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Modern industrial product design implies presence of many different materials. Consequently, in the recycling process, shredding and separation procedures are applied. However, all materials cannot be completely separated; therefore, there is a contamination in the recycling streams. The quality of the materials streams can be reduced in each of the following recycling steps. These qualitative losses cannot be described by material balance. This paper presents the concept of exergy as a measure of quality losses, and gives the methods for the calculation of the exergy content and the exergy loss. Losses attributed to the recycling or material losses, material contamination losses and dilution requirements can be used as indicators for the materials quality loss as well as for the resource efficiency in the production systems. In this paper, the example of calculations on the steel scrap is presented., Dizajn modernih industrijskih proizvoda je takav da oni predstavljaju kompleksne spojeve različitih materijala. Zbog toga se u postupku reciklaže materijala primenjuju procesi usitnjavanja i razdvajanja. Međutim materijali se ne mogu u potpunosti razdvojiti i zbog toga dolazi do kontaminacija u reciklažnim tokovima. Zbog toga se kvalitet materijala može smanjivati u svakom narednom reciklažnom koraku. Ovakvi kvalitativni gubici ne mogu se opisati masenim bilansom, i u radu je prikazan eksergijski koncept kao merilo gubitaka kvaliteta, odnosno dat je metod za izračunavanje eksergijskog sadržaja i eksergijskog gubitka. Gubici pripisani reciklaži ili tačnije materijalni gubici, gubici usled kontaminacije drugim metalima i posledično potreba za razblaživanjem, mogu se koristiti kao indikatori gubitka kvaliteta materijala i efikasnosti korišćenja resursa u proizvodnim sistemima. U radu je dat primer proračuna na čeličnom otpadu.

Dizajn modernih industrijskih proizvoda je takav da oni predstavljaju kompleksne spojeve različitih materijala. Zbog toga se u postupku reciklaže materijala primenjuju procesi usitnjavanja i razdvajanja. Međutim materijali se ne mogu u potpunosti razdvojiti i zbog toga dolazi do kontaminacija u reciklažnim tokovima. Zbog toga se kvalitet materijala može smanjivati u svakom narednom reciklažnom koraku. Ovakvi kvalitativni gubici ne mogu se opisati masenim bilansom, i u radu je prikazan eksergijski koncept kao merilo gubitaka kvaliteta, odnosno dat je metod za izračunavanje eksergijskog sadržaja i eksergijskog gubitka. Gubici pripisani reciklaži ili tačnije materijalni gubici, gubici usled kontaminacije drugim metalima i posledično potreba za razblaživanjem, mogu se koristiti kao indikatori gubitka kvaliteta materijala i efikasnosti korišćenja resursa u proizvodnim sistemima. U radu je dat primer proračuna na čeličnom otpadu., Modern industrial product design implies presence of many different materials. Consequently, in the recycling process, shredding and separation procedures are applied. However, all materials cannot be completely separated; therefore, there is a contamination in the recycling streams. The quality of the materials streams can be reduced in each of the following recycling steps. These qualitative losses cannot be described by material balance. This paper presents the concept of exergy as a measure of quality losses, and gives the methods for the calculation of the exergy content and the exergy loss. Losses attributed to the recycling or material losses, material contamination losses and dilution requirements can be used as indicators for the materials quality loss as well as for the resource efficiency in the production systems. In this paper, the example of calculations on the steel scrap is presented.

Proizvodnja obojenih metala iz sekundarnih sirovina daleko je jeftinija od njihove proizvodnje iz primarnih sirovina, prvenstveno zbog manje potrošnje energije. Pored toga, reciklažom obojenih metala iz sekundarnih sirovina racionalnije se koriste prirodni resursi i smanjuje količina otpadnih materijala, čime se direktno štiti životna sredina. Sekundarne sirovine obojenih metala nastaju u procesu proizvodnje i prerade metala do njihove ugradnje u gotove priozvode i izbacivanjem tih proizvoda iz upotrebe usled njihove dotrajalosti ili tehnološke zastarelosti. U zavisnosti od vrste sekundarne sirovine, koriste se različiti postupci pripreme i metalurške prerade. Pojedine se veoma jednostavno recikliraju pretapanjem u metalurškim agregatima, dok druge moraju proći komplikovane operacije pripreme pre metalurške prerade., Production of non ferrous metals from secondary raw materials is far less costly than its production from primary raw materials, due to lower energy consumption. Besides, by recycling of non ferrous metals from secondary raw materials, the natural resources are saved and the amount of waste materials is reduced, directly protecting the environment. The secondary raw materials can originate in metal production and treatment, accompanied by their incorporation into the final product and its elimination due to amortization. The different methods of preparation and metallurgical treatment are used depending on secondary raw materials type. Some of them are very easy to be recycled by remelting in metallurgical furnace, while others must pass through complicated preparation before metallurgical treatment.

Electromagnetic casting (EMC) is the technology developed as by combining the magnetic hydrodynamics and casting technique. Electromagnetic forces, arising from the interaction of Eddy currents induced in the metal by inductor magnetic field, cause an increased flow of the fluid, forced convection, more uniform temperature field and weak gravitation influence thus changing the conditions of solidification. The advantage of EMC reflects in obtaining a better quality of ingots compared to convent ional continuous casting process. Namely, the structure obtained is finer and more uniform through the cross section, with reduced segregation of alloy element and porosity. Apart from that, due to the reduced contact pressure (result of electromagnetic field effect) between the mould and the metal, the quality of ingot surface is improved, having no need for additional machine processing. The investigations conducted in the world were aimed to investigate the effect of electromagnetic, magnetic and hydrodynamic phenomena on Al ingots, but very little attention was given to the characterization of microstructure and mechanical properties. This work, should contribute to better knowledge of the effect of electromagnetic field on the obtained microstructure (morphology, size, volume fraction and distribution of phases) and properties of Al alloys. The chosen alloy was EN AW 7075 heat treatable, intended for forge with wide industry use. It is characterized by a number of defects that occur during the solidific ation process: porosity, hot cracks, non -uniformal grain size and crystal segregation. Since the quality of final product is directly affected by these defects it is necessary to prevent or reduce their appearance by the choice of the appropriate process and optimal parameters of casting. To compare the results of electromagnetic casting, (with different operating parameters), the process of vertical continual casting without the presence of low frequency electromagnetic, Elektromagnetni postupak livenja zasniva se na teoriji metalurških procesa i magnetohidrodinamici. Prilikom livenja u prisustvu elektromagnetnog polja naizmenična struja generiše vremenski promenljivo mognetno polje u istopljenoj masi što povećava indukovanu struju u rastopu. Rastop metala je pod uticajem elektromagnetne sile koja je prouzrokovana interakcijom indukovane struje i magnetnog polja. Elektromagnetna sila izaziva veći protok fluida, prinudnu konvekciju, ravnomernije temperaturno polje i slabiji uticaj gravitacije. Na ovaj način se menjaju uslovi očvršćavanja. Dobijeni odlivci su kvalitetniji, struktura je finija i uniformnija po preseku. Zbog smanjenog kontaktnog pritiska, (što je takođe posledica delovanja elektromagnetnog polja) između kalupa i metala, kvalitet površine je poboljšan tako da nije potrebna veća dodatna mašinska obrada. U svetu postoje određena istraživanja u oblasti elektromagnetnog postupka livenja, ali je malo pažnje posvećeno karakterizaciji mikrostrukture i mehaničkih svojstava tako dobijenih odlivaka. Ovaj rad treba da doprinese boljem poznavanju uticaja elektromagnetnog polja na dobijenu mikrostrukturu (morfologiju, veličinu zrna, raspodelu i udeo dobijenih faza) i ostale karakteristike dobijenih odlivaka. Izabrana legura EN AW 7075 ima široku primenu u industriji, termički je obradiva i namenjena je za plastičnu preradu odnosno kovanje. Proizvodnja ove legure je dugotrajna i skupa, a prate je nedostaci tipa poroznosti, toplih pukotina i neujednačenosti u veličini zrna. Ove metalurške greške utiču na pogoršanje mehaničkih svojstava i kvaliteta dobijenih odlivaka. U cilju smanjenja ovih grešaka još u livenom stanju neophodno je primeniti odgovarajući postupak livenja sa optimalnim radnim parametrima. Da bi se ispitao uticaj elektromagnetnog polja prilikom livenja upoređeni su uzorci odliveni bez dejstva polja i pod dejstvom polja različite frekvencije 10, 15, 20 i 30 Hz. Rezultati ispitivanja mikrostrukture i mehaničkih svojstava po

The grain boundary groove (GBG) developing at the ceramic substrate under the liquid metal is evident, yet not fully explained influencing appearance in describing the wetting phenomena at liquid metal/ceramics interface. The focus here is on modelling of the phenomena at/around a groove between grains depending on grooves' geometry. Based on atomic force microscopy results, the groove efficiency assessment is provided as a function of the transferred mass quantity and related to grooves geometry. The transferred mass quantity and, according to it, the groove efficiency at parabolic GBG is about 10% higher comparing to the triangular GBG.

Aflatoxin B-1 adsorption by the concentrate of bentonite clay - montmorillonite and the natural zeolite -clinoptilolite and was investigated at the initial toxin concentration of 4 ppm, with different amounts of solid phase in suspension (1, 0.5, 0.2 and 0.1 g/L) and different pH values - 3, 7 and 9. Results indicated that for both minerals, decreasing the amount of solid phase in suspension, decrease the amount of active sites relevant for adsorption of aflatoxin B-1. Thus, for concentrate of montnorillonite, at the lowest level of solid phase in suspension (0.1 g/L), aflatoxin B-1 adsorption indexes were 97% at pH 3, 88% at pH 7 and 82% at pH 9, while for the natural zeolite, adsorption of toxin was 9% at pH 3 and 7% at pH 7 and 9. Since inorganic cations in minerals are mainly responsible for aflatoxin B-1 adsorption, even the natural zeolite - clinoptilite has much higher cation exchange capacity (the content of inorganic exchangeable cations) compared to the concentrate of montmorillonite, adsorption of aflatoxin B-1 by this mineral is much lower. Comparing the molecular dimensions of aflatoxin B-1 molecule with the dimension of channels of clinoptilolite and interlamellar space of montmorillonite it is obvious that this toxin is adsorbed only at the external surface of clinoptilolite while in the montmorillonite all active sites are equally available for its adsorption. Thus, the concentrate of montmorillonite possesses higher adsorption capacity for aflatoxin B-1. Results presented in this paper confirmed the fact that the differences in the structure of minerals led to their different efficiency for adsorption of aflatoxin B-1. Mineralogical and chemical composition, determination of cation exchange capacity, etc., are very important parameters influencing the effectiveness of minerals as aflatoxin B-1 adsorbents.

Materials for recycling always contain a certain degree of contamination. The presence of impurities i.e. contamination in the recycling streams causes a change in the composition of the original materials to recycle. As a result, the quality of materials can be reduced in each successive step of recycling. In addition, the resources of lower quality are produced from the resource flows which had a higher quality in their original form. This kind losses of quality cannot be measured by mass balance, as well as the quality degradation not only can display measurements of mass. For the calculation of all losses caused by recycling contaminations, all further recycling processes required to return the materials back into resource cycles must be included. The method for calculating the exergy content and exergy losses of metal solutions during recovery and recycling is presented in this paper. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, exergy is proposed here as a measure of the efficiency of resources use. This paper presents calculations of exergy losses during recycling shown in the case of aluminum waste., Materijali za recikliranje uvek sadrže izvestan stepen nečistoća. Prisustvo nečistoća tj. kontaminacija u reciklažnim tokovima izaziva promenu u izvornom sastavu materijala za reciklažu. Usled toga, kvalitet materijala može se smanjivati u svakom narednom koraku reciklaže. Pored toga, resursi nižeg kvaliteta proizvedeni su iz resursnih tokova koji su u izvornom obliku imali viši kvalitet. Ovakvi gubici kvaliteta ne mogu da se mere masenim bilansima, isto kao što se degradacija kvaliteta ne može prikazati samo merenjem mase. Za proračun svih gubitaka prouzrokovanih reciklažnom kontaminacijom, svi dalji procesi reciklaže potrebni da bi se materijali vratili nazad u resursne cikluse moraju biti uključeni. U ovom radu prikazan je metod za izračunavanje eksergijskog sadržaja i eksergijskog gubitka metalnih rastvora u toku iskorišćnja i reciklaže. Gubici pripisani reciklaži ili tačnije materijalni gubici, gubici usled kontaminacije drugim metalima i posledično potreba za razblaživanjem, mogu se koristiti kao indikatori gubitka kvaliteta materijala i efikasnosti korišćenja resursa u proizvodnim sistemima. Dakle, ovde je eksergija predložena kao mera efikasnosti korišćenja resursa. U radu su proračuni eksergijskih gubitaka tokom reciklaže prikazani na primeru aluminijumskog otpada.

Procedures for copper secondary raw materials processing include two basic stages: pretreatment of the copper waste and its further metallurgical processing. For copper waste pretreatment technology, there are different applied procedures depending on the type of raw material. All operations of pretreatment are influencing the quality of metallurgical processing. For metallurgical processing of raw materials prepared for the purpose of obtaining copper and copper alloys the shaft, flaming and short-drum furnaces, converters and electric furnaces (electric resistant, electric arc and induction furnaces) are used., Postupci prerade sekundarnih sirovina bakra uključuju dva osnovna stupnja: pripremu bakarnih otpadaka i njihovu dalju metaluršku preradu. Za pripremu bakarnih otpadaka koriste se različiti postupci u zavisnosti od vrste i kvaliteta sekundarne sirovine. Sve operacije pripreme utiču na kvalitet metalurške prerade, odnosno na kvalitet proizvoda. Za topljenje pripremljenih sekundarnih sirovina u cilju dobijanja legura na bazi bakra koriste se razni agregati: šahtne peći, konvertori, plamene lončaste i koritaste plamene peći, kratke bubnjaste peći i električne peći (elektrolučne, elektrootporne, indukcione).

Besides iron ore, the main raw material of iron and steel production is steel scrap. This paper presents the quality and sources of creation the iron and steel scrap and estimation of their creation in the future. The content of impurities and trace elements to the scrap is very important and influencing to the quality of the obtained steel. Alloyed steel scrap known composition can often be used as an addition to a metal charge for steel production of the desired composition. Considering the steel scrap formation, the three major groups are elaborated: own scrap or circulation scrap, processing scrap and amortization scrap. The balancing model for estimating of steel scrap creation is based on the calculating the coefficients of the generation circulation, processing and amortization scrap, which are used as the basis for successful modelling., Čelični otpadak je, pored železne rude, najvažnija sirovina za proizvodnju gvožđa i čelika. U radu je prikazan kvalitet i izvori nastajanja otpadaka gvožđa i čelika i prognoza njihovog nastajanja u budućnosti. Sadržaj nečistoća i oligoelemenata u otpatku je veoma važan i utiče na kvalitet dobijenog čelika. Legirani čelični otpadak poznatog sastava često može biti iskorišćen kao dodatak metalnom ulošku za proizvodnju čelika željenog sastava. U zavisnosti od mesta nastajanja razlikujemo tri grupe čeličnog otpatka: vlastiti ili recirkulacioni, otpadak pri obradi i amortizacioni otpadak. Model bilansiranja za prognozu nastajanja čeličnog otpatka zasnovan je na izračunavanju koeficijenata nastajanja proizvodnog i amortizacionog otpatka koji služe kao osnova za uspešno prognoziranje njihovog nastajanja u budućnosti.

Čelični otpadak je, pored železne rude, najvažnija sirovina za proizvodnju gvožđa i čelika. U radu je prikazan kvalitet i izvori nastajanja otpadaka gvožđa i čelika i prognoza njihovog nastajanja u budućnosti. Sadržaj nečistoća i oligoelemenata u otpatku je veoma važan i utiče na kvalitet dobijenog čelika. Legirani čelični otpadak poznatog sastava često može biti iskorišćen kao dodatak metalnom ulošku za proizvodnju čelika željenog sastava. U zavisnosti od mesta nastajanja razlikujemo tri grupe čeličnog otpatka: vlastiti ili recirkulacioni, otpadak pri obradi i amortizacioni otpadak. Model bilansiranja za prognozu nastajanja čeličnog otpatka zasnovan je na izračunavanju koeficijenata nastajanja proizvodnog i amortizacionog otpatka koji služe kao osnova za uspešno prognoziranje njihovog nastajanja u budućnosti., Besides iron ore, the main raw material of iron and steel production is steel scrap. This paper presents the quality and sources of creation the iron and steel scrap and estimation of their creation in the future. The content of impurities and trace elements to the scrap is very important and influencing to the quality of the obtained steel. Alloyed steel scrap known composition can often be used as an addition to a metal charge for steel production of the desired composition. Considering the steel scrap formation, the three major groups are elaborated: own scrap or circulation scrap, processing scrap and amortization scrap. The balancing model for estimating of steel scrap creation is based on the calculating the coefficients of the generation circulation, processing and amortization scrap, which are used as the basis for successful modelling.

In this study the mechanical properties (reduction of area, S-0, tensile strength, R-m, yield strength, R-p, and elongation, A) of EN AW 7075 aluminum alloy obtained by electromagnetic casting were investigated at different operating parameters: frequency (V), field strength (T) and current intensity (I). The predictive mathematical models using Response Surface Methodology, with second order polynomial (SOP) regression models, and Artificial Neural Network model (ANN), were afterwards compared to obtained experimental results. Analysis of variance and post-hoc Tukey's HSD test at 95% confidence limit ("honestly significant differences") have been utilised to show significant differences between various samples. SOP models showed good prediction capabilities, with high coefficients of determination (r(2)), 0.531-0.977, while ANN model performed even better prediction accuracy: 0.800-0.992. The optimal samples were chosen depending on mechanical properties of the product (S-0 = 50.49mm(2), R-m = 405.75Nmm(-2), R-p = 302.49Nmm(-2), A = 6.86%), using optimal operating parameters (V = 30 Hz, I = 250 A, T = 18 x 10(-3) At).

Postupci prerade sekundarnih sirovina bakra uključuju dva osnovna stupnja: pripremu bakarnih otpadaka i njihovu dalju metaluršku preradu. Za pripremu bakarnih otpadaka koriste se različiti postupci u zavisnosti od vrste i kvaliteta sekundarne sirovine. Sve operacije pripreme utiču na kvalitet metalurške prerade, odnosno na kvalitet proizvoda. Za topljenje pripremljenih sekundarnih sirovina u cilju dobijanja legura na bazi bakra koriste se razni agregati: šahtne peći, konvertori, plamene lončaste i koritaste plamene peći, kratke bubnjaste peći i električne peći (elektrolučne, elektrootporne, indukcione)., Procedures for copper secondary raw materials processing include two basic stages: pretreatment of the copper waste and its further metallurgical processing. For copper waste pretreatment technology, there are different applied procedures depending on the type of raw material. All operations of pretreatment are influencing the quality of metallurgical processing. For metallurgical processing of raw materials prepared for the purpose of obtaining copper and copper alloys the shaft, flaming and short-drum furnaces, converters and electric furnaces (electric resistant, electric arc and induction furnaces) are used.

Za proizvodnju odlivaka od kojih se izrađuju zubni implantati, ortodontski aparati i pomoćni materijali koristi se više legura Co-Cr-Mo, različitog sastava. Ovde je reč o leguri, koja pored odsustva nikla, svoje biokompatibilnosti i otpornosti na koroziju, ima odlične mehaničke karakteristike, kao što su tvrdoća, zatezna čvrstoća i žilavost. Predstavljena je tehnologija pripreme sirovina, kao i izrada same legure u vidu uzoraka-tabletica od kojih se izradjuju zubni implantati, tehnologijom preciznog livenja u vakuumu, korišćenjem metode topivih modela. Osim eksperimantalnih parametara, praćen je hemijski sastav od polaznih sirovina do gotove legure. Prikazana je mikrostruktura uzoraka u livenom stanju., There are several biocompatible Co-Cr-Mo alloy compositions, as well as technological processes suitable for obtaining the tablet samples aimed to produce dental implants and orthodontic devices. Here presented Co-Cr-Mo alloy, besides its biocompatibility, corrosion resistance, and nickel absence, is favorable for its mechanical properties, such as hardness, tensile and fatigue strength. The technology for raw materials preparation and manufacturing of a Co-Cr-Mo alloy for dental implants vacuum precise casting is presented here. Besides the technological process characteristics, there are the chemical analysis of raw materials, alloy obtaining guidelines and microstructure of as-cast samples.

Materijali za recikliranje uvek sadrže izvestan stepen nečistoća. Prisustvo nečistoća tj. kontaminacija u reciklažnim tokovima izaziva promenu u izvornom sastavu materijala za reciklažu. Usled toga, kvalitet materijala može se smanjivati u svakom narednom koraku reciklaže. Pored toga, resursi nižeg kvaliteta proizvedeni su iz resursnih tokova koji su u izvornom obliku imali viši kvalitet. Ovakvi gubici kvaliteta ne mogu da se mere masenim bilansima, isto kao što se degradacija kvaliteta ne može prikazati samo merenjem mase. Za proračun svih gubitaka prouzrokovanih reciklažnom kontaminacijom, svi dalji procesi reciklaže potrebni da bi se materijali vratili nazad u resursne cikluse moraju biti uključeni. U ovom radu prikazan je metod za izračunavanje eksergijskog sadržaja i eksergijskog gubitka metalnih rastvora u toku iskorišćnja i reciklaže. Gubici pripisani reciklaži ili tačnije materijalni gubici, gubici usled kontaminacije drugim metalima i posledično potreba za razblaživanjem, mogu se koristiti kao indikatori gubitka kvaliteta materijala i efikasnosti korišćenja resursa u proizvodnim sistemima. Dakle, ovde je eksergija predložena kao mera efikasnosti korišćenja resursa. U radu su proračuni eksergijskih gubitaka tokom reciklaže prikazani na primeru aluminijumskog otpada., Materials for recycling always contain a certain degree of contamination. The presence of impurities i.e. contamination in the recycling streams causes a change in the composition of the original materials to recycle. As a result, the quality of materials can be reduced in each successive step of recycling. In addition, the resources of lower quality are produced from the resource flows which had a higher quality in their original form. This kind losses of quality cannot be measured by mass balance, as well as the quality degradation not only can display measurements of mass. For the calculation of all losses caused by recycling contaminations, all further recycling processes required to return the materials back into resource cycles must be included. The method for calculating the exergy content and exergy losses of metal solutions during recovery and recycling is presented in this paper. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, exergy is proposed here as a measure of the efficiency of resources use. This paper presents calculations of exergy losses during recycling shown in the case of aluminum waste.

In this paper the procedure of obtaining of high purity magnesium by using the vacuum distillation process has been shown. Vacuum distillation process has been conducted under low and high vacuum at different operating temperatures and times. Also, the condenser structure in vacuum equipment is set up in such a way to get the optimal conditions for obtaining of high purity magnesium. Based on experimental results, optimal process parameters were determined which justify the economy and technology of the process., U ovom radu opisana je procedura dobijanja metalnog magnezijuma visoke čistoće, korišćenjem tehnologije vakumske destilacije. Ispitivan je uticaj različitih parametra temperature i vremena vakuumske destilacije, kao i uticaj niskog i visokog vakuma na proces dobijanja magnezijuma visoke čistoće. Takođe, struktura kondezatora, u opremi za vakuumsku destilaciju, je podešavana na takav način da se dobijaju optimalni uslovi procesa vakuumske destilacije. Na osnovu eksperimentalnih ispitivanja, određeni su optimalni parametri procesa vakuumske destilacije, koji opravdavaju ekonomiju i tehnlogiju procesa.

With the recently increased use of magnesium alloys, especially in the automotive industry, a large quantity of generated waste, based on magnesium alloys, is expected. Such a waste often contains many impurities such as oil, paint, moisture, non-metallic fractions, oxides, Cu, Fe, etc. In this paper, two different methods for extracting magnesium from a highly contaminated waste are presented: the recycling of magnesium with flux and with the vacuum-distillation process. In addition, we present the process of pre-treating the contaminated magnesium waste that has proved to be a very important step in the recycling process for both economic and environmental reasons. The processing of post-consumer and contaminated magnesium scrap is described with a diagram, providing a sustainable and environmentally friendly procedure for the treatment of such wastes.

U ovom radu je ispitivana mogućnost dobijanja maskirnog pigmenta mehanohemijsko termičkim postupkom kao i energetsko učešće mehanohemijskog tretmana u dobijanju maskirnog pigmenta stehiometrijske formule Co0,51Zn0,29Mg0,41Cr1,24Al0,24Ti0,31O4. Mehanohemijski i termički tretirani uzorci smeše oksida radi dobijanja kompleksnog spinela su eksperimentalno istraživani u više serija opita, pri čemu su menjani parametri vezani za rad visokoenergetskog vibracionog mehanoaktivatora. Mehanohemijskom aktivacijom smeše oksida (Cr2O3, CO-oksida, ZnO, TiO2, MgO i Al2O3), u vibracionom mehanoaktivatoru sa prstenovima od 30; 60 i 90 min, a zatim termičkim tretiranjem u elektrootpornoj peći, pri vremenu zadržavanja uzorka od 1h, dobija se materijal spinelne strukture koji je pogodan kao maskirni pigment u vojnoj industriji., In this paper the possibility of obtaining masking pigment mechanochemically thermal process and the energy share of mechanochemical treatment in obtaining masking pigment by stoichiometric formula (Co 0.51 Zn 0.29 Mg 0.41 Cr 1.24 Al 0.24 Ti 0, 31 O 4). Mechanochemical and heat treated samples to obtain a mixture oxide spinel complex were experimentally investigated in a series of experiments wherein the altered parameters related to the operation of high energy vibratory mechanoactivator. Mechanochemical activation mixture oxide (Cr2O 3, C-O oxide, ZnO, TiO 2, MgO and Al 2 O 3), in vibration mechanoactivator with rings of 30; 60 and 90 min, and then, heat treatment in an electric furnace, with the sample retention time of 1 hour, the material is obtained, which spinel structure is suitable as the pigment in the masking military industry.

The effect of tempering at 450 - 650A degrees C of different duration on mechanical properties and microstructure of a cast low-alloy steel is investigated. The ultimate rupture strength, the yield strength, the elongation and the Vickers hardness of the steel are determined. Metallographic analysis is performed.

U ovom radu opisana je procedura dobijanja metalnog magnezijuma visoke čistoće, korišćenjem tehnologije vakumske destilacije. Ispitivan je uticaj različitih parametra temperature i vremena vakuumske destilacije, kao i uticaj niskog i visokog vakuma na proces dobijanja magnezijuma visoke čistoće. Takođe, struktura kondezatora, u opremi za vakuumsku destilaciju, je podešavana na takav način da se dobijaju optimalni uslovi procesa vakuumske destilacije. Na osnovu eksperimentalnih ispitivanja, određeni su optimalni parametri procesa vakuumske destilacije, koji opravdavaju ekonomiju i tehnlogiju procesa., In this paper the procedure of obtaining of high purity magnesium by using the vacuum distillation process has been shown. Vacuum distillation process has been conducted under low and high vacuum at different operating temperatures and times. Also, the condenser structure in vacuum equipment is set up in such a way to get the optimal conditions for obtaining of high purity magnesium. Based on experimental results, optimal process parameters were determined which justify the economy and technology of the process.

Eksperimentalnim istraživanjima su definisani kako tehnološka šema dobijanja kalcijuma iz krečnjaka aluminotermijskim procesom tako i osnovni radni parametri pojedinih tehnoloških faza. Uzorci krečnjaka koji su korišćeni u radu imaju visok sadržaj Mg, Na i K. Rendgenska analiza je pokazala da uzorci uglavnom sadrže kalcit i u manjoj količini dolomit. Na početku je ispitan uticaj temperature, vremena i granulometrijskog sastava na kalcinaciju kalcijum-karbonata. Vreme trajanja procesa disocijacije je 10-15 min na 1200 °C i povećava se sa smanjenjem veličine čestica do 5 mm. Nakon toga, ispitana je aluminotermijska redukcija kalcijum-oksida. Na temperaturi od 1200 °C i vakuumu od 3 KPa proces redukcije se završava za 2 h. Analiza hemijskog sastava kalcijum-oksida i kalcijuma pokazuje povećan sadržaj magnezijum-oksida i oksida alkalnih metala, posebno natrijuma., We present experimental investigations that define both the technological scheme of calcium production from limestone by aluminothermic process and the basic operating parameters of the particular technological phases. The limestone with high content of Mg, Na and K was used in the study. X-ray analysis reveals that the samples contain mainly calcite with small amount of dolomite. At first, the effects of temperature, time and granulometry on the calcium carbonate calcination were examined. The dissociation process was completed in 10-15 min at 1200 °C, and the dissociation rate increased with decreasing particle size down to 5 mm. Afterwards, the aluminothermic reduction process of calcium oxide was investigated. At a temperature of 1200 °C and vacuum of at least 3 kPa, the reduction process completed within 2 h. The chemical composition of calcium oxide and calcium showed increased content of magnesium oxide and alkaline oxides (especially sodium).

This work presents a way to obtain the better quality of EN AW 7075 aluminum high-strength alloy by application of electromagnetic field (EMF) during the casting process. In this way, the uniform fine-grained microstructure, and hence the better mechanical properties of the alloy can be achieved. The microstructure and mechanical characterization for samples obtained with and without EMF were performed. The application of numerical simulation for hot forging process, using appropriate software, is efficient and highly useful tool for problem prediction in industrial production, reducing the time and costs in the process of development of new products. The input data of high strength Al-alloy EN AW-7075 is used for simulation because it enables the development of parts with complex dimensions and shape.

U radu je prikazana mogućnost dobijanja homogenije mikrostrukture i ravnomernije raspodele legirajućih elemenata Zn i Mg u aluminijumskoj leguri EN AW 7075, prilikom livenja u prisustvu elektromagnetnog polja. Ispitana su i mehanička svojstva uzoraka koji su odliveni bez i sa elektromagnetnin poljem. Rezultati pokazuju da se livenjem u elektromagnetnom polju postižu prednosti u odnosu na klasičan postupak livenja aluminijumskih legura., The microstructure and the mechanical properties of the samples obtained by conventional vertical continuous casting and electromagnetic casting of 7075 aluminum as-cast alloy were investigated. The better surface quality, more homogeneous alloying elements distribution and hence the microstructure and better mechanical properties were obtained in samples casted with electromagnetic field (EMF) compared with samples casted without EMF. The microstructure was analyzed by optical microscope and the variation of alloying elements, Zn and Mg, through the sample cross section was examined by chemical analysis. The mechanical properties of samples casted with and without electromagnetic field were determined using computerized materials testing machine Zwick/Roel Z 100.

The processes that take place at the liquid metal-sand mold interface during the casting and crystallization of metal were studied in this paper. The mold was made using the CO2 - Method, with the addition of active components, such as: MgO, TiO2, AIK(SO4)(2) and Na2SO4. At the liquid steel pouring temperature, these active components undergo decomposition in the mold, caused by heat release during pouring, Crystallization and cooling of castings. Silicates, which have an important influence on casting surface quality, are formed as a result of the interaction between the mould material and liquid steel.

The technological procedures for copper secondary raw materials processing include two basic stages: pretreatment of the copper waste and its further metallurgical processing. For copper waste pretreatment technology, there are different applied procedures depending on the type of raw material. Scrap of copper cables and wires preparation includes cutting, crushing, air separation and sieving; with the aim of separating the copper from the electrical insulation. The brass slag is grinded, followed by separation metal from oxide components. Chips preparation includes sorting, sieving, degreasing, magnetic separation, and briquetting. The process of electronic scrap preparing is more complex and consists of crushing, sorting, magnetic separation, calcination, combustion, shredding, and sampling. All operations of pretreatment are influencing the quality of metallurgical processing., Tehnološki postupci prerade sekundarnih sirovina bakra uključuju dva osnovna stupnja: pripremu bakarnih otpadaka i njihovu dalju metaluršku preradu. Za pripremu bakarnih otpadaka koriste se različiti postupci u zavisnosti od vrste i kvaliteta sekundarne sirovine. Priprema bakarnih provodnika obuhvata rezanje, drobljenje, vazdušnu separaciju i prosejavanje sa ciljem odvajanja bakra od izolacije. Masingana šljaka se melje, a potom odvaja metalna od oksidne faze. Pripreme strugotine uključuje sortiranje, prosejavanje, odmašćivanje, magnetnu separaciju i briketiranje. Proces pripreme elektronskog otpada je složeniji i sastoji se od drobljenja, soriranja, magnetne separacije, kalcinacije, sagorevanja, usitnjavanja i uzorkovanja. Sve operacije pripreme utiču na kvalitet metalurške prerade, odnosno na kvalitet proizvoda.

Hidroksiapatitna (HAp) prevlaka je atmosferskim (APS) plazma-sprej postupkom naneta na metalne uzorke napravljene od 316LVM čelika, namenjenog za izradu implantata u ortopedskoj hirurgiji. Razvoj savremenih ortopedskih implantata podrazumeva da se na podlogu od bioinertnih legura nanosi bioaktivna HAp prevlaka. Sintetički HAp je hemijski sličan onom koji čini mineralnu građu kostiju i zuba. Zahvaljujući dobrim bioaktivnim svojstvima hidroksiapatitnih prevlaka moguće je obrazovanje stabilne veze između koštanog tkiva i implantata. U radu je prikazana mogućnost primene APS postupka za dobijanje stabilnih HAp prevlaka na uzorcima od nerđajućeg čelika 316LVM. Praćena je mikrostruktura i poroznost prevlake metodom optičke mikroskopije i skenirajuće elektronske mikroskopije. Ca/P odnos je određen EDS analizom., For decades, the standard metallic materials for hip implants, besides the 316LVM stainless steel, were titanium- and cobalt/chromium-based alloys. Although bioinert, due to their corrosion resistance, they are not biocompatible. Contemporary surgical implants are no longer made solely from bioinert metals anymore, but with deposited bioactive hydroxyapatite (HAp) coatings. Hydroxyapatite is chemically identical with the mineral constituent of bones and teeth, which, besides its biocompatibility, provides bioactivity as well. The HAp limitations are, however, weak tensile strength and low fatigue resistance for long term loadings, if used alone. This is the reason for HAp to be deposited onto the surgical implant, and to enable its bioactivity, which means intergrowth with bones, and therefore the long-lasting and mechanical stable non-cemented prosthesis. This is important predominantly because of the need for such prostheses for younger population and a better life quality. There are several contemporary techniques that have been used for deposition of these coatings onto the metal implant. The possibilities of atmospheric plasma-spraying for obtaining stable HAp coatings on 316LVM stainless steel, ordinarily used as a standard material for hip implants production, are presented in this paper. The coatings of a commercially available hydroxyapatite powder were plasma-sprayed onto specimens of medical grade 316LVM stainless steel under various operating conditions. Optical microscopy was used for microstructure and porosity characterization, while the coating morphology and Ca/P ratio were analyzed using an SEM equipped with EDX. The coating microstructure varied from a porous to a glassy structure, depending on the operating conditions and coating thickness. Coating porosity was determined to be at the lower required limit requested for the bone-coating intergrowth possibility, but nevertheless adhesion measurements showed good results. The Ca/P ratio was determin

U radu su prikazani osnovi elektromagnetnog postupka livenja aluminijumske legure EN AW 7075 kao i rezultati mehaničke karakterizacije otkovka od ove legure koja je dobijena livenjem klasičnim polukontinualnim postupkom livenja i livenjem pod dejstvom elektromagnetnog polja sa dve različite frekvence. Rezultati pokazuju da uzorci otkovaka dobijeni od legure koja je livena u elektromagnetnom polju imaju zadovoljavajuće vrednosti mehaničkih svojstava i da se pravilnim izborom radnih parametara livenja mogu stvoriti uslovi za skraćenje tehnološkog postupka prerade ove legure., The electromagnetic casting process fundamentals of EN AW 7075 Al-alloy casting, as well as the mechanical characterization results of this alloy forgings are presented in this paper. Forgings are obtained from the alloy casted by classical semi-continuous casting process and by electromagnetic casting process using two different frequencies. Results reveal that forgings obtained from the alloy casted by electromagnetic casting process have adequate values of mechanical properties and that proper choice of operating parameters can lead to shortening of this alloy processing.

At the contact surface between the liquid metal and the mold wall a number of chemical and thermodynamical reactions were taken. The products of those reactions are spread out on both the sides, i.e., in the solidified metal or into the mold wall. The processes which took place in the casting mold-here made from sand mix, during the pouring of liquid metal, solidification and cooling down to room temperature, are pretty complex. The thermodynamic reactions at the contact surface of liquid metal/sand mold in the process of castings forming are discussed in this paper. Experiments were performed in molds made by CO2 sand casting process. As a pouring metal we used steels from an ordinary production program of a steel foundry, exactly it was the steel GS 50CrMo4, assigned by DIN. Some results obtained in our investigations during studying those processes are shown here.

Tehnološki postupci prerade sekundarnih sirovina bakra uključuju dva osnovna stupnja: pripremu bakarnih otpadaka i njihovu dalju metaluršku preradu. Za pripremu bakarnih otpadaka koriste se različiti postupci u zavisnosti od vrste i kvaliteta sekundarne sirovine. Priprema bakarnih provodnika obuhvata rezanje, drobljenje, vazdušnu separaciju i prosejavanje sa ciljem odvajanja bakra od izolacije. Masingana šljaka se melje, a potom odvaja metalna od oksidne faze. Pripreme strugotine uključuje sortiranje, prosejavanje, odmašćivanje, magnetnu separaciju i briketiranje. Proces pripreme elektronskog otpada je složeniji i sastoji se od drobljenja, soriranja, magnetne separacije, kalcinacije, sagorevanja, usitnjavanja i uzorkovanja. Sve operacije pripreme utiču na kvalitet metalurške prerade, odnosno na kvalitet proizvoda., The technological procedures for copper secondary raw materials processing include two basic stages: pretreatment of the copper waste and its further metallurgical processing. For copper waste pretreatment technology, there are different applied procedures depending on the type of raw material. Scrap of copper cables and wires preparation includes cutting, crushing, air separation and sieving; with the aim of separating the copper from the electrical insulation. The brass slag is grinded, followed by separation metal from oxide components. Chips preparation includes sorting, sieving, degreasing, magnetic separation, and briquetting. The process of electronic scrap preparing is more complex and consists of crushing, sorting, magnetic separation, calcination, combustion, shredding, and sampling. All operations of pretreatment are influencing the quality of metallurgical processing.

Od vrste i kvaliteta kalupne mešavine odnosno njenog ponašanja u dodiru sa stopljenim metalom u realnim uslovima najviše zavise intenzitet, i uopšte razvoj, pojedinih procesa na graničnoj površini dodira metal-kalup. Značajno mesto u odigravanju procesa međusobnog delovanja livačkih kalupa i tečnog metala pored hemijskog, mineralnog sastava peska, vrste vezivnog sredstva imaju i dodaci kalupnim mešavinama. Ovi dodaci, tj aktivne komponente, uslovljavaju određene promene na povišenim temperaturama u samoj mešavini kao i njeno reagovanje sa površinskim slojem tečnog metala. Cilj ispitivanja je bio da se vidi u kolikoj meri sastav kalupne mešavine sa i bez dodatih-aktivnih komponenata utiče na površinu odlivaka., The intensity, and overall development of individual process on the metal-mould interface depend on the type and quality of mould mixture or its behavior in contact with the melted metal in real conditions. Important role in interaction between foundry moulds and liquid metals, in addition to chemical and mineral composition of sand, and a type of binding material, play also additives for mould mixtures. These additives, i.e. active components, provided some changes at elevated temperatures inside the mixture, as well as its reaction with the surface layer of liquid metal. The aim of this investigation was to determine how the composition of the mould mixture with and without active components affect the surface of castings.

During the casting of metals at the interface between metal and mould, or contact surface metal-mould, some chemical reactions occur. Reaction products penetrate or move toward the mould as well as toward the castings. In this work the chemistry at the contact surface between the metal and mould was studied. The objective of the work was better understanding of the chemical reactions that occur, at the interfaces, during the casting processes. All experiments were performed, both, on a laboratory and industrial scale, using the steel samples DIN G-X 120Mn 12, the steel samples came from the steel casting industrial plant production list. The moulds were made using the CO2 procedure. Some active components were added to the mould mixture. During the casting process, while liquid metal enter into the mould vacancy, a kind of intensive reaction of liquid metal with quartz sand and added active components occur thus forming a new chemical compounds. These Compounds have an important influence on the steel castings quality, and consequently on the production economy.