Task 3.2. – Processing of recovered slag metal fractions (M12-M18)

This task is dedicated to pre-concentration of the material streams by physical and physico-chemical separation technologies (mineral processing).
Several separation techniques will be tested on the representative investigated sample of slag. The separation techniques suggested in this task allow separation of liberated particles at μm level. The proposed innovative techniques will significantly increase the selectivity and recovery rate. Main objectives of this task are:

  1. to recover all metals from slags which can be recycled directly in the metallurgical processes;
  2. to concentrate “Strategic Metals” (SMs) as a feed material for leaching steps (WP4).

Magnetic separation will be tested on the crushed slag in dry and wet technologies, using low and high intensity magnetic separators at BRGM in order to recover metals droplets and metal-oxides containing minerals. Furthermore, an innovative dry multipolar magnetic separator, which is to date the most efficient magnetic separator, will be tested. This equipment was designed to create a strong agitation of particles that allows the release of non-magnetic particles, which are entrapped with the magnetic fraction, leading to the production of a magnetic fraction of a good quality. Finally, a new wet magnetic separation process with high intensity magnets (2Teslas) will be tested on fine particles of slags in water. BRGM expects to be able to recover some magnetic fine particles at micron level. This separation technique allows concentrating SMs in the non-magnetic fraction. Regarding the electrostatic separation experiment, electrostatic and tribo-electric separation will be tested on the non-magnetic fraction obtained from magnetic separation. The objective is to concentrate the mineral phases containing SMs. Gravity separation techniques will be investigated by wet shaking table technology and Falcon concentrator to recover the heavy metallic fraction.

All products obtained from different tests will be analysed by conventional analytical methods such as “X-Ray Fluorescence” (XRF), “Inductively Coupled Plasma-Atomic Emission Spectrometry” (ICP-AES), “X-Ray Diffraction” (XRD) and “Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy” (SEM/EDX) to evaluate the efficiency of the separation experiments. Optimization of separation procedure will lead to designing cost-effective processes to recover metallic particles (used directly as a raw material) and/or to concentrate metals (as oxides, spinels) suitable for further processing (WP4).


Phone: +33 4 77 42 01 23

Postal address
École des Mines de Saint-Étienne
158, cours Fauriel
CS 62362

F-42023 Saint-Étienne cedex 2