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Effect of Oxygen Potential on De-Si and De-P during Hot Metal Pretreatment

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Abstract

The effect of oxygen potential on De-Si and De-P, and initial [Si] content on De-P during hot metal pretreatment were studied by Fe2O3-CaO-CaF2 slag. The results showed that the final [Si] content of 0.144 %-0. 090 % can be reached if the oxygen potential is controlled in the range 1. 64×10-4% to 3. 26×10-4%; when initial [Si] content in hot metal is lower than 0.15 %, the De-P ratio of 85 % and 80 % were obtained by controlling oxygen potential higher than 1. 7×10-4% at 1 573 K and 5. 5×10-4% at 1 623 K respectively, but the final [P] content was a little higher in later case. The optimum initial [Si] content is 0.10 % to 0.15 %.

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The change law of oxygen activity was studied by using Fe 2O 3-CaO-CaF 2 and Na 2CO 3/Na 2SO 4 fluxes under laboratory conditions. At the same time, the range of oxygen activity which is in favour of removing phosphorus and sulphur simultaneously was also investigated. The results showed that the oxygen activity in the iron melt during de-phosphorization can reach up to 5.91×10 -6-10.03×10 -6 in about 5 min and then only varies within a narrow range. A final phosphorus content of 0.008% and a final sulphur content of 0.003% can be obtained if the oxygen activity is controlled within the range of 4.5×10 -6-8.0×10 -6.
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