New evidence for prehistoric copper metallurgy in the vicinity of Bor

The last three years of archaeological investigations at the site Ru`ana in Banjsko Polje, in the immediate vicinity of Bor, have provided new evidence regarding the role of non-ferrous metallurgy in the economy of the prehistoric communities of north-eastern Serbia. The remains of metallurgical furnaces and a large amount of metallic slags at two neighbouring sites in the mentioned settlement reveal that locations with many installations for the thermal processing of copper ore existed in the Bronze Age. We believe, judging by the finds of material culture, that metallurgical activities in this area also continued into the Iron Age and, possibly, into the 4th century AD

Reaction mechanism and kinetics of sulfide copper concentrate oxidation at elevated temperatures

Sulfide copper concentrate from domestic ore deposit (Bor, Serbia) was subjected to oxidation in the air atmosphere due to a better understanding of reaction mechanism and oxidation of various sulfides present in the copper concentrate at elevated temperatures. Results of the initial sample characterization showed that concentrate is chalcopyrite–enargite-tennantite type, with an increased arsenic content. Characterization of the oxidation products showed the presence of sulfates, oxysulfates, and oxides. Based on predominance area diagrams for Me-S-O systems (Me = Cu, Fe, As) combined with thermal analysis results, the reaction mechanism of the oxidation process was proposed. The reactions which occur in the temperature range 25 – 1000 °C indicate that sulfides are unstable in the oxidative conditions. Sulfides from the initial sample decomposed into binary copper and iron sulfides and volatile arsenic oxides at lower temperatures. Further heating led to oxidation of sulfides into iron oxides and copper sulfates and oxysulfates. At higher temperatures sulfates and oxysulfates decomposed into oxides. Kinetic analysis of the oxidation process was done using Ozawa’s method in the non-isothermal conditions. The values for activation energies showed that the reactions are chemically controlled and the temperature is the most influential parameter on the reaction rates

Developing the objective and the scope of the ecological footprint assessment project

Besides technological and economic aspects, environmental segments are gaining equal importance in planning, realization and control of contemporary project ventures. This manuscript is presenting the frame and the scope of the project for the ecological footprint assessment. The realization of some phases of this project has already begun, while most of the remaining phases are still at the preparation stage

TECHNOLOGICAL PROCESS MODELING AIMING TO IMPROVE ITS OPERATIONS MANAGEMENT

This paper presents the modeling procedure of one real technological system. In this study, thecopper extraction from the copper flotation waste generated at the Bor Copper Mine (Serbia), werethe object of modeling. Sufficient data base for statistical modeling was constructed using theorthogonal factorial design of the experiments. Mathematical model of investigated system wasdeveloped using the combination of linear and multiple linear statistical analysis approach. Thepurpose of such a model is obtaining optimal states of the system that enable efficient operationsmanagement. Besides technological and economical, ecological parameters of the process wereconsidered as crucial input variables

Developing a Questionnaire for Measuring Safety Climate in the Workplace in Serbia

This study was conducted because a real method for measuring safety climate had never been developed and assessed in Serbian industry. The aim of this paper was to start the process of developing a safety climate questionnaire that could be used in Serbia. As a starting point a 21-item questionnaire was adopted after an extensive literature review. The questionnaire was distributed at several Serbian factories; 1098 workers responded. After a statistical analysis of the data obtained with the questionnaire and a critical comparison with the available reference results, a final questionnaire with 21 questions, divided into 7 groups, was developed. The 7 groups of questions (factors) were safety awareness and competence, safety communication, organizational environment, management support, risk judgment and management reaction, safety precautions and accident prevention, and safety training

Optimization of the arsenic removal process from enargite based complex copper concentrate

Selective arsenic extraction from enargite based complex concentrate from Copper Mine in Bor (Serbia), using sodium hypochlorite as a leaching agent, was investigated in this paper. The aim was to assess the optimal conditions for the most efficient arsenic removal from the investigated concentrate, based on factorial design applied to experimentally obtained data. Five important factors with three factor levels were used as the input variables and experimentally obtained arsenic extraction yield was taken as the output variable. The first and the second final order model equations were obtained. It was found that the leaching temperature had the strongest effect on the arsenic extraction. The strongest positive interaction was between the sodium hypochlorite molar concentration and the stirring speed during extraction

Influence of chalcopyrite structure on their leaching by sodium nitrate in sulphuric acid

During the chalcopyrite leaching by sodium nitrate and sulfuric acid solution, leaching rate decreases with increasing the time and a part of chalcopyrite mineral grains remains in the leach residue. In chalcopyrite concentrate, 95.5 % of chalcopyrite mineral occurs as in liberated grains, and the rest is in association with gangue minerals, which is very favorably from the aspect of hydrometallurgical treatment. Complex forms, like impregnations and complex intergrowths, do not exist. After experiments carried out, leaching of copper achieved 84 % at temperature 80 o C and time 240 min. In the all leach residues, 97 % chalcopyrite mineral grains occur as liberated with highly corroded surfaces. Therefore, the structural assembly of chalcopyrite grains is favorable and no reason to reduce the leaching rate in the final stage of reaction. Reason for this is elemental sulfur, which was formed during the reaction, precipitated at the particle surfaces, and slowed down the leaching rate in the final stage of leaching process. http://dx.doi.org/10.5937/metmateng1401053

Ternary Bi-Cu-Ni alloys – thermodynamics, characterization, mechanical and electrical properties

The Bi–Cu–Ni ternary system belongs to the group of potential Cu-Ni-based advanced lead-free solder materials for high temperature application. The paper shows results of the thermodynamic calculations using general solution model along the line with the molar ratio of Cu: Ni = 1:1. The experimental part shows thermal, structural, electrical and mechanical properties based on differential scanning calorimetry (DSC), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), electroconductivity and hardness measurements of the alloys selected in the section from bismuth corner with molar ratio Cu: Ni = 1:1, Cu: Ni = 3:1, and Cu: Ni = 1:3

Ispravka: Ekološki rizici i reciklaža nanomaterijala - aktuelna pitanja (2014, vol. 7, p. 1)

Editorial board of the 'Recycling and Sustainable Development' Journal in agreement with the authors of the article titled 'Nanomaterials environmental risks and recycling - actual issues' (D. Zivkovic, Lj. Balanović, A. Mitovski, N. Talijan, N. Strbac , M. Sokić, D. Manasijević, D. Minić, V. Ćosović), which was published in this journal vol. 7 in 2014 (p. 1-8), made the decision to do correction of article because of a perceived serious oversights (based on check out by CEON). Oversight is reflected in inadequate citing a reference, or omission of reference from which the text used by individual states, as well as the duplication of certain references. The necessary correction refers to the parts of the article which reference source is not adequately specified and updates the list of references, in accordance with prescribed procedure.Uredništvo časopisa 'Reciklaža i održivi razvoj' je u dogovoru sa autorskim timom preglednog rada pod nazivom ' EKološki rizici i reciklaža nanomaterijala - aktuelna pitanja ' (D. Živković, Lj. Balanović, A. Mitovski, N. Talijan, N. Štrbac, M. Sokić, D. Manasijević, D. Minić, V. Ćosović), koji je publikovan u ovom časopisu vol.7 iz 2014. godine (str.1-8), donelo odluku da se zbog uočenog ozbiljnog previda (na osnovu provere CEON-a), koji se ogleda u neadekvatnom citiranju jedne reference, odnosno izostavljanju reference iz koje su korišćeni pojedini tekstualni navodi, kao i dupliranja pojedinih referenci, izvrši neophodna ispravka onih delova rada u kome pomenuti referentni izvor nije adekvatno naveden, kao i ispravke u listi referenci, a u skladu sa propisanom procedurom

Ekološki rizici i reciklaža nanomaterijala - aktuelna pitanja

Nanotechnologies are being spoken of as the driving force behind a new industrial revolution. Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. The size of nanoparticles allows them to interact strongly with biological structures, so they present potential human and environmental health risk. Nanometer size presents also a problem for separation, recovery, and reuse of the particulate matter. Therefore, industrial-scale manufacturing and use of nanomaterials could have strong impact on human health and the environment or the problematic of nanomaterials recycling. The catch-all term ''nanotechnology' is not sufficiently precise for risk governance and risk management purposes. The estimation of possible risks depends on a consideration of the life cycle of the material being produced, which involves understanding the processes and materials used in manufacture, the likely interactions between the product and individuals or the environment during its manufacture and useful life, and the methods used in its eventual disposal. From a risk-control point of view it will be necessary to systematically identify those critical issues, which should be looked at in more detail. Brief review of actual trends in nanomaterials environmental risks and recycling is given in this paper.Nanotehnologije se smatraju pokretačkom snagom nove industrijske revolucije. Nanonauka je tokom poslednje decenije značajno evoluirala od nauke koja se isključivo razvijala u laboratorijskim uslovima, do njene aplikacije u primenjenim tehnologijama. Trenutno, nanomaterijali se koriste u širokom spektru komercijalnih proizvoda kao što su elektronske komponente, sportska oprema, kreme za sunčanje i u biomedicinske svrhe. Veličina nanočestica omogućava im snažnu interakciju sa biološkim strukturama, tako da nanočestice predstavljaju potencijalni rizik po životnu sredinu i zdravlje ljudi. Nanometar kao veličina takođe predstavlja problem za separaciju, reciklažu i ponovno korišćenje nanočestica. Dakle, proizvodnja nanomaterijala u industrijskim razmerama i njihova primena mogli bi imati značajan uticaj na zdravlje ljudi i životnu sredinu ili stvorili probleme pri reciklaži. Sveobuhvatni termin 'nanotehnologija' nije dovoljno precizan kada se radi o upravljanju rizicima. Procena mogućih rizika zavisi od razmatranja životnog ciklusa materijala koji se proizvodi, a koji uključuje razumevanje procesa i materijala koji se koriste u proizvodnji, verovatne interakcije između proizvoda i pojedinaca ili životne sredine tokom proizvodnje nanomaterijala i njegovog životnog ciklusa, kao i metoda koje se koriste za njihovo konačno odlaganje. Sa stanovišta kontrole rizika, neophodno je identifikovati kritične faze, koje je neophodno detaljno istražiti. Pregled aktuelnih trendova ekoloških rizika i reciklaži nanomaterijala prezentovan je u ovom radu