Method and system for cooperatively treating waste denitration catalyst by sintering process

Abstract

The invention relates to a method and system for cooperatively treating a waste denitration catalyst through a sintering process, the method comprises the steps that a sintering mixture is prepared, the proportionality coefficient of vanadium and titanium elements entering sinter in a sintering raw material is calculated, the value of the proportionality coefficient eta is used for judging whether the waste denitration catalyst in the raw material is excessively added or not, and the system comprises a flue gas pipeline, a filter belt and a main exhaust fan; the filter belt is perpendicular to the transverse section of the flue gas pipeline, sintering flue gas is filtered by the filter belt in the flue gas pipeline, and the main exhaust fan is used for exhausting air to generate negative pressure, so that the sintering flue gas does not overflow in the chromium removal process. The method has the advantages that the waste denitration catalyst is treated by adopting a sintering process, and toxic and harmful substances in the flue gas are absorbed through the vanadium-titanium removal system, so that the problems of pollutant diffusion and secondary environmental pollution caused by the fact that the influence of the toxic substances in hazardous wastes on the sintering flue gas is not considered in an existing treatment process are solved.

Description

Technical Field

[0001] The present invention relates to the field of comprehensive utilization of wastes, and in particular to a method and system for collaboratively treating waste denitration catalysts using a sintering process. Background Art

[0002] With the implementation of the new "Environmental Protection Law" and "Solid Waste Law", the state has strictly supervised the discharge and disposal of hazardous wastes. According to regulations, hazardous wastes must be handed over to qualified enterprises for centralized treatment. However, the hazardous waste treatment capacity has reached saturation across the country, and steel companies have to use their own furnaces to centrally treat some hazardous wastes. According to the national hazardous waste list, waste denitrification catalysts are hazardous wastes, the waste category is "HW50", and the code is "772-007-50". The waste vanadium-titanium catalysts generated during the flue gas denitrification process are hazardous wastes and are toxic (T), especially the vanadium pentoxide therein is highly toxic and can cause respiratory, nervous and digestive system disorders. In order to deal with these hazardous wastes, some steel companies use their own furnaces to harmlessly treat these waste denitrification catalysts, so that part of the vanadium and titanium elements in the waste enter the atmosphere with the flue gas, causing serious secondary pollution to the environment. Research has found that when the vanadium and titanium content in the sintering raw materials is low, the vanadium and titanium in the raw materials are mainly solidified in the sintered ore after sintering, and the vanadium and titanium content discharged into the atmosphere with the flue gas is extremely low; but when the vanadium and titanium content in the sintering raw materials is higher than the critical value under a certain condition, after sintering, the proportion of vanadium and titanium content entering the sintering flue gas increases sharply. Moreover, under different sintering raw materials and process parameters, the critical value of the vanadium and titanium content is not fixed, which increases the difficulty of processing. There is currently no relevant research and report on how to control the amount of waste denitrification catalyst added in the sintering process to reduce the impact on the environment.

[0003] On the other hand, through the study of the existence form of vanadium and titanium in sintering flue gas, it was found that vanadium and titanium in sintering flue gas exist in the form of solid particles, and vanadium and titanium elements are mainly enriched in fine-grained dust, and the content in larger dust particles is very low. Through the study of sintering flue gas dust removal ash, it was also found that the smaller the dust particle size of the dust removal ash, the higher the percentage of vanadium and titanium elements. The sintering process of domestic and foreign steel enterprises generally uses electrostatic precipitators to treat sintering flue gas. Larger dust particles are easily captured, while small dust particles rich in vanadium and titanium are not effectively removed and eventually discharged into the atmosphere, causing harm to the environment. There is currently no better economical and reasonable method for removing vanadium and titanium from sintering flue gas.

[0004] Wu Yanmei published an article entitled "The Harmless Treatment Practice of Chromium Slag in Sintering Production", which introduced the production practice of Sichuan Dagang in treating chromium-containing waste slag during sintering. Wang Hongjun et al. published an article entitled "The Application Practice of Chromium Slag in Jiugang Sintering Production", which introduced Jiugang's treatment method of using chromium slag as a sintering auxiliary material in the sintering system. Both articles are about the application of chromium-containing solid waste in the sintering system, but their technical research content only considers the impact of chromium on the output and quality of sintering production. The existence form and final destination of chromium in the process of sintering treatment of chromium-containing waste are not involved and considered, ignoring the impact of chromium-containing waste on the environment. As hazardous waste, it needs to be centrally treated harmlessly, and the method of simply treating it as a sintering auxiliary material without considering environmental factors may not only fail to achieve the harmless treatment of toxic waste, but also cause the spread of hazardous waste through sintering flue gas emissions.

[0005] The application number is CN201921036591.2, and the patent name is "Tail Gas Treatment Equipment in the Process of Disposal of Chromium-Containing Heavy Metal Hazardous Waste". It includes a dust purification device, an acid gas purification tank, and a sludge settling tank. The dust purification device can mix the steam generated during water quenching with the flue gas, and use the condensation of the steam to settle the dust in the flue gas. The dust-removed flue gas is sent into the acid gas purification tank, below the liquid level, so that the acid gas in the flue gas fully reacts with the solution, thereby purifying the acid gas. When the equipment is running, a large amount of steam is required to participate in condensation, which consumes a lot of resources and energy, and has high operating costs. The effect of steam condensation in purifying chromium-containing dust particles is limited, and the removal rate of chromium-containing dust is low.

[0006] Application number CN201811373734.9, patent name "double-drum rotary kiln harmless disposal of chromium-containing sludge flue gas purification system", including a tilted double-drum rotary kiln, which effectively solves the dust, acid gas, nitrogen oxide waste gas treatment process in the chromium-containing sludge treatment process, so that its emissions meet the requirements of the "Hazardous Waste Incineration Pollution Control Standard" (GB18484-2001). The device passes the flue gas through the settling chamber and cyclone dust collector in sequence, and then washes it through the first water film dust removal and desulfurization spray tower, and then through the second water film dust removal and desulfurization spray tower, and then through the third water film dust removal and desulfurization spray tower. The whole system has a complex structure, and through sedimentation, cyclone dust removal, and three-stage spraying, the equipment cost and operating cost are high. In the selection of reagents, there is no targeted capture of chromium-containing dust, and chromium-containing fine dust cannot be completely captured.

[0007] The application number is CN200810058792.2, and the patent name is "Method for determining heavy metal elements in cigarette smoke using a smoke capture and absorption device". The smoke capture and absorption device includes an outer sleeve (1), an inner sleeve (2) and a sealing plug (3). The outer sleeve (1) is provided with an inlet (7) and an outlet (8). The outer sleeve (1), the inner sleeve (2) and the sealing plug (3) are sealed and matched in sequence. An upper sieve plate (6) and a lower sieve plate (4) are provided in the inner sleeve (2), and a buffer filler (5) is filled between the two sieve plates. In this method, the residence time and absorption time of smoke in the capture agent are slightly prolonged by the combined action of the upper sieve plate, the lower sieve plate, the buffer filler and other structures. In addition, the smoke is dispersed by the sieve plate and buffered by the buffer filler, and the reaction surface area of ​​smoke absorption is increased, so that the smoke components are more fully absorbed. However, the buffer filler can only play a buffering role. Its gap is too large to filter the tiny dust particles in the gas. The absorption of dust particles depends only on the short-term contact reaction between the collector and the flue gas, resulting in a low dust capture rate. In addition, the device can only absorb gases with small flow rates and low flue gas flow rates. The impact generated by the large flow rate and high flow rate of sintering flue gas passing into the device will disperse the buffer filler and even cause the collector to splash. In addition, the contact reaction time between the flue gas with a faster flow rate and the collector is shorter, resulting in insufficient absorption.

[0008] The application number is CN201921879172.5, and the patent name is "A Asphalt Smoke Absorption Device". The asphalt smoke absorption device has a structure including a cylinder, a resistance layer, an ozone layer, an ultraviolet lamp, a spray covering layer, a fan, and an exhaust port. It is characterized in that: a multi-layer filter plate is arranged at the bottom of the cylinder, the first layer of the multi-layer filter plate is provided with a screen made of asbestos mesh, the second layer is a material of activated carbon honeycomb holes, and the third layer is a screen plate covered with quicklime, and the height between two adjacent absorption layers is 300mm-500mm. The central cross-sectional position of the cylinder is the resistance layer, the spray covering layer, and the return smoke fan air collection port from top to bottom, and the spray covering layer is added with an organic flux that can absorb asphalt particles. The device uses an organic flux to absorb particulate matter in the asphalt smoke, and through the joint action of the resistance layer, the ozone layer, and the ultraviolet lamp, the asphalt smoke and oxygen are further reacted at high temperature to achieve a good absorption effect. However, the use of this device has certain limitations and disadvantages: first, the device has a complex structure and high cost. The material of the activated carbon honeycomb holes will become invalid after use and needs to be replaced regularly. The resources and energy costs consumed by the operation of the ozone layer and the resistance layer are also high, which significantly increases the operating cost of the equipment; second, in the several layers of filtering structure of the device, the asbestos mesh has limited filtering and intercepting effect on tiny dust in the flue gas, and the screen plate covered with quicklime only absorbs some acidic gases in the flue gas, and the absorption is not complete enough. The spraying of organic flux is to spray the spray liquid through tiny water droplets, and its collision with small asphalt particles in the flue gas is random, so the spraying absorption effect is poor. The combined effect of the resistance layer, ozone layer, and ultraviolet lamp only has a certain effect on organic particles in asphalt flue gas, and its effect is also very limited.

[0009] The application number is CN202021710826.4, and the patent name is "A petrochemical flue gas absorption device", which includes an absorption tower, a scrubbing part, a chemical absorption part and a water vapor recovery part. The scrubbing part is arranged at the bottom of the absorption tower, the chemical absorption part is arranged in the middle of the absorption tower, and the water vapor recovery part is arranged at the upper part of the absorption tower. The water vapor recovery part includes a water vapor baffle, and the water vapor baffle includes a water vapor baffle groove and a water vapor recovery groove. A cold air channel is provided at the top of the water vapor baffle groove, and a water outlet groove is provided at the bottom of the water vapor recovery groove. A heat conduction plate is provided on the cold air channel, a water collecting plate is provided on the water outlet groove, and a water outlet is provided at the bottom of the water outlet groove. After the flue gas is passed into the bottom of the absorption tower, it is scrubbed and cooled at the bottom of the absorption tower, and then chemically absorbed by the acid gas, and finally the water vapor is recovered. The device effectively solves the problem of catalysts and water in flue gas after treatment in conventional absorption towers, but it still has certain limitations and disadvantages: when the flue gas passes through the scrubbing part of the device, it usually moves upward rapidly in the form of bubbles, and 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, and the chemical absorption and water vapor absorption parts cannot achieve the purpose of absorbing dust particles in the flue gas.

[0010] Application number CN201410223759.6, patent name "A method for detecting chromium, nickel, arsenic, selenium, cadmium and lead in cigarette sidestream smoke", characterized by: using a fishtail cover in series with a quartz fiber filter to collect cigarette sidestream smoke particulate matter, three-stage nitric acid solution in series to collect sidestream smoke gaseous matter, microwave digestion method to digest the sample, and inductively coupled plasma mass spectrometry to detect the content of chromium, nickel, arsenic, selenium, cadmium and lead in the particulate matter and gaseous matter samples. This method absorbs toxic substances in the smoke separately and then detects them. This method requires the particulate matter and gaseous matter to be processed separately, which undergoes a series of processes such as elution, extraction, digestion, ultrasonic vibration, heating and concentration. The operation is complicated, time-consuming and costly. More importantly, the method of collecting particulate matter through a quartz fiber filter cannot completely absorb the particulate matter in the smoke, and some particles with extremely small particle sizes cannot be captured.

[0011] Among the existing domestic methods for harmless disposal of spent denitrification catalysts, there is no relatively economical and reasonable method that neither causes secondary environmental pollution nor can completely and permanently dispose of hazardous wastes containing vanadium and titanium. Summary of the invention

[0012] The purpose of the present invention is to provide a method and system for the coordinated treatment of waste denitration catalysts by a sintering process, which solves the problem that the existing treatment process does not take into account the impact of toxic substances in hazardous wastes on sintering flue gas, thereby causing the spread of pollutants and causing secondary environmental pollution. The waste denitration catalysts are harmlessly treated, which is more economical and reasonable, and provides a new route for the harmless treatment of waste denitration catalysts.

[0013] To achieve the above object, the present invention is implemented through the following technical solutions:

[0014] A method for treating a waste denitration catalyst by sintering process, specifically comprising:

[0015] S1, preparing a sintering mixture;

[0016] S2. Before sintering, weigh the mass of the sintering mixture, distribute, ignite and sinter the sintering mixture; after sintering, weigh the mass of all sintered ore products between the starting position and the end position of the sintering machine trolley, and perform multi-point sampling and vanadium and titanium content detection on the sintering mixture and sintered ore products in the process;

[0017] S3. Calculate the ratio coefficient of vanadium and titanium elements in the sintering raw materials into the sintered ore. The calculation formula is as follows:

[0018]

[0019] In formula ①, M1 represents the mass of the sintered mixture weighed before distribution, M2 represents the mass of all sintered ore products between the starting position and the end position of the sintering machine trolley recorded 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 value of the proportional coefficient η is used to determine whether the waste denitration catalyst is excessively added in the raw material: when the value of the proportional coefficient η is ≥0.975, it is determined that the waste denitration catalyst is not excessively added, and the addition ratio of the waste denitration catalyst is increased; when the value of the proportional coefficient η is <0.975, it is determined that the waste denitration catalyst is excessively added, and the addition ratio of the waste denitration catalyst in the sintering raw material needs to be reduced.

[0021] In S1, a sintering mixture is prepared, the contents of which are as follows:

[0022] The spent 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 denitration catalyst is mixed with a plurality of sintering fluxes to obtain a flux mixture, wherein the waste denitration catalyst accounts for 0.5% to 5.5% of the total flux mixture;

[0024] The flux mixture is mixed with the fuel and the premix again, and after the first mixing and the second mixing and granulation, a sintering mixture is finally obtained.

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

[0026] A sintering process coordinated treatment system for waste denitrification catalysts includes a vanadium-titanium removal device, which includes a flue gas duct, a filter belt, and a main exhaust fan. The filter belt and the transverse section of the flue gas duct are arranged perpendicular to each other. The sintering flue gas is filtered through the filter belt in the flue gas duct. The main exhaust fan is arranged in the flue gas duct to extract air to generate negative pressure, so that the sintering flue gas does not overflow during the chromium removal process.

[0027] The vanadium removal and titanium removal equipment also includes a filter belt cleaning tank, an absorption liquid wetting tank, and a filter belt rotating shaft. The number of the filter belt rotating shafts is an even number, and the filter belt rotating shafts are arranged in parallel and symmetrically in a manner of being low in the middle and high on both sides. The filter belt rotating shaft is connected to the filter belt so that the filter belt rotates clockwise along with the filter belt rotating shaft. The absorption liquid wetting tank is placed inside the annular space surrounded by the filter belt, the filter belt rotating shaft located at the upper center is arranged inside the absorption liquid wetting tank, the filter belt cleaning tank is placed directly below the annular space surrounded by the filter belt, and the filter belt rotating shaft located at the lower center is arranged 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 belt rotation axes with the farthest horizontal spacing; the horizontal width of the absorption liquid wetting tank is less than the distance between the two filter belt rotation axes with the farthest horizontal spacing.

[0029] The filter belt cleaning tank and the absorption liquid wetting tank are both filled with leaching liquid. The leaching liquid is a mixed solution of H2SO4 and H3PO4. The leaching liquid 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 present invention has the following beneficial effects:

[0031] 1. The sintering process is used to dispose of the waste denitrification catalyst, and the vanadium-titanium removal system is used to absorb the toxic and harmful substances in the flue gas, which solves the problem that the existing treatment process does 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;

[0032] 2. The amount of waste denitrification catalyst added is dynamically controlled by balancing the vanadium and titanium content in the sintering mixture and the sintering ore product, so as to minimize the proportion of vanadium and titanium entering the sintering flue gas. The method of filtering the flue gas with a filter belt moistened with an absorption liquid can achieve efficient and low-cost absorption of vanadium and titanium in the sintering flue gas. The waste denitrification catalyst is disposed of in a coordinated manner through the sintering process, and the waste denitrification catalyst is disposed of harmlessly. This not only saves high hazardous waste treatment costs, but also makes full use of calcium, magnesium, iron and other resources in the waste denitrification catalyst, creating considerable economic and environmental benefits.

[0033] 3. The sintering flue gas is treated by gravity dust collector and electrostatic dust collector, which can significantly reduce the dust content of the sintering flue gas, thereby reducing the operating burden of the chromium removal equipment and ensuring the operating effect of the chromium removal equipment;

[0034] 4. The vanadium removal and titanium removal equipment can further reduce the dust content of the sintering flue gas, which can further remove dust and reduce the operating burden of the desulfurization and denitrification processes, ultimately achieving compliant ultra-low emissions;

[0035] 5. The main exhaust fan not only creates negative pressure in the pipeline and promotes the combustion of sintering materials, but also prevents the smoke from overflowing during the chromium removal process;

[0036] 6. The immersion liquid is a mixed solution of H2SO4 and H3PO4. During immersion, it can react chemically with the dust particles in the filter belt to achieve better immersion effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1It is a flow chart of a method for co-processing waste denitration catalyst by sintering process.

[0038] Figure 2 It is a schematic diagram of the structure of the devanadium-titanium equipment.

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

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

[0041] In the figure: 1-filter belt cleaning tank 2-absorption liquid wetting tank 3-ultrasonic generator 4-filter belt rotating shaft 5-flue gas duct 6-joint 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 housing of devanadium and titanium removal equipment. DETAILED DESCRIPTION

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

[0043] Through a large number of experimental studies on the whereabouts and distribution of vanadium and titanium elements in the sintering process of major steel mills across the country, it was found that as the vanadium and titanium content in the sintering raw materials increases and reaches a certain critical value, the proportion of vanadium and titanium entering the sintering flue gas increases sharply; the vanadium and titanium elements in the sintering flue gas exist in the form of small particles, and the vanadium and titanium content in large particles of dust is extremely low. The lower the dust particle size, the higher the vanadium and titanium content. The present invention uses the sintering process to coordinate the treatment of waste denitration catalysts, completely realizing the harmless treatment of waste denitration catalysts without causing secondary pollution. The specific scheme is as follows:

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

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

[0046] 3. The flux mixture is mixed with the fuel and the premix again, and after the first mixing and the second mixing and granulation, a sintering mixture is finally obtained.

[0047] 4. Before spreading, weigh the mass of the sintering mixture, spread the mixture, number the sintering trolleys, record the starting and ending positions of the trolleys corresponding to the weighed sintering mixture spreading process, and 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, and perform multi-point sampling and vanadium and titanium content testing on the sintering mixture and sintered ore products in the process.

[0048] 5. Calculate the ratio coefficient of vanadium and titanium elements in sintering raw materials entering sintered ore.

[0049]

[0050] In formula ①, M1 represents the mass of the sintered mixture weighed before distribution, M2 represents the mass of all sintered ore products between the starting position and the end position of the sintering machine trolley recorded 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 excessive waste denitrification catalyst is added to the raw materials based on the coefficient η value: when the η value is ≥0.975, the addition ratio of the waste denitrification catalyst can be increased, or the current addition ratio can be maintained; when the η value is <0.975, the addition ratio of the waste denitrification catalyst in the sintering raw materials 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, and the flue gas from the electrostatic precipitator is then treated by a vanadium removal and titanium removal device. Figure 2 The flue gas is treated by the devanadium-titanium equipment and then passes through the main exhaust fan; the leaching liquid in the devanadium-titanium equipment is a mixed solution of H2SO4 and H3PO4, 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.

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

[0054] The devanadium and titanium equipment used in the above method includes a filter belt cleaning tank 1, an absorption liquid 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 equipment is connected as follows:

[0055] Inside the sealed housing 10 of the devanadium-titanium equipment, six filter belt rotating shafts 4 are placed parallel to each other in a manner of being low in the middle and high on both sides. The filter belt rotating shaft 4 is connected to the filter belt 7, so that the filter belt 7 can rotate clockwise with the filter belt rotating shaft 4. The absorption liquid wetting tank 2 is placed inside the annular space surrounded by the filter belt 7. The filter belt rotating shaft located at the upper center is surrounded on three sides by the absorption liquid wetting tank 2. The filter belt cleaning tank 1 is placed directly below the annular space surrounded by the filter belt 7. Its width is greater than the distance between the two filter belt rotating shafts 4 with the farthest horizontal spacing. The filter belt rotating shaft located at the lower center is surrounded on three sides by the filter belt cleaning tank 1. An ultrasonic generator 3 is suspended inside the filter belt cleaning tank 1. The cavitation effect of the ultrasonic wave generated by the ultrasonic generator in the liquid separates and peels off the dust particles on the filter belt, thereby achieving the purpose of cleaning. The flue gas duct 5 placed in the horizontal direction is connected to the filter belt 7 in the vertical direction. The connection between the two, i.e., the joint 6 between the flue gas duct and the filter belt, is shown in FIG. Figure 3 , Figure 4 .

[0056] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0057] [Example 1]

[0058] First, take the waste denitration catalyst from the gas power plant, crush it and then grind it, and perform particle size analysis on the waste denitration catalyst powder. The analysis shows that the mass of particles less than 1 mm accounts for 97.3%. The crushed waste denitration catalyst powder is mixed with other sintering fluxes to obtain a flux mixture, in which the waste denitration catalyst accounts for 0.5% of the total flux mixture. The flux mixture is mixed with the fuel and premix again, mixed once, mixed twice and granulated, and finally a sintering mixture is obtained. The sintering mixture is weighed, and its mass M1 is 323.1 tons. The material is laid, and the starting and end positions of the trolley corresponding to the laying process are recorded. Ignition and sintering are carried out. After sintering, the mass M2 of all sintered ore products recorded between the starting and end positions of the sintering machine trolley is weighed to be 258.8 tons. In this process, the sintering mixture and sintering ore products were sampled at multiple points 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 proportional coefficient η calculated according to formula (1) is 0.989, and the η value is greater than 0.975. The addition ratio of the denitrification catalyst can be appropriately increased according to the processing volume. For the sintering flue gas generated in the sintering process, it is first processed by a gravity dust collector, then enters an electrostatic precipitator for processing, and finally processed by a de-vanadium and titanium equipment. The leaching liquid in the de-vanadium and titanium equipment 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. The sintering flue gas after electrostatic precipitator and the sintering flue gas after vanadium removal and titanium removal equipment were sampled and analyzed for vanadium and titanium content. The vanadium and titanium content in the sintering flue gas after electrostatic precipitator were recorded as C1 and C2, and the vanadium and titanium content in the sintering flue gas after vanadium removal and titanium removal equipment were recorded as D1 and D2. The analysis showed that C1 was 28.35 μg / m 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 the sintering machine without adding spent denitrification catalyst is 20-25 μg / m 3 The average titanium content is 18-23 μg / m 3 It can be seen that the vanadium and titanium content of the sintering flue gas generated after adding the waste denitrification catalyst to the sintering ingredients has dropped to far below this level after being treated by the devanadium and titanium removal equipment, as shown in Table 1.

[0059] Table 1 Comparison of the effects of devanadium and titanium equipment before and after treatment

[0060] <![CDATA[C1]]> <![CDATA[C2]]> <![CDATA[D1]]> <![CDATA[D2]]> Vanadium and 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, take the waste denitration catalyst from the gas power plant, crush it and then grind it, and perform particle size analysis on the waste denitration catalyst powder. The analysis shows that the mass of particles less than 1 mm accounts for 96.9%. The crushed waste denitration catalyst powder is mixed with other sintering fluxes to obtain a flux mixture, in which the waste denitration catalyst accounts for 5.5% of the total flux mixture. The flux mixture is mixed with the fuel and premix again, mixed once, mixed twice and granulated, and finally a sintering mixture is obtained. The sintering mixture is weighed, and its mass M1 is 338.4 tons. The material is laid, and the starting and end positions of the trolley corresponding to the laying process are recorded. Ignition and sintering are performed. After sintering, the mass M2 of all sintered ore products recorded between the starting and end positions of the sintering machine trolley is weighed and is 271.06 tons. The sintering mixture and sintered ore products in the process were sampled at multiple points and tested for vanadium and titanium content. 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. The proportional coefficient η calculated according to formula (1) is 0.959, and the η value is less than 0.975, that is, the proportion of vanadium and titanium elements entering the flue gas is significantly higher than the normal situation, and the addition ratio of the denitrification catalyst needs to be reduced. For the sintering flue gas generated in the sintering process, it is first processed by a gravity dust collector, then enters an electrostatic precipitator for processing, and finally processed by a de-vanadium and titanium equipment. The leaching liquid in the de-vanadium and titanium equipment adopts 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 24m / min, and the ultrasonic vibration frequency is 25kHz. The sintering flue gas after electrostatic precipitator and the sintering flue gas after vanadium removal and titanium removal equipment were sampled and analyzed for vanadium and titanium content. The vanadium and titanium content in the sintering flue gas after electrostatic precipitator were recorded as C1 and C2, and the vanadium and titanium content in the sintering flue gas after vanadium removal and titanium removal equipment were recorded as D1 and D2. The analysis showed that C1 was 175.92 μg / m 3 , C2 is 145.43 μg / m 3 , D1 is 14.25 μg / m 3 , D2 is 11.94 μg / m 3 The average vanadium content in the conventional sintering flue gas of the sintering machine without adding spent denitrification catalyst is 20-25 μg / m 3 The average titanium content is 18-23 μg / m 3 It can be seen that the vanadium and titanium content of the sintering flue gas generated after adding the waste denitrification catalyst to the sintering ingredients has dropped to below this level after being treated by the devanadium and titanium removal equipment, as shown in Table 2.

[0063] Table 2 Comparison of the effects of devanadium and titanium equipment before and after treatment

[0064] <![CDATA[C1]]> <![CDATA[C2]]> <![CDATA[D1]]> <![CDATA[D2]]> Vanadium and 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, take the waste denitration catalyst from the gas power plant, crush it and then grind it, and perform particle size analysis on the waste denitration catalyst powder. The analysis shows that the mass of particles less than 1 mm accounts for 96.7%. The crushed waste denitration catalyst powder is mixed with other sintering fluxes to obtain a flux mixture, in which the waste denitration catalyst accounts for 3.5% of the total flux mixture. The flux mixture is mixed with the fuel and premix again, mixed once, mixed twice and granulated, and finally a sintering mixture is obtained. The sintering mixture is weighed, and its mass M1 is 333.9 tons. The material is laid, and the starting and end positions of the trolley corresponding to the laying process are recorded. Ignition and sintering are carried out. After sintering, the mass M2 of all sintered ore products recorded between the starting and end positions of the sintering machine trolley is weighed and is 268.61 tons. The sintering mixture and sintered ore products in the process were sampled at multiple points and tested for vanadium and titanium content. 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. The proportional coefficient η calculated according to formula (1) is 0.979, and the η value is slightly greater than 0.975. The production can be continued by maintaining the addition ratio of the denitration catalyst. The sintering flue gas generated in the sintering process is first processed by a gravity dust collector, then enters an electrostatic precipitator for processing, and finally processed by a devanadium and titanium removal device. The leaching liquid in the devanadium and titanium removal device is a mixed solution of H2SO4 and H3PO4, the percentage concentration of H2SO4 in the mixed solution is 3.5%, and 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. The sintering flue gas after electrostatic precipitator and the sintering flue gas after vanadium removal and titanium removal equipment were sampled and analyzed for vanadium and titanium content. The vanadium and titanium content in the sintering flue gas after electrostatic precipitator were recorded as C1 and C2, and the vanadium and titanium content in the sintering flue gas after vanadium removal and titanium removal equipment were recorded as D1 and D2. The analysis showed that C1 was 31.29μg / m 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 the sintering machine without adding spent denitrification catalyst is 20-25 μg / m 3 The average titanium content is 18-23 μg / m 3It can be seen that the vanadium and titanium content of the sintering flue gas generated after adding the waste denitrification catalyst to the sintering ingredients has dropped to far below this level after being treated by the devanadium and titanium removal equipment, as shown in Table 3.

[0067] Table 3 Comparison of the effects of devanadium and titanium equipment before and after treatment

[0068] <![CDATA[C1]]> <![CDATA[C2]]> <![CDATA[D1]]> <![CDATA[D2]]> Vanadium and 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] The present invention adopts a sintering process to dispose of the spent denitrification catalyst, and realizes the absorption of toxic and harmful substances in the flue gas through a vanadium-titanium removal system, which solves the problem that the existing treatment process does not consider the impact of toxic substances in hazardous waste on the sintering flue gas, which leads to the diffusion of pollutants and causes secondary environmental pollution; the amount of spent denitrification catalyst added is dynamically controlled by balancing the vanadium and titanium content in the sintering mixture and the sintering ore product, so as to minimize the proportion of vanadium and titanium elements entering the sintering flue gas, and adopts a method of filtering the flue gas with a filter belt moistened with an absorption liquid, which can realize the efficient and low-cost absorption of vanadium and titanium elements in the sintering flue gas, and the spent denitrification catalyst is synergistically disposed of through the sintering process to realize the harmless disposal of the spent denitrification catalyst, which not only saves the high cost of hazardous waste treatment, but also can make full use of the spent denitrification catalyst. The calcium, magnesium, iron and other resources in the nitrate catalyst create considerable economic and environmental benefits; the sintering flue gas is treated by gravity dust collector and electrostatic precipitator, which can significantly reduce the dust content of the sintering flue gas, thereby reducing the operating burden of the chromium removal equipment and ensuring the operating effect of the chromium removal equipment; the vanadium-titanium removal equipment can further reduce the dust content of the sintering flue gas, which not only plays a further dust removal effect, but also can reduce the operating burden of the desulfurization and denitrification process, and finally achieve compliant ultra-low emissions; the main exhaust fan not only plays a role in generating negative pressure in the pipeline and promoting the combustion of sintering materials, but also plays a role in preventing the overflow of flue gas during the chromium removal process; the leaching liquid adopts a mixed solution of H2SO4 and H3PO4, which can chemically react with the dust particles in the filter belt during leaching to achieve better leaching effect.

Claims

1. A method for treating waste denitration catalyst by sintering process, characterized in that: include: S1, preparing a sintering mixture; S2. Before sintering, weigh the mass of the sintering mixture, distribute, ignite and sinter the sintering mixture; After sintering, weigh the mass of all sintered ore products between the starting position and the end position of the sintering machine trolley, and take multi-point samples of the sintered mixture and sintered ore products in the process and test the vanadium and titanium contents; S3. Calculate the ratio coefficient of vanadium and titanium elements in the sintering raw materials into the sintered ore. The calculation formula is as follows: In formula ①, M1 represents the mass of the sintered mixture weighed before distribution, M2 represents the mass of all sintered ore products between the starting position and the end position of the sintering machine trolley recorded 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; S4. The value of the proportional coefficient η is used to determine whether the waste denitration catalyst is excessively added in the raw material: when the value of the proportional coefficient η is ≥0.975, it is determined that the waste denitration catalyst is not excessively added, and the addition ratio of the waste denitration catalyst is increased; when the value of the proportional coefficient η is <0.975, it is determined that the waste denitration catalyst is excessively added, and the addition ratio of the waste denitration catalyst in the sintering raw material needs to be reduced.

2. The method for treating waste denitration catalyst by sintering process according to claim 1, characterized in that: In S1, the preparation of the sintering mixture is as follows: The spent 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 denitration catalyst is mixed with a plurality of sintering fluxes to obtain a flux mixture, wherein the waste denitration catalyst accounts for 0.5% to 5.5% of the total flux mixture; The flux mixture is mixed with the fuel and the premix again, and after the first mixing and the second mixing and granulation, a sintering mixture is finally obtained.

3. The method for treating waste denitration catalyst by sintering process according to claim 2, characterized in that: The various sintering fluxes include quicklime, limestone, magnesia and dolomite.

4. A sintering process coordinated treatment system for waste denitration catalyst according to any one of claims 1 to 3, characterized in that: The vanadium-titanium removal equipment includes a flue gas duct, a filter belt, and a main exhaust fan. The filter belt and the transverse section of the flue gas duct are arranged perpendicular to each other. The sintering flue gas is filtered through the filter belt in the flue gas duct. The main exhaust fan is arranged in the flue gas duct to generate negative pressure by exhausting air so that the sintering flue gas does not overflow during the chromium removal process.

5. A sintering process coordinated treatment system for waste denitration catalyst according to claim 4, characterized in that: The devanadium-titanium equipment also includes a filter belt cleaning tank, an absorption liquid wetting tank, and a filter belt rotating shaft. The number of the filter belt rotating shafts is an even number, and the filter belt rotating shafts are arranged in parallel and symmetrically in a manner of being low in the middle and high on both sides. The filter belt rotating shaft is connected to the filter belt so that the filter belt rotates clockwise along the filter belt rotating shaft. The absorption liquid wetting tank is placed inside the annular space surrounded by the filter belt, the filter belt rotating shaft located at the upper center is arranged inside the absorption liquid wetting tank, the filter belt cleaning tank is placed directly below the annular space surrounded by the filter belt, and the filter belt rotating shaft located at the lower center is arranged inside the filter belt cleaning tank.

6. A sintering process coordinated treatment system for waste denitration catalyst according to claim 5, characterized in that: The horizontal width of the filter belt cleaning tank is greater than the distance between the two filter belt rotation axes with the farthest horizontal spacing; the horizontal width of the absorption liquid wetting tank is less than the distance between the two filter belt rotation axes with the farthest horizontal spacing.

7. A sintering process coordinated treatment system for waste denitration catalyst according to claim 6, characterized in that: The filter belt cleaning tank and the absorption liquid wetting tank are both filled with leaching liquid. The leaching liquid is a mixed solution of H2SO4 and H3PO4. The leaching liquid 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.

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