The processing plant at the Thalanga project is upgraded to restart mining operations. Image: courtesy of Red River Resources.
The West 45 deposit is an underground mine located 1.4km from Thalanga processing plant. Image: courtesy of Red River Resources.
The tailings storage facility provides water for plant operations. Image: courtesy of Red River Resources.

The Thalanga zinc project is located 60km south-west of the city of Charters Towers in Queensland, Australia.

The mine is estimated to produce 21,400t of zinc, 3,600t of copper, 5,000t of lead, 2,000oz of gold and 370,000oz of silver a year during the initial life of mine (LoM), which is estimated to be more than five years, with a significant extension potential.

Production of metal concentrates commenced in September 2017. Red River Resources made the first shipment of 5,500 wet metric tonnes of zinc concentrate and also delivered first copper concentrate to Glencore International from the Thalanga mine in January 2018.

Thalanga Zinc project history

The Thalanga deposit was first discovered in 1975 with open-pit and underground mining commencing in 1989 and 1991 respectively and continuing up to 1998. Regular operations at the processing plant ceased in 1998 and the facility was converted from a Cu-Pb-Zn (polymetallic) circuit to a copper only circuit.

The plant served the neighbouring Highway Reward deposit by treating 3.8Mt of copper ore from 1998 to 2005. In 2006, the Thalanga project was acquired by Kagara, which used it to process approximately 1.5Mt of copper from the Balcooma deposit.

The plant was converted back into a poly-metallic circuit in 2010 and placed on care and maintenance in 2012, with it then being acquired by Red River in 2014.

Thalanga project details

The Thalanga project comprises five deposits, including West 45, Far West, Waterloo, Orient and Liontown, with the first three being mined according to the restart study.

Located 1.4km from the processing plant, West 45 is an advanced underground mine. The Far West deposit and Waterloo are located approximately 500m and 110km from the processing plant respectively. Waterloo holds the highest grade deposit with a total mineral resource of 707,000t grading 19.1% zinc.

Geology and mineralisation at Thalanga mine

Thalanga comprises the biggest pyritic body of copper-lead-zinc-silver mineralisation within the Mount Windsor Volcanics.

Mineralisation at the deposit is hosted in stratiform sulphide lenses and stringer zones developed within quartz eye volcanoclastics located between a dacite hanging wall and a rhyolite footwall.

Thalanga zinc project reserves

As of December 2017 estimates, the Thalanga mine holds 2.28Mt of mineral resources, including 582,000t at the West 45 deposit and 1.693Mt at the Far West deposit.

The proven and probable ore reserves at the West 45 deposit are estimated to be 567,000t, and the Far West deposit is estimated to contain 1.53Mt.

Mining and processing at Thalanga

The West 45 mine was historically mined using the box-cut method, which will also be used for future developments.

The long hole stoping (LHS) method is applied at the Far West and the Waterloo deposits, with the mined ore trucked to the processing plant.

Development and mining activities recommenced at the West 45 deposit, the first to be mined at Thalanga, in April 2017.

Processing of the ore is undertaken at the existing plant on the project site. The processing plant has a three-stage crushing circuit, primary and secondary ball mill circuit, a regrind plant, differential copper-lead-zinc flotation circuits, concentrate thickening and filtration chamber and concentrate storage facility. Furthermore, facilities are available for blending and transport, and disposal of tailings to tailings storage facility (TSF).

Refurbishment works of the processing plant began in November 2016. Recommencement of the Thalanga processing plant was estimated to have a pre-production capital of A$17.7m ($13.09m) and forecasted to generate a LoM revenue of A$628m ($464.52m).

The plant was refurbished to produce saleable copper, lead and zinc concentrates with a throughput of 650,000t/y.

Major repair works at the plant included refurbishment of larox vertical concentrate filter press, ball mill and crushing circuit, electrical equipment and instrumentation, replacement/repair of all pumps and electrical motors, and refurbishment and commissioning of a multi-stream analyser (MSA).

“The processing plant at Thalanga is refurbished to produce saleable copper, lead and zinc concentrate with a throughput of 650,000t/y.”

Offtake of concentrates produced at Thalanga

Red River Resources entered a three-year off-take agreement with Glencore in June 2017 for the sale of copper produced at Thalanga.

In August 2017, the company also entered a similar agreement with Trafigura for the offtake of zinc and lead concentrates.

Infrastructure at the copper-lead-zinc mine

The project site is well connected to all the state and federal roads, including Flinders Highway (A6) and Gregory Developmental Road (A7) through company-owned all-weather, sealed access roads.

Power to the project site and other deposits is supplied through Ergon 66kV network from the local power grid. The Waterloo deposit is powered by using a diesel generator station.

The on-site tailings storage facility and the unused Vomacka open-pit currently have sufficient water capacity for the plant operations. An existing bore field located 9km from the project site is acting as a back-up water source. Reverse osmosis water treatment facility is supplying drinking water.

Other infrastructure at the project site include an existing tailings storage facility (TSF), waste rock dumps, two evaporation ponds, fuel storage tanks, dispenser and hydrocarbons storage and waste disposal area.

Additional infrastructure facilities include administration, mining and maintenance offices, workshops, process plant offices, metallurgical laboratory buildings and other ancillary facilities.

Contractors involved

Mining One Consultants conducted the geological review and mining review of the three deposits and resource estimation process as part of the restart study.

AMC Consultants provided geotechnical design input and advice for the project.

PYBAR Mining Services was awarded the mining contract for the West 45 underground deposit.

Financing for the restart project

Red River received commitments to raise A$30m through a two-tranche placement in December 2016. Proceeds from the placement, along with the company’s existing cash balance of $10m, are being used to fund the restarting of the project.