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Improving the efficiency and safety of hardening filling mixtures pipeline transport to deep mines

Relevance. Extraction of mineral raw materials has a negative impact on the natural environment. This effect is neutralized through technologies for mineral extraction using various options for development systems with worked-out spaces filling with hardening filling mixtures of various composition and strength. However, their application is complicated by hardening filling mixtures transportation through the pipeline over considerable distances vertically and horizontally to the point of placement, increased material and labor costs, and a shortage of material for preparing mixtures. Research aim is to improve the efficiency and safety of hardening backfill mixtures pipeline transportation into deep mines by determining the main parameters of hardening backfill mixture pipeline transportation installations (PTI), based on the conditions of its reliable delivery to the point of placement at minimal costs. Research methodology included literature review, the methods of theoretical generalizations using mathematical statistics, physical and mathematical modeling, calculations and feasibility studies, laboratory and field experimental studies, and industrial tests in deep mines using standard and new methods. Results. New USD-1 equipment has been developed and put into production for hardening filling mixtures delivery to deep mines; the equipment ensures overpressure reduction in the pipeline installed in the rise heading of 895–825 m floor in the Novaya-Glubokaya mine, Zheltye Vody, Ukraine. Conclusions. The recommended value of the maximum length of the pipeline between the reloading nodes is within the range of 415–508 m, and the excess of the emergency unloading point above the horizon is 11 m. In the last section of the vertical pipeline (turning into horizontal), a length is selected that ensures normal transportation of the mixture. The efficiency of hardening backfill mixture transportation has been established, which increases due to the elimination of stratification in the horizontal section of the pipeline under the condition of vmin <v <vmax, where v, vmin, vmax are mixture velocities corresponding to the steady design mode of transportation, the presence of solid aggregate particles at the limit in the weighted condition and maximum filling level of the filling pipeline vertical column.