Magnetic　agglomeration　of　magnetic　particles　under　the　influence　of　magnetic　field　plays　a　vital　role　in　enhancing　the　separation　of　fine　magnetic　mineral　particles.　In　this　study,　the　major　forces　acting　on　weakly　magnetic　particles　and　the　ratio　between　forces　in　high-gradient　magnetic　separators　(HGMS)　are　investigated.　A　3D　high-gradient　magnetic　field　based　on　HGMS　was　simulated,　and　the　major　forces　(magnetic　force　Fm,　magnetic　agglomeration　force　Fmm,　and　gravity　G)　acting　on　weakly　magnetic　particles　were　calculated　in　the　form　of　Fm/Fmm,　Fm/G　by　finite　element　method　(FEM).　The　results　show　that　the　value　of　Fm/Fmm　became　lower　as　the　increase　of　magnetic　field　intensity　and　the　relative　permeability　of　particles,　higher　as　the　increase　of　the　magnetic　field　gradient,　the　particle　size　and　the　distance　between　particles.　However,　there　was　no　correlation　between　the　value　of　Fm/Fmm　and　the　density　of　the　magnetic　particles.　Furthermore,　the　value　of　Fm/G　was　inversely　proportional　to　the　density　of　the　particles　and　directly　proportional　to　the　relative　permeability　of　particles,　the　magnetic　field　intensity　and　magnetic　field　gradient.　Meanwhile,　Fm　was　at　least　190　times　greater　than　Fmm　in　any　case　and　Fm　was　far　bigger　than　G　in　most　cases,　indicating　that　the　magnetic　agglomeration　is　not　significant　in　HGMS　and　gravity　has　little　effect　on　high-gradient　magnetic　separation,　and　HGMS　are　destined　to　be　a　kind　of　high-efficiency　magnetic　separation　equipment.　©　2021