WO2016187993A1 - Method for recovering and disposing waste scr denitrification catalyst - Google Patents

Abstract

A method for recovering and disposing a waste SCR denitrification catalyst. Firstly, pretreating the waste SCR denitrification catalyst to remove impurities, and to activate catalytic components, such as vanadium, tungsten and molybdenum, etc., then leaching the waste SCR denitration catalyst to obtain titanium-rich leach residue and a tungsten-molybdenum-vanadium-containing leachate. Valuable elements in the leachate can be subjected to a resource treatment via two methods: the first method comprises the steps of synchronously purifying the valuable elements in the leachate, then proportionally regulating the content of each substance to prepare a mixture of the catalysis ingredients, and further preparing a new catalyst so as to realize remanufacturing; the second method comprises the steps of separating and purifying each valuable elements in the leachate, thereby preparing different products.

Description

Method for recycling waste SCR denitration catalyst Technical field

The invention belongs to the field of solid waste treatment, and in particular relates to a method for recycling and treating a waste SCR denitration catalyst.

Background technique

China is a country with a large consumption of coal resources. While the combustion of coal brings convenience to residents' lives, it also produces a large amount of nitrogen oxides (NO _x ) and sulfur oxides (SO ₂ ). These nitrogen oxides and sulfur oxides are the main components of atmospheric pollution. On the one hand, they pollute the air environment seriously, and on the other hand, they form acid rain, which brings great hidden dangers to natural water resources. Selective Catalytic Reduction (SCR) is a relatively reliable and simple process for denitrification in recent years. It is usually based on ammonia as a denitrification agent and catalytic reduction of nitrogen oxides under the action of SCR catalyst. It is a non-polluting nitrogen. The SCR catalysts are mainly vanadium tungsten, vanadium molybdenum and vanadium tungsten molybdenum. All of them use V ₂ O ₅ and TiO ₂ as catalytic main bodies. The difference is that vanadium and tungsten catalysts use WO ₃ as an auxiliary agent, vanadium and molybdenum is MoO ₃ as an auxiliary agent, and vanadium tungsten and molybdenum is based on WO ₃ and MoO ₃ act as a co-agent. In the selective catalytic reduction technology, the investment of the catalyst is the core part, and the activity of the catalyst directly determines the efficiency of denitration. The SCR denitration catalyst has a reduced activity during use, and therefore it is necessary to regenerate and activate the catalyst after a certain period of use. However, some SCR catalysts have been severely damaged after repeated activation and use, and it has been difficult to regenerate. These non-renewable catalysts are waste SCR catalysts.

In the "Technical Specification for Selective Catalytic Reduction of Flue Gas Denitration Engineering in Thermal Power Plants" published in 2012, it is mentioned that the treatment method for the honeycomb waste SCR denitration catalyst is crushed landfill. However, the waste SCR catalyst is a dangerous solid waste because it contains toxic metal oxides such as V ₂ O ₅ , WO ₃ or MoO ₃ . If the SCR waste catalyst is disposed of by landfill, it will not only occupy a large amount of land resources, but also environmental pollution. Bringing risks will also create an economic burden on power plants and engineering companies. In fact, WO ₃ , MoO ₃ , V ₂ O ₅ and TiO ₂ contained in the honeycomb waste SCR catalyst are valuable resources. If they can be recovered by means of separation and purification, not only can new profit growth points be generated. It can also achieve good results in the formation of closed loops of various substances in the flue gas denitration industrial chain.

Patent CN104192911A discloses a method for recovering a tungsten trioxide component in a spent SCR denitration catalyst. The slag denitration catalyst is fully pulverized to dry powder. After high-temperature calcination, the tungsten trioxide component in the catalyst is dissolved under a certain condition by using a specific solution, and the tungsten trioxide is effectively separated from other components in the catalyst, and the upper layer containing tungsten is collected. The liquid was evaporated to dryness, and the obtained solid was sufficiently dried, and after high-temperature calcination, recovery of the tungsten trioxide component was completed.

Patent CN104195342A discloses a process for recovering the vanadium pentoxide component of a spent SCR denitration catalyst. Firstly, the reducing agent is used to reduce the pentavalent vanadium in the catalyst to a more soluble tetravalent vanadium in an acidic solution, and then the oxidizing agent further oxidizes the tetravalent vanadium in the acidic solution to pentavalent vanadium by adjusting the pH value of the solution. Under certain conditions, the pentavalent vanadium is fully hydrolyzed and precipitated, and the collected precipitate is calcined to obtain high-purity vanadium pentoxide, and the vanadium pentoxide purity is 98%.

Patent CN103130265A discloses a method for recovering titanium dioxide from a spent SCR denitration catalyst. The dust removal catalyst is firstly dedusted and pulverized, and then concentrated sulfuric acid is added to acidify the solution to obtain a concentrated solution of titanyl sulfate, and then diluted with water; then a nonionic emulsifier is added as a flocculating agent, a sulfonate surfactant. Or a polycarboxylate surfactant as a coagulant, followed by the addition of water-soluble methyl silicone oil; pumped into a plate and frame filter press for pressure filtration, the filtrate is concentrated in vacuo and heated to 90 ° C -98 ° C for 5.5 hours The filtrate is hydrolyzed; then the hydrolyzate is cooled to 40 ° C, vacuum filtration is carried out to deposit metatitanic acid; after rinsing with sand water and deionized water, potassium carbonate or phosphoric acid is added to obtain a metatitanic acid filter cake; After calcination at 500-800 ° C, followed by pulverization and grinding to obtain a finished titanium dioxide.

Patent CN104261415A discloses a process for the complete recovery of silica from spent SCR catalysts. The pulverized waste SCR catalyst is immersed in 3 to 4 volumes of water to remove impurities, and after the impurity removal, the powder is leached with an excess concentration of 60-80% by weight of a concentrated alkali solution, and filtered to obtain solid sodium metasilicate titanate Na ₂ TiO. ₃ , adding sulfuric acid to the filtrate, adjusting the pH to 11.5 to 12.5 at 70-90 ° C, standing for 0.5 to 1 h, filtering off the filter cake; adding the sulfuric acid to the filtrate to adjust the pH to 9-10 For silicic acid, the silicic acid filter cake is heated and stirred at 40-60 ° C for 1 to 2 h with dilute sulfuric acid and oxalic acid mixed acid, filtered, and the filter cake is washed with deionized water to wash away the acid ions contained in the solid, and decomposed by heating to obtain high purity. Silica.

Patent CN104275178A discloses a method for recycling and regenerating an SCR catalyst carrier for a spent SCR denitration catalyst. The waste SCR catalyst is pulverized, sieved, washed with water, and acid washed, and then wet pulverized and ground to obtain a catalyst slurry. The slurry is then mixed with a titanate slurry to obtain a mixed slurry. The mixed slurry is washed with water, filtered, dehydrated, adjusted to pH, and then bleached with a reducing agent. The bleached slurry is added with water, the pH is adjusted, ammonium paratungstate and white carbon black are added, and the catalyst is recovered by stirring, filtering, dehydrating, calcining and pulverizing.

Patent CN104263946A discloses a process for recovering tungsten, vanadium, titanium from an SCR denitration spent catalyst. The SCR spent catalyst is washed, pulverized, sieved, mixed with sodium carbonate and stirred uniformly, and the mixed powder is sintered at a high temperature to obtain a sintered material, which is further leached with water to obtain a mixed solution of sodium salt containing tungsten and vanadium; the pH of the solution is greater than 12 Selective extraction of tungsten, stripping with ammonium salt solution to obtain ammonium tungstate solution; extraction of the raffinate after tungsten extraction of vanadium at a pH of 10 ~ 11.5, stripping with sodium hydroxide solution A sodium vanadate solution containing a small amount of tungsten; titanium is left in the leaching residue to obtain a titanium-rich material.

Patent CN104178636A discloses a method for activating calcination in combination with acid leaching to recover Ti, V, Mo, Si from spent SCR spent catalyst. The treatment steps are as follows: pretreatment of the SCR spent catalyst, followed by high temperature calcination activation. The calcined product was then acid leached to obtain a white TiO ₂ powder. After evaporation of the leachate, a white precipitate of H ₂ MoO _{4 was obtained} . The leachate was added with ammonia to adjust the pH to 8.0 to 9.0 to obtain NH ₄ VO ₃ precipitation. The leachate was further added with ammonia to adjust the pH to 8.0 to 9.0, and then MgCl ₂ was added to obtain MgSiO ₃ . The filtered filtrate enters the wastewater recovery system.

Patent CN104326506A discloses a process for recovering titanium dioxide from a spent denitration catalyst. The method comprises the following steps: (1) grinding the fail-out catalyst into a powder form and placing it in an open container, adding an appropriate amount of distilled water to the open container to prevent the bottom; (2) acid hydrolysis, concentrated sulfuric acid having a mass fraction of 98% Adding to the open container, heating the open container to dissolve the powder, and continuously stirring during heating to make the solid and liquid evenly mixed. When the solution in the open container is brownish yellow, the heating is stopped, and the solution is cooled to ≤ 30 ° C to obtain a titanium liquid; 3) Neutralization, adding a lime milk solution with a mass fraction of 50% to 80% active calcium content of 80% to the titanium liquid, and shaking while dropping, controlling the temperature of the titanium liquid to be ≤70 ° C, after fully reacting Cooling to room temperature; (4) Concentrated hydrolysis, concentration of the neutralized titanium solution to 195-205 g / l, adding seed crystals to heat hydrolysis, filtering, rinsing, drying and calcining to obtain titanium salt.

The above-mentioned existing SCR denitration catalyst recovery treatment technology can not realize the recycling and re-manufacturing of the waste SCR denitration catalyst, and at the same time, the high-efficiency separation of valuable elements such as V, W, Mo and Ti cannot be realized and the vanadium tungsten molybdenum with purity exceeding 99% can be obtained. product. So far, China does not have a set of mature waste SCR catalyst recycling treatment projects. In the final analysis, there is no mature catalyst feasible recycling technology.

Summary of the invention

Based on the reality that the recycling technology of the current waste SCR denitration catalyst is lacking, the present invention proposes a method for re-manufacturing waste SCR denitration catalyst, and separating and recovering valuable components such as vanadium tungsten molybdenum as needed, wherein The recovery rate of valuable metals is over 95%, and the purity of vanadium/tungsten/vanadium molybdenum products is over 99%.

To this end, the present invention employs the following technical solutions:

A method for recycling waste SCR denitration catalyst comprises the following steps:

(1) pretreating the waste SCR denitration catalyst to remove impurities and activate catalytic components such as vanadium tungsten molybdenum;

(2) leaching the waste SCR denitration catalyst obtained after the pretreatment in step (1) to obtain leach residue and leachate;

(3) separating the valuable elements in the leachate obtained in the step (2) to obtain a vanadium extract and a tungsten/molybdenum/tungsten-molybdenum enrichment;

(4) The vanadium extract obtained in the step (3) is further purified for use in preparing a vanadium product; the obtained tungsten/molybdenum/tungsten-molybdenum concentrate is further purified for use in preparing a tungsten/molybdenum/tungsten-molybdenum product.

(5) The valuable elements in the leachate obtained in the step (2) are simultaneously purified, and the ratio of the contents of the respective substances is adjusted to obtain a catalytic component mixture for further preparation into a new SCR denitration catalyst.

Step (1) is an important step of removing impurities in the spent SCR denitration catalyst and activating catalytic components such as vanadium tungsten molybdenum. SCR denitration catalysts carry impurities such as dust, sand and oil during long-term use, which can affect the purity of subsequent products. Further, V ₂ O ₅ , WO ₃ and MoO ₃ in the spent catalyst are poorly soluble. Therefore, the spent catalyst needs to be pretreated to remove the carried impurities and activate the catalytic components such as vanadium tungsten molybdenum. The pretreatment method in the step (1) may be washing, pulverization, calcination, drying, or the like. Washing and drying can remove dust, sand and oil carried by the spent catalyst; pulverization can increase the specific surface area of the spent catalyst; roasting can activate V ₂ O ₅ , WO ₃ , MoO ₃ in the spent catalyst to be easily soluble in water. VO ₄ ^3- , WO ₄ ^2- , MoO ₄ ^2- . In the activation of the calcination, an additive may be added, and the additive may be an alkali metal base or a salt. To save cost, a sodium base or a sodium salt, such as NaOH or Na ₂ CO _{3 ,} etc., is preferred. The molar ratio of the additive to the total amount of metal in the spent catalyst is mdd:mmetal = 1 to 6, such as 1.2, 1.4, 1.6, 1.8, 2.3, 3, 3.8, 4.8, 5.3, and 5.8. The baking temperature is 500 to 900 ° C, for example, 550 ° C, 600 ° C, 650 ° C, 700 ° C, 750 ° C, 800 ° C, and 850 ° C. The calcination time is 1 to 7 h, for example, 1.5 h, 2 h, 3 h, 4 h, 5 h, and 6 h.

Step (2) is the main process for extracting vanadium tungsten molybdenum from the solid phase. The leaching agent can be neutral or acidic or alkaline. If the leaching agent is acidic, other metals such as Ti, other than V, W and Mo, in the spent catalyst will also enter the solution, which makes the composition of the leaching liquid more complicated and increases the difficulty of separation of subsequent components. Therefore, the leaching agent in the present invention is preferably neutral or alkaline. The liquid-solid ratio of the leaching agent to the calcined product is 0.02 to 1 L/g, for example, 0.025 L/g, 0.05 L/g, 0.1 L/g, 0.15 L/g, 0.2 L/g, 0.25 L/g, 0.5 L. /g, 0.75 L/g, and 0.8 L/g, and the like. The leaching temperature is 20 to 200 ° C, for example, 25 ° C, 40 ° C, 60 ° C, 80 ° C, 100 ° C, 120 ° C, 140 ° C, 160 ° C, 180 ° C, and the like. The leaching time may be 0.5 to 5 hours, for example, 0.75h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, and 4.5h. The leaching pressure is 0.1 to 1 MPa, for example, 0.2 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa, and 1.0 MPa. The leaching stirring speed is 100 to 5000 r/min, for example, 400 r/min, 800 r/min, 1200 r/min, 1600 r/min, 2000 r/min, 2400 r/min, 2800 r/min, 3200 r/min, 3600 r/min, 4000 r/ Min, 4400r/min and 4800r/min, etc.

Step (3) is the core operation for separating the valuable elements in the leachate. When the valuable elements in the leachate are extracted by extraction, the extracting agent may be an amine, an organic phosphonic acid, an organic ester, a neutral phosphine, a quaternary ammonium salt and a terpenoid, such as a primary amine N1923, Primene. JMT, Primene 81R and LK-N21, secondary amines DIDA, dioctylamine/n-octane, dioctylamine/carbon tetrachloride, tertiary amines Alamine 336, quaternary ammonium salts Aliquat 336, neutral phosphines TBP, organic Ester acetate amyl acetate and organophosphorus D2EHPA, hydrazine Lix63; extractant concentration is 5% to 30%, for example, 10%, 15%, 20%, and 25%; the initial pH of the aqueous phase is 1 to 9, for example 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, and 8, etc.; extraction temperature is 10 to 40 ° C, for example, 15 ° C, 20 ° C, 25 ° C, 30 ° C, 35 ° C, etc.; extraction time For 10 to 40 minutes, for example, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, etc.; when the organic phase is stripped, the stripping agent can be alkali or ammonia, and the NH ₄ ⁺ or OH ^- and metal in the stripping agent The molar ratio of the amount is mNH ₄ ⁺ /mOH ^{- :} mmetal = 1 to 10, for example, 2, 3, 5, 7, and 9, and the like. Wherein the concentration of the alkali solution is 1 to 10 g/L, for example, 2 g/L, 4 g/L, 6 g/L, 8 g/L, and 9 g/L; and the aqueous ammonia concentration is 5% to 30%, for example, 10%, 15%, 20%, 25% and 28%, etc. The stripping temperature is 20 to 70 ° C, for example, 30, 40, 50, and 60 ° C; the stripping time is 0.5 to 4 h, for example, 1, 1.5, 2, 2.5, 3, and 3.5.

When the valuable elements in the leachate are separated by ion exchange, the resin type is a strongly basic or weakly basic anion exchange resin, for example, D418, D301, etc.; the volume of the leachate is 10 to 100 times the volume of the resin, for example, 20, 30, 40, 50, 60, 70, 80 and 90, etc.; solution pH is 2 to 11, for example, 2, 4, 6, 8, and 9, etc.; temperature is 20 to 90 ° C, for example, 20 ° C, 30 ° C, 40 ° C, 50 ° C, 60 ° C, 70 ° C and 80 ° C, etc.; exchange time is 30 ~ 100min, such as 20min, 40min, 60min and 80min; etc.; resin regeneration liquid is a strong base or weak alkaline solution, such as NaOH, Na ₂ CO ₃ and ammonia water; regeneration time is 20-120 min, for example 30 min, 50 min, 60 min, 70 min, 80 min, 90 min and 110 min; regeneration temperature is 25-90 ° C, for example 30 ° C, 40 ° C, 50 ° C, 60 ° C, 70 ° C and 80 ° C, etc.;

When each valuable element in the leachate is separated by a precipitation method, the precipitating agent is an alkali metal salt or the like, and is, for example, Ca(NO ₃ ) ₂ , CaCl ₂ , Mg(NO ₃ ) ₂ , MgCl ₂ , BaCl _{2 ,} and Ba (NO _{3 ). 2} ; the molar ratio of the precipitant to the total amount of metal in the leachate mpre:mmetal = 1 to 6, for example, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5; etc.; solution pH = 5 to 11, for example 6, 7, 8, 9 and 10; the precipitation temperature is 20-80 ° C, for example 20, 30, 40, 50, 60 and 70 ° C; the precipitation time is 20-120 min, for example 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min and 110 min, etc.;

Step (4) is an important step for further purification of vanadium extract and tungsten/molybdenum/tungsten-molybdenum enrichment to prepare vanadium and tungsten/molybdenum/tungsten-molybdenum products, respectively. Further purification of the vanadium extract is by precipitation, extraction, ion exchange and membrane separation. The ammonium metavanadate precipitate is dissolved, reprecipitated, washed, dried and calcined to obtain a vanadium pentoxide product having a purity of more than 99.5%. The vanadium-containing solution can also be obtained by a high-purity vanadium pentoxide product by an extraction-back extraction vanadium-drying-baking process. The low concentration pure vanadium solution can be concentrated by electrodialysis. The vanadium salt product can also be obtained by extracting vanadium from a low concentration vanadium solution by ion exchange, followed by resin washing regeneration, evaporation crystallization and drying. Further purification of tungsten/molybdenum/tungsten-molybdenum enrichment by precipitation, extraction, ion exchange and membrane separation Wait. The sodium molybdate solution is first extracted with an amine extractant, and then extracted with ammonia water to obtain an ammonium molybdate solution, which is then concentrated by evaporation, washed, dried and calcined to obtain a molybdenum trioxide product. The pure calcium tungstate product can be obtained by dissolving, reprecipitating and drying the calcium tungstate precipitate. The vanadium molybdate solution containing a small amount of vanadium can be removed by a nanofiltration membrane and ion exchange to obtain a pure ammonium molybdate solution. The pure molybdate solution is acidified, evaporated and dried to prepare a molybdic acid product having a purity of more than 99.1%.

Step (5) is a key step in the simultaneous purification of vanadium, tungsten and molybdenum in the leachate. The method for simultaneous purification of the valuable group in the leachate may be coprecipitation, extraction and ion exchange. When the valuable elements in the leachate are simultaneously purified by extraction, the extracting agent may be amines, organic phosphoric acids, organic esters, neutral phosphines, quaternary ammonium salts and anthraquinones, such as primary amines N1923, Primene JMT. ,Primene 81R and LK-N21, secondary amines DIDA, dioctylamine/n-octane, dioctylamine/carbon tetrachloride, tertiary amines Alamine 336, quaternary ammonium salts Aliquat336, neutral phosphines TBP, organic esters Amyl acetate and organophosphorus D2EHPA, anthraquinone Lix63; extractant concentration is 5% to 30%, for example, 10%, 15%, 20%, and 25%; the initial pH of the aqueous phase is 1 to 10, for example, 1.5. , 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, and 9; extraction temperature is 10 to 40 ° C, for example, 15 ° C, 20 ° C, 25 ° C, 30 ° C, 35 ° C, etc.; extraction time For 10 to 40 minutes, for example, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, etc.; when the organic phase is stripped, the stripping agent can be alkali or ammonia, and the NH ₄ ⁺ or OH ^- and metal in the stripping agent The molar ratio of the amount is mNH ₄ ^/ mOH ^{- :} mmetal = 1 to 10, for example, 2, 3, 5, 7, and 9, and the like. Wherein the concentration of the alkali solution is 1 to 10 g/L, for example, 2 g/L, 4 g/L, 6 g/L, 8 g/L, and 9 g/L; and the aqueous ammonia concentration is 5% to 30%, for example, 10%, 15%, 20%, 25% and 28%, etc. The stripping temperature is 20 to 70 ° C, for example, 30, 40, 50, and 60 ° C; the stripping time is 0.5 to 4 h, for example, 1, 1.5, 2, 2.5, 3, and 3.5.

When the valuable elements in the leachate are simultaneously purified by ion exchange, the resin type is a strongly basic or weakly basic anion exchange resin, for example, D418, D301, etc.; the volume of the leachate is 10 to 100 times the volume of the resin, for example, 20, 30, 40, 50, 60, 70, 80, 90, etc.; the pH of the solution is 1 to 12, for example, 2, 4, 6, 8, and 10; the temperature is 10 to 100 ° C, for example, 20 ° C, 30 ° C, 40 ° C, 50 ° C, 60 ° C, 70 ° C, 80 ° C and 90 ° C; exchange time is 30 ~ 120min, such as 20min, 40min, 60min, 80min and 100min; resin regeneration liquid is a strong base or weak alkali solution, For example, NaOH, Na ₂ CO ₃ and ammonia water; regeneration time is 20-120 min, for example 30 min, 50 min, 60 min, 70 min, 80 min, 90 min and 110 min; regeneration temperature is 20-100 ° C, for example 30 ° C, 40 °C, 50 ° C, 60 ° C, 70 ° C, 80 ° C and 90 ° C, and the like.

When the valuable elements in the leachate are simultaneously purified by the coprecipitation method, the precipitating agent is an alkali metal salt or the like, and is, for example, Ca(NO ₃ ) ₂ , CaCl ₂ , Mg(NO ₃ ) ₂ , MgCl ₂ , BaCl _{2 ,} and Ba (NO). ₃ ) ₂ and so on.

Step (5) is also the core step in the preparation of the new SCR denitration catalyst from the catalytic component mixture. The SCR denitration catalyst can be classified into a granular and monolithic catalyst according to its appearance, wherein the monolithic catalyst is further divided into a plate type, a honeycomb type and a corrugated plate catalyst. Most of the particulate catalysts are obtained by fully impregnating the TiO ₂ powder in a precursor solution of ammonium metavanadate and other promoters by an impregnation process, followed by evaporation, drying and calcination. The plate catalyst adopts metal sieve plate as the support, and has good mechanical strength, and is especially suitable for the case of desulfurization of coal-fired high-ash SCR; the honeycomb catalyst is based on the SCR catalyst powder, and is mixed, kneaded, extruded, and dried with a molding aid. And the process of calcination and so on. The corrugated plate catalyst is a corrugated fiberboard as a support, and the surface of the coating is coated with an active component. The active material is 70% less than the honeycomb catalyst. When the surface active material is worn away, the catalytic activity decreases rapidly. Short life. Both honeycomb and plate catalysts are firstly mixed with water, binder, sweller, pore expander, lubricant, glass fiber, etc., using V ₂ O ₅ /TiO ₂ -based SCR catalyst powder as raw material. The plastic paste is then obtained by extrusion molding, drying and calcining the honeycomb catalyst with the plastic paste as a matrix. The plate-shaped catalyst is obtained by uniformly pressing the plastic paste onto a metal sieve plate, followed by drying and calcination to obtain a catalyst. The molar ratio of the total amount of metal in the leachate is mpre:mmetal=1 to 5, for example, 1.5, 2, 2.5, 3, 3.5, 4, and 4.5; and the solution pH = 6 to 12, for example, 7, 8, 9, 10, and 11; the precipitation temperature is 10 to 90 ° C, for example, 20, 30, 40, 50, 60, 70 and 80 ° C; the precipitation time is 10 to 120 min, for example 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min , 90min, 100min and 110min, etc.

Among them, the SCR catalyst powder is prepared by a precipitation method, a dipping method, a mixing method, an ion exchange method, a roll coating method, and a hot melt method. The impregnation method is to impregnate a liquid material containing the active component and the cocatalyst component onto the surface of the solid support. The carrier has high utilization rate, low dosage and low cost, and is widely used for the preparation of supported catalysts, especially for low-content precious metal catalysts; precipitation method is to convert soluble catalyst components into insoluble or insoluble compounds by using a precipitating agent. The process of separating, washing, drying, calcining, molding, etc., to obtain a finished catalyst. It is used for high content of non-precious metals, metal oxides, metal salt catalysts or catalyst carriers; the mixing method is simple, easy to operate, stable in chemical composition, and can be used to prepare high-content multi-component catalysts, especially mixed oxide catalysts. However, the dispersion degree of the method is low; the active component paste is placed in a shakeable container by a roll coating method, and a non-porous carrier ball is placed thereon, and after a period of rolling, the active component gradually adheres to the carrier. surface. Since the active component is easily peeled off, the roll coating method is not commonly used; the ion exchange method uses an exchanger as a carrier to introduce the active component in the form of a counter ion to prepare a highly dispersed, large-surface supported metal or metal ion catalyst, and is particularly suitable. It is prepared by using a low-content, high-utilization precious metal catalyst; the high-temperature melting method is to melt the various components of the catalyst into a uniformly distributed mixture, an oxide solid solution or an alloy solid solution by a high temperature condition to obtain a catalyst with special properties. It is mainly used for the preparation of ammonia synthesis molten iron catalyst, Fischer-Tropsch synthesis catalyst, Lanier framework catalyst and the like.

In general comparison, the present invention preferably produces an SCR catalyst powder by an impregnation method.

When preparing a shaped catalyst such as a plate type and a honeycomb SCR denitration catalyst, the usual molding methods are as follows: (1) Spray molding: the prepared sol or suspension is spray-dispersed in a drying tower by a spray head, and becomes a microsphere after being dried by hot air. Dry gel, particle size range 30 ~ 200 microns; (2) oil column forming: the raw material solution is divided into two ways, into the low pressure nozzle at a certain flow rate ratio, rapidly mixing in the nozzle and forming a sol, After leaving the nozzle, it is dispersed in a small light droplet state in a warm light oil or transformer oil column, and condenses into a hydrogel within a few seconds. The products obtained by spray molding and oil column forming have regular shape, smooth surface and good mechanical strength. (3) Rotary molding: the dry powder is placed in a rotating, inclined 30-60° turntable, sprayed into a misty paste. The cement, the wetted local powder, first bonds to the core. With the continuous movement of the turntable, the core gradually grows into a sphere. The larger sphere has a small coefficient of friction and floats on the surface. When it meets the particle size requirements, it rolls out from the lower edge of the turntable. (4) Extrusion molding: the powder is properly added The binder is formed into a plastically good muddy paste after being kneaded and kneaded. The slurry is forced to pass through the perforated plate by a piston or a spiral, and cut into strips or ring cylinders of almost equal length and the like, and dried and calcined to obtain a product. (5) Tablet molding: Many powder materials are made into a sheet-like cylinder or ring cylinder with uniform shape, uniform size and high mechanical strength.

As a preferred technical solution, the method of the present invention comprises the following steps:

(1) pretreating the waste SCR denitration catalyst to remove impurities and activate catalytic components such as vanadium tungsten molybdenum;

(2) leaching the spent catalyst obtained after the pretreatment in the step (1) to obtain leaching slag and leachate; the leaching agent is neutral or alkaline, and the liquid-solid ratio of the leaching agent to the spent catalyst is 0.02 to 1 L/g, The leaching temperature is 20 to 200 ° C, the leaching pressure is 0.1 to 1 MPa, the leaching time is 0.5 to 5 h, and the stirring speed is 100 to 5000 r/min;

(3) Step (2) Each valuable element in the leachate is separated by an extraction method, an ion exchange method or a precipitation method. In the extraction method, the extracting agent may be an amine, an organic phosphonic acid, an organic ester, a neutral phosphine, a quaternary ammonium salt and a hydrazine, and the concentration of the extracting agent is 5% to 30%, and the initial pH of the aqueous phase is 1 ～. 9, the extraction temperature is 10 ~ 40 ° C, the extraction time is 10 ~ 40min; in the ion exchange method, the resin type is a strong alkaline or weakly basic anion exchange resin, the volume of the leachate is 10 ~ 100 times the volume of the resin, the pH of the solution is 2～11, temperature is 20～90°C, exchange time is 30～100min, resin regeneration liquid is strong alkali or weak alkali solution, regeneration time is 20～120min, regeneration temperature is 25～90°C; precipitation by coprecipitation method The molar ratio of the agent to the total amount of metal in the leachate is mpre:mmetal=1～6, the solution pH=5～11, the precipitation temperature is 20～80°C, and the precipitation time is 20-120 min; the obtained vanadium purified material and the tungsten/molybdenum/tungsten-molybdenum enriched material are further purified to prepare vanadium and tungsten/molybdenum/tungsten-molybdenum products.

Or (4) synchronously purifying the valuable elements in the leachate of step (2), and adjusting the proportion of each substance to prepare a mixture of catalytic components. The valuable elements in the leachate are simultaneously purified by extraction or ion exchange or coprecipitation. In the extraction method, the extracting agent may be an amine, an organic phosphonic acid, an organic ester, a neutral phosphine, a quaternary ammonium salt and a hydrazine, and the concentration of the extracting agent is 5% to 30%, and the initial pH of the aqueous phase is 1 ～. 10, the extraction temperature is 10 ~ 40 ° C, the extraction time is 10 ~ 40min; in the ion exchange method, the resin type is a strong alkaline or weakly basic anion exchange resin, the volume of the leachate is 10 ~ 100 times the volume of the resin, the pH of the solution is 1～12, temperature is 10～100°C, exchange time is 30～120min, resin regeneration liquid is strong alkali or weak alkali solution, regeneration time is 20～120min, regeneration temperature is 20～100°C; precipitation by coprecipitation method The molar ratio of the agent to the total amount of metal in the leachate is mpre:mmetal=1～5, the solution pH=6～12, the precipitation temperature is 10-90° C., and the precipitation time is 10-120 min;

(5) The catalytic component mixture described in the step (3) is prepared into a new granular SCR denitration catalyst powder by an impregnation method. The catalytic component mixture is first dissolved in an oxalic acid solution of 0.1 to 0.2 mol/L, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 2 to 4 hours. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness is placed in a drying oven at 105 to 110 ° C for 12 to 24 hours. The dried solid mixture is ground into a powder, and then placed in a muffle furnace for calcination at a calcination temperature of 400 to 600 ° C and a calcination time of 5 to 12 h. The calcined product is a new granular SCR denitration catalyst powder.

Compared with the prior art solutions, the present invention has the following beneficial effects:

1. The method of the invention truly realizes the new catalyst which is re-manufactured to be highly active while the waste SCR denitration catalyst is harmlessly treated, and has good environmental and economic benefits;

2. The method of the present invention can separate valuable elements such as V, Mo and W in the waste SCR catalyst. And the recovery and recovery, the recovery of V, Mo and W are more than 95%, and the purity of the prepared vanadium/tungsten/molybdenum/tungsten-molybdenum product is over 99%.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a process flow diagram of the method of the present invention.

The invention is further described in detail below. However, the following examples are merely illustrative of the invention and are not intended to limit the scope of the invention, and the scope of the invention is defined by the appended claims.

detailed description

The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

In order to better explain the present invention, it is convenient to understand the technical solution of the present invention, and a typical but non-limiting embodiment of the present invention is as follows:

Example 1

The waste vanadium molybdenum-based SCR denitration catalyst provided by a laboratory has a V ₂ O ₅ content of 1.1%, a MoO ₃ content of 3.3%, and a TiO _{2 content} of 95.3%.

(1) 10 g of the above spent catalyst was taken, firstly washed to 100 mesh, washed with water, filtered, and dried at 105 °C. The dried spent catalyst was added with NaOH as an additive, and the molar ratio of NaOH to the total amount of metal in the spent catalyst was mdd:mmetal=1. After mixing uniformly, it is placed in a muffle furnace and calcined at a calcination temperature of 650 ° C and a calcination time of 4 h;

(2) Neutral pure water is used as the leaching agent, and V and Mo are leached from the spent catalyst after calcination in the step (1), the liquid-solid ratio is 0.02 L/g, the leaching temperature is 20 ° C, the leaching pressure is 0.1 MPa, and the leaching is performed. The time is 1.5h, the stirring speed is 1000r/min, the V single-stage leaching rate is 78.6%, and the Mo is 75.7%; the leaching residue returns to the step (1);

(3) The extraction system consisting of primary amine extractant N1923 and toluene is organic phase, the concentration is 5%, the initial pH of the aqueous phase is 1, the ratio is O/A=1, the extraction temperature is 10 °C, and the extraction time is V and Mo were simultaneously extracted from the leachate described in the step (2) under the conditions of 10 min, the V extraction rate was 100%, and the Mo extraction rate was 99.99%. Then, the V and Mo in the extract phase are simultaneously back-extracted with 5% ammonia water to obtain a mixed vanadium-molybdenum ammonium salt solution, wherein the molar ratio of the added ammonium ion to the total amount of the metal in the organic phase is mNH ₄ ^{+ :} mmetal=1, The temperature was 20 ° C and the stripping time was 0.5 h. Adjusting the ratio of V and Mo in the mixed vanadium-molybdenum ammonium salt solution, and then evaporating, crystallizing, washing and drying at 50 ° C to obtain a vanadium-molybdenum mixed ammonium salt;

(4) The extraction system consisting of primary amine extractant N1923 and toluene is organic phase, the concentration is 5%, the initial pH of the aqueous phase is 6, the ratio of O/A=1, the extraction temperature is 10 °C, the extraction time V and Mo were extracted and separated from the leachate described in the step (2) under the conditions of 10 min, the V extraction rate was 100%, and the Mo extraction rate was 0.5%, and a vanadium-rich organic phase and a molybdenum-containing raffinate were obtained. The vanadium-rich organic phase is back-extracted with 10% aqueous ammonia, wherein the molar ratio of ammonium ions added to the total amount of metal in the organic phase is mNH ₄ ^{+ :} mmetal=3, the stripping temperature is 40 ° C, and the stripping time is 1 h. Obtaining ammonium metavanadate precipitation;

(5) The vanadium molybdenum mixed ammonium salt obtained in the step (3) is first dissolved in a 0.2 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 2 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 110 ° C for 12 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 400 ° C and a calcination time of 5 h. The calcined product is a granular 1.2% V ₂ O ₅ -3.5% MO ₃ /TiO ₂ -based SCR denitration catalyst;

(6) The ammonium metavanadate precipitate obtained in the step (4) is first dissolved with nitric acid, and then the solution is adjusted to pH=7, and then ammonium sulfate is precipitated, and the obtained ammonium metavanadate precipitate is washed, dried and calcined to obtain a pentoxide. The vanadium product has a purity of 99.5%; the molybdenum-containing raffinate obtained in the step (4) is adjusted to pH=1.5 with nitric acid, and then crystallized by evaporation, washed and dried to obtain a molybdic acid product having a purity of 99.1%.

Example 2

The waste vanadium molybdenum-based SCR denitration catalyst provided by a laboratory has a V ₂ O ₅ content of 1.4%, a MoO ₃ content of 3.2%, and a TiO _{2 content} of 95%.

(1) 5 g of the above spent catalyst was taken, firstly washed to 100 mesh, washed with water, filtered, and dried at 105 °C. The dried spent catalyst is added with NaOH as an additive, and the molar ratio of NaOH to the total amount of metal in the spent catalyst is mdd:mmetal=2. After mixing uniformly, it is placed in a muffle furnace and calcined at a calcination temperature of 680 ° C and a calcination time of 5 h;

(2) Neutral pure water is used as the leaching agent, and V and Mo are leached from the spent catalyst after calcination in the step (1), the liquid-solid ratio is 0.06 L/g, the leaching temperature is 60 ° C, the leaching pressure is 0.1 MPa, and the leaching is performed. The time is 2h, the stirring speed is 800r/min, the V single-stage leaching rate is 79.6%, and the Mo is 77.4%; the leaching residue returns to the step (1);

(3) The extraction system consisting of secondary amine extractant dioctylamine and n-octane is organic phase, the concentration is 15%, the initial pH of the aqueous phase is 3, the ratio of O/A=1 is 2, and the extraction temperature is 20 °C. The extraction time was 15 min, and V and Mo were simultaneously extracted from the leachate of step (2). The extraction rate of V was 99.6%, and the extraction rate of Mo was 98.8%. Then, 10% ammonia water is used to synchronously strip V and Mo in the extracted phase to obtain a mixed vanadium molybdenum ammonium salt solution, wherein the molar ratio of the added ammonium ions to the total amount of metals in the organic phase is mNH ₄ ^{+ :} mmetal=4, The temperature was 45 ° C and the stripping time was 3 h. Adjusting the ratio of V and Mo in the mixed vanadium-molybdenum ammonium salt solution, and then evaporating, crystallizing, washing and drying at 55 ° C to obtain a vanadium-molybdenum mixed ammonium salt;

(4) The extraction system consisting of secondary amine extractant dioctylamine and n-octane is organic phase, the concentration is 15%, the initial pH of the aqueous phase is 5, the ratio of O/A=1, the extraction temperature is 25 °C. The extraction time was 25 min, and V and Mo were extracted and extracted from the leachate of step (2). The extraction rate of V was 99.5%, and the extraction rate of Mo was 0.12%, and a vanadium-rich organic phase and a molybdenum-containing raffinate were obtained. The vanadium metavanadate was precipitated by the reverse extraction of vanadium-rich organic with 15% ammonia water. The molar ratio of ammonium ion added to the total amount of metal in the organic phase was mNH ₄ ^{+ :} mmetal=10, and the stripping temperature was 70 °C. The time is 4h;

(5) The vanadium molybdenum mixed ammonium salt obtained in the step (3) is first dissolved in a 0.15 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 2.5 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 105 ° C for 15 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 450 ° C and a calcination time of 6 h. The calcined product was a particulate 1.1% V ₂ O ₅ -3.1% MO ₃ /TiO ₂ -based SCR denitration catalyst.

(6) The ammonium metavanadate precipitate obtained in the step (4) is first dissolved with nitric acid, and then the solution is adjusted to pH=7.5, then ammonium nitrate is added to precipitate vanadium, and the obtained ammonium metavanadate precipitate is washed, dried and calcined to obtain pentoxide. The vanadium product has a purity of 99.6%; the molybdenum-containing raffinate obtained in the step (4) is adjusted to pH=1.2 with nitric acid, and then crystallized by evaporation, washed and dried to obtain a molybdic acid product having a purity of 99.2%.

Example 3

The waste vanadium-tungsten SCR denitration catalyst provided by a laboratory has a V ₂ O ₅ content of 1.5%, WO ₃ of 3.3%, and TiO ₂ of 95%.

(1) 10 g of the above spent catalyst was taken, firstly washed to 100 mesh, washed with water, filtered, and dried at 105 °C. The dried spent catalyst was added with Na ₂ CO ₃ as an additive, and the molar ratio of Na ₂ CO ₃ to the total amount of metal in the spent catalyst was Madd:mmetal=6. After mixing uniformly, it is placed in a muffle furnace for calcination, the calcination temperature is 500 ° C, and the calcination time is 7 h;

(2) Neutral pure water is used as the leaching agent, and V and W are leached from the spent catalyst after calcination in step (1), the liquid-solid ratio is 0.05 L/g, the leaching temperature is 70 ° C, the leaching pressure is 0.1 MPa, and the leaching is performed. The time is 1.5h, the stirring speed is 1200r/min, the V single-stage leaching rate is 79.6%, W is 76.4%; the leaching residue returns to step (1);

(3) The extraction system consisting of tertiary amine extractant Alamine 336 and kerosene is organic phase, the concentration is 25%, the initial pH of the aqueous phase is 4, the ratio of O/A=1, the extraction temperature is 40 °C, extraction The V and W were simultaneously extracted from the leachate of step (2) under the condition of 40 min, the V extraction rate was 98.6%, and the W extraction rate was 99.6%. Then, the V and W in the extracted phase are simultaneously back-extracted with 20% ammonia water to obtain a mixed solution of vanadium and tungsten mixed ammonium salt, wherein the molar ratio of the added ammonium ion to the total amount of the metal in the organic phase is mNH ₄ ^{+ :} mmetal=6, and the extraction is carried out. The temperature was 50 ° C and the stripping time was 3 h. Adjusting the ratio of V and W in the vanadium-tungsten mixed ammonium salt solution, and then evaporating, crystallizing, washing and drying at 48 ° C to obtain a vanadium-tungsten mixed ammonium salt;

(4) The extraction system consisting of tertiary amine extractant Alamine 336 and kerosene is organic phase, the concentration is 25%, the initial pH of the aqueous phase is 1.0, the ratio of O/A=1, the extraction temperature is 25 °C, extraction The V and W were separated and extracted from the leachate of step (2) under the condition of 20 min, the V extraction rate was 100%, and the W extraction rate was 0.2%, and a vanadium-rich organic phase and a tungsten-containing raffinate were obtained. The vanadium-rich organic solution was reversely extracted with a 1 g/L NaOH solution, wherein the molar ratio of the added OH- to the total amount of metal in the organic phase was mOH-:mmetal=10, the stripping temperature was 70 ° C, and the stripping time was 4 h. Sodium vanadate solution;

(5) The vanadium-tungsten mixed ammonium salt obtained in the step (3) is first dissolved in a 0.16 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 3 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 106 ° C for 16 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 500 ° C and a calcination time of 5.5 h. The calcined product is a granular 1.2% V ₂ O ₅ -3.0% WO ₃ /TiO ₂ -based SCR denitration catalyst;

(6) The sodium vanadate solution obtained in the step (4) is adjusted to pH=8, and ammonium sulfate precipitation is added, and the obtained ammonium metavanadate precipitate is washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.5%; (4) The obtained tungsten-containing raffinate was adjusted to pH = 1.0 with nitric acid, and then crystallized by evaporation, washed and dried to obtain a tungstic acid product having a purity of 99.0%.

Example 4

The waste vanadium-tungsten SCR denitration catalyst provided by a laboratory has a V ₂ O ₅ content of 1.3%, WO ₃ of 3.2%, and TiO ₂ of 95.2%.

(1) Take 10g of the above spent catalyst, first to 100 mesh, washed with water, filtered, at 105 ° C Dry down. The dried spent catalyst was added with NaCl as an additive, and the molar ratio of NaCl to the total amount of metal in the spent catalyst was Madd:mmetal=4.5. After mixing uniformly, it is placed in a muffle furnace for calcination, the calcination temperature is 700 ° C, and the calcination time is 4 h;

(2) Neutral pure water is used as the leaching agent, and V and W are leached from the spent catalyst after calcination in the step (1), the liquid-solid ratio is 0.1 L/g, the leaching temperature is 80 ° C, the leaching pressure is 0.2 MPa, and the leaching is performed. The time is 3h, the stirring speed is 5000r/min, the V single-stage leaching rate is 78.8%, W is 75.9%; the leaching residue returns to step (1);

(3) The extraction system consisting of quaternary ammonium salt Aliquat 336 and kerosene is organic phase, the concentration is 25%, the initial pH of the aqueous phase is 3, the ratio of O/A=1, the extraction temperature is 30 °C, and the extraction time is The V and W were simultaneously extracted from the leachate of step (2) under the conditions of 30 min, the V extraction rate was 98.7%, and the W extraction rate was 98.90%. Then, the V and W in the extracted phase are simultaneously back-extracted with 20% ammonia water to obtain a vanadium-tungsten mixed ammonium salt solution, wherein the molar ratio of the added ammonium ion to the total amount of the metal in the organic phase is mNH ₄ ^{+ :} mmetal=5, and the extraction is carried out. The temperature was 45 ° C and the stripping time was 3 h. Adjusting the ratio of V and W in the vanadium-tungsten mixed ammonium salt solution, and then evaporating, crystallizing, washing and drying at 45 ° C to obtain a vanadium-tungsten mixed ammonium salt;

(4) The extraction system consisting of quaternary ammonium salt Aliquat 336 and kerosene is organic phase, the concentration is 25%, the initial pH of the aqueous phase is 9.0, the ratio of O/A=1, the extraction temperature is 40 °C, and the extraction time is The V and W were separated from the leachate of step (2) under the condition of 40 min, the V extraction rate was 0.2%, and the W extraction rate was 99.6%, and the tungsten-rich organic phase and the vanadium-containing raffinate were obtained. The tungsten-rich organic phase was reversely extracted with 10 g/L NaOH solution, wherein the molar ratio of OH- to the total amount of metal in the organic phase was mOH ^{- :} mmetal=5, the stripping temperature was 30 ° C, and the stripping time was 0.5 h. Obtaining a sodium tungstate solution;

(5) The vanadium-tungsten mixed ammonium salt obtained in the step (3) is first dissolved in a 0.2 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 4 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 110 ° C for 18 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 550 ° C and a calcination time of 7 h. The calcined product is a granular 1.3% V ₂ O ₅ -3.4% WO ₃ /TiO ₂ -based SCR denitration catalyst;

(6) The sodium tungstate solution obtained in the step (4) is adjusted to pH=1.5 with nitric acid, and then crystallized by evaporation, washed, dried and calcined to obtain a tungsten trioxide product having a purity of 99.2%; and vanadium obtained in the step (4). The raffinate was adjusted to pH=7.2, then ammonium chloride was added to precipitate vanadium, and the obtained ammonium metavanadate precipitate was washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.6%.

Example 5

The waste vanadium-tungsten-based SCR denitration catalyst provided by a laboratory has a V ₂ O ₅ content of 1.3%, WO ₃ of 2.4%, and TiO ₂ of 96.1%.

(1) 5 g of the above spent catalyst was taken, firstly washed to 100 mesh, washed with water, filtered, and dried at 110 °C. The dried spent catalyst was added with Na ₂ SO ₄ as an additive, and the molar ratio of Na ₂ SO ₄ to the total amount of metal in the spent catalyst was Madd:mmetal=5.5. After mixing uniformly, it is placed in a muffle furnace for calcination, the calcination temperature is 800 ° C, and the calcination time is 5 h;

(2) Using 1 g/L NaOH solution as the leaching agent, leaching V and W from the spent catalyst after calcination in step (1), the liquid-solid ratio is 0.2 L/g, the leaching temperature is 100 ° C, the leaching pressure is 0.2 MPa, and the leaching time is 4h, the stirring speed is 2000r/min, the V single-stage leaching rate is 81.7%, W is 77.2%; the leaching residue returns to the step (1);

(3) The extraction system consisting of neutral phosphine extractant TBP and kerosene is organic phase, the concentration is 30%, the initial pH of the aqueous phase is 6, the ratio is O/A=1, the extraction temperature is 30 °C, extraction The V and W were simultaneously extracted from the leachate under the condition of 35 min, the V extraction rate was 99.0%, and the W extraction rate was 97.6%. Then, the V and W in the extracted phase are simultaneously back-extracted with 30% ammonia water to obtain a mixed solution of vanadium and tungsten mixed ammonium salt, wherein the molar ratio of the added ammonium ion to the total amount of metal in the organic phase is mNH ₄ ^{+ :} mmetal=6, and the extraction is carried out. The temperature was 50 ° C and the stripping time was 4 h. Adjusting the ratio of V and W in the vanadium-tungsten mixed ammonium salt solution, and then evaporating, crystallizing, washing and drying at 50 ° C to obtain a vanadium-tungsten mixed ammonium salt;

(4) The extraction system consisting of neutral phosphine extractant TBP and kerosene is organic phase, the concentration is 30%, the initial pH of the aqueous phase is 2.5, the ratio is O/A=1, the extraction temperature is 30 °C, extraction V and W were extracted and extracted from the leachate under the condition of 35 min. The extraction rate of V was 99.8%, and the extraction rate of W was 0.3%, and a vanadium-rich organic phase and a tungsten-containing raffinate were obtained. The vanadium-rich organic phase is back-extracted with 5 g/L NaOH solution, wherein the molar ratio of OH ^- to the total amount of metal in the organic phase is mOH ^{- :} mmetal = 4.5, the stripping temperature is 35 ° C, and the stripping time is 1 h to obtain vanadic acid. Sodium solution;

(5) The vanadium-tungsten mixed ammonium salt obtained in the step (3) is first dissolved in a 0.2 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 3 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 110 ° C for 24 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 600 ° C and a calcination time of 12 h. The calcined product is a granular 1.4% V ₂ O ₅ -3.0% WO ₃ /TiO ₂ -based SCR denitration catalyst;

(6) The sodium vanadate solution obtained in the step (4) is adjusted to pH=9, and then vanadium nitrate is added, and the obtained ammonium metavanadate precipitate is washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.5%. The tungsten-containing raffinate was adjusted to pH=6.2, and then the tungsten was extracted again by extraction. The extraction system consisting of neutral phosphine extractant TBP and kerosene is organic phase, the concentration is 15%, the two ratios are O/A=1, the extraction temperature is 30 °C, the extraction time is 30 min, and the W extraction rate is 99.5%. The tungsten-rich organic phase is back-extracted with 30% ammonia water, wherein the molar ratio of the added ammonium ion to the total amount of metal in the organic phase is mNH ₄ ^{+ :} mmetal=5, the stripping temperature is 35 ° C, and the stripping time is 2 h, and the obtained tungsten is obtained. The ammonium acid solution was crystallized by evaporation, washed and dried to give an ammonium paratungstate product having a purity of 99.3%.

Example 6

The waste vanadium-tungsten-molybdenum SCR denitration catalyst provided by a laboratory has a V ₂ O ₅ content of 1.3%, WO ₃ of 1.4%, MoO ₃ of 1.4%, and TiO ₂ of 95.7%.

(1) 5 g of the above spent catalyst was taken, firstly washed to 100 mesh, washed with water, filtered, and dried at 105 °C. The dried spent catalyst was added with NaNO ₃ as an additive, and the molar ratio of NaNO ₃ to the total amount of metal in the spent catalyst was Madd:mmetal=6. After mixing uniformly, it is placed in a muffle furnace for calcination, the calcination temperature is 900 ° C, and the calcination time is 7 h;

(2) Using 1 g/L NaOH solution as the leaching agent, leaching V, W and Mo from the spent catalyst after calcination in step (1), the liquid-solid ratio is 0.3 L/g, the leaching temperature is 100 ° C, and the leaching pressure is 0.4 MPa. The leaching time is 5h, the stirring speed is 3000r/min, the V single-stage leaching rate is 81.7%, W is 77.2%; the leaching residue returns to step (1);

(3) The extraction system consisting of organic esters of amyl acetate and kerosene is organic phase, the concentration is 25%, the initial pH of the aqueous phase is 10, the ratio of O/A=1, the extraction temperature is 40 °C, the extraction time The V, W and Mo were simultaneously extracted from the leachate of step (2) under the condition of 40 min, the V extraction rate was 99.6%, the W extraction rate was 98.6%, and the Mo extraction rate was 97.8%. Then, the V, W and Mo in the extracted phase are synchronously back-extracted with 15% ammonia water to obtain a mixed solution of vanadium-tungsten-molybdenum mixed ammonium salt, wherein the molar ratio of the added ammonium ions to the total amount of metals in the organic phase is mNH ₄ ^{+ :} mmetal=5 The stripping temperature was 45 ° C and the stripping time was 2 h. Adjusting the ratio of V, W and Mo in the vanadium-tungsten-molybdenum mixed ammonium salt solution, and then evaporating, crystallizing, washing and drying at 45 ° C to obtain a vanadium-tungsten-molybdenum mixed ammonium salt;

(4) The extraction system consisting of organic esters of amyl acetate and kerosene is organic phase, the concentration is 25%, the initial pH of the aqueous phase is 3.2, the ratio of O/A=1, the extraction temperature is 40 °C, the extraction time V, W and Mo were separated and extracted from the leachate of step (2) under the condition of 40 min, the extraction rate of V was 100%, and the extraction ratio of W and Mo was less than 0.2%, and a vanadium-rich organic phase and a tungsten-containing molybdenum raffinate were obtained. The vanadium-rich organic phase was reversely extracted with 15% ammonia water, wherein the molar ratio of ammonium ions added to the total amount of metal in the organic phase was mNH ₄ ^{+ :} mmetal=4, the stripping temperature was 40 ° C, and the stripping time was 2.5 h. Ammonium metavanadate precipitation;

(5) The vanadium-tungsten-molybdenum mixed ammonium salt obtained in the step (3) is first dissolved in a 0.2 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 4 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 110 ° C for 24 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 600 ° C and a calcination time of 10 h. The calcined product is a granular 1.4% V ₂ O ₅ -1.2% WO ₃ -1.2% MoO ₃ /TiO ₂ -based SCR denitration catalyst;

(6) The ammonium metavanadate precipitate obtained in the step (4) is washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.3%; and the tungsten-containing molybdenum raffinate obtained in the step (4) is adjusted to have a pH of 2, It is then subjected to evaporation, washing, drying and calcination to obtain a mixture of molybdenum trioxide and tungsten trioxide having a purity of 99.0%.

Example 7

The waste vanadium molybdenum-based SCR denitration catalyst provided by a laboratory has a V ₂ O ₅ content of 1.2%, a MoO ₃ of 2.5%, and a TiO ₂ of 96%.

(1) taking 5 g of the above spent catalyst, firstly pulverized to 100 mesh, washed with water, filtered, and dried at 105 ° C;

(2) Using 2g/L NaOH solution as leaching agent, leaching V and Mo from the spent catalyst after drying in step (1), the liquid-solid ratio is 0.5L/g, the leaching temperature is 200°C, the leaching pressure is 1MPa, and the leaching time is 5h, the stirring speed is 5000r/min, the V single-stage leaching rate is 84.1%, Mo is 80.1%; the leaching residue returns to the step (1);

(3) The extraction system consisting of organic phosphine D2EHPA and kerosene is organic phase, the concentration is 15%, the initial pH of the aqueous phase is 8.5, the ratio of O/A=1, the extraction temperature is 30 °C, and the extraction time is 30 min. The V and Mo were simultaneously extracted from the leachate in step (2) under the conditions of V. The extraction rate of V was 99.8%, and the extraction rate of Mo was 98.9%. Then, the V and Mo in the extracted phase are simultaneously back-extracted with 20% ammonia water to obtain a mixed vanadium-molybdenum ammonium salt solution, wherein the molar ratio of the added ammonium ions to the total amount of metals in the organic phase is mNH ₄ ^{+ :} mmetal=6, and the anti-extraction The temperature was 30 ° C and the stripping time was 2.5 h. Adjusting the ratio of V and Mo in the mixed vanadium-molybdenum ammonium salt solution, and then evaporating, crystallizing, washing and drying at 40 ° C to obtain a vanadium-molybdenum mixed ammonium salt;

(4) The extraction system consisting of organic phosphine D2EHPA and kerosene is organic phase, the concentration is 15%, the initial pH of the aqueous phase is 2, the ratio of O/A=1, the extraction temperature is 30 °C, and the extraction time is 30 min. Under the condition of extraction, V and Mo were separated and extracted from the leachate of step (2), the extraction rate of V was 0.1%, and the extraction rate of Mo was 99.9%, and a molybdenum-rich organic phase and a vanadium-containing raffinate were obtained. The chromium-rich organic phase was reversely extracted with a 1 g/L NaOH solution, wherein the molar ratio of the added OH ^- to the total amount of metal in the organic phase was mOH ^{- :} mmetal = 5, the stripping temperature was 30 ° C, and the stripping time was 0.5 h. Obtaining a sodium molybdate solution;

(5) The vanadium molybdenum mixed ammonium salt obtained in the step (3) is first dissolved in a 0.1 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 4 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 110 ° C for 24 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 600 ° C and a calcination time of 9 h. The calcined product is a granular 1.5% V ₂ O ₅ -2.6% MO ₃ /TiO ₂ -based SCR denitration catalyst;

(6) The sodium molybdate solution obtained in the step (4) is crystallized by evaporation, washed and dried to obtain a sodium molybdate product having a purity of 99.5%; the vanadium-containing raffinate obtained in the step (4) is first adjusted to pH=8.5, and then After adding ammonium sulfate to form vanadium, the obtained ammonium metavanadate precipitate was washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.6%.

Example 8

The waste vanadium molybdenum-based SCR denitration catalyst provided by a laboratory has a V ₂ O ₅ content of 1.5%, a MoO ₃ of 2.3%, and a TiO ₂ of 96.1%.

(1) taking 5 g of the above spent catalyst, firstly pulverized to 100 mesh, washed with water, filtered, and dried at 105 ° C;

(2) Using 5g/L NaOH solution as leaching agent, leaching V and Mo from the spent catalyst after drying in step (1), the liquid-solid ratio is 0.6L/g, the leaching temperature is 150°C, the leaching pressure is 0.5MPa, and the leaching time is 5h, the stirring speed is 5000r/min, the V single-stage leaching rate is 80.1%, Mo is 81.1%; the leaching residue returns to the step (1);

(3) The extraction system consisting of hydrazine extractant Lix63 and kerosene is organic phase, the concentration is 30%, the initial pH of the aqueous phase is 6, the ratio is O/A=1, the extraction temperature is 40 °C, and the extraction time is V and Mo were simultaneously extracted from the leachate of step (2) under the condition of 40 min, the extraction rate of V was 98.7%, and the extraction rate of Mo was 98.9%. Then, the V and Mo in the extract phase are simultaneously back-extracted with 20% ammonia water to obtain a mixed vanadium-molybdenum ammonium salt solution, wherein the molar ratio of the added ammonium ion to the total amount of metal in the organic phase is mNH ₄ ^{+ :} mmetal=5, stripping The temperature was 20 ° C and the stripping time was 3 h. Adjusting the ratio of V and Mo in the mixed vanadium-molybdenum ammonium salt solution, and then evaporating, crystallizing, washing and drying at 40 ° C to obtain a vanadium-molybdenum mixed ammonium salt;

(4) The extraction system consisting of hydrazine extractant Lix63 and kerosene is organic phase, the concentration is 30%, the initial pH of the aqueous phase is 2, the ratio of O/A=1, the extraction temperature is 40 °C, and the extraction time is V and Mo were extracted and separated from the leachate under the condition of 40 min. The extraction rate of V was 99.7%, and the extraction rate of Mo was 0.4%. The vanadium-rich organic phase and the molybdenum-containing raffinate were obtained. The vanadium-rich organic phase is back-extracted with 15% ammonia water, wherein the molar ratio of ammonium ions added to the total amount of metal in the organic phase is mNH ₄ ^{+ :} mmetal=5, the stripping temperature is 45 ° C, and the stripping time is 2.5 h to obtain vanadium Ammonium phosphate precipitation;

(5) The vanadium molybdenum mixed ammonium salt obtained in the step (3) is first dissolved in a 0.1 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 4 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 110 ° C for 24 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 600 ° C and a calcination time of 9 h. The calcined product is a granular 1.4% V ₂ O ₅ -2.2% MO ₃ /TiO ₂ based SCR denitration catalyst;

(6) The ammonium metavanadate precipitate obtained in the step (4) is washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.7%; the molybdenum-containing raffinate obtained in the step (4) is adjusted to pH=1, and then Crystallization by evaporation, washing, drying and calcination gave a molybdenum trioxide product with a purity of 99.4%.

Example 9

The waste vanadium-tungsten-based SCR catalyst provided by a laboratory has a V ₂ O ₅ content of 1.2%, a WO ₃ of 3.3%, and a TiO ₂ of 95.3%.

(1) taking 50 g of the above spent catalyst, firstly pulverized to 100 mesh, washed with water, filtered and dried at 105 ° C;

(2) Using 2 g/L sodium hydroxide solution as the leaching agent, leaching V and W from the spent catalyst dried in the step (1), the liquid-solid ratio is 1 L/g, the leaching temperature is 200 ° C, and the leaching pressure is 1 MPa. , the leaching time is 5h, the stirring speed is 100r/min, the V single-stage leaching rate is 77.2%, W is 75.6%; the leaching slag is subjected to secondary leaching;

(3) The leachate obtained in step (2) is adjusted to pH=6 with nitric acid, and then coprecipitated by adding calcium nitrate. The molar ratio of calcium nitrate to the total amount of metal in the leachate is mpre:mmetal=1, the reaction temperature is 10 ° C, and the precipitation time is At 10 min, a mixture of calcium vanadate and calcium tungstate was obtained. The mixed precipitate was dissolved in nitric acid, and the solution was adjusted to pH=6, and then co-precipitated by adding calcium nitrate, and the obtained precipitate was washed and dried to be a pure vanadium-tungsten mixed calcium salt. The vanadium-tungsten mixed calcium salt was dissolved with nitric acid and the solution was adjusted to pH = 1.5, and then the ratio of V and W in the solution was adjusted. The vanadium tungsten solution is evaporated, crystallized, washed and dried at 105 ° C, and further calcined at 600 ° C to obtain a vanadium tungsten mixed oxide;

(4) The leachate obtained in the step (2) is separated from V and W by a precipitation method. Adjust the leachate pH=5, then add ammonium sulfate to vanadium, the molar ratio of ammonium sulfate to metal vanadium in the leachate mpre:mmetal=1, the precipitation temperature is 20 ° C, the precipitation time is 20 min, and the ammonium metavanadate precipitate and tungsten are filtered. Solution

(5) A vanadium-tungsten-based SCR catalyst powder is prepared by a mixed method of the vanadium-tungsten mixed oxide obtained in the step (3). The vanadium-tungsten mixed oxide was first pulverized to 100 mesh, and then wet-milled and mixed with TiO ₂ at a certain ratio for 5 hours. After the end of the mixing, they were placed in an oven at 110 ° C for 12 h. The dried product was 1.3% V ₂ O ₅ -3.2% WO ₃ /TiO ₂ -based SCR catalyst powder. 50 g of the catalyst powder ground to 0.1 mm was taken, and then 4.5 g of a binder polyacrylamide and 2.5 g of activated carbon powder having a particle diameter of 0.1 mm were added, followed by dry mixing for 15 minutes. After uniformly mixing, 10 mL of water and 4 mL of the eluating agent ethanolamine were sequentially added, and then the wet material was kneaded with a crucible bar to obtain a plastic paste. The plastic paste was placed in the upper portion of the honeycomb catalyst mold, and the plastic paste was forcibly pressed between the lower shaping rods using a press plate. The mold containing the catalyst paste was heated in an oven at 65 ° C, and after the paraffin wax which was previously applied to the sizing rod and the surface of the mold was melted, the mold was taken out to obtain a semi-dry catalyst body. The catalyst embryo body was dried in an oven at 105 ° C for 12 h and then calcined at 450 ° C for 12 h to obtain a honeycomb 1.3% V ₂ O ₅ -3.3% WO ₃ /TiO ₂ -based SCR denitration catalyst;

(6) The ammonium metavanadate precipitate obtained in the step (4) is washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.1%; the tungsten-containing solution obtained in the step (4) is adjusted to pH=8, and then the nitric acid is added. Calcium precipitation, molar ratio of calcium nitrate to metal tungsten in the leachate mpre:mmetal=6, reaction temperature 50 ° C, precipitation time 50 min, calcium tungstate precipitation. The calcium tungstate precipitate was washed and dried to obtain a calcium tungstate product having a purity of 99.3%.

Example 10

The waste vanadium-tungsten-based SCR catalyst provided by a laboratory has a V ₂ O ₅ content of 1.1%, a MO ₃ of 2.5%, and a TiO ₂ of 96.2%.

(1) 50 g of the above spent catalyst was taken, firstly pulverized to 100 mesh, washed with water, filtered and dried. The dried spent catalyst was added with NaNO ₃ as an additive, and the molar ratio of NaNO ₃ to the total amount of metal in the spent catalyst was Madd:mmetal=4.5. After mixing uniformly, it is placed in a muffle furnace for calcination, the calcination temperature is 700 ° C, and the calcination time is 6 h;

(2) using 2 g / L of sodium hydroxide solution as a leaching agent, from the spent catalyst after calcination in step (1) Leaching V and Mo, liquid-solid ratio is 0.2L/g, leaching temperature is 120°C, leaching pressure is 0.5MPa, leaching time is 5h, stirring speed is 1000r/min, V single-stage leaching rate is 74.9%, Mo is 72.7 %; the leaching residue is subjected to secondary leaching;

(3) The leachate described in the step (2) is adjusted to pH=12, and then coprecipitated by adding calcium chloride, the molar ratio of calcium chloride to the total amount of metal in the leachate mpre:mmetal=5, the reaction temperature is 90 ° C, precipitation The time is 120 min, and calcium vanadate and calcium molybdate can be mixed and precipitated. The mixed precipitate is dissolved in nitric acid, and after adjusting the pH of the solution to 12, the calcium chloride is coprecipitated, and the obtained precipitate is washed and dried to be a pure vanadium-molybdenum mixed calcium salt. The vanadium-molybdenum mixed calcium salt was dissolved with nitric acid and the solution was adjusted to pH = 1.5, and then the ratio of V to Mo in the solution was adjusted. The vanadium-molybdenum solution is evaporated, crystallized, washed and dried at 105 ° C, and further calcined at 650 ° C to obtain a vanadium-molybdenum mixed oxide;

(4) The leachate described in the step (2) is separated from V and Mo by a precipitation method. Adjusting the leachate pH=11, then adding ammonium chloride to form vanadium, the molar ratio of ammonium chloride to metal vanadium in the leachate mpre:mmetal=6, the precipitation temperature is 80 ° C, the precipitation time is 120 min, and the ammonium metavanadate precipitate is filtered. Molybdenum containing solution;

(5) The vanadium molybdenum mixed oxide obtained in the step (3) is first dissolved in a 0.1 mol/L oxalic acid solution, and then TiO ₂ is added in proportion. The system was placed in an ultrasonic cleaner and ultrasonically mixed for 4 h. After the end of the ultrasound, the system was stirred and evaporated to dryness. The solid mixture obtained after evaporation to dryness was placed in an electric blast drying oven at 110 ° C for 24 h. The dried solid mixture was ground into a powder, placed in a crucible and placed in a muffle furnace for calcination at a calcination temperature of 600 ° C and a calcination time of 9 h. The calcined product was a 1.2% V ₂ O ₅ -2.5% MO ₃ /TiO ₂ -based SCR catalyst powder. 50 g of the catalyst powder ground to 0.1 mm was taken, and then 5 g of a binder polyacrylamide and 2.5 g of activated carbon powder having a particle diameter of 0.1 mm were added, followed by dry mixing for 20 minutes. After the mixture was uniformly mixed, 8 mL of water and 3.5 mL of the eluating agent ethanolamine were sequentially added, and then the wet material was kneaded with a crucible bar to obtain a plastic paste. The plastic paste was placed in the upper portion of the honeycomb catalyst mold, and the plastic paste was forcibly pressed between the lower shaping rods using a press plate. The mold containing the catalyst paste was heated in an oven at 60 ° C, and after the paraffin wax which was previously applied to the sizing rod and the surface of the mold was melted, the mold was taken out to obtain a semi-dried catalyst body. The catalyst body was dried in an oven at 110 ° C for 24 h and then calcined at 450 ° C for 12 h to obtain a honeycomb 1.3% V ₂ O ₅ -2.4% WO ₃ /TiO ₂ -based SCR denitration catalyst.

(6) The ammonium metavanadate precipitate obtained in the step (4) is washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.5%; the molybdenum-containing solution obtained in the step (4) is adjusted to pH=10, and then chlorine is added. The calcium precipitation, the molar ratio of calcium nitrate to metal molybdenum in the leachate mpre:mmetal=6, the reaction temperature is 50 ° C, the precipitation time is 120 min, and calcium molybdate precipitation can be obtained. The calcium molybdate precipitate was washed and dried to obtain a calcium molybdate product having a purity of 99.6%.

Example 11

The waste vanadium molybdenum-based SCR catalyst provided by a laboratory has a V ₂ O ₅ content of 1.1%, a MO ₃ of 2.0%, and a TiO ₂ of 96.7%.

(1) 50 g of the above spent catalyst was taken, firstly pulverized to 100 mesh, washed with water, filtered, and dried at 105 °C. The dried spent catalyst was added with NaCl as an additive, and the molar ratio of NaCl to the total amount of metal in the spent catalyst was mdd:mmetal=6. After mixing uniformly, it is placed in a muffle furnace for calcination, the calcination temperature is 900 ° C, and the calcination time is 7 h;

(2) Using 1 g/L of sulfuric acid solution as a leaching agent, leaching V and Mo from the spent catalyst calcined in the step (1), the liquid-solid ratio is 1 L/g, the leaching temperature is 100 ° C, and the leaching pressure is 0.2 MPa. The leaching time is 0.5h, the stirring speed is 5000r/min, the V single-stage leaching rate is 96.2%, the Mo is 95.2%, the Ti is 86.1%, and the leaching residue is returned to the step (1);

(3) V, Mo and Ti in the leachate obtained in the step (2) are simultaneously extracted by the weakly basic anion exchange resin D418. The volume of the leachate was 10 times the volume of the resin, the pH of the solution was 1, the temperature was 10 ° C, the exchange reaction time was 30 min, the V extraction rate was 94.3%, the Mo was 95.8%, the Ti was 96.2%, and the mother liquor was subjected to secondary extraction. The resin was washed and regenerated with 15% ammonia water, the regeneration time was 20 min, and the regeneration temperature was 20 ° C, obtained vanadium molybdenum titanium mixed ammonium salt solution;

(4) The leachate described in the step (2) is first adjusted to pH=9, and filtered to obtain a sodium titanate precipitate and a vanadium-molybdenum solution. The vanadium-molybdenum solution was separated by a weakly basic anion exchange resin D418. The volume of the leachate was 10 times the volume of the resin, the pH of the solution was 2, the temperature was 20 ° C, the exchange reaction time was 30 min, the V extraction rate was 99.3%, and Mo was 0.2%. A negative vanadium resin and a molybdenum containing residue are obtained. The resin was washed and regenerated with a 2 g/L Na ₂ CO ₃ solution, the regeneration time was 20 min, and the regeneration temperature was 25 ° C to obtain a sodium vanadate solution;

(5) The vanadium molybdenum-titanium mixed ammonium salt solution obtained in the step (3) is prepared by a precipitation method to prepare a vanadium molybdenum-based SCR denitration catalyst powder. First, the vanadium molybdenum-titanium mixed ammonium salt solution was adjusted to pH=7.5, then calcium nitrate was added, and filtered to obtain a vanadium molybdenum-titanium mixed precipitate. The mixed precipitate was first dissolved with nitric acid and further acidified to pH = 1.1, and then crystallized by evaporation, washed, dried at 105 ° C and calcined at 750 ° C to obtain 1.2% V ₂ O ₅ -2.0% MoO ₃ /TiO ₂ -based SCR catalyst powder. . 50 g of the catalyst powder ground to 0.1 mm was taken, and then 5.5 g of a binder methylcellulose and 3.5 g of an activated carbon powder having a particle diameter of 0.1 mm were added, followed by dry mixing for 18 minutes. After mixing uniformly, 8 mL of water, 4 mL of the eluating agent ethanolamine and 2.5 mL of lubricating oil glycerin were sequentially added, and then the wet material was kneaded with a crucible bar to obtain a plastic paste. The 55*100mm stainless steel plate with mesh holes is used as the support. The thickness of the sieve plate is 0.5mm, the hole diameter is 1mm, the hole pitch is 1.5mm, and the triangles are arranged in a regular triangle shape. The 0.5mm thick plastic paste is uniformly pressed on the lower and upper sides of the sieve plate. The sieve plate with the plastic paste was dried at 105 ° C for 12 h, and then calcined at 500 ° C for 24 h to obtain a catalyst veneer having a thickness of 1.5 mm, which was assembled in a stainless steel casing to obtain a plate catalyst;

(6) The sodium vanadate solution obtained in the step (4) is adjusted to pH=8, and ammonium sulfate is added to form vanadium, and the obtained ammonium metavanadate precipitate is washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.5%. The molybdenum-containing residual liquid obtained in the step (4) is adjusted to pH=1.2, and then crystallized by evaporation, washed and dried to obtain a molybdic acid product having a purity of 99.0%.

Example 12

The waste vanadium-tungsten-based SCR catalyst provided by a laboratory has a V ₂ O ₅ content of 1.3%, WO ₃ of 2.4%, and TiO ₂ of 96.1%.

(1) taking 50 g of the above spent catalyst, firstly pulverized to 100 mesh, washed with water, filtered, and dried at 105 ° C;

(2) Using 1g/L NaOH solution as leaching agent, leaching V and W from step (1), liquid-solid ratio of 0.7L/g, leaching temperature of 150°C, leaching pressure of 0.5MPa, leaching time of 2h, stirring The speed is 4000r/min, the V single-stage leaching rate is 87.2%, W is 86.3%, Ti is 84.3%; the leaching residue returns to step (1);

(3) V and W in the leachate obtained in the step (2) are simultaneously extracted by the strongly basic anion exchange resin D201. The volume of the leachate was 100 times the volume of the resin, the pH of the solution was 12, the temperature was 100 ° C, the exchange reaction time was 120 min, the V extraction rate was 99.1%, and the W was 98.9%. The mother liquor was subjected to secondary extraction. The resin was washed and regenerated with 2 g/L NaOH solution, the regeneration time was 120 min, and the regeneration temperature was 100 ° C to obtain a vanadium-tungsten mixed sodium salt solution;

(4) V and W in the leachate described in the step (2) are separated by a strong basic anion exchange resin D201. The volume of the leachate was 100 times the volume of the resin, the pH of the solution was 11, the temperature was 90 ° C, the exchange reaction time was 100 min, the V extraction rate was 99.1%, and the W was 0.1%, and a negative vanadium resin and a tungsten-containing residual liquid were obtained. The resin was washed and regenerated with a 5 g/L NaOH solution, the regeneration time was 120 min, and the regeneration temperature was 90 ° C to obtain a sodium vanadate solution;

(5) The vanadium-tungsten mixed sodium salt solution obtained in the step (3) first adjusts the ratio of V and W, then adjusts the pH to 3, and then dissolves the Na2TiO3 in proportion, and the obtained vanadium-tungsten-titanium mixed solution is prepared by precipitation method. SCR denitration catalyst powder. First, the vanadium-tungsten-titanium mixed solution was adjusted to pH=8, then calcium nitrate was added, and filtered to obtain a vanadium-tungsten-titanium mixed precipitate. The mixed precipitate was first dissolved with nitric acid and continued to be acidified to pH = 1.5, then crystallized by evaporation, washed, dried at 105 ° C and calcined at 700 ° C to obtain 1.2% V ₂ O ₅ -2.3% WO ₃ /TiO ₂ -based SCR catalyst powder. . 50 g of the catalyst powder ground to 0.1 mm was taken, and then 5 g of the binder methylcellulose and 3 g of the activated carbon powder having a particle diameter of 0.1 mm were added, followed by dry mixing for 20 min. After mixing uniformly, 10 mL of water, 5 mL of the eluating agent ethanolamine and 2 mL of lubricating oil glycerin were sequentially added, and then the wet material was kneaded with a crucible bar to obtain a plastic paste. The corrugated fiberboard of 50*100mm is used as the support, the thickness of the fiberboard is 0.5mm, and the plastic paste of 0.5mm thick is evenly coated on both sides of the fiberboard. The sieve plate with plastic paste was dried at 105 ° C for 24 h, and then calcined at 450 ° C for 20 h to obtain 1.3% V ₂ O ₅ -2.2% WO ₃ /TiO ₂ corrugated plate catalyst;

(6) The sodium vanadate solution obtained in the step (4) is adjusted to pH=9, and ammonium nitrate is added to form vanadium, and the obtained ammonium metavanadate precipitate is washed, dried and calcined to obtain a vanadium pentoxide product having a purity of 99.7%. The tungsten-containing residual liquid obtained in the step (4) is adjusted to pH = 1.5, and then crystallized by evaporation, washed and dried to obtain a tungstic acid product having a purity of 99.5%.

It should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to be limiting, and the present invention will be described in detail with reference to the preferred embodiments, The modifications and equivalents of the present invention are intended to be included within the scope of the appended claims.

Claims (10)

1. A recycling treatment method for a waste SCR denitration catalyst, comprising the steps of:

   (1) pretreating the waste SCR denitration catalyst to remove impurities and activate catalytic components such as vanadium tungsten molybdenum;

   (2) leaching the waste SCR denitration catalyst obtained after the pretreatment in step (1) to obtain leach residue and leachate;

   (3) separating the valuable elements in the leachate obtained in the step (2) to obtain a vanadium extract and a tungsten/molybdenum/tungsten-molybdenum enrichment;

   (4) The vanadium extract obtained in the step (3) is further purified for use in preparing a vanadium product; the obtained tungsten/molybdenum/tungsten-molybdenum concentrate is further purified for use in preparing a tungsten/molybdenum/tungsten-molybdenum product.
2. The method according to claim 1, wherein (5) the valuable elements in the leachate obtained in the step (2) are simultaneously purified, and the ratio of the contents of the respective substances is adjusted to obtain a mixture of catalytic components for further preparation. For the new SCR denitration catalyst.
3. The method according to claim 1 or 2, wherein the leaching agent in the step (2) is a neutral or acidic or alkaline solution, and the liquid-solid ratio of the leaching agent to the spent catalyst is 0.02 to 1 L/g. The leaching temperature is 20 to 200 ° C, the leaching pressure is 0.1 to 1 MPa, the leaching time is 0.5 to 5 h, and the stirring speed is 100 to 5000 r/min;

   Preferably, the leaching agent is a neutral or alkaline solution.
4. The method according to claim 1, wherein when the valuable elements in the leachate in the step (3) are separated by an extraction method, the extracting agent is an amine, an organic phosphonic acid, an organic ester, or a neutral phosphine. The concentration of the extractant is 5% to 30%, the initial pH of the aqueous phase is 1 to 9, the extraction temperature is 10 to 40 ° C, and the extraction time is 10 to 40 minutes.
5. The method according to claim 1, wherein when the valuable elements in the leachate in the step (3) are separated by ion exchange, the resin type is a strongly basic or weakly basic anion exchange resin, and the volume of the leachate is 10 to 100 times the volume of the resin, the pH of the solution is 2 to 11, and the temperature is 20 to 90 ° C. The replacement time is 30 to 100 minutes, and the resin regeneration liquid is a strongly alkaline or weakly alkaline solution, the regeneration time is 20 to 120 minutes, and the regeneration temperature is 25 to 90 °C.
6. The method according to claim 1, wherein when the valuable elements in the leachate in the step (3) are separated by a precipitation method, the molar ratio of the precipitant to the total amount of the metal in the leachate is mpre:mmetal=1~ 6, the solution pH = 5 ~ 11, the precipitation temperature is 20 ~ 80 ° C, the precipitation time is 20 ~ 120min.
7. The method according to claim 2, wherein when the valuable element in the leachate of the step (3) is simultaneously purified by extraction, the extracting agent is an amine, an organic phosphonic acid, an organic ester or a neutral phosphine. Type, quaternary ammonium salt or bismuth extractant, the concentration of the extractant is 5% to 30%, the initial pH of the aqueous phase is 1-10, the extraction temperature is 10-40 ° C, and the extraction time is 10-40 min.
8. The method according to claim 2, wherein when the valuable element in the leachate in the step (3) is simultaneously purified by ion exchange, the resin type is a strongly basic or weakly basic anion exchange resin, and the leachate volume It is 10 to 100 times the volume of the resin, the pH of the solution is 1 to 12, the temperature is 10 to 100 ° C, and the exchange time is 30 to 120 minutes. The resin regeneration liquid is a strong alkaline or weakly alkaline solution, and the regeneration time is 20 to 120 minutes. The regeneration temperature is 20 to 100 °C.
9. The method according to claim 2, wherein when the valuable element in the leachate in the step (3) is simultaneously purified by the coprecipitation method, the molar ratio of the precipitant to the total amount of the metal in the leachate is mpre:mmetal=1. ~ 5, the solution pH = 6 ~ 12, the precipitation temperature is 10 ~ 90 ° C, the precipitation time is 10 ~ 120min.
10. The method according to any one of claims 2, 7, 8 or 9, wherein the method for preparing a new SCR catalyst by the catalytic component mixture of the step (4) is a dipping method, a mixing method and a precipitation method, The new SCR catalysts are in the form of pellets, plates, honeycombs and corrugated plates;

    Preferably, the catalytic component mixture is prepared by a dipping process, and the new SCR catalyst is in the form of granules.

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