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A new process for mine water purification has been proposed, based on biosorption followed by burning the loaded biosorbents. Wheat straw and sawdust of trees are convenient as biosorbents in the proposed process. Biosorption was performed in two stages: a cross-flow regime between the mine water and the biosorbent. The achieved copper adsorption degree was > 95%. Based on the mine water volume and its chemical composition, the estimated amount of the biosorbent was 60.000 t/year. The cogenerative mode of the loaded biosorbent combustion was considered for green energy production. For the recovery of metals concentrated in the ash, they must be processed separately. Several possibilities for ash processing were proposed and discussed. For an annual volume of mine water and the copper content in it, the mass and energy balances of the process were estimated, giving some economic data on the process efficiency. The analysis of the revenues and costs, based only on the energy value produced by the combustion of the biosorbent, has shown that the process can economically be viable regardless of the value of the recovered metal.

Flotation waste, which was produced through seventy years of copper ore processing in RTB Bor, Serbia, is deposited in a flotation tailings pond. In total, almost 26.4 Mt could be considered as available for eventual reprocessing and reuse. Chemical analysis has shown that an average concentration of targeted metals in the tailings is: 0.183% Cu, 0.35 g/t Au and 2.17 g/t Ag. The tailings contain 60 to 70% of SiO2, 10 to 17% of Al2O3 and pyrite 5 to 8%. Flotation tailings reprocessing consisted of acid leaching followed by re-flotation of the leach residue. Leaching of the tailings resulted in leach liquors containing Cu2+ ions from 50 to 580 ppm. The average copper removal degree in the leaching stage was 70%. After re-flotation, the total copper removal degree reached 83 to 85%. Sulphur removal degree reached 77%. Sulphur concentration in the treated tailings was reduced almost 5 times compared to the inlet concentration. An equivalent amount of iron was also reduced through the flotation process. Concentration of total copper was reduced 3 times.

This paper presents results of investigations of the possibility of using 'Gigovići'-Ulcinj limestone (Republic Montenegro) as filler in various industry branches. Micronization methods, granulometric composition, oil and water absorption and degree of whiteness were investigated, and chemical and thermal analyses (DT/TG) were performed. Physico-chemical properties of this limestone classify it among high quality carbonate raw materials with relatively high CaCO3 content of 98.16 %, as well as low MgCO3 content of 1.53 % and low silicate content (SiO2 0.30 %). Its quality satisfies requirements of standards on using of calcium carbonate as filler in industry of paints and coatings; paper industry, rubber and PVC industry; glass industry; production of mineral fertilizers; foundry industry; sugar industry and metallurgy. Due to the low degree of whiteness (85.25 %) 'Gigovići' limestone cannot be used in pharmaceutical and cosmetics industry. Due to relatively high content of MgO (0.73 %) and Fe (340 ppm), as well as high content of heavy metals, Cu (18 ppm), Ni (24 ppm) and Cd (9 ppm), 'Gigovići' limestone cannot be used, in production of cattle feed and for neutralization of acidic soils.

This paper describes the waste paper recycling process. Special emphasis is placed on the description of technological phase (disintegration or grinding, screening, cleaning, washing and/or flotation, water treatment and disposal of sludge), which are generally required in the processing of waste paper, and which also represent the main phases in the mineral processing. The waste paper is a potential secondary raw materials but due to degradation of cellulose physical properties which occur during the recycling, the cellulose fibers can be recycled a limited number of times. Because of this, the impact analysis of mechanical and chemical treatment on the secondary fiber quality is also given in the paper.

This paper deals with the investigation of column leaching of low-grade ores from the copper mine Cerovo, Serbia (the approximate Cu content in the ore ranges from 0.2 - 0.3 % with >10 % copper in the form of oxide minerals). The leaching experiments were performed using sulphuric acid solutions, whereby the kinetics of copper leaching was investigated with respect to acid concentration and solid to liquid ratio. The copper concentration in the leach solution ranged from 0.80 to 1.75 g dm-3. The total Cu recovery rate ranged from 30 to 56 %, whereas the recovery rate of copper oxide minerals ranged from 67 to 100 %. Furthermore, with increasing the amount of liquid phase, copper recovery increases as well, and copper oxide minerals were completely leached out. Besides copper ions, considerably high ferrous/ferric ion concentrations were achieved in the leach solution. This concentration was sufficiently high for the use of either solvent extraction or ion exchange techniques or both for further treatment of the leach solution.

Efficiency of screening shows screening performance compared to an ideal screening to achieve a complete separation of the fractions without the presence of grains of size less than the mesh openings left on sieve and grains of size larger than the mesh opening that passed through the sieve. Efficiency is growing rapidly and after a certain time is reduced. This is explained by the fact that the speed of screening depends on the percentage of 'small', 'small-to large' and 'large' grain. The paper shows how for the given grain, their shape and density affect the kinetics of screening.

The old flotation tailings of the Bor copper mine have not been reclaimed for several decades, although it is a serious threat to the environment, especially to some parts of the town. To date, there have been no efficacious attempts of solving the problem by indirect rehabilitation, only several cases of direct reclamation. This paper presents some results of the experiment established on a part of the tailings in the vicinity of the town, where various variants of meliorated and sterile substrates were applied in the biological reclamation with several tree and grass species. The analysis shows that, in the rehabilitation of sterile substrate of the copper mine, it is possible to grow several woody species. The best results were achieved by the species that were planted in the fertile soil layer on the sterile copper mine substrate, and on the mixture of soil and waste. Among the woody species, Robinia pseudoaccacia, Fraxinus excelsior and Acer pseudoplatanus showed the best survival percent, growth, and physiological vitality and the poorest were spruce and common oak.

This paper summarizes the results of determination of the washability characteristics of anthracite coal from Vrska Cuka coal mine, Serbia. The effect of different coal size fractions has been studied through washability studies. In this study, float-sink experiments were carried out with the anthracite coal samples on (−19 + 9.5) mm, (−9.5 + 4.75) mm, (−4.75 + 2.36) mm, and (−2.36 + 0.6) mm size fractions. Two washability parameters, Index of Washability (IW) and Near Gravity Material Index (NGMI), were calculated and the results were compared. The IW and NGMI values indicated that the washability of different size fractions of anthracite coal was easy to relatively difficult to wash. The obtained values of IW showed that the order of coal washing ability by size fractions was as follows: (−9.5 + 4.75) mm, (−4.75 + 2.36) mm, (−2.36 + 0.6) mm, and (−19 + 9.5) mm. The NGMI values decreased with increasing specific gravity and decreasing particle size fractions. The minimum values of NGMI were achieved at density of 1650 kg/m3 and these values were 0.1322, 0.0695, 0.0677, and 0.0240, respectively. The results presented in this study indicate that washability of the anthracite coal is relatively easy and should be washed at a specific density of 1650 kg/m3. [ABSTRACT FROM AUTHOR]

Research on chalcopyrite leaching represents a great challenge, given its importance as one of the most abundant copper minerals and its significant role in global copper extraction. This study aimed to evaluate the effects of different parameters on chalcopyrite leaching by hydrogen peroxide as a strong oxidizing reagent in sulfuric acid solution. A series of leaching tests were carried out to investigate the effect of the solid/liquid ratio, stirring speed, temperature, oxidant and acid concentrations, and lixiviant dosing method on copper extraction from chalcopyrite concentrate. The catalytic decomposition of hydrogen peroxide occurred in the investigated leaching system, as reflected in the obtained metal extraction values. Copper extraction was increased in the first 60 min of the reaction, after which it essentially ceased. The maximum final copper extraction of 64.5% was attained with 3.0 mol/L H2O2 in 3.0 mol/L H2SO4 at a temperature of 40 °C after 120 min of reaction. Due to the catalytic decomposition of hydrogen peroxide in the examined leaching system, the leaching experiment was performed with the periodic addition of lixiviant at specific time intervals as well. The dissolution process was described by the first-order kinetics equation with an apparent activation energy of ~39 kJ/mol. Finally, XRD and SEM-EDS analyses were used to characterize the leached residue, and the results showed that the formation of elemental sulfur on the chalcopyrite surface affected the dissolution process. [ABSTRACT FROM AUTHOR]

As water is essential to life and is an indispensable resource for ecosystems and their services and for nearly all human activities, the goal of this research was to evaluate the surface water quality of the Danube as it passes through the Romania–Serbia border in the nature reservations Djerdap and Iron Gate. The study aimed to assess the oxygen regime, nutrients and heavy metals contamination of the surface waters of the Danube on a length of about 240 km, between Bazias and Iron Gate II. Reference sampling and analytical methods (UV-VIS and AAS) were deployed to reach this goal. In addition, sediments were analyzed through back scattered SEM-EDAX for the elemental analysis of the sediment surface. Results obtained show a low environmental impact of heavy metals, while the Danube's oxygen regime is under stress due to nutrients' (nitrites and orthophosphates) significant concentration in the Danube surface water in the analyzed sector. Our approach can be applied to other water bodies in the area, to increase available scientific data together with societal awareness of the Danube's environmental risks. [ABSTRACT FROM AUTHOR]