Modern Mining March 2018

MINING News

Namdini indicated resource upgraded to 6,5 Moz

on the primary crushed product or the sec- ondary crushed product depending on the technology selected) that will provide higher grade ore to the heaps. The primary crusher reduces the rock to 127 mm (gyratory crusher), the secondary crusher to 32 mm (cone crusher) and the tertiary crusher to 5 mm (HPGR). The process is designed for a 90 % availability, processing over 23 000 tonnes of ore per day (at the 8,5 Mt/a sce- nario) at a strip ratio of waste to ore of 2 to 1. “By going with heap leach treatment and sorting technologies, we have been able to provide low capital cost and operat- ing costs and, equally as important, reduce the environmental footprint of the project,” said Pierre Léveillé, President and CEO of Deep-South. “The PEA proposes a robust economic return that we expect to enhance during the PFS stage.” Deep-South is a mineral exploration company largely held by Namibian share- holders and Teck Resources Ltd, which holds about 35 % of Deep-South share capital.  Koimtsidis says the higher-grade areas of the deposit, close to surface, will be tar- geted within the Stage 1 pit in the early years of production, as the recent results of the PEA study indicate that this pit will be the area most likely to repay capital investment soonest. The Stage 1 pit will see approximately 400 000 oz to 900 000 oz produced over three to four years at an average head grade of approximately 1,3 to 1,5 g/t Au based upon the PEA results and the throughput size selected.  mineralisation intersected down to 650 vertical metres, and still open. “ This upgrade to the mineral resource is more than a 50 % increase in the indicated category from the esti- mate published in the September 2017 NI 43-101 technical report and supports a long mine life as demonstrated by the results of the recently announced Preliminary Economic Assessment. “With the majority of indicated mineral resource continuous from sur- face to an approximate vertical depth of 400 m, we anticipate a conversion of mineral resources to ore reserves within a simple, single, large-scale open pit, with a very low strip ratio of 1,2 to 1 over the life of mine, as the preferred mining method.”

Typical long section through the Namdini resource model showing gold grade distribution.

Cardinal Resources, listed on the ASX and TSX, has completed an update to the Mineral Resource Estimate (MRE) for its Namdini gold project in north-east Ghana. As a result of an additional 15 684 m of HQ diamond drilling within 35 holes since the last MRE in September 2017, the infill drilling programme has been successful in delivering a substantial conversion of the inferred category ounces into the indi- cated mineral resource category which is now at 6,5 Moz of indicated mineral

resources and 0,5 Moz of inferred mineral resources. “We are extremely pleased that our intensive infill drilling campaign has sig- nificantly upgraded our confidence in the Namdini deposit with an overall lift in indicated mineral resources from 4,3 Moz to 6,5 Moz,” comments Cardinal’s CEO and MD, Archie Koimtsidis. “Further to this, we are confident that Namdini can continue to grow with more drilling given it remains open both along strike and down dip, with

PEA examines heap leaching options for Haib Deep-South Resources Inc, a company listed on the TSX-V, has received the results of a Preliminary Economic Assessment (PEA) from Mineral Engineering and Technical Services of Australia (METS) on its Haib copper project in southern Namibia. The project has an indicated resource of 456,9 Mt at 0,31 % Cu.

on the Haib project suggests that a conven- tional crush-grind-float is not economically feasible due to the low grade and hardness of the ore – requiring a significant amount of energy for grinding. The four recovery options considered for economic evaluation in the PEA were: Option 1 – ore sorter upgrading, dense media upgrading, flotation and heap leaching of the tails; Option 2 – two-stage dense media upgrading, flotation and heap leaching of the tails; Option 3 – ore sorter upgrading and heap leaching of the upgraded material; and Option 4 – whole ore heap leaching. The best economic outcome is derived by using Option 3. Despite this option having a relatively low copper recovery (73,2 %) compared to the other options, it has the lowest capex (US$191,8 million) at an initial throughput of 8,5 Mt/a. The system design proposed uses three crushers and an ore sorting system (either

The PEA focuses on the potential of heap leaching treatment. Several opportu- nities are identified in the PEA that could significantly enhance the economic return outlined in the report, including more assays of the molybdenum to be included in future resources estimation, sorting technologies enhancing the recovery pro- cessing performance and reduced power costs. The PEA recommends these oppor- tunities be pursued and that Deep-South proceed with a Pre-Feasibility Study (PFS). Heap leaching is considered to be the best route for the recovery of copper from the Haib deposit. Previous work conducted

16  MODERN MINING  March 2018