Scope and Contents

A large lathe in the machine shop. The mine plant also included a foundry in which worn and broken parts were melted and recycled.

Scope and Contents There were over 100 in the mill. There also were gravity traps and sluices to recover coarse gold. The deslimed fine sands (minus 7 mesh) from the ball mills flowed over riffles on the tables in a stream of water. The devices driven by a belt in the foreground imparted shaking motion to produce three products: (1) a concentrate of heavy minerals (2) middlings for retreatment and (3) tailings for disposal. The feed to the tables had about 4 dollars worth of gold per ton. After a series...

Scope and Contents

Flotation cells on the retreatment floor. These cells contained water and small amounts of oily materials, called reagents, which selectively coated certain minerals. When air was bubbled through the mixture, the coated materials formed froth on the surface that was skimmed off. Two products resulted: (1) mineralized concentrate which was dried and shipped to a smelter (2) tailings which were discarded.

Scope and Contents The gravity concentrate from the Deister tables assayed $20,000 to $30,000 per ton. It was charged into the rotating steel drum in the background with a few pounds of slaked lime and about 600 oz. of mercury that had been cleaned with nitric acid. The drum was rotated about 5 or 6 hours with a piece of shafting in the drum. The drum was then discharged into the 4-foot pan in the foreground (called a mechanical batea). The pan overflowed a galena (lead ore) product that contained silver...

Scope and Contents

Oil-fired melting furnace. Inside was a crucible similar to the one in the foreground. In front of the furnace was a mold on a movable stand. When the gold melted, the furnace was tipped forward to allow the liquid gold to pour into the mold. In the mold the gold cooled to form a dore (pronounced doe-ray) brick. This was sent to the mint where it was refined to remove silver, copper and other metals.