| 摘要 |
PROBLEM TO BE SOLVED: To provide a preliminary treatment method which executes both a desiliconization treatment and a dephosphorization treatment of molten ion efficiently by using a single revolving furnace.SOLUTION: In a preliminary treatment comprising desiliconizing and then dephosphorizing molten iron in a single revolving furnace, molten iron is subjected to a preliminary treatment by selecting one of the following refining patterns 1-4 according to the silicon content of molten iron used in charge, presence or absence of residual dephosphorization slag of the charge in the furnace, the amount of residual slag in a middle slag-discharging step and the phosphorus content of the molten iron after dephosphorization. Refining pattern 1: a refining method of carrying out desiliconization, dephosphorization, tapping and charge of the next-charge molten iron without discharging the dephosphorization slag, in this order. Refining pattern 2: a refining method of carrying out desiliconization, middle slag discharge, dephosphorization, tapping and charge of the next-charge molten iron without discharging the dephosphorization slag, in this order. Refining pattern 3: a refining method of carrying out desiliconization, middle slag discharge, dephosphorization, tapping, slag discharge and charge of the next-charge molten iron, in this order. Refining pattern 4: a method of carrying out desiliconization, tapping, slat discharge and charge of the next-charge molten iron, in this order. |
