Applications of nuclear technology in mining

The application of technology to mining is not new; it was already being used in Australia in the 1980s when neutrons, X-rays, and radiotracers were used for different purposes.

Nowadays, there are many different techniques with different uses, among which the following stand out:

Use of nuclear probes

To determine the physics and chemistry of soils, such as borehole diagraphy or isotopic dating, to determine whether a stratum has favourable conditions to host minerals or fuels. Example: In coal mining, it allows the thickness of the coal seam to be determined, thus avoiding unproductive excavation of the rock.

Measurement of radioactivity with e.g. mass spectrometers

In uranium mining, the measurement of the radioactivity of the rock separates the gangue from the ore and determines the richness of the ore and is also used for the characterisation of bitumens and asphalts and has allowed the determination of the peculiarities of various archaeological sites.

Use of radiotracers or nucleonic probes

To increase the efficiency of the mining industry and thus increase its profitability. In mining operations, it is important to analyse large quantities of ore - between 1,000 and 10,000 tonnes per hour - as it passes along a conveyor belt. To make a quick and accurate analysis, engineers need a way to examine the ores for the elements they contain and how much of them they contain. In this regard, the use of neutrons, X-rays, or high-energy gamma rays, which are very penetrating, allow large quantities of material to be analysed quite accurately, so nuclear techniques are considered to be the most appropriate for this type of analysis.

Radiotracers and nucleonic probes are also used in the mining industries to improve product quality, optimise processes and save energy and materials.

The Commonwealth Scientific and Industrial Research Organisation (CSIRO) has developed nuclear techniques for, among other things, drilling, ore sorting, real-time detection and analysis.

It uses an analyser in which X-fluorescence is combined with X-ray diffraction to rapidly characterise minerals at parts-per-billion levels. This technique can detect key elements down to a level of around one hundred parts per billion and can measure quantities of valuable metals, such as gold, silver, uranium, and platinum group elements, and important contaminants, such as lead, mercury, and arsenic, at levels of a few grams per tonne or less. CSIRO has also developed a gamma activation analysis method that uses high-energy X-rays to measure ore samples in an automated system, without the need for laborious sample preparation or access to a nuclear reactor for neutron activation analysis. This technique is particularly effective in detecting gold contained in various types of samples.

World gold production is valued at billions of dollars per year and the high price of gold is mainly due to the high cost of extracting it. Gold is commercially mined at levels of grams per tonne and few analytical techniques are sensitive enough to measure metals accurately at such low levels. Gamma activation analysis uses high-powered X-rays to excite specific elements in the ore to activate trace amounts of gold in the sample. The technique applies to gold in any chemical or physical form and can be used to determine the amount of gold in solids, slurries, or liquids. By combining the latest developments in high-power X-ray sources and radiation detectors with advanced computer modelling, the CSIRO-developed analyser can detect levels of gold ten times lower than can be detected by other techniques. It can also detect very low levels in extremely small samples.

On the other hand, it should not be forgotten that research and development in this field continues and that the International Atomic Energy Agency (IAEA) is collaborating with CSIRO, among others, to develop radiometric methods for the exploration and extraction of minerals and metals, in the framework of which it is making its technology known to scientists all over the world.