Monday, September 23, 2013

On Dry Washers, Desert Gold, and Working Dry Ground (Part 4)

 (Keene Engineering's "Vibromatic" hydrostatic dry washer.)

In this post I'd like to bring your attention to another type of dry washer, the electrostatic machine (some manufactured versions are known as a vibrostatic). Additionally, if time and space permit, I'll throw in an interesting story about gold and electrostatics for good measure.

Attracting Fine Particles

Another type of common dry washer is the electrostatic unit. The concept of using an electrostatic charge to attract small metallic particles has been around for quite a while now and is a fundamental aspect of the physics of electromagnetism.You're already familiar with a very basic form of electrostatics...static electricity. All of us have had numerous static "shocks" in our lifetimes and if you were to describe the conditions under which those shocks took place, I suspect your main descriptor would be the word "dry." (The light bulb in your head should be starting to glimmer a bit now.)

Gold Concentrates
Gold Pans
Gold Concentrators

Electrostatic dry washers are designed to use the physics of electromagnetism, electrostatics, and static electricity to capture or recover gold. Because of this, they are especially effective in recovering very fine particles of gold and small flakes, not to mention the "usual suspect" larger stuff like "chunkers," nuggets, etc. I hate to say this, but a properly rigged and operating electrostatic machine will do a much better job overall of recovering fine gold from dry placers than the venerable little "puffer" or bellows-type machine (my old school favorite).

Hot Air?

It should go without saying that electrostatic machines are typically motor-driven units with most of these powered by a leaf blower or vacuum engine. In some electrostatic dry washer models, the hot air from the engine is redirected into the radial blower re-heating the air as much as 50 degrees higher than the surrounding air before it's forced up and through the riffle tray. See the advantages here? With that type of heat being applied to your auriferous material the odds of losing gold through dampness are significantly reduced while the gold-grabbing electrostatic charge is correspondingly increased. Additionally, in many electrostatic dry washer models, the riffle tray is not fixed and rigid, but is suspended from the hopper box so that it vibrates under oscillation. This means feed material in the riffle tray is processed more quickly and efficiently.

All this said, I myself have never used a hydrostatic machine. I've seen a number of them in use over the years but I can't speak with any level of confidence or expertise about them. I understand the concept and the physics, but I'll have to rely on you, my readers, to flesh out any gaps about hydrostatics and what your experience has been using them in the field. So feel free in that regard.

 (Keene's "backpack" version of their hydrostatic. I guess the motor goes inside your backpack too!?)

Here's an interesting little story you may not be aware of about dry placer gold and the physics of hydrostatics:

Wizard of Electricity

About 14 miles from my home outside Santa Fe, lies one of New Mexico's oldest placer and lode gold locations, the Old Placers District. The Old Placers are in the Ortiz Mountains south and somewhat east of Santa Fe and were quite rich at one time, especially as dry placers go. At one time, the Old Placers supported over 4,000 would-be placer miners as well as various cutthroats, thieves, whores, and hangers on until the easy to get stuff was gone and the lack of water made things too difficult for the miners and, subsequently, their camp followers. I myself was fortunate enough to prospect and mine the Old Placers for a good 12 years or more until they were placed off limits by private property and environmental issues.

(This Keene vacuum model is like a dry version of a highbanker, complete with suction intake and hose for working bedrock cracks and crevices.)

Anyhoo, in the 1890s none other than our own wizard of electricity, Thomas Alva Edison, showed up in Santa Fe County and signed a lease on over 50,000 acres in the Ortiz Mountains, including a good portion of the Old Placers District. It seems that Edison had a plan for recovering the multitudes of minute specks and flakes of gold left stranded in the arroyos and washes of the Ortiz because of the lack of water there. Edison's plan? To use an electrostatic "separator" he had designed to recover all that dry placer gold. You see, he'd already been successful using a similar electrostatic device of his own creation back East to remove iron ore particles from sand without using water. If electromagnetism could recover fine iron particles, why couldn't it do the same when it came to gold?

(To be continued...)

(c)  Jim Rocha (2013)

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  1. Jim, Very interesting, I'm sure I'm jumping the gun here, but gold is not magnetic, so how does it work?? Gary

  2. J.R sorry to here about the accident.Glad you didn"t get hurt any worst then you did. Some one was looking out for you. Hope the health issues. Are minor and can be fixed. My prayers are with you.