A high-temperature demercuration agent for metal copper sulfide, preparation method and application thereof

Abstract

The present invention discloses a high-temperature mercury removal agent of copper sulfide, a preparation method thereof and an application thereof. The mercury removal agent comprises a copper salt solution, a sulfur ion-containing solution and CuCl2·2H2O. The preparation method of the above mercury removal agent is specifically as follows: the copper salt solution and the sulfur ion-containing solution are mixed and stirred, reacted, aged, washed and dried to obtain CuS, and then mixed and ground with a certain amount of CuCl2·2H2O and calcined at a high temperature, and further ground to obtain a CuS-Cl mercury removal agent. The present invention solves the problem of poor high-temperature mercury removal performance of traditional metal sulfides. The preparation method is simple, the large-scale preparation cost is low, and it can be directly applied to the purification of high-temperature and high-concentration mercury-containing waste gas in smelting, reducing the transformation cost of the flue gas purification system.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental pollution prevention and purification, and specifically relates to a high-temperature demercuration agent for metallic copper sulfide, a preparation method and application thereof. Background Art

[0002] The non-ferrous metal smelting industry is one of the main sources of atmospheric mercury pollution. The smelting flue gas containing high concentrations of SO2 and Hg enters the acid production system after high-temperature electrostatic precipitator. The flue gas after acid production is discharged after desulfurization and demisting. The most economical and effective technical means is to use jet adsorption coupled electrostatic precipitator to achieve the coordinated removal of mercury. The key is the demercuration material. At present, the most mature Hg 0 Pollution removal technology is activated carbon adsorption technology. However, the limitations of activated carbon itself significantly restrict the application prospects of this technology, including but not limited to: low mercury adsorption capacity, poor product stability, and high operating costs. In recent years, metal sulfides have been considered as an ideal alternative to activated carbon, which can achieve more economical and environmentally friendly removal of anthropogenic mercury pollution. The main mechanism is: the sulfur ions in the metal sulfide can react with sulfur-philic Hg 0 Combined with Hg 0 Converted into HgS which exists stably in nature. However, in the prior art, the temperature of non-ferrous smelting flue gas before entering the electrostatic precipitator is relatively high, usually greater than 200°C, and the traditional metal sulfide has poor high-temperature mercury removal performance. Therefore, the development of highly efficient sulfur-resistant mercury removal materials under high temperature conditions is of great significance for the treatment of mercury in non-ferrous smelting flue gas. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a high-temperature demercuration agent for copper sulfide, a preparation method and an application thereof in view of the shortcomings of the above prior art, thereby solving the problem of poor high-temperature demercuration performance of traditional metal sulfides. The material preparation method of the present invention is simple, the large-scale preparation cost is low, the demercuration temperature window is widened, and the material can be directly applied to the purification of high-temperature and high-concentration mercury-containing waste gas from smelting, thereby reducing the cost of modifying the flue gas purification system.

[0004] The technical solution of the present invention to solve the above technical problems is: a method for preparing a high-temperature demercuration agent for metal copper sulfide, wherein the demercuration agent comprises a copper salt solution, a sulfur ion solution and CuCl2·2H2O, and the molar ratio of the three is 1:1:0.01-0.1.

[0005] The preparation method of the mercury removal agent is specifically as follows: a copper salt solution and a sulfur ion solution are mixed and stirred, and CuS is obtained after reaction aging, washing, and drying. The CuS is then mixed and ground with a certain amount of CuCl2·2H2O, calcined at high temperature, and further ground to obtain a CuS-Cl mercury removal agent.

[0006] The present invention further defines the scheme:

[0007] Preferably, the copper salt is one or more of copper nitrate, copper chloride, copper sulfate and copper acetate.

[0008] Preferably, the sulfur ion solution is one or a mixed solution of Na2S, thiourea, ammonium sulfide and potassium sulfide.

[0009] Preferably, the molar ratio of the metal copper ions to the sulfur ions in the sulfur-containing solution is 1:1, stirring is performed at room temperature for 1-3 hours, and then aging is performed for 2-3 hours.

[0010] Preferably, the obtained precipitate is placed in a drying oven at 50-70° C. and dried for 12-24 hours.

[0011] Preferably, the CuS and CuCl2·2H2O are ground for 20-30 min and then calcined in a muffle furnace for 1-3 h.

[0012] Preferably, a high-temperature demercuration agent of copper sulfide is used to treat high-concentration mercury-containing waste gas. The CuS-Cl demercuration agent is injected into the air inlet flue of the high-temperature electrostatic precipitator through an injection system. The residence time is 0.5-1s. The reacted demercuration agent is mixed with roasted sand and enters the leaching process.

[0013] The beneficial effects of the present invention are:

[0014] (1) The mercury adsorption performance is improved by a simple modification method, which solves the problem of poor high-temperature mercury removal performance of traditional metal sulfides. The material prepared by the present invention is not only suitable for mercury removal under low-temperature environment, but also has good performance under high-temperature conditions, which broadens the mercury removal temperature window. In addition, the material has good mercury removal efficiency in a wide temperature window, which is more in line with actual application conditions and reduces the actual use cost.

[0015] (2) The preparation method of the mercury removal agent of the present invention is simple, the large-scale preparation cost is low, and there is no secondary pollution problem when using the mercury removal agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the CuS-Cl in Example 1 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 SEM images of

[0017] Figure 2 CuS, CuS-Cl in Example 1 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 XRD spectrum of

[0018] Figure 3 is the CuS-Cl in Example 10.1 , CuS-Cl 0.05 , CuS-Cl 0.01 TG diagram;

[0019] Figure 4 CuS, CuS-Cl in Example 1 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 Mercury removal efficiency diagram at 50℃, 100℃, and 200℃ respectively;

[0020] Figure 5 is the CuS-Cl in Example 1 0.05 Mercury removal rate diagram under different temperature conditions;

[0021] Figure 6 is the CuS-Cl in Example 1 0.05 Mercury removal efficiency diagram under different flue gas components;

[0022] Figure 7 is the CuS-Cl in Example 1 0.05 Mercury removal rate diagram at different SO2 concentrations;

[0023] Figure 8 is the CuS-Cl in Example 1 0.05 XPS spectra before and after the reaction;

[0024] Fig. 9 is the CuS-Cl in Example 1 0.05 Hg-TPD diagrams of reactions at 100°C, 150°C, and 200°C;

[0025] Fig.10 is the CuS-Cl in Example 1 0.05 Diagram of the mercury removal mechanism. DETAILED DESCRIPTION

[0026] Example 1

[0027] This embodiment provides a method for preparing a high-temperature demercuration agent for copper sulfide. 0.08 mol of Cu(NO3)2·3H2O and 0.08 mol of Na2S are dissolved in 80 mL of H2O, respectively. Then, the Na2S solution is added dropwise to the Cu(NO3)2·3H2O solution, and the mixture is stirred vigorously for 2 h on a magnetic stirrer. Then, the mixture is aged for 2 h, washed several times by centrifugation with deionized water, and the resulting precipitate is placed in a 60°C drying oven and dried overnight for 12 h. The resulting product is collected and recorded as CuS. A certain amount of CuS and CuCl2·2H2O are placed in a mortar, ground for 20 min, and then the solid is transferred to a crucible. Then, the solid is calcined in a muffle furnace at 400°C for 2 h, and the sample is taken out and ground in a mortar to collect the sample CuS-Cl as a demercuration agent. The molar ratios of the CuS and CuCl2·2H2O samples are 1:0.1, 1:0.05, and 1:0.01, respectively, and the samples are named CuS-Cl. 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 .

[0028] The above samples were analyzed by some characterization methods, such as XRD, SEM, BET, TG, XPS, etc. At the same time, the mercury removal ability of the material under various conditions was deeply explained and illustrated using the mercury removal performance evaluation system; the CuS-Cl 0.05 The mechanism of mercury removal is explained in depth, specifically:

[0029] Morphology analysis

[0030] The sample CuS-Cl prepared in the above embodiment was measured by field emission scanning electron microscopy. 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 Analyze the morphology of Figure 1 It can be seen from the figures that the three Cl-doped CuS exhibit layered structures. 0.1 and CuS-Cl 0.01 It shows large block aggregation and the overall size is larger, while CuS-Cl 0.05 It shows more pores, which are more dispersed and smaller in size, which may be beneficial to Hg 0 The adsorption Figure 1 CuS-Cl was determined in 0.05 From the energy spectrum, we can see that Cu and S elements account for the majority of the material, and it contains a small amount of Cl. Similarly, by performing a Mapping element scan on it, we can also observe the presence of these three elements, and their distribution is even.

[0031] Surface area analysis

[0032] The prepared CuS, CuS-Cl 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 The specific surface area, pore size and pore volume were analyzed. From the data in Table 1, it can be seen that after the introduction of Cl, the specific surface area of ​​the material decreased. When the introduction ratio of Cl was 0.05, the material had a higher pore volume and pore size. It is speculated that the introduction of Cl had a certain erosion effect on the morphology of CuS, which increased the pore volume and pore size, thereby promoting the Hg 0 adsorption conversion.

[0033] Table 1

[0034]

[0035] X-ray diffraction analysis was performed on a series of prepared materials, and the generated spectra were as follows Figure 2 As shown in the figure, the CuS synthesized by the coprecipitation method exhibits a characteristic peak with a JCPDS card number of 06-0464, indicating that CuS was successfully synthesized. After the gradual introduction of Cl, the peak position shifted, indicating that Cl successfully entered the CuS lattice at this time. It can also be observed that the peak intensity weakened after the introduction of Cl, and it is speculated that there may be some defects at this time. When the Cl ratio is 0.05, the peak of the material is weak overall, and it is speculated that there are the most defects at this time, which is consistent with the data in BET.

[0036] Structural analysis

[0037] For the prepared CuS, CuS-Cl 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 X-ray diffraction analysis was performed, and the generated spectrum 2 is shown. The CuS synthesized by the co-precipitation method showed a characteristic peak with JCPDS card number 06-0464, indicating that CuS was successfully synthesized. After the gradual introduction of Cl, the peak position shifted, indicating that Cl successfully entered the CuS lattice at this time. It can also be observed that the peak intensity weakened after the introduction of Cl, and it is speculated that there may be some defects at this time. When the Cl ratio is 0.05, the peak of the material is weak as a whole, and it is speculated that there are the most defects at this time, which is consistent with the data in BET.

[0038] Thermogravimetric analysis

[0039] The prepared CuS-Cl 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 Thermogravimetric analysis of materials is performed to determine the thermal stability and property changes of the materials, such as Figure 3As shown in the figure, all materials have a certain mass loss at around 110℃, which can be attributed to the volatilization of solvent molecules or physically adsorbed water in the materials. There is no obvious weight loss phenomenon in the range of 110℃-230℃. When the temperature gradually increases to 230℃ and above, the materials all have a certain weight loss, among which CuS-Cl 0.05 The weight loss rate is 15%, which is more stable than the other two ratios. The weight loss at this stage may be partly due to the gradual detachment of Cl in CuS-Cl from the CuS lattice to release chlorine species, and partly due to the decomposition of the CuS crystal structure at high temperature. A sharp weight loss occurs above 620°C, considering that the crystal structure changes and some elements volatilize at this stage.

[0040] Performance evaluation of different Cl introduction ratios at different temperatures

[0041] CuS, CuS-Cl at 50℃, 100℃, 200℃ 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 The performance of the material is evaluated to determine the high temperature adaptability of the material, such as Figure 4 After 120 min of reaction at 50 °C, the mercury removal efficiency of CuS was 50%, and the mercury removal rates of the other materials were basically saturated; at 100 °C, the mercury removal efficiency of CuS-Cl 0.1 , CuS-Cl 0.05 The mercury removal rates of CuS-Cl 0.05 The performance was the best. After 120 minutes of continuous reaction, the mercury removal rate was still around 95%. When the temperature was increased to 200°C and the reaction was continued for 120 minutes, the CuS-Cl 0.1 , CuS-Cl 0.05 The mercury removal rate of CuS-Cl was as high as 100%, and there was no upward trend, while the mercury removal rate of CuS was only about 10%. 0.01 The mercury removal effect is poor in the range of 50-200°C. Therefore, when the amount of Cl introduced is 0.05, the material has good mercury removal efficiency in a wide temperature window.

[0042] CuS-Cl 0.05 Temperature window performance evaluation

[0043] The optimal ratio of CuS-Cl in a wide temperature window of 50-400 °C 0.05 The mercury removal performance of Figure 5From the results, the material showed excellent mercury removal performance in the range of 100-300℃, and the removal rate was maintained above 90% after 100 minutes of continuous reaction. Moreover, the mercury removal rate was above 98% at 200℃, showing the material's excellent mercury removal ability under high temperature conditions, which greatly compensated for the lack of mercury removal performance of CuS in the high temperature window. Therefore, this material can be used as a potential application material for the treatment of zero-valent mercury in non-ferrous smelting flue gas.

[0044] Effect of smoke composition

[0045] The flue gas of nonferrous metallurgy is accompanied by the phenomenon of compound pollution of pollutants. Its flue gas composition is complex and accompanied by high concentration of SO2. Therefore, the experiment was conducted to preliminarily investigate the CuS-Cl 0.05 The mercury removal rate was analyzed under the gas composition conditions of different oxygen contents, water vapor and SO2 coexistence. In the gas composition experiments, except for the experiments with different oxygen contents, N2 was used as the carrier gas, and 5% O2 was introduced at the same time, and the reaction lasted for more than 30 minutes. The results are shown in Figure 6 It can be seen that under the conditions of no oxygen and 5% O2, the mercury removal rate of the material remains above 98%, but when the oxygen content increases to 8%, the excess O2 hinders the reaction, resulting in a slight downward trend in the mercury removal rate. 0.05 The mercury removal efficiency of CuS-Cl decreased slightly, but still remained above 90%. When 3000ppm SO2 was introduced, the mercury removal performance of the material did not show a further downward trend, indicating that the 0.05 The material has superior sulfur resistance and water resistance, and can be used as a potential material for mercury treatment in non-ferrous smelting flue gas.

[0046] In addition, due to the high concentration of SO2 in non-ferrous smelting flue gas, the experiment also tested CuS-Cl 0.05 The mercury removal rate under different SO2 content conditions was tested and analyzed. Figure 7 It can be seen that after the introduction of 1000ppm and 1500ppm SO2, CuS-Cl 0.05 The mercury removal rate of CuS-Cl 0.05 The mercury removal rate of CuS-Cl showed a slight downward trend, but was still above 97%, indicating that the introduction of SO2 at this concentration had no inhibitory effect on the mercury removal performance of the material. 0.05 It has excellent resistance to SO2 poisoning; when the SO2 concentration continues to increase to 6000ppm, the mercury removal performance of the material decreases to a certain extent. At this time, the excessive introduction of SO2 causes the performance of the material to be inactivated to a certain extent, but the effect is relatively weak. Therefore, even in a flue gas environment with high concentration of SO2, CuS-Cl0.05 Still able to demonstrate superior mercury removal capabilities.

[0047] Removal mechanism analysis

[0048] The XPS analysis of CuS-Cl 0.05 The mercury removal mechanism of the reaction is shown in the XPS spectra of Cl 2p, Cu 2p, S2p, and Hg 4f before and after the reaction. Figure 8 As shown, Figure 8 Figure a shows the Cl 2p spectra before and after the reaction. The fresh sample has peaks at 198.3eV and 199.83eV, indicating the presence of Cl species in the sample. After the reaction, the peak position moves to a lower binding energy, and the peak area ratio changes, indicating that Cl participates in the reaction of Hg 0 Removal reaction.

[0049] Figure 8 b is the characteristic peak spectrum of Cu 2p. After peak fitting, the binding energies of 933.35 eV and 952.3 eV correspond to Cu + species, the binding energies at 935.19eV, 936.56eV and 955.36eV ​​are attributed to Cu 2+ species, the binding energy of the samples shifted to the right after the reaction, and Cu 2+ The relative content of Cu + The relative content of Cu 2+ and Hg 0 There is electron transfer between them, which promotes the Hg 0 of oxidation.

[0050] The S2p orbital peak is fitted, from Figure 8 As can be seen in Figure c, the peak positions shift slightly before and after the reaction, but the relative peak area does not change, indicating that S plays little role in the reaction process. Figure 8 (d) is the Hg 4f spectrum after the reaction. The characteristic peak at 102.52 eV is attributed to Hg 2+ , indicating that during the reaction, Hg 0 Basically oxidized to Hg 2+ .

[0051] Table 6-2 XPS analysis of CuS-Cl 0.05 Changes in relative content of surface Cu element valence

[0052]

[0053] The Hg-TPD experiment was used to study the CuS-Cl 0.05 Mercury adsorption product, CuS-Cl 0.05 With Hg 0React at 100℃, 150℃, and 200℃ for about 20 minutes respectively, then stop Hg 0 and O2 are introduced, and the remaining Hg in the pipeline is blown away with N2 0 and Hg weakly adsorbed on the adsorbent surface 0 , and the temperature was adjusted to 50°C. Subsequently, the temperature was programmed to rise from 50°C to 700°C at a rate of 5°C / min, and the corresponding mercury signal curve was recorded. When the temperature continued to rise, the CuS-Cl reacted with mercury at 100°C. 0.05 A large amount of mercury is released, and the desorption peak is at 318°C. It is speculated that under low temperature of 100°C, CuS-Cl 0.05 The main reaction for mercury is adsorption, and the product is HgS. The material after mercury reaction at 150℃ releases a small amount of mercury after high-temperature desorption, indicating that the mercury reaction process at 150℃ is not entirely an adsorption reaction, but also has a certain catalytic process. At the same time, the CuS-Cl reaction at 200℃ 0.05 No significant amount of Hg was observed during the temperature programming process. 0 signal, it is inferred that a large amount of HgCl exists in the reaction process and has entered the flue gas during the reaction

[111] , indicating that the process is mainly catalytic reaction. It can be inferred that CuS-Cl 0.05 The good behavior under low temperature conditions is mainly due to the adsorption of CuS, while the excellent performance under high temperature conditions is mainly due to the catalytic reaction dominated by Cl. 0.05 It is not only suitable for mercury removal in low-temperature environments, but also has good performance under high-temperature conditions. It is an excellent mercury removal material with adaptability to a wide temperature window.

[0054] Based on the above results, CuS-Cl 0.05 In removing Hg 0 The mechanism of the reaction process, such as Fig.10 As shown, the specific reaction can be expressed as:

[0055] Hg 0 (g)→Hg 0 (ads) (6-1)

[0056] Hg 0 (ads)+Cu 2+ →Hg 2+ (ads)+Cu + (6-2)

[0057] Hg 0 (ads)+S 2- →HgS (6-3)

[0058] Hg 0(ads)+Cl - →HgCl (6-4)

[0059] The following conclusions can be drawn from the above:

[0060] (1) From the characterization data of XRD, SEM, BET, etc., it can be concluded that Cl successfully enters the CuS lattice and presents a layered stacking structure. The specific surface area is reduced to a certain extent compared with CuS;

[0061] (2) Through CuS, CuS-Cl 0.1 , CuS-Cl 0.05 , CuS-Cl 0.01 Performance tests showed that when the amount of Cl introduced was 0.05, it showed better mercury removal performance, and the removal rate could reach 100% at 100℃-200℃ for 120min.

[0062] (3) Under different flue gas components, it can be seen that the introduction of excessive O2 will inhibit the mercury removal rate of the material, while high concentration of SO2 also has a slight negative impact on the mercury removal of the material;

[0063] (4) XPS combined with material characterization and performance was used to speculate on the mercury removal mechanism. 0 First, it is adsorbed on the surface of the material to form a weak adsorption. Under low temperature conditions (around 100°C), the reaction is mainly manifested as adsorption, and the product is HgS. The main reaction process is Cu 2+ Promote Hg 0 Oxidation into Hg 2+ , Hg 2+ With S 2- The generated HgS is adsorbed in the material, and under high temperature conditions (about 200°C), the reaction mainly manifests as adsorption plus catalysis, Cl - and Hg 0 The reaction generates HgCl which enters the flue gas.

[0064] Embodiment 2:

[0065] The actual flue gas of a copper smelter was taken as the treatment object. The flue gas temperature at the outlet of the primary waste heat boiler was 320℃. 200m3 / h of flue gas was drawn out from the original flue. The SO3 concentration was 500mg / m3, the SO2 concentration was about 2%, and the Hg 0 Concentration is about 5mg / m3, Hg 2+ The concentration is 0.5mg / m3.

[0066] Entering the high-temperature electrostatic precipitator, a 300-mesh CuS-Cl demercuration agent was sprayed in front of the precipitator, with a spray rate of 500 g / h and a residence time of 1 s. After the reaction stabilized, the flue gas at the precipitator outlet was sampled and analyzed. The results showed that Hg 0 The removal efficiency is over 99%.

[0067] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A high-temperature mercury removal agent for metallic copper sulfide, characterized in that: The demercuration agent comprises a copper salt solution, a sulfur ion solution and CuCl2·2H2O, and the molar ratio of the three is 1:1:0.01-0.1; The above-mentioned method for preparing the mercury removal agent is specifically as follows: The copper salt solution and the sulfur ion solution are mixed and stirred, and then CuS is obtained after reaction aging, washing, and drying. The CuS is then mixed with a certain amount of CuCl2·2H2O, ground, calcined at high temperature, and further ground to obtain a CuS-Cl mercury removal agent.

2. A high-temperature mercury removal agent for metal copper sulfide according to claim 1, characterized in that: The copper salt is one or more of copper nitrate, copper chloride, copper sulfate and copper acetate.

3. A high-temperature mercury removal agent for metal copper sulfide according to claim 1, characterized in that: The sulfur ion solution is one or a mixed solution of sodium sulfide, thiourea, ammonium sulfide and potassium sulfide.

4. A high-temperature mercury removal agent for metal copper sulfide according to claim 1, characterized in that: The molar ratio of the metal copper ions to the sulfur ions in the sulfur-containing solution is 1:1, stirring is performed at room temperature for 1-3 hours, and then aging is performed for 2-3 hours.

5. A high-temperature mercury removal agent for metal copper sulfide according to claim 1, characterized in that: The copper salt solution and the sulfur ion solution are mixed and stirred, and the precipitate obtained by reaction aging and washing is placed in a drying oven at 50-70°C and dried for 12-24 hours.

6. The high-temperature demercuration agent for metallic copper sulfide according to claim 1, characterized in that the CuS and CuCl2·2H2O are ground for 20-30 min and then calcined in a muffle furnace for 1-3 h.

7. Use of the high-temperature demercuration agent for copper sulfide according to claim 1 in treating high-concentration mercury-containing waste gas from smelting.

8. The use according to claim 7, characterized in that: The CuS-Cl mercury removal agent is injected into the high-temperature electrostatic precipitator inlet flue through the injection system, with a residence time of 0.5-1s. The reacted mercury removal agent is mixed with the roasted sand and enters the leaching process.

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