Due to its properties, forage sorghum can grow under unfavorable soil conditions and in places with very harsh climatic conditions. Also, it is very tolerant of habitats that are contaminated with metals. Certain varieties of sorghum are capable of absorbing Zn from polluted soil. In this study, the optimal burning time and temperature of Sorghum spp. with the aim of obtaining ash with the highest possible concentration of Zn. Applying the chemical analysis of the homogenized initial sample of sorghum, it was established that 1 kg of sorghum contains 55.61 mg of Zn. Combustion experiments were performed at temperatures of 400, 450, 500 and 600 oC for 120, 240 and 360 minutes. In all experiments, the mass loss was approximately 90%. It was observed that the highest content of Zn has the ash that was formed after burning for 6 hours at a temperature of 500 oC. Differential thermogravimetric analysis showed that the greatest mass loss of the sample (ash) was recorded at a temperature between 150 and 400 oC. In order for the valorization of zinc from the ash to be possible, it is necessary that the ash and leachate (after washing the ash) do not contain any substance that would prevent the precipitation of zinc salts.

Serbia's mining industry is at a pivotal moment, navigating significant environmental challenges while pursuing economic growth. The country's rich mineral deposits, including copper, gold, and lithium, present substantial opportunities. However, the sector's development is hindered by outdated technology, limited institutional capacity, and regulatory frameworks that complicate policy implementation aligned with EU standards. Key legislative measures, such as the Law on Environmental Protection and the Law on Waste Management, are in place, with ongoing efforts to establish a mining waste cadastre supported by EU funding. Despite these efforts, challenges remain due to inadequate institutional capacity and poor interagency coordination. The industry requires robust regulations, enhanced waste management infrastructure, and strategic investments to overcome these obstacles. This research underscores the importance of balancing economic development with environmental stewardship and social welfare to ensure the region's sustainable growth and long-term prosperity.

Valorization of zinc from polymetallic ores and concentrates is a very important branch in the metallurgical industry. Zinc is mostly extracted by hydrometallurgical methods. Leaching is most often done with the help of strong oxidizing agents, which can have a harmful effect on the environment. Certain cyclic oxidation systems, such as the Fe3+/Fe2+ couple, often fail to achieve a high level of zinc leaching, especially when it is in the form of sulfide. In this work, a new oxidation system was applied, which consists of MnO2 as the primary oxidation agent and KI as an supporting oxidation agent that serves to form the I2/I- oxidation cycle in the medium of sulfuric acid. The leaching experiment was performed under atmospheric pressure conditions, in the temperature range from 40 to 80 °C. The influence of KI concentration on the degree of zinc leaching was also examined. For the mentioned system, the degree of zinc extraction is 89.78% after 3 hours of leaching at a temperature of 80 °C. These results show that the MnO2-KI oxidation system has the potential to improve zinc extraction from sphalerite concentrates.

The industrial development will influence the demand and price of nickel in the coming years which opens the possibility for the use of innovative ways for its exploitation from secondary resources. Phytomining of nickel is a prospective in situ technology that uses plants with natural hyperaccumulating capabilities for this element. This study represents application of currently established and developed hydrometallurgical methods on wild populations of nickel hyperaccumulator from Serbia and explores the impact of recrystallization on the purity of the final product. The study confirms that nickel salts (ammonium nickel sulfate hexahydrate) can be synthesized from the Odontarrhena muralis that is naturally occurring on the ultramafic sites in West Serbia. Due to the small starting mass for the harvested biomass the preliminary experiments were separated into two series, which yielded 7,3g and 5,2g nickel salts of 60% and 73% purity, respectively, before recrystallization. However after recrystallization their purity was maximized reaching analytical levels of purity 99,9%, whereas their mass was reduced to 5,45g and 3,89g. More comprehensive studies with larger biomass and proper cultivation on ultramafic soil are needed in future to fully explore the potential for the development of Ni phytomining in Serbia.

Forage sorghum (Sorghum spp.) is a fast-growing annual plant that contains certain micronutrients, the most abundant of which is iron, and the least abundant is copper. This paper presents the behavior of these two micronutrients in sorghum species during combustion at different times and temperature conditions. Combustion of the homogenized sample was performed at temperatures of 400 °C, 450 °C, 500 °C and 600 °C in times of 120, 240 and 360 minutes. Differential thermal analysis (DTA) is carried out at a heating rate of 3 K/min from 25 to 500 °C. It was found that the combustion of forage sorghum increased the concentration of these two micronutrients in it. The highest concentration of Fe (7777 mg/kg) was achieved after 360 minutes of combustion at 600ºC, while the highest concentration of Cu (105 mg/kg) was achieved after 240 minutes of combustion at 450ºC.

Efficient 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.

Based on gold and copper processing, Serbia's mining sector faces significant challenges due to outdated practices, existing regulations, and a lack of investment in sustainable technologies. Economically important, the industry unfortunately causes severe environmental degradation, resulting in air, water, and soil pollution, which is compounded by resource overexploitation and poor waste management. Serbia's material flow indicators show high raw material consumption and hazardous waste production, with per capita Raw Material Consumption (RMC) exceeding the EU average. The country ranks low in resource productivity and struggles to align its practices with modern European standards. Serbia's mining royalty rates remain relatively low compared to other countries, limiting state revenue and enabling resource overexploitation. Additionally, the lack of local processing of raw materials reduces the sector's economic contribution. While foreign investors bring capital and technology, concerns about environmental impacts and equitable benefit distribution persist. To address these issues, Serbia must enforce strict environmental standards, and adopt new technologies while incorporating material flow analysis into policy-making to achieve better resource management and minimize environmental damage. Promoting local processing and increasing mining royalties could enhance economic contributions while fostering sustainability. Collaborative efforts among government entities, investors, and the public are essential to balancing different aspects of the development of the Serbian mining sector by transitioning to more acceptable mining practices while preserving ecological integrity.

This study explores the electrochemical desulfurization of coal and the recovery of copper (Cu) using dimensionally stable anode (DSA) electrodes. Background: The research addresses the need for effective sulfur removal from coal to reduce emissions. Methods: Electrochemical desulfurization was conducted using DSA and graphite electrodes, evaluating parameters like activation energy, desulfurization rate, and energy consumption. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical properties. Results: The DSA electrode demonstrated superior performance with higher desulfurization rates, lower activation energy, and better response to temperature increases compared to the graphite electrode. Optimal desulfurization was achieved at 50 °C with the DSA electrode, balancing efficiency and energy consumption. Copper recovery from the solution post-desulfurization was effective, with an 86.34% recovery rate at −0.15 V vs. (Ag|AgCl). The energy consumption for the Cu recovery was calculated to be 10.56 J, and the total cost for recovering 1 ton of Cu was approximately 781.20 €. Conclusions: The study highlights the advantages of DSA electrodes for efficient sulfur removal and metal recovery, promoting cleaner energy production and environmental sustainability. Future research should focus on optimizing electrochemical conditions and scaling up the process for industrial applications.

Two medium-carbon microalloyed steels with a predominant acicular ferrite microstructure were investigated in this study in order to determine the initial micro-crack formation mechanism and the role of acicular ferrite structure in cleavage fracture. In order to ensure cleavage fracture, samples were investigated at −196 °C for uniaxial tension and four point bending fracture. Previous investigations have shown that cleavage fracture for steels with a predominant acicular ferrite microstructure has not been initiated by the fracture of coarse TiN particles as in ferrite-pearlite, bainite, or martensitic microalloyed steels. The average maximal thickness of cementite plates measured in this work is 0.798 µm and 0.966 µm, for V and TiV steel, respectively. The corresponding stress values required for their fracture according to Griffith’s equation are 1970 MPa and 1791 MPa, respectively. Estimated values of the effective surface energy for the V steel with an average cementite volume fraction of 3.8% range from 40 Jm−2 to 86 Jm−2, and for the TiV steel with an average cementite volume fraction of 18.3% range from 55 Jm−2 to 82 Jm−2. The fracture of coarse cementite plates was found to not to be responsible for the cleavage fracture initiation in case of both steels.

This paper examines the effects of structural-textural characteristics of sulfide minerals on their leaching from polymetallic concentrates with sulfuric acid and hydrogen peroxide solutions. The polymetallic concentrate was obtained by flotation of polymetallic ore from the Rudnik deposit in Serbia. X-ray diffraction (XRD), qualitative and quantitative mineralogical, scanning electron microscopy (SEM/EDX), and chemical analyses were used to characterize the polymetallic concentrate and leach residue. The polymetallic concentrate contained chalcopyrite, galena, sphalerite, pyrrhotite, and quartz. The total content of sulfide minerals was 69.5

The automotive industry is in the process of transformation from the traditional production of vehicles with engines powered by the combustion of fossil fuels to vehicles powered by electric energy. This revolutionary transformation will generate a growing demand for metallic raw materials that are a crucial part of batteries-nickel and cobalt, among others. Providing enough raw materials for e-mobility in a sustainable way will be a challenge in the years to come. The region of South-Eastern Europe (SEE) and Turkey is relatively rich in lateritic Ni-Co deposits, and this region has the potential to partially replace the import of nickel and cobalt intermediates to the European Union from distant overseas locations. Possibilities for the sustainable sourcing of nickel and cobalt from the SEE region are reviewed in this paper, with an overview of the global demand and production of these metals, lateritic mineral resources of SEE, the current status of production, and the prospective development of nickel and cobalt production in this region.

Phytomining is a currently developing biotechnology aiming to extract rare and precious metals from naturally enriched or polluted soils with the help of hyperaccumulator plants. On the territory of the Balkans, hyperaccumulating species mainly accumulate elements such as nickel, zinc, thallium, copper and arsenic. This paper provides an overview of the studied technologies around the world for the extraction of these elements from hyperaccumulator's biomass, as well as the areas of potential application of the obtained products. Phytomining has a potential for development in Serbia, and for this purpose it is necessary to utilitized available hyperaccumulators, as well as to investigate technologies for the extraction of metals from their biomass.

Electric waste from numerous devices that are put out of use every day has some form of printed circuit board that contains precious and valuable metals in their components. In order to extract these metals, the printed circuit boards were crushed and pyrolyzed into powder. The fine pyrolyzed printed circuit board (PPCB) powder was separated into fractions, and the fine metallic fraction was used as a raw material for metal leaching extraction. In order to better understand how various metal species react in leaching media, several leaching agents were used (sulfuric acid, nitric acid, glycine, and acid mine drainage-AMD) alone, and with the addition of hydrogen peroxide. Additionally, the influence of the S/L ratio and leaching temperature were investigated in sulfuric acid leaching solutions, as this is the one most widely used. In one case, the reactor was heated in a thermal bath, while in the other, it was heated in an ultrasonic bath. Lastly, several experiments were conducted with a (consecutive) two-pronged leaching approach, with and without applied pretreatment. The aim of this paper is to give a multifocal and detailed approach to how metals such as Al, Cu, Co, Zn, Sn, and Ca behave when extracted from fine PPCB powder. However, some attention is given to Nd, Pd, Pb, and Ba as well. One of the main findings is that regardless of the pretreatment or the sequence of leaching media applied, consecutive two-pronged leaching cannot be used for selective metal extraction. However, AMD was found to be suitable for selective leaching with very limited applications.

Microstructure assessment is crucial for the design and production of high-quality alloys such as cast aluminum alloy ingots. Along with the effect of a more homogeneous microstructure to result in much better mechanical properties, better as-cast alloy quality indicates a higher efficiency of the aluminum alloys production process. During the aluminum alloy solidification process many microstructural defects can occur, which deteriorate the mechanical properties and hence decrease the usability of such an ingot. Application of the electromagnetic field during the vertical continuous casting process significantly reduces occurrence of these defects. In the present study, EN AW 7075 alloy samples were cast with and without application of an electromagnetic field and examined regarding the microstructure, electrical conductivity, and changes in the phase composition. The obtained results clearly show that it is possible to decrease or avoid casting defects by the electromagnetic field application as verified by the microstructure characterization and quantification, electrical conductivity tests and differential thermal analysis (DTA).

The aim of the presented research was to analyze ceramic material based on cordierite as a function of activation time and sintering temperature. Three-component oxide mixture was prepared (MgO + Al2O3 + SiO2 in the ratio 2:2:5). To decrease the sintering temperature, 10 mass % Bi2O3 was added to this mixture. The mixtures were mechanically activated for 5 and 240 minutes in a ceramic ball mill. Activated mixtures were sintered at temperatures of 1173-1573K. XRD method was used to determine the structural transformations of the obtained products.

The roasting of sulfide ores and concentrates is one of the most important steps in pyrometallurgical metal production from primary raw materials, due to the necessity of excess sulfur removal, present in the virgin material. Pentlandite is one of the main sources for nickel pyrometallurgical production. The knowledge of its reaction mechanism, products distribution during oxidation and reaction kinetics is important for optimizing the production process. Raw pentlandite-bearing ore from the Levack mine (Ontario, Canada) was subjected to oxidative roasting in the air atmosphere. A chemical analysis of the initial sample was conducted according to EDXRF (Energy-Dispersive X-ray Fluorescence) and AAS (Atomic Adsorption Spectrometry) results. The characterization of the initial sample and oxidation products was conducted by an XRD (X-ray Diffraction) and SEM/EDS (Scanning Electron Microscopy with Energy Dispersive Spectrometry) analysis. Thermodynamic calculations, a phase analysis and construction of Kellogg diagrams for Ni-S-O and Fe-S-O systems at 298 K, 773 K, 923 K and 1073 K were used for proposing the theoretical reaction mechanism. A thermal analysis (TG/DTA—Thermogravimetric and Differential Thermal Analyses) was conducted in temperature range 298–1273 K, under a heating rate of 15° min−1. A kinetic analysis was conducted according to the non-isothermal method of Daniels and Borchardt, under a heating rate of 15° min−1. Calculated activation energies of 113 kJ mol−1, 146 kJ mol−1 and 356 kJ mol−1 for three oxidation stages imply that in every examined stage of the oxidation process, temperature is a dominant factor determining the reaction rate.

Phytomining is a new promising technique that is based on using hyperaccumulating plants which biomass is utilized as a bio-ore for metal extraction. The Ni-hyperaccumulating species Odontarrhena muralis is widely distributed on ultramafic soils in Serbia, and could be a promising candidate for Ni agromining. In the present study, efficiency of a hydrometallurgical process for Ni recovery using biomass of O. muralis wild population through the synthesis of Ni salts from plant ash in the form of ammonium nickel sulfate hexahydrate, Ni(NH4)2(SO4)2 6H2O ? (ANSH) was assessed. The average Ni content in the plant from ultramafic sites in West Serbia was up to 3.300 g kg-1. The mass yield of ANSH crystals from the crude ash was ~12 % with the average purity of 73 % were obtained. By optimizing the purification process before precipitation of ANSH crystals, it is possible to obtain salt crystals of higher purity, which increases the economic profitability of this process. The results of this preliminary study on wild population of O. muralis show the increased potential for implementation of phytomining practices as an alternative way of Ni extraction on ultramafic sites in Serbia.

The study is focused on the determination of the most effective chemical leaching process for the simultaneous demineralization/deashing and desulfurization of subbituminous coal from the Bogovina Basin. Coal was treated for 30 min, at different temperatures, using variable concentrations of hydrochloric, nitric, acetic and citric acids; hydrogen peroxide, mixture of hydrogen peroxide and nitric acid (pH 2), as well as by the stepwise leaching process (nitric acid + mixture of hydrogen peroxide and nitric acid, pH 2). The changes in mineral composition, caused by the chemical leaching, are followed using X-ray diffraction, whereas alterations of coal organic matter are tracked by Fourier-transform infrared spectroscopy and the content of fixed carbon. Inorganic acid leaching, regardless of the temperature and acid concentration, enabled the successful deashing of coal, whereas the percent of desulfurization was insufficient. The organic acid leaching was not satisfactory for both, deashing and desulfurization. Leaching by H2O2 and H2O2/HNO3 mixture (pH 2) resulted in moderate desulfurization, but the ash reduction was low. The most suitable method for the simultaneous effective ash (78 wt.%) and the sulfur (66 wt. %) removal from Bogovina coal is the two-step leaching, combining 10 vol. % HNO3 and mixture of 35 vol. % H2O2/10 vol. % HNO3 of pH 2 at 60?C.

Sodium carbonate is a material that is very good sorbent of carbon dioxide from the atmosphere, and it is a reason of it is increasing importance in environmental protection. In order to improve it is sorption characteristics, activation of Na2CO3 was performed by mechanochemical procedure and monitoring of changes during the relaxation time. This research is based on differential thermal analysis with thermogravimetry, in order to determine the changes that occurred on the activated samples during the relaxation period under controlled conditions. Sodium carbonate was activated for 2 and 7 minutes in a vibro mill, and then the activated samples were deposited in at room temperature and atmosphere of carbon dioxide at a humidity of 95% for 96h.