Kansanshi mineralisation is hosted by deformed metasediments of the Nguba (formerly Lower Kundulungu) Group within the Katanga Supergroup of the Zambian Copperbelt. The individual mineralised rock units of the stratigraphic sequence comprise dolomites, dolomitic marbles, and various schists and phyllites. Mineralisation is structurally modified across the Kansanshi deposits. The deposits are currently mined from Main and North West Pits.

Kansanshi copper mineralisation is believed to have originated as hydrothermally remobilised copper that has been lithologically and structurally controlled.

Copper mineralisation at Kansanshi occurs as three deposits (Main, North West and South East). The deposits are located within domal structures along the crest of a regional antiform. Deposit mineralisation is closely associated with these domes.

Three styles of primary sulphide mineralisation are associated with these deposits:
• disseminated stratabound mineralisation;
• sub-vertically dipping, quartz-carbonate-sulphide veins crosscutting the stratigraphy;
• localised breccia mineralisation.

Weathering influences mineralisation as follows:
• near surface weathering in the saprolitic zone;
• around vertical veins, with oxide copper mineralisation predominantly evident as malachite, tenorite and chrysocolla;
• mixed primary and secondary sulphide copper mineral assemblages in transitional zones between weathering zones;
• pervasive shallow to deep weathering located along geological structures.

Primary sulphide copper mineralisation is mostly chalcopyrite, with minor bornite. Oxide mineralisation is mostly chrysocolla with malachite. The transition zone contains mixed oxide, primary sulphide, secondary chalcocite and minor native copper and tenorite. Minor copper is hosted in clay and mica minerals, and is classified as refractory. Gold is associated with copper mineralisation.

Open pit mining at Kansanshi is based on conventional drill and blast, shovel and truck mining techniques. Mining has proceeded from initial excavations in two pits (Main and North West) through a sequence of cutbacks, which in the longer term will result in these pits merging. The South East Dome Pit will contribute to the longer term production profile, but is unlikely to merge with the Main Pit. The cutbacks generally comprise wide benches of 200 m to 300 m width, providing several mining horizons from which to satisfy the feed requirements for multiple processing routes.

In general, ore is currently hauled to a ROM (run of mine) pad located immediately south of the North West Pit, and to a number of ore stockpiles, whereas waste is hauled to various dump locations.

To accommodate the increased processing requirements for the S3 expansion, the existing mining fleet will be expanded. Cutbacks for the Main and North West Pits have been designed to accommodate trolley-assist haulage routes, in addition to proposed semi-mobile, in-pit crusher locations and associated conveyor routes.

Mining method and operations
Mining follows conventional drill and blast, shovel and truck mining practice. The sequence of mining activities is also conventional and is typically as follows:
• RC grade control drilling delineates the ore zones;
• a grade control model is developed from which blast limits and digging blocks are designed;
• ore and waste blocks are blasted to design, according to layouts based on varying hole patterns and powder factors to suit prevailing ground conditions and ore types;
• electric and diesel/hydraulic shovels and excavators load the blasted rock into a fleet of 180 tonne to 95 tonne capacity haul trucks;
• ore is currently hauled direct to a surface ROM (run of mine) pad or to stockpiles, whilst waste is hauled to surface dump tip heads;
• trolley assisted haulage is currently in use for truck hauls, and is proposed for future hauls from increasingly deeper mining elevations.

Drilling and blasting
Production drill and blast operations at Kansanshi are carried out by First Quantum Minerals Operations (FQMO) personnel. An explosives supply contractor manufactures bulk explosives in an on-site emulsion plant and delivers explosives under a “down-the-hole” contract.

Production drill and blast patterns are drilled on 5 m or 10 m high benches, as determined by the geological conditions. For production blasting on 5 m high benches, 115 mm diameter holes are used. Whereas for 10 m high benches, 127 mm and 165 mm diameter holes are used.

Wall control blasting requires the use of dedicated presplit designs, involving packaged explosives, with patterns designed according to the rock mass properties and pit wall profile. Trim blasts are designed according to the bench height and pit wall profile, and typically consist of two to three rows of 115 mm diameter holes and a number of rows of production holes.

Blast movement (heave and throw) is minimised by designing initiation sequences relative to ore/waste blocks and then by tracking material movement using blast movement indicators. Electronic delay detonators provide flexibility to the engineers for production and wall control initiation design.

In-pit crushing and conveying of ore (IPCC)
All ore hauled direct from the Kansanshi Pits or reclaimed from stockpiles, is currently fed to primary crushers adjacent to a ROM pad at the plant site.

The primary crushing circuit for the S3 expanded plant will comprise semi-mobile, independent, gyratory crushers (IPCs, ThyssenKrupp KB 63 x 89 or ThyssenKrupp KB 63 x 130) operating in open circuit. Each crusher will be positioned in-pit and remote from the S3 plant area, and crushed ore will be transported to the plant by an overland conveyor.

Trolley-assisted haulage
Towards the end of 2009 a mine electrification programme was implemented at Kansanshi to supplement the then existing diesel-electric trucks with an AC-drive fleet fitted with trolley assist (TA) pantographs. Four trolley lines have now been installed on the Main Pit ramps, over a total length of 3.7 km. These ramps are as follows:
• M10 ramp; 826 m in length, for ore and waste haulage;
• M12 ramp; 750 m in length, for ore and waste haulage;
• M6 ramp; developed in two segments of 896 m and 555 m length, used mainly for waste haulage;
• Congo ramp; 634 m length, used mainly for waste haulage.

Each trolley ramp is capable of accommodating three trucks (M6 accommodates five trucks over the two ramp segments). The benefits of trolley-assisted haulage include:
• reduction on diesel fuel consumption;
• increase in up-ramp speed from 11 kmph for diesel haulage, to 23 kmph;
• a 700 m length trolley line improves cycle times by 7% per load on a 28 minute haul cycle;
• a 700 m length trolley line usage converts to a ~$3.50/hr truck engine overhaul saving.

Mine design parameters
For more detailed planning, the following parameters were adopted in designing the pit layouts to suit trolley assist truck haulage:
- haul road minimum width = 5 x truck width (to allow up-haulage off the trolley line) = 41 m;
- total haul road width inclusive of catenary pole, bund and side drain = 50 m;
- maximum gradient = 1 : 10.

Ore delivery, primary crushing and crushed ore storage
Direct mined/tipped ore is hauled to a surface run-of-mine (ROM) pad located immediately to the north of the processing plant. Feed from direct mine sources, in addition to ore reclaimed from a number of surface stockpiles is tipped into one of three separate primary crusher dump pockets.

The sulphide and mixed ore crushing circuits comprise primary gyratory and open circuit secondary cone crushers, whilst the oxide crushing circuit comprises a primary jaw crusher and a secondary sizer. Each of the crushed ore product streams is conveyed to dedicated coarse ore stockpiles ahead of the grinding circuits.

A magnetic resonance analyser (MRA) ore sorting installation at Kansanshi is positioned on the sulphide circuit’s 2,800 t/h primary crushed conveyor belt, with the system taking precise measurements every four seconds for tonnages in the region of 2.5 t to a precision of +/- 0.028%.

Grinding circuits
The grinding circuits are all SABC circuits, each comprising a SAG mill, ball mill and pebble crusher.

Each mill is equipped with hydrocyclones, with cyclone overflow gravitating to the respective rougher flotation circuit, and cyclone underflow from both the SAG and ball mill cyclones being directed to the ball mill. Coarse material from the SAG mill discharge screen is conveyed to a pebble crusher for each circuit and crushed pebbles are returned to the SAG mill feed conveyor.

Each circuit is capable of gravity gold recovery from multiple centrifugal concentrators, mainly treating a bleed stream from the cyclone underflow in each circuit. The various gravity concentrates are all treated in the central gold room facility to produce gold doré bars.

The S3 expansion project
Primary crushing and crushed ore storage
Primary crushing will be carried out by two semi-mobile, in-pit, independent gyratory crushers (IPCs) operating in open circuit. One of these will be installed near-surface, on the south western side of the Main Pit, and the other will be installed near-surface on the south western side of the South East Dome.

Each crusher will be equipped with a transfer conveyor and a variable length discharge conveyor connecting the IPC facility to a surface transfer point. The mine plan attempts to minimise the number of in-pit transfer points along the discharge conveyor route. At the pit top transfer point, IPC product will be transferred onto an overland conveyor across to the S3 plant stockpile. Crusher operation will be for nominally 16 hours each / day with a lower availability of 85% requiring an average feed rate to the crushed ore stockpile of 5,351 tph.

The crushed ore stockpile will have 13 hours live capacity, equivalent to about 40,000 tonnes. Ore will be recovered from below the crushed ore stockpile by four variable speed apron feeders located in a single reclaim tunnel

Grinding circuit
Crushed ore reclaimed from the stockpile will be fed to a SAG mill. The 28 MW mill will be 12.2 m in diameter with an effective grinding length (EGL) of 8.2 m. A high-low liner configuration has been proposed, without pebble ports in the discharge grate. Oversize material from the SAG mill discharge screen will fall onto a conveyor and be transferred back to the SAG mill feed conveyor. Allowance has been made for future crushing of the oversize should this be required. The SAG mill will discharge into a sump and the ground product then pumped to a dedicated cyclone pack.

Ball milling will be accomplished in a single 22 MW, 8.5 m diameter, 13.3 m EGL (effective grinding length) ball mill. It will be fed by a combination of SAG mill cyclone underflow and recirculated ball mill cyclone underflow. Should the ball mill be down for relining, it will be possible to run the SAG mill in a single stage configuration, at a reduced feed rate. Dedicated liner handling machines will be provided for the SAG and ball mills to enable mill liner changing.

The processing facilities at Kansanshi comprise three main processing circuits; an oxide circuit with an approximate capacity of 7 Mtpa, a mixed ore circuit with a capacity of 8 Mtpa and the S2 sulphide circuit with a capacity of 13 Mtpa.

All ore types are treated in separate circuits via crushing, milling and flotation to produce copper in concentrate. In addition, oxide ore and a portion of mixed ore flotation tailings are leached and subject to solid-liquid separation, followed by solvent extraction (SX) and electrowinning (EW) to produce copper cathode.

Flotation
Each of the circuits includes a flotation section to recover sulphide minerals from the different ore types. Each flotation circuit includes rougher, rougher-scavenger, cleaner and recleaner sections, and the final concentrate from the sulphide circuit is treated in primary and secondary Jameson Flotation Cells to produce a final concentrate product. The oxide and mixed ore circuits use control ........