Micro Flood Gold

[Guest]

Garyww,

Okay now it's fairly easy to capture fine gold in a sluice some riffle types work better then others, and thats all fine and dandy, I've worked with a bowl, and a greenboard, a wheel,
and still there is a fair bit of real fine gold in the concentrates that is just not recoverable, you can seen it just barely with the naked eye, I've got good eyes, so it's real fine stuff, just can't seem to be able to recover it at any rate of speed, there fore while entertaining not real economically worth bugger all........Guest

[The Fossicker]

Howdy Grayww,
I sort of agree with you. Though I can collect the very small micro gold (270 mesh is the cut off for the human eye) I prefere to keep it to 200 mesh for my cut off point. One problem though, black sand or not, is flake and barrel shaped gold. It is much harder to work with, but I'm going after that problem and hope to solve it in an easy manner as well. As was mentioned before, under a microscope much of the micro gold looks like little nuggets and many of them have character to boot! Anyway, don't sell the small stuff too short as there are areas that are rich in it and worth the effort. Cheers.

The Fossicker

[oldgo;dminer]

First post here, hello all.
LOL, big fingered blundered my user name signing in.
It was meant to be oldgoldminer, ohh well.

I was referred here from another forum.
Not long back, acquired a fine gold property.
By "fine", I mean the placer gold here will fall right through a 150 mesh screen.
(smallest screen I have)


This is a low "bar" on the snake river in Idaho USA
White line is a mile long, to give you an idea of the scale of it.

Surface has a thin skin of either wind blown dust, or silt about 5 inches deep.
Below that is sand & small pebbles.
No overburden, to speak off & just scrub grass scattered here & there.

There are some old workings on the site & shallow pits all over the place.
It appears they were done turn of the century & the depression era.
No course cobble show in any of the existing pits.
Everything showing is 3/4 minus or below.

Panning samples from the pits turned up so much micro-fine gold, the boys thought the site might have been "salted".

So they used a post hole digger, to do about 30 small shallow virgin holes spread over the site.

Once below the skin cover, they recovered ultra fine gold by panning in every hole the dug.
Some, better than others, but the gold is everywhere.
No idea of depth to depth to bedrock.

Come spring, plan is to use a truck mounted hollow core churn hole drill to grid pattern drill sample the site.
To get a better idea of depth, material size & what’s there.

From sketchy historical data the first folks that got here, could recover 4 to 8 ounces a day.
Using hand shovels, rocker box & mercury to amalgamate the dust.

Historical data indicates the richer deposits were formed like this, over thousands of years.


In this example the #5 is at the surface, the rest buried.
This jibes with where the biggest surface working are on this bar.

I have been around long enough to know panning can "fool" you.
As,  careful panning can recover micro-fine gold that will shoot right out of a sluice box.

Again, historical data shows the old timers used burlap, or sail cloth to line their sluices with.
I'm thinking...if the drill testing shows promise……..trommel... to classify to 1/4 inch minus.
The run those fines over a sluice box with a series of 20 mesh screens in it.
Where those fines could drop into lateral sluices, lined with rough top conveyor belting.



Any suggestions would be appreciated.
Certainly, I realize until its drill tested, we are talking “smoke” here.
But, assuming the drill testing shows promise.
The trick would be how to recover enough gold, to make a profit.

Never worked such fine gold, so this is a new ball game to me.
Have run placers, where the gold ranged from fine (40 mesh) to ¼ inch.
But, never, all micro fine gold.

This one may be far bigger than I can chew.

[GollyMrScience]

Last time I checked they are paying the same for an ounce of 150 mesh gold as they are for an ounce of 40 mesh and once poured into a bar its a moot point anyway.

The trick is to determine the economics of the deposit before the final decisions are made on equipment OR design equipment that can do a certain job and don't expect it to perform on every deposit.
You could go straight to the highest recovery system possible - spend the money and build the biggest, meanest, most gold getting thing ever and spend two ounces of gold to get one ounce out.
Striking the right balance is the key.
Throughput versus recovery and the costs of operation have to be part of the equation.
Now a hand shovel operation is not so strict - especially if your beans and bacon don't rely on your production.
Still it would be nice to optimize the recovery so each shovel full gets the most gold it can.
Against that for a hand miner is capital cost, operations costs and access.
Access can be a real show stopper. Compare a basic high banker and what it takes to get that into your favorite spot. Now turn that into something weighing 600 pounds and built big enough to be awkward as all get out and imagine trying to drag that through the trees and down the cliff and you can see where access becomes real important.
I have worked in some pretty darn remote and primitve spots and having to break stuff down into tiny bite sized pieces so it can be hauled in can really take the jolly out of a guy.
Many a fancy gold getter sits in somebody's garage because the operator can't get it to where they want to without a chopper or a passle of willing helpers - three days with a chain saw and maybe a small CAT to break trail. The spontainaity is all gone - the mobility severley reduced and therefore the areas accessable on short notice or in remote locations is essentially gone.
Some of you have also touched on one of the real pains and that is recovering fine gold at the primary stage and not having a suitable system to handle the cons to actually get that gold out. Never mind that for most small scale operators that no see'um gold only represents a small fraction of the gold recovered - it keeps showing up to taunt ya.
Not only that but the nagging question haunts a prospector - "If I caught this how much of it got away and should I be doing something about it???"
There usually follows a process that is akin to figuring out how to cook up a pig you ain't caught yet with many a fun hour spent designing the perfect system. Thats what long winter nights are for.
Some things to consider:

Going to a highly efficient primary recovery system without upgrading the separation system is gonna get you in trouble.

Using a very efficient testing system helps determine the nature of the deposit and gives some guidance towards economics and equipment decisions but if the actual primary recovery plant is going to be less efficient than the test system an operator has to allow for that. Thats one reason why assay got a bad name in placer. Super high efficiency test method that cannot be duplicated at the real world level and placer operators not having any way to make allowances for the difference because assay (at least standard approaches) doesn't tell you a heck of a lot about the gold you are chasing and how much of that  gold is actually recoverable in your equipment.

One way to test is to use a testing system that comes close to the recoveries that your primary recovery system will use. Either a smaller version of it or a method that comes close to duplicating the efficiency. Thats why panning has been so well accepted as a test method as a careful panner can recover most gold that standard recovery methods can so there is a baseline to work from. A VERY careful panner who is willing to classify on narrow screen differences can pretty well cover the recovery rate of free gold from nuggets down to 400 mesh for most standard equipment from sluices to centrifuges. Taking the gold recovered and doing sieve sizing to see where the majority of the gold is reporting will help guide equipment decisions. It can also help determine some economics but that should not be based on just a couple of pans and thats for sure. In an ideal world usng this system the panner would run a bunch of pans of known weight and/or volume then dry and sieve the gold - weigh each fraction then determine what bigger equipment best suited the recovery of the major portion of the gold. Then they would get a small verison of that bigger equipment and run larger samples to see if the assumptions held and to do wider testing of the prospect and THEN they would look at production.
For hand miners though the equation is considerably shorter. Since the pan is the first test and the sluice, in either stream or highbanker form, is the standard production system the sluice serves as both the bulk sample pilot plant AND the production plant. I hazard a guess that many a hobby hand mining decision is based on how far the operator could drag the equipment and if there is a good place in the stream to keep the beer cold.

[oldgo;dminer]

Hollow core churn hole drilling the site on a grid pattern will result in 20, 30 or more yards of material, dependent on depth & how tight the grid pattern is. Plan is to split the cores, then run ½ on a practical, but the best recovery system possible. To give us a “ball park” figure of the values, and hopefully outline the higher grade zones. Then, use the other ½ for test runs on a small scale pilot plant, equivalent to what think best to use for actual production.  I’m financing this one alone, out of my hip pocket. So, the budgets are tight.

The 1st issue is, how much value is there & of that, how much can we recover economically. The 2nd issue is the most frugal practical means to get the material to & through the plant, then back again. As reclamation is going to be a big issue here. Since the bench bar is barren, except for some grass. I would wager no issues there. As once done, we simply hydro-seed it again with native grass. We have riparian water rights on the river, so water use is not an issue. But, turbidity of effluent water will be a big issue, So, we a whole series of variables to consider. One step at a time, slow & easy.

[Guest]

For hand miners though the equation is considerably shorter. Since the pan is the first test and the sluice, in either stream or highbanker form, is the standard production system the sluice serves as both the bulk sample pilot plant AND the production plant. I hazard a guess that many a hobby hand mining decision is based on how far the operator could drag the equipment

Yeah that's main reason I like to have my backpack highbanker smaller one for prospecting and larger one for handmin-in, the bigger one is 12 wide and can handle 1-1 1/2 yards per hour, depends on how ambitious you get, with pump and shovels, picks, prybars, buckets, hoses and gasoline and other nicnacks about 100 to 125 lbs of gear, so you can make two trips or partner up with someone trust worthy (and thats a whole new story) pack it all in up to a few miles or more,  remember you alway have to pack it back out someday, then you're all set up and only got to pack gasoline in and concentrates and gold bullion out everyday sounds real good doesn't oh yeah theres still a lot of back breaking work to do but at least your only working for yourself................and thats a good thing..........Guest

[fredgold]

Hi Fossicker
You say that the cleangold sluice is patent, what's the patent # ? I searched the web and can't find anything that relates to the cleansluice.

[NickMarch]

I've been reading but not posting lately but I just had to reply to this thread.

To get micron gold down into the nanometers I use  menhaden oil  (fish oil used by fishermen)  I pump stream sediment into a (closed top) 55 gallon drum thru about 1/4 gallon of oil.  You have to have the water draining from the bottom as fast as it is entering or you will lose your oil.  I use a mesh screen at the inlet of the suction hose to stop anything too large from getting sucked up.  In the drum the outlet hose should have a spray nozzel.  When I'm done pumping I hook up my suction hose to the outlet of the drum and recirculate/agitate the oil with liquid detergent and borax.  This releases the gold from the oil.  Then I use a coagulant/flocculant.  The coagulant/flocculant binds together the gold suspended in the water and drops it.    Pretty simple!

Centrifuges are probably the next best option but they can only recover down in the 50 micron area. (horizontal centrifuges)  300 mesh gold basically stays suspended in the turbid water in a centirfuge.  With oil you can recover down into nanometers.

Before anyone asks, yes there is a certain amount of junk in the bottom of the tank along with the gold.  Not much but yes there is!  Does any of the oil escape... Yes! but not much and it is fish oil.  Tens of thousands of gallons of it are dumped into waters yearly!

[garyww]

MrScience kind of beat me to the punch on this one as I was going to talk about panning and microscopic gold as I think most people don't believe that panning can capture ultra fine material. I can say for sure that it does and most of us throw away all that microscopic material after we snuffer up what we can see with the naked eye. If you want a surprise scan the bottom of your pan with a really powerful magnifying glass after you think you've collected all the gold. Pan sampling is still the best and cheapest way to prospect a site and not as slow as one might imagine.

[The Fossicker]

Howdy All,
There's some great posts here tonight and I want to jump in to address some of this most interesting debate and subject, but duty calls. I'll answer what I can tomorrow. Cheers.

The Fossicker