A method for regulating the separation of arsenic and valuable metals in smelting flue gas

Abstract

The application relates to a method for regulating separation of arsenic and valuable metals in smelting flue gas, and belongs to the field of clean production technology. After active carbon and chalcopyrite powder are mixed into the smelting flue gas, on one hand, oxygen in the flue gas is consumed to inhibit the formation of arsenate, and on the other hand, active sulfur components are provided to regulate the conversion of metal oxides into sulfates, and arsenic is volatilized in the form of As2O3, so that the target of separating arsenic from valuable metals is achieved. The application inhibits the formation of arsenate in the flue gas, improves the efficiency of dry condensation collection of As2O3 from the flue gas, and reduces the formation of arsenic-containing dust.

Description

Technical Field

[0001] This invention relates to the field of clean production technology, and in particular to a method for controlling the separation of arsenic and valuable metals in smelting flue gas. Background Technology

[0002] Arsenic is often found in various non-ferrous metal minerals, and due to its volatility, it inevitably enters the smelting system during the smelting process. Arsenic in flue gas affects the catalytic conversion system of subsequent acid production sections; moreover, as a significant source of atmospheric arsenic pollutants, its effective purification is crucial for air pollution control and the green development of the smelting industry.

[0003] Currently, the dry quenching arsenic recovery process, due to its short process flow, high removal and recovery efficiency, and direct arsenic recovery, has been adopted by smelting enterprises for flue gas arsenic removal. In the dry process, smelting flue gas from the furnace mouth recovers waste heat through a waste heat boiler, reducing the temperature to approximately 380-400℃. Subsequently, most of the particulate matter is removed by an electrostatic precipitator. Then, the flue gas, after condensation in a quenching tower, is quenched to 130-150℃, achieving rapid arsenic condensation to form particulate matter, which is finally collected as pure As2O3 by a bag filter. From a resource utilization perspective, the dry arsenic recovery process has potential advantages. However, the arsenate formed by the reaction of arsenic with valuable metals during the gradual condensation process of the flue gas inhibits the efficient arsenic recovery of the dry process. In addition, the generation of a large amount of arsenic-containing dust increases the additional processing costs for smelting enterprises. Currently, CN104451167 A discloses a method that uses spray, air, and other cooling methods to perform multi-stage cooling of arsenic-containing flue gas to condense the arsenic in the flue gas, followed by arsenic recovery using a bag filter. CN103961790 B discloses a method that uses small droplets generated by airflow and liquid flow to spray into high-temperature arsenic-containing flue gas to cool the flue gas, causing As2O3 to condense into solid particles, which are then collected by an arsenic collection system. CN108187436 B discloses a method that uses a high-temperature resistant ceramic filter, a circulating fluidized bed as a quenching device, and solid particulate media to rapidly cool the high-temperature arsenic-containing flue gas, converting gaseous arsenic into solid arsenic for recovery.

[0004] These methods focus on the condensation and capture of gaseous arsenic. However, during flue gas condensation, components such as copper, lead, and zinc react with As₂O₃ to form arsenates, thus failing to solve the problem of separating arsenic from valuable metals. Therefore, suppressing the formation of arsenates in flue gas through phase regulation is key to achieving the separation and recovery of arsenic from valuable metals. Summary of the Invention

[0005] To address the problem of arsenic being difficult to separate due to the formation of arsenates in existing dry arsenic recovery technologies, this invention proposes a method for regulating the phase transformation of arsenic with metal oxide minerals in smelting flue gas. This method aims to suppress the formation of arsenates, thereby achieving the separation of As2O3 from valuable metals. After separation, the arsenic is captured in the form of As2O3 by existing dry arsenic recovery equipment, while the metal is directly returned to the smelting system in the form of sulfates or oxides, significantly reducing the generation of arsenic-containing flue gas.

[0006] A method for controlling the separation of arsenic and valuable metals in smelting flue gas includes: simultaneously adding activated carbon and chalcopyrite powder to the smelting flue gas to control the phase transformation of arsenic and metal oxides and inhibit the formation of arsenate, wherein the ratio of activated carbon to chalcopyrite powder is 2:1 to 1:5.

[0007] It should be noted that the smelting flue gas involved in this invention can be regulated by the method described in this invention as long as it contains valuable metals and arsenic. For example, it can be copper smelting flue gas, lead smelting flue gas, zinc smelting flue gas, etc.

[0008] The simultaneous addition of activated carbon and chalcopyrite powder can also be understood as adding a mixed powder of activated carbon and chalcopyrite, that is, mixing activated carbon and chalcopyrite powder evenly before adding it to the smelting flue gas.

[0009] Preferably, the ratio of activated carbon to chalcopyrite powder is 1:3 to 1:5.

[0010] Preferably, the particle size of the activated carbon and chalcopyrite mixed powder is <0.15 mm.

[0011] Preferably, the amount of activated carbon and chalcopyrite powder added is 10-60% of the total mass of arsenic and metal oxides.

[0012] Preferably, the amount of activated carbon and chalcopyrite powder added is 30-60% of the total mass of arsenic and metal oxides.

[0013] Preferably, the reaction temperature is 600~800℃. The reaction temperature can be understood as the temperature at which the smelting flue gas reacts with the mixed powder of activated carbon and chalcopyrite. In actual production, the temperature of the directly emitted smelting flue gas is above 1000℃. After waste heat recovery, the temperature is adjusted to below 800℃, so that it can directly react with the mixed powder of activated carbon and chalcopyrite, thereby achieving phase control of arsenic.

[0014] Preferably, the reaction temperature is 600~700℃.

[0015] During the condensation of copper smelting flue gas, metal oxides react with SO2, O2, and As2O3 to form sulfates or arsenates, which coexist stably. Therefore, enhancing the conversion of metal oxides to sulfates is an effective way to inhibit the formation of arsenates.

[0016] The key technology of this invention lies in utilizing a mixture of activated carbon and chalcopyrite powder to react with metal oxides in flue gas under appropriate temperature conditions, thereby controlling the phase transformation process of the metal oxides and As₂O₃ to inhibit arsenate formation. Without the addition of the mixed activated carbon and chalcopyrite powder, the arsenate formation reaction is as follows:

[0017]

[0018] As can be seen from the above, the presence of metal oxides and oxygen is a necessary condition for the formation of arsenates. Therefore, regulating the phase transformation of metal oxides and reducing the oxygen content in the atmosphere are key to inhibiting the formation of arsenates.

[0019] In this invention, activated carbon, on the one hand, consumes oxygen in the smelting flue gas by forming CO2, and on the other hand, as a reducing component, reduces AsO5 to As2O3 to prevent further arsenate formation. Chalcopyrite, as a sulfide, consumes oxygen in the system through oxidation and provides a sulfur source to enhance the conversion of metal oxides to sulfates, thus inhibiting further reaction with As2O3, thereby achieving the goal of suppressing arsenate formation. Arsenic will then enter the next process in the form of gaseous As2O3. In a smelting atmosphere of 600–800°C, the main reactions that inhibit arsenate formation in the mixed powder of activated carbon and chalcopyrite are as follows:

[0020]

[0021] As can be seen from the above reaction, copper is mainly converted into stable metal sulfates, while iron is converted into oxides and sulfates, thereby inhibiting the formation of arsenates.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This invention regulates the phase composition of arsenic and metal oxides in copper smelting flue gas by using a mixture of activated carbon and chalcopyrite powder, inhibiting the formation of arsenates and achieving the separation of arsenic from valuable metals in copper smelting flue gas. Combined with existing dry arsenic removal equipment, it can significantly improve the arsenic recovery rate and reduce the generation of arsenic-containing dust. Attached Figure Description

[0024] Figure 1 This is a diagram showing the separation effect of arsenic and valuable metals under different dosages of activated carbon and chalcopyrite in Example 1.

[0025] Figure 2 This is a diagram showing the separation effect of arsenic and valuable metals under different ratios of activated carbon and chalcopyrite in Example 2.

[0026] Figure 3 This is a graph showing the separation effect of arsenic and valuable metals at different temperatures in Example 3;

[0027] Figure 4 This is a diagram showing the separation effect of arsenic and valuable metals under different atmospheres in Example 4;

[0028] Figure 5 This is a graph showing the separation effect of arsenic and valuable metals under different O2 and SO2 concentrations in Example 4;

[0029] Figure 6 This is a comparison chart showing the effect of activated carbon and chalcopyrite mixed powder used in this invention on the separation of arsenic and valuable metals in flue gas under the same dosage, temperature and atmosphere. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to specific embodiments and accompanying drawings. It should be noted that the reagents, raw materials, instruments, and equipment involved in the present invention are all commercially available products.

[0031] Example 1: Controlling the separation of arsenic and valuable metals in smelting flue gas under different dosages of activated carbon and chalcopyrite. In this example, the mass ratio of CuO to As₂O₃ was 2:1, and the gaseous components in the constant smelting flue gas were 20% O₂, 25% SO₂, 10% CO₂, and 45% N₂. The reaction was carried out at 600℃ for 60 min, and the reaction tail gas was discharged after two stages of washing. Figure 1 As shown, with the increase of the dosage of the mixed powder of activated carbon and chalcopyrite (10%~60%), when the ratio of activated carbon to chalcopyrite is 2:1, the separation rate first increases and then decreases, reaching a maximum separation rate of 77.76% at a dosage of 20%. However, when the ratio of activated carbon to chalcopyrite is 1:1, 1:2, and 1:3, the separation rate of arsenic and valuable metals all show an increasing trend with increasing dosage. The highest separation rate is 85.15% when the ratio of activated carbon to chalcopyrite is 1:3 and the dosage is 60%.

[0032] Example 2: Controlling the separation of arsenic and valuable metals in smelting flue gas under different activated carbon and chalcopyrite ratios. In this example, the mass ratio of CuO to As₂O₃ was 2:1, the total dosage of activated carbon and chalcopyrite was 60%, and the gaseous components in the constant smelting flue gas were 20% O₂, 25% SO₂, 10% CO₂, and 45% N₂. The reaction was carried out at 600℃ for 60 minutes, and the reaction tail gas was discharged after two stages of washing. Figure 2 As shown, with the increase of the ratio of activated carbon and chalcopyrite mixed powder (2:1 to 1:5), the separation rate of arsenic and valuable metals both showed an increasing trend. When the ratio of activated carbon and chalcopyrite was 1:5, the highest separation rate reached 88.32%.

[0033] Example 3: Study on the regulation of arsenic separation from valuable metals by a mixture of activated carbon and chalcopyrite powder in smelting flue gas at different temperatures. The gaseous components of the constant smelting flue gas were 20% O2, 25% SO2, 10% CO2, and 45% N2. The mass ratio of CuO to As2O3 was 2:1, the ratio of activated carbon to chalcopyrite was 1:3, the total dosage was 30%, the reaction time was 60 min, and the tail gas was discharged after two stages of washing. Figure 3 As shown, the separation rate of arsenic from valuable metals increases with increasing temperature in the range of 600–700 °C, reaching a peak at 700 °C (84.12%). When the temperature is further increased to 800 °C, the separation rate of arsenic from valuable metals decreases to 81.62%.

[0034] Example 4: Study on the regulation of arsenic separation from valuable metals by a mixture of activated carbon and chalcopyrite powder in different smelting flue gases. Specifically, the mixture of activated carbon and chalcopyrite powder was used to inhibit the reaction between As₂O₃ and metal oxides in flue gases at high temperatures and under different atmospheres to separate arsenic. In this example, the mass ratio of CuO to As₂O₃ was 2:1, the ratio of activated carbon to chalcopyrite powder was 1:3, the total dosage was 30%, the reaction was carried out at 600℃ for 60 min, and the reaction tail gas was discharged after two-stage washing. N₂ was used as the equilibrium gas in the reaction atmosphere, and the separation effect of arsenic from valuable metals was determined under different compositions and concentrations of O₂, SO₂, and CO₂ atmospheres.

[0035] like Figure 4 As shown, different atmospheric conditions affected the ability of activated carbon and chalcopyrite mixed powder to control the separation of arsenic from valuable metals. N2 (100% N2), SO2 (25% SO2 + 75% N2), and CO2 (10% CO2 + 90% N2) atmospheres were favorable for controlling the separation of arsenic from valuable metals by activated carbon and chalcopyrite mixed powder, with separation rates of 99.65%, 98.58%, and 97.99%, respectively. However, the addition of O2 inhibited the control of arsenic separation by activated carbon and chalcopyrite. The separation rates of the three oxygen-containing atmospheres (20% O2 + 80% N2, 20% O2 + 25% SO2 + 55% N2, and 20% O2 + 25% SO2 + 10% CO2 + 45% N2) were 78.35%, 83.92%, and 82.09%, respectively.

[0036] like Figure 5 As shown in Figure a, the equilibrium gas composition of the constant smelting flue gas is 25% SO2, 10% CO2, and N2. The separation rate of arsenic and valuable metals regulated by the mixed powder of activated carbon and chalcopyrite significantly decreases with increasing O2 concentration (0%~50%). Without O2, the separation rate of arsenic and valuable metals is 96.96%. At a 50% O2 concentration, the separation rate decreases to 76.64%.

[0037] like Figure 5As shown in b, the constant smelting flue gas composition of 20% O2, 10% CO2, and N2 serves as the equilibrium gas. The separation rate of arsenic and valuable metals, regulated by a mixture of activated carbon and chalcopyrite powder, increases with increasing SO2 concentration (0%~55%). Without SO2, the separation rate is 79.25%. At a SO2 concentration of 55%, the separation rate increases to 87.34%.

[0038] Comparative Example 1: Activated carbon was used to regulate and separate arsenic from valuable metals in copper smelting flue gas. The dosage was 30%, the mass ratio of CuO to As₂O₃ was 2:1, and other reaction conditions were the same as in Example 2. Figure 6 As shown, the separation rate of arsenic and copper in flue gas was 82.09% when the mixed powder of activated carbon and chalcopyrite (mass ratio 1:3, total addition 30%) was higher than that of pure activated carbon (56.89%). The mixed powder of activated carbon and chalcopyrite is significantly better than that of pure activated carbon.

[0039] Comparative Example 2: Chalcopyrite was used to control and separate arsenic from valuable metals in copper smelting flue gas. The dosage was 30%, the mass ratio of CuO to As₂O₃ was 2:1, and other reaction conditions were the same as in Example 2. Figure 6 As shown, the separation rate of arsenic and valuable copper in flue gas was 82.09% when the mixed powder of activated carbon and chalcopyrite (mass ratio 1:3, total addition 30%) was controlled, which was higher than the 59.60% of pure chalcopyrite. The mixed powder of activated carbon and chalcopyrite was significantly better than pure chalcopyrite.

[0040] This invention verifies, through experiments simulating smelting flue gas, that a mixture of activated carbon and chalcopyrite powder can regulate the phase composition of arsenic in smelting flue gas and inhibit the formation of arsenate.

[0041] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling the separation of arsenic and valuable metals in smelting flue gas, characterized in that, include: Activated carbon and chalcopyrite powder are added simultaneously to smelting flue gas for phase regulation of arsenic and metal oxides to inhibit the formation of arsenate. The amount of activated carbon and chalcopyrite powder added is 10-60% of the total mass of arsenic and metal oxides; the ratio of activated carbon to chalcopyrite powder is 2:1 to 1:5; and the reaction temperature is 600-800℃.

2. The method for regulating the separation of arsenic and valuable metals in smelting flue gas according to claim 1, characterized in that, A mixture of activated carbon and chalcopyrite powder is added to smelting flue gas.

3. The method for controlling the separation of arsenic and valuable metals in smelting flue gas according to any one of claims 1 or 2, characterized in that, The smelting flue gas includes any one of copper smelting flue gas, lead smelting flue gas, and zinc smelting flue gas.

4. The method for regulating the separation of arsenic and valuable metals in smelting flue gas according to claim 1, characterized in that, The ratio of activated carbon to chalcopyrite powder is 1:3 to 1:

5.

5. The method for regulating the separation of arsenic and valuable metals in smelting flue gas according to claim 1, characterized in that, The total amount of activated carbon and chalcopyrite powder added is 30-60% of the total mass of arsenic and metal oxides.

6. The method for controlling the separation of arsenic and valuable metals in smelting flue gas according to any one of claims 1 or 2, characterized in that, The particle size of the activated carbon and chalcopyrite powder is <0.15 mm.

7. The method for regulating the separation of arsenic and valuable metals in smelting flue gas according to claim 1, characterized in that, The reaction temperature is 600~700℃.

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