Method for comprehensive recovery of spent catalyst

Abstract

The present invention belongs to the technical field of catalyst secondary resource recovery, and specifically relates to a method for comprehensive recovery of waste catalysts. In the present invention, by collecting the flue gas generated during the roasting process of the waste catalyst, the carbon and sulfur in the waste catalyst are effectively recovered, and the sodium roasting and water leaching process is adopted to recover the vanadium and molybdenum in the waste catalyst, and the vanadium, molybdenum and aluminum, nickel are selectively separated, and the acid leaching process is adopted to recover the nickel and aluminum in the waste catalyst, and the solvent extraction method is adopted to selectively separate aluminum and nickel. In the present invention, by adjusting the process conditions, the efficient recovery of valuable metals such as vanadium, molybdenum, aluminum, and nickel in the waste catalyst is effectively achieved, and the recovery rate is high, and resource reuse is achieved, which is in line with the concept of green and sustainable industrial development.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst secondary resource recovery, and in particular relates to a method for comprehensive recovery of waste catalysts. Background Art

[0002] The deactivated catalyst of residue oil hydrodemetallization is a hazardous waste (HW50), which contains a large amount of organic residues and heavy metals and needs to be pretreated. The deactivated waste residue oil hydrodemetallization catalyst contains more effective components: carbon, sulfur, vanadium, molybdenum, nickel, aluminum, etc. These components are rare secondary resources, and the metals in the waste residue oil hydrodemetallization catalyst have the characteristics of high grade and simple composition compared with natural ores. Therefore, it is necessary to recycle the deactivated catalyst, which can not only recycle resources and improve the economic benefits of the refinery, but also reduce environmental pollution.

[0003] Methods for removing organic matter from waste hydrogenation catalysts include wet leaching, roasting-leaching and pyrometallurgical enrichment. Wet leaching can selectively recover valuable metals with a high metal recovery rate, but it produces a large amount of wastewater. Pyrometallurgical enrichment is to smelt waste catalysts and flux at high temperatures. The waste agent processing volume is large and the recovery process is short, but valuable metals cannot be selectively recovered. The roasting-leaching method is a combination of wet leaching and pyrometallurgical processes. It can selectively recover valuable metals, and the recovery rate of metals such as Mo, V, and Ni is high. However, the phase of alumina is transformed at high temperatures, the Al recovery rate is low, and it cannot be directly returned to prepare new hydrogenation catalysts.

[0004] The Chinese patent application document with the publication number CN114635032A discloses a method for comprehensive recycling of waste catalysts, comprising the following steps: (1) taking a certain amount of waste catalysts to remove porcelain balls; (2) roasting and deoiling; (3) roasting mixed materials; (4) water leaching: leaching with cold water for 2 hours, filtering, and obtaining filter residue a and filtrate b; (5) acidifying and removing impurities from the filtrate b; (6) recovering tungsten and vanadium: recovering valuable metals by ion exchange adsorption, adding acid and hydrogen peroxide to adjust the pH value to 2-3, and then precipitating tungstic acid, vanadium is reduced and remains in the solution, and vanadium is extracted by N235; (7) taking the filter residue a in step (4) and conducting high-temperature acid leaching to obtain leaching residue and acid leaching solution, (8) recovering precious metals; (9) recovering nickel and cobalt: filtering and crystallizing the stripping solution to obtain cobalt sulfate and nickel sulfate. Although this method can recover metals such as tungsten, vanadium, nickel, and cobalt, this method cannot recover aluminum.

[0005] The Chinese patent application document with publication number CN105274344A discloses a method for recovering vanadium and molybdenum from waste petroleum catalysts. First, the viscous oil in the waste catalyst is ignited in the air to burn off the carbon and oil therein, and the vanadium and nickel in the form of porphyrin compounds therein are oxidized to vanadium oxide and nickel oxide, and most of the molybdenum is also converted into molybdenum oxide. The waste catalyst after air burning and de-oiling is more conducive to crushing. The crushed waste catalyst is mixed with a certain proportion of sodium carbonate and roasted at high temperature; the roasted material is leached with hot water, and the sodium salts of vanadium and molybdenum are dissolved in water and filtered into the leaching solution, and a small amount of aluminum also enters the leaching solution, and the pH value is adjusted to remove aluminum; then the pH is adjusted to between 8 and 9, and ammonium chloride is added, and vanadium is precipitated in the form of ammonium metavanadate; the solution after vanadium precipitation is concentrated and enriched by ion exchange to enrich the ammonium molybdate solution. This method uses ammonium chloride to precipitate vanadium, which has certain requirements on the material of production equipment. Summary of the invention

[0006] In order to solve the technical problems existing in the related art of incomplete recovery of waste catalysts and difficulty in realizing resource recycling, the purpose of the present invention is to provide a method for comprehensive recovery of waste catalysts.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A method for comprehensive recovery of spent catalysts comprises the following steps:

[0009] S1: The spent catalyst is pyrolyzed and roasted in a nitrogen atmosphere to obtain a primary roasting product and flue gas; the obtained flue gas is passed through a cyclone bag to remove dust and then incinerated to obtain high-temperature process steam, which is condensed and cooled through a heat exchanger, and then passes through a denitration device (SCR reactor) and a SO2 converter in sequence, and then condensed in a condenser after cooling, and the generated sulfuric acid is recovered, and the remaining process steam is stored in an intermediate tank;

[0010] S2: roasting the primary roasting product obtained in step S1 and mixing it with sodium carbonate solution to form loose gravel, drying, secondary roasting, cooling, adding deionized water to a solid-liquid ratio of 1:2.5-5, leaching once, filtering, and obtaining leachate I and filter cake I; adjusting the pH value of leachate I to 9.5-10.5, adding magnesium sulfate and ammonium sulfate, stirring until no more precipitation occurs, filtering to obtain filtrate I, adjusting the pH value of filtrate I to 8-9, adding ammonium sulfate, continuing to stir until no more precipitation occurs, filtering, obtaining filtrate II and ammonium metavanadate, and obtaining vanadium pentoxide after roasting ammonium metavanadate; adjusting the pH value of filtrate II to 3-4, recovering molybdenum in filtrate II with ion exchange resin, adjusting the pH value of the remaining solution to 12-14, stripping ammonia, and passing the generated steam through sulfuric acid solution to obtain ammonium sulfate after evaporation and crystallization;

[0011] S3: adding sodium hydroxide solution to the filter cake I obtained in step S2 until the solid-liquid ratio is 1:2.5-5, performing secondary leaching, filtering, and obtaining a leachate II and a filter cake II;

[0012] S4: adding sulfuric acid solution to the filter cake II obtained in step S3 to a solid-liquid ratio of 1:2.5-5, leaching for three times, filtering, and evaporating and crystallizing the obtained leaching solution III to obtain nickel sulfate.

[0013] Furthermore, in the method for comprehensive recovery of waste catalysts, the pyrolysis temperature in step S1 is 300-450°C and the time is 0.5-2h; the calcination is carried out in an oxygen-deficient atmosphere with an oxygen content of <10%; the calcination temperature is 300-400°C and the time is 1-4h.

[0014] Furthermore, in the method for comprehensive recovery of waste catalysts, the incineration temperature in step S1 is 800-1000°C; the temperature of the high-temperature process steam after condensation and cooling through a heat exchanger is reduced from 800-1000°C to 380-420°C; and the cooling temperature is 200-300°C.

[0015] Furthermore, in the method for comprehensive recovery of waste catalysts, the calcination temperature in step S2 is 400-600°C, and the calcination time is 5-8h; the mass percentage of the sodium carbonate solution is 30%-33%, and the ratio of the amount of sodium carbonate in the sodium carbonate solution to the total amount of vanadium pentoxide and molybdenum oxide in the primary calcination product is 1.5-4:1.

[0016] Furthermore, in the method for comprehensive recovery of waste catalysts, the drying temperature in step S2 is 115-120°C, and the drying time is 1-2h; the secondary roasting temperature is 500-600°C, and the secondary roasting time is 3-8h; the leaching temperature is 25-90°C, and the leaching time is 1-4h.

[0017] Furthermore, in the method for comprehensive recovery of waste catalysts, the total amount of magnesium sulfate and ammonium sulfate added in step S2 is 90%-105% of the theoretical phosphorus content in the leaching solution I, and the amount of ammonium sulfate added is 1.0-5.0 times the mass of the theoretical vanadium pentoxide in the filtrate; the stirring temperature for continuing stirring until the precipitate no longer precipitates is 25-50°C, and the stirring time is 0.5-2h; the temperature for roasting ammonium metavanadate is 450-500°C, and the time is 1-2h.

[0018] Furthermore, the specific operation of recovering molybdenum in the filtrate II with an ion exchange resin in step S2 of the method for comprehensive recovery of waste catalysts is as follows: adsorbing the molybdenum in the filtrate II with a weakly basic anion exchange resin, controlling the flow rate of the filtrate II to 2-8 BV / hr, and the penetration concentration of molybdenum to 0.02 g / L, and analyzing with 1-4 mol / L ammonia water or sodium hydroxide solution to obtain a high concentration of ammonium molybdate or sodium molybdate solution, and obtaining ammonium molybdate or sodium molybdate after evaporation and crystallization.

[0019] Furthermore, in the method for comprehensive recovery of spent catalysts, the mass percentage of sodium hydroxide in step S3 is 30%-35%; the temperature of the secondary leaching is 25-200° C., and the time is 1-4 hours.

[0020] Furthermore, in the method for comprehensive recovery of spent catalysts, the concentration of the sulfuric acid solution in step S4 is 0.5-4 mol / L; the leaching temperature is 25-200° C., and the leaching time is 1-4 h.

[0021] The present invention also provides a method for preparing a residual oil hydrogenation catalyst using the product obtained in the above-mentioned method for comprehensive recovery of waste catalysts, which is specifically: introducing the remaining process steam obtained in step S1 into the leaching solution II obtained in step S3 at room temperature for reaction for 1-2 hours, controlling the pH value of the reaction end point to be 10-10.5, filtering, taking the filter cake, drying and crushing it to obtain a carrier; mixing the ammonium molybdate or sodium molybdate obtained in step S2, basic nickel carbonate and a 30% by mass phosphoric acid aqueous solution to obtain a molybdenum-nickel solution; putting the carrier and the molybdenum-nickel solution into an impregnation kettle, impregnating at 60-90° C. for 1-4 hours, drying at 90-120° C. for 1-4 hours, and calcining at 400-600° C. for 1-4 hours to obtain a residual oil hydrogenation catalyst; the mass percentages of the components in the residual oil hydrogenation catalyst are: MoO3%=8%-12%, NiO%=3%-4%, P2O5%=1%-3%, Al2O3%=80%-84%.

[0022] In the method for comprehensive recovery of waste catalyst provided by the present invention, in step S1, the waste catalyst is first pyrolyzed in a nitrogen atmosphere to remove the oil on the surface, and then low-temperature roasting is carried out in an oxygen-deficient atmosphere to remove carbon deposits and convert low-valent metal sulfides into high-valent metal oxides. The flue gas obtained mainly contains fly ash, nitrogen oxides, sulfur dioxide, carbon dioxide, etc. After the fly ash and particulate matter are removed from the flue gas, it is incinerated, and the heat recovered from the incineration is used to heat the circulating water. After the process steam obtained by the incineration is condensed, the nitrogen oxides therein are reduced to nitrogen and water in the SCR reactor. The process steam after denitration enters the SO2 converter, and SO2 is oxidized to SO3 at 380-420°C until SO2 / SO3 equilibrium is reached. The sulfuric acid concentration recovered after condensation in the condenser is 94%-97%, and the remaining process steam containing CO2 is stored in the intermediate tank for carbonization to prepare pseudo-boehmite.

[0023] When recovering vanadium and molybdenum in step S2, the primary leaching solution mainly contains sodium vanadate, sodium molybdate and sodium carbonate. After adding magnesium sulfate and ammonium sulfate, the phosphorus in the leaching solution is converted into PO4 3- In the form of Mg 2+ NH4 + and PO4 3- Insoluble magnesium ammonium phosphate precipitate is generated, a small amount of aluminum in the leachate is hydrolyzed to form a precipitate, the filtrate obtained by filtration is adjusted to pH value and then ammonium sulfate is added, the vanadium in the primary leachate is precipitated in the form of ammonium metavanadate, and vanadium pentoxide is obtained by roasting. In step S3, the secondary leaching obtains an aluminum-containing leachate, which is mainly sodium metaaluminate.

[0024] Compared with the prior art, the method for comprehensive recovery of waste catalyst provided by the present invention has the following technical advantages:

[0025] (1) The present invention effectively achieves efficient recovery of valuable metals such as vanadium, molybdenum, aluminum, and nickel in waste catalysts by regulating process conditions, and the recovery rate is high, among which ammonium metavanadate>98%, ammonium molybdate>98%, nickel sulfate>98%, and sodium metaaluminate solution (Al2O3%=40~100g / L)>98%;

[0026] (2) The ammonium molybdate or sodium molybdate and pseudo-boehmite recovered in the present invention can be used to prepare the residual oil hydrogenation catalyst again, the ammonium metavanadate / vanadium pentoxide and nickel sulfate can be sold, and the concentrated sulfuric acid and ammonium sulfate can be reused, so that the effective components such as carbon, sulfur, vanadium, molybdenum, aluminum, nickel and the like in the waste catalyst can be fully recovered and reused;

[0027] (3) The method for comprehensive recovery of waste catalysts provided by the present invention realizes resource recycling. By recovering sulfur and carbon in roasting flue gas, carbon emissions are reduced, environmental pollution is reduced, and the problem of hazardous waste disposal is solved. It truly realizes the recycling of all components of waste catalysts, which is in line with the concept of green and sustainable industrial development. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a process flow chart of comprehensive recovery of waste catalyst in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The technical scheme of the present invention is clearly and completely described below in conjunction with specific embodiments. The specific embodiments described are only partial embodiments of the present invention, rather than limitations of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present invention.

[0030] In this specific implementation manner, the leaching method is atmospheric pressure leaching or pressurized leaching, and the pressure of the pressurized leaching is 1.2-1.3 MPa; the weakly basic anion exchange resin is D314 or LS-32.

[0031] The main components of the waste catalyst used in this specific embodiment are shown in Table 1, and the process flow chart of the comprehensive recovery of the waste catalyst is as follows: Figure 1 shown.

[0032] Table 1 Main components of spent catalyst

[0033]

[0034] Example 1

[0035] A method for comprehensive recovery of spent catalysts comprises the following steps:

[0036] S1: The spent catalyst is pyrolyzed at 300°C in a nitrogen atmosphere for 2 hours, and then roasted at 300°C in an oxygen-deficient atmosphere (oxygen content <10%) for 4 hours to obtain a primary roasting product and flue gas; the obtained flue gas is passed through a cyclone bag to remove dust, and then passed through a secondary combustion chamber to be incinerated at 800°C to obtain high-temperature process steam, which is condensed and cooled through a heat exchanger from 800°C to 380°C, and then passed through a denitration device (SCR reactor) and a SO2 converter in sequence, cooled to 200°C, and then condensed in a condenser, the generated sulfuric acid is recovered, and the remaining process steam is stored in an intermediate tank;

[0037] S2: The primary calcined product obtained in step S1 is calcined at 400°C for 8h, then mixed with 30% by mass sodium carbonate solution into a loose gravel state (the ratio of the amount of sodium carbonate in the sodium carbonate solution to the total amount of vanadium pentoxide and molybdenum oxide in the primary calcined product is 1.5:1), dried at 115°C for 2h, then secondary calcined at 500°C for 8h, added with deionized water to a solid-liquid ratio of 1:2.5 after cooling, leached once at 25°C for 4h, filtered to obtain a leachate I and a filter cake I; the pH value of the leachate I is adjusted to 9.5, magnesium sulfate and ammonium sulfate are added, the total amount of magnesium sulfate and ammonium sulfate added is 90% of the theoretical phosphorus content in the leachate I, stirred until no more precipitation occurs, filtered to obtain a filtrate I, and the pH value of the filtrate I is adjusted to The value is 8, ammonium sulfate is added, and the amount of ammonium sulfate added is 1.0 times the mass of the theoretical vanadium pentoxide in the filtrate, and the mixture is stirred at 25°C for 2h until the precipitate no longer precipitates, and filtered to obtain filtrate II and ammonium metavanadate, and the ammonium metavanadate is roasted at 450°C for 2h to obtain vanadium pentoxide; the pH value of the filtrate II is adjusted to 3, and the molybdenum in the filtrate II is adsorbed with a weakly basic anion exchange resin, and the flow rate of the filtrate II is controlled to be 2BV / hr. No bias flow or bubbles should occur during the operation, and the penetration concentration of molybdenum is 0.02g / L. It is analyzed with a 1mol / L sodium hydroxide solution to obtain a high-concentration sodium molybdate solution, and sodium molybdate is obtained after evaporation and crystallization. The pH value of the remaining solution is adjusted to 12, and ammonia is stripped and evaporated. The generated steam passes through a sulfuric acid solution, and ammonium sulfate is obtained after evaporation and crystallization;

[0038] S3: adding 30% by mass of sodium hydroxide solution to the filter cake I obtained in step S2 until the solid-liquid ratio is 1:2.5, performing secondary leaching at 25° C. for 4 h, filtering to obtain a leachate II and a filter cake II, and evaporating and crystallizing the leachate II to obtain sodium aluminate;

[0039] S4: Add a 0.5 mol / L sulfuric acid solution to the filter cake II obtained in step S3 until the solid-liquid ratio is 1:2.5, leaching three times at 25°C for 4 hours, filtering, and evaporating and crystallizing the obtained leachate III to obtain nickel sulfate.

[0040] Example 2

[0041] A method for comprehensive recovery of spent catalysts comprises the following steps:

[0042] S1: The spent catalyst is pyrolyzed at 450°C in a nitrogen atmosphere for 0.5h, and then calcined at 400°C in an oxygen-deficient atmosphere (oxygen content <10%) for 1h to obtain a primary calcination product and flue gas; the obtained flue gas is passed through a cyclone bag to remove dust, and then passed through a secondary combustion chamber to be incinerated at 1000°C to obtain high-temperature process steam, which is condensed and cooled through a heat exchanger from 1000°C to 420°C, and then passed through a denitrification device (SCR reactor) and a SO2 converter in sequence, cooled to 300°C, and then condensed in a condenser, the generated sulfuric acid is recovered, and the remaining process steam is stored in an intermediate tank;

[0043] S2: The primary calcined product obtained in step S1 is calcined at 600°C for 5h, and then mixed with a sodium carbonate solution with a mass percentage of 33% to form a loose gravel state (the ratio of the amount of sodium carbonate in the sodium carbonate solution to the total amount of vanadium pentoxide and molybdenum oxide in the primary calcined product is 4:1), dried at 120°C for 1h, and then secondary calcined at 600°C for 3h, and after cooling, deionized water is added to a solid-liquid ratio of 1:5, and leached once at 90°C for 4h, filtered to obtain a leachate I and a filter cake I; the pH value of the leachate I is adjusted to 10.5, magnesium sulfate and ammonium sulfate are added, and the total amount of magnesium sulfate and ammonium sulfate added is 105% of the theoretical phosphorus content in the leachate I, stirred until no precipitation is precipitated, and filtered to obtain a filtrate I, and the pH value of the filtrate I is adjusted to 9. Add ammonium sulfate in an amount of 5.0 times the mass of the theoretical vanadium pentoxide in the filtrate, stir at 50° C. for 0.5 h until no more precipitates are precipitated, filter to obtain filtrate II and ammonium metavanadate, calcine the ammonium metavanadate at 500° C. for 1 h to obtain vanadium pentoxide; adjust the pH value of filtrate II to 4, adsorb molybdenum in filtrate II with weakly basic anion exchange resin, control the flow rate of filtrate II to 8 BV / hr, no bias flow or bubbles should occur during operation, the breakthrough concentration of molybdenum is 0.02 g / L, analyze with 4 mol / L ammonia water to obtain a high-concentration ammonium molybdate or sodium molybdate solution, evaporate and crystallize to obtain ammonium molybdate, adjust the pH value of the remaining solution to 14, strip and evaporate ammonia, and pass the generated steam through sulfuric acid solution to obtain ammonium sulfate after evaporation and crystallization;

[0044] S3: adding 35% by mass of sodium hydroxide solution to the filter cake I obtained in step S2 until the solid-liquid ratio is 1:5, performing secondary leaching at 200° C. for 1 h, filtering to obtain a leachate II and a filter cake II, and evaporating and crystallizing the leachate II to obtain sodium aluminate;

[0045] S4: Add a 4 mol / L sulfuric acid solution to the filter cake II obtained in step S3 until the solid-liquid ratio is 1:5, leaching three times at 200° C. for 1 h, filtering, and evaporating and crystallizing the obtained leaching solution III to obtain nickel sulfate.

[0046] Example 3

[0047] A method for comprehensive recovery of spent catalysts comprises the following steps:

[0048] S1: The spent catalyst is pyrolyzed at 400°C in a nitrogen atmosphere for 1.2h, and then roasted at 360°C in an oxygen-deficient atmosphere (oxygen content <10%) for 2.5h to obtain a primary roasting product and flue gas; the obtained flue gas is passed through a cyclone bag to remove dust, and then passed through a secondary combustion chamber to be incinerated at 900°C to obtain high-temperature process steam, which is condensed and cooled through a heat exchanger from 900°C to 400°C, and then passed through a denitration device (SCR reactor) and a SO2 converter in sequence, cooled to 250°C, and then condensed in a condenser, the generated sulfuric acid is recovered, and the remaining process steam is stored in an intermediate tank;

[0049] S2: The primary calcined product obtained in step S1 is calcined at 500°C for 7h, then mixed with 32% by mass sodium carbonate solution into a loose gravel state (the ratio of the amount of sodium carbonate in the sodium carbonate solution to the total amount of vanadium pentoxide and molybdenum oxide in the primary calcined product is 2.8:1), dried at 118°C for 1.5h, then secondary calcined at 550°C for 5h, added with deionized water to a solid-liquid ratio of 1:3.6 after cooling, leached once at 65°C for 2.3h, filtered to obtain a leachate I and a filter cake I; the pH value of the leachate I is adjusted to 10.0, magnesium sulfate and ammonium sulfate are added, the total amount of magnesium sulfate and ammonium sulfate added is 97% of the theoretical phosphorus content in the leachate I, stirred until no more precipitation occurs, filtered to obtain a filtrate I, and the pH value of the filtrate I is adjusted to 8 .5, add ammonium sulfate, the amount of ammonium sulfate added is 3.5 times the mass of theoretical vanadium pentoxide in the filtrate, stir at 38°C for 1.2h until no more precipitates are precipitated, filter to obtain filtrate II and ammonium metavanadate, calcine ammonium metavanadate at 480°C for 1.5h to obtain vanadium pentoxide; adjust the pH value of filtrate II to 3.5, use weak base anion exchange resin to adsorb molybdenum in filtrate II, control the flow rate of filtrate II to 6BV / hr, no bias flow or bubbles should occur during operation, the breakthrough concentration of molybdenum is 0.02g / L, use 2.5mol / L sodium hydroxide solution for analysis, obtain high-concentration sodium molybdate solution, evaporate and crystallize to obtain sodium molybdate, adjust the pH value of the remaining solution to 13, strip ammonia, and pass the generated steam through sulfuric acid solution to obtain ammonium sulfate after evaporation and crystallization;

[0050] S3: adding 32% by mass of sodium hydroxide solution to the filter cake I obtained in step S2 until the solid-liquid ratio is 1:3.4, performing secondary leaching at 110° C. for 2.5 h, filtering to obtain a leachate II and a filter cake II, and evaporating and crystallizing the leachate II to obtain sodium aluminate;

[0051] S4: Add a 2.6 mol / L sulfuric acid solution to the filter cake II obtained in step S3 until the solid-liquid ratio is 1:3.4, leaching three times at 110°C for 2.5 hours, filtering, and evaporating and crystallizing the obtained leachate III to obtain nickel sulfate.

[0052] Comparative Example 1

[0053] The method for comprehensive recovery of waste catalyst described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the ratio of the amount of sodium carbonate in the sodium carbonate solution described in step S2 of this comparative example to the total amount of vanadium pentoxide and molybdenum oxide in the primary roasting product is 8:1.

[0054] Comparative Example 2

[0055] The method for comprehensive recovery of waste catalysts in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that in step S2 of this comparative example, the pH value of the leaching solution I is adjusted to 12.0.

[0056] Comparative Example 3

[0057] The method for comprehensive recovery of waste catalyst described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the total amount of magnesium sulfate and ammonium sulfate added in step S2 of this comparative example is 50% of the theoretical phosphorus content in the leachate I.

[0058] Comparative Example 4

[0059] The method for comprehensive recovery of waste catalyst described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the total amount of magnesium sulfate and ammonium sulfate added in step S2 of this comparative example is 150% of the theoretical phosphorus content in the leachate I.

[0060] Comparative Example 5

[0061] The method for comprehensive recovery of waste catalyst in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that in step S2 of this comparative example, the pH value of the filtrate I is adjusted to 12.0.

[0062] Comparative Example 6

[0063] The method for comprehensive recovery of waste catalyst in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the amount of ammonium sulfate added in step S2 of this comparative example is 10 times the mass of the theoretical vanadium pentoxide in the filtrate.

[0064] Comparative Example 7

[0065] The method for comprehensive recovery of waste catalyst in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the pH value of filtrate II is adjusted to 7.0 in step S2 of this comparative example.

[0066] Comparative Example 8

[0067] The method for comprehensive recovery of waste catalysts in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the concentration of the sodium hydroxide solution in step S2 of this comparative example is 10 mol / L.

[0068] Comparative Example 9

[0069] The method for comprehensive recovery of waste catalyst in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the mass percentage of the sodium hydroxide solution in step S3 of this comparative example is 50%.

[0070] Comparative Example 10

[0071] The method for comprehensive recovery of waste catalysts in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the concentration of the sulfuric acid solution in step S4 of this comparative example is 8 mol / L.

[0072] Test example

[0073] The vanadium pentoxide, sodium molybdate, sodium metaaluminate and nickel sulfate recovered in Examples 1 to 3 and Comparative Examples 1 to 10 were weighed, and the recovery rates of vanadium, molybdenum, aluminum and nickel were calculated. The test results are shown in Table 2.

[0074] Table 2 Recovery rate of valuable metals

[0075]

[0076] As can be seen from Table 2, the comprehensive recovery method of waste catalysts provided by the present invention can effectively realize the recovery of valuable metals such as vanadium, molybdenum, aluminum, and nickel, and the recovery rates of by-products are: ammonium metavanadate>98%, ammonium molybdate>98%, nickel sulfate>98%, sodium metaaluminate solution (Al2O3%=40-100g / L)>98%, among which Example 3 has the highest recovery rate of valuable metals such as vanadium, molybdenum, aluminum, and nickel, which is the best embodiment of the present invention.

[0077] Compared with Example 3, Comparative Example 1 changes the ratio of the amount of sodium carbonate in the sodium carbonate solution in step S2 to the total amount of vanadium pentoxide and molybdenum oxide in the primary roasting product, but the recovery rates of vanadium and molybdenum are reduced, which indicates that the amount of sodium carbonate used will affect the recovery rates of vanadium pentoxide and sodium molybdate; Comparative Example 2 changes the pH value of the leachate I in step S2, and Comparative Examples 3 and 4 change the total amount of magnesium sulfate and ammonium sulfate added in step S2, but the recovery rates of vanadium and molybdenum are reduced, which indicates that in the recovery process of vanadium and molybdenum, the pH value of the leachate I and the total amount of magnesium sulfate and ammonium sulfate added will affect the precipitation of a small amount of impurity precipitates in the leachate, thereby affecting the subsequent recovery of vanadium and molybdenum; Comparative Example 5 changes the pH value of the filtrate I in step S2, and Comparative Example 6 changes the amount of ammonium sulfate added in step S2, but the recovery rate of vanadium is reduced, which indicates that only Within the pH range provided by the present invention, vanadium in the filtrate I can be effectively recovered by adding ammonium sulfate within the specified range of the present invention; Comparative Example 7 changes the pH value of the filtrate II in step S2, and Comparative Example 8 changes the concentration of the sodium hydroxide solution in step S2, but the recovery rate of molybdenum is reduced, which shows that when recovering molybdenum with ion exchange resin, the pH value of the solution and the concentration of the analytical solution are the key factors affecting the recovery rate of molybdenum; Comparative Example 9 changes the mass percentage of the sodium hydroxide solution in step S3, but the recovery rates of aluminum and nickel are reduced, which shows that the main products in the filter cake I are aluminum oxide and nickel oxide, and the concentration of the sodium hydroxide solution is the key to affecting the leaching of aluminum and nickel; Comparative Example 10 changes the concentration of the sulfuric acid solution in step S4, but the recovery rate of nickel is reduced, which shows that the main component of the filter cake II is nickel oxide, and the concentration of the sulfuric acid solution is the key to affecting the leaching of nickel.

[0078] The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any person skilled in the art shall not modify the above embodiments without violating the spirit and scope of the present invention. Therefore, any modification, equivalent substitution and improvement made by those skilled in the art under the technical concept of the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for comprehensive recovery of spent catalysts, characterized in that: The following steps are involved: S1: Pyrolyze and roast the spent catalyst to obtain a primary roasting product and flue gas; after the flue gas is dedusted, it is incinerated to obtain high-temperature process steam, which is condensed and cooled, and passes through a denitrification device and a SO2 converter in sequence. After cooling, it is condensed in a condenser, the generated sulfuric acid is recovered, and the remaining process steam is stored in an intermediate tank; S2: roasting the primary calcined product obtained in step S1 and mixing it with a sodium carbonate solution, wherein the ratio of the amount of sodium carbonate in the sodium carbonate solution to the total amount of vanadium pentoxide and molybdenum oxide in the primary calcined product is 1.5-4:1, drying, secondary roasting, adding deionized water after cooling, leaching once, filtering, and obtaining a leachate I and a filter cake I; adjusting the pH value of the leachate I to 9.5-10.5, adding magnesium sulfate and ammonium sulfate, wherein the total amount of magnesium sulfate and ammonium sulfate added is 90%-105% of the theoretical phosphorus content in the leachate I, and stirring until precipitation. The precipitate no longer precipitates, and a filtrate I is obtained after filtration. The pH value of the filtrate I is adjusted to 8-9, and ammonium sulfate is added. The amount of ammonium sulfate added is 1.0-5.0 times the mass of the theoretical vanadium pentoxide in the filtrate. Stirring is continued until the precipitate no longer precipitates, and the filtrate II and ammonium metavanadate are obtained. The ammonium metavanadate is roasted to obtain vanadium pentoxide; the pH value of the filtrate II is adjusted to 3-4, and the molybdenum in the filtrate II is recovered by using an ion exchange resin. The pH value of the remaining solution is adjusted to 12-14, and ammonia is stripped and evaporated. The generated steam passes through a sulfuric acid solution, and ammonium sulfate is obtained after evaporation and crystallization; S3: adding sodium hydroxide solution to the filter cake I obtained in step S2, performing secondary leaching, filtering, and obtaining a leachate II and a filter cake II; S4: adding sulfuric acid solution to the filter cake II obtained in step S3, leaching for three times, filtering, and evaporating and crystallizing the obtained leaching solution III to obtain nickel sulfate.

2. The method for comprehensive recovery of spent catalyst according to claim 1, characterized in that: The pyrolysis in step S1 is carried out in a nitrogen atmosphere at a temperature of 300-450°C for 0.5-2h; the calcination is carried out in an oxygen-deficient atmosphere with an oxygen content of less than 10%, at a temperature of 300-400°C for 1-4h.

3. The method for comprehensive recovery of spent catalyst according to claim 1, characterized in that: The incineration temperature in step S1 is 800-1000°C; the temperature of the high-temperature process steam after condensation and cooling through the heat exchanger is reduced from 800-1000°C to 380-420°C; the cooling temperature is 200-300°C.

4. The method for comprehensive recovery of spent catalyst according to claim 1, characterized in that: The temperature of the secondary roasting in step S2 is 400-600° C., and the roasting time is 5-8 hours; the deionized water is added to a solid-liquid ratio of 1:2.5-5; and the mass percentage of the sodium carbonate solution is 30%-33%.

5. The method for comprehensive recovery of spent catalyst according to claim 1, characterized in that: The drying temperature in step S2 is 115-120°C, and the drying time is 1-2h; the secondary roasting temperature is 500-600°C, and the secondary roasting time is 3-8h; the leaching temperature is 25-90°C, and the leaching time is 1-4h.

6. The method for comprehensive recovery of spent catalyst according to claim 1, characterized in that: The stirring temperature in step S2 is 25-50° C. and the stirring time is 0.5-2 h. The temperature for calcining ammonium metavanadate is 450-500° C. and the time is 1-2 h.

7. The method for comprehensive recovery of spent catalyst according to claim 1, characterized in that: The specific operation of recovering molybdenum in the filtrate II with an ion exchange resin in step S2 is as follows: adsorbing the molybdenum in the filtrate II with a weakly basic anion exchange resin, controlling the flow rate of the filtrate II to 2-8BV / hr, the breakthrough concentration of molybdenum to 0.02g / L, and analyzing with 1-4mol / L ammonia water or sodium hydroxide solution to obtain a high concentration of ammonium molybdate or sodium molybdate solution, and obtaining ammonium molybdate or sodium molybdate after evaporation and crystallization.

8. The method for comprehensive recovery of spent catalyst according to claim 1, characterized in that: The mass percentage of the sodium hydroxide in step S3 is 30%-35%, and the sodium hydroxide solution is added to a solid-liquid ratio of 1:2.5-5; the temperature of the secondary leaching is 25-200° C., and the time is 1-4 hours.

9. The method for comprehensive recovery of spent catalyst according to claim 1, characterized in that: The concentration of the sulfuric acid solution in step S4 is 0.5-4 mol / L, and the sulfuric acid solution is added to a solid-liquid ratio of 1:2.5-5; the temperature of the three leachings is 25-200° C., and the time is 1-4 hours.

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