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Kinetics of Sphalerite Leaching by MnO2-KI Oxidation System in Sulfuric Acid
No full textEfficient extraction of zinc from polymetallic concentrates is crucial for the
metallurgical industry. Traditional leaching techniques often rely on strong oxidizing
agents, which can be wasteful and environmentally harmful. While cyclic oxidation
systems like the Fe3+/Fe2+ pair are known, they often fail to achieve high leaching rates,
especially when the raw material contains multiple sulfide minerals. In this study, we
developed a novel oxidation system using manganese dioxide (MnO2) as the primary
oxidizing agent and potassium iodide (KI) as a supporting material to create an I2/I−
oxidation cycle in a sulfuric acid medium, at an atmospheric pressure between 40 ◦C
and 80 ◦C. Leaching experiments were conducted under varying temperatures and KI
doses. The results demonstrated that for the MnO2-KI system, a zinc leaching degree
of 89.78% was achieved after 3 h of leaching at 80 ◦C, and kinetic studies indicated that
the leaching process is diffusion-controlled (through the thin film), with an activation
energy of 27.65 kJ mol−1. Moreover, this system offers an improved method for separating
iodine from the leachate upon completion, enhancing the overall process efficiency. It also
opens opportunities to test other primary oxidizing agents in combination with iodide salts.
These findings suggest that the MnO2-KI oxidation system offers a promising approach for
improving zinc recovery from sphalerite concentrates
Enhancing Utilization of Municipal Solid Waste Bottom Ash by the Stabilization of Heavy Metals
No full textWaste-to-energy (WtE) is a key part of modern waste management. In the European Union, approximately 500 WtE plants process more than 100 million tons of waste yearly, while globally, more than 2700 plants handle over 500 million tons. Roughly 20% of the waste processed is bottom ash (BA). However, this ash can contain heavy metals in concentrations that may render it hazardous. This paper presents a study focusing on stabilizing municipal solid waste incineration BA using simple and industrially viable treatments. The Slovenian WtE plant operator wishes to install the stabilization process; thus, the samples obtained from the plant were treated (1) with a CO2 gas flow, (2) with water spraying, and (3) with a combination of water spraying and a CO2 gas flow under laboratory conditions. Thermodynamic calculations were applied to define potential reactions during the treatment processes in the temperature range from 0 to 100 °C and to define the equilibrium composition of the treated ash with additions of CO2 and water. The standard leaching test EN 12457-4 of treated ash shows a reduction of over 40% in barium concentration and over 30% in lead concentration in leachates
Hydrometallurgical treatment of sphalerite concentrate in oxidative acid solution
No full textSphalerite is the most abundant and economically significant zinc sulfide mineral,
typically found dispersed within complex concentrates alongside other sulfide minerals,
such as copper, lead, and iron sulfides, as well as associated gangue minerals. Due to
its fine-grained structure and intricate mineralogical composition, effective extraction
of zinc from sphalerite often necessitates sophisticated leaching processes. This paper
reviews current advancements in the acidic leaching of sphalerite, with special
emphasis placed on the kinetics and oxidation mechanisms induced by various
oxidizing agents, including hydrogen peroxide, oxygen, dichromates), nitrate and
nitrite salts, ferric and cupric ions, among others. Furthermore, novel findings from
leaching experiments employing sulfuric acid solution in combination with manganese
dioxide and potassium iodide an oxidation system not previously investigated, are
presented and discussed in detail. Comprehensive characterization techniques, such as
Atomic Absorption Spectroscopy (AAS), X-ray Diffraction (XRD), Scanning Electron
Microscopy coupled with Energy Dispersive Spectroscopy (SEM/EDS), and optical
microscopy, were utilized to analyze the original concentrate and the resulting leach
residues. Finally, the obtained results are systematically compared with previously
published data involving leaching of sphalerite concentrates in sulfuric acid solutions
using sodium nitrate or hydrogen peroxide as oxidants, providing new insights into
their relative effectiveness and mechanisms
Značaj rudarstva i geologije u konceptu održivosti
No full textU radu je prikazan značaj rudarstva i geologije za razvoj društva zasnovanog na načelima održivosti. Neravnomeran razvoj, svake zemlje pojedinačno, ima veliki uticaj na nivo primene održivih tehnologija. Održivo upravljanje prirodnim resursima je složen zadatak zbog mogućnosti nastajanja nepopravljivih grešaka izazvnih pogrešnim planiranjem. Stručnjaci rudarsko-geološke struke u saradnji sa kolegama iz drugih naučnih disciplina nastoje da reše izazove savremenog društva u ovoj oblasti. Rudarstvo i geologija su vodeće nauke u promovisanju novog pristupa prirodi, njenim resursima i njenoj zaštiti. Inovativna rešenja kao što je uvođenje nauke o održivostu u nastavne planove i programe rudarstva i geologije doprinosi profesionalnom razvoju mladih ljudi. Dobijena znanja kasnije mogu da implementiraju u praksi. Takođe, primena informacionih tehnologija i savremenih softvera doprinosi promovisanju naučno zanovanih predviđanja i rešenja koja jačaju i prirodne i društvene sisteme
Adsorptive removal of critical elements from mine wastewater
No full textOčuvanje zdrave životne sredine predstavlja neophodni korak u postavljanju održivog razvoja društva u celini. Industrijska dinamika, na globalnom nivou, poremetila je ravnotežu između ekonomskih i ekoloških interesa i značaja. Rudarstvo u Republici Srbiji je u konstantnoj ekspanziji. Tokom prerade mineralnih sirovina, od kopanja, preko koncentrisanja do dobijanja kritičnih elemenata dolazi do nastajanja otpadnih voda koje je neophodno prečistiti pre ispuštanja u recipiijent. S obzirom na njihov nizak pH nivo i visoke koncentracije različitih konstituenata, njihovo slučajno ispuštanje može imati veoma štetan uticaj i na životnu sredinu i na ljudsko zdravlje. U ovom radu biće prikazane adsorptivne tehnike za ukljanjanje različitih metala (železo, bakar, kobalt, itd.), uz poređenje njihove efikasnosti i neophodnih procesnih parametara. Pored toga, biće dat pregled zakonske regulative u Republici Srbiji koja bitno utiče na oblast rudarstva i zaštite životne sredine.Preservation of a healthy environment is a necessary step in establishing the sustainable development of society as a whole. Industrial dynamics, on a global scale, have upset the balance between economic and environmental interests and importance. Mining in the Republic of Serbia is constantly expanding. During the processing of mineral raw materials, from mining, through concentration to obtaining critical elements, waste water is produced, which must be purified before discharge into the recipient. Given their low pH level and high concentrations of various constituents, their accidental release can have a very harmful impact on both the environment and human health. In this paper, adsorptive techniques for the removal of various metals (iron, copper, cobalt, etc.) will be presented, with a comparison of their efficiency and necessary process parameters. In addition, an overview of the legislation in the Republic of Serbia that significantly affects the field of mining and environmental protection will be given
Electrochemical examining of cystine and cysteine as green corrosion inhibitors for 7075 aluminium alloy
No full textThe corrosion inhibition performance of cystine and cysteine as green inhibitors for 7075-T6 aluminium alloy in 0.1 M NaCl solution was investigated and compared. Inhibitive efficiency was evaluated using linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Various inhibitor concentrations were examined to assess their effectiveness. Surface analysis of the aluminium alloy before and after electrochemical testing was conducted using scanning electron microscopy (SEM). The findings indicate that both cystine and cysteine effectively inhibit corrosion, though their protection mechanisms vary. Cysteine demonstrated higher efficiency for short-term corrosion inhibition, while cystine provided more durable, long-term protection
High pressure die casting simulation of aluminum mounting frame for recessed lighting
No full textHigh pressure die (HPD) casting is a widely y used practice in industry, especially when it comes to casting
metals such as aluminum, copper or bronze and their alloys. This paper discussed how variation of piston
speed and pressure influence casting errors such as shrinking. Using simulations for determining how
processing parameters effect the final casting product has been a more popular since it is made to save
money, resources and energy. The program used to simulate HPD casting is NOVACASTTM which uses
finite volume elements for calculation both metal flow and solidification. The model for simulation uses
500000 elements, with about 15mm of distance casting and the wall of the mold for the calculation box. The
casting temperature of EN AC-46000 (SS4250) alloy is 685 ºC. There are two cooling channels one on each
side of the casting inside the mold that use water as a coolant at 30 ºC. The heat transfer model used is
Surface heat transfer while for Shrinkage calculation High gravity influence is taken in account. For HPD
with filling chamber parameters the Chamber diameter is 80 mm, the Chamber length is 345 mm (5 mm are
given to the model for more precise gating placement), melt mass in chamber 3.5 kg and Metal filled into
casting cavity is 2.933 kg. The varying parameters are Piston velocity and Flow. Unfortunately the current
model for the casting had critical shrinkage regardless of the varying parameters therefore the simulation
must be further improved to correspond to the real life results
Habitat Loss and Other Threats to the Survival of Parnassius apollo (Linnaeus, 1758) in Serbia
No full textThe cessation of traditional mountain grazing has emerged as a principal driver of habitat degradation and the local extinction of Parnassius apollo (Linnaeus, 1758) in Serbia. While previous studies have cited multiple contributing factors, our research provides evidence that the abandonment of extensive livestock grazing has triggered vegetation succession, the disappearance of the larval host plant (Sedum album), and a reduction in microhabitat heterogeneity—conditions essential for the persistence of this stenophagous butterfly species. Through satellite-based analysis of vegetation dynamics (2015–2024), we identified clear structural differences between habitats that currently support populations and those where the species is no longer present. Occupied sites were characterized by low levels of exposed soil, moderate grass coverage, and consistently high shrub and tree density, whereas unoccupied sites exhibited dense encroachment of grasses and woody vegetation, leading to structural instability. Furthermore, MODIS-derived indices (2010–2024) revealed a consistent decline in vegetation productivity (GPP, FPAR, LAI) in succession-affected areas, alongside significant correlations between elevated land surface temperatures (LST), thermal stress (TCI), and reduced photosynthetic capacity. A wildfire event on Mount Stol in 2024 further exacerbated habitat degradation, as confirmed by remote sensing indices (BAI, NBR, NBR2), which documented extensive burn scars and post-fire vegetation loss. Collectively, these findings indicate that the decline of P. apollo is driven not only by ecological succession and climatic stressors, but also by the abandonment of land-use practices that historically maintained suitable habitat conditions. Our results underscore the necessity of restoring traditional grazing regimes and integrating ecological, climatic, and landscape management approaches to prevent further biodiversity loss in montane environments
Origin, depositional environment and maturity of crude oils from the “KND” oil field (SE Pannonian Basin, Serbia)
No full textThe most important oil fields in Serbia are located in the northern part of the country and belong to the southeastern part of the Pannonian Basin. A third of the total crude oil production in Serbia is produced in the Velebit oil field. The second most prolific oil field is „KND“ yielding about 17% of the total crude oil production. Despite its importance, only few samples were investigated to a limited extent in the 2000s. Therefore, oils from the „KND“oil field (near the Romanian border) were investigated in this study to establish their origin, depositional environment, thermal maturity and age. For that purpose, distributions of biomarkers and aromatic hydrocarbons, as well as results from Fourier transform infrared spectroscopy (FTIR) and bulk carbon isotopy were used.
Gas chromatograms of whole oils and the total ion chromatograms of saturated fractions reveal three groups of oils. The first group includes non-biodegraded oils where n-alkanes are the predominant compounds. The second group of oils is characterized by the prevalence of isoprenoids pristane (Pr) and phytane (Ph), but contains the whole series of n-alkanes in considerable amounts, indicating the 1st stage of biodegradation. In oils of the third group Pr and Ph are also dominant compounds in the saturated fractions; however n-alkanes are present in lower concentrations or are almost absent revealing 3rd to 4th stage of biodegradation. This classification is checked by GC-MS analysis of C14-C16 bicyclic sesquiterpanes (m/z 123, 179, 193, 207), whose alteration starts in the 4th stage of biodegradation, while they are almost removed in the 5th stage. The presence of full series of C14-C16 bicyclic sesquiterpanes in biodegraded „KND“ oils confirms that biodegradation does not exceed the 4th stage. Therefore, polycyclic biomarkers (steranes, hopanes, tricyclic terpanes, oleanane, gammacerane) can be used for organic geochemical characterization.
In non-biodegraded oils, the n-alkane distributions are similar and are characterized by equal abundances of odd and even members (Carbon Preference Index, CPI ~ 1). A domination of short-chain homologues is associated with Low vs. High Carbon Preference Index (LHCPI) values ≥ 2.40 and Terrestrial-to-Aquatic Ratio (TAR) values ≤ 0.32, which indicates a significant input of aquatic (algal) organisms in the precursor organic matter (OM). The branching factor (CH2/CH3) of non-biodegraded oils derived from FTIR analysis (2.22-2.29) also argues for greater contribution of aquatic than terrigenous OM.
The source parameters derived from the distributions of polycyclic biomarkers showed similar values for all „KND“ oils, regardless of the degree of biodegradation. The relative abundances of regular C27-C29 αα(R) steranes are characterized by very slight prevalence of C28 and C27 over C29 homologues, plotting them in the area of mixed marine-terrestrial origin of OM in the corresponding ternary diagram. This is further supported by the values of sterane/hopane ratio, gammacerane index (GI = 10×G/(G+C30 αβ hopane)) and oleanane index (OI = 10×O/(O+C30 αβ hopane)) of 0.83-1.19, 1.21-1.50 and 1.56-1.72, respectively. The ternary diagram derived from relative abundances of (C19+C20), C21 and C23 tricyclic terpanes suggests a marine-deltaic depositional environment. Consistently, stable carbon isotope compositions (δ13C) of the saturated and aromatic fractions plot most oils between the marine and terrigenous lines in the Sofer diagram, while the remaining samples lie almost directly on the marine or terrigenous line.
The values of Pr/Ph ratio (0.92-1.15), associated with the C35 αβ/C34 αβ hopane ratios (0.88-1.01) indicate deposition of OM under transitional redox conditions. However, the presence of isorenieratane and its characteristic derivatives in some samples denotes photic zone anoxia. The plot GI vs. Pr/Ph confirms water column stratification. Alkylated 2-methyl-2-(4,8,12-trimethyltridecyl)chromans (MTTCs) occur in all samples. Their distributions are similar, resulting in quite uniform values of the MTTC ratio (0.42-0.47). The plot of Pr/Ph vs. MTTC ratios indicates deposition of OM in „normal“ marine conditions. Values of the C35 αβ/C34 αβ hopane (0.88-1.01), C29 αβ/C30 αβ hopane (0.42-0.43), C31 αβ(R)/C30 αβ hopane (0.25-0.27) and C25/C26 tricyclic terpane (1.11-1.55) ratios applied to corresponding graphs denote marine shale as source rocks of „KND“ oils. Hopane maturity ratios C30 βα moretane/C30 αβ hopane (0.12-0.15) and C31 αβ(S)/C31 αβ(S+R) (0.58-0.59) show almost identical values in all samples and attain their empirical equilibrium values (C30 βα moretane/C30 αβ hopane for Cenozoic oils). Sterane maturity ratios C29 αα(S)/(C29 αα(S)+ αα(R)) (0.53-0.56) and C29 ββ(R)/(C29 ββ(R)+ αα(R)) (0.56-0.59) confirm the uniform maturity of „KND“ oils. The same applies to methylphenanthrene maturity index MPDF (0.45-0.51). Vitrinite reflectance, calculated from the values of C29 αα(S)/(C29 αα(S)+ αα(R)) sterane ratio (0.88-0.96%) and MPDF index (0.84-0.97%), indicates a high maturity of „KND“ oils and their generation between the peak and the beginning of late stage of the oil window.
It is concluded that „KND“ oils have different properties in terms of biodegradation, from non-biodegraded to the 4th stage of biodegradation. However, regardless of the degree of biodegradation, the source parameters indicated that oils belong to the same genetic type. The precursor OM originates from mixed marine/terrestrial sources, and was deposited under transitional redox conditions. The oils were generated from source rocks at the maturity corresponding to the vitrinite reflectance of 0.84-0.97%. The oils were probably derived from marine shale of Miocene age within the local depression of Srpska Crnja, where some promising source rocks have been detected
Effect of packaging type on antimony leaching into bottled water
No full textThe type of packaging material is a critical factor influencing the safety of bottled water.
Polyethylene terephthalate (PET) and glass are the most commonly used materials, with PET
being widely applied due to its light weight and durability. However, antimony oxide, used
as a catalyst in PET production, can leach into water, raising potential health concerns. In
contrast, glass is generally chemically inert and does not contribute to antimony leaching
[1,2]. The aim of this study was to compare antimony leaching from PET and glass packaging
under different storage conditions. Six commercial bottled water brands were analyzed at
three temperatures (−20 °C, 25 °C, and 40 °C) using inductively coupled plasma mass
spectrometry (ICP-MS). In addition, the total Sb content of PET bottles was determined. The
results confirmed Sb leaching exclusively from PET packaging, with the highest
concentrations detected at 40 °C, exceeding the EU/EPA guideline value of 5 µg/L. In
contrast, glass packaging showed stable Sb levels under all storage conditions, with the only
exception being bottles sealed with PET-based caps, where measurable Sb leaching was
observed. These results confirm that antimony leaching is associated with PET packaging
and that glass packaging remains essentially inert under the studied conditions