High-conductivity pure iron cathode bar and preparation method

Abstract

The invention relates to a high-conductivity pure iron cathode bar and a preparation method thereof, by utilizing the high conductivity of a pure iron material, the electric energy loss of a cathode conductor in an aluminum electrolysis cell can be reduced, so that the electric aluminum conversion rate in electrolytic aluminum production is improved, and the energy consumption is reduced, and the high-conductivity pure iron cathode bar is characterized in that the conductivity is greater than or equal to 9.83 * 106 S / m, the total content of non-iron elements is less than or equal to 0.03 wt%, and the content of iron elements is greater than or equal to 99.97 wt%; all the non-ferrous elements are impurities, and the non-ferrous elements and the content of the non-ferrous elements in percentage by weight are specifically limited as follows: C is less than or equal to 0.0015, Si is less than or equal to 0.0015, Mn is less than or equal to 0.0035, S is less than or equal to 0.0030, Cu is less than or equal to 0.0030, Ni is less than or equal to 0.0025, N is less than or equal to 0.0020, O is less than or equal to 0.0050, Al is less than or equal to 0.0002, Cr is less than or equal to 0.0025, and P is less than or equal to 0.0005.

Description

Technical Field

[0001] This invention relates to the field of metallurgical production technology, and in particular to a high conductivity pure iron cathode rod and its preparation method. Background Technology

[0002] my country is the world's largest producer and consumer of electrolytic aluminum, and its domestic production has continued to grow in recent years. In 2024, China's annual electrolytic aluminum production exceeded 44 million tons, a record high. In the first half of 2025, production reached 26.38 million tons, a 2.8% increase compared to the same period in 2024. Electricity costs account for over 40% of electrolytic aluminum production costs. my country's average direct energy consumption per ton of aluminum is approximately 13,000 kWh, while the theoretical direct energy consumption per ton of aluminum is approximately 6,300 kWh, resulting in an energy utilization rate of about 48%, indicating significant potential for energy conservation and emission reduction.

[0003] As an important component of the cathode in aluminum electrolysis cells, cathode flat steel plays a role in distributing current evenly, improving the horizontal current of molten aluminum, enabling low-voltage production, and reducing the power consumption of electrolytic aluminum. Currently, the main materials for cathode flat steel produced are Q235A / B, Q195A / B, and SAE1006 (all carbon steel grades).

[0004] However, the aforementioned materials no longer meet the cost reduction and energy conservation requirements of the electrolytic aluminum industry. The cathode flat steel needs to meet the requirements of low resistivity (≤13.0 μΩ·cm, i.e., conductivity 7.7 × 10⁻⁶). 6 The material exhibits good mechanical properties (yield strength Rel≥140MPa, tensile strength Rm≥300MPa). Analysis suggests that electrical conductivity is affected by chemical composition and microstructure, and the same applies to mechanical properties. There is an urgent need for a material with lower non-ferrous chemical composition, higher purity, and better electrical conductivity to replace it.

[0005] To address the problems existing in the aforementioned materials, and in order to achieve cathode flat steel with non-ferrous low chemical composition, high purity, and high conductivity, it is of great significance to develop a cathode flat steel that can improve conductivity efficiency, reduce energy consumption, and lower costs when applied in aluminum electrolysis cells. Summary of the Invention

[0006] This invention addresses the deficiencies or shortcomings of existing technologies by providing a high-conductivity pure iron cathode rod and its preparation method. By utilizing the high conductivity of pure iron, the energy loss of the cathode conductor in the aluminum electrolysis cell can be reduced, thereby improving the electrolytic aluminum conversion rate in aluminum production. The high conductivity is defined as conductivity ≥ 9.83 × 10⁻⁶. 6 S / m, the pure iron has an iron content of ≥99.97wt%.

[0007] The technical solution of the present invention is as follows: A high-conductivity pure iron cathode rod, characterized in that its conductivity is ≥9.83×10⁻⁶.6 S / m, total non-ferrous element content ≤0.03 wt%, iron element content ≥99.97 wt%, all non-ferrous elements are impurities, all non-ferrous elements and wt% contents include the following specific restrictions: C ≤0.0015, Si ≤0.0015, Mn ≤0.0035, S ≤0.0030, Cu ≤0.0030, Ni ≤0.0025, N ≤0.0020, O ≤0.0050, Al ≤0.0002, Cr ≤0.0025, P ≤0.0005.

[0008] A preparation method of the above-mentioned high-conductivity pure iron cathode rod, characterized in that it comprises the following steps: Step 1, using ultra-high purity pig iron, KR stirring is used to remove S from the high-purity pig iron, and P is removed by injection to obtain a first iron liquid; Step 2, using top-bottom-side combined blowing to reduce C, remove Si, remove Mn and remove P from the first iron liquid to obtain a second iron liquid; Step 3, using LF+high vacuum RH combined refining technology to remove oxygen, nitrogen and hydrogen elements and deep purification from the second iron liquid to obtain a third iron liquid; Step 4, using a continuous casting machine to solidify and form the third iron liquid into a rolling blank; Step 5, rolling the rolling blank, the heating temperature of rolling is 1100℃-1180℃, the finish rolling temperature is 750℃-820℃, and after seven rolling passes, the total reduction is 150mm-200mm.

[0009] The non-ferrous element wt% content of the ultra-high purity pig iron in step 1 is as follows: C ≤4.5, Si ≤0.5, Mn ≤0.035, P ≤0.030, S ≤0.020, Cu ≤0.001, Ni ≤0.0020.

[0010] In the first iron liquid in step 1, S ≤0.0005wt%, P ≤0.0040 wt%.

[0011] In the second iron liquid in step 2, Si ≤0.008wt%, Mn ≤0.007wt%, P ≤0.003wt%, C ≤0.035wt%, Si ≤0.0008wt%, P ≤0.002wt%.

[0012] In the third iron liquid in step 3, O ≤0.0050wt%, N ≤0.0020wt%, H ≤0.0001wt%, C ≤0.0015wt%, Si ≤0.0015wt%, Mn ≤0.0035wt%, S ≤0.0030wt%, Cu ≤0.0030wt%, Ni ≤0.0025wt%, Al ≤0.0002wt%, Cr ≤0.0025wt%, P ≤0.0005wt%.

[0013] In step 5, the blank to be rolled is placed in a step heating furnace for heating, the total heating time is 150 min, the soaking section heating time is 30 min, and the soaking section temperature is 1100-1150℃.

[0014] In step 5, the blank to be rolled is placed in a step heating furnace for heating, the total heating time is 150 min, the soaking section heating time is 30 min, and the soaking section temperature is 1100-1150℃. 200mm of the blank, and the blank is sequentially subjected to hot saw cutting, cold bed cooling, and stack slow cooling to room temperature.

[0015] The technical effects of the present application are as follows: the high-conductivity pure iron cathode rod and the preparation method, wherein the high-conductivity pure iron cathode rod has an iron element content of ≥99.97wt% and a total non-iron element content of ≤0.03wt%, ensuring an electrical conductivity of ≥9.83×10 6 S / m, which is 15% higher than the electrical conductivity of the currently produced cathode flat steel materials Q235A / B, Q195A / B, and SAE1006, can reduce the electrical energy loss of the cathode conductor itself in the aluminum electrolysis cell, thereby improving the aluminum conversion rate in the electrolytic aluminum production, reducing the power consumption cost of the electrolytic aluminum enterprise, and meeting the needs of the electrolytic aluminum industry. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a microstructure diagram of the high-conductivity pure iron cathode rod obtained in Example 1 of the present application. Figure 1 The ferrite microstructure in the diagram corresponds to an electrical conductivity of 9.83×10 6 S / m at 25℃, S is Siemens, and m is meter; the thermal conductivity is 82.8039W / (m×K), W is watt, and K is Kelvin.

[0017] Figure 2 is a microstructure diagram of the high-conductivity pure iron cathode rod obtained in Example 2 of the present application. Figure 2 The ferrite microstructure in the diagram corresponds to an electrical conductivity of 9.84×10 6 S / m at 25℃; the thermal conductivity is 82.8713W / (m×K).

[0018] Figure 3 is a microstructure diagram of the high-conductivity pure iron cathode rod obtained in Example 3 of the present application. Figure 3 The ferrite microstructure in the diagram corresponds to an electrical conductivity of 9.85×10 6 S / m at 25℃; the thermal conductivity is 82.9575W / (m×K). DETAILED DESCRIPTION

[0019] The present application will be described below with reference to the accompanying drawings Figures 1-3 and examples.

[0020] Figure 1 Figure 1 is a microstructure diagram of a high conductivity pure iron cathode rod obtained in Example 1 of the present application. Figure 2 Figure 2 is a microstructure diagram of a high conductivity pure iron cathode rod obtained in Example 2 of the present application. Figure 3 Figure 3 is a microstructure diagram of a high conductivity pure iron cathode rod obtained in Example 3 of the present application. Referring to Figure 3, a high conductivity pure iron cathode rod has an electrical conductivity ≥ 9.83 x 10 Figures 1 to 3 6 S / m, total non-ferrous element content ≤ 0.03 wt%, iron element content ≥ 99.97 wt%, all non-ferrous elements are impurities, and all non-ferrous elements and their wt% contents include the following specific restrictions: C ≤ 0.0015, Si ≤ 0.0015, Mn ≤ 0.0035, S ≤ 0.0030, Cu ≤ 0.0030, Ni ≤ 0.0025, N ≤ 0.0020, O ≤ 0.0050, Al ≤ 0.0002, Cr ≤ 0.0025, P ≤ 0.0005.

[0021] The cross-sectional size is 140 mm 200 mm.

[0022] A method for preparing the above high conductivity pure iron cathode rod, comprising the following steps: Step 1, using ultra-high purity pig iron liquid, using KR stirring to remove S, and using injection to remove P, to obtain a first iron liquid; Step 2, using top and bottom side combined blowing to reduce C, remove Si, remove Mn and remove P, to obtain a second iron liquid; Step 3, using LF + high vacuum RH combined refining technology to remove oxygen, nitrogen and hydrogen elements and to deeply purify, to obtain a third iron liquid; Step 4, using a continuous casting machine to solidify and form the third iron liquid into a rolling blank; Step 5, rolling the rolling blank, the heating temperature for rolling is 1100°C to 1180°C, the final rolling temperature is 750°C to 820°C, and after seven rolling passes, the total reduction is 150 mm to 200 mm.

[0023] The non-ferrous element wt% content of the ultra-high purity pig iron liquid in Step 1 is as follows: C ≤ 4.5, Si ≤ 0.5, Mn ≤ 0.035, P ≤ 0.030, S ≤ 0.020, Cu ≤ 0.001, Ni ≤ 0.0020. In the first iron liquid in Step 1, S ≤ 0.0005 wt%, P ≤ 0.0040 wt%.

[0024] ​The second iron liquid in step 2 has Si≤0.008wt%, Mn≤0.007wt%, P≤0.003wt%, C≤0.035wt%, Si≤0.0008wt%, P≤0.002wt%. The third iron liquid in step 3 has O≤0.0050wt%, N≤0.0020wt%, H≤0.0001wt%, C≤0.0015wt%, Si≤0.0015wt%, Mn≤0.0035wt%, S≤0.0030wt%, Cu≤0.0030wt%, Ni≤0.0025wt%, Al≤0.0002wt%, Cr≤0.0025wt%, P≤0.0005wt%.

[0025] In step 5, the blank to be rolled is heated in a step-by-step heating furnace, the total heating time is 150 min, the soaking section heating time is 30 min, and the soaking section temperature is 1100-1150 DEG C. In step 5, the blank to be rolled is rolled into a rod with a specification of 140 mm 200mm by using a universal rolling mill for 7 passes, and the rod is sequentially subjected to hot saw cutting, cold bed cooling, and slow cooling to room temperature by stacking.

[0026] A high-conductivity pure iron cathode rod and a preparation method thereof; a high-conductivity pure iron cathode rod with a purity of 99.97wt% or more is prepared by a large-scale pyrometallurgical process, so that the purity is higher and the electrical conductivity is better, and belongs to the technical field of high-purity metal production. In order to improve the purity of the pure iron cathode rod, KR stirring is used to remove S (KR stirring is mechanical stirring) and P is removed by injection; C is reduced, Si is removed, Mn is removed, and P is removed by using top and bottom side cooperative blowing method; then degassing is carried out by using LF+high vacuum RH combined refining technology (LF is a ladle refining furnace method, and RH is a vacuum circulation degassing method); and pure iron cathode rod iron liquid is obtained by deoxidizing the iron-based liquid. The solidified and formed blank of the pure iron cathode rod is 250mm 250mm, and then the solidified and formed blank is rolled, the heating temperature is 1100-1180 DEG C, the finish rolling temperature is 750-820 DEG C, and the total reduction is 150-200mm after seven passes. Through the above steps and the corresponding process matching, the electrical conductivity of the pure iron cathode rod at 25 DEG C is ≥9.8*10 6 S / m (Siemens per meter, which is more than 15% higher than the electrical conductivity of the usual cathode flat steel) i.e. resistivity 10.2 mu Omega*cm, which can effectively improve the electrical conductivity, thereby reducing the power consumption cost of the electrolytic aluminum enterprise, and meet the needs of the electrolytic aluminum industry.

[0027] A high-conductivity pure iron cathode rod and a preparation method thereof, characterized in that: super-high-purity pig iron liquid is used, KR stirring is used to remove S from the high-purity pig iron liquid, and injection is used to remove P; a top, bottom and side combined blowing method is used to reduce C, remove Si, remove Mn and remove P; then, LF+high vacuum RH combined refining technology is used to remove oxygen, nitrogen and hydrogen; and iron-based liquid deoxidation is used to obtain pure iron cathode rod liquid.

[0028] The impurity content of the super-high-purity pig iron liquid is controlled to be C≤4.5%, Si≤0.5%, Mn≤0.035%, P≤0.030%, S≤0.020%, Cu≤0.001%, and Ni≤0.0020%.

[0029] After the KR stirring method is used to remove S, the S content in the high-purity pig iron liquid is less than or equal to 0.0005%.

[0030] After the injection method is used to remove P, the P content in the high-purity pig iron liquid is less than or equal to 0.0040%.

[0031] After the top, bottom and side combined blowing method is used to remove Si, Mn and P, the Si content is less than or equal to 0.008%, the Mn content is less than or equal to 0.007%, and the P content is less than or equal to 0.003%.

[0032] After the second oxidation purification of the top, bottom and side combined blowing method is used to reduce C, remove Si and remove P, the C content is less than or equal to 0.035%, the Si content is less than or equal to 0.0008%, and the P content is less than or equal to 0.002%.

[0033] After the LF+high vacuum RH combined refining technology is used to remove O, N and H, the O content is less than or equal to 0.0050%, the N content is less than or equal to 0.0020%, and the H content is less than or equal to 0.0001%.

[0034] After the RH refining technology is used to remove C, the deep purification and iron-based liquid deoxidation, the C content is less than or equal to 0.0015%, the Si content is less than or equal to 0.0015%, the Mn content is less than or equal to 0.0035%, the S content is less than or equal to 0.0030%, the Cu content is less than or equal to 0.0030%, the Ni content is less than or equal to 0.0025%, the Al content is less than or equal to 0.0002%, the Cr content is less than or equal to 0.0025%, and the P content is less than or equal to 0.0005%.

[0035] After solidification molding, the casting blank is heated in a walking beam furnace, the total heating time is 150 min, the soaking segment heating time is 30 min, and the soaking segment temperature is 1100-1150°C.

[0036] After heating, rolling is performed by using a universal rolling mill for seven passes to obtain a pure iron cathode rod with a specification of 140 200mm pure iron cathode rod with high purity iron, the last pass is controlled by UR rolling mill on the specification size accuracy and bending degree of pure iron cathode rod with high purity iron (UR rolling mill is universal rolling mill), the final rolling temperature is 750-820 DEG C, and the total reduction is 150-200mm. Then hot saw cutting, cold bed cooling, stacking and slow cooling to room temperature are carried out.

[0037] The technical problem to be solved by the present application: the main material of the currently produced cathode flat steel is Q235A / B, Q195A / B and SAE1006 (carbon steel grade), which cannot meet the demand of reducing cost and consumption of electrolytic aluminum industry. A material with lower chemical composition, higher purity and better conductivity is urgently needed. In order to realize low chemical composition, high purity and high conductivity of cathode flat steel, a kind of material is developed, which is applied to aluminum electrolysis cell to improve the conductivity efficiency, reduce the energy consumption and the cost of cathode flat steel, which has very important significance.

[0038] High purity iron has good ductility, corrosion resistance, thermal performance, soft magnetic property and conductivity, etc., which can obviously improve the performance and quality of steel, semiconductor, amorphous material, etc., greatly improve the performance of alloy in heat resistance and corrosion resistance, and further promote the development of electrolytic aluminum industry.

[0039] The present application provides a preparation method of high conductivity pure iron cathode rod; high purity iron with iron content of 99.97% is prepared by a large-scale pyrometallurgical process, so that the chemical composition of pure iron cathode rod is lower, the purity is higher, and the conductivity is better. The conductivity efficiency is improved, the energy consumption is reduced, and the green development of electrolytic aluminum industry is further improved.

[0040] In order to achieve the above purpose, the application discloses a high-conductivity pure iron cathode rod and a preparation method thereof. Longfengshan Foundry has provided super-high-purity pig iron billets and super-high-purity pig iron liquid to the market for a long time. The impurity content of the super-high-purity pig iron liquid can be controlled to be C≤4.5%, Si≤0.5%, Mn≤0.035%, P≤0.030%, S≤0.020%, Cu≤0.001%, and Ni≤0.0020%. The inventor uses the pig iron liquid or the pig iron as raw material to design high-purity iron for high-purity iron grade cathode flat steel. KR stirring method is used to remove S from the high-purity pig iron liquid. Then, the high-purity pig iron liquid after S removal is subjected to P removal by blowing method. Then, the high-purity pig iron liquid after P removal is subjected to the first oxidation purification including Si removal, Mn removal and P removal by top, bottom and side coordinated blowing method, so as to obtain the first purified iron base liquid. Then, the first purified iron base liquid is subjected to the second oxidation purification including C reduction, Si removal and P removal by top, bottom and side coordinated blowing method, so as to obtain the second purified iron base liquid. Then, the second purified iron base liquid is subjected to deep purification including Mn removal and P removal by LF method, so as to obtain the third purified iron base liquid. Then, the third purified iron base liquid is subjected to deep purification including C removal and iron base liquid deoxidation by RH refining technology, so as to obtain the fourth purified iron base liquid, that is, high-purity iron liquid for high-conductivity pure iron cathode rod. Then, the fourth purified iron base liquid is subjected to soft argon blowing and weak stirring deoxidation by an argon station, and then is solidified and formed into high-purity iron billet for high-conductivity pure iron cathode rod by a continuous casting machine. Then, the solidified and formed billet is rolled.

[0041] The application discloses a high-conductivity pure iron cathode rod and a preparation method thereof. Step 1: KR stirring method is used to remove S from the high-purity pig iron liquid. The S content in the high-purity pig iron liquid after S removal is less than or equal to 0.0005%.

[0042] Step 2: P removal is performed on the high-purity pig iron liquid after S removal by blowing method. The P content in the high-purity pig iron liquid after P removal is less than or equal to 0.0040%.

[0043] Step 3: the high-purity pig iron liquid after P removal is subjected to the first oxidation purification including Si removal, Mn removal and P removal by top, bottom and side coordinated blowing method, so as to obtain the first purified iron base liquid. The Si content in the first purified iron base liquid is less than or equal to 0.008%, the Mn content is less than or equal to 0.007%, and the P content is less than or equal to 0.003%.

[0044] Step 4: the first purified iron base liquid is subjected to the second oxidation purification including C reduction, Si removal and P removal by top, bottom and side coordinated blowing method, so as to obtain the second purified iron base liquid. The C content in the second purified iron base liquid is less than or equal to 0.035%, the Si content is less than or equal to 0.0008%, and the P content is less than or equal to 0.002%.

[0045] Step 5, the second purified iron base liquid is subjected to deep purification including Mn removal and P removal by LF method to obtain third purified iron base liquid; the third purified iron base liquid contains Mn≤0.003%, P≤0.0005%.

[0046] Step 6, the third purified iron base liquid is subjected to deep purification including C removal and iron base liquid deoxidization by RH method to obtain fourth purified iron base liquid, i.e. high purity iron liquid for pure iron cathode rod. C≤0.0015, Si≤0.0015, Mn≤0.0035, S≤0.0030, Cu≤0.0030, Ni≤0.0025, N≤0.0020, O≤0.0050, Al≤0.0002, Cr≤0.0025, P≤0.0005.

[0047] Step 7, the fourth purified iron base liquid is subjected to soft argon blowing and weak stirring deoxidization by argon station and then solidified by continuous casting machine to form high purity iron blank for pure iron cathode rod.

[0048] Step 8, heating: the casting blank is heated in a step-by-step heating furnace, the total heating time is 150 min, the heating time in the soaking section is 30 min, and the temperature in the soaking section is 1100-1150℃.

[0049] Step 9, rolling: the high purity iron for pure iron cathode rod is rolled into high purity iron with specification 140 200mm for pure iron cathode rod by 7 passes of universal rolling mill, and the last pass is subjected to UR rolling mill to control the specification size precision and bending degree of the high purity iron for pure iron cathode rod, the finish rolling temperature is 750-820℃, and the total reduction is 150-200mm. Then hot saw cutting, cold bed cooling and stack slow cooling to room temperature are carried out.

[0050] The preparation method of the high conductivity pure iron cathode rod has a complete set of technology and scheme. First, the high purity pig iron liquid is subjected to S removal by KR stirring method; then P removal is carried out by injection method; then Si removal, Mn removal and P removal are carried out by top, bottom and side coordinated blowing to obtain first purified iron base liquid; then C reduction, Si removal and P removal are carried out by top, bottom and side coordinated blowing to obtain second purified iron base liquid; then deep purification including Mn removal and P removal is carried out by LF method to obtain third purified iron base liquid; then deep purification including C removal and iron base liquid deoxidization are carried out by RH method to obtain fourth purified iron base liquid, i.e. high purity iron liquid for pure iron cathode rod. Then the fourth purified iron base liquid is subjected to soft argon blowing and weak stirring deoxidization by argon station, and then solidified by continuous casting machine to form high purity iron blank for pure iron cathode rod, and then the solidified blank is rolled. The obtained high purity iron for pure iron cathode rod has 20℃ electrical conductivity≥9.8×10 6 S / m, which can effectively improve the electrical conductivity and reduce the power consumption cost of electrolytic aluminum enterprises, and meet the needs of the electrolytic aluminum industry. Embodiment

[0051] The application provides a high-conductivity pure iron cathode rod for an aluminum electrolytic cell, which is produced by the method mentioned in the above technical scheme.

[0052] The smelting chemical composition of the cathode flat steel is composed of the following elements in percentage by mass: C≤0.0015%, Si≤0.0016%, Mn≤0.0036%, S≤0.0028%, Cu≤0.0030%, Ni≤0.0025%, N≤0.0022%, O≤0.0050%, Al≤0.0002%, Cr≤0.0027%, P≤0.0005%, and the rest is Fe and other inevitable impurities.

[0053] The high-conductivity pure iron cathode rod with a specification of 140 200 The production process of the high-conductivity pure iron cathode rod with a specification of 2025mm is as follows: high-purity pig iron liquid, pig iron pouring, dephosphorization of pig iron liquid, KR desulfurization, DP-COB furnace (i.e., top, bottom and side multi-point oxygen blowing purification converter), slagging and weak stirring station (slag removal), LF, RH, slagging and weak stirring station (weak stirring), casting and solidification, casting blank heating and rolling.

[0054] The smelting chemical composition (percentage by mass) of the pure iron cathode rod is composed of the following elements: C≤0.0015%, Si≤0.0016%, Mn≤0.0036%, S≤0.0028%, Cu≤0.0030%, Ni≤0.0025%, N≤0.0022%, O≤0.0050%, Al≤0.0002%, Cr≤0.0027%, P≤0.0005%, and the rest is Fe and other inevitable impurities.

[0055] A preparation method of a high-conductivity pure iron cathode rod comprises the following steps: 1, using KR stirring method to remove S from high-purity pig iron liquid; and 2, using spraying method to remove P from the high-purity pig iron liquid after S removal.

[0056] Step 2, using spraying method to remove P from the high-purity pig iron liquid after S removal; and P≤0.0040% in the high-purity pig iron liquid after P removal.

[0057] Step 3, using top, bottom and side collaborative blowing method to perform first oxidation purification including Si removal, Mn removal and P removal on the high-purity pig iron liquid after P removal, to obtain first purified iron-based liquid; Si≤0.008%, Mn≤0.007% and P≤0.003% in the first purified iron-based liquid.

[0058] Step 4, the second purification of the iron base liquid is carried out by using top and bottom side combined blowing method to include C reduction, Si removal and P removal, to obtain the second purification of the iron base liquid; the second purification of the iron base liquid has C≤0.035%, Si≤0.0008%, P≤0.002%.

[0059] Step 5, the third purification of the iron base liquid is carried out by using LF method to include Mn removal and P removal, to obtain the third purification of the iron base liquid; the third purification of the iron base liquid has Mn≤0.003%, P≤0.0005%.

[0060] Step 6, the fourth purification of the iron base liquid is carried out by using RH method to include C removal and deoxidation of the iron base liquid, to obtain the fourth purification of the iron base liquid, i.e. the cathode flat steel iron liquid. C≤0.0014%, Si≤0.0016%, Mn≤0.0036%, S≤0.0028%, Cu≤0.0030%, Ni≤0.0025%, N≤0.0022%, O≤0.0050%, Al≤0.0002%, Cr≤0.0027%, P≤0.0005%.

[0061] Step 7, the fifth purification of the iron base liquid is carried out by using argon station soft argon blowing and weak stirring deoxidation, and then the solidification molding is carried out by using the continuous casting machine to obtain the cathode flat steel blank.

[0062] Step 8, heating: the casting blank is heated in the step-by-step heating furnace, the total heating time is 150 min, the heating time in the soaking section is 30 min, and the temperature in the soaking section is 1100-1150℃.

[0063] Step 9, rolling: the universal rolling mill is used to roll the cathode flat steel with the specification of 140×200×2025mm by 15 passes, the last pass is controlled by the UR rolling mill to control the specification size precision and the bending degree of the cathode flat steel, the final rolling temperature is 750-820℃, and then the hot saw cutting, the cold bed cooling and the stacking slow cooling to room temperature are carried out to obtain the high conductivity cathode flat steel. Performance: the cathode flat steel has the electric conductivity of 9.83×10 6 S / m at 25℃, the structure is ferrite, the flat steel surface quality is good, and the specification size deviation meets the use requirement. Example

[0064] The embodiment is basically the same as example 1, except that the fifth purification of the iron base liquid, i.e. the cathode flat steel iron liquid, is obtained. C≤0.0015%, Si≤0.0015%, Mn≤0.0035%, S≤0.0025%, Cu≤0.0030%, Ni≤0.0025%, N≤0.0025%, O≤0.0049%, Al≤0.0002%, Cr≤0.0025%, P≤0.0005%. Example

[0065] The embodiment is basically the same as that of Example 1, except that a fifth purified iron-based liquid, i.e. cathode flat steel molten iron, is obtained, having C≤0.0014%, Si≤0.0015%, Mn≤0.0033%, S≤0.0025%, Cu≤0.0028%, Ni≤0.0027%, N≤0.0020%, O≤0.0049%, Al≤0.0002%, Cr≤0.0025%, P≤0.0005%.

[0066] The contents not described in detail in the specification of the present application belong to the prior art known to the person skilled in the art. It is hereby indicated that the above description is helpful for the person skilled in the art to understand the present application, but does not limit the protection scope of the present application. Any implementation of equivalent replacement, modification, improvement and / or deletion of the above description without departing from the essential content of the present application falls within the protection scope of the present application.

Claims

1. A high conductivity pure iron cathode rod, characterized in that, Electrical conductivity ≥ 9.83 × 10 6 S / m, total non-ferrous element content ≤0.03 wt%, iron element content ≥99.97 wt%, all non-ferrous elements are impurities, and the specific limits for all non-ferrous elements and their wt% content are as follows: C≤0.0015, Si≤0.0015, Mn≤0.0035, S≤0.0030, Cu≤0.0030, Ni≤0.0025, N≤0.0020, O≤0.0050, Al≤0.0002, Cr≤0.0025, P≤0.0005.

2. A method for preparing a high conductivity pure iron cathode rod as described in claim 1, characterized in that, Includes the following steps: Step 1: Using ultra-high purity pig iron molten iron, KR stirring is used to remove sulfur and blowing is used to remove phosphorus, to obtain the first molten iron. Step 2: The first molten iron is subjected to a top-bottom-side coordinated blowing method to reduce C, remove Si, remove Mn and remove P, to obtain the second molten iron; Step 3: The second molten iron is refined using a combination of LF and high vacuum RH refining technology to remove nitrogen and hydrogen elements and to deeply purify it, thus obtaining the third molten iron. Step 4: The third molten iron is solidified into a billet to be rolled using a continuous casting machine; Step 5: Roll the billet to be rolled. The rolling heating temperature is 1100℃~1180℃, the final rolling temperature is 750℃~820℃, and the total reduction is 150 mm~200 mm after seven rolling passes.

3. The method for preparing a high conductivity pure iron cathode rod according to claim 2, characterized in that, The wt% content of non-ferrous elements in the ultra-high purity pig iron molten iron in step 1 is as follows: C≤4.5, Si≤0.5, Mn≤0.035, P≤0.030, S≤0.020, Cu≤0.001, Ni≤0.0020.

4. The method for preparing a high conductivity pure iron cathode rod according to claim 2, characterized in that, In the first molten iron in step 1, S ≤ 0.0005 wt% and P ≤ 0.0040 wt%.

5. The method for preparing a high conductivity pure iron cathode rod according to claim 2, characterized in that, In step 2, the second molten iron contains Si ≤ 0.008 wt%, Mn ≤ 0.007 wt%, P ≤ 0.003 wt%, C ≤ 0.035 wt%, Si ≤ 0.0008 wt%, and P ≤ 0.002 wt%.

6. The method for preparing a high conductivity pure iron cathode rod according to claim 2, characterized in that, In step 3, the third molten iron contains O ≤ 0.0050 wt%, N ≤ 0.0020 wt%, H ≤ 0.0001 wt%, C ≤ 0.0015 wt%, Si ≤ 0.0015 wt%, Mn ≤ 0.0035 wt%, S ≤ 0.0030 wt%, Cu ≤ 0.0030 wt%, Ni ≤ 0.0025 wt%, Al ≤ 0.0002 wt%, Cr ≤ 0.0025 wt%, and P ≤ 0.0005 wt%.

7. The method for preparing a high conductivity pure iron cathode rod according to claim 2, characterized in that, Step 5 includes placing the billet to be rolled in a walking beam furnace for heating, with a total heating time of 150 minutes, a soaking zone heating time of 30 minutes, and a soaking zone temperature of 1100-1150℃.

8. The method for preparing a high conductivity pure iron cathode rod according to claim 2, characterized in that, Step 5 involves rolling the billet to be rolled into a specification of 140 mm using a universal rolling mill in 7 passes. The 200mm bar stock is sequentially hot-sawing cut, cooled on a cooling bed, and stacked for slow cooling to room temperature.

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