A method for directly measuring electrochemical properties of a slag-metal interface

Abstract

The application discloses a method for directly measuring electrochemical properties of slag-metal interface, and mainly relates to the interface between molten slag and metal liquid in a metallurgical process. The method comprises the following steps: designing a metal-molten slag cell system crucible system, and placing metal and molten slag into the crucible system; placing the crucible system into a high-temperature furnace, inserting an electrode into the molten slag after rising to a target temperature, and connecting an electrochemical workstation to perform impedance spectrum testing; and based on obtained impedance spectrum information, fitting analysis is performed to obtain electrochemical properties of the metal-molten slag interface. The application is suitable for studying and obtaining electrochemical properties of the metal-molten slag interface. Moreover, the method has strong portability, can be applied to the interface between various metal liquids and molten slags, and overcomes difficulties such as high temperature and black box interface, and has good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of metallurgy, specifically relating to a crucible system for a metal-slag battery system and a method for directly measuring the electrochemical properties of the slag-metal interface. Background Technology

[0002] In metallurgical processes, the interfacial properties between molten metal and slag are crucial to steelmaking, as many processes involve mass transfer and heterogeneous reactions of elements at the metal / slag interface. The slag / metal reaction is caused by the difference in chemical potential between the phases, but the physicochemical properties of the interface determine the kinetics. Properties such as interfacial tension play a significant role in steelmaking; low interfacial tension can lead to emulsification and enhance the metal / slag reaction by increasing the interfacial area, which is beneficial for the removal of elements such as C, P, and S during metallurgical processes. However, the interfacial properties are determined not only by the composition of the metal / slag but also by the rate of chemical reactions at the interface. Therefore, understanding the metal / slag reaction kinetics and interfacial properties is essential for producing high-quality steel.

[0003] However, the study of metal / slag interfaces faces significant challenges due to the difficulties of high-temperature experiments and observations. Researchers have long been dedicated to obtaining the physicochemical properties of the two-phase interface, but since both phases are opaque, they are typically observed using X-ray diffraction. This technique has been widely used to directly obtain interfacial tension through contact angles, but minute changes in angle on X-ray images can lead to errors. Another method is to visually observe stationary slag droplets on a large liquid metal substrate to obtain the contact angle and thus the interfacial tension. While these techniques can directly obtain interfacial tension, they cannot monitor mass transfer, the characteristics of the diffusion layer, or adsorption at the interface. Furthermore, neither X-ray diffraction nor visual observation yields interfacial electrochemical properties, and they cannot obtain the electrochemical properties of the slag-metal interface under high-temperature conditions. Therefore, new techniques and research methods are urgently needed to obtain this information.

[0004] Fundamentally, metal / slag reactions are electrochemical reactions, primarily involving heterogeneous charge transfer at the interface. The interfacial conductivity changes from electrons (metal phase) to ions (slag phase), forming an electrical double layer, which can then be studied using electrochemical methods. While this view is widely accepted, the application of electrochemistry in studying slag / metal reactions is still insufficient. A complete description of the slag / metal interface requires understanding its electrical properties, including interfacial capacitance, charge transfer resistance, charge density, and electrocapillary action—properties that control interfacial behavior. For example, the high charge density of the double layer leads to a strong attraction between the two phases and reduces interfacial tension. Among the many available electrochemical techniques, impedance spectroscopy is one of the most powerful. It uses an AC signal to characterize the frequency response of electrode processes. Rapid processes such as charging / discharging of the double layer are characterized at high frequencies. At mid-frequency frequencies, charge transfer processes are observed. At lower frequencies, slower processes such as adsorption, diffusion, and coupled chemical reactions are evident. Therefore, impedance spectroscopy provides a valuable method for detecting the characteristics of metal / slag interfaces. In addition, the potential drop generated by the electrochemical reaction occurring on the working electrode or counter electrode surface in the four-electrode system will not be measured. Only the potential drop caused by the current passing through the solution or the obstacle in the solution will be measured, which is suitable for liquid-liquid interface measurement.

[0005] Based on the four-electrode method and impedance spectroscopy, this invention designs and invents a crucible system for a metal-slag battery system, and proposes a method for directly measuring the electrochemical properties of the slag-metal interface. Summary of the Invention

[0006] The technical problem to be solved by this invention is that the application of electrochemistry in the study of slag / metal interface in the prior art is not sufficient. For example, although the prior art can directly obtain the interfacial tension, it cannot monitor the mass transfer, diffusion layer characteristics and adsorption on the interface.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] The present invention provides a crucible system for a metal-slag battery system, the crucible system comprising a first crucible, a second crucible and a third crucible, wherein the first crucible, the second crucible and the third crucible are all cylindrical hollow shells with open tops and closed bottoms.

[0009] The first crucible has a through hole at the center of its bottom end, the top end of the second crucible is fixedly connected to the through hole, and the bottom end of the second crucible extends away from the through hole.

[0010] The second crucible is completely located inside the third crucible, and the bottom end of the second crucible coincides with the bottom end of the third crucible. The top end of the third crucible extends upward and surrounds the bottom end of the first crucible.

[0011] Preferably, the diameter of the third crucible is greater than the diameter of the first crucible, which in turn is greater than the diameter of the second crucible.

[0012] Preferably, the diameter of the second crucible is equal to the diameter of the through hole at the bottom of the first crucible.

[0013] The first crucible is an alumina crucible with a diameter of 50 mm and a height of 80 mm, and the diameter of the through hole is 20 mm; the second crucible is an alumina crucible with a diameter of 20 mm and a height of 30 mm; the third crucible is an alumina crucible with a diameter of 60 mm and a height of 40 mm.

[0014] This invention also provides a method for directly measuring the electrochemical properties of the slag-gold interface, the method using the above-mentioned metal-slag battery system crucible system, comprising the following steps:

[0015] S1. Place the metal powder and slag into the crucible system.

[0016] Preferably, metal powder is loaded into a second crucible, followed by molten slag, which fills the connection area between the second and first crucibles. Finally, alumina high-temperature adhesive is filled into the third crucible.

[0017] Preferably, the metal powder is iron powder, and the slag is a mixture of pure oxides selected from at least four of CaO, SiO2, MgO, Al2O3, FeO, and MnO. The oxides are not limited to those listed above, but also include other oxides.

[0018] Preferably, the mass ratio of the metal powder to the slag is (1-2):15.

[0019] Preferably, after filling the third crucible with alumina high-temperature adhesive, the working electrode is inserted into the third crucible. The second crucible has an opening on its side, and a metal wire is passed through the opening to connect the bottom of the working electrode to the metal powder in the second crucible.

[0020] S2. Place the crucible system into a high-temperature furnace, raise it to the target temperature, insert the electrode into the molten slag, and connect it to an electrochemical workstation for impedance spectroscopy testing.

[0021] Preferably, the impedance spectroscopy test is performed using a four-electrode method. The electrodes include a working electrode, two counter electrodes, and a reference electrode. The working electrode and the second crucible are connected by a working electrode connector, and the working electrode connector and the working electrode are fixed by wrapping Mo wire. The Mo wire is protected by an alumina tube.

[0022] Preferably, both the counter electrode and the reference electrode are made of Mo, and the working electrode connector is made of ZrB2 or HfB2. Since other materials are not suitable for high-temperature conditions, the working electrode connector is limited to ZrB2 or HfB2. The Mo filament is protected by an alumina tube to prevent oxidation.

[0023] Preferably, the crucible system of the metal-slag battery system is placed in a high-temperature furnace heated by a silicon molybdenum rod and heated to the target temperature under Ar atmosphere protection. Then, the counter electrode and reference electrode are inserted, and after soaking and holding at the temperature for 2 hours, the tops of the working electrode, counter electrode and reference electrode are connected to the electrochemical workstation, and then the test is performed.

[0024] S3. Based on the obtained impedance spectrum information, the electrochemical properties of the metal-slag interface are obtained through fitting analysis.

[0025] Preferably, in the impedance spectrum test, a potential scan is first performed at a constant frequency. The differential capacitance curves under different potential conditions can be obtained using the formula -Z″ = 1 / (2πfC). The positions of the zero-charge potential and resting potential can be obtained from these differential capacitance curves. Next, the obtained resting potential is selected, and then measurement is performed using frequency scan-potential constant mode (EIS-V), with a measurement frequency range of 1Hz to 100kHz, to obtain the impedance spectrum information.

[0026] Preferably, the calibrated contact area is calculated based on the inner diameter of the second crucible to obtain the slag-gold contact area.

[0027] Preferably, based on the impedance spectrum information obtained in step S3, a Kramers-Kronig transform test (KK test) is first performed using the LIN_KK software. If the residual is biased towards high frequencies, points with large deviations are deleted for fitting analysis; if the residual is biased towards low frequencies, the spectrum is invalid, and the data is no longer fitted. After the KK test, ZSimpWin software is used for fitting analysis. The fitting circuit uses LR(C((R(O))RW)), where L is the inductance, the first R is the slag resistance impedance, C is the interface capacitance, and the R(O) unit is a finite-length outer spherical diffusion. Since the finite-length internal diffusion cannot fully meet the meaning of the data, Warburg elements are used to simulate internal diffusion. The third R is the charge transfer impedance. After fitting, eight parameters can be obtained: 1L, 2R, 3C, 4R, 5O-Y, 6O-B, 7R, 8W. Therefore, the interface charge transfer resistance (7R) can be directly obtained; according to the formula... The thickness δ of the Nernst diffusion layer can be obtained, where B is 6O-B in the fitting parameters and D is the diffusion coefficient of the metal; when the frequency is close to zero, it can be obtained from the formula. The diffusion resistance of iron can be obtained, where R is 4R in the fitting parameters and Y is 5O-Y in the fitting parameters; the interfacial charge and interfacial tension can be obtained from the differential capacitance curve, and the total excess charge density can be obtained from the integral differential capacitance curve, as shown in the following formula:

[0028]

[0029] Wherein σ M It is the total excess charge density, q M It is the free charge density, τ i It is the surface excess of adsorbed species, z i It is the charge of the adsorbed species, E PZC It is a zero potential.

[0030] Finally, the electrocapillary curve can be obtained by integrating the excess charge density curve, as shown in the following formula:

[0031]

[0032] The beneficial effects of the technical solution provided by this invention include at least the following:

[0033] This invention provides a crucible system for a metal-slag battery system. In this application, metal powder is loaded into a second crucible, and then slag is filled into the connection area between the second and first crucibles. A third crucible is located around the outer periphery of the second crucible, and the third crucible is filled with alumina high-temperature adhesive. The advantages of this structural design are that it reduces the amount of metal powder used, accurately determines the contact area between the metal and the slag, and uses ZrB2 or HfB2 as the working electrode connector to contact the molten metal. ZrB2 has chemical inertness to molten metal (such as iron) and high electronic conductivity, and also has a high melting temperature.

[0034] This invention also provides a method for directly measuring the electrochemical properties of the slag-metal interface. The method is highly portable, can be applied to the interfaces of various molten metals and slags, and overcomes difficulties such as high temperature and interface black box, and has good application prospects. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 It is a metal slag battery system.

[0037] The annotations in the attached figures are explained as follows:

[0038] 1. Working electrode; 2. Counter electrode; 3. Reference electrode; 4. Counter electrode; 5. First crucible; 6. Third crucible; 7. Second crucible; 8. Working electrode connector; 9. Alumina high-temperature adhesive.

[0039] Figure 2 The differential capacitance curve is shown in Example 1.

[0040] Figure 3 This is the excess charge density curve for Example 1.

[0041] Figure 4 The electrocapillary curve is shown in Example 1.

[0042] Figure 5 This is a typical impedance spectrum curve for Example 1.

[0043] Figure 6 This is a Kramers-Kronig transform test for Example 1.

[0044] Figure 7 The result is the ZsimpWin fitting result for Example 1.

[0045] Figure 8 This is the differential capacitance curve for Example 2.

[0046] Figure 9 This is the excess charge density curve for Example 2.

[0047] Figure 10 The electrocapillary curve is shown in Example 2.

[0048] Figure 11 This is a typical impedance spectrum curve for Example 2.

[0049] Figure 12 This is a Kramers-Kronig transform test for Example 2.

[0050] Figure 13 The result is the ZsimpWin fitting result for Example 2. Detailed Implementation

[0051] The technical solutions and problems solved by the embodiments of the present invention will be described below with reference to the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0052] like Figure 1 As shown, a metal-slag battery system crucible system includes a first crucible 5, a second crucible 7, and a third crucible 6. The first crucible 5, the second crucible 7, and the third crucible 6 are all cylindrical hollow shells with open tops and closed bottoms. A through hole is provided at the center of the bottom end of the first crucible 5. The top end of the second crucible 7 is fixedly connected to the through hole, and the bottom end of the second crucible 7 extends away from the through hole. The second crucible 7 is completely located inside the third crucible 6, and the bottom end of the second crucible 7 coincides with the bottom end of the third crucible 6. The top end of the third crucible 6 extends upwards and surrounds the bottom end of the first crucible 5.

[0053] Furthermore, the diameter of the third crucible 6 is greater than the diameter of the first crucible 5, which is greater than the diameter of the second crucible 7. The diameter of the second crucible 7 is equal to the diameter of the through hole at the bottom of the first crucible 5.

[0054] Furthermore, the first crucible 5 is an alumina crucible with a diameter of 50 mm and a height of 80 mm, and the diameter of the through hole is 20 mm; the second crucible 7 is an alumina crucible with a diameter of 20 mm and a height of 30 mm; and the third crucible 6 is an alumina crucible with a diameter of 60 mm and a height of 40 mm.

[0055] A method for directly measuring the electrochemical properties of the slag-gold interface, the method comprising the following steps:

[0056] S1. Place the metal powder and slag into the crucible system;

[0057] S2. Place the crucible system into a high-temperature furnace, raise it to the target temperature, insert the electrode into the molten slag, and connect it to an electrochemical workstation for impedance spectroscopy testing.

[0058] S3. Based on the obtained impedance spectrum information, the electrochemical properties of the metal-slag interface are obtained through fitting analysis.

[0059] Further, metal powder is loaded into the second crucible 7, followed by molten slag, which fills the connection area between the second crucible 7 and the first crucible 5. Finally, alumina high-temperature adhesive 9 is filled into the third crucible 6.

[0060] Furthermore, the mass ratio of the metal powder to the slag is (1-2):15.

[0061] Furthermore, the metal powder is iron powder, and the slag is a mixture of pure oxides selected from at least four of CaO, SiO2, MgO, Al2O3, FeO, and MnO.

[0062] Furthermore, in step S2, a four-electrode method is used for testing. The electrodes include a working electrode 1, two counter electrodes 2 and 4, and a reference electrode 3. The working electrode 1 and the second crucible 7 are connected by a working electrode connector 8, and the working electrode connector 8 and the working electrode 1 are fixed by wrapping Mo wire. The Mo wire is protected by an alumina tube.

[0063] Furthermore, the counter electrode 2, 4 and reference electrode 3 are all made of Mo, and the working electrode connector 8 is made of ZrB2 or HfB2. The Mo wire is protected by an alumina tube to prevent oxidation.

[0064] Further, in step S1, after filling the third crucible 6 with alumina high-temperature adhesive 9, the working electrode 1 is inserted into the third crucible 6. The second crucible 7 has an opening on its side; a working electrode connector 8 passes through the opening to connect the bottom of the working electrode 1 to the metal powder inside the second crucible 7.

[0065] In step S2, the crucible system of the metal-slag battery system is placed in a high-temperature furnace heated by a silicon molybdenum rod and heated to the target temperature under Ar atmosphere protection. Then, counter electrodes 2 and 4 and reference electrode 3 are inserted and soaked and kept at the temperature for 2 hours. The tops of the working electrode 1, counter electrodes 2 and 4 and reference electrode 3 are all connected to the electrochemical workstation, and then the test is performed.

[0066] Example 1

[0067] This embodiment studies the electrochemical properties of the interface between CaO-MgO-SiO2-Al2O3 slag and molten iron. Impedance spectra were obtained at 1600℃, and interface properties such as differential capacitance curves, excess charge density, electrocapillary curves, charge transfer resistance, Nernst boundary layer thickness, and diffusion resistance were obtained through fitting analysis. The main components of the slag are shown in Table 1.

[0068] Table 1. Slag Composition Table

[0069]

[0070] Design of the crucible system for S1 metal-slag battery system

[0071] The metal-slag battery system uses a combination of large and small crucibles, the specific structure and dimensions of which are shown in the attached figure. Figure 1 As shown, the large crucible, the first crucible, is an alumina cylindrical crucible with a diameter of 50 mm and a height of 80 mm. A 20 mm diameter hole is drilled in the center of its bottom, connecting to a second crucible, which is a 20 mm diameter, 30 mm high alumina cylindrical crucible. To connect the working electrode to the molten metal, a hole is drilled on the side of the bottom of the second crucible. A synthesized ZrB2 or HfB2 strip is inserted as the working electrode connector, and the connector and the working electrode are secured by wrapping with 0.5 mm diameter Mo wire. A 60 mm diameter, 40 mm high cylindrical crucible is selected as the base, the third crucible, and the entire system is placed inside. All connections are sealed with high-temperature alumina adhesive. Then, approximately 10–20 g of iron powder is placed in the second crucible, and 150 g of dried slag sample is placed in the first crucible.

[0072] After the equilibrium time is reached, the differential capacitance curve is measured first. At a constant frequency of 100kHz, the impedance spectrum is tested under different voltages, ranging from -1V to 1V. The measured differential capacitance curves are shown below. Figure 2 As shown in the figure, the zero charge potential (PZC) is approximately -0.4V, and the resting potential is approximately -0.32V. Furthermore, integrating the differential capacitance curve yields the excess charge density curve, as shown... Figure 3 As shown. To obtain the electrocapillary curve, integration over the excess charge density curve yields the result, as shown. Figure 4 As shown.

[0073] S2. Place the above crucible system into a high-temperature furnace, raise the temperature to the target temperature of 1600℃, insert the electrode into the molten slag, and connect the electrochemical workstation to perform impedance spectroscopy testing.

[0074] The crucible for the metal-slag battery system was placed in a high-temperature furnace heated with silicon molybdenum rods. Under an Ar atmosphere, it was heated to the target temperature of 1600℃. Then, counter and reference electrodes were inserted. This test employed a four-electrode method: one working electrode, two counter electrodes, and one reference electrode. Both the counter and reference electrodes were made of Mo rods with a diameter of 4 mm. At the target temperature, the two counter electrodes and the reference electrode were immersed in molten slag and held for 2 hours. The electrode tips were then connected to an electrochemical workstation for testing.

[0075] After the equilibrium time is reached, the differential capacitance curve is measured first. At a constant frequency of 100kHz, the impedance spectrum is tested under different voltages, ranging from -1V to 1V. The measured differential capacitance curves are shown below. Figure 2 As shown in the figure, the zero charge potential (PZC) is approximately -0.4V, and the resting potential is approximately -0.32V. Furthermore, integrating the differential capacitance curve yields the excess charge density curve, as shown... Figure 3 As shown. To obtain the electrocapillary curve, integration over the excess charge density curve yields the result, as shown. Figure 4 As shown.

[0076] S3. Based on the obtained impedance spectrum information, the electrochemical properties of the metal-slag interface are obtained through fitting analysis.

[0077] Based on the inner diameter of the second crucible, the contact area between the slag and the gold can be calculated to be 2.88 cm². 2 The following fittings are all calibrated using this area. Based on the impedance spectrum information obtained in step S3, the impedance spectrum is measured under resting potential conditions, with a frequency range of 1 Hz to 100,000 Hz. The obtained impedance spectrum is as follows: Figure 5 As shown. Before fitting, the Kramers-Kronig transform was tested using LIN_KK software, and the results are as follows. Figure 6 As shown, the deviation is large at high-frequency points, so high-frequency data points were removed before fitting. The fitting software used was ZsimpWin, and the fitting results are as follows. Figure 7 As shown. The charge transfer resistance Rct = 0.0535 Ω can be obtained from the fitting results. According to the formula... The thickness of the Nernst diffusion layer can be obtained as δ = 11 μm, where B is the fitting result and D is the diffusion coefficient of Fe, which is 1 × 10⁻⁶ at 1600 °C. -5 cm 2 / s. (via formula) The diffusion resistance of iron can be obtained as 0.14Ω.

[0078] The specific electrochemical properties of the slag-gold interface are listed in Table 2.

[0079] Table 2 Electrochemical properties of the slag-gold interface

[0080]

[0081] Example 2

[0082] This embodiment studies the electrochemical properties of the interface between CaO-MgO-SiO2-Al2O3 slag and carbon-containing iron liquid (carbon content 4.8 wt.%, iron content 95.2%). Impedance spectra were obtained at 1600℃, and interface properties such as differential capacitance curve, excess charge density, electrocapillary curve, charge transfer resistance, Nernst boundary layer thickness, and diffusion resistance were obtained through fitting analysis. The main components of the slag are shown in Table 3.

[0083] Table 3. Slag Composition Table

[0084]

[0085] Design of the crucible system for S1 metal-slag battery system

[0086] The metal-slag battery system uses a combination of large and small crucibles, the specific structure and dimensions of which are shown in the attached figure. Figure 1 As shown, the large crucible, the first crucible, is an alumina cylindrical crucible with a diameter of 50 mm and a height of 80 mm. A 20 mm diameter hole is drilled in the center of its bottom, connecting to a second crucible, which is a 20 mm diameter, 30 mm high alumina cylindrical crucible. To connect the working electrode to the molten metal, a hole is drilled on the side of the bottom of the second crucible. Synthesized ZrB2 or HfB2 strips are used as the working electrode connector, and the connector and the working electrode are secured by winding with 0.5 mm diameter Mo wire. A 60 mm diameter, 40 mm high cylindrical crucible is selected as the base, the third crucible, and the entire system is placed inside. All connections are sealed with high-temperature alumina adhesive. Then, approximately 10–20 g of carbon-containing iron powder (4.8 wt.% carbon, 95.2% iron) is placed in the second crucible, and 150 g of dried slag sample is placed in the first crucible.

[0087] S2. Place the above crucible system into a high-temperature furnace, raise the temperature to the target temperature of 1600℃, insert the electrode into the molten slag, and connect the electrochemical workstation to perform impedance spectroscopy testing.

[0088] The crucible for the metal-slag battery system was placed in a high-temperature furnace heated with silicon molybdenum rods. Under an Ar atmosphere, it was heated to the target temperature of 1600℃. Then, counter and reference electrodes were inserted. This test employed a four-electrode method: one working electrode, two counter electrodes, and one reference electrode. Both the counter and reference electrodes were made of Mo rods with a diameter of 4 mm. At the target temperature, the two counter electrodes and the reference electrode were immersed in molten slag and held for 2 hours. The electrode tips were then connected to an electrochemical workstation for testing.

[0089] After the equilibrium time is reached, the differential capacitance curve is measured first. At a constant frequency of 100kHz, the impedance spectrum is tested under different voltages, ranging from -1V to 1V. The differential capacitance curves obtained under different temperature conditions are shown below. Figure 8 As shown in the figure, the zero charge potential (PZC) is approximately -0.08V, and the rest potential is approximately -0.06V. Furthermore, integrating the differential capacitance curve yields the excess charge density curve, as shown... Figure 9 As shown. To obtain the electrocapillary curve, integration over the excess charge density curve yields the result, as shown. Figure 10 As shown.

[0090] S3. Based on the obtained impedance spectrum information, the electrochemical properties of the metal-slag interface are obtained through fitting analysis.

[0091] Based on the inner diameter of the second crucible, the contact area between the slag and the gold can be calculated to be 2.88 cm². 2 The following fittings are all calibrated using this area. Based on the impedance spectrum information obtained in step S3, the impedance spectrum is measured under resting potential conditions, with a frequency range of 1 Hz to 100,000 Hz. The obtained impedance spectrum is as follows: Figure 11 As shown. Before fitting, the Kramers-Kronig transform was tested using LIN_KK software, and the results are as follows. Figure 12 As shown, the error is small, the data is usable, and the fitting software used is ZsimpWin. The software fitting results are as follows. Figure 13 As shown. The charge transfer resistance Rct = 0.057 Ω can be obtained from the fitting results. According to the formula... The thickness of the Nernst diffusion layer can be obtained as δ = 18.26 μm, where B is the fitting result and D is the diffusion coefficient of Fe, which is 1 × 10⁻⁶ at 1600 °C. -5 cm 2 / s. (via formula) The diffusion resistance of iron can be obtained as 0.16Ω.

[0092] The specific electrochemical properties of the slag-gold interface are listed in Table 4.

[0093] Table 4 Electrochemical properties of the slag-gold interface

[0094]

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 crucible system for a metal-slag battery system, characterized in that, The metal-slag battery system crucible system includes a first crucible, a second crucible, and a third crucible. The first crucible, the second crucible, and the third crucible are all cylindrical hollow shells with open tops and closed bottoms. The first crucible has a through hole at the center of its bottom end, the top end of the second crucible is fixedly connected to the through hole, and the bottom end of the second crucible extends away from the through hole. The second crucible is completely located inside the third crucible, and the bottom end of the second crucible coincides with the bottom end of the third crucible. The top end of the third crucible extends upward and surrounds the bottom end of the first crucible.

2. The crucible system for the metal-slag battery system according to claim 1, characterized in that, The diameter of the third crucible is greater than the diameter of the first crucible, which in turn is greater than the diameter of the second crucible.

3. The crucible system for the metal-slag battery system according to claim 2, characterized in that, The diameter of the second crucible is equal to the diameter of the through hole at the bottom of the first crucible.

4. The crucible system for the metal-slag battery system according to claim 3, characterized in that, The first crucible is an alumina crucible with a diameter of 50 mm and a height of 80 mm, and the diameter of the through hole is 20 mm; The second crucible is an alumina crucible with a diameter of 20 mm and a height of 30 mm; The third crucible is an alumina crucible with a diameter of 60 mm and a height of 40 mm.

5. A method for directly measuring the electrochemical properties of the slag-gold interface, characterized in that, The method uses the metal-slag battery system crucible system according to any one of claims 1 to 4, and includes the following steps: S1. Place the metal powder and slag into the crucible system; S2. Place the crucible system into a high-temperature furnace, raise it to the target temperature, insert the electrode into the molten slag, and connect it to an electrochemical workstation for impedance spectroscopy testing. S3. Based on the obtained impedance spectrum information, the electrochemical properties of the metal-slag interface are obtained through fitting analysis.

6. The method according to claim 5, characterized in that, In step S1, metal powder is loaded into the second crucible, then molten slag is loaded into it, and the molten slag fills the connection area between the second crucible and the first crucible. Finally, alumina high-temperature adhesive is filled into the third crucible.

7. The method according to claim 6, characterized in that, In step S1, the mass ratio of the metal powder to the slag is (1~2):

15.

8. The method according to claim 6, characterized in that, In step S1, the metal powder is iron powder, and the slag is a mixture of pure oxides selected from at least four of CaO, SiO2, MgO, Al2O3, FeO, and MnO.

9. The method according to any one of claims 5 to 8, characterized in that, In step S2, the four-electrode method is used for testing. The electrodes include a working electrode, two counter electrodes and a reference electrode. The working electrode and the second crucible are connected by a working electrode connector, and the working electrode connector and the working electrode are fixed by wrapping Mo wire. The Mo wire is protected by an alumina tube.

10. The method according to claim 9, characterized in that, Both the counter electrode and the reference electrode are made of Mo, and the working electrode connector is made of ZrB2 or HfB2.

11. The method according to claim 9, characterized in that, In step S1, after filling the third crucible with alumina high-temperature adhesive, the working electrode is inserted into the third crucible. The second crucible has an opening on its side; a working electrode connector passes through this opening to connect the bottom of the working electrode to the metal powder inside the second crucible. In step S2, the crucible system of the metal-slag battery system is placed in a high-temperature furnace heated by a silicon molybdenum rod and heated to the target temperature under Ar atmosphere protection. Then, the counter electrode and reference electrode are inserted, and after soaking and holding at the temperature for 2 hours, the tops of the working electrode, counter electrode and reference electrode are connected to the electrochemical workstation, and then the test is performed.

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