# gold amalgam thread



## machiavelli976 (May 12, 2010)

hello again ! just a few days ago i have bought about 30 gold plated russian old watch cases and some plated bracelets. after removing the brass with nitric and boiling in hydrochloric ( rinsing between of course) i 've noticed enough dirt and metastanic grains among the foils. i decided to make an amalgam to get rid of dirt and so.. the mercury expelled a lot of misery easy to be washed with tap water. now the mix beeing clean i'd like to know what acid would you use to dissolve the mercury. have anyone done that ? i shall try again nitric to see any green colour if appear. could that mean some copper or nickel was expelled by mercury from gold alloy? the foils are quite thick and brittle and i would wait few more days to be penetrated. thanks for any comment and advice.


----------



## kalay (May 12, 2010)

While I do not condone using mercury in any way,I would suggest you distill off the mercury then you could reuse it.


----------



## 4metals (May 12, 2010)

The majority of the mercury can be remove by squeezing it through a chamois cloth. I remember way back when I first saw it work I was amazed that the mercury came flowing through the cloth leaving the gold behind. The remaining mercury can be dissolved in Nitric but if you have a lot a retort is the way to go.


----------



## nickvc (May 13, 2010)

Personally a small amount of dirt in the mix wouldnt tempt me to use mercury,Harold,s advice im sure would have been to incinerate and further acid rinses, im sure he is right,failing that a straight dissolution in AR and a filter would have been my way and if the gold was dirty to re refine the precipitate.


----------



## machiavelli976 (May 13, 2010)

thank you guys. there are several reasons for chosing Hg digestion: the items were pretty filthy (sounds weird ha ha..) and hard crusted, bracelets mostly. the foils were as brittle as they were thick and made a lot of gold dust , silly to wash and recover and i assume i can recover the Hg from nitrate salt by cementing somehow with a reactive metal. iron perhaps !? or replacing with NaOH.


----------



## Harold_V (May 13, 2010)

machiavelli976 said:


> thanks for any comment and advice.


I'm happy you said that. Otherwise I'd have ignored your post. I find it most disturbing.

Lose the idea of using mercury. It serves NO purpose, especially in this instance. Consider that if the gold in question is so dirty that you feel mercury would be to advantage, it likely would be too dirty to amalgamate. Mercury has NO place in refining. It can be used to advantage for recovering values from nature, however. Note that I do not promote the idea. 

In order to finish the results after processing with nitric, you should incinerate. You can then give the remains a treatment with HCl before digesting with AR, for eventual recovery of the values. I highly recommend you do that now. 

In this instance, you screwed up. You should have incinerated these items at the outset. That would have liberated the majority of troublesome contaminants that might be present. 

When, oh when, will you guys ever start incinerating? Dirty objects like you described beg for that procedure. Eyeglasses, too. 

Harold


----------



## machiavelli976 (May 13, 2010)

thank you Mr.Harold ! i have expected to receive some kicks and i'm glad you have done it. as i've said in some past topic i have no great financial purposses and i like to play somehow away from the right path. despite the disturb of this posting i hope there will be also some benefit for the further readers regarding your dissagreement.


----------



## Oz (May 13, 2010)

machiavelli976 said:


> i assume i can recover the Hg from nitrate salt by cementing somehow with a reactive metal



It will cement on copper.


----------



## WIZZARD (May 13, 2010)

Yep!\\



> machiavelli976 wrote:i assume i can recover the Hg from nitrate salt by cementing somehow with a reactive metal




You should know as most will tell you mercury is like working with TNT, you need to be an expert and cover the all the bases which are serious.
30 years ago I was working with a lab off and on that recovered mercury from industrial batteries. They had a retort over 15 feet long, a ignition chamber holding hundreds of pounds of mercury carrying waist. The unit would run at night, when no one was a sealed dedicated room , and shut off with a timer, so by morning it was cooled down. Even with their expertise the level of safety was beyond any thing most can imagine. They would run the fist retort product through a mercury press. The press was a bolt together set of pipes, fittings and filter paper and layer of chamois. The mercury would be placed in the chamber and locked down in a enclosed second safety chamber. A tire valve was at top of first chamber holding the mercury and air pressure would be run through the valve unit the mercury would be filtered through paper and chamois. They would run the filtered mercury through a much smaller retort three more times to get, three times distilled mercury. They were zoned, licensed and graduates of a well known mining school. They have passed on as they were old times back 30 years ago. 

I know Harold is most likely reacting with much concern and we all should, as TNT will not hurt you unless you have some. So the idea is the same mercury won't hurt you unless you have some. 

Just remember there are a lot people who read this and the warnings can not be stressed enough about this stuff. I jumped in because I've been around it and the experts who dealt with it, and learned that if you don't respect it's danger, ..............................*

WIZZARD


----------



## machiavelli976 (May 13, 2010)

thank you Wizzard for your concern but i have no intention to get rid of Hg boiling it . perhaps i will make some Hg(ONC)2 with the remain nitrate for a little fun. besides i've handled a lot of dangerous chemicals in this life and i am still alive. the years spent in a chemical plant and in a chem lab make myself sure of what i'm doing.


----------



## WIZZARD (May 13, 2010)

machiavelli976

With that said;

When using mercury, the two surfaces of your material and mercury need to be as clean as possible. Sodium hydroxide has been the choice of those using it. Got silver or base metals the pre nitric should get most of them. Your loaded Hg can be filtered with a press, and residue on top of filter will be goodies and some Hg. 30 years ago I used 50/50 DH2O to nitric to place the mercury from the filtered cake/gold in solution, from there you will refine gold as normal. Al or Cu sheets will collect the Hg back to flowing mercury from the nitric solution. Not all of it but most, I liked Cu, keep it sealed to be reused.

The time the Hg is in contact with gold is important as Hg covers gold and swallows it, as it is called, however Hg will put gold and base metals into mercury solution over a period of time or faster with micron gold. When this happens the mercury will need to be retorted. I have produced needle gold from Hg/Au. Looks like long eight sided hollow crystal needles. The brightest gold I've ever seen. Been a long time ago, so its 8 sides more or less, it is still very bright. 

It's been said that mercury will not pick up PGM's. There is one condition it will. When sodium metal (opps a dangerous one) is properly mixed with mercury you will have sodium of mercury, only 3% Na dry powder with dry Hg. Got to be done with absolute dry controlled conditions. It looks like white metal crusty chunks. When in presents of Cu, like in a copper pan, it will pick up PGM/Au and stick to side and bottom of the copper pan within the Hg clinging to the sides. It has short life reaction when mixed with ore finely divided the Hg will reacte when mixed with water (the mixture will not explode just fizz a lot as the alloy of NaHg is very low). Heavy rubber gloves, hood, over closed water tank, ect. The gold and PGM's have been captured by the mercury and the amalgam is separated from the gauge and placed in DH2O, by scrapping the copper pan with a hard chunk of flat rubber you will collect the amalgam. As amalgam becomes pregnant its color becomes more gray and it becomes flatten and not round ball like. You will notice gray particles dropping out of the Hg when parted form the mixing stage, as the jazzed up Hg gives up the reaction of the sodium. The gray stuff falling out of its clutches are PGM's and some other elements. So your still faced with more parting. 

Hope this is more what you were thinking?

I still think working with it is tricky business. When in the military I handled some very tricky stuff too, and it's kind of like that kind of respect. Kind of...........

WIZZARD


----------



## Anonymous (May 31, 2010)

I know that the use of mercury is not favored on the forum, most of you know that my friend in Saskatchewan purchased a building on back tax's and that this building was used previously as a dental clinic.

And that I did not know enough to leave the vacuum filters behind, as it is I have several case's of them, they all have about 2 inches of black sludge laying on the bottom. Knowing now what I do is that most refiners will not handle amalgam and these nasty filters. So I'm stuck holding the bag, in order to dispose of the contents in a favorable responsible manor, my first plan of attack is to run everything through a retort reclaiming any possible mercury.

Next step would be incineration once I'm positive the mercury has been driven off. Then processing for any precious metals that may be present.

I still have to build the condenser for the retort I made this afternoon and thread some holes for the screws that will secure the lid, yes there's a gasket under that lid. And I'll use pipe dope on all my threaded joints. 

Everything has been constructed from iron.

The collar for the condenser is going to be around 18 inches long, water supplied from the bottom end to assure that the column is full at all times, your comments an suggestions appreciated.


----------



## Harold_V (Jun 1, 2010)

Depending on the intended temperature, your choice of material may not be a good one. If you approach a dull red heat, you can expect the steel you used to oxidize. Short term it may serve well enough, but the best choice would have been what you mentioned---iron---like in cast gray iron (ductile would be even better). It tolerates being heated much better than does steel. 

Expect to experience some galling of threads. You may, or may not, achieve your goal with that design. Mine was similar, although I used some small C type clamps, made from stainless, and used stainless screws. I had no problems over the years, aside from mercury dissolving a portion of the bottom of my stainless retort. I ended up covering the bottom with a thin layer of asbestos, which solved the riddle. 

I suggest you condense the mercury with a water cooled portion of your discharge tube. Once mercury starts coming off, the entire discharge tube will be heated to near the evaporation point of mercury---so you risk discharging vapors. (I just reread your post and see that you have addressed that issue).
You have no idea how badly something can stink until you process this stuff. The filters capture human tissue, which is well rotted. 

Do handle all of these things with care. You risk exposure to pathogens that can alter your life--including hepatitis C and AIDS. 

Once you have retorted the material, I suggest you heat it well in a pan, to the point where it melts. That occurs at a relatively low temperature, well below a red heat. Stir it well, and keep stirring as it cools. The end result will be crumbles of silver/tin/other metals, what ever may be present. This process will oxidize the tin, making it far less troublesome when you dissolve the resulting material with dilute nitric. 

Should you elect to follow this procedure, insure that you do the heating in a hood. In spite of your best efforts, traces of mercury will remain. You sure as hell don't want to breath them.

Depending on the nature of the material, it could contain gold and the platinum group.

Harold


----------



## Anonymous (Jun 1, 2010)

Harold yes the retort is only for this one job. plenty of screws with a good gasket to secure the lid from leaks. The end of the discharge tube will be submerged in water to assist with fumes.

I did not think that you had to heat the retort glowing red to drive off the mercury when it boils at 673.84 degrees fahrenheit, and the old timers used a carved out potato thrown into the camp fire. 

Those filters have sat for 8 years you think they'll still stink of rotten human flesh, you think a bit of bleach would tone the smell and perhaps disinfect some germs from the filters.

Here is the finished retort.


----------



## Harold_V (Jun 2, 2010)

gustavus said:


> Harold yes the retort is only for this one job. plenty of screws with a good gasket to secure the lid from leaks. The end of the discharge tube will be submerged in water to assist with fumes.


That isn't recommended, due to the possibility of the retort aspirating water, perhaps resulting in a steam explosion. A hood of cloth wrapped around the discharge, barely in contact with the water in your collection container will work well. I recommend you add a serious amount of dish soap to the container. The stink will be unbelievable, with oils distilling from the material as well. Mercury from this operation won't agglomerate well unless it is well washed. If you have the same result I did, you'll have a pool of mercury with a mixture of black, burned oil and tiny globs of mercury floating on top. Soap will go a long ways towards dissolving the unwanted oils. With care, you can get all of the mercury to collect in a common pool. I found it so dirty that I retorted the mercury a second time, at which time it was placed in vials for storage. There were actually lumps of material that came out of the first heat. 



> I did not think that you had to heat the retort glowing red to drive off the mercury when it boils at 673.84 degrees fahrenheit, and the old timers used a carved out potato thrown into the camp fire.


My experience dictated that I had to get the bottom of my retort red, which was part of the problem with dissolution. Even then, when the retort was opened, there was a respectable amount of mercury that had not escaped. You may find some has dripped back on the material, with more in the form of droplets sticking to the top of the retort interior. I don't know if extended heating would have worked, but I gave mine a long soak, still with not great results. Could be you'll have better luck. A trial run should be very revealing. 



> Those filters have sat for 8 years you think they'll still stink of rotten human flesh, you think a bit of bleach would tone the smell and perhaps disinfect some germs from the filters.


Wish I had an opinion, Gill, but I haven't. Those that I processed were old, perhaps even a couple years, but being closed, they were still wet. If yours have had the opportunity to dry, and have seen some exposure to air, perhaps they're OK. Not trying to discourage you in any way---just a heads-up of the potential hazards. 

As far as adding some disinfectant, I think that's a good idea. I'd go the chlorine route if nothing else. Not knowing how long pathogens can remain infectious, I'd try anything that might be construed as helpful. Were it not for the mercury hazard, I'd suggest simply incinerating directly. That solves all of the problems, but not when there's mercury present.



> Here is the finished retort.



Nice job, Gill. Make damned sure you use a thread relief of some kind, or you may find you can't get the bolts out. 

I'm amazed at the similarity between yours and the one I used to run. You are right on target with having the bottom the input of the cooling water. If you use a hose, no big deal, but if you use a recirculating pump, once the mercury starts coming off, the water is heated fairly quickly. Do keep an eye on the temperature. 

Keep us posted, Gill. 

Harold


----------



## Anonymous (Jun 2, 2010)

Excellent read on mercury and sodium.

http://electrochem.cwru.edu/encycl/art-b01-brine.htm


----------



## qst42know (Jun 2, 2010)

I'm no chemist so please don't try this until we hear from one. 

Could the organics and oils in these filters be destroyed with sodium or potassium hydroxide before retorting or will either of these chemicals react with the mercury in a negative way?


----------



## Anonymous (Jun 2, 2010)

Won't know if there was any mercury until tomorrow, everything is still cooling down. I wrapped the upper half of the retort plus the discharge pipe up to the condenser with cerwool and cooked everything for 3 hours.

If there was any organic material inside the retort it's carbon now, it was very hot even the top of the lid turned blue under the wool. Hopefully this will get rid of the stinky stuff Harold_V was referring to when it's time to incinerate.

I certainly feel much better about using my retort now that chapter is past history..

Best Regards, 
Gill


----------



## Harold_V (Jun 3, 2010)

If you got no stink with this operation, you're home free. That was when mine smelled. 

Did you find any mercury in your collection vessel? When retorting amalgam, you get a serous discharge of the stuff. If the dentist in question didn't do silver amalgam, I expect there wouldn't be much in the material. Still, caution is advised, for he likely removed a few, if nothing else. 

I'm curious to see what comes from the retort, Gill. Pictures?

Harold


----------



## Anonymous (Jun 3, 2010)

Harold_V said:


> If you got no stink with this operation, you're home free. That was when mine smelled.
> 
> Did you find any mercury in your collection vessel? When retorting amalgam, you get a serous discharge of the stuff. If the dentist in question didn't do silver amalgam, I expect there wouldn't be much in the material. Still, caution is advised, for he likely removed a few, if nothing else.
> 
> ...



Harold nothing to take a picture of, no mercury. I'm running a second batch this morning included a small amount of amalgam which I know has some mercury content just to see if the retort is working as it should.

What I got from the first run is a Grey powder that sparkles in the sunlight, lost very little of the original volume. Obviously not bone ash.

The filters that I have are plastic with steel screen inside with a screw on top, if there was any mercury in them I don't have any clue where it may have gone. The lids were secure but dry inside.

Best Regards
Gill


----------



## Harold_V (Jun 3, 2010)

Interesting. The color description closely matches what I'd get, but if there was a significant amount of amalgam present, once the mercury was removed, the material melted, forming a solid, Bits and pieces of odd substances weren't included in the solid piece. 

I knew that I hadn't approached the melting point of silver, so came to realize that the combination of silver, copper and tin melted at a very low temperature. That's why I heated the material in a second operation (incineration) and allowed it exposure to atmosphere. That turned out to be the magic bullet needed to allow filtration of the resulting solution. Didn't get any of the gel, but, instead, white material that settled readily. 

I'm real curios about the contents of the gray material. Even more curious about the lack of mercury. Keep the reports coming. 

Harold


----------



## Anonymous (Jun 3, 2010)

Harold the second batch which included some amalgam produced some mercury. from the retort, There is an oily substance floating in the collection container pheew this stuff stinks.

Reading up on these perforated screen filters, they are primarily designed to trap only the heavy metals permitting the free passage of body tissue and fluids along with small bone fragments from drilling, grinding and polishing to enter the sewer system. 

There may well be more mercury than I currently see, the collection bucket has a jelly looking substance on the bottom that quivers when the pail is moved. This could be the mercury from the retort with a layer of oily crap clinging to it.

When I have time later in the week I'm going to run the Grey powders one more time.

Best Regards
Gill


----------



## Harold_V (Jun 4, 2010)

gustavus said:


> There is an oily substance floating in the collection container pheew this stuff stinks.


Oh, yeah! It seems to be common to dental waste. Even what appears to be clean amalgam tends to liberate the same stuff. That's why I suggested you use soap in the water. May take a few washings. Also, once you have the mercury washed clean, you can clean it chemically with a little HCl. 



> There may well be more mercury than I currently see, the collection bucket has a jelly looking substance on the bottom that quivers when the pail is moved. This could be the mercury from the retort with a layer of oily crap clinging to it.


That makes sense. I used a beaker to catch the mercury, so I could see what was under the top coating. That's when I started using dish soap. 



> When I have time later in the week I'm going to run the Grey powders one more time.


Likely not necessary, but that's how you make determinations for future applications. Once you understand what's necessary, you can then run from past experiences. 

Good job, Gill. 

Any trouble with the threads, or any signs of leaking mercury? I used to use a thin piece (1/64") of asbestos paper as a gasket. You could see signs of mercury trying to escape, but nothing got past the gasket more than about 1/4". The flange was about ½" wide, so it appeared to seal properly. To my knowledge, I never had any problems.

Harold


----------

