Method for controlling nitrogen content in lf refining furnace smelting process

Abstract

The invention discloses a method for controlling the nitrogen content in the smelting process of an LF refining furnace, which comprises the following steps: (1) removing oxygen in molten steel and top slag from the molten steel in the LF refining furnace, and adjusting the argon gas flow rate to 250-300L / min , the stirring and desulfurization time is 3-5min, and the diameter of the blown slag surface is 400-500mm; (2) The actual bottom blowing argon gas control during the power transmission and temperature raising process: the blown slag diameter is 170mm≤D≤220mm; (3) The power transmission and temperature increase In the process of slagging, add 0.2-0.3kg / t steel molten steel deoxidizer every 2-3 minutes, and the molten steel deoxidizer contains CaC 2 Above 60%; (4) Reduce the carbon, silicon, manganese, and aluminum components in the steel, adjust the number of times 1-2 times, so that the number of large-area exposure of molten steel is reduced to 1 time; (5) Adjust the blowing before feeding the pure calcium wire The diameter of the top slag surface is 0-50mm, feed the line for 30S, stop for 10S, then feed the line for 30S, stop for 10S, until the end of the line feeding. The invention adopts strengthened molten steel and top slag deoxidation, reduces the argon flow stirring desulfurization time, reduces the consumption of argon gas per ton of steel, reduces the aluminum loss in the molten steel, controls the amount of nitrogen added in the smelting process, and satisfies the nitrogen content of the finished molten steel. High-quality steel nitrogen content requirements.

Description

technical field [0001] The invention belongs to the technical field of steelmaking, in particular to a method for controlling nitrogen content in the smelting process of an LF refining furnace. Background technique [0002] The control of nitrogen in 120t molten steel has always been a difficult problem. Not only has many furnaces been downgraded and changed due to excessive nitrogen content, but also excessive nitrogen content in the molten steel will also affect the quality of the steel. Therefore, how to effectively control the steel To reduce the nitrogen content in the liquid so that the nitrogen content in the steel meets the nitrogen content requirements of high-quality steel, an effective method must be found. The original nitrogen control method is: (1) the deoxidation of the top slag is not complete, and the desulfurization of the large argon flow is carried out; (2) the actual bottom blowing argon control during the power transmission and temperature raising proce...

AI Technical Summary

Problems solved by technology

[0002] The control of nitrogen in 120t molten steel has always been a difficult problem. Not only has many furnaces been downgraded and changed due to excessive nitrogen content, but also excessive nitrogen content in the molten steel will also affect the quality of the steel. Therefore, how to effectively control the steel Nitrogen content in the liquid, so that the nitrogen content in the steel meets the nitrogen content requirements of high-quality steel, an effective method must be found

The original nitrogen control method is: (1) the deoxidation of the top slag is not complete, and the desulfurization of the large argon flow is carried out; (2) the actual bottom blowing argon control during the power transmission and temperature raising process: the diameter of the exposed surface of the molten steel is 300mm≤D≤450mm; (3 ) The submerged arc effect is poor during power transmission; (4) The number of component adjustments is 3 to 5 times; (5) The area of ​​the slag surface is large by argon blowing during the wire feeding process, and the diameter of the exposed surface is about 200mm; according to the original nitrogen control method, The effect is as follows: (1) Because the top slag deoxidation is not complete, the stirring desulfurization time of large argon gas flow is long, an average of 6 minutes. Although the sulfur can be desulfurized to the required level, the argon consumption is relatively high, and the argon gas consumption per unit is 0.078 Nm 3 / t, and the loss of aluminum components in molten steel is serious, with an aluminum loss of 0.008% per minute, and the risk of nodulation is also increased; (2) Due to the large flow control of argon gas during the power transmission and temperature raising process, the molten steel is in contact with air, resulting in steel (3) Due to the poor gas permeability of the top slag and the poor submerged arc effect, the transfer of nitrogen in the air to the molten steel is accelerated; (4) The frequent adjustment of the composition leads to an increase in the exposure of the molten steel, which increases the The risk of nitrogen absorption; (5) Feeding pure calcium wire, the flow of argon gas is relatively large during the wire feeding process, which leads to intensified splashing and aggravates the increase of nitrogen in molten steel