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The possibilities for application of numerical simulation in the ironing process of thin sheets
No full textIn this research, results of experimental investigations and physical model were used as the input variables for numerical analysis of the ironing strip drawing process by application of lubricants. The numerical simulation was realized in the specialized applicative software Simufact.forming. By applying the software for the 3D modeling, a model of the tool element assembly was made, which served as the starting basis for numerical simulation by application of the Finite Element Method. Experimental values of the friction coefficient for each type of lubricants and the contact pressures were used for defining the contact conditions. Numerical simulation of the drawing process was done for each type of the contact conditions between the tool's elements and the thin sheet sample. After conducted tests comparison of experimental and numerical results of the drawing forces in different contact conditions was done. Comparison was done with taking into account appearance of galling due to difficult drawing process conditions. By comparation of numerical results to the experimental one it is possible to interpret what types of simplifications were adopted in creating the experimental physical-tribological model
Effects of different mechanical treatments on structural changes of lignocellulosic waste biomass and subsequent Cu(II) removal kinetics
No full textIn this paper, the character of structural changes induced by different mechanical treatments to Prunus persica stones (PSs), and its subsequent effect on biosorption kinetics of Cu(II) were investigated. PSs were processed in vibratory disk mill (PS-V) and ultra-centrifugal mill (PS-C) and characterized by XRD, BET, SEM and FTIR spectroscopy. It was shown that PS-V was smaller and more reactive with less crystallinity index and hydrogen bond intensity compared to PS-C. In opposite, surface area of the PS-C was bigger than that of the PS-V. The total pore volume was about threefold, while the volume of micro pores was 9.29 times higher in PS-Cs than in PS-Vs. The kinetics of Cu(II) biosorption by both PSs was tested through various kinetic models: pseudo-first and pseudo-second order rate equations, Elovich equation, Boyd model, Weber-Morris and Urano-Tachikawa intraparticle diffusion model. For both sample types, Cu(II) biosorption occurred through combination of intraparticle and film diffusion mechanism, while kinetic results were best described by the pseudo-second order kinetic model. At the same time, the results indicated that together with kinetic rate the biosorption capacity of PS-C (21.20 mg g(-1)) was higher than that of PS-V (16.30 mg g(-1)). Mechanical activation like crushing and grinding will change material particle size, specific surface area and porosity, as well as its crystallinity. However, this paper elucidates that such physical structural changes will impact on heavy metal ions removal efficiency. This investigation suggests that the type of size reduction in lignocellulosic biosorbent preparation plays a very important role in overall biosorption performance, so it should be carefully considered every time when the mechanical treatment of material is necessary to be applied
The process of obtaining quartz sand size fraction -0.4
No full textThe paper presents the process of quartz sand processing from the "Bijela Stijena" - Skocic deposit in the plant "Kesogradnja d.o.o." at Kozluk near Zvornik, Republic of Srpska. Bearing in mind the fact that this quartz sand is used for water glass production in the company "Birac" - Zvornik or "Alumina" Zvornik, it was necessary to meet the quality requirements prescribed by that industrial production. Thus, the required size was -0.4+0.05 mm and the Fe2O3 content was maximum of 0.04%. Based on the laboratory tests, a technological scheme for the quartz raw material valorization was conceived in the separation of the company "Kesogradnja d.o.o.". The obtained results showed that quartz sand for water glass size fraction -0.4+0.05 mm could be obtained in the plant. Also, by introducing a magnetic concentration after washing and grading, the Fe2O3 content was reduced from 0.131% as it is in the initial sample to 0.038% which meets the required conditions from the water glass producers
The Cerovo-cementacija 2 porphyry Cu deposit, Eastern Serbia - Ore mineralogy and paragenetic analysis
No full textThe Cerovo-Cementacija 2 porphyry Cu deposit, hosted by hydrothermally altered hornblende andesite,
located into the Bor Metallogenic Zone, eastern Serbia, has been investigated. In this porphyry Cu
deposit, the following mineral parageneses have been established: i) pyrite-chalcopyrite with Mo; ii)
quartz-pyrite with Au; iii) digenite-chalcocite-covellite with Au; iv) chalcedony by sulfatization and
sulphation; v) malachite-azurite-limonite. Chalcopyrite is the major Cu mineral and it is the most
abundant compared to other established Cu-sulfide minerals. By the ascending and descending
hydrothermal processes along the Zone-1 (cementation zone), chalcopyrite was commonly transformed
into secondary Cu sulfide minerals (digenite, chalcocite, anilite, covellite, etc.), while those appearances
is less represented to the Zone-2 (transitional zone)
Rietveld analysis of zeolitic tuff modified by acid treatment
No full textAcidic zeolites are widely used in the chemical and petroleum industry because of their catalytic activity, remarkable reaction selectivity, and excellent chemical and thermal stability.
In this paper, data on the structural properties of the acid treated natural zeolitic tuff are presented
Potential ways to lower CO2 emission for cement production
No full textRapid technological development leads to an improvement in the quality of life in all spheres of human activity, but at the same time it creates environmental degradation. Therefore, it is important to analyze the negative impact of technological processes, in order to adopt the strategy and define activities for implementation adequate environmental protection rates. One of the major problems in environmental protection is the emergence of greenhouse gas emissions. The world's organizations dealing with environmental protection provide a great stimulus for the development of innovative sustainable solutions in the construction industry. Thus, one of the priorities in cement industry is finding new ways to reduce energy consumption and CO2 emissions with point on clinker production plants as the biggest CO2 emitter (the product of the baking process during the portland cement process). In such a way new solutions reduce the amount of clinker, while at the same time, they encourage the use of alternative materials. Materials that can replace the use of cement (supplementary cementitious materials - SCM) as well as mixtures of cement, offer advantages in better characteristics, lower energy consumption and emissions of gases that produce greenhouse effect
Elektroforetsko taloženje antibakterijske kompozitne prevlake hidroksiapatita sa hitozanom, grafenom i gentamicinom
No full textU ovom radu su ispitivane kompozitne prevlake koje se sastoje od hidroksiapatita (HAP), hitozana (CS) i grafena (Gr), sa i bez gentamicina (Gent) dobijene postupkom elektroforetskog taloženja (EPD). Taloženje je izvedeno u jednom koraku iz četvorokomponentne vodene suspenzije (HAP/CS/Gr/Gent) pri konstantnom naponu na titanskim (Ti) pločicama. Uticaj Gr i Gent je detaljno istražen primenom različitih fizičko-hemijskih i bioloških analiza. Karakteristike dobijenih HAP/CS/Gr i HAP/CS/Gr/Gent prevlaka ispitivane su infracrvenom spektroskopijom sa Furijeovom transformacijom (FT-IR), skenirajućom elektronskom mikroskopijom (FE-SEM), rendgenskom fotoelektronskom spektroskopijom (XPS) i rendgenskom difrakcionom analizom (XRD). Ispitivanja antibakterijske aktivnosti prema Escherichia coli i Staphylococcus aureus izvršena su metodom agar difuzije i testa u suspenziji, a citotoksičnost MTT testom na ćelijskim linijama MRC-5 i L929. Dobijeni rezultati ukazali su na veliki potencijal elektroforetski istaloženih kompozita za medicinske primene.In this work composite coatings consisting of hydroxyapatite (HAP), chitosan (CS) and graphene (Gr), with and without gentamicin (Gent) produced by electrophoretic deposition process (EPD) were investigated. Deposition was performed in a single step from the four-component aqueous suspension (HAP/CS/Gr/Gent) at a constant voltage on titanium (Ti) plates. The influence of Gr and Gent has been thoroughly explored using various physico-chemical and biological analyses. The characteristics of the obtained HAP/CS/Gr and HAP/CS/Gr/Gent coatings were investigated using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron analysis (XPS) and X-ray diffraction (XRD) techniques. Antibacterial efficacy assays against Escherichia coli and Staphylococcus aureus were performed by agar diffusion method and in suspension testing, while cytotoxicity was elucidated using MTT test toward MRC-5 and L929 cell lines. Obtained results pointed out high potential of electrodeposited composites for medical applications
Glass-ceramics obtained from copper mine tailings and glass cullets
No full textCopper mine tailings is one of the most used secondary raw materials. The most common use is in cement industry and as filler in road construction. The area of secondary raw materials utilization offering the greatest potential is in the development of glass-ceramic compositions, where the waste is melted to form a glass, fabricated using conventional glass forming techniques, and subsequently nucleated and devitrified in a controlled manner through heat treatment. The resultant, partially crystallized material offers improved strength, chemical and abrasion resistance. Copper mine tailings was mixed with 30% glass cullets and melted in electric furnace BLF 17/3 at T=1450 °C during t=0.5 h. The obtained glass sample was black, without visible residual gas bubbles. X-ray powder diffraction (XRD) analysis confirmed the quenched melt to be amorphous. DTA and HSM analysis was performed on the previously prepared glass powder. The glass powder samples were pressed in pellets and sintered in an electric furnace at the temperature of 1040 °C for 2h and a glass- ceramics was obtained. Applications for these glass-ceramic materials would include structural products, pipe or pipeliners to transport abrasive or corrosive fluids, alkali-resistant fibers to replace asbestos in concrete products, and use as a matrix material in which radioactive wastes could be chemically incorporated in a stable, nonleachable, solid form
Biosorption of copper by immobilized Myriophyllum spicatum
No full textBiosorption removes pollutants such as heavy metals onto a natural adsorbent, so it can be considered as a promising method of water purification. The objectives of this research were to examine the application of aquatic weed Myriophyllum spicatum immobilized in alginate beads – MsA for the removal of copper from aqueous solutions. Appield biosorbent was characterized by Fourier transform infrared spectroscopy (FT-IR). Experimental results were fitted by six isotherm models, and have showed that MsA holds great potential for copper removal, q = 1.307 mmol/ Results of TOC analyses showed that after Myriophyllum spicatum immobilization process , total organic carbon in MsA was more than four times less than with aquatic weed M. spicatum, 18.8 mg/L compared to 81.2 mg/L of TOC