Crushing black sands

[Dr. Meh]

What's the best way to grind black sand to powder to release the gold and platinum?

 

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[GoldFool]

Kevin, seeking black sand crusher that is most affordable. Was surprised to read a coffee grinder would be acceptable for this. But you then say "not the one at the grocery store". Pardon my ignorance, but which coffee grinder are you referring to specifically? And being one that would still be a less expensive option for this by downgrading to just a coffee grinder.. Or hmm, ....hard to explain. So where its not some high tech coffee grinder whose cost would make you question why youre botherring with a coffee grinder since its not the one you'd buy at the grocery store which would be the cheaper route. If that made any freakin sense

 

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[ConceptualizedNetherlandr]

Didn't I put out the solution long ago? Sand blast the stuff against a steel wall. (into a tube with the end over a water bucket...)

 

[WesternMassGold]

The real question here is : Why would you spend hundreds of Dollars to recover 2 or 3 cents worth of gold?
If the gold is so small that you can't even see it with a magnifying glass then you probably need a million pieces to make it worth 1 Dollar. You are better off spending the time in the river scooping for bigger gold.
That's just my 2 cents.

 

[ConceptualizedNetherlandr]

The real question here is : Why would you spend hundreds of Dollars to recover 2 or 3 cents worth of gold?
If the gold is so small that you can't even see it with a magnifying glass then you probably need a million pieces to make it worth 1 Dollar. You are better off spending the time in the river scooping for bigger gold.
That's just my 2 cents.

I guess if you accumulate a 55 gallon drum of the stuff and it is 25 OZ /ton ...

Keep in mind the largest gold deposit in this country is found as a contaminant in pyrite (in limestone) and is 'solution' gold - yup molecular sized. Go figger ...

Chemistry is your friend.

 

[KevinInColorado]

Kevin, seeking black sand crusher that is most affordable. Was surprised to read a coffee grinder would be acceptable for this. But you then say "not the one at the grocery store". Pardon my ignorance, but which coffee grinder are you referring to specifically? And being one that would still be a less expensive option for this by downgrading to just a coffee grinder.. Or hmm, ....hard to explain. So where its not some high tech coffee grinder whose cost would make you question why youre botherring with a coffee grinder since its not the one you'd buy at the grocery store which would be the cheaper route. If that made any freakin sense

I was kidding around. I meant don’t feed your thru the coffee grinder owned by the grocery store!

Instead use one like this:

 

[Duckwalk]

I do a bit of blacksmithing as a hobby. If i was going to fashion my own blade, it would be either out of 5160 (think leaf spring) or maybe even HSS (High Speed Steel) its what drill bits are made of.

 

[ConceptualizedNetherlandr]

I ground some case hardened files down to blades with equal length handles. Cuts a .30-06 in half vertically. Case and copper jacketed bullet. (sans primer and powder) Over 15 years ago, haven't sharpened them since. Weakness is brittleness. I broke one while hammering the back side on a cut.

 

[johngfoster]

Pardon my ignorance, but let me get this straight: Am I correctly understanding that there is actually gold INSIDE grains of black sand? This is in addition to the fine flour-gold mixed in with the black sand that you have to separate out by panning?

 

[Aufisher]

Yes and sometimes larger pieces

 

[KevinInColorado]

Pardon my ignorance, but let me get this straight: Am I correctly understanding that there is actually gold INSIDE grains of black sand? This is in addition to the fine flour-gold mixed in with the black sand that you have to separate out by panning?

Yup. Several years ago I built a benchtop rod mill. Ran some black sands in it and found gold. If you search here in tnet, you’ll find the thread. Info on how to build, gold results, etc.

 

[ecmjamsit]

I have smelted a lot of black sand from the Arkansas river. I never could get any thing from it. I used a magnet to remove the magnetite. If you get gold from a "black sand" you are probably cleaning off a stain of magnese. It will coat gold and make it dark. If it is magnese stained gold a fire assay in a smelter with the appropriate flux will always release the gold. I have a large carbide crucible I found near my mining claim, and it is coated with black sand residue. Under a 100X microscope, I can see little spherules of gold embedded. If want the gold you always have to play with fire. I will try and get some pics to post tomorrow. Not sure I can get pics of the gold bits as they are so small.

 

[johngfoster]

I'll have to start saving my black sand then. I've seen some YouTube videos of people extracting gold from black sand, but I thought this was just the fine gold that they missed panning out the black sands. It also seemed to be a very tedious process and not at all cost-effective with all the chemicals they had to use. You guys who do it--how do you do it? Mercury retort? Fire it in a kiln? How do you do this in a cost-effective way?

 

[ecmjamsit]

Molten black sand

Here are some pictures of an old graphite crucible that is broken. The top layer is molten black sand. It stuck to the sides of the crucible. The white/light gray material is probably a flux material used used to cure the crucible and prevent any sulfides from corroding away the graphite. The lower and thickest layer is the graphite crucible. This crucible would probably hold a charge of about 40 lbs of material to be smelted. The gold was most likely mined from a sluice box that was very long. It is a very fine gold. Before I would get too excited about black sand, I would look at it with a small plastic Micronta 100X microscope. If you can't see any gold, it just isn't worth messing with. Hope this helps.





View attachment Cruci1.jpg View attachment Cruci2.jpg View attachment Cruci3.jpg

 

[KevinInColorado]

I'll have to start saving my black sand then. I've seen some YouTube videos of people extracting gold from black sand, but I thought this was just the fine gold that they missed panning out the black sands. It also seemed to be a very tedious process and not at all cost-effective with all the chemicals they had to use. You guys who do it--how do you do it? Mercury retort? Fire it in a kiln? How do you do this in a cost-effective way?

The cost effective way is to crush and classify and pan.

 

[arizau]

The cost effective way is to crush and classify and pan.

Assuming you have already carefully panned the concentrates....even that(see above) is a "When I aint got nothing better to do" thang. Save um up for that day....or not and take up whittling.

 

[placertogo]

What is rarely discussed when considering final processing of black sand concentrates is that the dynamic and kinematic viscosity of water decreases with temperature. In other words, processing in warm or hot water produces better results than in cold water. Many people use detergent or something like “Jet Dry” to reduce surface tension but forget about the advantages of using warmer water.

 

[johngfoster]

Would a Gold Cube or a Blue Bowl make this process easier? A Miller table?

 

[arizau]

Would a Gold Cube or a Blue Bowl make this process easier? A Miller table?

The gold cube is a concentrator either for primary use in the field fed by prescreened material or for "super concentrating" collected concentrates from whatever method. The final cons need to be panned or otherwise processed to recover the gold. The miller table and the blue bowl are two ways to, as mentioned in the previous sentence, "otherwise process". It is still best to screen and run separately by size fraction to use them efficiently.

As an alternative to the cube, the goldhog multi sluice Multi Sluice - Gold Concentrator is a concentrate cleaner that strips almost all of the black sand out and produces an almost all gold product that needs very little further processing. It's price is less than the cube and it can also be used as a small high banker for field use. IMO, if you get a goldhog or a cube or just use what you already have, then forget about the miller table and blue bowl but do get a set of screen classifiers that include 20, 40 or 50, 100 and maybe 150 mesh. Even if you don't get one of them, the use of classifiers and a pan will make it easy to pan your concentrates and recover more than 99% by weight of any gold you have in the concentrates from any source....save the black sands after any of these processes if you still wish to crush/pulverize them, then screen and pan again. In that process any gold mostly just changes shape and can actually grow to a larger mesh size without weight loss while black sands shatter, sometimes to powder, thus the need to re-screen. I doubt you will do this more than once thinking that it will not be worth the effort after seeing the results.

Good luck

 

[johngfoster]

Yeah, after watching some YouTube videos of a guy who processed 6lbs of black sands, using acids and baking soda (cost him about $250 in materials), and then seeing how much gold he was able to recover out of it, I was not impressed with the results. IF I ever try this, it would need to be done in a way that was cheap, and not overly time consuming. As it is, panning out my black sands concentrates is almost not worth it for the gold I'm finding. Almost. ;-)