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Mostly used food packing are: paper, cartoon, plastics, glass, metals and multilayer materials. The plastics and paper/cartoon make about 70% of all food packing. These two have the biggest migration potential. The use of plastics is regulated by specific EU rules, but it is not yet the same about the use of paper packing. In order to ensure health assurance for the consumers, it is needed often to make an evaluation of the migration of the contaminants from paper/cartoon packing, especially in case of recycled papers, because of the fact that a recycled paper could contain many different contaminants, what is not the case regarding the originally produced paper. Migrating contaminants could originate from basic paper packing, but also from the components added in phase of forming, as well as from graphic finalisation trough the glue, paints, lacking etc. In this article is presented an overview of the typical contaminants from paper/cartoon packing, as well as their toxicological profile. [ABSTRACT FROM AUTHOR]

The process of the pulp washing is very important both economically and environmentally, since the quality of cellulose washing is directly related to the efficiency of chemical regeneration and the quality of the wastewater generated. The purpose of the cellulose fiber washing process is to economically remove the maximum of soluble organic and soluble inorganic substances with a minimum of fresh and recycled water. The filtrate formed during the washing of the pulp contains the lost chemicals during the cooking process and is sent to the regeneration system where the necessary active alkalis are extracted for cooking the pulp and the residual organic matter is burned in an alkaline boiler to obtain the energy required. Poorly washed pulp will carry with it a considerable amount of active alkali, which will end up in the wastewater after the process of thickening the cellulose mass and separating the filtrate. The aim of this paper was to examine the influence of process parameters on the pulp washing quality and determine the quality of the pulp washing in the cellulose and paper factory, Natron Hayat, Maglaj. [ABSTRACT FROM AUTHOR]

In industries such as the chemical industry, the oil industry, the steel industry, and the pulp and paper industry, energy systems are the basis of the production process and represent key indicators of the profitability of the process. Energy efficiency in industry is long-term related to technological development and the dynamics of renewal of production capacities. Increasing energy efficiency in the industry leads to a reduction in energy consumption but also reduces the negative impact on the environment. The rise in energy prices, both electricity and other energy sources, and the development of fees for emissions into the environment will mean important economic incentives in efforts to reduce energy consumption and emissions, thus increasing efficiency and the use of renewable sources in the industry. The paper presents several measures that achieve fuel, energy, and air savings in Natron-Hayat Maglaj. [ABSTRACT FROM AUTHOR]

Basic raw materials for paper production are cellulose fibers and water. Water plays a major role in the process of cellulose and paper production and it is present in almost all phases of the cellulose fiber production process. Because of that the cellulose and paper industry is considered to be one of the largest consumers of natural resource polluters. In the paper are analyzed the following quality parameters of wastewater generated in cellulose and paper factory and discharged into a surface water recipient: temperature, pH value, electroconductivity, chemical oxygen demand (COD), biological oxygen demand (BOD5), the share of biodegradable matter in total content of organic matter (BOD5/COD) and the content of dissolved oxygen (DO). The aim of the study was to determine whether the values of the mentioned parameters are within the legally permitted limits and then to determine whether wastewater from the cellulose and paper industry influence a surface water recipient, or a living world in it. Analyzed wastewater samples were taken in the cellulose and paper factory "Natron Hayat", Maglaj. Wastewater from the cellulose and paper factory "Natron Hayat", Maglaj is discharged into the surface water recipient, the river Bosna. [ABSTRACT FROM AUTHOR]

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Some specific aspects of metallurgy consulting in the industrial transition of Bosnia and Herzegovina are presented in this paper. The theoretical part of the paper is mostly concerned with a short overview of ZELJEZARA ZENICA cum ARCELORMITTAL-ZENICA (AMZ) product-mix and the facilities transition, as an example of the a.m. transition, although these parameters are realistic in the practice. In the practical part, some judicial cases-pictures related to the plastic deformation of the structures-facilities are presented, along with general proposals-solutions how to overcome the problems related to an occurrence of plastic deformation of the a.m. structuresfacilities, through proper mechanical maintenance, management, and consulting with renown institutions. The figures supplied in the practical part express the significant extent of the plastic deformations and are taken from the court expert judicial cases in different B&H companies. It may be an incentive for the technical faculties and institutes in B&H to visit metal sector production plants and offer their consulting services, in order to prevent the (dangerous) occurrence of plastic deformation of the structures-facilities, which can lead to worker injuries, structure-machinery breaks and to the un-planed stopping of normal production. [ABSTRACT FROM AUTHOR]

Occupational safety is a very important factor in the process of creating a safe work environment. The benefits employers, employees and even the state as a whole can reap greatly depend on the way occupational safety is organized and implemented. This paper aims to make a general analysis of the condition of safety at work in Bosnia and Herzegovina, with a special emphasis on the Federation of Bosnia and Herzegovina. The starting point of this paper is the fact that the current law on occupational safety was passed less than two years ago and certain doubts are sprouting up regarding its implementation. This is why there is a need for a deeper and more comprehensive analysis of existing legal situations, problems in implementation, and proposals that could improve or otherwise prove helpful in gaining a clearer understanding of the rights, obligations, and responsibilities of all parties involved, those being the state, employers, and employees. The initial hypothesis of the paper is that the current law on occupational safety, with all its vagueness, represents a good basis for improving the position and rights of employees. The descriptive method was used in the paper, along with a study of available literature, both domestic and foreign. [ABSTRACT FROM AUTHOR]

Wood is renewable, recyclable, climate-friendly material, and presents an important segment in achieving circular economy and sustainability concepts. To be able to link these two concepts, production and consumption systems need to transform towards sustainability. Wood-based products play a role in mitigating climate change by reducing carbon from the atmosphere. Their special properties, such as carbon storage capacity, high recyclability, renewal of raw materials, and a direct impact on the reduction of greenhouse gases in the atmosphere, make them the best product to combat climate change. This paper aims to present the role of the wood-based industry and its products in achieving sustainable development goals. [ABSTRACT FROM AUTHOR]

The paper describes the research methodology of the heat generated by the biological decomposition of a mixture of sludge from WTP (wastewater treatment plant) and biowaste and its use outside the system for a controlled biodegradation process. Earlier research in this area defined the optimal mixtures of sludge and biowaste that ensure quality management of the biological decomposition process. The research described in this paper aims to prove that the heat generated in the process of a biological enclosure can be taken outside the biodegradation system and used without violating the assumptions of optimal management of the process. [ABSTRACT FROM AUTHOR]

The paper presents data on emissions of analyzed pollutants into the air (SO2, NOx, CO, VOC, NH3, PM10, PM2.5, PAH, Pb, Cd, and Hg) by sector (industry and energy, small combustion plants, road traffic and services-agriculture and animal husbandry), and by cities and municipalities in the area of the Zenica-Doboj Canton. Based on the analyzed data, it was determined that the air quality in the area of the Zenica-Doboj Canton is very endangered and does not satisfy the prescribed legal regulations, which can potentially affect people's health, ecosystems, economic prosperity, and development. According to the results of the research, it was determined that the main causes of excessive air pollution are the production of emissions from industrial and energy plants, local boiler houses and home fireplaces, road traffic, and the service sector (agriculture, processing industry, construction, trade), as well as unfavorable climatic conditions, with the presence of inadequate topographical conditions and other influencing factors. [ABSTRACT FROM AUTHOR]

Pyrophyllite (Al2Si4O10(OH)2) is a layered phyllosilicate mineral with a basic 2:1 crystal structure, consisting of an aluminum octahedral layer placed between two silicon tetrahedral layers (T-O-T), connected by weak Van der Waals forces, which results in easy structural disruption. Natural pyrophyllite has an electroneutral surface, which causes a hydrophobic character. Due to its unique properties, such as low thermal and electrical conductivity, high refractive behavior, low coefficient of expansion, rheological properties, low bulk density, low deformation under high temperature, and chemical inertness, pyrophyllite is widely used in various industrial branches: refractory, ceramic, construction, pharmaceutical and cosmetic industry, production of pesticides, fertilizers, paper, paints, plastics, tires. Thanks to its unique properties, pyrophyllite shale from the Parasovići deposit, Konjic, Bosnia and Herzegovina, has shown the possibility of being used in many areas of life. This paper presents the results of research so far, which confirmed the wide application of natural, modified, and enriched pyrophyllite in various industrial branches, agriculture, and environmental protection. [ABSTRACT FROM AUTHOR]

We have introduced a theory for the calculation of thermodynamic characteristics for some characteristic nanostructures (ultrathin films and superlattices), using the adapted method of twotime temperature Green's functions. In this paper, we have determined the coefficient of thermal conductivity using the definition of free energy and then compared their temperature dependence to the thermal conductivity behavior of the bulk structures. For the observed nanostructures, the thermal conductivity coefficient values are almost equal at low temperatures, but at the same time, significantly lower than the bulk sample values. That result could be useful for the possible achievement of better superconducting conditions in the observed compound nanostructures. [ABSTRACT FROM AUTHOR]

This paper examines the possibility of producing metallurgical cement type CEM III/A 42.5N at the Kakanj Cement Factory. The tested samples contain respectively 46%, 41%, and 38% of granulated blast furnace slag and the rest is clinker. According to the test results, all cement samples meet the EN 197-1 standard in terms of physical-mechanical properties both after the initial period (2 days) and after the final period (28 days). As a result of the conducted tests, it can be concluded that the production of metallurgical cement type CEM III/A 42.5N at the Kakanj cement factory is possible and that its production would provide a number of ecological and economic benefits. [ABSTRACT FROM AUTHOR]

In this paper, C45 medium carbon tool steel was investigated after various heat treatments. The thermal properties, specifically thermal diffusivity and thermal conductivity, were measured and also the microstructure analysis was done on a light microscope. Heat treatment of the samples included: 1) the normalization heat treatment at 900°C for one hour and cooling in the air; 2) quenching the samples in water and in oil separately after reheating them at 880°C for one hour and; 3) tempering the quenched samples at 200°C-350°C for 2 hours. The results show the highest values of thermal properties for the normalized sample. Also, the lowest values were recorded for the quenched samples, and the values of thermal properties for the tempered samples are between the values of the quenched and normalized samples. Microstructure analysis shows a typical ferrite-pearlite structure after normalization. Martensite appeared in the water-quenched sample. However, the microstructure of the oil-hardened sample predominately consists of ferrite and pearlite because the critical cooling rate was not reached. Tempered samples quenched in the water had the microstructure of tempered martensite. [ABSTRACT FROM AUTHOR]

The particle shape and size of the starting powders represent the most important physical properties, on which the quality of the compacts and final sintered products depends. Two types of powder were analyzed in the paper - electrolytic copper powder with a dendritic particle shape and water-atomized copper powder with an irregular particle shape. The starting powders were sieved through a sieve system with openings of 45 µm, 80 µm, and 120 µm. The characterization of the obtained fractions of both powders was performed by determining the shape and dimensions of the particles using SEM microscopy in combination with ImageJ software, and the apparent density and flow rate were determined using the Hall flowmeter funnel. Pressing of each powder fraction was done using a pressure of 600 MPa. The compacts were further sintered at 1000°C for 2 hours to obtain the final sintered parts. After sintering, their density, hardness, and electrical conductivity were determined and their microstructure was analyzed. The results indicate a great influence of the characteristics of the starting powders on the properties of the final parts obtained by the powder metallurgy route. The particle shape of the powders had a more pronounced influence compared to the particle size. [ABSTRACT FROM AUTHOR]

We are currently witnessing the beginning of the global food crisis and disturbances in the fertilizer market. On the other hand, on July 16, 2022, Regulation (EU) 2019/1009 of the European Parliament and of the Council for laying down rules on the placing on the market of EU fertilizer products establishes strict rules on the safety and quality of fertilizers and repealing Regulation (EC) 2003/2003. The paper presents the modeling of process parameters of multifunctional fertilizer, as a compound inorganic macronutrient fertilizer/liming material/soil improver, based on pyrophyllite shale (pyrophyllite), deposits Parsovići, Konjic, BiH, enriched with dolomite, BiH to achieve the formulation of Product Function Categories (PFC) in terms of the content of secondary macronutrients (CaO and MgO) accordance with Regulation (EU) 2019/1009. The biological efficiency of the newly formulated fertilizer was tested through vegetation trials with beets (Beta vulgaris var. Conditiva). [ABSTRACT FROM AUTHOR]

This paper presents an experimental study to evaluate the possibility of CEM IV 42,5N producing by increasing the specific cement surface from 3180 to 3850 cm²/g. In this paper, fly ash is used as a cement admixture because fly ash possesses both hydraulic and pozzolanic properties. If one part of the clinker, as a major cement admixture, is replaced with a certain amount of fly ash, the preexisting deposit of fly ash is reduced, which can eventually give cheaper cement. Also, using more fly ash would reduce the emmision of CO2 into the atmosphere. Of course, in order to produce such pozzolanic cement, the requirements of EN 197-1 must be satisfied. Test results show that by increasing the specific surface of cement, the compressive strength of cement which meets the requirements for 42.5N class cement is also increased. [ABSTRACT FROM AUTHOR]

RDF (Refuse derived fuels) is an alternative fuel that has recently been used in the cement industry as a rotary kiln fuel. Generally, RDF is a mixture of different materials which have a certain energy value such as paper, textiles, rubber, plastics, household waste, etc. The quality of RDF varies depending on the source from whichmentionedalternative fuel is obtained. Exactly the quality of RDF has an extremely large impact on the reactivity of cement clinker, which again ultimately has an impact on the quality of the final product, ie cement. In this regard, the use of RDF as an alternative fuel must be treated with extreme caution because the variations in the RDF quality will affectonthe quality of the cement clinker. When it comes to the quality of RDF, we primarily refer to the calorific value of the RDF, however beside mentioned parametershould also pay attention to other parameters such as chlorine, sulfur, mercury, moisture, ash, etc., which also have a crucial effect on the reactivity of the clinker. This paper presents the results of a clinker/cement quality examinationin the case of using of RDF and for the case where RDF was not used. [ABSTRACT FROM AUTHOR]

Some specific aspects in the improvement processes related to I-beams production, especially related to the conversion of classical to the universal rolling mills stands are presented in this paper. One of practical solutions in the a.m. conversion is described in some more details, as well as some of better designs in the variety of I-beams, concerned with parallel flanged ones. So called INP I-beams have tapered flanges v.s. parallel flanges concerned with parallel flanged I-beams, which are very difficult to be produced on classical rolling mills stands, but much easier and better to be produced on so called universal rolling stands. Since the universal stands are expensive and is very difficult to fix (incorporate) them at the existing rolling mills with classical rolling stands, then a conversion of classical to the universal rolling mills stands is the cheapest satisfactory solution. One of the a.m. solutions is presented in this paper as well. [ABSTRACT FROM AUTHOR]

Hydrocracked base oil raw material (BORM) is the basis for the production of hydrocracked base oils (HC-base oils) in the company „Modriča Oil Refinery", which is engaged in the production of HC-base oils, various motor and industrial lubricating oils, and lubricating greases. The production of the mentioned HC-base oils consists of four production units, the first of which (hydrocracking) is located in Bosanski Brod, and the other three (vacuum distillation, deparaffinization, and final processing - bleaching) are located within the Modrič Oil Refinery. The aim of this work was to analyze the influence of different physicochemical characteristics of BORM, which undergoes certain production processes, on the quality of its distillates. Distillation curves are also presented in the paper, based on which the temperature regime of the vacuum column is monitored and set, and different yields of fractions can be obtained. The obtained results for all tested parameters of the obtained fractions using two different base oil raw materials are within the limits prescribed by the internal standard. [ABSTRACT FROM AUTHOR]

Considering the toxic properties of heavy metals and their effects on the environment, there is an increasing interest in studying their interactions with different ligands and searching for possibilities to remove those ions from the environment. Compared to other ligands, crown ethers possess the highest selectivity as ligands for metal cations, due to their "macrocyclic effect". In this paper, interactions between Pb(II), Cd(II) ions and various crown ethers (18 crown-6, benzo-18-crown-6, dibenzo-18-crown-6, dicyclohexane-18-crown-6 ether), were analyzed. The UV/VIS spectrometric method was used to record absorption diagrams of "model systems" of varying complexity. Cd(II) and Pb(II) ions were monitored using flame atomic absorption spectrometry. In different organic solvents used (chloroform, dichloromethane), UV/VIS and FAAS measurements showed that higher absorption intensity caused more stable complexes in the membrane, complicating the release of ions. With the benzo-18-crown-6 ether as ligand, Pb(II) ions released into the aqueous phase at a rate higher than 60%, compared with Cd(II) ions released at a rate of 49%. In a model system containing a nonionic surfactant (TX-100), metal ions interact more intensely with the membrane, and cation release is reduced in the aqueous phase, indicating that the reverse micellar aggregates incorporate metal ions that result in higher absorption intensities. According to the macrocycle selected, the presence of benzo- and cyclohexyl groups (B18C6, DB18C6, DCH18C6) probably reduces interactions between substituted macrocyclic ligands and metal cations, resulting in lower values of Pb(II) and Cd(II) ions measured in the aqueous phase compared with a model system with 18 crown-6 ether. [ABSTRACT FROM AUTHOR]

In this paper, an analysis of the surface water and sediment of the Drina River was carried out. Samples were taken from different six locations along the course of the Drina River in Bosnia and Herzegovina. Selected heavy metals were determined in the sediment after acid digestion using atomic absorption spectrometry - flame technique. The same method was used to determine Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn in surface water samples. The obtained results indicate that the Drina River in the investigated part of the course meets most of the prescribed metal limit values. The results obtained for the river Drina were compared with the results obtained in the studies of the rivers Bosna, Trstionica, and Spreča in Bosnia and Herzegovina. [ABSTRACT FROM AUTHOR]

Leachate water from sanitary landfills represents one of the most complex global environmental problems. This paper examines the possibility of using aluminosilicate material, pyrophyllite, from the Parsovići deposit, as an adsorbent. It was researched the influence of two granulations of pyrophyllite (0-53 µm and 0-100 µm) on the degree of adsorption of heavy metals (Fe, Ni, Mn) from leachate water from the municipal landfill "Desetine", Tuzla. The adsorption experiment was performed using the Batch method, depending on the contact time between the adsorbent and the adsorbate, the mixing speed, and the mass of the adsorbent, pyrophyllite, through two treatments. The results indicate a higher efficiency of the finer fraction of pyrophyllite, and in the competition of the three examined metals, iron is completely removed in the first treatment with both granulations and then nickel with finer granulation and manganese with coarser. After the first treatment, the unpleasant smell was removed, which is certainly a consequence of the removal of ammonia compounds as the most abundant compounds in leachate water. In these pioneering researches, pyrophyllite proved to be effective, and at the same time, it is a cheap, easily available, and environmentally friendly material for leachate water purification. [ABSTRACT FROM AUTHOR]

According to new EN 197-5 is possible to combine clinker with blast furnace slag, silica fume, pozzolana, fly ash, burnt shale, and limestone from 36 - 50% while clinker content should be from 50 - 64%. In this paper are presented results of laboratory testing concerning CEM II/C-M (S+W) production where a sample is prepared by mixing 50% of clinker, 23% of calcareous fly ash, 23% of granulated blast furnace slag, and 4 % of gypsum. The focus was on the physical and mechanical properties of laboratory-produced samples in terms of the specific surface, specific weight, setting time, and tensile/compressive strength. Besides the physical-mechanical properties, the main chemical parameters are also determined (SiO2, Al2O3, Fe2O3, CaO, MgO, SO3, Na2O, and K2O). The obtained results of CEM II/C-M (S+W) are compared with the results of cement CEM II/B-W 42,5N. [ABSTRACT FROM AUTHOR]

Metallic materials in granular packings show different electrical properties from their bulk counterparts. In this paper, we investigate the temporal evolution of the electrical conductivity of granular metals. We use metallic beads arranged in different one-, two- and three-dimensional ensembles through which different constant currents are injected. The conductivity behavior in all three types of systems is qualitatively similar. The results show the rise of conductivity which is more pronounced in the earlier stages of the time evolution. We investigate the influence of the dimensionality, the number of beads, and the values of the injected currents on the conductivity behavior. [ABSTRACT FROM AUTHOR]

In order to examine the state of critical components of the boiler of Unit 5 of Kakanj Thermal Prema wer Plant, headers were tested in order to undertake appropriate technological measures and activities on the basis of insight into the current state of affairs, and to make recommendations for further exploitation. From first commissioning in 1969 to 30 April 2019 the Unit 5 boiler had 271.403 operating hours in operation and was designed for 100.000 hours. During the exploitation so far, several modifications and revitalizations have been carried out on the block, although some components from the installation period are still in operation (superheater headers Pr 5 and Pr 6). The testing program was made on the basis of analysis and evaluation of the results from previous tests and records of performed repairs on the tested components (repair of individual cracks on welded joints, created during exploitation in the previous period). The paper presents the most important data on past exploitation, the results of the NDT tests, as well as the hardness and structure tests on the replicas. Material condition assessments of critical components of Pr 5 and Pr 6 superheaters, unit 5 boiler, and recommendations for further exploitation were made based on NDT tests, as well as hardness and structure tests, in accordance with prescribed, norms and applicable standards, and structural degradation assessment and the hardness drop from the commissioning of the block to the tests carried out in the course of this work on the same or similar components. [ABSTRACT FROM AUTHOR]

The paper describes the determination of the mechanical properties of the spherical floors of pressure vessels, obtained by the welding process and shaped by the process of gradual local deformation in the cold state, i.e. by the process of Incremental sheet forming (ISF). Spherical cylindrical bottoms are an integral part of most closed-pressure vessels. Cylindrical pressure vessel floors are made from one part, but the standards also allow for welded construction when the dimensions of the floors are larger than the standard dimensions of the sheet metal for production. Pressure vessel floors obtained by the welding process and shaped by the process of gradual local deformation in the cold state, i.e. by the process of incremental deformation, have a multiaxial initial stress state, which differs significantly from the initial stress state of the cylindrical part of the vessel. Checking the behavior of such floors before completing the vessel itself, i.e. before putting it into operation, is necessary, on the one hand, due to a large number of influencing factors, and on the other hand, due to the high cost of testing the real construction itself. The aim of the test is to determine the influence of the parameter: type of material, thickness, and diameter on the following quantities: mechanical properties, ReH, Rm, A5, and total energy used for impact, KV. [ABSTRACT FROM AUTHOR]

This paper describes the process of degradation of the structure of the inlet header of the intermediate reheater (MPr) 2 input header at the boiler of Unit 7 of the Thermal Power Plant Kakanj, determined on the basis of tests of replicas and hardness at characteristic places of the header. Headers, with minor delays, have been in continuous operation since 1988. Hardness was tested at replica pickup sites, on the basis of which the correlation between structure degradation and hardness drop resulting from exploitation during the long-term high-temperature operation was estimated. The change in hardness is certainly one of the most reliable indicators of the structure degradation degree, which is directly related to the service life of the installed components. The subject of the test was the inlet header of the intermediate heater made of low alloy steel 15Mo3, consisting of ferrite-pearlite microstructure, and having calculated values for the allowed hardness in the range from 133 to 176 HB. The structure degradation assessment was performed according to VGB-S-517 by comparing the microstructure of the replicates with the corresponding standards, and the hardness was tested according to ASTM A 956/1996-method A. The examination has shown that in the exploitation life achieved so far, there has been a partial or complete degradation of the structure, which is reflected in the initial and delayed coagulation of the perlite lamellae (Grades 2a and 3a). The hardness at the test sites is at or below the lower than the prescribed 133HB. The tests confirmed that there is a good correlation between the degree of degradation of the structure and the hardness, which can be used in assessing the condition and planning the extent of testing on critical components. [ABSTRACT FROM AUTHOR]

Steel S690 QL is a high-strength quenched and tempered, fine-grained structural steel with a minimum yield strength of ReH of 690 MPa and with guaranteed toughness (Charpy) for rolled plates with a thickness of 3 to 50 mm. This paper presents the examination and analysis of the microstructure and grain size results after quenching and tempering. Also, the aim of the examination is to consider the segments of the technological process and its influence on the physical and metallurgical characteristics, primarily on the microstructure and grain size, which affect the tensile characteristics and toughness at low temperatures. [ABSTRACT FROM AUTHOR]

Gray cast iron belongs to the group of iron casts that contain graphite particles in the microstructure. Graphite particles in gray cast iron have the shape of lamellae and are connected to each other. The specific combination of properties of gray cast iron, which is satisfactory for many applications, and simple and cheap production are the main reasons for its very wide application. For many years, gray cast iron has been the most used material for making metal castings. In this paper, there are microstructure tests for different variations of alloying gray cast iron with chromium, molybdenum, and copper. The assumption is that these elements influence the formation of pearlite in the microstructure, in different combinations. [ABSTRACT FROM AUTHOR]

Steel cooling is an important technological operation because the final microstructure of the steel, and therefore its properties, depends on the cooling rate. The speed of steel cooling depends on numerous factors, one of which is the movement of the cooling media. This paper presents the results of testing the influence of mixing the cooling media on the microstructure and hardness of 23MnB4 steel. Two media that are usually used for quenching steel (water and oil) were used for the test. The samples were cooled in an unstirred media and in a stirred media with three different stirring speeds (500, 750, and 1000 rpm). The results showed that mixing the media has an influence on the microstructure and hardness of steel. Samples that were cooled in a mixed medium had a higher hardness. The mixing speed had a greater influence on the hardness in the case of cooling in water. The microstructure after cooling in the water and oil was martensite-bainite. With an increasing cooling rate, the ratio of martensite in microstructure increases. [ABSTRACT FROM AUTHOR]

Austempered ductile iron is the last addition to the group of ductile irons obtained by isothermal improvement of classic ductile iron. Austempered nodular cast iron has improved mechanical properties and a different matrix microstructure compared to known iron-based castings. This type of casting is obtained by isothermal improvement - austempering, whereby the resulting microstructure consists of a mixture of ausferitic (acicular) ferrite and residual, isothermally transformed, carbon-enriched, stable, austenite. Changing the austempering parameters (temperature and time of austenitization and isothermal transformation) affects the obtained ausferite microstructure, and thus the mechanical properties. The most influential parameter that affects the mechanical properties of austempered ductile iron is the isothermal transformation temperature. This paper will present the relationship between microhardness values and microstructural transformations in the material due to the effect of elevated temperatures. [ABSTRACT FROM AUTHOR]

The production of titanium is very expensive, so it is interesting to research technologies that require lower costs, such as the HDH hydrogenation-dehydrogenation process technology, which is used for cheaper powder production from the waste material of titanium alloys. This paper presents the hydrogenation procedure of a recycled piece of the Ti6Al7Nb titanium alloy. Hydrogenation was carried out in a furnace for heat treatment at about 700oC in a hydrogen atmosphere. After hydrogenation, samples of the Ti-Al-Nb type alloy were mechanically crushed by the grinding process to a granulation below 120 μm. [ABSTRACT FROM AUTHOR]

Mine development imposes very high technical requirements of the mine hoisting equipment in terms of speed of transport. To meet these requirements it is necessary to properly design the structural elements of mine hoisting equipment which means that they must have the proper characteristics of the materials from which they are made such as mechanical properties. The suspension lever is an important fixing part of mining installations export container. Since the suspension levers are exposed to dynamic loads during operation, one of the most important test is a determination of their dynamical strength. This paper presents the determination of the dynamic strength of a new suspension lever and a suspension lever that has been in use for several years. Based on these parameters further working life of the suspension lever can be determined in order to increase the safety of the entire plant. [ABSTRACT FROM AUTHOR]

In this paper, we have introduced new contemporary materials for heat harvesting, based on thermoelectric effect (or Seebeck effect): rear earth mono-pnictides and graphene. Measure of effectiveness for transformation of heat to electricity is represented with zT factor, which measure heat harvesting potential. zT factor is related with heat and electric conductivity coefficients. For better understanding of these processes, it is necessary to comprehend all mechanisms of electron and phonon scattering in thermoelectric materials. Theory of electron and hole (or carriers) scattering was introduced trough modified Boltzman transport equation, and theory predicted results are in a good agreement with experimental data. [ABSTRACT FROM AUTHOR]

Some specific aspects in positioning of the re/heating furnaces at a layout of the modern rolling mills are presented in this paper. Theoretical and practical solutions in the above mentioned (further a.m.) field are presented for both, wire rod and light section bar mills. Some of the a.m. aspects are explained, confirming that even unexpected solution, from the theoretical point of view, could be successful and justified in practice, especially if some improvements are needed to be carried out on an existing layout of the concerned rolling mill, or in a vicinity of the other vital facilities on that rolling mill, or on the neighboring facilities. [ABSTRACT FROM AUTHOR]

Some specific aspects in positioning of the re-heating furnaces at a layout of different rolling mills, for a period of about last hundred years in rolling mills practice are presented in this paper. Practical solutions in the above mentioned (a.m.) field are presented for the different rolling mills. Some of the a.m. aspects are explained, confirming that both, the type of a rolling mill and the economic aspect are dominant in planning and carrying out the construction of an optimal rolling mill layout, in regard to the position of the re-heating furnace and the other rolling mill facilities. [ABSTRACT FROM AUTHOR]

In modern times, the science of materials cannot be imagined without metallography. The history of metallographic testing in Bosnia and Herzegovina is primarily related to Zenica. Today, most of the research related to the metal industry in BiH is conducted in laboratories at the Kemal Kapetanović Institute in Zenica. The Institute's Metallographic Laboratory has a history to be proud of and a future to nurture. This paper will review the capabilities of the Institute's Metallographic Laboratory 30 years ago and now. [ABSTRACT FROM AUTHOR]

This paper is concerned with carburization heat treatment. Standard carburization generally entails several steps: carburization of the surface layer by carbon diffusion at high temperatures, subsequent hardening and stress relief. This combination of hard surface and resistance to breakage upon impact is useful in parts such as a cam or ring gear, bearings or shafts, turbine applications, and automotive components that must have a very hard surface to resist wear, along with a tough interior to resist the impact that occurs during operation. This paper present carburization in solid done on two low alloyed steels: 17CrNiMo6 and 20CrMo5 and their properties obtained after carburization. [ABSTRACT FROM AUTHOR]

Austempered Ductile Iron (ADI) is obtained by exactly controlled heat treatment process of nodular cast iron. Ductile iron samples are first austenitised to dissolve carbon, then quenched rapidly to the austempering temperature to avoid the formation of deleterious pearlite or martensite. Resulting ausferrite microstructure consists of acicular ferrite embedded in stabile retained austenite. A new microstructure results with capability superior to many traditional, high performance, ferrous and aluminum alloys. Influence of heating rate on stability during working life of ADI casting, using thermal analysis (DTA), is presented in this paper. [ABSTRACT FROM AUTHOR]

Non-metallic inclusions usually deteriorate mechanical properties and surface quality of steel products. Presence of non-metallic inclusions might have negative affected some of the mechanical properties of steels like ductility, toughness, anisotropy, and formability. Macroscopic method for assessing the content of non-metallic inclusions in forged or rolled steel products is used for determination non-metallic inclusions visible to the naked eye or with aid of a magnifying with magnification of not more than 10 times. Only inclusions equal to or greater than 1 mm long are taken into consideration. In this paper is given procedure for blue fracture test method applied on bar diameter ϕ 60 mm bearing steel 100Cr6. [ABSTRACT FROM AUTHOR]

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The precipitation of sigma (σ) phase in austenitic stainless steels is a significant subject of many investigations. Exposure of these steels to elevated temperatures (from 600 °C to 900 °C) results in precipitation of σ phase (transformation product from delta (δ) ferrite) which is one of the main reasons for the deterioration austenitic stainless steels properties. It is therefore of considerable interest to study the conditions for σ phase formation, as well as the mechanism of the transformation. This review paper presents overview of precipitation characteristics (including morphologies and precipitation sites) as well as effect of σ phase on properties of austenitic stainless steels. It is particularly highlighted that the precipitation of hard, brittle and nonmagnetic σ phase occurring preferentially at δ/γ phase boundary and within δ ferrite islands (high Cr concentrated region) cause worse mechanical properties (impact toughness and elongation) and corrosion resistance. [ABSTRACT FROM AUTHOR]

In this paper, the results of changes in pH and conductivity values of the solutions during the rinsing of the adsorbent, as well as during the adsorption of copper ions were presented. Prior to the adsorption experiments, the sunflower heads were rinsed with 200 cm³ of distilled water in ten equal portions (20 cm³ each). After each water volume passes through the layer of the adsorbent, the pH and conductivity value of filtrate was measured. After the rinsing, the same adsorbent was then used for the adsorption experiments. As an aqueous phase, synthetic solutions of Cu2+ ions were used, with an initial concentration of 0.2 g dm-3. The obtained results show that from the beginning of rinsing the adsorbent, the pH value of rinsed water increases, reaching a constant value after passing 100 cm³ of water, and remains constant with further rinsing. It is assumed that an increase in pH value, during rinsing, occurs due to a transfer of H+ ions from the aqueous phase to the molecular structure of adsorbent to be exchanged there with alkali and alkaline earth metal ions. As for conductivity change during the rinsing of the adsorbent, it can be seen thata sudden increase in the aqueous phase conductivity occurs just after the first two portions of water passed through a bed of the adsorbent, reaching the peak around the volume of 0.05 dm³, it drops down rapidly. After V > 0.05 dm³ the conductivity of leachate continues to decrease but now more and more slowly, tending to achieve the initial conductivity of distilled water used for rinsing. This increase in the conductivity of the rinsed solution occurs most likely due to increasing in the concentration of alkali and alkalineearth metal ions in the solution, which are being transferred from the structure of the adsorbent into the solution during the rinsing. With further rinsing, the conductivity decreases, as a result of the decrease in the concentration of alkali and alkaline earth metal ions in the solution due to the dilution of the solution. During the adsorption of copper ions, quite a different behavior in changing of the pH and conductivity value in relation to the pH and conductivity change when rinsing the adsorbent with distilled waterwas noticed. The pH value rapidly drops downat the very beginning of the process, reaching a constant value in the next 30 minutes, and remains unchangeable with further process time.A very quick decrease in the initial pH occurs due to the releasing of H+ ions in the aqueous phase as a result of the deprotonation of functional groups existing in the molecular structure of adsorbent, where they are exchanged with copper ions. As for change of the conductivity of the solution, during the adsorption of copper ions, it can be seen that conductivity increasesat the very beginning of the process, reaching a constant value after 30 minutes. This increase can be attributed to the increase in the concentration of alkali and alkalineearth metal ions in the solution, which are exchanged with copper ions during the adsorption process. [ABSTRACT FROM AUTHOR]

In this paper, the influence of Na2SiO3/NaOH ratio on the compressive strength of fly ash - based geopolymers was tested. The fly ash from thermal power plant Stanari near Doboj, BiH is used. The ratio of alkali activator to fly ash (AA / FA ratio) was constant in all samples and it was 0.8. A 12M NaOH solution was used. The heat treatment temperatures of the samples were 60, 70 and 80 °C. The samples are made of fly ash and alkali activators, without the addition of aggregates, so they are geopolymer pastes. The compressive strengths after 1, 7 and 28 days from the thermal treatmentwere tested. The obtained values of compressive strengths, especially after 1 and 7 days, are far above the compressive strengths of cement. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation into the effect of nanosilica addition to porosity and capillary absorption of concrete. Three concrete mixtures 0%, 2%, and 4% nanosilicaby weight of cementweretested. The procedure described in ASTM C642-06 was used to determine the total volume of permeable voids. Water absorption and the rate of water absorption (sorptivity) was tested in accordance with ASTM C1585-13. The initial and secondary rate of absorption was calculated for each mix. Also, concrete compressive strength at 28 days was determined. Testresults indicated that the incorporation of nanosilicainconcrete resulted inadecreased volume of permeable voids, total water absorption and rate of water absorption, and increased compressive strength at 28 days. [ABSTRACT FROM AUTHOR]

The paper examined the changes in properties of conventional castables composed of a mixture of calcium-aluminate cement and chamotte caused by changes in the particle size distribution. Properties of castable with 20 % cement and „as received" chamotte were compared with castableofparticle size distribution adapted to the calculated distribution using the Andreasen equation. Porosity, water absorption, density and strength of samplesafter three-day curing and samples fired at 1100 °C were examined. It was found that samples with adjustedparticle size distribution gave better results than those prepared with „as received" particle size distribution, especially regarding strength. [ABSTRACT FROM AUTHOR]

The HK30Nb steel pipe casting was obtained by centrifugal casting. This steel is austenitic stainless steel grade AISI HK 30 and is standardized according to ASME SA-351 in as cast condition. HK 30 Nb steels not standardized i.e. it is HK 30 steel modified with niobium. In addition to the required mechanical properties, this steel is also tested for heat resistance because it is used at high temperatures. In this paper, the heat resistance testing was carried out on the HK 30 Nb stainless steel pipe casting for two temperatures (750 and 850 °C) according to the standard ASTM G 54-84. The mass change and rate of oxidation for different heating times (24, 48, 72, 96 and 120 hours) were determined. The results of the study are significant for the continued use of these materials at high temperatures in exploitation conditions. [ABSTRACT FROM AUTHOR]

In this paper were investigated the effect of hydrochloric acid concentration and addition of oxidizing agents on the rate of general corrosion of copper. For comparison, the corrosion rate in distilled water was also tested. Taffel extrapolation method was used for investigation of general corrosion of copper. Taffel extrapolation method implies scanning of working electrode potential on the order of ± 250 mV in relation to its Open Circuit Potential (EOCP), at the speed of 0.5 mVs-1.Investigations of corrosion were conducted in the corrosion cell according to Standard ASTM G5[5], on instrument potentiostat/galvanostat, Princeton Applied Research, model 263A-2, with the software PowerCORR®. Tests were performed at room temperature, 20 ± 1 °C. [ABSTRACT FROM AUTHOR]

The chemical composition of casting is an important factor affecting the shape of graphite and the mechanical properties and microstructure of the metal base. Different elements have different influence to casting properties. All elements that affect the microstructure development during casting solidification have significant influence on mechanical properties of the castings. In the practical part of this paper influence of molybdenum and chromium on the change in hardness and pearlite content in the microstructure is presented. The results show that with the addition of pearlitizing elements (Cr and Mo), the content of pearlite in the microstructure of the metallic matrix and hardness of the castings increase. [ABSTRACT FROM AUTHOR]