Scope and Contents Milling began at the rotary tipples. The tipple on the left was dumping simultaneously 4 ten-ton ore cars from the mine. Each train from the mine had forty similar cars. The tipple on the right was being repaired. The ore from the mine usually had an average value of about $1.50 or less per ton at $35.00 per ounce of gold. The mine operated 24 hours per day, 363 days per year and averaged over 12,000 tons per day. The tipples dumped over 1200 car loads per day, into a 1500 ton hopper. ...

Scope and Contents

The 3 primary crushers on the main crusher floor below the tipples. These were 36 x 48 inch Jaw crushers with 8-inch open settings. These crushed plus 4-inch size mine run feed from the tipple hopper and fed it to a series of grizzlies (coarse bar screens) and vibrating screens that segregated the ore by size. To allow for maintenance, two crushers worked, while one was held in reserve. The entire mill was similarly engineered to avoid shutdowns caused by equipment failure.

Scope and Contents One of the vibrating screens on the crusher floor. Ore from the hopper and the primary crushers was segregated by size and mineral content using screens and picking belts. All plus 4-inch size ore went over two picking belts that carried it past groups of four men who raked off the mineralized rock. Plus 3-inch size went over similar picking belts. All minus 3-inch size ore and all mineralized ore raked off the picking belts was crushed to progressively finer sizes as it passed through...

Scope and Contents

Plus 4-inch waste on the left and plus 3-inch waste on the right enroute via belt haulage from the picking belts to the dump. The man probably was greasing the bearings. One-half of the mine run rock was discarded at this stage. This is the source of the "A-J rock" that forms the rock dump and is used for fill throughout the Juneau area. Discarding half the ore cut grinding costs with little loss of gold. If all the rock had been ground the mine would not have been profitable.

Scope and Contents The mineralized rock from the picking belts and the minus 4-inch material from the primary crushers went to the gyratory crushers and then to the cone crushers. Plus 1 1/2-inch discharge from the cone crushers went to the roll crushers. This was a roll crusher driven through the belt shown and a similar belt on the opposite side by a pair of 150-horsepower electric motors. It was one of the number 2 roll crushers that crushed to a smaller size material previously crushed in a number 1...

Scope and Contents

A roll crusher dismantled for repair. (Howard Hayes is the man on the left). The mechanics on the maintenance crew were putting a shell on one of a set of two rolls. The circular device made of pipes was an oil or gas burner used to heat the shell. The shell was like a thick steel tire. It fitted over a very heavy split rim that was keyed to the axle. The men were tightening the split rim while the shell was hot. When the shell cooled it shrank to make a very secure fit.

Scope and Contents

In the background is a ball mill, a rotating steel tank lined with heavy steel plates and containing steel balls which ground the crushed ore to fine sand size. In front of the ball mill is a drag classifier that separated the sand from the water and slimes by dragging the sand up a ramp. The objects with round openings in the foreground are spare bearing caps for the roll crushers.

Scope and Contents

A ball mill equipped with trunnion trommel screens to remove fines. Oversize was returned by elevators for regrinding.

Scope and Contents

Discharge from grinding in the ball mills was screened and cleaned in desliming cones. Three products resulted: (1) oversize that was elevated and reground (2) fine sands that were sent to the Deister tables for treatment (3) fines and slimes that were sent to thickeners and then to flotation cells for treatment.

Scope and Contents

The machine shop. A large force of mechanics was constantly employed in maintenance and repair. (no. 37)