Patent ID: 6994754

Claim:
A plant for the continuous hot dip-coating of a metal strip ( 1 ), of the type comprising: a tank ( 11 ) containing a liquid metal bath ( 12 ), a duct ( 13 ) through which the metal strip ( 1 ) in a protective atmosphere runs and a lower part ( 13 a ) of which duct ( 13 ) is immersed in the liquid metal bath ( 12 ) in order to define with the surface of said bath, and inside this duct, a liquid seal ( 14 ), a roller ( 15 ), placed in the metal bath ( 12 ), for deflecting the metal strip ( 1 ), and means ( 16 ) for wiping the coated metal strip ( 1 ) on leaving the metal bath ( 12 ), characterised in that said plant further comprises, on the one hand, in a region ( 17 ) where the strip ( 1 ) leaves the liquid metal bath ( 12 ), an enclosure ( 20 ) for isolating the liquid metal in this region ( 17 ) with respect to the surface of the bath ( 12 ) and for recovering metal oxide particles and intermetallic compound particles by the liquid metal flowing from this region ( 17 ) into the enclosure ( 20 ), wherein the drop in height of the liquid metal ( 12 ) in the enclosure ( 20 ) is greater than 50 mm in order to prevent the metal oxide particles and intermetallic compound particles from rising as a countercurrent to the flow of liquid metal, and, on the other hand, means ( 30 ) for extracting the particles from this enclosure ( 20 ), said plant being further characterized: in that the enclosure ( 20 ) surrounds the metal strip ( 1 ) and has a bottom ( 21 ) and two concentric walls ( 22 , 23 ) making between them a compartment ( 24 ) and defining, in an upper part of the enclosure ( 20 ), an opening ( 25 ), and an upper edge ( 22 a ) of an external one of the concentric walls ( 22 ) being positioned above the surface of the liquid metal bath ( 12 ), and an upper edge ( 23 a ) of an internal one ( 23 ) of the concentric walls being positioned below said surface; and by means ( 35 , 36 ) for positioning the metal strip ( 1 ) with respect to the upper edge ( 23 a ) of the internal wall ( 23 ) of the enclosure ( 20 ), wherein the upper edge ( 23 a ) of the internal wall ( 23 ) of the enclosure ( 20 ) comprises, in the longitudinal direction, a succession of hollows ( 26 ) and projections ( 27 ), wherein the difference in height between the hollows ( 26 ) and the projections ( 27 ) is between 5 and 10 mm.