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.

With the exception of Tilwezembe OP, all of the mineralized properties of KCC are localized within the Kolwezi Nappe, a northeast striking synclinal basin with major and minor axes of approximately 20 km and 10 km respectively. Tilwezembe OP is located about 20 km to the east of Kolwezi.

Within the Kolwezi Nappe, each of the project areas, T17 Mine, Kananga OP, KTO UG, KOV OP and Mashamba East OP contain fragments with intact successions of Series Des Mines lithologies, which host the copper and cobalt mineralization. The fragments are often structurally complex, being tightly folded and exhibiting variable strikes and dips both within individual rafts and between neighbouring rafts.

T17 Mine
The T17 West is described as dismembered structurally complex packages, which belong to the southern flank of a synclinal fold that extends 2.6 km and is overturned towards the north. Faulting is assumed to be the predominant process in the deformation and dismemberment of the deposit.

Tilwezembe OP
The mineralized zone of Tilwezembe is located in a northeast-southwest anticlinal structural lineament, which extends further to the east where known copper and cobalt deposits exist (Kisanfu, Myunga, Kalumbwe and Deziwa). Strongly brecciated siliceous dolomites and shales of the Mwashya Formation (or R4) dominate with interstitial bands of haematite and oolites. The strata strike almost east-west and dips at about 45° to the south.

Kananga OP
The Kananga orebody outcrops and forms a ridge with a north-northeast strike. The ridge falls quite rapidly towards the south and has been cut to form part of the embankment for the Lobito railway line, which runs parallel to the ridge and 10 m to 20 m away from it for most of the strike length of the orebody. GCM interpretations indicate that Kananga is the northern limb of the Kananga Dilala syncline, which plunges to the south.

KOV OP
The KOV OP deposit can be sub-divided into five main fragments within the KCC concession. These fragments can be classified as rafts of the Lower Roan lithologies which are separated by faults and/or RAT Lilas waste intrusions. The KOV fragments as follows:
KTE: Can be divided into three sub-fragments; KTEA forms a broad syncline dipping at approximately 40° north, KTEB lies below KTEA and dips approximately 30° north, whilst KTEC lies to the east of the KTEB and is sub-vertical.
Oliveira: A broad open syncline with the northern limb dipping 5° to the southwest and the southern limb dipping 25° to the northwest.
Virgule: A rectangular fragment which is faulted in the west, appearing as a ‘trouser leg” shape. It is dipping 20° to the southwest.
Variante: Forms a rough L-shape plane, with the eastern portion steeply dipping 70° to the north, shallow dipping 20° to the west.
FNSR: An over turned fragment, rectangular fragment which is dipping 25° to the southwest.

Mashamba East Mine
The Mashamba East has an intact succession of Series de Mines lithologies, which host the copper and cobalt mineralization. Structurally, the lithologies of the Mashamba East strike to the northeast and dip 20° to the northwest in the west and wraps around to strike almost north-south and dip 35° to the east in the eastern portion of the property.

KTO UG
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:
Principal: forms a rough L-shape syncline, flat lying to gently dipping (up to 8° to the north) in the central and northern areas and becoming steeper (15° to 25°) towards the east and west flanks. The steeply dipping area to the south is sub-vertical in places and is separated from the flatter dipping area by structurally complex zones and RAT Lilas waste intrusions.
Etang South: forms a broad open synform dipping 25° to 35° to the east on an approximate north northwest strike;

Etang North: forms a roughly rectangular slab dipping 35° to 55° to the east on an approximate northnortheast strike. It extends below the Principal fragment in the north;

Ecaille Renversee: a small reversed fragment between Principal and Etang North; and

Pringle: forms a moderately open synform dipping 35° to 55° to the southeast on an approximate north strike.

Primary mineralization, in the form of sulphides, within the Lower Roan is associated with the DSTRAT and RSF for the OBI and the SDB and SDS for the OBS and is thought to be syn-sedimentary in origin. Typical primary copper sulphide minerals are bornite, chalcopyrite, chalcocite and occasional native copper while cobalt is in the form of carrolite. The mineralization occurs as disseminations or in association with hydrothermal carbonate alteration and silicification. Supergene mineralization is generally associated with the levels of oxidation in the subsurface sometimes deeper than 100 m below surface. The most common secondary supergene minerals for copper and cobalt are malachite and heterogenite.

The RSC, a lithological unit stratigraphically intermediate between the OBS and OBI host rocks , contains relatively less copper mineralization. The RSC contains appreciable copper mineralization near the contacts with the overlying SDB formation and the underlying RSF formations. The middle portion of the RSC, considered to be “sterile” by GCM, normally contains relatively less copper mineralization and was historically not sampled. KCC currently samples the entire RSC. The mineral potential of the RSC is less well known than that of other formations.

The RSC has been observed to be well mineralized in supergene cobalt hydroxide, heterogenite, which occurs as vug infillings, especially near the surface.

The active operations at KCC can be classified into surface and underground mining operations. Surface operations include KOV OP, KITD Tailings and Mashamba East OP; the T17 OP has been depleted. The underground operations include KTO UG and T17 UG, which have been developed to various stages.

The three mining methods practised at KTO are:
- Room and Pillar with Hydraulic Backfill (RAP) at dips of less than 12º;
- Transversal Longhole Retreat with Backfill (TLHR) between 13º and 55º; and
- Longitudinal Longhole Retreat with Backfill (LLHR) at dips of greater than 55º.

KOV OP is an existing, large-scale operation. Mining related modifying factors applied to the KOV OP mine plan include a cut-off grade of 0.65% TCu and mining dilution of 20% and 5% overall losses. Ore production is primarily oxide and mixed material with only 8% sulphide ore.

Mashamba East OP is an existing, large-scale operation. Mining related modifying factors applied to the Mashamba East OP plan include a cut-off grade of 0.65% TCu, mining dilution of 7.9% and 5% overall losses.

The KITD Tailings area consists of a tailings dam which formed as a result of the discharge of fine tailings from KTC between 2008 and 2013. The KITD Tailings was constructed by a conventional upstream discharge method and is a U-shaped tailings dam, constrained to the west, east and south flank by civil engineered (SRK Consulting, 2008) containment walls, and the northern flank formed by steep natural rising ground.

The hydraulic mining system simplifies the remaining operation in three ways. First, the hydraulic system eliminates the need for excavating and hauling equipment normally associated with the conventional mining. Second, the energy produced by the water jets serves to break down clay aggregates allowing more efficient separation, and finally, the hydraulic action provides the appropriate slurry necessary for the subsequent hydrometallurgical beneficiation. KCC is currently operating three barges with two guns each (water cannons). Water is sprayed at 3.58 m3/minute at a pressure between 16 and 25 bar at the tailings pile in order to cut the upstream face.

The modifying factors that were used for the T17 UG design in the mining model for conversion to Mineral Reserves include:
- The stopes are designed at a cut-off of 1.2% TCu;
- Cut-off grade is calculated using an assumed long term price of $6,500 per tonne of copper and long term price of $60,000 per tonne of cobalt;
- An 8% combined geological loss and mining loss was applied to all longitudinal and transverse stopes;
- An allowance was made for 7.8% dilution on all longitudinal and transverse stopes at 0.5%TCu;
- The longitudinal stoping design consists of 48 m stopes with an 8 m wide pillar (12% rib pillar loss); and
- The transverse stoping design consists of 20 m stopes with an 8 m wide pillar (35% rib pillar loss).

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

KCC is currently operating the WOL hydrometallurgical processing at their existing Luilu operation. The KCC WOL project is designed to process the mixed ore flotation tails from the KTC plant, as well as the roasted sulphide concentrate, to produce 300 ktpa of copper metal and 30 ktpa of cobalt contained in cobalt hydroxide. Further expansion is planned to achieve cobalt production capacity of 40 ktpa.

Flotation
The flotation circuit consists of two distinct parallel flotation circuits followed by a common cleaner circuit. From the surge tank slurry is distributed to the two flotation circuits via a dedicated pumping system.

The concentrate from the rougher cells 1 will gravitate to Tank TK 035, and then be pumped to Tank TK 059. The concentrate from the respective scavenger cells will gravitate to Tank TK 036, and also be pumped to Tank TK 059. The concentrate from Tank TK 059 will be pumped to the cleaner flotation cells. The tails from the rougher cells wi ........