Non-Chemical Back in the Day

[ΩPhoenix]

This is only a comment not a question...

Old School Refining

After dissolving gold scrap and filtering out the chlorides we used to evaporate the filtrate to a crystal and rehydrate with HCL
repeating this 3 or more times to a crystal until no brown nitric oxide fume would appear.
These are the dishes we used were CoorsTek and held about 4 liters.
Doing this eliminated the use of Urea to sequester the HNO3 and allowed a complete precipitation of the gold
with Ferrous Sulphate .

Thanks
Steve Looser
ΩPhoenix Consulting

 

[Harold_V]

This is only a comment not a question...

Old School Refining

After dissolving gold scrap and filtering out the chlorides we used to evaporate the filtrate to a crystal and rehydrate with HCL
repeating this 3 or more times to a crystal until no brown nitric oxide fume would appear.
These are the dishes we used were CoorsTek and held about 4 liters.
Doing this eliminated the use of Urea to sequester the HNO3 and allowed a complete precipitation of the gold
with Ferrous Sulphate .

Thanks
Steve Looser
ΩPhoenix Consulting

That's the method that has been promoted on this forum since its inception (thanks to Hoke's book), but it does no harm to remind readers that urea is not necessary for refining. I spent more than twenty years refining and never used it.

Harold

 

[Lino1406]

From my experience this is the safe though long
way to not loose values
Lino1406,
author "25 recovery procedures of precious
metals..."

 

[lazersteve]

I've found the evaporation step is not necessary if one uses the nitric acid in very small doses with heat. Stop nitric additions when the fizzing and tiny bubbles cease after an addition. Once the fizzing and bubbles stop test to be sure the HCl is not used up by adding a few millilters of muriatic acid. If the fizzing and bubbles begin again you did not use enough HCl in the intial set up of the reaction.

An ounce of prevention is worth a pound of cure.

Steve

 

[ΩPhoenix]

This is only a comment not a question...

Old School Refining

After dissolving gold scrap and filtering out the chlorides we used to evaporate the filtrate to a crystal and rehydrate with HCL
repeating this 3 or more times to a crystal until no brown nitric oxide fume would appear.
These are the dishes we used were CoorsTek and held about 4 liters.
Doing this eliminated the use of Urea to sequester the HNO3 and allowed a complete precipitation of the gold
with Ferrous Sulphate .

Thanks
Steve Looser
ΩPhoenix Consulting

That's the method that has been promoted on this forum since its inception (thanks to Hoke's book), but it does no harm to remind readers that urea is not necessary for refining. I spent more than twenty years refining and never used it.

Harold

Thank you Harold

I had a copy of Hoke's book years ago.
I gave to my ex- girlfriend as a gift because
she helped me so much in growing the
company.