# Recovering and refining from gold ore specimen



## gmadrone (Jan 9, 2012)

I have about 20 gold ore specimen that are from Australia. Some are gold in quartz, but most are gold in dark brown rock. The gold is clearly visible in all specimen. I have done estimates on the
gold content using specific gravity tests (using weight in air and weight of water displaced) and then crushed and panned (several iterations) and weighed the recovered gold. What
I have is small nuggets and some sand mixed in, since I don't seem to be able to fully extract all the gold through the crushing/panning process. Has anyone had experience in such an
extraction/refinement process? I don't want to crush all the specimen and then be unable to get the recovered gold into a saleable form. Some of the specimen are attractive and might
sell as they are, but most of the specimen are not particularly attractive, so I think extracting the gold and refining it is probably best. I would appreciate any experience or expertise
from forum members. Thank you.

I will attach a few examples so you can see what the specimen look like.

Garry


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## butcher (Jan 9, 2012)

Here is how I would approach this, grind as fine as possible, pan as much gold from the quartz sands as possible, dry the remaining sand (quartz, iron, gold) and put in casserole dish on hot plate incinerate to red hot, (on hot plate using propane torch from above), cool and cover with HCL boil, lower heat some add some water to dilute a little and let settle, decant acid to jar leaving sand and gold in pan(we will call this jar base metals chloride possible iron), now add some more HCl to cover sand mix, add a few drops of nitric acid while heating (not boiling), solution may turn yellow with gold going into solution, after heating for a while I may add few more drops of nitric, as this progresses more gold will go into solution and the solution concentrates (heat and gold is using up most all nitric acid at first), once this solution concentrates (I have two choices add more acid or decant this one), I would let settle and decant this solution to clean jar, and add new HCL to cover powders again to do another leach (using same process) the colors of solution and stannous chloride test tell me how the process is proceeding (? am I still leaching gold).
The last leach I would rinse sands with a little water, adding this rinse to my gold solution.

I may then add house-hold ammonia with just warming decant this solution to new jar put HCL in this liquid (get pH neutral with this ammonium chloride solution), this would precipitate any silver, (save ammonium chloride solution to make into crystals by evaporation (this is used to precipitate PGM).

Rinse the quarts in dilute HCL (just in case).

Now the first jar of HCL (only wash) test with stannous chloride, (this solution can be reused if you do other recovery with like electronic materials) or just treated for wasted if proven barren.

The jar of gold chloride yellow solution, we need to be sure we have no free nitric acid, adding a piece of the free gold you panned with heat will denox solution, after denox return to clean jar add 3 times water and let sit a day, you may see white silver powder settle, we will decant clear yellow liquid to new very clean jar and use sodium metabisulfite to precipitate our gold as fine brown powder, stannous tests of solution tells us when we have all of the gold out of our solution, this precipitated gold powder is washed to Harold’s instructions, see the post getting pure gold (shining) for Harold’s post on this procedure.

Now you can take the panned gold and in-quarter it with some silver (depends on karat of your panned gold, if unsure will not hurt), (melt with three parts silver to one part gold get molten well and give a stir with carbon graphite rod, pour shot (slowly pour molten gold into stainless steel dish of cold water to make small gold pieces), and then part the gold and silver in nitric acid, dissolve silver in heated nitric acid, letting powder gold settle decant silver nitrate, cement silver from AgNO3 solution using a copper buss bar, brush off bar into solution (can test solution to see if complete, a few drops nitrate solution in black plastic spoon add drops HCL if white cloud silver still in solution). this cemented silver can be washed and dried and melted.

Dissolve this gold powder in aqua regia (instructions similar to above will work here also).


This was not written to be the whole of what you need, but it is one way I would treat this, do more study on each of the above written procedures, if this is new for you, as in writing this, I may have left something out, and also you will find more details by studying. You may also find another way to process your ore.


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## gmadrone (Jan 10, 2012)

Thanks for the detailed response butcher. I had considered trying to do the refining myself, but did not have a clear picture of exactly what would be needed to
do that and I do now. I will have to weigh the pros and cons of getting set up to do it myself versus just doing the initial crush/panning and taking it to a refiner,
or perhaps finding someone locally who is already set up who would be willing to help me do the refining. I appreciate your help.

Garry


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## butcher (Jan 10, 2012)

gmadrone, are you in austrailia, and did you find this gold? doe's the madrone in your name refer to the tree? 

Here are the notes made by Phil Dreamer I was refering to:


http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=6902

Phil, lets say I had a gold nugget from panning and I wanted to refine it. Since it is about 16 to 18.5k gold I would most likely inquart it, (melt it with silver to lower karat), (at 18% I might be able to just use nitric without inquarting, but to insure I got all the base metals, I would “quarter” the gold with silver).
(NOTE: To inquart gold: 75% silver 25% gold. Melt together in a melting dish, and drop into metal bowl with cold water to form “flakes”. See Steve’s video. Then follow the procedures stated below.)

1) Process inquarted gold thru Nitric solution. (50% water / 50% acid. Heat if necessary) 
Now nitric can get down under the gold and attack the base metals. Depending on how much silver I added, gold would be either brown powder or a much-pitted nugget of gold.

2) After reaction stops, allow settling; decant nitric from gold.
To the nitric acid, after decanted from gold, add Hydrochloric acid to “get back”, (drop) the silver out of it as silver chloride. (Set aside for time being).

3) Dissolve gold in AR solution. (80% HCI / 20% Nitric. Apply heat) 
(Hoke states, 4 fl oz HCI (muratic acid) + 1fl oz HNO3 (nitric acid) will dissolve 1 troy oz of gold. This is equivalent to 31ml of HCI + 8ml of HNO3 per gm of gold.)
The gold would then be dissolved in Aqua Regia, best to only use the amount of nitric needed to get gold completely dissolved with heat. No need to use urea, I do not use urea; instead I boil the Aqua Regia down to almost syrup (not to crystals).

4) Boil off nitric acid before dropping gold with SMB.
Carefully watch first boil! What happens is, the nitric in solution gets concentrated and will try and foam over at the most concentrated point, if you watch it, after boiling for a while you will see foam bubbles forming around top of liquid; at this point lower heat, wait until this point of concentration is passed, then you can raise heat. 

Once you have syrup, add some HCl to wet solution and boil it again to syrup. Do this for a total of three times, in order to eliminate nitric acid from the aqua regia solution (no need to use urea).
Now we can add 3 times the water. This will dilute the acid to where the silver chloride that it held, (this is some Ag that was still in the gold), will come down as white cottage cheese; let solution sit overnight and decant solution from silver chloride powder. Now we can precipitate the gold from this yellow solution.
Butcher

5) Precipitate gold with SMB
NOTE: Filter the solution BEFORE precipitating gold with SMB!
leavemealone, post re: what is my wrong? Typically you want to use an equal amount of SMB, as the amount of gold you estimate in your solution IE: if you figure there’s roughly 3 grams of gold, use 3 grams of SMB, then test your solution after decanting. (If using copperas you need to double that figure.)
Johnny

The SMB can be used dry or wet it works either way. 
The key is to use enough SMB to reduce all the gold to a metallic state. This usually requires 1 gram of SMB per gram of gold to be reduced as a general rule of thumb. If you don't get all the chlorine (HCl-Cl reaction) or nitrate (AR reaction) out of the solution the amount of SMB needed could increase, typically not more than double the amount of gold expected. 

If you want to use water with your SMB, the solubility of SMB in water at 20C is 47 g per 100 mL, so a pint of 20 C water (473 mL) can hold enough SMB when saturated to reduce ( 47 x 4.73) 222.3 grams of gold at optimal conditions. 
Steve
As for adding SMB, I always add my SMB dry with lots of swirling of the beaker or stirring with a glass rod. A stannous test afterward proves the gold is all precipitated. 

Just two days ago the temperature outside was below 40F (~4C) at dusk. I precipitated a batch of gold from solution, outside in the cold, with solid SMB in less than 2 minutes. I added the SMB and swirled the flask, within one minute the solution turned dark brown. Within 1 hour all the gold had settled nicely. The solution was filtered outside and was completely cooled. Expect a slight delay of less than 2 minutes before the solution changes to clear then brown. 

I find that the removal of oxidizers from the gold solution to be the most important factor when using SMB. All the free chlorine or NOx should be removed before adding dry SMB. If you add a small amount of SMB and brown powder forms then re-dissolves, you have free oxidizers in the solution. 

Add small amounts of dry SMB with stirring, let it all dissolve, then add more if necessary. Test with stannous once the brown cloud or sponge of gold settles. 
Steve
Re: Best way to use SMB I use mine dry. Gold precipitates as a brown powder if the solution is clean, and a more black colored if the solution is dirty. I never check pH when using SMB.
Steve
Thank you Steve for your reply. I have seen the SMB precipitate out of solution as a white powder by a metallurgist in Las Vegas on my chlorine solution. In your opinion can it precipitate as a gold chloride?
Joyce if the solution contains copper II chloride and you add SMB, you will get an off white to grey collared precipitate of copper I chloride along with your gold. 
This contamination dissolves easily with warm HCl.
Steve

WASHING THE GOLD POWDER AFTER USING SMB – post by lazersteve
1) After precipitating the gold with SMB, test for gold in solution with stannous chloride, if present (purple swab) add more SMB until test is negative.

Here's how stannous looks to Gold, Platinum, and Palladium



Note the color of the results will be lighter if the concentration is low. The colors will also vary if you have several of the metals in the same solution.
1.	Let the gold powder settle to the bottom of the beaker over night.
2.	Siphon or gently pour off the used SMB solution into an old milk jug labelled Used SMB. Save in your stockpot or properly dispose of.
3.	The gold powder stays in the same beaker you precipitated it in.
4.	Add just enough water to cover the gold powder and boil for 5 minutes.
5.	Let settle and pour or siphon off the water into the stockpot.
6.	Repeat three times.
7.	Add just enough muriatic acid to cover the gold powder.
8.	Boil for 5 minutes and pour or siphon off into the stockpot after testing with stannous. If gold is present keep in separate beaker to precipitate later.
9.	Repeat until the acid is no longer discolored by the process.
10.	Repeat the water rinse as above.

11.	If you suspect silver is present as a contamination, repeat the process with hot 3% household ammonium hydroxide (unscented- clear). Put these rinses in a separate container and add muriatic acid until no more white silver chloride precipitates. You have added enough HCl when there are no more white fumes coming out of the liquid. Any karat, dental, cpu lid, or gold filled scrap will have silver as a contaminate.
12.	Finish up the rinses with three more hot water rinses. Put these rinses in with the ammonium hydroxide rinses.
13.	Gently heat the beaker containing the gold powder while swirling the beaker. As the gold dries it will begin to clump and move around the beaker freely. Don't allow the gold to stick to the beaker. 
14.	When the gold is 100% dry it should be a nice light tan color, if not re-dissolve it and precipitate again with SMB. Repeating the above cleaning process after precipitation. Good clean gold settles very quickly when precipitated and clumps into nice balls when dried. No gold should be stuck to the beaker when you are done.
15.	When completed transfer the gold to a properly prepared melting dish and melt into a button. 
16.	Steve
Re: AR process for placer gold
When we dissolve a metal in an acid the metal gives up electrons on the atomic level, the metal is still in this solution, when we give back these electrons the metal it will precipitate back out of solution as a metal.
Lets look at gold with its place on the reactivity series (if you don’t have an idea about reactivity series, do a search for it on web; get a chart for your refining notes), gold is at the bottom of the series, a very un-reactive metal, it will not dissolve in nitric acid, it will not dissolve in hydrochloric acid, but in a combination of the two of these acids it will dissolve, the nitric oxidizes the gold and then it will become a metal salt with the chloride from the hydrochloric acid, giving up its electrons, this is now yellow dissolved salt of gold chloride, the nitric in solution will keep it dissolved, until it is eliminated (or used up). Now, to get our gold back, how can we do this? Well, one way. We could just replace the gold from solution. Take a look at the reactivity series, and the position of copper in the series compared to gold. Copper is above gold, meaning, it is more reactive, so by adding copper to this acidic salt of gold in solution, the copper will start dissolving, giving up its electrons to the acid and if we had excess acid it would not start precipitating the gold until all of the un-reacted acid was used up, then the copper would continue giving up its electrons, but now to the dissolved gold in solution. Since the gold got back its electrons, it will form back into a metal (brown powder) and precipitate out of solution. Once all of the gold has precipitated and the solution is loaded the copper bar will not dissolve any further (nothing left to take its electrons). Now with dissolved copper salts in solution, all these copper atoms are missing their electrons; a metal higher in series can replace the copper from solution, and so on.


Another method to get the gold from aqua regia would be to eliminate the nitric acid ( 3 boil, Hcl additions method ) and the use a chemical to precipitate the gold, here is an equation using sodium bisulphite (notice the ITE in the name NOT ATE), this is a chemical reaction with the gold chloride, not a replacement reaction like the example above.
2HAuCl4 + 2NaHSO3 --> 2Au + 4HCl + NaSO4 + SO2.
The sulphur dioxide gas, after the arrow, gave back the gold its missing electrons, precipitating the gold.
In the examples above the acids dissolve the gold metal, gold loosing its electrons, becoming a yellow liquid. Copper was a replacement reaction, giving gold back the electrons, making gold precipitate, but loosing its own.
The second one was a chemical reaction, used to precipitate the gold.
By: R. Butcher

NOTE: Check SMB solution for other metals that could be present before storing or properly disposing of it!

I, philddreamer, took the liberty to compile some of the great information from a number of different posts from the GRF.com, so to have a guide when processing my first batch of inquarted gold. The result, a beautiful 13.4gm golden slug! Thank you, thank you, thank you, all you brothers & sisters @ GRF.com. I could not have done it without you.

Phil (philddreamer) Figueroa – Lynnwood, WA.


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