**ABSTRACT**

The main problem of hydraulic transport is the resistance generated during the mixture transport through the pipeline. Testing the flow characteristics of mixtures, shown in this paper, are based on the principles of determining the unit energy losses by a mathematical calculation using the nonlinear regression - the Levenberg-Marquardt algorithm. Such obtained results allow determining a transport rate in the horizontal pipeline, depending on the mixture bulk density and pipeline diameter. The flotation tailings is mainly used as a filling material in the mine "Trepca" - Stari Trg. According to the grain size distribution, it is a fine-grained material of a size of 0.074 to 1.2 mm. It is a multicomponent material containing pyrite, pyrrhotine and other heavy metals, and therefore has a high bulk mass. The average rate of t hydromixture, in which the energy losses reach the minimum value, depends on the pipeline diameter and kinetic bulk density of the mixture. For the test interval of change in the pipeline diameter, shown in this paper (0.168; 0.176; 0.193 and 0.225 mm), and kinetic bulk density of the hydraulic mixture (1-1.6 kg/m3), this rate ranges from 3 to 5.5 m/s. The increase of the energy losses in the hydraulic mixture transport increases proportionality with the increase of its kinetic bulk density. The results, presented in this paper, show that the required bulk density of 1.6 kg/m3 should be accepted as a limit from a point of view of the hydraulic transport cost-efficiency.

**KEYWORDS**

PAPER SUBMITTED: 2018-06-08

PAPER REVISED: 2018-08-24

PAPER ACCEPTED: 2018-08-27

PUBLISHED ONLINE: 2018-09-30

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