From: Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Date: 04/07/02-06:54:37 PM Z
William Marsh wrote:
> ...
> large (100ml) bottle of platinum has developed about 1/2 teaspoon of
> sludge in the bottom that won't redissolve. ...
>
> Can this stuff be salvaged? Do you think it could be re-refined ...
A couple options for the "sludge" are:
1) Your Pt solution is too strong to stay in solution at your room
temperature. There will be some precipitate which can be put back into
solution by warming the solution enough for that particular solution
strength. However, if the solution is used (which, in effect, removes a
weaker solution) the precipitate will increase and when dissolved will
cause the solution strength to be stronger than mixed. The solution is
to make sure the Pt solution is at the correct temperature for all to be
dissolved whenever using.
2) Your Pt material is contaminated with K2PtCl6. This can be likely
when using not using a high quality product. It can also be possible to
convert K2PtCl4 to K2PtCl6 with temperatures above 140F and the presence
of sodium, but this can be rare. The trouble with the K2PtCl6 is that
it is only slightly soluble in water. The K2PtCl6 crystals are normally
yellow, but the "sludge" can still look black. The solution is to use a
different vender for your Pt.
In option 1, some salvage can be made. But the strength of your
solution may not be known. However, a stronger than required solution
can be used with no ill effects other than wasting the Pt.
The material can be re-refined, as well as any scrap prints, spills,
cleared metal. But it will require a large volume to make it
profitable. Engelhard will do this for a fee, and you can contact them
for the break even amount (given as the weight of recovered material,
not the weight of the waste.)
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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