magnetite, page-7

from memory diesel/electric trains use one tenth the energy compared to trucking on flat ground about one Kw (1.4hp) a ton as against 10 Kw a ton of payload for a truck and trailer combination.

I am guessing the level of grinding (read energy use)in the ball mill will vary between ore types from different magnetite mines. And I think a rotary kiln is required to palletise so there is another energy sucker.