Method for improving slagging of fuming furnace by using residual reducing flue gas

Abstract

The invention discloses a method for improving slagging of a fuming furnace through residual reducing flue gas, and belongs to the technical field of non-ferrous metallurgy. A blowing opening is additionally formed in a slagging area of a vertical flue of the fuming furnace, oxidizing atmosphere is continuously sprayed into the slagging area when the fuming furnace begins to work, and the fuming furnace is started to work; and the oxidizing atmosphere and the residual reducing flue gas in the slagging area are subjected to an oxidation exothermic reaction, the temperature of the slagging area is increased to 1250-1350 DEG C through heat released by the reaction, and spraying of the oxidizing atmosphere is stopped until work of the fuming furnace is finished. According to the method, the slagging speed of the vertical flue of the fuming furnace is reduced; the cleaning period is prolonged: the cleaning period is prolonged to 6 months from original 3 months, the cleaning frequency is reduced, manpower and material resources are saved, and the production continuity is ensured; the upper limit of the slag adhering amount is improved, and the bearing capacity of the flue to the adhering slag is enhanced. Adhering slag distribution is improved, adhering slag is promoted to be evenly distributed, the protruding height of adhering slag is reduced to 55 cm or below, and the phenomenon that flue gas circulation is affected due to the fact that local adhering slag is too thick is avoided.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal metallurgy technology and relates to a method for improving slagging in a fuming furnace by utilizing residual reducing flue gas. Background Technology

[0002] Fuming furnaces are one of the main processes for processing tin slag and low-tin materials. They are widely used in the tin smelting industry at home and abroad and have advantages such as high metal recovery rate, large production capacity, relatively low energy consumption, and easy mechanization and automation of the process.

[0003] Slagging is a significant factor affecting the normal production and technical and economic indicators of smelting furnaces during operation. Slagging impairs heat and mass transfer processes within the furnace, hindering material flow, disrupting production continuity, and limiting the furnace's capacity and efficiency. It can also cause furnace blockages, forcing production interruptions and resulting in substantial economic losses for the company. Slagging causes wear and corrosion to the furnace body, pipes, and spray guns, shortening equipment lifespan. Furthermore, it reduces energy efficiency and increases energy consumption. Slagging also increases the maintenance cycle and frequency of furnace shutdowns for slagging removal, raising operational costs and safety risks for workers. Finally, slagging restricts the capacity and efficiency of the main tin smelting process, both upstream and downstream of the slag refining stage.

[0004] Therefore, how to develop a method to improve slagging in a fuming furnace using residual reducing flue gas is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a method for improving slagging in a fuming furnace by utilizing residual reducing flue gas.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for improving slagging in a fuming furnace using residual reducing flue gas includes the following steps: An injection port is added to the slagging zone of the direct-flow flue of the fuming furnace. When the fuming furnace starts working, an oxidizing atmosphere is continuously injected into the slagging zone, causing the oxidizing atmosphere to react with the remaining reducing flue gas in the slagging zone in an exothermic oxidation reaction. The heat released by the reaction raises the temperature of the slagging zone to 1250-1300℃ until the fuming furnace stops working and the injection of the oxidizing atmosphere stops.

[0007] The beneficial effects of the present invention are as follows: The slag in the direct-flow flue of the fuming furnace is formed by the rapid cooling and solidification of the flue wall (cold water wall) after the dust particles and molten materials are splashed and adhered to it. It is mainly a dark red or black foamy or dense blocky substance, which mainly contains high melting point components such as Fe2O3, Fe3O4, XY(Si,Al)2O6, and CaAl2Si2O8.

[0008] The oxidizing atmosphere reacts with the remaining reducing flue gas in the slagging zone in an exothermic oxidation reaction. The heat released by the reaction raises the temperature of the slagging zone by 200-300°C, reduces the viscosity of the slag to 40%-50% of its original viscosity, and promotes the slag to flow back into the molten pool.

[0009] Reduce slagging rate: Slagging rate <0.15t / d, a reduction of 40%, effectively reducing the slagging formation rate.

[0010] Extended cleaning cycle: The cleaning cycle has been extended from the original 3 months to 6 months, reducing the number of cleaning operations, saving manpower and resources, and ensuring the continuity of production. Increase the upper limit of ash hanging amount: The upper limit of total ash hanging amount is increased by 20%~25%, which enhances the flue's ability to bear ash hanging. Improved ash distribution: Promotes uniform ash distribution and reduces the height of ash protrusions to below 55cm, avoiding obstruction of flue gas flow due to excessively thick ash in some areas. The height of the slag protrusion is the vertical distance between the thickest part of the slag and the reference plane of the flue wall; the upper limit of the slag amount refers to the maximum slag mass value that the slag-forming zone of the vertical flue can stably bear; the slag formation rate refers to the average increase in the slag mass per day; the cleaning cycle refers to the interval between manual cleaning of the slag during continuous operation of the fuming furnace.

[0011] Furthermore, the slag formation zone is located 1.5-4.0m from the surface of the molten metal in the furnace through the vertical flue of the fuming furnace, and the temperature of the slag formation zone when no oxidizing atmosphere is injected is 1000-1100℃.

[0012] Furthermore, the injection nozzle is inserted into the vertical flue of the fuming furnace at a distance of 2-2.5m from the surface layer of the molten metal in the molten pool. The angle between the injection nozzle and the side wall of the vertical flue is 45°. The diameter of the injection nozzle is 10cm and the wall thickness is 2cm.

[0013] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: when the distance between the injection nozzle and the surface layer of the molten metal is 2~2.5m, there is no blockage at the injection nozzle, the injection speed is easy to adjust, and the injection atmosphere can be quickly and deeply mixed with the flue gas in the slag zone, so as to achieve the best injection effect.

[0014] Furthermore, three injection nozzles are inserted on each side of the vertical flue of the fuming furnace.

[0015] Furthermore, the residual reducing flue gas volume is 140-150 m³ / h, comprising reducing dust particles and gas. The residual reducing flue gas includes dust particles and gas, with a mass-to-volume ratio of dust particles to gas of (0.2-0.3) g:1 mL. The dust particles comprise 16-18% SnO₂ by mass, 75-78% FeS₂ by mass, and 4-8% ZnS by mass, with the remainder being impurities. The gas comprises 3-6% CO by volume, and [the remaining part is missing from the original text]. 2-5% H2, 70-75% SnS by volume, and 15-20% SO2 by volume, wherein CO and H2 are reducing gases.

[0016] Furthermore, an oxidizing atmosphere with an oxygen content ≥21% Vol is blown into the slagging area using a blower, with a blowing pressure ≥0.2MPa; the molar ratio of the injected oxidizing atmosphere to the total amount of reducing gases CO and H2 in the flue gas is (0.8-1.2):1.

[0017] The beneficial effects of adopting the above-mentioned further technical solution are as follows: An oxidizing atmosphere is injected into the slagging zone, causing it to undergo an exothermic oxidation reaction with the remaining reducing flue gas in the slagging zone. The heat released by the reaction raises the temperature of the slagging zone by 100-150℃, reducing the viscosity of the slag to 40-50% of its original viscosity. The slag with reduced viscosity flows back into the molten pool, thereby reducing the slag protrusion height to below 55cm, promoting uniform slag distribution, reducing the slagging rate to <0.15t / d by 40%, and increasing the upper limit of the total slag amount by 20%-25%.

[0018] Furthermore, the oxidizing atmosphere is oxygen or air. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method for improving slagging in a fuming furnace using residual reducing flue gas, as per the present invention.

[0020] Figure 2 This is a front view of the structure of the vertical flue of the fuming furnace.

[0021] Figure 3 This is a top view of the structure of the vertical flue of the fuming furnace. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0023] A method for improving slagging in a fuming furnace using residual reducing flue gas includes the following steps: Injection ports are added to the slagging zone of the 500t / d fuming furnace's direct-flow flue. When the fuming furnace starts working, an oxidizing atmosphere is continuously injected into the slagging zone, causing the oxidizing atmosphere to react with the remaining reducing flue gas in the slagging zone in an exothermic oxidation reaction. The heat released by the reaction raises the temperature of the slagging zone to 1250-1300℃ until the fuming furnace stops working and the injection of the oxidizing atmosphere stops.

[0024] The slagging zone is located 1.5-4.0 m above the surface of the molten tin in the 1200℃ molten pool, in the direct-flow flue of the fuming furnace. The temperature in the slagging zone before the introduction of an oxidizing atmosphere is 1000-1100℃. The residual reducing flue gas flow rate in the slagging zone is 140-150 m³ / h. This residual reducing flue gas includes particulate matter and gas, with a mass-to-volume ratio of 0.2 g:1 mL. The particulate matter consists of 16% SnO₂, 75% FeS₂, and 4% ZnS by mass, with the remainder being impurities. The gas contains 5% CO and [other components]. The mixture contains 5% H2, 75% SnS (by volume), and 15% SO2 (by volume), where CO and H2 are reducing gases.

[0025] Three injection nozzles are inserted on each side of the vertical flue of the fuming furnace, 2 meters above the surface of the molten metal in the molten pool. The angle between the nozzle and the side wall of the flue is 45°. The nozzle diameter is 10 cm and the wall thickness is 2 cm. An oxidizing atmosphere with an oxygen content ≥21% Vol is blown into the slagging area using the injection nozzles at a pressure of 0.2 MPa. The molar ratio of the injected oxidizing atmosphere to the total amount of reducing gases CO and H2 in the flue gas is 0.8:1. This promotes oxidation and exothermic heating in the slagging area, maintaining a stable temperature between 1250-1300℃, with traces of molten reflux in the slag.

[0026] Without the injection of an oxidizing atmosphere, the viscosity of the slag in the vertical flue of the fuming furnace was 127.33 Pa·s, the slag formation rate was 0.23 t / d, the cleaning cycle was 3 months, the maximum total slag amount was 20.73 t, and the slag protrusion height was 78 cm. In Example 1, the viscosity of the slag in the vertical flue of the fuming furnace was 76.56 Pa·s, the slag formation rate was 0.149 t / d, the cleaning cycle was 167 days, the maximum total slag amount was 24.88 t, and the slag protrusion height was 51 cm. Example 2

[0027] A method for improving slagging in a fuming furnace using residual reducing flue gas includes the following steps: Injection ports are added to the slagging zone of the 540t / d fuming furnace's direct-flow flue. When the fuming furnace starts working, an oxidizing atmosphere is continuously injected into the slagging zone, causing the oxidizing atmosphere to react with the remaining reducing flue gas in the slagging zone in an exothermic oxidation reaction. The heat released by the reaction raises the temperature of the slagging zone to 1250-1300℃ until the fuming furnace stops working and the injection of the oxidizing atmosphere stops.

[0028] The slagging zone is located 1.5-4.0 m above the surface of the molten tin in the 1200℃ molten pool, in the direct-flow flue of the fuming furnace. The temperature in the slagging zone before the introduction of an oxidizing atmosphere is 1000-1100℃. The residual reducing flue gas volume in the slagging zone is 140-150 m³ / h. This residual reducing flue gas includes particulate matter and gas, with a mass-to-volume ratio of 0.3 g:1 mL. The particulate matter consists of 18% SnO₂, 76% FeS₂, and 4% ZnS by mass, with the remainder being impurities. The gas contains 6% CO by volume. The mixture contains 2% H2, 72% SnS (by volume), and 20% SO2 (by volume), with CO and H2 being reducing gases.

[0029] Three injection nozzles are inserted on each side of the vertical flue of the fuming furnace, 2.5m above the surface of the molten metal in the molten pool. The angle between the nozzle and the side wall of the flue is 45°. The nozzle diameter is 10cm and the wall thickness is 2cm. An oxidizing atmosphere with an oxygen content ≥21% Vol is blown into the slagging area using the injection nozzles at a pressure of 0.23MPa. The molar ratio of the injected oxidizing atmosphere to the total amount of reducing gases CO and H2 in the flue gas is 1.2:1. This promotes oxidation and exothermic heating in the slagging area, maintaining a stable temperature between 1250-1300℃, with traces of molten reflux in the slag.

[0030] Without the injection of an oxidizing atmosphere, the viscosity of the slag in the vertical flue of the fuming furnace was 133.59 Pa·s, the slag formation rate was 0.23 t / d, the cleaning cycle was 3 months, the maximum total slag amount was 20.73 t, and the slag protrusion height was 76 cm. In Example 1, the viscosity of the slag in the vertical flue of the fuming furnace was 78.04 Pa·s, the slag formation rate was 0.143 t / d, the cleaning cycle was 180 days, the maximum total slag amount was 25.74 t, and the slag protrusion height was 49 cm.

[0031] Effect Experiment: Compared with Example 1, Comparative Examples 1-13 have some technical parameters adjusted in Table 1. Except for the test parameters of the technical conditions in Table 1, the other steps and parameters are the same.

[0032] Table 1

[0033] Conclusion: Utilizing residual reducing flue gas improves slagging in the fuming furnace, promoting uniform slagging distribution, increasing the upper limit of slagging amount, and reducing the slagging protrusion height to below 55cm, thus enhancing the flue's load-bearing capacity for slagging. The cleaning cycle was extended from the original 3 months to 6 months, reducing the number of cleaning operations, saving manpower and resources, and ensuring continuous production.

[0034] The description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for improving the slagging of a smelter by using residual reducing flue gas, characterized in that, The method comprises the following steps: The slagging area of the direct flue of the fuming furnace is provided with a blowing port, and the oxidizing atmosphere is continuously injected into the slagging area when the fuming furnace is working, so that the oxidizing atmosphere and the residual reducing flue gas in the slagging area have an oxidation exothermic reaction, the reaction releases heat to raise the temperature of the slagging area to 1250-1350℃, and the oxidizing atmosphere injection is stopped until the fuming furnace stops working.

2. The method for improving the slagging of a furnace by using the residual reducing flue gas according to claim 1, characterized in that, The slagging area is located at a position 1.5-4.0 m away from the surface layer of the molten metal liquid of the molten pool of the direct flue of the fuming furnace, and the temperature of the slagging area without the injection of the oxidizing atmosphere is 1000-1100℃.

3. The method for improving slagging in a furnace by using residual reducing flue gas according to claim 1, wherein The blowing port is inserted into the direct flue of the fuming furnace at a position 2-2.5 m away from the surface layer of the molten metal liquid of the molten pool, the included angle between the blowing port and the side wall of the direct flue is 45°, the pipe diameter of the blowing port is 10 cm, and the wall thickness is 2 cm.

4. The method for improving slagging in a combustion furnace using residual reducing flue gas according to claim 1, wherein Three blowing ports are respectively inserted into the two sides of the direct flue of the fuming furnace.

5. The method of claim 1, wherein the method further comprises: adding a reducing agent to the flue gas. The residual reducing flue gas has a wind volume of 140-150 m³ / h, and comprises flue dust particles and gas, and the mass-volume ratio of the flue dust particles and the gas is (0.2-0.3) g:1 mL, wherein the flue dust particles comprise SnO2 with a mass fraction of 16-18%, FeS2 with a mass fraction of 75-78%, ZnS with a mass fraction of 4-8%, and impurities; and the gas comprises CO with a volume fraction of 3-6%, H2 with a volume fraction of 2-5%, SnS with a volume fraction of 70-75%, and SO2 with a volume fraction of 15-20%, wherein CO and H2 are reducing gases.

6. The method for improving the slagging of a furnace by using the residual reducing flue gas according to claim 5, characterized in that, The oxygen content of the oxidizing atmosphere is ≥21%, and the blowing pressure is ≥0.2 MPa; and the molar ratio of the injected oxidizing atmosphere to the total amount of the reducing gases CO and H2 in the flue gas is (0.8-1.2):

1.

7. The method of claim 1, wherein the method further comprises: adding a reducing agent to the flue gas. The oxidizing atmosphere is oxygen or air.

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