Abstract: The proportion of filling material slurry has a significant impact on filling body strength and slurry conveying properties.Due to the shortages in the supply of rod milled sands in Jinchuan Mine,tests were carried out to investigate the filling intensity,slurry fluidity,bleeding ratio and loss rate of sedimentation of mixed filling slurry which contains three kinds of filling additives of rod milled sand,rod milled sand+river sand and rod milled sand+river sand+fly ash by adding the same amount of cement.The results showed that with proportion of river sand+rod milled sand at 2∶8,mixed filling slurry has the same filling intensity with the rod milled sand,and its slurry fluidity,bleeding ratio and loss rate of sedimentation are relatively lower.Still,it can meet the requirements of backfill mining in Jinchuan Mine.With the additive of fly ash as much as 30% of cement,the mixed slurry can greatly improve the strength of filling body,but also improve slurry fluidity,bleeding ratio and loss rate of sedimentation.Meanwhile,the segregation degree of filling slurry is reduced,which provides benefits to improve filling body quality and roof-contacted filling.The research result has been successfully applied in filling slurry preparation and industrial production in Jinchuan Mine.

Key words: Rod milled sand, Mixed filling material, Fly ash,Filling body strength, Conveying properties