Tsodilo Resources Limited said it has resumed evaluation activities on the BK16 kimberlite project in Botswana following the traditional extended holiday break in southern Africa.
The BK16 kimberlite project is located within the Orapa Kimberlite Field (“OKF”) in Botswana. The diamond mines in the country have produced an average of 27 million carats annually in the last 10 years and Botswana is the world’s largest producer of diamonds by value. In 2016, the OKF area produced 8.85 million carats. Of the 83 known kimberlite bodies, eleven have been or are currently being mined.
These are AK01, AK02 and AK07 (Orapa, Debswana), AK06 (Karowe, Lucara Diamond Corporation), BK01, BK09, BK12 and BK15 (Damtshaa, Debswana), DK01 and DK02 (Letlhakane, Debswana) and BK11 (Firestone Diamonds). The Karowe mine has produced such notable diamonds as the 1,109 carat ‘Lesedi La Rona’ and the 813 carat ‘Constellation’.
The diamondiferous BK16 kimberlite pipe is approximately 6 hectares in size at surface, and is known to contain rare and valuable Type IIa diamonds (see press release dated May 31, 2016). The following phases of kimberlite were identified during the 2015 drilling program: Red volcaniclastic kimberlite VK1, Black VK2, Grey VK3 and VKxxx also referred to as the basalt breccia, country rock breccia (CB) and coherent kimberlite (CK1).
The POLUS-M sorter was installed at the company’s secure facility in Maun, Botswana during week 2 of 2018 and the first diamond was recovered during the setup, calibration and instruction period. Installation and training was performed by personnel from Bourevestnik, Inc.’s offices in Germiston, South Africa.
Historic tailing material which was first processed through the company’s DMS was used for the sample material. The diamond was recovered in the plus 1 and minus 3 mm fraction. “BK16 is known to be diamondiferous so diamond recovery is expected but the significance of this recovery from tailings and waste that have been sitting for almost 20 years clearly indicates what we have said before is that the rotary plant which was employed in the previous evaluation was inefficient in the recovery of diamonds and reported grades were most likely understated,” said Dr. Mike de Wit, President and COO.
The POLUS-M sorter is designed to treat dry diamond concentrate with grain size – 8 + 6, – 6 + 3 and – 3 + 1 mm in the field in order to carry out geological exploration of diamond deposits. The POLUS-M sorter will treat the -8mm fraction at the company’s facilities while the plus 8mm material is currently planned to be hand sorted at the Diamond Technology Park in Gaborone, Botswana although the company is exploring avenues to obtain the use of a larger BV machine to treat this fraction.
The sorter operation concept is based on the use of diamonds’ property of luminescence under X-ray impact and on the difference of those properties with diamonds and associate luminescent minerals. The mode under reference term “luminescence and absorption” when the X-ray tube and photo detectors are located on both sides of the material flow is implemented. The effect of difference in X-ray absorption by diamonds and associate luminescent minerals is used. Additional information on the POLUS-M sorter from Bourevestnik, Inc. can be obtained from the press release of December 11, 2017 available on the Company’s website.
The refurbishing of the Company’s DMS treatment plant is ongoing with adjustments being made to the DMS section with special attention been given to the cyclone and prep-screens. The tailings material continues to be utilised for this final calibration and once the plant is fully optimize the processing will switch over to the LDD samples.
“It is exciting to see everything coming together and although we still have a bit to go to fine tune the recovery process it is good to know that we are recovering diamond and now we just need to get everything going at 100% efficiency,” added Dr. Mike de Wit.