Drones, data analysis and tree needles provide clues about mineral resources

Mining has a problem similar to agriculture: its products are widely accepted. But the production itself is often criticized because of its impact on the environment and possible long-term damage.

The need for products such as metals, energy resources, stones and gravel and especially high-tech raw materials such as lithium or iridium is expected to increase. He will not be satisfied with recycling alone, as an analysis by the German Raw Materials Agency shows.

Minimally invasive search

The industry is therefore trying to become “greener” . New processes should reduce the effects and be more economical. The EU supports this, among other things in the project “New Exploration Technologies” (Next). With almost seven million euros in funding, partners from six countries have researched how the search for raw materials, exploration, can be made more environmentally friendly.

Drones and satellite data are becoming more important. Many expensive flights with helicopters or airplanes that carry geophysical probes can be replaced with the help of robotic devices. This was shown recently when the project results were presented.

In addition, alternative methods are becoming interesting to find ore bodies in a “minimally invasive” manner. Instead of taking samples with an excavator and drill, it may be sufficient to analyze plants, as an example from Finland shows.

It has long been known that certain elements depend on the chemical composition of the subsoil occur in clusters in plants. According to this principle, the company Radai from Oulu in Lapland was looking for a gold-cobalt complex. The experts tested the needles, twigs and bark of spruce, juniper and pine. All three species showed element concentrations that could indicate mineralization, reports Ari Saartenoja from Radai.

However, the ore is so deep that there is no direct gold enrichment in the plants above it. The experts therefore looked for chemical signatures that are typical for the edge zone of such ore bodies – and they found what they were looking for. This is borne out by boreholes that show significantly increased gold grades at depth in the affected areas. The method can therefore help to concentrate the following exploration work on promising areas and avoid expensive failures.

Saartenoja sees other important advantages of plant analysis: “It hardly affects the environment and it is fast. “Many samples could be obtained within one day. But it also has limits. The plants to be examined must be present in the entire study area in order to obtain comparable results. “The element content varies significantly between the individual species and tissue types,” he reports. In addition, other sources such as dust or surface water can interfere with the weak geochemical signal from the subsurface and must be taken into account.

A second look at unspectacular rock

More environmentally friendly exploration can also be achieved using big data methods. For example, a tin deposit was recently discovered in the Ore Mountains, thanks to artificial intelligence. Actually surprising, as the Ore Mountains are considered to be one of the best geologically researched regions in the world. Nevertheless, new finds are also possible here.

Geoscientists from Beak Consultants from Freiberg have merged and evaluated existing data on geology, chemistry and mineralization as part of the Next project. “You can imagine how many thematic cards are placed on top of each other,” explains Andreas Brosig, one of the experts involved. As a human observer one quickly loses the overview, but not a clever software.

After she has “learned” at known tin ore deposits which geological conditions are favorable for mineralization, she has the A mass of data identifies another region where an occurrence appears possible. It is about an area between Amtsberg and Bockau, southeast of Zwickau, in which a previously unknown type of mineralization occurs.

A gray slate comes to light there, says Brosig. “Unspectacular, it looks like in many places in the Ore Mountains”. But tests confirmed the suspicion: There is tin here, more precisely its oxide, referred to by miners as cassiterite or pewter stone. However, the grains are so small that they cannot be seen with the naked eye and have not been taken into account in previous raw material explorations.

The current find is due to another innovation. Instead of laboriously knocking samples out of the rock, taking them to the laboratory and analyzing them there, the geoscientists used a mobile X-ray fluorescence analyzer. The analytical technique has been known for a long time, but it required some space in the laboratories. Now it has “shrunk” and can be used in the field without breaking the rock mechanically.

“You hold the device against the rock and you know immediately whether it is worth further searching”, says Brosig. It was worth it, further examinations confirmed the findings. Electromagnetic measurements from drones are now to be used to clarify the extent of the deposit. In the next step, drilling would follow to determine the ore volume more precisely, and the new data would be compared with the old results, says Brosig. Only then does it make sense to decide on the economy of the occurrence and mining.

Information and personal presence

Often, raw material explorations, especially when dredging and drilling, lead to skepticism and sometimes protests. Local residents fear pollution and a loss of quality of life once mining begins. In the EU’s Next project, research was therefore carried out into what the acceptance of the population depends on.

In economically weaker regions such as Lapland, raw material exploration is viewed more positively, reports Karin Beland Lindahl from Luleå University of Technology in Sweden. “Because jobs and an expansion of the infrastructure are usually associated with a reduction.” In areas with land use conflicts and strong NGOs, skepticism dominates inform. However, if you look at the websites of the relevant companies, this is only implemented by a small part, at least in Finland, the researcher notes. In principle, modern, less invasive exploration methods would be well received and increase acceptance by companies, their studies show. “But other factors seem to be even more important,” says Beland Lindahl. “People appreciate it when those responsible are personally on site and explain what they are up to.”

In the tin province near Bockau, the people reacted “quite positively” to the exploration says Brosig. “Many feel connected to the mining industry.” If further explorations follow, communication with the population will also be intensified. His argument: The availability of tin and other metals is essential for the energy transition. European reservoirs could make a valuable contribution.

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