Thermal analysis and kinetics of the chalcopyrite-pyrite concentrate oxidation process

The paper presents the results of experimental investigation of the chalcopyrite-pyrite concentrate oxidation in the air. Characterisation of the initial sample and oxidation products was done by ICP-AES, XRD, EDXRF methods. Phase stability diagrams were constructed for Cu-Fe-S-O system at 25, 450, 650 and 900 °C. Equilibrium composition of the charge for the optimal oxidation process was calculated. DTA-TG analysis was used for monitoring the oxidation process. Kinetic parameters in non-isothermal conditions were determined, based on Kissinger and Ozawa methods.Values of activation energies showed that all stages of the oxidation process occur in the kinetic field

Natural radionuclides in soil profiles surrounding the largest coal-fired power plant in Serbia

This study evaluates the influence of the largest Serbian coal-fired power plant on radionuclide concentrations in soil profiles up to 50 cm in depth. Thirty soil profiles were sampled from the plant surroundings (up to 10 km distance) and analyzed using standard methods for soil physicochemical properties and gamma ray spectrometry for specific activities of natural radionuclides (K-40, Ra-226 and Th-232) Spatial and vertical distribution of radionuclides was determined and analyzed to show the relations between the specific activities in the soil and soil properties and the most influential factors of natural radionuclide variability were identified. The radiological indices for surface soil were calculated and radiological risk assessment was performed. The measured specific activities were similar to values of BACKGROUND: levels for Serbia. The sampling depth did not show any significant influence on specific activities of natural radionuclides. The strongest predictor of specific activities of the investigated radionuclides was soil granulometry. All parameters of radiological risk assessment were below the recommended values and adopted limits. It appears that the coal-fired power plant does not have a significant impact on the spatial and vertical distribution of natural radionuclides in the area of interest, but technologically enhanced natural radioactivity as a consequence of the plant operations was identified within the first 1.5 km from the power plant

Procena ekološkog i zdravstvenog rizika od teških metala u zemljištu u okolini termoelektrane „Nikola Tesla A“

Ecological and health hazards were assessed based on the concentrations of selected heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in thirty surface soil samples taken from the sites around the largest Serbian thermal power plant. Ecological risk caused by heavy metals was estimated through pollution indices whose values indicated low to moderate ecological risks. Health hazard associated with residents’ exposure to heavy metals in soil was calculated applying the U.S. EPA model. The ingestion of soil was the most important exposure pathway. The risk assessment showed that exposure to Co, Fe, and Mn would result in an unacceptable non-carcinogenic risk for children. Cr and Pb were reported to significantly contribute to a carcinogenic risk, while total carcinogenic risk remained within the acceptable non-hazardous range.Ekološki i zdravstveni rizik su procenjeni u odnosu na koncentracije odabranih teških metala (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb i Zn) u trideset površinskih uzoraka zemljišta iz okoline najveće termoelektrane u Srbiji. Ekološki rizik je procenjen putem različitih pokazatelja zagađenja i njihove vrednosti pokazuju niski do srednji ekološki rizik. Rizik po zdravlje usled izlaganja stanovništva teškim metalima u zemljištu je izračunat primenom modela Agencije za zaštitu životne sredine Sjedinjenih Američkih Država. Ingestija zemljišta je identifikovana kao najvažniji put izlaganja. Procena rizika je pokazala da ekspozicija Co, Fe i Mn rezultuje neprihvatljivim nekancerogenim rizikom za decu. Cr i Pb su bili jedini elementi koji su doprinosili u većem obimu kancerogenom riziku, ali je ukupan kancerogeni rizik bio u granicama tolerantnog

Memory, post-socialism and the media: nostalgia and beyond

While research on the mediation of post-socialist memory has gained momentum in recent years, the field remains fragmented and limited to small-scale case studies, with little attempt to develop a more general reflection on the nature of the processes investigated. Engagement with the wider literature on the mediatisation of memory has been limited as well, with research typically applying established conceptual frameworks rather than using post-socialist materials to generate new theoretical insights. Given the state of the field, this article has a double aim. First, it offers a critical review of the main trends in existing research, focussing on four key issues: the fascination with nostalgic modes of remembering, the dominance of national frames of analysis, the lack of research on the mediation of personal and vernacular remembering, and the privileging of descriptive over explanatory modes of analysis. Second, the article outlines a new agenda for the field, and proposes three main research trajectories. The first pays attention to how mediated memories at local and national levels interact with transnational processes of remembering the Cold War, the second focusses on to the intersections between personal and public modes of mediated remembering, and the last moves the discussion from description to explanation, using comparative approaches to advance explanations of different modes of mediated post-socialist memories

Mineralogy and crystallographic properties of heu-type zeolitic tuff from the novakovic deposit, Bosnia and Herzegovina

This paper presents mineralogical and crystallographic characterization of the zeolitic tuff from the Novakovic deposit, Republic of Bosnia and Herzegovina. The zeolitic tuff is of a whitish color composed of Ca-clinoptilolite and an amorphous phase (volcanic glass and amorphous SiO 2 ). The zeolitic tuff was analyzed by X-ray diffraction of the polycrystalline sample (XRPD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), and differential thermal and thermogravimetric (DTA/DTG) methods. According to the results obtained, it can be concluded that the studied zeolitic tuff is composed of Heu-type minerals. Based on the chemical analysis, thermal treatment and XRPD analysis it was determined that this is a mineral Ca-clinoptilolite. Thermal analysis in the temperature range from 300 up to 700°C showed that the examined zeolite minerals from the Novaković deposit are stable up to the temperature of 600°C. The crystal structure of Ca-clinoptilolite has been refined in the centrosymmetric space group C2/m (S.G. 12) with disordered distribution of Al and Si in the tetrahedral framework. The unit-cell parameters are as follows: a = 17.662 Å, b = 17.874 Å, c = 7.402 Å, β = 116.32° and V = 2122.73 Å 3 . The basic structural motif is represented by four channels. Three channels are composed of eight-membered rings, and one of ten-membered rings. The ten-membered (channel A) and one eight-membered channel (B) are parallel to the crystallographic axis c, and the other eight-membered channel is parallel to the a-axis. Ca-clinoptilolite comprises approximately 90 % of the studied zeolite tuff while the rest 10 % is the amorphous phase. The overall cation exchange capacity (CEC) amounts to 187 mmolM + / 100 g, and calcium represents the most abundant cation in the studied sample. The atomic ratios of Si/Al, Na + /(Na + +K + ), and Ca 2+ /(Ca 2+ +Mg 2+ ) are as follows: 4.36, 0.14, and 0.55, respectively. The zeolite tuff is both thermally and structurally stable and has applications in various areas of industry and agriculture. © 2018, Association of Chemists and Chemical Engineers of Serbia. All rights reserved

PROCENA EKOLOŠKOG I ZDRAVSTVENOG RIZIKA OD TEŠKIH METALA U ZEMLJIŠTU U OKOLINI TERMOELEKTRANE „NIKOLA TESLA A“

Ecological and health hazards were assessed based on the concentrations of selected heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in thirty surface soil samples taken from the sites around the largest Serbian thermal power plant. Ecological risk caused by heavy metals was estimated through pollution indices whose values indicated low to moderate ecological risks. Health hazard associated with residents’ exposure to heavy metals in soil was calculated applying the U.S. EPA model. The ingestion of soil was the most important exposure pathway. The risk assessment showed that exposure to Co, Fe, and Mn would result in an unacceptable non-carcinogenic risk for children. Cr and Pb were reported to significantly contribute to a carcinogenic risk, while total carcinogenic risk remained within the acceptable non-hazardous range.Ekološki i zdravstveni rizik su procenjeni u odnosu na koncentracije odabranih teških metala (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb i Zn) u trideset površinskih uzoraka zemljišta iz okoline najveće termoelektrane u Srbiji. Ekološki rizik je procenjen putem različitih pokazatelja zagađenja i njihove vrednosti pokazuju niski do srednji ekološki rizik. Rizik po zdravlje usled izlaganja stanovništva teškim metalima u zemljištu je izračunat primenom modela Agencije za zaštitu životne sredine Sjedinjenih Američkih Država. Ingestija zemljišta je identifikovana kao najvažniji put izlaganja. Procena rizika je pokazala da ekspozicija Co, Fe i Mn rezultuje neprihvatljivim nekancerogenim rizikom za decu. Cr i Pb su bili jedini elementi koji su doprinosili u većem obimu kancerogenom riziku, ali je ukupan kancerogeni rizik bio u granicama tolerantnog

Physicochemical properties of natural and synthetic zeolites modified by acid treatment

10th International Conference on the Occurrence, Properties and Utilization of National Zeolites : June 24-29, 2018, Cracow, Poland

10.5937/tehnika1703383L= Development of methods for traffic simulation of telecommunication processes in IRITEL over 45 years

This paper summarizes the programs intended for simulation of traffic processes in different telecommunications systems. These programs are developed, implemented and verified by the members of the Institute IRITEL through numerous scientific papers and doctoral dissertations taken during 50 years of the Institute activities. Two main areas of traffic simulations are related (but not limited) to the analyses of switching systems and mobile telephony systems