In order to obtain hydrophobic material, the surface of natural limestone with the high content of calcite (>95%), was treated with 0.5, 1, 1.5, 2, 3 and 4% of stearic acid. Two methods were used for modification: the solution method and the dry coating. The obtained products were characterized using the thermal analysis (DT/TG), X-ray powder diffraction analysis (XRPD), scanning electron microscopy (SEM) and by the evaluation of floating test. Results of floating test showed that when the solution method was applied, the hydrophobicity arrived at above 99% when the amount of stearic acid was 1.5%, while with the dry coating the same hydrophobicity was achieved with 3% of stearic acid. From the position of the principal exothermic peak (> 310 °C) at DTA curves, for calcites modified with dry coating and with the solution method, it can be concluded that with both modification processes, the same active sites exist at the calcite surface onto which stearic acid may be chemisorbed. However, the position and the intensity of the other exothermic peaks, indicate the differences in bonding of stearic acid at the calcite surface during the solution method and the dry coating

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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 non-linear 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 finegrained material of a size of 0.074 mm 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 the 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 mm, 0.176 mm, 0.193 mm, and 0.225 mm), and kinetic bulk density of the hydraulic mixture (1-1.6 kg/m 3), this rate ranges from 3-5.5 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/m 3 should be accepted as a limit from a point of view of the hydraulic transport cost-efficiency.

Dobijanje novih asortimana proizvoda iz litotamnijskog krečnjaka ležišta "Dobrilovići" u postrojenju Zavoda za poljoprivredu Loznica ŽIVKO T. SEKULIĆ, Institut za tehnologiju nuklearnih i Stručni rad drugih mineralnih sirovina, Beograd UDC: 522.54:66.074.037 VLADIMIR D. JOVANOVIĆ, Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd SLAVICA R. MIHAJLOVIĆ, Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd DRAGAN S. RADULOVIĆ, Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd VLADAN D. KAŠIĆ, Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd BRANISLAV B. IVOŠEVIĆ, Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd U radu su prikazani rezultati ispitivanja mogućnosti poboljšanja tehnološkog postupka valorizacije litotamnijskog krečnjaka ležišta "Dobrilovići" -Loznica u cilju dobijanja novih asortimana proizvoda: za odsumporavanje dimnih gasova (ODG), kao dodatak stočnoj hrani i za kalcizaciju kiselih zemljišta.Rezultati su pokazali da se iz krečnjaka ovog lokaliteta mogu dobiti navedeni proizvodi koji po svojim karakteristikama ispunjavaju unapred propisane uslove kvaliteta. Na osnovu rezultata laboratorijskih ispitivanja autori su predložili tehnološku šemu po kojoj je moguća potpuna valorizacija krečnjaka iz ležišta "Dobrilovići". Adaptacijom postojeće tehnološke linije u firmi Zavod za poljoprivredu "Loznica" doo (koja je vlasnik Rudnika krečnjaka "Dobrilovići") mogu se dobiti još tri nova asortimana proizvoda.