The EU's green revolution has increased demand for rare earth metals used in wind turbines and electric cars. An Estonian biomining technology based on micro-organisms has been developed to extract rare earth metals from industrial waste and helps eliminate environmental pollutants.
The transition of European economies to digital, highly energy-efficient and environmentally friendly conscious economies has boosted demand for rare-earth metals.
"There has been much discussion about the importance of offshore wind turbines and electric vehicles, but the cost shouldn't be another mine somewhere in the Indonesian jungle used for the extraction of metals required for the green turn, which is also polluting the groundwater," said Priit Jõers, associate professor of biochemistry at the University of Tartu (TÜ) and head of research at BiotaTec.
A car that runs on electricity, for example, requires six times as many different metals as a conventional car that runs on fossil fuels. Offshore wind turbine generators require specific metals as well. Wind turbine motors are powered by permanent magnets that are composed of alloys of rare-earth metals, for instance, such as neodymium.
"Because catalysts made of precious metals such as platinum are required for hydrogen production, their demand is increasing as well," said Jõers. "In addition, demand for lithium, which is used in batteries, is expected to increase tenfold."
Reducing dependence on China and other non-EU sourcing
Historically, these metals have been extracted from mined ores. These deposits are highly concentrated outside the EU, with locations primarily in China, Turkey and South Africa.
The European Commission estimates that the EU will need up to 18 times more lithium and five times more cobalt, used in electric car batteries and energy storage, in 2030.
"For the EU, however, this poses a geopolitical risk, since it is theoretically possible that China will cease selling us these metals at some point, while we are committed to shifting energy production to renewable sources without having our own necessary resources," says Jõers.
Many important metals, such as those in the platinum group, have been primarily sourced from South Africa and Russia.
"This has highlighted the importance of having our own resources so that we are not reliant on other [non-EU] countries. Paying no attention to it makes little strategic sense, especially in light of Russia's actions," Jõers said.
It is also important to realize that the refining of metals needed for the green transition traditionally involves high temperatures and strong inorganic acids, he continued.
"All of these factors result in a high energy demand and significant carbon footprint," Jõers said.
Prioritizing green solutions
In the EU, there is a trend toward taxing environmentally hazardous technology in order to encourage businesses to invest in clean solutions. As a result, a number of once-profitable refineries have closed as they are no longer profitable in the new tax climate.
"In other words, there is pressure for an economically viable and environmentally friendly technology," Jõers said.
He and his colleagues at BiotaTec have spent more than a decade perfecting the bioleaching or bioremediation technique — an environmentally friendly and cost-effective technology for processing low-grade and complex ores.
The company has now built an industrial-scale prototype of a bio-mining reactor.
"The rationale for this approach is based on the fact that we are using micro-organisms [such as bacteria, archae, fungi or plants, which use metals to support their energy needs]," Jõers said.
"This technique does not require high temperatures and has significantly lower energy requirements," he highlighted. "It produces almost no toxic waste, resulting in an environmental footprint that is tens of times lower than traditional processes."
Bio-mining utilizes industrial waste
Bio-mining is used to extract metals from low-metal ores, industrial byproducts of metal ore processing as well as obsolete electronics ,or e-scrap.
"When you extract aluminum from aluminum ore, for example, you get red chip residue with a high iron content that also contains other metals such as scandium, which is used in steel alloys," Jõers explained. "Using the bioleaching technique, it's possible to extract fuseful and important raw elements rom this so-called 'red mud.'"
Bioleaching could also be used to extract toxic substances such as arsenic from the red mud as well.
Phosphorus production surpluses, for example, which contain a number of essential earth metals and weak radioactive chemicals, can be treated similarly.
"The material that remains after bioleaching is clean and can be used to build roads and houses," Jõers added.
"In other words, bioleaching facilitates the transformation of troublesome industrial waste into a supply of critical raw elements," he noted. "The gold content of old mobile phones is between 200 and 300 grams per ton, which means it is a very rich resource as well."
Bioleaching employs microorganisms to transform solid metal into a water-soluble state, which allows for the extraction of pure metals.
"Although this methodology has been used since the 1960s, its industrial application has been very limited," Jõers explained. "It is used in copper mining in Chile and gold mining in South Africa, for instance. Bioleaching is done on a smaller scale in Finland as well."
Developing time-saving bioleaching technology
Previously, bioleaching technology was not widely used due to the high costs associated with it. However, in the context of the green revolution, traditional techniques have become cost prohibitive, at the same time as bioleaching has become more cost-effective. Jõers said that bioleaching is much more environmentally friendly than conventional approaches.
It also causes fewer problems for local communities.
"There is a significant difference between mining with roaring stacks on one hand and metal cylinders with faint fumes on the other," he highlighted.
Long reaction times have thus far slowed the development of biomining. In most cases, it takes weeks to months to separate the metals from the ore.
"Reducing this time is one of BiotaTec's significant advances in this field of research," he said. "We've been able to cut it to days or even hours by using specific methods."
According to the Estonian researcher, the potential future of industrial-scale biomining depends in part on whether the policy of taxing environmentally harmful practices will remain.
"I believe this [biomining] technology will be commonplace in five years," Jõers said. "Consumers may not notice the difference, but electric cars purchased in the near future will contain bio-extracted metals."
BiotaTec is developing and licensing next-generation rapid biomining solutions for critical raw materials (CRMs) from low-grade ores, tailings and wastes. Critical raw materials are indispensable in solar panels, wind turbines, electric vehicles as well as energy-efficient lighting.
Editor: Kristina Kersa