A magnetic field-enhanced duoer alloy silver electrolysis device and process

Abstract

The present invention discloses a magnetic field-enhanced silver electrolysis device and process. The device includes a silver electrolyte buffer tank and a magnetic field-enhanced silver electrolysis tank. The electrolyte inlet and electrolyte outlet of the silver electrolyte buffer tank are respectively connected to the electrolyte outlet and electrolyte inlet of the magnetic field-enhanced silver electrolysis tank. A power pump and valve are provided on the connecting pipes between the electrolyte inlet of the silver electrolyte buffer tank and the electrolyte outlet of the magnetic field-enhanced silver electrolysis tank, and between the electrolyte outlet of the silver electrolyte buffer tank and the electrolyte inlet of the magnetic field-enhanced silver electrolysis tank. A permanent magnet device is arranged around the magnetic field-enhanced silver electrolysis tank, with the permanent magnet device arranged alternately with north and south poles. The magnetic field lines of the permanent magnet device are parallel to the electrodes of the silver electrolysis tank, and the Lorentz force applied to the permanent magnet device is vertically downward. The present invention utilizes the superposition of magnetic and electric fields to simultaneously change the relevant properties of the electrodes and the electrolyte, thereby accelerating anode dissolution, promoting solution mass transfer, optimizing cathode morphology, and improving product quality.

Description

Technical Field

[0001] The present invention relates to the technical field of Doer alloy silver electrolysis, and in particular to a magnetic field enhanced Doer alloy silver electrolysis device and process. Background Art

[0002] In the Kaldo furnace anode mud treatment process, the silver anode plate formed by melting and casting is called Doer alloy, which contains Ag, Au, platinum group metals and a small amount of impurities such as Bi, Se, Cu, Te, Pb, As, and Sb.

[0003] After silver electrolysis and refining, the Doer alloy can be used to produce cathode silver powder with a purity of 99.99%. To ensure efficient silver electrolysis production, silver electrolysis is typically conducted at high current density. However, high current density can easily lead to severe concentration polarization in the electrolyte, causing hydrogen and impurities to precipitate at the cathode and oxygen to precipitate at the anode. This, in turn, creates easily oxidized sponge silver, resulting in reduced electrolysis efficiency and excessive impurities in the silver powder product. Furthermore, some floating anode mud resists rapid sedimentation, resulting in adhesion to the cathode and impacting product quality.

[0004] Currently, the application of magnetic fields in the field of electrochemistry has been widely studied. As a physical field, it usually causes magnetocaloric effect and magnetohydrodynamic effect in electrochemistry. The magnetocaloric effect refers to the local heating that can be triggered on magnetic nanoparticles by applying an external magnetic field, resulting in a local temperature increase, which can improve the reaction kinetics. The magnetohydrodynamic effect refers to the micromagnetic fluid used as a micro-stirrer to induce rotation, which can reduce ohmic polarization and solution polarization, and the upward suction effect of the magnetic fluid convection will reduce the average separation size and residence time of the bubbles, thereby accelerating the release of a small number of bubbles at the cathode. In addition, the presence of a magnetic field will cause changes in the internal structure of the liquid, particle arrangement, and electric potential, thereby reducing the surface tension coefficient, density and viscosity coefficient of the liquid, and can also increase the diffusion coefficient of metal ions and enhance the mass transfer of the solution. Once the magnetic field disappears, the effect on the solution will be sharply weakened.

[0005] Based on the above theory, in the field of electrochemistry, magnetic fields are currently only used as a means of electrolyte pretreatment, using the Lorentz force and magnetic field gradient force to change the internal structure of the electrolyte and enhance solute movement. However, the magnetization treatment is placed before electrolysis, and the positive effect of the magnetic field on the electrolyte during electrolysis has been greatly weakened. At the same time, this process does not involve the influence of the magnetic field on the electrode reaction. Therefore, the effect of enhancing the electrolysis process by electrolyte pre-magnetization is minimal. At present, there are few attempts and studies on the superposition of magnetic and electric fields. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention aims to provide a magnetic field enhanced Doer alloy silver electrolysis device and process, which utilizes the superposition of magnetic field and electric field to simultaneously change the relevant properties of electrodes and electrolytes, thereby achieving the purpose of accelerating anode dissolution, promoting solution mass transfer, optimizing cathode morphology, and improving product quality.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A magnetic field-enhanced silver electrolysis device for Doer alloys comprises a silver electrolyte buffer tank and a magnetic field-enhanced silver electrolysis tank; the electrolyte inlet and electrolyte outlet of the silver electrolyte buffer tank are respectively connected to the electrolyte outlet and electrolyte inlet of the magnetic field-enhanced silver electrolysis tank; a power pump and a valve are provided on the connecting pipes between the electrolyte inlet of the silver electrolyte buffer tank and the electrolyte outlet of the magnetic field-enhanced silver electrolysis tank, and between the electrolyte outlet of the silver electrolyte buffer tank and the electrolyte inlet of the magnetic field-enhanced silver electrolysis tank;

[0009] The magnetic field enhanced silver electrolytic cell is surrounded by a permanent magnet device, which is arranged alternately with N poles and S poles. The direction of the magnetic field lines is parallel to the electrodes of the silver electrolytic cell, and the Lorentz force it is subjected to is vertically downward.

[0010] Furthermore, the silver electrolyte buffer tank is provided with a circulating cooling water device for cooling the silver electrolyte in the silver electrolyte buffer tank.

[0011] Furthermore, a filter is provided on the connecting pipeline between the electrolyte outlet of the silver electrolyte buffer tank and the electrolyte inlet of the magnetic field enhanced silver electrolytic tank.

[0012] Furthermore, a power pump and a valve are provided on the connecting pipe between the electrolyte outlet of the silver electrolyte buffer tank and the inlet of the filter, and a power pump is provided on the connecting pipe between the outlet of the filter and the electrolyte inlet of the magnetic field enhanced silver electrolytic tank.

[0013] Furthermore, a flow meter is provided on the connecting pipeline between the outlet of the filter and the electrolyte inlet of the magnetic field enhanced silver electrolytic cell.

[0014] Furthermore, the magnetic field strength of the permanent magnet device is 1-5T.

[0015] The present invention also provides a magnetic field-enhanced silver electrolysis process for Doer alloy using the above-mentioned device, comprising the following steps:

[0016] During electrolysis, the silver ion concentration of the silver electrolyte in the silver electrolytic cell is 150-200g / L and the nitric acid concentration is 4-9g / L, the interelectrode distance is 200-300mm, and the silver electrolysis current density is 500-1000A / m 2, temperature 35-55℃, silver electrolyte circulation flow rate 40-70L / min; when the temperature exceeds 60℃, open the circulating cooling water device of the silver electrolyte buffer tank.

[0017] Furthermore, the silver electrolyte in the silver electrolyte buffer tank is regularly sampled, tested and analyzed. If the impurity content exceeds the standard, a portion of the silver electrolyte is discharged as waste electrolyte and a portion of new silver electrolyte is added to ensure that the copper ion concentration in the silver electrolyte is lower than 1 / 3 of the silver ion concentration.

[0018] The beneficial effects of the present invention are:

[0019] (1) The present invention applies magnetic field to the field of Doer alloy silver electrolysis for the first time. By integrating a permanent magnet device in the electrolytic cell, the dissolution of the Doer alloy silver anode interface film during the electrolysis process is promoted under the superposition of electric field and magnetic field, thereby accelerating the anode dissolution and inhibiting the oxygen evolution reaction. The presence of the magnetic field also causes the metal ions and suspended particles in the electrolyte to be subjected to the vertical downward Lorentz force and the magnetic field gradient force in the same direction of the magnetic field lines during the migration process, thereby accelerating the downward sedimentation of the floating anode mud and intensifying the magnetic fluid convection near the cathode, reducing the cathode concentration polarization, and avoiding the cathode hydrogen evolution reaction and the production of sponge silver.

[0020] (2) The present invention solves the problems of severe cathode concentration polarization, severe plate side reactions (oxygen evolution at the anode and hydrogen evolution at the cathode), poor product morphology, and low quality under the action of a single electric field; at the same time, it avoids a series of problems caused by the failure to fully consider the plate reactions and the weakening of the electrolyte magnetization under the action of electrolyte pre-magnetization, and realizes dual magnetization enhancement of the electrode and the electrolyte; under the superposition of the magnetic field and the electric field, the effect of 1+1>2 is achieved.

[0021] (3) The present invention can directly obtain 5N grade high-purity silver powder that meets national standards by electrolysis of Doer alloy silver. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the magnetic field enhanced silver electrolysis device for Doer alloy in Example 1 of the present invention;

[0023] Figure 2 Schematic diagram of the silver powder prepared in Experimental Group 1 of Example 3 of the present invention;

[0024] Figure 3 Schematic diagram of silver powder prepared in Experimental Group 3 of Example 3 of the present invention;

[0025] Figure 4 CV curves of the anode dissolution of Doer alloy silver in three groups of experiments in Example 3 of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0027] Example 1

[0028] This embodiment provides a magnetic field enhanced silver alloy electrolysis device, such as Figure 1 As shown, the apparatus comprises a silver electrolyte buffer tank 3 and a magnetic field-enhanced silver electrolytic tank 6; the electrolyte inlet and electrolyte outlet of the silver electrolyte buffer tank 3 are respectively connected to the electrolyte outlet and electrolyte inlet of the magnetic field-enhanced silver electrolytic tank 6; a power pump 1 and a valve 2 are provided on the connecting pipes between the electrolyte inlet of the silver electrolyte buffer tank 3 and the electrolyte outlet of the magnetic field-enhanced silver electrolytic tank 6, and between the electrolyte outlet of the silver electrolyte buffer tank 3 and the electrolyte inlet of the magnetic field-enhanced silver electrolytic tank 6. In this embodiment, the valve 2 is a manual valve.

[0029] The magnetic field enhancement silver electrolytic cell 6 is surrounded by a permanent magnet device, which is arranged alternately with N poles and S poles. The direction of the magnetic field lines is parallel to the electrodes of the silver electrolytic cell, and the Lorentz force it is subjected to is vertically downward.

[0030] In this embodiment, the silver electrolyte buffer tank 3 is provided with a circulating cooling water device for cooling the silver electrolyte in the silver electrolyte buffer tank. The circulating cooling water device can cool the silver electrolyte when the temperature exceeds an upper limit, thereby preventing the magnetocaloric effect from affecting the electrolysis system.

[0031] In this embodiment, a filter 4 is further provided on the connecting pipe between the electrolyte outlet of the silver electrolyte buffer tank 3 and the electrolyte inlet of the magnetic field-enhanced silver electrolytic tank 6. The provision of the filter can enhance the separation of magnetic impurities formed by the dual action of the electric field and the magnetic field.

[0032] In this embodiment, a power pump 1 and a valve 2 are provided on the connecting pipe between the electrolyte outlet of the silver electrolyte buffer tank 3 and the inlet of the filter 4, and a power pump 1 is provided on the connecting pipe between the outlet of the filter 4 and the electrolyte inlet of the magnetic field enhanced silver electrolytic tank 6.

[0033] Furthermore, in this embodiment, a flow meter 5 is further provided on the connecting pipe between the outlet of the filter 4 and the electrolyte inlet of the magnetic field enhanced silver electrolytic cell 6 .

[0034] In this embodiment, the magnetic field strength of the permanent magnet device is 1-5T.

[0035] Example 2

[0036] This embodiment provides a magnetic field-enhanced silver-doped alloy electrolysis process using the apparatus described in Example 1, comprising the following steps:

[0037] During electrolysis, the silver ion concentration of the silver electrolyte in the silver electrolytic cell is 150-200g / L and the nitric acid concentration is 4-9g / L, the interelectrode distance is 200-300mm, and the silver electrolysis current density is 500-1000A / m 2 , temperature 35-55℃, silver electrolyte circulation flow rate 40-70L / min; when the temperature exceeds 60℃, open the circulating cooling water device of the silver electrolyte buffer tank.

[0038] The silver electrolyte in the silver electrolyte buffer tank is sampled and tested regularly. If the impurity content exceeds the standard, a portion of the silver electrolyte is discharged as waste electrolyte and a portion of new silver electrolyte is added to ensure that the copper ion concentration in the silver electrolyte is lower than 1 / 3 of the silver ion concentration.

[0039] Example 3

[0040] This embodiment aims to verify the performance of embodiments 1 and 2 through experiments.

[0041] (1) Liquid making

[0042] A 3N grade silver plate was used, and nitric acid and hydrogen peroxide were used to dissolve the silver plate and prepare a liquid. After filtration, a silver nitrate electrolyte was obtained. The main ion content of the silver electrolyte is shown in Table 1 below.

[0043] Table 1

[0044]

[0045] (2) Electrolysis comparison

[0046] Experimental Group 1

[0047] The silver plate is pressed from Doer alloy and used as the anode plate for silver electrolysis. The anode bag is placed on the outside. The cathode plate is a titanium plate. The DC current density is controlled to be 500A / m 2 During the electrolysis process, the cell voltage is about 2.65V and remains stable. During the electrolysis process, the valve of the electrolyte circulation process is opened, and the flow rate through the flow meter is controlled to be about 50L / min. The magnetic field strength of the electrolytic cell is 0T. The electrolysis of the Doer alloy is carried out. After the electrolysis is completed, the silver powder is washed with pure water and placed in a vacuum drying oven for drying. The electrolysis efficiency is calculated to be 94.45%, and the silver powder is obtained as follows Figure 2 The purity of silver powder is shown in Table 2.

[0048] Table 2

[0049]

[0050]

[0051] Experimental Group 2

[0052] The silver plate is pressed from Doer alloy and used as the anode plate for silver electrolysis. The outer layer is covered with a self-made double-layer anode bag. The cathode plate is a titanium plate. The DC current density is controlled to be: 500A / m 2 . During the electrolysis process, the cell voltage was about 2.61V and remained stable during the electrolysis process. During the electrolyte circulation process, the valve was opened to control the flow rate through the flowmeter to be about 50L / min, and the magnetic field strength of the electrolytic cell was 1.5T. The electrolysis of the Doer alloy was carried out. After the electrolysis was completed, the silver powder was washed with pure water and placed in a vacuum drying oven for drying. The purity of the obtained silver powder was recorded as No. 2, and its electrolysis efficiency was calculated to be 98.02%.

[0053] Experimental Group 3

[0054] The silver plate is pressed from Doer alloy and used as the anode plate for silver electrolysis. The outer layer is covered with a self-made double-layer anode bag. The cathode plate is a titanium plate. The DC current density is controlled to be: 500A / m 2 During the electrolysis process, the cell voltage is about 2.55V and remains stable during the electrolysis process. During the electrolyte circulation process, the valve is opened to control the flow rate through the flow meter to be about 50L / min, and the magnetic field strength of the electrolyte electrolytic cell is 2.5T. The electrolysis of the Doer alloy is carried out. After the electrolysis is completed, the silver powder is washed with pure water and placed in a vacuum drying oven for drying. The purity of the obtained silver powder is recorded as No. 2, and its electrolysis efficiency is calculated to be 99.37%, wherein the silver powder is obtained as follows Figure 3 The purity of silver powder is shown in Table 3.

[0055] Table 3

[0056]

[0057]

[0058] Through the comparison of the above three groups of experiments, it can be found that the CV curve of the dissolution of the silver anode of the Duoer alloy ( Figure 4 ) showed that when a magnetic field was applied during the electrolysis process, the peak current of the anode dissolution increased, and increased with the increase of the magnetic field strength, indicating that the magnetic field can promote the electrolysis of silver alloy and improve the electrolysis efficiency, while reducing the cell voltage and improving the current efficiency. Figure 1 and Figure 2 It can be seen that the addition of the magnetic field eliminates the formation of sponge silver. In addition, Table 3 shows that the magnetic field can effectively improve the purity of cathode silver and realize the one-step electrolysis of 5N grade silver powder from Doer alloy.

[0059] Those skilled in the art can make various corresponding changes and modifications based on the above technical solutions and concepts, and all of these changes and modifications should be included in the scope of protection of the claims of the present invention.

Claims

1. A magnetic field enhanced silver alloy electrolysis device, characterized in that: The invention comprises a silver electrolyte buffer tank and a magnetic field-enhanced silver electrolytic tank; the electrolyte inlet and electrolyte outlet of the silver electrolyte buffer tank are respectively connected to the electrolyte outlet and electrolyte inlet of the magnetic field-enhanced silver electrolytic tank; a power pump and a valve are provided on the connecting pipes between the electrolyte inlet of the silver electrolyte buffer tank and the electrolyte outlet of the magnetic field-enhanced silver electrolytic tank, and between the electrolyte outlet of the silver electrolyte buffer tank and the electrolyte inlet of the magnetic field-enhanced silver electrolytic tank; The magnetic field enhanced silver electrolytic cell is surrounded by a permanent magnet device, which is arranged alternately with N poles and S poles. The direction of the magnetic field lines is parallel to the electrodes of the silver electrolytic cell, and the Lorentz force it is subjected to is vertically downward; the magnetic field strength of the permanent magnet device is 1-5T.

2. The magnetic field enhanced Doer alloy silver electrolysis device according to claim 1, characterized in that: The silver electrolyte buffer tank is provided with a circulating cooling water device for cooling the silver electrolyte in the silver electrolyte buffer tank.

3. The magnetic field enhanced Doer alloy silver electrolysis device according to claim 1, characterized in that: A filter is also provided on the connecting pipeline between the electrolyte outlet of the silver electrolyte buffer tank and the electrolyte inlet of the magnetic field strengthening silver electrolytic tank.

4. The magnetic field enhanced Doer alloy silver electrolysis device according to claim 3, characterized in that: A power pump and a valve are provided on the connecting pipeline between the electrolyte outlet of the silver electrolyte buffer tank and the inlet of the filter, and a power pump is provided on the connecting pipeline between the outlet of the filter and the electrolyte inlet of the magnetic field strengthening silver electrolytic tank.

5. The magnetic field enhanced Doer alloy silver electrolysis device according to claim 4, characterized in that: A flow meter is also provided on the communication pipeline between the outlet of the filter and the electrolyte inlet of the magnetic field enhanced silver electrolytic cell.

6. A magnetic field-enhanced silver electrolysis process for Doer alloy using the device according to any one of claims 1 to 5, characterized in that: The steps include: During electrolysis, the silver ion concentration of the silver electrolyte in the silver electrolytic cell is 150-200g / L and the nitric acid concentration is 4-9g / L, the interelectrode distance is 200-300mm, and the silver electrolysis current density is 500-1000A / m 2 , temperature 35-55℃, silver electrolyte circulation flow rate 40-70L / min; when the temperature exceeds 60℃, open the circulating cooling water device of the silver electrolyte buffer tank.

7. The process according to claim 6, characterized in that The silver electrolyte in the silver electrolyte buffer tank is sampled and tested regularly. If the impurity content exceeds the standard, a portion of the silver electrolyte is discharged as waste electrolyte and a portion of new silver electrolyte is added to ensure that the copper ion concentration in the silver electrolyte is lower than 1 / 3 of the silver ion concentration.

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