The Dalgaranga Gold Project is located approximately 70km north-west of Mt Magnet, within the Murchison gold mining district in Western Australia. The project will involve the development of the brownfield Gilbeys deposit and the greenfield Golden Wings deposit.
The project is 100% owned by Gascoyne Resources. Mining lease for the Dalgaranga project was granted in September 2013.
The prefeasibility study (PFS) for the project was completed in March 2016 and the full feasibility study was completed in November 2016. The construction works started in 2017, with first production anticipated to start in the third quarter of 2018.
The pre-production capital cost for the processing plant and associated infrastructure is estimated to be A$86m ($65m approximately). The mine is expected to have a life of six years, and produce 105,000oz per annum during the first two years.
Dalgaranga Gold Project geology and mineralisation
The two deposits are located approximately 3.5km from each other. The brownfield Gilbeys deposit, which was developed from 1996 to 2000, produced approximately 229,000oz of gold.
The project is situated within the Archean Dalgaranga Greenstone. The mineralisation at the Gilbeys deposit occurs as quartz-pyrite-carbonate veins within a sheared porphyry-shale-basalt package. The deposit was mined to a depth of approximately 130m below surface, and continues to host mineralisation below the base.
The Golden Wings deposit extends for more than 400m east-west. The gold mineralisation is hosted within a sequence of high-magnesium basalts, basalt and interflow sediments (black shales), and minor porphyries.
The mineralisation extends to surface with 46% of the resource capable of being extracted using free dig. The mineralisation remains open at depth and along strike.
Reserves and production details
The project is estimated to contain combined proven and probable reserves of 13.3 million tonnes (Mt) grading 1.29g/t, containing 552,000oz of gold.
The combined measured, indicated and inferred resources are estimated at 25.7Mt grading 1.4g/t and containing 1.12Moz of gold.
Mining and processing at the Murchison gold mine
The mining method envisaged for the project is the conventional open-pit mining method, integrating drill, blast, laud and haul operations to be performed by a mining contractor. The Golden Wings deposit will be mined through a single-staged pit, whereas the existing Gilbey’s pit will be mined using a four-staged cutback.
The 2.5 million tonnes per annum (Mtpa) processing plant proposed for the project will incorporate a primary crushing circuit, a semi-autogenous grinding (SAG) mill, a gravity concentration and intensive leaching circuit, a classification circuit, a leaching and adsorption circuit, an elution circuit, an electrowinning circuit, and a smelting facility.
Construction of the processing plant is progressing on schedule for commissioning in May 2018.
Infrastructure for the Western Australian gold project
The process water required during the first two years of production will be sourced from the existing Gilbeys pit void, whereas an existing borefield will supply the water for the remaining three years. The potable water will also be supplied by an existing borefield following treatment using reverse osmosis (RO) technology.
The existing tailings storage facility (TSF) will be lifted by an additional 5m to serve the project for the first two years of production, while the Golden Wings pit, which is to be mined first, will serve as the TSF for the remaining three years. The initial TSF lift comprises the construction of a 3.5m embankment.
GNT Resources, a wholly owned subsidiary of Gascoyne Resources, has executed a Power Purchase Agreement with Zenith Pacific (DGA), a fully-owned subsidiary of Zenith Energy, for the construction and operation of a 15MW gas-fired power station for the gold project.
A new airstrip is being constructed next to the Dalgaranga village, which is scheduled to allow direct flights to the site from March 2018.
Workers will be accommodated at the newly constructed 240-member accommodation camp at Dalgaranga, approximately 4km east of the Gilbeys pit and the processing plant.
The PFS was compiled using inputs from RungePincockMinarco (RPM) for the resource estimates, CSA Global for the mining studies and reserve estimate, and Mintrex for the process engineering, and operating and capital costs estimates.
GNT Resources awarded the mining contract for Dalgaranga gold project to NRW Holdings.
GR Engineering Services was awarded a $66.5m contract by GNT Resources in July 2017 for the design and construction of the Dalgaranga processing facilities.