The mining operation for stage one will consist of an open pit mining campaign over five months from relatively shallow pits at the Wolverine, Gambit West, Gambit Central and Gambit East deposits.
A total 172,080t of mineralised material @ 1.19% TREO, containing 2,047,000kg TREO will be mined and stockpiled ready to be fed into the pilot plant. A 1.19% TREO grade is achieved as a result of higher grade ore near surface of the deposits. This will have minimal impact on the ore grade when the Project is developed at full scale.
Stage two: develop
Stage two involves completing several studies to increase the ore head grade, improve productivity and reduce mining costs, and increase ore reserve (ASX announcement 27 August 2015).
Northern Minerals will review the mine design and schedule to improve productivity and reduce forecast mining costs at the proposed Wolverine underground. On completion Northern Minerals is confident a cost reduction of 40% can be achieved through the elimination of paste fill by using sub level caving.
Further optimisation of the mining schedule will continue and may involve scheduling of the Wolverine underground from the base of the pit, re-evaluating the thickness and extraction of the Wolverine crown pillar and changing of the production sequence and layout.
There is potential to increase the TREO production rate 20% by targeting higher grade ore in the earlier stages. This involves increasing the DFS mill head grade from 0.66 to 0.80% by scheduling the current life of mine mill feed plan in a more favourable sequence. However, this will reduce the current 11 year life of mine, to seven to eight years. Exploration planning is well advanced, with exploration targets identified that have the potential to replace this high grade ore and extend the LOM (ASX announcement 23 March 2016)
Stage three: build full scale
During full scale production a total of 585,000tpa of ore will be mined through a combination of open pit and underground mining operations.
As per the DFS, the proposed mining operation will consist of four conventional open pits at Wolverine, Gambit, Gambit West and Area 5 deposits. With the Wolverine and Gambit West deposits progressing to underground operations.
Mining studies on the Wolverine deposit indicate that mining is likely to be concurrent from open pit and underground mines, with the underground starting from a separate boxcut near the base of the open pit depending on the studies in stage two. Preliminary mining studies on the Gambit West deposit indicate that mining is likely to progress underground from near the base of the open pit.