Whitehaven Coal provides coal resources and coal reserves update
Published by Jessica Casey,
Editor
World Coal,
Whitehaven Coal Ltd has updated its managed coal resources and coal reserves under the JORC Code 2012.
Key changes from the previous (August 2020) coal resources and coal reserves statements are as follows:
- Maiden reserve statement for Winchester South in December 2020.
- Xoal resources for Maules Creek, Narrabri North, Tarrawonga and Werris Creek decreased due to mining depletion only.
- Recoverable coal reserves and marketable coal reserves at Tarrawonga, Werris Creek and Maules Creek decreased due to mining depletion only.
- Revisions have been made to reserves for the Narrabri North (ML1609) and Narrabri South (EL6243/Stage 3 Extension Project), primarily reflecting changes to mine planning, in line with WHC’s strategy of focusing production from these assets on higher quality coal to meet market demand. The revisions also reflect mining depletion.
- Narrabri North has been revised from 102 million t to 72 million t for recoverable reserve and from 97.8 million t to 70.7 million t for marketable reserve.
- Narrabri South has been revised from 121 million t to 98 million t for recoverable reserve, and from 114 million t to 96 million t for marketable reserve.
Narrabri Coal has elevated proved recoverable coal reserves from 97 million t in 2020 to 157 million t in 2021. Proven marketable coal reserves have been elevated from 94 million t in 2020 to 157 million t in 2021. This elevated level of confidence has been achieved as a result of detailed work undertaken and completed as part of the feasibility process associated with Stage 3.
The current Narrabri mine life is expected to continue until 2044.
Coal resources and reserves for active mining areas are as the 31 March 2021. Production for the quarter ended 30 June 2021 is detailed in the June 2021 quarterly report.
Narrabri Complex: Change in reserve
In late 2020 a feasibility study was conducted for the extension of the mine into EL6243 known as Narrabri South. The study included an assessment of the southern portion of ML1609 known as Narrabri North and how the mine production plan would progress.
Narrabri North: Reconciliation
A net decrease of 30 million t of underground coal reserves was reported, due mostly to the following:
Mining activity
Narrabri North mined approximately 6.3 million t during the reporting period.
Mine plan changes
Recent exploration activity and mine plan optimisation completed as part of the feasibility study resulted in changes in the mine layout. The changes to the mine plan are detailed as follows:
- Shortening of LW209 to avoid thinning of the Hoskissons seam.
- A step around in LW110 to avoid identified faulting.
- A change from planned longwall extraction to continuous miner extraction for LW201 and LW202.
- Shortening of LW203 and LW204 to avoid identified faulting.
A value optimisation exercise completed for the feasibility study showed that the highest realised value is achieved by mining only within the HSK2 ply and forgoing the poorer quality coal in the upper plies of the Hoskissons seam. The reduced height is supported by the planned purchase of reduced height mining equipment.
The decrease in underground marketable coal reserves of 27.1 million t is consistent with the decrease in the run of mine (ROM) coal reserves. The total marketable coal reserves of 71 million t is determined using the updated processing logic and yield assumptions.
Narrabri South
A net decrease of 23 million t of underground coal reserves was reported due mostly to:
Mine plan changes
Recent exploration activity and mine plan optimisation completed as part of the feasibility study resulted in changes in the mine layout. The changes to the mine plan are detailed as follows:
- Shortening of LW307 to avoid thinning of the Hoskissons seam.
- A re-alignment of the central Mains between the 200 series and the 300 series longwall panels.
- Shortening of LW304 to avoid subsidence of an environmentally sensitive area.
- Lengthening of LW308 due to availability of reduced height equipment.
Change in the working section assumptions
Narrabri South was also assessed as part of the value optimisation exercise completed for the feasibility study which showed that the highest realised value is achieved by mining only within the HSK2 ply and forgoing the poorer quality coal in the upper plies of the Hoskissons seam. The reduced height is supported by the planned purchase of reduced height mining equipment.
The decrease in underground marketable coal reserves of 18 million t is generally consistent with the decrease in ROM coal reserves. The exception is a change in yield assumptions based on modelling completed for the feasibility study where the yield increased from 95% to approximately 99%. This resulted in an increase to the marketable reserves of 5 million t.
Read the article online at: https://www.worldcoal.com/coal/27082021/whitehaven-coal-provides-coal-resources-and-coal-reserves-update/
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