The Stock Pot

[4metals]

I then add an aquarium bubbler like in the ap process to keep the solution agitated and after a couple of days i decant the solution and move it to another bucket. This is where i add steel and drop the copper that i will use for the stock pot cementing and when the process is done then the solution is ready for disposal in the next step.

This is essentially the process used for waste treatment which has been discussed on the forum. With the exception that the pH need be increased to 2.5 before adding the iron.

I have never used a stock pot per se. If I processed a lot for gold and the lot had payable platinum I would always zinc the entire lot, add HCl to get rid of the excess zinc, roast the sludge and process the sludge accordingly. This saved me the time of evaporating the solution down as I was able to keep the volume of the solution used to digest sludges down to a minimum so the Pt (and Pd) was concentrated enough to drop easily. Another benefit of this procedure is the metals you recover from the sludges are finely divided and will dissolve in HCl and sodium chlorate so there is no need to get rid of any excess nitric. The waste from this process went into the standard flow for aqua regia waste.

All solutions that had been precipitated were placed into a cementation tank and all waste acids were cemented with copper. This essentially was my stock pot. The solution from there went to the next tank for the pH increase and the iron to recover the copper. The copper recovered was dried and melted and cast in an anode mold to be used in the cementation tank.

The waste was now essentially ferric chloride so it was easy to drop out the iron as a hydroxide and neutralize the waste for discharge. The classic metal hydroxide method involves raising to a pH of 10 to drop all of the metals as hydroxides and then it has to come back down (by acid additions) to neutral for discharge. This method eliminates that step because the iron comes out around pH 3 to 3.5 and after filtration to remove the iron cake the solution only needs additional alkaline to get to discharge pH. Back when I did this the waste met discharge standards, today it would likely need some carbon polishing. Often refiners use this process to clean up their waste and have the "process water" removed for a fraction of the cost it would cost for the waste acid removal and it is removed as a non-hazardous waste.

 

[kadriver]

I got a smaller bucket and began using this as #1 of 2 stock pots. In the smaller #1 I will use copper to cement out trace amounts of gold and PGMs. Then I'll transfer the resulting copper solution to the larger iron stock pot #2 to cement copper onto iron for use in stock pot number one.

I hope I got this right. I used bits and pieces of copper wire instead of powdered copper.

kadriver

 

[MarcoP]

All solutions that had been precipitated were placed into a cementation tank and all waste acids were cemented with copper. This essentially was my stock pot. The solution from there went to the next tank for the pH increase and the iron to recover the copper. The copper recovered was dried and melted and cast in an anode mold to be used in the cementation tank.

The waste was now essentially ferric chloride so it was easy to drop out the iron as a hydroxide and neutralize the waste for discharge. The classic metal hydroxide method involves raising to a pH of 10 to drop all of the metals as hydroxides and then it has to come back down (by acid additions) to neutral for discharge. This method eliminates that step because the iron comes out around pH 3 to 3.5 and after filtration to remove the iron cake the solution only needs additional alkaline to get to discharge pH. Back when I did this the waste met discharge standards, today it would likely need some carbon polishing. Often refiners use this process to clean up their waste and have the "process water" removed for a fraction of the cost it would cost for the waste acid removal and it is removed as a non-hazardous waste.

So raise PH to 2-2.5 before adding scrap iron and then when at 3-3.5 the iron will come out by it self?
Sure other metals hydroxides and carbonates will drop at 9, but still great to know (unless I misunderstood).

 

[butcher]

Here is one chart showing the pH range some metals precipitate around.
http://hoffland.net/treatment-processes-chemistry-2/hydroxide-precipitation/

Note: Some metals are amphoteric and will precipitate in a basic solution and dissolve again in an excess of that same basic compound.
http://www.docbrown.info/page07/appendixtrans12.htm

http://cpe.njit.edu/dlnotes/CHE685/Cls06-2.pdf

more for further research,
https://www.google.com/search?newwindow=1&site=&source=hp&q=metal+hydroxide+precipitation+chart&oq=metal+hydroxide+precipitation+chart&gs_l=hp.13..0i22i30.2331.18279.0.20590.36.30.0.6.6.0.314.3477.16j12j1j1.30.0....0...1c.1.54.hp..1.35.3380.0.LXh8Xi7d-iw

 

[Silver Sliver]

Here is one chart showing the pH range some metals precipitate around.
http://hoffland.net/treatment-processes-chemistry-2/hydroxide-precipitation/

Note: Some metals are amphoteric and will precipitate in a basic solution and dissolve again in an excess of that same basic compound.
http://www.docbrown.info/page07/appendixtrans12.htm

http://cpe.njit.edu/dlnotes/CHE685/Cls06-2.pdf

more for further research,
https://www.google.com/search?newwindow=1&site=&source=hp&q=metal+hydroxide+precipitation+chart&oq=metal+hydroxide+precipitation+chart&gs_l=hp.13..0i22i30.2331.18279.0.20590.36.30.0.6.6.0.314.3477.16j12j1j1.30.0....0...1c.1.54.hp..1.35.3380.0.LXh8Xi7d-iw

Some really good information here, thank you Sir!

 

[MarcoP]

That answer many questions, new questions that would eventually come up and I even found unexpected information! I'm sure one day I would have searched about it, but you Sir just made my day and gave new keywords to look up for.
Thank you butcher!

 

[kurtak]

1 gallon & 2 gallon cookie jars from Walmart make great stock pots - unlike plastic buckets they don't become impregnated with metals you are trying to recover (as Harold talked about) metals may stick to the walls but you can just wipe the walls down with a paper towel & add the paper towel to your filter burn bucket for later recovery when incinerating your filters

I have been using them since I started doing this & really like them for this purpose

Kurt

 

[Platdigger]

Good stuff Butcher!

 

[4metals]

Kurt,

The stock pots are nice but I really like the silver cell! No refiners workbench would be complete without a little gem like that!

What volume does it hold and how many amps do you pull?

 

[Shark]

1 gallon & 2 gallon cookie jars from Walmart make great stock pots - unlike plastic buckets they don't become impregnated with metals you are trying to recover (as Harold talked about) metals may stick to the walls but you can just wipe the walls down with a paper towel & add the paper towel to your filter burn bucket for later recovery when incinerating your filters

I have been using them since I started doing this & really like them for this purpose

Kurt

I just had one of those real "DUH" moments. I have no idea why I haven't already thought of it, as I have one of those cookie jars needing a good use.

 

[GotTheBug]

I use those wally world jars a lot also, and learned a valuable (or shall I say values lost) lesson about using them with any heat....

 

[kurtak]

Kurt,

The stock pots are nice but I really like the silver cell! No refiners workbench would be complete without a little gem like that!

What volume does it hold and how many amps do you pull?

I'm running a BK Precision 10 volt/10 amp linier power supply - the cell takes 4 liters electrolyte to the bottom of the anode basket & the anode basket holds 3 two pound anode bars (so 6 lb silver) & it can pull the full 10 amps continual for as long as I need (I can "set" the current limit so I actually set it at 9.8 which it will pull once the cell is about half full of crystals)

It was kind of a spendy power supply (about $500) but the first one I bought was one of those cheep made in China $100 one's from ebay & I burned it up in no time - this one is near indestructible - well worth the money

At the time I bought it 10 amps was enough but I am getting to a point where I run enough silver that I am considering getting a 20 amp & maybe even a 30 amp - but they run 2 to 3 times the money & with silver down so low right now its hard to justify - so for right now I will just keep running this one - its built to take the heat of running non-stop for days

Kurt

 

[kurtak]

I use those wally world jars a lot also, and learned a valuable (or shall I say values lost) lesson about using them with any heat....

They will actually take a fair amount of heat you just have to be "careful" you don't thermal "shock" them or apply direct heat (put them directly on a hot plate)

I have done "a lot" of silver chloride conversion in them (& they get quit hot when you add the NaOH) as well as using them for silver cementing & stockpot cementing & in 4 years have "never" had one brake --- I "always" put them in a shallow plastic tote/bin for secondary containment just in case & that was only needed one time when I added to much NaOH to fast to a Ag/CL conversion & had a boil over - never broke one though

So I am kind of curious as to what you did to have one brake ?

Kurt

 

[Harold_V]

I use those wally world jars a lot also, and learned a valuable (or shall I say values lost) lesson about using them with any heat....

Or with heavy pieces of scrap metal. The jars are nice, but subject to breakage. That's the reason I used an ice cream bucket. Never had one fail in all my years of refining, but I can't count the number of broken glass vessels I experienced.

Harold

 

[Palladium]

I use those wally world jars a lot also, and learned a valuable (or shall I say values lost) lesson about using them with any heat....

Or with heavy pieces of scrap metal. The jars are nice, but subject to breakage. That's the reason I used an ice cream bucket. Never had one fail in all my years of refining, but I can't count the number of broken glass vessels I experienced.

Harold

+ 1

The only thing i really use glass for is the final refining of gold. Everything else is stainless and plastic.
I'm the paranoid type! :mrgreen:

 

[rickbb]

I use those wally world jars a lot also, and learned a valuable (or shall I say values lost) lesson about using them with any heat....

Or with heavy pieces of scrap metal. The jars are nice, but subject to breakage. That's the reason I used an ice cream bucket. Never had one fail in all my years of refining, but I can't count the number of broken glass vessels I experienced.

Harold

+ 1

The only thing i really use glass for is the final refining of gold. Everything else is stainless and plastic.
I'm the paranoid type! :mrgreen:

I'm not the paranoid type, just clumsy. Glass just doesn't last long around me. sigh.

 

[kadriver]

This is where i add steel and drop the copper that i will use for the stock pot cementing and when the process is done then the solution is ready for disposal in the next step. I keep separate buckets for gold and silver solutions and i don't mix them.

Palladium,

I am getting quite a buildup of copper in my 2nd bucket that is charged with iron.

Do you just add the bits of copper back into your stock pots, or do you melt into ingots first?

Thanks, kadriver

 

[Palladium]

I guess you could do both, but to me melting only takes away surface area and cost extra time and money. I just add the copper powder to my waste disposal bucket after removing it from my cementing bucket without washing it or anything. Waste bucket to waste bucket is all i do. If you just cement without air agitation then the powder will give you more reaction surface than a bar does. If you use a bar i would use air agitation. Don't fill the whole bottom of the bucket with copper or it will crust up into a clump. Use moderate amounts and every time you empty your bucket check to see you have excess copper in the bottom. Using copper in your stock pot it will not consume near as much copper to drop the precious metals as with iron because iron with replace everything above it where as copper won't. The end result should be a cleaner stock pot which is easier to process.

 

[jason_recliner]

I guess you could do both, but to me melting only takes away surface area and cost extra time and money. I just add the copper powder to my waste disposal bucket after removing it from my cementing bucket without washing it or anything. Waste bucket to waste bucket is all i do. If you just cement without air agitation then the powder will give you more reaction surface than a bar does. If you use a bar i would use air agitation. Don't fill the whole bottom of the bucket with copper or it will crust up into a clump. Use moderate amounts and every time you empty your bucket check to see you have excess copper in the bottom. Using copper in your stock pot it will not consume near as much copper to drop the precious metals as with iron because iron with replace everything above it where as copper won't. The end result should be a cleaner stock pot which is easier to process.

This is something that has been perplexing me this week, as I am still tidying up my first mistakes, a year on.

I have a small jar containing a 1kg solid block of copper, in which potentially gold bearing (amongst other things) solution sits for a week or three. I guess that's my stock pot. Then I gently syringe off the almost black solution into a 1l waste jar containing iron. Originally that iron was sandblasting grit but it reacts too quickly, causing foam and heat. Instead, now I drop in a dozen or so rusty nails.

So now I have a slowly clearing pale green/blue solution in the waste jar with a good inch or so of copper precipitate.

If I understand correctly, you're saying that you use this powder from waste bucket back into the stock pot. I am having trouble comprehending the method of reusing copper for the stock pot in powdered form.
The idea of the stock pot, as I understand it, is to recover gold powder. If I add copper powder from the waste jar to the stock pot, gold will precipitate but that gold still needs to be separated from the copper - all over again. That sounds like a circular flow to me. If it were melted into a bar, for which I don't yet have the facilities anyway, it would be much cleaner, though slower?

Also, a minor point, how would I know when it's consumed? I can't just lift and check it like a solid bar.

 

[kadriver]

If I understand correctly, you're saying that you use this powder from waste bucket back into the stock pot. I am having trouble comprehending the method of reusing copper for the stock pot in powdered form.
The idea of the stock pot, as I understand it, is to recover gold powder. If I add copper powder from the waste jar to the stock pot, gold will precipitate but that gold still needs to be separated from the copper - all over again. That sounds like a circular flow to me. If it were melted into a bar, for which I don't yet have the facilities anyway, it would be much cleaner, though slower?

Also, a minor point, how would I know when it's consumed? I can't just lift and check it like a solid bar.

I am just getting a handle on stock pot usage and terminology. Palladium says he uses TWO stock pots; one for silver wastes, and another for gold wastes. In his writing above, he transfers the copper from waste bucket to waste bucket. I have one stock pot that has lots of copper in it. I have a second bucket that has lots of iron in it (I am using angle iron, eight 12 inch pieces) and then a waste treatment bucket used to precipitate out the dissolved iron with sodium hydroxide (50LB bucket from Duda Diesel for $100 deliver via ebay).

I have been adding my gold and silver wastes to my stock pot that is loaded with copper. But I am switching to two stock pots like Palladium, one for gold wastes and another for silver, both will contain copper. I don't use a bubbler yet, I give it a good stirr several times a day, but I plan to start using one. When I feel comfortable to do so, I allow the stock pot to settle over night. I then siphon off the blue to blue green liquid (I use ferrous sulfate and SMB as gold precipitants so there is iron in solution in my stock pot) into the second bucket that contains lots of pieces of angle iron. I stir this bucket at the same rate as my stock pot. This bucket eats iron pretty fast and the copper is building up in it. After I feel comfortable, I siphon the liquid from the iron bucket into a waste treatment bucket and process this liquid with sodium hydroxide.

I guess I am a little confused by the terms "waste bucket to waste bucket". I envision this to mean that the copper cemented out in the bucket that contains iron is transferred BACK to the stock pot for use to cement out traces of gold and PGMs. This makes sense because the acidic solution in the stock pot will consume copper as it cements out the PMs relieving me from having to add valuable pure copper to the stock pot. The copper is user OVER AND OVER in this way.

Plus if I siphon off any PMs still in solution FROM my stock to my second bucket that is loaded with iron, the PMs will cement out and settle with the cemented copper as the angle iron goes into solution. These PMs will get placed BACK into the stock pot when I transfer the copper out of the angle iron bucket back to the stock pot.

This is how I understand the stock pot to function from where my knowledge is at this writing. Since I have picked up a jeweler as a customer I am seeing an increase in PGMs (although only in traces amounts) and my waste production has increased dramatically also.

As a side note, I am planning on waiting as long as possible before I try to refine the PMs in my stock pot. I am going for the Harold_V retirement plan.

A note to jason_recliner, if you look at what I have written you will see that the copper gets recycled so you don't have to continually add virgin pure copper to the stock pot. And you get a second chance to get any PMs that are (inadvertently, accidentally, ignorantly) siphoned out of the stock pot and into the bucket with iron in it.

If I am in error here then any guidance would be greatly appreciated.

kadriver aka sreetips