Effects of mechanical activation on physicochemical properties and alkaline leaching of boron concentrate

Boron concentrate is one of the major products created during the magnetic separation and gravity treatment of ludwigite. Nevertheless, achieving high B2O3 leaching efficiency in alkaline solution is difficult owing to its low B2O3 grade. This study proposes a mechanical activation (MA) method for the pretreatment of boron concentrate and describes the changes in B2O3 leaching rate of boron concentrate as a function of different ball-milling conditions. This work examines the changes in the physicochemical properties change of samples arising as a result of the MA process, in particular by PSD, BET, SEM, XRD, FTIR and TG-DSC analyses. The experimental results show that particle size, specific surface area, crystal structure, stability of chemical bonds, energy accumulation and the B2O3 leaching rate of boron concentrate are all significantly affected by the milling process. The B2O3 leaching rate exhibits an initial increase as the rotation speed and milling time are increased, and the optimum MA conditions are established as 500 rpm and 60 min. Under these conditions, the B2O3 leaching rate increases from 67.52% (unmilled sample) to 89.47%. The decrease in particle size from 13.2 μm to 6.2 μm and the increase in the BET specific surface area from 15.6 m2/g to 27.7 m2/g in samples milled for 60 min produces an increase in the contact area between the sample and the alkaline solution. Additionally, the increased extent of crystal structure amorphization and the weakening of chemical bonds increase the active points on the surface of sample particles or within their lattice structure, thereby facilitating the reaction with the alkaline medium. Finally, the increase in energy and dehydroxylation caused by the milling process increase the OH− absorption during the leaching process.