Example of the results of a flotation experiment at BRGM's Plat'Inn platform in Orléans on mineral raw materials and the circular economy (Loiret, 2023).
© BRGM - Didier Depoorter
Project background and objectives
In France, Europe and the rest of the world, driving the energy transition to low-carbon and renewable energies is leading to a growing need for critical metals, in particular lithium, tungsten, cobalt and nickel, extracted mainly from ores and mine tailings. The processes commonly used for recovering minerals and precious metals from the subsurface in an environmentally-friendly way are not efficient enough. It is therefore vital to improve the efficiency of these techniques in order to extract critical metals sustainably from primary sources, ores, and secondary sources, such as mine tailings, in line with the challenging needs of the ecological transition.
Flotation is a highly effective and widely used process for separating minerals of interest from their gangue (non-valuable minerals). The method is based on the use of reagents to modify the surface tension of the minerals, followed by the injection of air bubbles to recover the particles that have been rendered hydrophobic.
However, the flotation method is still not optimal, leading to a longer and more costly process, because of the difficulty in understanding and simulating the phenomena involved. This is because it involves heterogeneous materials, complex water chemistry, particles, bubbles and reagents interacting in complex flows, particularly for fine-grain materials, which are attracting growing interest.
At present, only atomic simulations and fluid dynamics simulations on the considerably larger scale of the reactor are taken into account, without any mechanistic understanding of the phenomena involved. The efficiency of flotation can be significantly improved by improving its simulation and, ultimately, the recovery of the minerals (and thus the metals). This is achieved by taking into account multi-physical and multi-scale phenomena, from the atomic to the reactor scale, and by understanding and mechanistically simulating the interaction forces between particles and their environment during transport.
Expected results
The MINFLOT project proposes a new and innovative multi-disciplinary and multi-scale approach that closely combines cutting-edge experiments and numerical modelling, from the atomic scale, where the key physico-chemical phenomena at interfaces occur, through the particle and microreactor scales, right up to the reactor scale.
Molecular dynamics simulations coupled with artificial intelligence will provide the input data to reproduce the flow and reactivity of particles in microreactors. These simulations will be validated by microfluidic and microreactor experiments.
Next, the flow and reactive transport at the larger scale of the reactor will be modelled, taking into account the results of smaller-scale simulations and measurements of mineral and metal recovery from innovative flotation experiments.
The expected advances will considerably improve the reliability of flotation simulations, as well as the efficiency and cost of the process. This will make it possible to process larger quantities of ore and mining waste in order to recover the metals that are essential to the ecological transition, such as tungsten and lithium.
Partners
The MINFLOT project won the first call for proposals under the exploratory PEPR programme ‘Sous-sol, bien commun’, a research programme focused on the responsible and sustainable use and exploitation of the subsurface, co-led by the BRGM and the CNRS and funded by the France 2030 investment plan.
This project brings together several partners :
- BRGM
- University of Lorraine
- CNRS
