25 Jun 2020

Underground mining is expected to double Lucara’s mine life from the original 2010 feasibility study.

Lucara Diamond Corporation vice president, Dr John Armstrong said this during minister of Mineral Resources, Green Technology and Energy Security, Mr Lefoko Moagi’s visit to the mine this week. He said underground mining would expand the life of the mine by 20 more years from 2020 to 2040. He added that the project capital cost was estimated at US$667.5 million.

Dr Armstrong noted that underground mining would be undertaken from 2020 to 2025 with full production from underground expected to commence in 2025/2026.

He stated that resource work completed post Preliminary Economic Assessment (PEA), identified a much larger economic opportunity at depth of the mine pit on the basis of new drilling and open pit recoveries.

He highlighted that underground mining would bring US$4 billion in additional revenue with over US$200 million in revenue from exceptional diamonds. 

The Karowe mine pit has three lobes being south, centre and north and mining would be concentrated on the south lobe, as it has produced Karowe’s top recoveries such as Lesedi La Rona, the Constellation and Sewelo, among others.

Operational readiness manager, Mr Leonard Marumo stated that long hole shrinkage, a hybrid between the vertical crater retreat method and block cave has been considered the best mining method for underground.

 Mr Marumo said the benefits of long hole shrinkage was that it allowed for mining of highest value first, leading to an increase in revenue of over US$150 million per year in early years. 

 The shrinkage method, he said, maintained 60 to 70 per cent of the ore in the stopes until the entire deposit was mined.

He said long whole shrinkage would lead to minimal dilution until late in the mine life ensuring that payback was achieved before weak waste rock could be exposed.

Mr Marumo also added that underground mining and simultaneous production would enable the mine to bring value forward with no dip in production as well as low operational expenditure.

The operational readiness manager noted that underground mining required new power supply from Botswana Power Corporation (BPC), adding that underground and overhead line sections as well as full commissioning had been completed with a new operational line. 

Minister Moagi said the purpose of his visit was to appreciate challenges post the COVID-19 lockdown and to facilitate how the economy could be sprung back to life. Ends