Influence of Acid Attack on Physical Characteristics of Cemented Tailings Backfill

The strength of backfill plays an important role in the stability and safe mining of goaf. Considering the influence of underground acid environment, the physical characteristics and corrosion mechanism of cemented tailings backfill (CTB) are studied. Based on the accelerated test method of the acid environment, the mass change fraction, longitudinal wave velocity, porosity, volume and appearance change in sulfuric acid solution of the CTB in different corrosion periods were measured and analyzed. In addition, the concentration of H + in solution was monitored, and the surface material of the corroded backfill was analyzed by X-ray diffraction and scanning electron microscopy. The results show that acidic corrosion increases the porosity, longitudinal wave velocity, and volume of the CTB after soaked 60 days. Acidic corrosion also increases the quality of the CTB in the early stage of corrosion. The quality of the CTB deceased with day of corrosion in long term. Corrosion causes the surface of the CTB to bulge and fall off. The corrosion mechanism of the CTB was found to be generated by two kinds of destructive factors: the dissolution reaction of H + ion and S0 4 2− ion resulted in the swelling material.