geoguy

Personally, I think HF is your best bet.....happens every day in the semiconductor industry.

 

But have you thought of putting them in a regular test tube with water and then trying to separate with a pasture pipette?

The "mica sand", since is less dense, should be pulled into the pipette much easier than the gold, much like a centrifuge....

 

Then I think you may be left with mercury, which is still used to purify gold from ore.....

 

If you don't want to mess with mercury...TOXIC!!...ignore the following....

 

If there is still some impurites left (I'm sure there are) cover the concentrates with water. Add one tablespoon of household lye to the concentrates and swirl it around for several minutes. This will remove surface impurities such as dirt and oils from the gold.

 

Pour off the lye laden water. Add fresh water and add one ounce of mercury.

 

*** WARNING!!! WHEN USING LYE YOU SHOULD WEAR SAFETY GOGGLES AND RUBBER GLOVES TO AVOID GETTING ANY IN YOUR EYES OR ON YOUR SKIN. WHEN USING MERCURY, USE THE SAME PRECAUTIONS. IN BOTH CASES DO NOT INHALE ANY OF THE FUMES!!! ALWAYS WORK OUTSIDE AND UPWIND.

 

Slowly swirl the contents with the mercury. As the mercury goes around the pan it will pick up all the finest gold in the pan. The more gold there is the stiffer the mercury becomes.

 

Once you have all the gold gathered, pan or suck off the sands (or use a magnet in a plastic baggie to retrieve black sands), leaving only the gold laden mercury and free mercury. The free mercury will roll around easily where the gold laden mercury is stiff and does not toll well. Place your mercury container INSIDE another gold pan and pour off the free mercury into the container. Using another pan keeps it from spilling out onto the floor or ground. If you spill mercury on the floor or God forbid, the living room carpet, you will be inhaling evaporating fumes for years!

 

Once you have a stiff ball of gold laden mercury in the plastic pan flush it out into a glass measuring cup. To this add a few drops of nitric acid Keep adding nitric acid until you get a bubbling or fizzing action from the mercury. !!! DO NOT BREATH THE FUMES !!! The acid will dissolve the mercury as well as any trace silver. After awhile the fizzing stops and at the bottom of your cup is a bronze colored metallic looking blob.... It's GOLD!

 

You can recover your mercury from the nitric acid by placing a flat copper bar or copper sheet into the acid and letting it set overnight. The next day the mercury will have come out of solution and attached itself to the copper now you can scrape the mercury from the copper and put it back into your storage container.

 

Carefully pour off the remaining liquid and neutralize the acid with baking soda, a little at a time until you get no reaction from the acid and soda. Gently rinse the gold in the cup with fresh water avoiding hard sprays that could rinse away your gold. Pour off the water and let dry. The remainder is your pure gold! (actually 95% - -98% pure)

http://www.learngoldprospecting.com/index.cfm?var_file=separate-gold-concentrates.htm

what the heck? This is gold and mica. You are making a mountain out of a mole hill. Pour them in a glass of WATER and the gold and mica will separate. Odds are the mica silicate plates will float. No need for mercury etc.

I'm not sure what you are trying to do. You have a residue containing gold and mica? Or, to the contrary, is this in a matrix rock such as quarzite? If it's a residue then simply dump the gold and mica into a tall clear glass of water and the gold will sink much quicker....the difference so obvious that you just have to tilt the glass after the gold sinks to separate them.

I have to question if you actually have flakes of gold and mica....they will be quite distinct if you look with a hand lens. There couldn't be an element and a mineral easier to separate just by vibrating them on a sheet of paper. No fancy solutions or equipment are necessary. Even blowing on the residue will separate them.