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Peter Freedman

Large Gold Sand Deposit That Pays $8 A Yard - Worth Presuing?

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I have been prospecting a deposit that is a fossilized sand placer containing gold. I dug a couple of trenches and have run several yards - The material comes out to about $8 a yard from a sluice. Historical records suggest $17 yards.  Is this something worth considering to mine?

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It really is based on what it costs you to mine it. If you are in a high expense area with few resources and difficult conditions, it may cost more than $8 a yard to mine and process.

I would say its worth investigating further. I guess at this point, you need to work on figuring how much it will cost you to mine and process it.

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Chris, 

 

Thanks for your reply. I am just an amateur prospector learning the ropes. Been looking for good ground in the lower 48 for the last 7 years. But it seems that sand deposits of lower grade could be economic because of the ease of access and quantity of material.  

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The problems you will run into, in no particular order, are:

 

The gold will be real small. The larger gold and consequently heavier dropped out amongst the pebbles and cobbles upstream.

By small I mean mostly -100 mesh and down.

This presents a bit of a task to accomplish a high percentage of recovery.

 

Then there is the shear volume of material that must be run through the sluice.

All of the material must be slowly fed into it or you will plug the bedding resulting in more recovery loss.

Rather than being able to classify out the obviously not-gold, you will have to sluice it all.

Then there will be all the tailings that come with the garbage in, garbage out process.

 

The above demands will require lots of water and a monster width sluice to process.

 

Can it be done? Sure.

Economically? Maybe.

 

If you look at the Keene Beach Box, you can see that it is a lot wider than their other models.

It is this wide just because it was designed to run sand and still be small enough to be portable.

 

Hope this helps.

eric

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Eric,

 

Thanks for your reply. I understand the sluicing process - but seems that there are better recovery methods such as Humphrey Spirals, cylones,  mineral jigs, centrifuges etc. Water will be an issue and seems that recovery systems that can economize on water should be employed.  I am curious if you have input on these methods or why theses method are not good. I assume that cost is the biggest issue. 

 

-Peter

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Got a few opinions, but no experience to base those opinions on.

I imagine you are correct about the cost factor.

I just know that sluices are really cost effective.

I doubt that a jig would work on the size of gold found in sand deposits.

The others are probably quite cost effective once scaled up to some minimum required feed rate.

 

You said this was a fossilized sand placer. Is it sandstone or just sand glued together with clay?

 

Maybe you should determine how many yards you can move in a day and what your budget is. Then decide from there.

I'm thinking at least 1 and maybe more inhabitants of this website had dreamed big once or twice their own selves. Okay, it was me.

 

eric

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Peter,

 

I have spent the past few years elaborating on the subject of mining a low grade placer deposit.

 

Every mine has a unique set of variables that affect cost of operation.

 

If your objective is to mine gold commercially and generate a profit, the method or process of recovery has to be decided with attention to all of the cost factors. Cost control and grade control are borne out of sound management.

 

Since mining involves a number of steps, each step in the process has to be given close attention. Given a value of pay, for example $13.00 per cubic yard defines the level of production required to suit your ambition. One cubic yard per hour pays $13.00 (less cost of operation). Mechanical placer mining such as I have done has a grade requirement based on the hourly cost of operation. Working the numbers from the cost side; Given the cost of operating a 23HP Vanguard Water Pump and a Bobcat, fuel cost alone in the interior of Alaska is $18 per hour. Is your labor free? Do you support the cost of other helpers? Do you have debt that has to be serviced? How do you plan to replace worn out equipment and afford repairs? If there really is a "profit motive", then how much profit is expected? All of these factors and more control the requirement for "pay" as determined by extensive sampling of the deposit.

 

- Geowizard 

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Capacity;

 

Gold production - even on a low grade placer deposit can be profitable if certain levels of production can be sustained.

 

A Bobcat loader can handle one cubic yard. Running 10 cubic yards per hour and $13.00 placer will generate $130.00 per hour. A two man crew with wages and fuel are covered. Another scenario is 40 cubic yards per hour, same machine and manpower generating $520 per hour at the same cost. Net profit might be around $400 per hour and on a 10 hour day works pretty well for most entrepreneurs.

 

- Geowizard

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$8.00 Gold?

 

A business model for $8.00 gold requires high volume production.

 

The investment in a Dozer, loader, trommel operation that runs 200 cubic yards per hour might be in the range of $250,000 to $500,000. Production of $1600 per hour with costs in the range of $600 per hour would provide a net profit of $10,000 in a 10 hour day.

 

- Geowizard

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$8.00 Deposit model;

 

The large scale production required for $8.00 placer gold demands a large deposit.

 

Considering the volume at 200 yards per hour and 2000 yards per day, to recover $1,000,000 profit on a $500,000 investment, at $10,000 per day net, makes the deposit size 100 x 2000 = 200,000 cubic yards.

 

Note: Investment in capital equipment for mining leaves the equipment paid for and $1,000,000 in the bank.

 

$8,00 x 200,000 = 1,6 million Gross revenue. $100,000 is paid out over the 100 day production campaign.

 

- Geowizard

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Reality;

 

A placer deposit usually contains 18 inches of placer gold. This number pops up frequently in historic placers.

 

Can we assume it is an undiscovered placer gold deposit of historic proportions?

 

Unfortunately availability of sufficient water for large scale placer mining is intermittent or insufficient. A 200 cubic yard per hour (solids) operation requires 1000 cubic yards or 200,000 gallons of water per hour for 20 percent slurry in the sluice.

 

Unfortunately the gold is intermittent and the grade becomes sub economic. Low grade must be offset by an equal amount of higher than expected grade. The probability of lower grade is usually greater than the probability of higher grade!

 

Unfortunately placer deposits have extensive overgrowth in the form of trees, roots, moss, and other vegetation.

 

If the placer deposit is continuous, the area for the example given above would be 400,000 square yards. Large placer miners (historically) have been known to mine 400,000 square bedrock feet in a season (in Alaska).

 

Given 9 square feet per square yard... the project would likely involve a period of 9 to 10 years.

 

- Geowizard

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A placer deposit usually contains 18 inches of placer gold.

That's not really a reliable rule of thumb. I've seen placers with good gold only within a couple inches of bedrock and others where the pay gravel extends up 3 to even 6 feet above bedrock.

 

Unfortunately placer deposits have extensive overgrowth in the form of trees, roots, moss, and other vegetation.

In Alaska, sure - but in the deserts of California, Arizona, Nevada, Mexico, etc. - no, "extensive overgrowth" is not an issue.

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Hi All, 

 

I appreciate all the though into this. 

 

Just finished up my season of sampling the property. Dug many pits with an excavator and sampled away. In-fact - found areas as rich as $40 per yard. Proved to myself that the property has value and merit.  In the process of securing the permits for next year and planning on the drilling of a well. 

 

Stay tuned for my bombardment of recovery questions is future posts in this forum. 

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There is a medium scale mining operation working on the fossil placer by the CO/WY border near the Little Snake River using those big spiral separators and recycling their water. They look to be about 30ft tall. I've tested that general area in the past and it's about the same tenor, $5-$10/yd and its all sand, almost no cobbles.

 

Anyways, not sure where you are at, but it sounds like you are looking at pretty similar conditions so if you are nearby to them you might stop by and see if they are talkative and have some lessons learned they are willing to share. Doesn't look incredibly profitable to me, but who knows.

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Jasong - do you know if they are also selling gravels? There are many gravel plants which make the bulk of their money on gravel and aggregate sales, but also recover some gold from processing and in some facilities the gold is a significant part of their profit. In others the gold is not the bulk of their sales, but is icing on the cake so to speak.

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I don't think they are, it's all sand out there, not many cobbles. They had a big dryland dredge out there 100 years ago and the tailings piles are about 4ft tall now since they mostly blew away. Looks like the sandstone its derived from is an old fossil ocean beach to me. I'm not sure how they make a profit, those towers look like they cost quite a bit.. It kind looked like one was an elutration tower and one was a spiral gravity separator but I can't remember exactly.

 

There are a few gravel plants in Colorado that just ignore the gold entirely because the gravel is more profitable. Only reason I know that is because I tried convincing them to let me put a sluice in somewhere or work the bottom of the sandscrew tank (no luck).

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I knew a guy who worked at a plant like that  - he offered to clean out the sand screw for free on his own time if the boss would let him keep what gold he found.

The boss thought he was crazy, because the boss knew for sure that there was no gold out there and so he let him do it.

The kid and a couple friends did it on a Saturday when the plant was closed and took a little over 5 ounces total. It wasn't super rich, but 5 ounces split between a few guys is pretty good money for a few hours work.

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