Why does it take less energy to get aluminum metal from used cans than to get it directly from the ore?
in order to extract the raw aluminum, you have to heat everything and melt it first, then remove the stuff that precipitates out as it cools or forms via chemical reaction with catalysts you introduce. With aluminum cans, you don't have to raise the temperature much above the melting point of aluminum, since it's already the substance in the can with the highest melting point. With aluminum ore, there can be anything in the ore with pretty much any melting point. In particular, if the ore contains an alloy of aluminum and a metal with a higher melting point than aluminum, then rest assured, you will have to raise the temperature of the ore above the melting point of aluminum in order to melt that alloy, In any case, because the maximum required temperature of the smelter needed to melt used aluminum cans is necessarily lower than the maximum temperature required to work with the ore, less energy is required to get aluminum from used cans than from ore.
