System and method for minimizing slag carryover during the tapping of a BOF converter in the production of steel

A basic oxygen furnace (BOF) system for use in the manufacture of steel, the BOF system comprising:

• a BOF converter for holding molten steel and molten slag, the molten slag floating on top of the molten steel, said BOF converter including a tap hole defined therein for enabling the molten steel to flow therefrom;
• a ladle positioned at a vertical elevation below the BOF converter for receiving molten steel which flows from the BOF converter via the tap hole in a tap stream;
• an infrared (IR) imaging device for imaging the tap stream of molten steel and molten slag flowing from the tap hole in the converter into the ladle in order to detect the presence of slag in the tap stream;
• and
• wherein the IR imaging device uses IR wavelengths of at least about 8 .mu.m in order to detect the presence of slag in the tap stream.

A method of pouring molten metal from a steel-making vessel into a ladle during the manufacture of steel, the method comprising the steps of:

• providing a steel-making vessel holding a volume of molten metal, the molten metal including molten steel and molten slag;
• providing an IR imaging camera for monitoring a stream of molten metal flowing from the vessel into the ladle;
• causing molten metal to flow in the stream out of the vessel through a hole defined therein, and downward into the ladle;
• monitoring the stream with the IR imaging camera using IR wavelengths between about 8 and 14 .mu.m so that emissivity differences in the stream between molten steel and molten slag are displayed on a corresponding monitor;
• viewing the monitor in order to determine when a substantial amount of slag enters the stream;
• and
• observing a substantial change in color in the stream on the monitor which indicates a substantial amount of slag in the stream flowing from the vessel into the ladle, and the operator in response thereto stopping the pouring of the molten metal and minimizing slag carryover into the ladle.

A system for determining when molten slag is present in substantial amounts in a BOF-to-ladle tap stream, the system comprising:

• a BOF having at least one tap hole defined therein;
• a ladle located at an elevation below the BOF;
• a housing within which an imaging device is positioned, said imaging device for imaging the BOF-to-ladle tap stream in order to determine when molten slag is present therein in substantial amounts;
• and
• a window defined in said housing, said window being at least about 95% transparent to long infrared (IR) wavelengths, and wherein said imaging device images said tap stream through said window.

A steel-making apparatus comprising:

• a steel-making vessel for holding molten hot metal including slag and steel;
• an opening in said vessel for allowing the molten hot metal to flow from said vessel downward into a ladle by way of a stream of the hot metal;
• an infrared (IR) imaging device for imaging the stream of hot metal flowing between the opening and the ladle in order to detect the presence of slag in the stream;
• and
• wherein the IR imaging device used IR wavelengths of at least about 8 um in order to detect the presence of slag in the tap stream.