By Dave Brown – Exclusive to Uranium Investing News
The exploration of uranium is similar to other forms of mineral prospecting in many regards with the exception of some specialized instruments for detecting the presence of radioactive isotopes. The use of remote sensing airborne detectors to prospect for radioactive minerals was first pioneered by a geophysicist working at Port Radium in 1943 named G.C. Ridland.
Exploring for uranium deposits today involves complex procedures because most of the remaining economic deposits reside in deep geological formations, and sophisticated technology is required to detect their existence. Technological deployments in uranium mining include geochemical analysis, geophysical surveys, satellite imagery and specialized computer programs.
In all stages of the geochemical and mineral exploration process, decisions are based upon site conditions, judgment, experience and relevant information. Quickly obtaining accurate exploration assay data to conduct mining operation decisions is one of the largest impediments to high productivity. Any improvement in the quality or efficiency in this data for rapid delineation of resource deposits and the in-depth, quantitative geochemical analysis of ore concentrations for mine mapping and grade control is critically important for mining operational functions.
Airborne gamma-ray spectrometry has now become a standard accepted technique for uranium prospecting with worldwide applications for geological mapping, mineral exploration & environmental monitoring. A deposit of uranium, discovered by geophysical techniques, is evaluated and sampled to determine the amounts of uranium materials that are extractable at specified costs from the deposit.
Laboratory work and chemical assays are still fundamental for resource estimation and especially relevant for sandstone style uranium deposits in the determination of disequilibrium. The use of calibrated down hole gamma logs is standard practice in industry and is routinely used in exploration and resource estimates. One aspect of growth in the exploration of uranium has seen an increase in the use of portable x-ray fluorescence (XRF) devices that can be used to get an on the spot reading, whilst the drill rig is still set up.
BMO Capital Markets Mining Analyst Ed Sterck discussed the technology with Uranium Investing News noting, “the XRF instruments are viewed as potentially useful but you have to be careful in how you use them. Using them in the field is possibly not the best way to employ them. The danger is when you just sample a very small area that just happens to be uranimite you will end up with a spectacular result.”
Experience in the field
The challenges seem to always focus around a strong survey design using the proper equipment for the expected model in terms of depth and geometry, optimal sampling intervals for high-quality mapping resolution and cost effectiveness. As always, it is incumbent upon the geophysicist to determine the physical property characteristics of a target and its host rock, and to conduct orientation surveys to quantitatively assess optimum survey parameters.
Prompt Fission Neutron (PFN) uranium logging system technology was significant in the detection and development of two of Australia’s largest uranium deposits, the Beverley mine and Four Mile deposits in South Australia. The technology was originally developed in the US and has been extensively improved and streamlined for practical routine borehole logging application. The PFN borehole logging tool is unique in that it directly measures the content of uranium in boreholes, overcoming the problem of disequilibrium which limits the interpretation of uranium concentrations using gamma logging tools. PFN tools are being used extensively in American and Australian projects to establish uranium grades at a number of uranium mines and exploration projects.
Through the employment of these technological resources geophysics has seen large scale improvements in mapping resolution and depth of penetration; uranium exploration and development projects, mining operations and investors have all benefited. Compared with the technological limitations during the previous boom, the modern geophysicist has a much upgraded suite of hardware and software, readily enabling quantitative field analyses and interpretation which can be leveraged in laboratory work creating even more efficient resource evaluation.