SEPERATION OF MERCURY FROM GOLD

1 ANSWERS

1. amomipais82
   

   Hi,
   The separation of gold from mercury is a very old problem.  The 49'ers actually used potatoes in an oven to do it, and then ate the potatoes, don't do that...
   
   There are a couple of ways to separate the gold, depending on the amount of gold and the amount of mercury.  First, you have to be very careful in handling mercury.  Although there is a relatively low toxicity involved in ingesting the mercury by mouth, nearly all other ways of absorbing it have really bad results.  Don't breathe the fumes, in any circumstance, don't handle it with your bare hands, it is absorbed by the sweat glands in the palm of the hand, use good rubber gloves.  Remember, mercury evaporates into the air gradually, even at room temperatures, so keep it convered at all times.  I generally keep a layer of water over mine to keep it separated from the air.
   
   Ok, on to actual separation.  If you have a volume of mercury containing a reasonable amount of gold, you can separate it the old fashioned way, with a leather chamois.  If you use a tube, or other device, to force the mercury through several layers of chamois leather the majority of the gold will be left in the leather and can be cleaned up, carefully, by dissolving the remaining mercury away with 20% nitric acid.  Stronger acid does not help, the water is neaded in the dissolution process.  There are people who sell mercury presses which use air pressure to force the mercury through the leather, you can find them listed in the International Journal of Mining (used to be the California Mining Journal).  Action Mining is one such supplier, there are others.  You can build one of these using PVC pipe, a tire inflation valve and a tire pump.
   
   Another method is the use of a retort.  Again, there are suppliers as above.  A retort is more complicated to use, but does a better job, but you need to be very careful, especially with the fumes.  You need a very well ventilated area and a vacuum pump.  Basically, you heat the mercury in a closed system, usually made from iron, the vapor is condensed in a water cooled tube and collected under water, the fumes drawn out with the vacuum pump, the gold is left behind in the original iron vessel. This is the primary commercial method.
   
   The resultant gold can be cleaned up with a borax and soda ash fusion and cupelled if necessary to remove trace metals.
   
   If you want extremely pure gold, you can re-dissolve the gold in aqua regia (very carefully, this stuff is really dangerous) and use dibutyl carbitol to extract the gold chloride, which you can precipitate using oxalic acid.  This method can produce extremely pure gold.  I have made .9999999 gold this way, which brings a real premium in the market.
   
   Bottom line, it is done fairly easily by experienced people, great care is necessary, but it is not overly complex or expensive.
   
   I hope this helps...

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