Method and device for treating nitrogen oxides in the fire smelting of secondary copper

Abstract

The application discloses a kind of regenerative copper fire metallurgy nitrogen oxide processing method and device, processing method includes the following processing steps;By fixed-time fixed-quantity feeding is changed into temperature, nitrogen oxide NOx index feeding;Original fixed-time fixed-quantity feeding is melted after stage temperature exceeds 1300 DEG C and produces a large amount of nitrogen oxide, peak value reaches 1900 mg / M3, SNCR is difficult to process and reaches standard;By regenerative copper raw material is input into anode furnace, detect the data of temperature in furnace, nitrogen oxide NOx, control temperature in furnace 800-1100 DEG C, once temperature rises and exceeds 1100 DEG C or nitrogen oxide NOx reaches emission index and exceeds 70%, should promptly put regenerative copper raw material, emission nitrogen oxide NOx is reduced to 20-30% of emission index and stops feeding, continues to work smelting;Cycle last process, until the whole smelting process ends, by low temperature combustion reduces thermal NOx generation.The beneficial effects of the application are: by temperature control source to reduce the generation of nitrogen oxide NOx control improves denitration efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of recycled copper processing, and in particular to a method and apparatus for treating nitrogen oxides in pyrometallurgical recycled copper. Background Technology

[0002] The generation of nitrogen oxides (NOx, mainly including NO and NO2) during metal smelting is primarily related to high-temperature combustion, chemical reactions, and raw material impurities. The specific generation processes and sources are as follows: 1. High-temperature combustion produces thermal NOx. Mechanism: At high smelting temperatures (usually >1200℃), nitrogen (N2) and oxygen (O2) in the air undergo an oxidation reaction: N2 + O2 = 2NO (high temperature), and the generated NO further reacts with oxygen to form NO2.

[0003] Influencing factors: Temperature: The higher the temperature, the faster the reaction rate (exponential growth).

[0004] Oxygen concentration: Excessive air or oxygen-rich environments can promote NOx formation.

[0005] Residence time: Extended residence time in high-temperature zones increases NOx production.

[0006] 2. Fuel NOx; Mechanism: Nitrogen-containing organic matter or impurities (such as pyridine and amines) in fuels (such as coal and heavy oil) are oxidized during combustion (N + O2 = NO + other products in fuel).

[0007] Characteristics: It can be generated even at medium and low temperatures (800~1000℃). The higher the nitrogen content of the fuel, the greater the NOx emissions.

[0008] 3. Prompt NOx; Mechanism: During fuel-rich (oxygen-deficient) combustion, hydrocarbon radicals (such as CH·) react with N2 to generate intermediate products (such as HCN, NH3), which are then oxidized to NO. CH + N2 = HCN + N is further oxidized to NO.

[0009] 4. Other auxiliary processes; Oxygen blowing operation: High-pressure oxygen injection reacts with high-temperature molten copper, exacerbating local high temperature and nitrogen oxidation.

[0010] The main sources of NOx in metal smelting processes, such as copper smelting, include: fuel combustion + decomposition of nitrogen compounds in ore, thermal NOx generation from hot blast furnace combustion, NOx generation from oxygen blowing and high-temperature electric arc, fuel combustion, and refining processes.

[0011] Currently, the mainstream denitrification methods in China rely on SCR and SNCR equipment. While these methods can control nitrogen oxides (NOx) to some extent, they struggle to meet existing environmental standards in terms of effectiveness and stability. The main problems are as follows: SCR disadvantages: 1. High investment and operating costs: SCR systems require catalysts, reactors, ammonia injection devices, etc., resulting in a large initial investment and high catalyst replacement costs.

[0012] 2. Catalysts are susceptible to poisoning or deactivation: Dust, sulfides (SO2), and other substances in flue gas can cover the catalyst surface or cause chemical poisoning, reducing its activity.

[0013] 3. Ammonium bisulfate (ABS) corrosion problem: Unreacted NH3 reacts with SO3 to form ammonium bisulfate (NH4HSO4), which can easily cause air preheater blockage and equipment corrosion.

[0014] 4. Sensitive to temperature: The optimal reaction temperature of the catalyst is usually between 300 and 450°C. Temperatures that are too high or too low will affect the denitrification efficiency and may even damage the catalyst.

[0015] 5. Large footprint: Traditional honeycomb SCR reactors are large in size, especially in high dust conditions, requiring additional dust removal equipment; SNCR disadvantages: 1. Low denitrification efficiency: Generally around 30%-50%, and during operation, it was found that the actual effect could not even reach 30%, making it difficult to meet higher environmental protection requirements.

[0016] 2. High reaction temperature requirements: The reaction must be strictly controlled within a high temperature range of 850-1100℃, which makes temperature control difficult.

[0017] 3. High consumption of reducing agent: This may lead to increased operating costs, and excessive use may cause secondary pollution, failing to meet environmental standards.

[0018] 4. Potential leakage of reducing agent: If not properly controlled, unreacted reducing agent may be released into the atmosphere, polluting the environment and causing severe corrosion to equipment.

[0019] In the process of pyrometallurgical refining of recycled copper, the treatment of nitrogen oxides (NOx) is indeed a technical challenge, mainly due to the high-temperature smelting environment, fuel combustion, and the conversion of nitrogen elements in raw materials.

[0020] The following are the ways in which this problem occurs: 1. NOx formation mechanism High-temperature combustion: Pyrometallurgical processes typically require high temperatures (above 1200°C), at which point nitrogen (N2) in the air reacts with oxygen (O2) to produce thermal NOx.

[0021] 2. Fuel-type NOx: If nitrogen-containing fuels (such as coal or natural gas) are used, the nitrogen compounds in the fuel will be converted into NOx during combustion.

[0022] 3. Nitrogen impurities in raw materials: Recycled copper may contain impurities such as paint and plastic, which release nitrogen-containing gases during the smelting process, further increasing NOx emissions.

[0023] The formation of nitrogen oxides (NOx) is closely related to temperature, and mainly occurs in the following temperature ranges: 1. High-temperature nitrogen oxides (thermal NOx) When the combustion temperature exceeds 1300℃, nitrogen (N2) and oxygen (O2) in the air undergo a chemical reaction at high temperatures to produce NO. x The higher the temperature, the greater the amount generated. It is one of the main sources of nitrogen oxides in industrial combustion (such as boilers, kilns, etc.).

[0024] Other types of nitrogen oxides Fuel-type NOx: It is formed by the oxidation of nitrogen elements contained in fuels (such as organic nitrogen in coal and petroleum) during combustion. It has a wide temperature range (500-1200℃), but high temperatures will promote its formation.

[0025] Fast NOx: It is generated by the reaction of intermediate products from hydrocarbon decomposition with nitrogen under fuel-rich combustion conditions below 1100℃, and usually accounts for a relatively small proportion.

[0026] In summary, high temperatures (especially above 1300°C) are a key condition for the formation of thermal nitrogen oxides (NOx), while the formation of fuel-based and rapid NOx is related to factors such as temperature, fuel composition, and combustion atmosphere (e.g., oxygen content). Currently, existing technologies do not reduce the generation of nitrogen oxides at the source, and there is an urgent need for a treatment method to reduce nitrogen oxides. Summary of the Invention

[0027] The purpose of this invention is to overcome the shortcomings of existing technologies and improve denitrification efficiency by reducing and controlling the generation of nitrogen oxides (NOx) at the source through temperature control. This is mainly achieved by controlling the furnace temperature within the range of 800-1100℃, and by installing temperature sensors and NOx data monitoring equipment on-site. The original method of timed and quantitative raw material feeding has been replaced with a comprehensive feeding method that combines temperature, NOx, and other factors to control the furnace temperature, thereby reducing NOx generation and improving denitrification efficiency to meet emission requirements. This is a method and apparatus for treating NOx in pyrometallurgical regenerated copper.

[0028] The objective of this invention is achieved through the following technical solution: a method for treating nitrogen oxides in pyrometallurgical regenerated copper, comprising an apparatus used in this method, the apparatus including an anode furnace, a flue gas absorption hood, an SNCR denitrification device, a settling device, an activated carbon injection device, a membrane bag filter device, and a desulfurization tower device, the treatment method comprising the following treatment steps; S1. Recycled copper raw materials are fed into the anode furnace. The furnace temperature and NOx data are monitored, and the furnace temperature is controlled between 800-1100℃. If the temperature exceeds 1100℃ or NOx emissions exceed 70% of the emission standard, recycled copper raw materials should be added promptly. Feeding should be stopped when NOx emissions decrease to 20-30% of the emission standard, and smelting should continue. This process is repeated until the entire smelting process is complete. Low-temperature combustion reduces the generation of thermal NOx. The feeding method has been changed from timed and quantitative feeding to feeding based on temperature and NOx emission standards. The original timed and quantitative feeding method resulted in a large amount of nitrogen oxides being generated when the temperature exceeded 1300℃ in the melting stage, with peak values ​​reaching 1900 mg / m³, making it difficult to achieve SNCR standards. S2, High-temperature flue gas directly connected to SNCR denitrification device; When the system temperature inside the SNCR denitrification unit reaches above 850℃, the SNCR injection guns operate; those below the required temperature do not start, ensuring effective utilization of urea and significantly improving denitrification efficiency. This also prevents ammonia escape. This is achieved through the temperature control system and flue gas... By dynamically adjusting the NOx concentration in the atmosphere and the supply and injection volume of urea, the generation of nitrogen oxides can be effectively reduced.

[0029] Preferably, in step S1, the temperature inside the anode furnace is controlled within the range of 800-1100℃, which reduces the generation of nitrogen oxides (NOx) at the source.

[0030] Preferably, after the temperature inside the anode furnace exceeds 1100°C, the ratio of natural gas to oxygen is adjusted to reduce the generation of nitrogen oxides.

[0031] Preferably, step S2 employs a comprehensive treatment method using monitoring: when the SNCR injection temperature reaches 850-1100℃, urea is automatically injected for denitrification; when the online data shows that the system's nitrogen oxide (NOx) data exceeds two-thirds of the standard emission value, recycled copper raw materials are added for cooling; when the temperature exceeds 1100℃, raw materials are added for cooling, thereby achieving source control of NOx.

[0032] Preferably, the anode furnace, flue gas absorption hood, SNCR denitrification device, settling device, activated carbon injection device, membrane bag device, and desulfurization tower device are all connected by pipelines, and there are three pipelines connecting each of the flue gas absorption hood, SNCR denitrification device, settling device, activated carbon injection device, membrane bag device, and desulfurization tower device.

[0033] Preferably, the top of the anode furnace is provided with a placement trough one, and the bottom of the placement trough one is provided with a placement trough two. A placement mesh plate is provided between the placement trough one and the placement trough two. A smoke extraction pipe one is provided at one end of the SNCR denitrification device, and one end of the smoke extraction pipe one is connected to the flue gas absorption hood.

[0034] Preferably, the side wall of the smoke absorption hood is provided with a sliding sleeve one and a sliding sleeve two, and the sliding sleeve one and the sliding sleeve two are respectively engaged with the sliding rod one and the sliding rod two. The sliding sleeve one and the sliding sleeve two are tightened with the sliding rod one and the sliding rod two by a tightening bolt. The smoke extraction pipe one is provided with a telescopic pipe.

[0035] Preferably, the activated carbon injection device has a mesh plate inside and an injection device on the top, which is fixed by bolts.

[0036] The present invention has the following advantages: 1. This invention improves denitrification efficiency by reducing the generation of nitrogen oxides (NOx) at the source through temperature control. It mainly controls the furnace temperature within the range of 800-1100℃ by installing temperature sensors and NOx data monitoring equipment on-site. The monitoring equipment is existing technology. The original method of feeding raw materials in a timed and quantitative manner has been changed to a comprehensive feeding method that controls the furnace temperature by considering temperature, NOx, and other factors. This reduces the generation of NOx and improves the denitrification efficiency to meet emission requirements.

[0037] 2. The placement mesh plate of the present invention facilitates the placement of waste copper. At the same time, the flue gas absorption hood rises and falls under the action of sliding rod one and sliding rod two, resulting in different absorption effects on the flue gas. The activated carbon injection device is equipped with a mesh plate inside, which facilitates high injection efficiency and also makes it easy to replace the mesh plate.

[0038] 3. By lowering the temperature, this invention reduces the amount of natural gas and liquid oxygen used, resulting in a reduction of energy consumption of more than 25%.

[0039] 4. This invention automatically sprays urea, saving more than 27% while improving NOx removal efficiency.

[0040] 5. Appropriate temperature reduces the generation of nitrogen oxides (NOx), and SNCR temperature control improves the timeliness and effectiveness of denitrification.

[0041] 6. It has been running in smelting enterprises for 5 months. After its use, the nitrogen oxide data has been significantly reduced compared with before the implementation of the method. The hourly pass rate is over 99%, and the daily average pass rate is up to 100%. It has solved the problem of frequent exceedances of emission standards to now being far below the emission targets. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the present invention; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 for Figure 2 A magnified view of a portion of point A in the middle; Figure 4 for Figure 2 A magnified view of a portion of point B in the middle; Figure 5 for Figure 2 A magnified view of a portion of point C.

[0043] In the diagram, 1 is the anode furnace, 2 is the flue gas absorption hood, 3 is the SNCR denitrification device, 4 is the settling device, 5 is the activated carbon injection device, 6 is the membrane bag device, 7 is the desulfurization tower device, 8 is the placement tank 1, 9 is the placement tank 2, 10 is the placement mesh plate, 11 is the smoke extraction pipe 1, 12 is the sliding sleeve 1, 13 is the sliding sleeve 2, 14 is the sliding rod 1, 15 is the sliding rod 2, 17 is the telescopic pipe, 18 is the mesh plate, 19 is the injection device, and 20 is the bolt. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings. The scope of protection of the present invention is not limited to the following description: like Figures 1-5 As shown, a method for treating nitrogen oxides in pyrometallurgical regenerated copper includes an apparatus used in this method. The apparatus includes an anode furnace 1, a flue gas absorption hood 2, an SNCR denitrification device 3, a settling device 4, an activated carbon injection device 5, a membrane bag filter device 6, and a desulfurization tower device 7. The treatment method includes the following treatment steps. S1. Recycled copper raw materials are fed into anode furnace 1. The furnace temperature and NOx data are monitored. The furnace temperature is controlled at 800-1100℃. Once the temperature rises above 1100℃ or NOx reaches more than 70% of the emission standard, recycled copper raw materials should be added in time. Feeding should be stopped when NOx emissions are reduced to 20-30% of the emission standard, and smelting should continue. The previous process is repeated until the entire smelting process is completed. Low-temperature combustion reduces the generation of thermal NOx. The feeding method has been changed from timed and quantitative feeding to feeding based on temperature and NOx indicators. The original timed and quantitative feeding generated a large amount of nitrogen oxides when the temperature exceeded 1300℃ in the melting stage, with a peak value of 1900 mg / m3, which was difficult to treat to meet the SNCR standard. S2, High-temperature flue gas directly connected to SNCR denitrification device; When the system temperature inside the SNCR denitrification unit reaches above 850℃, the SNCR injection gun will start. If the temperature is not reached, it will not start. The starting device is an existing automatic control device, which promotes the effective utilization of urea, greatly improves the denitrification efficiency, and prevents ammonia escape. By dynamically adjusting the supply and urea injection volume through the temperature control system and the NOx concentration in the flue gas, the generation of nitrogen oxides is effectively reduced.

[0045] In this embodiment, in step S1, the temperature inside the anode furnace 1 is controlled within the range of 800-1100℃ to reduce the generation of nitrogen oxides (NOx) at the source.

[0046] In this embodiment, after the temperature inside the anode furnace 1 exceeds 1100°C, the ratio of natural gas to oxygen is adjusted to reduce the generation of nitrogen oxides.

[0047] In this embodiment, step S2 employs a comprehensive monitoring approach: when the SNCR injection temperature reaches 850-1100℃, urea is automatically injected for denitrification; when the online data shows that the system's nitrogen oxide (NOx) data exceeds two-thirds of the standard emission value, recycled copper raw materials are added to cool the system; when the temperature exceeds 1100℃, raw materials are added to cool the system, thus achieving source control of NOx.

[0048] In this embodiment, the anode furnace 1, flue gas absorption hood 2, SNCR denitrification device 3, settling device 4, activated carbon injection device 5, membrane bag device 6, and desulfurization tower device 7 are all connected by pipelines. Furthermore, there are three pipelines connecting the flue gas absorption hood 2, SNCR denitrification device 3, settling device 4, activated carbon injection device 5, membrane bag device 6, and desulfurization tower device 7, which facilitates a large contact surface for the flue gas and facilitates heat dissipation.

[0049] In this embodiment, the top of the anode furnace 1 is provided with a placement groove 8, and the bottom of the placement groove 8 is provided with a placement groove 9. A placement mesh plate 10 is provided between the placement groove 8 and the placement groove 9. The SNCR denitrification device 3 is provided with a smoke extraction pipe 11 at one end, and one end of the smoke extraction pipe 11 is connected to the flue gas absorption hood 2.

[0050] In this embodiment, the side wall of the smoke absorption hood 2 is provided with a sliding sleeve 12 and a sliding sleeve 2 13, and the sliding sleeve 12 and the sliding sleeve 2 13 are respectively engaged with the sliding rod 14 and the sliding rod 2 15. The sliding sleeve 12 and the sliding sleeve 2 13 are tightened with the sliding rod 14 and the sliding rod 2 15 by a tightening bolt 16. The smoke extraction pipe 11 is provided with a telescopic pipe 17.

[0051] In this embodiment, the activated carbon spraying device 5 has a mesh plate 18 inside and a spraying device 19 on the top of the activated carbon spraying device 5. The spraying device 19 is fixed by bolts 20.

[0052] The working principle of this invention is as follows: by controlling the temperature at the source to reduce the generation of nitrogen oxides (NOx) and improve the denitrification efficiency, the furnace temperature is mainly controlled within the range of 800-1100℃. Temperature sensors and NOx data monitoring equipment are installed on-site. The original timed and quantitative feeding of raw materials is replaced by a comprehensive feeding method that controls the furnace temperature by considering temperature, NOx and other factors. This reduces the generation of nitrogen oxides and improves the denitrification efficiency to meet emission requirements.

[0053] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for treating nitrogen oxides in pyrometallurgical regenerated copper, characterized in that: The method includes the apparatus used in this process, which includes an anode furnace, a flue gas absorption hood, an SNCR denitrification device, a settling device, an activated carbon injection device, a membrane bag filter device, and a desulfurization tower device. The treatment method includes the following treatment steps. S1. By feeding recycled copper raw materials into the anode furnace, the furnace temperature and NOx data are monitored. The furnace temperature is controlled at 800-1100℃. Once the temperature rises above 1100℃ or the NOx emission level exceeds 70% of the emission standard, recycled copper raw materials should be added. Feeding should be stopped when the NOx emission level is reduced to 20-30% of the emission standard, and smelting should continue. The previous process is repeated until the entire smelting process is completed. Low-temperature combustion reduces the formation of thermal NOx. S2. High-temperature flue gas directly connected to SNCR denitrification device; When the system temperature inside the SNCR denitrification unit is detected to be above 850℃, the SNCR injection gun will start working. If the temperature is not reached, it will not start, which will promote the effective utilization of urea and greatly improve the denitrification efficiency. It will also prevent ammonia escape. By dynamically adjusting the supply and urea injection volume through the temperature control system and the NOx concentration in the flue gas, the generation of nitrogen oxides will be effectively reduced. The anode furnace, flue gas absorption hood, SNCR denitrification device, settling device, activated carbon injection device, membrane bag device and desulfurization tower device are all connected by pipelines, and there are three pipelines between each of the flue gas absorption hood, SNCR denitrification device, settling device, activated carbon injection device, membrane bag device and desulfurization tower device. The anode furnace is provided with a placement trough 1 on the top and a placement trough 2 on the bottom of the placement trough 1. A placement mesh plate is provided between the placement trough 1 and the placement trough 2. A smoke extraction pipe 1 is provided at one end of the SNCR denitrification device. One end of the smoke extraction pipe 1 is connected to the flue gas absorption hood. The side wall of the smoke absorption hood is provided with a sliding sleeve one and a sliding sleeve two, and the sliding sleeve one and the sliding sleeve two are respectively engaged with the sliding rod one and the sliding rod two. The sliding sleeve one and the sliding sleeve two are tightened with the sliding rod one and the sliding rod two by a tightening bolt. The smoke extraction pipe one is provided with a telescopic pipe.

2. The method for treating nitrogen oxides in pyrometallurgical regenerated copper according to claim 1, characterized in that: In step S1, the temperature inside the anode furnace is controlled within the range of 800-1100℃ to reduce the generation of nitrogen oxides (NOx) at the source.

3. The method for treating nitrogen oxides in pyrometallurgical regenerated copper according to claim 2, characterized in that: Once the temperature inside the anode furnace exceeds 1100℃, the ratio of natural gas to oxygen is adjusted to reduce the generation of nitrogen oxides.

4. The method for treating nitrogen oxides in pyrometallurgical regenerated copper according to claim 1, characterized in that: In step S2, comprehensive treatment is achieved through monitoring: when the SNCR injection temperature reaches 850-1100℃, urea is automatically injected for denitrification; when the online data shows that the system's nitrogen oxide (NOx) data exceeds two-thirds of the standard emission value, recycled copper raw materials are added to cool down; when the temperature exceeds 1100℃, raw materials are added to cool down, thus achieving source control of NOx.

5. The method for treating nitrogen oxides in pyrometallurgical regenerated copper according to claim 1, characterized in that: The activated carbon injection device has a mesh plate inside and an injection device on top, which is fixed by bolts.

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