Removing metallic impurities from ferrosilicon alloy by Ar-O₂ gas blowing

Abstract

Ferrosilicon alloy is widely used as alloying agent and deoxidizer in the steelmaking process, which containing the metallic impurities of Al, Ca, and Ti would directly affect the cleanliness of the molten steel. Therefore, metallic impurities from the ferrosilicon alloy removed by the top blowing Ar-O2 gas was carried out. The morphology, composition, and area fraction of impurity phases of metallic impurities in the ferrosilicon alloy were compared before and after Ar-O2 gas blowing treatment by automatic scanning electron microscopy, and contents of metallic impurities were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results show that a large amount of metallic impurity phases precipitate in the ferrosilicon alloy raw material, which mainly contain Al, Ca, and Ti impurities, and their contents are 1.11% (mass fraction, the same below), 0.31% and 0.11%, respectively. After blowing Ar-O2 gas for 5 minutes, contents of Al and Ca are dropped sharply to 0.66% and 0.13%, respectively. After blowing Ar-O2 gas from 45 minutes, the removal rate of impurity elements is slowed down and the refining reaction tends to reach equilibrium. After 120 minutes of blowing Ar-O2 gas, contents of Al, Ca and Ti are 0.42%, 0.014% and 0.094%, respectively; meanwhile the removal efficiency of Al, Ca and Ti are 62.16%, 95.48% and 14.54%, respectively. The refining method of blowing Ar-O2gas can effectively remove impurity elements of Al and Ca in the ferrosilicon alloy, while no significant change in Ti content is found.

Keywords

• ferrosilicon alloy
• purification
• removal efficiency
• ar-o₂ gas
• impurity phase