CN117566790A - Method for recycling and purifying thallium-poisoning waste SCR denitration catalyst - Google Patents
Method for recycling and purifying thallium-poisoning waste SCR denitration catalyst Download PDFInfo
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- CN117566790A CN117566790A CN202311538743.XA CN202311538743A CN117566790A CN 117566790 A CN117566790 A CN 117566790A CN 202311538743 A CN202311538743 A CN 202311538743A CN 117566790 A CN117566790 A CN 117566790A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 95
- 239000002699 waste material Substances 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000004064 recycling Methods 0.000 title claims abstract description 23
- 208000026015 thallium poisoning Diseases 0.000 title claims abstract description 21
- 238000006243 chemical reaction Methods 0.000 claims abstract description 52
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000003513 alkali Substances 0.000 claims abstract description 22
- 239000012065 filter cake Substances 0.000 claims abstract description 20
- 239000000047 product Substances 0.000 claims abstract description 15
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 13
- 239000012535 impurity Substances 0.000 claims abstract description 13
- 239000002253 acid Substances 0.000 claims abstract description 9
- 238000001704 evaporation Methods 0.000 claims abstract description 9
- 230000008020 evaporation Effects 0.000 claims abstract description 9
- 239000002002 slurry Substances 0.000 claims description 48
- 230000020477 pH reduction Effects 0.000 claims description 30
- 239000008367 deionised water Substances 0.000 claims description 18
- 229910021641 deionized water Inorganic materials 0.000 claims description 18
- 238000009835 boiling Methods 0.000 claims description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 238000001914 filtration Methods 0.000 claims description 15
- 238000005903 acid hydrolysis reaction Methods 0.000 claims description 9
- 239000010881 fly ash Substances 0.000 claims description 9
- 150000003839 salts Chemical class 0.000 claims description 9
- 239000000428 dust Substances 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- 239000011148 porous material Substances 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 8
- 238000010408 sweeping Methods 0.000 claims description 8
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 claims description 7
- 235000019345 sodium thiosulphate Nutrition 0.000 claims description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical class [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical class [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 4
- RQPZNWPYLFFXCP-UHFFFAOYSA-L barium dihydroxide Chemical class [OH-].[OH-].[Ba+2] RQPZNWPYLFFXCP-UHFFFAOYSA-L 0.000 claims description 4
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical class [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 2
- 239000011777 magnesium Substances 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 230000009467 reduction Effects 0.000 claims description 2
- 229910010413 TiO 2 Inorganic materials 0.000 claims 1
- 229910052716 thallium Inorganic materials 0.000 abstract description 22
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 0.000 abstract description 22
- 238000004065 wastewater treatment Methods 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 2
- 229910003077 Ti−O Inorganic materials 0.000 abstract 2
- 238000005457 optimization Methods 0.000 abstract 2
- 230000002378 acidificating effect Effects 0.000 abstract 1
- 238000000746 purification Methods 0.000 abstract 1
- 239000011734 sodium Substances 0.000 description 12
- 239000000243 solution Substances 0.000 description 10
- 229910004298 SiO 2 Inorganic materials 0.000 description 7
- 239000004568 cement Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- 239000003546 flue gas Substances 0.000 description 4
- GFNGCDBZVSLSFT-UHFFFAOYSA-N titanium vanadium Chemical compound [Ti].[V] GFNGCDBZVSLSFT-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000002920 hazardous waste Substances 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 206010008428 Chemical poisoning Diseases 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000011028 pyrite Substances 0.000 description 1
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 description 1
- 229910052683 pyrite Inorganic materials 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
- C01G23/053—Producing by wet processes, e.g. hydrolysing titanium salts
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Catalysts (AREA)
Abstract
The invention discloses a recycling and purifying method of thallium poisoning waste SCR denitration catalyst, which belongs to the technical field of denitration catalysts, wherein waste SCR denitration catalyst is dedusted, disassembled, and then a catalyst body is collected, the catalyst body is crushed, slurried, pressurized and boiled with alkali, filtered, a filter cake is slurried again, added with strong acid and reducing agent, acidified and filtered again, and the filter cake is transferred into a flash evaporation furnace to remove water to obtain Ti-O 2 A product; the thallium poisoning waste SCR denitration catalyst recycling and purifying method is characterized in that the reducing agent is added under the acidic condition through optimization of the reducing agent and optimization of the reaction condition, so that thallium is thoroughly removed, and the thallium is efficiently removed; the method does not introduce other impurities, has good purification effect, and is effective in treating Ti-O 2 The product purity is high, which is helpful for reducing the difficulty of wastewater treatment and is more efficient.
Description
Technical Field
The invention belongs to the technical field of denitration catalysts, and particularly relates to a method for recycling and purifying a thallium-poisoning waste SCR denitration catalyst.
Background
With the increasingly strict emission control of thermal power, steel, cement and other industrial kilns on nitrogen oxides, the demand of denitration catalyst products is gradually increased. Among various denitration technologies, the application technology of the vanadium-titanium SCR denitration catalyst is the most mature, the application range is wide, the denitration efficiency is high, the use cost is low, and the vanadium-titanium SCR denitration catalyst is widely accepted and applied to the market. Because the denitration catalyst is replaced in about 3 years due to the technical characteristics, a large amount of waste vanadium-titanium denitration catalysts can be produced, and meanwhile, according to the regulations in the national hazardous waste directory (2021 edition): the waste denitration catalyst (vanadium-titanium system) belongs to hazardous waste (HW 50 waste catalyst), and if the catalyst is randomly piled up or improperly utilized and disposed of, the waste denitration catalyst can cause environmental pollution and resource waste.
The main raw materials used in cement production include limestone, fly ash, pyrite, etc., and these raw materials and fuel coal contain a small amount of thallium (T l). In the cement kiln clinker calcination process, the temperature can reach 900-1500 ℃, thallium in raw material minerals and fuel coal is mixed into flue gas in a gaseous state under the high temperature condition, and various harmful substances and ash generated in the cement kiln combustion can pass through the SCR denitration catalyst along with the flue gas, so that the physical blockage and chemical poisoning of the catalyst are caused, and the activity of the catalyst is further reduced. Thallium substances have strong electron donating ability, and thallium substances in the flue gas are easy to be adsorbed on the carrier T iO preferentially 2 On, lead to hydroxyl groups on the catalyst surface being T l 2 O 3 Substitution followed by subsequent enrichment of thallium species on the catalyst surface with thalliumThe material occupies and destroys the active sites of the catalyst surface and ti O 2 The T i- (OH) -T i bridging sites of the catalyst lead to a significant reduction in the number and strength of acid sites on the catalyst surface, and simultaneously thallium is used as a sulfur-philic element, thallium-containing species adsorbed on the catalyst surface can react with SO in flue gas 2 Reaction to form T l 2 SO 4 T l further covering the catalyst surface 2 O 3 On the catalyst surface with final thallium as T l 2 O 3 And T l 2 SO 4 The form is covered by layers, so that the thallium of the catalyst is poisoned, and the catalytic activity is obviously reduced.
The prior art mainly aims at thallium poisoning catalyst regeneration treatment (CN 111715210A, CN111589473B, CN113600248A, CN 112827354A), and no intensive study is made on thallium removal by recycling treatment. The Chinese patent with publication number of CN113600248A is cleaned twice by sulfuric acid and nitric acid respectively, and is matched with an oxidant, a dispersant, a chelating agent and the like, so that the process flow is complex, more impurities are introduced, and the wastewater treatment difficulty is high; the Chinese patent with publication No. CN111589473B and publication No. CN112827354A mainly adopts dilute sulfuric acid method, has low thallium removal efficiency, and has high thallium content after treatment according to the thallium poisoning condition of the existing retired spent catalyst in the cement industry (thallium content of 3-5 wt%).
Disclosure of Invention
The invention aims to provide a method for recycling, utilizing and purifying thallium-poisoned waste SCR denitration catalyst, which solves the problem that thallium is difficult to thoroughly remove during recycling of the SCR denitration catalyst in the prior art, and efficiently removes thallium by a simple method and a simple process to obtain a high-purity titanium dioxide product.
The aim of the invention can be achieved by the following technical scheme:
a method for recycling and purifying thallium-poisoning waste SCR denitration catalyst comprises the following steps:
step one: placing the waste SCR denitration catalyst in a negative pressure dust collection workshop, sweeping fly ash on the surface and in a pore canal of the waste SCR denitration catalyst by using compressed air, then disassembling and removing a metal frame of the waste SCR denitration catalyst, and collecting a catalyst body;
step two: crushing a catalyst body, adding deionized water to disperse the catalyst body into first slurry with the solid content of 20% -35%, transferring the first slurry into a reaction kettle, adding strong alkali liquor into the reaction kettle, and carrying out pressurized alkali boiling for 1-4h under the conditions of the pressure of 0.2-2MPa and the temperature of 100-200 ℃;
step three: filtering the first slurry after pressurized alkali boiling, dispersing the filter cake into a second slurry by deionized water, transferring to an acidification tank, adding strong acid and reducing agent into the acidification tank, and acidifying at 50-150deg.C for 1-4 hr to obtain insoluble T l 3+ Reduced to readily soluble T l + ，T iO 3 2- Acid hydrolysis of salt to produce H 2 T iO 3 Simultaneously removing acid-soluble impurities;
further, strong alkaline solutions include, but are not limited to, saturated sodium hydroxide solutions, saturated potassium hydroxide solutions, saturated barium hydroxide solutions, and saturated lithium hydroxide solutions.
Further, in the second step, the mass ratio of the first slurry to the strong alkali solution is 15-20:1.
further, strong acids include, but are not limited to, 90% -98% sulfuric acid by mass, 20% -30% nitric acid by mass, and 20% -30% perchloric acid by mass.
Further, reducing agents include, but are not limited to, magnesium tape, aluminum powder, sodium thiosulfate, and zinc powder.
Further, in the third step, the mass ratio of the filter cake, deionized water, strong acid and reducing agent is 100:200-400:1-20:0.02-5.
Step four: filtering the second slurry after the acidification reaction, transferring the filter cake into a flash evaporation furnace to remove water to obtain SiO 2 And (5) a product.
The invention has the beneficial effects that:
the method for recycling and purifying the thallium-poisoning waste SCR denitration catalyst of the invention optimizes the reducing agent and the reaction condition, adds the reducing agent under the strong acid condition, thoroughly removes thallium and ensures that the insoluble T l 3+ Reduced to readily soluble T l + The thallium removal rate reaches over 96 percent, which is favorable for realizingEfficient removal of thallium.
The filtrate after the pressurized alkali boiling and acidification reaction can recycle other noble metals, tiO 3 2- Acid hydrolysis of salt to produce H 2 T i O 3 Meanwhile, acid-soluble impurities in the wastewater are removed, so that the recycling utilization rate is improved, the wastewater treatment difficulty is reduced, and the wastewater treatment device is more environment-friendly and efficient.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1: the embodiment provides a method for recycling, utilizing and purifying thallium-poisoning waste SCR denitration catalyst, which comprises the following implementation steps:
step one: placing the waste SCR denitration catalyst in a negative pressure dust collection workshop, sweeping fly ash on the surface and in a pore canal of the waste SCR denitration catalyst by using compressed air, then disassembling and removing a metal frame of the waste SCR denitration catalyst, and collecting a catalyst body.
Step two: crushing the catalyst body, adding deionized water to disperse the catalyst body into first slurry with the solid content of 20%, transferring 1500kg of the first slurry into a reaction kettle, adding 100kg of saturated barium hydroxide solution into the reaction kettle, and carrying out pressurized alkali boiling for 4 hours under the conditions of 0.2MPa pressure and 100 ℃. The main reactions are as follows:
V 2 O 5 +Ba(OH) 2 ＝Ba(V0 3 ) 2 +H 2 O
WO 3 +Ba(OH) 2 ＝BaWO 4 +H 2 O
T iO 2 +Ba(OH) 2 ＝BaT iO 3 +H 2 O
step three: filtering the first slurry after pressurized alkali boiling, dispersing 100kg of filter cake into a second slurry by 200kg of deionized water and transferring to acidAdding 1kg of 90% sulfuric acid and 0.02kg of aluminum powder into an acidification tank, and acidifying at 50deg.C for 4 hr to obtain insoluble T l 3+ Reduced to readily soluble T l + ，T iO 3 2- Acid hydrolysis of salt to produce H 2 T iO 3 While removing acid-soluble impurities therefrom. The main reactions are as follows:
3T l 2 (SO 4 ) 3 +4A l＝3T l 2 SO 4 +2A l 2 (SO 4 ) 3
BaT i O 3 +H 2 SO 4 ＝H 2 T iO 3 (s)+BaSO 4
step four: filtering the second slurry after the acidification reaction, transferring the filter cake into a flash evaporation furnace to remove water to obtain SiO 2 And (5) a product. The main reactions are as follows:
H 2 T iO 3 ＝T iO 2 +H 2 O(g)↑
example 2: the embodiment provides a method for recycling, utilizing and purifying thallium-poisoning waste SCR denitration catalyst, which comprises the following implementation steps:
step one: placing the waste SCR denitration catalyst in a negative pressure dust collection workshop, sweeping fly ash on the surface and in a pore canal of the waste SCR denitration catalyst by using compressed air, then disassembling and removing a metal frame of the waste SCR denitration catalyst, and collecting a catalyst body.
Step two: crushing the catalyst body, adding deionized water to disperse the catalyst body into first slurry with the solid content of 30%, transferring 1500kg of the first slurry into a reaction kettle, adding 100kg of saturated potassium hydroxide solution into the reaction kettle, and carrying out pressurized alkali boiling for 2.5h under the conditions of 1MPa pressure and 150 ℃. The main reactions are as follows:
V 2 O 5 +2KOH＝2KV0 3 +H 2 O
WO 3 +2KOH＝K 2 WO 4 +H 2 O
T iO 2 +2KOH＝K 2 T iO 3 +H 2 O
step three: will be pressurizedFiltering the first slurry after alkaline boiling, dispersing 100kg of filter cake into a second slurry by using 300kg of deionized water, transferring the second slurry into an acidification tank, adding 10kg of sulfuric acid with the mass fraction of 98% and 2kg of aluminum powder into the acidification tank, and carrying out acidification reaction for 2.5 hours at 100 ℃ to obtain insoluble T l 3+ Reduced to readily soluble T l + ，T iO 3 2- Acid hydrolysis of salt to produce H 2 T iO 3 While removing acid-soluble impurities therefrom. The main reactions are as follows:
3T l 2 (SO 4 ) 3 +4A l＝3T l 2 SO 4 +2A l 2 (SO 4 ) 3
K 2 T iO 3 +H 2 SO 4 ＝H 2 T iO 3 (s)+K 2 SO 4
step four: filtering the second slurry after the acidification reaction, transferring the filter cake into a flash evaporation furnace to remove water to obtain SiO 2 And (5) a product. The main reactions are as follows:
H 2 T iO 3 ＝T iO 2 +H 2 O(g)↑
example 3: the embodiment provides a method for recycling, utilizing and purifying thallium-poisoning waste SCR denitration catalyst, which comprises the following implementation steps:
step one: placing the waste SCR denitration catalyst in a negative pressure dust collection workshop, sweeping fly ash on the surface and in a pore canal of the waste SCR denitration catalyst by using compressed air, then disassembling and removing a metal frame of the waste SCR denitration catalyst, and collecting a catalyst body.
Step two: after crushing the catalyst body, adding deionized water to disperse into first slurry with the solid content of 35%, transferring 2000kg of the first slurry into a reaction kettle, adding 100kg of saturated sodium hydroxide solution into the reaction kettle, and carrying out pressurized alkali boiling for 1h under the conditions of 2MPa pressure and 200 ℃. The main reactions are as follows:
V 2 O 5 +2NaOH＝2NaV0 3 +H 2 O
WO 3 +2NaOH＝Na 2 WO 4 +H 2 O
T iO 2 +2NaOH＝Na 2 T iO 3 +H 2 O
step three: filtering the first slurry after pressurized alkali boiling, dispersing 100kg of filter cake into a second slurry by using 400kg of deionized water, transferring the second slurry into an acidification tank, adding 20kg of nitric acid with mass fraction of 20% and 5kg of aluminum powder into the acidification tank, and carrying out acidification reaction for 4 hours at 150 ℃ to obtain insoluble T l 3+ Reduced to readily soluble T l + ，T iO 3 2- Acid hydrolysis of salt to produce H 2 T iO 3 While removing acid-soluble impurities therefrom. The main reactions are as follows:
3T l(NO 3 ) 3 +2A l＝3T l NO 3 +2A l(NO 3 ) 3
Na 2 T iO 3 +2HNO 3 ＝H 2 T iO 3 (s)+2NaNO 3
step four: filtering the second slurry after the acidification reaction, transferring the filter cake into a flash evaporation furnace to remove water to obtain SiO 2 And (5) a product. The main reactions are as follows:
H 2 T iO 3 ＝T iO 2 +H 2 O(g)↑
example 4: the embodiment provides a method for recycling, utilizing and purifying thallium-poisoning waste SCR denitration catalyst, which comprises the following implementation steps:
step one: placing the waste SCR denitration catalyst in a negative pressure dust collection workshop, sweeping fly ash on the surface and in a pore canal of the waste SCR denitration catalyst by using compressed air, then disassembling and removing a metal frame of the waste SCR denitration catalyst, and collecting a catalyst body.
Step two: crushing the catalyst body, adding deionized water to disperse the catalyst body into first slurry with the solid content of 20%, transferring 1500kg of the first slurry into a reaction kettle, adding 100kg of saturated barium hydroxide solution into the reaction kettle, and carrying out pressurized alkali boiling for 4 hours under the conditions of 0.2MPa pressure and 100 ℃. The main reactions are as follows:
V 2 O 5 +Ba(OH) 2 ＝Ba(V0 3 ) 2 +H 2 O
WO 3 +Ba(OH) 2 ＝BaWO 4 +H 2 O
T iO 2 +Ba(OH) 2 ＝BaT iO 3 +H 2 O
step three: filtering the first slurry after pressurized alkali boiling, dispersing 100kg of filter cake into a second slurry by using 200kg of deionized water, transferring the second slurry into an acidification tank, adding 1kg of sulfuric acid with the mass fraction of 95% and 0.02kg of sodium thiosulfate into the acidification tank, and carrying out acidification reaction for 4 hours at 50 ℃ to obtain insoluble T l 3+ Reduced to readily soluble T l + ，T iO 3 2- Acid hydrolysis of salt to produce H 2 T iO 3 While removing acid-soluble impurities therefrom. The main reactions are as follows:
2T l 2 (SO 4 ) 3 +Na 2 S 2 O 3 +5H 2 O＝2T l 2 SO 4 +Na 2 SO 4 +5H 2 SO 4
BaT i O 3 +H 2 SO 4 ＝H 2 T iO 3 (s)+BaSO 4
step four: filtering the second slurry after the acidification reaction, transferring the filter cake into a flash evaporation furnace to remove water to obtain SiO 2 And (5) a product. The main reactions are as follows:
H 2 T iO 3 ＝T iO 2 +H 2 O(g)↑
example 5: the embodiment provides a method for recycling, utilizing and purifying thallium-poisoning waste SCR denitration catalyst, which comprises the following implementation steps:
step one: placing the waste SCR denitration catalyst in a negative pressure dust collection workshop, sweeping fly ash on the surface and in a pore canal of the waste SCR denitration catalyst by using compressed air, then disassembling and removing a metal frame of the waste SCR denitration catalyst, and collecting a catalyst body.
Step two: crushing the catalyst body, adding deionized water to disperse the catalyst body into first slurry with the solid content of 30%, transferring 1500kg of the first slurry into a reaction kettle, adding 100kg of saturated potassium hydroxide solution into the reaction kettle, and carrying out pressurized alkali boiling for 2.5h under the conditions of 1MPa pressure and 150 ℃. The main reactions are as follows:
V 2 O 5 +2KOH＝2KV0 3 +H 2 O
WO 3 +2KOH＝K 2 WO 4 +H 2 O
T iO 2 +2KOH＝K 2 T iO 3 +H 2 O
step three: filtering the first slurry after pressurized alkali boiling, dispersing 100kg of filter cake into a second slurry by using 300kg of deionized water, transferring the second slurry into an acidification tank, adding 10kg of sulfuric acid with the mass fraction of 98% and 2kg of sodium thiosulfate into the acidification tank, and carrying out acidification reaction for 2.5 hours at the temperature of 100 ℃ to obtain insoluble T l 3+ Reduced to readily soluble T l + ，T iO 3 2- Acid hydrolysis of salt to produce H 2 T iO 3 While removing acid-soluble impurities therefrom. The main reactions are as follows:
2T l 2 (SO 4 ) 3 +Na 2 S 2 O 3 +5H 2 O＝2T l 2 SO 4 +Na 2 SO 4 +5H 2 SO 4
K 2 T iO 3 +H 2 SO 4 ＝H 2 T iO 3 (s)+K 2 SO 4
step four: filtering the second slurry after the acidification reaction, transferring the filter cake into a flash evaporation furnace to remove water to obtain SiO 2 And (5) a product. The main reactions are as follows:
H 2 T iO 3 ＝T iO 2 +H 2 O(g)↑
example 6: the embodiment provides a method for recycling, utilizing and purifying thallium-poisoning waste SCR denitration catalyst, which comprises the following implementation steps:
step one: placing the waste SCR denitration catalyst in a negative pressure dust collection workshop, sweeping fly ash on the surface and in a pore canal of the waste SCR denitration catalyst by using compressed air, then disassembling and removing a metal frame of the waste SCR denitration catalyst, and collecting a catalyst body.
Step two: after crushing the catalyst body, adding deionized water to disperse into first slurry with the solid content of 35%, transferring 2000kg of the first slurry into a reaction kettle, adding 100kg of saturated sodium hydroxide solution into the reaction kettle, and carrying out pressurized alkali boiling for 1h under the conditions of 2MPa pressure and 200 ℃. The main reactions are as follows:
V 2 O 5 +2NaOH＝2NaV0 3 +H 2 O
WO 3 +2NaOH＝Na 2 WO 4 +H 2 O
T iO 2 +2NaOH＝Na 2 T iO 3 +H 2 O
step three: filtering the first slurry after pressurized alkali boiling, dispersing 100kg of filter cake into a second slurry by using 400kg of deionized water, transferring the second slurry into an acidification tank, adding 20kg of nitric acid with the mass fraction of 30% and 5kg of sodium thiosulfate into the acidification tank, and carrying out acidification reaction for 1h at 150 ℃ to obtain insoluble T l 3+ Reduced to readily soluble T l + ，T iO 3 2- Acid hydrolysis of salt to produce H 2 T iO 3 While removing acid-soluble impurities therefrom. The main reactions are as follows:
4T l(NO 3 ) 3 +Na 2 S 2 O 3 +5H 2 O＝4T l NO 3 +Na 2 SO 4 +H 2 SO 4 +8HNO 3
Na 2 T iO 3 +2HNO 3 ＝H 2 T iO 3 (s)+2NaNO 3
step four: filtering the second slurry after the acidification reaction, transferring the filter cake into a flash evaporation furnace to remove water to obtain SiO 2 And (5) a product. The main reactions are as follows:
H 2 T iO 3 ＝T iO 2 +H 2 O(g)↑
comparative example 1: based on example 6, the reducing agent was replaced by sodium sulfite from sodium thiosulfate, the remaining steps remained unchanged, to prepare TIO 2 And (5) a product.
Comparative example 2: on the basis of example 6, the reducing agent was replaced by sodium thiosulfate with ascorbic acid, the remaining steps remaining unchangedPreparing the TIO 2 And (5) a product.
Performance tests were performed on examples 1-6 and comparative examples 1-2 to prepare TIO under different methods 2 The thallium removal rate and the analysis result of the introduced impurities are shown in table 1:
TABLE 1
As can be seen from Table 1, T i O obtained by the method of example 1-example 6 2 The thallium removal rate of the product is high, and no impurity is introduced.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. The method for recycling and purifying the thallium-poisoning waste SCR denitration catalyst is characterized by comprising the following steps of:
step one: placing the waste SCR denitration catalyst in a negative pressure dust collection workshop, sweeping fly ash on the surface and in a pore canal of the waste SCR denitration catalyst by using compressed air, then disassembling and removing a metal frame of the waste SCR denitration catalyst, and collecting a catalyst body;
step two: crushing a catalyst body, adding deionized water to disperse the catalyst body into first slurry with the solid content of 20% -35%, transferring the first slurry into a reaction kettle, adding strong alkali liquor into the reaction kettle, and carrying out pressurized alkali boiling for 1-4h under the conditions of the pressure of 0.2-2MPa and the temperature of 100-200 ℃;
step three: filtering the first slurry after pressurized alkali boiling, dispersing a filter cake into second slurry by deionized water, transferring the second slurry into an acidification tank, adding strong acid and a reducing agent into the acidification tank, and carrying out acidification reaction for 1-4h at 50-150 ℃; to poorly soluble Tl 3+ Reduction to readily soluble Tl + ，TiO 3 2- Acid hydrolysis of salt to produce H 2 TiO 3 Simultaneously removing acid-soluble impurities;
step four: filtering the second slurry after the acidification reaction, transferring the filter cake into a flash evaporation furnace to remove water to obtain TiO 2 And (5) a product.
2. The method for recycling and purifying the thallium poisoning waste SCR denitration catalyst according to claim 1, wherein the strong alkali solution in the second step includes, but is not limited to, saturated sodium hydroxide solution, saturated potassium hydroxide solution, saturated barium hydroxide solution and saturated lithium hydroxide solution.
3. The method for recycling and purifying thallium-poisoning waste SCR denitration catalyst according to claim 1, wherein in the second step, the mass ratio of the first slurry to the strong alkali solution is 15-20:1.
4. the method for recycling and purifying thallium-poisoning waste SCR denitration catalyst according to claim 1, wherein the strong acid in the third step includes but is not limited to sulfuric acid, nitric acid and perchloric acid.
5. The method for recycling and purifying the thallium-poisoning waste SCR denitration catalyst according to claim 1, wherein the reducing agent in the third step comprises but is not limited to magnesium strip, aluminum powder, sodium thiosulfate and zinc powder.
6. The method for recycling and purifying the thallium-poisoning waste SCR denitration catalyst according to claim 1, wherein in the third step, the mass ratio of the filter cake, deionized water, strong acid and reducing agent is 100:200-400:1-20:0.02-5.
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