Effect of content of defluorinated solid waste on macroscopic strength and microstructural evolution of cemented tail filling composites

Abstract

Solid waste created by the ferrous mining industry has a major number of notable differences. The deficiency of recognition of solid waste features is the key factor limiting its discarding and reuse. In this paper, cemented tailings backfill (F-CTB) was prepared by combining the defluorinated solid waste made in the process of mine's water treatment and tailings. The impact of content of defluorinated solid waste on macroscopic strength and microstructure of filling was investigated experimentally. Lab findings reveal that with the growth of content of defluorinated solid waste in backfill, fill's strength decreases and then increases. Fill's damage mode changes to tensile damage-shear damage-tensile damage, which leads to the following conclusions: in the case of the sufficient amount of defluorinated solid waste, F-CTB will not be delaminated and its strength will be increased. Through the analysis of energy, one can accomplish that, in the case of content of defluorinated solid waste in 60 %, the dissipated energy is smaller, and F-CTB will be stronger and stronger. Energy dissipation is reasonably small while F-CTB's inner cracks is less. The microstructure of F-CTB was observed by SEM and analyzed by energy spectrum. As the content of defluorinated solid waste increases, the hydration products and Ca(OH)2 crystals in F-CTB will hinder cracks’ generation/development ensuring F-CTB's strength. This research sheds new light on clarification of efficient use of defluorinated solid waste in backfill form and offers some practical ways on its efficient treatment and disposal technique.