Modern Mining April 2020

Stage One – processing plant and infrastructure at a nominal design basis rate of 0,4-0,5 Mt/pa to produce a nominal 60 kt/pa graphite concentrate in the first four years of production. Stage Two – a second 0,5 Mt/y plant and associ- ated additional infrastructure doubling throughput to 1 Mt/y from Year 5 of operation. Meanwhile, a mine optimisation study was under- taken based on an appropriate balance of grade and strip ratio, rather than defining the largest economic pit. The result was an approximately four-year starter pit(s) that used a 10% TGC cut-off to ensure the high- est possible grade of ore feed in the early years followed by a larger LOM pit utilising a reduced (6% TGC) cut-off grade for the remainder of the schedule to minimise waste and keep the stripping ratio as low as possible. The mining operation will be undertaken by a local mining contractor. Processing The processing plant is designed to recover graph- ite concentrate by froth flotation. The design for the processing plant is based on a metallurgical flow- sheet with unit operations that are conventional and well proven in the industry and aligned with current graphite industry practice. The run of mine (ROM) ore will be two-stage crushed, followed by grinding in a rod mill, with graphite recovered by flotation. The process includes multi-stage re-grind milling and cleaner flo- tation to improve liberation and product purity. The flotation concentrate is then dewatered by

filtration and drying. The product is screened and bagged as final product in five different sized frac- tions and bagged for transport to port. The tailings will be thickened and pumped to the tailings storage facility (TSF). The second stage expansion in year 5 is expected to comprise a duplicate parallel production plant. Power for the project will be supplied from diesel generators under a BOOM (build, own, operate and maintain) contract. Additional power for the second stage expansion plant is expected to be supplied from then upgraded local grid network. Graphite concentrate produced will be road hauled to the Port of Dar es Salaam for shipment to market. The LOM operation costs are estimated at US$385/t of concentrate (FOB).

Above: Compelling economics, combined with low technical risks and 100% ownership, make Mahenge an incredibly attractive investment. Left: Armadale’s wholly-owned Mahenge Liandu graphite project is located in a highly prospective region.

Description

Stage 1

Stage 2

Capital Cost (US$ ‘000)

Capital Cost (US$ ‘000)

Process Plant Infrastructure

16,290 8,660

15,989 6,085

Indirect costs EPCM and other construction costs 6,487

4,693

Owners’ costs Contingency GRAND TOTAL

3,035 4,109

820

3,277

38,580

30,864

Capital cost estimated for Stage 1 and 2.

April 2020  MODERN MINING  23