A method for resource utilization of waste denitrification filter cartridges

Abstract

This invention discloses a method for the resource utilization of waste denitrification filter cartridges, including pretreatment of the waste denitrification filter cartridges, leaching reaction, pressure filtration separation, leaching residue treatment, and preparation of a denitrification catalyst. In this invention, an organic-inorganic mixed acid solution is selected as the leaching liquid, which achieves good leaching effect while reducing environmental pollution. The leaching residue, mainly composed of glass fiber and TiO2, can be used as recycled material to prepare new catalysts. This invention is simple to operate, has low energy consumption, minimal environmental pollution, and is easy to scale up for industrial production. The prepared denitrification catalyst has a high specific surface area, high compressive strength, and good catalytic activity.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource recycling technology, specifically to a method for the resource utilization of waste denitrification filter cartridges. Background Technology

[0002] With the rapid development of national industry, NO X Emissions of NO are constantly rising, while NO X Coal-fired power plants are the main culprits behind acid rain, photochemical smog, and ozone layer depletion, posing a serious threat to atmospheric environmental governance and human health. Coal-fired power plants, as NOx-containing fuels... X The main production source widely uses Selective Catalytic Reduction (SCR) technology, which has advantages such as high denitrification efficiency, wide operating temperature range, and no pollution from reduced N2, to meet national emission standards. The corresponding V2O5-WO3 / TiO2 catalyst, as the core of the entire denitrification system, has always been favored by researchers and is constantly being developed and improved. However, long-term use of SCR denitrification catalysts in harsh environments inevitably leads to problems such as mechanical wear, fly ash blockage, high-temperature sintering, alkali (earth) metal poisoning, and vanadium loss and valence changes. Generally, regeneration or replacement with a new catalyst is required after 3-5 years of use. According to the "Guidelines for Review of Hazardous Waste Management Licenses for Waste Flue Gas Denitrification Catalysts" issued by the environmental protection department on August 19, 2014, regeneration should be the priority for collected waste flue gas denitrification catalysts (vanadium-titanium based). For waste flue gas denitrification catalysts that cannot be regenerated due to breakage or other reasons, the vanadium, tungsten, titanium, and other metal resources should be recovered as much as possible for reuse while avoiding environmental pollution. This invention takes into account the limited lifespan and regeneration cycles of SCR denitrification catalysts. Furthermore, many companies currently mix small amounts of waste material directly into the mixture of newly manufactured catalysts due to cost considerations, which is one of the main reasons for the significant reduction in the quality of SCR catalysts. Therefore, developing suitable resource utilization technologies for waste catalysts with different compositions is a problem that needs to be continuously solved.

[0003] This invention references the resource utilization method of waste SCR catalysts and, based on previous research, prepares new catalysts using recycled glass fiber under different conditions, realizing the comprehensive utilization of leachate and leachate residue, and exploring a resource utilization method for waste denitrification filter cartridges. Summary of the Invention

[0004] In view of the limited research on the resource recycling of waste denitrification filter cartridges, this invention provides a method for the resource utilization of waste denitrification filter cartridges.

[0005] To obtain specific recycling conditions, the present invention includes the following experimental steps:

[0006] (1) Pretreatment of waste denitrification filter cartridges: The waste denitrification filter cartridges are blown, washed, dried and crushed to obtain waste denitrification filter cartridge powder, and XRF analysis is performed on the waste denitrification filter cartridge powder;

[0007] (2) Leaching reaction: The waste denitrification filter powder from step (1) is added to an organic-inorganic mixed acid solution for leaching reaction to obtain a mixed slurry;

[0008] (3) Pressure filtration separation: The mixed slurry in step (2) is separated by plate and frame filter press to obtain vanadium-containing supernatant and leaching residue. The vanadium-containing supernatant is evaporated and concentrated for later use.

[0009] (4) Leaching residue treatment: Add water to the leaching residue in step (3) and perform plate and frame filter press until the leaching residue is rinsed and filtered to neutral. Dry the rinsed leaching residue and perform XRF analysis to obtain the dried leaching residue. Recycle the generated rinsing water back to step (2) as a supplement to the water required for preparing the mixed acid solution.

[0010] (5) Preparation of denitration catalyst: The leaching residue dried in step (4) is used as recycled material. According to the XRF analysis results, titanium dioxide and other small materials are added in proportion and mixed. After the mixing is completed, mud is obtained. It is aged, extruded, dried and calcined. After impregnation in the vanadium-containing supernatant obtained in step (3), dried and sintered, the denitration catalyst loaded with active material V2O5 can be obtained.

[0011] Further, step (1) specifically involves: high-pressure air blowing treatment should not damage the overall structure of the denitrification filter cartridge, the waste denitrification filter cartridge after water washing and drying should not have any slag falling off, and the powder obtained from the crushing should be mixed as evenly as possible before XRF analysis, and the sample should be analyzed 3 times to ensure that the average error is within 1%.

[0012] Furthermore, in step (2), the organic-inorganic mixed acid solution is composed of organic acid and inorganic acid, the organic acid being 0.9 mol / L oxalic acid solution and the inorganic acid being 0.05% dilute sulfuric acid.

[0013] Furthermore, the leaching reaction conditions in step (2) are as follows: the reaction temperature is 80℃, the solid-liquid ratio of the waste denitrification filter cartridge powder and the organic-inorganic mixed acid solution is 1:25 g / mL, and the mechanical stirring speed is 300 r·min. -1 The reaction time was 150 min.

[0014] Further, in step (3), the vanadium-containing supernatant is evaporated and concentrated to 3-5 wt%.

[0015] Further, in step (4), drying specifically involves drying in an oven at 80°C for 8-10 hours until the moisture content of the leaching residue is ≤5wt%.

[0016] Furthermore, according to the XRF analysis results in step (4), the main components of the leaching residue are glass fiber and TiO2. Among them, glass fiber is the target product. TiO2 is still needed as a support when preparing new SCR denitration catalyst. Therefore, the leaching residue after drying is mainly purified glass fiber as recycled material. Considering that the glass fiber in the recycled material has become short glass fiber, which may reduce the mechanical strength of the newly prepared catalyst, long glass fiber needs to be added during the mixing process.

[0017] Further, the amount of leaching residue added after drying in step (5) is 3-6 wt%, the amount of titanium dioxide added is 83.5-90.8 wt%, and the other minor materials are long glass fiber, ammonium metatungstate, carboxymethyl cellulose, polyoxyethylene and stearic acid; among which the amount of long glass fiber added is 2.5 wt%, the amount of ammonium metatungstate added is 3-5 wt%, the amount of carboxymethyl cellulose added is 0.1-0.5 wt%, the amount of polyoxyethylene added is 0.5-2 wt%, and the amount of stearic acid added is 0.1-0.5 wt%.

[0018] Furthermore, monoethanolamine, lactic acid and kapok are added during the mixing process in step (5). Based on the amount of titanium dioxide used, 20 mL of monoethanolamine, 20 mL of lactic acid and 10 g of kapok need to be added for every 2 kg of titanium dioxide.

[0019] Furthermore, in step (5), the mixing temperature is room temperature (when the mud has a high water content, the oil bath heating is turned on). During mixing, 20% ammonia water is also added to adjust the physical properties of the mud so that the plasticity of the mud reaches 2-3N and the water content is 26-30%.

[0020] Furthermore, in step (5), the aging temperature is 50-90℃ and the aging time is 0.5-5h;

[0021] The extrusion process involves extruding the material according to the required number of holes and length, with an extrusion pressure of 1.5-2.0 MPa and an extrusion speed of 0.8-1.2 m / min.

[0022] Specifically, the extruded unit strips are placed in a drying cart with paper spacers and then dried in a drying room. The temperature in the drying room is 45-55℃, the ambient humidity is >95%, and the drying time is 10-15 days.

[0023] After drying, the unit strips are placed in a mesh belt kiln for calcination at a temperature of 500-600℃ for 12-24 hours.

[0024] Furthermore, the immersion time in the vanadium-containing supernatant in step (5) is 1-12 hours;

[0025] The drying temperature is 80-120℃, and the drying time is 1-12 hours;

[0026] The sintering temperature is 250-600℃, and the sintering time is 0.5-5h.

[0027] The beneficial effects of this invention are:

[0028] (1) This invention is based on decades of research experience in the resource recovery of waste SCR catalysts. It uses an organic-inorganic mixed acid solution as the leaching liquid and takes advantage of the strong acidity of inorganic acid and the excellent reduction and complexing effects of organic acid to effectively recover V2O5 from waste denitrification filter cartridges. The vanadium-containing supernatant can be concentrated and crystallized and then used for the regeneration of SCR catalysts. The main components of the leaching residue are glass fiber and TiO2, which can be used for the preparation of new catalysts. This invention fills the gap in the field of resource recovery of waste denitrification filter cartridges.

[0029] (2) The process of this invention is short and the recycling method is simple. The catalyst made from leaching residue with glass fiber as the main component has little difference in physicochemical properties compared with the new catalyst. Moreover, the water used to wash the leaching residue can be reused as water required for the acid preparation stage, which greatly reduces the amount of wastewater. In addition, this invention is easy to implement and scale up to industrial production. Attached Figure Description

[0030] The accompanying drawings are provided to further explain the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0031] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0032] To illustrate the technical solutions and advantages of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to several examples. It should be noted that the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] The first step is the pretreatment of waste denitrification filter cartridges: the waste denitrification filter cartridges are blown dry, washed with water, dried, and crushed for later use, and the powder is subjected to X-ray fluorescence spectroscopy (XRF) analysis. The results of the XRF analysis are shown in Table 1;

[0035] Table 1 Main Components of Waste Denitrification Filter Cartridges

[0036]

[0037] The second step, leaching reaction: An organic-inorganic mixed acid solution was used as the leaching solution. The organic acid in the mixed acid solution was a 0.9 mol / L oxalic acid solution, and the inorganic acid was a 0.05% (w / w) dilute sulfuric acid solution. The reaction temperature was 80℃, the solid-liquid ratio was 1:25 g / mL, and the mechanical stirring speed was fixed at 300 r·min. -1 After reaching the reaction temperature, continue the reaction for 150 minutes to obtain a fully reacted mixed slurry;

[0038] The third step is filter press separation: the mixed slurry obtained in step (2) is separated by a plate and frame filter press to obtain vanadium-containing supernatant and leaching residue. The vanadium-containing supernatant is evaporated and concentrated to 3-5 wt% for later use.

[0039] Step 4, leaching residue treatment: Add water to the leaching residue obtained in step (3) and perform plate and frame filtration until the leaching residue is washed and filtered to neutrality; then dry the obtained leaching residue and perform X-ray fluorescence spectroscopy (XRF) analysis on it. The results are shown in Table 2. According to the XRF analysis results, the main components of the leaching residue are glass fiber and TiO2. Among them, glass fiber is the target product. TiO2 is still needed as a support when preparing new SCR denitration catalyst. In addition, the generated rinsing water is recycled back to step (2) as a supplement to the water required for preparing mixed acid solution.

[0040] Table 2. Main components of the leaching residue obtained from the waste denitrification filter cartridges in the examples.

[0041]

[0042] Step 5, Preparation of the denitrification catalyst: During the mixing process, the leaching residue obtained is used as recycled material at a ratio of 3 wt%, and sodium metatungstate is added at a rate of 5 wt%. The following components are added by mass fraction: 2.5 wt% long glass fiber; 0.5 wt% carboxymethyl cellulose; 1.5 wt% polyoxyethylene; 0.5 wt% stearic acid; the remainder is supplemented with virgin titanium dioxide. Monoethanolamine, lactic acid, and kapok are added according to the amount of titanium dioxide added (for every 2 kg of titanium dioxide, 20 mL of monoethanolamine, 20 mL of lactic acid, and 10 g of kapok are required). During the mixing process, 20% ammonia water is added to adjust the physical properties of the mud, and heating is used to assist in the adjustment, so that the plasticity of the mud reaches 2-3 N, and the moisture content is within the range of 26-30%. After mixing, a mud material is obtained. The mud material is aged at 60℃ for 4 hours. It is then extruded according to the required number of holes and length, with an extrusion pressure of 0.8MPa and an extrusion speed of 1.0m / min. The extruded unit strips are placed in a drying trolley with paper spacers and dried in a drying room at 50℃ and >95% humidity for 15 days. The dried unit strips are then calcined in a mesh belt kiln at 550℃ for 20 hours to obtain the initial denitrification catalyst. The initial denitrification catalyst is then impregnated in the vanadium-containing supernatant concentrated in step (3) for 10 hours, dried at 100℃ for 8 hours, and sintered at 400℃ for 3 hours to obtain the denitrification catalyst loaded with active material V2O5.

[0043] Example 2

[0044] The difference from Example 1 is that in the fifth step, the leaching residue obtained during the mixing process is used as recycled material at a ratio of 4 wt%, sodium metatungstate is added at a ratio of 3 wt%, and the mass fractions of the added small materials are 2.5 wt% long glass fiber; 0.3 wt% carboxymethyl cellulose; 2 wt% polyoxyethylene; 0.3 wt% stearic acid; and the remainder is supplemented with new titanium dioxide. The remaining steps are the same as in Example 1.

[0045] Example 3

[0046] The difference from Example 1 is that in the fifth step, the leaching residue obtained during the mixing process is used as recycled material at a ratio of 5 wt%, the amount of sodium metatungstate added is 5 wt%, and the mass fractions of the added small materials are 2.5 wt% long glass fiber; 0.1 wt% carboxymethyl cellulose; 1 wt% polyoxyethylene; 0.1 wt% stearic acid; and the remainder is supplemented with new titanium dioxide. The remaining steps are the same as in Example 1.

[0047] Example 4

[0048] The difference from Example 1 is that in the fifth step, the leaching residue obtained during the mixing process is used as recycled material at a ratio of 6 wt%, the amount of sodium metatungstate added is 5 wt%, and the mass fractions of the added small materials are 2.5 wt% long glass fiber; 0.1 wt% carboxymethyl cellulose; 0.5 wt% polyoxyethylene; 0.1 wt% stearic acid; and the remainder is supplemented with new titanium dioxide. The remaining steps are the same as in Example 1.

[0049] Comparative Example 1

[0050] The difference from Example 1 is that in the fifth step, the leaching residue obtained during the mixing process is used as recycled material at a ratio of 6 wt%, sodium metatungstate is added at a ratio of 5 wt%, and the mass fractions of the added small materials are 0.1 wt% carboxymethyl cellulose, 0.5 wt% polyoxyethylene, and 0.1 wt% stearic acid, respectively; long glass fibers are no longer added, and the remaining part is supplemented with new titanium dioxide. The other steps are the same as in Example 1.

[0051] Comparative Example 2

[0052] The denitrification catalyst is prepared using virgin materials instead of leaching residue as recycled material.

[0053] Preparation of the novel denitrification catalyst: During the mixing process, 0.8 wt% ammonium metavanadate and 5 wt% sodium metatungstate were added. The following minor components were added by mass fraction: 4.5 wt% long glass fiber; 0.5 wt% carboxymethyl cellulose; 1.5 wt% polyoxyethylene; 0.5 wt% stearic acid; the remainder being supplemented with novel titanium dioxide. Monoethanolamine, lactic acid, and kapok were added according to the amount of titanium dioxide added (20 mL monoethanolamine, 20 mL lactic acid, and 10 g kapok were added for every 2 kg of titanium dioxide). During the mixing process, 20% ammonia water was added to adjust the physical properties of the mud, and heating was used to assist in the adjustment, so that the plasticity of the mud reached 2-3 N and the moisture content was within the range of 26-30%. After mixing, a mud material is obtained. The mud material is aged at 60℃ for 4 hours. It is then extruded according to the required number of holes and length, with an extrusion pressure of 0.8MPa and an extrusion speed of 1.0m / min. The extruded unit strips are placed in a drying trolley with paper spacers and dried in a drying room at 50℃ and >95% humidity for 15 days. The dried unit strips are then calcined in a mesh belt kiln at 550℃ for 20 hours to obtain the initial denitrification catalyst. The initial denitrification catalyst is then impregnated in the vanadium-containing supernatant concentrated in step (3) for 10 hours, dried at 100℃ for 8 hours, and sintered at 400℃ for 3 hours to obtain the denitrification catalyst loaded with active material V2O5.

[0054] Experimental Example 1

[0055] The pore structure parameters of the samples were determined using a TriStar II low-temperature nitrogen adsorption-desorption analyzer from Micromeritics. The compressive strength was tested using a computer-controlled electronic pressure testing machine (YAW-300D) manufactured by Jinan Xinshijin Testing Machine Co., Ltd. The wear strength of the samples was determined using a wear resistance tester from Taber. The catalytic activity of the samples was detected using a flue gas analyzer (VARIO plus) from MRU, Germany.

[0056] The main components, specific surface area and pore structure analysis results, mechanical property test results and catalytic activity test results of the denitrification catalysts prepared in Examples 1-4 and Comparative Examples 1-2 are recorded in Tables 3, 4, 5-1, 5-2 and 6, respectively.

[0057] Table 3. Main components of the denitrification catalysts prepared in Examples 1-4 and Comparative Examples 1-2

[0058]

[0059] *All data in the table are quality percentages.

[0060] Table 4. Specific surface area and pore structure analysis results of the denitrification catalysts prepared in Examples 1-4 and Comparative Examples 1-2.

[0061]

[0062] Table 5-1 Compressive strength of the denitrification catalysts prepared in Examples 1-4 and Comparative Examples 1-2

[0063]

[0064] Table 5-2 Wear intensity of the denitrification catalysts prepared in Examples 1-4 and Comparative Examples 1-2

[0065]

[0066] Table 6. Catalytic activity test results of the denitrification catalysts prepared in Examples 1-4 and Comparative Examples 1-2

[0067]

[0068] The characterization results of Examples 1-4 and Comparative Examples 1-2 show that the present invention discloses a method for the resource utilization of waste denitrification filter cartridges. The catalyst prepared by using leaching residue with glass fiber as the main component as recycled material has very little difference in specific surface area, pore structure, mechanical strength and catalytic activity compared with the new catalyst. It can be scaled up proportionally for use in the catalyst production process. However, it is necessary to add a certain amount of long glass fiber to increase the mechanical strength of the catalyst.

[0069] Figure 1This is a schematic diagram of the process flow of the present invention.

[0070] The examples and comparative cases described above represent preferred embodiments of the present invention. The specific descriptions are intended to illustrate the experimental results of the present invention and to enable those skilled in the art to understand its content. However, it should be noted that any obvious combinations or equivalent substitutions of conditions based on the technical conditions of the present invention, without departing from the scope defined by the present invention, should be covered within the protection scope of the present invention.

Claims

1. A method for the resource utilization of waste denitrification filter cartridges, characterized in that, Includes the following steps: (1) Pretreatment of waste denitrification filter cartridges: The waste denitrification filter cartridges are blown, washed, dried and crushed to obtain waste denitrification filter cartridge powder, and XRF analysis is performed on the waste denitrification filter cartridge powder; (2) Leaching reaction: The waste denitrification filter powder from step (1) is added to an organic-inorganic mixed acid solution for leaching reaction to obtain a mixed slurry; (3) Filtration separation: The mixed slurry in step (2) is separated by plate and frame filtration to obtain vanadium-containing supernatant and leaching residue. The vanadium-containing supernatant is evaporated and concentrated for later use. (4) Leaching residue treatment: Add water to the leaching residue in step (3) and perform plate and frame filter press until the leaching residue is rinsed and filtered to neutral. Dry the rinsed leaching residue and perform XRF analysis to obtain the dried leaching residue. Recycle the generated rinsing water back to step (2) as a supplement to the water required for preparing the mixed acid solution. (5) Preparation of denitration catalyst: The leaching residue dried in step (4) is used as recycled material. According to the XRF analysis results, titanium dioxide and other small materials are added in proportion and mixed. After mixing, mud is obtained. It is aged, extruded, dried and calcined. It is then impregnated in the concentrated vanadium-containing supernatant obtained in step (3), dried and sintered to obtain the denitration catalyst loaded with active material V2O5. After drying in step (5), the amount of leaching residue added is 3-6 wt%, the amount of titanium dioxide added is 83.5-90.8 wt%, and the other small materials are long glass fiber, ammonium metatungstate, carboxymethyl cellulose, polyoxyethylene and stearic acid; among which, the amount of long glass fiber added is 2.5 wt%, the amount of ammonium metatungstate added is 3-5 wt%, the amount of carboxymethyl cellulose added is 0.1-0.5 wt%, the amount of polyoxyethylene added is 0.5-2 wt%, and the amount of stearic acid added is 0.1-0.5 wt%.

2. The method according to claim 1, characterized in that, In step (2), the organic-inorganic mixed acid solution is composed of organic acid and inorganic acid. The organic acid is 0.9 mol / L oxalic acid solution, and the inorganic acid is 0.05% dilute sulfuric acid.

3. The method according to claim 1, characterized in that, The leaching reaction conditions in step (2) are as follows: the reaction temperature is 80℃, the solid-liquid ratio of the waste denitrification filter cartridge powder and the organic-inorganic mixed acid solution is 1:25 g / mL, and the mechanical stirring speed is 300 r·min. -1 The reaction time was 150 min.

4. The method according to claim 1, characterized in that, In step (3), the vanadium-containing supernatant is evaporated and concentrated to 3-5 wt%.

5. The method according to claim 1, characterized in that, In step (4), drying specifically involves drying in an 80℃ oven for 8-10 hours until the moisture content of the leaching residue is ≤5wt%.

6. The method according to claim 1, characterized in that, Before mixing in step (5), monoethanolamine, lactic acid and kapok are added. Based on the amount of titanium dioxide used, for every 2 kg of titanium dioxide, 20 mL of monoethanolamine, 20 mL of lactic acid and 10 g of kapok need to be added.

7. The method according to claim 1, characterized in that, In step (5), the mixing temperature is room temperature. During mixing, 20% ammonia water needs to be added to adjust the physical properties of the mud so that the plasticity of the mud reaches 2-3N and the water content is 26-30%.

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