The problem is that the Romans got here first, and for 300 years hacked
out the easiest-to-get-at seams. The gold that is left is deep
underground and encrusted in a mineral called granodiorite, which also
contains sulfur and arsenic. Extracting the gold involves oxidizing the
rock using cyanide, which the company says it will do outside Spain.
Before that, the rock will be treated with biodegradable chemicals, a
process that only allows for a concentrate of 200 grams per tonne, which
is less cost effective.
http://elpais.com/elpais/2014/10/06/inenglish/1412590566_239055.html
No comments:
Post a Comment