CN115194163B - A method for preparing titanium tungsten powder by recycling waste SCR denitrification catalyst - Google Patents

Abstract

The invention relates to a method for recovering and preparing titanium-tungsten powder from a waste denitrification catalyst, and belongs to the field of recovery of waste denitrification catalysts. In the present invention, the waste denitrification catalyst is pretreated by dust removal, crushing and grinding to obtain the waste denitration catalyst powder, and the powder with high tungsten content is obtained through a flat throwing layering process to obtain a powder with a high tungsten content, and the powder is mixed with a calcium compound Mix evenly at 1: (0.2‑0.8), add ultrapure water at a liquid-solid ratio of 1: (5‑10), and then input it into a ball mill for grinding reaction to obtain a slurry. The slurry is calcined in a rotary kiln to obtain the reaction mixture of the spent denitrification catalyst and the calcium compound, pickling and dissolving the calcium vanadate therein, and then filtering; the filter residue is washed and dried, and then ground to obtain titanium tungsten powder, and the filtrate is adjusted to make the vanadic acid After calcium precipitation, filter and dry. Obtain titanium tungsten powder to be finely ground. The invention forms calcification by high-temperature calcination to extract vanadium element in the waste denitration catalyst to obtain titanium-tungsten powder material, which reduces the calcination cost.

Description

A method for preparing titanium tungsten powder by recycling waste SCR denitrification catalyst

technical field

The invention belongs to the field of recovery of waste denitration catalysts, and in particular relates to a method for producing titanium-tungsten powder from waste denitration catalysts based on a high-temperature calcination method.

Background technique

The selective catalytic reduction denitrification technology uses the denitrification catalyst as the core of the process to remove nitrogen oxides in the flue gas. This process is the most widely used flue gas denitrification technology in the coal industry due to its high efficiency and stability, but the denitrification catalyst The service life is 2-3 years, and it is scrapped due to the deactivation of various catalysts due to the action of flue gas with complex components during use. In recent years, as a large number of catalysts have reached the end of their service life, the output of spent denitration catalysts has continued to increase.

Metal elements such as vanadium, tungsten, and titanium, which are the main components of waste denitrification catalysts, are important metal resources and have extremely high recovery value. It not only obtains economic benefits but also reduces environmental pollution.

Patent CN112408470A discloses a method for producing titanium dioxide with waste denitrification catalyst based on high-temperature calcination, including steps such as cleaning and impurity removal, crushing, lye mixing, calcining, grinding, filtering and washing, drying, and fine grinding to obtain titanium dioxide and Vanadium tungsten products, but adding two lye to react and using a large amount of water washing to reduce the pH of the filtrate, not only increases the consumption of alkali but also produces a large amount of waste liquid that is difficult to handle, and the production cost is high.

Chinese patent CN101921916A discloses a method for recovering metal oxides from waste flue gas denitrification catalysts, including primary roasting, crushing, grinding, mixing alkali, secondary roasting, hot water soaking, precipitation filtration, pickling, water washing, roasting Titanium dioxide is obtained, and the filtrate is subsequently processed to obtain V ₂ O ₅ , MoO ₃ and WO ₃ products; however, this process uses two high-temperature roasts, and sodium carbonate needs to be mixed and ground to <200 μm before the second roast, and the operation is relatively It is cumbersome, and at the same time, the patent mainly discusses the preparation of V ₂ O ₅ , MoO ₃ and WO ₃ products in detail, and mainly aims at the recovery of these three products of V ₂ O ₅ , MoO ₃ and WO ₃ . Chinese patent CN106337133B discloses a recovery method of titanium, vanadium and tungsten in waste denitrification catalysts: mix waste denitrification catalysts, iron-containing raw materials, carbon-containing raw materials, binders and calcium-containing raw materials, and granulate them into spherical materials. Calcined under high temperature conditions to obtain vanadium-tungsten-containing pig iron and titanium slag. The calcination temperature of this process is high, resulting in changes in the crystal form of TiO ₂ and high energy consumption, which is not suitable for the preparation or production of titanium dioxide. CN202011187934.2 discloses a process for treating waste vanadium-titanium denitrification catalysts, which includes the following steps: crushing and pulverizing: crushing the vanadium-titanium series denitrification waste catalysts into powders below 100 μm; sodium roasting: pulverized vanadium-titanium series denitrification The waste catalyst is mixed with soda ash and water in a certain proportion, and then added to the rotary kiln for sodium roasting transformation; leaching: the mixture is added to the water ball mill and sieved to obtain the filtrate and filter residue; vanadium recovery: add excess ammonium chloride to the filtrate, and mechanically stir 0.5-1h, static precipitation, filtration to obtain filtrate and ammonium metavanadate; recovery of molybdic acid and tungstic acid: heat the filtrate steam to 60 ℃ ~ 70 ℃, adjust the pH value to 2 with sulfuric acid, and filter to obtain molybdic acid and tungstic acid and filtrate; adjust the pH value and wash: filter residue and water are put into the reactor according to the mass ratio of 1:10～1:150, adjust the pH of the solution to ≤6.0 with inorganic acid, keep it warm, and wash the reaction product with water after solid-liquid separation Solid, obtained titanic acid precipitation; Calcination: calcining titanic acid precipitation to obtain TiO ₂ .

Contents of the invention

The invention provides a method for producing titanium-tungsten powder with waste denitrification catalyst based on a high-temperature calcination method. After the waste denitration catalyst is crushed and ground, the heavy powder with higher tungsten content is kept in the front through a flat throwing layering process. layer, so as to remove light impurities such as alkali metals and obtain powders with high tungsten content, which are wet-milled to form a slurry and then calcined to improve the reaction rate of waste denitrification catalytic metal oxides and calcium compounds, and then separate different metals by pickling element. The filter residue is dried to obtain titanium and tungsten powder before use, and the vanadium in the filtrate is recovered by precipitation. The main purpose of the present invention is to solve the following technical problems in related technologies: first, to increase the recycling rate of spent denitrification catalysts and reduce environmental pollution; second, to simplify the process flow and recovery cost of titanium-tungsten powder.

The present invention is achieved through the following technical solutions:

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitration catalyst, characterized in that the method comprises the following steps:

(1) After the waste denitration catalyst is pretreated by dust removal, crushing and grinding, the waste denitration catalyst powder is obtained, and the powder with high tungsten content is obtained through the flat throwing layering process to obtain a powder with a high tungsten content. Mix evenly with the calcium compound at 1: (0.2-0.8), add ultrapure water according to the liquid-solid ratio (5-10): 1, and then input it into a ball mill for grinding reaction to obtain a slurry;

(2) Calcining the slurry to obtain a reaction mixture of the spent denitrification catalyst and the calcium compound, pickling and dissolving the calcium vanadate therein, and then filtering. The acidic filtrate is reused several times, and the filter residue is washed and dried, and then pulverized to obtain titanium-tungsten powder. Further, the filtrate reused many times is filtered and dried by adjusting the pH to precipitate calcium vanadate.

Further, the dust removal in step (1) is to remove the floating ash on the surface and the dust in the holes through air circulation, and set the airflow pressure to 0.2-2MPa; crushing is to mechanically crush the spent denitrification catalyst after dust removal to 5-10mm: Grinding the waste denitration catalyst sheet is ground to an average particle size of 50-120 μm to obtain waste denitration catalyst powder, so as to facilitate the reaction between reactants.

Further, the material in the screen of the flat-throwing stratification process described in step (1) falls freely by gravity, and the powder material is stratified by the action of the vertical airflow at a speed of 2-4m/s, and the first 60- 90% used. In the flat throwing layering process, the powder falling by the vertical airflow is under the action of the airflow at a certain speed, so that the powder with higher content of tungsten and titanium metal oxides and heavier quality remains in the front layer, and the lighter impurities such as alkali metals and silicon are removed. The air flow is brought to the back layer, so that the metals of different weights are stratified, and then the heavy powder with lower impurity content in the front layer is collected for subsequent treatment processes, further reducing the impurity components in the spent denitrification catalyst powder.

Further, the calcium compound described in step (1) is one or more of CaO, Ca(OH) ₂ , and CaCO ₃ .

Further, the ball mill described in step (1) is ground for 2-8 hours to 50-80 μm, the solid content of the slurry is 10-20%, and the temperature of the slurry is 60-80° C. Ball milling can not only further reduce the particle size of the powder, but also make the mixing of the powder more uniform and keep the mixed powder in an alkaline environment, which further promotes the reaction during the calcination process.

Further, the calcination temperature in step (2) is 450-780°C, and the calcination time is 1-3h. The slurry after being wet-milled by adding ultra-pure water maintains an alkaline environment, which promotes the further activation of the valuable metal oxides in the spent denitration catalyst. The direct calcination of the aqueous slurry promotes the preservation of the alkaline environment of the reactants during the heating process, and the heating promotes the further reaction between the calcium compound in the slurry and the spent denitration catalyst, effectively reducing the calcination temperature generated by the reaction. At the same time, the boiling action in the process of water evaporation promotes the formation of holes between the powder materials, which is conducive to the occurrence of the reaction between the compound and the spent denitration catalyst at high temperature.

The main reactions that may occur during the calcination process are as follows:

WO ₃ + CaO/Ca(OH) ₂ /CaCO ₃ = CaWO ₄ + H ₂ O/CO ₂ (1)

V ₂ O ₅ + CaO/Ca(OH) ₂ /CaCO ₃ = CaV ₂ O ₆ + H ₂ O/CO ₂ (2)

CaV ₂ O ₆ + CaO ＝ Ca ₂ V ₂ O ₇ (3)

Further, the acid described in step (2) is one or more of HCl, HNO ₃ , H ₂ SO ₄ , the concentration is 1-4mol/L, and the liquid-solid ratio is (2-5):1 .

Further, the pickling temperature in step (2) is 40-90°C, and the reaction time is 0.5-1.5h. Pickling makes the calcined calcium vanadate, calcium pyrovanadate, etc. produce vanadic acid dissolved in the solution, and the calcium tungstate is transformed into tungstic acid and titanium dioxide remains in the precipitate. Among them, the vanadium content of the waste denitration catalyst powder is relatively low, so the acid solution needs to be recycled and used many times to increase the concentration of vanadium. By adjusting the pH of the acid solution, calcium ions will react with vanadic acid to form calcium vanadate precipitates. After filtering and drying, calcium vanadate products with high purity can be obtained, which facilitates the recovery of vanadium.

Further, the drying temperature in step (2) is 110-180°C, and the drying time is 0.5-2h. The drying process not only removes the acid and moisture contained in the filter residue, but also converts the tungstic acid in the filter residue into tungsten trioxide by pyrolysis, so as to obtain regenerated titanium tungsten powder for recycling. After filtering and drying, the calcium vanadate product with higher purity can be obtained, which facilitates the recovery of vanadium.

Further, the average particle size of the pulverized powder in step (2) is 10-30 μm. Through secondary grinding, the titanium and tungsten powder product meets the standards for industrial production and realizes the recycling of spent denitration catalysts.

The technical innovation point of the present invention is:

(1) Compared with the prior art, the present invention adds a flat throwing stratification process and a mixed grinding process. In the flat throwing stratification process, the powder falling by the vertical airflow will reduce the content of tungsten and titanium metal oxides under the action of a certain speed airflow. The higher and heavier powder remains in the front layer, and the lighter impurities such as alkali metals and silicon are carried to the back layer by the airflow, so that the metals of different weights are stratified, and then the heavy powder with lower impurity content in the front layer is collected. Adding ultra-pure water to the powder for mixed grinding, not only reduces the impurity components in the spent denitrification catalyst powder, but also keeps the slurry after wet grinding in an alkaline environment, which promotes the removal of valuable metal oxides in the spent denitrification catalyst further activation. The direct calcination of the aqueous slurry promotes the preservation of the alkaline environment of the reactants during the heating process, and the heating promotes the further reaction between the calcium compound in the slurry and the spent denitration catalyst, effectively reducing the calcination temperature generated by the reaction. Combined with calcium compound as a sintering aid, the calcination temperature of the product is directly reduced from the general 1000°C to 450-780°C.

(2) Compared with CN112408470A, in addition to adding a flat throwing layering process, adding a mixing and grinding process before calcination, and matching calcium compounds as sintering aids, the present invention adds a pickling process after calcination, replacing alkali In the water grinding process, while reducing the discharge of alkaline water, pickling will cause the calcined calcium vanadate, calcium pyrovanadate, etc. to generate vanadic acid and dissolve in the solution, and the calcium tungstate will be converted into tungstic acid and titanium dioxide will remain in the precipitate. Not only the calcium vanadate product with higher purity is obtained, but also the purity of titanium tungsten powder is improved.

(3) CN101921916A adopts a secondary roasting process, the production process is complicated and the cost is high.

(4) CN106337133B has a high firing temperature.

(5) CN202011187934.2 discloses a treatment process for spent vanadium-titanium denitrification catalysts, which uses sodium roasting. In fact, ammonium metavanadate, ammonium molybdate, and ammonium tungstate are produced by water immersion after roasting. The recovery of vanadium through ammonium metavanadate does not involve the production of titanium tungsten powder.

The outstanding feature of the present invention is that TiO ₂ and WO ₃ components are retained and prepared as titanium tungsten powder carrier, which shortens the process steps and also reduces the consumption of alkali and the output of waste water in the reaction process, while the existing complete separation and recovery This method will lead to problems such as complex titanium dioxide recovery process, large alkali consumption, and large waste water output.

The beneficial technical effect of the present invention is:

(1) Titanium tungsten powder is prepared from waste denitration catalyst, which simplifies the recovery process of waste denitration catalyst, reduces the output of waste liquid, reduces costs and reduces the risk of environmental pollution.

(2) By controlling the ball milling, calcination temperature and calcination time, the reaction between V ₂ O ₅ and calcium compound can be increased while the reaction between calcium compound and TiO ₂ can be inhibited, so as to reduce energy and recover titanium tungsten powder in a relatively energy-saving manner.

(3) The vanadium component is separated by alkali neutralization and precipitation, which avoids the high energy consumption evaporation crystallization process, and the obtained products such as calcium vanadate have the same economic value as vanadium oxide.

Description of drawings

Fig. 1 is a flowchart of a method for recovering and preparing titanium-tungsten powder from a spent SCR denitration catalyst according to the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention, and those skilled in the art can fully understand the present invention without the description of these details. The present invention covers any alternatives, modifications, equivalent methods and schemes made on the spirit and scope of the present invention as defined by the claims.

Implementation Case 1

As shown in Figure 1, a method for preparing titanium and tungsten powder by recovering waste SCR denitration catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of filtrate to increase vanadium content Afterwards, pH is adjusted to precipitate vanadium and dry to obtain calcium vanadate product, and the filter residue is washed with water and dried to obtain titanium-tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 0.8MPa, mechanically crush the waste denitrification catalyst to 5-10mm after dust cleaning, and then grind to obtain waste denitrification with an average particle size of 80-150μm Catalyst powder. After the catalyst powder is layered by flat throwing at a vertical wind speed of 2m/s, the first 80% of the layered powder is collected to complete further impurity removal. After uniformly mixing the heavier powder collected from the front layer and 0.8 times the mass of CaO, the powder and ultrapure water are fed into the ball mill with a liquid-solid ratio of 10:1 and then ball milled. Set the ball milling temperature to 50°C and the ball milling time to 2h: The ball-milled slurry was calcined at a calcination temperature of 750° C., kept for 1.5 hours and then air-cooled.

Further, the calcined powder and 2mol/L HCl were added into the stirring reactor at a liquid-solid ratio of 5:1, and the reaction temperature was set at 60°C for 0.5h. Filtrate and filter residue were then obtained by filtration. Keep the acid concentration of the filtrate at 2mol/L and then reuse it again. After repeated reuse of the filtrate, adjust the pH to ≥ 7 through lye to precipitate calcium vanadate, filter, and dry to obtain calcium vanadate product. The acid-washed filter residue is then dried at 150°C for 1 hour to obtain titanium-tungsten powder, which is used after secondary grinding to a particle size of 10-30 μm.

Implementation Case 2

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium, dried to obtain calcium vanadate product, filter residue washed with water, dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Ash cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 0.6MPa, mechanically crush the spent denitrification catalyst to 5-8mm after dust removal, and then grind to obtain spent denitrification catalyst with an average particle size of 80-120μm Catalyst powder. Further, after the catalyst powder is layered by flat throwing at a vertical wind speed of 2.5m/s, the first 70% of the layered powder is collected to complete further impurity removal. After uniformly mixing the heavier powder collected from the front layer with 0.8 times the mass of CaCO ₃ , the powder and ultrapure water are fed into the ball mill with a liquid-solid ratio of 10:1 and then ball milled. Set the ball milling time to 2h: after ball milling The slurry was calcined at a calcination temperature of 700°C, kept for 2 hours and then air-cooled.

Further, the calcined powder and 2mol/L HCl were added into the stirred reactor at a liquid-solid ratio of 4:1, and the reaction temperature was set at 40°C for 1 h. Filtrate and filter residue were then obtained by filtration. Keep the acid concentration of the filtrate at 2mol/L and then reuse it again. After repeated reuse of the filtrate, adjust the pH to ≥ 7 through lye to precipitate calcium vanadate, filter, and dry to obtain calcium vanadate product. The acid-washed filter residue is dried at 120°C for 0.5 to obtain titanium-tungsten powder, which is used after secondary grinding to a particle size of 10-30 μm.

Implementation Case 3

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium and drying to obtain calcium vanadate product, and the filter residue is dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 0.5MPa, mechanically crush the waste denitrification catalyst to 7-10mm after dust removal, and then grind to obtain waste denitrification with an average particle size of 80-100μm Catalyst powder. Further, after the catalyst powder is layered by flat throwing at a vertical wind speed of 3m/s, the first 80% of the layered powder is collected to complete further impurity removal. After uniformly mixing the heavier powder collected from the front layer with 1.0 times the mass of Ca(OH) ₂ , the powder and ultrapure water are fed into the ball mill with a liquid-solid ratio of 8:1 and then ball milled. Set the ball milling time to 4h: The ball-milled slurry was calcined at a calcination temperature of 730° C., kept for 2 hours, and then air-cooled.

Further, the calcined powder and 3mol/L HNO ₃ were added into the stirred reactor at a liquid-solid ratio of 5:1, and the reaction temperature was set at 50°C for 1 hour. Filtrate and filter residue were then obtained by filtration. Keep the acid concentration of the filtrate at 3mol/L and then reuse it again. After multiple reuses, the filtrate is adjusted to pH ≥ 10 through ammonia water to precipitate calcium vanadate, filter, and dry to obtain calcium vanadate product. After the acid-washed filter residue is washed with water, it is dried at 120°C for 1 hour to obtain titanium-tungsten powder, which is used after secondary grinding until the average particle size of the powder is 15 μm.

Implementation Case 4

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium and drying to obtain calcium vanadate product, and the filter residue is dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Ash cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 1.5MPa, mechanically crush the spent denitrification catalyst to 7-10mm after dust removal, and then grind it to obtain waste denitrification with an average particle size of 80-100μm Catalyst powder. After the catalyst powder is layered by flat throwing at a vertical wind speed of 3m/s, the first 80% of the layered powder is collected to complete further impurity removal. After the heavier powder in the front layer is collected and mixed evenly with 1.0 times its mass of CaO, then the powder and deionized water are fed into the ball mill with a liquid-solid ratio of 6:1 and then ball milled. Set the ball milling time to 1.5h: after ball milling The slurry was calcined at a calcination temperature of 727°C, kept for 2.5 hours and then air-cooled.

Further, the calcined powder and 1.5mol/L HCl were added into the stirred reactor at a liquid-solid ratio of 5:1, and the reaction temperature was set at 85°C for 0.5h. Filtrate and filter residue were then obtained by filtration. Keep the acid concentration of the filtrate at 1.5 mol/L and reuse it again. After multiple reuses, the filtrate is adjusted to pH ≥ 7 through ammonia water to precipitate calcium vanadate, filter, and dry to obtain calcium vanadate product. The acid-washed filter residue is dried at 120°C for 2 hours, and the titanium-tungsten powder product is obtained after secondary grinding until the particle size of the powder is below 20 μm.

Implementation Case 5

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium and drying to obtain calcium vanadate product, and the filter residue is dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Ash cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 2MPa, mechanically crush the spent denitrification catalyst to 6-10mm after dust removal, and then grind to obtain a spent denitrification catalyst with an average particle size of 100-150μm Powder. After the catalyst powder is layered by flat throwing at a vertical wind speed of 3m/s, the first 85% of the layered powder is collected to complete further impurity removal. After uniformly mixing the heavier powder collected from the front layer with CaCO ₃ of 0.6 times its mass, the powder and deionized water are fed into the ball mill with a liquid-solid ratio of 10:1 and then ball milled. Set the ball milling time to 4h: After ball milling The slurry was calcined at a calcination temperature of 650° C., kept for 1.5 h and then air-cooled.

Further, the calcined powder and 1.5mol/L HCl were added into the stirred reactor at a liquid-solid ratio of 5:1, and the reaction temperature was set at 85°C for 0.5h. Filtrate and filter residue were then obtained by filtration. Keep the acid concentration of the filtrate at 1.5 mol/L and reuse it again. After repeated reuse of the filtrate, adjust the pH ≥ 7 through sodium hydroxide to precipitate calcium vanadate, filter, and dry to obtain the calcium vanadate product. The acid-washed filter residue is dried at 150°C for 2 hours, and the titanium-tungsten powder product is obtained after secondary grinding to a powder particle size of 10-20 μm.

Implementation Case 6

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium and drying to obtain calcium vanadate product, and the filter residue is dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Ash cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 0.8MPa, mechanically crush the spent denitrification catalyst to 6-10mm after dust removal, and then grind to obtain waste denitrification with an average particle size of 100-150μm Catalyst powder. After the catalyst powder is layered by flat throwing at a vertical wind speed of 2.5m/s, the first 80% of the layered powder is collected to complete further impurity removal. After uniformly mixing the heavier powder collected from the front layer and Ca(OH) ₂ of 0.8 times its mass, the powder and deionized water are fed into the ball mill with a liquid-solid ratio of 10:1 and ball milled. Set the ball milling time to 4h : The ball-milled slurry is calcined at a calcining temperature of 650° C., kept for 1 hour, and then air-cooled.

Further, the calcined powder and 2mol/L HCl were added into the stirred reactor at a liquid-solid ratio of 4:1, and the reaction temperature was set at 40°C for 1 h. Filtrate and filter residue were then obtained by filtration. Keep the acid concentration of the filtrate at 2mol/L and then reuse it again. After repeated reuse of the filtrate, adjust the pH to ≥ 7 through lye to precipitate calcium vanadate, filter, and dry to obtain calcium vanadate product. The acid-washed filter residue is dried at 160°C for 0.5h to obtain titanium-tungsten powder, which is used after secondary grinding to a particle size of 10-20μm.

Implementation Case 7

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium and drying to obtain calcium vanadate product, and the filter residue is dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Ash cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the pores through air circulation, set the airflow pressure to 0.7MPa, mechanically crush the spent denitrification catalyst to 5-8mm after dust removal, and then grind to obtain spent denitrification catalyst with an average particle size of 120-150μm Catalyst powder. After the catalyst powder is layered by flat throwing at a vertical wind speed of 2m/s, the first 65% of the layered powder is collected to complete further impurity removal. After uniformly mixing the heavy powder collected from the front layer and the mixed calcium compound (30% CaCO ₃ , 70% CaO) 0.8 times its mass, the powder and deionized water are jointly input into the ball mill at a liquid-solid ratio of 8:1 After ball milling, set the ball milling time to 4h: the slurry after ball milling is calcined at a calcination temperature of 630°C, kept for 2h and then cooled with the furnace.

Further, the calcined powder and 2mol/L HCl were added into the stirred reactor at a liquid-solid ratio of 4:1, and the reaction temperature was set at 40°C for 1 h. Filtrate and filter residue were then obtained by filtration. Keep the acid concentration of the filtrate at 2mol/L and reuse it again. After repeated reuse, the filtrate is adjusted to pH ≥ 7 by calcium oxide, so that the calcium vanadate is precipitated, filtered, and dried to obtain the calcium vanadate product. The pickled filter residue is dried at 130°C for 1 hour to obtain titanium-tungsten powder, which is used after secondary grinding to a particle size of 10-30 μm.

Implementation Case 8

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium and drying to obtain calcium vanadate product, and the filter residue is dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Ash cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 0.5MPa, mechanically crush the spent denitrification catalyst to 7-10mm after dust removal, and then grind to obtain spent denitrification catalyst with an average particle size of 80-130μm Catalyst powder. After the catalyst powder is layered by flat throwing at a vertical wind speed of 4m/s, the first 90% of the layered powder is collected to complete further impurity removal. After uniformly mixing the heavier powder collected from the front layer with 0.8 times its mass (50% CaCO ₃ , 50% CaO), the powder and deionized water are fed into the ball mill with a liquid-solid ratio of 6:1 and then ball milled. Set the ball milling time to 4 hours: the ball milled slurry is calcined at a calcination temperature of 730° C., kept for 1 hour and then cooled in the furnace.

Further, the calcined powder and 4mol/L HCl were added into the stirring reactor at a liquid-solid ratio of 2:1, and the reaction temperature was set at 80°C for 0.5h. Then filter to obtain the filtrate and filter residue, keep the acid concentration of the filtrate at 4mol/L and reuse it again, and adjust the pH to ≥ 7 through calcium oxide after repeated reuse of the filtrate, so that the calcium vanadate is precipitated, filtered, and dried to obtain the calcium vanadate product . The acid-washed filter residue is dried at 150°C for 0.5h to obtain titanium-tungsten powder, which is used after secondary grinding to a particle size of 10-30μm.

Implementation Case 9

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium and drying to obtain calcium vanadate product, and the filter residue is dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 1.5MPa, mechanically crush the waste denitrification catalyst to 7-10mm after dust cleaning, and then grind to obtain waste denitrification with an average particle size of 80-130μm Catalyst powder. After the catalyst powder is layered by flat throwing at a vertical wind speed of 2.5m/s, the first 75% of the layered powder is collected to complete further impurity removal. After uniformly mixing the heavier powder collected from the front layer and CaO 0.8 times its mass, the powder and deionized water are fed into the ball mill with a liquid-solid ratio of 6:1 and then ball milled. Set the ball milling time to 4h: After ball milling The slurry was calcined at a calcining temperature of 780° C., kept for 0.5 h and then cooled.

Further, the calcined powder and 3mol/L HCl were added into the stirring reactor at a liquid-solid ratio of 3:1, and the reaction temperature was set at 80°C for 0.5h. Then filter to obtain the filtrate and filter residue, keep the acid concentration of the filtrate at 3mol/L and reuse it again, and adjust the pH to ≥ 7 through potassium hydroxide after repeated reuse of the filtrate to precipitate calcium vanadate, filter, and dry to obtain calcium vanadate product. The acid-washed filter residue was dried at 180°C for 0.5h to obtain titanium-tungsten powder, which was used after secondary grinding until the average particle size of the powder was 10 μm.

Implementation Case 10

A method for recovering and preparing titanium-tungsten powder from a waste SCR denitrification catalyst, including pretreatment, flat layering, mixing, ball milling, calcination, pickling and filtration to obtain filter residue and filtrate, and further reuse of the filtrate for multiple times to increase the vanadium content and then adjust the PH precipitation Vanadium and drying to obtain calcium vanadate product, and the filter residue is dried to obtain titanium tungsten powder.

Pretreatment includes wherein said pretreatment includes dust removal, crushing and grinding. Cleaning is to remove the floating ash on the surface of the denitrification catalyst and the dust in the holes through air circulation, set the airflow pressure to 1.6MPa, mechanically crush the waste denitrification catalyst to 6-8mm after dust removal, and then grind to obtain waste denitrification with an average particle size of 100-150μm Catalyst powder. After the catalyst powder is layered by flat throwing at a vertical wind speed of 3m/s, the first 80% of the powder in the impurity layer is collected to complete further impurity removal. After uniformly mixing the heavier powder collected from the front layer and CaCO ₃ with 0.4 times the mass of 2, the powder and deionized water are fed into the ball mill with a liquid-solid ratio of 5:1 and then ball milled. Set the ball milling time to 4h: ball milling The final slurry was calcined at a calcination temperature of 660° C., kept for 2 hours and cooled.

Further, the calcined powder and 3mol/L HNO ₃ were added into the stirred reactor at a liquid-solid ratio of 5:1, and the reaction temperature was set at 90°C for 0.5h. Then filter to obtain the filtrate and filter residue, keep the acid concentration of the filtrate at 3mol/L and then reuse it again. After repeated reuse of the filtrate, adjust the pH to ≥ 7 through calcium hydroxide to precipitate calcium vanadate, filter, and dry to obtain calcium vanadate product. The acid-washed filter residue is washed with water and dried at 180°C for 0.5h to obtain titanium-tungsten powder, which is used after secondary grinding until the average particle size of the powder is 15μm.

Claims (7)

1. The method for preparing titanium tungsten powder by recycling the waste SCR denitration catalyst is characterized by comprising the following steps of:

(1) The method comprises the steps of carrying out pretreatment on a waste denitration catalyst by ash removal, crushing and grinding to obtain waste denitration catalyst powder, further carrying out impurity removal and purification by a horizontal polishing layering process to obtain powder with high tungsten content, uniformly mixing the powder with calcium compound in a ratio of 1:0.2-0.8, adding ultrapure water in a liquid-solid ratio of 5-10:1, and then inputting the mixture into a ball mill for grinding reaction to obtain slurry; the calcium compound is CaO, ca (OH) ₂ 、CaCO ₃ One or more of them;

(2) Calcining the slurry to obtain a mixture of the waste denitration catalyst and calcium compound after reaction, and filtering after acid washing to dissolve calcium vanadate in the mixture; recycling the acid filtrate for multiple times, washing and drying filter residues, and grinding to obtain titanium tungsten powder; further, the filtrate recycled for multiple times is filtered and dried after the calcium vanadate is precipitated by adjusting the pH value; the calcination temperature is 450-780 ℃ and the calcination time is 1-3h;

the acid is HCl or HNO ₃ 、H ₂ SO ₄ One or more of the following components with concentration of1-4mol/L, and the liquid-solid ratio is (2-5) to 1.

2. The method for preparing titanium tungsten powder by recycling the waste SCR denitration catalyst according to claim 1, wherein the ash removal in the step (1) is to remove surface floating ash and dust in holes through air circulation, and the air flow pressure is set to be 0.2-2MPa; crushing to mechanically crush the waste denitration catalyst to 5-10mm after ash removal: grinding the waste denitration catalyst tablets to an average particle size of 50-120 mu m to obtain waste denitration catalyst powder.

3. The method for preparing titanium tungsten powder by recycling the waste SCR denitration catalyst according to claim 1, wherein the materials in the horizontal polishing layering process screen mesh in the step (1) freely fall by gravity, layering is carried out on the powder by the action of vertical airflow with the speed of 2-4m/s, and the first 60-90% of the layered materials are collected for use.

4. The method for preparing titanium tungsten powder by recycling waste SCR denitration catalyst according to claim 1, wherein the ball mill in the step (1) grinds for 2-8 hours to 50-80 μm, the solid content of the slurry is 10-20%, and the slurry temperature is 60-80 ℃.

5. The method for preparing titanium tungsten powder by recycling the waste SCR denitration catalyst according to claim 1, wherein the pickling temperature in the step (2) is 40-90 ℃, and the reaction time is 0.5-1.5h.

6. The method for preparing titanium tungsten powder by recycling the waste SCR denitration catalyst according to claim 1, wherein the drying temperature in the step (2) is 110-180 ℃, and the drying time is 0.5-2h.

7. The method for preparing titanium tungsten powder by recycling waste SCR denitration catalyst according to claim 1, wherein the average particle size of the powder after grinding in the step (2) is 10-30 μm.

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