# A puzzle



## Dog Biscuit (Jul 15, 2007)

I recently completed a batch of 200 cell phone boards using the AP method. The gold flake return was disappointing, so I checked the diluted solution for gold. The test returned a reading for palladium.

I checked my stannous chloride on a batch of fingers I just finished. It showed a strong gold reaction.

Does anyone have any idea why palladium shows from de-populated phone boards with only gold and solder visible?

Also, would the palladium reading mask that for gold?


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## Harold_V (Jul 16, 2007)

How did you test for palladium? 

Harold


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## Dog Biscuit (Jul 16, 2007)

I used stannous chloride to test for gold and got a yellow and brown reaction. This batch of boards was my first real production run and I have a lot to learn. Thanks Harold.


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## Harold_V (Jul 16, 2007)

If your stannous chloride isn't fresh, you can expect horrible results. That could be part of your problem. 

Are you familiar with DMG? (Dimethylglyoxime)

Harold


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## Dog Biscuit (Jul 16, 2007)

I have some DMG, however I'm not sure how to use it in testing. I made up the stannous chloride 7/14 and got a strong positive test for gold on auric chloride from a batch of fingers.

When I first tested the diluted AP solution, I thought the stannous chloride was not working. Then, I tested the auric chloride and got the strong reading. As far as I know there should not be any palladium in the solution - thus my puzzle.


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## Harold_V (Jul 16, 2007)

DMG doesn't dissolve well in water, but Sue, the guy that was such a PITA and rarely contributed anything to the forum aside from ridicule, suggested that it will dissolve readily in, I believe, alcohol. At any rate, it's a conclusive test for palladium, yielding a brilliant yellow precipitate, even when there's almost no pd in solution. In other words, it's a very sensitive test. Best of all, it has a good shelf life, so you can prepare a couple ounces of the solution and be set for a long time. It's useful in determining the presence of nickel, too, so it serves double duty. You can actually recover pd with it, but the precipitate is voluminous beyond belief, and very sticky----almost impossible to handle. I used it only for testing, precipitating with ammonium chloride and sodium chlorate. 

I'm unable to provide any guidance on making the DMG test solution, for my copy of Hoke's book is in storage and I've been unable to locate it. If, by chance, you don't have a copy, I'll nag you well until you do. It's very good at such things, providing perfect guidance in terms that guys like me (not educated) can follow. I recommend the book highly, as others can attest. 

The results you got could have been attributed to a low gold content, but it would have to be quite low, and the stannous chloride solution of questionable quality. Like DGM, it's quite sensitive. The only time I had negative results was when mine bordered on, or was, worthless. I recall confusing results with weak palladium a time or two. Perfect time to check your stannous chloride, and to make a test with DMG. 

Harold


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## Harold_V (Jul 16, 2007)

Been thinking about your original inquiry. I'm a little troubled. 

If you stripped the gold from the boards, but there was still base metal (copper) left on the boards, it's not uncommon for the stripped gold to precipitate from the solution on the copper. It might not even look like gold, and probably wouldn't. If you saw a black deposit on the boards, along the traces, there's a distinct possibility that your gold went with the processed boards and spent solution. If you haven't tossed anything, it's not lost. The test that you interpreted as pd might have been nothing more than an extremely low display of gold. Not sure, but I wouldn't discount the possibility. Care to comment?

Harold


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## Dog Biscuit (Jul 16, 2007)

Harold,

I think you have solved the puzzle! Some of the boards show clean copper - some show copper with blackened areas - many are completely black where the copper should show. Mike


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## Harold_V (Jul 16, 2007)

There's probably not a lot of gold to begin with, so it wouldn't take much to make a significant change in the yield. While I don't wish you any bad in this situation, it might have been a good learning experience. We pay for our education one way or another. 

The ability to precipitate on base metals can be used to great advantage when you're refining mixed materials that would be, otherwise, difficult to sort. A mixture of dental alloys, for example, can be run accordingly, but you have to use real good judgment. When done properly, you end up eliminating almost all of the base metals, leaving behind only a small amount. The precious metal goes into solution, and is then precipitated on the base metals, slowly consuming them. When the solution tests barren, it is disposed and a new round of acid is applied. You have to know when to stop, and it's important to constantly test the solution so you don't discard values. 

I don't know that I'd have any advice in this case-----I avoided low grade wastes like the plague, having more to do than time allowed when I refined, so I don't know what I'd do in a similar circumstance. There are guys here (Steve, in particular) that have dedicated a great deal of their time tuning up the stripping process, so they may be able to offer some good advice on what to do to avoid the problem in the future. 

One thing I will offer, and I've mentioned it quite a few times. The refining game really consists of two distinct operations. The first one is recovery----the second is refining. When they are combined, you rarely get gold of good quality. Precipitating gold from a solution that is barren of base metals will always yield a cleaner final product, so do your best to eliminate the base metals prior to dissolving the gold. 

Harold


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## lazersteve (Jul 16, 2007)

Harold said:


> precipitating (Pd) with ammonium chloride and sodium chlorate.



Harold, 

Can you give me some numbers on this process? How much ammonium chloride and sodium chlorate per gram of dissolve Palladium?

Thanks,

Steve


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## Dog Biscuit (Jul 16, 2007)

Harold,

Thank you so much for your time and advice. This has, indeed, been a learning experience. Unfortunately, I have learned, too late from studying this forum, cell phone boards are very low yield, I have acumulated about four thousand of the little pests over the past two years and need to find a method to deal with them.

There appears to be two choices. One, to take a page from Megan Rose, I can simply "nibble" the border traces and treat them as small fingers with AP. Two, I can use the E-cell to strip the borders. Yes, this does work, as the borders are continuous.

In any case,, this will necessitate tossing the soldering pads, which are a waste of time anyway because of the solder contamination on most of them.

I think Thomas Edison said something about failure. To paraphrase, "If I fail a thousand times, I know what doesn't work."

Thanks again. 

Mike


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## Harold_V (Jul 16, 2007)

lazersteve said:


> Harold said:
> 
> 
> > precipitating (Pd) with ammonium chloride and sodium chlorate.
> ...



Trusting to memory, and dealing in troy ounces, not grams, I recall that you should use an ounce of ammonium chloride for every ounce of Pd you expect to recover. This process parallels the recovery of Pt in that the ammonium chloride, which is dissolved in hot water (which turns very cold, thus you should always start with hot water to facilitate the dissolution of the ammonium chloride) is introduced to the chloride solution bearing values. That solution should be concentrated---diluted solutions will not precipitate. Assuming you have no Pt in solution, you then heat the solution to a point just below boiling. Sodium chlorate is then winnowed into the near boiling solution. You'll notice that the solution starts to change color, at which time you should start seeing minute particles forming, deep red in color. You continue to introduce the sodium chlorate a tiny amount at a time until all the Pd is down. Stirring the solution will often "seed" the precipitation, for reasons I don't know. Study Hoke for clarification. The amount of sodium chlorate is difficult to determine, for each case appeared to be different in my experience. Likely an ounce/ounce proposition as well. Dunno. 

Again, if your solution is too dilute, nothing will happen. Sparse amounts will not precipitate at all, although when you start with a concentrated solution and work properly, it is possible to make a complete recovery. Washing the salts is tricky in that they dissolve readily in water. I suggest you study Hoke for proper washing instructions. Don't discard any of the solutions if they show traces of vales. Start and maintain a stock pot so you can recover them. Again, study Hoke. 

Harold


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## lazersteve (Jul 16, 2007)

Dog Biscuit,

I had planned on making a very short video on removing the microthin edge plating from the cell phone boards. Maybe later tonight I'll post you a short take showing you how to get the pests stripped rapidly. The components are still on the boards I have and don't necessarily have to be removed. Basically just use AP and a toothbrush to remove the coating in no time flat. The cell may be just as fast. With 4000 to process you may actually get a decent BB out of the batch!! :lol: 

Steve


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## lazersteve (Jul 16, 2007)

Harold,

Thanks for the quick overview on precipitating Palladium. I have about 1.5 Liters of fairly concentrated Palladium bearing solution. I wanted to video the precipitation process soon. I'll study Hokes more before I take the plunge.

Steve


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## badastro (Jul 17, 2007)

It may actually be better to sell your phones to http://www.grcrecycling.com/ rather than refine them yourself. They pay 50 cents minimum per phone regardless of its condition. Newer phones pay out more...

I've never actually dealt with them. I just couldn't get a significant number of phones....


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## Aristo (Jul 17, 2007)

Recovery of Palladium is done with Sodium chlorate or ammonium chloride?. Could someone kindly elaborate?. DMG is quite expensive and most of the time its hard to find.

I have read somewhere that the addition of aqeous ammonia to solutions with palladium would form a palladium salt ppt......anyone had any experiences with this?. It goes on to say that the ppt would then be dissolved in ammonia and Pd would be precipitated.

PS... Nice forum and very insightful info. Good work.


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## goldsilverpro (Jul 17, 2007)

A guy I knew first dropped the Pt with ammonium chloride. After filtering off the Pt compound, he made the solution alkaline with ammonium hydroxide and dropped the Pd with ammonium chloride. I don't think the sodium chlorate was needed using this scheme. I never tried this method.


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