Kansanshi Copper-Gold Mine

With the increased reserves and resource estimates, the current mine life is expected to be extended to 24 years.

Project location and geology

The Kansanshi copper-gold mine is located in the North-Western Province of Zambia, approximately 15km north of the town of Solwezi and 180 km northwest of Chingola.

The copper-gold deposit is located in the Zambian Copperbelt with the mineralisation hosted by deformed metasediments of the Nguba Group within the Katanga Supergroup. The stratigraphic sequence of mineralised rocks comprises of dolomites, dolomitic marbles, and various schists and phyllites.

Mineralisation and reserves

The Kansanshi ore body comprises three mineralised zones namely, the Main, North West, and the South East deposits that occur in domal structures along the crest of a regional antiform. Primary sulphide mineralisation occurs as chalcopyrite with minor bornite, while the oxide mineralisation occurs primarily as chrysocolla with malachite.

The proven and probable reserves at Kansanshi were estimated to be 842.7Mt grading 0.64% Copper and 0.12g/t of gold As of June 2020. The proven and probable stockpile reserves were estimated to be 128.1Mt containing 0.46% Cu.

Mining operations and expansion

The Kansanshi mine comprises two open pits namely, the Main pit and the Northwest pit. The mining operations are based on conventional drill and blast, shovel, and truck mining techniques. The two pits are planned to eventually merge through a sequence of cutbacks from both the pits that are 200m to 300m wide.

The Kansanshi S3 expansion project to increase the sulphide processing facilities along with the development of an open-pit for the southeast Dome deposit was halted in 2013. The expansion project involves the construction of a 25Mtpa stand-alone copper concentrator and an overland conveyor.

The project is planned to be resumed with the commissioning of the process plant expected in the second half of 2024. To follow up with the plan, the southeast Dome pit pre-strip operations are also expected to commence in 2024. The project will have a primary crushing circuit comprising of an open-circuit, semi-mobile, independent, gyratory crushers.

Mineral processing

The concentrator facility for the Kansanshi mine has three main processing circuits; an oxide circuit with an approximate capacity of 7Mtpa, an 8Mtpa mixed ore circuit, and the S2 sulphide circuit with a capacity of 13Mtpa.

The sulphide and mixed ores undergo two-stage crushing in a primary gyratory, and open-circuit secondary cone crushers while the oxides are crushed in a primary jaw crusher and a secondary sizer.

The grinding circuits comprise a SAG mill, a ball mill, and a pebble crusher equipped with hydro cyclones. The cyclone overflow feeds the rougher flotation circuit while the cyclone underflow from both the SAG and ball mill cyclones are re-directed to the ball mill.

Each of the flotation circuits includes a rougher, rougher-scavenger, cleaner, and recleaner sections, and the final concentrate product is produced through primary and secondary Jameson Flotation cells that treat the final concentrate from the sulphide circuit.

The obtained copper concentrate undergoes acid leaching in five leach tanks followed by thickening in a counter-current decantation (CCD). The pregnant leach solution (PLS) is treated through solvent extraction and electrowinning (SX and EW) to produce copper cathodes for export.

Gold is produced via natural flotation of the finer gold particles from the flotation concentrate which is introduced to copper anodes. The milling circuits are also installed with centrifugal concentrators to enable gravity gold recovery from the cyclone underflow.

Kanshanshi smelter

The Kansanshi copper smelter (KCS) that started commercial operations in March 2015 has the current capacity to smelt 1.38Mtpa of copper concentrate. It features a single Isasmelt furnace, one 6-in-line electric furnace for matte settling and slag cleaning, four PeirceSmith converters (PSCs), and two conventional rotary anode furnaces.

The Isasmelt furnace operates at a feed rate of up to 180t/h of concentrate. Matte and slag from the furnace are introduced to the electric furnace for separation. While the slag is transferred into slag cooling pits, the matte is transferred to the converters to produce blister copper. The blister undergoes final refining in anode furnaces to produce anode copper.

Infrastructure facilities

The Kansanshi Operations is accessible via a 12km-long sealed road connecting Solwezi in the north.

The electrical power supply is received via a 330kV overhead transmission line from Luano. Two 65 MVA, one 80 MVA, and two 120 MVA transformers are used a step down to the voltage to 33 kV. State-owned power company ZESCO supplies electricity for the mine under a fixed-term agreement.

The process water requirement of approximately 91.4ML/day is received primarily from the mine dewatering activities as well as from the Solwezi River and a dam previously constructed for the S3 expansion.

Contractors involved

Fluor provided the engineering and design services for the expansion of the sulphide circuit at the Kansanshi smelter in 2011.

Outotec delivered a SAG mill, which was considered to be the world’s biggest SAG mill, for the mine under a contract awarded in 2012. Integrating Outotec’s patented Turbo Pulp Lifter (TPL™) technology, it can be operated as a single-stage SAG mill performing both primary and secondary grinding functions.

Outotec also provided critical processing equipment including four grinding mills, multiple flotation cells, and thickeners for the Kansanshi concentrator facility that commenced operations in 2004.