I served my apprenticeship at Alcan as an electrician and worked in Carbon Plant maintenance until i was made redundant last year.
Its amazing yet horrible at the same time to see what has happened to the place, were there many pot canopies left, in the potrooms? It seems theres just the risers, belly flexis, busbars and flexis left in most of the pictures.
Line current in the potrooms was 190,000 Amps at 800 V Dc, not the 150,000 you quoted although line current was originally 145,000 Amps when the plant opened. I remember working on potroom cranes as an apprentice for days on end with temperatures regularly topping 55-60 celsius.
The picture you posted of a conveyor in the Green Mix was incorrect it looks to me like it was in the Glamma, the section of plant between the carbon plant and the potrooms, where used anodes were exchanged for new anodes.
Do you have any pictures of the carbon plant? of the chains? or any machines?
Any questions about the place feel free to ask.