Modern Mining June 2015

MINING News

Trial mining of the eastern lobe of the Baoulé kimberlite pipe (photo: Stellar Diamonds).

AIM-listed Stellar Diamonds recently announced an operational update from trial mining at its 75 %-owned, 5 ha Baoulé kimberlite pipe in Guinea in West Africa. The trial mining has yielded a total of 5 087 carats to date at an average grade of 13,5 cpht and high quality gems continue to be recovered, including stones of 12,6 carat and 10,0 carat. The first sale of 733 gem quality carats from Baoulé in March realised US$195 000 for an average value of US$266 per carat (which formed part of a larger sale of 4 414 carats). Included in this sale was a 5,55 carat stone which sold for US$5 000 per carat and several stones which exceeded Good progress reported on trial mining at Baoulé US$1 000 per carat, underpinning the high value and quality of some Baoulé gems. Stellar Diamonds Chief Executive Karl Smithson commented: “Good progress continues to be made from trial mining at Baoulé. Our objective is to produce 15 000 carats from this exercise to enable us to determine the grade, value and presence of large stones in the pipe, with a view to using this information to consider a deci- sion to advance Baoulé to commercial scale mining. “It is pleasing that we have achieved our maiden revenues following the first diamond sale from Baoulé, as well as other Stellar projects. We are currently planning

the next export and sale of Baoulé goods and remain committed to targeting addi- tional diamond sales throughout 2015.” Trial mining of the eastern lobe of the Baoulé kimberlite pipe has continued dur- ing the first quarter of 2015. In order to maximise the pit area in preparation for the second 3 m cut, mining progressed towards the eastern and southern margin of the pipe where a lower grade contact breccia was recently encountered, reduc- ing the average grade to 13,5 cpht at a 1,25 mm cut off. This has resulted in fewer car- ats being produced than anticipated at this point in time, but mining and processing of the second cut is expected to see a return to higher grades, based on the results realised from the first cut of the lobe. Simultaneous to this mining, stripping of the western lobe of the pipe has com- menced in advance of the rainy season. Overburden and ground disturbed by dia- mond diggers is currently being stripped to access the uncontaminated kimberlite in preparation for bulk sampling. The processing plant is running at a steady state average capacity of approxi- mately 50 t/h over a double shift (16 hours). The kimberlite material remains predomi- nantly weathered; however, some harder blocks of kimberlite are being encoun- tered. Since these blocks are too hard to scrub but are also too soft to efficiently crush, they are being sent to an oversize stockpile where they are broken down with an excavator prior to being re-fed into the plant to ensure maximumdiamond lib- eration and integrity of results. 

BlueRock Diamonds commissions new plant AIM-quoted BlueRock Diamonds reports that the new plant at its Kareevlei project in Northern Cape Province is now fully operational and is in commercial produc- tion processing at a rate of approximately 80 tonnes of kimberlite per hour.

Report published at the time of our admis- sion to AIM.” Adds CEO Riaan Visser: “In December 2014, we halted processing of kimberlite through the existing plant to allow con- struction of the new plant to commence, which included the addition of rotary pans to the existing DMS plant and an enlarged and more efficient crushing circuit. We are confident that the new plant will enable us to profitably produce sufficient diamonds at a lower operating cost per tonne in 2015. “We are yet to explore the remainder of the Kareevlei property but based on the sampling data received from the previous owners, particularly for the K5 pipe, we believe that it still offers excellent medium to long term growth opportunities for the company.” 

“This is the culmination of almost 18 months of hard work during which we have completed our trial mining and con- structed our new processing plant,” says Non-executive Chairman Paul Beck in the company’s preliminary results for the year ended 31 December 2014 (released on 19 May 2015). “We were pleased with the results of the trial mining from which we recovered 575 carats. These were sold at an average price of US$248, some 36 % higher than anticipated in the Competent Person’s

6  MODERN MINING  June 2015