Smelting Flux Help !!

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dennyhb94

Member
Joined
Aug 1, 2017
Messages
7
Hi All,

I collected 30kg of dore from mining (composition is 30% Au, 30% Ag, 3% Ir, 17% Cu, 15 % Pb, and 5% other base metal such as Fe, Zn, Ni)

I melted the dore with borax and a lot of slag is produced as you can see from image attached.

Then i proceed to skim the slag, but after many skimming, the slag did not seem to disappear..
It keep re-appearing over and over again...

So i wonder if there's a more efficient method ?

Currently i melt the dore using only borax.
I'm also wondering if i need to use any other flux? and if so, what flux do i need to use?


slag_molten.jpg
 
With 30% Au it's almost perfect for inquartation. Maybe add a bit of silver, pour into water to make grains and cornflakes of it and proceed to nitric boils. Then refine the gold with aqua regia.

The slag is probably the base metals getting oxidized. When you skim the old slag the fresh surface can react with oxygen again, forming more slag.

I hope the numbers you quoted is your own assay and not what the miners told you.

Göran
 
3% Ir !!!

Watch out, that's probably arsenic and your melt could probably give off toxic arsenic vapors. Keep it well ventilated!!!


Whenever I see Ir in an assay of ore or doré I know that it was done with an XRF. Most XRF tuned in to metal or precious metals doesn't know about arsenic and will report it as iridium. It also ignores oxygen and sulfur so a lot of your slag might already be there and just surfacing during the melt. You could have a lot of melt losses on this lot.

Best thing to do for doré in my view is to take drill samples around the bar and do a fire assay or refine the sample.

Göran
 
g_axelsson said:
3% Ir !!!

Watch out, that's probably arsenic and your melt could probably give off toxic arsenic vapors. Keep it well ventilated!!!


Whenever I see Ir in an assay of ore or doré I know that it was done with an XRF. Most XRF tuned in to metal or precious metals doesn't know about arsenic and will report it as iridium. It also ignores oxygen and sulfur so a lot of your slag might already be there and just surfacing during the melt. You could have a lot of melt losses on this lot.

Best thing to do for doré in my view is to take drill samples around the bar and do a fire assay or refine the sample.

Göran

This assay is only preliminary by XRF method. My concern is actually about removing the slag to ensure homogenous sample is taken to be send for Fire Assay.

So I'm not sure if the smelting technique i'm using currently is correct since i'm only using borax.

After some research i think i need to use more flux beside borax to further improve the efficiency of the smelting and remove the slag easily.

So i'm wondering if you have any suggestion of the smelting method & also the flux i probably need.
 
Have a proper assay done and that would indicated how to properly treat your material, including flux mixtures.

And yes, the reading from XRF indicating iridium is likely arsenic. Have fun with lung damage on that.

Time for more coffee.
 
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