Gold Recovery for Dummies?

A. Hi, Cory. Topics 771b and 18889 may be a good start. Good luck.

A. You can leach it off with a 5% solution of sodium or potassium cyanide (REALLY TOXIC STUFF!), a dash of hydrogen peroxide makes it work faster. Then you can electroplate out the gold.the solution is reusable just add a little more cyanide if it quits working. Another method is digest the metal in 50% nitric acid this will leave pieces of gold leaf behind which you can filter out. Gets kinda expensive unless you have a cheap source of HNO3. As far as the gold on pottery goes you would have to process a heck of a lot since it's only a few millionths of an inch thick. You can kill the cyanide with calcium hypochlorite for disposal. I once got about 3 oz of gold off mil spec connector pins but I had to process about 27 pounds of them. Good luck and be very careful with the cyanide.

A. Well Cory I am an Engineer for a large gold mine. You have a good idea here... The Chemistry problems are real, as you know. And I'm sure you know that I WOULD NOT LEACH AT MY HOUSE or try to make any CN product without being in a proper lab or a place designed for it. Always keep CN solutions at a pH of 10.5, realize that if your pH hits 9.3 your gassing of half of the CN in your solution...BAD NEWS. At 10.5 your only losing <1%. If the pH gets over 11 the solution has a hard time picking up gold.

With that said you can get gold out of anything and they are right NaCN works great for a lot of "host" materials, but do NOT use it where acids or S's are present. Also realize that in our leach pads we use a basic rule: 150 micrograms takes 45 days in a leach pad with cyanide consecration of .2 lbs/ton and an application rate of .003 GPM/ft^2 (you will be much high on both of these numbers). The big problem is cyanide the problem is you will have to make it; no one will sell it to you. You're a chemist and probably can think of ways to make it. (to help make sure no one gets hurt I'm going to let you do some of the Engineering work) But one way is NaCl, C (flower will work) and N2(g) from a welding store, e's are involved, you get the picture.

When extracting make sure your CN Solution has flow, the amount of gold is directly linked to CN concentration, the overall solution can (when ratios are right) hold 500 oz gold / ton of solution.
Remember pH pH pH

You can skip any carbon loading for concentration and go straight to electrolysis. Start with 6V don't use a Cu cathode, use gold, this will keep you from having to refine with acids and some other headaches.
Remember pH and do NOT pour the CN solution down the sink. If you're going to pour make sure the CN is totally killed with something like CaO, Baking soda
Anyway stay safe, good luck, Gold may hit $1500 + in 2010. A lot of the big companies are planning on it.
Anyway there are a lot of in's and out with gold extraction, have fun.
BMC

A. Hi, James. At a small risk of oversimplification, yes; if a low voltage electrical contact is the color of gold, it is gold plated.

Regards,

A. GOLD REFINING STEP BY STEP INSTRUCTIONS

For every ounce of scrap gold you are going to refine you will need a capacity of 300 milliliter container for the aqua regia solution.

1. Place impure gold to be dissolved into a glass or plastic container.

2a. Aqua regia - Mix one part nitric acid to 3 parts hydrochloric acid. OR
2b. To the container, add 30 milliliter of nitric acid for every ounce of metal.

To the container, add 120 ml of hydrochloric or muriatic acid for every ounce of metal in the container.

3. Allow impure gold to dissolve for an hour to overnight for complete dissolution.

4. Once all gold is dissolved, filter out any particles out of the acid solution containing the liquified gold into another glass container using a fine stainless strainer. The remaining particles should not be discarded as these may contain other precious metals!

5. The acid containing the dissolved gold will be an amber to emerald green color depending on the purity of the gold and should be clear (not murky or cloudy). If the acid solution containing the dissolved gold is murky, it may contain particles and should be re-filtered with a finer grade paper filter.

6. Slowly, add the water/urea (urine ) to the acid solution containing the dissolved gold. The acid solution containing the dissolved gold will foam with the addition of the water/urea (urine). Do not add the water/urea (urine) so quickly that the acid foams out of its container. When the acid solution containing the dissolved gold stops reacting to the addition of water/urea (urine), stop adding the water/urea (urine). You've just raised the pH of the acid from 0.1 To 1.0, killing the nitric acid but not the hydrochloric.

7. Add precipitant ( sodium bisulfite ) slowly in minute amounts to the acid solution containing the dissolved gold, immediately the acid solution containing the dissolved gold will change to a muddy brown appearance as brown particles of gold form in the solution. Occasionally agitate the solution with a glass stir rod, as the brown particles continue to form they will sink to the bottom of the container, this brown "mud" is, despite its appearance, pure gold.

8. Allow precipitant ( sodium bisulfite ) to fully draw out all the gold out of the solution, test for gold in the remaining solution, if it tests positive for gold, you may have to add more precipitant ( sodium bisulfite ).

9. To test the solution for remaining gold, first immerse the end of the stirring rod in the acid. Remove it and touch that end to a paper towel to make a wet spot. Put a drop of gold detection liquid on the wet spot on the paper towel. If any gold is still dissolved in the acid, the wet spot will turn a purple-black or a purple-brown. If you see this color change then give the precipitant more time to work and/or add more precipitant.

10. Now all the gold should be drawn out of the solution and the acid should now be a clear amber color with a brown mud settled at the bottom.

11. Using a fine paper filter, pour off the acid into another container allowing the mud to stay in the filter. The mud is pure gold.

12. When all the acid is poured off, return the mud to a container for rinsing, add tap water to the mud. Stir and let the mud settle. Using a fine paper filter, pour off the tap water into the container with the acid. Do not pour off any particles of brown. Repeat this rinsing 3-4 times or more.

13. After completing the final tap water rinse, rinse once again with aqua ammonia [affil link on Ebay & Amazon] ( %10 ammonia [affil link on Ebay & Amazon] to %90 distilled water ) white vapors will appear. The aqua ammonia [affil link on Ebay & Amazon] cleans impurities from the gold mud while, at the same time, it neutralizes any acid still clinging to the gold mud.

14. While in the fine paper filter, give the mud on last rinse, this time with distilled water until mud and filter is clean.

15. Take filter with clean gold mud and gently squeeze of any excess water and place filer with mud into crucible for melting.

16. Once melted, the gold will again take on the appearance of metal. If you've followed the instructions carefully and used filters, the gold will be 999.5 % Pure with virtually no losses.

17. Platinum- If you had platinum in your gold, it will not dissolve, to any appreciable degree, in the room temperature aqua regia. It will be left behind when you pour off the aqua regia, prior to precipitation. To insure high purity of the platinum, you will need to re-refine this material. Put this material in a fresh aqua regia bath. This time, however, heat the acid to simmering. Continue heating until all the platinum is dissolved (that may take 1-2 hours). When completely dissolved at 1 ounce of ammonium chloride for every ounce of dissolved platinum. The platinum will precipitate as a red mud. If you want to leave the iridium in the platinum, then wait for it to precipitate before recovering the platinum. Iridium will precipitate as a blue-black mud after the platinum precipitates. Platinum group metals will also show up on the stannous chloride test. Platinum turns red, palladium Palladium turns orange and iridium turn blue-black.

A. Philosophers stone? Alchemy? When using nitric acid to remove base metals in gold recovery it is very easy to misplace your gold. On electronics that use gold for shielding (such as RF shielding) the gold can be very thin and instead of coming off in foils will separate into finely divided particles and will get lost in trash. Another cause for missing gold recovered this way is bad work habits. Dirty glass that has been cross contaminated will hold chemicals that can't be seen. Did you use the glassware for any solution that contained a HCl acid solution? If so, remember that you can't rinse acids from materials. If you use a container for a HCl solution and then rinse well, and then use it for a nitric acid solution a weak aqua regia will form and dissolve values. A small amount of HCl will make quite a bit of AR solution. As far as the philosophers stone, the only one I can think of is the one in the Harry Potter stories. Values that have been precipitated have distinct colors and as far as white powder goes, metal salts can be white if crushed finely enough. If you would like some help, put the witchcraft aside and let me know what you did to get what you have and I will try to give some advise on what it is and what can be done with it.