Research on the Engineering Properties of Phosphogypsum Based on the Laboratory Test

摘要

Phosphogypsum (PG) is one of the major solid wastes disposed on land. The safety evaluation of PG stacks is highly dependent on the correct characterization of its properties. Laboratory tests were performed to determine the physical and mechanical properties of PG, including its gradation, hydraulic conductivity, and consolidation characteristics. The shear strength of sedimented PG was determined through consolidated-undrained triaxial tests. Results show that PG is a dilatant granular material with a high internal friction angle. The odometer consolidation tests revealed that the consolidation of PG can last a long time after the initial sedimentation and the magnitude of consolidation caused by creep was significantly higher than that caused by compression. The measured vertical hydraulic conductivity of PG ranged from 10~(-5) cm/s to 2×10~(-4) cm/s, which is similar to that of silt. The CU triaxial tests showed that PG exhibits a dilalant behavior under all confining pressures and its shear strength is higher than that of most soil and mine tailings, with an effective peak friction angle of approximately 46.5°.