Hello, I wasn't exactly sure where to post this kind of question but I
figured this was a logical choice (among a few others)...
Suppose you have a solid mixture of tungsten, gold, and other metals
that can be dissolved with aqua regia acid. Assume also that the
mixture contains only those metals and very, very tiny trace amounts
(less than 100 ppm) of anything else. Now imagine placing them, as
shavings, into a suitable container, like a pyrex beaker, into a
centrifuge. Also assume that the beaker can be heated as it spins to
help increase the speed of the acid action on the metals.
Assuming a relatively equal amount of each metal, would it be possible
to separate the metals into stratas or layers? It might be possible to
boil the acid off as it spins too. This way, a more dry particulate
may be left and separated, at least partially. The density near room
temperature (and not too far from aqua regia boiling point) for
tungsten and gold are quite close, 19.25 and 19.3 g/cm^3
Does such a practice exist? How good of separation is possible? Could
it work in general for any metals dissovable, if given enough time
(maybe even with additional acid added after boil-off).
Thanks in Advance!
Modifications of these do exist - "Centrifugal Fast Sacn Analyzer" and
"ore floatation" as an examples. Nature separates metals and their
ores using gravitation and flowing water (best example: the gold found
at Sutters mill CA that started to gold rush).
However, when metals are dissolved in acids they are at a lower
thermodynamic state than when they were alloyed and cannot be
separated as free elements (only as ions) by graviation or centrifugal
forces alone - electron transfere must occur to free the metal ion
into free metals - electroplating is the most direct but not
necessarly the most energy efficent.
Boiling away the acid will leave the dissolved metals as chlorides and
oxides (essentially ores). This is the main problem addressed in the
field of extractive metallurgy.
In my particular ore, I'm quite interested in extracting the gold
first and worry about other particulates later. Here is a breakdown of
the elements in my "ore":
I've noticed the melting points of all the elements mentioned for the
main contributors are quite high but gold is basically the lowest of
them. Te and Yb are much lower than gold's but I was thinking if I
pulvurized the ore as much as possible and then heated it to slightly
above the melting point of gold, I could "leach" out the gold? From
there, I could focus on separating the Au from Yb and Te directly for
some profit. There is a significant portion of gold, as it can be seen
due to the yellow tint and various SEM microphoto scans show.
Does anyone suppose this would be a viable approach? It is unfortunate
that all the elements are fused together in the "ore" (which is not
natural by the way). It is possible Au particles are literally wrapped
inside other elements deposited. Therefore, milling or whatever to
pulvarize the material would be crucial step. The predominant element
will must certainly be W.
Thanks for all your help, it has been quite informative!
the only thing that i can think of is the ability of W to form
tungstates (WO4)-2, under oxidizing conditions.
dissolve it all in aqua regia, oxidize the heck out of it, precip the
tungstate, then send the residue to a Au/PGM recycler?
not very elegant.
How about zonal refining.
Think semiconductor refining. Many foundries have gone to larger and larger.
You might be able to find a small unit for sale.
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Life; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
It all comes down to economics - Gold metal can be extracted from any
ore as long
as the cost to extract does not exceed the market value of the
extracted gold plus any
market value of the tailings.