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Method for producing low-phosphorus steel or extremely low-phosphorus steel by using limestone slag-single slag method

A limestone and low-phosphorus steel technology, applied in the field of steelmaking, can solve the problems of excessive energy and material consumption, slow lime melting speed, and increased environmental pollution, and achieve the effects of saving resources and energy, good smelting effect, and high-efficiency dephosphorization

Active Publication Date: 2020-01-10
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the phosphorus content of molten iron used in steelmaking converters ranges from 0.08 to 0.20%, the carbon content is 3.9 to 5.0%, the silicon content is 0.15 to 0.85%, and the temperature range is 1250 to 1450 ° C. Lime is used for dephosphorization to make double slag or multiple slag. What's more, the dual steelmaking method is used, that is, pre-dephosphorization and slag removal in the converter or other molten iron containers (pre-dephosphorization of molten iron), and then the molten iron is mixed into the converter for secondary dephosphorization and decarburization, but due to The melting speed of lime is slow, it is difficult to form slag, and the temperature drop of slag is small, it is difficult to remove phosphorus from molten iron to low-phosphorus steel (0.01%≥[P]>0.005) or extremely low-phosphorus steel ([P]≤0.005%) level, but the consumption of energy and materials has paid too much, increasing environmental pollution

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] 120 tons of converter, the temperature of molten iron is 1300℃, the phosphorus content is 0.20%, the carbon content is 4.1%, limestone is added in 4 batches to make slag, and the weight of each batch is 1 / 2 to 1 / 8 of the total. Operate until 5 minutes before the end point, the final slag alkalinity is controlled to 5.3, and the oxygen lance position before the end point is controlled to adjust the furnace atmosphere within 50% of the decarburization lance position. The average oxygen consumption per ton of steel is 52 cubic meters. After blowing oxygen for 17 minutes, the oxygen supply strength is 3.06 cubic meters per minute·ton steel, the end point carbon content is 0.03%, and the phosphorus content is 0.004%, reaching the level of extremely low phosphorus steel. The temperature of tapping molten steel is 1610℃.

Embodiment 2

[0022] A 60-ton converter, the molten iron temperature is 1330℃, the phosphorus content is 0.15%, the carbon content is 4.3%, limestone is added in 8 batches to make slag, and the weight of each batch is 1 / 4 to 1 / 15 of the total. Operate until 3 minutes before the end point, the final slag alkalinity is controlled to 4.6, and the oxygen lance position before the end point is controlled to adjust the furnace atmosphere within 50% of the decarburization lance position. The average oxygen consumption per ton of steel is 53 cubic meters. After blowing oxygen for 14 minutes, the oxygen supply intensity is 3.79 cubic meters per minute per ton of steel, the slag temperature measurement result is 1550 degrees, the end point carbon content is 0.02%, and the phosphorus content is 0.006%, reaching the level of low-phosphorus steel. The temperature of tapping molten steel is 1640℃.

Embodiment 3

[0024] A 30-ton converter is charged with molten iron at a temperature of 1350°C, with a phosphorus content of 0.11% and a carbon content of 4.6%. Limestone is added in 13 batches to make slag. The weight of each batch is 1 / 6 to 1 / 20 of the total. Before the end, the oxygen lance position before the end point is controlled within 50% of the decarburization lance position to adjust the furnace atmosphere. The average oxygen consumption per ton of steel is 55 cubic meters, oxygen blowing for 12 minutes, and the oxygen supply intensity is 4.58 cubic meters. / Min·ton steel, the final slag alkalinity is controlled to 3.8, the end point carbon content is 0.10%, and the phosphorus content is 0.01%, reaching the level of low-phosphorus steel. The temperature of tapping molten steel is 1670℃.

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Abstract

The invention provides a method for producing low phosphorus steel or extra-low phosphorus steel by using a limestone slagging-single slagging method, and belongs to the technical field of steelmaking. The method for producing low phosphorus steel or extra-low phosphorus steel by using the limestone slagging-single slagging comprises the steps that when slagging is conducted by using limestone, the oxygen consumption range of ton steel is controlled in 40-65 cubic meters, and the total adding amount of ton steel, the limestone and dolomite is 40-100 kg; the dolomite is about 1 / 4-1 / 5, accordingto converter capacity, the oxygen supplying intensity is controlled at 2-5 cubic meter / cent.ton steel, the alkalinity of final slag is controlled at 3. 0-6. 0, and the oxygen lance position is controlled within about 50% range of the decarbonization gun position; the furnace atmosphere is adjusted, the molten slag temperature is controlled between 1450-1630 DEG C, the adding batch of the limestone is controlled at 2-20 times, the eight of each batch of limestone is 30-0.5 kg / ton steel, and molten iron can be efficiently dephosphorized; and the single slagging method can produce low phosphorussteel or extra-low phosphorus steel. According to the method for producing low phosphorus steel or extra-low phosphorus steel by using the limestone slagging-single slagging, the goal of dephosphorization can be achieved by easy operating, resources and energy can also be reduced, and workers easily master the method for producing low phosphorus steel or extra-low phosphorus steel by using the limestone slagging-single slagging.

Description

Technical field [0001] The invention relates to the technical field of steelmaking, in particular to a method for producing low-phosphorus steel or extremely low-phosphorus steel by using limestone slagging-single slag method. Background technique [0002] It is difficult to produce low-phosphorus steel or very low-phosphorus steel by using lime slag for molten iron steelmaking. At present, the molten iron used for steelmaking converters has a phosphorus content of 0.08~0.20%, a carbon content of 3.9~5.0%, a silicon content of 0.15~0.85%, and a temperature range of 1250~1450℃. The dephosphorization adopts lime to make double slag or multiple slag. What's more, the double steelmaking method is used, that is, the pre-dephosphorization and slag removal (pre-dephosphorization of molten iron) in the converter or other molten iron containers, and then the molten iron is poured into the converter for secondary dephosphorization and decarburization. Lime has a slow melting speed and is ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21C5/36
CPCY02P10/20
Inventor 李宏
Owner UNIV OF SCI & TECH BEIJING
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