I need help with EcoGoldex E

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FrugalRefiner said:
Yes, UV is 100% necessary.

Dave
There are different UV lights. Is there a specific UV light. (For inside)?

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FrugalRefiner said:
I've not had a chance to work with it yet, but there was a pretty good discussion in the Potassium Ferricyanide Leach thread.

I should qualify my statements that I am referring to straight ferro / ferri cyanide leaches. I can't say for sure the same applies to the Eco-Goldex products.

Dave
Thanks Dave!

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FrugalRefiner said:
I've not had a chance to work with it yet, but there was a pretty good discussion in the Potassium Ferricyanide Leach thread.

I should qualify my statements that I am referring to straight ferro / ferri cyanide leaches. I can't say for sure the same applies to the Eco-Goldex products.

Dave

Dave it depends upon the other chemicals in the mix.
 
Hello All, eco-goldex registered an account on this forum two years back, but was too busy to come here joining the discussion. recently quite a few of eco-goldex clients contacted us about some suggestions/comments of how to use eco-goldex E agent in e-scraps recycling/gold ore processing. i would like to use this forum to answer any question that our users might encounter in their application/test of our product.
we are the inventor/producer and supplier of eco-goldex series and equipment, our answers/suggestion are based on our own research and test results. we consider our answers are official and correct, at the same time,we acknowledged that there are still a lot of potentials yet to be explored of our product application.
answers on some representative comments/questions that were asked by clients:
Q: eco-goldex E/O series need UV light to make it work.
A: No, both eco-goldex E/O agent don't need any UV to make them work. as long as you follow our instructions:
  • 5% agent concentration in stripping solution;
  • stripping solution temperature maintains around 35-40oC;
  • maintain good dynamic in the stripping solution(make sure all materials in the stripping solution are equally exposed to stripping solution to avoid partial stripping);
then you should see very good stripping result.

Q: one of our clients sent us a comment about eco-goldex of its leaching features as cited here" The reason why the alternative leaches are not used commercially is, apart from the price of the active cyanide component being raised by the cost of the additives, the additives will dissolve many other metals which cyanide alone will not dissolve.
These metals will adsorb onto carbon but are not desorbed by a cyanide strip, so after a few cycles your carbon is clogged with metals which not only prevent gold loading onto the carbon but also prevent the loaded gold from being effectively stripped.
Basically you get only one strip from the carbon then you have to dump it, depending on the contaminants being loaded.
Always remember that these leaches are being sold to make money for the promotors, your interests are well down the line.
I would, in your case, investigate the possibility of accessing either ferro or ferricyanide availability.
Always keep in mind that all of the other leach formulations are going to be either or both of the above with added metal solubilising agents to keep the mystery going
"


A: both eco-goldex O agent and cyanide can dissolve metals(Au,Ag,Cu,...) in ores. any Active carbon (AC) used in precious metal adsorption has limited cycle period due to the decrease of its adsorption effectiveness. these downgrade of adsorption effectiveness is not because of the metals adsorbed on AC surface, but due to clays/lime scales (used for pH adjust). this is the reason that AC after elution must be reactivated using acid to wash any base metals/lime scales that might be still exist in AC.

the comment"the additives will dissolve many other metals which cyanide alone will not dissolve" is derived either the person who post the thread has no practical experience in cyanidation in gold ore leaching or use his/her imagination to mis-interpretation and accordingly misleading the readers.
Eco-Goldex O series agent can be used for loaded AC elution purpose, we don't need to use cyanide in any steps. users who need help may contact us in how to do elution.
 
"[Eco-Goldex O series agent can be used for loaded AC elution purpose, we don't need to use cyanide in any steps. users who need help may contact us in how to do elution]"

Why not post the elution process here? You may get more customers by making sure everybody understands the entire process.

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John (eco-goldex), we welcome your comments here. Some of our members have tried to provide some insight into how your products work, but information has been difficult to find. We hope you will help us better understand your products, as they may be helpful to some.

We do encourage open discussion on the forum instead of by PM or email so that everyone can benefit.

Dave
 
What seems to be some secrecy around the use of this product does put many off on it's use. We have to spend our money on the product to find out how it works instead of finding out before hand if we want to use it for specific jobs. Why not do some tutorials on how to use it, which version to use and provide some open discussion about the product. I am one of those who has looked else where for options because of the lack of information. It would help to have more than one person for world wide support I would think. This is one of those products I would like to try, it just needs to be more open about it's use before I would become committed to it.
 
Having retired after 40 years in the gold mining field I consider that I have enough experience as well as the technical background to comment knowledgeably about gold leaching methods.

Any leach which has thiourea as its active agent is to be wary of. Thiourea is listed as a carcinogen and any one who is intending to use a leach containing it should be made aware of the risks.

The gold thiourea complex has a positive charge and despite many people claiming otherwise, there is no magic adsorbent such as activated carbon which is effective in recovering these complexes .

This means that recovery of gold from these types of leaches is either by zincing or similar or by electrowinning.

Turning to the cyanide leaching method, if you have a method of leaching gold directly with a ferro cyanide/ferricyanide complex I can but say congratulations as you have managed to circumvent a lot of basic chemistry .

A solution containing ferro/ferri cyanide complexes cannot directly solubilise gold without the ferro/ferricyanide complexes first going through a disassociation step so that the leach contains a mixture of ferro/ferri complexes and cyanide complexes.

In order for the disassociation step to be initiated there must be an energy source to cause the disassociation to occur.

This can be either a chemical energy source such as a strong oxidant or a much cheaper catalysed reaction with UV.

Usually fluorescent lights or sunlight will cause this disassociation, the greater the UV level the faster and more complete the disassociation is.

Either way you will still have cyanide complexes in solution, this is easily shown by use of a cyanide probe.

With the pH around 11 or above, you will have the ferro/ferri counter ions all converted to ferric hydroxide in the oxidising environment.

This will result in the formation of ferric hydroxide particles which are the ideal size to block pores in activated carbon.

All modern gold orebodies will have base metals present to a greater or lesser degree.

The major problem metals in cyaniding are copper, lead and zinc.

Copper is a problem usually because of the high amount present in relation to the amount of gold in the ore.

The cyanide leaching of copper can be minimised by running low cyanide levels with just dissolved oxygen as the oxidant.

High cyanide levels and/or additional chemical oxidisers will ensure that high copper values are dissolved.

These copper cyanide complexes will load readily onto activated carbon, thus lowering the number of sites available for any gold to load onto.

Lead and zinc are solubilised in alkaline solution as hydroxides.

The levels solubilised are directly related to the pH of the solution and the Eh or energy of the solution.

If you raise either of the above you will solubilise substantially more of the metals.

Both of these metal hydroxide complexes will load quantitatively onto activated carbon but will not desorb quantitatively during a strip, so you get a build up of these metals on the carbon adsorption sites.

Ores which have higher levels of these metals will cause rapid failure of the carbon to adsorb further metal complexes or to desorb the loaded gold values. The only way to get rid of most of these metal complexes is with an extended HCl contact with 10 - 20% HCl or higher.

This acid strip is performed prior to the strip cycle as the carbon will be regenerated in a steam regeneration kiln after a number of strip cycles which is used for that particular mine.

An acid contact after regeneration will greatly lower the activity level of the regenerated carbon which is why this is not done.

Deano
 
Deano, your posts are always loaded with useful info, very much apreciated.

Considering the ferro / ferri cyanide option, just a brief look at the MSDS sheet gives me doubts about the ability to import and deploy it here. I think you mentioned before that purchase and transport are non restrictive. See MSDS sheet below.

Another issue is toxicity of the discharge which in the case of the "green product" containment (dams) would be required based on toxicity of the dissolved metals/minerals but the product itself is supposedly environmentally benign.

We want to run a 20 ton/day CIP plant but it has to be a cyanide alternative.
 

Attachments

  • SDS-POTASSIUM-FERRICYANIDE-en-20181030.pdf
    411.4 KB · Views: 19
K3Fe(CN)6 - this?

https://www.alibaba.com/product-detail/Potassium-Ferricyanide-with-CAS-13746-66_1186515012.html?spm=a2700.7724838.2017115.23.68f5340aBWYtED&s=p
 
The MSDS shown allows for the transport and storage of ferricyanide subject to the standard regulations, most of these are commonsense.

It should be noted that the MSDS is being updated with respect to fish and algae studies, I have never seen an occasion where the review findings wound back restrictions.

Tailings dams are subject to mining department regulations, usually the first thing an effective inspector will do is to test a water sample from the dam for free cyanide and apply the appropriate regulations from there.

As you said above, It is not correctly labelled as a green product either during or after use.

The reason why cyanide is still the gold leach of choice is related to its effectiveness and cheapness.

Acid alternatives such as halides have high costs for the chemicals as well as for the plant.

They also have health and environmental concerns.

Alkali alternatives suffer from high operational costs as well as high chemical costs.

The only system I know of which is viable is neutral pH hypochlorite leaching in vats.

Even that can be nonviable if sulfide levels are too high without commensurate high gold levels.

Mining companies are not stupid, if there were processes available for large scale in which the use if cyanide was avoided and a realistic profit made then those companies would use those processes.

The fact that cyanide is still the industry standard process sums up the state of alternative gold leaching technologies.

Deano
 
Thanks Deano,

Although my expectations are now much lower in regards to deploying one of the cyanide alternative “green complexes” I’m committed to carry out the experiment and make the examination with our specific ore. Our bottle roll tests with the Eco-Goldex product were actually very encouraging. Sulfide ores are typical of this zone, our ore having medium to high percentage of arsenopyrite, sometimes chalcopyrite. Most of the ores here are high in silver, sometimes in the form of electrum.

Just doing a little browsing I read where ferricyanide is low toxicity but the MSDS alert on aquatic life would still be a spoiler here, same reason for the ban on cyanide.

As a lixiviant for ores you recommend “potassium ferricyanide” is that right? Not ferro. The agricultural grade (white powder) or the industrial grade (red powder?) And to deploy the straight ferricyanide requires exposure to UV light? Any other considerations outside of the normal leaching processes for cyanide?

When using one of the cyanide alternative “green complexes” does using agricultural lime for pH adjustment cause scaling onto the carbon as Jon mentioned?

Back to lixiviation - after the bottle roll tests I set up a rustic agitation tank to test bulk samples (about 1/2 ton) with some equipment on hand, which ended up not working very well for reasons of mechanical design but I did manage to load some gold onto a small batch of carbon (about 8 kilos). Final recovery by elution was (still is) the plan as there seems like no alternative. So, my elution / EW experiment is still in progress, appearing to be the main obstacle, key challenge.

This week I’m setting up a pachuca tank to test bulk samples with the Goldex product, partly to see how well the tank works, basically a CIP cell with agitation by air only (air lift) - capacity about 1 ton (solids). The blower puts out about 1 m3 / minute. We have a basic lab setup, don’t have AA but we do have the ability to do fire assay and titration to track results which I’ll share here as they unfold.

I appreciate all the useful info. Our journey to the next phase of our operation has been educational. There are an untold amount of small / med scale mining operations around the world like ours that are still amalgamating whole ores. However, regulations are slowly forcing change upon us, mercury will become more scarce and governments will get more strict. I agree the big miners aren’t stupid, no argument about that but I do believe the industry will not adequately invest in the R & D to develop cyanide alternatives unless they are forced by regulation...which I confirmed yesterday when I came across this article.
https://www.linkedin.com/pulse/alta-2017-cyanide-alternatives-alleviation-panel-alan-taylor/

In the meantime the Chinese are experimenting with alternative leaches which may or may not lead to something better but at the moment it’s the only game to play and has been given the green light by the government here.

In regards to developing a small CIP process using a "green leach" I wonder sometimes if small scale (20 t/day) has some kind of advantage that would be considered impractical on a large scale - like stripping carbon for example, in batches of 50 kilos versus many tons, use alternative forms of pre/post treatment maybe. Obviously I’m thinking out loud here. I'm may not be technically qualified but I'm willing to help carry out the experiment if it's worthwhile. Someone needs to crack this nut.
 
Lime is usually used for pH control on a cost basis but it has possible downsides.

Usually there is not total dissolution of the lime and some fine particles escape the prescreen and enter the leach liquor.

These fine particles will adhere to activated carbon but do little to lessen gold adsorption.

In mines where the process water has high sulfate levels there can be precipitation of gypsum, this is in some cases a major blinding agent for activated carbon.

The above can be overcome by using caustic soda for pH control despite the extra cost in doing so.

Ferricyanides are basically oxidised forms of ferrocyanides but both have similar cyanide masses per unit weight so if the prices are similar then you would go for ferricyanide on a slender cost basis.

Both forms are subject to light induced disassociation in aqueous solution, my experience is that the effect is driven by the UV component of the light. The ferri form has a faster disassociation rate than the ferro form under identical conditions.

If you want a very basic system you would have a mixing tank where the solution was subject to direct sunlight. This tank would have the capacity to have a reserve sufficient for overnight additions if you wished to maintain constant cyanide additions.

The disassociation process rate is temperature enhanced but this is not a requirement if a mixing tank is used where time is substituted for temperature.

The pH of the mixing tank should be around 11, the same as in your leach circuit.

As the leach as above is a straight cyanide leach you can run it as any other cyanide leach, keep your dissolved oxygen levels up and practice good mixing.

You could also recover your gold by zincing as you have no added oxidants to give you problems.

Deano
 
about " ferricyanide" composition used in eco-goldex product.
there are quite a lot of discussions/guess about using fericaynide in gold leaching since eco-goldex disclosed this chemical in its MSDS. Please note, ferricanide is one of the many (6-7) chemicals we used in eco-goldex (O,E) production. these chemicals are roasted/melted under 700-800oC in special designed furnace, all these raw chemicals are mixed and melted together (and accordingly series complex chemical reactions) in such high temperature conditions. so essentially, eco-goldex (O,E) is a chemical compound (mixture of several chemicals and fused under high temperature), there is no chemical formula can be used to express its chemical features/ characteristics. after the high temperature fusing, ferricyanide reacted with other chemical, as a independent chemical, ferricyanide doesn't exist in the compound, so please don't try to use the ferricyanide to test (leaching) your gold ores/ e-scraps as this won't work.
 
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