Water Reclamation and Tailings
The concentrated ore, now called copper concentrate, is dewatered
and dried to about 10% moisture content. It is shipped by truck
to the Asarco smelter in Hayden, Arizona. (The El Paso smelter
is on stand-by status). Water is recovered from the tailings
in another thickener. The thickened tailings flow by gravity
in large pipes to tailings ponds, where the solid material settles
out and additional water is recovered and pumped back to the
mill. About 80% of the water used at the mine is recycled and
re-used. The rest is lost to evaporation and used to keep haul
roads damp to minimize dust.
After a tailings dam is decommissioned, the tailings are capped
with dirt and treated with manure for grazing cows or amended
with biosolids (sludge) from a local waste water treatment plant.
This provides organic material and nutrients to create a sustainable
soil for native grasses and shrubs.