Sierra Gorda Scoping Study Outlines Major Project

Quadra Mining reported on July 23, 2009, that the scoping study for its 100%-owned Sierra Gorda copper-molybdenum project in northern Chile has outlined a $1.7-billion open-pit and concentrator operation that would process 111,000 mt/d of mill feed and produce between 250 million and 400 million lb/y of copper in concentrates over a 25-year mine life. Life-of-mine copper production costs, including by-product credits, would average $0.79/lb. Metal price assumptions for the study were $2/lb for copper, $12/lb for molybdenum, and $800/oz for gold.

Sierra Gorda molybdenum production would average 33 million lb/y during the first eight years of operations and would decline thereafter. With molybdenum credits included, copper production costs during the first eight years of operation are projected to average $0.34/lb.

The Sierra Gorda project is located 140 km northeast of Antofagasta, Chile, and about 200 km northeast of Quadra’s 75- million lb/y Franke heap leach–SX/EW copper project, which is starting up during the third quarter of 2009. BHP Billiton’s Spence project is located 10 km to the northeast of the Sierra Gorda project.

The Sierra Gorda deposit contains about 1 billion mt of sulphide mill feed. Grades average 0.42% copper, 0.027% Mo, and 0.069 g/mt gold. In addition, there are approximately 456 million mt of inferred resources. Significant oxide resources were assumed to be waste by the scoping study but will be the subject of future economic study.

Mining at Sierra Gorda will make use of conventional, large-scale, open-pit mining methods, using electric production drills and cable shovels and 340-mt haul trucks. The strip ratio will be 2.5:1. Pit parameters include 16-m bench heights and 38-m road widths at 8% grades. The processing plant will incorporate threestage crushing and ball-mill grinding and conventional flotation. Concentrate slurry will be piped 141 km to a port facility at Mejillones for thickening, filtering and loading onto ships.

The scoping study assumed that water will be supplied by a desalination plant at the coast and piped to the project. Lowercost ground water and upstream terrestrial surface water sources may be available, but permitting for their use remains uncertain.

Quadra presently intends to invest about $40 million in pre-feasibility and feasibility studies, including further metallurgical testwork, progression of the environmental impact study and associated permits, evaluation of all water supply options, infill drilling, and further trade-off and optimization studies to continue to improve project economics.

Quadra President and CEO Paul Blythe said, “We believe that we have the makings of a very substantial, long-life project at Sierra Gorda, and one that would be pivotal to the growth and future of the company.”.

As featured in Womp 2009 Vol 07 - www.womp-int.com