The last five years have seen Heron develop the Woodlawn Zinc-Copper Project from planning through to construction, commissioning and ramping up to commercial production. Construction activities commenced in September 2017 and were completed in the June 2019 quarter. Commissioning activities are completed and ramp-up proceeding with the first lead and zinc concentrate produced, transported to and shipped from Port Botany and Port Kembla in September and October. The first revenue from sales of concentrate was received in October 2019.
Heron awarded its contract for Underground Mining operations to Pybar Mining Services in early 2018 with preparatory work for mobilisation to site progressing to achieve a target of a third quarter 2018 start date.
At the end of the September quarter, access works to the underground had included final ground support to the box cut and the initial few metres of decline development advance that signified the commencement of the Woodlawn Underground Mine. The completion of the G2 drilling in the year has provided the opportunity to access earlier production for the first ore with mine planning work being revised to include this into the activity schedule.
The hydraulic mining operation at Heron’s Woodlawn site, alongside the underground operations that commenced in September 2018, will provide a second ore source to be processed through the new processing plant. The hydraulic mining operation covers the hydraulic monitors and the associated high-pressure water, reclaim and slurry transfer pumps.
The mining equipment supply, installation and commissioning contract for Heron’s Tailings Mine operations and specialist hydraulic mining services contract were awarded in May 2018 to National Pump & Energy and Paragon Tailings Australia respectively.
This combination of project partners brought together a complementary skill set of proven equipment supply and operational expertise to the tailings hydraulic mining operations at Heron’s Woodlawn Mine.
Hydraulic tailings retreatment preparations commenced in late December 2018, with infrastructure energised and water testing underway in December 2018. The commissioning activities involved the functional testing of equipment in the circuit including the commissioning of the trash screen and transfer pumps at the transfer station.
Two sources of ore from underground and tailings operations will be processed through the processing plant at Heron’s Woodlawn site to produce three concentrates – zinc, copper and lead.
One of the best examples of the advances made in sulphide processing technology and forming an integral component of the Woodlawn processing plant is the 3MW IsaMillTM.
The IsaMillTM is manufactured in Germany and first entered commercial use in 2000. It now represents proven technology, taking on grinding applications in a large number of global mining operations.
Having become available after Woodlawn’s former operations ceased in 1998, this piece of equipment provides the critical fine grinding capability to reduce the flotation feed to 30microns in size. Test work has demonstrated this sizing to be the most effective to liberate the different zinc, copper and lead sulphides, allowing for the highest recoveries to Heron’s base metal concentrates.
The Woodlawn site will produce three separate mineral concentrates – Zinc, Copper and Lead which will be exported via Port Kembla and Port Botany. The concentrate is moved between the mine site and the ports using a dedicated fleet of sealed containers.
The domestic logistics chain for Woodlawn concentrate export will comprise a small fleet of semi-trailers moving containers between Goulburn and the mine site, the use of a container storage facility in Goulburn, and the transfer of containers on to rail services running between Goulburn, Port Botany and Port Kembla.
At the conclusion of a tender process, Heron awarded its significant transportation services contract to Goulburn-based road and rail services provider, Crawfords Freightlines Pty Limited in June 2018.
Heron had initially planned to move the containers entirely by road haulage to the ports but in evaluating the opportunities for transportation, identified an attractive and cost-effective opportunity to utilise a rail yard in Goulburn (approximately 50km north of the mine site) to undertake a transfer from road to rail. Use of this intermodal has the advantages of reducing the annual road movements and eliminating truck movements through Goulburn.