# I got a Piranha in a bucket...



## crow king (Mar 12, 2012)

My Acid/Peroxide that has dissolved 4 pounds of fingers and now has a bubbler in it has ATE a couple pounds of plastic housed gold plated pins. Within an hour the plastic had turned to a black sludge and had went into both the strainer bucket and lower bucket. I also had in the solution a missing 4 grams of dissolved gold I was waiting to recover after saturated with copper. Any idea on what I am facing with the plastic now going into the solution? CrowKing


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## 4metals (Mar 12, 2012)

When possible it is best to incinerate the plastic before going into solution but the plastic has not gone into solution in the true sense of dissolving. It may have softened and formed a thin film but you should be able to filter the solution and be left with dissolved metal in acid. 

Before wasting a lot of time, test the solution with stannous chloride to assure the solution has gold in it. You didn't say how much acid you used or how much oxidizer but 4 pounds is a lot of metal and it is possible you have cemented your gold out already. If so you can roast the residue and redissolve it in acid.


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## acpeacemaker (Mar 12, 2012)

From what I've seen its possible you used to much peroxide causing so much heat, in turn making your plastic sludge. I agree incenerate if possible. But what ratio was your acid/oxidizer?


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## crow king (Mar 12, 2012)

2 pounds 7oz of board ends is what we added to it last week, (not 4 pound as I mentioned earlier) they were stripped (or dissolved) by the next day, we only recovered 2.6grams from those foils, but this is our first attempt at any recovery. The A/P was made last week with 4000ml HCL and then 2000ml of Peroxide was added. An hour later an additional 1000ml of Peroxide was again added to the solution. In the video, Steve adds another cup the following day, we got this wrong and added too much, too quick. The bucket has had a bubbler running in it for the last 3 days and today the plastic housed pins were added. Took a look in it an hour later and discovered the black plastic sludge. So the gold in solution I was referring to was a guess at last weeks missing grams of weight.


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## Geo (Mar 12, 2012)

plasticized pvc will break down in concentrated hcl. did the solution turn black? if so, it is now useless as AP solution. in the future before attempting this kind of separation, test one of each type of connector you will be working with in warm hcl. if it gets mushy in a short time it will break down in AP. remember if the plastic bends before it breaks it may break down in hcl but if it breaks before it bends, it should be ok.


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## butcher (Mar 12, 2012)

What percentage of peroxide? If more than 3% it is possible you dissolved gold, and if you had un-dissolved copper metal in solution could precipitate it as powder in the plastic sludge, the advice of testing the solution for values with stannous chloride is important, let everything settle well, decant solution and filter, filter plastic sludge last, since it can have values in this plastic mud, incineration would be the best way to get back the values, but before doing so I would try another approach first, and it would depend on what else was in this mud, if elemental base metal I would try to get that dissolved without getting gold into solution HCl/3% H2O2 again letting every thing un-dissolved settle and decant, boiling hot washes to remove any lead, then heating the mud in HCl with small additions of sodium hypochlorite (bleach), to try and get the gold in solution settle decant solution, filter, filter and rinse plastic mud last, the remaining plastic can be neutralized with a dilute caustic soda wash and put into a plastic bucket with lid, used to hold materials that need incineration later (integrated chips, old filter papers, and so on).

Some types of plastic will hold up better than other types to these acidic solutions, it would be better to separate the metals from the plastic, or at least figure out which type of plastic breaks down easily and keep this type separated from the solution.


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## crow king (Mar 13, 2012)

Peroxide was 3%. Just had a look at it today, the plastic isn't as soft as yesterday, the plastic is still solid. Trying the bend/break test, on a new piece from a board, it snapped before bending. A stannous check showed purple particles all over the small piece of filter I used to check it with, however it didn't show a solid purple covering where the Stannous was applied, only the specks, that may be coming off the flash coated items. Is it possible that the plastic going soft at first killed the A/P and that is why it is no longer dissolving plastic, or could it be that the initial start of the reaction to this plastic I misidentified and it is okay? The solution was very dark before we added these plastic components in, It had a slight yellow, more green hue and now I can't tell if it has darkened or not. Is there a way to check PH of my solution that can tell me if my acid is still doing its job?


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## Geo (Mar 13, 2012)

i use pool test strips to test PH. i'm not a chemist so i cant explain why it does what it does, but from experience, if you have a lot of plastic dissolved in the AP it stops dissolving copper. its kind of like the plastic creates a kind of barrier in the solution that prohibits the reaction. even if the solution is acidic it wont break the copper down or at least its so slow it seems to have stopped working. i would filter whats in it and add the solution to the stock pot and incinerate everything ( filters,solids and the sludge) and start over with fresh acid.


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## butcher (Mar 13, 2012)

crow king,
The plastic should not change the acid content, although the metals will make salts out of the acid, dissolved metal salts, and un-dissolved metal salt, this will lower acid content in solution, if only copper was involved the copper II Chloride salt (CuCl2) would stay in solution, copper I chloride salt (CuCl) would precipitate as a white powder, usually when the solution gets very dark almost black when acid has lower free acid content in solution, I believe this black/green solution is caused some (CuCl) still in solution not precipitated as white salt yet, also the acidity and the oxidizer is low in this dark solution, adding some HCl to the dark solution and also some oxidizer (air or 3% H2O2) will revive the dark solution back into a light green copper II Chloride, with free HCl in solution, and oxidizer, ready to dissolve more copper metals, I have never been concerned with pH.

Studying the document Laser Steve provides on his web site explains the theory of how this leach works, understanding the process and what happens in solution's helps you understand how to use the solution to your advantage.

If the plastic did not make a goop, I would not try and dissolve gold from it with the HCl/Bleach, as I suggested above, if the plastic is hard (or just soft solid), just rinse powders from the plastic, as the HCl/ Bleach is strong and may melt the plastic more, also if the plastic is solid just rinsing should wash off any gold powders, for kicks you could always add a drop or two of stannous on the plastic to see if you get a violet color of gold, if the plastic did not dissolve to a goop or have gold locked up in them , there is no reason to save and incinerate it.



Also keep in mind tin in solution will make gold colloids, that will not precipitate, and the stannous chloride test will not detect (gold is already reduced to metals), tin also makes solution very hard to filter, keeping tin out of your solution's you will avoid many head aches and avoid losses of gold.


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## dtectr (Mar 13, 2012)

What butcher said. (BTW - congrats to the new mod).
From your description, which lacks a few details - not complaining, just saying. You have a setup VERY heavy with oxidizers - you could be getting a stannous result similar to excess nitric/Cl - the reading redissolving almost before its read, you know what I mean. 
AND/OR the sludge is your gold. 
Also, do you know the manufacturer and part number of the connectors? If so, google them and try to find a datasheet for them - facts beats guessing every time. 
Just my dos centavos 
Dtectr


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