Containing bauxite liquor using bentonite-polymer composite geosynthetic clay liners

Abstract

Experiments were conducted to evaluate the hydraulic conductivity of geosynthetic clay liners (GCLs) to bauxite liquor from aluminum refining. Tests were conducted with a GCL containing conventional sodium-bentonite (Na-B) and one GCLs containing a bentonite-polymer composite. B-P has polymer loading of 6.8%. Hydraulic conductivity tests were conducted on the GCLs with bauxite liquor in flexible-wall permeameters following procedures in ASTM D6766. The bauxite liquor used in the experiments has pH 13 and ionic strength = 700 mM. Hydraulic conductivity of the Na-B GCL increased to approximately 10 −7 m/s during permeation, whereas the B-P GCL maintained low hydraulic conductivity (~ 4.3 × 10 −12 m/s). Suppression of bentonite swelling by the bauxite liquor is the primary factor responsible for the higher hydraulic conductivity of the Na-B GCL. Low hydraulic conductivity of the B-P GCL to bauxite liquor is attributed to polymer clogging intergranular pores controlling flow of bauxite liquor through the GCL. The findings indicate that B-P GCLs with sufficient polymer loading can be used effectively in composite liners for disposal facilities containing bauxite liquor.