Soil formation from tailings: comparison of predictions and field measurements

The extraction and processing of most mineral ores results in the generatio n of large volumes of fine-grained residue or tailings. The safe disposal o f such material, which generally exhibits slow rates of sedimentation and c onsolidation, is of prime concern to the management of mining operations. I n order to devise both long- and short-term options, it is necessary to hav e an understanding of the transportation, sedimentation and consolidation c haracteristics of the residue material, which may be impounded behind speci ally designed dams. The processes of transport of sediments, sedimentation and consolidation take place simultaneously in the reservoirs formed behind dams. The objective of this study is to analyse the coupled phenomena of s oil formation to estimate accurately the capacity of a reservoir when waste material is impounded. An implicit finite difference analysis was develope d to solve the transport of sediments and sedimentation problem. Linked to this procedure, a finite element analysis of the consolidation processes is introduced considering geometrical and material non-linearity, through the use, respectively, of a Eulerian rate viewpoint and a nonlinear elastic co nstitutive model. The complete process is analysed in a step-by-step method ology. This paper compares numerical results with held measurements during the disposal of bauxite mine tailings. The numerical analysis successfully predicts the filling of the reservoir and the void ratio profile.