Amélioration de la résistance mécanique des remblais miniers en pâte cimentés : étude des effets de l'ajout d'adjuvants et de liants alternatifs

Cemented paste backfill is one of the methods of integrated management of tailings from ore processing. It consists of filtered mine tailings, water and binders. CPB has some technical (ground support), economic, and environmental benefits. Indeed, it allows to increase ore extraction (leaving less pillar support) and to place underground up to 50% of tailings (which are problematic for surface disposal). However, paste fill practice involves significant costs and binders make up 80% of backfilling overall costs. Therefore, the main goal of this work is to enhance mechanical properties of CPB and reduce costs related to its manufacture. Two approaches were investigated. On the one hand, substituting traditional binders with alternative binders (by-products with low or no commercial values) and on the other hand, adding admixtures such as superplasticizers which allow optimizing the amount of mixing water recognized as deleterious for CPB mechanical properties. Consequently, it was, firstly, to assess the influence of additives used in CPB manufacture as flocculent agent. Secondly, to study the optimal substitution of traditional binders, Taguchi experimental design was used to determine the optimal recipes followed by their alkali-activation to improve theirs mechanical performances while focusing on by-products pozzolanicity. Finally, assessment of superplasticizers effects on CPB performances was made by using measurement tests of slump, uniaxial compression, microcalorimetry, and zeta potential measurements. To attain this aim, four types of tailings (four sampling points in the backfill plant) from LaRonde polymetallic mine, four different superplasticizers groups (lignosulfonate, polynaphthalene sulfonate, polymelamine sulfonate and polycarboxylate), alternative binders (industrial by-products having pozzolanic properties) and sodium silicate were used.