Following the discovery of gold's solubility in cyanide (1890's), it was
discovered that passing the gold dissolved in cyanide solution through chips
of zinc caused a gold to precipitate. The zinc reacts with the cyanide,
replacing the gold in the Au-Cn matrix, and causes the gold to release as a
solid precipitate.
Early zinc precipitation systems simply used a wooden box filled with zinc
chips. These systems worked, however, they were very inefficient, since much
of the dissolved gold still remained in solution after passing through the
zinc box.
The Merrill-Crowe process was the first use of the zinc precipitation
process that made the use of powdered zinc, a highly efficient gold
recovery process. Primarily, the Merrill-Crowe process works so much better
than the early zinc boxes because in order for efficient and complete
precipitation of gold and silver from a cyanide leach solution to occur,
dissolved oxygen must be removed from the solution. The merrill Crowe plant
also uses 325 mesh zinc, which is much more efficient in mixing with the
Au/Ag-Cn solution, more surface area, as you know, makes for more efficient
reactions. A Merrill-Crowe plant typically reduces the oxygen content of a
cyanide solution to about 1 PPM or less. Recovery increases to 85-95%, from
30-50% without removing the O2. Now your technology has advanced from 1880
to 1920, in one giant leap.
But then you really don't need to know anything, just make it up as you go
along. Those of us that spent too much time at universities and working in
professional capacities on various projects all over the world, simply
wasted our time, we could have just made everything up, so it sounded nice,
and tried to convince everyone that we were "experts".
I'm taking up brain surgery next week, the week after that, I'm going to be
a 787 pilot and the week after that, maybe I'll have a coup in the
Honduras. I always wanted to be a dictator of a banana republic. Did you
ever wonder how much gold could be in the banana, perhaps processing
banana's could yield a higher quantity of gold than your mine?
How do you do zinc cementation for the recovery of precious metals? We
have a small continuous leach mill in Honduras.
Thanks,
/s/ Tom Milam, Jr.
--
Tom Milam, Jr.
The Inglesrud Corporation
P.O. Box 18759
Oklahoma City, Oklahoma 73154
Telephone: (405) 843-7389
Facsimile: (405) 843-0351
www.inglesrud.com