Method and system for synergistically treating spent denitration catalysts in a sintering process

Abstract

The present application relates to a kind of sintering process synergistically treating waste denitration catalyst method and system, including preparation sintering mixture, calculate the proportion coefficient of vanadium, titanium element in sintering raw material into sinter, proportion coefficient η Value is used to judge whether the waste denitration catalyst in raw material is added excess, system includes flue gas pipeline, filter band, main fan, filter band and flue gas pipeline transverse section are perpendicular to each other, sintering flue gas is filtered in flue gas pipeline through filter band, main fan is used to produce negative pressure by air draft, so that sintering flue gas does not overflow in the process of removing chromium.The present application has the advantages that: waste denitration catalyst is disposed by sintering process, and the absorption of toxic and harmful substances in flue gas is realized by the system of removing vanadium and titanium, the influence of toxic substances in hazardous waste on sintering flue gas is not considered in existing treatment process, which further leads to the diffusion of pollutants, causing the problem of secondary pollution of environment.

Description

Technical Field

[0001] This invention relates to the field of comprehensive utilization of waste, and in particular to a method and system for co-processing waste denitrification catalysts in a sintering process. Background Technology

[0002] Studies have found that when the vanadium and titanium content in the sintering raw materials is low, the vanadium and titanium are mainly solidified in the sintered ore after sintering, and the amount of vanadium and titanium emitted into the atmosphere with the flue gas is extremely low. However, when the vanadium and titanium content in the sintering raw materials exceeds a certain critical value, the proportion of vanadium and titanium entering the sintering flue gas increases sharply after sintering. Furthermore, this critical value for vanadium and titanium content is not fixed under different sintering raw materials and process parameters, increasing the difficulty of treatment. Currently, there are no relevant studies or reports on how to control the amount of waste denitrification catalyst added in the sintering process to reduce environmental impact.

[0003] On the other hand, studies on the existence forms of vanadium and titanium in sintering flue gas have revealed that they exist primarily as solid particulate matter, with vanadium and titanium mainly concentrated in fine-grained dust particles, exhibiting very low concentrations in larger-sized dust particles. Research on sintering flue gas dust collectors also shows that the smaller the dust particle size, the higher the percentage of vanadium and titanium content. Domestic and international steel enterprises commonly use electrostatic precipitators to treat sintering flue gas, easily capturing larger dust particles while leaving the smaller, vanadium- and titanium-rich particles unremoved, ultimately releasing them into the atmosphere and harming the environment. Currently, there is no readily available, economically sound method for removing vanadium and titanium from sintering flue gas.

[0004] Wu Yanmei's article, "Practice of Harmless Sintering Production Treatment of Chromium Slag," introduces Sichuan Dagang's production practice in treating chromium-containing waste slag during sintering. Wang Hongjun et al.'s article, "Application Practice of Chromium Slag in Jiuquan Iron & Steel's Sintering Production," introduces Jiuquan Iron & Steel's method of treating chromium slag as a sintering auxiliary material in its sintering system. Both articles concern the application of chromium-containing solid waste in the sintering system; however, their technical research only considers the impact of chromium on sintering production yield and quality, neglecting the existence form and final destination of chromium during the sintering treatment of chromium-containing waste, thus ignoring the environmental impact of chromium-containing waste. As hazardous waste, it requires centralized harmless treatment. Simply treating it as a sintering auxiliary material without considering environmental factors may not only fail to achieve harmless treatment of toxic waste but may also cause the spread of hazardous waste through sintering flue gas emissions.

[0005] Application number CN201921036591.2, patent titled "Tail Gas Treatment Equipment in the Disposal of Chromium-Containing Heavy Metal Hazardous Waste," includes a dust purification device, an acidic gas purification tank, and a sludge settling tank. The dust purification device mixes steam generated during water quenching with flue gas, utilizing the condensation effect of the steam to settle the dust in the flue gas. The dust-removed flue gas is then sent into the acidic gas purification tank, where the liquid level is below a certain threshold, allowing the acidic gases in the flue gas to fully react with the solution, thereby purifying the acidic gases. However, this equipment requires a large amount of steam for condensation, consuming significant resources and energy, resulting in high operating costs. Furthermore, the effectiveness of steam condensation in purifying chromium-containing dust particles is limited, with a low chromium dust removal rate.

[0006] Application number CN201811373734.9, patent titled "Purification System for Flue Gas Generated from Harmless Disposal of Chromium-Containing Sludge by a Double-Cylinder Rotary Kiln," includes an inclined double-cylinder rotary kiln. It effectively solves the problems of dust, acidic gases, and nitrogen oxides in the waste gas treatment process of chromium-containing sludge, ensuring emissions meet the requirements of the "Standard for Pollution Control of Hazardous Waste Incineration" (GB18484-2001). The device sequentially passes the flue gas through a settling chamber, a cyclone dust collector, then through a first water film dust removal and desulfurization spray tower for washing, followed by a second and third water film dust removal and desulfurization spray tower. The entire system has a complex structure, with high equipment and operating costs due to the settling, cyclone dust removal, and three-stage spraying processes. Furthermore, the selection of reagents does not specifically target the collection of chromium-containing dust, and fine chromium-containing dust cannot be completely captured.

[0007] Application number CN200810058792.2, patent titled "Method for Determining Heavy Metal Elements in Cigarette Smoke Using a Smoke Collection and Absorption Device," describes a smoke collection and absorption device comprising an outer sleeve (1), an inner sleeve (2), and a sealing plug (3). The outer sleeve (1) has an inlet (7) and an outlet (8). The outer sleeve (1), inner sleeve (2), and sealing plug (3) are sequentially sealed together. The inner sleeve (2) contains an upper sieve plate (6) and a lower sieve plate (4), with buffer filler (5) filling the space between the two sieve plates. This method, through the combined action of the upper and lower sieve plates and the buffer filler, slightly prolongs the residence time and absorption time of the smoke in the collector. Furthermore, the dispersion of the smoke by the sieve plates and the buffering effect of the buffer filler increase the reaction surface area for smoke absorption, resulting in more complete absorption of the smoke components. However, the buffer packing only serves a buffering function, and its relatively large gaps are insufficient to filter fine dust particles in the gas. The absorption of dust particles relies solely on the short-term contact reaction between the collector and the flue gas, resulting in a low dust collection rate. Furthermore, this device can only absorb gases with small flow rates and low flue gas velocities. When large flow rates and high velocities of sintering flue gas are introduced into the device, the resulting impact force can disperse the buffer packing and even cause the collector to splash. Moreover, the contact reaction time between the faster-flowing flue gas and the collector is even shorter, resulting in insufficient absorption.

[0008] Application number CN201921879172.5, patent title "An Asphalt Fume Absorption Device," describes an asphalt fume absorption device comprising a cylinder, a resistive layer, an ozone layer, an ultraviolet lamp, a spray covering layer, a fan, and an exhaust port. The device is characterized by a multi-layered filter plate at the bottom of the cylinder. The first layer of the filter plate is made of asbestos mesh, the second layer is made of activated carbon with honeycomb pores, and the third layer is a screen plate covered with quicklime. There is a height of 300mm-500mm between adjacent absorption layers. From top to bottom, the cylinder's central cross-section consists of the resistive layer, the spray covering layer, and the exhaust fan inlet. The spray covering layer contains an organic solvent capable of absorbing asphalt particles. This device uses an organic solvent to absorb particulate matter in asphalt fumes, and through the combined action of the resistive layer, ozone layer, and ultraviolet lamp, the asphalt fumes react further with oxygen at high temperatures, achieving excellent absorption results. However, the use of this device has certain limitations and drawbacks: First, the device has a complex structure and high cost. The activated carbon honeycomb pore material needs to be replaced regularly because it will fail after use. The ozone layer and the resistance layer also consume high resources and energy, which significantly increases the operating cost of the equipment. Second, among the several layers of filtration structure of this device, the asbestos mesh has limited filtering and interception effect on fine dust in the flue gas. The screen plate covered with quicklime only has an absorption effect on some acidic gases in the flue gas, and the absorption is not complete. The sprayed organic solvent is sprayed through tiny water droplets, and the collision between the spray liquid and the small asphalt particles in the flue gas is random, so the spray absorption effect is poor. The combined effect of the resistance layer, ozone layer and ultraviolet lamp is only effective against organic particles in asphalt flue gas, and its effect is also very limited.

[0009] Application number CN202021710826.4, patent title "A Petrochemical Flue Gas Absorption Device", includes an absorption tower, a gas washing section, a chemical absorption section, and a water vapor recovery section. The gas washing section is located at the bottom of the absorption tower, the chemical absorption section is located in the middle of the absorption tower, and the water vapor recovery section is located at the top of the absorption tower. The water vapor recovery section includes a water vapor baffle plate, which includes a water vapor baffle channel and a water vapor recovery channel. A cold air channel is provided at the top of the water vapor baffle channel, and a water outlet channel is provided at the bottom of the water vapor recovery channel. A heat-conducting plate is provided on the cold air channel, and a water collection plate is provided on the water outlet channel. A water outlet is provided at the bottom of the water outlet channel. After the flue gas is introduced into the bottom of the absorption tower, it undergoes gas washing and cooling at the bottom of the absorption tower, then chemical absorption of acidic gases, and finally water vapor recovery. This device effectively solves the problem of catalysts and water in flue gas after conventional absorption tower treatment, but it still has certain limitations and drawbacks: when the flue gas passes through the gas washing section of the device, it usually rises rapidly in the form of bubbles. The reaction time between the flue gas and the absorption liquid is limited and the contact area is small, resulting in insufficient absorption of dust particles in the flue gas. The chemical absorption and water vapor absorption sections also cannot achieve the purpose of absorbing dust particles in the flue gas.

[0010] Application number CN201410223759.6, patent titled "A Method for Detecting Chromium, Nickel, Arsenic, Selenium, Cadmium, and Lead Elements in Cigarette Sidestream Smoke," is characterized by: using a fishtail hood connected in series with quartz fiber filters to collect particulate matter from cigarette sidestream smoke; using a three-stage series of nitric acid solutions to collect gaseous matter from the sidestream smoke; digesting the sample using microwave digestion; and detecting the content of chromium, nickel, arsenic, selenium, cadmium, and lead in the particulate and gaseous samples using inductively coupled plasma mass spectrometry. This method absorbs toxic substances in the smoke separately before detection. However, this method requires separate processing of particulate and gaseous matter, involving a series of processes such as washing, extraction, digestion, ultrasonic vibration, and heating concentration, making the operation complex, time-consuming, and costly. More importantly, the method of collecting particulate matter using quartz fiber filters cannot completely absorb particulate matter in the smoke, and some extremely small particles cannot be captured.

[0011] Currently, among the existing methods for the harmless disposal of waste denitrification catalysts in China, there is no economical and reasonable method that can completely and permanently harmlessly dispose of vanadium-titanium-containing hazardous waste without causing secondary environmental pollution. Summary of the Invention

[0012] The purpose of this invention is to provide a method and system for co-processing waste denitrification catalysts in sintering processes. This solves the problem that existing treatment processes do not consider the impact of toxic substances in hazardous waste on sintering flue gas, which leads to the spread of pollutants and secondary environmental pollution. This invention provides a more economical and reasonable approach to the harmless treatment of waste denitrification catalysts, offering a new route for the harmless treatment of waste denitrification catalysts.

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] A method for co-processing waste denitrification catalysts in a sintering process, specifically including:

[0015] S1. Prepare the sintering mixture;

[0016] S2. Before sintering, weigh the mass of the sintering mixture, and then distribute, ignite, and sinter the sintering mixture. After sintering, weigh the mass of all sintered ore products between the starting and ending positions of the sintering machine trolley. During this process, perform multi-point sampling and vanadium and titanium content testing on the sintering mixture and sintered ore products.

[0017] S3. Calculate the proportion coefficients of vanadium and titanium elements in the sintering raw materials entering the sinter. The calculation formula is as follows:

[0018]

[0019] In formula ①, M1 represents the mass of the sintering mixture weighed before feeding, M2 represents the mass of all sintered ore products weighed and recorded between the starting and ending positions of the sintering machine trolley after sintering, Y1% represents the vanadium content of the sintered ore, Y2% represents the titanium content of the sintered ore, X1% represents the vanadium content of the mixture (wet basis), X2% represents the titanium content of the mixture (wet basis), and η represents the proportionality coefficient.

[0020] S4. The proportionality coefficient η is used to determine whether the waste denitrification catalyst in the raw material is added in excess: when the proportionality coefficient η is ≥ 0.975, it is determined that the waste denitrification catalyst is not added in excess, and the proportion of waste denitrification catalyst added should be increased; when the proportionality coefficient η is < 0.975, it is determined that the waste denitrification catalyst is added in excess, and the proportion of waste denitrification catalyst added in the sintering raw material should be reduced.

[0021] In S1, the sintering mixture is prepared as follows:

[0022] The waste denitrification catalyst is crushed and ground, and the processed material has a particle size of less than 1 mm accounting for more than 95%;

[0023] The crushed and ground waste denitrification catalyst is mixed with various sintering fluxes to obtain flux mixture, in which the waste denitrification catalyst accounts for 0.5% to 5.5% of the total flux mixture;

[0024] The flux mixture is mixed with fuel and premixed again, and after one mixing and two homogenization and granulation, a sintering mixture is finally obtained.

[0025] Various sintering fluxes include quicklime, limestone, magnesia, and dolomite.

[0026] A sintering process co-processing system for waste denitrification catalyst includes a vanadium-titanium removal device. The vanadium-titanium removal device includes a flue gas duct, a filter belt, and a main exhaust fan. The filter belt and the flue gas duct are arranged perpendicular to each other in their transverse sections. The sintering flue gas is filtered by the filter belt in the flue gas duct. The main exhaust fan is installed in the flue gas duct to generate negative pressure, so that the sintering flue gas does not overflow during the chromium removal process.

[0027] The vanadium-titanium removal equipment also includes a filter belt cleaning tank, an absorbent wetting tank, and filter belt rotating shafts. The number of filter belt rotating shafts is even, and they are arranged in parallel and symmetrically with the middle being lower and the sides being higher. The filter belt rotating shafts are connected to the filter belts, so that the filter belts rotate clockwise with the filter belt rotating shafts. The absorbent wetting tank is placed inside the annular space surrounded by the filter belts, and the filter belt rotating shaft located at the upper center is located inside the absorbent wetting tank. The filter belt cleaning tank is placed directly below the annular space surrounded by the filter belts, and the filter belt rotating shaft located at the lower center is located inside the filter belt cleaning tank.

[0028] The horizontal width of the filter belt cleaning tank is greater than the distance between the two filter belts with the furthest horizontal spacing; the horizontal width of the absorbent wetting tank is less than the distance between the two filter belts with the furthest horizontal spacing.

[0029] Both the filter belt cleaning tank and the absorbent wetting tank are filled with immersion solution, which is a mixed solution of H2SO4 and H3PO4. The immersion solution is used to clean the residue on the filter belt. The percentage concentration of H2SO4 in the mixed solution is 2.5% to 4.5%, and the percentage concentration of H3PO4 is 3% to 3.8%. The linear running speed of the filter belt is 20 to 24 m / min, and the ultrasonic vibration frequency is 25 to 35 kHz.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. The waste denitrification catalyst is treated by sintering process, and the toxic and harmful substances in the flue gas are absorbed by the vanadium-titanium removal system. This solves the problem that the existing treatment process does not take into account the impact of toxic substances in hazardous waste on sintering flue gas, which leads to the spread of pollutants and secondary environmental pollution.

[0032] 2. By dynamically controlling the balance of vanadium and titanium content in the sintering mixture and sintered ore products, the amount of waste denitrification catalyst can be minimized, thereby maximizing the reduction of the proportion of vanadium and titanium elements entering the sintering flue gas. By using a filter belt wetted with absorbent liquid to filter the flue gas, the absorption of vanadium and titanium elements in the sintering flue gas can be achieved efficiently and at low cost. Through the sintering process, the waste denitrification catalyst can be treated in a synergistic manner, achieving the harmless disposal of the waste denitrification catalyst. This not only saves high hazardous waste treatment costs, but also makes full use of resources such as calcium, magnesium, and iron in the waste denitrification catalyst, creating considerable economic and environmental benefits.

[0033] 3. By treating the sintering flue gas with gravity dust collectors and electrostatic precipitators, the dust content of the sintering flue gas can be significantly reduced, thereby reducing the operating burden of the chromium removal equipment and ensuring the operating effect of the chromium removal equipment.

[0034] 4. Vanadium-titanium removal equipment can further reduce the dust content of sintering flue gas, which not only has the effect of further dust removal, but also reduces the operating burden of desulfurization and denitrification processes, and ultimately achieves compliant ultra-low emissions.

[0035] 5. In addition to generating negative pressure in the pipeline and promoting the combustion of sintered material, the main exhaust fan also prevents the flue gas from overflowing during the chromium removal process.

[0036] 6. The washing solution is a mixed solution of H2SO4 and H3PO4, which can chemically react with the dust particles in the filter belt during washing to achieve a better washing effect. Attached Figure Description

[0037] Figure 1This is a flowchart of a method for co-processing waste denitrification catalysts in the sintering process.

[0038] Figure 2 This is a schematic diagram of the vanadium-titanium removal equipment.

[0039] Figure 3 This is a schematic diagram of the connection structure between the flue gas duct and the filter belt.

[0040] Figure 4 This is a schematic diagram of the cross-section of the joint between the flue gas duct and the filter belt.

[0041] In the diagram: 1-Filter belt cleaning tank; 2-Absorbent liquid wetting tank; 3-Ultrasonic generator; 4-Filter belt rotating shaft; 5-Flue gas duct; 6-Seam between flue gas duct and filter belt; 7-Filter belt; 8-Transverse section of flue gas duct; 9-Longitudinal section of flue gas duct; 10-Sealed outer shell of vanadium-titanium removal equipment. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0043] Extensive experimental research on the fate and distribution of vanadium and titanium elements during the sintering process in major steel plants across the country revealed that as the vanadium and titanium content in the sintering raw materials increases, a certain critical value is reached, at which point the proportion of vanadium and titanium entering the sintering flue gas surges dramatically. Vanadium and titanium elements in the sintering flue gas exist in the form of small particles; the content of vanadium and titanium in large dust particles is extremely low, and the smaller the dust particle size, the higher the vanadium and titanium content. This invention utilizes a sintering process in conjunction with the treatment of waste denitrification catalysts to completely achieve the harmless treatment of waste denitrification catalysts without causing secondary pollution. The specific solution is as follows:

[0044] 1. The waste denitrification catalyst is crushed and ground. The processed material must have a particle size of less than 1 mm accounting for more than 95%.

[0045] 2. The crushed and ground waste denitrification catalyst is mixed with other sintering fluxes to obtain flux mixture, wherein the waste denitrification catalyst accounts for 0.5% to 5.5% of the total flux mixture.

[0046] 3. The flux mixture is mixed with fuel and premixed again, and after one mixing and two granulation processes, a sintering mixture is finally obtained.

[0047] 4. Before feeding the sintering mixture, weigh the mass of the sintering mixture, feed the mixture, number the sintering trolleys, and record the starting and ending positions of the trolleys during the feeding process. Then, ignite and sinter. After sintering, weigh the mass of all sintered ore products between the recorded starting and ending positions of the sintering machine trolleys. During this process, perform multi-point sampling and vanadium and titanium content testing on both the sintering mixture and the sintered ore products.

[0048] 5. Calculate the proportion coefficients of vanadium and titanium elements entering the sinter from the sintering raw materials.

[0049]

[0050] In formula ①, M1 represents the mass of the sintering mixture weighed before feeding, M2 represents the mass of all sintered ore products weighed and recorded between the starting and ending positions of the sintering machine trolley after sintering, Y1% represents the vanadium content of the sintered ore, Y2% represents the titanium content of the sintered ore, X1% represents the vanadium content of the mixture (wet basis), X2% represents the titanium content of the mixture (wet basis), and η represents the proportionality coefficient.

[0051] 6. Determine whether the waste denitrification catalyst in the raw material is added in excess based on the coefficient η: When η value ≥ 0.975, the proportion of waste denitrification catalyst added can be increased, or the current proportion can be maintained; when η value < 0.975, the proportion of waste denitrification catalyst added in the sintering raw material needs to be reduced immediately.

[0052] 7. The sintering flue gas generated during the sintering process first passes through a gravity dust collector, then enters an electrostatic precipitator for treatment. The flue gas exiting the electrostatic precipitator is then treated by a vanadium-titanium removal device. See [link to relevant documentation]. Figure 2 The flue gas is treated by the vanadium-titanium removal equipment and then passes through the main exhaust fan. The immersion solution in the vanadium-titanium removal equipment is a mixed solution of H2SO4 and H3PO4, in which the percentage concentration of H2SO4 is 2.5% to 4.5% and the percentage concentration of H3PO4 is 3% to 3.8%. The linear running speed of the filter belt is 20 to 24 m / min and the ultrasonic vibration frequency is 25 to 35 kHz.

[0053] 8. After vanadium and titanium are removed from the flue gas, desulfurization and denitrification are carried out to finally achieve emission standards.

[0054] The vanadium-titanium removal equipment used in the above method includes a filter belt cleaning tank 1, an absorbent wetting tank 2, an ultrasonic generator 3, a filter belt rotating shaft 4, a flue gas duct 5, a joint between the flue gas duct and the filter belt 6, and a filter belt 7. The connection method of this equipment is as follows:

[0055] Inside the sealed outer casing 10 of the vanadium-titanium removal equipment, six filter belt rotating shafts 4 are placed parallel to each other with a lower center and higher sides. The rotating shafts 4 connect to the filter belts 7, allowing the filter belts 7 to rotate clockwise with the shafts. The absorbent wetting tank 2 is placed inside the annular space surrounded by the filter belts 7. The filter belt rotating shaft located at the upper center is surrounded by the absorbent wetting tank 2 on three sides. The filter belt cleaning tank 1 is placed directly below the annular space surrounded by the filter belts 7, and its width is greater than the distance between the two horizontally furthest rotating shafts 4. The filter belt rotating shaft located at the lower center is surrounded by the filter belt cleaning tank 1 on three sides. An ultrasonic generator 3 is suspended inside the filter belt cleaning tank 1. Through the cavitation effect of the generated ultrasonic waves in the liquid, the dust particles on the filter belts are separated and peeled off, thus achieving the cleaning purpose. The horizontally placed flue gas duct 5 connects to the vertically placed filter belts 7. The structure of the connection point, i.e., the flue gas duct and filter belt joint 6, is shown in [details omitted]. Figure 3 , Figure 4 .

[0056] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0057]

Example 1

[0058] First, waste denitrification catalyst from a coal gas power plant was taken, crushed, and then ground. Particle size analysis of the resulting waste denitrification catalyst powder revealed that particles smaller than 1 mm accounted for 97.3% of the mass. The crushed waste denitrification catalyst powder was then mixed with various other sintering fluxes to obtain a flux mixture, with the waste denitrification catalyst comprising 0.5% of the total flux mixture. The flux mixture was then mixed again with fuel and premixed materials, undergoing a first mixing and a second homogenization and granulation process to finally obtain a sintering mixture. The sintering mixture was weighed, and its mass M1 was 323.1 tons. The mixture was then distributed, and the starting and ending positions of the sintering machine trolley were recorded. Ignition and sintering were then performed. After sintering, the mass M2 of all sintered ore products between the recorded starting and ending positions of the sintering machine trolley was weighed and found to be 258.8 tons. Multiple samples were taken from the sintering mixture and sintered ore products during the process, and the vanadium and titanium content was tested. The vanadium and titanium content (wet basis) of the mixture was 0.049% and 0.037%, respectively, and the vanadium and titanium content of the sintered ore was 0.061% and 0.048%, respectively. The proportionality coefficient η calculated according to formula (1) was 0.989. The value of η is greater than 0.975, and the addition ratio of the denitrification catalyst can be appropriately increased according to the processing volume. The sintering flue gas generated in the sintering process is first treated by a gravity dust collector, then by an electrostatic precipitator, and finally by a vanadium and titanium removal device. The leaching solution in the vanadium and titanium removal device is a mixed solution of H2SO4 and H3PO4. The percentage concentration of H2SO4 in the mixed solution is 2.5%, the percentage concentration of H3PO4 is 3%, the linear running speed of the filter belt is 20m / min, and the ultrasonic vibration frequency is 35kHz. Sintering flue gas after electrostatic precipitator treatment and sintering flue gas after vanadium-titanium removal treatment were sampled separately, and the vanadium and titanium contents in the flue gas were analyzed. The vanadium and titanium contents in the sintering flue gas after electrostatic precipitator treatment were denoted as C1 and C2, respectively, and the vanadium and titanium contents in the sintering flue gas after vanadium-titanium removal treatment were denoted as D1 and D2, respectively. The analysis showed that C1 was 28.35 μg / m³. 3 C2 is 23.59 μg / m 3 D1 is 2.47 μg / m 3 D2 is 2.02 μg / m 3 The average vanadium content in the conventional sintering flue gas of this sintering machine, without the addition of waste denitrification catalyst, is 20–25 μg / m³. 3 The average titanium content is 18–23 μg / m³. 3 As can be seen, after the sintering flue gas produced by adding the waste denitrification catalyst to the sintering batch is treated by the vanadium-titanium removal equipment, the vanadium-titanium content has been reduced to a level far below this level, as shown in Table 1.

[0059] Table 1 Comparison of the effects of vanadium-titanium removal equipment before and after treatment.

[0060] <![CDATA[C1]]> <![CDATA[C2]]> <![CDATA[D1]]> <![CDATA[D2]]> Vanadium-titanium removal rate <![CDATA[28.35μg / m 3 ]]> <![CDATA[23.59μg / m 3 ]]> <![CDATA[2.47μg / m 3 ]]> <![CDATA[2.02μg / m 3 ]]> 91.36％

[0061]

Example 2

[0062] First, waste denitrification catalyst from a coal gas power plant was taken, crushed, and then ground. Particle size analysis of the resulting waste denitrification catalyst powder revealed that particles smaller than 1 mm accounted for 96.9% of the mass. The crushed waste denitrification catalyst powder was then mixed with various other sintering fluxes to obtain a flux mixture, in which the waste denitrification catalyst comprised 5.5% of the total flux mixture. The flux mixture was then mixed again with fuel and premixed materials, undergoing a first mixing and a second homogenization and granulation process to finally obtain a sintering mixture. The sintering mixture was weighed, and its mass M1 was 338.4 tons. The mixture was then distributed, and the starting and ending positions of the sintering machine trolley were recorded. Ignition and sintering were then performed. After sintering, the mass M2 of all sintered ore products between the recorded starting and ending positions of the sintering machine trolley was weighed and found to be 271.06 tons. Multiple samples were taken from the sintering mixture and sintered ore products during the process, and the vanadium and titanium content was tested. The vanadium and titanium content (wet basis) of the mixture was 0.080% and 0.068%, respectively, and the vanadium and titanium content of the sintered ore was 0.109% and 0.083%, respectively. According to formula (1), the proportionality coefficient η was calculated to be 0.959, which is less than 0.975. That is, the proportion of vanadium and titanium elements entering the flue gas is significantly higher than that under normal circumstances, and the addition ratio of denitrification catalyst needs to be reduced. The sintering flue gas generated in this sintering process is first treated by a gravity dust collector, then by an electrostatic precipitator, and finally by a vanadium and titanium removal device. The leaching solution in the vanadium and titanium removal device is a mixed solution of H2SO4 and H3PO4. The percentage concentration of H2SO4 in the mixed solution is 4.5%, the percentage concentration of H3PO4 is 3.8%, the linear running speed of the filter belt is 24 m / min, and the ultrasonic vibration frequency is 25 kHz. Sintering flue gas after electrostatic precipitator treatment and sintering flue gas after vanadium-titanium removal treatment were sampled separately, and the vanadium and titanium contents in the flue gas were analyzed. The vanadium and titanium contents in the sintering flue gas after electrostatic precipitator treatment were denoted as C1 and C2, respectively, and the vanadium and titanium contents in the sintering flue gas after vanadium-titanium removal treatment were denoted as D1 and D2, respectively. The analysis showed that C1 was 175.92 μg / m³. 3 C2 is 145.43 μg / m 3 D1 is 14.25 μg / m 3 D2 was 11.94 μg / m 3 The average vanadium content in the conventional sintering flue gas of this sintering machine, without the addition of waste denitrification catalyst, is 20–25 μg / m³. 3 The average titanium content is 18–23 μg / m³. 3 As can be seen, after the sintering flue gas produced by adding the waste denitrification catalyst to the sintering batch is treated by the vanadium-titanium removal equipment, the vanadium-titanium content has been reduced to below this level, as shown in Table 2.

[0063] Table 2 Comparison of the effects of vanadium-titanium removal equipment before and after treatment.

[0064] <![CDATA[C1]]> <![CDATA[C2]]> <![CDATA[D1]]> <![CDATA[D2]]> Vanadium-titanium removal rate <![CDATA[175.92μg / m 3 ]]> <![CDATA[145.43μg / m 3 ]]> <![CDATA[14.25g / m 3 ]]> <![CDATA[11.94μg / m 3 ]]> 91.85％

[0065]

Example 3

[0066] First, waste denitrification catalyst from a coal gas power plant was taken, crushed, and then ground. Particle size analysis of the resulting waste denitrification catalyst powder revealed that particles smaller than 1 mm accounted for 96.7% of the mass. The crushed waste denitrification catalyst powder was then mixed with various other sintering fluxes to obtain a flux mixture, with the waste denitrification catalyst comprising 3.5% of the total flux mixture. The flux mixture was then mixed again with fuel and premixed materials, undergoing a first mixing and a second homogenization and granulation process to finally obtain a sintering mixture. The sintering mixture was weighed, and its mass M1 was 333.9 tons. The mixture was then distributed, and the starting and ending positions of the sintering machine trolley were recorded. Ignition and sintering were then performed. After sintering, the mass M2 of all sintered ore products between the recorded starting and ending positions of the sintering machine trolley was weighed and found to be 268.61 tons. Multiple samples were taken from the sintered ore products of the sintering mixture during the process, and the vanadium and titanium content was tested. The vanadium and titanium content (wet basis) of the mixture was 0.058% and 0.049%, respectively, and the vanadium and titanium content of the sintered ore was 0.074% and 0.062%, respectively. According to formula (1), the proportionality coefficient η was calculated to be 0.979. Since the value of η is slightly greater than 0.975, the addition ratio of the denitrification catalyst can be maintained for production. The sintering flue gas generated during the sintering process is first treated by a gravity dust collector, then by an electrostatic precipitator, and finally by a vanadium and titanium removal device. The leaching solution in the vanadium and titanium removal device is a mixed solution of H2SO4 and H3PO4. The percentage concentration of H2SO4 in the mixed solution is 3.5%, the percentage concentration of H3PO4 is 3.4%, the linear running speed of the filter belt is 22m / min, and the ultrasonic vibration frequency is 30kHz. Sintering flue gas after electrostatic precipitator treatment and sintering flue gas after vanadium-titanium removal treatment were sampled separately, and the vanadium and titanium contents in the flue gas were analyzed. The vanadium and titanium contents in the sintering flue gas after electrostatic precipitator treatment were denoted as C1 and C2, respectively, and the vanadium and titanium contents in the sintering flue gas after vanadium-titanium removal treatment were denoted as D1 and D2, respectively. The analysis showed that C1 was 31.29 μg / m³. 3 C2 is 26.01 μg / m 3 D1 is 2.79 μg / m 3 D2 is 2.30 μg / m 3 The average vanadium content in the conventional sintering flue gas of this sintering machine, without the addition of waste denitrification catalyst, is 20–25 μg / m³. 3 The average titanium content is 18–23 μg / m³. 3As can be seen, after the sintering flue gas produced by adding the waste denitrification catalyst to the sintering batch is treated by the vanadium-titanium removal equipment, the vanadium-titanium content has been reduced to a level far below this level, as shown in Table 3.

[0067] Table 3 Comparison of the effects of vanadium-titanium removal equipment before and after treatment.

[0068] <![CDATA[C1]]> <![CDATA[C2]]> <![CDATA[D1]]> <![CDATA[D2]]> Vanadium-titanium removal rate <![CDATA[31.29μg / m 3 ]]> <![CDATA[26.01μg / m 3 ]]> <![CDATA[2.79g / m 3 ]]> <![CDATA[2.30μg / m 3 ]]> 91.12％

[0069] This invention employs a sintering process to dispose of spent denitrification catalysts and utilizes a vanadium-titanium removal system to absorb toxic and harmful substances in the flue gas. This addresses the problem that existing treatment processes fail to consider the impact of toxic substances from hazardous waste on sintering flue gas, leading to pollutant diffusion and secondary environmental pollution. By dynamically controlling the amount of spent denitrification catalyst added through a balance of vanadium and titanium content in the sintering mixture and sintered ore products, the proportion of vanadium and titanium entering the sintering flue gas is minimized. Furthermore, the use of filter belts wetted with absorbent liquid to filter the flue gas enables efficient and low-cost absorption of vanadium and titanium from the sintering flue gas. Through the synergistic treatment of spent denitrification catalysts via the sintering process, the harmless disposal of spent denitrification catalysts is achieved, saving significant hazardous waste treatment costs and fully utilizing the waste catalysts. The calcium, magnesium, and iron resources in the nitrification catalyst create considerable economic and environmental benefits. Treating the sintering flue gas with gravity dust collectors and electrostatic precipitators significantly reduces the dust content, thereby reducing the operational burden on the chromium removal equipment and ensuring its effectiveness. The vanadium-titanium removal equipment further reduces the dust content in the sintering flue gas, achieving both further dust removal and reducing the operational burden on the desulfurization and denitrification processes, ultimately achieving compliant ultra-low emissions. The main exhaust fan, in addition to generating negative pressure in the pipeline and promoting the combustion of the sintered material, also prevents flue gas from overflowing during chromium removal. The washing solution, a mixture of H2SO4 and H3PO4, reacts chemically with the dust particles in the filter belt during washing, achieving a better washing effect.

Claims

1. A method for co-processing waste denitrification catalyst in a sintering process, characterized in that, include: S1. Prepare the sintering mixture; S2. Before sintering, weigh the mass of the sintering mixture, and then distribute, ignite, and sinter the sintering mixture. After sintering, weigh all sintered ore products between the starting and ending positions of the sintering machine trolley as recorded. Perform multi-point sampling and vanadium and titanium content testing on the sintered mixture and sintered ore products during this process. S3. Calculate the proportion coefficients of vanadium and titanium elements in the sintering raw materials entering the sinter. The calculation formula is as follows: In Formula ①, M1 represents the mass of the sintering mixture weighed before feeding, M2 represents the mass of all sintered ore products weighed and recorded between the starting and ending positions of the sintering machine trolley after sintering, Y1% represents the vanadium content of the sintered ore, Y2% represents the titanium content of the sintered ore, X1% represents the vanadium content of the wet-based mixture, X2% represents the titanium content of the wet-based mixture, and η represents the proportionality coefficient. S4. The proportionality coefficient η is used to determine whether the waste denitrification catalyst in the raw material is added in excess: when the proportionality coefficient η is ≥ 0.975, it is determined that the waste denitrification catalyst is not added in excess, and the proportion of waste denitrification catalyst added should be increased; when the proportionality coefficient η is < 0.975, it is determined that the waste denitrification catalyst is added in excess, and the proportion of waste denitrification catalyst added in the sintering raw material should be reduced.

2. The method for co-processing waste denitrification catalyst in a sintering process according to claim 1, characterized in that, In S1, the preparation of the sintering mixture is described as follows: The waste denitrification catalyst is crushed and ground, and the processed material has a particle size of less than 1 mm accounting for more than 95%; The crushed and ground waste denitrification catalyst is mixed with various sintering fluxes to obtain flux mixture, in which the waste denitrification catalyst accounts for 0.5% to 5.5% of the total flux mixture; The flux mixture is mixed with fuel and premixed again, and after one mixing and two homogenization and granulation, a sintering mixture is finally obtained.

3. The method for co-processing waste denitrification catalyst in a sintering process according to claim 2, characterized in that, The various sintering fluxes mentioned include quicklime, limestone, magnesia, and dolomite.

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