The feasibility studies for mineral exploration aim at the evaluation of economic mineral deposits to know whether profitable mining is possible. The approach to feasibility study should be on economical bias. As far as mineral exploration is concerned there are three stages as feasibility, detailed project planning and quality control. The estimation of mineral reserves is the first consideration of feasibility studies. Only the regions containing the mineral resources should be subjected to feasibility studies.
The quantum and nature of tasks are variable depending on extent, nature of deposits, the nature of assignment, etc. The feasibility report should ultimately provide investment analysis. The preparation of feasibility report involves the work of inter disciplinary interests.
Mineral deposits should be taken up for evaluation only when the preliminary prospecting has proved the possible occurrence of economic deposits. Generally, the preliminary prospecting includes, geological reconnaissance, mapping on scales of 1: 100 000 or 1: 50 000, geochemical and geophysical surveys, some test drilling of the geophysical and geochemical anomalies, and finally, the laboratory tests such as chemical and petrological.
For most of the deposits, the feasibility studies can be done in two phases but for non ferrous and precious metals, they involve three stages as mentioned below.
The first phase might indicate the desirability of going ahead for the remaining phases.
The following tasks are involved in first phase:
1. Development of infrastructure such as approach roads, camping facilities, construction of godown, magazines for explosives, electrical lines, installation of generator, etc.
2. Depending on the extent of area under investigation, geological maps on scales of 1:1000 or 1: 500 should be prepared. The contour intervals may be 3 meters or 5 meters. Topographic maps are also useful.
3. Detailed geophysical and geochemical surveys such as radiometric surveys on closely spaced grids should be done. Drilling can be done at intervals of 300 meters to 500 meters.
4. Chemical, petrological, and spectrographic analysis can be done to know about valuable minerals.
5. Geological cross sections should be prepared based on bore hole data. They show the attitude of mineralization.
The more intensive exploratory work should be carried out in the selected blocks or block during the second phase. The major task involved in this stage is the closely spaced drilling at intervals of 50 to 100 meters. Systematic sampling, testing of split core samples, bulk samples, etc to prepare beneficiation, and metallurgical reports.
Estimation of the profitability profile is one of the most important objectives of the final phase. The major tasks during this stage include, intensive under ground exploratory mining to know the continuity of mineral deposit, under ground drilling to ascertain the extent of mineralization, estimation of level or bench wise reserves, preparation of geological plans, preparation of isocore or isopach maps, structure contour plan, beneficiation and metallurgical tests, and finalising the process flow sheet.
According to experts, a minimum of 30% reserves should be brought into A and B categories before any mineral deposit is considered for exploitation.
