Lisbon bottleneck forces delay

Constellation Copper (CCU-T) says its Lisbon Valley copper mine in southeastern Utah will hit full steam three months later than originally forecast, owing to bottlenecking and grade control issues.

Copper production in June and July was short of forecast at 975,000 lbs. and 637,000 lbs. (some of July’s plated copper was not harvested by month’s end), as fewer tonnes of ore were placed on the leach pad. Production also suffered from lower head grades and below-budget acid and water addition on the heap.

The company says subsequent improvements to materials handling and plant feeding saw throughput increase by 45% to 17,000 tons per day during the second half of July; target capacity is 24,000 ton per day. The company has also refined its ore control process in the pits to reduce dilution.

Constellation has also arranged for an increased supply of sulphuric acid, and has begun drilling a back up well for the operation’s recently repaired water well. Pumping capacity is also being boosted.

Lisbon Valley is now expected to hit full production of around 4.5 million lbs. per month in December, rather than September. Production for the third quarter of 2006 is pegged at 4.6 million lbs., with another 11.7 million lbs. expected in the final stanza of the year. The company sill expects to produce more than 54 million lbs. of cathode copper in 2007.

The Lisbon Valley solvent extraction-electrowinning (SX-EW) plant yielded its first cathode copper in mid-April, and produced 804,000 lbs. of copper during the balance of the month. Copper production in May totalled more than 1.5 million lbs., while delivery of ore to the pad slipped owing to down time in the secondary crushers associated with processing a zone of finer-grained material and scheduled maintenance of the primary crusher.

At last count, Lisbon hosted proven and probable reserves totalling 36.7 million tonnes running 0.514% copper. Several satellite deposits and numerous prospects have been identified on the surrounding land package, which includes prospective claims in neighbouring Colorado.

Meanwhile, the latest batch of 8 holes from the compnay’s San Javier oxide copper project, in southern Sonora State, Mexico, returned an average thickness of 117 metres grading 0.4% copper. The previously reported initial 7 holes of the program yielded an average grade of 0.46% copper over 123 metres.

Highlighting the recent holes is an 84-metre section running 0.86% copper in hole no. 10. The first round of holes yielded a 123-metre interval of 0.75% copper in hole no. 6.

Drilling at San Javier is aimed at an area of copper oxide stained cliff faces around a hill about 200-to-300 metres in height. The company believes the area represents an iron-oxide copper-gold (IOCG) deposit with an exposed strike of up nearly 2 km, width up to 500 metres and about 100-to-200 metres in thickness.

Drilling continues in anticipation of a resource estimate by the end of the year.

Shares in Constellation were off 7, or 2.8%, at $2.47 in afternoon trading in Toronto following the news on Aug. 2.