Magnetic　separation　has　been　proposed　to　greenly　separate　chalcopyrite　and　talc　several　decades　ago,　due　to　their　extremely　similar　floatability　of　minerals.　However,　this　approach　was　not　achieved　initially　due　to　the　inadequately　magnetic　induction　of　traditional　magnetic　separation,　and　fine　particle　size　of　chalcopyrite.　Currently,　the　development　of　highly　magnetic　induction　technology　provides　strong　feasibility　for　this　separation.　In　this　work,　we　employed　pulsating　high-gradient　magnetic　separation　(PHGMS)　with　highly　magnetic　induction　(1.8T)　to　separate　chalcopyrite　and　talc,　and　found　that　the　PHGMS　achieves　a　good　separation　of　chalcopyrite　from　talc.　But　the　chalcopyrite　recovery　decreased　with　the　decrease　of　its　particle　size,　and　thus　surface　oxidation　treatment　was　attempted　to　increase　the　magnetism　and　magnetic　capture　of　ultrafine　chalcopyrite.　As　a　result,　an　increment　of　approximately　10　%　was　observed　in　the　recovery　of　ultrafine　chalcopyrite　post-oxidation.　As　verified　by　the　superconducting　quantum　interference　device　measurements,　the　oxidized　ultrafine　chalcopyrite　exhibited　a　significant　increase　in　the　saturation　magnetisation　intensity,　remanent　magnetisation　and　coercivity　values.　Such　magnetism　enhancement　is　a　result　of　the　formation　of　paramagnetic　Fe(III)–O–OH　structures　on　the　oxidized　chalcopyrite　surface,　in　terms　of　X-ray　photoelectron　spectroscopy　and　Mössbauer　spectroscopy　investigations.　Furthermore,　the　density　functional　theory　revealed　that　the　formation　of　Fe(III)–O–OH　structures　caused　a　substantial　increase　in　the　magnetic　moments　of　iron　ions　in　antiferromagnetic　chalcopyrite.　These　findings　may　extend　the　application　of　magnetic　separation,　and　facilitate　the　flotation　of　ultrafine　chalcopyrite　from　other　minerals,　at　significantly　reduced　reagents　use,　and　productive　and　environmental　costs.　©　2023　The　Authors