Yes Kurt, XRF. And a test run on a larger batch of 2kg.I assume these are XRF read outs ?
Kurt
Should/can the tin be removed at this stage, and how if yes?
Pics to follow later…
Yes Kurt, XRF. And a test run on a larger batch of 2kg.I assume these are XRF read outs ?
Kurt
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.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?
Thanks guys for the responses…here are some answers to the questions:
The slag composition is very close to the original powder:
SLAG:
Si 45
Cu 38
Sn 10
Fe 7
Al 3
Au 1.43
It was a fairly liquid pour. Flux was sodium carbonate/borax/silica sand 10/4/1.
BGAs were half Broadcom, half another type 1” square with a gold tip on one corner. I did not separate the base from the black top.
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.No beads visible. Sieved to 80 mesh. Quite fluid, but not runny. Flux glass was very brittle, crystalline, reddish-brown colour (Cu?)
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.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?
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.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.
ExactlySometimes, 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.
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.So this was a "test run" on a larger batch
So the 100 grams came from concentrates of the larger batch - Edit to add - I would like to see a pic of the remaining concentrates
After milling did you sift the milled material through an 80 mesh screen or just run it through the cube (this is more a question about your process other then the smelting process)
With that much soda ash in the flux it should dissolve most of the slag in HOT water (simmer boil) --- try that & lets see what we get - post pic
Kurt
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