Glycine method
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It works on flash plated gold.
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
Dave
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.
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.
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.
Gold likey the sulfur.
Of course you can use cyanide boosted glycine for the best of both.
As they are organic compound there should be some nice little microbe that would have evolved to digest them.Lou said:
If the bond's are to strong for normal degradation.
Topher_osAUrus
Well-known member
Lou said:
:lol:
On paternity leave a week and already its beginning to show.
anachronism
Well-known member
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- May 31, 2016
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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
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
anachronism
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Certainly
http://www.google.com/patents/WO2015031943A1?cl=en
http://www.google.com/patents/WO2015031943A1?cl=en
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
Is there a way to passivate the copper so it doesn't dissolve in the glycine solution?
Göran
anachronism
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g_axelsson said:
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
Well-known member
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
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
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.
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.
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
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
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.
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.
