Rade Tokalic

Preliminary Examination of the System Fly Ash-Bottom Ash-Flue Gas Desulphurization Gypsum-Portland Cement-Water for Road Construction

This paper describes an investigation into the use of three power plant wastes: fly ash, flue gas desulphurization gypsum, and bottom ash for subbase layers in road construction. Two kinds of mixtures of these wastes with Portland cement and water were made: first with fly ash consisting of coarser particles (<1.651 mm) and second with fly ash consisting of smaller particles (<0.42 mm). The mass ratio of fly ash-Portland cement-flue gas desulphurization gypsum-bottom ash was the same (3 : 1 : 1 : 5) in both mixtures. For both mixtures, the compressive strength, the mineralogical composition, and the leaching characteristics were determined at different times, 7 and 28 days, after preparation. The obtained results showed that both mixtures could find a potential use for subbase layers in road construction.

Polymer resins with foam effect and their application in mining

For stabilization of degraded rock massif around the built underground mining premises, the procedures of injecting of polymer synthetic resins with foam effect are in use today more and more. By injecting of polymer resins in drill holes or cracks and their hardening, the spreading of deformity by depth is stopped, and therefore the stability of degraded rock material and built premises is provided. For increasing the stability of mining premises, the fast reacting phenolic resins are used, filling up the cracks in the cracked rock mass and preventing their expansion. In that way they contribute improving the operative safety and efficiency in building the mining premises. Few years ago, two-component poliurethan foamy resins appeared that have found an application for strengthening, insulation and rehabilitation of mining premises demanding a medium or longer period of usage. Urea of silicate non-flammable resin is approved for usage in the coal mines and in building the underground premises in heavy work conditions. Stabilization and strengthening of weaked zones in these cases is done by combining the drainage and injecting the fast reacting foamy resins. New materials and technologies have enabled very significant improvements in many areas of mining and constructions, both in domain of faster, safer and more efficient building, and in domain of maintenance and rehabilitation the mining and construction facilities.

Justification of renewed coal exploitation from the deposit 'Bajovac'

Coal presents the basic energy potential of the Republic of Serbia. More than half of electric energy production in our country comes from this resource. This causes a need for activation the new seams of raw material which are potentially exploitable. This work presents an extract from the research results, published within the Project TR 33029 “Study of Possibilities for Valorization the Remaining Coal Reserves with a View to Provide the Stability of Energy Sector of the Republic of Serbia”, financed by the Ministry of Education and Science. This work treated the problems of future coal exploitation from the West Morava Basin, with special review to the activation of the closed mine “Bajovac”.