ritnms
Not a member yet
1551 research outputs found
Sort by
Krečnjak-mineralna sirovina u zaštiti životne sredine
No full textSa razvojem različitih industrija i uvođenjem novih tehnologija savremeno društvo se suočilo problemom zagađenja životne sredine. Paralelno sa poboljšanjem kvaliteta života i modernizacijom u svim sferama ljudskih aktivnosti, došlo je do ozbiljnog narušavanja i degradacije životnog i radnog prostora. Zbog toga je neophodno da se tokom primene određenih tehnologija koje zagađuju životnu sredinu koriste materijali koji mogu da smanje negativne efekte ili da ih u potpunosti eliminišu. Jedan od ekološki prihvatljivih materijala je krečnjak. Krečnjak je sedimentna karbonatna stena koja je izgrađena od kalcita, CaCO3, kao dominantnog minerala, uz neznatno prisustvo aragonita. Generalno se može reći da se pod pojmom krečnjak podrazumeva ona mineralna sirovina koja sadrži najmanje 50% CaCO3. Industrijske grane koje koriste ovu sirovinu doprinose očuvanju životne sredine imajući u vidu da su materijali na bazi krečnjaka ekološki prihvatljivi. Najveća primena krečnjaka je u oblasti građevinarstva za dobijanje maltera, betonskih mešavina, u proizvodnji raznih vrsta cementa, kreča i direktno u vidu drobljenog kamena različite krupnoće. Drugi važan korisnik je metalurgija, gde se krečnjak koristi u aglomeraciji, u visokim pećima i kod Besemerovog postupka topljenja čelika. Hemijska industrija, takođe, koristi značajne količine ove sirovine u industrijskoj proizvodnji azotnih jedinjenja, celuloze, papira, sode, hlornog kreča, karbida, gume i drugo. U poljoprivredi se krečnjak koristi za neutralizaciju kiselih zemljišta i kao dodatak stočnoj hrani. Velike količine krečnjaka nalaze svoju primenu u industriji šećera, kao i u staklarskaoj i keramičkoj industriji. Kada je zaštita životne sredine u pitanju, treba istaći primenu krečnjaka u odsumporavanju dimnih gasova koji nastaju u termoelektranama koje koriste ugalj. Istraživanja su pokazala da je sagorevanje uglja daleko najveći izvor emisije sumpor dioksida. Kako bi se sprečilo zagađenje vazduha, vode i zemljišta oksidima sumpora koji potiču iz dimnih gasova nastalih sagorevanjem uglja u termoelektranama primenjuje se nekoliko postupaka, a to su: odsumporavanje dimnih gasova (ODG), prečišćavanje uglja pre procesa sagorevanja (pranje uglja), gasifikacija uglja i sagorevanje uglja u fluidizovanom sloju. Postupci odsumporavanja dimnih gasova su našli veliku primenu, posebno krečno-mokri postupci prečišćavanja dimnih gasova po tehnologiji vlažnog krečnjaka, tzv. gips postupak. Studije su pokazale da je to najisplativiji postupak za našu zemlju, jer je bogata ležištima krečnjaka. Više od 90% postrojenja za odsumporavanje dimnih gasova u svetu radi po ovom principu. Razlog za to je visoka efikasnost, 90-95%, relativno niska potrošnju sorbenta tokom navedenog postupka, kao i mogućnost iskorišćavanja otpadnog produkta, odnosno gipsa
Study of mineralogical and physicochemical properties of samples of flotation tailings "Rudnik“ mine
No full textIn this study, two samples of flotation tailings from the ""Rudnik"" Mine (one from boreholes and
one from the surface) were examined. Various physical and chemical properties were analyzed, including gross
and hygroscopic moisture, specific mass, bulk density in both loose and compacted states, and specific weight.
Additionally, granulometric and chemical compositions were determined. A qualitative mineralogical analysis
was conducted using X-ray diffraction (XRD), along with the preparation of polished sections for optical and
SEM microscopy. Comprehensive physicochemical and mineralogical tests were performed to define all
parameters necessary for the valorization and recycling of flotation tailings from the "Rudnik" Mine
Kritični elementi EU i SAD šansa za razvoj geologije, rudarstva i nauke, na bazi primarnih i sekundarnih sirovina sa prostora Srbije i Balkana
No full textOvaj rad skreće pažnju na ozbiljnu nestašicu mineralnih sirovina na dva najveća i tehnološki najnaprednija tržišta, EU i SAD, koja su postala veoma zavisna od uvoza raznih mineralnih sirovina od velikog broja dobavljača širom sveta. Iz tog razloga, oba tržišta su svako za sebe, njihova velika potreba za sirovinama, bez kojih njihova industrija, odbrana i samo društvo ne mogu da funkcionišu, pretočila se u liste kritičnih elemenata, kao i u veliki broj istraživanja i studija koje pokušavaju da prevaziđu ovaj problem. U radu se takođe razmatraju dva domaća projekta (Reasoning i Ext-Min-Waste) koje finansira Fond za nauku Republike Srbije, u okviru kojih se sprovode istraživanja o reciklaži flotacione jalovine i mogućnostima valorizacije svih korisnih elemenata, kao i utvrđivanju potencijala za dobijanje građevinskog materijala iz ostataka, odnosno primeni principa „Nulti otpad“. Ovakva situacija u oblasti proizvodnje minerala u EU i SAD otvara mogućnosti za razvoj geologije i rudarstva širom sveta, uključujući i Srbiju i Balkan, između ostalog. Osvajanjem proizvodnje samo nekoliko nedostajućih minerala, bilo iz primarnih ili sekundarnih izvora, otvara se mogućnost pozicioniranja države i društva kao strateškog i dugoročnog partnera ovih zemalja
Application of grounded foam glass for removal of the brilliant green dye
No full textBrilliant green (BG), one of the most widely used dyes in the textile industry can cause serious problems for the ecosystem if is not removed from wastewater. This research investigates the possibility of BG removal using grounded foam glass (GFG). Foam glass is widely recognized for its exceptional thermal insulation properties, but it can be repurposed as an adsorbent. By utilizing its porous structure and surface characteristics, the study explores its potential for wastewater treatment, contributing to sustainable material applications and environmental protection. The results provide insight into the feasibility of using grounded foam glass in adsorption processes, promoting circular economy principles. Foam glass was produced using a glass cullet as a glass matrix and sugar beet factory lime, a CaCO3-rich waste, as a foaming agent. The mixture was pelletized and sintered at T= 800 ℃ for t= 30 min. The sample was characterized by SEM and ATR-FTIR techniques. The foam glass was grounded and sieved to a size below 0.5 mm. Batch adsorption experiments were conducted with an adsorbent dosage of 2 g/L, at room temperature, using initial BG concentrations of 25-500 mg/L for 24 hours. The adsorption data were evaluated using the Langmuir, Freundlich, and Sips adsorption isotherms. The maximum adsorption capacity obtained by Sips model was found to be 206 mg/g. The results indicate that foam glass, in addition to its thermal insulation properties, represents a promising solution for dye removal from contaminated water. Consequently, further investigations will be conducted to explore its potential applications
Environmental Impacts of Microplastics in Contaminated Soils: Potential Implications for Cu, Mn, and Sr Phytoremediation
No full textMicroplastics (MPs) are widespread environmental pollutants and have emerged as a growing global concern. In soil ecosystems, MPs frequently coexist with potentially toxic elements (PTEs), yet their combined effects on soil–plant interactions and phytoremediation processes remain insufficiently explored. This field-based study investigated the occurrence of MPs in urban soils from four Serbian cities and assessed their influence on the uptake of PTEs - copper (Cu), manganese (Mn), and strontium (Sr) - by Capsella bursa-pastoris (L.) Medik. MPs were extracted from soil using an optimized density separation method, while total (aqua regia) and phytoavailable (EDTA-extractable) fractions of PTEs were quantified in both soils and plant tissues. Maximum MPs abundance was recorded in Bor — 500 ± 100 MPs kg-1.The highest total concentrations of Cu (516.14 µg g⁻¹), Mn (553.46 µg g⁻¹), and Sr (173.69 µg g⁻¹) were detected in soils from Bor. The geoaccumulation index (Igeo) indicated moderate to heavy contamination levels. CuEDTA accounted for UP to 50.7% of CuAR, MnEDTA for 34.4% of MnAR, and SrEDTA 27.3% of SrAR. After the uptake, C. bursa-pastoris primarily translocated the elements to the aerial parts, indicating shoot accumulation as the dominant strategy. Principal component analysis (PCA) revealed distinct clustering of samples by city, while Spearman correlation analysis highlighted significant associations between MPs and PTEs mobility in the soil-plant system. Strongest correlations were found between MPs phytoavailable Cu fraction (ρ =+0.49) and Cu content in shoots (ρ =+0.56). The highest BCF values were determined for Sr, ranging from 2,40 (SM) to 5,41 (BO). PTEs were mainly transferred to the shoots. TF range for Cu was 0.54 (BO) – 1.48 (VR), 0,68 (BO) to 1,42 (VR) for Mn, and 0,76 (BO) to 1,34 (VR) for Sr. Strong correlations among MPs abundance and Cu mobility and accumulation in shoots (ρ = +0.56), and Sr bioaccumulation potential (BCF up to 5.41), highlight the role of MPs in modifying element transfer within urban soil–plant systems and consequent phytoremediation potential
Mechanical Performance and Atomistic Modeling of polycrystal NiFeCrMn Alloy Under High-Temperature Tensile Loading
No full textHigh-entropy alloys (HEAs) have emerged as promising materials for nuclear applications due to their exceptional mechanical properties, thermal stability, and resistance to radiation damage. Among these, FCC Ni-based high entropy alloys are particularly notable for their high strength, ductility, and structural integrity, making them ideal for extreme environments such as nuclear reactors.
This study examines the mechanical performance of a NiFeCrMn alloy under tensile loading using a combination of atomistic computational modeling and experimental validation. Analyses were conducted on both single-crystal and polycrystalline samples across room-temperature and high-temperature conditions to explore the effects of grain structure and crystallographic orientation on deformation mechanisms. A refined Embedded Atom Method (EAM) potential, optimized for NiFeCrMn alloys, was employed to ensure accurate representation of the alloy’s behavior, with simulations closely replicating experimental conditions for direct comparison of stress-strain responses.
Key findings highlight the influence of temperature on ultimate stress, grain structure on twin formation, and crystal orientation on defect propagation during deformation. The study underscores the alloy’s ability to maintain mechanical integrity under high-temperature conditions, advancing the understanding of HEAs for demanding applications, particularly in nuclear energy systems.
This work demonstrates the synergy between computational and experimental approaches, offering a robust methodology for evaluating advanced materials under extreme conditions
Analysis and automatic defect detection on cast parts using deep learning
No full textДетекција дефеката код ливених делова представља један од основних корака у осигурању квалитета индустријских производа. Традиционалне методе контроле често су споре, субјективне и захтевају значајно искуство оператера, што отвара простор за примену савремених техника машинског учења. У овом раду приказана је примена конволуционих неуронских мрежа за идентификацију дефеката на ливеним
деловима потопних пумпи, користећи скуп података отвореног приступа. Анали- зирани су кораци обуке и тестирања модела, као и начини интерпретације резултата који омогућавају његову употребу у реалним индустријским условима. Добијени резултати указују на високу тачност модела и потенцијал дубоког учења као поузданог а лата за аутоматизацију контроле квалитета у ливарској индустрији.Defect detection in cast components is one of the fundamental steps in ensuring the quality and reliability of industrial products. Traditional inspection methods are often slow, subjective, and dependent on the operator’s experience, which creates space for the application of modern machine learning techniques. This paper presents the use of convolutional neural networks for identifying defects in cast components of submersible pumps,
based on an open-access image dataset. The key stages of model training, testing, and result interpretation are analyzed, with emphasis on their applicability in real industrial environ ments. The obtained results demonstrate high classification accuracy and confirm the pot ential of deep learning as a reliable tool for automating quality inspection in the casting
industry
Health risk assessment of As, Cd and Pb in infusions prepared from Capsella bursa-pastoris L. Medik.
No full textOwing to their taste and scent, herbal infusions rank among the most widely consumed non-alcoholic
beverages globally [1]. The infusion prepared from Capsella bursa-pastoris (L.) Medik. benefits human
health [2]. However, it can also hold toxic elements, which raises concerns about its safety and potential
adverse effects on well-being. This study aimed to determine the levels of arsenic (As), cadmium (Cd),
and lead (Pb) in C. bursa-pastoris aqueous infusion, along with their potential health risk assessment.
Plant samples collected from four cities in Serbia (Belgrade, Sremska Mitrovica, Vršac, and Bor) were
used for infusion preparation. As, Cd and Pb determination was performed by inductively coupled
plasma optical emission spectroscopy (ICP-OES). The overall trend noticed in recorded concentrations
was As>Pb>Cd. Kruskal-Wallis's non-parametric test revealed statistically significant variations (p<0.05)
in the contents of these elements in the analyzed samples. Infusion prepared from samples from Bor
contained the highest concentration of As. Principal Component Analysis (PCA) also indicated the
presence of distinct clusters belonging to samples from different locations. Although the highest values
for estimated daily intake (EDI), non-carcinogenic-target hazard quotient (THQ), and lifetime
carcinogenic risk (LCR) were found for As, all examined parameters were lower than the acceptable
limit for children and adults. THQ for As, Cd, and Pb was below 1, and LCR was less than 10-4,
indicating negligible risks. Infusions prepared from C. bursa-pastoris were safe for children and adults,
regarding carcinogenic and non-carcinogenic effects. Nevertheless, calculated levels suggested that
children are more vulnerable to health risks. The present study emphasized that drinking herbal extracts
could be a significant and direct pathway for PTEs' introduction into human nutrition. The human health
risks related to the consumption of herbal infusions should be of concern
Assessment of Nontoxic Surfactant-Modifed Kaolinite for Potential Application as an Adsorbent for Mycotoxins
No full textIn this study, natural kaolin was modified with hexadecyltrimethylammonium bromide
(HDTMA-Br) at two levels corresponding to 50% and 90% of its cation exchange capacity.
The resulting materials, designated as HKR-50 and HKR-90, were used as adsorbents for
the mycotoxins ochratoxin A (OCHRA) and zearalenone (ZEN). The characterization of
the HKRs with several methods (X-ray diffraction, DRIFT spectroscopy, thermal analysis (DTA/TG), SEM, zeta potential measurements, and the determination of the point
of zero charge and textural properties) confirmed the presence of surfactant ions on the
organokaolinites’ surfaces. The adsorption of ZEN and OCHRA by HKRs followed nonlinear adsorption isotherms, suggesting a complex adsorption mechanism. The adsorption
capacities of ZEN and OCHRA were similar for HKR-50 and HKR-90 at pH 3, with higher
adsorption observed for ZEN (~13.0 mg/g for HKR-50 and HKR-90 for ZEN and ~8.0 mg/g
for HKR-50 and HKR-90 for OCHRA). At pH 7, the adsorption of ZEN and OCHRA was
lower than at pH 3, especially for OCHRA, but slightly increased with increased amounts
of surfactant on the kaolinite surface (8.5 mg/g for HKR-50 and 10.8 mg/g for HKR-90 for
ZEN and 2.6 mg/g for HKR-50 and 4.1 mg/g for HKR-90 for OCHRA). Special attention
was paid to the safety assessment of the natural kaolin and HKR-90, and toxicological tests
confirmed the safety of both materials, as no adverse effects were observed in rats
Simulation of the iron transport ladle preheating process
No full textBecause of very important compounds such as tin sulfide, tin is critical metal for green economy. SnS applications are mostly used in optoelectronic devices (photovoltaics), lithium- and sodium-ion batteries, and sensors among others with a significant potential for a variety of future uses. Thermochemical analysis of synthesis of SnS and SnS2 was used for an analysis of possibility for formation of the aimed product. This study explores pyrometallurgical method for synthesis of SnS using pure elements of tin and Sulphur through one strong exothermic reaction in laboratory conditions. The goal is to offer new synthesis method in one closed reactor at temperatures between 220° and 440°C. The mass loss during synthesis was followed in the static conditions. We concluded that this synthesis of SnS can be controlled via an exothermic reaction in very short time. The better results can be reached using the synthesis process in dynamic conditions via an intensive mixing through the synthesis reactio