Acoustic emission investigation of cemented paste backfill prepared with tantalum–niobium tailings

Abstract

Tantalum-niobium tailings are solid waste materials left over from mine beneficiation, which occupy the surface space and pollute the surrounding natural environment. If tailings are cemented with cement to form tailings cementing material and filled into the mined-out area, the stability of surrounding rock in the mined-out area can be guaranteed, and waste materials can be recycled. The mechanical properties of filling body are the main factors to ensure the stability of surrounding rock, and the acoustic emission characteristics can reflect the failure process of filling body under external loads. Through uniaxial compression and splitting failure tests, the relationship between AE event rate, ringing count rate, and stress–time was studied. During the entire specimen failure process, the AE activities for three different ratios (1:4, 1:6, and 1:8) showed certain variations with the loading time and stress change law. When the lime–sand ratio was 1:4, the maximum AE event occurred once the loading time reached 300 s, that is, after the peak stress. When the lime–sand ratio was 1:6, the maximum AE occurred at 250 s, which corresponds to the peak stress. When the lime–sand ratio was 1:8, the maximum AE event occurred once the filling time reached 200 s, that is, before the peak stress. Under the condition of uniaxial compression, the initial stage of an AE activity was not evident. As the load increased toward the elastic molding stage, the AE activity became active and fluctuated greatly. Near or at the point of peak stress, the AE event reached an extreme value. The AE activity law of the split test specimen was generally consistent with uniaxial compression. The difference is that under the split test condition, the AE activity of the filling specimen was inactive, and the performance was relatively calm before the peak stress. When stress peaked, the AE activity was extremely active and reached its maximum.