Deformation behaviors of cemented backfill using sulphide-content tailings

Abstract

The deformation properties of cemented tailings backfill (CTB), especially prepared from sulphidic tailings, are valuable for the estimation of design parameters for underground stope filling as well as for numerical simulation. In this paper, the effect of curing time, sulphur content, cement dosage and solids concentration on the free expansion ratio of CTB specimens was investigated using an invented lab apparatus called "free expansion measuring instrument". The backfill recipe (sulphur content, binder dosage and solids concentration) and curing days had significant influences on the expansion performance of the CTB. The results indicated that with the change of sulphides, the free expansion ratio (FER) showed no obvious growth at the curing of 28 days. However, after the curing of 120 days, FER increased from 4.96% (S: 4%) to 9.61% (S: 20%). As the solids concentration increased, the FER also rised. And this growth was distinctive only when the solids concentration is relatively high (65~75%) and at the long-term curing time (120 days). The proportions of binder and the obtained FER clearly show a sub-linear and proportional relationship. Increasing the amount of binder (8~16%) could not restrict the increment of expansion ratio, and ultimately the CTB specimens would generate cracks and collapse.

Study of the reduction of resistance over time in specimens tested by uniaxial compressive strength for paste filling

“…It should be noted that different types of cements were evaluated to compare their behaviour of resistance over time, taking into account the properties of each type of cement. The UCS tests in Stage 3 were carried out with different types of anti-sulfate cement (Yin et al 2017) and different types of slag. The results show that the sample (tailings/cement) which reached the highest resistance was type V cement.…”