We go on up the hill to the Ellison shaft, the one now being used most extensively. There the ore is coming up from the 2300 foot level, by hoists and seven ton cars. It is dumped into a conveyor belt, and passes the pickers. We go next to see the giant air compressors for maintaining circulation of air in the mines.
The hoist room contains large drums driven by 1400 horse power electric motors working on direct current. These huge affairs bring the heavy cars up from the mine in a very short time. Their speed and precision are remarkable, considering their enormous size. The room is immaculate.
From the hoist room we go to the shop where diamond drills are sharpened. These are tubular bars of hard iron, with hollow centers, and sharp edges on one end in the form of a cross. They are used with the electric drill down the mine, working on the plan of the electric riveter. When dull these points are brought to the surface, pounded into shape in a trip hammer, while white hot, and tempered very hard.
The motor generator which is driven by alternating current and delivers direct current is a huge affair. It has to be in order to develop enough direct current to drive the heavy machinery. Its flywheel alone weighs thirty-five tons.
In the blacksmith shop all of the blacksmith work of the mine is done. Repairs are made, castings are made, gears are cut, and iron is pounded into shape. A pair of shears is cutting iron ¾ inch thick for a boiler. The ease with which it goes through this mass is astounding. Lathes are plaining blocks of iron or gears into shape. These lathes are cutting shavings a half-inch thick. In the molding room molten iron is being poured into casts, covered with sand, and allowed to cool.
Now comes the real gold mill. The first part we come to is the rock crusher or rod mills. From the rod mills the material is taken to the stamper, where it is mixed with water. The solution passes to dewatering cones and cleaner troughs. Rod mills crush the ore to powder, which, with water makes a mud. The mud passes through troughs containing mercury. Most of the gold leaves the mud and clings to the mercury.
The remaining solution goes to sand slime separation cones and then to cyanide tanks. The tanks are filled with mud. The water drains off. Cyanide is poured over the mass. The cyanide sinks, carrying the remaining gold of the crushed ore to the bottom with it. This is reclaimed and the mud is washed out and sent down the gulch.
The trip is an interesting one. The guide now tells us that the gold is molded into bricks worth twenty-five to thirty thousand dollars. Approximately sixteen are made each month.
B & M. Shop #2
One of the buildings of the Homestake Mining Company’s
Lead, S.D.