The Mount Keith (Mt Keith) nickel mine is a large-scale, low-grade sulphide ore open-pit operation located in Western Australia.
BHP Billiton owns and operates the Mt Keith mine and concentrator as part of its mine-to-market integrated nickel business Nickel West, which also includes the Cliffs and Leinster underground mines, and the Leinster and Kambalda concentrator plants, along with the Kalgoorlie nickel smelter and the Kwinana nickel refinery in Western Australia.
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The Mt Keith nickel mine was brought into production by Western Mining Corporation (WMC) in 1995, while BHP became its owner and operator by acquiring WMC in 2005.
BHP commenced production from the Mt Keith satellite mine to extend Mt Keith’s operational life by more than 12 years in December 2019.
With the demand for battery-grade nickel anticipated to grow by six times over the next decade, driven by the increasing adoption of electric vehicles (EVs) worldwide, BHP is further planning to ramp up the production from the Mount Keith nickel mine by 40% in 2022.
The mining leases granted by the Western Australian Government for the Mount Keith nickel operation are scheduled to expire between 2029 and 2036.
Mt Keith location, geology, and mineralisation
The Mt Keith nickel mine is located in the Northern Goldfields region of Western Australia, approximately 485km north of Kalgoorlie.
The ore body lies on the northern edge of the 800km-long Norseman-Wiluna Greenstone belt of the Yilgarn Craton in Western Australia, while the Mount Keith satellite deposit is located within the Yakabindie Greenstone belt, approximately 20km south of the main mine.
The Mt Keith ore deposits are characterised by disseminated textured, magmatic nickel-sulphide mineralisation hosted in olivine mesocumulates and are associated with a metamorphosed ultramafic intrusion.
Mt Keith satellite project details
The Mt Keith satellite (MKS) project involved the development of two new open-pit nickel sulphide mines at Yakabindie, namely Six Mile Well and Goliath, along with a waste rock facility and ancillary infrastructure.
The project was approved by the Environmental Protection Authority (EPA) of Western Australia in December 2018, while the construction works were started in February 2019 with production commencing in December of the same year.
The ore produced from the satellite mine is transported by road trains for processing at the Mt Keith mine complex, located 20km away.
Mt Keith mine expansion details
The Mt Keith mine expansion targets to increase the mining activity at the main pit by 50% with the addition of two new Liebherr 9600 and 9400 excavators to the existing fleet.
The Mt Keith concentrator facility will be expanded from the existing 10.5 million tonnes per annum (Mtpa) ore treating capacity to 15Mtpa by installing new stockpile feed conveyors, and a third and much bigger 16MW semi-autogenous (SAG) mill.
The floatation circuit of the plant will also be modernised using Concorde cell floating technology from Metso Outotec to increase the recovery of ultrafine nickel particles. A flash flotation unit is also planned to be installed in the grinding circuit of the Mt Keith concentrator facility in 2022.
Production at Mt Keith
The Mt Keith mine produced 224.6 thousand tonnes (Kt) of nickel concentrate in the year ended 30 June 2021, compared to 178.2Kt produced in the previous year.
Nickel reserves at Mt Keith
The proved and probable ore reserves of the Mt Keith main pit were estimated to be 84 million tonnes (Mt) grading 0.57% nickel as of June 2020, while those of the Mt Keith satellite mine were estimated to be 163Mt grading 0.57% nickel.
The contained nickel metal in measured, indicated and inferred ore resources of the Mt Keith and the Mt Keith satellite deposits were estimated to be 1.18Mt and 2.5Mt, respectively, as of June 2021.
Mining and processing of ore from the Mt Keith mine
The conventional open-pit mining method, involving drill, blast, truck, and shovel operations, is deployed for ore extraction at the Mt Keith mine. The run-of-the-mine (ROM) ore is crushed and processed at the 10.5Mtpa Mt Keith concentrator facility.
The nickel concentrate produced at the plant is transported by road to the Leinster processing facility for drying, after which it is sent to the Kalgoorlie nickel smelter to produce nickel matte.
The granulated nickel matte is further processed at the Kwinana nickel refinery to produce high-grade refined nickel, which is transported to the Port of Fremantle for overseas export.
A nickel sulphate plant is also planned for commissioning at the Kwinana nickel refinery by the end of 2021.
Nickel supply agreement
BHP signed a nickel supply agreement with Tesla, the world’s biggest manufacturer of electric vehicles and battery storage systems, in July 2021.
Infrastructure facilities for the Mt Keith mine
The Mt Keith mine complex receives power from an on-site gas-fired electricity generating facility operated by a third party, while diesel generators are used for back-up power supply.
The mine site also has a vast tailings storage facility. Spanning 5km-wide, the Mt Keith tailings dam is one of the biggest tailings dams in Australia.
Solar farm for Mount Keith nickel operation
In July 2021, BHP announced to build a 27.4MW solar farm at Mt Keith, in partnership with TransAlta, as part of the Northern Goldfields solar project that also includes a 10.7MW solar farm and a 10.1MW battery storage facility at the Leinster mine.
The construction works on the solar project are expected to be started by the end of 2021 with the start of operations expected by early 2023.
The solar farms and the battery facility will be built, owned, and operated by TransAlta as part of a power purchase agreement (PPA) extension signed in October 2020. The new clean energy facilities are intended to displace the diesel and gas-fired power generation at Mt Keith and Leinster, and reduce emissions from electricity use at both the mine sites by 12%.
Contractors involved in Mt Keith mine expansion
DRA Global, an engineering and project management company focused on mining and based in Australia, was contracted for the detailed engineering and design services for the expansion of the crushing and grinding circuit at Mt Keith in June 2021.
Metso Outotec was contracted to provide its proprietary Concorde CellTM flotation technology for the Mt Keith nickel concentrator in August 2021. Metso is also providing the third SAG mill for the facility.
