Argon-oxygen refining method for low-carbon ferrochromium alloy

Abstract

The invention provides an argon oxygen refining method for refining high-carbon ferrochromium alloy to low-carbon ferrochromium alloy. In the method, the molten ferrochromium alloy is refined at a higher temperature by adjusting the oxygen content of top-blown argon (nitrogen) / oxygen mixed gas, so that decarburization efficiency is improved and the loss of chromium is reduced; the carbon content (wt%) of the refined ferrochromium alloy is less than 0.25%, the loss of the chromium is 6%-8% (wt%), and the invention provides a proposal for the 'spraying-splashing' phenomenon appeared during high-temperature refining of the molten ferrochromium alloy and for decarburization and chromium protection during cooling. By adopting temperature control for refining the ferrochromium alloy, the method is beneficial to realizing on-line automatic control and has the advantages of short refining time, simple production process and easy operation.

Description

technical field [0001] The invention relates to a method for reducing carbon in high-carbon and high-chromium alloys, in particular to a method for refining high-carbon ferrochrome alloys into low-carbon ferrochrome alloys. Background technique [0002] Low-carbon ferrochrome alloy is an important raw material for smelting special steel and ultra-low-carbon alloy structural steel. The lower its carbon content and the higher its chromium content, the higher its economic value and use value. [0003] At present, the methods for smelting low-carbon ferrochrome alloys are mainly three-step method and "Perrin method". Carbon ferrochrome alloy is used as raw material to produce silicon chromium alloy, and then silicon chromium alloy is used as raw material to produce low carbon ferrochrome alloy, thereby obtaining low carbon ferrochrome alloy with carbon content (wt.%) lower than 0.5%. The disadvantage of this kind of method is that the process is long, the power consumption is h...

AI Technical Summary

Problems solved by technology

Specifically: 1) a large amount of oxygen blowing is required for decarburization because of the high carbon content in the high carbon ferrochrome alloy melt; 2) the chromium in the high carbon ferrochrome alloy melt is much higher than that in the chromium series stainless steel melt It is easy to be oxidized when blowing oxygen; 3) The chromium content in the high-carbon ferrochromium alloy melt is high, and the melt density is high, so the viscosity and surface tension of the melt and the slag liquid containing chromium oxide on the surface of the melt are relatively large, which is It is necessary to increase the amount of top-blown gas and the pressure of top-blown gas (or increase the gas flow rate), so that the oxygen in the gas can penetrate deep into the ferrochromium alloy melt and fully contact with carbon; 4) A large amount of top-blown oxygen will undergo violent oxidation with carbon Reaction, the generation of a large amount of reaction gas will easily increase the gas content of the viscous ferrochrome alloy melt and slag rapidly and cause boiling, resulting in "splash" accidents

Reducing the amount and pressure of top-blown oxygen can avoid and reduce its "splash", but it will make it difficult for top-blown oxygen to rush into the viscous slag liquid and ferrochrome melt, making it difficult to reduce carbon

[0014] The current converter can be equipped with top and bottom double-blowing mixed gas device after modification, which is basically suitable for refining high-carbon ferrochrome alloy, but the furnace mouth of the converter is relatively low. The ferrochrome alloy melt and slag overflow the furnace mouth, causing losses

[0015] The structure of the current AOD furnace is mainly designed for the refining of stainless steel with low carbon and chromium content. If it is used for the refining of high-carbon ferrochrome alloy, it will not be ideal. The mouth is narrow and small. When the amount of reaction gas is large, especially when boiling occurs, the gas in the furnace will be difficult to discharge and the gas pressure will increase, which is not conducive to the oxidation reaction of carbon, and will make the melt and slag liquid high speed splash

Therefore, the use of AOD furnace to refine ferrochrome alloys will affect the rapid decarburization because the flow and pressure of top-blown oxygen cannot be increased.