The Leonora gold project is a high-grade gold mine being developed by Kin Mining in Western Australia.
The pre-feasibility study (PFS) of the Western Australian gold project was completed in December 2016, while the definitive feasibility study (DFS) was completed in October 2017. The mine is expected to produce 372,000oz of gold per annum through an estimated mine life of seven years.
Kin Mining produced first gold in September 2016 as part of the trial mining programme initiated at the Lewis deposit within the Cardinia deposit. Initial site activities at Leonora commenced in February 2018 but suspended in May 2018 following a decision to conduct a comprehensive capital cost review of the project.
Leonora gold project location, geology, and mineralisation
The Leonora gold project is located within the shire of Leonora in the Mount Margaret mineral field of the eastern goldfields. It comprises three mining centres namely Mertondale, Cardinia, and Raeside, which are hosted by a series of shear zones that cut through a typical Eastern Goldfields greenstone sequence.
The Cardinia prospects are located above a sequence of intermediate-mafic lithologies and epiclastic sediments. The Bruno and Lewis areas of the Cardinia centre host felsic porphyries and lamprophyre rock formations in lesser volumes.
Gold mineralisation at the mine is generally stratiform within the dolerite and certain sedimentary horizons. Most of the mineralisation within the Raeside prospect is made up of a mixture of fine-grained sediments and a quartz dolerite unit.
Leonora gold project reserves
The proven and probable ore reserves at Leonora gold project are estimated to be 7.9Mt, grading 1.5g/t Au, while contained gold is estimated to be 373,000oz.
The indicated and inferred mineral resources are estimated to be 22.3Mt, grading 1.4g/t gold.
Mining and processing of ore at Leonora gold project
Conventional open-pit mining method will be employed to extract ore from the three mining centres at the Leonora gold project.
The Cardinia deposit mainly contains oxide and transitional ore while the Mertondale area hosts oxide, transitional, and fresh ore. The Raeside deposit is expected to contain transitional and fresh ore.
Initial mine plan focuses on extracting oxide and transitional ore from the Cardinia deposits, followed by the Mertondale and Raeside pits in the third and fourth year respectively. The later phases of mining will include the blending of the harder material from Mertondale deposit with the softer oxide and transitional ores.
The mine will comprise a 1.5Mtpa conventional processing plant at Cardinia, featuring a 2.5MW ball mill and six 1,500m³ carbon-in-leach (CIL) tanks. Ore will be hauled in 100t trucks from the mining area and dumped onto the ROM pad for grading.
A front-end loader (FEL) will be used to transport the graded material to the primary crushing plant, followed by secondary crushing. The crushed material will be forwarded to the 2.5MW ball mill, followed by gravity and CIL circuits to extract gold.
Kin Mining secured an A$35m ($27m) binding senior secured credit facility from Sprott Private Resource Lending for the development of the project.
The project can be accessed from the town of Leonora through the sealed Leonora-Laverton highway and a well-maintained private road to Cardinia. A new 10km haul road to the proposed Cardinia mill is planned to be built as part of the project.
Initial main water supply will be made from the historical production bores at Mertondale 3-4 and Mertondale 5 pits. Freshwater will be provided by a reverse osmosis unit at the processing plant. A 20km water supply pipeline is planned to be constructed from Mertondale 3-4 to the Cardinia mill.
The power required by the project will be provided by an onsite power station comprising six 1,250kVA containerised diesel generating sets. Employees and contract personnel are proposed to be accommodated at the nearby town of Leonora.
Perth-based independent consultants Peter O’Bryan & Associates prepared the geotechnical assessments of the project as part of the DFS.
Kin Mining engaged SMS Innovative Mining Solutions for conducting site activities at the mine while Como Engineers was engaged as external and principal consultant to conduct an independent review of the project.