Many types of detailed geological data are required to begin the evaluation of a mineral deposit - and the data must be accurate, detailed, complete and consistent. Studies of a mining project are typically conducted in three stages; scoping studies, pre-feasibility studies and feasibility studies. The basic reason for these is to decide whether the project has a potential to become profitable, with each stage being based on more and more detailed information about the mineralization and lower uncertainty of modelling results. Each study is followed by a decision whether to proceed further or not. Some feasibility studies are also called “bankable” if they also address a number of issues to which banks and credit lending institutes require an answer to before they finance a project.
The definition of a scoping study is that it is “a study that includes an economic analysis of the potential viability of mineral resources taken at an early stage of the project prior to the completion of a preliminary feasibility study”. On industry average basis, accuracy of the scoping study calculations is usually about 40%. When a successful scoping study has been finalised, it will be followed by the feasibility studies.
By the time a decision is made to proceed with a pre-feasibility study, a preliminary mineral resource report has been finalised and as well as an orebody model, demonstrating its shape, tons and grade. Feasibility studies include technical investigations, ore calculations, processing tests, environmental studies and permissions, assessments of market conditions – as well as an estimation of necessary investments and operational costs.
They involve the use of metrics and data specific to each project. 3 D-images are used to analyse how the holes have been drilled and what they reveal about the structure of the deposit – and what that implies for the future mining of the deposit. Geological data and interpretations form the basis of the entire evaluation process by delineating the mineralization, estimating the resource, and providing essential information for the mine and processing design. Accuracy of the feasibility study calculations is usually about 15 %.
Final feasibility study
The final feasibility study is usually based on the most attractive alternative for the project development as previously determined. The aim of the study is to remove all significant uncertainties and to present the relevant information with back up material in a concise and accessible way. The final feasibility study has a number of key objectives, including:
- to demonstrate within a reasonable confidence that the project can be constructed and operated in a technically sound and economically viable manner
- to provide a basis for detailed design and construction of the mine
- to enable the raising of finance for the project from banks or other sources
- to optimise the project for best use of the mineral, capital and human resources;
Other aspects to be considered include waste disposal and infrastructure requirements, such power and water supply as well as internal roads and plant infrastructure.