rocket stove designs suitable for smelting scrap aluminum and/or lead?

so i have at least two rocket stoves or RMH's on the docket for this spring, i have all the firebrick I need, i want to make the outside one first before i try to build one inside.

but i'm trying to think up a valid reason to be burning the outside one during the warmer months.  i'm thinking of it more or less like a high-efficiency trash incinerator, but it'll produce heat, and i want to use that heat for something useful.

and so i was thinking, i end up with a bunch of aluminum cans thrown in the recycle.  maybe i could melt those down.  aluminum doesn't rust and i might find a use for those ingots someday.

anyone have experience adapting a rocket stove for this kind of purpose?