# Filtering foils from AP - Help Separating the foils



## hauger (Aug 9, 2017)

Hi,

First, I've tried searching the forum, and the internet as a whole, and I can't seem to find much on this small, trivial, but extremely frustrating part of the process....

I'm sure this is eye-roll easy for most, but I'm on my first learning batch of removing gold foils from trimmed fingers. The HCl + aquarium bubbler worked as advertised. I then removed the finger boards and filtered the solution through 3x Coffee Filters. Once the filter had drained, I rinsed thoroughly with distilled water. Again, everything ran as advertised. 

My problem, though, is how do I remove the foils stuck to the filter in an efficient, non-tool-throwing-frustrated way from the filter? I tried spraying and all that did was help the filter fall apart and make a mess plus putting the foils back into a bunch of water.

About the best I can think of is just letting the filter air dry and trying to brush collect the foils.

If anyone has a better plan, I'd really, really like to hear it.

Thanks


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## glorycloud (Aug 9, 2017)

If you let the foils stay on the filter for a long time, the filter
starts to disintegrate. For me, I filter the foils and then rinse them 
off into a bucket with the spray bottle. If some are stubborn and
don't want to come off, I let the filter touch the side of the bucket
and spray the foils down into the bucket using the side wall of the
bucket as a back drop if you will.

That may help you. I have found that if I let the foils sit on the filter
paper for a long time (like overnight or days), the filter does fall apart.
You can probably just go straight to HCL & Clorox to dissolve the foils
and rinse out the auric chloride from the "debris" like small fingers, etc.
that end up in the gold foil mash no matter what you do. 8)


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## hauger (Aug 9, 2017)

That's awesome, thanks. I was thinking of sort of doing that, just running it through a filter again (the foils are in a bucket of distilled water right now) then just letting them dry out. I was planning on running everything through a second HCl bath to get any leftover copper. Would there be any harm in just throwing the whole filter into a HCl bath?

Plan after the second bath is AR instead of HCl + Bleach, mostly because I have 1L of HNO so why not. Once again, is there any harm in throwing the whole filter into AR?

Thanks again for the response.


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## 4metals (Aug 9, 2017)

The paper filter will break down into a pulp in the aqua regia and not inhibit the function of the acid in any way. Then when you filter the acid before dropping out your gold, the pulp from the first filter is caught in the new filter.


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## kernels (Aug 10, 2017)

I do the same as 4metals, don't bother trying to remove the foils from the filter, just dissolve all of it and filter out the broken apart filter paper.


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## steyr223 (Jun 20, 2018)

Be careful not to let anything with color get stuck between filters 
Sometimes when I have a lot of liquid and want
To filter faster I end up with 12 or 16 little filters on a big strainer so as to have at least 3 filters in all spots 
When putting these in hcl/bleach my au tends to get stuck in between.

Steyr223 rob


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## artart47 (Jun 22, 2018)

Hi my Friends!
I always take the foils and the debris that I rinse from the filters with a spray bottle, and keep pouring them into a large mason jar filled with muriatic acid. That's how I store them. When the acid gets too dark I pour some out, filter it and return the solids to the mason jar. I believe it helps clean the foils and other gold debris before refining.
One of my very early posts from circa. 2010 has a photo of me holding my first mason jar. There were many pieces of filter paper that went into the jar, but they seem to just disappear. 
That jar gave me my first button of 19grams! I think it was better than when I first discovered girls!
Art.


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## Rachello (Jun 23, 2018)

Glory cloud, 

I have this exact process... your words are mine true to thought. I hate processing actual filter debris ( filter particles) but take all punches as they come. Sometimes I incinerate, but for foils I rarely do. 

Seems I loose more values out of incineration of foils as I do plain processing. 

I usually just spray off my filter full of foils into a bucket of weak aqua regia & then let them sit for a week in solution. 

If I can’t spray the foils off because I let them sit for to long, I mush them up in a pulp & put it into the same weak solution.

I walk away & come back some other time. I don’t obsess on it & figure it will all dissolve in its own time. When it does, I process like I normally would. Works wonders. 

Rachel


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## nickton (Jun 23, 2018)

This is one of my first stumbling blocks. I find there are so many paint chips, slivers of mylar (I think that's what it is), and small chips of plastic, that I have to use too many filters and end up with a multi colored mess that drives me to individually picking out what pieces I can. I'm definitely concerned about the possible contamination of base metals too, so soaking in Muriatic for another week doesn't sound like a bad idea, to make sure all copper and tin is fully dissolved. I just went through a pretty large batch of clipped off pieces and boards I had previously soaked in Lye. It is so tedious I know there must be a better way, but at least I'm thorough. I have yet to melt any kind of button. I can't sleep tonight because I see tiny pieces of wet plastic in my dreams. :!:


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## g_axelsson (Jun 24, 2018)

Most of my foils never ends up in a filter. Neither do I use distilled water to wash foils.

Whenever processing fingers with copper chloride I let the foils collect at the bottom of a beaker, then I decant the liquid. If I'm going to use it again I might not bother with filtering the copper chloride, but whenever I do that I just unfold the filter at the end and wash the solids back with the bulk of the foils. Anything sticking to the filter just ends up in my burn pile with used filters and other stuff that's been in contact with gold or gold solution.

When I finally refine the gold, I filter the gold chloride but when the gold has dropped and I have washed it I just let it dry in the beaker. The dry gold powder is collected in a small bottle with a glass stopper. Any gold stuck in the beaker is dissolved next time I refine gold as I use the same beaker to dissolve the next batch in.

So most of my gold only sees a filter when it is dissolved as gold chloride.

If I have gold contaminated with too much organic debris like plastic or dust I just incinerate it to reduce the volume and concentrate the gold. Works like a charm. 

Göran


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## philddreamer (Jun 24, 2018)

Goran wrote:


> So most of my gold only sees a filter when it is dissolved as gold chloride.



Same here! I don't like spending the extra time freeing the foils from the filter... I let the foils dropped over night, while I'm doing other things, and then decant the AP the next day. I dissolve the foils in Poorman's AR!
Then vacuum filter, and so on... :mrgreen: 

Take care!
Phil


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## anachronism (Jun 25, 2018)

Mine too - never filter foils etc only gold chloride.


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## nickton (Jun 29, 2018)

Thank you for the replies. For some reason I never quite understand how you guys so easily rinse off and separate those foils from the plastic pieces. For me this is very tedious. I guess I won't use filters at this stage anymore, but I thought distilled water was important in order to leave all gold out of solution. It would certainly be nice not to have to use it yet.


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## Geo (Jun 30, 2018)

Tap water will create silver chloride in silver nitrate but it does not contain enough sodium hypochlorite to dissolve any gold.


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## anachronism (Jun 30, 2018)

Geo said:


> Tap water will create silver chloride in silver nitrate but it does not contain enough sodium hypochlorite to dissolve any gold.



Not always it depends upon the Chlorine quantity in your particular water supply. It's a good idea to test your water but in many cases tap water is fine.


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## g_axelsson (Jun 30, 2018)

nickton said:


> Thank you for the replies. For some reason I never quite understand how you guys so easily rinse off and separate those foils from the plastic pieces. For me this is very tedious. I guess I won't use filters at this stage anymore, but I thought distilled water was important in order to leave all gold out of solution. It would certainly be nice not to have to use it yet.


What plastic pieces are you talking about? Pieces of the green solder mask or pieces of circuit boards?

For getting the pieces of circuit boards you can use sieves with big holes, for example a bucket with drilled holes within a larger bucket.
Smaller flakes of the solder mask survives aqua regia and is easy to filter off after the gold is dissolved.

Any gold dissolved would either cement out on copper and end up as a fine sludge among the foils or staying in the solution. Either way, treating the waste as possible gold containing catches the gold. Treat the solid particles as possibly containing gold and keep it with the foils going to aqua regia will take care of the first possibility. And if some gold were dissolved with the copper chloride then it can be tested and detected. Recovering the copper by cementing on iron would cement out any gold with the copper. Melting the copper into anodes and parting it in a copper cell would leave any precious metals as a anode slime which could be refined further.

It all boils down to accepting that there will be losses and at some time you have to decide how much work you want to do to get that last part of gold out. It will differ from person to person.

I usually run a test batch of the waste material just to see if I can recover any more gold from the waste. It is also a good way to see how effective your process are.

I once ran a batch of black fiber CPU:s and I suspected that there was some gold dissolved in the solder on the lids I removed. I found some but it turned out to be a lot less than 0.1gin that batch. So for me, running lids from pentium black fibers doesn't pay. It's better just selling it as copper scrap and let the copper smelter have the gold as a bonus.

I have recovered a couple of kilos of copper from excess copper chloride solution, some day I will run it through a copper cell. Just for fun and to see if I can find some gold in it.

Göran


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## nickton (Jul 6, 2018)

Okay. I'm still grappling with some of these concepts and processes, but a lot does eventually make sense if I keep trying. I'm a bit confused for instance, about whether to use copper or iron to cement out base metals that I guess are "in solution" at the point where the ap leach is saturated. I had a stock pot for some time with a piece of angle iron in it, and it did seem to clear out the water pretty well, but left a pile (that I kept) , which looked mostly like rust. Now I would imagine one would not want any cemented copper to be contaminated with iron oxide, but I could be wrong. And how to separate the cemented mess into refined metals is also quite confusing to me. I 've been searching for topics on this but am not having much luck yet. 
I also don't quite understand what you mean by: 

" Melting copper into anodes and parting it into a copper cell would leave any precious metals as an anode slime which could be refined further."

I have done a sulphuric stripping cell so a have a bit of a clue.

Please excuse my lack of using the proper quote tool. Haven't figured that one out either. :mrgreen:


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## nickvc (Jul 6, 2018)

Nickton take your time all this will make sense if you keep reading but there is a lot to understand.
When Goran was referring to a copper cell, we have several if not more very good threads on the forum covering these, he meant that any copper you have cemented can be electolytically refined using a copper sulphate solution and a power supply so you recover pure copper and any values you missed will slough off the copper and be caught in the anode bag for further refining, it’s a good way to concentrate your values with little work.
By using iron to cement your old solutions you will cement all values and the copper and any other metals less reactive than itself, if you use copper to cement you should only have values cement but with e scrap there may well be a few other oddities that will also cement which is why you need to re refine the powders.


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