Magpie - 6-11-2006 at 17:22
This is a specialized analysis in the field of metallurgy. I'm not sure where it belongs but since it requires a furnace and crucibles I placed it
here.
My ore looks like silica and indeed when I made a test for reducing power it had none. For the fusion I ended up with a flux made of Na2CO3, PbO, and
Na2B4O7. For the reductant I used wheat flour. One quarter inch of NaCl was used for a cover.
Today I cupeled the lead prill and was thereby presented with a dore bead weighing 3 mg for the 15g ore charge. Therefore, my ore is loaded at about
6oz/ton of Au/Ag/PGM.
The next step is to dissolve out the Ag and determine the gold content. I'll attach some pictures if there is any interest.
Fleaker - 6-11-2006 at 18:36
I am interested to hear more about it. So you've finished the cupellation then I take it and now you intend to part the remaining lead and silver from
the more noble things (Pt and others). Keep in mind that you should check for palladium (DMG works) and checking for silver is easy enough with table
salt. Just give it an ammonia wash to check to see if the silver complexes.
If you don't mind me asking, where'd the ore come from?
P.S. Avoid the fumes from the lead.
P.P.S. What type of cupel are you using, bone ash or magnesia. Both are available at lmine (just google legend mining, and you will be quite happy
with this store). Rather interesting that they sell NaCN by the kilo there, along with large quantities of mineral acids, bismuth, lead, silver, etc.
BTW, Ammen's book is rather nice. I take it you are reading from the book on refining.
[Edited on 7-11-2006 by Fleaker]
Magpie - 6-11-2006 at 18:46
I'm trying to follow the directions of Ammen's book and will use that for parting the gold. However, I did find that his recommended cupelation
temperature of 850C was too low. I used 1000C today then cut back a bit when I noted that the cupel had "opened." This seemed to work well.
The ore is from central Idaho.
Magpie - 7-11-2006 at 10:01
Ah, yes the lead fumes. I did the furnace work in my hood. But it still bothers me to generate them. For that reason I wish I had the bismuth
trioxide instead of PbO (litharge). I don't plan on doing many of these.
I used bone ash cupels. The attached picture shows my equipment. The Jelenko furnace is an old dental (I think) furnace that I picked up on eBay for
less than $200, IIRC. I did get the rest of the supplies from Legend Mine as you indicated. I had to buy a case of clay crucibles but was able to
buy just a few cupels, at that time.
The little cone in the picture is the black glass produced when I did the reducing power (RP) determination for the ore. The lead buttons (not shown)
are the same shape and size. The piece of grey glass is a piece of slag from the assay fusion. Not shown is a cast iron mold used to get the cone
shapes from the fusion pour.
Yes, I'm using Ammen's Recovery and Refinning of Precious Metals. It's a fun read and oriented towards doing instead of theory. I called
Ammen with a question a couple years ago. He's old and crusty but has a good (and bawdy) sense of humor. 
I would show a picture of the dore bead but it is very small, with diameter <1mm.
neutrino - 7-11-2006 at 16:37
On the subject of fire assays and prospecting in general, this site may be of help.
Fleaker - 7-11-2006 at 16:52
I am quite familiar with that site and it has (for the most part) rather good information. A few things I don't see working well, but the guy did have
experience running his own assay lab. I heard from a friend who knew him that he passed away last year. IIRC I think he was bitten by a snake while
in the jungle prospecting.
Eclectic - 7-11-2006 at 19:47
Quick, back the site up before it goes away.
neutrino - 8-11-2006 at 19:38
I uploaded a full copy to axehandle's FTP ages ago, so don't worry. It's under Basement Chemistry for the Prospector or something along those lines.
The page seems different than it was a few months ago. The top frame and the links page were added, I think. It seems that someone is still
maintaining it.
Magpie - 10-11-2006 at 13:05
For the mining history buffs here is a picture of the assay office at Vulture, Arizona, where $200 million in gold was extracted.
Is this possibly a part of vulture's worldwide empire? 
