Expected demand brings airborne survey system back to Africa

There are many mining and exploration opportunities in Southern Africa, with exploration work growing as more mining companies are focusing on the region, says South African airborne geophysics technology provider Spectrem Air GM Louis Polomé.

In the next ten years, remote sensing in terms of geophysics, will play a critical role in the exploration of Southern Africa, for which geological data is lacking, he tells Mining Weekly.

Subsequently, the company’s Spectrem Plus airborne electromagnetic survey system has returned to Africa, after 18 months in Australia, where there has been a boost in exploration spend.

For the rest of the year, Spectrem Air intends to focus on attaining work in Southern Africa and has secured contracts in South Africa and Zambia. Polomé also notes potential demand for Spectrem Air’s services in Botswana and Angola.

Historically, exploration of Southern Africa has been limited, especially under cover. In the past, geology was visible on the surface, allowing for faster decision-making by miners on the viability of exploring a deposit. However, as all these prospects have been discovered and exploited, explorers need to look under cover, which could involve penetrating 10 m to 500 m below surface.

Where geology has not been on the surface, the success rate of exploration has also been limited, owing to scarce geological data, says Polomé.

Airborne geophysical surveys use several different sensors to measure certain physical properties of rocks, such as density, magnetism and conductivity. Geophysical sensor technology has allowed for significant enhancements in terms of data resolution, the size of detectors, the sensitivity of the measurements and the ease of deployment.

Polomé notes that Spectrem Air has one of the most powerful airborne geophysics systems in the world, which can penetrate up to 800 m to 1 000 m below surface in favourable conditions. It also provides enhanced geological resolution while still maintaining a high level of detail in the near-surface geology.

Additionally, airborne geophysics is an economical way of selecting potential targets before spending capital on exploration and is nonintrusive by nature, he outlines.

“The alternative is to potentially misuse funds on poorly located drilling and testing in the hopes of finding an economically viable prospect.”

Polomé further emphasises the importance of building proper three-dimensional (3D) geological models using data derived from airborne geophysics to ensure that it is presented in a manner that is understood by everyone involved in developing a mining asset.

He highlights that greater advances have been made in data interpretation, compared with the technological advances of remote sensing, which are limited.

Increased computer power and software development have resulted in better processing of airborne geophysical data, while 3D models are being generated that closely resemble the true geology on the ground.

Exploration in Angola

Exploration in Africa, which is generally lagging compared with some places, such as Australia, Canada and South America, is improving in response to greater political stability in countries such as Angola, which has introduced new mining legislation that is making it a more attractive investment destination.

Angola has seen an uptick in exploration activity. Last year, President Joao Lourenco and the Angolan Council of Ministers enacted a new diamond marketing policy, which is among the measures being introduced to increase foreign direct investment in the country’s diamond sector.

“Angola has great potential, with large portions of the country yet to be properly explored,” says Polomé.

The success of Angola’s well-explored neighbouring countries holds promise for its mining potential, with Zambia known for copper and nickel mining, Botswana renowned for its diamonds and Namibia hosting significant diamonds and uranium projects, besides other commodities.

With diamonds being mined at diamond group Lucapa Diamond Company’s Lulo diamond mine, a 3 000 km2 concession in Angola’s Lunda Norte diamond heartland, Polomé states that the potential of discovering new diamond deposits is “very good”.

He also notes potential for nickel prospects in the south and copper in the east of Angola.

“We know more or less where to start looking, but it is a huge country and you need to target deposits effectively. Therefore, Spectrem Air expects significant demand for its airborne electromagnetic system to come from Angola in the next five years.”

He expects that mining companies will initially start exploration to expedite the development of economically viable prospects. Angola’s government should fill in the gaps at a later stage, although it has undertaken some mapping.