Treatment of molten aluminum with an impeller

Claim 1

The method according to claim 1 wherein said impeller is a vaned disc impeller having a substantially horizontal disc portion and upstanding radial vanes.

Claim 25

A method of treating molten aluminum to decrease its content of oxide inclusions, hydrogen gas and sodium comprising the steps a. introducing said aluminum into an agitated zone maintained by the action of a submerged rotating impeller and containing a mixture of said molten aluminum and a reactive salt flux containing magnesium chloride, b. introducing into said agitated zone a gas to strip dissolved gases from said molten aluminum being treated therein, c. continuously moving a mixture comprising molten aluminum and salt flux from said agitated zone to a quiet zone, separated from said agitated zone, to substantially separate molten aluminum from the remainder of said mixture which remainder rises to form a floating salt flux-oxide layer above the separated molten aluminum, d. recirculating salt flux from said floating salt flux-oxide layer in said quiet separation zone to said agitated zone, e. removing a purified molten aluminum product.

Claim 27

A method of treating molten aluminum to decrease its content of oxide inclusions, hydrogen gas and sodium in a level pour system having an inlet and an outlet disposed not more than 3 inches below said inlet and comprising the following steps a. introducing said aluminum through said inlet into an agitated zone containing a mixture of said molten aluminum and a reactive salt flux containing magnesium chloride and not more than 1 percent moisture, b. the agitation being provided by the action of a rotating vaned disc impeller having a substantially horizontal disc portion and upstanding radial vanes, the disc of the impeller being situated at or below the static molten metal-salt flux interface which prevails in said agitated zone when the agitator is not running, c. said molten metal introduction being arranged in cooperation with the rotating disc impeller such that it falls downwardly a distance of up to 5 inches upon the upper faces of said rotating disc and wherein at least 90 percent of the molten metal being introduced is fragmented into particles and streams each having a dimension under one-fourth inch, d. continuously moving a mixture comprising molten aluminum and salt flux from said agitated zone to a quiet zone to substantially separate molten aluminum from the remainder of said mixture which remainder rises to form a floating salt flux-oxide layer above the separated molten aluminum, e. recirculating salt flux from said floating said flux-oxide layer in said quiet separation zone to said agitated zone, f. removing oxide from said floating salt flux-oxide layer in said quiet separation zone to provide and maintain a maximum oxide content of 20 percent within the salt flux recirculated to said agitated zone, g. removing a purified molten aluminum product through said outlet.