GB701273A - Process for the filtration of metal melts - Google Patents

Abstract

701,273. Filtering molten metals. DEUTSCHE GOLD - UND SILBERSCHEIDEANSTALT, VORM. ROESSLER. Aug. 10, 1951 [Aug. 10, 1950], No. 18889/51. Class 46 A metal melt especially of metals sensitive to oxygen, e.g. alkali metals, zinc, aluminium and alloys thereof, lead, magnesium, sodium, silver and alloys thereof is filtered for the removal of solid impurities, e.g. oxides or for the separation of segregated intermetallic phases by flowing under its own hydrostatic pressure from a first chamber to a second chamber through a filter constituted by a porous partition or porous mass forming the separating wall between the chambers, the level of the filtered metal in the second chamber being so adjusted that the metal emerges from the filter below the surface of the filtered metal. As shown, the chamber B for the filtered melt N and the chamber A for receiving the crude melt N are arranged side by side and are separated by a porous filter device F forming the whole or part of the lower portion of the separating wall W. Alternatively, the filter F may consist of loosely piled material deposited at the lower end of the wall W. The surface of the filtered melt N is maintained at the level of an overflow L. In an alternative apparatus the container for the crude metal is closed at the bottom by a porous filter device and is located in the filtered metal receiving chamber with the filter bottom below the overflow. The crude metal may be introduced to the filter chamber directly by means of an overflow or lower inlet depending upon the ratio of specific weights of the melt and solid components. The porous filter in the form of plates may consist of calcined aluminium silicate, quartz or aluminium oxide and the loose filter material may consist of quartz, aluminium oxide, calcined aluminium silicate, spinels, coke or magnesium oxide and may be retained by vertical perforated ceramic or metal plate-like structures. For the separation of segregated intermetallic phases, filters of metallic material made in the form of porous plates by methods of powdered metallurgy or in the form of loose heap metal powders, preferably coarse grained, are used. The filter may be made with layers of different pore sizes made by use of filter materials of different granular sizes.