Green liquor dregs are one type of chemical by-products produced by the pulp and paper industry which are usually landfilled, and cause concern to the pulp mills due to the cost of landfilling. Their alkaline and impermeable properties render however their re-utilisation possible in several domains. Solidification/stabilisation of sulphide ore mine tailings is one type of potential application of green liquor dregs which is considered in this work. The project aimed at assessing the efficiency of green liquor dregs associated with other pulping wastes (fly ash, bark sludge) in decreasing the permeability and release of metal contaminants in copper mine tailings from an abandoned mine site. The possibility to use these pulping wastes as a hydraulic barrier to cover tailings or traditional landfills was also considered. To achieve this objective, 2 types of permeability tests were performed, as well as an adapted Column Leaching test and a modified Batch Leaching in oxidising conditions. Tailings alone, different combinations of pulping wastes, and tailings treated with these combinations of pulping wastes were tested. Addition of pulping wastes to tailings proved efficient in immobilising copper, in particular when one type of green liquor dregs was added to tailings in the proportion of 10%. Copper release was reduced at least 4 times by all the admixtures. Permeability of tailings was decreased to various extents with the addition of different proportions of pulping wastes. The best result was obtained with a combination of green liquor dregs, fly ash and bark sludge mixed with tailings. Hydraulic conductivities of pulping wastes were not as low as to guarantee their efficiency as a hydraulic barrier. It was suggested that moistening the materials may improve their impermeability. Variability of the wastes produced by the mill was judged as the major problem if their re-utilisation became effective, and increased green liquor dregs quality control was suggested.