Mineral exploration
Mineral exploration is the process of looking for commercially viable concentrations of mineral ores to exploit. Mineral exploration is a much more organized, intensive and professional form of mineral prospecting.
There are five stages of mineral exploration:
Area selection
Selection of the best areas in mineral fields or geological regions is the most crucial step in mineral exploration. This makes it not only possible to find mineral ore deposits, but to find them easily, quickly and cheaply. Selection of an area requires the application of theories behind ore genesis, the knowledge of known ore occurrences and methods of their formation, to determine the possible areas where a particular ore deposit being sought may be found.
Most of the time, new styles of ore deposits may be found which expose opportunities to find look-alike deposits in rocks or places previously thought barren. This process may apply basin modeling, petrology, structural geology and a host of other disciplines to make predictions and draw parallels between the known ore deposits and their physical forms and the unknown potential of locating a look-alike within the chosen area.
Area selection is also influenced by the mineral being sought; areas which are prospective for iron may not be prospective for oil or other commodities exploration. Area selection may also be influenced by previous studies or finds, availability of infrastructure, tariff systems, or the financial and the taxation incentives of the individual country. The result of an area selection process is the pegging of tenements (exploration licenses).
Target generation
Target generation involves examination of the geology via geophysics, mapping and conducting comprehensive geochemical or geophysical testing of the surface and sub- surface geology. Areas covered by soil and platform cover may require drilling as a mechanism for generating targets.
Methods used for generating targets include:
• Geophysical methods: Geophysical instruments are used in gathering geological data which is used in the exploration of minerals. These instruments are used to check for variations in magnetism, gravity, electromagnetism, radioactivity and other numerous variables in a selected area. The most widespread method of gathering geophysical data is by flying airborne geophysics.
• Remote sensing: Aerial photography is used in examining mineral exploration agreements. It provides the explorer with information on the location of tracks, roads, vegetation cover and habitation across the whole region. Satellite based spectroscopes are used in mapping minerals and alteration directly where there is no vegetation cover.
• Geochemical methods: The presence of certain chemical elements may signify the presence of a certain mineral. Chemical analysis of plants and rocks may indicate the existence of an underground ore deposit.
Resource evaluation
This process is used to quantify the grade and tonnage of a mineral ore occurrence. Resource evaluation is achieved by drilling to locate the horizon and lode or strata where the mineral occurs. Resource estimation requires pattern drilling on a set grid or some form of geophysics. The main aim is to generate a density of drilling to satisfy the statutory and economic standards of an ore resource. The level of details required to generate this resource and the stage of extraction depends on the size of the deposit, availability of finance and the structure of the company involved. A scooping study is carried out at this stage to determine if there is enough ore to warrant extraction.
Reserve definition
Reserve definition is carried out to convert a mineral resource into an ore reserve. This process is more intensive and technical than resource evaluation and is aimed at quantifying the grade continuity and the tonnage of the ore. Reserve definition also includes the extractability and milling characteristics of the ore. During this process samples of the ore are taken for metallurgical test work, to check for crushability, floatability and other parameters. Reserve definition also involves geotechnical assessments and studies of rocks within and surrounding the ore deposit to determine the potential instabilities of the proposed underground or open pit mining methods. The ultimate aim of reserve definition process is to determine whether the ore deposit is economical to exploit or not.
Extraction
Extraction methods vary from one mineral to another. It’s the work of mining engineers to determine the safest, most efficient and most cost effective method to be used in the extraction of mineral (s) from the ore.
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