# Methods for Refining "High Yield Pins" ?HELP?



## dwt9999 (Mar 28, 2007)

I have heard about pins from p-1 processors and other pins that are High yield pins, I however do not know the best method for processing the different types of pins.. Can anyone give advice on the method they would use for the different types?

Would you use AR?

Would you use a Cell?

Any thoughts would be greatly appreciated!!

Thanks in advance for your help!

Lew


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## lazersteve (Mar 28, 2007)

Lew,

Here's a link to a topic for a semi-direct route to pins:

http://goldrefining.110mb.com/phpBB2/viewtopic.php?t=155

As usual with these 'homegrown' techniques they get changed as they get tested and they vary from individual to individual. A sort of evolution or mutation of methods if you will.

Steve


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## dwt9999 (Mar 28, 2007)

Steve,

Thanks for the link!

Lew


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## Fever (Mar 31, 2007)

It seems that it is common knowledge that gold-plated pins should be processed separately from other gold-plated materials. While I agree in sorting like components for the best refining methods, I'm not sure I understand why pins are such a pain in the ass. If all you have are gold-plated pins with exposed non-gold areas (copper, tin, etc), why not just use nitric acid first to dissolve these metals, then filter out the gold particles left over? Am I missing something?

Fever


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## jimdoc (Mar 31, 2007)

I think it is because the pins have solder on them, and it is better to
keep them from the cleaner items.


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## Fever (Mar 31, 2007)

But solder is primarily Lead and Tin right? Or Silver in older items. Won't all 3 of those metals dissolve in Nitric? There must be another reason......

Fever


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## Noxx (Mar 31, 2007)

Yes right.
But you must be very careful when disposing nitric acid containing lead. You should precipitate it before.


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## Fever (Mar 31, 2007)

Good point Noxx-

Though I'm still primarily in the collection stages of processing, I plan on precipitating as many metals from my solutions as possible. Lead is a valuable metal that recyclers will pay for. Same goes for Copper. The most important point that Noxx is making is in regards to Lead's toxicity. It's not something you just want to dispose of in the trash.

Speaking of Lead, what chemical will precipitate it from a Nitric solution? I suppose it depends on what it was dissolved with?

Fever


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## Noxx (Mar 31, 2007)

I know aluminium will make copper and other base metals drop out. I'm not sure about lead but it probably will.


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## lazersteve (Mar 31, 2007)

Fever,

Pins vary in their substance quite a bit. They can range from zinc to brass plated with gold and every other base metal in between. This variable makes a single technique good only with certain types of pins. The nitric is a good overall choice, but it's expensive and hard to come by for most folks. The pins, when all piled together, tend to protect one another from the etchant you choose as well. 

Fortunately, there are plenty of great substitutes. 
Here are a few:

Straight HCl
HCl + H2O2
Ferric Chloride
Persulfate compounds
Reverse Plating 


Another side affect of processing pins is the salts that form. These can show up as solids, sludges, or even emulsions. If you don't have the concentration of solvents right you will get a variety of salts in the gold. Some salts are insoluble in water or acid or both. If you mix a bunch of types of pins together you only complicate the dissolution process with more varieties of metals. These mixtures tend to interact with each other to make one big mess if you don't know how to handle the percipitates you encounter.

Yet another problem arises from debris. These can come in many forms as well. Insoluble ceramics, fiberglass, board laminates, plastics, rubbers, etc.

The list above is just a short summation of the problems associated with doing batches of pins.

If you encounter a specific difficultly, post a question with the details of the experiment and I'm sure the forum can help you out.

Steve


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## Fever (Mar 31, 2007)

Steve-

Great points as usual. Is your favorite is the peroxide and hydrochloric method? Is there a particular reason?

Fever


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## lazersteve (Mar 31, 2007)

I would have to say I use it the most, but I'm trying to get back to the AR or Cl-H20 for the really pure gold.

It does great job at stripping base metals and will even dissolve gold. It's main draw back is it works slowly at room temp. I could heat it to speed things along, but I don't like to have to keep an eye on it so I don't. It's a very good tool. Another side affect is all the left over copper chloride which can't be dumped until the copper is removed. So I've started exploring the uses of the cupric chloride for other tasks.

Steve


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## Harold_V (Apr 1, 2007)

Fever said:


> Speaking of Lead, what chemical will precipitate it from a Nitric solution? I suppose it depends on what it was dissolved with?
> Fever



From the position of a refiner that is looking to eliminate lead from a gold solution, the addition of a small amount of sulfuric acid will precipitate lead as lead sulfate, which is then removed by filtration. As others alluded, it does dissolve in nitric, but it's usually associated with tin, which presents more than its share of problems when it comes to filtration. A somewhat gelatinous substance, a compound of tin, plugs off the filter rather quickly----so you can spend literally days filtering a small amount of solution. 

If you process solder bearing objects with nitric, here's a tip that can help you, and it makes filtration of the chloride solution much easier and faster. After you have eliminated the base metals, get everything in a filter and dried, then incinerate the filter paper along with its contents, heating in a small stainless steel frying pan. Heat the pan to dull redness with a torch (heat the pan from outside, not inside) before removing the contents from the burner, and don't melt the gold. This process eliminates remaining nitric and carbonaceous materials. With traces of nitric gone, you can now do a wash with HCL and water, which will eliminate the problematic tin compound. You might find that a couple repetitions of the water rinse are beneficial. Be certain to decant only after all flocculence has settled well after adding the tap water. 

You can usually find small stainless frying pans at second hand stores for a buck or so. I removed all traces of handles and used wheel weight pliers to handle them to avoid being burned. 

Harold


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## Fever (Apr 1, 2007)

Now that's a great tip. Thanks Harold! I don't think I'll have concentrations of lead that will warrant a scheme like this, but it's great to know the details just in case. Most of the stuff I have picked is free of solder. I usually cut off the solder glob at the end of my pins, and I shear away the non-plated portion too. No need to use more acid for a non-target metal that can be mechanically removed prior to processing.

Thanks for the outstanding info! This is what makes this forum so great!

Fever


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