Viana do Bolo, a small municipality in Orense whose inhabitants continue to live off the fields and cattle, has just carved a niche on the world map of precious metals. A team led by the CSIC has managed to recover niobium and tantalum from the Penouta mine, two of the minerals most valued by the technology industry because with them they are manufactured from mobile phones and other computer devices to smart weapons. These are the first compounds of these raw materials to be synthesized in Spain, while Penouta is the first and only mine for their extraction in all of Europe.
Coltan is a relatively scarce mineral that contains niobium and tantalum and is one of the critical minerals for the European Union”, explains Felix Antonio Lopez, a CSIC researcher at the National Center for Metallurgical Research (CENIM). Tantalum is used mainly in the manufacture of capacitors, since it is capable, in its oxide form, of accumulating electrical charge very efficiently and releasing it when necessary in integrated circuits. With these minerals our smartphones, tablets, LED screens, video consoles are made. But not only that. They are also essential in the construction of tanks and other weapons for the military industry.
Lopez leads the ESTANNIO project, in collaboration with the Strategic Mineral and KROWN companies, which seeks to design processes to take advantage of the mining waste from Penouta, exploited in the past by the Rumasa company until its closure in 1982. These metals are critical for Europe because Until now, we had no deposits on the continent. It means that we can have an independent production “, says Lopez. The rapid increase in demand and the fact that its obtaining is linked to areas with child exploitation and armed conflicts, such as the Congo, make it essential to find an alternative that allows obtaining these minerals in conflict-free areas. “Anything that avoids these markets is geostrategic for Europe,” says the researcher.
CRITICAL FOR EUROPE
For a few months now, the Strategic Minerals company has been processing the ponds and slag heaps from the old mine and has begun the exploitation of the open-pit deposit, from which tin, tantalum, and niobium are extracted, as well as quartz, feldspar, and mica (granite). Tin was already exploited by the Romans, but “obtaining these critical metals is a great step for our country. It places us as an important producer worldwide and the only one in Europe “, says Felix Antonio Lopez. “And there is great concern in Europe for everything critical for us,” he adds.
From the minerals extracted in the mine, the CENIM team has developed a process that allows obtaining high purity tin and later, from the resulting slag, the niobium and tantalum compounds. Being two elements with high chemical affinity, their selective separation is complicated. To do this, the researchers first separate the tin and then apply a laborious process to obtain commercial salts of both niobium and tantalum, with a commercial quality that cannot be achieved with traditional methods.
In this way, they have obtained tin ingots with a purity of 95% and the first ones of niobium and tantalum salts with a commercial quality of up to 97% and 99%, respectively. Rare earth Investigators do not know how much coltan is in the mine, but they believe it is abundant. They estimate their useful life at 35 to 40 years, at least. Unlike other projects, the works have not produced social rejection, since their reactivation has generated employment in the municipality near the Portuguese border. Also, according to Strategic Minerals, there is no environmental risk either. Also, the researchers do not rule out that there are more similar mines yet to be discovered.
Within the ESTANNIO project, a commercial fusion plant to obtain tin will be installed in Salamanca and a hydrometallurgical pilot plant to obtain niobium and tantalum at CENIM. It is the first commercial farm to produce all three elements simultaneously. Also, the project will study the possible obtaining in these dumps of rare-earth metals, mainly cerium and lanthanum, with great economic value and also strategic for Europe. “They are essential to produce consumer goods such as LEDs or fluorescent,” says Lopez.