# First 120g Ingot



## darkminos (Oct 17, 2020)

So here it is, 120g of .9997 fine gold ingot (tested with XRF). Inquartation, nitric acid treatment, AR and I used Iron (II) Sulfate (pure, not copperas) to drop it as there was some platinum in solution. Was very supprised to see .9997 when they tested it as there was a small tint on the top of the ingot which must have been some sort of contamination.

I do have some questions, when precipitating the solution first a light brown powder dropped and later a fine dark powder (the light coloured powder has become small foils, hard to see from the pictures, and I expected this to be "sludge" which needs boiling off using Hydrochloric Acid - however the boil didn't react with either samples). I was very confused by seeing this so I took a sample of both materials and added some Nitric Acid to each sample - no reaction. I cleaned them up and melted the samples into buttons - both were gold and both had a slight purple tint to them (but only on the top of the button, while the bottom was clean and left a purple mark on the crucible). Eventually I decided to melt it all down, despite knowing there is a contaminant in there. It went beautifully, poured a lovely ingot and was very happy how it looked and felt with only a small tint on the top. 

Later I noticed that whatever was contaminating the powder has soaked into the crucible and turned it purple... Any ideas what it might have been? I think I might have unknowingly performed a fire assay :lol: :lol: Maybe the copper I used for inquartation was not 100% pure an contained other metals which the nitric acid treatment didn't dissolve? As a side note, I did use probably an excess of Iron (II) Sulfate to precipitate the solution, is it possible to add too much of it? 

EDIT: and before I forget, I big thank you to sreetips and his YouTube channel, although I have been reading CM. Hoke's book every step of the way, his videos have really helped me visualise the whole process!

EDIT 2: From Hoke's book "Gold shows itself by a bronze or purple stain on the crucible;" so looks like the purple stain is normal for gold. :?


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## g_axelsson (Oct 19, 2020)

Beautiful! That's some pure gold. Just strange the discoloration of the bar.

For a first pour this is outstanding. It seems you have done the home work properly before starting to refine.

Just as you found out, the purple stain of the melting dish is from colloidal gold that got stuck in the flux. It is a sign of purity that the flux doesn't turn black. If there were any base metals mixed in the gold, the oxides would have turned the borax black.

Let me guess that you use oxygen acetylene torch? I didn't get any discoloration from melting pure gold with lpg and air, but my welding torch makes the melting dish go pink. I suspect it is the higher temperature that makes that.

Göran


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## darkminos (Oct 19, 2020)

Thank you. I did actually use MAPP gas and a Bernzomatic TS8000 torch as I knew it will be powerful enough to complete the melt (since I have been inquarting about 120g of gold and copper at a time), was thinking of getting an oxy-hydrogen setup, but turned out to be too costly for my needs so just used what I had.

I did however let it sit some 30-60sec longer on the heat to make sure it's completely molten. 



g_axelsson said:


> Beautiful! That's some pure gold. Just strange the discoloration of the bar.
> 
> For a first pour this is outstanding. It seems you have done the home work properly before starting to refine.
> 
> ...


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## MGH (Oct 19, 2020)

Yes, as you referenced from Hoke, and upon which Goran expounded, your contaminant is gold. Not the worst problem to have. 8) 

I'm guessing you may have just a little bit too much flux in your dish. I've had bars come out this way before too. The colloidal gold is trapped in the flux, and then you pour a little flux on top of the gold, forming a thin layer of purple. You may have some success dissolving the flux in warm dilute sulfuric acid, as discussed elsewhere. You could probably just polish out that area too, but it would be a shame to disturb the otherwise pristine surface which speaks to the purity of the gold overall.

Nice job!


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## darkminos (Oct 25, 2020)

I actually always intended to wash it with dilute sulphuric acid but was under time pressure to sell it on the day so run out of time  

I also just remembered that when I was melting down a sample of the copper that I used for inquartation, there was a red/purple coat on the copper afterwards - that's probably caused the stain on the gold, but still have no idea what it is... 



MGH said:


> Yes, as you referenced from Hoke, and upon which Goran expounded, your contaminant is gold. Not the worst problem to have. 8)
> 
> I'm guessing you may have just a little bit too much flux in your dish. I've had bars come out this way before too. The colloidal gold is trapped in the flux, and then you pour a little flux on top of the gold, forming a thin layer of purple. You may have some success dissolving the flux in warm dilute sulfuric acid, as discussed elsewhere. You could probably just polish out that area too, but it would be a shame to disturb the otherwise pristine surface which speaks to the purity of the gold overall.
> 
> Nice job!


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## etack (Oct 28, 2020)

Why use Cu at all. 

Eric


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## darkminos (Oct 29, 2020)

Because I didn't have any silver on hand...



etack said:


> Why use Cu at all.
> 
> Eric


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## nickvc (Oct 29, 2020)

The manufacturers use small additions of various metals for certain applications to improve strength or resistance to corrosion so that could be the cause of the colour on your copper and possibly your gold.


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## darkminos (Nov 15, 2020)

I'm just processing the second batch and I think it's the wire coating. I just submerged the inquarted gold in 98% sulfuric acid and waiting for the enamel to dissolve. This is a fairly redundant step as the nitric acid wash would take care of it anyways, but since I have more than enough sulfuric acid, might as well use it up... 



nickvc said:


> The manufacturers use small additions of various metals for certain applications to improve strength or resistance to corrosion so that could be the cause of the colour on your copper and possibly your gold.


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