Double-slag process for smelting ultralow-phosphorus and low-carbon steel in combined-blown converter

Abstract

The invention relates to a double-slag process for smelting ultralow-phosphorus and low-carbon steel in a combined-blown converter. The double-slag process comprises the following steps: (1) molten iron and waste steel are put into the converter according to the molten iron ratio of 85% to 90%; (2) bottom blowing gas adopts nitrogen and argon in a switched manner, the nitrogen is adopted before the supply of 80% of oxygen, and the argon is automatically switched after the supply of 80%t of oxygen; (3) at the first stage of blowing, the flow rate of the oxygen adopts 20000-21000 Nm<3> / h within the first minute, and a normalized slag lance position of 1800-2000 mm is adopted; after the start of blowing for one minute, the flow rate of the oxygen is adjusted to be 13000 Nm<3> / h; (4) a de-slagging moment is set as 8-10 minutes after the start of blowing; (5) at the second stage of blowing, blowing is started when the high lance position is 1700-1800 mm, the flow rate of the oxygen is adjusted to be 18000 Nm<3> / h, and the converter end point control target is that carbon is less than 0.05%, and phosphorus is less than 0.004%. According to the double-slag process provided by the invention, the converter end point phosphorus can be stably controlled to be less than or equal to 0.004 percent, so that the target of smelting the ultralow-phosphorus and low-carbon steel by a single converter is stably realized.

Description

technical field [0001] The invention belongs to the technical field of smelting ultra-low phosphorus and low-carbon steel by a combined blowing converter, and in particular relates to a double slag process for smelting ultra-low phosphorus and low carbon steel by a combined blowing converter. Background technique [0002] The removal of impurity elements and the control of inclusions in steel have always been the most concerned issues for metallurgists. Phosphorus can significantly reduce the low-temperature impact toughness of steel, increase the ductile-brittle transition temperature of steel, make steel cold and brittle, and deteriorate welding performance. One of the first tasks of high-grade steel grades. For enterprises using converter steelmaking, dephosphorization is mainly completed in the converter process, so dephosphorization is the main task of converter smelting. [0003] For low-phosphorus steel grades, the deep dephosphorization process is required in the c...

AI Technical Summary

Problems solved by technology

The duplex method is stable in production and has a short smelting cycle, but it has high requirements for supporting process equipment and requires renovation of plant equipment, so many enterprises cannot adopt this method