The Motheo Copper Project is an open-pit mine being developed in Western Botswana by Sandfire Resources, a mining and exploration company based in Australia.
The project mainly involves the development of the T3 deposit located in the Kalahari Copper Belt. Completed in December 2020, the definitive feasibility study (DFS) for the project confirmed the potential to develop an open-pit mine with an estimated life of mine (LoM) of 12.5 years.
The development cost of the Motheo copper project is estimated at $259m. Sandfire received a mining licence for the project from the Government of Botswana in July 2021, paving the way for full-scale construction. The mine is expected to generate approximately 1,000 jobs during the construction phase and 600 full-time jobs during the production phase.
The first copper from the mine is expected in the first quarter (Q1) of 2023.
Motheo copper project location and geology
The open-pit mine is located within prospecting licence (PL) 190/2008, approximately 80km north-east of Ghanzi town in western Botswana.
Located in the Ghanzi-Chobe belt, the main T3 deposit is a sediment-hosted copper and silver deposit comprising the basal volcanic lithofacies of Kgwebe Formation, overlain by siliciclastic sedimentary lithofacies of Ghanzi Group.
The Ghanzi Group, which is a siliciclastic marine sedimentary group, is composed of sandstones and conglomerates of the Kuke Formation overlain by arkose, siltstone, shale, and limestone of the N’Gwako Pan, Mamuno, and D’Kar formations. The T3 deposit has a strike length of approximately 2km and down-dip extension of 720m.
Motheo copper project mineralisation and reserves
Mineralisation at the T3 deposit remains open at depth. The orebody of the deposit contains sulphide copper minerals, such as bornite, chalcopyrite, and chalcocite. The mineralisation is dominated by vein-hosted chalcopyrite and bornite, while disseminated chalcocite is found in lesser amounts. The host rocks at the Motheo copper project include limestone, shale, black shale, marl, siltstone, and sandstone.
The proven and probable mineral reserves at the Motheo project were estimated at 39.9 million tonnes (Mt), grading 0.90% copper (Cu) and 12.2g/t silver (Ag), as of December 2020.
Mining methods at Motheo copper mine
The Motheo copper project will involve conventional open-pit mining operations using truck and shovel (excavator) method. The design opted for the open-pit operations that suit the orebody characteristics and reduce dilution and ore loss while improving the safety of mining operations.
The open-pit copper mine is being developed in four stages using Whittle mine planning software.
Choked or semi-choked blasting methods will be implemented to undertake drilling and blasting of ore and waste, while 250t excavators and 140t class haul trucks will be used to perform load and haul operations. The mining operations will be conducted on approximately 2.5m-high flitches in ore zones and 3.5m-high flitches in bulk waste zones.
Ore processing details
The processing plant of the copper project will have an initial nameplate capacity of 3.2 million tonnes per annum (Mtpa), with the potential for expansion up to 5.2Mtpa. The plant availability is estimated at 92%.
The run-of-mine (ROM) ore will undergo single-stage crushing in a primary crusher followed by grinding and classification of ores passing 212µm. The ground ore will be introduced to the flotation circuit comprising rougher and cleaner flotation, and regrind stages.
The concentrate from the flotation circuit will be transferred to the thickening and filtration circuits to produce a copper concentrate filtrate. The produced concentrates will be stored for export.
The project area will be accessed from the A3 Highway via a two-way, 14km-long access road that will be fenced with gates installed at multiple points to provide access to farmers for the movement of livestock.
The initial power requirement of 13MW for the project will be met via a grid connection with Botswana Power Corporation (BPC). The DFS also outlines the construction of a new switching station at the corner of the A3 Highway and a site access road to enable the grid connection.
A 14km-long 132kV overhead transmission line will transmit power to the substation located adjacent to the processing plant.
The installation of a 12-15MWp solar photovoltaic (PV) plant and a 2-4MW Li-ion battery energy storage system is also being considered.
The raw water needs for the processing plant will be met from pit dewatering bores from where water will be pumped to the dewatering transfer pond near the mine before being transferred to the raw water pond located in the processing plant.
A tailings storage facility comprising an embankment with a storage capacity of approximately 50Mt of tailings will be built.
A permanent operations camp with the capacity to accommodate 750 people will also be built near the project site. A temporary construction camp will be built that will be able to house 200 workers within the mining licence.
Contractors involved in Motheo copper project
Global mining services group Perenti Global’s subsidiary African Mining Services (AMS) was awarded a contract worth $496m to provide open-pit mining services for the Motheo copper project in June 2021.
Lycopodium was engaged to undertake the DFS for the project, which also included study of the processing plant engineering and associated infrastructure, in January 2020. The company was supported by Knight Piésold, Orelogy Consulting, AQ2, John Wood Group, LOCI Environmental (Botswana), and Sandfire in the preparation of the DFS.
Lycopodium was also awarded the engineering and procurement services contract for the project in December 2020.