MK Gold enters permitting stage at Las Cruces

With grades averaging 5.94% copper, there isn’t much doubt about the economics of Las Cruces, a copper project being developed by MK Gold (MKAU-O) in Spain’s Iberian Pyrite belt. But with memories of the 1997 Los Frailes tailing spill lingering in the minds of citizens, there can be no room for doubt about the project’s environmental integrity.

MK Gold says its project was designed to a high standard of environmental care with the help of Bechtel, which produced the bankable feasibility study, and FRASA Ingenieros Consultores, which produced the environmental impact study.

Las Cruces will be an open-pit mine exploiting reserves of 15.8 million tonnes grading 5.94% copper. An average of 1.2 million tonnes will be mined and processed annually for at least 13.5 years, resulting in a projected 834,000 tonnes plus of cathode copper.

Before mining can begin, MK must excavate 150 metres of calcareous clay (known as marl), along with a thin sandstone aquifer overlying the deposit. Water resources in the region are protected in a plan that calls for the open pit to be de-watered and for the extracted groundwater to be re-injected into the aquifer, thereby preventing any adverse impact on the surrounding groundwater. Processing water will be pumped 15 km from a sewage treatment plant in Seville.

The environmentally safe hydrometallurgical facility is based on a ferric leaching process developed by Dynatec. The ore will be crushed and ground using conventional technology, followed by leaching and solvent extraction-electrowinning (SX-EW) to produce cathode copper of London Metal Exchange-grade quality.

The plant can produce up to 72,000 tonnes of cathode copper per year, though annual production is expected to average 63,000 tonnes over the mine life. Capital costs are estimated at US$289 million; average cash operating costs, at US33 per lb.

Tailings from the process plant will be filtered, producing a nearly dry material that will be progressively encapsulated in marl. This system of tailings management eliminates the need for a conventional tailings dam with the associated risk of failure.

After mining ends, the open pit will be partially backfilled with marl to isolate the aquifer and mineralized zone in the base of the open pit. It will then be filled with run-off water to create a permanent lake of good-quality water. The remaining overburden will be carefully contoured and re-vegetated throughout mining operations and after the mine closure.

Spain has numerous incentives in place to attract mining investment, mostly because unemployment in some rural regions is high. In Andalusia, for example, most citizens welcome the 1,000 jobs that will be created during the construction phase and the 270 permanent positions during operations. But the environment matters too, as MK Gold knows from its operating experience in the western U.S., where standards rank among the highest in the world.

The company has won several environmental awards for its work in the U.S. In 1997, the California Mining Association awarded the American Girl mining joint venture, managed and 53%-owned by MK Gold, its Excellence in Reclamation Award for reclamation activities completed in early 2000. Situated in an arid desert, the American Girl project consisted of an open pit and underground mine, as well as heap-leach pads and a 750-ton-per-day mill. Also, in 1994, the Oregon government presented MK with an Outstanding Reclamation Exploration Award for its work at an exploration project.