Study on Sodium Modification of Inferior Ca-Based Bentonite by Suspension Method

Hunyuan Ca-based bentonite is one of large-type bentonite deposits in China, the reserve of which is more than 0.15 billion tons. However, they are not completely utilized in the pellet production. Process mineralogy investigation shows that the bentonite is a kind of typical Ca-bentonite (Ca-Bent). The sodium modification of the sample is studied by suspension method in this study. Results present the alkali coefficient K of modified Na-bentonite that is increased from 0.34 to 1.33, and the 2HWA, dilation, and colloid index are, respectively, increased to 601%, 32.4 mL/g and 87.6 mL/(3 g) under optimal conditions of Na2CO3 dosage 3.0%, pulp density 20%, sodium temperature 55°C, and sodium time 0.5 h. The XRD patterns show that d(001) of the sample bentonite is reduced from 1.5539 nm down to 1.2467 nm, and 2θ(001) of the sample bentonite is increased from 5.6875° to 7.0907°, indicating that the sample Ca-Bent is effectively modified into Na-Bent.