Cost-reducing efficiency-increasing production method for large-tonnage converter

Abstract

The invention discloses a cost-reducing efficiency-increasing production method for a large-tonnage converter, and relates to the technical field of steelmaking optimization assistance. According to the technical scheme, the air blowing mode is top and bottom mixed air blowing, top air blowing and bottom air blowing are alternately carried out, and an oxygen supply spray pipe used for oxygen supply is provided with a Laval pipe type oxygen supply spray head; the purposes of efficient production of the large-tonnage converter and low operation and maintenance cost are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of steelmaking optimization assistance, and in particular to a production method for reducing costs and increasing efficiency of a large-tonnage converter. Background Art

[0002] The steelmaking converter is a device used to convert molten iron, scrap steel and ferroalloys into liquid steel. Its main feature is that it does not rely on external energy, but completes the steelmaking process through the physical heat of the molten iron itself and the heat generated by chemical reactions. The converter steelmaking method is widely used in the production of carbon steel, alloy steel, and the smelting of copper and nickel. It has the advantages of fast production speed, high single furnace output, low cost, and low pollution. It is one of the most commonly used steelmaking equipment.

[0003] In order to ensure stable improvement of product quality and achieve high efficiency and low cost of converter production, it is necessary to achieve high-efficiency and low-cost large-scale production to make the steelmaking process economically profitable. Compared with small-tonnage converters, large-tonnage converters have higher production efficiency, but the corresponding operation and maintenance costs are higher. How to reduce the production cost of large-tonnage converters is the key to reducing costs and increasing efficiency. Summary of the invention

[0004] The object of the present invention is to provide a method for reducing costs and increasing efficiency of a large-tonnage converter production, so as to achieve the purpose of efficient production of a large-tonnage converter with low operation and maintenance costs.

[0005] In order to achieve the above object, the present invention adopts the following technical means: A production method for reducing costs and increasing efficiency of a large-tonnage converter, wherein the blasting mode is top and bottom mixed blowing, the top blowing and the bottom blowing are performed alternately, and the oxygen supply nozzle for supplying oxygen has a Laval tube-type oxygen supply nozzle.

[0006] Furthermore, the maximum diameter of the cavity of the oxygen supply nozzle is 299 mm, the oxygen supply nozzle is a five-hole nozzle, the throat diameter of the oxygen supply nozzle is 40.2 mm, the outlet diameter of the oxygen supply nozzle is 52.2 mm, and the nozzle angle of the oxygen supply nozzle is 14°.

[0007] Furthermore, air-permeable bricks for bottom blowing are laid at the bottom of the converter. The air-permeable bricks are arranged in an annular seam type. The air-permeable bricks arranged at the bottom of the converter are provided with through air inlet channels surrounding the axis, and the bottom end of the air inlet channel is connected to the blowing equipment.

[0008] Furthermore, the diameter of the steel outlet of the converter is 190 mm.

[0009] Furthermore, the oxygen supply nozzle is a copper nozzle, the oxygen supply nozzle can withstand at least 2.5MPa of water pressure, and the forging density of the oxygen supply nozzle is not less than 8.93g / cm 3 .

[0010] During use, the present invention has the following beneficial effects: The shortest smelting cycle is 23 minutes, and the single-shift single-furnace production can reach up to 20 furnaces, with high production efficiency. Moreover, the final carbon-oxygen content of the product is 0.0020-0.0025, which is close to the oxygen balance level of the molten steel, so that high-quality steel can be produced. During operation, the bottom air bricks are synchronized with the furnace age, which can greatly reduce the number of maintenance times and improve maintenance efficiency. There is no need to maintain the furnace body and the bottom air bricks separately. The converter drop-type control system is adopted to achieve unequal steel tapping. The final carbon content of the steel tapping reaches 0.08%, the average qualified rate is 85%, and the residual manganese in the steel is as high as about 0.25%. Using a special oxygen lance nozzle, the converter oxygen supply time is shortened by 50-70 seconds / furnace. Using a special inner diameter steel tapping port, the steel tapping time is shortened by 1 minute. For finished products, the alloy recovery rate continues to maintain a high level, with a manganese recovery rate of 97% and a silicon recovery rate of more than 93%. The lime consumption and light-burned dolomite consumption have reached 18kg / t and 20kg / t respectively. Moreover, after the transportation of molten iron was changed from three bags to two bags, the transportation time of molten iron was shortened by 15-20 minutes. After the converter is directly converted, the scrap ratio reaches 23%, and the highest reaches 24%. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0012] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0014] Example 1 A production method for reducing costs and increasing efficiency of a large-tonnage converter, wherein the blasting mode is top and bottom mixed blowing, the top blowing and the bottom blowing are performed alternately, and the oxygen supply nozzle for supplying oxygen has a Laval tube-type oxygen supply nozzle.

[0015] Furthermore, the maximum diameter of the cavity of the oxygen supply nozzle is 299 mm, the oxygen supply nozzle is a five-hole nozzle, the throat diameter of the oxygen supply nozzle is 40.2 mm, the outlet diameter of the oxygen supply nozzle is 52.2 mm, and the nozzle angle of the oxygen supply nozzle is 14°.

[0016] Furthermore, air-permeable bricks for bottom blowing are laid at the bottom of the converter. The air-permeable bricks are arranged in an annular seam type. The air-permeable bricks arranged at the bottom of the converter are provided with through air inlet channels surrounding the axis, and the bottom end of the air inlet channel is connected to the blowing equipment.

[0017] Furthermore, the diameter of the steel outlet of the converter is 190 mm.

[0018] Furthermore, the oxygen supply nozzle is a copper nozzle, the oxygen supply nozzle can at least withstand a water pressure of 2.5 MPa, and the forging density of the oxygen supply nozzle is not less than 8.93 g / cm3.

[0019] Among them, the use of a five-hole Laval tube oxygen lance nozzle with a larger throat diameter further improves the oxygen supply intensity and shortens the oxygen blowing time, thereby shortening the smelting cycle. The total time is shortened by more than 1 minute. The blowing process is stable and the slag formation time does not change.

[0020] At the same time, the top and bottom composite blowing process is used to optimize the bottom gas supply mode, improve the later gas supply intensity, strengthen the post-stirring, and further reduce the oxidizability of the molten steel and slag at the end of blowing. It can ensure a large ground gas supply intensity, and the nitrogen and argon gas switch is fast without leakage or cross-talk. The ground air bricks can ensure that they are basically synchronized with the furnace life, ensuring the metallurgical effect of the entire furnace service.

[0021] In this embodiment, the metallurgical effect of the combined blowing process is remarkable, and the performance indicators such as the final slag oxidizability and manganese recovery rate are excellent. According to production data statistics, the final carbon-oxygen product of the molten steel reaches 0.0027-0.0025.

[0022] The tapping process was optimized, the inner diameter of the tapping hole was enlarged to 190mm, and the slag blocking was done well; the tapping hole material was improved to increase the life of the tapping hole. After the improvement, the tapping time was shortened by 40 seconds.

[0023] Example 2 A production method for reducing costs and increasing efficiency of a large-tonnage converter, wherein the blasting mode is top and bottom mixed blowing, the top blowing and the bottom blowing are performed alternately, and the oxygen supply nozzle for supplying oxygen has a Laval tube-type oxygen supply nozzle.

[0024] Furthermore, the maximum diameter of the cavity of the oxygen supply nozzle is 250 mm, the oxygen supply nozzle is a five-hole nozzle, the throat diameter of the oxygen supply nozzle is 29 mm, the outlet diameter of the oxygen supply nozzle is 52.2 mm, and the nozzle angle of the oxygen supply nozzle is 29°.

[0025] Furthermore, air-permeable bricks for bottom blowing are laid at the bottom of the converter. The air-permeable bricks are arranged in an annular seam type. The air-permeable bricks arranged at the bottom of the converter are provided with through air inlet channels surrounding the axis, and the bottom end of the air inlet channel is connected to the blowing equipment.

[0026] Furthermore, the diameter of the steel outlet of the converter is 140 mm.

[0027] Furthermore, the oxygen supply nozzle is a copper nozzle, the oxygen supply nozzle can at least withstand a water pressure of 2.5 MPa, and the forging density of the oxygen supply nozzle is not less than 8.93 g / cm3.

[0028] Example 3 A production method for reducing costs and increasing efficiency of a large-tonnage converter, wherein the blasting mode is top and bottom mixed blowing, the top blowing and the bottom blowing are performed alternately, and the oxygen supply nozzle for supplying oxygen has a Laval tube-type oxygen supply nozzle.

[0029] Furthermore, the maximum diameter of the cavity of the oxygen supply nozzle is 350 mm, the oxygen supply nozzle is a five-hole nozzle, the throat diameter of the oxygen supply nozzle is 50 mm, the outlet diameter of the oxygen supply nozzle is 52.2 mm, and the nozzle angle of the oxygen supply nozzle is 10°.

[0030] Furthermore, air-permeable bricks for bottom blowing are laid at the bottom of the converter. The air-permeable bricks are arranged in an annular seam type. The air-permeable bricks arranged at the bottom of the converter are provided with through air inlet channels surrounding the axis, and the bottom end of the air inlet channel is connected to the blowing equipment.

[0031] Furthermore, the diameter of the steel outlet of the converter is 240 mm.

[0032] Furthermore, the oxygen supply nozzle is a copper nozzle, the oxygen supply nozzle can at least withstand a water pressure of 2.5 MPa, and the forging density of the oxygen supply nozzle is not less than 8.93 g / cm3.

[0033] Compared with Example 1 to Example 3, Example 1 is the most optimized example, wherein, for Example 1, the shortest smelting cycle is 23 minutes, and the single-shift single-furnace production is up to 20 furnaces, with high production efficiency. Moreover, the final carbon-oxygen product of the molten steel is 0.0020-0.0025, which is close to the oxygen balance level of the molten steel, so that high-quality steel can be produced. During operation, the bottom air brick is synchronized with the furnace age, thereby greatly reducing the number of maintenance times and improving the maintenance efficiency, without the need to maintain the furnace body and the bottom air brick separately. A converter drop-type control system is adopted to achieve unequal steel tapping, and the final steel tapping carbon content reaches 0.08%, with an average pass rate of 85%, and the residual manganese in the steel is as high as about 0.25%. Using a special oxygen lance nozzle, the converter oxygen supply time is shortened by 50-70 seconds / furnace. Using a special inner diameter steel tapping port, the steel tapping time is shortened by 1 minute. For finished products, the alloy recovery rate continues to maintain a high level, with a manganese recovery rate of 97% and a silicon recovery rate of more than 93%. The lime consumption and light-burned dolomite consumption have reached 18kg / t and 20kg / t respectively. Moreover, after the transportation of molten iron was changed from three bags to two bags, the transportation time of molten iron was shortened by 15-20 minutes. After the converter is directly converted, the scrap ratio reaches 23%, and the highest reaches 24%.

[0034] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A large-tonnage converter cost reduction and efficiency improvement production method, characterized in that: The blowing mode is top and bottom mixed blowing, and the top blowing and the bottom blowing are performed alternately. The oxygen supply nozzle used for oxygen supply has a Laval tube type oxygen supply nozzle.

2. A large-tonnage converter cost reduction and efficiency improvement production method according to claim 1, characterized in that: The maximum diameter of the cavity of the oxygen supply nozzle is 299 mm, the oxygen supply nozzle is a five-hole nozzle, the throat diameter of the oxygen supply nozzle is 40.2 mm, the outlet diameter of the oxygen supply nozzle is 52.2 mm, and the spray hole angle of the oxygen supply nozzle is 14°.

3. The method for reducing costs and increasing efficiency of a large-tonnage converter according to claim 1 is characterized in that: Air-permeable bricks for bottom blowing are laid at the bottom of the converter. The air-permeable bricks are arranged in an annular seam manner. A through air inlet channel surrounding the axis is distributed on the air-permeable bricks at the bottom of the converter. The bottom end of the air inlet channel is connected to the blowing equipment.

4. The method for reducing costs and increasing efficiency of a large-tonnage converter according to claim 1 is characterized in that: The diameter of the tapping port of the converter is 190 mm.

5. The method for reducing costs and increasing efficiency of a large-tonnage converter according to claim 1 is characterized in that: The oxygen supply nozzle is a copper nozzle, which can withstand a water pressure of at least 2.5 MPa, and the forging density of the oxygen supply nozzle is not less than 8.93 g / cm 3 .