To resolve the difficulty in slag formation during steelmaking with low silicon hot metal and to increase productivity, a new five-hole lance was developed by increasing oxygen flow rate from 50000 m~3/h to 60000 m~3/h. The five-hole lance has been found to be more effective for slag formation because of the increase in the oxygen flow rate by 20%, nozzle angle by 1 ° and stirring energy by 8%. Synthetic slag was added to adjust the slag composition. The dephosphorization was improved by slag modification with synthetic slag, sand, and others to promote the lime solution and to increase slag volume. The average end phosphorus content in the study was 0.0116%, 0.0024% lower than that with a four-hole lance. For steelmaking with de-S, de-Si, de-P pretreated hot metal, the end phosphorus content was lower than 0.007%, with a minimum of 0.004%. Thus, the pretreated hot metal is suitable for low-phosphorus steel production. The oxygen blowing period was reduced by 1.38 minutes on average for heats (300t/heat) blown with five-hole lance, and the metal yield per ton steel was increased by 1.0 - 1.5 kg due to less splashing. The problems such as difficulty in dephosphorization and slag adhesion on oxygen lance and hood were settled.
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