Sodium-modification of Ca-based bentonite via semidry process

In order to improve the quality of Hunyuan inferior Ca-based bentonite (Ca-Bent), semidry process was used to modify Ca-Bent into superior Na-based bentonite (Na-Bent). The factors affecting sodium-modification were investigated. The optimized experimental parameters are obtained as follows: Na₂CO₃ dosage 4.0%, ageing time 25 d, briquetting pressure 25 MPa and briquetting moisture 20%. Under the optimization conditions, the modified Na-Bent has a colloid value of 73.6 mL/(3g), dilation of 38 mL/g and water absorption in 2 h (2HWA) of 465%, respectively. The balling results indicate that the modified Na-Bent pellets have higher drop strength and compression strength than the Ca-Bent pellets.