Regional Geology
The Kibali gold deposits are hosted within the Moto Greenstone Belt, a Kibalian Neoarchean terrane that lies in the NE Congo Craton. The northeastern part of the Congo craton is formed of Archean rocks, which extend eastward from the northern part of the DRC across the Cenozoic East African rift into Uganda, southern Kenya, and northern Tanzania (Allibone et al, 2020). Plutonic rocks underlie 80 to 90% of the area, volcano-sedimentary rocks are largely metamorphosed under greenschist facies conditions and form isolated belts for the remaining 10% to 20% of the craton.

The Moto Greenstone Belt is elongated, WNW-ESE trending, and is comprised primarily of two distinct litho-stratigraphically blocks. To the north, the belt is bounded by the West Nile Gneiss complex, a Meso- or Paleoarchean granite gneiss that extends northward into the Sahara Desert (U-Pb ages > 2670 Ma; Turnbull et al., 2017). To the south, the belt is bounded by the Upper Zaire Granitic Massif, an Archean granite-gneiss terrane that dominates the NE Congo Craton. The Massif is locally represented by the Watsa Igneous Complex.

Project Geology
The mineralised KZ Trend, which hosts the Kibali deposits, is located in the central part of the Moto Greenstone Belt. The Project hosts most of the gold endowment in the Moto Greenstone Belt. The KZ Trend marks an important boundary between older and younger parts of the belt with different provenances (Allibone et al., 2020). The Project includes a wide complex of variably deformed and metamorphosed basalts, dacitic volcanic and volcaniclastic rocks, siliciclastic sedimentary rocks, BIF, and chert.

Mineralisation
At Kibali, the gold deposits are largely hosted in siliciclastic rocks, BIF, and chert that were metamorphosed under greenschist facies conditions. Ore-forming H2O-CO2-rich fluids migrated along a linked network of gently NE dipping shears and NE to NNE-plunging fold axes of the KZ Trend. On-going deformation during hydrothermal activity resulted in development of lodes in a variety of related structural settings within the KZ Trend. The source(s) of metal and fluids which formed the deposits remain unknown, but metamorphic devolatilisation reactions within the supracrustal rocks of the Moto Greenstone Belt and/or deeper fluid and metal sources may have contributed.

Mineralised rocks at Kibali typically lack significant infill quartz-rich veins, unlike many other orogenic gold deposits. Gold is instead associated with pyrite in zones of alteration that replaced the earlier mineralogy of the host rocks.

Most of the mineralisation currently delineated at the Project occurs along the KZ Trend. The KCD deposit and satellite deposits (Kombokolo and Gorumbwa) are located in the central part of the KZ Trend. Most deposits are located along the north branch of the KZ Trend (Aerodrome to Ikamva), with other targets along the south branch of the KZ Trend (KZ South).

Deposit Types
Gold deposits of the Kibali district are part of the globally significant group of Neoarchean orogenic gold deposits, examples of which are found in most Neoarchean cratons around the world. However, the gold deposits of the Kibali district are hosted within the sulphide vein and disseminated in the altered country rocks instead of in mineralised quartz veins, found generally in most Neoarchean cratons around the world (Allibone et al., 2020). Vein hosted gold is identified in the Project area, but to date only represents small scale mineral occurrences.

Gold mineralisation within the Neo-Archean Moto Greenstone Belt is associated with epigenetic mesothermal style mineralisation, consistent with the majority of Archaean and Proterozoic greenstone terranes worldwide. The type of deposit has been termed orogenic gold and is generally associated with regionally metamorphosed terranes that have experienced a long history of thermal and deformational events and intrusion by igneous complexes. As such, the gold deposits are invariably structurally controlled. The most common style of mineralisation in this setting is fracture, vein-type and disseminated gold bearing sulphide mineralisation in zones of brittle fracture to ductile folding and dislocation.

The Kibali deposits differ from many orogenic gold deposits in terms of structural setting. Rather than being linked to a major large scale steeply dipping strike slip fault with brittle-ductile deformational evolution, many of the deposits are hosted within a thrust stack sequence with ductile to brittle-ductile deformational structures and complex folding history. Some Kibali deposits, like Kalimva and Oere, are more typical orogenic gold deposits, with planar mineralised lodes associated with mineralised brittle ductile fault systems, and with high-grade shoots associated with geological intersections and/or flexures of the host fault zone.

The Mine comprises both open pit and underground mining operations.

Open-pit
From 2022 onwards, open pit production will come from the Sessenge, Aerodrome, Pamao, Gorumbwa, Megi-Marakeke-Sayi, Kalimva-Ikamva, Oere, Pakaka, and the KCD deposits. The Mengu Hill, Mofu, Kombokolo and Rhino pits were depleted in 2017.

Open pit mining is carried out using conventional drill, blast, load, and haul surface mining methods. Mining of the main pits is carried out by a mining contractor, KMS.

From 2022 onwards, open pit production will come from the Sessenge, Aerodrome, Pamao, Gorumbwa, Megi-Marakeke-Sayi, Kalimva-Ikamva, Oere, Pakaka, and the KCD deposits. The Mengu Hill, Mofu, Kombokolo and Rhino pits were depleted in 2017.

The upper levels of the open pits are usually in weathered material, which typically is free digging material. Once fresh (unweathered) rock is encountered, drilling and blasting is required. Emulsion explosives are supplied as a down-the-hole service by the Mine’s explosive contractor Orica. Free digging in the upper levels uses 5 m high benches, with 10 m benches used for drilling and blasting operations. The 10 m benches containing ore are excavated in three flitches of equal height.

Pits Design has following Parameters:

- For Weathered material:
- Bench - Height 5-10m;
- Berm Width 4-5m;
- Batter Angle 27-50°;
- IRA 27-50°.

- For Transition Rocks:
- Bench Height 10m;
- Berm Width 4-6m;
- Batter Angle 27-65°;
- IRA 38-55°.

- Fresh Rock:
- Bench Height 10-20m;
- Berm Width 4-6m;
- Batter Angle 50-80°;
- IRA 48-59°.

Waste Dumps
An estimated 300 Mt of waste will be mined over the remaining LOM based on Mineral Reserves. No in-pit dumping was carried out in 2021 and none is planned for 2022, as the Kombokolo, Mengu Hill, KCD, and Sessenge mines continue to explore potential underground opportunities. Future work will, however, consider the use of some of the satellite pits with low potential for future underground operations for waste disposal, based on the mining sequence. Within the current LOM, Pamao has been planned to be backfilled with tailings upon exhaustion of the mineral reserve.

External waste dumps includes: KCD/Sessenge, Gorumbwa, Pamao, Kalimva-Ikamva, Megi Marakeke Sayi, Pakaka/Aerodrome that have total disign capacity 271.71 Mm3.

Underground Mining
The Kibali underground mine is a long hole stoping operation producing at a rate of 3.8 million ore tonnes per year. Mine has haulage shaft (740 m deep). The decline to surface will be used to haul some of the shallower zones and to supplement shaft haulage.

To date, 43,609 m of capital and access development has been completed. The current LOM plan contains a further 9,928 m of capital lateral development based on Mineral Reserves. The key capital infrastructure remaining to be developed are the 9101 decline, 9101 incline, southern exhaust raises and the 3101 / 3102 access development.

Existing infrastructure comprises:
• A vertical shaft;
• Mobile equipment mining fleet;
• Backfill plant;
• Batch plant;
• Underground dewatering facility;
• Surface compressor house;
• Multiple surface workshop facilities;
• Electrical power line connection to the grid;
• Office building;
• Warehouse;
• Water clarifying plant.

Ore from stopes is loaded (both by teleremote and conventional manual loaders) from the stopes into the eight ore passes via finger raises on the respective levels. This ore is then transferred by Autonomous LHDs into two coarse ore bins and then into two primary crushers, followed by two fine ore bins and independent skip loadout conveyors near the shaft bottom. The proposed mining methods are variants of long hole open stoping with cemented paste:
• Primary / Secondary long hole open stoping (primary 20% of Mineral Reserve tonnes, secondary 33% of Mineral Reserve tonnes) is used in the wider zones, with 35 m interval heights where stopes are mined either as single lift or multiple (up to four) lifts, depending on stope geometry and the geotechnical stable span.
• Advancing face long hole open stoping (29% of Mineral Reserve tonnes) is used where the mineralisation has a shallower plunge (approximately 20° to the NE), where stopes are mined with variable interval heights between 25 m and 35 m to optimise extraction.
• Longitudinal open stoping (18% of Mineral Reserve tonnes) is used in narrow zones (< 15 m width) with variable interlevel heights between 20 m and 30 m.

The mine is accessed via a twin decline, a vertical shaft, and a system of internal ramps. Ore from stopes is loaded (both by teleremote and conventional manual loaders) from the stopes into the eight ore passes via finger raises on the respective levels. This ore is then transferred by Autonomous LHDs into two coarse ore bins and then into two primary crushers, followed by two fine ore bins and independent skip loadout conveyors near the shaft bottom.

Sulphide Crushing and Screening
Two primary jaw crushers (two Sandvik CJ815:200 kW, CSS:16 0 mm) are used targeting 1,300 tph and feeding two secondary crushers (two Sandvik CS660; 250 kW, CSS:45 mm) via a coarse ore stockpile (COS).

ROM sulphide ore, received from trucks, is treated in a primary crushing circuit comprising of a ROM bin, apron feeder, and primary jaw crusher (Sandvik CJ815) operated in open circuit at 1,300 tph target. This primary crushed product is then conveyed to a primary crushed stockpile or COS with a 5,000 t live capacity. The sulphide ore from underground has already been crushed underground and is also conveyed to this stockpile.

Apron feeders under the stockpile are used to combine the sulphide ores from the two sources, before it is conveyed to the secondary crushing circuit that has two secondary cone crushers (Sandvik CS660) operating in parallel (running/standby) in open circuit to produce a crushed product stream with a P80 of 45 mm. The secondary circuit was commissioned in May 2014.

When sulphide ore is being treated, secondary crusher product is fed onto a fine ore stockpile (FOS) via a conveyor system. The FOS serves as a common mill stockpile to both the mills and has a live capacity of 11,700 t of sulphide ore to each mill. The mill is fed from the mill feed stockpile using apron feeders that feed directly onto the mill feed conveyor.

When oxide ore is being treated through its circuit, the primary crusher product (Sandvik CJ815) is fed directly to the mill feed conveyor and not via the secondary crushing circuit but may be subject to an in-line hybrid crushing stage, if deemed necessary, at least on one of the two parallel streams.

The design of the crushing circuit includes provision for the installation of a tertiary crushing circuit.

Oxide Crushing and Screening
ROM ore received from trucks is treated in a primary crushing circuit comprising of a ROM bin, an apron feeder, and a single toggle jaw crusher. This primary crushed product (at 450 tph) can either be diverted to the primary mill feed conveyor when oxide ore is treated, or alternatively conveyed to a common 5,000 t live primary crushed stockpile when sulphide ore is treated.

Sulphide Milling and Oxide Milling
A ball milling circuit comprising two Polysius ball mills, each operating independently in parallel, treats ore at a total feed rate of 900 tph dry solids. When treating oxide ore, the primary crusher product will feed directly onto the mill feed conveyor and into the milling circuit. When sulphide ore is treated, the mill will be fed from the mill feed stockpile.

Each ball mill is operated in closed circuit with a cyclone cluster used to produce a target grind of 80% passing 75 µm on sulphide and 80 µm on oxide. The mill feed consists of fresh crushed ore, a portion of the cyclone underflow, gravity concentrator scalping screen oversize and flash flotation cell high density tailings. Ground ore from the mill reports to the mill discharge sump where it combines with gravity concentrator tailings, flash flotation low density tailings and Gekko Inline Leach Reactor (ILR) tailings, before being pumped to the cyclone cluster.

Ultra-Fine Grinding
Flotation concentrates, together with gold-room waste, report to the concentrate thickener. Thickener underflow is fed to the ultra-fine milling circuit. The UFG consists of eight VXP2500 FL Smidth (originally Deswik) ceramic bead mills in parallel, where circuit feed material of 80% passing 40 µm is treated to achieve a target grind of 80% passing 23 µm. The ultra-fine milling products are pumped to the pre-oxidation and pre-leach circuit followed by the Pumpcell circuit.

The Kibali gold processing plant comprises two largely independent processing circuits, the first one designed for oxide, transition and free milling ore sources and the second for sulphide refractory ore. However, both circuits are designed to be switched to process sulphide ore when the oxide, transition and free milling ore sources have been depleted.

The processing plant rated throughput is 3.6 Mtpa of soft oxide rock ore through the oxide circuit and 3.6 Mtpa of primary sulphide rock ore through a parallel sulphide circuit. Once the plant is sulphide only, the capacity is 7.2 Mtpa of sulphide ore. Kibali’s operational performance has demonstrated that the process plant is fully capable of its design capacity, and further modifications to the mills with an increased motor size coupled with a decreased inlet trunnion size has allowed for an even greater power draw and hence higher throughputs.

Once the oxide, transition and free-milling ore sources have been ........