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Mine water from mines is pumped into the river
Photo: Roland Weihrauch / dpa
Something is happening underground under the Ruhr area.
Every day, thousands of cubic meters of water are pumped out of long-disused mines and fed into rivers.
It's an expensive job to last forever.
Because the pumps must not stand still.
Otherwise the polluted water from the coal mines would mix with drinking water in the former mining regions here and also on the Saar.
The mining group RAG spent around 290 million euros last year to keep the water in check.
But maybe the pit water can be used.
Volker Presser, professor at the Leibniz Institute for New Materials in Saarbrücken, wants to turn it into a raw material supplier.
Because on its way through the rock layers into the old mining tunnels, the rainwater enriches itself with many minerals.
In very small quantities, however, there is also valuable material - including lithium.
And that is what Presser wants to get out of the mining legacy.
The alkali metal lithium plays a crucial role in the production of rechargeable batteries and thus in electromobility, because the element is a core component of battery cells.
The more electric vehicles roll on the streets, the more lithium is needed.
The raw material has so far been completely imported, mainly from Australia and South America.
"The German economy is currently completely dependent on imports, since lithium is not extracted in the country," emphasizes Michael Schmidt from the German Raw Materials Agency (Dera).
Only a few battery cells are still being manufactured in Germany.
The production capacity is currently far less than ten gigawatt hours, says Schmidt.
The demand will increase by leaps and bounds.
The Chinese automotive supplier Svolt Energy Technology wants to set up its European production in Saarland.
And Tesla is planning to start mass production of battery cells on the site of its future plant near Berlin.
Based on previous announcements from the industry, raw materials expert Schmidt expects a production capacity in Germany of 70 to 240 gigawatt hours by 2025.
According to him, the lithium demand in Germany could then increase to up to 30,500 tons per year.
Presser wants to cover a small part of this requirement with its development.
"Our approach is to understand mine water as an eternity opportunity and to make it usable as valuable water through innovative technology," he says.
One liter of mine water only contains around 20 milligrams of lithium.
But in this case: the mass does it.
The scientist calculates that an estimated 1900 tons of lithium would be washed away with the mine water every year.
His test project with water from two former mines on the Saar is funded by the RAG Foundation, among others, which has to pay for the permanent follow-up costs of hard coal mining.
Electrodes fish lithium ions out of the water
Presser and his team run the mine water through a cell that contains two electrodes with different polarities.
Lithium and chlorine ions remain in the cell, while all other dissolved substances run off again with the mine water.
Fresh water then flows into the cell and collects lithium and chlorine in the form of lithium chloride.
This process is repeated several times so that the concentration of lithium chloride in the water continues to increase.
After the water has evaporated, it is finally in solid form.
The lithium chloride has to be further processed in order to obtain elemental lithium.
And what does it cost to extract lithium from mine water?
Presser cannot say that yet: "The project has just started - in two years we will be able to provide more information about optimal electrode materials and process parameters." In any case, the energy requirement should not be of great importance in terms of costs.
Since the electrical charge introduced is almost completely recovered, the process is largely energy-efficient, says Presser.
Lithium from mine water is not the only project to extract the raw material in Germany.
Deutsche Lithium plans to mine the light metal in the Ore Mountains soon.
The company suspects around 125,000 tons in the deposit near Zinnwald.
Managing director Armin Müller is following an ambitious schedule.
All approval procedures should be completed by 2022.
The construction of the mine and the attached factories could then be completed in the course of 2024, he reports.
Total investments of 159 million euros are required for the project.
Chance for lithium from Germany?
Is it worth the effort to extract lithium in Germany?
Michael Schmidt is careful: Lithium is not a geologically scarce raw material.
»We do not expect major deficits until 2023 or 2024.
But these can occur from 2025, globally and in Europe. «If production in Germany were economical compared to global supply, then something like this can make sense.
But the price development for lithium is difficult to predict.
There have been violent rashes in recent years.
At its peak, a ton of lithium carbonate cost around 15,600 euros in 2018, and at the beginning of 2021 only 5500 euros, reports Schmidt.
From 2025, however, prices can be expected to rise sharply.
There could be a chance for lithium, mined or dried in Germany.
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