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Removal of copper from aqueous solutions by low cost adsorbent-Kolubara lignite
No full textSerbian lignite from "Kolubara" deposit was used as a low cost adsorbent for removal of copper ions (Cu2+) from aqueous solutions. Lignite was subjected to the elementary and technical analysis as well as BET and FTIR analysis due to complete characterization. Basic comparison between lignite and activated carbon was also done. As a method, batch adsorption procedure was applied. Adsorption efficiency was studied as a function of the initial metal concentration, pH of the solution, contact time, and amount of the adsorbent. Optimum removal of copper ions was achieved at pH values of 5.0. About 90% of copper cations were removed in 5 min of contact time from the solution with the lowest copper concentration (50 mg Cu2+/l) regardless adsorbent amount, while the same effect of adsorption was achieved in 60 min in case of solutions with higher concentrations of copper. It was concluded that the effect of adsorbent amount on adsorption kinetics is evident but not crucial. It was proved that the experimental results of copper adsorption fit well to a Langmuirian type isotherm which was used to describe monitored adsorption phenomena. The calculated adsorption capacities of lignite for copper adsorption decrease with increasing adsorbent amount. The study proved that tested lignite is very efficient adsorbent material, especially in case of low copper concentration in aqueous solution where the usual methods are either economically unrewarding or technically complicated. This behavior can be explained by FTIR spectrum despite a small specific surface area of lignite. Namely, many bands (peaks) are attributed to the functional groups that they are involved in chemisorption and ionic exchange, basic mechanisms of copper adsorption
Preparation and characterization of zinc-exchanged montmorillonite and its effectiveness as aflatoxin B-1 adsorbent
No full textA zinc-exchanged montmorillonite (Zn-MONT) was prepared from a natural montmorillonite (MONT) and the adsorption of aflatoxin B-1 (AFB(1)) was investigated at pH 3 and 7. Characterization of Zn-MONT was done by determination of chemical composition, the point of the zero charge (pH(pzc)), thermal (DTA/TGA/DTG) and X-ray powder diffraction (XRPD) analysis. Adsorption of AFB(1) (C-0 = 4 ppm) by Zn-MONT, at different solid/liquid ratios (10, 1 and 0.5 g L-1), at pH 3 or 7, showed that its adsorption was high (over 96%) and independent of pH, similar to MONT. No desorption of AFB(1) from MONT-AFB(1) and Zn-MONT-AFB(1) complexes occurred at pH 6.5, suggesting strong binding of AFB(1) by both adsorbents. Furthermore, AFB(1) adsorption by Zn-MONT followed a nonlinear (Langmuir) type of isotherm at pH 3 with a calculated maximum capacity of 60.17 mg g(-1). The stability of MONT-AFB(1) and Zn-MONT-AFB(1) complexes was evaluated by calculating the binding energies between AFB(1) and metal cations using quantum chemical methods. The evaluated interaction energies of AFB(1) with hydrated Zn2+, Mg2+, and Ca2+ cations showed that the strongest interaction was the interaction of the Zn2+ system, -70.2 kcal mol(-1), whereas energies for Mg-2 and Ca2+ systems were -68.8 and -62.9 kcal mol(-1), respectively. The results indicate that Zn-MONT can be suitable for potential practical application as both, an antibacterial and an aflatoxin binding agent
Correlation between microstructure, phase composition and mechanical properties of thermo-insulation bonding agents based on waste material
No full textKonstrukcioni kompoziti - termo-izolaciona i/ili visoko-temperaturna veziva u kojima je leteći pepeo, kao potencijalno štetna materija za okolinu, kombinovan sa običnim i vatrostalnim cementom predstavlja jednu sasvim novu mogućnost za reaplikaciju ovog otpadnog materijala. U ovoj studiji, ispitivana su veziva spravljena na bazi dve vrste letećeg pepela dobijenog procesom sagorevanja uglja i dve vrste cementa - obični Portland cement i visoko-aluminatni cement. Promena u mineralnom sastavu kompozita uslovljena povećanjem temperature je analizirana pomoću XRD metode. Mikrostrukturne promene ispitivanih kompozita su utvrđene na osnovu rezultata skening-elektronske mikroskopije (SEM). Makro performanse - mehanička svojstva ispitivanih veziva su povezana sa promenama koje se dešavaju u mikrostrukturi materijala. Ispitivana veziva imaju odlične vrednosti pritisne čvrsoće, a SEM i XRD analiza je ukazala i na potencijalno dobra termo-izolaciona i vatrostalna svojstva ovih materijala.Building composites - thermo-insulating and/or high-temperature resistant bonding agents in which fly ash, as potentially environmentally harmful waste material, is combined with ordinary and refractory cement is new option for reapplication of this waste material. In this study, investigated bonding agents were based on two types of fly ashes from coal combustion process and cements - ordinary Portland cement and highaluminate cement. Change of mineral phase composition of the composites with increasing temperature was analyzed by means of XRD method. Microstructural changes within investigated composites were investigated by means of scanning electron microscopy (SEM). Macro-performance - mechanical properties of the investigated bonding agents was finally correlated with its microstructure. The investigated bonding agents showed excellent compressive strength, while SEM and XRD analysis indicated its valuable refractory and thermo-insulation properties
The effect of different collectors on recovery of copper and precious metals of the ore body Tenka 3
No full textU ovom radu prikazan je deo tehnoloških ispitivanja koja su obavljena sa ciljem definisanja optimalnih uslova flotacijske koncentracije rude ležišta Tenka 3 - Severni revir, rudnika bakra Majdanpek. Dati prikaz odnosi se na ispitivanje uticaja kolektora NaIPX, 3418A i AP5500 kao i pH vrednosti pulpe na pojedine tehnološke pokazatelje (iskorišćenja bakra i plemenitih metala) procesa osnovnog flotiranja. Utvrđeno je da se generalno najbolja iskorišćenja bakra i zlata u osnovnom koncentratu bakra postižu primenom kombinacije kolektora 3418A i AP5500, dok se najbolja iskorišćenja srebra u osnovnom koncentratu bakra postižu primenom natrijum izopropil ksantata. Pored toga, veća iskorišćenja zlata i srebra dobijena su pri nižim pH vrednostima pulpe, dok, s druge strane, nije uočena jasna zavisnost iskorišćenja bakra od pH vrednosti pulpe u ispitivanom opsegu pH (10,0 - 11,5).This work presents a part of technological testing that were conducted in order to define the optimum conditions of flotation concentration of the ore from the deposit Tenka 3 - North Mining District, Majdanpek copper mine. Provided description refers to testing the effect of collectors NaIPX, 3418 and AP5500 as well as the pH value of pulp to the certain technical indicators (recovery of copper and precious metals) of the rough flotation process. It was found that generally the best recoveries of copper and gold in the basic copper concentrate are obtained using a combination of collectors 3418 and AP5500, while the best silver recovery in the basic copper concentrate is obtained using the sodium isopropyl xanthate. In addition, higher recoveries of gold and silver were obtained at lower pH value of pulp, while, on the other hand, a clear dependence of copper recovery on pH value was not observed in tested pH range (10.0 to 11.5)
Kinetics and mechanism of sphalerite leaching by sodium nitrate in sulphuric acid solution
No full textInterest for application of hydrometallurgical processes in a processing of complex sulphide ores and concentrates has increased in recent years. Their application provides better metal recoveries and reduced emission of gaseous and toxic ageneses in the environment. The kinetics and mechanism of sphalerite leaching from complex sulphide concentrate with sulphuric acid and sodium nitrate solution at standard conditions was presented in this paper. The influences of temperature and time on the leaching degree of zinc were investigated and kinetic analysis of the process was accomplished. With temperature increasing from 60 to 90oC, the zinc leaching increased from 25.23% to 71.66% after 2 hours, i.e. from 59.40% to 99.83% after 4 hours. The selected kinetic model indicated that the diffusion through the product layer was the rate-controlling step during the sphalerite leaching. The activation energy was determined to be 55 kJ/mol in the temperature range 60-90oC. XRD, light microscopy and SEM/EDX analyses of the complex concentrate and leach residue confirmed formation of elemental sulphur and diffusion-controlled leaching mechanism
Zircon-based coating for the applications in Lost Foam casting process
No full textU ovom radu je istraživana mogućnost dobijanja novih vatrostalnih premaza na bazi cirkona koji bi imali primenu u livarstvu. Optimizacija sastava premaza kontrolisana reološkim svojstvima postignuta je primenom različitih komponenata premaza, naročito primenom novog veziva na bazi suspenzije i variranjem načina spravljanja premaza. Čestice cirkonskoh praha veličine 25×10-6 m su korišćene kao ispuna. Uzorak cirkona ispitivan je pomoću sledećih metoda: difrakcija X-zraka, diferencijalna termalna analiza i mikroskopija. Oblik i veličina zrna su analizirani pomoću računarskog programa za analizu slike OZARIA 2.5. Pokazano je da primena ovih premaza na bazi vode i alkohola ima pozitivan uticaj na kvalitet površine, tj. na strukturne i mehaničke karakteristike odlivaka livenog gvožđa koji su dobijeni metodom livenja u peščane kalupe i pomoću isparljivih modela (Lost Foam metoda livenja).In this work, a possibility to develop a new zircon-based refractory coating for casting applications was investigated. Optimization of the coating composition with controlled rheological properties was attained by application of different coating components, particularly by application of a new suspension agent and by alteration of coating production procedure. Zircon powder with particle size of 25×10-6 m was used as filler. The zircon sample was investigated by means of X-ray diffraction analysis, diffraction thermal analysis and polarized microscopy. The shape and grain size were analyzed using OZARIA 2.5 software. It was shown that application of this type of water-alcohol-based coating had a positive influence on surface quality, structural and mechanical properties of the castings of cast iron obtained by pouring into sand molds by means of the expandable patterns method (Lost Foam casting process)
Possibilities for treatment of non-standard copper concentrates and environmental protection
No full textProblemi koji se odnose na industrijsko zagađenje, iz godine u godinu postaju sve intezivniji i značajniji, kako na lokalnom, tako i na globalnom nivou. Osnovni razlog su emisije različitih zagađujućih materija koje nastaju kao posledice industrijskih aktivnosti. Problemi koji nastaju tokom ovih aktivnosti su zagađenje voda, zagađenje vazduha, stvaranje opasnog otpada itd. Priroda emisije i uticaj industrije na sredinu, u velikoj meri zavisi od specifičnosti same industrije. Tehnologija pirometalurškog tretmana koncentrata bakra po konvencionalnom postupku, koja se još uvek koristi u pogonima Topionice u Boru, dovela je do značajne degradacije stanja životne sredine u Boru i okolini. Smanjenje koncentracije bakra u domaćim rudnim ležištima dovela je do neophodnosti prerade rude sa oboda već eksploatisanih rudnih tela u kojima je povećana koncentracija štetnih primesa i pratioca bakra, u prvom redu: Zn, Pb, As, Cd, Hg, Ni, i drugih. U regionu Bora i okoline, ova problematika postaje sve značajnija sa stanovišta buduće ekstrakcije bakra iz domaćih koncentrata. Naime, u pojedinim, još uvek neeksplatisanim, rudnim nalazištima u okolini Bora se nalazi velika količina bakra, ali sa povišenim sadržajem štetnih komponenti.Recently, the problems relating to the industrial pollution have become more intensive and important at local as well as global level. The primary reason is an emission of polluting substances that appear as a consequence of various industrial activities. These activities produce the whole range of harms to the environment such as: water pollution, air pollution, hazardous waste production etc. The scope of emission of pollutants and industrial affect on the environment depend on specific characteristics of various industries. Pyrometallurgical treatment of copper concentrates, a conventional technological process, still used in the Copper Smelter in Bor, caused serious damages in the environment (in Bor as well in the region). In addition, the decrease of a copper content in domestic row minerals led to the necessity of treatment ores from the periphery (already exploited mineral ores) with an increased concentrations of harm components and metals tied to copper; first of all, Zn, Pb, As, Cd, Hg, Ni and others. In the Bor region this problem has become more important in regard to the future extraction of concentrates from domestic sources. Namely, in some copper minerals, recently discovered and, hence, not exploited, a significant amount of copper with higher contents of pollutants is present
Influence of mechanochemical activation on the sintering of cordierite ceramics in the presence of Bi2O3 as a functional additive
No full textDue to its outstanding electrical characteristics, such as the low temperature expansion coefficient, low dielectric constant and good mechanical properties, cordierite, 2MgO center dot 2Al(2)O(3)center dot 5SiO(2), is a very attractive high-temperature ceramic material. In order to accelerate the process of sintering, 2.50 mass% Bi2O3 has been added to the starting mixtures. Liquid phase sintering caused by the presence of bismuth-oxide lowers the temperature of cordierite formation. The mechanical activation of the starting mixtures (0-56 min in vibro-mill) additionally lowers sintering temperatures. The sintering process was performed at 1200, 1300, 1350 and 1400 degrees C, for 2 h. The particle size analysis (PSA) was employed in order to determine the changes in the particle size of the mechanically treated powders. The phase composition of the starting powders and sintered materials was analyzed by the X-ray diffraction method. Furthermore, scanning electron microscopy (SEM) was used in the analysis of the powder morphology
Structural features of two novel alluaudite-like arsenates Cd1.16Zn2.34(AsO4)(1.5)(HAsO4)(H2AsO4)(0.5) and Cd0.74Mg2.76(AsO4)(1.5)(HAsO4)(H2AsO4)(0.5)
No full textTwo new compounds, Cd1.16Zn2.34(AsO4)(1.5)(HAsO4)(H2AsO4)(0.5) (1) and Cd0.74Mg2.76(AsO4)(1.5)-(HAsO4)(H2AsO4)(0.5) (2), have been prepared hydrothermally. Their crystal structures consist of chains of edge-sharing M1O(4)(OH0.5)(2), M1aO(4)(OH0.5)(2), M2O5(OH0.5), and M(2)aO(5)(OH0.5) octahedra (M1, M1a = Zn, Cd; M2, M2a = Zn for 1, and M1, M1a = Mg, Cd; M2, M2a = Mg for 2) that are stacked parallel to (1 0 1) and are connected by the [(AsO4)(0.5)(AsO3(OH))(0.5)](2.5-) and [(AsO4)(0.5)(AsO2(OH)(2))(0.5)](2-) tetrahedra. These chains produce two types of channels parallel to the c-axis. Cd atoms are located in channels 2, while in channels 1 are situated hydrogen atoms of O-H groups. The infrared spectra clearly show the presence of broad O-H stretching and bending vibrations centred at 3236, 2392 1575 and 1396 cm(-1) in (1), and 3210, 2379 1602 and 1310 cm(-1) in (2). The O-H stretching frequency is in good agreement with O center dot center dot center dot O distances. Furthermore, structural characteristics of compounds with similar alluaudite-like structures were discussed
Electrical properties of mechanochemically activated cordierite ceramics
No full textThree-component oxide mixtures were prepared containing MgO, Al (2) O (3) and SiO (2) in a 2 : 2 : 5 ratio with addition of 10% Bi (2) O (3). The mixtures were mechanically activated in a range from 5 to 240 min in a mill with ceramic balls, and sintered in the range 1173-1573 K. In order to determine the structure transformations, sintered products were analyzed by the XRD method. The goal of the research was to find the possible correlation between process parameters and functional properties of the cordierite-based ceramic materials. Quantitative measures of the functional sample properties, capacity (C (c) ) and electrical resistance (R (rho)), as well as of dielectric loss (tg delta) were used. The results obtained prove that there is a correlation between mechanical activation and properties of cordierite ceramics