Numerical simulation of agglomeration process dynamics of ferromagnetic mineral particles in a weak magnetic field

• Different forces on mineral particles in a magnetic field were calculated.
• The dynamic model of an agglomeration process was established and simulated.
• Magnetic potential energy conversion in the agglomeration process was calculated.
• Optimum times and efficient methods of agglomeration destruction were identified.

Based on the magnetic dipole theory of magnetic-field distribution, the forces acting on ferromagnetic mineral particles (FMMPs) in the magnetic separation process were calculated in detail and a macro-scale dynamic model of magnetic agglomeration (MA) of particle swarms was established. A calculation method toward the dynamic model was proposed, and the two-dimensional dynamic process of the interaction between FMMPs was simulated. Furthermore, the energy conversion of single mineral particles to magnetic chains (MCs) was also analyzed. The results show that magnetic dipole–dipole attraction (MDDA) acting on FMMPs was the primary force in the magnetic separation process, and the dynamic process of MC formation from single mineral particles was closely related to time, distance between particles, and the external magnetic-field orientation. For FMMPs arranged in chain structures oriented along the external magnetic field, the time required for FMMPs to form MCs was less than 50 ms. In addition, the optimum time for MC destruction was in the initial stages (less than 5 ms) of the MC-formation process; either removal of the permanent magnet or discontinuation of the excitation current was the most direct and efficient way to fragment MCs once formed.