Removing copper/silver from gold

[Xotom125]

Helloi am new to the site.
I am currently working on an industrial sized agua regia machine processing up to 5kg per cycle currently we have processed gold of 92 percent and above on the machine with good results. We now have a client who is wishing to have us process gold that is coming directly from the mines at 60-70 percent, we expect the material that we need to be separated to have copper or silver in large amounts due to the location of the mine.

Starting with copper can anyone give a detailed account of how to remove excess copper,so far we have been advised to add more copper still to force a separation. Is this correct and also is this the only way to achieve the seperation. If there is a separate machine that Be bought for instance to convert the original 70 percent gold to a higher amount by removing the excess copper before moving to AR we would like to know. If it is just a matter of a chemical process that has to be done to seperate the copper from the gold , can anyone let us know. We are talking industrial amounts of course.

For the silver seperation process we have also been told to add extra silver,
So the question for silver is the same as the above question for copper
thanks in advance

 

[orvi]

Helloi am new to the site.
I am currently working on an industrial sized agua regia machine processing up to 5kg per cycle currently we have processed gold of 92 percent and above on the machine with good results. We now have a client who is wishing to have us process gold that is coming directly from the mines at 60-70 percent, we expect the material that we need to be separated to have copper or silver in large amounts due to the location of the mine.

Starting with copper can anyone give a detailed account of how to remove excess copper,so far we have been advised to add more copper still to force a separation. Is this correct and also is this the only way to achieve the seperation. If there is a separate machine that Be bought for instance to convert the original 70 percent gold to a higher amount by removing the excess copper before moving to AR we would like to know. If it is just a matter of a chemical process that has to be done to seperate the copper from the gold , can anyone let us know. We are talking industrial amounts of course.

For the silver seperation process we have also been told to add extra silver,
So the question for silver is the same as the above question for copper
thanks in advance

If i guessed correctly, you talk about processing the metal, not the ore concentrates. Saying that you processed gold alloys with gold content above 92%. Natural electrum and raw gold is alloyed with silver. Not so much with copper, but there are few examples of natural copper-gold alloys.

With 60-70% gold and rest being silver, you will have hard time to digest it in AR.
Firstly, you need to know the exact composition of the raw alloy. What other impurities along with silver it contains.

Then you can inquart the metal with more silver to get somwhere around 25%, pour the shot into the water and digest it in nitric acid. This is a common practice in gold refining. You can also inquart with copper, but it takes more nitric acid to dissolve copper, than to dissolve silver (you will recover the silver at the end).

Some members dissolve finely divided karat filings in AR directly, but unfortunately, alloys like you are facing are the hardest to dissolve.

If you are well established company, than you will have no problem purchasing bulk nitric acid for good price. For the first run, you will need some pure silver in significant quantity, but later on, you will recover it by cementation with copper. And recycle indefinitely for the process. I will personally go with inquartation - it is well established bulletproof way how to refine AuAg alloys for centuries

 

[Xotom125]

If i guessed correctly, you talk about processing the metal, not the ore concentrates. Saying that you processed gold alloys with gold content above 92%. Natural electrum and raw gold is alloyed with silver. Not so much with copper, but there are few examples of natural copper-gold alloys.

With 60-70% gold and rest being silver, you will have hard time to digest it in AR.
Firstly, you need to know the exact composition of the raw alloy. What other impurities along with silver it contains.

Then you can inquart the metal with more silver to get somwhere around 25%, pour the shot into the water and digest it in nitric acid. This is a common practice in gold refining. You can also inquart with copper, but it takes more nitric acid to dissolve copper, than to dissolve silver (you will recover the silver at the end).

Some members dissolve finely divided karat filings in AR directly, but unfortunately, alloys like you are facing are the hardest to dissolve.

If you are well established company, than you will have no problem purchasing bulk nitric acid for good price. For the first run, you will need some pure silver in significant quantity, but later on, you will recover it by cementation with copper. And recycle indefinitely for the process. I will personally go with inquartation - it is well established bulletproof way how to refine AuAg alloys for centuries

Thank you very much for the fast reply yes we are a reputable company and have a vast supply of acids already, anything needed once we know what is is we will locate no problem
I will go through your message thoroughly and post a full reply soon
Thanks again

 

[nickvc]

Depending on the size of your operation , the equipment I believe is fairly expensive , there is a process to dissolve all your feed stock in one pass and have all the values back within 48 hours but for the details I will have to ask you to speak to our own 4metals who developed the process some time back , I believe he has retired or semi retired so it may well cost you a fair amount of money to tempt him to help but that’s between you and him.
Failing that Orvis suggestions are on point.

 

[Xotom125]

Hi Orvi,
I have done as much research as I can on the inquarting process, and I can see that this will be my best option.

My questions

1,
The process of inquarting that I have watched on YouTube has only been on A very small scale,
We expect to be inquarting 5kg at one time of gold that has come direct from a mine but with a content of 60-70 percent,

2,
How do you calculate what amount of silver/copper you need to add to part the gold from the unwanted materials

3,
Is there an industrial sized machine that can be bought so that the inquarting process can be done both on a larger scale and faster than those methods shown on YouTube etc the machine cost is not an important factor

Any help would be greatly appreciated
Thanks

 

[Xotom125]

Depending on the size of your operation , the equipment I believe is fairly expensive , there is a process to dissolve all your feed stock in one pass and have all the values back within 48 hours but for the details I will have to ask you to speak to our own 4metals who developed the process some time back , I believe he has retired or semi retired so it may well cost you a fair amount of money to tempt him to help but that’s between you and him.
Failing that Orvis suggestions are on point.

Hi nickvc,
Thank you for the info,
If it is possible to let me back how to get in touch with 4metals for advice ,as that would be very helpful

 

[nickvc]

Try using the messaging here on the forum .

 

[Xotom125]

Sorry I'm not good on the net where do I find the messaging option

 

[nickvc]

Its on your screen top right it looks like an envelope.

 

[kurtak]

. We now have a client who is wishing to have us process gold that is coming directly from the mines at 60-70 percent, we expect the material that we need to be separated to have copper or silver in large amounts due to the location of the mine.

Per the bold print - first we need to know how much copper &/or silver - it makes a difference

Silver becomes (somewhat) a problem when it runs 15% or higher as the silver forms a silver chloride crust on the surface which passivates the surface of the gold preventing the AR from reacting with the gold

Below 15% the silver remains "somewhat" a problem but becomes less of a problem the lower the silver content is

There are a number of ways to deal with that - (as the saying goes - there is more then one way to skin a cat)

The point being we need to know - in particular - the percentage of silver

Starting with copper can anyone give a detailed account of how to remove excess copper,so far we have been advised to add more copper still to force a separation. Is this correct and also is this the only way to achieve the seperation. If there is a separate machine that Be bought for instance to convert the original 70 percent gold to a higher amount by removing the excess copper before moving to AR we would like to know. If it is just a matter of a chemical process that has to be done to seperate the copper from the gold , can anyone let us know. We are talking industrial amounts of course.

If copper is the only other metal - &/or - silver is 10% or less - then you can go direct to AR

Again - more then one way to skin a cat - depending on silver content --- as in - may need to boil the AR instead of simply running it hot

For the silver seperation process we have also been told to add extra silver,
So the question for silver is the same as the above question for copper
thanks in advance

You are talking about the inquartation process here which is one way to skin the cat - but certainly not the only way

The point being - without knowing the silver/copper content it is hard to say which method of skinning the cat is best

Although inquartation (when silver is high) is one way to skin the cat (& the most common recommendation) it certainly is not the only method

Personally speaking - I would rather lower the silver content (with copper &/or more gold) enough that the silver chloride passivation is not a problem & thereby go direct to AR

Ether way - inquarting with silver - or lowering the silver with copper is going to use MORE nitric but when you buy your nitric (cheap) on an industrial scale it becomes irrelevant --- so at least in my mind it's 6 of one or half a dozen another --- which is why - if & when I can lower the silver & go direct to AR I prefer that

There is one other possibility - for going direct to AR - even with high silver content (provided it's not over 20 - 25% silver) --- this is just a theory of mine which I have never tried but have wanted to try

If you atomize the alloy to a powder of 300 minus mesh & are able to provide enough agitation to keep the "powder" suspended when adding it to the AR you should be able to dissolve MOST - if not all the gold thereby then allowing you to filter the silver chloride from the dissolved gold

The theory here being that by atomizing the alloy to an ultra fine particle size the particles don't have time to fully form that silver chloride crust on them preventing the AR from dissolving the gold - so (at least in theory) the gold should dissolve - leaving the silver chloride to be filtered from the dissolved gold

Also - the agitation should (at least in theory) prevent the silver chloride from "crusting" to the particles - thereby keeping the particles exposed to the AR to dissolve the gold

Between those two factors - you should be able to take even high silver content gold directly to AR by atomizing the dore/alloy

You can set up a system for atomizing your dore/alloy with an industrial pressure washer & a 55 gallon drum

Kurt

 

[Xotom125]

Thank you very much for the detailed reply,
I will go through your message and then I will have to wait until we get the first batch which will be in 3/4 weeks then I will come back to the forum,
For more great advice,