After decades of heavy mineral exploitation around the world, the number of 'easy' deposits which haven't already been developed has dropped to almost zero. As a result, mining exploration projects are forced to dig deeper, in more ways than one, to find feasible deposits.
At the same time, fluctuations in commodity prices have seen some resources (particularly rare earth metals) skyrocket in value, meaning many deposits previously deemed too complex in composition or challenging to reach are back on the table.
A great deal of time and money has been invested in better equipment for exploration and analysis to deal with these challenges. Here we look at the technology that is taking some of the hassle out of finding and evaluating new prospects, from lasers and spectrometers to satellite-assisted exploration programmes.
Laurentian University's laser ablation breakthrough
When analysing mineral samples, the more detail, the better. These details, after all, could be vital in identifying a potentially profitable trace metal in a sample. They could prove the difference between throwing away waste mining material and extracting valuable secondary resources. With this in mind, researchers at Laurentian University's Trace Element Mapping Facility for Geological Samples, in Ontario, Canada, have been developing a new ultraviolet laser ablation system which promises a clearer picture of samples, right down to their elemental composition.
Made possible by a grant of more than C$170,000 from the Canada Foundation for Innovation, the team's pioneering laser is a reaction to the perceived weaknesses of standard laser ablation spot analysis in spotting elemental distribution in samples. The new system vaporises samples into particles, which are then transported through a helium gas stream into a mass spectrometer for a full breakdown of the material's elemental make-up.
Dr Balz Kamber, professor of earth sciences at the university, told the Sudbury Mining Solutions Journal that the technology could help spot trace metals and elements, as well as reducing false conclusions about mineral deposits when analysing drill core samples. "If the results aren't interesting, you can switch off the drill and not have to wait six weeks for an assay," he said.
Brazil Gold's unified pattern processing
As minerals become more precious and difficult to find, mining companies will have to employ enhanced technology to cut costs and increase productivity, claimed Brazil Gold CEO Phillip Jennings. Therefore, the company set-up an agreement with Software Sciences (SSC) in September 2011 to explore the opportunities of unified pattern processing (UPP) for mining.
UPP is a patented pattern recognition technology which uses proprietary algorithms and artificial intelligence programmes to find relationships in organised or unorganised databases. The pattern can unearth data often missed by regular, 'model biases'.
Based on this basic algorithm, the two companies agreed to develop an application to simplify data processing for mineral exploration. "This allows us to gather, organise, fuse, process and analyze vast amounts of data quickly," said Jennings.
The technology's potential for the mining industry has been relatively unexplored, even though various applications of the technology have been used in different industry sectors, from military battlefield applications for the US Department of Defense (DOD) to marketing activities for international finance firms. "Semantic computing is a significant leap forward," explained Jennings. "It brings a new spectrum to predictive analysis. We believe that semantic computing can increase the efficacy of our search models."
Remote sensing: molecular resonance technology
Since the launch of the first satellite 40 years ago, imaging sensor technology has undergone rapid advancement, opening up huge potential to a number of industry sectors. Today, satellites are used by major mining companies for exploration of minerals - BHP Billiton, Newmont Mining and Anglo American are just a few to do so.
The key of using satellites for mineral discovery is resonance coupling, a natural phenomenon where wavelengths from exacting substances create a sympathetic reaction in identical, nearby materials. The resulting electromagnetic emissions expose a substance's location and chemical nature. Molecular resonance technology (MRT) instrumentation can locate that same exact substance underground or on the surface, using mineral samples to couple wavelengths.
Molecular structure patterns of gold, silver, platinum, zinc and copper are applied to satellite and airborne image downloads of the survey area, to identify field intensity and probability of the target substance existing at the surface or below hundreds of metres of overburden.
US-based Natural Resource Testing is one of the first companies to have used MRT for the exploration of worldwide mineral deposits. In 2009, the company set-up the satellite analysis resonance electron coupling (SATAREC) platform, combining this new form of remote sensing with proprietary resource concentration and signal strength measurements.
TerraSpec 4: near-infrared spectroscopy
Near-infrared spectroscopy has been gathering momentum in the mining industry, especially in the later stages of exploration, as a key technological enabler for faster and more precise mapping of mineral deposits, using high resolution spectra to separate indicator minerals from their worthless gangue counterparts.
Chief technology officer of mineral analysis technology specialist ASD Inc Dr. Brian Curtiss told Mining & Exploration in February that near-infrared equipment is vital for evaluating complex deposits. "If you have [a deposit] with variability, detailed spatial knowledge of ore properties is essential to minimise the risks when making a decision to develop a mine."
Curtiss's comments came just after ASD released the latest iteration of its TerraSpec range of portable mineral spectrometers, the TerraSpec 4. Made available in both hi-res (6nm resolution) and standard-res (10nm resolution) versions, the TerraSpec 4 line promises a twofold improvement in spectrum quality in the wavelengths that are relevant to mineral analysis (the SWIR region of 1,001-2,500nm), as well as faster data collection.
"The improved technology in the new TerraSpec line of mineral analyzers helps mineral exploration experts to more quickly map new deposits, and mining production organisations to better optimise their ore analysis, which aids in maximising metal recovery and mine longevity," said Curtiss, at the product's launch in January 2012.
X-ray fluorescence for speedy sampling
The use of X-ray fluorescence (XRF) is another technique which precludes the need to haul rock samples out of a mine and into a laboratory for time-consuming testing. With results available in a matter of moments, handheld XRF analysers are one option for speeding up exploration and on-site analysis process. XRF is commonly used to map deposits of base and precious metals, as well as rare earth elements and iron ore. Also, XRF analysers are often configurable to maximise their effectiveness in identifying different resources.
In the case of precious metals like gold and silver, portable XRF technology can be particularly useful, as XRF analysers are particularly sensitive to the geochemical pathfinder elements like arsenic copper and zinc, the presence of which often indicates nearby precious metal deposits. Limits of detection of XRF technology has also been boosted by the development of the silicon drift detector for handheld analysers, which allows high pulse throughput without any associated loss of accuracy.
SQUIDs - superconducting quantum interference devices
Detecting deeply buried, highly conductive massive sulphides, such as nickel, is a job best to be done by portable magnetic mineral exploration tools. One of the most powerful devices is LANDTEM, which uses highly sensitive magnetic sensors known as SQUIDs (superconducting quantum interference devices) to distinguish the ore from other conductive material.
Developed by a team of scientists at CSIRO in Australia, the device scooped a major mining industry award in 2011, the Australian Institute of Mining and Metallurgy Mineral Industry Operating Technique Award (MIOTA), for discovering the method for making the magnetic field sensor, which sits at the operational heart of the mineral exploration tool, using a high-temperature superconductor.
The initiative sparked interest in the industry, with mining companies BHP Billiton and Falconbridge heavily investing in development of the device. Since then, the technology has been licensed to Australian start-up company Outer-RIM Exploration Services. Ten systems have been built and deployed on four continents, to help unearth mineral deposits worth around $6bn, as CSIRO project leader Cathy Foley explained.
"LANDTEM represents a major innovation in our ability to unearth mineral deposits worth hundreds of million of dollars - deposits which may have been missed without this technology," she said.
By Elisabeth Fischer and Chris Lo