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Investigation of the optimal technology for copper leaching from old flotation tailings of the copper mine Bor (Serbia)
No full textThis work aimed to investigate optimal leaching technology for copper extraction from old flotation tailings of the Copper Mine Bor. The leaching degree of copper after leaching with sulphuric acid at 80 degrees C was 50%, the maximal leaching degree was achieved after 30 minutes. Then, old flotation tailings were leached with adapted moderately thermophilic acidophilic bacteria in a bioreactor at 40 degrees C. Maximal leaching degree of 84% was achieved after nine days of the experiment. The third leaching experiment was conducted with biogenic lixiviant obtained by bacterial oxidation of the ferrous iron (concentration of Fe3+ 1300 mgL(-1), pH 2.14). Biogenic lixiviant with ferric sulphate was then used in the leaching experiment at 80 degrees C. Maximal leaching degree was 78%, and it was achieved after five minutes. Results of the leaching experiments show that the most efficient technology for copper recovery from the old flotation tailings of the Copper Mine Bor was leaching with biogenic lixiviant
Adjusting pH PZC value during and after adsorbent preparation
No full textPoint of zero charge (PZC) is one the most valuable parameter of adsorbent preparation process, in
wastewater management. Although, this parameter may be determined measuring the electrokinetic potential (zetta
potential) as the function of pH; material engineers oftenrely on pH PZC value which may be easily determined and
can give usefuladsorbent properties duringexploitation. Samples from previous study are characterized and their pH
PZC values are determined. Provided results are such intriguing since they brought conclusions that those values can
be explained by process parameters of the particular sample preparation. Sample marked as Cr2O3/Fe3O4/EVer have
lowest pH PZC value (4.75) and sample marked as MnFe2O4/EVer highest pH PZC value (7.47). Another study in this
paper showed that pH PZC value could be easily increased or decreased by simple base or acid treatment, respectfully.
As expected, samples treated with bases or prepared in alkali medium have greater adsorption capacity towards
cation species, up to 20 % more than base material in the case MnFe2O4/EVer
Uticaj krupnoće materijala u ulaznoj rudi i prozvodu mlevenja na vrednost bondovog radnog indeksa krečnjaka „Carmeuse“-Doboj
No full textU ovom radu prikazani su rezulati određivanja Bondovog radnog indexa krečnjaka iz postrojenja za preradu krečnjaka “Carmeuse”- Ševarlije-Doboj. Bondov radni index je određivan na klasi krupnoće - 22+16mm, koja je jedan od proizvoda koji se dobija u postrojenju. Ova klasa je trebalo da predstavlja polaznu sirovinu za postupak mlevenja i proizvodnju punioca pa je stoga bilo bitno da se odredi Bondov radni index kao jedan od najvažnijih parametara usitnjavanja za bilo koju rudu
Ponašanje mikrolegiranog čelika u uslovima dejstva kavitacije
No full textMikrolegirani čelici se primenjuju za izradu različitih elemenata opreme u metalurgiji i rudarstvu. Zbog zahteva koje oprema treba da ispuni i sigurnosti koju treba da obezbedi, vrše se različita ispitivanja ove vrste konstrukcionih materijala. U radu je ispitivano ponašanje mikrolegiranog čelika S355M u uslovima dejstva kavitacije. Za ispitivanje je primenjena ultrazvučna vibraciona metoda sa stacionarnim uzorkom. Praćena je promena mase uzoraka u funkciji vremena dejstva kavitacije. Morfologija oštećenja površine analizirana je primenom skenirajuće elektronske mikroskopije. Utvrđen je mehanizam nastajanja i razvoja oštećenja površine uzoraka pod dejstvom kavitacije. Procenjena je mogućnost primene ove vrste materijala u rigoroznim uslovima eksploatacije koji su prisutni u metalurškim procesima
Preparation of fluorapatite-based nanophosphorus doped with Pr3+ ions for bio-medical applications
No full textLuminescentni nanokristali (nanofosfori) na bazi fluorapatita (FAP-a) dopirani elementima retkih zemalja idealni su kontrastni agenti za bio-medicinske primene, kao što su detekcije, snimanja, praćenja i terapije ćelija kancera. Kancer je jedna od najčešćih bolesti modernog doba čiji uspeh lečenja zavisi od rane dijagnostike i neinvazivnog tretmana. Luminescentne nanočestice mogu uneti inovativnu paradigmu u lečenje kancera kombinovanjem biosnimanja, dijagnostike i tretmana. Za studije fluorescentnih biosnimanja nanokristali fluorapatita dopirani retkim zemljama kao kontrastni agenti pružaju značajne prednosti u vidu velikih kontrasta i dugotrajnosti luminescencije, i što je još važnije visoke biokompatibilnosti, netoksičnosti i bioaktivnosti. Glavni ciljevi ove doktorske disertacije su sinteza novih luminescentnih multifotonskih bionanomaterijala na bazi fluorapatita dopiranih jonima prazeodimijuma (Pr3+), njihova karakterizacija i evaluacija primene za fluorescentna biosnimanja kancera. Sintezom nanoprahova u umerenim uslovima metodom ko-precipitacije, a potom sušenjem na 110 oC i kalcinacijom na temperaturama od 700 i 1000 oC očekuje se pronalaženje najboljih uslova za dobijanje novih nanofosfora koji bi našli i različite bio-medicinske primene u oblasti fluorescentnih biosnimanja. Proučavane su tri vrste PrFAP nanokristala, sa 0,1%, 0,5% i 1% atomskih procenta Pr3+, zajedno sa nedopiranim FAP kontrolnim uzorkom. Nivoi energije aktivator jona Pr3+ sadrže metastabilna multipletna stanja koja nude mogućnosti efikasnih emisionih linija u više boja u FAP nanokristalima, kao i u infracrvenoj i ultravioletnoj oblasti spektra. Metodom ko-precipitacije na sobnoj temperaturi (25 oC), a potom sušenjem na 110 oC, sintetisani su monofazni heksagonalni nanokristali PrFAPs nepravilnog sfernog oblika. Termičkom analizom sintetisanih uzoraka, na osnovu detektovanih temperaturnih opsega procesa dekarbonacije i dehidroksilacije, utvrđene su temperature kalcinacije od 700 i 1000 oC. Termička analiza i karakterizacija uzoraka su pokazale da Pr3+ joni dovode do stabilizacije FAP strukture na višim temperaturama, što je pripisano unosu lantanoidnih jona sa specifičnim magnetnim osobinama u sistem i stvaranju jačih privlačnih sila sa O2- anjonima. Nanokristali sušeni na 100 oC i kalcinisani na 1000 oC, zbog prisustva defekata kristalne rešetke koji zadržavaju emisiju Pr3+ jona, nisu pokazali luminescentne karakteristike od značaja za primene u medicinskim fluorescentnim biosnimanjima. Kalcinacijom uzoraka na 700 oC izrađen je novi tip aktiviranih fluorapatitnih nanokristala dopiranih prazeodimijumom (PrFAPa) sa ekscitaciono-emisionim profilima u vidljivom delu spektra. Fizičko-hemijska karakterizacija potvrdila je sferne kristale heksagonalne strukture do nanometrske veličine od oko 20 nm. Kvantno-hemijske kalkulacije predvidele su da se joni Pr3+ ugrađuju u kristalnu rešetku FAP nanokristala na položaju Ca2 (6h), što je praćeno deformacijama pozicije F- jona. Pretpostavljeni mehanizam supstitucije je jedan jon Pr3+ za jedan Ca2+, s delimičnom supstitucijom anjona F– sa O2– i OH– i stvaranjem vakansi usled postizanja neutralnosti sistema. Rezultati in vitro biokompatibilnosti i hemokompatibilnosti pokazali su da nanokristali PrFAPa nisu toksični za žive ćelije. Pored toga, internalizacija PrFAPa nanokristala od strane ćelija kancera kože (A431) i pluća (A549) je proučavana korišćenjem konfokalne mikroskopije i mikroskopije širokog polja zasnovane na fluorescenciji. Nanokristali pokazuju karakterističnu zelenu emisiju na 545 nm (3P0→3H5 tranzicija Pr3+ jona) i narandžastu emisiju na 600 nm (1D2→3H4), koje su korišćene za razlikovanje od pozadinske autofluorescencije ćelije. Studije dobijenih slika konfokalnom mikroskopijom u plavom, zelenom i crvenom kanalu su otkrile da nanokristali mogu da prepoznaju ćelijsku površinu i da se lepe za nju, ali nisu potvrdile ulazak nanokristala u ćelije. Mikroskopija širokog polja je detektovala emisione prelaze u zelenoj i narandžastoj boji i potvrdila da luminescentni signal dolazi iz unutrašnjosti ćelija. Korišćenjem rezonantne ekscitacije od 488 nm i emisije od 600 nm PrFAPa nanokristala, konfokalnom mikroskopijom ekstrahovan je signal fluorescencije iz unutrašnjosti ćelija kancera. Ortogonalne projekcije u 3D konfokalnim ravnima pokazuju da su nanokristali u stanju da uđu u ćelije kancera i da se raspoređuju po citoplazmi. Sveukupno, ovako dobijeni nanokristali PrFAPa su biokompatibilni i od testiranih uzoraka, aktivirani nanokristali dopirani sa 0,5% Pr3+ pokazuju najviše potencijala za primenu u medicinskim fluorescentnim biosnimanjima kao kontrastni agenti.Luminescent nanocrystals (nanophosphorus) based on fluorapatite (FAP) doped with rare earth elements are ideal contrast agents for biomedical applications such as cancer cell detection, imaging, tracking and therapy. Cancer is one of the most common diseases of the modern times whose success of the cure depends on early diagnosis and non-invasive treatment. Luminescent nanoparticles can bring an innovative paradigm into the treatment of cancer by combining bioimaging, diagnostics and treatment. Rare earth doped fluorapatite nanocrystals as contrast agents for studies of fluorescence bioimaging, offer significant advantages in terms of high contrasts and long-term luminescence, and more importantly high biocompatibility, non-toxicity and bioactivity. The main objectives of this doctoral dissertation are the synthesis of novel luminescent multiphoton bionanomaterials based on fluorapatites doped with praseodymium ions (Pr3+), their characterization and evaluation of their application for cancer fluorescence bioimaging. Synthesis of nanopowders under moderate conditions by the co-precipitation method, followed by dried at 110 °C and calcination at 700 and 1000 °C, is expected to find the best conditions for obtaining new nanophosphors that would find different bio- medical applications in the field of fluorescence bioimaging. Three types of PrFAP nanocrystals were studied, with 0,1%, 0,5%, and 1% atomic percentages of Pr3+, together with an undoped FAP control sample. Energy levels of the Pr3+ ion activator contain metastable multiplet states that offer the possibility of efficient multi-color emission lines in FAP nanocrystals as well as in the infrared and ultraviolet regions of the spectrum. Single-phase hexagonal nanocrystals PrFAPs of irregular spherical shape were synthesized by the method of co-precipitation at room temperature (25 oC) and then drying at 110 oC. Thermal analysis of the synthesized samples, based on the detected temperature ranges of the decarbonation and dehydroxylation processes, determined calcination temperatures of 700 and 1000 oC. Thermal analysis with characterization showed that Pr3+ ions lead to stabilization of the FAP structure at higher temperatures, which was attributed to the entry of lanthanoid ions with specific magnetic properties into the system and the creation of stronger attractive forces with O2- anions. Nanocrystals dried at 100 oC and calcined at 1000 oC, due to the presence of crystal lattice defects that quench the emission of Pr3+ ions, did not show luminescent characteristics of significance for applications in medical fluorescence imaging. Calcination of the samples at 700 oC produced a new type of activated praseodymium doped fluorapatite nanocrystals (PrFAPa) with excitation-emission profiles in the visible part of the spectrum. Physicochemical characterization confirmed spherical crystals of hexagonal structure up to a nanometer size of about 20 nm. Quantum-chemical calculations predicted that Pr3+ ions would be embedded in the crystal lattice of FAP nanocrystals at the Ca2 position (6h), which was followed by deformations of the F- ion position. The assumed substitution mechanism is one Pr3+ ion for one Ca2+, with partial substitution of F– anions with O2– and OH– and creation of vacancies due to achieving system neutrality. The results of in vitro biocompatibility and hemocompatibility showed that PrFAP nanocrystals were not toxic to living cells. In addition, the internalization of PrFAPa nanocrystals by skin (A431) and lung (A549) cancer cells was studied using fluorescence-based confocal microscopy and wide-field microscopy. The nanocrystals show characteristic green emission at 545 nm (3P0→3H5 transition of Pr3+ ion) and orange emission at 600 nm (1D2→3H4), which we use to discriminate from cell autofluorescence. Studies of the images obtained by confocal microscopy in the blue, green, and red channels revealed that nanocrystals could recognize the cell surface and adhere to it, but they did not confirm the entry of nanocrystals into the cells. The wide-field microscopy detected emission transitions in green and orange color, and confirmed that the luminescent signal was coming from inside the cells. Using resonant excitation of PrFAP nanocrystals at 488 nm and emission of 600 nm, confocal microscopy extracted the fluorescence signal from inside the cancer cells. Orthogonal projections across 3D confocal stacks show that the nanocrystals are able to enter the cells positioning themselves within the cytoplasm. Overall, the obtained PrFAPa nanocrystals are biocompatible and of the tested types, the 0,5% Pr3+ doped nanocrystals show the highest promise as a tracking nanoparticle probe for bioimaging applications
Sustainable mining towards accoplisihng circular economy principles
No full textToday human society is already witnessing rapid depletion of non-renewable ore resources. As the distribution of raw material resources globally is very off-balance, and preassure on environment as the consequence of ore exploatation is not negligible, reutilization and recycling of industrial side-streams gaining on importance. Finding new potentially anthropogenic resources of material (at first place critical raw materials) are inline with sustainable waste management goals, and in correlation with boundaries given by the circular economy principles. Side-streams from mines can become source for recovery of these materials. The aim of this paper was to analyze position of mining waste in correlation with circular economy principles, as well potential for implementation of them within extraction industry in the Republic of Serbia
Prediction model based on artificial neural network for pyrophyllite mechano-chemical activation as an integral step in production of cement binders
No full textThe optimal outputs of pyrophyllite mechano-chemical activation in an ultra-centrifugal mill performing under different technological conditions were determined by analytical modeling and verified via Artificial Neural Network in order to be employed in the production of cement-based binders. Cluster Analysis and Principal Component Analysis were utilized in assessment of the effect of activation process parameters on the activated pyrophyllite quality. Artificial Neural Network which performed with high prediction accuracy, i.e. 0.914 during the training period, was sufficient for precise prediction of activated pyrophyllite quality in a wide range of processing parameters. The probability of utilization of observed activation products was estimated through interrelation of technological parameters (mesh size sieve, activation period, specific energy consumption) and acquired characteristics of pyrophyllite (grain diameter, specific surface area). The optimal products singled out from each activation sequence were used as mineral additives in the mix-designs of four cement binders (cement replacement portion was 30%). Influence of activated pyrophyllite additions on the cement chemistry, mineral phase compositions and microstructures of the cement binders were monitored by instrumental techniques (DTA/TGA, XRD, SEM). Activated pyrophyllite showed characteristics of pozzolana as it slightly accelerated early stages of hydration, decreased cement hydration energy and increased the quantity of cement mineral alite at later hydration stages. Micron-sized crystalline foila characteristic for mechanically activated pyrophyllite formed micro-reinforcement within cement binder microstructure
Disposal of flying ash from thermal power plants
No full textThe problem of fly ash as a by-product of thermal power plants is an actual issue. This ash is extremely hazardous to the environment. It contains particles of extremely small diameter that are easily carried by the wind, and have many toxic elements and heavy metals. The scattered particles reach the water and soil, thus causing environmental contamination. Multiple solutions have been offered to remedy this serious problem, which relates not only to the environment (land, air and water) but also significantly affects the health of people living close to the thermal power plants. Remediation of ultra-fine particles spread by aeolian erosion reduces the potential for water and soil contamination as well as crops used by the population for nutrition, and thus for acute and chronic diseases found to be caused by fly ash pollution. The use of elemental sulfur, which is a secondary product of the oil refining process, in order to bind fly ash, manages waste, thus solving two environmental problems
Uticaj klimatskih promena na proces biološke rekultivacije rudničkih jalovišta
No full textPredviđene promene klime uticaće na čitav sektor rudarstva i kroz više faza životnog ciklusa rudnika. Uticaj klimatskih promena u fazi zatvaranja, rekultivacije i monitoringa životne sredine po prestanku rudarskih aktivnosti skopčan je sa različitim vrstama potencijalnih rizika, pa je stoga neophodno da mogući efekti klimatskih promena, kao i mere ublažavanja i prilagođavanja, budu uzeti u obzir još u ranoj fazi planiranja rudnika i ugrađeni u planska rešenja i procenu rizika
Modifikacija biomase za uklanjanje polutanata sa osvrtom na biočađ i imobilizovanu biomasu
No full textAntropogena aktivnost i industrijalizacija prave sve veći pritisak na životnu sredinu stvaranjem velikih količina otpadnih voda. Biomasa kao organski čvrsti otpad i obnovljivi izvor dobija na značaju u istraživanjima njene odgovarajuće primene. Biosorpcija se pojavljuje kao potencijalna alternativa postojećim konvencionalnim tehnologijama za uklanjanje i/ili povraćaj zagađujućih materija iz vodenih rastvora. Ovaj rad prikazujemoguće modifikacije biomase, u cilju povećanja sorpcionog kapaciteta, za uklanjanje polutanata iz voda sa posebnim osvrtom na biočađ i imobilizovanu biomasu