From what you are describing it seems like you are dealing with fine loose free mill gold right? Using only the HCl acid (muratic) will normally breakdown the rock/silca which encases the gold. but HCl is also used to remove/dissolve the base metals associated with plated gold. And then further refined by placing the gold recovered into a solution of HCl and bleach, which will dissolve the gold into the solution. In order to verify that the gold is present in the solution, you can do a Stannous test. The gold is then "dropped" from the solution by using small additions of Sodium MetaBiSulfate. That gold sludge is then washed and dried, and then melted in a crucible. This is an alternate method to using AquaRegia. The problem with using acids like this with "gold ore" is that other metals are almost always present in the ore with the gold, so once you dissolve the gold into solution, other metals are also spoiling the mix, which makes removing the gold even harder to do. Sulfuric Acid will "not" dissolve gold. It is used mainly in "electrowinning". You likely know the difference between oxidized gold (free gold, nuggets, flakes, fine particles) and sulfide gold. When gold is locked up as a sulfide, even the cyanide leaching doesn't work to loosen the gold....it needs to be oxidized first. usually by roasting it under intense heat. If you are describing the fact that you may have free mill gold, using the HCl with bleach will likely dissolve the gold and allow you to purify it. But....if you do have free mill gold wouldnt that be the same as flour gold? Then there is no need to process it chemically. I suspect what you have is really "sulfides" and unless you have large quantities, will probably be very difficult to recover economically. Gold is usually "adsorbed" to the surface of the pyrite and hard to remove unless these other methods for treating sulfides are used.

     Pyrite is iron disulfide , FeS2 thus a sulfide.  Roasting @ 400 degrees for about one hour should drive off the sulfur leaving just the iron to deal with maybe.  Pyrite can have substantial amounts of nickel, cobalt, and gold also running with it.  After roasting try the muriatic acid bath again and see what happens.  Good luck with that.       Ron

Muratic Acid (HCl )alone will not do anything. Go to goldrefiningforum.com and there is a wealth of info to use.

Muratic is only typically used to dissolve "base" metals.......the ore might be able to be oxidized by adding some peroxide into the solution. This will aid the oxidation rate. But regardless a second treatment using HCl and Bleach will dissolve the free gold. It is necessary to turn the gold into a cloride, and then precipitating it out of the solution with the SMB 

HCL and Bleach creates a very nasty Chlorine Gas cloud, I wouldn't recommend that to anybody. As for dissolving the gold that is not what I want, I want to dissolve the pyrite to get the free gold out. The idea of cooking it for a while sounds interesting but I don't think 400 degrees would be adequate, but its worth a try because it's not a large enough quantities to spend a great deal of money on, maybe a penny weight of gold. I do have a kiln and it might be worth a try to smelt the gold out of the pyrite in a cupple, I just don't know.

Another person told me a way of using borax instead of mercury to bind the gold, has anybody ever heard of such a technique? The last time I used borax with gold it bubbled and tipped over the crucible which shorted out my kiln melting one of the heating coils.

We recently had one of our oldest members of GPAA pass away, 28 years as a Member and a father of our Chapter. When I went to his wife's yard sale to sell off his equipment I realized he had been melting lead tire weights to make larger weights. I just have to wonder if that lead exposure didn't give him the cancer that killed him? With all the equipment he had I am sure he had been smelting other stuff as well and it was not in a well ventilated area nor did I see the type of protective mask you need for smelting or melting lead.

I know as a commercial gold miner ( and not working in the mill any more) small amounts of HCn (hydrogen cyanide) are used to pull it from all other minerals and then brought back. but never seen anything else used without HCn