Geotechnical evaluation of uranium tailings for enhanced dewatering

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The uranium mining industry in Canada is at the forefront of environmental compliance. The tailings (produced as a by-product of metal extraction) have been traditionally stored in large containment facilities and thoroughly monitored for several decades. To reduce both space requirements and time commitment, Cameco Inc. has recently launched an initiative to develop engineered tailings streams. This new category of tailings will have superior geotechnical properties (segregation, sedimentation, consolidation, and hydraulic conductivity) that will also contribute to geochemical (diffusion-controlled movement) stability. As part of Cameco Inc.'s engineered tailings initiative, the main objective of this collaborative research is to understand and improve the dewatering and segregation behavior of the next-generation uranium tailings. This is the first time that such a detailed geotechnical evaluation of the uranium tailings streams is undertaken at Cameco Inc. Based on a comprehensive research program, an innovative scientific framework will be developed to study the selected slurries in conjunction with complex physicochemical interactions at the solid-liquid interface. This is a paradigm shift from conventional geotechnical engineering that deals with the physical understanding of soil behavior by considering the soil as chemically inert. The proposed research will be a significant development for Cameco Inc. with respect to its future expansion plans. The resulting technology (physicochemical model, nonsegregating tailings, improved dewatering, and ternary diagram) will be pivotal for tailings design at various Canadian mining operations. The expected economic benefits of material-specific tailings amelioration methods can be classified as follows: (i) increased storage capacity of the tailings impoundments; (ii) lower environmental liabilities due to reduced metal mobility; (iii) increased reclamation of process water and chemical reagents; and (iv) improved balance water consumption at various stages in the ore beneficiation process. Likewise, the infrastructure capacity development, recruitment of qualified professionals, and cross-disciplinary extensions are important benefits for the University of Regina.