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

[kurtak]

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

 

[icejj]

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

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!

 

[orvi]

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.

 

[Vinny PaisAuno]

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.

Would this work on silver powder from the lye sugar process? Has anyone tried it?

I kept decanting what I thought was sugar and lye solution but after a few times I realized it was fine silver particles.

After that I started gravity filtering, it actually filtered really nicely, and captured an additional 3 grams of silver.

I was surprised that it was so little, and I only ended up losing about three grams total out of an expected 160gm.

 

[Yggdrasil]

Would this work on silver powder from the lye sugar process? Has anyone tried it?

I kept decanting what I thought was sugar and lye solution but after a few times I realized it was fine silver particles.

After that I started gravity filtering, it actually filtered really nicely, and captured an additional 3 grams of silver.

I was surprised that it was so little, and I only ended up losing about three grams total out of an expected 160gm.

The Lye/Sugar process should have produced heavy Silver grains.
Can you explain what you did step by step?

 

[Vinny PaisAuno]

The Lye/Sugar process should have produced heavy Silver grains.
Can you explain what you did step by step?

Thank you Yggdrasil. Yes no problem.

The bulk of the silver settled very fast, but a small amount was very fine and cloudy and took 24 hours to settle, only to re-suspend with the slightest movement.

Overall I'm very happy with the silver recovery and can't wait to melt it.

My process was as follows

1. Silver rounds were used for inquartation of karat scrap. And inquarted gold was dissolved in 50\50 (36%) nitric solution.

2. After parting gold from silver, I filtered blue nitrate solution then added NaCl to drop silver chloride.

3. I washed the silver chloride in very hot water (180F) at least 10 times.

4. Added NaOH to the silver chloride slurry while mixing vigorously with an immersion blender until jet black. Very exothermic!

5. Added table sugar to the slurry very slowly while stirring with a spoon until temperature started dropping off and it was obvious the conversion was complete. Also very exothermic.

6. Decanted, washed silver powder and repeated about 5 times when I realized I was probably pouring off some finely suspended silver. Continued washing and decanting through a filter until it was very clean and neutral ph. Only captured about 3gm in filter may process later.

7. Dried silver powder in oven at 200F.

 

[Vinny PaisAuno]

Incidentally regarding my gold refining, I did use a few ml of sulfuric acid after the SMB drop and some heating. That really made it agglomerate and settle very nicely and quickly. I think it went really well. The SMB drop was amazing, it kept dropping as I added SMB and stirred and then after last spoonful it just stopped abruptly. Very obviously done dropping. Supernatant was crystal clear and negative for stannous test.

 

[Yggdrasil]

Incidentally regarding my gold refining, I did use a few ml of sulfuric acid after the SMB drop and some heating. That really made it agglomerate and settle very nicely and quickly. I think it went really well. The SMB drop was amazing, it kept dropping as I added SMB and stirred and then after last spoonful it just stopped abruptly. Very obviously done dropping. Supernatant was crystal clear and negative for stannous test.

Nice powder

 

[Yggdrasil]

Thank you Yggdrasil. Yes no problem.

The bulk of the silver settled very fast, but a small amount was very fine and cloudy and took 24 hours to settle, only to re-suspend with the slightest movement.

Overall I'm very happy with the silver recovery and can't wait to melt it.

My process was as follows

1. Silver rounds were used for inquartation of karat scrap. And inquarted gold was dissolved in 50\50 (36%) nitric solution.

2. After parting gold from silver, I filtered blue nitrate solution then added NaCl to drop silver chloride.

3. I washed the silver chloride in very hot water (180F) at least 10 times.

4. Added NaOH to the silver chloride slurry while mixing vigorously with an immersion blender until jet black. Very exothermic!

5. Added table sugar to the slurry very slowly while stirring with a spoon until temperature started dropping off and it was obvious the conversion was complete. Also very exothermic.

6. Decanted, washed silver powder and repeated about 5 times when I realized I was probably pouring off some finely suspended silver. Continued washing and decanting through a filter until it was very clean and neutral ph. Only captured about 3gm in filter may process later.

7. Dried silver powder in oven at 200F.

Are you sure that the slow settling "debris" are Silver?

 

[Vinny PaisAuno]

Actually now that you mention it, perhaps it could be something else. But what could it be?

I washed the silver chloride so well I can't imagine anything else came with it. Not in the quantity I was seeing washing the silver powder anyway.

It could potentially be un reacted silver chloride that didn't convert to oxide. But it was pretty darn black and no white flecks or smears of AgCl.

The lye and sugar would have been washed out long ago especially because pH is neutral.

I guess I could melt the 3 grams of stuff in the filter and see what happens.

Perhaps using the immersion blender was just a bit too much mechanical overkill.

I could just keep washing and filtering until it goes away, but I feel like that should have happened already, I have literally done it between 10 and fifteen times already.

But I want to do things the right way too so whatever it takes.

Thanks again for your help, Vin