EXPLORATION AND SAMPLING
Exploration levels are picking up and the suppliers are certainly ready for an upturn. John Chadwick looks at some of the new equipment and ideas
Exploration on the up
As we prepare International Mining Project News for publication every fortnight, it’ s been noticeable in recent months that there is more news to publish, more finance is available, older or delayed projects are being reexamined, many project optimisations are underway or have been completed, etc. In basic terms, things are looking brighter. Dozens of projects are covered in each issue of International Mining Project News- ask emma @ im-mining. com for subscription information.
In geophysics news we note that McPhar International has purchased Southern Exploration Surveys( SES) of Mossel Bay, South Africa. SES operates mainly in the southern African region, but also throughout Africa, offering airborne magnetic and radiometric surveys from acquisitions to final mapping and interpretation. SES has partnered with the Council for Geoscience for the last 10 years flying the national program for geophysical coverage.
McPhar is an airborne geophysical services company with offices in Canada, India and Singapore. It has been involved with airborne geophysical surveys for more than 60 years, providing surveys around the mining world.
Gedex says it“ delivers immense value by reducing risk of exploration, fast-tracking best prospects and ultimately accelerating discovery success rates by providing mass and density information at a quality that no other geophysical system can. We can transform resource discovery and development by illuminating previously undetectable economic
deposits. Our technology assists in detecting and defining important subsurface structures that, in combination with existing imaging techniques, create substantial value through costs savings and discoveries.
“ The Gedex high definition airborne gravity gradiometry data( HD-AGG™) is the most significant new technology capable of transforming resource discovery to be developed in over 20 years.”
The HD-AGG system measures minute changes in the strength and direction of the Earth’ s gravity field, and has a target performance level better than 1 Eotvos( E)/ √Hz, from a fixed wing aircraft.
The cost effective imaging derived from this data maps changes in the subsurface geology, ranging from the near surface features to depths in the orders of kilometres. This new exploration data can be used either alone or quantitatively integrated with other geophysical imaging technologies( seismic, electromagnetics, magnetics) as well as integrated with legacy data to detect buried resources that current generations of technology cannot effectively image. Integration with HD-AGG data also improves other technologies, enabling a new generation of risk mitigation best practices to evolve. As a result, Gedex can help clients to make faster discoveries with lower project time, cost and risk.
Geotech says the VTEM™ and ZTEM™ helicopter-borne electromagnetic systems are examples of active source( time-domain EM) and passive natural field( tipper AFMAG) systems that were primarily designed for deep
The Atlas Copco Diamec Smart 8 is a true deep hole exploration rig capable of taking cores at depths of up to 2,000 m and, according to the manufacturer, the most powerful core drilling equipment on the market
penetration mineral exploration applications. Yet, examples of successful VTEM and ZTEM applications for gold exploration also exist around the world. The VTEM system combines near surface high resolution resistivity imaging and deep penetration making it a low cost,“ flyto-drill” direct-detection and mapping tool. The ZTEM system uses worldwide sferic thunderstorm activity as its primary EM source field and, like other ground natural source EM methods, such as AMT, is capable of depths of investigation ranging from tens to thousands of metres. Coupling this with its sensitivity to weak lateral resistivity contrasts and the benefits of rapid 2D-3D inversion make it a powerful subsurface rapid reconnaissance geologic mapping tool.
Furthermore, J. M Legault and Geotech colleagues state in the paper Helicopter electromagnetic( VTEM AND ZTEM) applications for gold exploration that“ airborne electromagnetic methods have long been highly effective detection tools for base-metal and nickel deposits, due to their high conductivity contrast with the surrounding bedrock. Helicopter time-domain EM( HTEM) systems in particular have significantly improved penetration, sensitivity and positional accuracy that easily rival ground systems. In contrast, the physical properties normally associated with gold deposits provide significant challenges for
14 International Mining | FEBRUARY 2017