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Differential thermal analysis (DTA) and thermal gravimetric analysis (TGA), at a heating rate of 10 ЊC/min, revealed a complete reduction of NiCl 2 by hydrogen in a temperature interval of 375 ЊC to 450 ЊC. However, addition of 0.1 mass pct of Pd, Cu, or Ni to the sample caused the reduction to occur at considerably lower temperatures, in the rather narrow range of 315 ЊC to 370 ЊC. The activation energy of NiCl 2 reduction by hydrogen (between 300 ЊC and 550 ЊC) without additives is 54 kJ/mol, and with Pd and Cu or Ni added, under isothermal conditions (from 260 ЊC to 380 ЊC), is 33 and 50 kJ/mol, respectively. These values confirm a positive effect of additives on the reduction kinetics. The positive effect of Pd is a consequence of the dissociation and spillover of hydrogen, whereas in the case of Cu and Ni(HCOO) 2 , it is manifested in a decrease in bonds energy in the nickel lattice because of good Cu solubility, and in the formation of artificial nickel nuclei that intensify the reduction, respectively. Scanning electron microscopy (SEM) analysis of nickel powders obtained under isothermal conditions shows relatively rounded spherical particles (0.321 to 0.780 m in size) of powder samples with additives, and particles of irregular shape (2.085 m mean size) of the sample without additives. This illustrates the positive effect of Pd, Cu, or Ni added in the reduction process, in decreasing the size of nickel particles and in the production of a more uniform particle shape.

Selecting the best mining method among many alternatives is a multicriteria decision making problem. The aim of this paper is to demonstrate the implementation of an integrated approach that employs AHP and PROMETHEE together for selecting the most suitable mining method for the "Coka Marin" underground mine in Serbia. The related problem includes five possible mining methods and eleven criteria to evaluate them. Criteria are accurately chosen in order to cover the most important parameters that impact on the mining method selection, such as geological and geotechnical properties, economic parameters and geographical factors. The AHP is used to analyze the structure of the mining method selection problem and to determine weights of the criteria, and PROMETHEE method is used to obtain the final ranking and to make a sensitivity analysis by changing the weights. The results have shown that the proposed integrated method can be successfully used in solving mining engineering problems.

This paper presents the investigation of the air-pollution management possibility in Bor (Serbia) using statistical analyses of the correlation dependence of SO(2) pollution concentration and meteorological parameters. This kind of approach allows data to determine the shape of time trends; models serial correlation and dependence on covariance; and provides statistical analyses of data. Air quality control in the area of Bor is measured at four monitoring stations: City park; Institute of Mining and Metallurgy; Jugopetrol oil logistic centre and Brezonik suburb. There is also a meteorological station near the aforementioned institute that measures temperature; air humidity; atmosphere pressure; wind speed and direction. The results received from all monitoring stations are processed by the Institute of Mining and Metallurgy in Bor. The data from the reported documents were used for statistical analyses, for determining the correlation between SO(2) emission concentration and meteorological parameters. The source of SO(2) emissions is the local copper smelter, built within the town of Bor from 1961-1963. However, the disposition of the pollutant concentration is influenced by meteorological parameters (air humidity, atmosphere pressure, speed and wind direction). The successful application of these statistical analyses in this paper points to a possibility of its usage in air pollution studies.