Chemical 20 pounds of Gold filled to refine

[goldsilverpro]

Just curious how you would do GF over stainless?

Tyler

Exactly the same as with glass.

 

[moose7802]

Wouldn't the hcl attack the stainless container?

Tyler

 

[kmann1969]

Thanks guys!! the information you have provided is great!! Thank you Harold for the process outline. i have just about everything i need to start processing. im still looking for a fume hood thats reasonable. I am going to start off with a 300 gram batch or two until i am efficient enough in the processes to move onto larger batches. I do have a question about the stainless steel pots, wont the process eat the stainless pot? and since i wouldn't have to worry about glass breaking can i crank the heat up higher to speed the process? I live in the country with no real close neighbors should i have a fume scrubber or will it dissipate enough to where not to worry about it.

Thanks again for all the info!! this forum is great. My wife is starting to call it the other women!!haha

Kevin

 

[goldsilverpro]

Wouldn't the hcl attack the stainless?

Tyler

I assumed we're talking about nitric only because that's what is used on gold-filled to leach out the base metals. Not HCl or AR. Anyhing with HCl in it you must use glass or plastic.

 

[moose7802]

I thought he said the GF he has is over stainless that is why I was saying not to use a stainless container and the reasons for my questions. I also have some GF I'm about to run that is Au over stainless. So I will be leaching the base metals with hcl first then rinse, incinerate, then AR.

Tyler

 

[Westerngs]

If you can expose the stainless under the GF, soaking it in HCl would probably work well. You would not need to dissolve all the stainless, only enough for the gold to flake off.

 

[Palladium]

Run it in nitric and pick and wash the big pieces off. The smaller pieces will get digested in ar with some amount of work and knowledge. It's as simply as it sounds, but then again it's not! Hcl will not work for removal of base metals from gold filled. Hcl does not dissolve copper.

 

[goldsilverpro]

Gold-filled on stainless is a whole different deal. What are you running, watch bands?

 

[moose7802]

They are some type of spring. I have not received the material yet I will be getting it soon. I just know it's GF over stainless. But yes I do have some watch bands that are GF over stainless I'm going to run soon.

Tyler

 

[Harold_V]

For the record, in almost all cases, the white metal under gold on the tops of watch bands is not stainless. It will process perfectly well with dilute nitric. (Take note that I am speaking of watch bands that were available to me when I refined. Today they may be different. I don't know.) The bottoms of the bands are, in fact, stainless.

If you're going to the trouble to strip the tops off, try a couple before jumping to conclusions. I highly recommend you incinerate first, however, as the only thing I ever processed that was dirtier than watch bands was the occasional set of gold rimmed glasses. Some appeared to have never been washed in their entire useful life. For me, these things went directly to incineration, after removing the glass (by breaking). Interesting to see metal frames supporting flame, albeit briefly.

Long before I sold my refining business I had stopped dismantling watch bands, choosing to remove the gold in a cyanide cell. It was a slow process, but it ran without my attention, so that was fine with me.

Harold

 

[moose7802]

Thanks Harold, I actually did take the time to pluck the tops off and I know there stainless because I put them in Nitric with some other GF that I had and nothing happened to them.

Tyler

 

[niteliteone]

Thanks Harold, I actually did take the time to pluck the tops off and I know there stainless because I put them in Nitric with some other GF that I had and nothing happened to them.

Tyler

Throw a few into some HCl and see what they do. I've got a pound or so to do myself

 

[moose7802]

Thanks Tom. That's my plan as I have already put some to nitric with no luck so now they will go to hcl.

Tyler

 

[Harold_V]

Ok, things aren't what they used to be, which was one of my fears. I'm way behind the curve on this stuff now, and it's becoming quite evident.

One of the things you can do with excellent results is to process such material using AR. Yeah, I know---I speak out against that process regularly, but there's method to my madness.

If you use too little AR, some of the base metal will get dissolved, along with the values. However, as the acid level declines, there will then take place cementation of the values on the remaining base metal, further dissolving what remains. If you control the process well, all of the values will get cemented, then you can decant the now barren solution (after allowing the values to settle well), then start again. You can eliminate the vast majority of the base metal this way, so you work with a much cleaner solution. I used that very process when I received a large volume of dental material that was mixed high temp alloy with platinum and palladium bearing material. Testing each piece wasn't in the cards, but this process worked very well in eliminating the unwanted high temp alloy.

Harold

 

[moose7802]

Awesome advice Harold! I really appreciate all the help and members of this forum that aren't afraid to indulge us with their years of knowledge. I am great full for the great people I have meet and some that I have only just come in contact with. Thanks again guys and of course Harold for keeping this thing a tight ship.

Tyler

 

[kadriver]

Ok, things aren't what they used to be, which was one of my fears. I'm way behind the curve on this stuff now, and it's becoming quite evident.

One of the things you can do with excellent results is to process such material using AR. Yeah, I know---I speak out against that process regularly, but there's method to my madness.

If you use too little AR, some of the base metal will get dissolved, along with the values. However, as the acid level declines, there will then take place cementation of the values on the remaining base metal, further dissolving what remains. If you control the process well, all of the values will get cemented, then you can decant the now barren solution (after allowing the values to settle well), then start again. You can eliminate the vast majority of the base metal this way, so you work with a much cleaner solution. I used that very process when I received a large volume of dental material that was mixed high temp alloy with platinum and palladium bearing material. Testing each piece wasn't in the cards, but this process worked very well in eliminating the unwanted high temp alloy.

Harold

I have a small batch of gold filled (GF) scrap jewelry that I am going to process, about 300 grams.

I start by cleaning mechanically; removing stones, steel springs and other non metal items with pliers and metal cutters.

I recently started to use a magnet to separate the magnetic into a separate pile from the non-magnetic GF scrap.

The non-magnetic scrap is usually watch cases, bangle bracelets and other jewelry items. They usually contain non-ferrous base metal such as brass or copper and these digest nicely in hot dilute nitric. Since some stainless is not magnetic, I check carefully to ensure that no stainless is added to the non-magnetic pile.

The magnetic GF scrap comes from watch band tops (the little decorative covers that hide the stainless steel springs and riggings of the watch band) and they are peeled off from the watch band one at a time. They frequently only have one side that is rolled gold. The other side is left bare of gold because it faces downward toward the stainless watch band. But there are also some GF jewelry pieces that have ferrous (iron) base metal.

As an experiment, I would like to try the hot AR treatment on the magnetic and stainless GF scrap.

Harold, In your writing above it says that you decant the barren solution and start again.

Before decanting the barren solution and if I controlled the reaction carefully, then I would have cemented gold with a small amount of undigested ferrous base metal under a barren solution.

I would then (after patiently waiting for everything to settle completely - probably overnight), decant the barren solution, test for values, then add to waste for treatment.

Then add fresh acids to the cemented gold and remaining ferrous base metal to form new AR and continue until everything in the container, the cemented gold and undigested ferrous base metal, are both completely in solution, filter, and precipitate - is this the correct procedure?

Thank you, kadriver

 

[Harold_V]

Then add fresh acids to the cemented gold and remaining ferrous base metal to form new AR and continue until everything in the container, the cemented gold and undigested ferrous base metal, are both completely in solution, filter, and precipitate - is this the correct procedure?

Yes. If you use care, the last addition of AR will digest very little base metal, as the majority if that material will have been dissolved and removed in previous operations. It's highly unlikely you'd eliminate all, but simply by reducing the ratio of values to base metal makes this worth the effort.

I almost never recommend the use of AR on base metals, but this is one case where, if used with wisdom, it can prove to be quite beneficial.

Harold

 

[Geo]

i processed a small batch of GF (mostly watches) with nitric first. the gold came off the bands and left clean shiny stainless steel untouched. there was one band that was unaffected by the nitric. the gold stayed in place and wasnt loosened. i had to digest the entire band, base metals and all. it had gold on all exposed surfaces and not just the caps. it was a very old ladies watch.

 

[kadriver]

Thanks, I've got a small batch of stainless and magnet GF scrap and I am going to try this. May be I'll post some photos for all to see.

kadriver

 

[kadriver]

i processed a small batch of GF (mostly watches) with nitric first. the gold came off the bands and left clean shiny stainless steel untouched. there was one band that was unaffected by the nitric. the gold stayed in place and wasnt loosened. i had to digest the entire band, base metals and all. it had gold on all exposed surfaces and not just the caps. it was a very old ladies watch.

I did a small batch of non-magnetic GF scrap. I sorted it carefully to ensure that the scrap had base metals that were brass or copper only with a thick layer of gold. I digested in dilute nitric acid.

Like Geo, I had two pieces in that non-magnetic batch were the base metal was some sort of non-magnet steel and was unaffected by the nitric. The gold foil did come off these two pieces and retained their original shape and I was able to match the gold foil to the undigested piece of steel. I picked out the two undigested non-magnetic steel pieces with tweezers.

Just goes to show; just because a piece of GF scrap is not magnetic does not guarantee that it is brass or copper base metal, could be non-magnetic steel! Another point is that the gold foils will, in some cases, come off the stainless base metal just like it did in my batch above and in Geo's batch.

Geo, did you use AR to digest the band with gold on the old style ladies watch?

kadriver