# cementing the stock pot



## glondor (May 25, 2011)

I have about 30 gallons of solution in a drum from all of my adventures. (all hcl solutions no nitric in this stockpot)
I want to cement out any residual values.
I hung a 3 foot piece of 2 inch copper pipe in the solution last week.
The pipe is gone. Dissolved.

I am trying to understand the situation.

Question. Does the fact that the pipe fully dissolved mean that an equal amount of lower metals on the electromotive series have been pushed out of solution?

OR does it mean all lower metals were pushed out of solution and the pipe continues to dissolve even though all lower metals are pushed out.

OR does it mean that since it is fully dissolved, MORE copper needs to be added to push more metal out of solution.

Since the pipe was about 3 pounds I suspect that all lower metals are out and the pipe continues to dissolve anyway. If this is not the case I will be in for a good payday!

I am going to the shop to decant the solution, but I sure could use some guidance on this. ( I did review Hoke but I could not make it apply to this situation) Thanks Mike


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## Harold_V (May 25, 2011)

Using copper in a solution that does not test positive for values makes no sense. 

I feel you do not understand the intent of the stock pot. I can think of NO reason to apply copper unless the solution tests positive. Otherwise you can expect the loss of copper, just as you'd expect any metal to dissolve in the presence of acids. 

Simply stated, the stock pot is used to recover traces of values that may not be recoverable by other means, or that are so dilute that conventional methods don't yield expected results (very common with the platinum group). Scrap steel is generally used, although if one hopes to eliminate copper recovery, then (and only then) the use of copper is advised. 

If you have solutions that test barren of values, scrap steel is the metal of choice. It removes dissolved copper, which should never be discharged to a drain system. 

Harold


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## glondor (May 25, 2011)

Thanks for your reply Harold. My apologies as I always try to qualify my posts properly. I did not disclose (by mistake) that the Stanous test on the solution was faint but positive. Purple on a Q tip. After the application of the copper pipe (now) the stanous test is brown at first changing to green after an hour or so. The cemented material is almost to fine to filter and does not settle.Iwill attempt again with a charmin plug.


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## Lino1406 (May 27, 2011)

Experiments should be done on samples.
A copper strip in said solution will reveal
if a nobler metal is present, by changing
the color in a definite form.


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## glondor (May 27, 2011)

I should finish this by the end of today. Lots of precipitate via charmin plug. About 5 more gallons to filter. We shall see what happens. It's my first real attempt at the stock pot. I am still making mistakes, but they are getting fewer.

Thanks for the information guys. Every step is a learning experience.


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## Harold_V (May 27, 2011)

glondor said:


> I should finish this by the end of today. Lots of precipitate via charmin plug. About 5 more gallons to filter. We shall see what happens. It's my first real attempt at the stock pot. I am still making mistakes, but they are getting fewer.
> 
> Thanks for the information guys. Every step is a learning experience.


Filtering isn't required. If you have used a stock pot as it is intended, the resulting solution tends to be quick to settle. Filtration would apply only to the remaining solids, if even that. It's possible they would be washed in hot HCl after cementation, so there is no need to filter. 

When dealing with large volumes of solution, you are well served to allow gravity to do the work for you. It requires no attention on your behalf, and does an excellent job. The only exception that may come to mind is if you have colloidal particles in suspension, but even filtration will not deal with that circumstance with satisfaction. 

Harold


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## glondor (May 27, 2011)

Thanks Harold. I must be honest and tell that I did expect a nice precipitate at the bottom of the barrel when I siphoned the liquid off. It was not there so I assumed I was too aggressive with the siphoning and had somehow vacuumed it off the bottom. That is why I took the filter approach. I am getting a filtrate, I am guessing 6 to 8 grams by looking at the little pile in the funnel. I will wash it tomorrow with HCL and see if there is any thing left. Maybe I am chasing a ghost. I have always felt my returns were sub par so I was hoping for a nice return on this pot. We shall see. Thanks for helping me along. How would I know if I had colloidal gold in suspension? Is there a test? Just curious.


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## butcher (May 27, 2011)

from reading how you were dissolving copper so easily and the stock pot could possibly dissolve more, my thought is solution could still have alot of oxidizer in solution, if so stannous tests may redissolve. I would take a sample of solution evaporate off any possible oxidizers and test it again.


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## Harold_V (May 27, 2011)

glondor said:


> How would I know if I had colloidal gold in suspension? Is there a test? Just curious.


My limited experience dictates that when you have colloidal gold present, the solution will have a general purple/pink cast, the color being determined by the amount in suspension. Correct me if I'm wrong, but the purple reaction one gets with stannous chloride is the result of gold being precipitated as a colloid. It is so finely divided that it likely wouldn't settle in many days, although I expect that it ultimately would hit bottom. You see evidence of gold that borders on being colloidal when you precipitate from quite dilute solutions---where it takes hours for the stratified gold to hit bottom. In this case, it's still brown or golden in color, because the particles are large enough to reflect the true color of gold. That's not true of colloidal gold. 

To get an idea of what it looks like, look through a piece of gold foil. It looks purple, not golden, being only a few atoms thick. 

Harold


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## glondor (May 28, 2011)

Excellent point Butcher. I will do that. Would taking a sample, diluting it with water and bringing it to a low boil to evaporate to half the original sample work for this?


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## Harold_V (May 28, 2011)

glondor said:


> Excellent point Butcher. I will do that. Would taking a sample, diluting it with water and bringing it to a low boil to evaporate to half the original sample work for this?


Adding water is the wrong thing to do. What you should be attempting to do is evaporate the solution to the point where any free nitric that may be present can be evaporated. To do that, in spite of the fact that you likely have no values in solution, evaporation should not be conducted at a boiling temperature. That insures there are no losses should there inadvertently be values present. 

What I'd recommend in a case such as this is to take a dip sample, which can be evaporated quickly. It will be representative of the entire lot, assuming you have stirred before the sample is taken. Evaporate a few drops to a thick syrup, then add a drop of HCl to insure that any residual nitric is evaporated. If no brown fumes are detected, you can safely assume you are free of nitric, and the resulting solution can be tested. The real benefit here, aside from insuring that nitric is gone, is that you will have concentrated the solution, so testing will be enhanced. Minute traces of vales will display much bolder than they would have with the dilute solution. If your sample tests barren, you know you need not spend any time on the large body of liquid. 

Harold


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## glondor (May 28, 2011)

Here is a dry sample of the stock pot on a spot plate. I believe I do see some purple. Sorry the pics look like crap.


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## butcher (May 28, 2011)

Where I am I cannot see the picture, so cannot comment there.

heat and acid can help to break the colloids.


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## Harold_V (May 29, 2011)

There does appear to be a slight stain in the right cavity---which would suggest the presence of gold. 

If you have any ferrous sulfate, a second test can be very revealing. Place a drop of solution in a cavity, then a small crystal of ferrous sulfate. Any gold present will be precipitated by the ferrous sulfate crystal. If there's enough gold present, it may form a leaf of gold. Stir the drop with a glass rod, observing if you see any dark particles forming. When the ferrous sulfate has been totally dissolved, follow up with a drop of stannous chloride. If gold is the source of the dark reaction, the test will reveal a barren solution. Proof positive that you have gold in solution. 

Harold


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## glondor (May 30, 2011)

I will continue looking for some cheap copperas. I may try a finer filter for now. I will stir thoroughly and filter a gallon and see what I get. My A/R from the filtrate looks good. Super purple on the spot plate. I will drop and wash today.


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## butcher (Jun 4, 2011)

Ferrous sulfate is so easy to make Iron in dilute sulfuric acid.


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## glondor (Jun 4, 2011)

Thanks Butcher. Is there any more to the process than that? Sounds easy.


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## butcher (Jun 4, 2011)

Old transformers the laminates are soft Iron, I do not use steel, after removing copper from transformer I grind off welds, separate laminates and torch them to remove oils and shellac, then cut them with tin snips, sulfuric is diluted to about 10%, heating speeds reaction but Iron will dissolve without heat takes longer, the green ferrous sulfate is filtered, and can be concentrated or evaporated to crystals, if crystals keep slight acidic, you want nice green crystals, keep from air, If I make crystals I leave them with some concentrated acidic solution, and little piece of Iron metal in air tight jar, if these good green crystals get oxidized in air they will turn brown, which will not work for precipitating gold.

Have also made it with sodium bi sulfate the salt left over from making nitric acid, it acts like sulfuric acid in the chemical reaction with Iron.


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## glondor (Jun 5, 2011)

Cool. Thanks butcher. I will add this to my list of things to do. Do you use them wet from your acid jar for precipitation? I guess it does not matter much as ...Nevermind, I answered my own question.


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## lazersteve (Jun 18, 2011)

If your stock pot solution is hungry for more copper why not use it to dissolve more base metals from gold plated scrap? Place the copper based scrap in an acid proof bag or cloth and allow the solution to dissolve more metal while making more gold foils at the same time.

Steve


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## Harold_V (Jun 19, 2011)

lazersteve said:


> If your stock pot solution is hungry for more copper why not use it to dissolve more base metals from gold plated scrap? Place the copper based scrap in an acid proof bag or cloth and allow the solution to dissolve more metal while making more gold foils at the same time.
> 
> Steve


Pretty hard to find anything wrong with that logic!

Harold


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## glondor (Jun 19, 2011)

You are correct Sir.


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## saadat68 (Nov 23, 2018)

Harold_V said:


> Using copper in a solution that does not test positive for values makes no sense.
> 
> I feel you do not understand the intent of the stock pot. I can think of NO reason to apply copper unless the solution tests positive. Otherwise you can expect the loss of copper, just as you'd expect any metal to dissolve in the presence of acids.
> 
> ...



Hi my thought was we must add any of waste solution that touch gold, silver or pgms to stock pot
According to this post I have 2 question
1- Assume we have some waste solution from gold refining process. We test it with stannous chloride and the test is negative for gold and pgms . So do you transfer this solution to copper stock pot or iron stock pot?


And about Silver
2- If we have some nitrate solution without any gold and pgms, do we must test it with some hcl and if the test was positive transfer it to copper stock pot? I don't think hcl testing detect few traces of silver nitrate in solution

Thanks


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## saadat68 (Nov 23, 2018)

Is these true?
Transfer waste solution from silver cementation to copper stock pot ( don't need a test )

Test waste solution from silver chloride process and if test was negative for silver transfer it to iron stock pot 

Test waste solutions with stannous chloride and if test was positive transfer solutions to copper stock pot and if test was negative transfer them to iron stock pot


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