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This paper presents the results of an industrial testing of the phase of rough flotation of copper ore from the deposit "North revir" in the Copper Mine Majdanpek. The achieved technological parameters in the rough flotation process, the results of grain size analysis by size classes of on the tested products, as well as the recovery and content of copper by size classes in the products of rough flotation show that the process of rough flotation does not work satisfactorily.

Flotation of grinding products with 55, 60, 65, 70, and 75% of grain size

Robule Lake is located in Eastern Serbia, near city of Bor, known for copper production, and it is being influenced by waste materials from mining activities. For the purification of water from Robule Lake, contaminated with various metal ions (Fe, Cu, Zn, Mn, Cd, Ni, etc.), acid mine drainage (AMD) treatment methods such as: passive treatment method, sequential neutralization, ion exchange, adsorption process based on low cost adsorbents, adsorption process based on natural zeolits, electrodialysis, filtration with nanofiltration membranes, and reverse osmosis, were evaluated by following MCDM methods: TOPSIS, VIKOR, MOOSRA; WASPAS, and CoCoSo. Criteria used for the evaluation were: efficiency in the metal ions removal and the quality of the purified water, necessity of pre-treatment and / or post-treatment of treated water, possibility of using the generated waste, capital costs, operating and maintenance costs, needed area, and sensitivity of the method. The results of the MCDM analysis showed that sequential neutralization was the most appropriate for this wastewater, while passive treatment system and ion exchange were ranked as second and third, respectively.After the selection of AMD treatment method, neutralization tests with lime were carried out on the water sample from Robule Lake. The results of sequential neutralization testing showed that concentration of Fe ions could be lowered below the maximal allowable concentration prescribed by Serbian legislation at pH value 4. The other metal ions: Cu, Zn, and Ni needed pH value 7, and Mn and Cd needed pH 10 for effective removal.

This paper presents the results of mineralogical and flotation studies on the copper ore from the deposit "North Revir" in the Copper Mine Majdanpek, using different collectors. XRD and ore mineralogical analysis showed that the most common minerals are pyrite and chalcopyrite. Chemical analysis confirm that it is a complex low-grade copper ore with average copper content of 0,273%. The content of precious metals (Au and Ag) was 0.2 g/t and 1.2 g/t, respectively. The main aim of flotation studies have been the effect of collector type on the recovery and concentrate grade in the copper flotation process. Various collectors and combinations of them were used in the rough flotation tests of copper ore. The copper recovery was in the range from 79.43% (test no. 4) to 84.96% (test no. 7). The best flotation results were obtained with mixture collectors of sodium isopropyl xanthate (Z11), dialkyl dithiophosphinates (Aerophine 3404) and SKIK BZ 2000. The collector's dosages of 20 g/t Z11, 8 g/t AP3404 and 8 g/t SKIK BZ 2000 produced the copper recovery (84.96 %) with copper concentrate grade of 1.52% .

Coal plays an important role in energy supply. However, low rank/oxidized coals are difficult to float with the common oily collectors, and hence effective collectors are urgently needed to be found or created. The difficult-to-float reason of low rank/oxidized coals primarily includes two aspects, i.e. abundant oxygen-containing groups on coal surface and porous surface of coal particle. The common oily collectors are difficult to adsorb on hydrophilic sites on low rank/oxidized coals surface and a porous structure of coal surface needs large consumption of collectors. This review is to highlight recent advances in the effective collectors for enhancing the flotation of low rank/oxidized coals, especially an overview of effective collectors proposed in the past decade. The effective collectors are achieved through the emulsion of common oily collectors, the mixture of several collectors/surfactants, the special collectors and bio-collectors. Throughout this review, the mechanism of the effective collectors enhancing the flotation of low rank/oxidized coals is discussed and the development directions of effective collectors in the future are also recommended.

Acid mine drainage (AMD) waters are one of the most important ecological risks at the global level because of its high heavy metals content and strong acidity. Treatment of AMD water is a complex and expensive. One of the most widely used treatment process is the neutralization process of AMD. The result of neutralization is the production of sludge which may contain various other (heavy) metals, depending on the chemical characteristics of the mine water treated. In this paper, leachability and toxicity of the sludges obtained during the neutralization process of wastewater from Saraka and Robule acid mine drainage and the sludges after the stabilization process at different temperatures is tested. Sludge produced in the neutralization process of Robule AMD R4 (40) and stabilized on 105°C and 200°C shows a H8-corrosiveness characteristic. Stabilized sludge show tendency to lower leachability of zinc and copper, but without influence on sulphate leachability. Sludges that show a H8-corrosiveness needs additional stabilization/neutralization pretreatment prior temperature treatment.

In this study the effect of mixtures of copper slag and flotation tailings from copper mine Bor, Serbia on the flotation results of copper recovery and flotation kinetics parameters in a batch flotation cell has been investigated. By simultaneous adding old flotation tailings in the ball mill at the rate of 9%, it is possible to increase copper recovery for about 20%. These results are compared with obtained copper recovery of pure copper slag. The results of batch flotation test were fitted by MatLab software for modeling the first-order flotation kinetics in order to determine kinetics parameters and define an optimal model of the flotation kinetics. Six kinetic models are tested on the batch flotation copper recovery against flotation time. All models showed good correlation, however the modified Kelsall model provided the best fit.

The results of flotation kinetics the hydrocyclone underflow and overflow in high-grade copper ore processing from the Copper Mine Bor (RB Bor), suggest the possibility of improving the current technological flotation process. This is confirmed by the following results: the distribution of copper in classification product in ration 80:20 % in favor of hydrocyclone underflow as well as higher copper content in the sample and individual class of hydrocyclone underflow compared to the same parameters of hydrocyclone overflow. Participation of optimal size class - 0.075 mm in hydrocyclone underflow is 32.47 %, with copper content of 4.38 %, resulting that about 65 % of total copper in this class to the feed of hydrocyclone is distributed in hydrocyclone underflow and 35 % in the same class in hydrocyclone overflow. Copper recoveries, obtained in laboratory batch flotation tests from hydrocyclone overflow and underflow, are 90.77% and 7.94 %, respectively. Calculated in relation to total copper in the feed of hydrocyclone, 17.30 % Cu can be valorized from hydrocyclone overflow by flotation process, with the same process, 59.58 % Cu is valorized from hydrocyclone underflow, what is 3.44 times more. The results indicate higher copper recovery and slightly better flotation kinetics of hydrocyclone overflow. However, due to better liberation of solid phase and optimization the pulp density in the flotation process, each class of hydrocyclone underflow gives higher contribution to the copper recovery compared to the relevant class of hydrocyclone overflow, calculated on copper, contained in the same class of hydrocyclone feed. Parallel flotation of hydrocyclone overflow and underflow can improve the existing technological process of high-grade copper ore processing in the Copper Mine Bor.

This article investigates the effect of attrition of fine waste coal from anthracite mine “Vrska Cuka, Serbia on the flotation results and flotation kinetic parameters in a batch flotation cell. Waste coal was generally stored into settling ponds and old tailing ponds as a waste material. Floatability of oxidized coal can be improved by attrition. The flotation tests were performed with and without attrition using different dosages of kerosene. The best results were observed on the waste coal combined flotation with attrition (attrition time 10 minutes) using 5,000 g/t kerosene. These results are compared with obtained coal recovery of raw coal. Based on batch flotation test data of the coal, the nonlinear fitting was conducted using a MatLab tool for modeling the first-order flotation kinetics. The cumulative combustible recovery against flotation time were correlated using the classical model and modified Kelsall model. The attrition had a positive effect on the coal flotation kinetics parameters. Also,...

The basic aims of layer excavation by filling methods are: increasing or total layer spending without ore impoverishment, layer excavation in complex mining and geological conditions, environmental factors preservation, improvement of ergonomic and safety work conditions and recirculation the waste material. For achievement of these aims, it is necessary to put in the stope the filling material of appropriate physical and mechanical characteristics, especially the pressure strength. This work presents a discussion of procedure of filling material selection with necessary strength, and application of filling stoping methods at complete layer excavation and protection of the earth surface and objects on it from damages.

The research results show the possibility of improvement the basic technological parameters of copper flotation in the copper mine Majdanpek. With increasing the fineness of definite grinding product from 55 % to 65 % of grain size class -74 μm, as well as optimizing the pH value of the pulp, the type and dose of collectors and frothers, there was an increase of copper recovery for 9.35% and the quality of primary concentrate for 0.54 % or about 40 %. The compared technological parameters of the industrial process of flotation, in the laboratory experiment with optimal parameters is achieved an increase of the copper recovery for 7.56 % and concentrate quality for 0.61%, or about 50%. The analysis of the achieved technological parameters on narrow grain size classes of grinding products in industrial and laboratory tests, show unfavorable granulometric composition, both in terms of low participation of optimal floating class (-74+37) μm 15.75 % and a relatively large share of classes, + 147 μm and - 37 μm, which achieve much worse technological indicators in the process of basic flotation. The great similarity of granulometric composition of the industrial grinding product, which works in a closed circuit of grinding and sizing, and discontinuous, laboratory grinding, indicates the lack of efficiency of industrial process. The consequences of ineffective grinding, improper values of circulative charge and decreased sharpness of classification in a closed cycle of grinding and classification, are overgrinding of material, i.e. the increased participation of the finest and coarsest class of definite grinding product, or worse technological parameters, copper recovery and concentrate quality in the basic flotation process.

The research results of the effect of grain-size distribution of the starting sample of size class -3.35 mm on the value of the Bond work index OF grindability, obtained by the method of shortened procedure by prof. N. Magdalinovic, clearly indicate that the characteristics of starting sample significantly affects the value of resistance to comminution. Differences in values of the Bond work index of grindability for low-grade copper ore of 5.4 kWh/t or about 42 % and high-grade copper ore of 3.77 kWh/t or about 35%, from the point of the theory of comminution and practical application in designing and selection of process equipment are of particular importance.

For achievement a complete efficiency of deposit without depletion of ore, with preservation of the Earth surface from deformations, the stope mining methods with backfilling are used, without leaving the safety pillars or with subsequent obtaining the safety pillars. For these purposes, backfilling of stope is done with necessary strength and deformation characteristics. The mathematical models are discussed in this work for selection the filling material depending on a function in the process of ore mining and after mining the deposit.

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