TW544468B - Novel 3-stage process for making stainless steel - Google Patents

Abstract

A novel 3-stage process for making stainless steel mainly comprises transferring a steel liquid from an EAF electric furnace to an MRP conversion furnace; blowing oxygen to perform an oxygen decarburization reaction; omitting a reduction step in the MRP process and directly transferring the oxide-containing steel liquid to a VOD vacuum furnace to perform a VCD vacuum carbon deoxidization step; adding a reducing material (e.g. aluminum, silicon iron, lime, fluorite, etc.) into the steel liquid to reduce out oxides of chromium, manganese, iron, etc.; and performing a temperature measurement, a sampling, and adjustments of composition and temperature, followed by outputting the steel. The invented 3-stage process transfers a reducing step in the MRP process to a VOD vacuum furnace, thereby avoiding a consumption of temperature and oxygen caused by the interruption of a decarburization process, reducing the cost of reducing material, and increasing the operation life of the refractory material.

Description

544468 V. Description of the invention (1) ---- This invention is a new three-stage steelmaking process for stainless steel. More specifically, 'specially refers to a method that can reduce the consumption cost of reducing materials and increase the wealth. New three-stage steelmaking process for stainless steel. , 2 Refer to the first figure, which is a traditional EAF—A〇I) two-stage steelmaking " L process chart ', which is a solution of EAF (Electric Arc Furnace electric furnace) 1 1 The molten steel is directly transferred to the AOD (Argon Oxygen Decarburizat ιηη) process. 12 Refining, using argon and oxygen for decarburization steps. 'Although this two-stage steelmaking process has the advantages of production capacity and raw material use, the A0D process 2 It is difficult to make steel with extremely low carbon and nitrogen, and high cost gas (argon) consumes a large amount, which is not economical. Another traditional two-stage steelmaking process is shown in the second figure, which is an EAF-V0D two-stage steelmaking process, which uses EAF (Electric Arc

Furnace electric furnace) 1 1 molten steel is directly moved to VOD (Vacuum

Oxygen Decarburization (vacuum furnace) process 丄 3 for vacuum oxygen decarburization. Although this two-stage steelmaking process can produce high-quality steels with very low carbon, nitrogen, and hydrogen, there are many restrictions on the raw materials used. In order to improve the defects of the traditional two-stage steelmaking process, a so-called EAF-MRP-V0D three-stage steelmaking process has been developed (as shown in the third picture), which is based on EAF (Electric Arc Furnace electric furnace) ; [1 The molten steel is first transferred to MRP (Metal Refining PrOcess converter) process 14, using top-blowing oxygen and bottom-blowing nitrogen or argon to carry out the decarburization reaction, and adding alloy raw materials in the process of oxygen blowing The composition is adjusted, and then the reduction step is performed in the MRP process 14 and the reducing materials such as aluminum, ferrosilicon, lime, and fluorite are added to the molten steel to reduce the oxidation of chromium, manganese, and iron.

544468 V. Description of the invention (2) The material is then moved to the VOD (Vacuum Oxygen Decarburization vacuum furnace) process 13 for refining, and vacuum oxygen decarburization is performed by using vacuum, top blowing oxygen, and bottom blowing argon, and After V0D stops blowing oxygen, the vacuum degree is further pulled, and a VCD (Vacuum Carbon Deoxidization) step is performed. The high vacuum degree is used to force the carbon and oxygen in the molten steel to react to achieve carbon deoxidation. Finally, in the V0D process, The reduction step is performed again, and reducing materials such as aluminum, ferrosilicon, lime, and fluorite are added to the molten steel to reduce the oxides such as chromium, manganese, and iron.

However, after many years of actual production in the conventional three-stage steelmaking process, it is found that its efficiency is not as good as the original expectation, and its refractory cost and material cost yield are lower than the traditional one-stage process. The main reason for the low efficiency is that it is first performed the reduction step in the MRP process and then moved to the V0D process for decarburization. However, the conditions required for the decarburization step are mainly high temperature, low Pco partial pressure and high oxygen content. The steelmaking process arranges reduction steps in the MRP process, which not only interrupts the decarburization process, but also consumes high temperatures and oxygen that can continue to deoxidize. It also increases the cost of materials, and the slag generated at the time is easy to attack refractory materials. , So reduce the use of refractory oddities.

However, in the actual manufacturing of the conventional stainless steel making process, it is not difficult to summarize the following shortcomings: 1 · Although the traditional EAF-A0D two-stage steel making process has the advantages of capacity and raw material use, the A0D process is difficult to make extreme Low-carbon-nitrogen steel grades are still costly and consume large amounts of milk (argon), which is not economically beneficial.

544468 V. Description of the invention (3) 2 · The traditional EAF-VOD two-stage steelmaking process can produce high-quality steels with extremely low carbon, nitrogen, and hydrogen, but its raw materials have many restrictions. 3 · The conventional EAF-MRP-VOD three-stage steelmaking process arranges reduction steps in the MRP process, which not only interrupts the decarburization process, but also consumes high temperatures and oxygen that can continue to deoxidize, and also increases the cost of material consumption. ' And the slag produced by the reduction is easy to attack the refractory, so the service life of the refractory is reduced.

The inventor of this case has been concentrating on the design and development of steel technology for many years, and has a strong sense of mission for quality improvement projects. He usually has a detailed and clear analysis of the advantages and disadvantages of various metal processing processes, and often starts to improve. According to the foregoing analysis, it can be known that the conventional stainless steelmaking process has the disadvantages of increasing costs and not meeting economic benefits. In view of this, the inventor of this case has researched and improved the above-mentioned shortcomings. In the spirit of excellence, he continues to study and think and has experienced many This test finally completed the design of the present invention. That is, the main object of the present invention is to provide a new three-stage steelmaking process for stainless steel which can reduce the consumption cost of reducing materials and improve the service life of refractory materials.

According to the above purpose, the new stainless steel three-stage steelmaking process of the present invention is mainly to move the molten steel after the EAF electric furnace is melted to the MRP converter, use the blowing | to carry out the oxygen decarburization reaction, and cancel the reduction step of the MRP process. Directly transfer the molten steel containing oxides to the V〇d vacuum furnace before performing VCD vacuum carbon removal | step by step, and then add reducing materials (such as aluminum, ferrosilicon, lime, fluorite, etc.) in the molten steel to reduce the Oxides of chromium, manganese, iron, etc.

No. 6 I 544468 5. Description of the invention (4), the steel can be tapped after sampling and composition and temperature adjustment; the three-stage process of the present invention moves the reduction step of the MRP process to a VOD vacuum furnace, so it can avoid stripping The carbon process is interrupted and consumes temperature and oxygen, which can reduce the cost of reducing materials' and increase the service life of two refractories. The reason is that the new three-stage stainless steelmaking process of stainless steel according to the present invention mainly includes: EAF (Electric Arc Furnace) melting process, which can melt scrap steel and alloy materials into high temperature molten steel; MRP (Metal Refining Process Converter) The oxygen decarburization process uses a top-blown oxygen and a bottom-blown nitrogen or argon to perform the decarburization reaction. During the oxygen blowing process, alloy materials can be added to adjust the composition, and the original reduction step in the MRP process can be cancelled directly. Move the molten steel containing oxides to a vOD vacuum furnace for refining; (Vacuum Oxygen Decarburization vacuum furnace) vacuum oxygen decarburization process, which uses vacuum and top-blow oxygen and bottom-blow argon to perform post-dehydration reactions' In the present invention, the molten steel in the JJRP process is directly moved to the vacuum carbon deoxidation VCD first, and then the vacuum blown oxygen decarburization V0D or the vacuum is used to increase the oxygen temperature. The aforementioned vacuum carbon deoxygenation VCI) uses high vacuum to force the molten steel. The carbon in the reaction with oxygen, in order to achieve the purpose of carbon deoxidation; and the aforementioned vacuum oxygen blowing temperature rise is because the molten steel enters the vOD process, and then performs VCD vacuum carbon deoxidation, and KD The temperature of the molten steel in the process of empty carbon tax and oxygen will continue to decrease, so the oxygen blowing temperature must be carried out, so that the molten steel has sufficient temperature for subsequent processes such as reduction and composition adjustment; finally, aluminum, ferrosilicon, lime, fluorite, etc. are added. The reducing substance is reduced in the molten steel to reduce the oxides such as chromium, manganese, iron, etc., and the temperature is measured.

Page 7 544468

V. Description of the invention (5) Steel can be produced after sampling, composition, temperature adjustment and other processes. In terms of metallurgical concepts, the conditions required for decarburization are mainly high temperature, low Pc0, and high oxygen content. The new three-stage steelmaking process of stainless steel of the present invention eliminates the original reduction step in the MRP process and directly contains oxidation. The molten steel of the material is moved to a VOD vacuum furnace to perform vacuum carbon deoxidation VCD, and then perform a vacuum oxygen decarburization VOD or vacuum oxygen oxygen heating step, and then a reducing material is added to the vOD process liquid steel for reduction step. Therefore, the new stainless steel three-stage steelmaking process of the present invention can avoid the interruption of the decarburization process and consume the temperature and the amount of oxygen, and can reduce the consumption of the reducing materials ', and the present invention only performs the reducing step in the VQD process', thereby reducing The number of times that the slag generated during the erosion of the refractory material is reduced during the reduction, thereby increasing the service life of the refractory material. In order to make a clear and clear understanding of the object, effect and characteristics of the present invention ', the following preferred embodiments are illustrated in conjunction with the illustrations as follows: Please refer to the fourth figure, which is the present invention. Manufacturing flowchart. It can be seen from the figure that the new three-stage stainless steelmaking process of stainless steel according to the present invention mainly includes: EAF (Electric Arc Furnace) melting process, which can melt scrap steel and alloy materials into high temperature molten steel; MRP (Metal Refining Process converter) The oxygen decarburization process uses top-blowing oxygen and bottom-blowing nitrogen or argon to carry out the decarburization reaction. During the oxygen blowing process, alloy materials can be added to adjust the composition, and the original reduction step in the jjrp process can be cancelled. Move the molten steel containing oxide directly to a VOD vacuum furnace for refining; VOD (Vacuum Oxygen Decarburization vacuum furnace) vacuum

No. 8 I 544468 Oxygen decarburization process 'uses a vacuum and top-blown oxygen and bottom-blown argon to perform the break-off reaction.' The present invention moves the molten steel of the MRP process directly to the vOD process = vacuum Carbon deoxidation VCD, followed by vacuum blowing oxygen decarburization V0D or vacuum oxygen blowing heating step 'the aforementioned vacuum carbon deoxygenation VCJ) is to use high vacuum to force the carbon in the molten steel to react with oxygen to achieve the purpose of carbon deoxidation; and the aforementioned The vacuum oxygen blowing temperature rise is because the molten steel enters the vOD process, and the vacuum carbon deoxidation is performed, and the temperature of the molten steel will continue to decrease during the VCD vacuum breaking deoxidation process. Therefore, the oxygen blowing temperature must be raised. Subsequent processes such as reduction and composition adjustment; finally add aluminum, ferrosilicon, lime, fluorite and other reducing materials in the molten steel to reduce the oxides such as chromium, manganese, and iron, and perform temperature measurement, sampling and composition, temperature After adjustment and other processes, steel can be produced. Continued please refer to the fifth figure, which is a comparison chart of the amount of reducing materials of the present invention. It can be seen from the figure that after actual testing of the new three-stage stainless steelmaking process of the present invention, the results show that the amount of reducing materials (ferrosilicon, lime, fluorite, etc.) used in the reduction step is far less than the traditional EAF-AOD two-stage Steelmaking process and the conventional EAF—MRP- ^ vqd three-stage steelmaking process. In terms of the amount of Dream Iron, the average EAF—AOD two-stage steelmaking process uses about Ukg / MT of ferrosilicon. Knowing that the EAF-MRP-VOD three-stage steelmaking process has an average Shixi Iron consumption of about 22kg / MT, and the stainless steel new three-stage steelmaking process of the present invention has an average Shixi Iron consumption of about 7.8kg / MT, which is about an improvement. The level of 8kg / MT, and the consumption of lime and fluorite is much less than the traditional two-stage and conventional three-stage processes. In terms of metallurgy, the conditions required for decarburization are mainly high temperature and PC0 minutes.

544468 V. Description of the invention (7) Low M and high oxygen content. The new three-stage stainless steelmaking process of the present invention eliminates the original reduction step in the MRP process and directly moves the molten steel containing oxides to a VOD vacuum furnace. The vacuum carbon deoxidation VCD is performed first, and then the vacuum oxygen decarburization VOD or vacuum oxygen blowing heating step is performed, and then the reducing material is added to the vOD process molten steel to perform the reduction step. Therefore, the stainless steel of the present invention is a new three-stage refining The steel process can avoid the decarburization process and consume the temperature and oxygen, and can reduce the consumption of reducing materials, and the invention only performs the reduction step in the 忉 ^ process. Therefore, the slag erosion refractory produced during the reduction can be reduced. Times, thereby increasing the service life of the refractories. According to the above, the present invention has the following advantages: 1. The new three-stage stainless steelmaking process of the present invention moves the reduction step of the MRp process to a VOD vacuum furnace, which can avoid the interruption of the decarburization process and consume temperature and oxygen. It can reduce the consumption of reducing materials, and the present invention only performs the reducing step in the VOD process. Therefore, the number of times that the slag erodes the refractory material during the reduction can be reduced, thereby improving the service life of the refractory material. In summary, the present invention has excellent progress and practicality among similar products. At the same time, it has been found that the same structure exists in the literature at home and abroad. "Applicable" and "appropriate for industrial use" and "progressive" patent requirements, apply according to law. Only “the one mentioned above” is only one of the best feasible embodiments of the present invention, and all other equivalent changes made by applying the description of the present invention and the scope of patent application are feasible, so it should be included in the patent application of the present invention.

笫 Page 10 544468 V. The scope of the invention description (8). The following is a schematic illustration of the present invention: The first diagram is a flowchart of the EAF-AOD two-stage steelmaking process. The second picture is the EAF-VOD two-stage steelmaking manufacturing flow chart. The third diagram is a conventional three-stage steelmaking manufacturing flow chart. The fourth figure is a manufacturing flowchart of the present invention. The fifth figure is a comparison chart of the amount of reducing materials of the present invention.

Claims (1)

544468 6. Scope of patent application " — 1 · A new three-stage stainless steelmaking process for stainless steel, which mainly includes: EAF melting process, which can melt scrap steel and alloy materials into high temperature molten steel; MRP oxygen decarburization process 'Decarburization reaction is carried out using top-blown oxygen and bottom-blown nitrogen or argon; VOD vacuum oxygen decarburization process uses vacuum and top-blown oxygen and bottom-blown argon to carry out decarburization reaction; the present invention mainly relates to The original reduction step in the MRP process was moved to the process. When the molten steel in the MRP process was moved to the vOD process, vacuum carbon deoxidation VCD was performed first, and then vacuum oxygen decarburization v0d or vacuum oxygen oxygen heating step-by-step. Adding reducing materials to the molten steel to reduce the oxides, and the temperature can be measured after sampling, composition, and temperature adjustment process; therefore, the interruption of the decarburization process and the consumption of temperature and oxygen can be avoided, and the reduction can be reduced. Consumption of materials and increase the service life of refractories. 2 • According to the new three-stage stainless steelmaking process of stainless steel according to item 1 of the scope of the patent application, where the oxygen blowing process of the MRP process can add alloy materials to adjust the composition. 3. According to the new three-stage stainless steelmaking process of stainless steel according to item 1 of the scope of the patent application, the vacuum carbon deoxidation VCD step uses high vacuum to force the carbon in the molten steel to react with oxygen to achieve the purpose of carbon deoxidation . 4 · According to the new three-stage stainless steelmaking process of stainless steel according to item 1 of the scope of the patent application, wherein the vacuum oxygen blowing temperature increasing step is because vcd vacuum carbon deoxidation is performed after the molten steel enters the VOD process, and VCD vacuum carbon deoxidation is performed. Page 12 544468 During the process, the temperature of the molten steel will continue to decrease. Therefore, oxygen blowing and heating must be performed so that the molten steel has sufficient temperature for subsequent processes such as reduction and composition adjustment. 5 · According to the new three-stage stainless steelmaking process of stainless steel as described in item 1 of the scope of the patent application, where the reducing material can be aluminum, ferrosilicon, lime, laurel, etc. 0 6 · According to the item 1 of the scope of patent application The new three-stage steelmaking process of stainless steel described in the above, wherein the reduced oxides may be iron, short, iron, etc.