The 4,000tph North West Continental conveyor system is one of the key components of infrastructure required for the Tahmoor North expansion. The Continental conveyor system includes a 1600mm belt trunk conveyor, incorporating variable frequency drives, 2xMMD sizers and a dewatering station. Contracting company, Walter Construction Group, installed the system in joint venture with Continental Conveyor & Equipment.
The effect of the major works and consequent reduced production were anticipated and budgeted Austral said in its September quarter results. ROM production during the quarter was 71,000t, compared with 164,000t during the previous September.
Mining of longwall panel 19 in the south-western area of the Tahmoor lease was completed in mid July. The longwall was then relocated to panel 20, the new mining domain adjacent to Tahmoor North, some 4km away. Longwall equipment was modified to allow coal extraction to take place in the opposite direction from previous panels.
“This was a major engineering task and a critical component of the Tahmoor North expansion,” Austral said.
“The upgrade presented a significant challenge to mine management requiring completion within the short window of opportunity provided by the longwall changeover. As the major coal transport route was disabled during this process no longwall or development production was feasible.”
Austral said mine development for the quarter was restricted to 414 metres by several factors including the inability to haul coal throughout the conveyor installation period. Roadway development operations had to “grunch” through the final few hundred metres of panel 20 development.
“Development is now proceeding at considerably improved rates utilising the two new Joy 12CM30 continuous miners,” Austral said.
In seam gas drilling productivity improved in the quarter to 29,765m. Contract drilling company, Valley Longwall Drilling undertook additional exploration work in the Tahmoor North longwall domain to confirm reserves and geology.
Longwall production for the December quarter has since resumed on a seven day basis to maintain production budgets for the full year.
Austral expects the thicker Bulli seam in panel 20 to result in improved productivity for both longwall and continuous miner units as well as significantly improving washed coal yields.
“The first few weeks of operations have been encouraging with coking coal yields increased by over 5% on the historical average,” Austral said.
A final review of the Tahmoor North feasibility study was completed by International Mining Consultants. Austral said IMC valued the Tahmoor mine at $156 million based on the net present value of pre-tax cash flows discounted at 12% per year.
