# Gold taking a long time to settle after third wash cycle with water



## icejj (Dec 9, 2021)

First, I'd like to thank everyone for the wonderful information that I've received from this forum, it has help me tremendously with understanding different processes and techniques.

The issue that I'm facing is that I'm having trouble understanding why my gold is taking so long to settle after a third wash cycle with water, and I am seeking help to understand why.

After dropping gold with SMB from aqua regia and pouring off the aqua regia, I was left with gold mud (as usual). I then started to perform the wash cycle. I boiled the gold mud in water, then allowed the gold to settle, in which it only took maybe 10 minutes or so to completely settle and the wash water was very much clear. The gold mud moved around very freely in the bottom of the beaker when shifting the beaker. I then poured off the water. I repeated the wash cycle a second time with water, and again, the gold settled in minutes just as the first wash cycle.

After repeating the wash cycle for a third time with water, the gold did not completely settle. In fact, after about 12hrs, it has only partially settled, with the water still being noticeably dark with gold mud floating around. I'm wondering why this has happened, when the first two wash cycles settled immensely faster! I have never run into this situation, so any help or insight would be much appreciated. Thanks!


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## icejj (Dec 9, 2021)

After the third wash


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## Martijn (Dec 9, 2021)

Give it some heat to a gentle boil with a little bit of sulfuric acid. A couple of ml will do. It wil make the gold particles clump together and settle better.


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## icejj (Dec 9, 2021)

Thanks for the info. I'll go try it now. Do you know why this may have happened? Especially as opposed to why this didn't happen in the first two wash cycles? I thought it was weird since I didn't do anything different in the third wash from the first two washes...


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## icejj (Dec 9, 2021)

Martijn said:


> Give it some heat to a gentle boil with a little bit of sulfuric acid. A couple of ml will do. It wil make the gold particles clump together and settle better.


It worked! Thanks a ton. Should this be done as a general practice, or only if one runs into this issue?


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## orvi (Dec 10, 2021)

icejj said:


> It worked! Thanks a ton. Should this be done as a general practice, or only if one runs into this issue?


Yes, it is done in the classical refining procedure. Dropping gold, mainly from AR solutions with lot of base metal cause fine gold to "drag" base metal impurities with it and encage them into aggregates of forming gold precipitate. I use boiling with HCl, till washes are colorless. Then i continue with water. Sulfuric is another option, no nasty fumes when lightly boiling dilute H2SO4... maybe this will be the main advantage. But HCl evaporates easily, so traces of acid, if present after (improper) workup, just vaporize.


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## icejj (Dec 10, 2021)

orvi said:


> Yes, it is done in the classical refining procedure. Dropping gold, mainly from AR solutions with lot of base metal cause fine gold to "drag" base metal impurities with it and encage them into aggregates of forming gold precipitate. I use boiling with HCl, till washes are colorless. Then i continue with water. Sulfuric is another option, no nasty fumes when lightly boiling dilute H2SO4... maybe this will be the main advantage. But HCl evaporates easily, so traces of acid, if present after (improper) workup, just vaporize.


Thanks for the clarification. I also boil with HCl until colorless, but not dilute H2SO4 until today, which solved my issue.


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## Geo (Dec 10, 2021)

H2SO4 can also be used to break many different colloids. I mix a diluted solution of 10/1 water and H2SO4 (respectively). Then this solution is added to the colloid or nearly any solution with high turbidity. In this respect, it acts as a flocculent. Another, less dangerous, flocculent is MgSO4 (epsom salt). Add this to solutions that are murky and let it set undisturbed a couple of days.


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## Martijn (Dec 10, 2021)

As to why this happened on the third wash, maybe you stirred it up a bit more? 
I use this wash procedure: 
Thread 'Getting pure gold (shining)' Getting pure gold (shining)
That looks like a troy ounce of gold you have in that beaker by the way! Please share a picture of that button!


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## icejj (Dec 10, 2021)

Geo said:


> H2SO4 can also be used to break many different colloids. I mix a diluted solution of 10/1 water and H2SO4 (respectively). Then this solution is added to the colloid or nearly any solution with high turbidity. In this respect, it acts as a flocculent. Another, less dangerous, flocculent is MgSO4 (epsom salt). Add this to solutions that are murky and let it set undisturbed a couple of days.


Thanks! I will keep note of these tips for if/when I run into this type of situation. This is very helpful.


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## icejj (Dec 10, 2021)

Martijn said:


> As to why this happened on the third wash, maybe you stirred it up a bit more?
> I use this wash procedure:
> Thread 'Getting pure gold (shining)' Getting pure gold (shining)
> That looks like a troy ounce of gold you have in that beaker by the way! Please share a picture of that button!


I don't think I stirred it up anymore than the other washes, but I'm not sure. Thanks for the wash procedure, that is the wash procedure that I was implementing, I had just decided to wash the gold in water first a few times to make sure that any leftover aqua regia was gone. And thanks, I'm hoping for an ounce! I'll share a pic of the button after melting!


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## icejj (Dec 11, 2021)

Martijn said:


> As to why this happened on the third wash, maybe you stirred it up a bit more?
> I use this wash procedure:
> Thread 'Getting pure gold (shining)' Getting pure gold (shining)
> That looks like a troy ounce of gold you have in that beaker by the way! Please share a picture of that button!


The wash procedure says to add water to HCl and ammonia when performing washes with them. Is there any advantage to adding water to HCl or ammonia when performing washes as opposed to washing in concentrated HCL or ammonia? Just curious as to why water is combined with the chemical used for washing. I realized that I haven't been adding water to the chemicals used for washing, and also don't know the ratio of water to HCl/ammonia for washing.


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## Martijn (Dec 11, 2021)

Not sure, but i think to make room for the salts of the contaminations to dissolve in the water.


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## snail (Dec 13, 2021)

I believe it was Lou that recommended a couple of boils in full strength HCl.
Hot it picks up silver contamination pretty well.
Has given me good results.


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## icejj (Dec 14, 2021)

snail said:


> I believe it was Lou that recommended a couple of boils in full strength HCl.
> Hot it picks up silver contamination pretty well.
> Has given me good results.


Thanks for your input! I usually do full strength, but have heard of others adding water so I was a bit confused. I haven't processed enough to know the difference.


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## icejj (Dec 14, 2021)

Martijn said:


> Not sure, but i think to make room for the salts of the contaminations to dissolve in the water.


Ahhh I see.


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## icejj (Dec 14, 2021)

So what do you all think? Should I refine again or am I ready to melt? The first two pics are with the flash off. The next two pics are with the flash on. The last two pics are with the flash off. To me, the last pic with the beaker on the table seems to show the true color that I see. Lighting could be affecting the other pics.


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## Martijn (Dec 14, 2021)

Beatiful light brown gold powder! I say melt. Three nines fine or more i think. 
Good job done imo.


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## icejj (Jan 17, 2022)

Thank you all for your help and input!


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## Martijn (Jan 17, 2022)

Thats a beauty with nice gold crystal structure! Thanks for sharing the picture.


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## kurtak (Jan 17, 2022)

icejj said:


> The wash procedure says to add water to HCl and ammonia when performing washes with them. Is there any advantage to adding water to HCl or ammonia when performing washes as opposed to washing in concentrated HCL or ammonia? Just curious as to why water is combined with the chemical used for washing. I realized that I haven't been adding water to the chemicals used for washing, and also don't know the ratio of water to HCl/ammonia for washing.



I always do my HCl wash with full strength (31/32 %) HCl - full strength will dissolve most base metal drag down including *trace* drag down of AgCl --- dilute HCl is less likely to do so

any true salts (not the same as oxides) should dissolve in the water wash

you *only* need to wash with ammonia if you suspect *more then a trace* amount of AgCl drag down other wise the ammonia wash is not needed 

Kurt


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## icejj (Jan 17, 2022)

kurtak said:


> I always do my HCl wash with full strength (31/32 %) HCl - full strength will dissolve most base metal drag down including *trace* drag down of AgCl --- dilute HCl is less likely to do so
> 
> any true salts (not the same as oxides) should dissolve in the water wash
> 
> ...



Ah, okay I see. Thanks for your input! At times I felt as if an ammonia wash may have not been necessary, but I'd do it anyway just to make sure I didn't miss anything. Hard for me to judge right now. Thanks again!


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## orvi (Jan 17, 2022)

Very nice result. Washing multiple times don´t hurt much, boiling in HCl nicely agglomerates the gold = easy washing. Also when very dirty gold is dropped for example from AR dissolution of pins or other things, HCl wash till colorless is first point, than you wash with water and next concentrated ammonia (hot, but not boiling, or all of it evaporate). If you have copper inside, ammonia is great indication of it.


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