Modern Mining January 2020

MINERAL SANDS

bulldozers) and it is anticipated that relocation will occur every two to four weeks. Run of mine feed (ROM) enters the DMU through a grizzly (400 mm screen), passes up the DMU con- veyor which discharges to a slurry area where water is added, and then screened at 4 mm. The screen undersize is pumped to the WCP. Oversize is dis- posed of in the pit void. Coarse tailings (quartz sand) separated by the WCP is pumped, initially to an out of pit storage facil- ity and later to the mining pit void where a moveable tails stacker de-waters the slurry. Water is recovered and pumped back to the WCP. Sand is stacked to a height approximating the planned finished surface level and then formed into fine tails evaporation ponds by bulldozer. Flocculated clay tailings (fine tailings) from the thickener at the WCP are pumped to the evapora- tion ponds built on coarse tails. Initially, until enough in-pit coarse tails area is available, some ponds will be constructed on ore and the dried tails removed to allow subsequent mining. The tails ponds will be filled to a depth of approximately 1,5 m and when dry the clay will be about 0,4 m thick. Describing the landform reconstruction process, the DFS says the desiccated fine tails are worked by bulldozer into the coarse tails to make a nomi- nal 2 m thick water retention layer at the surface, graded into final landform. Stockpiled topsoil is then

Mining Equipment (HME), a Dozer Mining Unit (DMU), a 1 750 t/h wet concentrator plant (WCP) and a 150 t/h mineral separation plant (MSP). Also to be constructed in Stage 1 are various ancillary works such as a camp, a power generation facility, a haul/ access road and bridge, an export facility storage shed and a jetty, and a multi-buoy mooring (MBM) facility and ship loader. Stage 2 commences four years after initial pro- duction and includes the addition of a second DMU (identical to DMU1), a second 825 t/h WCP, additional HME and an upgrade of the power plant capacity by 30 %. The borefield will be expanded with the addi- tion of two boreholes and the camp will be enlarged with the addition of an 18-room dormitory. The selected mining method is conventional dozer trap with in-pit tailings deposition, enabling a short three to four-year cycle from initial land clearing to final land rehabilitation. Mining will involve three D11 bulldozers feeding a DMU to deliver 13 Mt/a to the WCP in Stage 1 before increasing to 19 Mt/a in Stage 2, with the addition of a second DMU and a single D11 bulldozer for the remaining mine life. It is envisaged that an existing Kwale DMU built by Piacentini & Son will be refurbished and shipped to Toliara for Stage 1. The same company will be commissioned to supervise the DMU installation at Toliara as well as supply the second DMU in year 4. Each DMU is designed to be relocatable (using D11

The proposed 150 t/h mineral separation plant (MSP).

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January 2020  MODERN MINING  31