Thalanga Zinc Project, Queensland, Australia


Thalanga

The Thalanga zinc project is located 60km south-west of the city of Charters Towers in Queensland, Australia. Red River Resources, the owner of the project, conducted a study to assess the viability of recommencing the project.

Announced in November 2015, the positive study results recommended restarting production at the Thalanga processing plant, which has been on care and maintenance since 2012.

The study estimated the project would require a pre-production capital of A$17.7m ($13.09m) and forecasts it to generate a life of mine (LoM) revenue of A$628m ($464.52m). The initial LoM is estimated to be more than five years, with a significant extension potential.

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 LoM.

Refurbishment works at the processing plant began in November 2016, while production is scheduled to start in the second half of 2017.

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 deposit is an advanced underground mine. The Far West deposit and Waterloo are located approximately 500m and 110km from the processing plant respectively. Waterloo deposit 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.

Thalnga zinc project reserves

As of June 2015 estimates, the Thalanga mine holds 2.4Mt of mineral resources, including 591,000t at the West 45 deposit, 1.1Mt at the Far West deposit and 707,000t at the Waterloo deposit. The ore reserve at the West 45 deposit is estimated to be 421,000t of proven reserves.

Mining and processing at Thalanga

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

The Far West and the Waterloo deposits will be mined using long hole stoping (LHS) method. The mined ore will be trucked to the processing plant for further processing.

Processing of the ore will take place in 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).

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

Major repair works at the plant include 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 multi-stream analyser (MSA).

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

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 will be supplied through Ergon 66kV network from the local power grid. The Waterloo deposit will be powered 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 will act as a back-up water source. Reverse osmosis water treatment facility will supply 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 to be developed includes 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.

Financing for the restart project

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