# Elution of gold from strong base anion resin?



## TrickyDicky (Dec 6, 2021)

Dear All,

Does anyone know the best, easiest, most economical way to recover gold from resin, and once back in solution, the easiest way to get the gold metal?

The resin has to be reused so burning is not am option.

Many thanks if you can help.


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## Martijn (Dec 10, 2021)

Dissolve the resin in a solvent and filter.
Edit: and distill the solvent off to reclaim the resin.


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## Martijn (Dec 10, 2021)

Assuming the gold is in solid form...


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## TrickyDicky (Dec 10, 2021)

TrickyDicky said:


> Dear All,
> 
> Does anyone know the best, easiest, most economical way to recover gold from resin, and once back in solution, the easiest way to get the gold metal?
> 
> ...





Martijn said:


> Dissolve the resin in a solvent and filter.
> Edit: and distill the solvent off to reclaim the resin.


Many thanks for the reply Martijn, however the criteria was that the resin had to be reused, so dissolving or burning is not an option, I was thinking about elution with salt water?


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## Lino1406 (Dec 10, 2021)

No way to recover both gold and resin. The resin is lost in one way or another


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## TrickyDicky (Dec 11, 2021)

Hi Lino1406, thanks for your reply, I understand that some of the gold producers are using thiosulfate leach on to resin and then eluting the gold and re using the resin, however, they are keeping the process proprietary (secret). 

From what I understand the elution from the resin is a 2 part process, first any copper is removed by Ammonia solution (with a buffer) and then the gold is eluded with a salt solution..

This is what I need to find out...

Thanks


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## Lino1406 (Dec 12, 2021)

To see the problem, google:
Recovery of gold from pregnant thiosulfate solutions... a sulfur problem


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## Deano (Dec 12, 2021)

When you are looking at recovery methods the first thing you do is to look at what the mining industry uses.

There are literally hundreds of research papers available which are beautifully researched and written but all of them will have a fatal flaw in the processing which prevents them from commercial use.

Firstly, what methods are used in recovery by industry. They are activated carbon, ion exchange resin and zinc precipitation.

Zincing is a multi-step expensive process which the industry could not get rid of fast enough when activated carbon was introduced.

Activated carbon was a literal game changer for the gold industry, much simpler and cheaper than zincing.

Unfortunately it has poor loading characteristics when used for gold thiosulfate and thiourea solutions.

Ion exchange resin suffers from a couple of defects, it is expensive to buy and it locks up a lot of gold in the beads after several cycles of loading and stripping. The last thing you want is to have a large gold inventory locked in your resin.

Stripping is usually done with sulphuric acid and causes high resin losses from osmotic shock.

If resin is used with gold thiosulfate or thiourea there are also problems with precipitation of silver complexes and sulfur compounds.

Practically the only way to recover gold from thiosulfate and thiourea solutions in small scale is by zincing or electrowinning if the gold tenor in leach solutions is high enough, you will still get a lot of sulfur on your plates if you electrowin.

Deano


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## Lou (Dec 12, 2021)

I would definitely recommend against elution. Just burn the resin. Strong base anion exchangers are not hugely expensive...150-200/cubic foot. That puts the cost at probably less than a dollar an ounce.


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## TrickyDicky (Dec 13, 2021)

Hi Deano,

Many thanks for the reply, 

I have been studying this for a long time now and keep going down different avenues only to find that yes, there is a fatal flaw in most of the methods.

I don't have the option of spending lots of money, and the situation is complicated, I have fire assay tests done which indicate around 1.8ozt Au/ton plus other nice stuff and we have a lot of the ore. 

We have tried everything from heating, flotation, gravity separation, etc, and nothing has worked (except smelting with a collector metal, but to expensive to do).

Our last option is leaching, but cyanide is not an option for us.

Any help is always appreciated

Kind regards



Deano said:


> When you are looking at recovery methods the first thing you do is to look at what the mining industry uses.
> 
> There are literally hundreds of research papers available which are beautifully researched and written but all of them will have a fatal flaw in the processing which prevents them from commercial use.
> 
> ...


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## TrickyDicky (Dec 13, 2021)

Lou said:


> I would definitely recommend against elution. Just burn the resin. Strong base anion exchangers are not hugely expensive...150-200/cubic foot. That puts the cost at probably less than a dollar an ounce.


Hi Lou,

Thanks for the reply,

I need to reuse the resin to save costs for the moment and I am based in the Philippines so good equipment is not available and if it is it is extremely costly, However, I would appreciate any info on the ion exchangers.

Kind regards


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## Deano (Dec 13, 2021)

If you cannot use flotation to concentrate the gold values then you have two options.

The first is to either have your ore toll treated by someone who can use cyanide or to sell the ore to a similar operator.

The second is leaching with either carbon recovery or zinc precipitation.

If you are prohibited from using cyanide you can either use a ferro or ferri cyanide salt depending on local regulations, this is actually cyanide leaching but in most places the regulations have not caught up with this method.

Thiosulfate leaching with zinc precipitation is usually allowable but is more complex and more expensive than cyanide.

Depending on the ore matrix you can use acid thiocyanate with carbon recovery, if you have a carbonaceous matrix the acid cost will be high.

Again, depending on the ore matrix, you can use neutral pH hypochlorite leaching with carbon recovery or chlorine leaching also with carbon recovery.

The thiocyanate, hypochlorite and chlorine methods all have the downside that no metal parts of the plant can contact the leach solution.

You cannot use resins for recovery on the hypochlorite or chlorine leaches, these oxidisers will destroy the functional groups on the resin.

Deano


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## AJLnz (Dec 13, 2021)

Hi Deano
With flotation have you ever used IXOM products.
I have a refractory ore with 9,87g/t and cyanide gives 95% recovery within 2hr but it's restricted use here. (BLEG test)
Can you suggest another lexivant that will match cyanide maybe.
I have tested a Chinese product called Henan LV JIN that is suppose to replace cyanide but more green. Not very successfully.


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## TrickyDicky (Dec 14, 2021)

Deano said:


> If you cannot use flotation to concentrate the gold values then you have two options.
> 
> The first is to either have your ore toll treated by someone who can use cyanide or to sell the ore to a similar operator.
> 
> ...


Thanks Deano, 

This is a big help. Please could you be more specific with the ferric or Ferro cyanide salt to see if it is available here?

Kind regards


Deano said:


> If you cannot use flotation to concentrate the gold values then you have two options.
> 
> The first is to either have your ore toll treated by someone who can use cyanide or to sell the ore to a similar operator.
> 
> ...





Deano said:


> If you cannot use flotation to concentrate the gold values then you have two options.
> 
> The first is to either have your ore toll treated by someone who can use cyanide or to sell the ore to a similar operator.
> 
> ...


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## AJLnz (Dec 14, 2021)

TrickyDicky said:


> Thanks Deano,
> 
> This is a big help. Please could you be more specific with the ferric or Ferro cyanide salt to see if it is available here?
> 
> Kind regards


You could try the Chinese product if you working with actual gold element.
It can be recovered on carbon and then washed as per cyanide process.


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## TrickyDicky (Dec 14, 2021)

AJLnz said:


> You could try the Chinese product if you working with actual gold element.
> It can be recovered on carbon and then washed as per cyanide process.


I have a different 'Chinese Product' not the LV one, and it definitely leaches gold as i did a test in some old computer scrap printed circuit boards, getting the gold into solutiin is easy, getting the gold back out of solution is problematic to say the least. I need to know it works before trying on the 'ore' so I am not chasing my tail


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## AJLnz (Dec 14, 2021)

You need to deaerate the solution and then use zinc and a bit of lead acetate not lead nitrate as per cyanide then sulferic wash to remove extra zinc before smelt.


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## Deano (Dec 14, 2021)

All products coming out of China are a mix of ferro/ferri cyanides with various amounts of other metal solvents, chelates and oxidisers.

They will all dissolve gold along with other metals, they all work by having uv light from sunlight split the ferro/ferri cyanides into cyanide and ferric/ferro salts.

They will not dissolve more gold than straight ferro/ferri cyanide will but you will have the problem of lots of other metals in solution along with high levels of oxidisers, usually peroxides.

If you are working with small quantities of material then you can zinc out the gold for recovery.

Larger scale processing using carbon will give you major problems in two areas.

All the junk metals in solution will load on the carbon giving you low gold loadings on the carbon.

When you go to strip the carbon the high levels of junk metals will not allow the gold to be stripped in any meaningful amounts.

This means that your only realistic way to recover the gold from the carbon is to ash the carbon.

Why people would rather use a mix of chemicals containing one which is actually useful rather than just using the useful one is something I cannot understand, I put it down to marketing to people who do not have the knowledge to sort out the facts.

Always keep in mind that the Chinese sales people are only interested in selling their product so by making it sound as if it is the all dancing all singing answer to their needs, they prey on the uninformed at inflated prices.

Depending on the regulatory conditions where you are you can usually transport, store and use potassium ferrocyanide or potassium ferricyanide without restrictions.

Always keep in mind that uv light is essential to split the cyanide away from the complexes, this means nothing more than making up a solution of the potassium salt and exposing it to bright sunlight at pH 11.

You will also get an orange colour in the solution, this is the ferric part of the potassium complexes forming ferric hydroxide.

The formation of the ferric hydroxides is rapid if you use the potassium ferricyanide complexes, it is slower if you use the potassium ferrocyanide complexes as it takes time for the ferro salt to be converted to the ferro salt by the dissolved oxygen in the water.

The ferric hydroxide does not affect the leaching of the gold.

Deano


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## TrickyDicky (Dec 14, 2021)

Deano said:


> All products coming out of China are a mix of ferro/ferri cyanides with various amounts of other metal solvents, chelates and oxidisers.
> 
> They will all dissolve gold along with other metals, they all work by having uv light from sunlight split the ferro/ferri cyanides into cyanide and ferric/ferro salts.
> 
> ...


Thanks Deano,

Excellent info, if/when it works, I will buy you a pint or two...!

I will try and get some of the suggested chemicals, what sort of solution concentration do I need?

Kind regards


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## Yggdrasil (Dec 15, 2021)

Deano said:


> All products coming out of China are a mix of ferro/ferri cyanides with various amounts of other metal solvents, chelates and oxidisers.
> 
> They will all dissolve gold along with other metals, they all work by having uv light from sunlight split the ferro/ferri cyanides into cyanide and ferric/ferro salts.
> 
> ...


How long does the cyanide complex exist as a leaching agent after beeing subjected to UV light?
Can it be pumped from the surface into a heap for instance?
Or is this situation completely uncontrolable with leaching depth and so on?
Or is it so short lived that it has to be more or less be used in surface situation only?

Regards Per-Ove


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## TrickyDicky (Dec 15, 2021)

Deano said:


> All products coming out of China are a mix of ferro/ferri cyanides with various amounts of other metal solvents, chelates and oxidisers.
> 
> They will all dissolve gold along with other metals, they all work by having uv light from sunlight split the ferro/ferri cyanides into cyanide and ferric/ferro salts.
> 
> ...


Deano,

Can the gold from the pregnant potassium/iron salts solution be absorbed onto resin instead of carbon?


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## Deano (Dec 15, 2021)

At pH 11 the ferric complexes will precipitate out as ferric hydroxide leaving the cyanide in solution exactly as if you had started with sodium, potassium or calcium cyanide in the first place.

These cyanide complexes will last in solution just as long as standard cyanide complexes do and are used in leaches of all types in exactly the same way as normal cyanide is used, the only difference between the types is the method of formation.

Basically cyanide is cyanide, there are no differences apart from the starting materials and the requirement for the uv step.

Running the potassium ferri/o-cyanide complexes at 1 g/l will give you close to the mining industry standard of 1g/l sodium cyanide.

Deano


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## Deano (Dec 15, 2021)

If you are really keen on spending money needlessly then feel free to use resin instead of carbon, see my earlier post in this thread.

Deano


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## TrickyDicky (Dec 19, 2021)

Deano said:


> If you are really keen on spending money needlessly then feel free to use resin instead of carbon, see my earlier post in this thread.
> 
> Deano


Hi Deano, 
Haha, don't like spending money any more... however, I hear that eluting from resin is now possible as follows:
The strong base resin is used to collect/concentrate the gold from the leaching solution (I understand that Ambersep 21k can load 60g/L or 60ozt/cubic foot). The resin is then subjected to an ammonia solution (with a buffer) so strip any copper and then subjected to a solution of 2M Salt water with 0.1M sodium Sulphite, which strips the gold and renews the resin for anothe cycle. This process was devised in 2017. the testing team reused the resin 8 times with little degradation, however, I have been told that the resin gets locked after 8 cycles and has to be burned or fumed at that point to recover the PM's.

Your thoughts please mate

Kind regards


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## TrickyDicky (Dec 19, 2021)

Many thanks for the info..


Deano said:


> At pH 11 the ferric complexes will precipitate out as ferric hydroxide leaving the cyanide in solution exactly as if you had started with sodium, potassium or calcium cyanide in the first place.
> 
> These cyanide complexes will last in solution just as long as standard cyanide complexes do and are used in leaches of all types in exactly the same way as normal cyanide is used, the only difference between the types is the method of formation.
> 
> ...


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## Deano (Dec 20, 2021)

There is always a big difference in results between solutions made up in the lab and solutions generated in the real world.

With resin you will always get lock up of gold from process solutions, the only variables are how much lockup and how many cycles does it take.

The more contaminant metals you have in your solutions the faster and more complete lockup will be.

From a practical standpoint most operators use the industry standard of activated carbon, there are always good reasons why alternatives are not in commercial use.

Deano


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## nickvc (Dec 21, 2021)

In virtually all cyanide processes there is a decision to be made about whether the time , effort and costs outweigh the returns and the art is getting the balance right , the mining industry will have looked at all variables and picked the best compromise .
Many assume that cyanide is the process that works the best and in some circumstances it does but it rarely recovers all the gold available which is where the decision has to be made over return and the variables I listed above but if you can get that balance right it pays off .


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## TrickyDicky (Dec 21, 2021)

Deano said:


> There is always a big difference in results between solutions made up in the lab and solutions generated in the real world.
> 
> With resin you will always get lock up of gold from process solutions, the only variables are how much lockup and how many cycles does it take.
> 
> ...


Ok thanks Deano, I will consider using carbon in a column and compare to the resin. I will let you know what happens


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## TrickyDicky (Dec 21, 2021)

Yes I understand. Many thanks 


nickvc said:


> In virtually all cyanide processes there is a decision to be made about whether the time , effort and costs outweigh the returns and the art is getting the balance right , the mining industry will have looked at all variables and picked the best compromise .
> Many assume that cyanide is the process that works the best and in some circumstances it does but it rarely recovers all the gold available which is where the decision has to be made over return and the variables I listed above but if you can get that balance right it pays off .


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## TrickyDicky (Feb 2, 2022)

Martijn said:


> Dissolve the resin in a solvent and filter.
> Edit: and distill the solvent off to reclaim the resin.


Hi Martijn, thanks for the updated message, which solvent would be best, any suggestions? Thanks.


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## TrickyDicky (Feb 2, 2022)

Yggdrasil said:


> How long does the cyanide complex exist as a leaching agent after beeing subjected to UV light?
> Can it be pumped from the surface into a heap for instance?
> Or is this situation completely uncontrolable with leaching depth and so on?
> Or is it so short lived that it has to be more or less be used in surface situation only?
> ...


Hi Per,

Sorry i just seen your post... i will have a vat leach in IBC tanks and then all dumped onto a leaching pad with a filter bottom where the solution will be collected.


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## TrickyDicky (Feb 2, 2022)

Deano said:


> All products coming out of China are a mix of ferro/ferri cyanides with various amounts of other metal solvents, chelates and oxidisers.
> 
> They will all dissolve gold along with other metals, they all work by having uv light from sunlight split the ferro/ferri cyanides into cyanide and ferric/ferro salts.
> 
> ...


Hi Deano,

Happy new year .

Just a thought... can i use a UV water sterilisation colum (i believe it is a mercury vapor tube broad spectrum UV) to activate the Ferro/Ferri instead of sunlight?

And how long does the leaching solution stay active?

Thanks


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## Yggdrasil (Feb 2, 2022)

I believe there was a discussion earlier, a few years back and the conclusion was that 400nm UV light was sufficient.
My memory may be incorrect though.
It might have been 390 or 410.

Do a search on FerriCyanide, carbon cell and Anachronism as author.

Any broad spectrum UV in that region should be sufficient.
And as an answer to me earlier, Deano said that as long as it has been "activated"
The CN ion is ready for its job.
Regards Per-Ove


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