Dissolution of Precious Metals in Supercritical CO2

[Chumbawamba]

Found this paper abstract whilst googling:

Dissolution of Precious Metals in Supercritical Carbon Dioxide
http://pubs.acs.org/doi/abs/10.1021/ie040198m

Abstract:

Precious metals including copper, gold, and palladium can be dissolved in supercritical CO2 by oxidation with HNO3 and subsequent chelation with hexafluoroacetylacetone to form CO2-soluble metal β-diketonate complexes. The oxidizing agent HNO3 is carried into the supercritical fluid phase by the CO2-soluble Lewis base tri-n-butyl phosphate (TBP) as a complex of the general form TBP(HNO3)x(H2O)y. For the dissolution of Pd metal, a Lewis acid−base complex of the form TBP(HNO3)1.0(H2O)0.4 is required. Au and Cu can be oxidized with a lesser amount of HNO3 in the complex. This supercritical fluid dissolution technique provides a “dry” method for recovering precious metals from abandoned electronics and spent catalysts with minimum waste generation.

Am trying to locate a copy of the complete paper. Anyone have access to ACS papers?

 

[Irons]

:mrgreen:

 

[Lou]

I can get the paper but it is of nothing more than academic curiousity. I can not see it being used industrially.

 

[Chumbawamba]

Hi Lou.

Is that because of the expense or the complexity of process or low yield rate?

 

[Lou]

Probably all of those reasons. It's somewhat equipment intensive.

 

[jsargent]

Probably all of those reasons. It's somewhat equipment intensive.

I believe de-caffeinated coffee is produced using super critical CO2 extraction, so the equipment is available, at a cost. Maybe it will work as claimed on gold ore?

I can tell you this: It works like a charm for extracting organic contaminants from soil samples for testing, without using organic solvents. We had a small unit at our contaminants lab in the mid 1990's.

 

[a_bab]

While a device for supercritical extraction can be home built with some 1500 bucks, the usefull volume will be rather small: http://www.aerogel.org/?cat=33 (these guys use it to supercritical dry the aerogel, but the device would work for extraction too).