Aluminium melts at temperatures that, as far as ovens are concerned, can be classified as "tame". Sure, the oven needs to be built heat-resistant, but a melting

Aluminium melts at temperatures that, as far as ovens are concerned, can be classified as "tame". Sure, the oven needs to be built heat-resistant, but a melting point of just 660C allows things like uncooled structural steel to be used. This is so tame, that the molten salt type nuclear reactors (well, some of them) are able to serve as a heat source for such an aluminium recycling oven. 10 years ago there were coal power plants in active development that used high-pressure (around 350 atmospheres; 75% higher than what consumer-grade pressure washers tend to max out at) supercritical (700C) water to drive the first stage of their turbines, in an effort to extract more of the coal's chemical energy through exploiting a greater temperature drop. The aluminium oven does not need to handle such severe pressures, or contact with fast-flowing liquid that is as corrosive as water at those conditions (they can use a gas between the heat source and the aluminium, and fire brick style material between the aluminium and the structural walls of the molten-aluminium-bucket).