This paper studies the effects of pipeline inner surface materials on hydrotransport energy parameters in the transportation of tailings slurry. It has been established that pipelines with inner surfaces made of polymeric materials ensure higher transportation energy efficiency due to lower specific pressure losses. The respective laboratory tests were carried out in two stages. At the first stage, pressure losses in the transportation of pure water and the initial roughness of the pipe samples studied were experimentally established. At the second stage, changes in sample roughness were studied in the hydrotransport of tailings slurry. The samples were represented by pipes made of high-density polyethylene with an inner layer of thermoplastic vulcanizate; single-layer pressure pipes manufactured in compliance with GOST 18599; and previously used longitudinally electric-welded steel pipes under GOST 10704-91. The influence of the hydraulic friction coefficient on the specific pressure loss and energy intensity of the hydrotransport process has been analyzed. Equivalent roughness values have been established for pipelines made of polymer materials and steel. The relationship between the roughness height parameters of Ra, Rq, Rz and the equivalent even-grained roughness has been established; their changes during tailings slurry hydrotransport ha

he purpose of the work is to analyze the aggregates of complexes for the extraction of marine minerals. In particular, the variants of complexes, their advantages and disadvantages are considered. The complex is analyzed, which uses robotic pickers/reclaimers of the walking type to perform mining operations of ferromanganese nodules (FMN) or cobalt-bearing manganese crusts (CMC). Results. The variants of complexes for mining of bottom deposits are analyzed, advantages and disadvantages of different variants are indicated. The device for collecting minerals on the bottom, developed in SPMU, is described, laboratory studies of the model of such a device are considered, the main parameters are presented, the dependence of productivity on the size and time of operations of the cycle of work is indicated. It is determined that for minimal impact on the seabed biota it is necessary to use walking submersibles with an actuator for extraction in the form of rarefaction chambers or a grapple with an impactor (depending on the type of solid minerals). It is shown that the productivity of the walking underwater vehicle varies with the diameter of the rarefaction chamber plates: the optimum plate diameter is 1.5 m. Experimental study of hydrodynamic resistance of “foot” models with different midships cross-section has been carried out. According to the experimental results, the conclusion about the preferred design of the “foot” was made: the cross-section should be a streamlined shape with the smallest drag coefficient cx and have a continuous surface without holes. Experimental studies of tine models movement in water have shown that it is reasonable to use as tine parts the structures without holes, streamlined ellipsoidal shape. Calculations of productivity of mining units when using rope hoisting from the bottom to the ship have shown the necessity of using four or more hoisting devices for realization of the required annual productivity of more than 1 million tons per year. The stages of creating a workable extraction unit including a vessel, vertical lifting device and a system of deep-water collectors require very significant material and monetary costs, so they should be carried out in accordance with the R&D plan and tasks of the relevant ministry and agency and require coordination of efforts of investors, scientists and machine builders.

Based on the literature review, the authors arrive at the conclusion that abrasivity of rocks is not only governed by their strength, but also by the structure and parameters of mineral inclusions, such as shape, size and amount. In terms of the Khibiny’s apatite–nepheline ore of various kinds with different strength and mineralogical composition, it has experimentally been estimated using the modified Baron–Kuznetsov procedure how the strength of rocks affects the wear rate of specimens made of steel 110G13L that is most often used for manufacturing rapidly wearing parts of mining equipment. It is found that for all ore kinds tested, the steel wear rates are approximately the same irrespective of the ore strength. It has been supposed that on abrasion of steel on hard rock (f ~ 10) composed of grains of hard tabular nepheline with thin partings of relatively soft fine-grain apatite, nepheline grains disengage slowly, the contact surface becomes smooth and steel wear rate is reduced consequently. On the other hand, on abrasion on weak rock (f ~ 0.5) composed mostly of apatite, fast failure of this type rock causes continuous exposure of rough-surface apatite grains, which accelerates steel wear resistance. On stee