Rare earth elements (REEs) recovery and porous silica preparation from kaolinite

Kinetics of Natural Kaolinite as a Catalyst for Toluene Dry Reforming

“…Accordingly, a low heating rate (10°C/min) was used in the catalytic dry reforming experiments of toluene. These findings are comparable to the 15.35m 2 /g BET determined by (Ji et al, 2021) for the raw kaolinite (source: Ward's Science, USA) and 13.63m 2 /g determined by (Rosadi et al, 2020) for the pretreated and calcined kaolinite (source: Ranong, Thailand) at 500ºC. Running the dry reforming reaction at a low heating rate is a beneficial process since it provides the residence time required for reaction completion (Basu, 2010).…”

The effect of mechanical grinding and thermal treatment on the recovery of rare earth elements (REEs) from kaolinite

“…Besides the ion adsorption form, REEs also frequently associate with clays as accessory minerals (e.g., monazite and crandallite group minerals) [18][19][20]. The content and extractability of non-ion adsorbed REEs are lower than those of ion adsorbed REEs, therefore the recovery of REEs from non-ion adsorption clays has rarely been investigated [21]. Recently, the authors found that after thermal treatment of a kaolinite sample at 600 °C, the material was dehydroxylated and converted into metakaolinite, while the REEs existing in the metakaolinite were easily leached under relatively weakly acidic conditions, such as 0.01 mol/L HCl [21].…”

“…The content and extractability of non-ion adsorbed REEs are lower than those of ion adsorbed REEs, therefore the recovery of REEs from non-ion adsorption clays has rarely been investigated [21]. Recently, the authors found that after thermal treatment of a kaolinite sample at 600 °C, the material was dehydroxylated and converted into metakaolinite, while the REEs existing in the metakaolinite were easily leached under relatively weakly acidic conditions, such as 0.01 mol/L HCl [21]. The solid residue after REE leaching was prepared into porous silica with a surface area as high as 337 m 2 /g.…”

Preparation of monodisperse silica powder from acid residue after extracting alumina from coal gangue

“…When the concentration of sodium silicate is high, there are enough silicate monomers in the system to participate in the polymerization. With the increase of concentration, the number of silicate monomers is increasing, the nucleation phenomenon is intense, the crystallization process is difficult to control, and the agglomeration phenomenon is serious, so the specific surface area decreases 23 . The optimal concentration of sodium silicate was determined as 0.6 mol/L.…”