An old paper but good bed-time reading for BBX ers...

An old paper but good bed-time reading for BBX ers
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.405.617&rep=rep1&type=pdf

No probs with gold , silver and PGMs and some selectivity depending on the resin chosen, pH and other chemical reagents.
There would appear to be a ready supply of suppliers for the materials needed
e.g.http://www.magpie-polymers.com/
"
Magpie Polymers fix metals through coordination chemistry: selective bonds are formed between the metals and the polymer beads. Whereas ion-exchange chemistry, commonly used in water treatment, uses charge to capture metals, Magpie delivers superior loading, preformance and selectivity.
The material consists of phosphine-oxide functionalities which coordinate selectively to precious metals (similar to TOPO but without the burden of liquid/liquid extraction). The phosphine oxide functionality is thermodynamically very stable, so that Magpie resins are:

• Extremely selective towards precious metals (despite 1000 x or higher concentrations of other pollutants)
• Stable in strong acid and oxidizing conditions including nitric acid (unlike thiol based resins)
• High performance (high loading and low residual metal concentration)

Magpie Polymers has fostered a culture of innovation and pursued the continuous development of its products since its inception. Our technology is patented and is the result of rigorous research aiming to mitigate environmental risks and capture lost value."

On the Pies!!