Study on influence of potential gradient on dewatering and consolidation characteristics of fine tailing sand and its mechanism

Due to low hydraulic conductivity and poor water permeability, the sand particles of tailings storage pile dams lead to the problems of poor drainage capacity, long consolidation time and low mechanical strength of the pile dams, which are prone to cause geologic disasters such as pile dam instability. Combined with the tailings sand specific surface area and strong charged characteristics and electro-osmosis principle, proposed the addition of an electric field to promote its dehydration and consolidation, dry discharge tailings sand is the object of study, following the principle of similarity with the state of the sand samples of the wet discharge tailings accumulation dams, the use of independent research and development of a one-dimensional level of the electro-osmosis test device to carry out physical simulation experiments to study the potential gradient on the tailings sand drainage, evaporation, drainage rate of the changing law, combined with the role of before and after the tailings sand samples straight shear strength, the effect of the tailings sand samples, and the effect of the tailings sand samples. They Combined with the straight shear strength, X-ray diffraction and scanning electron microscopy (SEM) characterization tests of the tailings sand samples before and after the tailings sand dewatering and consolidation effect and its mechanism of action. The results show that: ①the applied electric field has a promotion effect on the dewatering and consolidation of the tailing sand, and the total dewatering volume is firstly increased and then basically stabilized with the increase of the potential gradient, and the best dewatering effect is achieved under the action of the potential gradient of 1 and 6 V/cm, and the total dewatering volume is increased by 1.61 times. It should be noted that in the 0−1 V/cm role of dehydration to electro-osmosis-based, in the 1−6 V/cm role of dehydration to electro-evaporation-based; ②The shear strength of the tailing sand increased by 12.4%−21.7% after applying the electric field, and the increase of anode under the same potential gradient was obvious compared with that of the cathode; ③ New minerals such as limonite, gypsum, and iron oxides were generated in the anode area after the application of the electric field, and no new minerals were generated in the cathode area. The proportion of limonite and gypsum in the anode area increased and then decreased with the rise of the potential gradient, and the proportion of iron oxide increased with the rise of the potential gradient; ④electric field to promote tailings sand dewatering and consolidation of the mechanism mainly has four aspects: electro-osmotic drainage, electrophoretic migration of small particles transport aggregation, electric evaporation effect, and electrochemical reaction in the anode near the role of the cementing material. The results of the study provide some theoretical and applied value for the applied electric field to promote the dewatering and consolidation of tailings sand.