KCN setup questions

[Rickthenewb]

Hi everyone, I am in the process of purchasing a 40 gallon setup to dissolve gold off of fingers and chips. I am getting my supplies from a company called Technic. I am curious to see what you guys think of my setup and if you have any comments to push me in the right direction.

I am using a combination of tap water, KCN and a Technic stripper solution
When saturated I am raising the pH to over 13 with NaOH, adding their additive "D" as they call it and increasing the temperature to 190F for 3 hours
At this point I plan on using the gold bug to recover the gold

I am really curious if I have too many steps or not enough and also is their a way to get any non-gold metals from the solution as well as neutralize the waste to save on disposal.
Also if anyone knows what these Technic chemicals could be I would love to save some money.
Thank you in advance

 

[goldsilverpro]

The question to ask Technic is not how to strip the gold (that is easy with their stripper) but, how, can you (without shipping the solution to them), simply recover 100% of the gold from their stripper (not so easy). That is the most important question.

 

[Rickthenewb]

I will be extracting the gold myself using electrolytic recovery, i.e. the "Gold Bug"

 

[shadybear]

Where is this place i havent seen it yet.

Probably Merlin Magic!

 

[4metals]

Their stripper is designed to strip the gold efficiently. A gold bug unit for plating out the gold will not work effectively if at all. Their gold is chelated in the strip and they know but won't tell the chemical used to break the chelating agent to free the gold.

Be careful with cyanide, it is not something to work with casually. Treating cyanide requires a 2 stage oxidation process. How will you handle rinsing your work? Since you know of Technic I assume you have some plating experience, since Technic usually only deals with corporations perhaps you own or work in a plating shop and these warnings may be for nothing. But if you are not prepared to do the job and treat the waste completely you are looking for trouble.

 

[jsargent]

Their stripper is designed to strip the gold efficiently. A gold bug unit for plating out the gold will not work effectively if at all. Their gold is chelated in the strip and they know but won't tell the chemical used to break the chelating agent to free the gold.

Why even add a chelating agent to a KCN leach? Seems the KCN would do just fine on it's own. However, if one is looking for a gold chelating agent I know that some resin beads use methyl mercaptan and thiouronium as noble metal chelators.

 

[goldsilverpro]

Is this super high dollar Techni-Strip AU? Very difficult to recover the gold from this solution. Not the best choice. This chemical is designed to strip the faulty gold plate so that the platers can replate the parts. It's not designed for recovery of the gold. Recovery can be done but, even if you can figure out how to do it, it's not easy. It requires some dangerous chemicals (a hydrosulfite, if I remember correctly) and, even then, 100% recovery is difficult. They used to sell sugar (sucrose) with a proprietary name, at a high price, that you could add to the solution and would supposedly allow you to plate the gold out. That doesn't work well either.

The Gold Bug has difficulty recovering all the gold, also.

You are trying to cut corners. There is no free lunch in this business..

 

[goldsilverpro]

Why even add a chelating agent to a KCN leach? Seems the KCN would do just fine on it's own. However, if one is looking for a gold chelating agent I know that some resin beads use methyl mercaptan and thiouronium as noble metal chelators.

He's not adding a chelating agent. This is a proprietary formula. I wouldn't necessarily call it a chelating agent that's in there but, whatever is in there prevents attack or cementation of the gold on the copper. For the same reasons, it prevents cementation from the addition of zinc. Therefore, unlike normal cyanide solutions, you can't precipitate the gold with zinc. I seem to remember that lead in the solution deposits a micro-thin coating on the copper (or the zinc) to prevent this attack. I believe there's a patent. A company named ACR held the original patents, I think. At one point, I think ACR sold a special proprietary chemical to help recover the gold.

If you are interested in the recovery of parts for replating, this is a great solution. If you want to recover the gold, however, it is about the worst thing you could choose.

 

[jsargent]

Why even add a chelating agent to a KCN leach? Seems the KCN would do just fine on it's own. However, if one is looking for a gold chelating agent I know that some resin beads use methyl mercaptan and thiouronium as noble metal chelators.

He's not adding a chelating agent. This is a proprietary formula. I wouldn't necessarily call it a chelating agent that's in there but, whatever is in there prevents attack or cementation of the gold on the copper. For the same reasons, it prevents cementation from the addition of zinc. Therefore, unlike normal cyanide solutions, you can't precipitate the gold with zinc. I seem to remember that lead in the solution deposits a micro-thin coating on the copper (or the zinc) to prevent this attack. I believe there's a patent. A company named ACR held the original patents, I think. At one point, I think ACR sold a special proprietary chemical to help recover the gold.

If you are interested in the recovery of parts for replating, this is a great solution. If you want to recover the gold, however, it is about the worst thing you could choose.

makes sense. The KCN puts the gold into solution then the mystery stripper stuff sequesters it somehow. I bet chelation is involved somehow. Just for grins i would try TR-6 on the stuff as it is sold as a "chelation bond-breaker" and we know how it drops just about anything out of solution.

 

[Lou]

Destroy the cyanide, evaporate it, and then give it hell at high temperature, perhaps in the presence of silver to collect. Nothing like heat to destroy tough-toothed chelators.

 

[Rickthenewb]

I called Technic and talked with there "Chemist". He affirmed that I initially use the technic stripper AU and then after saturation I add the "additive D" that turns our is a sugar. He then confirmed that it will be a two step process of removing the gold. First is through an electrolytic cell then by adding sodium hypochlorite (clorox) to the mix will preicipitate the rest. After siphoning off the cyanide I can then recover the left over gold. For the record I am not trying to cut corners I have been reading alot about this process and a lot of these posts as well as emailing several members for there input. Technic whether for good or bad has answered all my questions and I thought it would be good to bring to the forum for further input. I am not sure what else I can do to try and get something started. It seems everyone I talk to has a different way of doing these processes with no full explanation, and I am trying to find one or start out with one and work with it.

 

[jsargent]

I called Technic and talked with there "Chemist". He affirmed that I initially use the technic stripper AU and then after saturation I add the "additive D" that turns our is a sugar. He then confirmed that it will be a two step process of removing the gold. First is through an electrolytic cell then by adding sodium hypochlorite (clorox) to the mix will preicipitate the rest. After siphoning off the cyanide I can then recover the left over gold. For the record I am not trying to cut corners I have been reading alot about this process and a lot of these posts as well as emailing several members for there input. Technic whether for good or bad has answered all my questions and I thought it would be good to bring to the forum for further input. I am not sure what else I can do to try and get something started. It seems everyone I talk to has a different way of doing these processes with no full explanation, and I am trying to find one or start out with one and work with it.

Personally. I would follow Lou's advice and use evaporation and heat. That way there's no way to lose your gold and heat will destroy any chelator, due to their organic nature. This avoids the complications of electrolytic cells and iffy multiple step chemical processes. It's also cheaper than paying a premium for proprietary reagents.

 

[goldsilverpro]

A story about the use of Techni Strip Au. I once consulted for a guy that set up about a 100 gal tank of this stuff and ran tons of material through it in a plating barrel. He bought it in 100 or 200# drums - very high dollar. I tried to talk him in to using a simpler cyanide formulation, one that could be zinced out, but he wouldn't budge. When it came time to get the (lots of) gold out of about 2000 gallons of this solution, nothing really worked that well, even with Technic's guidance. He ended up bringing over an "expert" from France to get the gold out. The expert used an involved procedure that involved the nasty sodium hydrosulfite. It took days and still didn't work 100%. The moral of this story is, I would rather live in a dog's a**hole than ever use Techni-Strip Au again, in my entire life. It strips great but, oh, is it a b*****d to get the gold out.

However, Lou may have the answer. After evaporation, Lou, are you talking about incineration?

Rickthenewb,

I still think you're trying to take the easy way out. But, you'll end up paying the piper. For one thing, how will you know when all the gold is out? You certainly can't test it with stannous chloride.

 

[nickvc]

Rick can i strongly suggest you listen to GSP........he isnt trying to steer you in the wrong direction and if any one knows his stuff on cyanide its him.

 

[jsargent]

A story about the use of Techni Strip Au. I once consulted for a guy that set up about a 100 gal tank of this stuff and ran tons of material through it in a plating barrel. He bought it in 100 or 200# drums - very high dollar. I tried to talk him in to using a simpler cyanide formulation, one that could be zinced out, but he wouldn't budge. When it came time to get the (lots of) gold out of about 2000 gallons of this solution, nothing really worked that well, even with Technic's guidance. He ended up bringing over an "expert" from France to get the gold out. The expert used an involved procedure that involved the nasty sodium hydrosulfite. It took days and still didn't work 100%. The moral of this story is, I would rather live in a dog's a**hole than ever use Techni-Strip Au again, in my entire life. It strips great but, oh, is it a b*****d to get the gold out.

However, Lou may have the answer. After evaporation, Lou, are you talking about incineration?

Rickthenewb,

I still think you're trying to take the easy way out. But, you'll end up paying the piper. For one thing, how will you know when all the gold is out? You certainly can't test it with stannous chloride.

So what is this Techni-Strip stuff really? I've been to their website and of course there's no real info there. If it really does overcome the interference of higher electromotive series metals while leaching gold, it might be worth it for some troublesome ore I have which contains decent amounts of gold but high percentages of iron, silver sulfides, copper and lots of carbonate. The carbonate precludes economical acid leaching and re-cementation is an issue. Ammoniacal leaches might work but combining ammonia and silver is worrisome. Thiourea... no thanks. Mercury... no way. Cyanide would likely work but I live right over an aquifer and can't risk any cyanide spills. I have no doubt heat would destroy technistrip to release the gold so I don't see that as a problem.

 

[nickvc]

So what is this Techni-Strip stuff really? I've been to their website and of course there's no real info there. If it really does overcome the interference of higher electromotive series metals while leaching gold, it might be worth it for some troublesome ore I have which contains decent amounts of gold but high percentages of iron, silver sulfides, copper and lots of carbonate. The carbonate precludes economical acid leaching and re-cementation is an issue. Ammoniacal leaches might work but combining ammonia and silver is worrisome. Thiourea... no thanks. Mercury... no way. Cyanide would likely work but I live right over an aquifer and can't risk any cyanide spills. I have no doubt heat would destroy technistrip to release the gold so I don't see that as a problem.

The answer isnt what you want to hear from what i can gather....cyanide based stripper.

 

[Rickthenewb]

Thanx GSP, I am really just testing all the waters, I have not bought anything yet, I am just looking at all options. I am in a great situation here, a friend of mine who wants me to see if I can turn a profit by dissolving his scrap. If it doesn't work then I move on, but if it does I may have a small business I can run. So I am not really looking for an answer just trying to gather as much info as possible. With all this info I gathered I will not be using the stripper and maybe trying something different instead. So thank you everyone for your input it has really helped.

 

[goldsilverpro]

Don't get me wrong. I know of nothing on the planet that strips gold better and easier, without touching anything else, than Techni-Strip Au. For the plating industry, it's a marvelous product. It is very difficult to get the gold out, though, and there is no simple testing method to make sure you have got it all out. If someone could come up with a step-by-step that would get it all out, every time, I would change my tune. If that would happen, the only problem then would be the exorbitant price. I think there is a patent on it, however, and it could probably be made for 1/10 the price. When I get a chance, I'll look for the patent.

I think that there are still cyanide gold strippers on the market that will allow zinc powder to be used to drop all the gold. These were the precursors to TS-Au in the plating industry and I think they're still sold by several companies (I would check ACR, Enthone, Lea Ronal, etc. - any big company that sells gold plating systems). Maybe even Technic makes one. I would imagine they are cheaper than TS-Au. They will slightly etch the copper, however. From a recovery standpoint, that should be OK.

 

[Anonymous]

I found this in regards to Technistrip Au FYI http://www.mtl.umn.edu/safety/MSDS/MSDS%20Sheets/Strippers/Technistrip%20Au.pdf

 

[goldsilverpro]

I guess I was right about the lead being in it. Lead oxide = .22%