A method for electrolytic refining of crude antimony based on a tartaric acid system

Abstract

This invention discloses a method for the membrane electrolytic refining of crude antimony based on a tartaric acid system, relating to the field of metal purification technology. The method includes: preparing an antimony tartrate solution, controlling the antimony ion concentration to 30–55 g / L and the tartrate ion concentration to 230–270 g / L, so that the antimony ions exist as negatively charged complex ions. After settling and filtration, crude antimony is used as the anode and a stainless steel plate as the cathode, at a current density of 200–250 A / m. 2 Pre-electrolysis is performed at 25–55°C to achieve deep purification of the solution; then, anion exchange membranes are used to separate the anode and cathode chambers, allowing only negatively charged ions to pass through; finally, the clean solution obtained from pre-electrolysis is used as the initial electrolyte, and the solution is purified at a current density of 50–200 A / m³. 2 Electrolytic refining at 25~55℃. This invention enables electrolytic refining over a wide current density range (50~250 A / m). 2 It operates stably for a long time within a temperature range (15~55 ℃), and obtains high-quality refined antimony products with dense crystals, smooth surfaces and excellent morphology on stainless steel cathode plates, realizing efficient and low-pollution electrolytic refining of crude antimony under the green tartaric acid system.

Description

Technical Field

[0001] This application relates to the field of metal purification technology, and in particular to a method for crude antimony membrane electrolytic refining based on a tartaric acid system. Background Technology

[0002] Antimony (Sb), a strategically critical metal, has conductivity between that of conductors and insulators. It is resistant to oxidation and corrosion at room temperature, and its compounds exhibit high heat resistance and low resistivity, making it a key raw material for semiconductor devices, infrared detectors, and phase change materials. my country imposed export controls on antimony and related products in September 2024.

[0003] Currently, the refining of metallic antimony mainly involves two methods: pyrometallurgical refining and electrolytic refining. Pyrometallurgical refining primarily removes impurities by adding alkalis and other impurity-removing agents at high temperatures to form slag, or by using methods such as melt refining and zone melting to remove impurities. However, these processes suffer from low resource utilization, severe environmental pollution, and difficulties in metal recovery. Electrolytic refining offers several electrolyte systems to choose from, including hydrofluoric acid-sulfuric acid systems, ammonium fluoride-sulfuric acid systems, hydrochloric acid systems, and tartaric acid systems. Among these, the acidic electrolyte systems that have achieved industrial application are mainly hydrofluoric acid-sulfuric acid systems, ammonium fluoride-sulfuric acid systems, and hydrochloric acid systems. Due to the high acidity of fluoride salt electrolytes and the strong corrosiveness and toxicity of high-fluoride solutions, their large-scale industrial application is limited. In hydrochloric acid systems, antimony salts are easily hydrolyzed and passivated, and electrolyte regeneration is difficult. Tartaric acid (C4H6O6) is a biodegradable and low-toxicity organic acid that can form stable water-soluble complexes with various metal ions. It has been applied in the green extraction and electroplating of non-ferrous metals such as copper, tin, and zinc. However, existing processes for antimony electrolytic refining in tartaric acid systems suffer from unsatisfactory impurity removal, and cathode burning is prone to occur under high cathode current densities.

[0004] Therefore, developing an electrolysis method with better impurity removal effect and adaptability to higher current density for the antimony tartrate acidic electrolyte system is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this application provides a method for crude antimony membrane electrolytic refining based on a tartaric acid system, which can effectively solve the problem of unsatisfactory impurity removal.

[0006] This application discloses a method for the electrolytic refining of crude antimony using a tartaric acid system via a membrane, comprising the following steps: (1) Prepare antimony tartrate solution with antimony trioxide and DL tartaric acid, and control the concentration of antimony ions in the solution to be 30-55 g / L and the concentration of tartrate ions to be 230-270 g / L. By adjusting the molar ratio of antimony ions and tartrate ions, the antimony ions in the solution exist in the form of multi-coordinated and negatively charged complex ions. (2) After the above-prepared solution is allowed to stand and filtered, it is pre-electrolyzed to promote the co-deposition of impurities with electrode potential close to or more positively charged than antimony on the cathode. Through a certain period of pre-electrolysis, the solution can be deeply purified and impurities removed. The clean antimony-containing solution obtained by pre-electrolysis is used as the initial electrolyte in the cathode chamber of the subsequent electrolysis process. (3) Anion exchange membrane is used as a diaphragm to divide the electrolytic cell into an anode chamber and a cathode chamber. The function of the diaphragm is to allow only negatively charged ions in the anode chamber to pass through the diaphragm into the cathode chamber, thereby retaining positively charged impurity ions in the anode chamber. Meanwhile, multi-coordinated and negatively charged antimony complex ions and acid radical ions can pass through the diaphragm into the cathode chamber, thereby ensuring the formation of an electric circuit in the electrolytic cell. (4) Using crude antimony as the anode and stainless steel plate as the cathode, direct current is applied, and the electrolysis temperature, current density and anode-cathode distance are controlled for electrolytic refining. As electrolysis proceeds, the electrolyte in the anode chamber is led out of the cell through the external circulation system of the electrolytic cell for open-circuit purification and impurity removal, and then circulated back to the cathode chamber. (5) As electrolysis proceeds, the crude antimony anode undergoes continuous electrochemical dissolution. Antimony and impurities with electrode potentials negative or similar to antimony also dissolve into the electrolyte in the anode chamber. However, due to the obstruction of the anion exchange membrane, most impurities cannot directly enter the cathode chamber. The electrolyte in the anode chamber is led out of the cell through the external circulation system of the electrolytic cell. After purification and impurity removal, it is circulated back to the cathode chamber to deposit antimony. Therefore, the electrolyte in the cathode chamber is always a high-purity solution containing antimony during the electrolysis process. After electrolysis for a certain period of time, high-purity metallic antimony can be obtained on the cathode plate.

[0007] Further, the pre-electrolysis process conditions described in step (2) are as follows: crude antimony is used as the anode, stainless steel plate is used as the cathode, current density is 200~250 A / m2, electrolysis temperature is 25~55 ℃, electrode spacing is 55~65 mm, electrolyte circulation speed is 400~600 mL / min, and electrolysis cycle is 5~10 days.

[0008] Furthermore, the anion exchange membrane described in step (3) is of model AE2 or AE4.

[0009] Further, the electrolytic refining process conditions described in step (4) are as follows: crude antimony is used as the anode, stainless steel plate is used as the cathode, current density is 50~200 A / m2, electrolysis temperature is 25~55 ℃, electrode spacing is 60~75 mm, and electrolyte circulation speed is 400~600 mL / min.

[0010] Furthermore, the open-circuit purification and impurity removal method described in step (4) is one or more combinations of fine filtration, activated carbon adsorption, ion exchange resin adsorption, or antimony-based impurity removal adsorbent.

[0011] The beneficial effects of this application are: (1) In this invention, after the electrolyte is prepared and before the formal electrolysis, a pre-electrolysis step is introduced. A specific current density, temperature and circulation rate are used to carry out pre-electrolysis for 5 to 10 days. This can effectively remove impurities in the solution system whose electrode potential is close to or more positive than antimony (such as copper, lead, etc.), purify the antimony tartrate electrolyte from the source, and provide a clean reaction medium for the subsequent deposition of high-purity antimony.

[0012] (2) This invention uses an anion exchange membrane (such as AE2 or AE type) to divide the electrolytic cell into an anode chamber and a cathode chamber. By utilizing the selective permeability of the anion exchange membrane to multi-coordinated negatively charged antimony tartrate ions, it ensures the mass transfer and reduction of antimony ions in the cathode chamber, and effectively prevents impurity ions and oxidizing substances generated by anode dissolution in the anode chamber from migrating to the cathode region, thus avoiding co-deposition of impurities and oxidative pollution of antimony at the cathode. At the same time, by combining the periodic open-circuit purification treatment of the external circulation of the anode chamber solution and its return to the cathode chamber, the continuous cleanliness of the cathode chamber solution can be maintained, thereby solving the problems of easy cathode burn-out plates and rough crystals in the existing antimony tartrate system under high cathode current density.

[0013] (3) Under the synergistic effect of the above-mentioned pre-electrolysis and membrane electrolysis, the present invention can achieve a wide current density range (50~250 A / m). 2 It operates stably for a long time within a temperature range (15~55 ℃), and obtains high-quality refined antimony products with dense crystals, smooth surfaces and excellent morphology on stainless steel cathode plates, realizing efficient and low-pollution electrolytic refining of crude antimony under the green tartaric acid system. Attached Figure Description

[0014] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0015] Figure 1 This is a schematic diagram of the antimony cathode obtained in Example 1 of this application; Figure 2This is a schematic diagram of the antimony cathode obtained in Example 2 of this application; Figure 3 This is a schematic diagram of the antimony cathode obtained in Comparative Example 1 of this application; Figure 4 This is a schematic diagram of the antimony cathode obtained in Comparative Example 2 of this application; Figure 5 This is a schematic diagram of the electrolytic refining apparatus of this application. Detailed Implementation

[0016] The embodiments of this application will now be described in more detail with reference to the examples. While embodiments of this application are shown in the examples, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0017] Example 1 This embodiment provides a method for the electrolytic refining of crude antimony using a tartaric acid system via a membrane, comprising the following steps: (1) Antimony tartrate electrolyte with antimony ion concentration of 45 g / L and tartrate ion concentration of 250 g / L was prepared using antimony trioxide and DL-tartaric acid, and the molar ratio of antimony ion to tartrate ion was controlled to be 11:50. (2) The solution prepared in step (1) was allowed to stand for 12 h, finely filtered, and then subjected to a current density of 250 A / m. 2 Pre-electrolysis purification was carried out under the conditions of electrolysis temperature of 25 ℃, anode-cathode distance of 55 mm and electrolyte circulation rate of 600 mL / min, and the pre-electrolysis time was 5 days. (3) The electrolytic cell is divided into an anode chamber and a cathode chamber using an AE2 anion exchange membrane; the surface oxides and oil stains of the crude antimony are removed by sanding with sandpaper, and then rinsed and dried with ultrapure water to serve as a soluble anode plate. The composition of the crude antimony is shown in Table 1 below. Table 1 Elemental content in crude antimony (4) A surface-treated stainless steel plate is used as the cathode plate, and direct current is applied to control the current density at 150 A / m. 2 Electrolytic refining was carried out at an electrolysis temperature of 25 ℃ and a cathode-cathode spacing of 75 mm. (5) The solution in the anode chamber is led to the purification tank through external circulation. After removing impurities such as lead and bismuth by antimony-based adsorbent and fine filtration, the electrolyte is then pumped into the cathode chamber at a circulation rate of 300 mL / min. (6) After 4 days of electrolysis, refined antimony product can be obtained on a stainless steel cathode plate. The morphology of the obtained cathode antimony product is as follows: Figure 1 As shown in Table 2, the composition of refined antimony is 96.27%, the cell voltage is 0.708 V, and the DC power consumption is 485.75 kW·h / t·Sb.

[0018] Table 2 Elemental content in refined antimony Example 2 This embodiment provides a method for the electrolytic refining of crude antimony using a tartaric acid system via a membrane, comprising the following steps: (1) Antimony tartrate electrolyte with antimony ion concentration of 40 g / L and tartrate ion concentration of 250 g / L was prepared using antimony trioxide and DL-tartaric acid, and the molar ratio of antimony ion to tartrate ion was controlled to be 1:5. (2) The solution prepared in step (1) was allowed to stand for 12 h, finely filtered, and then subjected to a current density of 200 A / m. 2 Pre-electrolysis purification was carried out under the conditions of electrolysis temperature of 55 ℃, anode-cathode distance of 60 mm and electrolyte circulation rate of 400 mL / min, and the pre-electrolysis time was 5 days. (3) The electrolytic cell is divided into an anode chamber and a cathode chamber using an AE2 anion exchange membrane; the surface oxides and oil stains of the crude antimony are removed by sanding with sandpaper, and then rinsed and dried with ultrapure water to serve as a soluble anode plate. The composition of the crude antimony is shown in Table 3 below. Table 3 Elemental content in crude antimony (4) A surface-treated stainless steel plate is used as the cathode plate, and direct current is applied to control the current density at 100 A / m. 2 Electrolysis was carried out at an electrolysis temperature of 35 ℃ and a cathode-cathode spacing of 65 mm. (5) The solution in the anode chamber is led to the purification tank through external circulation. Antimony-based adsorbent, activated carbon adsorbent and fine filter are used to remove impurities such as lead and bismuth. Then, the electrolyte is pumped into the cathode chamber at a circulation rate of 600 mL / min. (6) After 4 days of electrolysis, refined antimony product can be obtained on the stainless steel cathode plate. The composition of refined antimony is shown in Table 4 below. The current efficiency is 97.59%, the cell voltage is 0.691 V, and the DC power consumption is 467.68 kW·h / t·Sb.

[0019] Table 4. Elemental content of antimony in cathode Example 3 This embodiment provides a method for the electrolytic refining of crude antimony using a tartaric acid system via a membrane, comprising the following steps: (1) Antimony tartrate electrolyte with antimony ion concentration of 40 g / L and tartrate ion concentration of 250 g / L was prepared using antimony trioxide and DL-tartaric acid, and the molar ratio of antimony ion to tartrate ion was controlled to be 1:5. (2) The solution prepared in step (1) was allowed to stand for 12 h, finely filtered, and then subjected to a current density of 200 A / m. 2 Pre-electrolysis purification was carried out under the conditions of electrolysis temperature of 35 ℃, anode-cathode distance of 75 mm, and electrolyte circulation rate of 500 mL / min for 5 days. (3) The electrolytic cell is divided into an anode chamber and a cathode chamber using an AE4 anion exchange membrane; the surface oxides and oil stains of the crude antimony are removed by sanding with sandpaper, and then rinsed and dried with ultrapure water to serve as a soluble anode plate. The composition of the crude antimony is shown in Table 5 below. Table 5 Elemental content in crude antimony (4) A surface-treated stainless steel plate is used as the cathode plate, and direct current is applied to control the current density at 200 A / m. 2 Electrolytic refining is carried out at an electrolysis temperature of 55 ℃ and an electrode spacing of 65 mm; a schematic diagram of the electrolytic refining apparatus is shown below. Figure 5 As shown; (5) The solution in the anode chamber is led to the purification tank through external circulation. After removing impurities such as arsenic, lead and bismuth by resin adsorbent, antimony-based adsorbent and fine filtration, the electrolyte is then pumped into the cathode chamber at a circulation rate of 400 mL / min. (6) After 4 days of electrolysis, refined antimony product can be obtained on a stainless steel cathode plate. The morphology of the obtained cathode antimony product is as follows: Figure 2 As shown in Table 6, the composition of refined antimony is 99.18%, the cell voltage is 0.683 V, and the DC power consumption is 455 kW·h / t·Sb.

[0020] Table 6 Elemental content in refined antimony Example 4 This embodiment provides a method for the electrolytic refining of crude antimony using a tartaric acid system via a membrane, comprising the following steps: (1) Antimony tartrate electrolyte with antimony ion concentration of 45 g / L and tartrate ion concentration of 250 g / L was prepared using antimony trioxide and DL-tartaric acid, and the molar ratio of antimony ion to tartrate ion was controlled to be 11:50. (2) The solution prepared in step (1) was allowed to stand for 12 h, finely filtered, and then subjected to a current density of 200 A / m. 2Pre-electrolysis purification was carried out under the conditions of electrolysis temperature of 45 ℃, anode-cathode distance of 65 mm, and electrolyte circulation rate of 600 mL / min for 5 days. (3) The electrolytic cell is divided into an anode chamber and a cathode chamber using an AE4 anion membrane; the surface oxides and oil stains of the crude antimony are removed by sanding with sandpaper, and then rinsed and dried with ultrapure water to serve as a soluble anode plate. The composition of the crude antimony is shown in Table 1 below. Table 7 Elemental content in crude antimony (4) A surface-treated stainless steel plate is used as the cathode plate, and direct current is applied to control the current density at 50 A / m. 2 Electrolysis was carried out at an electrolysis temperature of 35 ℃ and a cathode-cathode spacing of 70 mm. (5) The solution in the anode chamber is led to the purification tank through external circulation. After removing impurities such as arsenic, lead and bismuth by resin adsorbent, antimony-based adsorbent and fine filtration, the electrolyte is then pumped into the cathode chamber at a circulation rate of 300 mL / min. (6) After 4 days of electrolysis, refined antimony product can be obtained on the stainless steel cathode plate. The composition of refined antimony is shown in Table 8 below. The current efficiency is 98.84%, the cell voltage is 0.698 V, and the DC power consumption is 466.4 kW·h / t·Sb.

[0021] Table 8 Elemental content in refined antimony Comparative Example 1 The only difference between this comparative example and Example 1 is the absence of a diaphragm; all other conditions are the same. The morphology of the obtained cathode antimony product is as follows. Figure 3 As shown.

[0022] Depend on Figure 3 It can be seen that, without a diaphragm and with a current density of 200 A / m 2 Under electrolytic conditions, the antimony cathode exhibits cracking.

[0023] Comparative Example 2 The only difference between this comparative example and Example 3 is the absence of a diaphragm; all other conditions are the same. The morphology of the obtained cathode antimony product is as follows. Figure 4 As shown.

[0024] Depend on Figure 4 It can be seen that, without a diaphragm, pre-electrolysis is performed at a current density of 250 A / m 2 Under electrolytic conditions, the antimony cathode exhibits cracking.

[0025] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for membrane electrolytic refining of crude antimony based on a tartaric acid system, characterized in that, Includes the following steps: (1) Prepare antimony tartrate solution with antimony trioxide and DL tartaric acid, and control the concentration of antimony ions in the solution to be 30-55 g / L and the concentration of tartrate ions to be 230-270 g / L. By adjusting the molar ratio of antimony ions and tartrate ions, the antimony ions in the solution exist in the form of multi-coordinated and negatively charged complex ions. (2) After the above-prepared solution is allowed to stand and filtered, it is pre-electrolyzed to promote the co-deposition of impurities with electrode potential close to or more positively charged than antimony on the cathode with antimony. The clean antimony-containing solution obtained by pre-electrolysis is used as the initial electrolyte in the cathode chamber of the subsequent electrolysis process. (3) Anion exchange membranes are used as diaphragms to divide the electrolytic cell into an anode chamber and a cathode chamber; (4) Using crude antimony as the anode and stainless steel plate as the cathode, direct current is applied, and the electrolysis temperature, current density and anode-cathode distance are controlled for electrolytic refining. As electrolysis proceeds, the electrolyte in the anode chamber is led out of the cell through the external circulation system of the electrolytic cell for open-circuit purification and impurity removal, and then circulated back to the cathode chamber. (5) After electrolysis for a certain period of time, high-purity antimony metal can be obtained on the cathode plate.

2. The method for diaphragmatic electrolytic refining of crude antimony based on a tartaric acid system according to claim 1, characterized in that, The pre-electrolysis process conditions described in step (2) are as follows: crude antimony is used as the anode, stainless steel plate is used as the cathode, and the current density is 200~250 A / m. 2 The electrolysis temperature is 25~55 ℃, the electrode spacing is 55~65 mm, the electrolyte circulation rate is 400~600 mL / min, and the electrolysis cycle is 5~10 days.

3. The method for diaphragmatic electrolytic refining of crude antimony based on a tartaric acid system according to claim 1, characterized in that, The anion exchange membrane mentioned in step (3) is of model AE2 or AE4.

4. The method for diaphragmatic electrolytic refining of crude antimony based on a tartaric acid system according to claim 1, characterized in that, The electrolytic refining process conditions described in step (4) are as follows: crude antimony is used as the anode, stainless steel plate is used as the cathode, and the current density is 50~200 A / m. 2 Electrolysis temperature 25~55 ℃, electrode spacing 60~75 mm, electrolyte circulation rate 400~600 mL / min.

5. The method for diaphragmatic electrolytic refining of crude antimony based on a tartaric acid system according to claim 1, characterized in that, The open-circuit purification and impurity removal method described in step (4) is one or more combinations of fine filtration, activated carbon adsorption, ion exchange resin adsorption, or antimony-based impurity removal adsorbent.

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