Blackthorn Resources has increased its mineral resource estimate for its Kitumba project in Zambia by 25% since April 2013 following the completion of its phase 7 drilling programme. Using a 1% copper cut-off, the deposit now contains a total measured and indicated mineral resource of 34.7 Mt at 2.29% copper for a total of 795 000 t of copper.

Blackthorn Resources holds a 100% interest in the Mumbwa iron oxide copper-gold (IOCG) project, located within the Mumbwa project area in Zambia.

A key improvement on the previous mineral resource estimate is the inclusion of measured material. The deposit now contains 10.4 Mt in the measured category at a grade of 2.93% copper using a 1% cut-off for a total of 306 000 t of copper, or approximately 38.5% of the total contained copper in the measured and indicated categories.

“We are delighted with this mineral resource update. The excellent results reported from the drilling programme have translated into an increase in tonnes, grade and confidence level, delivering an increase of over 25% in contained copper metal in the high-grade zone of the Kitumba deposit. This confirms Kitumba’s ranking as one of the highest grade undeveloped copper resources of ASX-listed projects,” says acting CEO Mike Oppenheimer.

The phase 7 drilling programme commenced in June 2013 and was designed to increase the confidence level of the mineral resource. The programme included 10 resource definition holes within the Kitumba deposit, as well as three geotechnical holes, four new holes and the extension of two existing holes focused on satellite targets near Kitumba for a total of 9 616 metres. A total of 81 holes and 45 587metres were used in the estimate.

Infill drilling during phase 7 yielded world class copper intercepts which have had a clear impact on the high-grade portion of the deposit, located between a 180 and 500 metre vertical depth from surface, and extends along strike for a distance of about 500 metres and across strike for about 300 metres.

Work on optimisation of the prefeasibility study was initiated in November 2013 and is focused on further metallurgical testing to improve copper recoveries, as well as identifying processing options within the preferred hydrometallurgical flow sheet.

“With over 10 Mt of mineral resource at nearly 3% in the measured category, or 306 000 t of contained copper metal, we look forward to being able to announce an update to the ore reserve estimate, once the optimised mine plan has been completed.”

“While this mineral resource upgrade on its own is expected to materially enhance the economics of the Kitumba deposit, we are now focussed on achieving further improvements through the optimisation of the other key economic drivers, including metallurgy and process plant design to improve metal recovery, in parallel with optimisation of the mine design,” Oppenheimer notes.

The PFS optimisation is proceeding to schedule and is expected to be completed by April 2014.