Gold is everywhere on Planet Earth, but seldom is it found in significant concentrations. The Earth's crust contains approximately 0.004 grams of gold per ton but, left over mill and mine tailing piles can assay as much as a few ounces per ton.
The word "Tailings" usually brings a mental picture of heaps of useless waste dirt left over from digging out mine shafts and tunnels to get to the vein of gold. In reality, mill and mine tailing piles can be highly valuable and a source of extreme profits. The value of a 3 million ton, 50-foot-high mound of dirt and ruble can quickly turn to a glimmering pile of treasure!
But, extracting precious metals from the raw earth is a difficult process. Removing the gold-bearing rock from the above-ground tailings is just the first step. To isolate pure gold and other precious metals we must use a complex extraction method.
The first step in this process is breaking down large chunks of crude rock into smaller pieces. This process helps to breakdown the ores at the molecular level to help liberate the gold from other ores.
The Rock Crusher reduces the ore to ¾ minus pieces no larger than road gravel.
The ¾ minus ore is then feed into the hammer mill which grinds it down to between -50 and -125 mesh.
The gravel-like -50 to -125 mesh material is fed into the Flail Mill drum that is lined with rotating steel heads. In the drum, the ore is ground to an extra fine -250 to -400 mesh slurry or powder.
Once the ore powder is classified down to about a -200 to -400 mesh (a talc like powder much smaller than a grain of salt) it is then sent to the (Shaker) Table to be separated.
This Table process separates particle grains into a concentrate based on the differences in their specific gravity, density, size and shape. Only the heaviest metals (primarily gold plus some platinum group) vibrate into Journal 1.
Journal 2 & 3 also contain precious metals (silver, copper, other platinum group metals and iron or lead based metals) while Journal 4 is primarily waste rock.