Optimisation of geocomposites for sludge filtration in the context of an industrial partnership

Abstract

The mining industry produces huge amounts of waste under the form of mineral sludge, like mature fine tailings issues from the production of bituminous sands. These residues are hard to dry, in relation with their large clay content. This paper gives the result of a study of filtration under pressure of a sludge containing silt and clay by nonwoven geotextiles (GTX): 8 different geotextiles were tested with the same sludge containing a high amount of clay. Then 8 different sludge compositions with variable amounts of silt and clay were filtered with a given GTX. The D50 of the sludge ranged between 3 and 55 µm and the clay content between 0 and 38%. Results obtained indicate that the sludge can be filtered with GTX chosen based on their opening size. GTX only impact the filtration in the very first times when they retain the biggest particles leading to the formation of a filter cake. The filter cake very quickly becomes the filtering element. The GTX function is then reduced to support of the filter cake. The final drying out of the reached during the tests is controlled by the sludge composition and totally independent of the GTX used.