3D visual detection method of mine filling pipeline blockage based on ERT technology

Full tailing sand cementation filling method has been widely used in metal mines. However, the safety and routine operations of filling pipeline are significantly threated by plugging and bursting of the filling slurry in the pipe transmission process, which is a great obstacle restricting the development and application of filling technology. In the paper, the three-dimensional model of multi-layer ERT sensing array is constructed based on COMSOL software for the purpose of exploring the visualization detection method of mine filling pipe blockage, obtaining the three-dimensional information of geometry and relative position of the lump inside the mine filling pipe. Moreover, the ERT positive problem is solved by using finite element method. The trend of potential and current density in the three-dimensional ERT sensitive field are revealed. On this basis, the “soft field” characteristics of ERT were analyzed in terms of sensitivity, and the distribution law of detection sensitivity in the three-dimensional sensitive field is provided. The inverse problem of ERT is solved by Gauss-Newton algorithm, and the three-dimensional image reconstruction is performed for five blockage simulation models. The simulation results show that the difference between the regularized Gauss-Newton one-step algorithm and the regularized Gauss-Newton iterative algorithm in terms of reconstructed image quality is minor. The reconstruction time of the regularized Gauss-Newton one-step algorithm is, however, better than the regularized Gauss-Newton iterative algorithm, which is more suitable for 3D image reconstruction. The Laplace prior knowledge selected in the Gauss-Newton one-step algorithm is better than the Noser prior knowledge. Finally, according to the simulation model, four kinds of agglomerated specimens with different sizes were made using the metal mine tailing sand. After 14 hours of curing, the specimens are put into five different positions in a vertical pipe filled by full tailing backfill with 74% solid content to simulate different agglomerated positions and clogging degrees inside the filling pipe. Then the self-developed 48-electrode 3D-ERT imaging system and the Gauss-Newton one-step algorithm are utilized to perform 3D imaging experiments on the above five blockage cases. The experimental results show that the measured results are consistent with the simulation results, and the reconstructed images can accurately reflect the three-dimensional information of the geometry and location of the clumps inside the pipeline.