Thermodynamic analysis of the Ga-Pb binary system

Thermodynamic properties of binary Ga-Pb alloys were investigated experimentally and analytically. Quantitative differential thermal analysis was used for determination of integral mixing enthalpies for the gallium-reach alloys, at the constant temperature inside the liquid two-phase region. Calculation of gallium activities in the temperature range of 800-1000 K was done using Chou’s calculation model developed for binary systems with miscibility gap existence

Thermodynamics of As, Sb and Bi distribution during reverb furnace smelting

The results of thermodynamic analysis of arsenic, antimony and bismuth distribution between copper matte and discard slag in reverberatory smelting at 1573 K are shown in this paper. On the basis of chemical analysis of the melt samples taken during stable operation of the reverb furnace No.2 in the Copper Smelter and Refinery, RTB Bor (Yugoslavia), the distribution coefficients of As, Sb, and Bi between copper matte and slag are calculated. The influence of the matte grade on the minor element distribution coefficients between copper matte and slag is also analyzed, as well as arsenic, antimony and bismuth distribution in slag

Life cycle assessment (LCA) of lead-free solders from the environmental protection aspect

Life-cycle assessment (LCA) presents a relatively new approach, which allows comprehensive environmental consequences analysis of a product system over its entire life. This analysis is increasingly being used in the industry, as a tool for investigation of the influence of the product system on the environment, and serves as a protection and prevention tool in ecological management. This method is used to predict possible influences of a certain material to the environment through different development stages of the material. In LCA, the product systems are evaluated on a functionally equivalent basis, which, in this case, was 1000 cubic centimeters of an alloy. Two of the LCA phases, life-cycle inventory (LCA) and life-cycle impact assessment (LCIA), are needed to calculate the environmental impacts. Methodology of LCIA applied in this analysis aligns every input and output influence into 16 different categories, divided in two subcategories. The life-cycle assessment reaserch review of the leadfree solders Sn-Cu, SAC (Sn-Ag-Cu), BSA (Bi-Sb-Ag) and SABC (Sn-Ag-Bi-Cu) respectively, is given in this paper, from the environmental protection aspect starting from production, through application process and finally, reclamation at the end-of-life, i.e. recycling. There are several opportunities for reducing the overall environmental and human health impacts of solder used in electronics manufacturing based on the results of the LCA, such as: using secondary metals reclaimed through post-industrial recycling; power consumption reducing by replacing older, less efficient reflow assembly equipment, or by optimizing the current equipment to perform at the elevated temperatures required for lead-free soldering, etc. The LCA analysis was done comparatively in relation to widely used Sn-Pb solder material. Additionally, the impact factors of material consumption, energy use, water and air reserves, human health and ecotoxicity have been ALSO considered including the potentials for dissolution and recycling processes

Кинетика и механизам процеса оскидације једињења Аs2S2

The kinetics of realgar (As2S2) oxidation was studied under isothermal and non-isothermal conditions. The obtained values of the activation energy indicate that the process occurs in the kinetic domain with the realgar particles being converted to As2O3 and AS 4O6 (g). The very fast reaction rates were limited by the chemical reaction. The kinetic equation was found to be: -In (1-α) = 4.56 × 103 × e(-8780/T) × t. The proposed reaction mechanism and chemical transformation investigated by ICP-AES, EDXRF and thermal analysis are discussed.У овом раду представљена су истраживања кинетике процеса оксидације једињења реалгара (Аs2S2) у изотермским и неизотермским условима. Добијене вредности енергије активације указују да се процес одвија у кинетичкој области при чему се честице реалгара оксидишу до Аs2О3 и Аs4О6(g). Кинетичка једначина која најбоље описује посматрани процес је: (1-α) = 4.56 × 103 × e(-8780/T) × t. У раду је предложен реакциони механизам и презентовани су резултати ICP-AES, EDXRF и термалне анализе

Optimization of the arsenic removal process from enargite based complex copper concentrate

Selective arsenic extraction from enargite based complex concentrate from Copper Mine in Bor (Serbia), using sodium hypochlorite as a leaching agent, was investigated in this paper. The aim was to assess the optimal conditions for the most efficient arsenic removal from the investigated concentrate, based on factorial design applied to experimentally obtained data. Five important factors with three factor levels were used as the input variables and experimentally obtained arsenic extraction yield was taken as the output variable. The first and the second final order model equations were obtained. It was found that the leaching temperature had the strongest effect on the arsenic extraction. The strongest positive interaction was between the sodium hypochlorite molar concentration and the stirring speed during extraction. [Projekat Ministarstva nauke Republike Srbije, br. TR 34023

Effect of degree of crystallinity and the contents of aluminium oxide and sodium oxide on water sorption capacity in NaY zeolite

The paper presents mathematical models which describe the dependence between water sorption capacity, on one hand, and the degree of crystallinity and the content of Na2O and Al2O3 in NaY zeolite, on the other. NaY was synthesized from sodium aluminate solution, water glass and sulfuric acid under different conditions of crystallization. The obtained zeolite powders underwent chemical analysis (Na2O, Al2O3), water sorption capacity (WSC), as well as diffraction analysis which served to determine the degree of crystallinity (CD). Zeolite powder samples had the following values: for the content of Na2O from 13.81 to 16.14%, for Al2O3 from 21.58 to 27.17%, degree of crystallinity from 58.70 to 114.00 and WSC from 21.32 to 36.59%, and regression analysis lead to the conclusion that there is a significant correlation between water sorption capacity and the degree of crystallinity, unlike the contents of Na2O and Al2O3 in the zeolite powder, whose correlation with water sorption capacity was neglibile. The mathematical model obtained by linear regression analysis had a high R2= 0.796, where as non-linear regressional analysis produced a better mathematical model R2= 0.912, where water sorption capacity was expressed through a quadratic model

Nacionalni program biotehnologija i agroindustrija - program unapređenja stočarstva i proizvoda animalnog porekla, studija projekta: Proizvodnja kvalitetnih svinjskih polutki

The object of this research-developmental project is the production of quality pig halves. By the application of various methods of selection and breeding along with optimal conditions of nutrition, care and keeping carcass quality of breeding animals and fatteners shall be improved. Another aim of the project is the improvement of health state and performance of pigs by securing optimal microclimate factors, keeping conditions and housing system. The economical valorization of quality pig halves shall also be established. The research has been carried out in three breeding stocks (Breeding stock 1 - PKB "IMES" AD, Padinska Skela; Breeding stock 2 - DP "Stari Tamiš", Pančevo; Breeding stock 3 - Institute for Animal Husbandry also one of parties who realize the project) who are all the users of the research results. In the second year of research we worked on the improvement of reproductive traits of breeding pigs as well as fattening and slaughter traits of three-race and four-race crossing breeds, optimal nutrition, possible use of probiotics in the nutrition of piglets and fatteners, preventing of digestive disorders by use of various probiotic populations, establishing microclimate factors and economical indicators in pig production. In the first two research years the results were published in leading scientific journals of national importance, and reported at the international and national scientific meetings. The study displays the published results of the project in question