Time of flight separation of gold from creek sand

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Re: Time of flight separation of gold from creek sand

Postby Bill Fain » Sat Nov 13, 2010 10:20 am

Hi, Well I installed my sluice(s) Thursday. Now to let them sit through a few heavy rains and see what they might contain. That is of course is if they aren't stolen, shot up, or washed to the ocean.
Long sluice in place
The long sluice also has a split open gutter drain attachment connected to one side. I did this because I was looking for different plug 'n play items that might collect heavy minerals differently. It has deep, more angled riffles (maybe rifes? not sure)than the drain pipe.
Golden Fleece
. Here is the Chris Bradley suggested "Golden Fleece" shag carpet. We'll see what it yields.
Dryer Vent
And of course, here is an old favorite: Flattened out aluminum dryer vent. Still I was looking for something with different sized and spaced riffles. This may be my undoing though; as it is highly noticeable and has some value ($0.55/lb) Now I would appreciate it if someone can suggest how I get the contents out of the long sluice; without pulling it up each time. Wet vac maybe? -bill
Last edited by Bill Fain on Sun Nov 14, 2010 8:03 pm, edited 2 times in total.
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Re: Time of flight separation of gold from creek sand

Postby Bill Fain » Sat Nov 13, 2010 12:42 pm

Hi, Just thought I show the contents of a small amount of concentrates I panned from Western North Carolina and ask a few questions. I promise to use a black bowl next time; as it has better contrast.
Pesky flakes of Gold
Notice a few "pickers" of gold. There is apparently a lot of "flour" gold too.
Stuff other than gold
Now this is the stuff that wants to be in the pan with gold. An experienced "panner" can wash this out easily. Now when I was up at Doug's the other day, I wondered if this was radioactive. We placed a small amount of it on the Geo pancake detector and got a count about 450cpm above background. So I theorize that this contains a lot of Monazite or maybe even Uranium. We don't have a good gamma spectrometer, so we don't know right now. Now these pictures were taken after I pulled out the magnetite with a magnet. (I could not detect anything much over background in the magnetite). With the high price, or more likely, the unavailability of rare earth minerals, I wonder if the monazite can be mined economically today from the creek sands. This table is not correct in that it lists some pure metals and I don't know at this moment which oxides or sulfates etc. the metals actually exist in nature. Also I need to get in touch with USGS or the North Carolina equivalent to find out what is actually in there. Of course with the fusor and a good gamma spec, we would know for sure. Here is a link to the rare earth etc. in Monazite.
Attached are two tables of relative densities of stuff that is or maybe is in the creek sand I panned.

Sorted by low Sorted by high
Sp/gr Sp/gr
Element/compound Element/compound
low high low high
mica 1.6 2.88 sio2 2.65 2.65
sio2 2.65 2.65 quartz 2.65 2.65
quartz 2.65 2.65 mica 1.6 2.88
garnet 3 4.25 garnet 3 4.25
monazite 4.6 5.7 pyrite 5.1 5.1
pyrite 5.1 5.1 magnetite 5.17 5.18
magnetite 5.17 5.18 monazite 4.6 5.7
zirconium 6.5 6.5 zirconium 6.5 6.5
silver 10.5 10.5 silver 10.5 10.5
thorium 11.72 11.72 thorium 11.72 11.72
uranium 18.95 18.95 uranium 18.95 18.95
gold 19.28 19.28 gold 9.28 19.28
platinum 21.4 21.4 platinum 21.4 21.4
(sorry about the table spacing. I formatted it several times and it still looks like this; should I use the Quote function?)

Maybe the Sio2/Quartz is as pure as it is at Spruce Pine,NC (source of all the world's silicon for electronic chips). -bill
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Re: Time of flight separation of gold from creek sand

Postby Doug Coulter » Sun Nov 14, 2010 7:51 pm

Now you guys have me thinking about this (the fact that Bill brought me a 5 gal pail of gold bearing sand didn't hurt).

What I'd like to find is a dense liquid, preferably clear, that wasn't fluoinert (too doggone expensive, that stuff, but it's very dense as liquids go). A density of 2-3 would be a lot better than water for what I have in mind here, and of course, I don't want to use mercury or lead, both of which combine with gold (easier to get it back from mercury, though, in a vacuum distillation rig, which I happen to have).

I envision a sloped ramp, which I push this fluid UP, as in a sheet-jet at some speed, so it goes up over the top of the ramp. By adjusting the parameters of slope and flow rate, you should be able to create what amounts to continuous panning, with the light stuff being carried up over the top, and the gold staying down in the bottom. One big feature of this is of course you also catch the "discard" stuff, so you can run it through again in case it still has some gold in it.

The problem with doing this with water or anything else much less dense than rocks is that you then need a high velocity flow. In a high velocity flow, the density of the stuff won't matter as much as its surface area to volume ratio will, so it won't separate as well as the "perfect" fluid, which would simply float the rocks and let the gold sink. Which is why normal panning is hard work and takes some skill. I'm trying to make it dumb enough that a simple machine can do it. It would be rather nice not to have to sieve all the stuff first to get uniform sizes, as you'd add a lot of work and steps doing that. Not to mention, good sieves aren't cheap and don't last forever, either.

I could consider using some molten metal, but -- gold alloys with nearly all of them easily (anyone have more data on that? AFAIK, gold pretty much alloys with everything), then how to get it back out of there? So, not so good, and dealing with high temps means a pretty special pump, too.

I know in the other mining businesses they will use a slurry of something to get the density up, but that won't be clear, and won't stay a slurry without a lot of agitation, so that's a last resort from my point of view. Further, it could conplicate keeping the discards for another pass.

Here's one I found, TBE or tetrabromoethane. Sand floats, pyrite sinks, no motion needed at all for that. So that's getting into the range of density that would really help a lot.

Here's another good link
http://en.wikipedia.org/wiki/Electrosta ... separation
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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