Preparation method of ultra-low-sulfur and ultra-low-oxygen electrolytic high-purity iron

Abstract

According to the ultralow-sulfur ultralow-oxygen electrolytic high-purity iron preparation method, electrolyte adopts a chlorate system, the removal rate of the sulfur element can be increased by 90% or above, the sulfur content in an electrolytic iron product is lower than 0.1 ppm, quality improvement of the electrolytic high-purity iron is facilitated, in addition, a reduction furnace is adopted for deoxidation, the oxygen content of the electrolytic iron can be reduced by 90% or above, and the quality of the electrolytic high-purity iron is improved. And the oxygen content in the electrolytic iron reaches below 10ppm, so that the difficulty of high oxygen content in the electrolytic iron is solved.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic high-purity iron, in particular to a method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron. Background Art

[0002] CN113481540A discloses a method for preparing high-purity iron by direct current electrolysis on a prefabricated cathode. The electrolyte mainly contains FeSO4·7H2O, and the sulfur content of the electrolytic iron produced is as high as 138.7ppm, which cannot meet the requirements of high-purity iron for users of high-temperature alloys, etc., and the oxygen content of the electrolytic iron is relatively high.

[0003] CN104609443A discloses a device and method for preparing high-purity iron by consumable anode electrolytic deposition. The impurity removal process requires the addition of sodium sulfide solution, which causes the sulfur content of the electrolytic iron product to increase to more than 2ppm, and under acidic electrolyte conditions, hydrogen sulfide toxic gas will be formed, which will cause harm to the environment and human body. The ion permeable membrane used in the electrolysis will become blocked as the electrolysis is used for a long time, causing uneven deposition of electrolytic iron.

[0004] CN116555835A discloses a production process for high-purity iron. The preparation process requires prefabricated electrolyte, during which more impurity elements will be introduced. It needs to be purified multiple times and more stabilizers need to be added. The production efficiency is low, more electrolytic waste liquid is produced, and the electrolytic iron sulfur and oxygen content are high.

[0005] CN117418271A discloses a method for preparing high-purity iron, wherein the electrolyte is prepared with anhydrous ferrous sulfate, and the non-consumable anode provides Fe 2+ The efficiency of electrolytic iron production is low and the manufacturing cost is high. Both the cathode and the anode have diaphragms, and the process of adding sodium sulfide and iron powder is complicated. The sulfur and oxygen content of the electrolytic iron product is high. Summary of the invention

[0006] In view of the defects or shortcomings existing in the prior art, the present invention provides a method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron, wherein the electrolyte adopts a chloride salt system, which can increase the removal rate of sulfur element by more than 90%, and the sulfur content in the electrolytic iron product is lower than 0.1ppm, which is conducive to improving the quality of electrolytic high-purity iron. In addition, deoxidation by a reduction furnace can reduce the oxygen content of the electrolytic iron by more than 90%, and the oxygen content in the electrolytic iron reaches below 10ppm, thereby solving the difficulty of high oxygen content in the electrolytic iron.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron, characterized in that it comprises the following steps:

[0009] Step 1, preparing an electrolyte in an electrolytic cell, wherein the components of the electrolyte include ferrous chloride, sodium chloride, purified water, ascorbic acid and purified water, and the anode in the electrolytic cell is an iron plate, and the cathode is a titanium plate;

[0010] Step 2: Heat the electrolyte to 40-50°C and adjust the Fe 2+ The ion concentration is 30-50 g / L, and the pH value is adjusted to 1.8-2.5;

[0011] Step 3: Start the rectifier power supply and set the current to 50-100A / m 2 , the voltage is set to 0.6-1.0V, and the first electrolysis time is 10-30 hours;

[0012] Step 4: Control the electrolyte temperature to 60-65°C, adjust the pH value to 2.0-2.3, and adjust the Fe 2+ The ion concentration is 40-50 g / L and the current is set to 100-150 A / m 2 , the voltage is set to 0.8-1.5V, and the second electrolysis time is continued for 10-30 hours;

[0013] Step 5: Control the electrolyte temperature to 60-65°C, adjust the pH value to 2.0-2.3, and adjust the Fe 2+ The ion concentration is 45-55 g / L and the current is set to 150-300 A / m 2 , the voltage is set to 1.0-2.0V, and the third electrolysis time is continued for 20-100 hours;

[0014] Step 6, peeling off the electrolytically deposited pure iron sheet from the cathode titanium plate.

[0015] The following steps are also included:

[0016] Step 7, using a slicer to cut the pure iron sheet into rectangular electrolytic pure iron fragments, the rectangular size of which is 10-30 mm*10-30 mm;

[0017] Step 8, placing the rectangular electrolytic pure iron fragments in a mechanical rust remover for surface rust removal for 5 hours;

[0018] Step 9, placing the surface-cleaned electrolytic pure iron sheet in a reduction furnace for deoxidation treatment for 10 hours, taking samples for analysis, and packaging the product.

[0019] The electrolytic cell in step 1 is respectively connected to a water purifier, an acid storage tank, a liquid storage tank, a circulation purification device and a negative pressure fan.

[0020] In the step 1, a nitrogen-filled liquid collecting tank is attached to the outside of the electrolytic cell, and an overflow pipe arranged horizontally at the upper part of the electrolytic cell is bent downward and inserted into the nitrogen-filled liquid collecting tank. The nitrogen-filled liquid collecting tank is a sealed container, and the electrolyte is protected by the atmosphere by filling nitrogen to prevent oxygen in the air from entering the electrolyte and causing Fe 2+ Ion oxidation, the nitrogen-filled liquid collecting tank has a safety valve on the top, a sewage outlet at the bottom, and a circulating liquid outlet at the bottom of the side. A titanium metal heat exchanger is arranged in the electrolytic cell, and a circulating liquid inlet connected to a circulating purification device is arranged at the bottom of the electrolytic cell.

[0021] The heat source of the titanium metal heat exchanger comes from electric energy, air energy or natural gas.

[0022] The negative pressure fan is used to form a slight negative pressure in the electrolytic cell with the cell cover closed, so as to reduce the air entering the electrolyte to generate Fe 2+ Oxidation and solution evaporation.

[0023] The components of the electrolyte in step 1 include hydrochloric acid in a ratio of: 4m 3 Purified water, 800kgFeCl2·4H2O, 200kgNaCl, 0.2-0.5L hydrochloric acid, 8kg ascorbic acid.

[0024] The anode iron plate and the cathode titanium plate are both connected to the rectifier power supply through copper conductive plates.

[0025] The electrolytic high-purity iron entering the product packaging in step 9 has an oxygen weight content not higher than 10 ppm and a sulfur weight content lower than 0.1 ppm.

[0026] Compared with the prior art, the present invention has the following characteristics:

[0027] 1) The method of the present invention has a simple operation process, does not require additional isolation membranes for the cathode and the anode, has a low production cost, and has a high efficiency in preparing high-purity iron by electrolysis.

[0028] 2) The electrolyte adopts a chloride salt system, which increases the removal rate of sulfur by more than 90%. The sulfur content in the electrolytic iron product is less than 0.1ppm, achieving improved quality of electrolytic high-purity iron.

[0029] 3) The use of circulating filtration and purification can promptly remove fine impurities in the electrolyte, improve the surface quality of electrolytic iron, and reduce the generation of surface streaks and nodules.

[0030] 4) Using polyester thread as the purification filter element can filter particles larger than 0.1 microns, has good purification effect, is easy to clean, the filter element can be recycled, and the electrolytic mud produced by filtration can be used as sintering raw material.

[0031] 5) The electrolytic cell is sealed with a cover, and the liquid surface is slightly negatively pressured to reduce the entry of oxygen into the electrolyte and reduce Fe 2+It can also reduce the oxidation of volatile acid gases and the corrosion of the environment and equipment.

[0032] 6) During the electrolyte circulation process, nitrogen sealing protection is used to prevent O2 in the air from entering and causing Fe 2+ of oxidation.

[0033] 7) The hydrogen reduction furnace is used for deoxidation, which is easy to operate and can eliminate the difficulty of high oxygen content in electrolytic iron. The oxygen content of electrolytic iron after treatment is reduced by more than 90%, and the oxygen content in electrolytic iron is less than 10ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a schematic flow chart of a method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron. Figure 1 The method comprises the steps of: 1, electrolyzing in an electrolytic cell with a chloride salt system electrolyte, wherein the chloride salt system electrolyte comprises FeCl2·4H2O, NaCl, and an antioxidant, wherein an anode (+) and a cathode (-) are provided in the electrolytic cell, a rectifier power supply is respectively connected to the anode and the cathode, and the electrolytic cell is respectively connected to a pure water machine, an acid storage tank, a liquid storage tank, a circulation purification device, and a negative pressure fan; 2, slicing; 3, mechanical rust removal; 4, reduction deoxidation; and 5, inspection and packaging.

[0035] Figure 2 yes Figure 1 Schematic diagram of the electrolytic cell structure. Figure 2 The reference numerals in the figure are explained as follows: 1-copper conductive plate; 2-overflow pipe; 3-nitrogen-filled liquid collecting tank; 4-circulating liquid outlet; 5-titanium metal heat exchanger; 6-circulating liquid inlet.

[0036] Figure 3 This is a physical picture of the electrolytic iron obtained in Example 1 of the present invention. Figure 3 The thickness of electrolytic iron measured by medium micrometer is 1.000mm.

[0037] Figure 4 This is a physical picture of the electrolytic iron obtained in Example 2 of the present invention. Figure 4 The thickness of electrolytic iron measured by a micrometer is 1.952mm.

[0038] Figure 5 This is a physical picture of the electrolytic iron obtained in Example 3 of the present invention. Figure 5 The thickness of electrolytic iron measured by a micrometer is 1.952mm. DETAILED DESCRIPTION

[0039] Below is a combination of the embodiments and the accompanying drawings ( Figure 1-Figure 5 ) to illustrate the present invention.

[0040] Figure 1The present invention is a schematic flow chart of a method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron. Figure 2 yes Figure 1 Schematic diagram of the electrolytic cell structure. Figure 3 This is a physical picture of the electrolytic iron obtained in Example 1 of the present invention. Figure 4 This is a physical picture of the electrolytic iron obtained in Example 2 of the present invention. Figure 5 This is a physical picture of the electrolytic iron obtained in Example 3 of the present invention. Figures 1 to 5 As shown, a method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron comprises the following steps: step 1, preparing an electrolyte in an electrolytic cell, the components of the electrolyte comprising ferrous chloride, sodium chloride, pure water, ascorbic acid and pure water, the anode in the electrolytic cell adopts an iron plate, and the cathode adopts a titanium plate; step 2, heating the electrolyte to 40-50°C, adjusting Fe 2+ The ion concentration is 30-50 g / L, and the pH value is adjusted to 1.8-2.5; Step 3, start the rectifier power supply, and set the current to 50-100 A / m 2 , the voltage is set to 0.6-1.0V, the first electrolysis time is 10-30 hours; step 4, control the electrolyte temperature to 60-65°C, adjust the pH value to 2.0-2.3, adjust Fe 2+ The ion concentration is 40-50 g / L and the current is set to 100-150 A / m 2 , the voltage is set to 0.8-1.5V, and the second electrolysis time is continued for 10-30 hours; step 5, control the electrolyte temperature to 60-65°C, adjust the pH value to 2.0-2.3, and adjust Fe 2+ The ion concentration is 45-55 g / L and the current is set to 150-300 A / m 2 , the voltage is set to 1.0-2.0V, and the third electrolysis time is continued for 20-100 hours; Step 6, peeling off the electrolytically deposited pure iron sheet from the cathode titanium plate.

[0041] The method also includes the following steps: Step 7, using a slicer to cut the pure iron sheet into rectangular electrolytic pure iron fragments, the rectangular size of which is 10-30 mm*10-30 mm; Step 8, placing the rectangular electrolytic pure iron fragments in a mechanical rust remover for surface rust removal for 5 hours; Step 9, placing the electrolytic pure iron sheet with a clean surface treatment in a reduction furnace for deoxidation treatment for 10 hours, taking samples for analysis, and packaging the products.

[0042] The electrolytic cell in step 1 is respectively connected to a water purifier, an acid storage tank, a liquid storage tank, a circulation purification device and a negative pressure blower. A nitrogen-filled liquid collecting tank is attached to the outside of the electrolytic cell in step 1. The overflow pipe arranged horizontally on the upper part of the electrolytic cell is folded downward and inserted into the nitrogen-filled liquid collecting tank. The nitrogen-filled liquid collecting tank is a sealed container. The electrolyte is protected by the atmosphere by filling nitrogen to prevent oxygen in the air from entering the electrolyte and causing Fe2+ Ion oxidation, the nitrogen-filled liquid collecting tank has a safety valve on the top, a sewage outlet at the bottom, and a circulating liquid outlet at the bottom of the side. A titanium metal heat exchanger is arranged in the electrolytic cell, and a circulating liquid inlet connected to a circulating purification device is arranged at the bottom of the electrolytic cell.

[0043] The heat source of the titanium metal heat exchanger comes from electricity, air or natural gas. The negative pressure fan is used to form a slight negative pressure in the electrolytic cell with the cell cover closed to reduce the amount of air entering the electrolyte to generate Fe 2+ Oxidation and solution volatilization. The components of the electrolyte in step 1 include hydrochloric acid in a ratio of: 4m 3 Purified water, 800kgFeCl2·4H2O, 200kgNaCl, 0.2-0.5L hydrochloric acid, 8kg ascorbic acid. The anode iron plate and the cathode titanium plate are both connected to the rectifier power supply using copper conductive plates. The electrolytic high-purity iron entering the product packaging in step 9 has an oxygen weight content of no more than 10ppm and a sulfur weight content of less than 0.1ppm.

[0044] The present invention discloses a method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron, belonging to the field of material technology; the present invention discloses a method for preparing ultra-low sulfur and ultra-low oxygen electrolytic iron on a prefabricated cathode titanium plate by direct current electrolysis. The method is characterized in that a soluble anode and an insoluble titanium plate cathode are used, the electrolyte mainly contains stabilizers such as FeCl2·4H2O and sodium chloride, the electrolysis process is online heated and cyclically impurity removed, and the cathode current density used is 50-300A / m 2 , the pH of the electrolyte is 1.80-2.50, the temperature of the electrolyte is 60-85°C, the obtained electrolytic iron is sliced, hydrogen reduced and deoxidized, and the final iron purity is 99.99%-99.999%, the S content is less than 0.1ppm, the O content is less than 10ppm, and the thickness of the electrolytic iron is 0.5-5mm. The advantages of the method of the present invention are simple process, high degree of automation, low cost and stable operation, less environmental pollution, high purity of the prepared electrolytic iron, extremely low sulfur and oxygen content, easy stripping of cathode deposited iron, good integrity, uniform and controllable thickness, etc.

[0045] The method of the invention has the advantages of controllable process, high degree of automation, simple operation, no need to add other materials, no secondary pollution of water bodies, low processing cost, easy industrialization, and extremely low sulfur and oxygen contents of electrolytic iron products, better quality and higher purity.

[0046] refer to Figure 1 The present invention provides a method for preparing ultra-low sulfur and ultra-low oxygen electrolytic iron, comprising the following steps:

[0047] Step 1: Before electrolysis, the surface of the prefabricated cathode titanium plate is degreased and cleaned, and the conductive connection is fixed; the surface of the anode iron plate is pickled, and the conductive connection is fixed.

[0048] Step 2: Electrolyte preparation: add a certain amount of electrolyte into the electrolytic cell, the ratio is: 4m 3 Purified water, 800kgFeCl2·4H2O, 200kgNaCl, 0.2-0.5L hydrochloric acid, 8kg ascorbic acid antioxidant.

[0049] Step 3: Turn on the electric heating, turn on the nitrogen protection, turn on the circulating pump filtration, raise the electrolyte temperature to 40-50℃, and detect Fe 2+ The ion concentration is 30-50g / L and the pH value is 1.8-2.5.

[0050] Step 4: Place the consumable anode and cathode in an electrolyte solution that meets the requirements, close the cover of the electrolytic cell, and start the micro-negative pressure exhaust fan to reduce the amount of air entering the electrolyte to produce Fe 2+ Oxidation and solution evaporation.

[0051] Step 5: Start the rectifier power supply and set the current to 50-100A / m 2 , the voltage is set to 0.6-1.0V, and electrolysis begins for 10-30 hours;

[0052] Step 6: Control the electrolyte temperature to 60-65°C, detect the pH value to 2.0-2.3, Fe 2+ Ion concentration 40-50g / L, current setting 100-150A / m 2 , the voltage is set to 0.8-1.5V, and the electrolysis is continued for 10-30 hours;

[0053] Step 7: Control the electrolyte temperature to 60-65℃, and check the pH value to 2.0-2.3 (otherwise start the acid adding system to add 100ml of hydrochloric acid each time), Fe 2+ The ion concentration is 45-55 g / L and the current is set to 150-300 A / m 2 , the voltage is set to 1.0-2.0V, and the electrolysis is continued for 20-100 hours (the thickness of the electrolytic iron increases with the increase of electrolysis time);

[0054] Step 8: Turn off the rectifier power supply, stop the heating and circulation system, turn off the negative pressure exhaust and nitrogen protection system, lift out the cathode titanium plates one by one, rinse off the residual liquid on the surface, peel off the deposited pure iron sheet (plate), and place the cathode titanium plates on the storage rack for standby use;

[0055] Step 9: The pure iron sheet (plate) is processed by a slicer to form a rectangular electrolytic pure iron fragment with a side length of 10 to 30 mm, and then sampled and analyzed;

[0056] Step 10: Place the rectangular electrolytic pure iron fragments in a mechanical rust remover for surface rust removal for 5 hours;

[0057] Step 11: Place the surface-treated electrolytic pure iron sheet in a reduction furnace for deoxidation treatment for 10 hours, take samples for analysis, and package the product;

[0058] refer to Figure 2 1) The nitrogen-filled liquid collecting tank is a sealed container. The electrolyte is protected by filling it with nitrogen. Oxygen in the air enters the electrolyte and causes Fe 2+ Ion oxidation has a safety valve on the top, a sewage outlet on the bottom, and an overflow pipe with a drop of 50 to 80 mm.

[0059] 2) The heat source of the titanium metal heat exchanger can come from electricity, air energy, natural gas, etc.

[0060] 3) The circulating liquid inlet is located at 1 / 3 of the distance from the side of the bottom of the electrolytic cell.

[0061] Example 1: The cathode uses a titanium plate of 830mm×755mm×3mm, and the anode uses a 750mm×650mm×18mm DT4 pure iron plate produced by Taigang. The surfaces of the two plates are degreased and cleaned, and a number of spare plates are prepared. The electrolyte is prepared, and 4m 3 After adding pure water, 800kgFeCl2·4H2O, 200kgNaCl, 0.2-0.5L hydrochloric acid and 8kg antioxidant, start the circulation pump to mix evenly; then start the heating system for about 4 hours, the electrolyte temperature rises to 45-50℃, and the pH value of the electrolyte is measured and controlled at 2.0-2.3. 17 cathode plates and 18 anode plates are placed, with a center distance of 75mm between the two. Turn on the rectifier power supply and control the current density to 50A / m 2 , voltage 0.8~1.0V, close the tank cover, turn on the negative pressure fan, the electrolyte automatically controls the temperature at 60℃, and after electrolysis for 10 hours, the current density is adjusted to 100A / m 2 Continue electrolysis for 10 hours, then set the current density to 150 A / m 2 Continue electrolysis for 20 hours. Shut down all operating systems, open the tank cover, lift out the cathode titanium plate, peel off the electrolytic iron, and obtain a total of 45.5 kg of electrolytic iron with a thickness of 0.5 to 1.1 mm ( Figure 3 ), after sampling and testing, the S content was 0.92ppm, the O content was 22ppm, and the Fe purity was 99.993%; then the iron was sliced, rusted, and deoxidized for 10 hours, and the O content of the electrolytic iron was tested again, which was 8ppm.

[0062] Example 2: The cathode uses a titanium plate of 830mm×755mm×3mm, and the anode uses a 750mm×650mm×18mm DT4 pure iron plate produced by Taigang. The surfaces of the two plates are degreased and cleaned respectively. The electrolyte is prepared, and 4m 3After adding pure water, 800kgFeCl2·4H2O, 200kgNaCl, 0.2-0.5L hydrochloric acid and 8kg antioxidant, start the circulation pump to mix evenly; then start the heating system for about 4 hours, the electrolyte temperature rises to 45-50℃, the pH value of the electrolyte is measured and controlled at 2.0-2.3, 17 cathode plates and 18 anode plates are placed, with a center distance of 75mm, and the rectifier power supply is turned on to control the current density to 100A / m 2 , voltage 0.8~1.0V, close the tank cover, turn on the negative pressure fan, the electrolyte temperature is automatically controlled at 60℃ for electrolysis for 10 hours, and the current density is adjusted to 150 / m 2 Continue electrolysis for 20 hours, then set the current density to 200 m 2 The electrolysis was continued for 30 hours. All operating systems were shut down, the tank cover was opened, the cathode titanium plate was lifted out, and the electrolytic iron was peeled off to obtain a total of 86.8 kg of electrolytic iron with a thickness of 1.5 to 2.0 mm ( Figure 4 ), sampling and testing showed that S was 0.9ppm, O was 18ppm, and the purity of Fe was 99.991%; then the iron was sliced, rust-removed, and deoxidized for 10 hours, and the electrolytic iron O content was 6ppm after sampling and testing again.

[0063] Example 3: The cathode uses a titanium plate of 830mm×755mm×3mm, and the anode uses a 750mm×650mm×18mm DT4 pure iron plate produced by Taigang. The surfaces of the two plates are degreased and cleaned, and a number of plates are prepared for use. The electrolyte is prepared, and 4m 3 After adding pure water, 800kgFeCl2·4H2O, 200kgNaCl, 0.2-0.5L hydrochloric acid and 8kg ascorbic acid antioxidant, start the circulation pump to mix evenly; then start the heating system for about 4 hours, the electrolyte temperature rises to 45-50℃, the pH value of the electrolyte is measured and controlled at 2.0-2.3, 17 cathode plates and 18 anode plates are placed, the center distance between the two is 75mm, the rectifier power supply is turned on, and the current density is controlled to 50A / m 2 , voltage 0.8~1.0V, close the tank cover, turn on the negative pressure fan, the electrolyte automatically controls the temperature at 60℃ for electrolysis for 20 hours, and the current density is adjusted to 100A / m 2 Continue electrolysis for 20 hours, then set the current density to 150 A / m 2 The electrolysis was continued for 60 hours. All operating systems were shut down, the tank cover was opened, the cathode titanium plate was lifted out, and the electrolytic iron was peeled off to obtain a total of 153.5 kg of electrolytic iron with a thickness of 2.0 to 3.5 mm ( Figure 5 ), after sampling and testing, S was 0.62ppm, O was 32ppm, and the purity of Fe was 99.991%; then the iron was sliced, rusted, and deoxidized for 10 hours, and the electrolytic iron O content was tested again, which was 10ppm.

[0064] Table 1 Comparison of composition and purity of electrolytic iron products

[0065]

[0066] The "ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron" obtained by the present invention is compared with the high-purity iron in CN111519210A (202010417630.4, a device and method for preparing high-purity iron by consumable anode electrolytic deposition). It can be seen from Table 1 that the electrolytic iron obtained by this method has higher purity and lower sulfur content.

[0067] The contents not described in detail in this specification belong to the prior art known to the professional and technical personnel in this field. It is pointed out here that the above description helps those skilled in the art to understand the invention, but does not limit the protection scope of the invention. Any equivalent replacement, modification and / or simplification of the above description without departing from the essence of the invention falls within the protection scope of the invention.

Claims

1. A method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron, characterized in that: The following steps are involved: Step 1, preparing an electrolyte in an electrolytic cell, wherein the components of the electrolyte include ferrous chloride, sodium chloride, purified water, ascorbic acid and purified water, and the anode in the electrolytic cell is an iron plate, and the cathode is a titanium plate; Step 2: Heat the electrolyte to 40-50°C and adjust the Fe 2+ The ion concentration is 30-50 g / L, and the pH value is adjusted to 1.8-2.5; Step 3: Start the rectifier power supply and set the current to 50-100A / m 2 , the voltage is set to 0.6-1.0V, and the first electrolysis time is 10-30 hours; Step 4: Control the electrolyte temperature to 60-65°C, adjust the pH value to 2.0-2.3, and adjust the Fe 2+ The ion concentration is 40-50 g / L and the current is set to 100-150 A / m 2 , the voltage is set to 0.8-1.5V, and the second electrolysis time is continued for 10-30 hours; Step 5: Control the electrolyte temperature to 60-65°C, adjust the pH value to 2.0-2.3, and adjust the Fe 2+ The ion concentration is 45-55 g / L and the current is set to 150-300 A / m 2 , the voltage is set to 1.0-2.0V, and the third electrolysis time is continued for 20-100 hours; Step 6, peeling off the electrolytically deposited pure iron sheet from the cathode titanium plate.

2. The method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron according to claim 1, characterized in that: The following steps are also included: Step 7, using a slicer to cut the pure iron sheet into rectangular electrolytic pure iron fragments, the rectangular size of which is 10-30 mm*10-30 mm; Step 8, placing the rectangular electrolytic pure iron fragments in a mechanical rust remover for surface rust removal for 5 hours; Step 9, placing the surface-cleaned electrolytic pure iron sheet in a reduction furnace for deoxidation treatment for 10 hours, taking samples for analysis, and packaging the product.

3. The method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron according to claim 1, characterized in that: The electrolytic cell in step 1 is respectively connected to a water purifier, an acid storage tank, a liquid storage tank, a circulation purification device and a negative pressure fan.

4. The method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron according to claim 1, characterized in that: In the step 1, a nitrogen-filled liquid collecting tank is attached to the outside of the electrolytic cell, and an overflow pipe arranged horizontally at the upper part of the electrolytic cell is bent downward and inserted into the nitrogen-filled liquid collecting tank. The nitrogen-filled liquid collecting tank is a sealed container, and the electrolyte is protected by the atmosphere by filling nitrogen to prevent oxygen in the air from entering the electrolyte and causing Fe 2+ Ion oxidation, the nitrogen-filled liquid collecting tank has a safety valve on the top, a sewage outlet at the bottom, and a circulating liquid outlet at the bottom of the side. A titanium metal heat exchanger is arranged in the electrolytic cell, and a circulating liquid inlet connected to a circulating purification device is arranged at the bottom of the electrolytic cell.

5. The method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron according to claim 4, characterized in that: The heat source of the titanium metal heat exchanger comes from electric energy, air energy or natural gas.

6. The method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron according to claim 3, characterized in that: The negative pressure fan is used to form a slight negative pressure in the electrolytic cell with the cell cover closed, so as to reduce the air entering the electrolyte to generate Fe 2+ Oxidation and solution evaporation.

7. The method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron according to claim 1, characterized in that: The components of the electrolyte in step 1 include hydrochloric acid in a ratio of: 4m 3 Purified water, 800kgFeCl2·4H2O, 200kgNaCl, 0.2-0.5L hydrochloric acid, 8kg ascorbic acid.

8. The method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron according to claim 1, characterized in that: The anode iron plate and the cathode titanium plate are both connected to the rectifier power supply through copper conductive plates.

9. The method for preparing ultra-low sulfur and ultra-low oxygen electrolytic high-purity iron according to claim 2, characterized in that: The electrolytic high-purity iron entering the product packaging in step 9 has an oxygen weight content not higher than 10 ppm and a sulfur weight content lower than 0.1 ppm.

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