Previous in Forum: Electric/Electronic means to eradicate moles   Next in Forum: Face to Face Interviews
Close
Close
Close
48 comments
Anonymous Poster

Gold flake/foil refining

09/07/2007 11:52 PM

I have several ounces of near 24K gold flake/foil that I recovered from Gold Hardness (Knoop micro-hardness) test panels. These test panels were plated with as much as .005" of high purity gold that was usually Ni hardened and plated on Ni or Cu panels. I have carefully disolved these substrates with Nitric acid leaving only the Au undisolved in flake/foil form. I am trying to increase the purity of the Au to 24K. I have done this recovery in the past without attempting to increase purity and feel I am being cheated by my current processor. Therefore I want to make this into a 24K nugget that I can then sell on ebay. When I do the melt (in a ceramic crucible with an aceteline torch) what can I do to remove the residual Ni and possible Cu that are surely contaminating my gold and lowering the purity/value. Any help is appreciated. My facilities are very limited (single crucible used for melting and cooling after the torch melting process).

Reply
Interested in this discussion?
You can "subscribe" to this discussion to be notified of new comments.
Click on the Subscribe menu at the top of the page.

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Guru
United Kingdom - Member - New Member Hobbies - Musician - New Member Engineering Fields - Mechanical Engineering - New Member Hobbies - Target Shooting - New Member Engineering Fields - Power Engineering - New Member Hobbies - Fishing - New Member

Join Date: Mar 2007
Location: South-east corner of Spain 50 48 49.24N 2 28 27.70W
Posts: 1508
Good Answers: 31
#1

Re: Gold flake/foil refining

09/08/2007 3:50 AM

I may be wrong, but I saw a documentry on science shack and they used a spud! The spud absorbed all the other stuff but not the gold! Pretty cool I thought!

__________________
“It's kind of fun to do the impossible.” Walt Disney
Reply
Power-User

Join Date: Mar 2007
Posts: 158
Good Answers: 2
#3
In reply to #1

Re: Gold flake/foil refining

09/09/2007 12:58 AM

I believe what your referring to is the mercury spud. They used liquid mercury to absorb the impurities in the gold concentrate, hollowed out a "Spud", placed the plug of liquid mercury in the hollow, wired it close put it in a fire and let the mercury burn off along with the impurities. That works but the danger from the mercury vapors makes it a questionable procedure. I think that it resulted in near pure forms of gold.

Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 49
#29
In reply to #1

Re: Gold flake/foil refining

09/15/2007 1:34 AM

Among his other accomplishments, I'll bet you didn't know he was a member of KISS!

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Reply
Participant

Join Date: Nov 2009
Posts: 3
#34
In reply to #1

Re: Gold flake/foil refining

11/25/2009 7:47 AM

where to source spud? OR how to make an improvised spud at home?

Reply Off Topic (Score 5)
Guru

Join Date: Jul 2006
Location: "Dancing over the abyss."
Posts: 4942
Good Answers: 243
#35
In reply to #34

Re: Gold flake/foil refining

11/25/2009 11:30 AM

Spud is the american english slang term for a POTATO.

milo

__________________
People say between two opposed opinions the truth lies in the middle. Not at all! Between them lies the problem, what is unseeable,eternally active life, contemplated in repose. Goethe
Reply Off Topic (Score 5)
Guru
Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3968
Good Answers: 119
#2

Re: Gold flake/foil refining

09/09/2007 12:12 AM

Archimedes method. weigh dry to .1 milligram in air and in water at 4C.

The weight difference between the two in grams is the volume in milliliters, from which the density ensues. Assume straight line gradient between Ni and Au for density. Nickel hardening uses between .2 and 2.5% weight % nickel, so worst case is is about 23.5 carat gold.

What has he been paying you?

__________________
Per Ardua Ad Astra
Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 49
#4
In reply to #2

Re: Gold flake/foil refining

09/09/2007 1:24 AM

Yeah. Get a graduated cylinder in cubic centimeters, pour distilled water into the cylinder, then dump in your gold. Next measure the displacement and compare it against the density of pure gold. This will give you an accurate reading of the purity of the gold - the math is pretty straightforward.

Once you've determined the purity, you can make confident derisions about the price of your gold. There is no reason to purify it to 24K as long as you are getting paid a fair price for its gold content.

For example, and American gold Eagle is not 24K, it's 22K, but it's a little heavier than one ounce so you are assured of getting a full ounce of 24K gold.

Make sense?

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17989
Good Answers: 200
#5
In reply to #4

Re: Gold flake/foil refining

09/09/2007 4:03 AM

It does make good sense, all of what you wrote. I have learned something too!! Many thanks.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Reply
Guru

Join Date: Jul 2006
Location: "Dancing over the abyss."
Posts: 4942
Good Answers: 243
#6
In reply to #4

Re: Gold flake/foil refining

09/09/2007 10:05 AM

I forsee problems as follows- He has gold foil flakes, foil slivers, which will not "simply displace water in the cylinder" they will likely 1) hold air bubbles and float unless mechanically agitiated; 2) depending on the thinness ofthe foils, they may attach themselves permanently to the cylinder. You will need a very precise graduated cylinder, and error of reading meniscus is likely to be as significant as your 'alloying contaminant issue' unless the cylinder is of highest precision (not just std. lab grade.)

We did the mercury / potato trick using an old gas grill outside dedicated to 'refining'. (Gold prospecting in North Georgia mountains). Not sure if it will separate the nickel. (Not sure- not saying it won't- just not sure)

Never underestimate the power of surface tension to screw up what seems to be an easy process! Archimedes was dealing with chunks, not films.

milo

__________________
People say between two opposed opinions the truth lies in the middle. Not at all! Between them lies the problem, what is unseeable,eternally active life, contemplated in repose. Goethe
Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 49
#8
In reply to #6

Re: Gold flake/foil refining

09/09/2007 4:09 PM

Yes, this is why I was debating whether to use a different liquid to find exact size... Perhaps one of the alcohols. And, yes, you'll need a little precision. But this is not outside the realm of the armature.

We don't use the potato, we use the squeezed out half a grapefruit here.

The point is that if he can determine to some reliable degree the gold content, he should be able to get a good price without having to refine it himself.

Also, what amount of damage (being crippled, being insane) to his nervous system is equivalent to a little poke of gold?!

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Reply
Anonymous Poster
#7

Re: Gold flake/foil refining

09/09/2007 2:45 PM

I will wager twice the difference in what you can get for your gold as is and what you can get for the 24c gold you can from it less the cost of refining the it better to sell it as is an do any more to it. That doesn't count what happens to the price of gold in between.

I you want to bet on the price of gold too my bet for twice the difference is on taking the money now and running with it as quick as you can is a winner.

I was playing gold the last time it did this kind of thing and got my plow cleaned in 3 days. I got out even but I was way ahead for a while.

The price of gold is good and the markets are all going where hot money drives them. As soon as the new deal comes along the old one is history as the hot money moves on to the next deal.

If gold can get some light between it that high in Mar 06 it might attract some hot money a go for a wild ride but if it does do better than than its done it risks becoming hot money and looking for a new home. If you bought gold after the fall in mar 06 you had to really buy it right to beat anyone that sacked their 13% rocking chair money they got from buying Eros with dollars and Euros sure give you a lot more time to unload them than gold.

The are a lot surer method of making money that trying to get the last bit of value out of gold. The way the price moves you could increase the yield of gold by 4% in two day and loose 10% in the market if it had a bad run.

I don't know what's next but there is train wreck down the track some were and were head for it flat out.

gc

Reply
Guru
Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3968
Good Answers: 119
#9
In reply to #7

Re: Gold flake/foil refining

09/09/2007 4:30 PM

I think the gold buyers are out to lowball you in a big way. They see you as getting free salvaged gold and want to give you 50% or less for it. They will mislead you anyway they can.

That said, if you only have 10-20 grams of gold, of unknown grade they will find it easy to low ball you.

If you have 8-10 ounces of gold per quarter and it is a provable 23+ carat you can get a fairly good price for it. Best way to maximize is to melt it into a lump which you can easily measure the density of, and sell it to a jeweller who makes lost wax castings for sale. He has the ability to weigh and measure the density and satisfy the need for purity.

That way yiu bypass the gold dealers.

one place to sell is ebay, another is http://sfbay.craigslist.org/about/cities.html

__________________
Per Ardua Ad Astra
Reply
Anonymous Poster
#10

Re: Gold flake/foil refining

09/09/2007 7:43 PM

Thanks for all the comments. I think the problem here is the way I have sold it. I used a coin store as middleman between me and whoever actually buys the 4-6 oz melts I have previously sold. I have been paid 16K, and 18K values when I know it is at least 22K. That is why I was looking for a sure method to purify to 24K so he cannot cheat me or I could sell on Ebay or elsewhere. I have about 150gms of flake/foil that I am melting Monday and was hoping there was an easy slag I could add that would suck up the Ni and Cu or whatever else is lowering the purity. I guess I will just have to pay $150 and have my local lab give me composition so I can sell based on that analysis without worrying. This is tha end of about 1000gms of Au I have recovered this way. I have never felt like I was paid fairly, but relied on others honesty. Anyhow, thanks for all the comments and NO I WOULD NEVER USE THE MERCURY/POTATO method for scavaging gold!

Reply
Guru
Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3968
Good Answers: 119
#14
In reply to #10

Re: Gold flake/foil refining

09/09/2007 9:32 PM

All you need to do is give it a known carat grade.

Just melt it into a clean shape with no voids. Then get a piece of monofilament nylon and weigh it in air and weigh it with a beaker of water covering it. with 150 grams as long as you are within 1/4 gram that is good enough.

The buyer at the coin store will not pay you any more as he is a retail gold buyer.

Never give a sucker an even break = their motto

sell it to a jewellery maker you find somewhere.

The only way to purify it easily is to dissolve it in cyanide and then precipitate it with zinc dust and remelt it. You can also melt it in a crucible with some litharge and flux

http://www.prospectorsparadise.com/html/assaying.html

__________________
Per Ardua Ad Astra
Reply
Guru

Join Date: Nov 2006
Location: KnoxTN
Posts: 1485
Good Answers: 6
#15
In reply to #10

Re: Gold flake/foil refining

09/09/2007 10:31 PM

" I have been paid 16K, and 18K values when I know it is at least 22K. "

Out of economic necessity the coin dealer or any middle man MUST pay for less gold content than the actual amount. Otherwise they have to go out of business. It is called profit or the cost of doing business. They don't get a free ride nor should you expect one.

The price of new gold or silver sheet rod or other forms will be higher in the daily spot metal price due to cost of fabrication and profit margin. The price paid for scrap gold or silver is below spot prices to cover cost of refining and profit margin.

It is a matter of basic business economics.

__________________
Do Nothing Simply When a Way Can be Found to Make it Complex and Wonderful
Reply Score 1 for Good Answer
Commentator

Join Date: Jan 2006
Location: Quad Cities Illinois
Posts: 56
Good Answers: 1
#17
In reply to #10

Re: Gold flake/foil refining

09/10/2007 7:21 AM

I wouldn't sell my gold now, regardless of purity. We are on the verge of a significant economic downturn, possibly a recession. At some point money is going to look for safe havens in metals, and other tangible assets. Gold is closing in on a 26 year high right now, and once it breaks that threshhold, it will go nuts. Hold on to your gold. If you must sell it, and I can be reasonably sure of your gold's purity, I will buy it for spot price from you.

Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17989
Good Answers: 200
#19
In reply to #17

Re: Gold flake/foil refining

09/10/2007 2:07 PM

You said:- "Hold on to your gold", I would like to add also "Hold on to your Nuts too"!!! Keep them out of harms way!!!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Reply
Participant

Join Date: Nov 2009
Posts: 3
#33
In reply to #17

Re: Gold flake/foil refining

11/25/2009 7:38 AM

If you are interested to buy gold dust with 99.99 purity, I can supply you from India . I say 99.99 pirity as I have refined it using Aqua Regia Method.

Reply Off Topic (Score 5)
Guru

Join Date: Nov 2006
Location: KnoxTN
Posts: 1485
Good Answers: 6
#11

Re: Gold flake/foil refining

09/09/2007 7:55 PM

" I am trying to increase the purity of the Au to 24K."

As others has asked, WHY? In pepraration to sell of for some use you will have for it. Gold buyers sell it to refiners and pay for gold content. you can waste time and money as well expose yourself to health risks as a DIY gold refiner.

Cupellation and other Processes for refining gold jewelry scraps and wastes

Generally it is financial folly to try to do a difficult process your self when others can do it for you much more economically.

__________________
Do Nothing Simply When a Way Can be Found to Make it Complex and Wonderful
Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17989
Good Answers: 200
#12

Re: Gold flake/foil refining

09/09/2007 8:00 PM

Actually, even if you have 24k Gold but its dirty, its not worth a 24k price.....

You have two choices basically, learn how to refine it properly with all its costs and dangers, or sell at a lower price. Your call....nothing has really changed....

__________________
"What others say about you reveals more about them, than it does you." Anon.
Reply
Power-User

Join Date: Mar 2007
Posts: 158
Good Answers: 2
#13
In reply to #12

Re: Gold flake/foil refining

09/09/2007 8:36 PM

One method to increase your profit is to cast it, yourself, into rings or doodads then sell it on ebay or what have you, just a thought.

joshua

Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 49
#16

Re: Gold flake/foil refining

09/10/2007 2:34 AM

Also, check these guys out: http://www.kitco.com At least you'll have a good idea of price.

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Reply
Power-User

Join Date: May 2007
Location: Los Angeles area, California, USA
Posts: 202
Good Answers: 9
#18

Re: Gold flake/foil refining

09/10/2007 1:18 PM

[[[[ I have several ounces of near 24K gold flake/foil that I recovered from Gold Hardness (Knoop micro-hardness) test panels. These test panels were plated with as much as .005" of high purity gold that was usually Ni hardened and plated on Ni or Cu panels. I have carefully dissolved these substrates with Nitric acid leaving only the Au undissolved in flake/foil form. I am trying to increase the purity of the Au to 24K. I have done this recovery in the past without attempting to increase purity and feel I am being cheated by my current processor. Therefore I want to make this into a 24K nugget that I can then sell on ebay. When I do the melt (in a ceramic crucible with an aceteline torch) what can I do to remove the residual Ni and possible Cu that are surely contaminating my gold and lowering the purity/value. Any help is appreciated. My facilities are very limited (single crucible used for melting and cooling after the torch melting process).]]]] TORCH MELTING IS NOT A GOOD WAY TO GO FOR ACCURACY/PURITY.

>>>>>>>>>>>>>>>>>>

Sir: I am curious...how have you determined your stated "near 24 carat" carat purity?

It is impossible to get to where you want to go without substantially more lab equipment than you indicate.

Nitric Acid will not soluabilize gold.

Aqua regia....noble acid....will

Consists of

one part hydrochloric acid... two parts nitric aicid...pharmecutical grade... will dissolve all metals in your gold coating. Do this in Pyrex beakers at 150 F. do not boil away liquid. Hold temp not to exceed 160F degrees. ALLOW FOR THERMAL AND "ACTION" EXPANSION.

chemical "boiling action" will occur until totally dissolved (bubbles/action).

After action stops...ioninc exchange out of COOLED solution by ferrous sulfite powder (NOT SULPHATE)...sprinkled very slowly. Violent action will occur.

After action stops, filter off liquid...gold "sands" will collect on filter paper.

This should be three nines gold when fired with a little borax flux.

Fire paper and all...for top results.

Chemical Assay after that to determine purity achieved.

WARNING.....

IMPROPER OR MISUSE OFANY OF THESE STEPS COULD BE FATAL.

YOU WILL HAVE CREATED HAZMAT SOLUTIONS AND RESIDUALS.

THE NEEDED CHEMICAL/ACIDS MAY NOT BE AVAILABLE IN CONVENIENT ECONOMIC SIZES FOR YOUR USE/WORK.

TRANSIT OF NAMED CHEMICALS ALL REQUIRE LISCENCED HAZMAT CONDITIONS.

NOTHING CAN GO DOWN THE DRAIN OR THROWN IN "TRASH" LEGALLY WITHOUT TREATMENT TO SATISFY YOUR LOCAL WASTE CODE REQUIREMENTS. Permit may be required

GET THE MSD SHEETS TO KNOW HOW TO HANDLE THESE ITEMS LEGALLY.

FUMES EMMITTED DURING SOLUBILIZATION ARE HAZZARDOUS.

ELBOW LENGHTH RUBBER GLOVES/FACE MASK PROTECTIVE EQUIPMENT AND EXTREME CAUTION MANDITORY.

IT IS NOT A RECOMENDED PROCEEDURE FOR ANYONE WITHOUT TRAINING IN LABRATORY CHEMISTRY APPLICATIONS..

(MERCURY IS WORSE)

All of the above are obtainable procedures from several precious metal books on gold, silver refinings..."Amans" is one of the industry standards for processes.

Many college level chemistry book on metallurgy carry the same or similar information.

There are process variations depending on complexity/constituents and impurities of the beginning metal product or ores.

UNDERSTAND WHAT YOU ARE DOING BEFORE YOU START.

Your jewelry or pawn shop buyer can only hit the carat quality by less accurate methods.....probably scratch test.......and must protect himself as well as make a profit to stay in business...........same with the refinery except that wet chemical assay is very accurite......ussually within two HUNDRETHS of a percent of purity or better.

CAUTION.........TO SELL A SMELTED SAMPLE AS A "NUGET" ON E BAY IS IS LESS THAN TRUTHFUL......IN THE INDUSTRY A NUGET IS IN IT'S NATURE FORMED STATE.....AND EXTREMELY RARELY 24 CARAT.

ALL THIS IS WHY REFINERS, WITH ALL THE PROPER EQUIPMENT/AIR SCRUBBERS/FUME HOODS/PFAUDLER KETTLES/SECONDARY CONTAINMENT PROVISIONS/TRAINING/SAFETY EQUIPMENT/PERMITS/KNOWLEDGE OF REGULATORY RULES/SPACE EXISTS AT SUBSTANTIAL CAPITAL INVESTMENT.

AND ARE IN BUSINESS TO MAKE A PROFIT.....

MR. GUY

__________________
If you are looking for a positive answer..it's YUP......
Reply Score 1 for Good Answer
Power-User

Join Date: Nov 2006
Location: Rockwell,North Carolina
Posts: 211
Good Answers: 1
#20

Re: Gold flake/foil refining

09/12/2007 7:19 AM

Gold assay costs $100.00 Get enough gold and it is worth sending in and you will know what you have. That way you can guarantee what you are selling. I am not sure that I would buy gold on e-bay. I had enough difficulities with people I know.

Check out http://www.hooverandstrong.com/ today gold 705.00

__________________
1.1 billion people do not have safe drinking water
Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 49
#21
In reply to #20

Re: Gold flake/foil refining

09/13/2007 1:31 AM

Most places that deal in ingots will accept ingots that are marked only by certain companies. So even the ingot buyers are suspicious of the metal they buy. I think they are adversed to risk. There are places where you can send your gold, they will work the numbers and pay you for gold content.

Again, take a look at www.kitco.com.

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Reply
Anonymous Poster
#22
In reply to #21

Re: Gold flake/foil refining

09/13/2007 3:38 AM

you can always sell it to the hip crowd to place on their teeth!

Reply
Guru

Join Date: Jul 2007
Location: 30°30'N, 97°45'W, Elv: 597 ft.
Posts: 2411
Good Answers: 10
#24
In reply to #21

Re: Gold flake/foil refining

09/14/2007 11:31 PM

Interestingly, the American Eagle is a 1 T.Oz silver coin in the States. It is legal tender of $1USD.

If you go to the market you can buy one dollar worth of shmeg, with a 31g 99.99%fine silver coin. Go figure.

cr3

__________________
I never apologize. I'm sorry that's just the way I am.
Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 49
#25
In reply to #24

Re: Gold flake/foil refining

09/14/2007 11:43 PM

That's the face value, just as the face value of the gold eagle has always been $20.00. If you purchase $1.00 worth of anything with your silver eagle, you've got a screw lose. You can get these only from bullion and coin dealers, where you pay over $12.00 for them. And that's where you take them when you want to cash out.

One thing that's quirky about dealing in bullion - dealers will only accept bullion that is marked by a reputable and well known bullion manufacture. If you come in with a bar of gold or silver that is of unknown origin, even if it is pure, they may just show you the door.

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Reply
Guru

Join Date: Jul 2007
Location: 30°30'N, 97°45'W, Elv: 597 ft.
Posts: 2411
Good Answers: 10
#26
In reply to #25

Re: Gold flake/foil refining

09/15/2007 12:04 AM

I have been collecting about 20 years now.

__________________
I never apologize. I'm sorry that's just the way I am.
Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 49
#27
In reply to #26

Re: Gold flake/foil refining

09/15/2007 12:26 AM

Well, then you know!

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Reply
Guru
Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3968
Good Answers: 119
#28
In reply to #21

Re: Gold flake/foil refining

09/15/2007 1:27 AM

There were anumber of fake bullion bars with tungsten cores presnted to banks a few years ago.

So they started drilling them. Then they perfected the ultrasonic method to verify them. http://www.theodoregray.com/PeriodicTable/Elements/074/

the two metals have different sound propagation speeds, so the interface shows up.

__________________
Per Ardua Ad Astra
Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 49
#30
In reply to #28

Re: Gold flake/foil refining

09/15/2007 1:36 AM

Yes, but your local coin/bullion dealer doesn't have the equipment, so...

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Reply
Power-User

Join Date: Nov 2006
Location: Rockwell,North Carolina
Posts: 211
Good Answers: 1
#23

Re: Gold flake/foil refining

09/13/2007 3:47 AM

I used to buy old gold teeth, was good gold, about 20K. As far as making gold fronts for the brothers. I bet they would holler when I put that torch in their mouth!

__________________
1.1 billion people do not have safe drinking water
Reply
Participant

Join Date: Nov 2009
Posts: 3
#31

Re: Gold flake/foil refining

11/25/2009 2:11 AM

Sir,

The elimination of Cu, Ni etc is not a problem, just boil with 20% nitric acid stop when coloured fumes cease. cool and wash with liquor ammonia, that may give you 24K gold. The nitric acid is diluted so that no gold leaches with it.

May I ask you the best solution to melt pure gold at home without any hazzards. Is there any electric torch like acetylene torch?

Johnson Lall

Reply Off Topic (Score 5)
Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
Posts: 1950
Good Answers: 109
#32
In reply to #31

Re: Gold flake/foil refining

11/25/2009 2:40 AM

Hi,

avoid acetylene, this may form explosive compounds with gold and silver and copper.

These usually burn immediately but who knows?

Try in charcoal isolated by a wooden trunk or a hole in earth or clay.

Blow with a reversed vacuum cleaner.

Use a graphite or iron or SS crucible, cover with charcoal dust and lid on and add some flux (jewellers, borax or similar).

To perfect: use a type K or better thermo-element to indicate temperature of the melt.

RHABE

Reply Off Topic (Score 5)
Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
Posts: 1950
Good Answers: 109
#36

Re: Gold flake/foil refining

11/25/2009 3:34 PM

The spud that is mentioned in post1 is in reality a piece of porous magnesium-oxide,

near 1 inch dia and same height with a shallow concave upper surface to accommodate some tiny pieces of metal that are heated by an oxidising torch from above.

Any non-gold (and may be platinum-group-metals?) is oxidised and attaching to the MgO, so a pure sphere of gold is remaining after the test.

Useful for test but not for refining.

RHABE

Reply
Guru

Join Date: Jul 2006
Location: "Dancing over the abyss."
Posts: 4942
Good Answers: 243
#37
In reply to #36

Re: Gold flake/foil refining

11/25/2009 4:55 PM

We put the fines from our panning into a potato with mercury wired it together and cooked it using the gas grill. end result, a mass of gold and a pool of mercury with all the contaminants at th bottom of the potato. thanks for your clarification. we may get to try your method one of these days. milo

__________________
People say between two opposed opinions the truth lies in the middle. Not at all! Between them lies the problem, what is unseeable,eternally active life, contemplated in repose. Goethe
Reply
Participant

Join Date: Nov 2010
Posts: 1
#38

Re: Gold flake/foil refining

11/05/2010 6:33 PM

The idea is to get your gold in as small parts as possible. If you have a mill you go as thin as and cut it with scissors. Without a mill it gets to take longer but it still works. Pour the gold when good liquid into a deep body of water, a bucket with steel bottom. Get the parts as small as possible in a glass jar, best coffee can/jar that can take heat.

Then go to your local green fingers shop garden supply and get fertilizer Sodium of Nitra. And get some Urea, also a fertilizer of a different type. Then get a gallon of Muriatic Acid at the hard ware store. Get some old electric wire that is easy to strip, for the copper we need later. To make test water you may get at the hardware store some plumbers lead free solder. That is pure tin. Work with your face upwind. have a pan with water and baking soda in the sink for if you touch acid, it neutralizes it at once, leaving it harmless.

Pour the glass jar with the gold half full with muriatic acid, and add a few table spoons of nitric sodium, (on e-bay, called SN) Let it stand over night or longer if bubbles still coming up. The little bubbles are gold dissolving. The other metals become grey dust that we filter out. If you have a coffeepot you can put the thing on the hotplate and that will make the reaction faster. Do not let the steam out of the pot, a good lid that drips the condense back in the pot is best.

Once no more bubbles arise, tap the jar and see. Then all the contents of the jar go in a coffee filter, triangular, 8 cups coffee filters are very good.

Now put in the still dirty coffee jar a half cup of water from the airco or rain is best, but water will do. Put it on the hotplate and dissolve a few tablespoons urea in it. When the urea is dissolved, pour this onto the sides of the filter that holds the Sodium Nitra from the first action. The jar holding the gold solution must stand in a big glass pan. I use a glass door from a discarded front loader washing machine. Because when the urea solution gets through the filter it starts to foam. More or less. And the liquid gets warm. Now put copper, plate or wire, and see that the copper gets black and a dark red mud starts to form. That is your gold. When the reaction is over, when the copper is not black anymore when it comes out all the gold is now in the bottom as red mud. To see if the gold is precipitated all the way you make test water.

Put a few cc muriatic acid and an inch or so of plumbers tin solder in a small container, best is an empty eye drops bottle. Leave it open while the tin dissolves. Now put one drop of the tin acid on a white paper towel and add a drop of the gold solution acid.If it turns black there is still gold, add more urea and copper.other colors than black indicate whatever, but oonly gold makes it black it detects 4 parts in a million!.

the liquid with the red mud goes through three coffee filters or 4 if you want. The gold mud can be very fine but most gets stuck in the first layer filters. Discard the liquid in a container for later. The filters must now be washed with plenty rinsing with water. untill it is acid free. To make sure you add some amoniac (janitor strength) in the rinse water. If blue color appears, keep rinsing.

Onmce it is rinsed and clean, wring twist the filters in a small possible ball in the crucible and torch it. I have an oven to 800 Celsius and that burns away the filters and leaves the gold to melt.

If you put the flame straight on the filters paper will fly away, do not attempt. You can dip it first in alcohol, but I find still a risk of flying particles.

However, you can make a small oven for only the one crucible you have/ Find a thick walled piece of steel pipe (tail pipe, car exhaust shops) slightly bigger than the crucible, put the pipe over the crucible on a smooth red brick and close it with a steel plate on top, enough small slit for smoke to get out. Torch the iron pipe until cherry red hot for ten minutes and then see if all the filter is gone without flying in the air.

Once most or all of the filter is gone torch the stuff in the crucible, if the surface is black you may have left some piece of copper in the red mud. after rinsing let the red mud dry and check for any copper still there.

Instead of copper it is better to use Meta bi sulfate, also on e-bay (MS) the you have no risk of copper residue in the red mud. .

have fun!

Reply
Guru

Join Date: Nov 2006
Location: KnoxTN
Posts: 1485
Good Answers: 6
#39
In reply to #38

Re: Gold flake/foil refining

11/06/2010 9:41 PM

You have suggested a rather involved procedure which appears to be difficult to follow, requires materials inadequately specified by the accepted names, etc. etc.

It seems to me that it will take more time and effort than it is worth, (if it works), and will cost more in time and effort than it is worth.

If it were my scrap I would ship it off to a RELIABLE refiner who will do the whole job and pay you an honest return for the gold content. The larger the amount of scrap with a high gold content the better the return percentage wise.

__________________
Do Nothing Simply When a Way Can be Found to Make it Complex and Wonderful
Reply
Anonymous Poster
#40
In reply to #39

Re: Gold flake/foil refining

11/06/2010 10:53 PM

It takes a day or two, but I take the gold out of any gold containing scrap/ Check ebay NS and Urea salesman goldman! he selld the stuff and with rcovery of 1 gram you have earned back your investment. 975/1000 pure or better. All material is over the counter hardware and garden shop.

I do it all the time.

Reply
Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
Posts: 1950
Good Answers: 109
#41
In reply to #38

Re: Gold flake/foil refining

11/07/2010 5:02 AM

Some questions:

first step is to get a solution of HCl and HNO3 with some free chlorine by dissolving NaNO3 in HCl. This dissolves gold. But why are the other metals precipitated as grey dust?

(Private handling of acids is no longer allowed in Europe - ridiculous.)

What is the urea doing with the dissolved metal(s) or acids?

Next step: copper is pushing the gold out of solution and precipitating as fine particles. Why use copper, commercially this is done with iron or zinc?

Both are available as fine powder, so the reaction can be controlled with accuracy.

Melting the filter with gold powder: best done in a cavity of graphite or charcoal.

RHABE

Reply
Anonymous Poster
#42
In reply to #41

Re: Gold flake/foil refining

11/07/2010 8:10 AM

I use battery acid and sodium nitrate warmed up on an electric plate to 70-80 celsius to make nitric acid, that dissolves every thing but not gold.

The kings water that dissolves gold is muriatic acid with sodium nitrate.

Urea brings down the acidity so the precipitated gold does not dissolve itself,

copper is available in abundance of old wire and that is why I use it,

when I have metabisulfite I use that but there is no shop to buy it here on my isolated Caribbean island

Reply
Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
Posts: 1950
Good Answers: 109
#43
In reply to #42

Re: Gold flake/foil refining

11/07/2010 9:45 AM

Thank you,

do you know how the Incas did dissolve the gold with the natural salts from the Atacama-desert? There was (many years ago) an article in SciAm about this topic but I don't find it anymore.

This must be possible without any strong acid!

RHABE

Reply
Anonymous Poster
#44
In reply to #43

Re: Gold flake/foil refining

11/07/2010 10:58 AM

I have no idea how they did it then. Hydrochloric acid is also in your stomach! ha ha!

Reply
Guru

Join Date: Oct 2014
Location: Hemet, Land of milk and honey.
Posts: 2363
Good Answers: 36
#45

Re: Gold flake/foil refining

02/09/2018 12:19 AM

You said that you wanted to make Gold nuggets that you could sell on eBay.

I checked eBay for Gold Nugget, there were 3947 people selling real gold nuggets.

Then I checked for Artificial gold Nugget,

There were 2 people selling artificial leprechaun doll house gold nuggets.

Then i checked for Man made gold nugget,

All of those were rings or bracelets.

Which category were you going to sell your, " Gold Nuggets" in ?

Reply
Guru

Join Date: Aug 2012
Location: Land of Fruits and Nuts
Posts: 4125
Good Answers: 52
#46

Re: Gold flake/foil refining

02/09/2018 5:52 AM

I had a similar problem as yours but on a larger scale. In one of my former careers, I owned a jewelry store. I would take my scrap gold, melt it into an ingot and sell it to the refiner. He would assay it and give me a check based on the purity and spot price of gold x 98% to 99%, depending on the amount of gold I had.

I started thinking I was being cheated, so I took some 14Kt plumb gold (guaranteed by a legitimate company) and melted it into a bar, then took it to the refiner. It came out to less than 14Kt. From that point on, I decided to take my scrap gold to the assayer and then sell it to the refiner.

Here's how I did it. I would melt the gold scrap into a bar. I'd use an oxygen/propane torch - acetlyene is too dirty. I'd use a cast iron ingot maker, coat it with boric acid, then melt the gold in the ingot maker. When the gold was flowing and looked fully melted, i'd take the torch away and let it cool. Once it was back to a solid, I'd dump the ingot maker into a bucket of cold water. It would sizzle and bubble, but most importantly, it would break free from the cast iron mold. I'd scrub it with a stiff nylon brush and some soap, rinse it and then bring it to my assayer.

My assayer would check my gold bar for consistency and if he didn't think I'd done a good job melting the bar, he'd re-melt it and form a new ingot. He would then drill out a sample, weigh the shavings, then he'd put in a beaker. He would put some acid in the beaker and I'd leave. After an hour or so, I'd return and he would rinse the shavings with water, dry them and weigh the remains. The final wt/starting weight x 24 = Kt. He'd give me a slip of paper stating he had assayed the bar, he'd stamp the bar with a reference number, which was the same number that was pre-printed on the assay paper. He would put my shavings in a small ziplock baggie, write the assay number and weight on the baggie and tape it to the gold bar.

I would pay him $15 for the assay, then take it to the refiner and he'd pay me out. Most times I would get 14Kt. plumb gold casting shot and the remainder in cash. I would always have to ask the assayer to include the value of the pure gold shavings as part of my payout. Hey, a gram or so of pure gold was $10 or so back then.

Note that this was from 1994-1999 and I'd have anywhere from 2 lb to 15 lb bars of 12.5-13.7 Kt bars. Back then, gold was less than $300/oz, so it didn't make sense to bring anything less than a 2 lb ingot.

One other thing, be careful trying to purify the gold yourself. The fumes from burning off the impurities can cause damage to your body. Even melting the gold into ingots can be dangerous. Some other post mentioned using mercury, which will work, but the risk of personal injury is too great.

Instead of trying to purify the gold, just let the assayer do his job. All the times I sold my scrap, the assayer never cheated me. As for the refiner, he'd take advantage of me every chance he could.

One final note, we would buy scrap gold off the street for about 1/2 of the gold value. The reason is that we paid the expenses to operate a store, there was always risk that the jewelry could be stolen, the gold could have impurities and our scratch test wasn't that accurate, so we'd have to err on the side of caution. I had a dental lab owner who would sell me his scrap gold. Sometimes it was miscast teeth, while other times it was small squares of high purity gold (it was a very hard alloy). The purity was stamped on the small squares. I would pay him 80% for the small squares and 70% for the miscast teeth. I remember being suspicious at first, but I checked to verify he was the owner of the lab.

__________________
Enjoy and be happy! Life is too short!
Reply
Guru

Join Date: Jun 2009
Location: Ontario Canada
Posts: 930
Good Answers: 32
#47

Re: Gold flake/foil refining

02/09/2018 10:35 AM

I understand you can use boron instead of mercury to do the refining. I saw it on a TV show years ago the idea was to protect the illegal miners from mercury poisoning. Boron is cheap and 20 mule team is a box of food grade boron. Read the label.. hope this helps.

__________________
The fine line between cuddling and holding one down to prevent escape must be learned
Reply
Guru
Popular Science - Weaponology - New Member Hobbies - Fishing - New Member

Join Date: May 2007
Location: Aloha or
Posts: 579
Good Answers: 17
#48

Re: Gold flake/foil refining

02/09/2018 4:27 PM

I don't think you should be starting with Nitric acid. start with sulfuric and dissolve the nickel and copper first. Once it is gone the rest is easier.

__________________
Closed biased minds are utterly impervious to any factual evidence which contradicts their beliefs
Reply
Reply to Forum Thread 48 comments
Interested in this discussion?
You can "subscribe" to this discussion to be notified of new comments.
Click on the Subscribe menu at the top of the page.

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

Andy Germany (3); Anonymous Poster (6); aurizon (4); Autobroker (1); CaptainZen (1); exbanker (3); madscientist (1); Milo (3); Mr. Guy (1); Mr. Truman Brain (1); mutantone (2); RHABE (4); roy hammy (1); rustyh2o (2); silvCrow (1); Stirling Stan (3); TexasCharley (2); tonyhemet (1); vermin (8)

Previous in Forum: Electric/Electronic means to eradicate moles   Next in Forum: Face to Face Interviews

Advertisement