Method for producing ultra-low phosphorus steel by using premelted calcium ferrite to refine molten steel outdoors by RH process

A technology for out-of-furnace refining and ultra-low phosphorus steel, applied in the field of metallurgy, can solve the problems of inability to fully utilize the productivity of the converter, long smelting time, and reduction in the amount of scrap steel, achieve stable dephosphorization efficiency, reduce smelting intensity, and reduce oxygen consumption effect

Inactive Publication Date: 2013-01-16
LIAONING TIANHE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, most steel mills adopt the "double slag method", that is, two slag making methods are used in the converter smelting; or the "duplex method", that is, the molten iron is smelted in one converter for half the time and then poured into another converter to continue smelting. The disadvantages of these two methods are that the process is complex, the smelting time is long, and the productivity of the converter cannot be fully utilized.
Another way is to carry out "three removals" on molten iron in advance, that is, desiliconization, desulfurization, and dephosphorization. For example, Japanese iron and steel enterprises have the disadvantages of requiring more equipment, large investment, complicated process, and large heat loss. The temperature of molten iron after "three removals" is low, which greatly reduces the amount of steel scrap added during converter smelting
Therefore, in order to produce these low-phosphorus and ultra-low-phosphorus steels, conventional converter smelting methods can no longer meet the phosphorus requirements of these steel types, so it is necessary to study the method of assisting dephosphorization by refining outside the furnace, so as to realize the production of ultra-low phosphorus steels

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] After the converter smelting is completed, the phosphorus content at the end of the converter is controlled below 0.03%, the tapping temperature is controlled at about 1590°C, the molten steel is not deoxidized during the tapping process, and slag blocking treatment is used during the tapping process; The ladle is transported to the RH refining station, the RH immersion tube is lowered, and the vacuum operation is carried out, the vacuum degree is controlled at 150Pa, and then the gas inlet is lifted from the immersion tube to feed Ar at a flow rate of 150NL / min, and then the powder is sprayed by lowering from the top of the RH vacuum chamber Gun, spray pre-melted calcium ferrite powder into the molten steel flowing through the vacuum chamber from the powder spray gun. It is Ar, the conveying gas pressure is controlled at 0.2MPa, the conveying rate of the powder is 1-2Kg / s, the net circulation time of the molten steel after powder spraying is controlled at 8-10min, and t...

Embodiment 2

[0036]After the converter smelting is completed, the phosphorus content at the end of the converter is controlled below 0.03%, the tapping temperature is controlled at about 1630°C, the molten steel is not deoxidized during the tapping process, and slag blocking treatment is used during the tapping process; The ladle is transported to the RH refining station, the RH immersion tube is lowered, and the vacuum operation is carried out, the vacuum degree is controlled at 300Pa, and then the gas inlet is lifted from the immersion tube to feed Ar at a flow rate of 800NL / min, and then the powder is sprayed by lowering from the top of the RH vacuum chamber Spray the pre-melted calcium ferrite powder from the powder spray gun to the molten steel flowing through the vacuum chamber. It is Ar, the conveying gas pressure is controlled at 0.5MPa, the conveying rate of the powder is about 4Kg / s, the net circulation time of the molten steel after powder spraying is controlled at 5-7min, and th...

Embodiment 3

[0038] After the converter smelting is completed, the phosphorus content at the end of the converter is controlled below 0.03%, the tapping temperature is controlled at about 1650°C, the molten steel is not deoxidized during the tapping process, and slag blocking treatment is used during the tapping process; The ladle is transported to the RH refining station, the RH immersion tube is lowered, and the vacuum operation is carried out, the vacuum degree is controlled at 500Pa, and then the gas inlet is lifted from the immersion tube to feed Ar at a flow rate of 1200NL / min, and then the powder is sprayed by lowering from the top of the RH vacuum chamber Spray the pre-melted calcium ferrite powder from the powder spray gun to the molten steel flowing through the vacuum chamber. It is Ar, the delivery gas pressure is controlled at 1MPa, the delivery rate of the powder is 5-6Kg / s, the net circulation time of the molten steel after powder spraying is controlled at 3-5min, and then the...

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Abstract

The invention provides a method for producing ultra-low phosphorus steel by using premelted calcium ferrite to refine molten steel outdoors by RH process, mainly comprising the following steps: tapping steel from a converter, dephosphorize deeply by using the vacuum spraying premelted calcium ferrite powder in a refining furnace by the RH process, slagging, adjusting temperature, stirring, deoxidizing, refining, alloying and casting continuously. By using the method to dephosphorize deeply, the dephosphorization rate can be more than 80%, the content of phosphorus in the molten steel is controlled below 0.003% stably, the dephosphorization efficiency is high and stable, the smelting intensity of the converter is reduced, the service life of the converter is prolonged, the consumption of lime, oxygen and iron and steel materials is reduced, the electric energy is saved, and the metal yield is improved.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and is used for removing phosphorus in steel by applying pre-melted calcium ferrite in the refining process outside the furnace, especially applying pre-melted calcium ferrite in RH (abbreviation of Ruhstahlhausen Process, steelmaking process) A method for producing ultra-low phosphorus steel during the external refining process of molten steel in a refining furnace. Background technique [0002] Phosphorus is usually a harmful element in steel, because the segregation of phosphorus in steel is relatively serious, which deteriorates the toughness of steel and produces "cold brittleness", especially at low temperature conditions, it is more likely to occur "cold brittleness". Phosphorus segregation can also cause anisotropy of steel, reduce welding performance, and cause corrosion fatigue of stainless steel, so it must be strictly controlled. In traditional technology, the phosphorus in steel ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/064C21C7/10
Inventor 陈云天
Owner LIAONING TIANHE TECH
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