Smallish tonnes but high grade, may as well look at the...

Smallish tonnes but high grade, may as well look at the possibility of mining and trying to use the pilot plant built in 2006 to see if it works. I know that it was a small scale pilot plant but was there ever an explanation of why this plant stopped in 2011? Was it economics and low Zn prices that stopped the show or was there some other technical reason such as lack of ore or poor recoveries from the plant ?