rru2s, You said, "The SX and IEX processes don't lend themselves...

rru2s,

You said,

"The SX and IEX processes don't lend themselves to any size runs. They have minimum thresholds."

Not true, in fact a tiny little plant producing maybe 2 or 3 tonnes a year will have a way lower unit cost/kg because it is much cheaper to build, run and maintain than a 500 or 1000TPA plant. The equipment in a smaller plant is throw away due to the small size and doesn't require the durability and specialist maintenance/equipment that larger plants require. It is also much easier to recover from process upsets to produce on-spec product and clearly has the capability for very large surge capacity between recovery units for the various metals, and thus can be run as a batch process.

Don't get me wrong here, I'm not a huge fan of MCP's story but it may well be that it's not hard for them to build a tiny little HRE recovery process. Whether there's a buck in it for them or not remains to be seen.