment gradient cooling mode is adopted. First stage: Cooling from 70-80℃ to 50-55℃ at a rate of 1.0-1.5℃ / min, while maintaining a stirring rate of 200-250 r / min to promote rapid crystal nucleation; The second stage involves reducing the temperature from 50-55℃ to 35-40℃ at a rate of 0.3-0.5℃ / min and reducing the stirring rate to 150-200 r / min, which is beneficial for crystal growth and impurity desorption. The third stage: the temperature is reduced from 35-40℃ to 20-25℃ at a rate of 0.8-1.0℃ / min, while the stirring rate is maintained at 150r / min to ensure uniform crystal growth; S5.5 Solid-liquid separation: After crystallization, the slurry is sent to a centrifuge for centrifugal separation to obtain crude ammonium metavanadate crystals and crystallization mother liquor; the crystallization mother liquor is returned to the leaching process for recycling.

6. The method for purifying ammonium metavanadate from waste hydrorefining catalyst according to claim 1, characterized in that, The recrystallization and purification step in step S6 is as follows: S6.1 Dissolution: Add crude ammonium metavanadate crystals to ultrapure water, heat to 70-80℃, stir to dissolve, and prepare an ammonium metavanadate solution with a mass concentration of 20%-25%. S6.2 Precision filtration: The solution is filtered in two stages, passing through a 0.45μm ceramic membrane and a 0.1μm organic ultrafiltration membrane, to remove colloidal impurities and trace mechanical impurities; S6.3 Recrystallization: The filtered solution is sent to a secondary crystallizer, and 0.3%-0.5% of ammonium metavanadate seed crystals by mass of the solution are added. The "constant temperature evaporation-slow cooling" coupling mode is adopted: first, the solution is evaporated and concentrated to 60%-70% of the original volume at 60-70℃ and vacuum degree -0.07--0.09MPa, and then cooled to 20-25℃ at a rate of 0.2-0.3℃ / min, and kept at the same temperature for 2-3 hours. S6.4 Centrifugal Washing: The recrystallized slurry is fed into a high-speed centrifuge and centrifuged to obtain refined ammonium metavanadate crystals. The crystals are washed 2-3 times with ultrapure water to remove impurity ions adsorbed on the surface.

7. The method for purifying ammonium metavanadate from waste hydrorefining catalyst according to claim 6, characterized in that, The specific steps for recovering by-product metals from the leaching residue of step S3 and the sulfide precipitate of step S4.2 are as follows: S8.1 Acid leaching and dissolution: Mix the leaching residue and sulfide precipitate, send them into the acid leaching tank, add sulfuric acid solution with a mass concentration of 15%-20%, the liquid-solid ratio is 10-15:1, heat to 80-90℃, stir and leach for 3-4 hours to dissolve nickel, molybdenum and tungsten metals into the solution, filter to obtain acid leaching solution and acid leaching residue; S8.2 Solvent extraction separation of molybdenum: Adjust the pH of the acid leaching solution to 1.5-2.5, send it into the extraction tank, add a mixed extractant of tributyl phosphate and kerosene at a ratio of 1:2-1:3, stir and extract for 10-15 minutes, let stand to separate the layers, molybdenum enters the organic phase, while nickel and tungsten remain in the aqueous phase; back-extract the organic phase with ammonia water with a mass concentration of 5%-8% to obtain an ammonium molybdate solution, which is then evaporated, crystallized, and dried to obtain the ammonium molybdate product; S8.3 Solvent extraction separation of tungsten: Adjust the pH of the aqueous phase after molybdenum separation to 3.5-4.5, add a mixed extractant of 2-octanol and kerosene at a ratio of 1:1-1:2, stir and extract for 15-20 minutes, allow to stand and separate into layers, and tungsten enters the organic phase; back-extract the organic phase with a 10%-15% sodium hydroxide solution to obtain a sodium tungstate solution, which is then evaporated, crystallized, and dried to obtain the sodium tungstate product; S8.

4. Precipitation and recovery of nickel: Adjust the pH of the aqueous phase after tungsten separation to 8.5-9.5, add a sodium carbonate solution with a mass concentration of 10%-15%, stir and react for 30-40 minutes to generate nickel carbonate precipitate, filter, wash and then calcine to obtain nickel oxide product.

Images