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

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

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

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

Efficiency of the process of cryogenic air separation into the components

The separation process of atmospheric air into its components by means of cryogenic low-pressure procedure, which takes place in the Oxygen plant in the Copper Mining and Smelting Complex, yields various products of different quantities and purities. Proper assessment of the energy consumption, hence assignments production cost of individual products may present considerable problem. For that goal, the least invested technical operation was adopted as criteria, and was restrained for all costs of production and distribution of specific energy. Case study was carried out in the Oxygen factory by monitoring producing parameters for the process in the 2007 year. Based on the monitoring of production parameters and their costs for 20 months in the period 2004-2005, correlation equations for power consumption in the total monthly amount and per mass of produced gaseous oxygen were created. The energy and exergy efficiency of the air separation process into the components are expressed as the ratio of input and useful energy and exergy of the process. On the basis of the adopted criteria, the assignments of energy consumption and production costs for cryogenic air separation process into the components are as follows: 82.59% for gaseous oxygen, 14.04% for liquid oxygen, 1.39% for gaseous nitrogen and 1.98% for liquefied nitrogen. The air separation efficiency is achieved in the amount of energy 0.0872-0.1179 and exergy 0.0537-0.1247. Power consumption per mass of the products in 2007 year is 1325.059 kWh/t of liquid oxygen, 828.765 kWh/t of liquid nitrogen, 429.812 kWh/t of gaseous oxygen and 309.424 kWh/t of nitrogen gas. Production costs of the technical gases at the dawn of the factory are: 6730.69 RSD/t of liquid oxygen, 4209.74 RSD/t of liquid nitrogen, 2183.25 RSD/t of gaseous oxygen and 1571.73 RSD/t of gaseous nitrogen

Thermodynamic and kinetic analysis of the polymetallic copper concentrate oxidation process

This paper presents the experimental investigation results of the polymetallic copper concentrate oxidation process with the oxygen from the air. Concentrate characterization included chemical analysis, X-ray diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), and light microscopy. Chemical analysis and EDXRF results showed that the investigated copper concentrate consisted mainly of copper, iron and sulphur, with small amounts of zinc, lead, arsenic and other minor elements. XRD analysis showed that metals were bonded to sulphur in sulphide minerals: chalcopyrite, pyrite, luzonite, sphalerite and enargite. Those minerals were mutually bonded into aggregates, confirmed by light microscopy. The results of DTA/TG analysis were used for determining the mechanism of the oxidation process. Comparison between experimental data obtained by XRD, DTA/TG and data obtained from the phase stability diagrams, implied that the oxidation process of the investigated concentrate can be divided in two stages: the first stage consisted of sulphide oxidation reactions with the characteristic exothermal effects below 973 K while forming sulphates and oxysulphates, and the second stage, which consisted of sulphates and oxysulphates decomposition reactions and forming copper and iron oxides, with endothermal effects above 973 K. Kinetic studies were carried out in isothermal conditions in the temperature range (573–873) K. Calculations were done according to Sharp’s method of reduced half-time reaction. Calculated values for the activation energies were 82 kJ mol−1 for the initial stage of the oxidation process (up to 723 K), and 42 kJ mol−1 for the stage of the process where desulphurization degree reached 68–86 % for the oxidation temperatures 748 K and higher. Calculated activation energy values indicated that the reaction of oxidation is a chemically controlled reaction

Thermodynamic and kinetic analysis of the polymetallic copper concentrate oxidation process

This paper presents the experimental investigation results of the polymetallic copper concentrate oxidation process with the oxygen from the air. Concentrate characterization included chemical analysis, X-ray diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), and light microscopy. Chemical analysis and EDXRF results showed that the investigated copper concentrate consisted mainly of copper, iron and sulphur, with small amounts of zinc, lead, arsenic and other minor elements. XRD analysis showed that metals were bonded to sulphur in sulphide minerals: chalcopyrite, pyrite, luzonite, sphalerite and enargite. Those minerals were mutually bonded into aggregates, confirmed by light microscopy. The results of DTA/TG analysis were used for determining the mechanism of the oxidation process. Comparison between experimental data obtained by XRD, DTA/TG and data obtained from the phase stability diagrams, implied that the oxidation process of the investigated concentrate can be divided in two stages: the first stage consisted of sulphide oxidation reactions with the characteristic exothermal effects below 973 K while forming sulphates and oxysulphates, and the second stage, which consisted of sulphates and oxysulphates decomposition reactions and forming copper and iron oxides, with endothermal effects above 973 K. Kinetic studies were carried out in isothermal conditions in the temperature range (573–873) K. Calculations were done according to Sharp’s method of reduced half-time reaction. Calculated values for the activation energies were 82 kJ mol−1 for the initial stage of the oxidation process (up to 723 K), and 42 kJ mol−1 for the stage of the process where desulphurization degree reached 68–86 % for the oxidation temperatures 748 K and higher. Calculated activation energy values indicated that the reaction of oxidation is a chemically controlled reaction

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