Gas flow separation of powdered metal
A method for gas flow separation of powders includes establishing a stream of mixed powders; and applying a cross-flow stream of gas to the stream of mixed powders such that powders of different density are displaced by the cross-flow stream to a different extent, thereby forming separate streams of powders having different density. An apparatus is also disclosed.
1 . A method for gas flow separation of powders, comprising:
establishing a vertical stream of mixed powders; and
applying a cross-flow stream of gas to the vertical stream of mixed powders such that powders of different density are displaced by the cross-flow stream to a different extent, thereby forming separate streams of powders having different density, wherein the establishing step comprises flowing the mixed powders through a nozzle to create the vertical stream of mixed powders, and wherein the nozzle has a straight-line configuration and establishes a nozzle per inch of between 100 and 2,400 nozzles per inch (NPI).
2 . The method of claim 1 , wherein the vertical stream of mixed powders comprises a stream of superalloy powder mixed with contaminants having lower density than the superalloy powder.
3 . The method of claim 2 , wherein the superalloy powder comprises nickel-based superalloy powder.
4 . The method of claim 2 , wherein the contaminants are selected from the group comprising silica, alumina and mixtures thereof.
5 . The method of claim 1 , wherein the nozzle establishes a jetting speed for the mixed powders of between 1 and 100 m/s.
6 . The method of claim 1 , wherein the nozzle comprises a slot.
7 . The method of claim 1 , wherein the cross-flow stream of gas comprises a flow of air, CO 2 or inert gas.
8 . The method of claim 7 , wherein the inert gas is argon.
9 . The method of claim 1 , further comprising collecting separated powders from the separate streams of powders having different densities.
10 . The method of claim 9 , wherein the collecting step is conducted using a moving web apparatus to catch and transport at least one of the separated powders.
11 . The method of claim 10 , wherein the moving web catches the separated metal alloy powder and conveys the separated metal alloy powder to a further station for use.
12 . The method of claim 1 , wherein the establishing step is conducted with a gas that matches a gas used for the step of applying the cross-flow.
13 . The method of claim 1 , further comprising the step of sieving a starting group of mixed powders into different size groups, and then conducting the step of establishing the stream of the mixed powders for each of the different size groups.
14 . The method of claim 13 , wherein the different size groups comprise a first group having particle sizes greater than 100 and up to 125 microns, a second group having particle sizes between greater than 75 microns and up to 100 microns, a third group having particle sizes between greater than 55 microns and up to 75 microns, and a fourth group having particles between 40 microns and 55 microns.
15 . The method of claim 1 , further comprising feeding at least one of the separate streams of powders having different density to an electric or electromagnetic further separation step.
16 . An apparatus for gas flow separation of powders, comprising:
a nozzle for establishing a stream of mixed powders, wherein the nozzle has a straight-line configuration; and
a source of a stream of gas oriented to direct a cross-flow stream of gas across the stream of mixed powders such that powders of different density are displaced by the cross-flow stream to a different extent, thereby forming separate streams of powders having different density, wherein the nozzle establishes a nozzle per inch of between 100 and 2, 400 nozzles per inch (NPI).
17 . The apparatus of claim 16 , further comprising a moving web apparatus arranged to collect and transport at least one of the separate streams of powders.