What Is Your Grade?
March 2021 by Thom Seal, PhD, PE
After paying for the mine fleet, mill capital, supplies, fuel, power and labor, at today’s metal prices, does this mine make a profit?
It is not necessary to have a PhD in geology, but you need to know the basics, so that’s what I am going to try to dig into here—the understandable basics of these gigantic gold deposits.
Setting up a gravity dredge
Most placer equipment is really made with gold in the 30 and larger mesh sizes in mind, though if carefully used can often get reasonable recovery down to the 50 mesh size.
Over the years, I've noticed a pattern in the type of rocks associated with the best gold deposits in Midwestern glacial gravel.
…as an academic argument, when mated to the appropriate engine, is the pump really moving water at the rate of 400 GPM?
The excavator or backhoe has become the tool of choice for testing placer ground. These machines are the best way to explore and sample a placer deposit if the ground is not too wet or frozen and bedrock is not beyond the reach of the machine.
The problems of the submersible dredge tube are addressed by the subsurface dredge, where the enclosed sluice recovery tube is suspended from a flotation assembly...
The Bawl Mill • Ask The Experts - Info on Santa Cruz beach placers? • Ask The Experts - Detectors and flour gold • Ask The Experts - Why is the gold in these clays? • Ask The Experts - Can you explain colloidal gold? • Ask The Experts - Where did this kimberlite come from? • Ask The Experts - Can gold particles combine to form a nugget? • Placer Gold Deposits in the Western States • Evaluating Gold Recovery with Mass Balance Calculations • Clues for Detecting Ancient River Channels and Flats • State of Idaho Looks to Invest in Gold and Silver • Colorado Uranium Mining in the 1950s Boom • Drywashing for Desert Gold—Part II • Decoding Dredge Capacity • I Just Tripped Over A Nugget • Melman on Gold & Silver • Mining Stock Quotes and Mineral & Metal Prices