Refining Gold from Gold Filled Jewelry

[kadriver]

I rinsed the gold powder out of the beaker with distilled water from a squirt bottle.

This put an excessive amount of water in the dish with the gold and water takes a long time to evaporate - even when heated.

I use a folded up piece of paper towel and tilt the dish to get all the clear water to one side of the dish.

Then I dip the tip of the paper towel into the water, being careful not to get any of the particles of gold sucked up into the paper towel.

It very effectively removes all the standing water and saves lots of time while waiting for the gold powder to dry so I can melt it into a button (or a bar if there is enough gold powder for that).

 

[goldenchild]

So it sounds like the heating technique worked well. 8) Just one thing. The picture of you pouring the gold chloride. Its looks a bit cloudly like it could have been put through a filter one more time. I think very thorough filtration is sometimes overlooked. You can drop that nice brown clumpy sponge from solution even in a very dirty solution if youve filterd thoroughly. That may possibly be why your solutions were taking so long to settle. Keep the pictures coming Kad. We love pictures!

 

[kadriver]

While I waited for the gold powder to dry, I took the filter paper and held it with tweezers over the heat to dry it out. With the burner on high, it took about 15 seconds to completely dry.

Then I tore it up into pieces and put it in a melt dish and covered with lots of borax.

Using a torch with the flame on low, I slowly melted the borax over the pieces of filter paper containing the gold from the filtering earlier in the post.

I made a video of this process. I will edit the footage and produce a short video and post it later tonight or tomorrow.

The photo below is a shot of the piece of gold that I recovered from the filter paper.

The filter paper gets completely erradicated during this process - no traces of it are left in the melt dish. And the melt dish is clean from all that borax.

If fact, I used the same melt dish to melt the dried powder coming up in the next shot.

 

[kadriver]

Thanks goldenchild - I filtered the solution about 5 times through the same filter paper, the last couple times there was no change in the clarity so I gave in and decided to drop the gold as this was a recovery. I will add the resulting button to my next batch of karat scrap for inquarting.

 

[kadriver]

Once the gold powder was completely dry, I transfered it to the same melt dish I used to recover the gold in the filter paper. It was still hot!

 

[kadriver]

I also added the piece of gold I got from the filter paper to the powder before I melted it.

 

[kadriver]

Here is the resulting button before getting a bath in dilute sulfuric acid to remove the borax that clung to it.

 

[kadriver]

Here is the button taking a bath in warmed, dilute sulfuric acid.

 

[kadriver]

Here is the new button posing with the other three pieces I recovered from filter papers.

 

[kadriver]

A shot of the reverse side of the button.

 

[kadriver]

I had calculated that there should be about 5.75 grams based on the amount of scrap gold filled material I started with. I conservatively estimated that the resulting gold button would weigh about 4 grams.

To my astonishement the button weighed in at 9.2 grams!

I was very pleasantly surprised. There must have been way more gold on those filled and rolled gold watch covers and bracelets that I used.

Some of them were real old - what a wonderfully rewarding experience it was to have recovered this much gold from this batch!

Many thanks to this forum and to those who helped me along in this process.

kadriver

 

[kadriver]

Here is the video I made showing how to recover the gold powder that gets trapped in a filter paper using a torch, melt dish and borax.

The filter is incinerated and completely destroyed leaving no traces.

[youtube]http://www.youtube.com/watch?v=GlozdhFuExk[/youtube]

Comments and critical input welcomed and appreciated.

kadriver

 

[Oneal58]

Kadriver, you missed your calling. Instead of Flying around with those Stewardess you should have been teaching? No,on second thought, I think flying with the Stewardess wasn't too bad of a choice? Would have been a hard choice to make??? Wife's ironing right now? :lol:
Thank You Kadriver, just saying you did an absolutely wonderful job somehow just doesn't give the amount of credit that your hard work deserves!!
Just like everyone on this site, saying thank you anymore just sounds empty now, just isn't enough anymore for the amount you give to others like me. Who did not stand a chance witout you!
Oneal

 

[HAuCl4]

Great descriptions and photos Kadriver!. 8)

Only comment I can think right now is that if you intend to re-refine the gold at a later stage, it's best to keep it in powder form and not melt it, but you already know that.

Cheers!. 8)

 

[butcher]

Another option is using Harold's trick, and GSP's trick.

GSP's trick "(use minimum amount of nitric when making aqua regia to dissove gold)"

Harold's trick "(use Kadriver's shiny gold button to see how well you done with GSP's trick, to eliminate excess nitric from aqua regia)"

(well not a direct quote)

 

[kadriver]

Thanks to all for your kind words.

kadriver

 

[HAuCl4]

Another option is using Harold's trick, and GSP's trick.

GSP's trick "(use minimum amount of nitric when making aqua regia to dissove gold)"

Harold's trick "(use Kadriver's shiny gold button to see how well you done with GSP's trick, to eliminate excess nitric from aqua regia)"

(well not a direct quote)

I like the "no nitric" trick the best for dissolving gold powders. Nitric has become expensive and a hassle to obtain (In some places it has become a controlled substance requiring police permits for purchase, etc, etc, etc).

A few people I have setup are using inquartation and parting with sulphuric acid, and those that want finer purity after that use HCl and Clorox or Sodium Chlorate or something else. No nitric acid at all anywhere, except for assays. :shock:

 

[kadriver]

I remember reading Harolds tip on adding a gold button, but I cannot remember where.

Can someone post a link to Harolds description of adding the gold button while adding nitric acid to ensure the nitric is used up?

I would like to copy it and print it out for my notes.

I used to pre-mix the aqua regia and add it slowly to dissolve the gold. Sometimes the gold would be completely dissolved and I would end up with aqua regia sitting in the container, unused.

I like the idea of adding just hydrochloric at first, them adding small amounts of nitric acid slowly over time until all the gold is dissolved.

I used this method to dissolve the gold that produced the button in this post.

Thanks - kadriver

 

[philddreamer]

Kad, it's been posted several times, one way or another, but, this is the copy I saved in my notes about a year ago, I hope it helps:
"Q-goldenchild: Where does Harold talk about saving a button to get rid of excess nitric?
Answer: I don't have a clue where I may have made mention, but it is a process used ONLY if you evaporate. When all of your feed has been dissolved, a weighed button of gold is then added to the solution, which would be kept warm enough for evaporation. As the solution concentrates, any free nitric will dissolve some of the button, or even all of it, assuming there is an abundance.

This process is used to avoid using urea. I never used urea at any time. Preferring to evaporate, but more importantly, to use only the amount of acid necessary to do the intended job. You get amazingly good at judging after you've refined for a while.
However, I found it far faster to use a slight excess of acid when dissolving the values instead of trying to hit it dead on. That insured all values were dissolved when processing wastes that contained other substances, such as filings from a jeweller’s bench. A slight excess insured the customer lost no gold. The added button eliminated the free nitric problem without effort on my behalf. I evaporated, regardless, because I preferred to keep my solutions highly concentrated. YMMV.

One word of caution, if you elect to use an added button of gold, do not be mislead by a lack of activity on the button as the solution gets concentrated. The cause can be due to the lack of free HCl, so to insure that is not the case a small amount of HCl should be added to the solution as activity subsides. An excess of HCl does no harm, unlike free nitric.
By weighing the button before, then after it has been used, you can determine how much gold you added to the solution. That was important for me, because I ran individual batches for each of my customers. I had to know their yield in order to settle. Harold"

When using AR, I first add the HCl to the gold, then some peroxide; start to heat the solution & as the reaction starts, I add a small increment of nitric. When the reaction slows or stops, then I add another small increment of nitric; I do this until all the gold is dissolved.
I always calculate the amount of acids needed for the digestion of the gold.

Take care!

Phil

 

[kadriver]

Thats it - thanks Phil