Yes Kurt, XRF. And a test run on a larger batch of 2kg.
Should/can the tin be removed at this stage, and how if yes?
Pics to follow later…
Smelting losses?
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Should/can the tin be removed at this stage, and how if yes?
Pics to follow later…
Years ago when I melted jewelers sweeps which had been incinerated and crushed to -60 mesh I used copper as a collector. The furnace was a rotary furnace and it was important to have a reducing flame and the concentration of Gold in the powder was about 1 oz per pound. We added copper metal from the cathode copper from the copper sulfate cells where we recovered the PM’s. Adding about 200 lbs of Copper for every drum (55 gal) of sweeps. Copper was an effective collector.
One time someone messed with the air gas mix and the flame was oxidizing and the slag turned red and was holding a lot of the copper and gold. Keeping the charge oxygen starved kept the copper in the melt allowing it to be an effective collector.
This was in the days before XRF so fortunately the color of the slag was able to tell us there was an issue. These days there are some convenient tools to keep you on track.
One time someone messed with the air gas mix and the flame was oxidizing and the slag turned red and was holding a lot of the copper and gold. Keeping the charge oxygen starved kept the copper in the melt allowing it to be an effective collector.
This was in the days before XRF so fortunately the color of the slag was able to tell us there was an issue. These days there are some convenient tools to keep you on track.
One other question—-the melt cools rather quickly in the inverted cone mold. Should it be hotter, in order to enable and give time for the heavies to sink to the bottom point, or does this happen anyways in any pour?
If cooling too fast is an issue you will see a ring of small beads just above the metal cone in the slag. I usually pre heat a cone mold but never to red hot.
Now I see it - reddish, brick-coloured slag could point out to copper oxide formation. And if XRF say 38% Cu, then it is all oxidized and gold is dispersed in these oxides.
Jason from MBMMLLC had one YT video, in which he tried to oxidize or reduce some shredded and separated e-scrap, and I remember that he had like 100g of copper in, and when he added CuO or something, he produced reddish slaggy melt with nearly no metal collected.
I suspect that Cu2O forms from CuO (copper oxidized during incineration) and Cu during melting, and metal just "disappear" into the slag.
Try to re-melt the slag in graphite or in clay with addition of sawdust or flour/charcoal. Leave it plenty time to fully reduce the metal.
When pouring any melt into the mold, there will almost always be stuck in the slag metal beads which didn't have enough time to sink to the bottom of the mold before solidifying the slag.
With any metallic collector. The only question is their quantity, which depends on the final temperature and viscosity of the slag.
If you want to avoid such losses, then the best option is to sacrifice the fire clay crucible and not pour out the melt, allowing it to slowly cool inside the furnace. After this, break the crucible.
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a good idea in that case
can be
grab the slags
pulverize it (use googles and a mask or respirator)
and put in a beaker
first add Nitric acid to get rid any base metal
and silver if there is any
after that add aqua regia
do the process
filter out,denox and precipitate
and let see what you can have
can be
grab the slags
pulverize it (use googles and a mask or respirator)
and put in a beaker
first add Nitric acid to get rid any base metal
and silver if there is any
after that add aqua regia
do the process
filter out,denox and precipitate
and let see what you can have
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- Messages
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A person i know
In His mining claims
He have lot of slag
left over by old timers
and He processing certain amount of the slags
And almost always got gold and silver
for the amount of slags He have in his claims
He can easily stay busy processing the slags for years
the point is almost always certain amount of precious metals will be left in the slags
for that reason i don’t trust fire assay
in the measuring of Grams X Tons
Fire assay can only give You an Idea of the amount You have possibly found.
but Not is 100% sure.
Not even 50% sure.
I only use fire assay to know what is in the ore.
In His mining claims
He have lot of slag
left over by old timers
and He processing certain amount of the slags
And almost always got gold and silver
for the amount of slags He have in his claims
He can easily stay busy processing the slags for years
the point is almost always certain amount of precious metals will be left in the slags
for that reason i don’t trust fire assay
in the measuring of Grams X Tons
Fire assay can only give You an Idea of the amount You have possibly found.
but Not is 100% sure.
Not even 50% sure.
I only use fire assay to know what is in the ore.
Aluminum oxide Al2O3 from chip substrates will not dissolve in nitric acid. But in aqua regia, aluminum partially will dissolve to AlCl3. Hydrated aluminum ions in solution will lead to significant losses during the precipitation of gold from aqua regia. Remelting is much more reliable.
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Sometimes, the old times prospectors used what they had available. This could be a recipe for an inadequately fluxed slag. I have seen piles of the waste slag from some of the first smelters in Colorado, and read the history of why this occurred. Competing mines, some Gold/Silver, with Silica gangue, other mines were replacement deposits in Limestone, containing Lead, Silver, Copper, and occasionally Zinc. The smelters needed a combination of both ores. The Limestone basic ore, with the necessary collector metals, to balance out the Au/Ag Silicious ores. Like greedy bullies in the sand box, nobody got along, so the smelting results suffered. Eventually, all ores were shipped to another area, which had the proper furnaces, and mixes of ores. This left behind a conglomeration of rich slags, and occasionally, some rich matte layers.
So if a mine had an acid, or basic flux only gangue, it was not enough to recover the metals adequately.
A properly fluxed assay, will give very accurate results. Sometimes a good assayer will run duplicates (2), if he he unsure about a sample. This could be from a sample which was crushed by the customer, leaving no easily identifiable minerals, to determine what flux recipe to use, varying the flux recipe ever so slightly.
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Exactly
and those piles of Slags will keep Him busy for long time
is way dirty to play with the slags
But we recover gold and silver
No matters the amount gold is gold
But even today with all the equipment and the new and better flux ,it will almost always some precious metal left in the slag
could be minimum but it will there in the slag.
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Kurt, boiling the slag only took out Silicon (from 62 to 33) and increased Copper from 10 to 31. All base metals stayed the same. Silver increased from 0.2 to 1, and Gold went up from 0.062 to 0.380.
