Modern Mining March 2015

DIAMONDS

Liqhobong off to a strong start Firestone Diamonds, the AIM-quoted diamond development company developing the Liqhobong mine in Lesotho, says that the project is currently within budget and on schedule to achieve initial production at the end of H1 2016. In its recently released results for the six months ended 31 December 2014, the company says achievements thus far include a safety record of zero lost time injuries and the creation of approximately 1 000 jobs in Lesotho.

A lthough Liqhobong has been mined in the past, the new proj- ect will see mining at the site on a much larger scale. The new US$185,4 mine is designed to deliver 1,1 million carats a year over 15 years, which is roughly 10 times what nearby Letšeng – Lesotho’s best known mine – produces (al- though the dollar price per carat of Letšeng’s stones is the highest of any kimberlite mine in the world). The project is based on mining the main pipe (there is also a satellite pipe) at the site down to 393 m over 15 years, exploiting a reserve of over 11 million carats at a grade of 32,07 cpht. The anticipated average strip ratio of waste to ore is 2,28. The ore will be treated in the Main Treatment Plant (MTP) which utilises a conventional flowsheet comprising scrubbing, screening, crushing, concentration via DMS, and final recovery using X-ray machines. The plant will have 2 x 250 t/h streams. According to Firestone Diamonds, the first six months of the construction phase – which started in late June 2014 – encountered both winter and summer weather conditions. The winter was relatively mild which enabled the project to start well and the project team to get ahead on a number of work streams before enter- ing the start of the rainy season in November. The above average rainfall experienced in November and December and delays expe- rienced in the issuing of work permits to the civils and earthworks contractor had an initial negative impact, necessitating a re-scheduling of certain works and increased work load. The project team also encountered areas where excess top soil needed to be removed which, in combination with the wet weather, caused days to be lost through personnel not being able to work safely. Additional crews were deployed to ensure that development remains on schedule and within budget. Work on the residue tailings facility starter wall and the accommodation terraces is also progressing well. Overall, as at the end of

December, the project was marginally ahead of schedule with significant progress being made on the construction of the tailings dam wall, as well as other earthworks and site preparations. Design, engineering and procurement were set as a priority by the development team and sig- nificant progress has been made ahead of the scheduled targets to ensure the smooth comple- tion of the project. The provision of electrical infrastructure to connect the mine to grid power is a sepa- rate undertaking which is also progressing as planned. The total grid power project cost is R165 million with Firestone funding R145 million and the balance of R20 million being funded by the local company engaged to con- struct the power infrastructure. All equipment and long lead item orders have been placed and site preparation for the substations is well advanced. Connection to grid power is expected to be achieved during the second half of 2015, ahead of the initial schedule. At the end of December, a total of R1,28 bil- lion in orders out of the total budgeted R1,43 billion EPCM contract (being undertaken by DRA) had been placed. The three largest sub- contracts under the EPCM contract, totalling R943 million, have been agreed on a fixed price/cost basis to remove price escalation risk. The grid power and Main Treatment Plant projects combined have created over 1 000 local jobs, and it is expected that the level of employment will continue to increase as con- struction progresses. 

View of the site in January this year (photo: Firestone Diamonds).

Connection to grid power is expected to be achieved during the second half of 2015, ahead of the initial schedule.

March 2015  MODERN MINING  31