Magnetic separation of serpentinite mining residue as a precursor to mineral carbonation

• The magnetic separation of serpentinite mining residue was studied.
• The non-magnetic fraction can be used for mineral carbonation.
• The process removed about 71% of the iron impurities from the initial feed.
• The optimum magnetic field is 7.5 × 103 T.
• The concentration of iron oxide in the magnetic fraction is 79%.

Chrysotile mining in Québec has produced about 2 Gt of serpentinite residue. The present study investigates the magnetic separation of serpentinite residue from Québec to produce a non-magnetic feed stock for mineral carbonation. This study also scrutinizes the quality of the magnetic fraction recovered for use as a source of iron ore. The optimum conditions of magnetic separation were obtained with multiple pass approaches; at 40% initial pulp density and 7.5 × 10− 3 tesla (T) magnetic intensity with a mean particle size of 75 μm. The process removed about 71% of the iron impurities from the initial feed. The final non-magnetic fraction is rich in magnesium silicates with a low iron oxide concentration of 3.4%. The concentrations of iron oxide and silica in the final recovered magnetic fraction are 79% and 8.6%, respectively.