Non-Chemical Precipitation for newbs

[kurtak]

“What make you thing the copper contamination was because the button "was from old dirty papers"

Because I filtered copper chloride through some of them.

I do not precipitate using hydroxide. I simply raise the ph.

You missed my point - you originally said your button was contaminated with copper because it came from dirty papers (in other words the AR had copper in it because the papers had copper in them - therefore when you precipitated the gold - copper also came down - because copper was in solution from the copper in the papers)

There is NO reason for copper to come down with your gold simply because copper is also in solution when you go to drop the gold - IN FACT - you can drop you gold - as near pure - if not pure --- by ADDING copper

That is why I followed up the question about the dirty papers with --- "I suspect it was the result of raising the Ph with hydroxide"

In other words - by raising the Ph of your AR to Ph 3 - you have made the acids that are keeping the metals in solution weaker (in this case the copper) - therefore - the weaker acid - that is having trouble holding the metals in solution - are going to be MORE likely to come down WITH the gold when you go to precipitate the gold

In other words - the acid is no longer strong enough to keep the more reactive metals (like copper) in solution when you go to drop your gold --- which is why you ended up with a button contaminated with copper - which is why you now need to re-refine the button

WEAK acids WILL cause base metals to come down with your gold - whether the acid is made weak by raising the Ph of the acid - or by "over" diluting the acid with water

You are doing both - you are adding urea that is dissolved in water (30% urea 70% water) and then adding hydroxide dissolved in water - so you are making the acid weaker with the hydroxide addition to a Ph of 3 - plus diluting the acid with water (the water may not be enough to make a difference - but raising the Ph certainly makes a difference)

The very reason you ended up with a button contaminated with copper - that needs re-refining - because it's not near pure

Let me put it this way - I have "cemented" MANY ozt from VERY dirty solutions with nothing but copper & turned out gold no less then 995 & as pure as 999

Last year when I spent a week in Jon's lab - I did a batch of ceramic CPUs (so VERY dirty solution) I showed Jon, Goran, Nick, & Pat how to drop the gold with copper - we were expecting 53 grams of gold from that batch & we hit the 53 grams on the nose & the gold came down right at 995 --- with nothing but copper & the batch was done from start to finish in a day - & for what it is worth the gold could have been brought up to 999 by putting a "pinch" of potassium nitrate in the melt of the powder (didn't do that)

Bottom line - & as Butcher has told you - adjusting Ph (up) is NOT a "better" way & is likely to cause problems --- especially with "dirty" solution

So I suggest you stop pushing this narrative that you have come up with a "better" way - when in FACT it's just not true - we try to teach "new" members "age old" methods that are tried & true - & NOT methods that can/will cause problems

Not saying your method wont work - but it "most certainly" has the potential to cause problems

Bottom line --- there is NO need to add hydroxide to drop ALL your gold - & drop it "very" near pure - from VERY dirty solutions

ALL of us - that have been doing this for MANY years - have been doing it with out the "need" to add hydroxide & we have OFTEN had to help new members clean up their mess - "because they added hydroxide

So again - I suggest that you stop telling our new members to use a method - that we KNOW is going to get them into trouble - & then we have to fix their problem - because they followed your BAD advice

For new members following this thread --- you DO NOT need to add hydroxide to drop your gold - DO NOT follow this advice - it is bad advise that is likely to cause problems we will then need to fix - we spend a lot of time fixing problems without having to add another possible problem to what we do - there are better whys to deal with dirty solutions & or solutions with free nitric in them

In both those case's - cementing happens to be my go to method - it's not the only why but it is my way & yes you can hit near pure - if not pure gold --- there is "a bit" of a learning curve with using copper - which I have posted about several times here on the forum --- you will be better served following my advice to cement with copper (or other methods discussed) - then following this advise to add hydroxide

Kurt

 

[Jmk88]

Kurt,

Who said I had come up with a new way and who said I use hydroxide to drop my gold?

Think I’ve clearly said the opposite mate quite a few times.

 

[Jmk88]

And for that matter... if you said to a professional refiner that you’re preferred method was to cement with copper, they would laugh you out of the room.

Fact.

 

[kurtak]

Kurt,

Who said I had come up with a new way and who said I use hydroxide to drop my gold?

You did not say you are using hydroxide "to drop the gold" - nor did I suggest that is what you are doing

nor did ether one of us call it "a new way"

However - what you have "pushed" here - is that by raising the Ph with hydroxide you get a "better" result of droping the gold

And the FACT of the matter is that flat out is NOT true

Kurt

 

[butcher]

I am not laughing, not even a chuckle, using copper as a reagent to precipitate gold from solution contaminated with base metals is just good common sense, any good refiner would have in his toolbox.

I would keep the copper in my toolbox, and dump the urea for fertilizer (urea really not that great of fertilizer either) ...

 

[Jmk88]

I’ve got the copper in my toolbox...

It’s used as a last resort. Like I said.... you said to a professional refiner that your preferred method was cementing on copper you wouldn’t be spoken to for very long.

If anything I think that’s bad advice to newbies that want to learn to do it professionally.

Copper cementing is for mess ups and stock pots. No other refinery or gold chemistry book would advise you to do this. Why are you so obsessed with cementing on copper?

 

[butcher]

fishaholic5,
I do not know how to say this?
I can understand when working with ore, there may be more of a reason to tweak around with the chemistry more, and can there be circumstances where adjusting pH, or using a carbon-based chemical reaction like carbamide, or some other reactions may be helpful or even almost necessary.

I would most likely have a whole different opinion and discussion if we were discussing recovery from ore or something else...

But not with precipitating gold for new members...

Jmk88,
Once you have done this as long as Kurt has, and spent as much hard work to learn his trade, and have gotten as skilled, then you will be able to answer that question and many more...

 

[FrugalRefiner]

Guys, come on. Urea has been used by professional refiners for decades. Cementing with copper is also used by professional refiners. They're just two different methods. Saying that either method would get you laughed at by professional refiners is pointless. Some people prefer to drop gold with sulfite. Others prefer ferrous sulfate. Others may prefer oxalic acid, hydrazine, ascorbic acid, etc. Saying that one way is the right way and other ways are the wrong way doesn't help anyone. I'm here to learn from everyone.

Yes, we usually promote tried and true methods because even novice refiners can usually enjoy success with them. It doesn't mean we can't keep open minds to discuss other methods. If we didn't, we would never have learned to use sulfamic acid to deNO_x AR.

Dave

 

[Jmk88]

I have no further comment.

Completely agree with Dave.

 

[kurtak]

And for that matter... if you said to a professional refiner that you’re preferred method was to cement with copper, they would laugh you out of the room.

Fact.

That is NOT a fact --- in fact - 4metal - who is in fact - a "professional" refiner - is the one that taught me to cement gold with copper from VERY dirty solutions that also have free nitric in them

Following "his" instructions on how to do it with results that achieve near pure - if not pure gold - is the very reason it has been my method for YEARS now

In other words Jmk88 - the method (cementing with copper) is NOT the method for "all" solutions - it's a method that works "well" for solutions that are DIRTY &/or have free nitric in them (sometimes "lots" of free nitric) --- & when done "right" you can/will achieve high purity gold

A (very) professional refiner did not laugh me out of the room - he taught me how to do it - & how to do it "right"

you should spend more time listening to & learning from "professional" refiners - instead of pushing a narrative of what you "think" works better

You "do not" need to use hydroxide to help drop your gold - & you will likely get a cleaner drop without the hydroxide

Kurt

 

[kurtak]

Why are you so obsessed with cementing on copper?

Because it works - it works well & it works every time - especially with "dirty" solutions &/or that have free nitric & it gets ALL the gold

Kurt

 

[butcher]

Using a metal, to use up the oxidizer (HNO3) in a solution that may have been added in excess, (and the metal we are adding to the solution is the same metal you already have in that solution) such as gold to de-NOx a solution, only makes good sense, you are not adding anything you do not have already in solution, you are not altering the chemistry to form salts or other impurities, you are not adding trash to get the gold out...

Using a metal like copper to recover or displace gold from a solution that already has base metals as well as copper in solution, again is just good common sense, the only portion of the added copper that will go into solution as copper ions are the amount it takes to consume the excess acids, at the same time providing electrons for the gold ions to form clusters of gold atoms large enough to precipitate from the solution, with copper ions as well as other base metals in solution the copper added just added a few more of what was already in the soup, we did not add any new trash, or salts... (drag down or the gold quality from this would most likely not change if you were to use a different reagent to precipitate the gold from this solution...).

Copper will not displace metals that are more reactive than it is or donate electrons to them...

Basically you are not adding trash to get gold out of the trash, you are just adding electrons and using the copper the same metal that is in solution already to provide electrons for the gold ions and form a bond with the chloride ions (the gold was once bonded to), to form a copper salt, only adding a little to the copper salts already in solution...

The more base metals making salts in solution the more reactions are occurring between them and the acids...

Carbamide (urea) will remove NOx gases (the different decomposition gases of nitric acid) from solution (de-NOxing the solution)...

But with nitric acid, it does not eliminate the nitric in solution but changes it to a salt, which can become a problem in later operations, it forms a salt of urea nitrate, a salt that reforms nitric acid with hydrogen or hydronium ions from acids...

Urea will remove the gases of the decomposition of the nitric acid, and any excess nitric acid in solution with the urea just converts into urea nitrate salts...
Urea is not removing the free nitric in solution it is just changing it to nitrate salts in solution (with the acids)...

Adding sodium hydroxide bonds with hydronium ions in solution to form water, and the sodium bonds with chlorides and or nitrates to form more salts, and as discussed raises the possibility of precipitating other base metals, or dragging them along...

 

[kurtak]

Using a metal, to use up the oxidizer (HNO3) in a solution that may have been added in excess, (and the metal we are adding to the solution is the same metal you already have in that solution) such as gold to de-NOx a solution, only makes good sense, you are not adding anything you do not have already in solution, you are not altering the chemistry to form salts or other impurities, you are not adding trash to get the gold out...

Using a metal like copper to recover or displace gold from a solution that already has base metals as well as copper in solution, again is just good common sense, the only portion of the added copper that will go into solution as copper ions are the amount it takes to consume the excess acids, at the same time providing electrons for the gold ions to form clusters of gold atoms large enough to precipitate from the solution, with copper ions as well as other base metals in solution the copper added just added a few more of what was already in the soup, we did not add any new trash, or salts... (drag down or the gold quality from this would most likely not change if you were to use a different reagent to precipitate the gold from this solution...).

Copper will not displace metals that are more reactive than it is or donate electrons to them...

Basically you are not adding trash to get gold out of the trash, you are just adding electrons and using the copper the same metal that is in solution already to provide electrons for the gold ions and form a bond with the chloride ions (the gold was once bonded to), to form a copper salt, only adding a little to the copper salts already in solution...

The more base metals making salts in solution the more reactions are occurring between them and the acids...

Carbamide (urea) will remove NOx gases (the different decomposition gases of nitric acid) from solution (de-NOxing the solution)...

But with nitric acid, it does not eliminate the nitric in solution but changes it to a salt, which can become a problem in later operations, it forms a salt of urea nitrate, a salt that reforms nitric acid with hydrogen or hydronium ions from acids...

Urea will remove the gases of the decomposition of the nitric acid, and any excess nitric acid in solution with the urea just converts into urea nitrate salts...
Urea is not removing the free nitric in solution it is just changing it to nitrate salts in solution (with the acids)...

Adding sodium hydroxide bonds with hydronium ions in solution to form water, and the sodium bonds with chlorides and or nitrates to form more salts, and as discussed raises the possibility of precipitating other base metals, or dragging them along...

That is correct - which is why I like copper - for DIRTY solutions &/or solution with free nitric

With "clean" solutions (like dissolved foils or clean karat scrap) that may have free nitric - I put a gold button in (with heat - on the hot plate) until the free nitric is used up (no more reaction)

Then the ONLY other chemical needed to drop the gold is SMB

Kurt

 

[g_axelsson]

Why are you so obsessed with cementing on copper?

Because it works - it works well & it works every time - especially with "dirty" solutions &/or that have free nitric & it gets ALL the gold

Kurt

Not every time. :wink: My cyanide mess I made when visiting Jon, boiling in aqua regia for hours and precipitated with copper came back as a mess again. It did it with SMB, FeSO₄ and ascorbic acid too. It took me ten times boiling in ammonia and decant to get it even to a point that it looked like dirty gold. When I melted it I ended up with a dirty gold button.

Every tool fails in some conditions. There is no perfect tool, but the professional collects enough tools to handle most situations and experience enough to judge when a certain tool is the best to use.

Göran

 

[g_axelsson]

They then go to dissolve the gold and have all sorts of problems as they have more base metals in than they should and therefor need more acids to do the job. I had a friend who ended up with 3 litres of crap from 3G of 18k gold. It was unbelievable.

They then end up with excess nitric and precipitation won’t work. When I tried to pass on advice to my friend that I had received he wouldn’t listen and proceeded with evaporation. It was a sight to behold. 3 litres. He was doing it for weeks. Then he cemented and ended up with .4 grams after 3 months. It was painful.

And you think your friend that wouldn't listen and follow easy instructions would have fared any better if he tried to add NaOH to adjust the pH? If it takes him 3 liters of aqua regia to dissolve 3 grams of 18k gold then I would not hold any hope he would manage to adjust the pH to 4 without overshoot and precipitate the gold as a hydroxide.

And evaporation, that's not hard. Give me an old style coffee maker for a coffee pot and I can finish that in a day or two. There's a thermal switch that keeps it from getting too hot. A wide and low evaporating dish on top and it's fire and forget. Top it up every hour and if you forget about it the salts will dry out but not overheat. Just dissolve it in HCl again, and you are probably close enough to filter and drop your gold after you dissolved the crust. Anything not dissolved in HCl is probably not gold, but whipe it up and put it with the filters in the burn pile.

Gold(III) hydroxide can precipitate between pH 3 to 8.

...pH range (8–3), which is most favorable for gold(III) hydroxide precipitation.

https://www.researchgate.net/publication/257541621_Properties_of_GoldIII_Hydroxide_and_AquahydroxogoldIII_Complexes_in_Aqueous_Solution

Evaporation is easy, there isn't a lot of ways you can mess it up. In contrast, adjusting pH takes some chemical knowledge, a light touch and patience. Three things few newbies have. That is why I wouldn't recommend this "adjust the pH method" to a newbie.

Göran

 

[Jmk88]

Thank you all as always.

Everything has been considered. As always.

 

[butcher]

We all learn something every day, it keeps life interesting, and we are not just sitting around with a dead brain, but using it to discover lifes mystery and wonders.

I have been learning these skills for several years, almost all of my old notebooks are useless, yes they have some very relevant information, but they were written as I was learning, so I would make notes on what I had learned at the time, years later I would learn much more, and the old notebook would need to be rewritten.

I find I have to always be updating notes or my thinking as I learn more.
as I learn more I also learn that what I learned in my youth may need to be revised..,
Like shedding old skin and growing a new one.

 

[Jmk88]

That’s what I always say to people when they ask why I’m so solitary.... I find it baffling how one can be interested in people when life has so much to offer.

I’m always ahead of the curve... I’ve been social distancing since I was an early teen.

Any links to Kurts method would be much appreciated.

 

[kurtak]

Read ALL of this thread - it will get you STARTED on cementing with copper

:arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=85&t=22203#p232016

Kurt

 

[kurtak]

Also read this

:arrow: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=28635&p=302186&hilit=cementing#p302186

Kurt