System and method for reducing emission of CO in copper smelting flue gas

Abstract

The invention discloses a system and a method for reducing emission of CO in copper smelting flue gas. The emission reduction system for CO in copper smelting flue gas comprises a starting module and an adjusting module, the starting module is used for starting an air draft fan and closing an air supply fan after anode furnace refining is started, so that the concentration of CO in flue gas of a combustion chamber and flue gas of a sulfuric acid plant is increased; and the adjusting module is used for opening an air distribution system to ensure that enough oxygen is contained in the combustion chamber when the temperature of the flue gas in the combustion chamber reaches 650 DEG C or above and the oxygen concentration is lower than 3%. According to the method, CO emission reduction in the refining reduction stage process of the copper smelting anode furnace is achieved through continuous combustion of CO in the dilute oxygen environment.

Description

Technical Field

[0001] The present invention relates to the field of metal smelting, and in particular to a system and method for reducing CO emissions in copper smelting flue gas. Background Art

[0002] During the metal smelting process, the smelting flue gas usually contains a high concentration of carbon monoxide (CO), but the country currently has no clear regulations on CO emission standards. The flue gas to be treated is generally only discharged directly after desulfurization and denitrification treatment. The carbon monoxide in the flue gas is not treated and utilized in a targeted manner, resulting in direct emission of carbon monoxide. However, carbon monoxide is a colorless, odorless, and non-irritating gas that easily combines with hemoglobin to form carboxyhemoglobin, which makes hemoglobin lose its oxygen-carrying capacity and function, causing tissue asphyxiation and death in severe cases; carbon monoxide has toxic effects on tissue cells throughout the body, especially the cerebral cortex. Therefore, the direct emission of carbon monoxide is extremely polluting to the environment.

[0003] In the sulfuric acid production process of copper smelting, when the CO content in the flue gas exceeds 800ppm, it will cause the precipitation of sulfur in the sulfuric acid electrostatic precipitator, seriously affecting the normal operation of the smelting sulfuric acid plant, and then leading to a decrease in production efficiency, and there are also potential environmental safety risks. However, in the reduction and refining process of the copper smelting anode furnace, due to the use of carbon-containing reducing agents, the CO concentration in the smelting flue gas is extremely high. The CO concentration in the flue gas at the anode furnace of a copper smelter can reach up to 30%. Therefore, reducing the CO concentration in copper smelting flue gas is an urgent problem to be solved, but there are almost no reports on reducing the CO concentration in copper smelting flue gas. In the field of steel smelting, direct combustion, adsorption and catalytic oxidation methods have been developed to treat CO in flue gas, but these methods are either relatively costly or cannot be adapted to existing copper smelting processes. Therefore, it is urgent to develop a method that can solve the above technical problems. Summary of the invention

[0004] The first object of the present invention is to provide a system for reducing CO emissions in copper smelting flue gas; the second object is to provide a method for reducing CO emissions in copper smelting flue gas.

[0005] The first object of the present invention is achieved in that the CO emission reduction system in copper smelting flue gas comprises a start-up module and an adjustment module, wherein: The start-up module is used to start the exhaust fan and shut down the supply fan after the anode furnace refining starts, so as to increase the CO concentration in the flue gas in the combustion chamber and the flue gas to the sulfuric acid plant; The adjustment module is used to open the air distribution system to ensure that there is enough oxygen in the combustion chamber when the flue gas temperature in the combustion chamber reaches above 650°C and the oxygen concentration is lower than 3%.

[0006] The second object of the present invention is achieved by comprising: During the refining process of the copper smelting anode furnace, the exhaust fan is used to introduce the smelting flue gas in the refining reduction stage of the copper smelting anode furnace into the combustion chamber through the flue gas duct, the flue gas temperature in the combustion chamber is monitored by a thermocouple, and the content and composition of the main gases in the combustion chamber are analyzed by a flue gas analyzer; In the initial stage of flue gas treatment, the air distribution system is turned off to make the flue gas temperature in the combustion chamber quickly reach the ignitable point of CO to ensure that carbon monoxide is in a complete combustion state. When the flue gas temperature reaches above 600℃, it can be observed that the flue gas in the combustion chamber is in a red temperature state, and the concentration of O2 measured by the flue gas analyzer continues to decrease. When the flue gas temperature reaches above 650℃ and the oxygen concentration measured by the flue gas analyzer is lower than 3%, in order to ensure the continuous combustion of CO in the flue gas, the air distribution system needs to be opened at this time to introduce process air into the combustion chamber to ensure the sustainability of CO combustion.

[0007] The CO emission reduction system of the present invention includes: a flue gas duct, a combustion chamber, an air distribution system, an exhaust system, and a monitoring and analysis system. The combustion chamber is a place where the copper smelting flue gas undergoes combustion reaction; the air distribution system provides oxygen for the continuous combustion of the flue gas and can dilute the CO concentration in the flue gas; the exhaust system guides the flow of the flue gas; the monitoring and analysis system measures the flue gas temperature through a thermocouple and analyzes the flue gas composition through a flue gas analyzer.

[0008] In the copper smelting anode furnace refining process, the exhaust fan is used to introduce the smelting flue gas in the copper smelting anode furnace refining reduction stage into the combustion chamber through the flue gas duct. The flue gas temperature in the combustion chamber is monitored by a thermocouple, and the content and composition of the main gases in the combustion chamber are analyzed by a flue gas analyzer, including: CO, CO2, SO2, O2, etc.

[0009] In the initial stage of flue gas treatment, the air distribution system is turned off to make the flue gas temperature in the combustion chamber quickly reach the ignitable point of CO to ensure that carbon monoxide is in a complete combustion state. When the flue gas temperature reaches above 600°C, it can be observed that the flue gas in the combustion chamber is in a red temperature state, and the concentration of O2 measured by the flue gas analyzer continues to decrease. When the flue gas temperature reaches above 650°C and the oxygen concentration measured by the flue gas analyzer is lower than 3%, in order to ensure the continuous combustion of CO in the flue gas, the air distribution system needs to be opened at this time to introduce process air into the combustion chamber to ensure the sustainability of CO combustion. Through the continuous combustion of CO in a dilute oxygen environment, CO emissions can be reduced during the refining and reduction stage of the copper smelting anode furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Schematic diagram of the CO emission reduction process and system of the present invention; Figure 2This is a monitoring schematic diagram of Example 1 of the present invention; Figure 3 This is a monitoring schematic diagram of Comparative Example 1. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0012] The CO emission reduction system in copper smelting flue gas of the present invention comprises a start-up module and an adjustment module, wherein: The start-up module is used to start the exhaust fan and shut down the supply fan after the anode furnace refining starts, so as to increase the CO concentration in the flue gas in the combustion chamber and the flue gas to the sulfuric acid plant; The adjustment module is used to open the air distribution system to ensure that there is enough oxygen in the combustion chamber when the flue gas temperature in the combustion chamber reaches above 650°C and the oxygen concentration is lower than 3%.

[0013] The combustion chamber is a place where the copper smelting flue gas undergoes combustion reactions. The flue gas duct, combustion chamber, air distribution system, exhaust system, monitoring and analysis system are respectively connected to the combustion chamber; the air distribution system provides oxygen for the continuous combustion of the flue gas and at the same time adjusts the CO concentration in the wet flue gas; the exhaust system guides the flow direction of the flue gas; the detection and analysis system measures the flue gas temperature through a thermocouple, and analyzes the flue gas composition through a flue gas analyzer and provides it to the adjustment module.

[0014] The method for reducing CO emissions in copper smelting flue gas of the present invention comprises: During the refining process of the copper smelting anode furnace, the exhaust fan is used to introduce the smelting flue gas in the refining reduction stage of the copper smelting anode furnace into the combustion chamber through the flue gas duct, the flue gas temperature in the combustion chamber is monitored by a thermocouple, and the content and composition of the main gases in the combustion chamber are analyzed by a flue gas analyzer; In the initial stage of flue gas treatment, the air distribution system is turned off to make the flue gas temperature in the combustion chamber quickly reach the ignitable point of CO to ensure that carbon monoxide is in a complete combustion state. When the flue gas temperature reaches above 600℃, it can be observed that the flue gas in the combustion chamber is in a red temperature state, and the concentration of O2 measured by the flue gas analyzer continues to decrease. When the flue gas temperature reaches above 650℃ and the oxygen concentration measured by the flue gas analyzer is lower than 3%, in order to ensure the continuous combustion of CO in the flue gas, the air distribution system needs to be opened at this time to introduce process air into the combustion chamber to ensure the sustainability of CO combustion.

[0015] The main gases are CO, CO2, SO2 and O2.

[0016] The sustainability of CO combustion is ensured by continuous combustion in a dilute oxygen environment.

[0017] The present invention is further described below with specific implementation cases: Example 1 In the refining and reduction stage of the copper smelting anode furnace, the amount of copper liquid is about 160,000 kg, the reducing agent feeding speed is 12-14 kg / min, and the process wind speed of the reducing agent is ~250 Nm 3 / h, the flue gas volume entering the combustion chamber is 3000Nm 3 / h, the air supply volume of the combustion chamber is about 1600Nm 3 / h.

[0018] After the anode furnace refining begins, the exhaust fan is turned on and the air supply fan is turned off. The CO concentration in the flue gas in the combustion chamber and the flue gas to the sulfuric acid plant continues to increase, and the flue gas temperature in the combustion chamber rises rapidly. The CO concentration in the flue gas in the combustion chamber can reach 100,000 ppm, and the CO concentration detected in the flue gas to the sulfuric acid plant is 1450 ppm. When the flue gas temperature in the combustion chamber reaches 650°C, an obvious flame can be observed in the combustion chamber, but the O2 concentration in the combustion chamber drops rapidly at this time. In order to ensure the continuous combustion of flue gas CO in the combustion chamber, the air supply system needs to be turned on to ensure that there is enough oxygen in the combustion chamber. After CO starts to burn, the CO content in the flue gas from the copper smelting anode furnace refining reduction stage to the sulfuric acid plant is less than 800 ppm, and the CO emission reduction effect is obvious.

[0019] Comparative Example 1 During the refining and reduction stage of the copper smelting anode furnace, the amount of molten copper is about 160,000 kg, the reducing agent feeding rate is 12-14 kg / min, the process wind speed of the reducing agent injection is ~250 Nm3 / h, the flue gas volume entering the combustion chamber is 3000 Nm3 / h, and the combustion chamber air supply volume is about 1600 Nm3 / h.

[0020] After the anode furnace refining begins, turn on the exhaust fan and turn on the air distribution system to supply air to the combustion chamber. In the early stage of reduction, since most of the reducing agent participates in the oxidation-reduction process, the generated CO is relatively small. After dilution by the combustion chamber air distribution, the CO concentration in the flue gas of the sulfuric acid plant is less than 800ppm. However, as the reduction process proceeds, in order to ensure that the reduction process is completed within the predetermined time, the amount of reducing agent fed will gradually increase, and due to the reduction of copper oxides, the utilization efficiency of the reducing agent is greatly reduced, the reaction is not sufficient, and a large amount of CO is generated. In addition, due to the low temperature of the combustion chamber, the ignition point of CO is not reached, and the dilution effect of the CO concentration by air distribution is limited, so the CO concentration in the flue gas of the sulfuric acid plant exceeds 800ppm.

[0021] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A system for reducing CO in copper smelting flue gas, characterized in that: The CO emission reduction system in copper smelting flue gas comprises a start-up module and an adjustment module, wherein: The start-up module is used to start the exhaust fan and shut down the supply fan after the anode furnace refining starts, so as to increase the CO concentration in the flue gas in the combustion chamber and the flue gas to the sulfuric acid plant; The adjustment module is used to open the air distribution system to ensure that there is enough oxygen in the combustion chamber when the flue gas temperature in the combustion chamber reaches above 650°C and the oxygen concentration is lower than 3%.

2. The system for reducing CO in copper smelting flue gas according to claim 1, characterized in that: The combustion chamber is a place where the copper smelting flue gas undergoes combustion reactions. The flue gas duct, combustion chamber, air distribution system, exhaust system, monitoring and analysis system are respectively connected to the combustion chamber; the air distribution system provides oxygen for the continuous combustion of the flue gas and at the same time adjusts the CO concentration in the wet flue gas; the exhaust system guides the flow direction of the flue gas; the detection and analysis system measures the flue gas temperature through a thermocouple, and analyzes the flue gas composition through a flue gas analyzer and provides it to the adjustment module.

3. A method for reducing CO emissions in copper smelting flue gas, characterized in that: The method for reducing CO emissions in copper smelting flue gas comprises: During the refining process of the copper smelting anode furnace, the exhaust fan is used to introduce the smelting flue gas in the refining reduction stage of the copper smelting anode furnace into the combustion chamber through the flue gas duct, the flue gas temperature in the combustion chamber is monitored by a thermocouple, and the content and composition of the main gases in the combustion chamber are analyzed by a flue gas analyzer; In the initial stage of flue gas treatment, the air distribution system is turned off to make the flue gas temperature in the combustion chamber quickly reach the ignitable point of CO to ensure that carbon monoxide is in a complete combustion state. When the flue gas temperature reaches above 600℃, it can be observed that the flue gas in the combustion chamber is in a red temperature state, and the concentration of O2 measured by the flue gas analyzer continues to decrease. When the flue gas temperature reaches above 650℃ and the oxygen concentration measured by the flue gas analyzer is lower than 3%, in order to ensure the continuous combustion of CO in the flue gas, the air distribution system needs to be opened at this time to introduce process air into the combustion chamber to ensure the sustainability of CO combustion.

4. The emission reduction method according to claim 4, characterized in that: The main gases are CO, CO2, SO2 and O2.

5. The emission reduction method according to claim 4, characterized in that: The sustainability of CO combustion is ensured by continuous combustion in a dilute oxygen environment.

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