st george float, page-65

Supergene ore has been mined for the past eight weeks. Supergene ore is blended with drier and harder ore types to optimise feed through the treatment plant.

Complicating the situation further are old filled stopes from the Mikado mine. The old timers took only the richest ore and left bands of lower grade. Some fill material tends to be mined along with envelope ore. Mikado ore would have been sorted to an extent within the stopes. Old timer reject ore is now acceptable so much of the fill may be ore grade as well.

This fill was not well compacted and became saturated when the mine flooded. Remnant ore along the backs became water saturated too. Even though the mine is being dewatered, much of the higher grade ore is water saturated. In fact the reason the ore was high grade in the first place was because it became enriched by migrating colloidal/solution gold in the anoxic zone below the water table. The A1 plant is only able to accept a proportion of saturated ore in the feed.