Nada Štrbac

Kinetics and mechanism of Sb2S3 oxidation process

Abstract This paper presents the results of experimental investigations of Sb 2 S 3 oxidation process in an air atmosphere. Methods of investigation, including DTA–TG–DTG and DSC analysis, enabled the determination of heat effects, kinetic parameters and mechanism of the investigated process.

Developing a Questionnaire for Measuring Safety Climate in the Workplace in Serbia

This study was conducted because a real method for measuring safety climate had never been developed and assessed in Serbian industry. The aim of this paper was to start the process of developing a safety climate questionnaire that could be used in Serbia. As a starting point a 21-item questionnaire was adopted after an extensive literature review. The questionnaire was distributed at several Serbian factories; 1098 workers responded. After a statistical analysis of the data obtained with the questionnaire and a critical comparison with the available reference results, a final questionnaire with 21 questions, divided into 7 groups, was developed. The 7 groups of questions (factors) were safety awareness and competence, safety communication, organizational environment, management support, risk judgment and management reaction, safety precautions and accident prevention, and safety training.

Thermal study and mechanism of Ag2S oxidation in air

The results of thermal study and mechanism of the oxidation process of synthetic Ag2S in air are presented in this article based on the comparative analysis of DTA and XRD results, as well as by constructed phase stability diagrams (PSD) for the Ag–S–O system.

Influence of fluorides on polymorphous transformation of α-Al2O3 formation

Abstract Results of investigation into the influence of added fluorides (AlF3, CaF2, MgF2, LiF, NaF and Na3AlF6, up to 10%) at the temperature of the polymorphous transformation γ-Al2O3 ⇒ α-Al2O3 are presented. It was determined that, at a heating rate of 10°C min−1, addition of 2% fluoride decreases the transformation temperature by 400°C for AlF3, by 220°C for MgF2, and by 130°C for CaF2. The other fluorides have no effect. The mechanism of the influence is determined, and it can be explained by the formation of fluorine bridges between fluoride cations and aluminum on the γ-Al2O3 surface.

Kinetics and Mechanism of the Natural Mineral Marmatite Oxidation Process

Results obtained by the comparative investigations of the natural mineral marmatite (Zn,Fe)S (Stari Trg, Yugoslavia) oxidation process are presented in this paper.Determination of the oxidation process mechanism was done by thermal analysis methods: DTA-TG-DTG and DSC, while Mössbauer spectroscopy, X-ray and electronic microanalysis were used for phase composition determination of the products formed during the oxidation process. Kinetics of the process was defined for two temperature intervals 862–973 and 1023–1173 K, under isothermal conditions.

Physicochemical investigation of some archaeometallurgical findings from locality Kmpije (Bor, Serbia)

Preliminary results of physicochemical investigation of some archaeometallurgical findings from Kmpije locality in vicinity of Bor (Serbia) are presented in this paper. Ancient samples of prehistoric origin were investigated using different instrumental analytic methods—chemical, differential thermal, X-ray diffraction, and energy dispersive X-ray fluorescence analysis. Obtained results indicate to the presence of ancient metallurgical activities, so locality Kmpije may be considered as an archaeometallurgical site, which should be investigated more in future for more precise details.

Investigation of copper(I) sulphide leaching in oxidative hydrochloric acid solution

Present work is focused on the copper (I) sulphide leaching with sodium chloride in hydrochloric acid solution and with introduction of gaseous oxygen. Chemical reactions of leaching and their thermodynamic probabilities are predicted based on the literature data and products which were formed during the process and the overall leaching reaction was defined. The influence of temperature and time on the leaching degree of copper was experimentally determined. The quantity of dissolved copper increases with the increase of both investigated parameters. Elemental sulphur was formed as the main leaching product, precipitated at the particle surfaces and chloride ions have a role to disrupt the creation of this passive layer.

The Role of Infrared Spectroscopy and X-Ray Diffraction Analysis in the Investigation of the Influence of Fluorides on the Process of Calcination of Aluminium Hydroxide

Abstract The aim of this work was to check the possibility that by use of infrared spectroscopy the influence of fluorides on the calcinations process of aluminum hydroxide can be followed. The DTA method shows it clearly. It was, namely, found that the added fluoride influences the process of polymorphous transformation of the formation of α-Al2O3 from Al(OH)3. According to DTA, IR, and X-ray analyses, it was found that the added fluoride lowers the temperature of the mentioned transformation for some 300 degrees. For this purpose recorded were IR spectra and X-ray difractograms of pure AI(OH)3 as well as of such samples with added fluoride, in this case of AlF3, in the range of 0. 1 to 10 per cent. The samples were examined in the temperature range of 298 to 1673 K in different time intervals.

Monitoring the Process of Crystallization and Determination of the Degree of Crystallinity of NaA Zeolites by Infrared Spectroscopy

Abstract The course of crystallization and the degree of crystallinity of NaA zeolite, as well as its modified forms after treatment with HCl can be monitored by infrared cpectroscopy. As internal standard the band at 470cm−1, due to vibrations in the SiO4 tetrahedron may be used. During the crystallization process the amount of double fourfold rings (D4R) in the alumino-silicate gel increases which can be followed by the IR band at 560cm−1. The ratio of intensity of this band and the one at 470cm−1 increases in the course of crystallization.

MINING-METALLURGICAL SOURCES OF POLLUTION IN EASTERN SERBIA AND ENVIRONMENTAL CONSCIOUSNESS

The ethics of environmental protection is based on the moral responsibility of a man not to endanger his living environment because it is the only way for creating the conditions for a better life quality. Environmental consciousness (EC) is characterized by a high awareness about the environment, especially in urban areas with mining-metallurgical sources of pollution. Raising EC in such environments causes acceptance and ecological and social responsibility. A mining-metallurgical complex plant represents an important source of pollution of urban areas. In that sense, Bor is an interesting urban area having in mind that it represents one of the most important ore and metal production centers in South-East Europe. What defines the EC of Bor inhabitants is derived from the very town and its economy. The research encompasses concrete environmental problems of the mining town Bor and its surroundings. The components of the EC of people living in Bor were analyzed according to the awareness, knowledge and attitude method, having in mind the extent to which the environment has been polluted in this area. It has been concluded that the perception of people living in Bor about the state of the environment depends on numerous factors – first, whether the employee works for the RTB Bor Company or not.