Method and device for treating a metal or a molten metal alloy using an addition agent

1. A process for treating a molten metal or metal alloy using an additive agent, comprising:

depositing the additive agent in at least one local cavity made in a bottom of a treatment ladle and delimited by a low annular wall that protrudes with respect to the bottom;

lowering down to a bottom position at least one closure member comprising a closure bell so that the closure bell surrounds, at a distance, the low annular wall and so that a frontal edge of the closure bell bears against the bottom of the treatment ladle, creating an annular bearing zone around and at a distance from the low annular wall and that is located below an upper edge of the low annular wall, forming a chamber that includes the at least one local cavity;

at least partially filling the treatment ladle with the molten metal or metal alloy; and

raising the at least one closure member so as to bring the molten metal or metal alloy and the additive agent into contact.

2. An application of the process as claimed in claim 1 , for the treatment of a molten cast iron using pure magnesium or a magnesium alloy.

3. An application of the process as claimed in claim 1 , for the treatment of a molten steel using calcium metal, a ferrosilicon alloy, or a silicon-calcium alloy.

4. An application of the process as claimed in claim 1 , for the treatment of aluminum or an aluminum alloy using titanium, boron, sodium or an alloy thereof.

5. A device for treating a molten metal or metal alloy using an additive agent, comprising a treatment ladle, wherein at least one local cavity is made in a bottom of the treatment ladle and that comprises added equipment comprising at least one closure member and a displacement assembly for moving the at least one closure member to and from a bottom position for isolating or closing the at least one local cavity;

wherein the bottom of the treatment ladle has a protruding low annular wall that delimits the at least one local cavity;

and wherein a lower portion of the at least one closure member comprises a closure bell which, in said bottom position, is capable of surrounding, at a distance, the low annular wall and a frontal edge of which, in said bottom position, is capable of bearing against the bottom of the treatment ladle, creating an annular bearing zone around and at a distance from the low annular wall and that is located below an upper edge of the low annular wall, so as to form a chamber that includes the at least one local cavity.

6. The device as claimed in claim 5 , wherein the at least one, closure member comprises a suspension arm connected to said displacement assembly and a lower portion having a lower annular edge that bears, in said bottom position, against a zone of the bottom of the treatment ladle, extending around the at least one local cavity.

7. The device as claimed in claim 5 , wherein the at least one closure member extends through a passage of a cover portion for at least partial closure of the treatment ladle.

8. The device as claimed in claim 5 , wherein the added equipment comprises a guide for guiding the at least one closure member.

9. The device as claimed in claim 5 , wherein the at least one closure member is rigidly connected to the displacement assembly.

10. The device as claimed in claim 5 , wherein the displacement assembly is configured to exert a force for applying the at least one closure member, over the annular bearing zone of the at least one closure member, against the bottom of the treatment ladle.

11. The device as claimed in claim 5 , wherein the annular bearing zone of the at least one closure member against the bottom of the treatment ladle is provided with a sealing layer.