# need help removing mercury from gold



## Nite Hawk

Howdy folks,
Was wondering if anyone could give me some advice. 
A fair amount of the placer gold that you pan in some areas around here is coated with mercury. I believe that a fair amount of the mercury comes from the old old miners from years ago, but some people believe that some areas may have natural occuring mercury as well.
Many people that I know just "hit" their placer gold with a torch, and they say the mercury is instantly "gone". 
Well I know that is *very dangerous*, ( I do know people who have gotten mercury poisoning) so after careful research we built a retort out of cast iron.( places that sell retorts are almost impossible to find ).
We didn't know at first that one needed a crucible so the gold wasn't in contact with the cast iron, so the first time we tried it, the gold came out a "burnt" color.
We were then told we needed to put the gold in a crucible, so that is what we did.
We put a "tiger" torch on the retort and walk away for 10-15 minutes, and I would have thought that would be enough to get rid of any mercury but some of the gold still comes out a faint silver shiny color, and the odd piece is still has a "burnt" color, even though it is in a crucible. 
It has been suggested to use nitric acid to remove the mercury, however, I have been told that usually creates "sponge" gold, and alot of the buyers around here don't want to deal with "sponge" gold and either don't want to buy it, or at an extremely reduced price.
I don't have the time or the equipment to melt the gold down,( to take care of the "sponge" gold problem) I just want to safely remove the mercury, and have a "clean" product for the buyers so I can get a proper price, but a fair amount of the gold still comes out either slightly shiny, or slightly "burnt" in color.
Would appreciate any thoughts or advice...
Nite Hawk


----------



## qst42know

I have no experience with a retort but understand it is the proper way to deal with mercury. The silver and burnt color of your result is likely silver and base metal content. Using processes found here on the forum you can refine your resulting metals to a high purity to get the best price for your gold and get paid for the silver you recover.


----------



## Anonymous

Using a retort,or a fume hood and scrubber,is a must.There is one company that used to sell them in indonesia to "backwoods" refiners.I do not know the name of the company but from what I understand they are very inexpensive.


----------



## goldenchild

retort http://www.abprospecting.com/sitebuildercontent/sitebuilderfiles/amalgam17.jpg


----------



## oldgeek

There are retorts on ebay, fairly inexpensive. However, I do not have any experience with them.


----------



## Harold_V

There is no need for a crucible when using a retort. The metal in question is poured directly in the retort, which is then heated. It's a good idea to have a cooling coil attached, so the evaporated mercury isn't discharged to the atmosphere. If that's all you're going to do, you can do that without a retort. (Don't do it!)

Do not expect gold that has been subjected to a retort to retain its original color. It has been heated, and there are other substances present that will oxidize. 

Nitric acid _does not _create sponge from gold. The only exception to that is if the gold content is exceedingly low--less than 40%. Placer gold will undergo a washing in dilute nitric with little to no effect on its surface due to the (generally) high percentage of gold involved. In the end, it often looks cleaner.

You are seeking a way to do a specific thing. It might pay you to investigate changing course---you may find that you can refine the material and improve your profit margin-----unless you are selling placer gold at a premium. 

Harold


----------



## Nite Hawk

Thanks for the replies..
A small amount of the placer gold also has a black coating, some people say it is tungstun, and some say it is maganese coating. I have no idea what it is, but if it sets in water for a while it tends to lighten somewhat or sometimes disappear, but not always.
I have spoken to some of the other people who have recovered gold from the same area, and the ones who "*live dangerously*" and simply hit the mercury covered gold with a torch, and they tell me that their gold is "clean" with no faint silver shiny look whatsoever, so I am baffled unless our retort isn't getting hot enough somehow. I figure 10 minutes with a tiger torch should be getting it hot enough. Unless somehow the mercury isn't somehow leaving the receptical for the gold, and is not traveling down the nozzle, and once the receptical cools it is re-condensing back onto the gold??? Is this possible?? 
I also have wondered concerning the "burnt" color if somehow the cast iron from the retort might be somehow in some way be contaminating the gold somehow, and turning it a dark color even though it is setting in a crucible. I am baffled, and some of the other people I have talked to and shown the gold to, are baffled too.
I am not new to prospecting, but very "green" in the smelting direction, so I do not know what stannous is or what it is used for.
Appreciate your thoughts....thanks-
Nite Hawk


----------



## Nite Hawk

Harold -V
What is the process of using Nitric acid to remove mercury? I know my father used to use it in his jewelry work to determine if there were other metals in the gold, but I was just a kid at the time, and now my father is gone so I can't ask him anything about nitric acid.
I have heard that you have to boil the nitric acid to remove the mercury, is this true?
And of course I know there are safety issues with it as well, but I don't know basically anything about it, or how to handle it at all.
Appreciate your advice on the issue...
Nite Hawk


----------



## Harold_V

There are issues with dissolving mercury---but just like it is dissolved, it can be recovered (on copper), which is what I'd recommend. 

I have never tried dissolving--but I am of the opinion that it would dissolve readily in dilute nitric. Very little nitric would be required---and if you intend to recover the mercury (it's going to be difficult to get rid of in any form) the less you need to accomplish the task, the better. An excess of nitric will result in the unnecessary dissolution of the copper you'd use to recover the mercury. 

Heating the solution is always an option---so if it doesn't dissolve readily when cold, heating would be in order. In either case, you have fumes to deal with. Don't try this indoors unless you have a fume hood at your disposal. 

Don't allow any alcohol to get involved with the resulting solution. 

In regards to your experience with a retort, I found it was common for droplets of mercury to fall back on the retorted material as the retort cooled. Not much, but any is too much. For the record, all of my experience was in retorting dental amalgam, where a much greater volume of mercury was at hand. 

Harold


----------



## rusty

I used a cast iron brake drum with a large center hole to hold my retort which was wrapped with cerwool above the drum up to the water cooled portion of my condenser. 

My condenser was water cooled with the wet rag over the discharge spout just above the water level of my receiving vessel for the mercury, make sure the rag hangs into the water and not the end of your discharge pipe.

If the discharge pipe from the retort were under water the retort on cooling will suck water back.

As the retort was suspended from the cast iron brake drum the retort was heated from the underside, the material processed was dental amalgam. 

regards
rusty


----------



## Nite Hawk

I am starting to suspect re-condensed mercury falling back onto the gold why there is a slightly shiny coloring left. Any good thoughts on how to prevent that? I am wondering if a larger tube leaving the "condenser" of the retort might help, or maybe a shorter tube?
We do have a water jacket on the nozzle to cool the mercury vapor as it leaves the nozzle. Not sure if that would make any difference on how the gold turns out or not.
Any good thoughts on how to get rid of the "burnt" color? I tried soaking the retorted gold in vinegar, and it helped a lighten it a very small bit, but didn't remove all of it. 
In using nitric acid what sort of safety precautions would be recommended? about recovering the mercury from the nitric? Any good tutorials or books you can recommend??
thanks..
Nite Hawk


----------



## rusty

Nite Hawk said:


> I am starting to suspect re-condensed mercury falling back onto the gold why there is a slightly shiny coloring left. Any good thoughts on how to prevent that? I am wondering if a larger tube leaving the "condenser" of the retort might help, or maybe a shorter tube?
> We do have a water jacket on the nozzle to cool the mercury vapor as it leaves the nozzle. Not sure if that would make any difference on how the gold turns out or not.
> Any good thoughts on how to get rid of the "burnt" color? I tried soaking the retorted gold in vinegar, and it helped a lighten it a very small bit, but didn't remove all of it.
> In using nitric acid what sort of safety precautions would be recommended? about recovering the mercury from the nitric? Any good tutorials or books you can recommend??
> thanks..
> Nite Hawk



Can you add some pictures of your retort this may help in solving the problems your encountering.


----------



## Nite Hawk

unfortunately my camera "died" a couple of weeks ago, and at this point has not been replaced. The "condenser" is made out of 2 threaded cast iron pipe caps with a double threaded mid-section. The one pipe cap has a hole drilled into it, and a copper pipe that has been flared inside the cap, and it curves up and through a "water jacket" that one can attach a hose to for cooling purposes.
I am thinking that possibly the copper pipe may possibly be too small in diameter, and possibly should be larger in diameter to allow a freer flow of vapour from the "condenser".
I can't remember exactly the diameter of the copper pipe, but I am thinking it was 1/4 to 1/2 inch diameter, and I am leaning towards 1/4 ". It is fairly large overall, approximately 3 feet long.
Sorry I don't have any pictures...
Nite Hawk


----------



## prospect88

Nite Hawk, first off copper should not be part of a retort for mercury, it will attach itself to it and stay there. I use a small retort but it was built out of stainless steel and the condenser is a small diameter tube that passes through a 1 inch square tubing that is the water jacket, i will see if i can get a picture uploaded later in the week. I have done many, many test using nitric to clean up mercury, it does not make sponge gold it is beautiful bright crystals , use 20% nitirc and 80% distilled water, must be distilled no chlorine or you will form chlorides that you don't want, heat gently and watch bubbles form around the gold mercury amalgam, if the bubbles stop and the gold does not look clean add a bit more nitric. when it stops working pour off the water nitric solution and rinse the gold with distilled water, pour off again and repeat again to make sure its clean. Always wear rubber gloves as you don't want the acid on your skin, especially once it has mercury in it. Clean up the acid with either zinc of copper and the mercury will drop back out, neutralize the acid with caustic or soda and the base metals will drop out .

prospect88





Nite Hawk said:


> unfortunately my camera "died" a couple of weeks ago, and at this point has not been replaced. The "condenser" is made out of 2 threaded cast iron pipe caps with a double threaded mid-section. The one pipe cap has a hole drilled into it, and a copper pipe that has been flared inside the cap, and it curves up and through a "water jacket" that one can attach a hose to for cooling purposes.
> I am thinking that possibly the copper pipe may possibly be too small in diameter, and possibly should be larger in diameter to allow a freer flow of vapour from the "condenser".
> I can't remember exactly the diameter of the copper pipe, but I am thinking it was 1/4 to 1/2 inch diameter, and I am leaning towards 1/4 ". It is fairly large overall, approximately 3 feet long.
> Sorry I don't have any pictures...
> Nite Hawk


----------



## Nite Hawk

prospect88
Maybe that is part of the problem, the mercury is attaching itself to the copper tubing and then when cooling some maybe re- settling back into the "condenser???" or not allowing the mercury to escape down the nozzle at all and possibly building up in the nozzle???.
Very interesting thoughts !!
I was told when using Nitric acid one had to "boil" it, to remove the mercury. Is that true, or will nitric acid simply remove the mercury by simple contact?
You mentioned soda to neutralize the nitric, are you refering to common baking soda?? You also mentioned when one neutralized the nitric with soda the base metals will drop out. what do you mean by that??
The gold that we have been dealing with is placer of course, alot of it is around the size of sesame seed size, not quartz gold, but I am sure the effect of the nitric would be the same.
Do you think the nitric would remove the "burnt" coloring, that we are sometimes getting after retorting?
Where can one find nitric acid?
I would like to continue this discussion a bit further, but am having computer problems, and having to use the library computer ( which is only open 2 afternoons a week). Hope to be back online hopefully tonight, but it is hard to tell with computers!, so it might be a bit before i can discuss this further.
Thanks for the info...
Nite Hawk


----------



## Nite Hawk

Computer is back up and running! I would definately like to see any pictures you have of your retort..
NIte Hawk


----------



## adam_mizer

Looking through the threads, this one stopped last April and you guys did not post any pictures as you said.

We are working the creek and pulling out much old placer in mercury.
I have nitric on hand, and a retort would cost approximately $150.
Wanted to try the nitric but had some questions.

Mentioned above was 20% nitric (but does not state if it was 70% technical to start)?
If it were now its less than 20% nitric in the distilled water.

Is this percentage nitric to low to effect the silver?
There is a lot of silver in the placer gold.

Is the retort the best method?


----------



## qst42know

A retort would be needed to separate the silver from the mercury after cementing with copper anyway. So nitric wouldn't solve the problem just create another.

Have the retort cap threaded for a steel hydraulic line and get rid of the copper tube. Tapered threads and a compression fitting should seal it up well.

Don't count on 10 minutes with any torch to do the job, use a gas cook stove you will never eat from or a lab type Bunsen burner for as long as it takes. When you think you are done give it some more time just to be safe.


----------



## NoIdea

Just a quick tip for mercury vapour, the exit from the condencer unit should pass through a vapour/air filter before entering the atmosphere, use any of the three that follow, sulfur lumps or filter paper impregnated with sulfur, aluminium shavings, iodine impregnated filter paper or zinc shavings, im sure their are more butt that should do.

Be Safe

Deano


----------



## Palladium

Just something interesting !

http://silverprospector.com/assaying/au-hg-amalgamation.html


----------



## Barren Realms 007

Palladium said:


> Just something interesting !
> 
> http://silverprospector.com/assaying/au-hg-amalgamation.html



That was a nice find.


----------



## JYOU18

Leave the heat on it for 30-40 min to an hour.


----------



## saadat68

rusty said:


> If the discharge pipe from the retort were under water the retort on cooling will suck water back.


Hi
In all of diagrams discharge pipe is under water. can you explain more ?

http://uupload.ir/files/pi3b_image39.jpg


----------



## Topher_osAUrus

That isn't underwater in the picture.

If it were underwater, it could/would easily suck back water into the retort, which Im sure would then make for a very interesting show..


----------



## FrugalRefiner

The discharge end of the pipe should not actually be under water. As others have mentioned, if the heat to the retort ended and the discharge was under water, it could draw water back up into the very hot retort and cause a steam explosion.

The end of the discharge pipe should be a little above the water level in the catch vessel. It should then have a small piece of thin leather, or cloth, or something similar attached to the end that hangs down just below the water level. The reason you want this is to keep any stray mercury vapors from escaping into the air. If the heat is removed from the retort, as the pressure drops in the retort, and it tries to draw water up into the condenser, the leather or cloth will break the vacuum and allow a bit of air in instead of drawing water up into the retort. At least, that's the principal.

In your diagram, you show air going into the jacket of the condenser. Air won't cool it much. Water has a much higher capacity to cool the vapors from the retort. Cold water should come in at the bottom of the condenser and exit at the top.

Dave


----------



## DennisW

A simple trick taught to me by an old prospector was to take a fairly large potato cut it in half and hollow it out enough to hold the amalgam then securely tie the potato pieces together. Boil the potato until cooked and do not remove the lid of the pot until it had cooled completely. The gold will have formed a neat button in the middle of the potato and the mercury vapour is trapped by the skin of the potato and can be recovered by mashing and washing away the pulp in cold water


----------



## kjavanb123

DennisW said:


> A simple trick taught to me by an old prospector was to take a fairly large potato cut it in half and hollow it out enough to hold the amalgam then securely tie the potato pieces together. Boil the potato until cooked and do not remove the lid of the pot until it had cooled completely. The gold will have formed a neat button in the middle of the potato and the mercury vapour is trapped by the skin of the potato and can be recovered by mashing and washing away the pulp in cold water



Good advice thanks


----------



## kurtak

kjavanb123 said:


> DennisW said:
> 
> 
> 
> A simple trick taught to me by an old prospector was to take a fairly large potato cut it in half and hollow it out enough to hold the amalgam then securely tie the potato pieces together. Boil the potato until cooked and do not remove the lid of the pot until it had cooled completely. The gold will have formed a neat button in the middle of the potato and the mercury vapour is trapped by the skin of the potato and can be recovered by mashing and washing away the pulp in cold water
> 
> 
> 
> 
> Good advice thanks
Click to expand...


This is - NOT" - a safe method for removing the mercury from amalgam :!: :!: :!: 

Kurt


----------



## FrugalRefiner

kjavanb123 said:


> DennisW said:
> 
> 
> 
> A simple trick taught to me by an old prospector was to take a fairly large potato cut it in half and hollow it out enough to hold the amalgam then securely tie the potato pieces together. Boil the potato until cooked and do not remove the lid of the pot until it had cooled completely. The gold will have formed a neat button in the middle of the potato and the mercury vapour is trapped by the skin of the potato and can be recovered by mashing and washing away the pulp in cold water
> 
> 
> 
> 
> Good advice thanks
Click to expand...

That is horrible advice! While _some_ of the mercury will be caught in the potato, some will escape. Then you have a toxic mess of mercury in the water and the mashed pulp. I know it used to be done in the past, but we know better now.

Dave


----------



## galenrog

DennisW said:


> A simple trick taught to me by an old prospector was to take a fairly large potato cut it in half and hollow it out enough to hold the amalgam then securely tie the potato pieces together. Boil the potato until cooked and do not remove the lid of the pot until it had cooled completely. The gold will have formed a neat button in the middle of the potato and the mercury vapour is trapped by the skin of the potato and can be recovered by mashing and washing away the pulp in cold water



No. Just....No.

Time for more coffee.


----------

