20974 29Metals AR23 WEB V1 - Flipbook - Page 72
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29Metals 2023 Annual Report
Mineral Resources & Ore Reserves Estimates continued
Changes in the Mineral Resources estimates
Changes to the Golden Grove Mineral Resources es琀椀mates, rela琀椀ve to the last es琀椀mates (31 December 2022), are outlined below.
Material changes comprise:
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Mining deple琀椀on during the period 1 January 2023 to 31 December 2023, accoun琀椀ng for a 1.56Mt reduc琀椀on in the Golden Grove
Mineral Resources es琀椀mates. Reconciled mined tonnes for the corresponding period total 1.52Mt, producing a posi琀椀ve variance
of 0.04Mt.
Contras琀椀ng to previous repor琀椀ng years, deple琀椀on incorporated in the 2023 Golden Grove Mineral Resources es琀椀mates exceed the
reconciled mined tonnes for the period. This was due to the inclusion of non-recoverable shapes during the mining deple琀椀on process.
Prior to repor琀椀ng the 2023 Mineral Resources es琀椀mates, a substan琀椀al amount of work was invested into assessing the viability and
economics of several remnant mining stopes and scheduled stopes within the life-of-mine plan (the ‘LOM’). In total, forty Gossan Hill
and eight Scuddles stope designs were iden琀椀昀椀ed and 昀氀agged during this process, and subsequently ‘stamped’ as non-recoverable
during the deple琀椀on stage of repor琀椀ng, accoun琀椀ng for 246kt of the 1.56Mt mining deple琀椀on recorded.
When isolated and removed from the mining deple琀椀on, the 昀椀gure assigned to deple琀椀on for the period 1 January to 31 December
2023 drops to 1.32Mt. Mining deple琀椀on of 1.32Mt aligns with previous years and produces a nega琀椀ve variance of 0.21Mt when
comparing (‘non-recoverable’ corrected) mining deple琀椀on against reconciled mined tonnes.
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Primary contribu琀椀ng factors to this di昀昀erence are a琀琀ributed to barren post mineralisa琀椀on intrusives within designed mine shapes,
and to a lesser extent:
– below cut-o昀昀 material included within designed mine shapes; and
– external dilu琀椀on when mining adjacent to 昀椀lled stopes;
Drilling results – increase in Mineral Resources es琀椀mated tonnes of 0.35Mt, re昀氀ec琀椀ng analysis of data from drilling results and
associated geological interpreta琀椀ons;
Updated metallurgical modelling – 0.2Mt increase due to annual updates to the site recovery models. Speci昀椀cally, changes in assumed
recoveries in material with rela琀椀vely low copper or zinc to iron ra琀椀os; and
Economic cut-o昀昀 assump琀椀ons:
– 3.54Mt increase as a result of decrease to the foreign exchange (AUD/USD) applied (refer below); and
– 4.76Mt reduc琀椀on in Mineral Resources es琀椀mated tonnes as a result of increases to the net smelter return (‘NSR’) cut-o昀昀 value.
