# Glycine method



## pp2kr (Jul 28, 2016)

Hello Guys

I'm just curious about glycine to leach gold. There are some papers around. Has anyone tried it?

Tks
Kleibe


----------



## Lou (Jul 28, 2016)

It works on flash plated gold.


----------



## pp2kr (Jul 28, 2016)

Lou
Flash plated gold...Could you explain it please?


----------



## FrugalRefiner (Jul 28, 2016)

It's gold that is plated very thin. Gold on contact surfaces, like fingers on RAM or plug in cards is typically 30 microinches. Flashplated gold might be more like 5 to 10 microinches, with 7 or 8 microinches being common.

Dave


----------



## pp2kr (Jul 28, 2016)

Good. Thanks for make it clear.
Anyway, someone tried it?
I would like to hear about it.


----------



## justinhcase (Jul 29, 2016)

That is quite promising.
I like the way Amino acids dissolve copper at room temperature, but need to be heated to 40-50 degrees to dissolve gold. Very handy! me like things you can target accurately.

Read more at: http://phys.org/news/2014-10-amino-acids-key-gold-leaching.html#jCp

"You have other amino acids which are even more selective and more powerful dissolvers of gold compared to glycine, but they are much more expensive, much more exotic," he also says.

Even better if it saves time it is worth the extra cost.an interesting line of research.


----------



## Lou (Jul 29, 2016)

Those amino acids usually have a S atom in them; they work faster but hold the gold even more tenaciously.


Gold likey the sulfur.

Of course you can use cyanide boosted glycine for the best of both.


----------



## justinhcase (Jul 29, 2016)

Lou said:


> Those amino acids usually have a S atom in them; they work faster but hold the gold even more tenaciously.
> 
> 
> Gold likey the sulfur.
> ...


As they are organic compound there should be some nice little microbe that would have evolved to digest them.
If the bond's are to strong for normal degradation.


----------



## Topher_osAUrus (Jul 29, 2016)

Lou said:


> Those amino acids usually have a S atom in them; they work faster but hold the gold even more tenaciously.
> 
> 
> Gold likey the sulfur.
> ...




:lol: 
On paternity leave a week and already its beginning to show.


----------



## anachronism (Jul 30, 2016)

Hello all

Glycine leaching. A excellent and forward thinking topic given the work that has been done into finding alternative "non toxic" leach alternatives to Cyanide. My practical observations below: 

Both Lou and Frugalrefiner mentioned limitations regarding plating thickness. The process has both similarities and fundamental differences to cyanide leaching and these differences can be utilised to make the glycine leach more effective for thicker plating therefore practicable for ewaste. It is this particular area that I am currently working on. Flash plated jewellery is easily stripped in the leach even in its raw form. Some minor adjustments already begin to strip finger board plating however more adjustment is required to compete fully with cyanide.

Do take into account that the glycine leach process is both temperature dependant, and flow dependant since the glycine molecule is larger than cyanide. Movement of the leach liquor is far more important in this leach than with cyanide. As such you need to build equipment to perform this leach, but nothing particularly technical and for those willing to invest it would in 95% of cases completely negate the requirement for AP provided that the plating thickness issue is dealt with. 

Extracting the gold from the leach is simple and performed either by using zinc to precipitate the metals or by using a cell. (Edit: or activated carbon)

Is it non toxic? Yes, compared to cyanide although treated with care cyanide is both remarkably effective and safe. Is it chemically dangerous? Of course- because you need to be running at pH 13, so appropriate safety precautions must be used. Is it for a home refiner? That's a good question, and I believe that it could be, for someone who has a knowledge of the processes involved so they can judge what do do when something doesn't behave the way they expect it to behave. 

Is the leach perfect? No naturally not. Nothing ever is otherwise everyone would be rich. For one thing the leach simply loves copper, so that needs to be taking into account. Using differing amino acids can and will make subtle differences with regards to selectivity however glycine is the simplest one to get started with. 

The whole process is in fact on a patent application on the internet for anyone to read. pp2kr I hope that goes some way to answer your original question.

Anac


----------



## pp2kr (Jul 30, 2016)

Hello anachronism
Thanks for clarify all the questions. Just search about the patent application but none found. Could you point me the rigth way?

tks


----------



## anachronism (Jul 30, 2016)

Certainly

http://www.google.com/patents/WO2015031943A1?cl=en


----------



## g_axelsson (Jul 30, 2016)

I couldn't see anything about selective leaching of gold over copper. On the contrary, according to Oraby 2014, "The selective leaching of copper from a gold–copper concentrate in glycine solutions" a glycine solution was used to selectively leach copper, both metallic and in various sulfide minerals. The gold ore without the copper could then be effectively leached with cyanide solutions.

Is there a way to passivate the copper so it doesn't dissolve in the glycine solution?

Göran


----------



## anachronism (Jul 30, 2016)

g_axelsson said:


> I couldn't see anything about selective leaching of gold over copper. On the contrary, according to Oraby 2014, "The selective leaching of copper from a gold–copper concentrate in glycine solutions" a glycine solution was used to selectively leach copper, both metallic and in various sulfide minerals. The gold ore without the copper could then be effectively leached with cyanide solutions.
> 
> Is there a way to passivate the copper so it doesn't dissolve in the glycine solution?
> 
> Göran



Goran


Passivating the copper isn't something I am currently having an issue with since the sample material to date doesn't involve relevant amounts of exposed copper due to the nickel flash plating between the gold layer and the copper substrate. If it was a cyanide leach, then the answer would be easy, namely 50ppm KCN making the cyanide effectively selective to the gold. Whether the same logic applies to glycine/alkali remains to be seen. 

That given, there are also reports that different amino acids behave differently in this process with some being selective. As usual the only information that is "out there" is the information people are willing to share for free as long as it doesn't affect a commercial advantage. Hence I would suggest that it would all need "rediscovering" if you get my meaning?

It requires lab conditions, and the correct equipment to produce any hard data and I suppose the logical question to ask then is that if the data was found, would someone be willing to share it themselves.


----------



## Grelko (Jul 30, 2016)

How much information did you need? :lol:

https://en.wikipedia.org/wiki/Biomining
http://www.nature.com/news/gold-digging-bacterium-makes-precious-particles-1.12352 (pubmed references near bottom)
http://www.pnas.org/content/106/42/17757

http://nopr.niscair.res.in/bitstream/123456789/17160/1/IJEB%2041%289%29%20967-971.pdf (Bio Recovery of Gold)

(Some microorganisms isolated from gold-bearing deposits a
re capable of dissolving gold; dissolution was aided by the presence of aspartic acid, histidine, serine, alanine, glycine, and metal oxidants)


http://ntur.lib.ntu.edu.tw/bitstream/246246/165242/1/63.pdf (You might need a degree in Biochemistry to understand this)

Glycine plays a number of roles during the synthesis of the Au core–Au–Ag shell NPs (nanoparticles) by controlling the
solution pH, altering the reduction potentials of gold and silver ions through forming complexes with metal ions (Au+and Ag+), minimizing the formation of Ag2O, AgCl, and AgBr precipitates, and stabilizing the thus-prepared NPs.
----------------------------------

Hydrometallurgy
http://www.mpsinnovation.com.au/wp-content/uploads/The-selective-leaching-of-copper-from-a-goldcopper-concentrate-in-glycine-solutions.pdf

http://www.scholarbank.nus.edu.sg/bitstream/handle/10635/16581/Pham%20Van%20Anh%20MEng%20ChBE%202009%20Gold%20Bioleaching%20of%20ESM.pdf?sequence=1

200 page PDF

(GOLD BIOLEACHING OF 
ELECTRONIC SCRAP 
MATERIAL BY CYANOGENIC BACTERIA AND ITS 
ENHANCEMENT WITH BIOOXIDATION )

http://www.minproc.pwr.wroc.pl/journal/pdf/1999/s55.pdf

(A heap consisting of an oxide gold-bearing ore c
ontaining 3.5 g/t of gold a
nd 14.0 g/t of silver was 
leached by solutions containing amino acids of 
microbial origin and thiosulphate as gold-
complexing agents.)

http://www.google.ch/patents/US5378437


----------



## pp2kr (Jul 30, 2016)

Hello
Well. I'm looking for start a ewaste company here. I just don't like to take all scrap and sending it to China or other place. Just looking for a new idea for precious metal recovery here, localy. 
The ewaste instigued me and I'm ready to start a chemistry's bacharelor course here so I have a bit long way to do. To be true: I would like to see 'real' experiments with glycine or some reports from the forum's users.

I'm collecting some ideas. The acetic acid was one of them. Glycine too. The guys from Canada are looking for a medium-large(min 20 t/m of e waste) corporate which isn't my case.  

So thanks all for the tips. I'm already reading as much as I can.


----------



## Deano (Jul 31, 2016)

anachronism has fairly well summed up the glycine situation.

What he has not mentioned is that the running of the leach at pH 13 will cause high dissolution rates of any zinc substrate used in gold plating.

This dissolution of the zinc layer will enhance the displacement rate of gold on the residual zinc layer.

You have the option of running the leach until all zinc has been dissolved or running the leach until all visible gold has been leached, decanting the leach and then coming back with a second fresh leach to scavenge gold from the zinc layer.

The gold tenor in the second leach is low and the re-displacement rate of the gold on any residual zinc is correspondingly low.

Deano


----------



## nickvc (Aug 1, 2016)

I suspect this method will need some really extensive testing and tweaking to get it to work as the user requires .
I think that should someone spend the time and money to perfect this they will have a commercial reason to do so and the scrap to run so don't expect any answers too soon, like most leaches I don't think it will be perfect and will not suit every type of scrap but with patience perhaps it will become a useful tool.


----------



## samuel-a (Aug 4, 2016)

I have on hand 3000lb of USP grade Glycine...  

Guess i'm gonna try it on the weekend.. :evil:


----------



## pp2kr (Aug 4, 2016)

Hello Sam
Tell us about your results!

pp2kr


----------



## samuel-a (Aug 9, 2016)

pp2kr said:


> Hello Sam
> Tell us about your results!
> 
> pp2kr



The short version... it didn't really worked.
Perhaps some dissolution of gold, but not enough to make it a viable option..


----------



## pp2kr (Aug 9, 2016)

Hello Sam
Post your long version or PM me please!

pp2kr


----------



## Craig A (Aug 19, 2016)

Sam,, I am currently building a leach tank(4000 Ltr) , heated and insulated for au reduction in Glycine. it would be interesting to share notes on ur failures,,, success's in your trial. Btw ,, we dont have a Cu problem, will be using Hydrogen peroxide for di-oxy,, CuSO4 ( 4 nMol) 1 Mol Glycine. running thru a carbon collumn . cheers


----------



## Fireflymetals (Jan 15, 2017)

There is a process for leeching using glycine, It looked a bit to me at a first glimpse as what they were aiming at.

A leeching process in the right PH range and at the right temp would work about that fast...

I will run this up in the lab tomorrow after my normally scheduled tomfoolery and see what happens. I think I have some glycine around...

Oh, and howdy guys, been reading for a while, never actually posted. I am rather impressed. I actually studied BioChem postgrad and well, ::coughs:: I hate to admit I am rather dodgy on actual knowledge of inorganic processing. I was more aimed at bio research, it has been lovely dusting off the cobwebs with you lads.

--L


----------



## g_axelsson (Jan 16, 2017)

Hi Fireflymetals and welcome to the forum.

Since your post mentioned glycine, I moved it to the glycine thread.  

There are a couple of papers written about glycine leach, but it seems it isn't so specific to gold only.

Some articles that can be found via sci-hub.ac : 
"The leaching of gold, silver and their alloys in alkaline glycine-peroxide solutions and their adsorption on carbon", E.A. Oraby, J.J. Eksteen, 2014, doi: 10.1016/j.hydromet.2014.12.015
"The selective leaching of copper from a gold–copper concentrate in glycine solutions", E.A. Oraby, J.J. Eksteen, 2014, doi: 10.1016/j.hydromet.2014.09.005

Looks like they are experimenting with it in Australia.

Let us know how it goes, so far I haven't heard anyone else trying glycime on the forum. 

Göran


----------



## g_axelsson (Jan 16, 2017)

I found open sources of two interesting papers.

The Selective Leaching of Copper from a Gold-Copper Concentrate in Glycine Solutions, E.A. Oraby and J.J. Eksteen, December 2014
The leaching of gold, silver and their alloys in alkaline glycine-peroxide solutions and their adsorption on carbon, E.A. Oraby and J.J. Eksteen, December 2014

Göran


----------



## Fireflymetals (Jan 18, 2017)

So, while I have tonnes of odd things in my kit, I did not have glycine...

I ordered it and it showed up today, was packing things up to wander into the lab and got a call informing me that there was no power in the building, so results will be delayed.

I played a bit with modeling software (it never answers anything but it gives you good basal parameters).

Long story short, the answer is delayed...

I was planning on answering in the other thread (thanks for moving this), I also found datum I will post over there.

In any case I will keep you all appraised of what comes from this, I expect to have the experiment up and running in about 48 hours.

For datum points however I will run down what the process is going to be:

I have 4 items up on this weeks bench.

For testing I have 40kg of tight trimmed gold fingers. (I hear people having problems sourcing volumes of items. I don't know why I found that part easy but there ya go).


Glycine leaching: Testing 500 grams, looks like I will be working in a 5l beaker and starting with roughly 1l of leechant (I over shoot needs due to the fact that I prefer big batches).
Recovery will be carbon and I will be doing a ash out, water plunge separation then tossing the remains in the small furnace for a melt out. I should get a lil bead out of that.

More as it comes along.

--L


----------



## nickvc (Jan 19, 2017)

I do not know if my input will help but you need to keep the solution heated, I think the temperature is fairly critical, and moving constantly to effectively strip the gold the same as using weak cyanide solutions, also from the little I understand of this method it will not load as much gold as cyanide so running a winning cell would allow the solution to be stripped of values and pumped back into the leach tank providing the movement, I'm not sure how the cell will react to the glycine so more may have to be added if it destroys some or all of it.
As I stated earlier this method has legs but the details at present are sketchy and I think testing is going to be needed to make the process work effectively, it also looks like this process will need specific equipment such as pumps to provide flow, a cell to strip the solution and almost certainly access to assaying to determine the effectiveness of the stripping and recovery, short version is this will not be for a hobbyist or home refiner until the process is proved.


----------



## Barstool miner (Feb 25, 2020)

I have a very specific and unusual Gold coated Silica ore . I use the Simple Glycine hydrogen peroxide leach at +/- 150 deg F. . I still have to figure out how 
to post photos. My pregnant leach has a reddish color to it giving me the impression of Colloidal Gold . I pass a red Laser beam thru the loaded leach and 
get a clear line thru the leach , no defusion of the light . My Activated Carbon
increases by 16 grams per 1pound in my carbon column when I have dried the loaded AC . I am unable to elute the Gold from the Activated Carbon (AC )
I am able to recover the Gold by destroying the Glycine leach, turning it into 
Chloride . I welcome new ideas


----------



## FrugalRefiner (Feb 25, 2020)

Barstool miner said:


> I still have to figure out how to post photos.



See Attaching Images or Files, Working with Attachments.

Dave


----------



## Barstool miner (Feb 26, 2020)

Thank you Frugal-refiner, for tips on posting pictures on this forum. I will have to study on it .


----------



## FrugalRefiner (Feb 26, 2020)

You can practice in the Private message area.

Click on "Private message" up toward the upper right corner of the window.

Then click on "Compose message" from the menu list along the left side.

You can type a little text, attach a couple of images, and hit the "Preview" button to see how it looks. Play with the "Place inline" button.

The PM editing screen is pretty close to the Post editing screen. If you click on the "Submit" button by mistake, it will just give you an error that you didn't specify a subject or a recipient (don't ask me how I know  ). I built a couple of my large projects that way.

Dave


----------

