The mining operation required the ore crushers and freight silos up at the mines, a production site for slime (pulverized ore) and later a briquette works, mechanical workshop and quay site for shipping. The extraction of the iron ore gradually became more efficient. The six ball mills at the post-war works had a greater capacity than the 64 mills at the old works.

The description provided in Fasting's book states: "With the addition of water, the ore is milled in ball mills, the slime is segregated over permanent magnetic separators and is for the most part released by the water over the vacuum filters."

The large mill silo is an extended concrete building with a rectangular layout. The body of the building is compact, consisting of larger and smaller 'modules' or 'sections' of varying height and breadth. The large lean-to roof over the hall accommodating the ball mills follows the gradient of the hill down towards the level area and the town. The wall sections are characterized by large areas of rendered concrete, which are broken up by windows. Facing the northeast and down towards the town centre there is a large area of glass, which is divided up into small, square panes. The building is otherwise mostly made up of horizontal rows with windows.