The article presents analytical calculations of specific pressure losses during hydraulic transportation of slurry tailings from iron ore beneficiation processes at the Kachkanarsky MPP during the storage of processing tailings in the tailings pond. The calculations were performed based on the results of experimental studies of dependence of specific pressure losses on roughness of inner surface of pipelines lined with polyurethane coating. In the process of experimental determination of pipeline polyurethane coatings roughness, it was established that the physical roughness of the coatings is more than four times less than the roughness of steel pipelines, which leads to a decrease in the coefficients of hydraulic resistances included in the design formula for the specific pressure losses - the Darcy-Weisbach formula. The coefficients of relative and equivalent roughnesses for pipelines with and without coating have been calculated. Comparative calculations have shown that the use of polyurethane coatings of hydrotransport pipelines contributes to a decrease in the specific energy during hydraulic transportation of processing tailings of iron ore from Kachkanarsky MPP in 1.5 times. To assess the nature and intensity of changes in the physical roughness of test pipes with polyurethane coating, experiments were performed on the roughness on a laboratory hydraulic bench. The prepared slurry of the iron ore tailings of Kachkanarsky MPP was pumped through a looped pipeline, in the linear part of which three test coated pipes were sequentially installed. Experiments showed that the roughness after running 484 hours on all the samples of the pipelines varies insignificantly. Roughness values are in the range from 0.814 to 0.862 μm. As a result of the processing of experimental data by mathematical statistics, an empirical formula is obtained for calculating the surface roughness of the polyurethane coating surface, depending on the time of operation of pipeline transporting the slurry of the iron ore processing tailings.
