GB964734A - Method and apparatus for de-gassing molten metal - Google Patents

Abstract

A stream of molten metal is degassed by exposing it to vacuum conditions in consecutive degassing chambers, using preferably from five to eight, wherein the pressures decrease in the direction of flow, the pressure in the first chamber being such as to cause the stream to diverge to a diameter, e.g. 500 mm., adequate for degassing prior to it being conducted in free fall through at least one further degassing chamber before being intercepted in a collecting vessel. An example, Fig. 1, illustrates five consecutive degassing chambers 14 to 18 separated by partitions 10 to 13 each having an orifice 19 to 22, the last chamber containing a collecting vessel 23, and the first, wherein the highest pressure obtains e.g. 30 torrs, having <PICT:0964734/C6-C7/1> sealingly mounted above it a storage vessel 3. The sizes of the orifices, preferably cylindrical with sharp edges, and the suctions of the vacuum pumps 25, 27, 29, 32, 33 are such as to produce a throttling effect between the falling molten stream and the orifices to maintain the required pressure drop from one chamber to the next. The partitions are preferably cooled by coils 34.