Modern Mining November 2018

GRAPHITE

There is significant opportunity to increase the mine life beyond 16 years by processing lower grade material from the large resource base, or by discovering additional high-grade resources within reasonable trucking distance to the proposed processing plant. The design of the processing plant – by Minnovo (owned by DRA) – is based on test- work by SGS Canada and best practice in similar operations. The plant feed will be delivered from the run-of-mine stockpile (ROM) by front-end loader to the grizzly and ROM bin. Material is passed through a mineral sizer for primary size reduction and then processed through a scrubber charged with steel media. Scrubber discharge slurry is passed through a 10 mm screen with a small quantity (0-15 %) of over- size being directed to a small pebble crusher. Scrubber undersize at 100 % passing 2 mm is pumped to the rougher flotation section for processing. Rougher tailings are pumped to the tailings thickener while rougher concentrate undergoes a polishing regrind. The concentrate undergoes cleaner flota- tion stages with cleaner concentrate split into coarse and fine fractions at 180 µm. There are three stages of recleaner flotation attritioning of the coarse and fine fractions, followed by three stages of cleaner flotation (separately). The final concentrate fractions (+180 µm (+80 mesh) and -180 µm (-80 mesh) streams) will be combined, thickened, and fed to a filter. The concentrate is dewatered using a plate and frame filter and air blow and membrane squeeze steps. The filtered concentrate will be dried using a flash dryer. Dried product will be screened to produce up to four fractions and bagged for despatch and sale. The Tailings Storage Facility (TSF) was designed by SLR Consulting to safely con- tain the life of mine estimated tailings of approximately 8,6 Mt. Test work has indi- cated a final settled density of 1,1 t/m 3 which is the figure adopted for the study. The maximum plume extent from the downstream toe of the TSF is predicted to reach 1 053 m at the end of year 100. Geochemical test-work indicates that the TSF pool and seepage water is of relatively good quality with low acid potential and low neutralising potential. In terms of water balance, it is expected the project will require an additional approximately 20 000 m 3 per month dur- ing each nine-month dry season for the first two years of operation. On the subject of access to infrastructure,

mine strip ratio is 1:1 waste to ore including the capitalised pre-strip. Pit geotechnical studies were undertaken by Peter O’Bryan and Associates. A recommended maximum overall pit slope of 58 degrees was adopted for pit design purposes. Mining will be undertaken via conventional truck and shovel methods. An initial contract mining strategy was selected for the first seven years, transitioning to an owner-operator model after this.

Soft, friable saprolite material from a diamond drill core sample at Malingunde.

Simplified process flowsheet for the Malingunde project.

30  MODERN MINING  November 2018