Diamond / Stone Removal Process

[Romantic]

I have decided to try an acid based stone removal process myself. This will be my first attempt at any sort of gold refining.

What I have is about 13oz of mixed 10K & 14K Gold mountings with diamonds. All the items have been cut to where it is just the smallest bit of gold that is holding the stones. There might also be a few tennis bracelets that will have to go in whole (too much of a PITA to cut apart). It is a mix of white and yellow gold. I would like to recover the silver and any platinum mountings that might be there as well.

I have watched a bunch of online videos and read a bunch of stuff and found some great step-by-step guides here...

http://www.abovetopsecret.com/forum/thread812741/pg1
http://www.abovetopsecret.com/forum/thread810904/pg1
http://goldrefiningforum.com/phpBB3/viewtopic.php?p=6873#6873
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=5480&p=47002&hilit=flask+scrubber#p47002

However none of this really talks about the stone removal process. Do I have any extra steps for this?

One of these guides referred to "inquarting" the gold first. I don't really know what that means and if it is required for what I am doing.

I see a lot of talk about using plastic buckets for the acid stage. Will any kind of plastic work?

Other articles say to use a glass container and apply heat during the process. Which is best?

With glass, I don't see how I can build a scrubber. How would I deal with the fumes using glass?

Is there a step-by-step guide for the stone removal process?

THANKS!

 

[maynman1751]

Do a search within the forum. Type in "stone removal". Here's one I found.

I refined for a pawn shop that didn't remove the small stones, anything under about .2 carat in size. I used a flex shaft and a small abrasive disc to cut the prongs. Doing them by other means was too slow, because the amount of scrap submitted for refining was large----often yielding near 100 ounces of gold. I made more money on the removed diamonds than I did on the refining. They didn't want them returned.

You need not fear hurting a diamond with a grinding wheel of the type I described-----but softer stones can be harmed if you don't use care. For me, it was worth the risk to make stone removal a faster process.

I made a small glove box with a viewing window (piece of large diameter plastic pipe with a Lucite window) so I could catch the grindings that came from the stone removal process. No losses that way.

Harold

 

[nickvc]

You haven't picked the easiest process to start with, it takes some skill to release the stones from assorted material, some will dissolve completely some will just sit in the beaker snickering at your attempts. Forget plastic you need heat and decent extraction and will still have to eye and hand sort the stones. At the very least your going to have to remove the silver chloride from your stones and that involves using ammonia which needs acidifying after use.

 

[Palladium]

True education isn't cheap. :mrgreen:
Nick is right. Most processes are learned in simple one step processes. This one here may seem simple, but the overall complexity of what's involved is not. This lesson can cost you dearly and i think i seen a post where you mentioned having a problem with your refiners numbers and in that post the complexity of this undertaking was explained. Where are you located at?

 

[Romantic]

Removing tiny melee stones with a grinding wheel is not an option.

Do a search within the forum. Type in "stone removal". Here's one I found.

I refined for a pawn shop that didn't remove the small stones, anything under about .2 carat in size. I used a flex shaft and a small abrasive disc to cut the prongs. Doing them by other means was too slow, because the amount of scrap submitted for refining was large----often yielding near 100 ounces of gold. I made more money on the removed diamonds than I did on the refining. They didn't want them returned.

You need not fear hurting a diamond with a grinding wheel of the type I described-----but softer stones can be harmed if you don't use care. For me, it was worth the risk to make stone removal a faster process.

I made a small glove box with a viewing window (piece of large diameter plastic pipe with a Lucite window) so I could catch the grindings that came from the stone removal process. No losses that way.

Harold

 

[nickvc]

Removing tiny melee stones with a grinding wheel is not an option.

Do a search within the forum. Type in "stone removal". Here's one I found.

I refined for a pawn shop that didn't remove the small stones, anything under about .2 carat in size. I used a flex shaft and a small abrasive disc to cut the prongs. Doing them by other means was too slow, because the amount of scrap submitted for refining was large----often yielding near 100 ounces of gold. I made more money on the removed diamonds than I did on the refining. They didn't want them returned.

You need not fear hurting a diamond with a grinding wheel of the type I described-----but softer stones can be harmed if you don't use care. For me, it was worth the risk to make stone removal a faster process.

I made a small glove box with a viewing window (piece of large diameter plastic pipe with a Lucite window) so I could catch the grindings that came from the stone removal process. No losses that way.

Harold

Hate to tell you the bad news but as I said before this isn't easy, when you actually try it you may well decide the costs and losses are worth it. Set up costs are not cheap and actually getting those small diamonds out can be a pain, that's been very polite, if as Palladium said your following on from that post you never bothered to give us the details so we can't tell you the answer you asked due to lack of information.
You feel that your not getting a fair shake then spend the time to learn the basics and don't try to run before you can walk, keep your material and spend the necessary time to learn how to do what you want to do.
I state again this isn't easy!

 

[Romantic]

I am on here trying to learn. As for my previous post and not providing additional info, the only info I did not provide was the weight of the recovered stones. I am sorry, but I don't have that info.

Removing tiny melee stones with a grinding wheel is not an option.

Do a search within the forum. Type in "stone removal". Here's one I found.

I refined for a pawn shop that didn't remove the small stones, anything under about .2 carat in size. I used a flex shaft and a small abrasive disc to cut the prongs. Doing them by other means was too slow, because the amount of scrap submitted for refining was large----often yielding near 100 ounces of gold. I made more money on the removed diamonds than I did on the refining. They didn't want them returned.

You need not fear hurting a diamond with a grinding wheel of the type I described-----but softer stones can be harmed if you don't use care. For me, it was worth the risk to make stone removal a faster process.

I made a small glove box with a viewing window (piece of large diameter plastic pipe with a Lucite window) so I could catch the grindings that came from the stone removal process. No losses that way.

Harold

Hate to tell you the bad news but as I said before this isn't easy, when you actually try it you may well decide the costs and losses are worth it. Set up costs are not cheap and actually getting those small diamonds out can be a pain, that's been very polite, if as Palladium said your following on from that post you never bothered to give us the details so we can't tell you the answer you asked due to lack of information.
You feel that your not getting a fair shake then spend the time to learn the basics and don't try to run before you can walk, keep your material and spend the necessary time to learn how to do what you want to do.
I state again this isn't easy!

 

[Romantic]

I am in East Tennessee

True education isn't cheap. :mrgreen:
Nick is right. Most processes are learned in simple one step processes. This one here may seem simple, but the overall complexity of what's involved is not. This lesson can cost you dearly and i think i seen a post where you mentioned having a problem with your refiners numbers and in that post the complexity of this undertaking was explained. Where are you located at?

 

[nickvc]

No disrespect but you have been a member for some years, I guess as most who have earnt a living from buying scrap the small details didn't matter, things have changed, the small details are now how you make a living or go under.
I will repeat myself you need to read and learn there is no quick fix, what we all discuss is complicated science, your not going to be able to do what you want now, give it 12-24 months maybe, this is not a quick read and fix solution, hit the books and use the search function and learn what you need to know or find a new way to earn a living.
I know I sound harsh but I'm just giving you the truth, it's not nice but it's the honest answer, 10 posts since you joined in 2011, have you studied the forum?
This isn't what you want to hear but do you understand even the basics of recovery and refining?
If not your at the mercy of those that do as GSPs tag line says, the refiner is the last liar!

 

[Romantic]

nickvc, if you don't want to answer any of question I post that is fine but I don't understand why you insist on downing me. You have call me "stupid" and are now bitchin that I have not posted that much. If you read your responses, you might understand why I have not posted much. I have done much more reading on this forum than posting.

I don't make a living on scrap. I simply want to learn to do he stone removal myself. I came here in 2011 just looking for an honest refiner, now I am ready to try this myself.

No disrespect but you have been a member for some years, I guess as most who have earnt a living from buying scrap the small details didn't matter, things have changed, the small details are now how you make a living or go under.
I will repeat myself you need to read and learn there is no quick fix, what we all discuss is complicated science, your not going to be able to do what you want now, give it 12-24 months maybe, this is not a quick read and fix solution, hit the books and use the search function and learn what you need to know or find a new way to earn a living.
I know I sound harsh but I'm just giving you the truth, it's not nice but it's the honest answer, 10 posts since you joined in 2011, have you studied the forum?
This isn't what you want to hear but do you understand even the basics of recovery and refining?
If not your at the mercy of those that do as GSPs tag line says, the refiner is the last liar!

 

[butcher]

Romantic,

Nick, is trying to help you, he answered your question of how to learn to remove the diamonds, (you have it in your head there is some easy solution to a complicated problem)and from what I can see Nickvc is giving you very good advice, and trying to be as helpful to you as possible, not telling you what you wish to hear (some simple method that does not exist). He is not downing you, or bitching on post count, he is giving you sound advice, trying to help you save money, as I see it you do not understand the complexity of your question, and you do not understand the good answer to help you solve your problem.

 

[nickvc]

Romantic
Please forgive me if I sound like I'm making you look or sound stupid, it's not my intention, I'm just trying to get you to see that recovery and refining isn't as simple as add a few chemicals and it's done.
All the information you will ever need or want is here on the forum but start with small steps and small amounts that won't be a total loss if it all goes wrong, been there done that, read Hoke and follow the guided tour, it's possible to do what you want but as I keep saying this isn't the easiest process to start with.

 

[Romantic]

I truly do not know what I have said that makes you think I "have it in your head there is some easy solution to a complicated problem". I stated in my first post that I have been on the forum reading all sorts of postings about the process. I even listed links to what seemed the most relevant postings I had found. All I hoped for was that someone would point me to additional postings or reference material about stone removal using AR. What I got was, a point to using a dremel to grind them out.

A few weeks ago, I posted about recommendations on a refiner to do this for me and just a general question about a couple of lots and what everyone thought about the results. All I got on that was comments that perhaps I did not know enough to realize if I was already getting a good deal. Not a single person volunteered that they were very happy with xyz or abc refiner.

I only became interested in doing it myself after talking to a long time local PM refiner who explained the process and convinced me that it is possible to do this myself. Then I came back here to learn all I could before I tried a test run. Do to another hobby of mine I do have some experience with chemicals.

As for trying small, I had planed to start with about 1oz of material and see what happens. I currently have about 13oz (and likely 5 times that waiting for me to cut out the stone sections). I never planed to dump in the whole 13oz on my first try. If you think even 1oz is too much, I will start with less. That is the kind of info I was hopping to get here.

My apologies to nickvc, as it was not him that referred to me as "stupid", it was the guy who pointed me to the dremel post. nickvc just seems to keep implying that it is too difficult for me to do. That might be the case, but I intend to give it a try. If anyone really wants show that this forum is about "Refiners helping one another" and point me to some relevant info on this, I would really appreciate it.

Thanks!

Romantic,

Nick, is trying to help you, he answered your question of how to learn to remove the diamonds, (you have it in your head there is some easy solution to a complicated problem)and from what I can see Nickvc is giving you very good advice, and trying to be as helpful to you as possible, not telling you what you wish to hear (some simple method that does not exist). He is not downing you, or bitching on post count, he is giving you sound advice, trying to help you save money, as I see it you do not understand the complexity of your question, and you do not understand the good answer to help you solve your problem.

 

[FrugalRefiner]

My apologies to nickvc, as it was not him that referred to me as "stupid", it was the guy who pointed me to the dremel post. nickvc just seems to keep implying that it is too difficult for me to do. That might be the case, but I intend to give it a try. If anyone really wants show that this forum is about "Refiners helping one another" and point me to some relevant info on this, I would really appreciate it.

Thanks!

Romantic,

I'll take a shot at your question, but first, let's get something straight. No one referred to you as stupid. First, you said that Nick called you stupid. Then you corrected that, and said it was the guy who pointed you to the dremel post. If you'll take a look back at that post, you'll find that line is part of maynman's signature line. It was not a comment directed at you. It is part of every post he makes. If you look at the thread with a fresh mind, you'll find that everyone who has posted has actually tried to help, either by providing links, information, or their hard won opinions on the difficulty of stone removal on mixed material.

In your first post, you said you had "13oz of mixed 10K & 14K Gold mountings with diamonds". You didn't mention at that time that you were only planning to try a small test with one ounce. You've been a member here for long enough that you should be familiar with people coming here saying they've just dumped a couple of computers, a dozen cell phones, and some gold jewelry into a batch of AR and want to know what happened to their gold. So it's no surprise that people have assumed you intended to do the same thing.

You've been a member since 2011, so it's also no great surpise that wne you mention that you don't know what inquarting is, people are suspicious that you haven't done much reading over the last few years. Inquartation is covered fully in Hoke's book. There are links to the book in my signature line. She explains why inquartation is important and how to do it.

Now, let's start fresh. You have a mix of 10K and 14K yellow gold, white gold, and possibly platinum in your material. Stone removal will be difficult because no single process is going to work. Any pieces with more than 10% silver content will be a problem for AR. It will form an impenetrable crust of silver chloride, stopping any further action on the gold. You'll have to go back and forth between AR and one of several processes to dissolve the crust. Platinum will also be a problem, as it is much slower to dissolve than gold. White gold may contain nickel and or palladium, which can each bring their own problems to the endeavor. This is why several members have suggested this can be a difficult process if you don't have a lot of refining experience. It's not that it can't be done. It's just not a good project for a beginner.

I can't point you to any particular post that directly addresses your questions. I know I've read some, but I ddon't have a ready reference to any of them. That's where the search comes to your aid. There is information here, but most members probably don't have specific threads marked that they can direct you to.

I know I haven't reeally answered your question. The best place to start is Hoke's book. It will explain inquartation, why and when it is used, and the problems that will occur when it is not. Once you have a firm grasp on that, you'll be better able to search out the information you seek.

Dave

 

[Romantic]

Thank you FrugalRefiner for a fresh-start. It seems many assumptions have been made about me and then by me. My apologies to all for not being more exact in my initial posts and for any wrong assumptions I made.

Yes I have been here for a few years but I only joined initially to find a commercial refiner that could be trusted. Please consider me a total newbie as far as refining is concerned. I now want to learn the art for myself and yes I have been reading the Hoke book... Thanks for that!

Here is what I have so far..

1. Cover gold/diamonds with HCL in Pyrex container. Add nitric slowly while on heat with watch glass on top until the stones fall out or silver chloride builds a crust and the action stops. Done outdoors of course.

2. In the event that silver chloride builds a crust and the action stops remove the undissolved solids with coarse filtration, rinse and then soak in concentrated sodium thiosulfate solution or ammonia then return to AR in step 1 (repeat as often as required)

3. Filter to remove stones and any undissolved platinum mountings

At this point I get a little confused. I would expect the liquid to contain both gold and silver. If I use Urea to neutralize the nitric and then precipitate out the gold with SMB will the solution still contain the silver? If so, how do I get it?

Is a sodium thiosulfate solution or ammonia preferred for dissolving silver chloride? Do I mix sodium thiosulfate with water and if so what is the ratio? If I use ammonia, do I just add HCL to it before disposal and if so, how much?

Is there any way to scrub the fumes created in step 1?

Thanks again!

 

[FrugalRefiner]

Here is what I have so far..

1. Cover gold/diamonds with HCL in Pyrex container. Add nitric slowly while on heat with watch glass on top until the stones fall out or silver chloride builds a crust and the action stops. Done outdoors of course.

2. In the event that silver chloride builds a crust and the action stops remove the undissolved solids with coarse filtration, rinse and then soak in concentrated sodium thiosulfate solution or ammonia then return to AR in step 1 (repeat as often as required)

3. Filter to remove stones and any undissolved platinum mountings

At this point I get a little confused. I would expect the liquid to contain both gold and silver. If I use Urea to neutralize the nitric and then precipitate out the gold with SMB will the solution still contain the silver? If so, how do I get it?

Much better! Keep studying.

You'll have two liquids at this point - the AR, and the thiosulphate or ammonia. We'll start with the AR.

In general, gold and silver will not be found in the same soultion. Remember, it is silver creating a silver chloride crust that stops the action of the AR. This tells us that silver isn't very soluable in AR. The qualifier here, is that strong AR solutions can hold a small amount of silver in solution. This is why it is good to chill your gold bearing solution, followed by filtering, before reducing your gold.

The other solution will contain silver. If it's an ammonia solution, you do want to reacidify it promptly to avoid the creation of any explosive compounds. That is where you'll find any silver, in the form of silver chloride. I can't answer your thiosulphate question, but I'm sure someone else will be able to.

Is there any way to scrub the fumes created in step 1?

Absolutely. You'll find plenty of information here on the forum.

Dave

 

[artart47]

Hi Romantic!
This may make it easier to understand. When you inquart you are spreading out the gold atom so that the nitric acid can penetrate to the core of the piece and leach out the silver and other base metals, leaving only the gold sponge as a solid. The inquartation would burn your diamonds away durring the melt.
So, you won't inquart till after the diamonds are removed. You will be disolving the pieces in AR so that the diamonds will fall out as their mounts are disolved.
there is a problem though. as the AR removes the surface gold and converts some of the silver to silver chloride, the AgCl will begin protecting the gold below it from exposure to the AR. Any gold that was disolved will remain in the AR. Have a small amount of distilled water in a beaker to rinse the AR off the pieces before they go into the ammonia solution. You will just be soaking in the ammonia to rid the surface of the AgCl crust so that the gold is once again exposed and the AR can continue it's work.
Back in the AR. you will have to do this a number of times.
Inquart and part the gold and then you can use same AR with the little gold in it to do your first refine. Also add the rinse water to the AR and you will have all the gold in the same beaker.
Be sure to study about using AR. You don't make a batch of AR! You will learn how we add small amounts of the nirtic acid as needed. If you don't you may end up with too much and will have further problems.
IMPORTANT ! You must acidify the ammonia /silver solution lest you create explosive compounds that are unstable. Read about metals and ammonia!!!

I'm sure the more skilled members can add to this . I'm still a noob but I've experimented with a few pieces in AR.
If you do the homework before you start pouring chemicals you'll succeed
Hope this helped.
See your gold soon!

artart47 edit; spelling correction

 

[maynman1751]

My apologies to nickvc, as it was not him that referred to me as "stupid", it was the guy who pointed me to the dremel post. nickvc just seems to keep implying that it is too difficult for me to do. That might be the case, but I intend to give it a try. If anyone really wants show that this forum is about "Refiners helping one another" and point me to some relevant info on this, I would really appreciate it.

In know way did I claim you were stupid! That is strictly my signature line! Apology accepted. :roll:

 

[Romantic]

I am very sorry about that. I thought you were directing that directly at me. Sometimes I have been known to resemble that remark anyway

Thanks!

My apologies to nickvc, as it was not him that referred to me as "stupid", it was the guy who pointed me to the dremel post. nickvc just seems to keep implying that it is too difficult for me to do. That might be the case, but I intend to give it a try. If anyone really wants show that this forum is about "Refiners helping one another" and point me to some relevant info on this, I would really appreciate it.

In know way did I claim you were stupid! That is strictly my signature line! Apology accepted. :roll:

 

[4metals]

Romantic,

I think there are a few things here that are messing you up. Lets start with the basics, Aqua regia will not dissolve any appreciable amount of silver so recovering silver from the acid is never an issue. The trouble with the silver is it coats over the gold as silver chloride and the silver chloride stops the acid from attacking the gold. Much like rust covers the surface of steel and actually protects the steel from further rust. (Not totally because it will eventually rust through but it slows it down tremendously, well silver chloride does that to karat gold too.)

You had mentioned in this thread that you at some point have the gold separated between 10 karat and 14 karat. Well quite often if you keep it separate and put the 10 karat in a mixture of half nitric acid and half distilled water you can dissolve the silver and the base metals enough for the stones to fall out. This requires the acid be warm to hot but not boiling. The gold in this case will not dissolve it will remain as a mud with the stones. Often this can loosen the stones or drop them enough for separation. In any event pour or filter off the acid leaving the stones and insolubles behind in the beaker and repeat the nitric distilled water a second time.

The remaining insolubles can now be digested in Aqua regia. If the pre treatment was sufficient (and if it is primarily 10 karat it usually is) there should be only minimal silver to be a problem. Aqua regia will dissolve about 7 1/2 ounces of metal per liter of acid. Do the math and add about 80% of the required acid as hydrochloric acid. Any nitric acid that was not washed out from the previous step will likely start off the reaction, if not slowly add about 1/4 of the total nitric required (4 parts hydrochloric to 1 part nitric) and allow the acid to react until no red fumes are coming off or the only thing on the bottom are stones. The trick here is to use as little nitric acid as possible to dissolve the metal and no more.

A trick Harold has discussed is to add some fine gold when all dissolves in the beaker until the remaining nitric is consumed. But a guy like you may not have or want to waste pure gold on this process so you need an alloy with no silver. Copper will work but so will white gold. Either way burn off the nitric, filter out the stones and they should be clean with minimal picking.

The method for dropping the gold is covered so many times on this forum that repeating it here would be impractical. The same is true for the silver in the nitric solution you used in the pre treatment step.

This is a good method for the 10 karat material and you don't need to gum things up with ammonia or thiosulphate.

Now you need to address the 14 karat material and higher karat material. Unfortunately here you will be dealing with silver in the alloy. When it gets up to 9 or 10 percent it can cause the reaction to freeze up as mentioned earlier. So to start, add enough acid to dissolve the scrap remembering 1 liter of 4:1 aqua regia will dissolve 7 1/2 ounces of metal. As before, add the hydrochloric first (80% of the calculated acid total) and follow that with 1/4 of the nitric. The reaction will proceed and when it slows down add another fraction of nitric. Always keep in mind if you are in a hurry and add all of the nitric too quickly you will likely add too much and you only have to deal with it later. Eventually the reaction will subside either because everything has dissolved (rarely are you that lucky) or because the chlorides have shut down the reaction.

Now you have to filter the insolubles from the acid, I like to pass the acid through a plastic screen for a coarse filtration. The screen needs to be small enough to catch the smallest diamonds but big enough to allow the small silver chloride particles to pass through. I shouldn't have to say this but no metal screens please.

You should now have a screen with diamonds, undissolved chunks of gold encrusted with silver chloride, and any other insolubles (platinum findings?) Rinse this with tap water and add the rinse to the acid with the silver chlorides in it.

The silver chloride can be dissolved in ammonium hydroxide, a method that produces nasty fumes which always manage to find my nose, or with a solution of sodium thiosulfate crystals in water. I prefer the thiosulfate and I like to tumble them in a small rock tumbler for about 15 minutes. The thiosulfate does not smell.

When done tumbling pour the solution from tumbling and the contents of the tumbler through the same screen and save the tumbling liquor. Usually 1 or 2 times tumbling will suffice. The gold should look yellow if it was silver chloride encrusted to start and the stones will be clean. If the silver was very high, it may require another tumble with thiosulfate. Usually any stones remaining in settings are easy to dislodge and it can be done manually. If you want the gold can be dissolved using the same techniques as the new 14 k scrap was processed in.

Now you have the acid containing your gold, that has to be filtered to separate the gold from the silver chlorides and processed using the methods found elsewhere on this fine forum. The silver chloride on the filter paper should be collected and stored wet and in the dark until you have enough to process, again by methods found elsewhere on this forum. Maybe some of our members can jump in here with some links.

Lastly you have some spent thiosulfate solution containing silver. When you have enough you can use the steel wool canister recovery methods also discussed on this forum to effect a complete recovery.

If you start doing this process regularly, there are some things you can do to conserve like take your insolubles from the 10 karat process and add them with the 14 karat and higher scrap. Then all of the gold recovery will be in one place at the end of all your lots.

Commercial refiners rarely get the luxury of having every karat separate so their process is just like the 14 k process and they have to deal with the excess silver chloride. Rarely do they see a job of mixed karat scrap which does not involve picking of stones from insolubles.

If you decide processing all of your own stone removal lots is the best approach you will want to check out the threads on treating your waste to recover any remaining precious metals and reduce the hazard of your waste acids after recovering the values. It should come as no surprise that you can find all of those details on this forum as well.

The details I have listed require a considerable amount of your time to do. It will get less and less as you learn the process and are more comfortable with it but it will always involve a considerable amount of your time and attention. You had mentioned that you cut off all of the shanks from your goods before shipping for this process. Since a refiners charges are usually a percentage of the total metal recovered, the metal recovered from the reduced weight lots is minimal. Figure out what a refiner can charge for the service based on your yields and reflect on how much work you do to get to the same end. If you have a refiner who pays you fairly and returns all of your stones, you will find it is better to send this work out for processing. But after you do it you will have a better feel for what is involved. I would appreciate your getting back to us after this experience to let us know your thoughts.

Enjoy