# What's hot or not in a Crockpot?



## Astraveller (Dec 30, 2009)

Happy New Years to all,

Santa brought me a slow cooker ( http://direct.tesco.com/product/images/?R=100-2168 ) this Christmas and I am anxious to try out the Crockpot method when I get back to the workshop but I have a few questions, the answers to which could save me a lot of time.

I would like you know that I have scoured the archives for the last few days for the answers and either couldn’t find them or would appreciate clarification. 

Thanks in advance and here we go:-

1. Hcl only yes? But which concentration is best 30% or 18%? I realise that this might seem a silly question but when I was discovering the AP process I experimented with both and found the lower concentration seemed to work the best in that situation, counter intuitive at the time but later explained by Steve and Palladium.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=4249&p=36665#p36665

2. I realise the process will dissolve base metals leaving the gold (a good thing!) but what else will it dissolve and what should be avoided? Eg. Can I put nickel plated pin in the mix? Is solder a problem? Iron/steel? What about aluminum? (I think I know the answer to that one : ) Pc board?

3. We have a lot of gold pins – connectors – still in their plastic holders from the mother boards, the ones that connect to hard drives and cd drives etc., what would be the effect of putting these in whole?

4. It has been a long time since my last post (forgive me father  and at the time we were experimenting with removing solder mask from gold plated boards. I have found a way of doing it that I feel comfortable and safe with and we now have a sack of clean gold plated pc boards to process. Which process would be the best, Crockpot or AP bearing in mind that the boards do still have very small amounts of solder on them?

5. When a batch is done, what is the best way to filter, clean and process the results ready for the hcl-cl / AR step?

If there is a simple/idiots guide to using a Crockpot on the forum that I have missed, maybe someone could point me in the right direction or maybe we can turn this post into it.

TIA.


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## lazersteve (Dec 30, 2009)

Check out this thread and post any questions you have:

Crockpot

Clean foils are easily digested in HCl-Cl.

Steve


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## Astraveller (Dec 30, 2009)

Steve,

Thank you for being the first to answer, your posts are always timely and hugely welcome and always bring gravitas. And it’s nice to be back in the game.

I have spent the holidays reading Hoke and studying the forum. I have read and downloaded this thread and read it again and again and now have read it again because you have suggested I do so but it doesn’t answer the questions I asked.

It would be great to throw a load of pc boards into an Hcl Crockpot and then separate and process the results but I know it’s not going to happen that way. What can I realistically use a Crockpot for? And what should I avoid?

In return I will tell you the story about my recent visit to 'Anner the Stripper' (SFW) and what I learned!! (On topic)

Linton.


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## butcher (Dec 31, 2009)

Astraveller, I will not give you an answer but some things to consider.
some plastics will break down in chloride, I have done the pins in plastic in HCL/ peroxide not heated, some types of plastic start breaking down, most of the plastic has no effect, when I do a batch I remove the type that start to soften, and process seperately,they usualy look alike or are same color plastic.
here inceneration of powders and filtered material works wonders,
you wont need crock pot for these.

as far as solder, lead is insoluble in chlorides, it will be a white or grayish powder, it can be some what seperated because of the fact that cold lead choride is insoluble in water, and slightly soluble in boiling hot water, this sounds easy the fact is it will cause a whole lot of work to get the lead seperated, and seperating it completely seems almost impossible, it can be done, but if you can eliminate the most you can before you will save yourself much work.
the tin will disolve in chloride solution, but keep it away from nitric(unfilterable slime forms), HCl soak and a brush will break down the tin in the solder, the lead forms a crust as lead oxidizes and passivates, this crust can be brushed away, and soak and repeat,
Non heated HCl, without oxidizers if I was just after the solder.
HCl/H2O2 will also break down solder but it also disolves copper so you will end up with the lead in your gold and other insolubles, this pain in the rear is best avoided.

I would work with acid peroxide for the cleaned gold plated boards, 

now lets look at chloride solution in your crock pot, HCl is a chlorine and water, this as with other acids has an certain azeotrope with water.
a point of maximum concentration, and a boiling point were chlorine gases out of it when heated, and since HCl @30 percent is at about this azeotrope heating it is gassing the chlorine out of it, but if water added you will be mostly evaporating water and very little chlorine with heat, this would let the chlorine make metal chlorides in solution instead of wasted as unused gas, so if I was using it in crock pot, I would add water diluting it and as the water boils out, if I smell alot of chlorine I would dilute again, unless my goal is to boil off chlorine, now remember this also chlorine gas and water make HCl acid, as a metal is disolved by HCl the hydrogen is displaced and the metal disolved makes a chloride salt of that metal with chlorine in the solution, and if you boiled out your chlorine from solution you are wasting the gas and also it picks up moisture from the air and make HCl again, but its not in yer pot.
crock pot is great tool.


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## Irons (Dec 31, 2009)

butcher said:


> Astraveller, I will not give you an answer but some things to consider.
> some plastics will break down in chloride, I have done the pins in plastic in HCL/ peroxide not heated, some types of plastic start breaking down, most of the plastic has no effect, when I do a batch I remove the type that start to soften, and process seperately,they usualy look alike or are same color plastic.
> here inceneration of powders and filtered material works wonders,
> you wont need crock pot for these.
> ...



One correction: HCL and Cl are 2 different animals. HCl gas and Water make Hydrochloric acid. Chlorine and Water make Chlorine Water.
The vapor pressure of HCl is a function of temperature and concentration, so except at very low concentration in Water, and or at a low temperature, HCl will have a positive vapor pressure and will evaporate.

HCl vapor is very corrosive and will attack even Stainless Steel. If the siding begins to fall off of your workshop, you will probably find that HCl attacking the nails was the culprit.
Personally, I would use the crockpot as a heating mantle and keep the HCl confined, with a refluxer to recover the gas and keep it from causing problems elsewhere.


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## viktor1984 (May 10, 2010)

how about silver does in dissovle also along with the base metals in just the HCL ALONE in crockpot? while dissolving computer stuff


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## Harold_V (May 10, 2010)

viktor1984 said:


> how about silver does in dissovle also along with the base metals in just the HCL ALONE in crockpot? while dissolving computer stuff


For all practical purposes, silver is _not_ soluble in HCl.

Harold


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## viktor1984 (May 18, 2010)

i dissolved half of 6Q crockpot full of motheroard pins with plastics on them. now all the pins are dissolved and there is dark/black/grey powder on the bottom.
so where to i go from here to try to get to the gold?


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## Barren Realms 007 (May 18, 2010)

viktor1984 said:


> i dissolved half of 6Q crockpot full of motheroard pins with plastics on them. now all the pins are dissolved and there is dark/black/grey powder on the bottom.
> so where to i go from here to try to get to the gold?



I am going to assume that you used HCL or HCL/peroxide to disolve your base metals. Try and filter out your platics and then wash with HCL till you no longer get a color change and then wash with water 3 times and then repeat with the HCL 3 times and see what you have.

In a glass coffee pot on a hot plate would work best so you could see if there were any color change.


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## viktor1984 (May 18, 2010)

sweet gonna try it now thanks for fast reply


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