Gold will not drop with SMB or Sulfamic Acid

[Ag and Au]

Hello, I am about two months into Gold Refining and I have realized that this is NOT as easy as it looks.
Here is my dilemma:

I separated my gold into a pile of gold plated circuit boards with a whole lot of other components soldered in place. There was no practical way to isolate just the gold areas. I then started the Acid Peroxide (AP) process. The AP process went exceptionally well - causing the gold foil/flakes to float in the AP solution.

I then filtered as much "gunk" out as I could, and then I proceeded with the Aqua Regia (AR) process. This left me with a “goldish colored” solution. A stannous test showed an instant dark brown stain (but no purple). Home free, right? Wrong.

I denoxed it with urea and I could not drop any gold out with the addition of SMB. I then tried a little sulfamic acid and the same result – NO gold drop. Are the other dissolved metals causing mayhem?

Any thoughts would be appreciated?

 

[Yggdrasil]

The description may be lacking information.
1. You obviously do not quite understand what you are doing.
Read C.M. Hokes book you will find it here in the forum.

How did you make the AR?

Urea is best used as fertiliser.
Better use Sulfamic acid, which will not drop any gold but will turn any Nitric/NOx to Sulfuric acid.
It has to be done warm at 70-80 C

Then you can use SMB to drop the Gold.

 

[Ag and Au]

Thank you. I made the AR using HCL (31%) and equal amount water, plus the addition of a nitric acid substitute (MX-3 powder) from a company called Shor International.

 

[4metals]

(MX-3 powder) from a company called Shor International.

Unfortunately whenever chemical products for refining sold by this company pop up in discussion, it always seems to be for the same reason........ something isn't working right.

People here tend to steer away from their products.

 

[Alondro]

Try cementing everything out with pure, clean iron. Then re-process. You can make a simple galvanic cell with two electrodes: one iron, one copper. Connect them with a wire which will remain outside the solution, then hang them on opposite sides of the solution. The weak current generated will pull the less-reactive metals quickly out of solution and crystalize them on the electrodes. It should first pull much to the iron, but as the solution becomes depleted of low-reactivity metals, metal will even begin crystallizing on the copper electrode. That's the sign the reaction is nearly complete.

 

[Golddigger76]

When you are first learning how to refine you need to stick with the ways that are discussed for each or even mixed metals and stay away from unknown/new methods. At the learning stage you do not know enough about chemistry to be experimenting, it's not safe for you, your family and neighbors.
Unknown = Unsafe when you do not understand what reactions will take place. I have been studying this for 10 years and I still will not deviate away from tried and true methods because the ways of refining that I have learned mostly on this forum work great
I wish I could give you advice about the Mx3 powder but I have never used it or anything from shor. They have great marketing but I have never seen great results with their products, not saying that they do not work only there's been quite a few problems with their products that have been posted about here.

 

[Ag and Au]

Great advice everyone. I still need to drop the gold out of this solution. Thank you all.

 

[Shark]

If any metal remained without dissolving, your gold may have cemented out to it.

Leaving excess copper in your poormans AR (basically the same as the Shore method) often will generate more nitric that requires above average amounts of chemicals to neutralize it also. If the nitric does not fully become neutralized it can cause your gold to redissolve. Try neutralizing with sulfamic acid, urea does not work the same way.

 

[FrugalRefiner]

Ag and Au, welcome to the forum. At this point, you have what we refer to as a "mess". That's not meant to be demeaning. It just means you have a combination of liquids and solids, you're pretty sure there's gold in it somewhere, but you don't know where it is, how to find it, or how to recover it. That's OK. You've come to the right place.

First, take a breath, and let everything settle for a couple of days. When all the undissolved solids settle, and the liquid looks clear, you can separate them.

You can test the liquid with stannous chloride. If it's positive, you can proceed to recover any values from it. But in your first post, you said "A stannous test showed an instant dark brown stain (but no purple).". A brown stannous test is usually referred to as a "false positive", and it usually means copper, not gold.

If the solution is barren, treat it properly as toxic waste and dispose of it responsibly.

Then you have the solids... I don't know if a picture would help, but try showing us what you have left from trying to dissolve all your stuff and we can try to help from there.

Dave

 

[Ag and Au]

Dave, your forum and its members are excellent.

I do, in fact, have a mess. Two things I know for sure: 1) I definitely have gold in there and, 2) I definitely have copper and solder in there. I will post a picture tomorrow.

 

[Ag and Au]

This is what my "mess" looks like..... and its stannous test strip results. I can hear the gold asking to be liberated....

 

[FrugalRefiner]

That stannous test looks like a "false positive" to me, meaning there is no gold in the solution.

I'd like to see pictures of the material that was still in the AP. You said you put "a pile of gold plated circuit boards with a whole lot of other components soldered in place." How big was this pile? Was it a few ounces, a few pounds, a five gallon bucketful? That will help us understand how much gold to expect.

I'd also like to see what was left of the "gunk" that you put into AR. If there were any undissolved metals there, your gold probably cemented out on them. That would result in the stannous test not showing any gold.

Dave

 

[Ag and Au]

Hi Dave, The typical board that I started with is illustrated in #1 on the attached photo. The boards that I started with were much larger and contained way more gold than picture #1. I started with approximately 2 pounds of boards in a 5 gallon bucket with approx 3 gallons of AP. The boards were then removed after 10 days and were completely stripped of everything!

When I filtered the AP, there was alot of gold flakes (I know, it always looks like more...) along with a dark gunk powder and lots of electronic components at the bottom of the bucket. I then used the Shor AR process (gold flakes with the dark gunk) ...everything dissolved as I thought it would. I added urea then smb and had NO gold drop. I then added sulfamic acid and heated, then a bit more SMB - No gold drop.

 

[4metals]

I started with approximately 2 pounds of boards in a 5 gallon bucket

One of the hardest things to do in refining is to recover small quantities of gold. Given the yield of gold on typical modern printed circuit boards is as little as 3 and as much as 8 ounces per ton you are looking for an exceptionally small quantity of gold. Let's use the high end, 8 ounces. That is 31.103 grams per ounce times 8 = 248.8 grams of gold per ton. That translates to 248.8/2000=0.1244 grams per pound. You had 2 pounds and you so looking for about 1/4 of a gram. IF the boards ran at the high end of average.

Compound that with the tin which is in the mix from the solder and you likely put your 1/4 gram into suspension as a colloid of gold and tin which just doesn't like to settle out.

When starting out refining, it is best to be processing quantities of scrap which yield more fine gold simply for the ease of spotting it. That is why a lot of guys start with karat scrap or gold filled scrap. There is something to find at the end. Your process has been successfully used by members who have patiently collected foils to the point where there are enough to yield a recoverable quantity.

If I had to guess, which is all we can do, you dissolved your gold foils and the insoluble mud and the gold is hung up as a colloid. As far as the stannous test, testing a solution with a maximum of 1/4 gram diluted to an unspecified quantity of aqua regia may not yield an instant purple indicator to indicate gold. It depends on the dilution. This is why we suggest dissolving a known weight of gold and making dilutions so you can see, first hand, how stannous reacts to different solutions.

 

[Shark]

Picture 0753, the flask on the right may contain your gold. With the small amount of material used it could have dropped and the brown suspension could be the gold powders. This is just a guess but possible.

I would still differ to Dave’s advice as he is much more experienced than I am.

 

[Ag and Au]

I am certain that a detectable amount of gold is in that flask. I produced a fair amount of gold flakes/foils (from the AP process) before dissolving them in the Shor AR solution. Also, I failed to mention that the stannous test also had a trace of "white or silver" in addition to the dark brown stain. Thanks guys. I welcome all viewpoints.

 

[FrugalRefiner]

But you haven't shown us what was left after you dissolved those flakes. Was there anything left that did not dissolve in the Shor AR?

Dave

 

[Ag and Au]

I don't believe so, but I will check my notes later today and reply tomorrow.

 

[Ag and Au]

Here is exactly what I did to create this solution:
1) I added ~ 2-3 pounds of industrial grade circuit boards with high visable gold content (from the early 2000's) to the AP solution
2) Let sit for ~ 10 days with occasional stirring
3) Filtered out all of the solids (lots and lots of electronic components came off the boards)
4) Retained quite a "pile" of gold flakes/foils (and dark powder) in my filter
5) Dried out this pile
6) Added it to the Shor AR solution; all of it dissolved withing 1 - 2 hours, leaving a golden solution and a smile on my face
7) Added urea (no real fizzing observed), then used the Shor Quadratic precipitant and heated it.
8) Waited about 2 hours - no gold drop
9) Added SMB and heated to about 80 degrees C for about 1 hour - no gold drop.
10) Stannous test: instant dark brown and NO purple and a small trace of "white/silver".
11) Added some clean copper pieces - some residue dropped to the bottom of the beaker (didn't look like gold mud)
12) Added some sulfamic acid and heated then added more SMB - No gold drop.

My head is spinning and I am sure yours is too. I normally do not approach such processes like a "bull in a china shop" but this
one got away from me. My suspicions lie in the use of the Shor International products, as I have had dubious results in the past on much simpler, refining trials.

 

[Alondro]

One of the hardest things to do in refining is to recover small quantities of gold. Given the yield of gold on typical modern printed circuit boards is as little as 3 and as much as 8 ounces per ton you are looking for an exceptionally small quantity of gold. Let's use the high end, 8 ounces. That is 31.103 grams per ounce times 8 = 248.8 grams of gold per ton. That translates to 248.8/2000=0.1244 grams per pound. You had 2 pounds and you so looking for about 1/4 of a gram. IF the boards ran at the high end of average.

Compound that with the tin which is in the mix from the solder and you likely put your 1/4 gram into suspension as a colloid of gold and tin which just doesn't like to settle out.

When starting out refining, it is best to be processing quantities of scrap which yield more fine gold simply for the ease of spotting it. That is why a lot of guys start with karat scrap or gold filled scrap. There is something to find at the end. Your process has been successfully used by members who have patiently collected foils to the point where there are enough to yield a recoverable quantity.

If I had to guess, which is all we can do, you dissolved your gold foils and the insoluble mud and the gold is hung up as a colloid. As far as the stannous test, testing a solution with a maximum of 1/4 gram diluted to an unspecified quantity of aqua regia may not yield an instant purple indicator to indicate gold. It depends on the dilution. This is why we suggest dissolving a known weight of gold and making dilutions so you can see, first hand, how stannous reacts to different solutions.

And, always do a first cleaning in just HCl for a couple days. That'll get rid of many of the 'pest' metals like tin, which complex with gold in solution. The HCl can usually be used for several batches of this type of boards. Or, sulfuric acid, but for that one needs a well-built ventilation or gas-capture set up and the ability to warm the acid to 80C and hold it there.

For those with the equipment to do it, though, it's a great way to recover very clean gold and platinum, which will not be touched at all by sulfuric acid, as Sreetips demonstrated in a video where he even BOILED the sulfuric acid with gold powder in it, and the gold powder simply clumped together in a lump.