Ora Banda Mining is on track to achieve steady-state production at its Riverina underground gold mine near Kalgoorlie in the June quarter with capital projects complete and first stopes to be mined next month.
First ore from the underground operation in Western Australia was processed as a single batch through the company’s nearby Davyhurst processing plant and returned 16,727 tonnes at 2.74 grams per tonne and 93.9 per cent recovery to produce 1383 gold ounces.
Management says reconciliation was 4 per cent above the mine call grade and about 16 per cent above the designed block model grade. Once stoping begins, the development grade is expected to double due the stoping width of 2.2m compared to 4.5m in development, bringing it in line with the overall reserve grade of 4.3g/t.
Ora Banda today reported that its overall development rates within the mine have increased, with January achieving a record advance rate of 575m – representing a 97 per cent increase from the July-to-December average last year of 292m.
Completed capital projects include the primary ventilation system, the primary surface pump station, the surface power station and underground sub station, in addition to key surface infrastructure.
Meanwhile, the company is continuing a diamond drilling program, with 7379m of infill and extension drilling polished off since its most recent operational update in November. The work is aimed at producing further infill and extensional targets at Riverina.
Significant high-grade intercepts include 3m grading 20.1g/t gold from 204.7m including 2m at 29.8g/t from 205m, with a peak grade discovered in a separate 0.3m section going 98.6g/t from 102.6m within a bigger 1m segment reading 33.5g/t. Wider results show a 10m hit at 3.2g/t gold from 43.9m and a 13m section grading 2.4g/t from 221m.
The company says the infill program is providing much-needed geological definition that is required for the stoping phase, while the extensional drilling has been important to define the limits of the mineralisation on any given level. Importantly, a significant amount of drilling has specifically targeted the Murchison Lodes, which were under-drilled in the initial resource drill-out.
Ora Banda Mining managing director Luke Creagh said: “The diamond drilling from the underground rig continues to define and extend the mineralisation at Riverina and further supports our view that this is very early days in unlocking a big mineralised and high-grade system. We remain on schedule to achieve commercial production in the June quarter, and this will mark a significant inflection point for the Company as it pivots away from a low-grade, open pit operation to a high-grade underground operation as the primary mill feed, resulting in increased production at lower costs.”
Earlier this month, the company identified its Sand King deposit, also near Kalgoorlie, as the preferred site for its second underground gold mine following significant high-grade results from its first-phase drill campaign.
If management makes the move to develop the deposit as a second underground operation to support Riverina, it predicts its 1.2 million tonnes per annum Davyhurst processing plant will subsequently be full of high-grade ore and production rates will increase substantially.
The continued progress at Riverina and unlocking the potential at Sand King are all part of Ora Banda’s “Drive to 100” project that aims to produce 100,000 ounces of gold per annum by next year – And with its operations making continued progress, it appears to be well on track to turn it into a reality.
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By Michael Philipps
