63 Westgold Resources Limited Annual Report 2022 3. SIGNIFICANT ACCOUNTING JUDGEMENTS, ESTIMATES AND ASSUMPTIONS (CONTINUED) Significant judgements (continued) These assessments are undertaken for each individual mining operation based on the information available in the mine plan. The mine plans and, therefore, the identification of components, will vary between mines for a number of reasons. These include, but are not limited to, the type of commodity, the geological characteristics of the ore body, the geographical location and/or financial considerations. Judgement is also required to identify a suitable production measure to be used to allocate production stripping costs between inventory and any stripping activity asset(s) for each component. The Group considers that the ratio of the expected volume (e.g., in tonnes) of waste to be stripped for an expected volume (e.g., in tonnes) of ore to be mined for a specific component of the ore body, is the most suitable production measure. Furthermore, judgements and estimates are also used to apply the UOP method in determining the depreciable lives of the stripping activity asset(s). There are a number of uncertainties inherent in estimating the carrying value of mine properties and development and assumptions that are valid at the time of estimation may change significantly when new information becomes available. Changes in the forecast price of commodities, exchange rates, production costs or recovery rates may change the economic status of reserves and may ultimately, result in the requirement to restate the carrying value. Significant accounting estimates and assumptions Determination of mineral resources and ore reserves The determination of reserves impacts the accounting for asset carrying values, depreciation and amortisation rates and provisions for mine rehabilitation. The Group estimates its mineral resource and reserves in accordance with the Australian code for Reporting of Exploration Results, Mineral Resources and Ore Reserves 2012 (the JORC code). The information on mineral resources and ore reserves were prepared by or under the supervision of Competent Persons as defined in the JORC code. The amounts presented are based on the mineral resources and ore reserves determined under the JORC code. There are numerous uncertainties inherent in estimating mineral resources and ore reserves and assumptions that are valid at the time of estimation may change significantly when new information becomes available. Changes in the forecast prices of commodities, exchange rates, production costs or recovery rates may change the economic status of reserves and may ultimately, result in the reserves being restated. Mine rehabilitation provision The Group assesses its mine rehabilitation provision on an annual basis in accordance with the accounting policy stated in Note 2(j). In determining an appropriate level of provision consideration is given to the expected future costs to be incurred, the timing of those future costs (largely dependent on the life of mine) and the estimated level of inflation. The ultimate rehabilitation costs are uncertain, and cost estimates can vary in response to many factors, including estimates of the extent and costs of rehabilitation activities, technological changes, regulatory changes, timing, cost increases as compared to the inflation rate of 2.5% (2021: 2.2%), and changes in discount rates. The applicable discount rates are based on the expected life of mine for each operation. The expected timing of expenditure can also change, for example in response to changes in reserves or production rates. These uncertainties may result in future actual expenditure differing from the amounts currently provided. Therefore, significant estimates and assumptions are made in determining the provision for mine rehabilitation. As a result, there could be significant adjustments to the provisions established which would affect future financial result. The provision at reporting date represents management’s best estimate of the present value of the future rehabilitation costs required. Impairment of capitalised exploration and evaluation expenditure The future recoverability of capitalised exploration and evaluation expenditure is dependent on various factors, including whether the Group decides to exploit the related area interest itself or, if not, whether it successfully recovers the related exploration and evaluation asset through sale. Factors that could impact the future recoverability include the level of reserves and resources, future technological changes, which could impact the cost of mining, future legal changes (including changes to environmental restoration obligations) and changes to commodity prices. To the extent that capitalised exploration and evaluation expenditure is determined not to be recoverable in the future, profits and net assets will be reduced in the period in which this determination is made. In addition, exploration and evaluation expenditure is capitalised if activities in the area of interest have not yet reached a stage that permits a reasonable assessment of the existence or otherwise of economically recoverable reserves. To the extent it is determined in the future that this capitalised expenditure should be written off, profits and net assets will be reduced in the period in which this determination is made.
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