Zivan Zivkovic

The influence of the silicate slag composition on copper losses during smelting of the sulfide concentrates

This paper presents the results of multi-linear regression analysis (MLRA) of the slag composition (SiO2, FeO, Fe3O4, CaO, Al2O3) and the content of copper in the matte on resulting copper content in the slag during smelting of the sulfide concentrates in the reverberatory furnace. When comparing results obtained with MLRA model calculations with values measured at industrial level high degree of fitting is obtained (R2 = 0.974). This indicates that slag composition and content of copper in the matte influences the copper losses in the waste slag with the probability of 95 %.

Comparison of properties of silver-metal oxide electrical contact materials

Changes in physical properties such as density, porosity, hardness and electrical conductivity of the Ag-SnO2 and Ag-SnO2In2O3 electrical contact materials induced by introduction of metal oxide nanoparticles were investigated. Properties of the obtained silver-metal oxide nanoparticle composites are discussed and presented in comparison to their counterparts with the micro metal oxide particles as well as comparable Ag-SnO2WO3 and Ag-ZnO contact materials. Studied silvermetal oxide composites were produced by powder metallurgy method from very fine pure silver and micro- and nanoparticle metal oxide powders. Very uniform microstructures were obtained for all investigated composites and they exhibited physical properties that are comparable with relevant properties of equivalent commercial silver based electrical contact materials. Both Ag-SnO2 and Ag- SnO2In2O3 composites with metal oxide nanoparticles were found to have lower porosity, higher density and hardness than their respective counterparts which can be attributed to better dispersion hardening i.e. higher degree of dispersion of metal oxide in silver matrix.

Thermodynamic study of Ga-Sn and Ga-Zn systems using quantitative differential thermal analysis

The results of quantitative differential thermal analysis application in thermodynamic investigation of two gallium-based binary systems, Ga-Sn and Ga-Zn, are presented in this paper. Integral molar enthalpies of mixing in liquid state, as well as the activities, activity coefficients, and other partial and integral molar quantities were determined at the temperatures of 1000, 1073 and 1200 K (for Ga-Sn system) and 723 K (for Ga-Zn system). Obtained results were compared with literature data and comparison showed good agreement. Also, phase diagrams for the investigated simple eutectic systems were confirmed based on DTA curves and compared with literature.

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.

Thermodynamic and structural analysis of the Pb–InSb system

Abstract Results of thermodynamic and structural analysis of the Pb–InSb system are presented in this paper. Thermodynamic investigations were performed experimentally by Oelsen’s calorimetric method and calculated by thermodynamic predicting according to Chou’s general solution model, while structural analysis of the alloys in Pb–In–Sb system was done by SEM–EDX and diffractometry.

Assessment of the ISO 9001 functioning on an example of relations with suppliers development: empirical study for transitional economy conditions

In this paper, a model for the development of relationships with suppliers in order to create long-term partnerships, while following the requirements of ISO 9001 standard, was defined. Research has shown that the same relations with suppliers that exist between standardised companies (SC) and non-standardised companies (NSC) within the set of suppliers, also exist between NSC and NSC within the set of companies. Creating partnerships between SC and NSC suppliers is not possible, while obtained results show the opposite, which clearly indicates that the certification in the studied economy is being performed pro forma.

Effect of the Slag Basicity on the Coefficient of Distribution Between Copper Matte and the Slag for Certain Metals

This paper presents the results of investigation of the effect of slag composition and the slag basicity, in the process of smelting of sulfide copper concentrate, on the distribution coefficient ( ) for the following elements: Cu, Bi, Co, Au, Ag, Zn, Pb, Ni, As, Sb, Se, and Te. The research was conducted under the industrial operating conditions of the copper smelter in Bor, Serbia. High values for the coefficient of determination (R 2 > 0.6) for the dependence on the slag composition were obtained, which presents a high degree of fitting. In the case of the dependence of on the slag basicity, obtained R 2 values were much lower, due to the much smaller statistical sample.

Episodes of extremely high concentrations of SO2 and particulate matter in the urban environment of Bor, Serbia.

This paper presents the extremely high concentrations of SO2 and particulate matter measured in the urban area of the town Bor (Serbia) during August 2011. Concentrations of SO2 above 125 μg m(-3) and concentrations of particulate matter above 200 μg m(-3) recorded over several days indicate significant risk to human health and the ecosystem in this region.

ANFIS-Based Prediction of the Decomposition of Sodium Aluminate Solutions in the Bayer Process

This article presents the results of nonlinear statistical modeling of the decomposition process of sodium aluminate solution, as part of the Bayer technology for the production of alumina. Based on the data collected in 2011 and 2012 from industrial production in the Birač Alumina Factory, Zvornik (Bosnia and Herzegovina), nonlinear statistical modeling of the industrial processes was derived. The model was developed as an attempt to define the dependence of the degree of decomposition of sodium aluminate solution as a function of the input parameters of the leaching process: caustic ratio (αk) of the solution; ratio of the crystallization; content of Na2O(caustic) in the solution; the initial temperature of the solution; the final temperature of the solution; average diameter of the crystallized seeds; and duration of the crystallization process. As a tool for statistical modeling, Adaptive Network Based Fuzzy Inference System (ANFIS) was applied. The defined model using ANFIS methodology expressed a high level of fitting, and could be used to effectively predict the degree of decomposition of the sodium aluminate solution as a function of the input process under industrial conditions.

Multi-Criteria Decision Support System for Optimal Blending Process in Zinc Production

The formation of input batch zinc concentrates is one of the key processes on which the quality and efficiency of all subsequent operations during the production of zinc cathodes directly depends. The optimization of the formation of a mixed batch aims at making a selection between the zinc concentrates that have different contents of useful and harmful components and to determine their share in the optimal mix. A multi criteria optimization model, which can be a good support for the defined problem of determining the optimal mixture of zinc concentrates, was developed in this study. For an evaluation of this model, according to four different research scenarios, the PROMETHEE/GAIA methodology was used to rank the considered zinc concentrates and determine their optimal share in the mix batch. In addition, the determination of the significance of the criteria in the optimization model was performed by application of the subjective AHP approach and the objective entropic approach. The results of this study, which were obtained during an analysis of a real case from the practice of a zinc production facility, indicate that the choice and formation of the optimal mixture of concentrates directly depends on the subjective or objective type of assessment of the significance of several chemical components in the zinc concentrates, and on the market price of the considered concentrates.