recovering gold from sodium cyanide.?

[anachronism]

Nitric, AR and sulfuric will injure you or kill you slowly.

Cyanide poisoning will kill you quick. And not all hospitals are equipped with its antidote.

Do not compare these common acids used for refining with cyanide.

I disagree - I'm not downplaying the dangers of cyanide, rather upgrading the dangers of the other acids and reagents. Not enough respect is given to the dangers of the common acids. We should treat the others with the same respect as cyanide and this doesn't happen enough.

 

[autumnwillow]

You may be surprised to hear that but cyanide is more common in recovery&refining than what you call "common acids used for refining".
Slowly or quick (killing) is not an argument.
But I do agree - If you're afraid of wolves, don't go to the woods.

The context of common is this forum, not outside this forum.
I am not arguing anything in the statement I made.
Your third line does not seem to make any sense. Does one have to be brave in order to deal with cyanide? I think that person should be knowledgeable not brave.

I am sorry I think I am tired but I cannot understand your statements.

 

[4metals]

Make the cyanide part of the forum private.

This could cause more problems than it is worth. How will we decide who to let in? How do you prove you are careful enough to be let in? Everyone assumes they are qualified and I believe the forum has more responsibility if we choose a member to join the private club and he or she ends up getting hurt.

Refining with chemicals or smelting is a grown up sport, the forum has made disclaimers about the dangers and every chemical or red hot furnace carries unique threats if used improperly. We expect our members to follow directions and we strive to correct any members posing questions if they are heading in the wrong direction.

In the end I think it is wiser to broach the cyanide subject with facts and good procedures than to bury our heads in the sand and make believe it doesn't exist. Cyanide is real, cyanide is widely used for refining, and we have grown enough as a forum to discuss the topic in a way that our members can use the information in a safe and environmentally sound way to process their precious metals.

 

[goldsilverpro]

Make the cyanide part of the forum private.

This could cause more problems than it is worth. How will we decide who to let in? How do you prove you are careful enough to be let in? Everyone assumes they are qualified and I believe the forum has more responsibility if we choose a member to join the private club and he or she ends up getting hurt.

Refining with chemicals or smelting is a grown up sport, the forum has made disclaimers about the dangers and every chemical or red hot furnace carries unique threats if used improperly. We expect our members to follow directions and we strive to correct any members posing questions if they are heading in the wrong direction.

In the end I think it is wiser to broach the cyanide subject with facts and good procedures than to bury our heads in the sand and make believe it doesn't exist. Cyanide is real, cyanide is widely used for refining, and we have grown enough as a forum to discuss the topic in a way that our members can use the information in a safe and environmentally sound way to process their precious metals.

I totally agree with 4metals.

 

[autumnwillow]

The very bad thing about cyanide is its fumes are not visible to the naked eye. Unlike acids where you could see or smell them and have time to go away. Cyanide is just fast.

An ORP meter and pH meter should be done on the test.

Whatever you guys decide on to I'll help with my experience on cyanide.

 

[anachronism]

If you're running cyanide at pH 11 you're not going to have clouds of HCN coming off the solution.

 

[goldsilverpro]

The very bad thing about cyanide is its fumes are not visible to the naked eye. Unlike acids where you could see or smell them and have time to go away. Cyanide is just fast.

An ORP meter and pH meter should be done on the test.

Whatever you guys decide on to I'll help with my experience on cyanide.

In general, the fumes are not as hazardous as most acid fumes, except those generated (HCN) by combining cyanide and any acid or from solutions with too low a pH. Fumes (mainly hot fumes) off of an alkaline cyanide solution can, however, produce a very annoying skin irritation called cyanide itch. I covered a lot of this is this post:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=24567&p=259896&hilit=cyanide+itch#p259896

I would guess that 4metals and I have much more experience working with cyanide, hands-on, than anyone else on the forum. I would guess that I worked with it daily for a period of 25 years. Sometimes with huge quantities, like 1000's of gallons. To me, it makes it safer to talk about it rather than to keep it a secret. When we only allow the elite to read about it, the ignorant or those not allowed to read about it could mess with it and end up dying.

When you know and obey the rules - don't eat it, don't drink it, don't swim in it, don't smoke, eat, or drink around it, or don't add acid to it - it can be far safer than concentrated sulfuric, strong lye solutions, or aqua regia.

For several years In the late 60's, I spent at least a day or two a week in electroplating shops in L.A., troubleshooting plating problems. At that time, there were many 100's of plating shops in L.A. Every shop had at least one (and usually, several) tank filled with a cyanide solution. Some held 1000's of gallons and as much as 1/2 pound of cyanide salts per gallon. I never heard of anyone being hurt or poisoned from cyanide in those shops. They were taught the basic safety rules and adhered to them. At the same time, there were many acid accidents where people were severely injured.

 

[4metals]

I never heard of anyone being hurt or poisoned from cyanide in those shops. They were taught the basic safety rules and adhered to them.

For years, if I couldn't find an experienced refiner to hire (which is difficult anyway to find, even today) I would advertise for workers with electroplating experience and train them to refine. I always found them to be well trained to be safe around chemicals, that is a good foundation to teach someone to refine.

 

[Shark]

My opinion from the aspect of a person who knows virtually nothing about cyanide, other than it can kill you.

Many who want to know how to use cyanide from a cost or efficiency stand point have two primary choices. They can go to someone (or a group of people) who are knowledgeable in it's use, or they can just continue to experiment on their own (as seen in the Eco-Goldex thread and other venue's like youtube). I have no plans at the moment to use any form of cyanide and I can see where it's use could be the preferred method for certain materials. In a month or a year, I might be wanting to try it so if I start studying now, I should be ahead of the curve when I am ready. Last year if some one told me I would be melting copper and running a copper cell I would not have took them serious, but I still done some studying on the subject. When 4metals started the post on smelting and the copper cell I was ready to give it a try, but I knew enough by then to be able to follow most of what he was saying. A few question and a bit more reading and I have been fairly happy with the results.

I would much prefer to learn from the senior members here than youtube. I don't much mind experimenting with things, but somethings are just easier, safer and quicker to learn with good help. If this thread gets started I will be reading very closely just in case I need to use the information sometime down the road.

 

[anachronism]

A brief summary of the methodology Jon is using, while he has posted it before, would be useful here to get this thread back on track.

4metals.

My apologies I missed this part of your post earlier.

In the interests of getting this thread back on track.

Stripping the gold from a cyanide leach.

The first option is zinc. This is all well and good until you have a leach accelerator and/or excess CN- and oxidant in the solution. At this point you can end up in a loop whereby your gold precipitates out and is redissolved into solution in a similar manner to having Nitric present in an AR solution. If you are using a CN leach with merely air as the oxidant then zinc works extremely well but many leaches contain H2O2 or MBNSS or other proprietory additions.

Second option is electrowin. You are passing your leach liquor through a cell which is stripping the metals from the liquor onto the carbon cathode. The advantages are that your liquor is then devoid of metals and can be processed back into your original leach with minimal degradation of the CN content of the leach. The cathode which contains the metals can be processed in AR and reused. The down side is the expense of the rectifier and electrowin cell itself but overall it is the most cost effective way of doing this.

Third option is activated carbon. You load the carbon with the metals in the leach and again pass the liquor back into the leach tank to carry on stripping metal. The upside again is that you return a stripped liquor which is reusable. The downside is that you then have to ash the carbon in a suitable furnace and process the ash. Your costs are activated carbon, and a good furnace.

Options two and three will both work using oxidants and accelerators in the leach. It's all a trade off you just have to pick the best overall solution to suit your budget and your base material.

For ALL the above an AAS is almost essential because you need to know when the tenor of your solution is high, or low respectively. Not to mention that you also need to know when it is completely spent.

I hope that helps in some small way guys. There is a lot more to this and I would be more than happy to contribute to the cyanide section that is planned to provide more clarity.

Jon

 

[autumnwillow]

I have a small refinery with one staff, I never let him work with cyanide since he makes small mistakes that will not work with cyanide. Small mistakes in cyanide can lead to death. He has five kids so I'm not risking it. I am always the one working with cyanide. I also get those itches even when just working with less than 5L of solution.

Just look at the mess other people make in this forum with acids, imagine that being cyanide. We may not have the time to tell them to stop, they may not have the time to post in the forum to ask what they did wrong.

Maybe I am wrong though, maybe we should give out the information since some members will attempt to do it anyway. And it is already being openly discussed here. A trial could be done to see, if too much mess is being generated then close that forum, if it works then that's good!

When I registered here 5 years ago, after reading so much I told myself that I should just hire a chemist with all these chemicals that I am not familiar with until I decided to study on my own. Being with chemicals is just about knowing what they are, what they can do and how to use them. Everything around us are chemicals.

 

[Lino1406]

I want to highlight two risks of cyanide:
1.Absorption through wounds of over 1g
2.Heavy than air cyanogene (CN)2 and/or cyanogene chloride (CNCl) with noxious smell, appearing on cyanide oxidation/chlorination

 

[muhammad Shahzad]

There are several answers. For example, Zn powder, Al powder/foil... ref:"30 and more recovery procedures"

Hi lino

Is there need to extract oxygen from cyanide solution to cementation gold with aluminium foil ?

Sent from my GT-I9060 using Tapatalk

 

[Lino1406]

If you mean dissolved oxygen it is negligible

 

[muhammad Shahzad]

If you mean dissolved oxygen it is negligent

you mean there is no need to pay attention for oxygen to Cementation gold in cyanide solution

Sent from my GT-I9060 using Tapatalk

 

[Lino1406]

The amount of dissolved oxygen is negligible hence the effect on cementation is negligible