Gruyere gold project delivers first gold pour
READY, SET, GOLD Gold Road Resources' focus now turns to commissioning of the final components of the gold process plant, which is expected to be in the September quarter
Photo by Reuters
Australian gold miner Gold Road Resources’ Gruyere gold project, in Western Australia, delivered its first gold pour from the carbon-in-leach (CIL) circuit in the June quarter of this year, containing 1 138 oz of gold.
This milestone, which was achieved safely and in line with the final forecast capital cost estimate of $621-million, elevates Gold Road to the ranks of Australian Security Exchange-listed gold producers and comes less than six years since the Gruyere deposit was discovered, according to Gold Road’s quarterly report for the quarter ending June 30.
Gruyere is a joint venture (JV) with global gold miner Gold Fields, which operates and manages the project.
With the delivery of gold from the entire CIL processing circuit, the focus now turns to commissioning of the final components of the process plant, such as the ball mill, which is anticipated to be completed in the first half of the September quarter this year.
Once the ball mill is fully functioning, the design throughput of up to 1 000 t/h will be achievable. The start of the operation of the ball mill will mark the start of the anticipated ramp-up period of six to seven months to full production.
During the commissioning and initial stages of ramp-up, lower-grade stockpiled ore is planned to be processed to reduce gold losses associated with the lower recoveries anticipated while plant operations are stabilised.
Delays to completion of construction and plant commissioning resulted in the Gruyere JV revising forecast gold production for this year to between 75 000 oz and 100 000 oz, down from the previous guidance of 100 000 oz to 120 000 oz.
All-in sustaining costs for the period from attainment of commercial production to the end of this year are likely to be higher than previous guidance of between $1 050/oz and $1 150/oz. This is primarily a timing issue owing to the reduced period between commercial production and the end of this year, arising from the aforementioned delay and reduced production guidance. The Gruyere JV will provide revised cost guidance once commercial production is achieved, which is anticipated half-way through the ramp-up period, according to the company.
Mining continues ahead of plan, with more than 2-million tonnes of ore mined and stockpiled by the end of the quarter, which de-risks mining-related aspects of the operation during the ramp-up phases. Ore tonnages mined are closely aligned to ore reserve and grade control estimates. Estimates of gold grades are closely aligned to projections.
With the first gold pour on June 30 of this year, no gold was sold during the June quarter.
Exploration
A 9 000 m drilling programme, designed to extend the indicated resources below the current ore reserve pit design and delineate the limits of mineralisation at the southern end of the Gruyere porphyry, started in the June quarter. The programme is expected to be completed in the September quarter.
In addition, Gold Road focused its exploration efforts on the Gilmour deposit and Morello prospect in its 100%-owned southern project area.
At the Gilmour deposit, drilling was designed to extend mineralisation both along strike as well as at depth to support an estimation of a maiden mineral resource, the company states.
The best intersections from drilling include 2.06 m at 12.4 g/t gold from 357.2 m; 4 m at 4.96 g/t gold from 199 m; 7 m at 2.20 g/t gold from 146 m; and 2.78 m at 5.25 g/t gold from 401.43 m.
Initial metallurgical testwork on five reverse circulation (RC) samples indicated potential recoveries at Gilmour ranging from 89% to 99% and averaging 96%, with significant gravity recoverable gold ranging from 28% to 82% and averaging 61%. Resultants were consistent with the abundant free gold observed in drill samples.
The Morello prospect RC and diamond drill programme defined potential new shoots including an area untested by bedrock drilling adjacent to the Rocha Fault, which is an analogous geological position to the Gilmour high-grade shoot.
The best intersections included 7 m at 3.59 g/t gold from 167 m; 3 m at 6.80 g/t gold from 123 m, and 3 m at 4.94 g/t gold from 157 m.
The Morello shoot remains open at depth and will be evaluated and ranked against other projects before work is progressed.
In the 100%-owned northern project area, the company completed first bedrock diamond drilling at the Brahman and Bloodwood 8 targets, with the objective of refining knowledge of geological controls.
The best intersections drilled at Brahman was 2.5 m at 1.20 g/t gold from 126.5 m, and at Bloodwood 8 was 1.7 m at 3.30 g/t gold from 114 m.
Further diamond and RC testing has been planned for the December quarter.
During the quarter, several Milestone 1 and 2 targets were tested with aircore drilling. In the northern project area, programmes were completed at Corkwood North and Stock Route, and further work was conducted south of the Smokebush prospect and at Tobin Hill in the southern project area. Follow-up programmes on these prospect areas will depend on ranking priorities once assays and geological data has been assessed.
Planned exploration work for the September 2019 quarter will focus on the Gruyere drilling programme and early stage exploration targets in the southern project area.
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