The Stock Pot

[jason_recliner]

One distinction I would like to clarify is the term "waste", and it seems to be a sticking point of confusion with more people than just myself.
In my current understanding, waste is not the solution that goes into a stock pot, rather that which comes out of it.

Only solutions with values, or probable values, go into the stock pot.
The copper enriched solution that comes OUT of the stock pot, HCl washings after incineration (unless reused for other purposes), expired stannous chloride, et al. I consider these are waste. "Waste' is to ultimately have all metals removed (whether by Cu, Fe individually or by all metals simultaneously is not my point here) and the resulting clean salt water dumped.

Even then, there may be good reasons to put certain waste items into the stock pot. HCl washings for example, may help keep a nice low pH. But you would never include your old stannous chloride - for we all know tin in your gold is just evil. :twisted:

So this was my comprehension of what Palladium does, as he mentioned "cementing bucket" and "waste disposal bucket". Therefore I believe "Waste bucket to waste bucket" just means "bucket to bucket".

Palladium says he uses TWO stock pots; one for silver wastes, and another for gold wastes.

It makes good sense to have one for as many different items as you regularly process individually. I'm merely simplifying, to speak of one at a time.

For any given stock pot, adding copper powder would mean it's partially or wholly replaced by gold powder. You would have a Cu/Au powder mix. I guess this is still pretty easy to re-process, but you'd be having to redissolve the copper all over again as opposed to extracting only small amounts of non-values if you used busbar or ingot. On the other hand, ingots mean work and busbars mean expense.

 

[MarcoP]

As a side note, why aren't you using calcium hydroxide for waste treatments? It's easy cheaper then sodium hydroxide and little easy to filter off. I can buy 25Kg locally at €3-€3.50.

 

[kurtak]

As a side note, why aren't you using calcium hydroxide for waste treatments? It's easy cheaper then sodium hydroxide and little easy to filter off. I can buy 25Kg locally at €3-€3.50.

Correct - calcium hydroxide (lime) is the better way to go for removing the iron after using iron to remove the metals below it in the reactive series - its cheaper & easier to filter - the down side is it takes longer to react & drop the iron out then NaOH --- if the solution is to dilute &/or temps to cool it can take a few days for calcium hydroxide to do its job - where as NaOH gets the job done in dilute solutions &/or cool temps

So I use both - depending on conditions

Kurt

 

[MarcoP]

As a side note, why aren't you using calcium hydroxide for waste treatments? It's easy cheaper then sodium hydroxide and little easy to filter off. I can buy 25Kg locally at €3-€3.50.

Correct - calcium hydroxide (lime) is the better way to go for removing the iron after using iron to remove the metals below it in the reactive series - its cheaper & easier to filter - the down side is it takes longer to react & drop the iron out then NaOH --- if the solution is to dilute &/or temps to cool it can take a few days for calcium hydroxide to do its job - where as NaOH gets the job done in dilute solutions &/or cool temps

So I use both - depending on conditions

Kurt

Roger that, great to know. Thank you!

 

[kurtak]

Keven - Jason

Agitation is key to the success of cementing (ether "constant" stirring or bubbling) especially if there is a high concentration of PGMs

I was having trouble with this awhile back with solutions with high levels of PGMs that I posted about & 4metals helped to clear the problem up in this thread :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=21218&hilit=cementing#p219231

My first couple post explain the problem then 4metals helps solve it - hope that helps you guys as well

When you cement your copper (with iron) the more dilute the solution is & with bubbling agitation your copper will come down finer - then if you use the copper powder - in small additions - to your stock pot - with constant stirring - it should improve your stock pot recovery without ending up with a lot of copper contamination

Kurt

 

[jason_recliner]

Thanks Kurt.
I've seen that thread before; it makes a bit more sense now, and different sense too.

 

[FrugalRefiner]

I too use a two bucket stock pot system, with copper in the first and iron in the second. All of the precious metals are below copper in the reactivity series, so given enough time and agitation, they should all cement out completely in the copper bucket. When I move the solution to the iron bucket, the copper will cement out on the iron.

I think it is important to remember that everything below iron will also cement out in this bucket, not just copper. This means you could have a mix of copper, antimony, arsenic, bismuth, lead, tin, nickel, cobalt, cadmium, etc. if any of those metals are in your waste stream.

I'm fortunate to have plenty of scrap copper available, so I prefer to use fresh copper in my first bucket rather than take the chance of adding any contaminants back into the first bucket. This keeps the cement in the first bucket pretty clean, since this is where I expect to find any precious metals.

Another thing to keep in mind is that Harold only used a single bucket with iron. Since he processed mass quantities of jewelers' waste, this made a lot of sense. He would use a magnet to remove all the iron from the waste he received and he added that to his stock pot. In this way, any precious metals that may have been mixed with the iron, e.g., bits of gold or platinum stuck to broken jewelers' saw blades, were not lost. As the iron blades were consumed in the stock pot, the values remained in the sludge.

I guess it depends on what type of scrap you process, and what processes you are able to use to treat the contents of your stock pot. Just keep in mind that it's not a clean, simple matter of PMs cementing on copper and copper cementing on iron.

Dave

 

[kadriver]

Great info here, thanks to all who responded.

About 10 days ago I had 5 rings, I concluded that all were 14k but one was platinum And unmarked.

I did a gold test with 14k acid and it LOOKED like 14k gold.

As I inquarted I began to stir and the one ring was not melting very well.

I pulled it up on the side of the melt dish and added heat and part of it went into solution/alloyed with the molten gold and silver.

I pulled the remaining part of the intact ring out of the melt and put it in with other scraps of Pt that I am saving for later on after I have gained some more experience with PGMs.

After making flakes from the melt, I treated with dilute nitric acid and then tested the silver nitrate with stannous.

Sure enough it was loaded with platinum. I added this to my silver jar for cementing later on.

I processed the gold in the normal manner with AR and the waste (I call the left over SMB liquid after the gold has been precipitated, waste) was tested and showed high level of Pt also.

I added this waste to my stock pot that is charged with at least 20 pieces of fresh copper metal from cut-open copper tubing.

Last Friday I added about 5ml nitric acid to see if that would help get the platinum to cement out - stirring manually several times a day.

I was going to siphon my stock pot liquid (settled overnight) to my iron bucket today but first did a stannous test and bang, still platinum clearly visible (see picture).

I am going to get several aquarium bubblers and use these to start agitating the buckets. This Pt has been in the stock pot for about 10 days and it refuses to cement out completely.

This stock pot info has all been very helpful. Thanks again to all who gave input.

kadriver

 

[kurtak]

I think it is important to remember that everything below iron will also cement out in this bucket, not just copper. This means you could have a mix of copper, antimony, arsenic, bismuth, lead, tin, nickel, cobalt, cadmium, etc. if any of those metals are in your waste stream.

Dave

Very good point Dave

I'm fortunate to have plenty of scrap copper available, so I prefer to use fresh copper in my first bucket rather than take the chance of adding any contaminants back into the first bucket. This keeps the cement in the first bucket pretty clean, since this is where I expect to find any precious metals.

Due to the fact that most of my PMs come from dirty sources (electronics, contactor points etc.) I also use nothing but clean copper for cementing stock pot values & because I scrap metals in general I never have a shortage of clean copper on hand --- the copper I recover from cementing with iron gets melted & poured into 2 pound bars & sold as red brass to the scrap yard

I guess it depends on what type of scrap you process, and what processes you are able to use to treat the contents of your stock pot. Just keep in mind that it's not a clean, simple matter of PMs cementing on copper and copper cementing on iron.

correct - if I was processing more - or nothing but sterling &/or coin silver & karat/dental scrap & didn't scrap other metals (which provides a cheap source of copper) I would then likely use my copper recovered from the iron cementing process --- but only then

kadriver

If there was a relatively high concentration of PGMs in your AR stock pot it may have already formed the passivation layer of PGMs on your copper that was giving me troubles which 4metals helped with (agitation) in the thread I provided a link to in my other post --- this passivation layer maybe somewhat of a problem if you try to re-use it in your AR stock pot - even with agitation now added

At least it was for me when I tried re-using it in my AR stock pot after I got my bubbler --- so what I have been doing is adding my copper with the passivation layer to my silver nitrate solutions when cementing my silver - the silver nitrate seems to get under the passivation layer better then in an AR solution & the PGMs are then being recovered in the anode slime from the silver cell

In fact if the AR stock pot has a "high" concentration of PGMs the passivation problem can still be "somewhat" of a problem - even with the bubbler - though certainly not as bad as without the bubbler

I have found (since the discussion with 4metals) that when higher levels of PGMs are involved "fine" copper powder on the magnetic stirrer works better - you want to do it with small additions of copper powder - with time given to each addition to insure that all the copper has had time to dissolve & go into solution - more time needs to be given between additions as it nears the end - so there is a bit of a learning as you go curve - & of course stannous testing as you go near the end

Here is a pic of a bus bar (right) used with a bubbler in AR high in PGMs - compared to one used to cement silver (left) first day in the bubbler most of the PGMs came down but still had a PGM positive stannous test --- 3 days later it was still testing PGM positive so stopped it & went to copper powder on the magnetic stirrer - a few hours later I had the rest of my PGMs with a negative stannous test

Kurt

 

[kadriver]

Excellent Kurt, I got two aquarium bubblers today at WalMart, about $7 each.

I have 5/16 clear tubbing with a 12 inch length of rigid tubing at the end to keep it directed at the bottom of the buckets.

Copper powder, magnetic stirrer treatment for stubborn PGMs - that is very good to know.

Also withdrawing copper with passive layer from the stock pot and using it to cement silver, I never would have done that. Thanks for that tip.

I concluded that after the PGMs are cemented with the stir and copper powder that the solids are returned to the stock pot.

Great info - thank you!

kadriver

 

[nickvc]

As has been said it really does depend on the quantities and sort of materials you refine and recover as to what the best route is with stockpots. I always had a settlement tank to allow any fines to settle to the bottom with added precipitant then two stockpots the first loaded with copper the second with a little steel added fresh every time it was full. The last stockpot contents were added back into the first every now and then depending on how much material I had in my system, the last stockpot I worked on the theory if I could cement copper out all the values especially any PGMs should have also been cemented out and could be recovered later from the first stockpot.

 

[jason_recliner]

As a side note, why aren't you using calcium hydroxide for waste treatments? It's easy cheaper then sodium hydroxide and little easy to filter off. I can buy 25Kg locally at €3-€3.50.

Correct - calcium hydroxide (lime) is the better way to go for removing the iron after using iron to remove the metals below it in the reactive series - its cheaper & easier to filter - the down side is it takes longer to react & drop the iron out then NaOH --- if the solution is to dilute &/or temps to cool it can take a few days for calcium hydroxide to do its job - where as NaOH gets the job done in dilute solutions &/or cool temps

So I use both - depending on conditions

Kurt

I've just exhausted my NaOH on my waste so I'm going to buy some calcium hydroxide as per your excellent suggestion. Here's a follow up for anyone else playing at home.
It's a bit hard to buy "calcium hydroxide". As I researched bulk limes, you might find the right one in your local Bunnings / Mitre 10 / Lowes as "builder's lime" or "hydrated lime". On the other hand, "lime" from the garden centre may well be calcium magnesium carbonate. Just keep an eye on the fine print or MSDS.

 

[MarcoP]

I was finally able to find the english product's name of what I'm using: lime wash paint, basically slaked like (calcium hydroxide) in water.

 

[kurtak]

Calcium carbonate works just fine - its what I use - I buy what is called "barn lime" (used by dairy farmers to spread on their barn floors) any feed/farm supply store should have it & it is dirt cheap - it takes 2 - 3 days with stirring it a few times a day to complete the reaction

Kurt

 

[kadriver]

Here is a short video that I made after I siphoned the liquid out of my stock pot and into my waste bucket.

There is a nice layer of black powder accumulating in my stock pot.

I will just continue to run all my waste through this bucket - I didnt realize that it would work this well.

Harold's "stock pot retirement plan" is valid - here's proof.

https://youtu.be/P86Ch6w2V7I

Thanks for looking!

kadriver

 

[MarcoP]

The plastic will hold some values, that's why the bucket is black all around, When time arrive you should incinerate the bucket to get all the values (exactly as Harold does). I preferred to use a 20L glass jar, pretty tick glass, and get a friend to drill an hole at about 10cm from the bottom to screw in a teflon tap so I can easily decant the liquid ... yet unused.

Marco

 

[g_axelsson]

Oooohhhh, I could never keep my hands off that stock pot. I would refine it as soon as there are enough materials just to find out how much there is. :mrgreen:

After refining 50 grams of gold in mostly smaller batches of one or a few grams I emptied my stock pot the first time. I recovered a gram of gold and a few grams of PGM:s, then I seldom let the gold settle for more than half an hour after a drop so some fine gold is always carried over. I like the speed of refining and I catch the gold from the washing water in the stock pot.

My first mistake in the stockpot was to put in a solid chunk of copper, too heavy so I risked smashing the glass jar and too little surface area. Second mistake was to fill it up too far one day I had forget to remove the barren liquid before refining some gold.

A good video! I really like your system with bubbler for agitating the liquid, but then I guess you have to turn off the air before removing liquid. How long do you let it settle before siphoning off the barren liquid?

Göran

 

[Palladium]

I love your ingenuity! Necessity is the mother of invention. Something i have been noticing in your video i wanted to point out. The spray or the squeeze bottle for washing things like from one bucket to another where it takes a LOT of squeezing. By the time you go through a whole process from a to b it tends to take its toll on your hands. When i was running a lot of materials by hand that calculated into a lot of squeezes if you think about it. This is what i eventually found to work best for me after trying several types of spay bottle designs and sizes. I can't find a picture of it on the net or listed on their website, but they have them at dollar general for $4. Just look for them. Their not to big or to small and you can adjust the fan for light mist when all you need to do is wash the watch glass back into the beaker without splattering it everywhere or a steady stream for moving a lot of materials. Its great for washing those stubborn fine powders out of hard to rinse plastic buckets. Pry the little locking mechanism off the top of the handle like you would a child proof lighter and your good to go. The trigger is pressure sensitive so the more you squeeze the more comes out which is great for me. I swear this is the only picture i could find of it so you will have to overlook the video it's presented in. :mrgreen: https://www.youtube.com/watch?v=jWh4SHUtAVs

 

[4metals]

I too noticed how often Kevin squeezes that bottle. He must have developed some grip!

I like to use a setup in a refinery that I call an endless squeeze bottle. It uses a small adjustable nozzle which goes from a heavy flow all the way down to the smallest stream you can get from a squeeze bottle. The difference is since it works off a pressurized hose it is a strong fine stream and it never quits. This is the nozzle. http://www.mcmaster.com/#garden-hose-nozzles/=yy7xgk The nozzle is item F

The only problem is there is no shut off. I then use a standard spray nozzle with a trigger and a hose thread on the spray end, like this.http://www.mcmaster.com/#garden-hose-nozzles/=yy7xzn The other nozzle is either L or M

Finally a retracting hose makes the unit complete, one like this;http://www.mcmaster.com/#garden-hose/=yy7yg0 The second hose type listed, scroll down.

Put them together and give up on those squeeze bottles for tap water. Note: Distilled water users still need to squeeze!

 

[Shark]

I love your ingenuity! Necessity is the mother of invention. Something i have been noticing in your video i wanted to point out. The spray or the squeeze bottle for washing things like from one bucket to another where it takes a LOT of squeezing. By the time you go through a whole process from a to b it tends to take its toll on your hands. When i was running a lot of materials by hand that calculated into a lot of squeezes if you think about it. This is what i eventually found to work best for me after trying several types of spay bottle designs and sizes. I can't find a picture of it on the net or listed on their website, but they have them at dollar general for $4. Just look for them. Their not to big or to small and you can adjust the fan for light mist when all you need to do is wash the watch glass back into the beaker without splattering it everywhere or a steady stream for moving a lot of materials. Its great for washing those stubborn fine powders out of hard to rinse plastic buckets. Pry the little locking mechanism off the top of the handle like you would a child proof lighter and your good to go. The trigger is pressure sensitive so the more you squeeze the more comes out which is great for me. I swear this is the only picture i could find of it so you will have to overlook the video it's presented in. :mrgreen: https://www.youtube.com/watch?v=jWh4SHUtAVs

That spray bottle recently went up to $5 or $6 (my memory isn't the greatest), still not a bad price though. I have two, one of which I reworked the internals and converted it to a vacuum pump. They even work pretty good as a sprayer for weed killer and insecticides.