Processing Black Sands

[SchoolOfHardRocks]

I've heard that prospector's "would be surprised, & never discard black sands again if they knew how much gold is in it"...Well, with my 2nd season coming to a close I think I have stock piled enough to think about processing it.

I have about 2 gallons of black sands and am wondering, what's the most efficient way to process it? I've heard about the crushing method & the heat & freeze method...but what is the best way? Are there other ways??

My plan is to document this process from beginning to end on this thread once I have determined which processing method will work best for me..who knows someone else may benefit from seeing my trial and error with black sands. Plus it will keep me busy while I'm patiently waiting for spring

 

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[KevinInColorado]

Those red nuggets look good, where can I dig for those? LoL!

 

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[Goldwasher]

Ha ha...they are good...as you can see classifying helps recovery

 

[Jimmydolittle]

A person would be hard pressed to even blow air through mesh that fine.

Doing a little research on-line I found some suppliers for finer screens ranging from 1/2 down to 1/325. I also happened across the following chart/table that gives us a good idea of the sizes we re dealing with as related to mesh sizes.

Mesh to Micron Conversion Chart

Kind of interesting if you ask me. Not that I'd want to be working with the sizes at the bottom end of the chart mind you. Those would pretty much make Talcum powder feel like 60 grit sandpaper. I remember using 5 micron wet or dry sanding film to polish the ends on fiber optic connectors and it almost felt like plain plastic.

I'd like to run some of the materials I've been working with through a 325 mesh just to see what is going on under the scope, but at $30 a sq/ft for unmounted screen I think I'll pass.

 

[goldenIrishman]

A person would be hard pressed to even blow air through mesh that fine.

Yeah... Sounds like high pressure filter material to me. If gold is THAT small... I say give it back to Mother Earth. Might as well look for a new place to be digging or be setting up a leach heap system if there's enough of that fine stuff to warrant it.

 

[goldenIrishman]

Checked that batch of -70 magnetic sand that I ran and when I opened up the barrel it was full of foam! Lots of the material was in suspension so I know it was ground down super fine. It was pretty messy and I ended up with about a teaspoons worth of non-magnetic materials left over after using the magnet on it. I did find a couple of flakes in it but I was in a hurry this morning so I didn't finish all of it. Those flakes had been rolled so thin that it looked almost like gold leaf. Since I'm running out of light here I'll have to finish cleaning it up tomorrow to see what else is in that messy mix that came out of the tumbler. The flakes I did get out were rolled so thin that the slightest amount of water was causing them to move and I almost mistook them for flakes of mica. I'm going to have to be very careful panning the rest of this stuff down. I will also be throwing some samples under the scope to have a look at it.

 

[KevinInColorado]

How big is your processing barrel GI?

 

[goldenIrishman]

It's one of those home rock tumbler barrels Kev. Not supposed to be loaded over 3 pounds each of running two of them. Maybe 6 inches tall and about as big around as a four-deuce mortar round. If you want exact measurements I'll have to get out the tape measure. I've been loading up a single barrel with about 4 pounds of rods, materials and water and it's been running pretty well. BTW.. Can I interest you in some magnetic talcum powder? That's how fine it rendered that -70 stuff down to.

 

[KevinInColorado]

It's one of those home rock tumbler barrels Kev. Not supposed to be loaded over 3 pounds each of running two of them. Maybe 6 inches tall and about as big around as a four-deuce mortar round. If you want exact measurements I'll have to get out the tape measure. I've been loading up a single barrel with about 4 pounds of rods, materials and water and it's been running pretty well. BTW.. Can I interest you in some magnetic talcum powder? That's how fine it rendered that -70 stuff down to.

Cool thanks. I'm asking for a sense of how big of a barrel you put 1/4 cup of material into. I've been running smaller amounts with just the few rods I had. Now that I have more rod stock, I really need to get it cut up and do a run like yours. Also I've only run +30 mesh magnetic material if I remember right so I also want to do non-mags and smaller mags too (I have plenty of spent cons to work with). I want to finish this testing and crank thru my stockpile of material. We plan to sell the house in the spring and I DON'T want to move spent concentrates. We will have enough to move after 19 years in the same house!!

 

[goldenIrishman]

Yeah... I can understand that. Moving is bad enough as it is and there's no sense hauling anything you don't have to.

Weather allowing I'll get the rest of that last batch cleaned out tomorrow and will let you know what I found. Being rushed this morning I did a very down and dirty job on them and I know they need more attention before I pronounce them as dead.

Things I need to look into/find something to prevent the slurry from foaming up like it did. I'm sure that there is something available on the market. I just hope it's not going to cost an arm and a leg or only be available in 55 gallon drums!

 

[Clay Diggins]

Yeah... I can understand that. Moving is bad enough as it is and there's no sense hauling anything you don't have to.

Weather allowing I'll get the rest of that last batch cleaned out tomorrow and will let you know what I found. Being rushed this morning I did a very down and dirty job on them and I know they need more attention before I pronounce them as dead.

Things I need to look into/find something to prevent the slurry from foaming up like it did. I'm sure that there is something available on the market. I just hope it's not going to cost an arm and a leg or only be available in 55 gallon drums!

Light machine oil (3 in 1) or even more effective Polydimethylsiloxane (PDMS) will kill your foaming. Don't contaminate your regular processing equipment with either one of them or you will really regret it.

Heavy Pans

 

[goldenIrishman]

A quick search showed me that the PDMS (I'm to lazy to type that full name out!) is also sold as Trombone slide oil! I'm not real hot on the idea of introducing any kind of oil or silicon compounds into my processing if I can avoid it. I'm thinking that part of the problem was that I opened up the tumbler barrel right after I took it off the drive base. Next time I'll let it sit for a while before I open it up and see if that makes any difference. I was in a rush this morning and think I shouldn't have opened it up quite so quick.

 

[johnedoe]

NO OILS.........
Use 1 drop of jet-dry.

 

[johnedoe]

I'm going to have to be very careful panning the rest of this stuff down. I will also be throwing some samples under the scope to have a look at it.

You don't pan the milled material..... You use screens... that's why while you are reducing the size of the gangue material the gold is flattened and effectively increases it's size......
It's a good thing I stick around here to keep you guys on the straight and narrow............ OH, and lets see some pics.

 

[mytimetoshine]

Jd the rod mill nazi.. lmao.

 

[arizau]

Yeah... Sounds like high pressure filter material to me. If gold is THAT small... I say give it back to Mother Earth. Might as well look for a new place to be digging or be setting up a leach heap system if there's enough of that fine stuff to warrant it.

Edit.....Oops....That is not the quote I meant to use. It is the one where you mentioned foaming.

If I recall correctly you pretty much doubled up the water over what the original concept recommends (I know the load was unbalanced so that is why you added but did you let it run for a while to see if it would self correct?). If you back off on some of the additional water it might help to prevent the foaming by forming a thicker slurry. I know you are starting with already small and I hope "closely classified" material so, it seems to me, the grind time can be reduced from what you are doing too. I would add that some amount of under grind is probably better than over grind or at least it is in mine milling processes and they put screens in place to add oversize back to the mill. You too can always add it back with equal sized material. The original concept is basically to change the size of everything (gold as big or bigger than it was and everything else smaller than the screen it originally passed), re-screen and recover and not necessarily to grind what you can to powder then recover. I put these out there as reminders and not as criticism.

Good luck.

 

[johnedoe]

Jd the rod mill nazi.. lmao.

If you guys would PAY ATTENTION... I would not have to have you continually showing me your papers.........

 

[mytimetoshine]

If you guys would PAY ATTENTION... I would not have to have you continually showing me your papers.........

Hey man if feel your pain. The concept isn't complicated. Obviously we are all putting together make shift devices but how hard is it to understand the flatten vs crush and sieve vs pan theory?!?

 

[johnedoe]

Hey man if feel your pain. The concept isn't complicated. Obviously we are all putting together make shift devices but how hard is it to understand the flatten vs crush and sieve vs pan theory?!?

The nature of humans is to take seemingly simple concepts and complicate them beyond recognition and usefulness......
Nothing wrong with makeshift devices as long as they stay within the proven parameters..... It's just not that difficult.
Good god you'd think some of these guys worked for the gov or something......

See, I do have a sense of humor...............

 

[goldenIrishman]

Well John, let me put it this way. I am not using a drive with adjustable speed so there are going to have to be some adjustments made to what the PDF states. At times there is nothing wrong with reinventing the wheel because SOMETIMES you can come up with a better wheel. Now given that I'm locked in on the speed of the unit, I've got no choice but to adjust the mix in the barrel and do some playing around with times, rod combinations and material/water ratios to find what works best for the setup that I have. The few pieces of gold that I did get out of this last batch would have been doing good to be caught in a 100 mesh screen which is finest one I have on hand. The tumbler was bought for doing amalgamation but I'm trying to see if I can get away from that process. Using it as a rod mill was never the intent for this unit. Grinding magnetic sands was never the intent either. What no one here knows is that I'm also tracking every batch on a spread sheet so I can chart the results and see the numbers to find out what works best for my particular setup. I don't know if the site here will allow me to upload an Excel file, but when I've finished my experiments with this setup I'll be more than glad to share the information with others that want to use the same setup that I'm working with. If I can't upload then I can always e-mail them to interested people.

I happened to decide to try a batch of magnetic sands was just to see what happens. Nothing more, nothing less. Maybe grinding down larger mesh sizes on magnetics will yield larger gold that can be caught in a screen, but maybe starting with -70 isn't the best way to be finding gold large enough to be caught in a 100 mesh classifier to start with. Any experiment like this is subject to many variables. Just because it happens to work (or not) with the materials in my area of Arizona doesn't mean that someone in California, Oregon or Nevada can always expect the same results. Heck... I could end up with different results with materials from Gold Basin and a wash only a few miles away for that matter. There is always the X factor to consider. Remember... your mileage may vary....

Oh.... Just so you know... I WAS a government contractor for a lot of years. I've worked for the Navy and Border Patrol on the federal level as well as most of the counties in S.California.

 

[Oregon Viking]

I think I'am going to build one. How it will work on black beach sand will be a good test.