metallurgical knowledge = no project, page-14

Plough,

Spirals are indeed used in mineral sands and like HMS are used to separate minerals based upon density. Depending on what size the gangue minerals are in FMG's deposits will decide which gravity devices are used (Jigs for a coarse separation, spirals for a fine one). Wet scrubbing (effectively a rotating drum with a constant flow of ore and water) is used on low grade ores to liberate Alumina and other waste minerals that can be screened out or removed used gravity devices (spirals etc). You can see that a wet plant would require additional environmental consideration - equally capital cost and water resources put this in a very lonely place. I really can't see even a +20% iron ore price increase would encourage this type of development.

As for sour grapes - I don't eat them.