gold and palladium solution

[arthur kierski]

which one is precipitated first?i think pd first---am i correct(right)??

 

[kelly]

I drop the gold first, then concentrate the solution and drop palladium

 

[Oz]

What is the ratio of gold/palladium?

What precipitants do you plan on using?

What contaminates are with them in solution?

Depending on the ratio it may be best to precipitate or cement both as fine particles then wash with nitric leaving your gold as elemental and your palladium in solution.

 

[Harold_V]

My personal opinion, based on processing dental gold on a fairly regular basis, is to precipitate gold first. If you precipitate palladium from a solution that bears gold, it will be difficult to eliminate the gold that is dragged down by the palladium. The salt of palladium is soluble in water, so washing is troublesome without dissolving some of the palladium.

I routinely precipitated with SO2, which has a tendency to drag down traces of palladium along with the gold. The precipitate was always a dark brown color. I accepted that as one of the problems of processing the two metals from a single solution, and refined the resulting gold a second time. That seems to eliminate the included palladium, or it is reduced to an insignificant level, if nothing else.

You may wish to see this from a different perspective if you have a solution rich in palladium and contains only traces of gold.

Remember----it your solution is relatively dilute, it's entirely possible you won't achieve precipitation of palladium. It is unlike gold in that regard.

Harold

 

[arthur kierski]

thanks for the replyes--i will do what harold and kelly sugested since the main metal in the solution is gold--oz is absolutelly right in his sugestion(but the solution is ready to drop the values)-thanks all

 

[Oz]

With high gold content and little Pd I agree with Harold. I know that you work with PGMs often so I thought it may have been the other way around.

Something to be aware of is that Harold used SO2 gas and I believe you are using SMB last I heard. If you have a liter of solution that is concentrated to 10 troy ounces Au per liter then you will have over 300 grams of SMB per liter added to your solution. After precipitating your gold if you have only 10 grams per liter Pd, you will wish to concentrate your now Pd solution further to get closer to a full recovery of the Pd. When you concentrate further you may find that you are forming sodium chloride crystals before you reach a good concentration. Harold of course did not have this concern since he used the SO2 gas. If this becomes a problem, cement your Pd values and wash to remove the sodium chloride from the equation and proceed as usual.

On the other hand if it had been higher in Pd the precipitants used for making a salt of the Pd would not interfere with the precipitation of the gold with SMB afterwards as gold can easily be precipitated from more dilute solutions. In the future if you need to precipitate your Pd first you will want to wash your Pd salt free of the gold still in solution with your ammonium chloride or sodium chlorate precipitating solutions instead of water as Harold pointed out.

Let us know how it turns out.