How to store gold powder

[Metaphore]

I'm pretty sure someone must have asked this question in the past, but can't seem to find it.

I recovered a couple of grams of gold powder, washed it with boiling water a few times but would like to wait until I recover more to do the acid wash and melt. What is the best way to store gold powder? In the rinse water?

 

[Geo]

Gold does not oxidize easily. Gold powder can be stored dry or wet. The most important part of storing clean gold powder is to keep it in a clean container (preferably with a screw on or snap on cap) where the powder can not be contaminated.

 

[nickvc]

First rule somewhere safe..
As Geo advised but I'd always use a marker pen to label it just in case.

 

[jason_recliner]

Yes, label it. You think you'll never forget what's in your jar. But someone else might think it's dirt and toss it. Or you might actually forget.
It's important to seal it and tuck it away. Whenever gold is exposed to open air for too long, something worse then oxidisation happens. It gets stolen.

 

[Anonymous]

I keep my black gold powder in a beaker with the fresh distilled water until I'm ready to do a nitric bath and final rinsing. You can easily keep it that way with a piece of saran wrap pulled down on it to keep it air tight. Works the same for nitric acid and HCL.

Kevin

 

[Palladium]

Please quit recommending nitric washs for gold powder. Nowhere is that common practice or recommended.

 

[Geo]

Please quit recommending nitric washs for gold powder. Nowhere is that common practice or recommended.

Unless you WANT to dissolve some gold. The first year I refined behind my shed, I realized that the white film that coated every surface was tin oxide. I could not for the life of me figure out how tin oxide got on all the exposed glass. That is until I studied stannic chloride (tin(IV) chloride,SnCl4). Stannic chloride is created when you dissolve tin metal in HCl. It fumes in ambient temperatures and is a mild to moderate irritant and was used as a weapon in WWI until tin supplies ran low. It deposits on cool surfaces where the chlorine is oxidized creating tin oxide crystals. I'm just saying that until these fumes oxidize, nitric acid can react with it to form an AR solution.

 

[resabed01]

If you choose to store the powder in a glass vessel in water be aware that if the water freezes, it will break the container

 

[Palladium]

Please quit recommending nitric washs for gold powder. Nowhere is that common practice or recommended.

Unless you WANT to dissolve some gold. The first year I refined behind my shed, I realized that the white film that coated every surface was tin oxide. I could not for the life of me figure out how tin oxide got on all the exposed glass. That is until I studied stannic chloride (tin(IV) chloride,SnCl4). Stannic chloride is created when you dissolve tin metal in HCl. It fumes in ambient temperatures and is a mild to moderate irritant and was used as a weapon in WWI until tin supplies ran low. It deposits on cool surfaces where the chlorine is oxidized creating tin oxide crystals. I'm just saying that until these fumes oxidize, nitric acid can react with it to form an AR solution.

Science ...... The study of observation !
I've spent so many hours just learning by watching that i could have gotten a college degree by now.

 

[Anonymous]

Please quit recommending nitric washs for gold powder. Nowhere is that common practice or recommended.

I never recommended using nitric in my reply at all. Also, when you wash your gold powder, you do use nitric acid to hot wash out anything that may have made it to that point before drying it.

You must be saying the thread/tutorial by kadriver and others on the forum are wrong.

I know you have read that after you do your washes of the black powder (water, then ammonia, then more water, then nitric acid, and then water.... in that order.) I can show you the thread if you like. But again, I never said anything about using nitric acid. I said saran wrap can be used to cover it up, just as with Sulfuric Acid.

Also, nitric acid do not dissolve gold.

Here is the link to the process. Nitric Acid is indeed used.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=7093&start=80#p167168

Kevin

[ADDED LINK ABOVE]

 

[Geo]

The neat thing about the sulfuric stripping cell is the small amount of sulfuric acid left in the powders. When you dilute the acid/powder mixture, the dilute sulfuric should dissolve any copper metal in the powder. I found that diluting with water and given time for the powder to settle, the solution will turn aquamarine to blue. It should do a pretty good job of removing excess copper.

 

[Anonymous]

The neat thing about the sulfuric stripping cell is the small amount of sulfuric acid left in the powders. When you dilute the acid/powder mixture, the dilute sulfuric should dissolve any copper metal in the powder. I found that diluting with water and given time for the powder to settle, the solution will turn aquamarine to blue. It should do a pretty good job of removing excess copper.

I have experienced that same effect before when I used my sulfuric cell and after decanting it, added some water to the powder solution. I'm glad you pointed that out. Since the pyrex dish I have that I don't have a plastic lid for (like the one in Lazersteve's video) I covered mine with saran wrap, and it's still air tight from after 7 months.

Kevin

 

[Harold_V]

The neat thing about the sulfuric stripping cell is the small amount of sulfuric acid left in the powders. When you dilute the acid/powder mixture, the dilute sulfuric should dissolve any copper metal in the powder. I found that diluting with water and given time for the powder to settle, the solution will turn aquamarine to blue. It should do a pretty good job of removing excess copper.

It is commonly accepted that dilute sulfuric acid does NOT dissolve copper. If it did, it would not be satisfactory for use as a pickle for copper.

However, it WILL (and does) dissolve copper oxide, which is what you see when you do the process you mentioned.

Don't believe me?

Put a small piece of copper wire in a small beaker with some dilute sulfuric acid. It can be new or old copper wire, it makes no difference. Drive it to a boil. Take note that the copper gets clean, and nothing more.

Heated concentrated sulfuric will dissolve copper.

Harold

 

[Geo]

The neat thing about the sulfuric stripping cell is the small amount of sulfuric acid left in the powders. When you dilute the acid/powder mixture, the dilute sulfuric should dissolve any copper metal in the powder. I found that diluting with water and given time for the powder to settle, the solution will turn aquamarine to blue. It should do a pretty good job of removing excess copper.

It is commonly accepted that dilute sulfuric acid does NOT dissolve copper. If it did, it would not be satisfactory for use as a pickle for copper.

However, it WILL (and does) dissolve copper oxide, which is what you see when you do the process you mentioned.

Don't believe me?

Put a small piece of copper wire in a small beaker with some dilute sulfuric acid. It can be new or old copper wire, it makes no difference. Drive it to a boil. Take note that the copper gets clean, and nothing more.

Heated concentrated sulfuric will dissolve copper.

Harold

Thank you Harold. Does the copper come out of the stripping electrolyte as copper metal or as an oxide? It's an interesting thought as to the mechanism that brings the copper down.

 

[nickvc]

Geo not sure of the chemistry of what happens but as copper reacts easily in air it could be just that process that helps to remove the copper in the dilute sulphuric especially if the copper is in small particle form, I used a similar process to remove excess copper from my stock pots by simply allowing the copper to form copper carbonate and then dissolving it in dilute sulphuric reducing the weight by around 90% which made recovery a lot easier.