Modern Mining December 2017
Pre-Feasibility Study on Malingunde now underway
that it has been granted additional ground directly along strike of the Malingunde deposit. The new ground is to the south-east of the deposit, extend- ing the prospective strike length of the ‘Malingunde Trend’ by approximately 25 km. Previous exploration is known to have intersected saprolite-hosted graphite mineralisation in this newly granted area. Commenting on the award of the new licence, Sovereign’s Managing Director, Dr Julian Stephens, said that the company now controlled the entire Malingunde Graphite Trend, providing significant scale and optionality upside to the exist- ing resource that has been defined at Malingunde. “Sovereign’s in-country team will commence targeted exploration along strike from Malingunde over the upcom- ing wet season (December – March) using the very cheap and effective hand-auger exploration tool,” he said. Malingunde is located just 15 km south- west of Lilongwe, Malawi’s capital city. The discovery was made in 2015 by Sovereign’s in-country geological team using hand-auger drilling techniques in an area of no outcrop. In April 2017, Sovereign reported a maiden mineral resource esti- mate (MRE) of 65,1 Mt at 7,1 % TGC (Total Graphitic Content) at a 4 % TGC lower cut-off grade (saprolite, saprock and fresh rock). The MRE, prepared by CSA Global, includes a high-grade saprolite compo- nent of 8,0 Mt at 10,0 % TGC. The next phase of work at the Free State project will consist of an analysis of the indicator mineral chemistry for each of the pipes to determine an economic interest rating which will prioritise further work. This follows field observations of exten- sive historical workings which suggest that these kimberlites are diamondiferous. This is planned for early in 2018. “The re-discovery of eight kimberlites in a highly prospective diamond area was very positive,” comments John Teeling, Chairman of Botswana Diamonds.“We now know the sizes of each pipe/dyke and we believe that each could contain diamonds. The next step is to evaluate the diamond indicator minerals in each pipe to decide priorities for drilling.” Koffiefontein is also well known for the high-quality gems it produces.
A drill site at the Malingunde graphite project (photo: Sovereign Metals).
ASX-listed Sovereign Metals reports that the Pre-Feasibility Study (PFS) for the low cost Malingunde saprolite-hosted graphite project in Malawi has begun. The company says the PFS will build on the outstanding results delivered in the Scoping Study, which highlighted the potential for a very low capital and oper- ating cost operation with annual graphite concentrate production of approximately 44 000 tonnes over an initial mine life of 17 years. Sovereign reported the results of the Scoping Study in June 2017. A number of opportunities were identified in the study to further enhance the project economics. The company has completed a compre- hensive review of the Scoping Study to assess these opportunities and define
key work programmes for the PFS. Following completion of the review, the scope of work for the PFS has been finalised, with key activities including a 6 000 m infill and extensional aircore drilling programme; mine design, including optimisation of the mining schedule and mine-site layout; a substantial metallurgical programme, pro- cessing multiple samples to optimise the flotation regime, producing concentrates for evaluation by offtake partners and for further downstream test-work; and process design and engineeringworks based on the results of the metallurgy programme. Sovereign is targeting completion of the PFS in mid-2018, with certain work programmes designed to continue directly through into the DFS stage. The company has also announced gravity geophysical techniques, which has resulted in very strong images of the foot- prints of these kimberlites. The kimberlites occur along a north-west to south-east trending kimberlite feeder system along which the diamond mines of Jagersfontein, Koffiefontein and Kimberley are located. It is therefore inferred – says Botswana Diamonds – that the eight kim- berlites were formed at the same time as these mines. Recent whole rock geochem- istry shows similar compositions in the kimberlites to the surrounding mines. Jagersfontein is renowned for the blue gems it produced, and the Excelsior (972 carat) and Reitz/Jubilee (651 carat) dia- monds recovered from it are amongst the 10 largest diamonds ever discovered.
Sizes determined for re-discovered kimberlites Botswana Diamonds, listed on AIM, has announced results from its third ongo- ing exploration project in South Africa. The Free State project is situated between Bloemfontein and Kimberley, the historic centre of the diamond industry, where kim- berlite was first identified.
Following the company’s announce- ment in October 2017 regarding the re-discovery of eight Group 1 kimberlites, detailed ground geophysical survey work was undertaken by Geofocus. The survey work was aimed at determining the surface area of these kimberlites. Results indicate the sizes of these kimberlites to range from 0,3 to 1,15 hectares. The sizes were determined using a com- bination of magnetic, electromagnetic and
6 MODERN MINING December 2017
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