# Reduced Gold yield



## Saddiq NG (May 27, 2022)

Hello members of this blessed forum I urgently need some advice with my refining.

I just recovered some gold from cell phone pcb using ferrous sulfate. I washed the gold precipitate and weighed it; it was 2 grams. I decided to refine it for the third time to make it pure, I usually refine two times.

I used 100ml HCl and about 9ml HNO3 and 6ml H2SO4 to dissolve the gold. I heated the reaction moderately to make it fast and to eliminate any excess nitric acid. I filtered the solution when the reaction was done, diluted the solution with water and then I added the ferrous sulfate to precipitate the gold.

The color of the solution turned black, that's how it does when the gold precipitate. After a while, the brown powder of gold began to accumulate at the bottom. After there was no more powder coming, I decanted the solution, washed the gold and weighed it. 

To my suprise, it was only 0.8 grams of gold that precipitated. The actual weight was 2.0grams. The color of the gold powder before refining was brown, but when dried it turns grey and that was why I decided to refine for the third time. I urgently need advice and info as to what could have possibly happened to my remaining lost 1.2grams of gold lost. Thank you.


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## silver1 (May 27, 2022)

One you didn't DeNOx 
Two no Stannous Chloride test?


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## FrugalRefiner (May 27, 2022)

I hope you didn't throw the solution away. Your gold is probably there.

Dave


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## Saddiq NG (May 28, 2022)

silver1 said:


> One you didn't DeNOx
> Two no Stannous Chloride test?


I didn't DeNOxed this one because I did the incremental Nitric addition watching the gold dissolve in solution. I did the stannous test and the solution is Negative. I even added FeSO4 and it didn't turn dark.
I usually DeNOx however by heating the solution could it be possible that the gold chloride is evaporating or volatilizing?


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## Saddiq NG (May 28, 2022)

FrugalRefiner said:


> I hope you didn't throw the solution away. Your gold is probably there.
> 
> Dave


I've stored the solution in stock pot. I've tested the solution however and it's negative. I've added FeSO4 to it and there was no precipitation.


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## silver1 (May 28, 2022)

When In Doubt, Cement It Out


When In Doubt, Cement It Out This is advice I often give to new members who find they've created a bit of a mess, and they're wondering how to recover their values (gold, silver, PGMs, etc.). Perhaps they've followed a process they've seen on YouTube that left out some important details...




goldrefiningforum.com


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## nickvc (May 29, 2022)

You desc your initial powder as grey which means it wasn’t anywhere near pure in fact very very dirty so if your solution is testing negative you have all the gold that was there in the first place as you didn’t have 2 grams to start.


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## Saddiq NG (May 29, 2022)

nickvc said:


> You desc your initial powder as grey which means it wasn’t anywhere near pure in fact very very dirty so if your solution is testing negative you have all the gold that was there in the first place as you didn’t have 2 grams to start.


But why is this so. I refined the gold twice and it's still dirty. Maybe the problem is with the iron sulfate I'm using then. Another thing I need to know is what impurity turns gold powder to grey.


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## Yggdrasil (May 29, 2022)

Saddiq NG said:


> But why is this so. I refined the gold twice and it's still dirty. Maybe the problem is with the iron sulfate I'm using then. Another thing I need to know is what impurity turns gold powder to grey.


As far as I know, nothing turns Gold to grey powder, but if you have other metals in there particularly Tin it can look grey.
Did you use different methods of precipitating the gold?


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## Shark (May 29, 2022)

Saddiq NG said:


> I used 100ml HCl and about 9ml HNO3 and 6ml H2SO4 to dissolve the gold. I heated the reaction moderately to make it fast and to eliminate any excess nitric acid. I filtered the solution when the reaction was done, diluted the solution with water and then I added the ferrous sulfate to precipitate the gold.


This needs filtering after the water is added. This will remove any silver that the dilution may cause to drop out.


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## Saddiq NG (Jun 4, 2022)

Yggdrasil said:


> As far as I know, nothing turns Gold to grey powder, but if you have other metals in there particularly Tin it can look grey.
> Did you use different methods of precipitating the gold?


No I only use iron sulfate. I have however come to realise that when I boil the gold sediment in nitric acid, the sediment will change to brown or red which is what I expect. What annoys me is when I try to refine, the mass of the gold always reduces by half. I also found out that if I add nitric acid and sulfuric acid to the solution in stock pot, after adding iron sulfate a second time the gold clouds still form again.


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## Yggdrasil (Jun 4, 2022)

Saddiq NG said:


> No I only use iron sulfate. I have however come to realise that when I boil the gold sediment in nitric acid, the sediment will change to brown or red which is what I expect. What annoys me is when I try to refine, the mass of the gold always reduces by half. I also found out that if I add nitric acid and sulfuric acid to the solution in stock pot, after adding iron sulfate a second time the gold clouds still form again.


No the mass of Gold do not reduce. The gold stay as it is, but the base metals are dissolved, which means it was quite impure.
After Nitric you have even purer Gold, so when you dissolve it, and precipitate it will be actually refined.


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## eaglekeeper (Jun 4, 2022)

Saddiq NG said:


> No I only use iron sulfate. I have however come to realise that when I boil the gold sediment in nitric acid, the sediment will change to brown or red which is what I expect. What annoys me is when I try to refine, the mass of the gold always reduces by half. I also found out that if I add nitric acid and sulfuric acid to the solution in stock pot, after adding iron sulfate a second time the gold clouds still form again.



How pure is your ferrous sulfate?

Did you filter your ferrous sulfate solution before use.... I found that there is some contamination in the store bought stuff.... usually iron particles. Oxidized iron can look brownish red. 

As silver1 said....you didn't DeNOx, simply heating it doesn't fully DeNOx your solution. Do you have access to sulfamic acid (wood bleach), that is what's recommended for DeNOx'ing.


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## Shark (Jun 4, 2022)

Saddiq NG said:


> I used 100ml HCl and about 9ml HNO3 and 6ml H2SO4 to dissolve the gold. I heated the reaction moderately to make it fast and to eliminate any excess nitric acid. I filtered the solution when the reaction was done, diluted the solution with water and then I added the ferrous sulfate to precipitate .


Did you use the ferrous sulfate in powder form or did you prepare it ahead of time.


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## Saddiq NG (Jun 4, 2022)

eaglekeeper said:


> How pure is your ferrous sulfate?
> 
> Did you filter your ferrous sulfate solution before use.... I found that there is some contamination in the store bought stuff.... usually iron particles. Oxidized iron can look brownish red.
> 
> As silver1 said....you didn't DeNOx, simply heating it doesn't fully DeNOx your solution. Do you have access to sulfamic acid (wood bleach), that is what's recommended for DeNOx'ing.


Yes I always filter my ferrous with cotton and sometimes with HCl to keep the iron impurities away. 
For the deNOxing however I only use heat, I have never used urea or sulfamic acid before. I have seen this sulfamic acid in the chemicals shop before. I am going to buy it.


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## Saddiq NG (Jun 4, 2022)

Shark said:


> Did you use the ferrous sulfate in powder form or did you prepare it ahead of time.


No I used to dissolve it in water, then I will filter off any undissolved and heavy particle with cotton and sometimes with HCl. Then I will immediately pour it into the gold chloride solution.
I however heard that ferrous sulfate has a life span of 4 months maximum after which it turns to ferric sulfate. And I do not know how I can tell if mine is expired.


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## FrugalRefiner (Jun 4, 2022)

If it's still green, you're OK. When it turns brown, it's no longer useful.

For longer life, keep it well sealed away from air, and add a small amount of sulfuric acid. Be careful with the sulfuric acid. It will eat your flesh.

Dave


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## Shark (Jun 4, 2022)

Stick to using HCl to prepare the ferrous sulfate. I am not sure water will do it. As Dave mentioned, as long as it has not turned brown it will work. If it has turned a pale white it needs HCl then filtered. The solution of ferrous sulfate should be a pale greenish color when ready to use.


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## Kuldne (Jun 5, 2022)

Better to use lab grade iron sulfate. The stuff you buy from garden store has often already trivalent cations in it. Lab grade iron II is slightly greenish after dissolving in water. Adding few drops of HCI, makes it totally white and transparent.


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## Saddiq NG (Jun 6, 2022)

FrugalRefiner said:


> If it's still green, you're OK. When it turns brown, it's no longer useful.
> 
> For longer life, keep it well sealed away from air, and add a small amount of sulfuric acid. Be careful with the sulfuric acid. It will eat your flesh.
> 
> Dave


Thanks Man


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## Saddiq NG (Jun 6, 2022)

Kuldne said:


> Better to use lab grade iron sulfate. The stuff you buy from garden store has often already trivalent cations in it. Lab grade iron II is slightly greenish after dissolving in water. Adding few drops of HCI, makes it totally white and transparent.


Yes my own is Lab grade. I buy it from a laboratory chemical store.
I Read in Hooke's book that the HCl making it transparent is what is needed as all the impurities from the iron sulfate will dissolve in it


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