Enhanced grindability of bastnaesite ore by ex-situ CO₂ treatment under the partial pressure of 0-100 psi

High grinding energy consumption has long constrained the sustainable development of mineral processing. This study introduces an innovative technology that employs ex-situ CO₂ treatment to enhance the grindability of bastnaesite ore. The grinding aid effect was evaluated under CO₂ partial pressures ranging from 0 psi to 100 psi using particle size distribution and the Bond work index (BWI), while the underlying mechanism was elucidated with various characterization techniques including inductively coupled plasma (ICP), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET). The optimal grinding aid effect was achieved at 100 psi partial pressure, 50% slurry concentration, and 3 h reaction duration. Correspondingly, the P80 of the grinding product decreased from 81.76 μm to 72.73 μm and the BWI of bastnaesite ore decreased from 6.96 kW·h/t to 6.30 kW·h/t, a reduction of 9.48%. The grinding aid effect primarily resulted from the transformation of sparingly soluble carbonates like calcite and dolomite into more soluble bicarbonates, which created substantial cracks and pores, thereby reducing the ore's hardness and improving its grindability. By significantly saving grinding energy consumption while delivering environmental benefits, this technology exhibits great promise for further optimization and widespread adoption.. Authors: Wang, Xu [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)]; Wang, Yi [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)]; Zhang, Wencai [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)]. DOE Contract: AR0001713. Subjects: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES; Bastnaesite ore; CarbonateCracks and pores; Dissolution; Ex-situ CO2 treatment; Grindability