# Copper dissolves while cementing.



## zumka (Dec 9, 2021)

Hello, everyone. 

I searched a lot but couldn't find a similar problem and i hope i didn't open an unnecessary thread.

I have a stockpot with AR waste in mostly. And a few failed attemps which i directly put it in without causing more acid waste. (Total around 5 litres of water, hcl, nitric, a few ml sulphuric, sulfamic, urea and smb)

I tried to cement out but the copper plate and copper wires i add in dissolved after a few hours. And no solid at the bottom. Waited anyway till morning with air-bubble in, tried two different times but same problem. (Expecting minimum 4-5 grams gold alone just from failed attemps i added in)

So, what am i missing? What should i do?

Thank you in advance.

Zuma.


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## Yggdrasil (Dec 9, 2021)

zumka said:


> Hello, everyone.
> 
> I searched a lot but couldn't find a similar problem and i hope i didn't open an unnecessary thread.
> 
> ...


Most likely way too much Nitric and Sulfuric.


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## Lino1406 (Dec 9, 2021)

Maybe air (oxygen) bubbling has negative effect for reduction


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## Martijn (Dec 9, 2021)

Don't put AR in your stockpot! Refine gold with it. 
When the oxidizer (HNO3) has depleted, return the used HCL with left over traces of pm's salts to your stockpot. 
Martijn.


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## nickvc (Dec 9, 2021)

My advice follows on from yggdrasil reply consume any free nitric with additions of sulphamic and try again.


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## zumka (Dec 9, 2021)

Thank you all for the replies. 

Yeah, one of the reason of a falied attempts was the free nitric. I added sulfamic to the stockpot. I think i even overdosed. (Around 10 tablespoons). About sulphuric, i'm sure it's not more than 5 ml. But as i'm not an expert, if you say that still can be a reason, i would love a way to get rid of it. 

I will be more careful next time about AR as Martijn said.

And about air bubble makes negative effect, i would try again without air bubbling if it makes sence.

Thanks

Zuma


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## FrugalRefiner (Dec 9, 2021)

An air bubbler is a double-edged sword with pros and cons.

Any cementation reaction, like your stock pot, benefits from circulation. The solution bearing your values has to come in contact with the metal being used to cement the values out. An air bubbler is a simple, low cost way of circulating the solution.

But, an air bubbler also helps oxygen to dissolve into the solution. The AP process (copper chloride leach) relies on oxygen to convert CuCl to CuCl2 which then dissolves more copper. So cementation needs to be monitored to determine when the process is complete.

The AP process is slow. It takes a long time to digest copper plate or even heavy wire. Since your copper dissolved in a few hours, I would expect the excess nitric was the culprit.

Dave


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## zumka (Dec 9, 2021)

Thank you, Dave.

So, as sulfamic didn't work on nitric, what would you suggest to neutralize the nitric? Or there is no recover? (Stannous test positive)


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## FrugalRefiner (Dec 9, 2021)

Can you post a picture of your stannous test please?

If it is a true positive test, and the purple / black color remains, it would indicate that there is no longer any excess oxidizer (nitric in this case).

If that's true, I would add more copper and watch what happens. You can test by dipping a clean piece of copper wire into the solution for 30 seconds, then pulling it out. Is it still clean copper colored, or is it coated with a gray or black color?

Dave


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## zumka (Dec 9, 2021)

FrugalRefiner said:


> Can you post a picture of your stannous test please?
> 
> If it is a true positive test, and the purple / black color remains, it would indicate that there is no longer any excess oxidizer (nitric in this case).
> 
> ...



Sure. I will post a picture as soon as i'm in my workshop.

I already tested with a clean copper wire. It turns into a whitish gray colour in a few minutes.


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## Geo (Dec 9, 2021)

You can dilute the solution to effectively raise the PH. Diluted solution tend to work better than concentrated solutions when cementing.


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## orvi (Dec 10, 2021)

zumka said:


> Thank you, Dave.
> 
> So, as sulfamic didn't work on nitric, what would you suggest to neutralize the nitric? Or there is no recover? (Stannous test positive)


sulfamic acid should work, but it perform better at higher temperatures. 
afterall, the classical options how to get rid of nitrates are: evaporating down with HCl, sulfamic acid, adding metal to deplete it completely.
I am sure evaporating the stockpot is way too impractical. Sulfamic acid did not work for you... So... maybe the easiest (but not best) option is to add more copper to deplete nitrates. Or adding iron to the pot could cement some copper back as precipitate, which in turn redissolves back with help of that nitric  overall consuming iron = cheaper. But this will also cement out your gold.


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## nickvc (Dec 10, 2021)

You could also add some zinc if you have any , this will consume the acid but may allow other metals to cement out but this is only a problem if you want to recover the values now, if not adding more solutions to your stockpot later will dissolve any base metals and also cement out values.


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## Geo (Dec 10, 2021)

I have a seemingly endless supply of rusty nails. When I collect a few gallons of solution in a five gallon bucket, I add a small hand full of nails. I expect some copper to come down. For me, it's not a problem. If it is time sensitive, I will use steel wool from the hardware store. I buy a variety pack that weighs a couple of pounds for around $9 USD. When I have a solution that is being very stubborn and I need to "get on with it", I use steel wool and a couple hours later I am re-dissolving and trying not to make the same mistake that caused it the first time.


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## zumka (Dec 13, 2021)

Well, while i was still confused about what to do, now i have this.

I layed a copper wire without air-bubble as suggested. And next morning, i see that thick layer as you see in the picture, attacked to the wire. What that should be?


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## zumka (Dec 13, 2021)

I dipped the second wire 2 hours ago and it's like this. (So whatever the metal is this, still cementing)


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## upcyclist (Dec 13, 2021)

How much copper are you adding? Using some very fuzzy math, it'll take about 250g of copper to consume 1 L of nitric. So, that's about a half pound of copper for every liter of 70% nitric you have in there. For perspective (and more math), that works out to about 25 or 26 _feet _of 12g AWG copper wire.

Hopefully I didn't flub the math


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## Lino1406 (Dec 13, 2021)

zumka said:


> Well, while i was still confused about what to do, now i have this.
> 
> I layed a copper wire without air-bubble as suggested. And next morning, i see that thick layer as you see in the picture, attacked to the wire. What that should be?


When copper cements metal, it should be nobler then copper, e.g. silver, mercury, palladium, gold...


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## speed (Dec 13, 2021)

Just make sure there is copper in there for a few weeks and it will sort itself out. You can then collect what has cemented out and try again.


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## zumka (Dec 13, 2021)

Thank you, all. I will update with the news.


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## minero74 (Feb 19, 2022)

Hello Guys
I have reading this blog for very long time
and I learn a lot
I'm following many members posting 
And I do my own cement out
and this what i get
i put a piece of copper pipe
and i get a black powder


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## Yggdrasil (Feb 19, 2022)

minero74 said:


> Hello Guys
> I have reading this blog for very long time
> and I learn a lot
> I'm following many members posting
> ...


Nice, do you have a question?
The black sludge is your values, but they need refining.


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## minero74 (Feb 19, 2022)

Yggdrasil said:


> Nice, do you have a question?
> The black sludge is your values, but they need refining.


Thank you for replying
I have one question
because the solution is from ore rocks
and i wonder if that black sludge
is gold or mix it with PGM group?


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## Yggdrasil (Feb 19, 2022)

It have to be tested.
Simply redissolving and testing with stannous will give some answers.
A full assay will tell the whole story.


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## minero74 (Feb 20, 2022)

Yggdrasil said:


> It have to be tested.
> Simply redissolving and testing with stannous will give some answers.
> A full assay will tell the whole story.


Thank you very much
Before i cement out 
the solution with copper
I do test the solution with Stannous chloride
and it was black and bit purpple
But as I'm new in refining
I was with lot of doubt and I choose to cement out to see what i get from that solution.
I will follow your advice 
and redisolve it and check again with stannous again.

Thank you very much


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## Yggdrasil (Feb 20, 2022)

minero74 said:


> Thank you very much
> Before i cement out
> the solution with copper
> I do test the solution with Stannous chloride
> ...


You may need to dilute it, if it is very black. The colour should be purple for gold and orange for Pt. 
Pd gives a greenish mixed colour.
If it is a mix you may get strange results color wise. 
You could then drop the gold with SMB and test again without the gold.


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## minero74 (Feb 20, 2022)

Yggdrasil said:


> You may need to dilute it, if it is very black. The colour should be purple for gold and orange for Pt.
> Pd gives a greenish mixed colour.
> If it is a mix you may get strange results color wise.
> You could then drop the gold with SMB and test again without the gold.


Thank you very much
You help me a lot
I will do it.
Thank you


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## orvi (Feb 21, 2022)

minero74 said:


> Thank you very much
> You help me a lot
> I will do it.
> Thank you


After the cementation is done, don´t forget to brush that copper pipe - some values tend to stick to the surface and they don´t fall off on their own, or with just rinsing.

Be aware that in mining waste solutions, mercury and arsenic could be present as well - and these are severly toxic. If you immerse copper pipe to the solution, mercury will precipitate from the solution together with other values. 
If you aren´t sure, never smelt the cemented metals. Rather dissolve them again in AR and proceed from there. By doing this, you circumvent possible mercury volatilization during heating and smelting.

Stay safe


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## minero74 (Feb 21, 2022)

orvi said:


> After the cementation is done, don´t forget to brush that copper pipe - some values tend to stick to the surface and they don´t fall off on their own, or with just rinsing.
> 
> Be aware that in mining waste solutions, mercury and arsenic could be present as well - and these are severly toxic. If you immerse copper pipe to the solution, mercury will precipitate from the solution together with other values.
> If you aren´t sure, never smelt the cemented metals. Rather dissolve them again in AR and proceed from there. By doing this, you circumvent possible mercury volatilization during heating and smelting.
> ...


Thank you for the advice

let me tell you the process that i was doing and the ore that i was use it.
and let see what you guys are thinking about

I was use a very rusty Rhyolite
i pulvurize and put the material in a beaker with sulfurix acid and a bit of distiled water
heated but not boiled for 40 minutes
in open air outside my home
let cool down,decanted the solution
washed the material several times
them i put aqua regia
with little nitric acid enought for the process
and few drop of sulfuric acid
them heated but not boiled for 1 Hour

let it cools down and cotton filter
twice
after that i separate it in two parts

i put one part with the copper pipe and the other part
i save it until i know i good process to get the value of it.

i apologize for english
i still learning


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## orvi (Feb 21, 2022)

Why do you choose to process it like this ?

If anything of value go into the AR solution, you will cement it all out on copper. In terms of reducing volumes of liquid to just handful of concentrate, this is the best recovery method - widely applicable and nearly 100% effective. Just need to be in the solution for quite a time, and solution should be agitated for better circulation of liquid inside the vessel.


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## minero74 (Feb 21, 2022)

orvi said:


> Why do you choose to process it like this ?
> 
> If anything of value go into the AR solution, you will cement it all out on copper. In terms of reducing volumes of liquid to just handful of concentrate, this is the best recovery method - widely applicable and nearly 100% effective. Just need to be in the solution for quite a time, and solution should be agitated for better circulation of liquid inside the vessel.


Thank you for the advice

Because of my lack of knowledge
working with aqua regia.

if get anything of value
i trying to make it the best way possible to leach the gold out off the gold ore.

I was thinking that heat the ore with concentrated sulfuric acid solution
will i get rid of most base metal
and aqua regia with dissolve of others precious metal that could be in the ore.

I think leaching gold from gold ore this way more faster
than Chlorination of SSN.

if i learn how to do it the right way.
and if i can possible keep the consumption of nitric acid to a minimum.
can be profitable.
maybe I'm wrong
for reason i want to hear from peoples with more knowledge and learn from them.


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## orvi (Feb 22, 2022)

Sulfuric acid helps you to get rid of basic carbonate minerals (if there are any), and also some oxides to some extent. Remember that you do not have metals in there, there are metallic compounds. It is very different to take copper or iron and dissolve them in acid, than taking malachite or hematite and dissolve them in acid.

Actually, you maybe done good with sulfuric acid. There are some cases when you cannot perform acidic pre-leach with aggresive strong acid like HCl. Many ores contain pyrolusite or burel - manganese dioxide. If MnO2 is present and you pour HCl into it, it reacts and generate chlorine. That will slowly dissolve the gold.

Other big question is.. If the gold is naked to acid leach solution. If it is liberated or enclosed still in the rock. Did you panned some of the crushed material and seen gold ? Or the gold is invisible and you try to prove it is there ?

My assumptions: 
There are far better methods how to analyse and process the ore like you are describing. Rusty means lots of oidized iron in oxohydroxide form. That need acid to be converted to ton of liquid Fe waste - ineffective.

Be sure that ore do not contain sulfides. Pouring acids on sulfides isn´t good idea. Sulfides are reducing agents - altough not that reactive, they can slowly react and depleting your AR solution from nitric acid oxidizer - or dropping your gold back to solution. If the sulfides are concerned, I will firstly roast the ore to get rid of them.

Finally. If you are trying to chase the values in some type of deposit, firstly, you must be sure they are there. It isn´t an very big deal to take represenatative sample from outcropping and pay for one analysis to be sure your values are there. Then I will start to elaborate recovery process.


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## nickvc (Feb 22, 2022)

One point I always raise when working with ores is to know what you are dealing with as roasting or adding acids can create highly toxic and possibly deadly fumes…


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## minero74 (Feb 22, 2022)

Thank you guys for the advice
I will be very carefull when dealing with some kind of ore with arsenopyrite.

the ore that I took
is an example for a old abandoned mine with free mill gold
it was just 5 lbs of ore.

in this case it's appears that it have invisible gold
because when i crushed and panned
i don't see any visible gold
not even with a loop

the history of that mine is not to extensive ,but is for gold and silver as well.

it have tons of high grade ore just outside in a pile that the miner left it
long time ago

i roasted ore to dead roast for almost 1.5 hrs
after that i do the pre leach process with sulfuric acid
and then AR.

I have some knowledge with SSN
and cement out with Zinc powder
and i get very good result
but that process is way longer
if I learn this new way working with AR
and if a get values of it.
can be profitable

this sunday I will dissolve the sludge with AR as you Guys told me to do

thank you for the valuable advice
learning is a process
and thank you for sharing your knowledge.


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## minero74 (Feb 22, 2022)

This is was one of the ore
I put it Brilliant green to see if it have gold and look the color change


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## minero74 (Mar 2, 2022)

Hello guys
I pick the black sludge ,that i get from the copper cement out and I heat it with dilute it nitric acid
and this is what i get.

when from black powder 1 picture
to the light color in the 2 picture.

I have no idea what happen
I think is not brown compare to others pictures of gold precipitation that others peoples get.


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## Martijn (Mar 10, 2022)

minero74 said:


> Hello guys
> I pick the black sludge ,that i get from the copper cement out and I heat it with dilute it nitric acid
> and this is what i get.
> 
> ...


Looking at the hairs in your pm cement, I suspect you did not filter before cementing. 
Making it organic chemistry which i can't help you with. 
So anything could have happened.
Junk in junk out. 
Something reacted with your cement possibly forming nitrates. It's not silver, that should have dissolved. 

Ore can contain mercury and tungsten which are less rective than copper and can also cement out on copper. (I think, and needs confirmation) 

Is there any brown powder left on the bottom? 

Maybe dissolve a small sample in AR and test with stannous for pm's. 

Martijn.


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## minero74 (Mar 12, 2022)

Thank you the reply

I agree with you,i guess is pure junk
I just put it a side and I will start
again
I learn from the advice giving to me here
and from all this mistake that a make.

I really don't see any brown powder
in the beaker.

i have another part of the same solution and i do stannous test
and this is what i get


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## FrugalRefiner (Mar 12, 2022)

It may just be the picture or my screen, but to me that looks brown. It is what we refer to as a false positive. Gold will be a definite purple. If there is a lot of gold in solution, the purple can be so dark it looks black.

Dave


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## minero74 (Mar 12, 2022)

Thank you Dave
Yes it was very black and brown
I cemment out the solution with zinc
and i wash it the zinc precipitate with nitric acid and heat it.

and the solution getting light blue
could be silver?


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## silver1 (Mar 13, 2022)

If you have crushed the rock and looked at it under magnification and can't see any visible gold then the gold may not be in metallic form. Maybe the gold exist as a compound within the rock. It could exist in what looks like the iron part of this story. From the looks of that test solution the solution looks irony chloride color. Then you added stannous which reduced it to that brown color there (Iron) in your test. That would be my guess..... don't know. If you had that much iron in your solution then chances are it (Gold) never went into solution in the first place and is still on the residue (Rocks) from the leach. That's before you even start to discuss the grinding or fineness of the rock or proper roasting. A lot lot of things could have gone wrong.


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## Martijn (Mar 13, 2022)

minero74 said:


> Thank you the reply
> 
> I agree with you,i guess is pure junk
> I just put it a side and I will start
> ...


You said you had black powder cemented on copper, so it's not all junk. Just not as clean as it should have been. 









When In Doubt, Cement It Out


When In Doubt, Cement It Out This is advice I often give to new members who find they've created a bit of a mess, and they're wondering how to recover their values (gold, silver, PGMs, etc.). Perhaps they've followed a process they've seen on YouTube that left out some important details...




goldrefiningforum.com





Now why did you cement with zinc this time? 

The light blue can be because of the zinc, now in solution. Giving a silverish look. Zinc chloride is colorless and clear like silver nitrate. 


Redirect Notice


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## minero74 (Mar 13, 2022)

Thank You Martijn and Silver1

I learn a lot from yours advice

Yes it was lot of iron in those stone.
the mine story said it is a gold mine
perhaps i choose the wrong stones.

I cemment out with Zinc this time
trying a different process to find one that can bit faster than SSN.

i was doing placer before but now the is not lot of land close by for placer
because is the easier way

now i get into hard rock mining
that is a whole different way

but is very interesting,
finding a way to get the gold out off those stones in the safe manner possible

and i wont quit
i will try as many time i can and
i will find a way to get the gold out off those stone
there are lot of lode mine around

but very few mine with free mill gold

one mill site with lot of green stones

the old miners were melting those stone on site.

i'm posting some pictures of those stones
they were focus only on those two types of ore


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## Martijn (Mar 13, 2022)

I think you're better off to learn to fire assay and cupel.


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## orvi (Mar 13, 2022)

I will try to abandon the leaching approach. In some circumstances, it could work, but I don´t consider this approach easy and replicable. Too many factors which could mess it up.

I will perform fire assay. If you aren´t certain that no mercury or cadmium are present, do not do it on your own. If you have means to undoubtly confirm there is no mercury and cadmium, go for it (like well calibrated XRF of reputable brand, capable to run "geochem" mode. or ICP analysis better). You can also replace lead with bismuth, making it less toxic.


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## minero74 (Mar 14, 2022)

Thank you Martijn and Orvi
I will follow your advice
Judging by the size of the Slag in that Mill site 
that's the way it is.

and a friend talk me about a place
where they do fire assay.

Thanks a lot guys


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## orvi (Mar 14, 2022)

minero74 said:


> Thank you Martijn and Orvi
> I will follow your advice
> Judging by the size of the Slag in that Mill site
> that's the way it is.
> ...


Inform us how it was going. 
I hope that you successfuly test the ore with good results.

Orvi


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## minero74 (Mar 14, 2022)

Thank you
For all your advice and sharing the valuable knowledge you guys have.

I will let you guys know 
thank you very much


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## EAR74 (Nov 11, 2022)

We're you able to get fire assay done?I read so many threads of success ,failure,and the questionable due to process and profitability.I do wish you luck,health ,and promising future.I look forward to updates from many people and process reports that lead to successful safe profitable refining.


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