Improved and New Uses of Natural Radioactivity in Mineral Exploration and Processing

Measurement of natural radioactivity has been used in both a qualitative and a quantitative way in mineral exploration, particularly in the search for uranium. In the last five years, the Kernfysisch Versneller Instituut (KVI) and British Geological Survey (BGS) have designed, built and tested a new detector system that greatly improves quantitative applications in mineral exploration, especially on the seafloor and in the nearshore zone. The new system is an enhancement of an earlier BGS design. The major improvements comprise the use of a highly sensitive ?-ray detector, together with new data processing, from which concentrations of natural radionuclides may be deduced in real time. After laboratory analysis of samples, these concentrations can be converted into mineral percentages. Once the mineralogy of an area has been characterized, this conversion can also be done in real time. Thus far the system has mainly been used to map heavy-mineral concentrations in coastal subtidal and intertidal sediments. For such work the multi-sensor detector probe is towed on the seafloor and various parameters are recorded continuously. The probe contains, in addition to the gamma-ray detector, a water-pressure sensor (giving water depth) and an acoustic device to measure bottom roughness. The system, when used together with high-precision positioning systems such as D GPS, enables the production of detailed maps of bathymetry, bottom roughness, and seafloor radioactivity or mineral distribution. These maps allow mineral concentrations to be readily correlated with seabed topography and sediment type. In the same way, ?-ray detectors could be used advantageously during dredging operations to provide on-line assessment of the mineral content of the dredged sediment as well as to guide the direction of dredging. Additionally, the same technique could be used to monitor the subsequent fate of a dredge spoil after dumping on the seafloor. Natural radioactivity arising from potassium and the thorium and uranium decay series has potential use for the fast and reliable assessment of siliciclastic and phosphatic impurities in limestones. Detection of such impurities may preclude the use of the limestone for chemical or cement production. Apart from its use in exploration, the technique has significant potential in mineral processing, particularly of heavy minerals. It can be applied as on-line quality control in dry and wet separation processes and for process control, by using decisions based on the results to control valves and other instrumentation. In addition, it can also be used in environmental monitoring of waste arising from mineral extraction and processing. In conclusion, the technique described has a diversity of applications in exploration, mining and mineral processing.
Keywords: Radioactivity, KVI, BSG, Mineral exploration, Mineral Processing, Heavy-mineral concentration, On-line quality control
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Summary: A consistency-driven pairwise comparisons method for mineral potential assessment is presented, using a simplified case of volcanic-associated massive sulfide type deposits as an example. Geological, geochemical, and geophysical criteria are considered on two levels: local and regional. The local geological criteria are subdivided into stratigraphy, lithology, alteration and/or mineralization, and structure. The concept of geomerit index and a procedure for computing this index are introduced...
Publication: Exploration & Mining Geology
Author(s): WALDEMAR W. KOCZKODAJ: Centre in Mining and Mineral Exploration Research Laurentian University, Sudbury, Ontario, Canada P3E 2C6; WILLIAM O. MACKASEY: WOM Associates, 140 Crater Crescent, Sudbury, Ontario, P3E 5Y8
Keywords: Mineralogy, Geological criteria, Geochemical criteria, Geophysical criteria
Issue: 1
Volume: 6
Year: 1997
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Summary: The Sudbury Structure consists of three major components: 1) the Sudbury Basin; 2) the Sudbury Igneous Complex which surrounds the basin as an elliptical collar; and 3) an outer zone of shatter-coned and intensely brecciated footwall rocks. Although the Sudbury Event which formed the structure may be unique, the area has, in fact, been shaped by a series of tectonic, magmatic and mineralization events which can be considered in terms of two Wilson cycles of continental extension and closure....
Publication: Exploration & Mining Geology
Author(s): DON H. ROUSELL, HAROLD L. GIBSON: Mineral Exploration Research Centre Department of Earth Sciences, Laurentian University, Sudbury, Ontario, Canada P3E 2C6, and
IAN R. JONASSON: Mineral Deposit Division, Geological Survey of Canada 601 Booth Street, Ottawa, Ontario, Canada K1A 0E8
Keywords: Mineralization, Sudbury structure, Tectonic events, Magmatic events
Issue: 1
Volume: 6
Year: 1997
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Summary: The Navan zinc-lead ore deposit (70 million tonnes) is hosted principally (97%) by the Meath Formation (Lower Carboniferous, Courceyan, Navan Group), comprising a lower, mainly carbonate mudstone unit, the Stackallan Member, and an upper grainstone-dominated unit. The Stackallan Member, about 60 m thick, comprises about 35 peritidal cycles including an oolitic grainstone interval. Grainstones forming the upper part of the formation, about 150 m thick, comprise at least six shallowing-upward...
Publication: Exploration & Mining Geology
Author(s): GIANCARLO RIZZI and C.J.R. BRAITHWAITE Department of Geology and Applied Geology
University of Glasgow, G12 8QQ, Scotland
Keywords: Navan zinc-lead ore deposit, Meath Formation, Mudstone, Upper grainstone-dominated unit
Issue: 1
Volume: 6
Year: 1997
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Summary: The Amazon region is characterized by the development of deep chemical weathering represented by widespread lateritic covers and soils. Two distinct periods of laterite formation can be distinguished: mature laterites from the Eocene-Oligocene (and locally from the end of the Cretaceous), and immature laterites from the Pleistocene. The older laterites occur on plateau landscapes, and the younger ones on widespread hilly to flat lowlands. Both types show complete or truncated profiles,...
Publication: Exploration & Mining Geology
Author(s): MARCONDES LIMA COSTA: Geosciences Center, Federal University of Pará, C.P. 1611 66075-110, Belém-PA, Brazil.
Keywords: Amazon Region, Laterite formation, Mineral deposits.
Issue: 1
Volume: 6
Year: 1997
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