White sediment after palladium AR volume reduction

Christopher.kurz · Sep 16, 2019

Hi Guys,
Any ideas why did I get a white sediment (that completely dissolved in hot water) after I reduced the volume of my Aqua Regia with dissolved palladium from MLCC.
I leached palladium with diluted nitric acid, filtered and then added HCl to both clear liquid and filter to further dissolve palladium.
The precipitated white sediment does not seem to be silver chloride as it dissolved in hot water during my attempt to wash it.
Any ideas?
Thx

anachronism · Sep 16, 2019

Hi

Nice to meet you. I need to know a few details before trying to help. What was the reason you thought that adding HCl would help given that you had already dissolved in Nitric?

Did you wash the MLCC in HCl to get rid of the Tin in the solder before you dissolved in Nitric?
Did you roast them after this to get rid of the HCl?
If adding HCl didn't precipitate any AgCl, would there actually be any Pd in the first place?

FrugalRefiner · Sep 16, 2019

A white sediment that dissolves in hot water is often lead chloride. When the hot water is cooled again, do white, needle like crystals form?

Dave

Christopher.kurz · Sep 16, 2019

anachronism said:
Hi

Nice to meet you. I need to know a few details before trying to help. What was the reason you thought that adding HCl would help given that you had already dissolved in Nitric?

Did you wash the MLCC in HCl to get rid of the Tin in the solder before you dissolved in Nitric?
Did you roast them after this to get rid of the HCl?
If adding HCl didn't precipitate any AgCl, would there actually be any Pd in the first place?

Hi, thank you for your reply.
1. HCl was added to drop Silver
2. MLCC was washed in HCl and then roasted and grinder before adding Nitric
3. MLCC were carefully selected, so should contain up to 3% Pd