The copper-cobalt minerals hosted in rocks of the Neoproterozoic Katangan Basin in the Central African copper belt metallogenic province of the DRC are a classic example of (low energy) sediment-hosted stratiform copper (SSC) ore system deposits. These deposits are economically significant, as they account for approximately 25% of the world’s copper production and known Mineral Reserves being second only to porphyry copper deposits in terms of copper production and the most important global cobalt resource.

The copper-cobalt deposits contained in a sedimentary series of rocks are known as the Mines Group in the Katanga sequence and the Roan Group in Zambia. The sediments are shallow-water shales, dolomitic shales, reefal dolomites and possible evaporitic lagoonal mudstones, formed on a platform marginal to a subsiding basin. The rocks are exposed in a series of tightly folded and thrusted anticlines and synclines, which generally trend east-west or southeast and are often overturned to the north. In spite of this deformation overprint, the mineralized zones, although sometimes lenticular along strike and down dip, as well as showing local diapiric forms, display remarkable large-scale continuity within the Mines Group.

KTO UG operations extract mineralized copper ore from the Kamoto deposit, which is differentiated from KTE, predominantly mined in the KOV OP, but contains the same lithologies. The KTO UG is subdivided into five fragments as follows:

The deposit is currently divided into three categories of dip/plunge, and the three mining methods applied throughout the zones are:
- RAP with Hydraulic or Cement Hydraulic Backfill at dips of less than 12º;
- TLHR with Backfill between 13º and 55º; and
- LLHR with Backfill at dips greater than 55º.

Room and Pillar
The RAP mining practised at KTO UG is applied to the OBS and OBI horizons. Access drives are developed along strike on the hanging wall contact, 6 m wide by 5 m high on 25 m centres. Cross drives (6 m x 5 m) are developed, 25 m centre to centre, along the centre of the stope for the full length thereof; connected by drifts, 25 m centre to centre, for ease of loading the broken ore and for ventilation purposes. A strike gathering drive is developed at the bottom of the stope for cleaning of ore. The cross drives are then slyped to a full width of 12.5 m and height of 5 m. Benching of drives takes place by drilling long down-holes and slots from the slyped cut to the footwall of the stope, and then blasting from the gathering drive end. Benching operations take place under a hanging wall that is supported in the development and slyping stages of mining.

The 12.5 m stopes with 12.5 m pillars are mined as primary stopes and backfilled with cemented hydraulic fill to provide support for the pillars. If fill is not used, much larger pillars would be required for a stable layout. As an indication, for a mining height of 15 m wit ........

The mixed ore milling consist of CM1 and BM1 (or CM2 and BM2), CM5, CM6 and BM6, CM7 and BM7 milling circuits.

The CM1/BM1 (or CM2/BM2) mills are operated in a closed circuit with a common cyclone clusters. CM5, CM6/BM6 and CM7/BM7 also have the same arrangement. All circuits will produce a grind of 80% -150 µm from a feed with an F80 of 150 mm. BM1/BM2, CM5, BM6 and BM7 operate with a ball load of up to 35%.

The feed to each mill circuit is measured and recorded using a weightometer installed on each AG or SAG mill feed conveyor. Process water, together with the crushed ore, is added to each AG or SAG mill to achieve a slurry solids content of 75% by mass within the mill. Scats conveyors are installed at the discharge of CM5, CM6 and CM7 to remove material from the milling area to a dedicated stockpile outside the building.

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