Abstract: A process for the reflux refining of metals in which impure metal crystals within a column of the liquid metal are transported from a cool zone through a temperature gradient to a hot zone, wherein melting of the crystals occurs; said transport being facilitated by the use of a mechanical device comprising a plurality of elements movably supported at spaced-apart locations within the column, each element being of small maximum transverse cross-sectional area relative to that of the column, said elements being moved at least reciprocally in the direction of extent of the column, whereby in consequence of the shape and movement of the elements there is, in the vicinity of each element, a net displacement of crystals towards the hot zone.

Abstract: A method is provided for the continuous purification of an impure metal in a column consisting of a slurry of metal crystals in liquid metal, said column having a relatively hot zone and a continuous temperature gradient between said zones; the temperature of the cool zone being such as to permit coexistence of liquid and crystalline metal, and said hot zone being at a temperature sufficient to melt the crystals. A portion of the column in the said cool zone is chilled to form a coherent mass of crystals of the metal; then incipient melting in the mass is allowed to occur to release crystals from the mass into the column of the crystals in the liquid metal in the cool zone of said column. The crystals are transported through the temperature gradient and into the hot zone, wherein melting of the crystals occurs and the hot zone thereby becomes enriched with the pure liquid metal.