Method for smelting high-phosphorus steel by low-temperature low-silicon molten iron in converter

Abstract

The invention discloses a method for smelting high-phosphorus steel by low-temperature low-silicon molten iron in a converter. The method comprises the following steps that: scrap steel is added into the converter; active lime is added in the converter for the first time, and an oxygen lance, the position of which is lower than the normal position for 10-20 centimeters, blows oxygen; after the oxygen blowing is performed for 50-60 seconds, dolomite is added into the converter at one time; when the oxygen blowing is performed for 90-110 seconds, the oxygen lance is lifted to the normal oxygen blowing position, and active lime is added into the converter again; and tapping is carried out. The method fully utilizes the conditions of the low-temperature low-silicon molten iron in reducing a phosphorus removal rate to smelt the high-phosphorus steel, the phosphorus removal rate can be reduced to 40%-50% from the above 85% of the current conventional smelting, and thus the phosphorus content of the smelting at the end point is effectively improved; the lime addition amount is reduced to be not over 25Kg/ton of steel from 40Kg-60Kg/ton of steel, and the usage amount of phosphorus alloy can also be reduced; the waste residue discharge can be reduced; and moreover, a fluorite slagging agent is not used, and thus the environmental burden can be relieved.

Description

technical field [0001] The invention relates to metal smelting, and specifically belongs to a method for smelting high-phosphorus steel in a converter by using low-temperature low-silicon molten iron, which is suitable for smelting in a converter of more than 50 tons. Background technique [0002] For the iron and steel metallurgical process with blast furnace-converter-extra-furnace refining as the core process, the appropriate temperature and composition of molten iron in the blast furnace are the basis for ensuring the smooth flow of the process. However, as the sources of raw materials for iron and steel enterprises are increasingly diversified and the pressure of cost control is increasing, the temperature and composition of molten iron produced by blast furnace smelting fluctuate significantly, and the frequency is gradually increasing, especially in the condition of low-temperature and low-silicon molten iron. Higher requirements are put forward for converter smelting...

AI Technical Summary

Problems solved by technology

First of all, due to the serious low temperature of the furnace, it may be difficult to slag in the early stage; secondly, due to the decrease in the silicon content of the molten iron, in order to create a slag with a suitable alkalinity, the corresponding amount of slag such as lime is reduced, and the proportion of slag and steel is reduced. When the basicity of the final slag remains stable and the end point temperature meets the smelting requirements, the phosphorus distribution ratio of slag to steel does not change much, and the dephosphorization rate directly decreases accordingly. Therefore, when using low temperature and low silicon molten iron as raw material to smelt conventional steel , the control of dephosphorization effect is one of the biggest difficulties

[0004] At present, when using low-temperature low-silicon molten iron as raw material to smelt ordinary steel, there are many ways to deal with it. Basically, the direction of control is to make the smelting end-point components, especially phosphorus content, end point temperature, etc. are equivalent to conventional smelting conditions, and maintaining a high dephosphorization rate and ensuring low-phosphorus tapping (generally requiring phosphorus in molten steel ≤ 0.02%) are the core control objectives, but due to low-temperature and low-silicon raw material conditions The extreme characteristics of the converter bring more difficulties to the converter smelting process and the control of the end point. The overall end point temperature and component hit rate are lower than those of conventional smelting conditions.