Abstract: A slide gate plate throttling mechanism for the continuous casting of molten metal includes a gate plate assembly. The gate plate assembly is connected to an upper nozzle disposed below a vessel for containing molten metal and is disposed above an elongated lower nozzle that directs flow of molten metal. Each plate of the gate plate assembly includes an opening that forms a portion of a passageway for the molten metal. The gate plate assembly comprises a gate plate that is moved so as to open and close the passageway, a lower plate connected to an upper surface of the nozzle, and a groove disposed in a bottom surface of the lower plate around the lower plate opening. The mechanism further comprises at least one control device for regulating flow of inert gas and graphite into the groove. The system may include a device for measuring back pressure in the groove to determine when to seal the groove by injecting graphite therein.