Bleeding Characteristics and Improving Mechanism of Self-Flowing Tailings Filling Slurry with Low Concentration

In order to solve the bleeding problem of self-flowing tailings filling slurry with low concentration, the influences of the dosage of special additive on the bleeding rate were investigated. The improving mechanism of special additive on the bleeding of tailings filling slurry was studied by measuring the bleeding rate and compressive strength of the slurry. Also, microstruture analysis was conducted by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and infrared spectroscopy (IR) of the hardened body. The results show that with the slurry concentration of 60%, the binder-to-tailings ratio of 1:6 and the special additive dosage of 10%, the filling slurry is not bleeding and the compressive strength of hardened body can increase by 43.5% at three days. A large amount of needle-like ettringite is generated in the hardened body after adding the special additive, and the structure becomes denser. The special additive can effectively improve the bleeding of the filling slurry and increase the compressive strength of the filling material at early age.