Thanks to research, what until now was just waste could become a precious source of rare earths. Here is the turning point of red mud
Can an industrial waste become a source of supply critical raw materials like them rare earths? Sometimes yes, this is the case of the “red mud” generated by aluminum productiona toxic waste that is becoming one of the most promising revolutions of the European ecological and energy transition.
Red muds: concentrate of rare earths
Before going into the merits of the production process of rare earths from aluminum waste, it is necessary to clarify where these “red muds” come from.
In fact, we don’t start from metallic aluminum scrap (like cans), but rather from bauxitethe mineral rock from which aluminum is obtained, and from its chemical waste, i.e. red mud, precisely.
When bauxite is processed in refineries to extract aluminum, almost all of the rare earths initially present in the rock do not dissolve. As a result, they concentrate and accumulate spontaneously in the waste sludge.
Compared to the starting rock, the red mud is therefore a “concentrate” of precious elements such as Neodymium, Praseodymium and Scandiumall critical materials for the high-tech and clean energy sectors.
The refining of rare earths
To free these metals trapped in the chemical structure of the mud, the leachingor an acid wash.
Instead of aggressive and highly polluting industrial acids, new technologies use biodegradable organic acidssuch as formic acid or citric acid. These substances selectively attack the chemical bonds of the mud, causing the rare earths to pass from the solid to the liquid state, dissolving them in an aqueous solution.
Meanwhile, a industrial microwave bombards the mixture with mud and acid. This targeted and ultra-rapid heating accelerates chemical reactions exponentially, with an almost total separation (close to 100%) of the rare earths occurring in very few minutesdrastically reducing energy consumption.
Once the rare earths are dissolved in the liquid, they are separated from the rest of the solution through filtration techniques. The liquid is treated to deposit the individual metals as pure salts or oxides.
From here, the metals obtained (Neodymium and Praseodymium) are ready to be melted and transformed into super magnets that power the engines of electric cars and the generators of wind turbines.
From the laboratory to production
In Europe, red sludge recycling is moving beyond the laboratory phase to become real pilot industrial plants. Greece is the leader thanks to the Mytilineos refinery which, within the European consortia RemovAL And NEMOalready extracts iron and scandium for aerospace.
In Italy the technological frontier is represented by CAMEBAXan excellent research project that maps Sardinian waste to demonstrate the feasibility of recovering rare earths and converting waste into construction geopolymers.
While actual industrial production has not yet started, these initiatives nevertheless play the essential role of trailblazers.
Production and geopolitical implications
However, it should be noted that absolute volumes of rare earth production would remain limited. The concentration of rare earths within the red mud, although higher than in the starting sedimentary rock, is still measured in parts per million (ppm) or in reduced percentages compared to the very rich Chinese or Scandinavian primary deposits.
This means that the recycling of bauxite residues will never be able to fully replace the enormous global mining supply chains, nor alone satisfy the exponential demand linked to the energy and ecological transition.
However, even an apparently small production takes on a profound strategic geopolitical value. China currently holds a quasi-monopoly on the refining of Scandium, Neodymium and Praseodymium, being able to exert strong commercial pressure or block exports to Western economies.
From this perspective, having a share of internal production, albeit marginal in terms of volumes, acts as a strategic shield against possible commercial blackmailhelping to redesign Europe’s geopolitical and energy independence.
Obtaining an autonomous and constant flow of critical raw materials guarantees a minimum basis of survival for the automotive electric and continental wind industrial supply chains.
