New Zealand Gold Prospecting & Metal Detecting Forums Archive

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Separating gold/sand

nuggetman		Posted : Thursday, 30 September 2010 11:59:56 AM(UTC)
Rank: Gold Dust Groups: Registered Joined: 5/08/2010(UTC) Posts: 5 Location: New Plymouth<NZ		Hi. I have a few ounces of very small gold flakes mixed with sand etc that I panned at Tadmor a while ago. A magnet from an old hard drive(in a plastic bag)removed all the ironsand effectively but the remaining opaque sand and tiny garnets are hard to remove.Using a high-powered magnifying glass it is possible to sort out 1 grain at a time! Recovering about 20 grains took 6 hours today. I would welcome any suggestions on how to speed up the process.Thanks.

criticol		Posted : Thursday, 30 September 2010 3:08:07 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 14/05/2010(UTC) Posts: 234 Location: coromandel Thanks: 72 times Was thanked: 66 time(s) in 48 post(s)		Hi Nuggetman. I am sure hat you will get some helpful replies to your request, In the meantime you may find this site interesting? http://webpages.charter....lliams00/bcftp/bcftp.htm Fine gold recovery usually involves acids, or mercury, recovery methods. (all fairly dangerous to work with.) One method that could be of “Merit” in recovering all the fine gold in Black sands could very likely be achieved by Electrolysis, or basically by electroplating the gold out of a suitable solution on to say “Copper“, and then dissolving the copper away. I played around with this method many, many years ago, and have now lost all my research papers. But the information’s for using un-dangerous methods of attempting this approach are available with the Internets search capabilities. From memory: (don’t quote me here!) but a 9volt battery is used as the power source. And some solution of salt ( I think that Sea water can be used? ) is used to carry the current between the “Anode”, and “Cathode” of the plating solution. I’m sure that a bit of research into “Electroplating gold without acids” could pay dividends for you. “I hope so anyway”. Sorry about my faded memory over this. If the gold can be plated out on to a conducting powder, (Graphite, was an old method.) that is smeared on to say, “Plastic” then you could just Peel the plated gold off this medium? You could try a hardware store for graphite powder, Or you can grind up some ordinary “Pencil” leads, if you cant obtain it easily, Cheers---Colin. Edited by user Thursday, 30 September 2010 3:10:20 PM(UTC) \| Reason: Not specified
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nzgold		Posted : Friday, 1 October 2010 2:21:49 AM(UTC)
Rank: Gold Nugget Groups: Registered Joined: 5/08/2010(UTC) Posts: 97 Location: New Zealand Thanks: 23 times Was thanked: 20 time(s) in 19 post(s)		Hi nuggetman, If you've removed all of the most magnetic (heaviest) sands with your magnet, DON"T throw it away. The magnet works well, but it will usually pinch at least some gold when it picks up the ironsand. Keep that black sand and you may be able to recover more gold from it at a later date. I was in the same situation as this, no ironsand left, And had a cup of really concentrated gold and sand. Used some black ribbed rubber matting, with a hose clamped at the top of it to keep the water flow steady. if you buy some black, ribbed rubber matting (You could ask about it here: http://www.dredgenz.co.nz) Mix the concentrates up with dishwashing liquid and water, and have the rubber matting set up so that it's going into a pan (YOu can run it through again if any is lost) Then just feed it through real slowly with a spoon. Another option would be to do what Colin said, use chemicals to get it out. This option would be most efficent, and seeing as you have a reasonable amount of gold, It probably would be worth buying the chemicals to do it. But just keep in mind that you have to be careful with acids, particularly Hydofluoric acid, it can burn you badly. Mercury can be dangerous too ( If you're burning it off, don't breath in the fumes whatever you do) The only other suggestion I have is you could use a blue bowl? Haven't used one myself, but some other members on here have? and they're supposed to be pretty good too. CHeers :)

criticol		Posted : Friday, 1 October 2010 4:21:40 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 14/05/2010(UTC) Posts: 234 Location: coromandel Thanks: 72 times Was thanked: 66 time(s) in 48 post(s)		Hi, NZGOLD. Not being picky! But I presume you mean "Hydrochloric" acid. Not, "Hydrofloric", as this acid is "EXTREMELY" dangerous to work with. and "DEFINITELY" not one that the average fossicker should even consider using.) Cheers---Colin.
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nzgold		Posted : Friday, 1 October 2010 8:26:44 AM(UTC)
Rank: Gold Nugget Groups: Registered Joined: 5/08/2010(UTC) Posts: 97 Location: New Zealand Thanks: 23 times Was thanked: 20 time(s) in 19 post(s)		Colin, yep I was meaning hydrofluoric not hydrochloric. It's pretty nasty stuff if you get it on you. However it you're careful and wear all the right safety gear it'd be OK to use. No most prospectors wouldn't bother using it.

criticol		Posted : Friday, 1 October 2010 3:11:26 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 14/05/2010(UTC) Posts: 234 Location: coromandel Thanks: 72 times Was thanked: 66 time(s) in 48 post(s)		Hi there, NZGOLD. O.K. You did mean Hydrofloric Acid. What seems sort of strange to me, is that I cant recall ever hearing of it being used to recover fine gold at all. Heres hoping that you can give me a quick brief on how it is used to achieve this result. :) Thanks muchly, and Cheers---Colin. Edited by user Friday, 1 October 2010 3:12:36 PM(UTC) \| Reason: Not specified
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nzgold		Posted : Saturday, 2 October 2010 2:06:41 AM(UTC)
Rank: Gold Nugget Groups: Registered Joined: 5/08/2010(UTC) Posts: 97 Location: New Zealand Thanks: 23 times Was thanked: 20 time(s) in 19 post(s)		Hi Colin, no I don't know of it being used to clean up fine gold, but quite a few people use either HF or HCL (or both) to clean up gold specimens/nuggets. I've heard it can be pretty dangerous stuff. I haven't used it myself, except in low concentrations in a Chemistry class. Good luck :) Regards nzgold

roman holiday		Posted : Monday, 4 October 2010 9:42:28 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 26/04/2010(UTC) Posts: 147 Location: Tauranga Thanks: 18 times Was thanked: 8 time(s) in 7 post(s)		Not sure if this helps, but I remember once seeing some dude using air flow to separate the heavier gold from the lighter material. Put a bit of your mix on shiny paper then blow or use a fan at the appropriate speed distance. Edited by user Monday, 4 October 2010 9:43:00 AM(UTC) \| Reason: Not specified

Flintlock		Posted : Thursday, 23 December 2010 8:48:02 AM(UTC)
Rank: Gold Nugget Groups: Registered Joined: 9/08/2010(UTC) Posts: 53 Location: Ashburton Thanks: 9 times Was thanked: 11 time(s) in 8 post(s)		roman holiday wrote: Not sure if this helps, but I remember once seeing some dude using air flow to separate the heavier gold from the lighter material. Put a bit of your mix on shiny paper then blow or use a fan at the appropriate speed distance. When I have panned as much of the sand off as I can and just have the very fine sand left I put the pan on the stove (metal pan of course) and dry out the sand. Then I sit outside and gently blow across the pan. The fine sand, being lighter blows off the opposite side of the pan. You have to fine tune your technique as to tilt of pan and strength of huff, but it does work. Cheers Ian Edited by user Friday, 14 January 2011 2:57:29 PM(UTC) \| Reason: Not specified

onegram		Posted : Monday, 30 January 2012 12:58:10 AM(UTC)
Rank: Gold Flake Medals: Groups: Registered Joined: 18/01/2012(UTC) Posts: 14 Location: Australia Thanks: 5 times Was thanked: 4 time(s) in 3 post(s)		Originally Posted by: criticol Hi there, NZGOLD. O.K. You did mean Hydrofloric Acid. What seems sort of strange to me, is that I cant recall ever hearing of it being used to recover fine gold at all. Heres hoping that you can give me a quick brief on how it is used to achieve this result. :) Thanks muchly, and Cheers---Colin. Hi Colin, This comment is a bit late (very late actually) mostly because I only joined the Forum a couple of weeks ago and have only now gotten to reading your post. You will probably have gotten the answer long ago but in case you haven't......... Hydrofluoric acid does NOT dissolve metallic gold nor does hydrochloric acid (by itself) though it is one of the few chemicals that will dissolve quartz, glass etc and presumably(?) some silicon-containing minerals and that is why it is sometimes used for cleaning up (not dissolving!) gold samples. BUT as noted elsewhere, it is very dangerous stuff which causes non-healing injuries if inhaled or spilt on you. If you want to use it for cleaning get expert advice on handling it first! cheers, onegram

chchfossiker		Posted : Monday, 30 January 2012 5:58:53 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 5/05/2011(UTC) Posts: 151 Location: christchurch Thanks: 9 times Was thanked: 15 time(s) in 12 post(s)		hey all i use hydrochloric and hydrofloric acid on a regular basis. not for gold clean up but for work. if you need any tips on useing it id be happy to help. and yep its very dangerous stuff.

mineforgold.co.nz		Posted : Monday, 30 January 2012 11:48:18 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 14/11/2011(UTC) Posts: 299 Location: Nelson Thanks: 58 times Was thanked: 38 time(s) in 35 post(s)		For those that haven't seen it - The Gold Lab is a much safer alternative to chemical recovery. Probably not an investment for a casual prospector, but for anyone that processes a reasonable amount I am sure it would pay for itself in no time. [Disclaimer - I do sell them].
		Own: Lobo SuperTraq, Garrett ATPro, Minelab Excalibur
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simon		Posted : Monday, 30 January 2012 12:56:44 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 7/01/2011(UTC) Posts: 789 Location: Central Otago Thanks: 33 times Was thanked: 239 time(s) in 150 post(s)		i think we're forgetting a lot of us are only talking of part time hobby quantities of black sand containing gold and aren't looking to spend up big. the old timers had a slow but successful method of separation that doesn't require any dodgy chemicals. you simply dry out the black sands, magnet off the black sand, place the remaining particles of sand/gold/black sand dust etc on a white piece of paper and gently blow until the lighter materials blows to the outer edge of the paper. this can be quite tedious if you have to do it daily or regularly. ok to save for a wet day. what i did is buy a black sand plastic moulded concentrator from the guy above. it was about $65 i think. you simply bungy cord it onto a bucket and connect to your garden hose. the trick is to get the flow right. some gold does get lost, thus you simply repeat the process. i would save up my summer concentrates and treat them this way. the reason some gold was lost was the pieces were so small. often they would be incredibly thin tiny flakes. from a whole bucket of black sand i got less than a gram of fine gold dust. this was what i reprocessed after magneting and blowing as per above. i figured with such a small loss it was more efficient to put this extra time in back at the river and simply ditch this reprocessing in the end. now a have a golden garden with gold laced black sands instead.
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mineforgold.co.nz		Posted : Monday, 30 January 2012 4:16:44 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 14/11/2011(UTC) Posts: 299 Location: Nelson Thanks: 58 times Was thanked: 38 time(s) in 35 post(s)		Thanks Simon. If you get an inline tap that clips on the end of your hose (a couple of bucks from a hardware store) it makes fine tuning the flow easier. Another thing that might be worth trying is using a pump and having it set up on recirculation system so that you can add some surfactant. Or as you say, plenty more in the river.
		Own: Lobo SuperTraq, Garrett ATPro, Minelab Excalibur
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rob		Posted : Sunday, 5 February 2012 10:52:34 PM(UTC)
Rank: Gold Flake Groups: Registered Joined: 8/09/2011(UTC) Posts: 11 Location: Dunedin Thanks: 8 times Was thanked: 2 time(s) in 2 post(s)		If i have a bit of super fine in concentrate (beach gold etc) i tend to use aqua regia, works well and as said before very dangerous, use a fume hood or do outside (well ventilated) etc.

LepreSean		Posted : Thursday, 16 February 2012 12:08:44 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 8/12/2011(UTC) Posts: 171 Location: Wherever I may roam Thanks: 187 times Was thanked: 130 time(s) in 78 post(s)		http://www.youtube.com/watch?v=upcKLHSgsHs this should help,
		auri sacra fames (accursed hunger for gold)