King of the Hills (KOTH) gold project is an underground gold mine located in the Eastern Goldfields region of Western Australia.
The project is 100% owned by Red 5, which acquired the mine from Saracen Mineral in early 2017.
Mining at the site started in January 2018. The mine, which currently employs underground mining, is planned to be developed as a stand-alone bulk mining operation. A final feasibility study for a bulk open-pit and underground gold mine and stand-alone processing plant operation is expected to be completed in September 2020.
Based on a pre-feasibility study unveiled in August 2019, the production from the open-pit is expected to be 140,000oz with an estimated mine life of ten years. The project’s initial capital investment is estimated to be A$218m ($150m), which will cover the construction of a processing plant to support the proposed integrated mining operation.
Location, geology and mineralisation of King of the Hills gold project
The King of the Hills gold mine is located 80km south of Red 5’s Darlot gold mine and 28km north of Leonora town. Its mineralisation domains are hosted by a large trondhjemite granite pluton with overlying, strongly foliated mafic and ultramafic sequences.
The deposits that comprise the proposed KOTH integrated mining operation are KOTH, Rainbow and satellite open-pit resources, including Severn, Cerebus-Eclipse and Centauri. The regional satellite deposits provide the potential for production and cash flow in the initial stages of the bulk operation.
Gold mineralisation occurs in sheeted quartz veins within a hosting granodiorite stock and carbonated altered ultramafic rocks.
In June 2018, the King of the Hills gold project was estimated to contain 0.71 million tonnes (Mt) of probable reserves, comprising 88koz of contained gold at a grade of 3.9g/t of gold.
The open-pit ore reserves estimated as part of the 2019 PFS include underground reserves, which are now planned to be mined using open-pit mining. The company is expected to revise the underground reserves as part of the FFS. The KOTH project has maiden open-pit probable ore reserves of 36Mt, grading at 1.25g/t with contained gold of 1.45Moz.
Mining and processing at King of the Hills gold project
Red 5 employs both bulk underground stoping and airleg mining to extract ore from the mine.
The open-pit mining operation at the project will involve conventional truck and excavator mining, as well as drilling and blasting.
The average annual production from the existing underground operation currently stands at approximately 500,000t. The produced ore is transported to the nearby Darlot processing plant.
The project mined 161,379t in the second quarter of 2020. The proposed mine development plant will include the construction of a new processing facility onsite with a capacity of 4Mtpa of gold ore. The plant will operate at a nominal treatment rate of 500 dry tonnes per hour.
The carbon in leach (CIL) processing circuit will include a single-stage crusher, a semi-autogenous grinding (SAG) mill, a centrifugal gravity concentrator, CIL adsorption, recovery of gold and calcining and smelting doré.
The preliminary design of the tailings storage facility (TSF) considers the processing of 21Mt of gold ore over 5.3 years, discharging into TSF4 and TSF5. The existing TSF4 is planned to be recommissioned to provide tailings storage capacity for one year.
The plan also includes the completion of the construction of the TSF5 first stage and raising it to support storage requirement for 5.3 years, and potential development of TSF6 for the balance of the life of mine.
Infrastructure at King of the Hills gold project
Infrastructure to be created at the mine site as part of the bulk mining operation will include access roads and tracks, a 280-room village, internal roads, culverts, hardstands, water ponds and drains, transportable offices and other buildings.
Transport of 240 second-hand portable rooms, a wastewater treatment system and a 1,050m² office complex to the site begun. The tender for the building contract of the village commenced and a visit to the tender site was concluded.
The site will also have steel-framed structures, including workshops, warehouse and storage areas, and fuel storage and distribution facility. Additional infrastructure will include power supply, power reticulation, water supply for processing needs and wastewater treatment.
The mine will use the Leonora aerodrome to fly workers to and from the site.
Total installed power capacity of 20MW will be established to support operations. A natural gas-fired power plant will service the project site.
Key players involved
CSA Global is compiling the independent technical expert’s report, which will support the financing of the KOTH gold project.
SRK and Entech are managing the mine planning studies and mine schedules.
GR Engineering Services (GRES) performed the plant design and cost estimates for the process plant and other on-site infrastructure.