Production method for smelting low-phosphorus steel from vanadium-containing molten iron

Abstract

The invention relates to the technical field of metallurgy, and particularly discloses a production method for smelting low-phosphorus steel from vanadium-containing molten iron. The production methodcomprises the following steps of carrying out desulfurization pretreatment on the vanadium-containing molten iron; feeding the desulfurized vanadium-containing molten iron into a dephosphorizing converter, adding a calcium dephosphorizing agent for dephosphorizing, and pouring out slag; carrying out coarse oxygen vanadium extraction on the dephosphorized vanadium-containing molten iron; and feeding semisteel into the dephosphorizing converter after deslagging for decarburization treatment, and conducting steel tapping. In the steel tapping process, small-particle lime and low-silicon refiningslag are added along with deoxidized alloy materials, and slag is reserved after steel tapping. According to the production method provided by the invention, desulfurization pretreatment is firstly carried out, then the alkalinity and oxidability of the slag are adjusted by utilizing the calcium dephosphorizing agent, the fluidity of the slag is improved, phosphorus is converted into 3CaO.P2O5 or4CaO.P2O5, the dephosphorizing efficiency is improved, vanadium extraction and decarburization are carried out after dephosphorizing, the grade of vanadium slag can be improved, residual vanadium inthe semisteel is reduced, the difficulty of smelting the low-phosphorus steel from the vanadium-containing molten iron is greatly reduced, and the low-phosphorus steel of which P is less than or equalto 0.005% is obtained.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a production method for smelting low-phosphorus steel from vanadium-containing molten iron. Background technique [0002] Phosphorus is a harmful element in steel. It is easy to segregate at the grain boundary, causing the steel to be "cold and brittle", significantly reducing the low-temperature impact toughness of the steel, and causing low-temperature brittleness and temper brittleness of the steel. High-grade high-quality steel has increasingly strict requirements on phosphorus content, especially for high-grade steel such as low-temperature steel, marine steel, and hydrogen-induced cracking-resistant steel. Require. With the increasing market demand for high-grade high-quality steel, low-phosphorus steel and ultra-low-phosphorus steel, as an indispensable part of the pure steel production process, have received more and more attention. Phosphorus content has become one ...

AI Technical Summary

Problems solved by technology

[0003] However, at present, when low-phosphorus steel is smelted with vanadium-extracted semi-steel, due to the lack of slag-forming elements such as silicon and manganese in the semi-steel, there are problems such as difficulty in slagging in the early stage and low dephosphorization rate. In order to solve this problem, the converter The method of adding SiC, bauxite or leaving slag is often used for rapid dephosphorization to increase the dephosphorization rate. However, due to the high cost of SiC and bauxite, which directly affects the price of finished products, conventional converter steelmaking methods have been difficult to organize at low cost. Production

Therefore, the slag-retaining operation is mostly used at present, but the effect of only slag-retaining operation is not good, and it is difficult to stably produce low-phosphorus steel