Constellation Implements Production Enhancements at Lisbon Valley Copper

Constellation Copper Corp. recently reported on the progress of production enhancement projects under way at its Lisbon Valley surface mine located in southeastern Utah, USA. The company said its immediate focus has been on increasing the amount of contained pounds of copper placed on the leach pad and expediting construction of an Intermediate Leach Solution (ILS) system.

During July and August 2007, Lisbon Valley commissioned a fleet of three 100- ton capacity trucks and started hauling and stacking primary crushed ore onto an 800,000-ton-capacity section of the leach pad. Previously, all ore was processed through a secondary crushing system before being loaded on the leach pad.

The company said the decision to leach primary crushed ore resulted from the inability to process all of the ore being mined through the secondary crushing and stacking system. Any excess ore is now being hauled directly to the leach pad, with a goal of placing at least 6 million lb of contained copper per month on the pad. As of the end of August, 383,000 tons of primary crushed ore, containing approximately 5 million lb of copper, had been stacked. Initial leaching of this ore began during the first half of September 2007. Continuation of the truck stacking program will depend on an assessment of the effectiveness of the program once initial leach results have been compiled.

Constellation expects the ILS system is expected to double the amount of ore maintained under leach and help offset the expected slower recovery of sulphide copper. In addition, copper concentration in the Pregnant Leach Solution (PLS) are expected to increase significantly as a result of recycling leach solution back over the leach pads before it is processed through the SX/EW facility. The earthwork part of the ILS project was completed in early September 2007, and lining the pond, assembling the pumping plant, and installing the large piping system required to facilitate doubling the leach solution flow rate was scheduled to begin in mid- September. Lisbon Valley expects to start the ILS system in November 2007, and have it at full capacity by mid-spring 2008.

In order to mitigate problems Lisbon Valley experienced last winter with low solution temperatures, it has placed plastic insulating balls on all three solution ponds. Another cold weather mitigation project, completed in the spring 2007, involved converting the solvent extraction plant to parallel flow to allow slower solution flows through each SX extractor, while increasing the total flow rate 16%.